Category: hydroponic agriculture

American elderflower appears to contain a different chlorogenic acid isomer than the European elderflower, which has mainly neochlorogenic acid. Furthermore, 12 cultivars were sampled for the study, which showed high variability in concentration of the two compounds measured. Rutin concentrations ranged from 4637 to 8111 mg kg-1 while chlorogenic acid concentrations ranged from 1180 to 3064 mg kg-1 , showing that key phenolic compounds can be more than double in some cultivars. The concentration of these two compounds did not appear correlated, as the correlation coefficient was only 0.018.While there have been several studies measuring the CG content in elderberries of different subspecies, the data available on elderflower CG content is limited. In fact, only one study has published data on this area to date and it focused on European elderflowers. A study comparing growing locations at multiple altitude levels to determine impact on phenolic compounds and cyanogenic glycosides found that CG concentrations in elderflowers ranged from 1.23 ug g-1 to 18.88 ug g-1 , generally increasing as thealtitude increases. 6 Sambunigrin was the only CG measured and compared to the berries of the same plants in this study, elderflowers contained more CGs than elderberries. Elderflowers from the American subspecies nor the blue subspecies have been analyzed for their CG content. As consumer concern for this toxic group of compounds remains high, it would increase confidence of consumers to utilize the elderflowers of these other subspecies if data was available on the CG concentrations of these flowers.Elderflowers and elderflower products have been investigated for their volatile profile. A direct comparison is difficult to make from the syrups, danish trolley which have other ingredients like sugar or lemons, to the plain flower extracts, but due to the high popularity of elderflower syrups, the results of those studies are included here as well.

In studies of the European elderflower without any additional food ingredients, linalool and linalool derivates, such as -linalool pyranoxide and cis-linalool oxide, have frequently been identified as prominent. The aroma of linalool, the main aroma compound in lavender, can be described as citrus, fruity, floral, and woody. The age of the flower when harvested as well as how the flowers are stored after harvest can greatly impact the volatile profile. As expected from the other data on inter-cultivar variation, the volatile profile is heavily influenced by the cultivar. For example, wild elderflower had twice as much rose oxide and more linalool oxide than the other 12 cultivars. While this could be a challenge for manufacturers that use elderflower in products to have a consistent aroma from batch to batch, it also allows for more selectivity to find a cultivar that matches desired organolepticproperties in the product. American elderflowers have not yet been evaluated for their volatile profile, nor have blue elderflowers.Elderberry and elderflower are becoming more common ingredients and flavoring agents in beverages and food products. However, a vast majority of the products on the market today utilize the European subspecies of this plant due its more established cultivation and a deeper understand of the composition, particularly the phenolic profile, of the fruit and flower. North American subspecies, the American elderberry S. nigra ssp. canadensis and the blue elderberry S. nigra ssp. cerulea, have some information available regarding composition, but further analyses are needed to understand how they may perform in the common applications that European elderberry and elderflower are used in today.As global warming and water scarcity issues continue to impact food systems, fire-resilient and drought-tolerant plants will become more important for supplying nutrient-rich foods. Wildfires throughout the western United States are becoming more common and more serious as seasons are hotter and drier. California has been experiencing unprecedented levels of wildfires, including over 1.9 million acres burned in 2018, over 4.2 million acres burned in 2020, and over 2.5 million acres in 2021.

One native and fire-resilient plant is the blue elderberry , which grows wild throughout the western United States and has become a popular choice to grow in hedgerows. The blue elderberry is drought-tolerant, and the roots of the blue elderberry can survive fires to regrow the next season to continue providing valuable flowers and fruit , making it an ideal choice to plant in regions of California and American West often stricken by wildfires. While European and American elderberries have been studied for decades, there is currently little information on the subspecies native to the western region of North America, S. nigra ssp. cerulea , known as blue elderberry due to a white-colored bloom on the exterior of the berry which makes it appear blue. In California, it grows wild in riparian ecosystems near rivers and streams 86 , but is also planted in hedgerows on farms to improve water, air, and soil quality, in addition to providing a habitat for birds, pollinators, and other beneficial insects. The plant can grow several meters tall and wide and flowers from May to August, with peak fruit ripening throughout July and August. While elderberry prefer moist soil and some hedgerows may receive some irrigation during the summer months, most are not irrigated once the hedgerow has been established, about 2-4 years . That is one of the benefits of using native and drought-tolerant plants, as they can better withstand the natural climate without excess resources. Elderberries have a long history of use by Native Americans and Europeans in foods, beverages, and herbal medicines. Research exploring links between elderberry consumption and health has increased dramatically, particularly in the past decade. Numerous in vitro and in vivo studies demonstrate that elderberries have potent antioxidant, antibacterial, and antiviral properties. Results of two randomized, double-blind, placebo-controlled clinical trials suggest that elderberry supplements reduce the duration and severity of cold symptoms. Roscheck et al. identified two non-anthocyanin flavonoids in elderberry extract that inhibited viral ability to infect host cells when bound. While most bio-activity of elderberries is assumed to result from the phenolic compounds like anthocyanins, the high-molecular weight fraction of concentrated elderberry juice was found to contain acidic polysaccharides that had potent effects against the human influenza virus. The health-promoting properties of elderberry have led to recent increases in its use in products such as supplements, syrups, gummies, and teas, as well as wine and jams.

During the COVID-19 pandemic, elderberry supplements gained wide attention because of potential anti-viral activities; however, there is no strong clinical evidence that elderberry could be beneficial in preventing or treating COVID-19. The market for elderberries is expected to continue to increase, as the sales of herbal dietary supplements was over $11 billion in 2020, a 17.3% increase from 2019. Elderberry was the top selling herbal supplement, with sales over $275 million, as consumers became more interested with supporting their immune systems 9 . In addition to the interest in elderberry as an ingredient in functional foods, elderberry can be an excellent source of natural coloring agents for food and beverage applications due to the high content of red and purple anthocyanins.Characterization of the chemical composition, functional properties, and impact of processing on the bioactive compounds in elderberry is largely limited to S. nigra ssp. nigra and, to a lesser extent, S. nigra ssp. canadensis. S. nigra ssp. nigra is commonly referred to as the European black elderberry, which has many established cultivars, such as “Haschberg” and “Samyl”, vertical aeroponic tower garden and it has an established market. The European elderberry is the most frequently used subspecies in commercial elderberry-based products and has been extensively studied for its composition, anthocyanin stability, and health benefits in European black elderberry-based products . S. nigra ssp. canadensis is commonly referred to as the American elderberry, a subspecies native to the eastern and central regions of North America. There are several cultivars of the American elderberry, including “Johns” and “Bob Gordon”. The American elderberry, which is utilized in small-batch products, has also been evaluated for its composition and health-promoting properties . The acreage grown of this subspecies has been increasing rapidly and there is a goal to grow over 2,000 acres by 2025, according to the Midwest Elderberry Cooperative. Currently, there is no information on the chemical composition of the fruit of the blue elderberry . With the recent increase in demand for elderberry, blue elderberry grown in hedgerows may be an additional and valuable source of bio-active phenolics and natural colorants. The objective of this study was to determine the moisture content, soluble solids, pH, titratable acidity, and establish the anthocyanin and phenolic profiles of blue elderberries grown in Northern California to support the use of this robust, native crop in commercial products.Hedgerows of S. nigra ssp. cerulea were identified on five farms near Davis, California in Spring 2018 with the assistance of an experienced agronomist at The Cloverleaf Farm . Farm, hedgerow, and harvest information is presented in Table 1. Blue elderberries were determined to be ripe when the berries in a cyme were deep purple, with or without the white bloom, and had no green berries present. Ripe elderberries were harvested by hand from all four quadrants of the elderberry shrub, totaling approximately 3 kg of elderberries. The berries were placed in clear plastic bags, stored on ice, and transported to the laboratory. A subsample was separated for moisture analysis, while the rest was de-stemmed and stored at -20 °C until analyzed.Elderberries were extracted by combining 5 g frozen berries with 25 mL MeOH:formic acid in a conical tube. The contents were homogenized, placed in a shaker without water at speed 7.5 for 20 min, then centrifuged at 3,000 rpm for 7 min. The supernatant was transferred to a 15 mL plastic tube and stored at -80 °C for no more than two weeks prior to analysis. Duplicate extracts were made from each shrub. TPC was determined using the Folin-Ciocalteu method. First, elderberry phenolic extract was diluted 1:4 with water. Each extract was analyzed in duplicate and averaged. In 10 mL glass tubes, 6 mL water was combined with 100 µL sample and 500 µL Folin-Ciocalteu reagent. After mixing and incubating for 8 min at room temperature, 1.5 mL 20% aqueous sodium carbonate was added. The tubes were mixed, covered with foil to avoid light exposure, placed in a water bath at 40 °C for 40 min, then cooled at room temperature for 15 min. The samples were read by a UV visible spectrophotometer at 765 nm and quantified using an external standard curve prepared with gallic acid . TPC is expressed as mg gallic acid equivalents per 100 g FW.Five grams of frozen berries were mixed with 25 mL of in a conical tube, which was then homogenized for 1 min at 7,000 rpm . The mixture was stored at 4 °C overnight, then in the morning, centrifuged at 4,000 rpm for 7 min. The supernatant was used directly for analysis. Three pooled samples were made for each hedgerow, each consisting of even amounts of berries from three distinct shrubs. Eachpooled sample was extracted once to give 3 biological replicates, and each extract was run in duplicate . The concentration of phenolic compounds in blue elderberry followed the method by Giardello et al. with some modifications. Briefly, samples were analyzed via reversed-phase liquid chromatography on an Agilent 1200 with a diode array detector and fluorescence detector . The column used was a PLRP-S 100A 3 µm 150 x 4.6 mm at 35 °C, and the injection volume was 10.0 µl. Mobile phase A was water with 1.5 % phosphoric acid, while mobile phase B was 80%/20% acetonitrile/ mobile phase A. The gradient used was 0 min 6% B, 73 to 83 min 31% B, 90 to 105 min 6% B. The DAD was used to monitor hydroxybenzoic acids at 280 nm, hydroxycinnamic acids at 320 nm, flavonols at 360 nm, and anthocyanins at 520 nm. The FLD was used to monitor flavan-3-ols, with excitation at 230 nm and emission at 321 nm. External calibration curves were prepared using chlorogenic acid for phenolic acids, rutin for flavonols, and cyanidin-3-glucoside for anthocyanins , at the following concentrations: 200, 150, 100, 75, 50, 25, 10, 5, and 2.5 mg/L. Catechin was used to quantify flavan-3-ols and standards were run at 150, 100, 75, 50, 25, 10, 5, 2.5, and 1 mg/L.

During the experiment conducted in the 2019 growing season, the kaempferol proportion increased in LR and ST treatments, but largest increase was measured when ST and LR were applied concurrently. Likewise, the higher the degree of exposure degree a greater kaempferol accumulation was observed during the 2017 growing season. The increase in kaempferol in total proportion of flavonols was accompanied with a concomitant decrease of quercetin and myricetin proportions. These results are corroborated with our previous work performed on Merlot and Cabernet Sauvignon., and by others on Cabernet Sauvignon, Nero d’Avola, Raboso Piave, and Sangiovese in Italy . We previously reported the proportion of kaempferol was a feasible tool for accounting the solar radiation received by berry due to the greater canopy porosity and this corresponded to the 1930 W·m−2 of global radiation accumulated at the research site in Experiment 3. On the other hand, the higher proportion of quercetin derivatives in detriment of myricetin derivatives found in LR vines has been related to down regulation of F3’5’H family genes . Previous work on red grapevine berries, indicated that IBMP content decreased with greater solar exposure due to the canopy management practices during berry ripening . In our work, the lowest IBMP content was measured in LRST berries. Our results indicated a negative and linear relationship between leaf to fruit ratio and IBMP content. Conversely, blueberry grow pot the relationship between kaempferol proportion and IBMP was not significant.

Therefore, our data suggested that the decrease of IBMP content was better explained by changes in the source-sink balance rather than differences in solar exposure. Likewise, Koch et al. provided evidence that solar exposure affected IBMP content to a greater extent when canopy porosity was enhanced before fruit set and not during berry ripening corroborating our results. The lower berry IBMP content was explained by a diminution of the accumulation rates rather than increased rates of degradation due to canopy management practices and restriction of applied water between fruit set and veraison in a warm climate.The total operating costs per hectare of a Cabernet Sauvignon vineyard in Napa County, CA U.S.A. is approximately US$ 40,382 . The labor operations costs of canopy management practices per hectare are 25% of the total costs. Our data indicated that although some berry traits were improved by the removal of shoots and leaves or the more common practice of doing them concurrently, their profitability is not ensured in warm climates. The unit cost to produce one unit of anthocyanin increased by about 10-fold with the additional canopy management practices. Therefore, the unfavorable leaf area to fruit ratios increased the cost of producing anthocyanins as previously reported by Cook et al. in Merlot grapevine grown in a warm climate. Likewise, the diminution of accumulation rates of IBMP were not as economically effective as once thought due to loss in yield and reduction in gross income per hectare for the grower. Finally, the breaking points determined through segmented regression analysis indicated that although increases in solar exposure led to significant IBMP content decreases , however, we were unable to elucidate this effect on anthocyanin content .

Since the effect of canopy management practices lead to higher solar exposure in hot climates that might be deleterious on grape quality, we aimed to elucidate the thresholds for maintaining anthocyanin content, while waiting for the target TSS required for fermentations and green aroma removal without compromising the yield. Although increasing canopy porosity through canopy management practices can be helpful for other purposes such as pest protection, this may not be the case of flavonoid compounds when a certain proportion of kaempferol is attained. Our data from these trials revealed different sensitivities to degradation within the flavonoid groups, flavonols being the only monitored compounds that were upregulated by solar radiation. Anthocyanin depletion was observed in all the trials with increasing solar radiation exposure . Under our experimental conditions, ST and LRST hastened fruit maturity; however, a clear improvement of the flavonoid compounds was not observed at harvest. On the other hand, all the canopy management practices studied decreased IBMP from mid-ripening to harvest. Therefore, although some berry traits were improved due to canopy management practices , this came with costs of labor and yield and gross income reduction that decreased flavonoid productivity per hectare; and these all should be assessed together when taking the decision to apply these treatments in hot climates.Grapes are profitable fruit crop that are widely grown in the state of California, with an increasing need to accomplish cultural tasks mechanically , 2020; Kurtural and Fidelibus, 2021. However, there are many factors that are currently challenging the productivity, quality, and sustainability in wine grape vineyards, one being the increasingly significant global warming trend affecting California and the whole world , where more frequent heat waves and continued warming of air temperature imposes great threats to vineyard yield, berry and wine composition .

Grape berry and wine quality are determined by the composition and concentration of secondary metabolites accumulated in berries. Flavonoids are the most abundant secondary metabolites and contribute to many quality determining traits, including color, mouthfeel, and aging potential of wine . There are generally three classes of flavonoids in wine grapes, including anthocyanins, flavonols, and proanthocyanidins. Anthocyanins are responsible for grape berry and wine color, and they are sensitive to external environmental conditions when clusters are exposed to solar radiation and heat, with overexposure resulting in anthocyanin degradation . On the other hand, flavonols tend to be positively related to solar radiation . Solar radiation, especially UV-B, can often up-regulate flavonols’ biosynthesis, resulting in more flavonols accumulated in berry skins. However, excessive solar radiation received and heat accumulated in California would accelerate the degradation of not only anthocyanins, but also flavonols, which will cause a decline in the antioxidant capacity of resultant wine and a possible reduction in wine aging potential . In viticulture, trellis system selection is a critical aspect grower needs to consider when establishing a vineyard. An ideal trellis can promote grapevines’ photosynthetic capacity through optimizing light interception by the grapevine canopy. Most importantly, a suitable trellis can optimize canopy microclimate by providing sufficient solar penetration into canopies since solar radiation is necessary to enhance the berry composition without excessive exposure of clusters to direct sunlight to avoid flavonoid degradation . There is evidence that grape clusters over-exposed to solar radiation are prone to occur with some of the widely used trellis systems. For example, vertical shoot position , a traditional and commonly used trellis system in viticulture production, has been found to produce canopies with high porosity which increases vulnerability of clusters to over-exposure , causing overly enhanced maturity and considerable degradation in berry anthocyanins . However, square plastic pot there is a lack of evaluations of the performance among various trellis systems in relation to the warming climate trends, and how their specific architectures contribute to variations in berry chemical profiles. In warm climates such as California, viticulture relies on irrigation for maintaining production, and previous work in the area showed that the application of different amounts of crop evapotranspiration can significantly modify polyphenolic and aromatic profiles in wine . Due to the increasingly frequent drought condition in many wine grape growing regions, recent studies have been focusing on the grapevine physiological and berry chemical responses towards specific levels of water deficits imposed by different ETc replacements, where water deficits are affective in manipulating grapevine water status, leaf gas exchange, components of yield, and berry composition: often, more water deficits applied to the grapevines would diminish photosynthetic capacities, but promote berry maturity . In some extremely drought conditions, however, severe water deficit might lower flavonoid concentration due to encouraged chemical degradation . Moreover, these effects resulted from different irrigation regimes can be modified by the canopy architecture as functions of trellis system since trellis systems can directly determine canopy sizes, hence resulting in different water demands from grapevines accordingly . On the other hand, over extraction of ground water to irrigate permanent crops have recently been questioned and legislation has been enacted in the state of California called the ‘Sustainable Groundwater Management Act’ . As a result, in some regions such as Napa Valley of California, grape growers will only be allowed to irrigate 120 mm per year. However, there is a lack of information on how the existing vineyards will cope with this water limitation in terms of irrigation scheduling. Therefore, the objectives of this study were to evaluate and compare 6 different trellis systems in combination with 3 irrigation strategies to understand the impact of trellis system and applied water amount on canopy architecture, grapevine physiology and berry composition. We hypothesized that traditional VSP systems would not be as efficient as the other trellis systems in terms of yield production and flavonoid accumulation, leading to greater berry flavonoid degradation and overall lower flavonoid concentrations.

The second subset of 20 berries was used for the determination of skin flavonoids from each individual treatment-replicate. Skins were manually removed from the subset of 20 berries and subsequently lyophilized . After lyophilization, dry skin weights were recorded and then, the dried skins were ground into fine powder with a mixing mill . 50 mg of the freeze-dried berry skin powder were collected, and the skin flavonoids were extracted with 1 mL of methanol:water:7M hydrochloric acid to simultaneously determine flavonol and anthocyanin concentration and profile as previously described by MartınezLüscher et al. . The extracts were stored overnight in a refrigerator at 4°C. In the next day, the extracts were centrifuged at 30,000 g for 15 minutes, and the supernatants were separated from the solids and transferred into HPLC vials after being filtered by PTFE membrane filters . Then, the samples were injected into HPLC for chromatographic analysis.Anthocyanin and flavonol concentrations in berry skin tissues were analyzed with a reversed-phase HPLC with the use of two mobile phases: 5.5% formic acid in water and 5.5% formic acid in acetonitrile. The specific method used for this study required a C18 reversed-phase HPLC column for the analysis . The flow rate of the mobile phase was 0.5 mL min- 1 and the flow gradient started with 91.5% A with 8.5% B, 87% A with 13% B at 25 min, 82% A with 18% B at 35 min, 62% A with 38% B at 70 min, 50% A with 50% B at 70.01 min, 30% A with 70% B at 75 min, 91.5% A with 8.5% B from 75.01 min to 90 min. The column temperature was maintained at 25°C on both left and right sides of the column. All chromatographic solvents were of high-performance liquid chromatography grade, including acetonitrile, methanol, hydrochloric acid, formic acid. These solvents were purchased from Thermo-Fisher Scientific . Detection of flavonols and anthocyanins was recorded by the diode array detector at 365 and 520 nm, respectively. Investigated anthocyanin derivatives included di-hydroxylated forms: cyanidin and peonidin, and trihydroxylated forms: delphinidin, petunidin, and malvidin; investigated flavonols included a mono-hydroxylated form: kaempferol, di-hydroxylated forms: quercetin and isorhamnetin, and tri-hydroxylated forms: myricetin, laricitin, and syrigintin. Post-run chromatographic analysis was conducted with Agilent OpenLAB software and identification of individual anthocyanins and flavonols was made by comparison of the commercial standard retention times found in the literature . Myricetin-3-O-glucuronide, myricetin 3-O-glucoside, quercetin 3-O-glucuronide, quercetin 3-O-galactoside, quercetin 3-O-glucoside, kaempferol 3-O-glucoside, isorhamnetin 3-Oglucoside, and syringetin 3-O-glucoside used for flavonol identification were purchased from Sigma-Aldrich . Flavonol molar abundant was calculated as the percentage of specific flavonol derivatives’ concentration over total flavonols’ concentration.The statistical analysis for the experiment was performed using MIXED procedure of SAS . All the datasets were first checked for normal distribution using a Shapiro-Wilkinson test before running the two-way MIXED procedure. A Tukey’s HSD post-hoc test was performed to analyze the degree of significance among the various measurements. The levels of significance ≤ 0.10 were the results that were considered for the Tukey’s post hoc tests. Season-long measurements of leaf gas exchange variables were analyzed for each year via three-way Analysis of Variance using the MIXED procedure of SAS using REPEATED option for measurement dates. A regression analyses was performed between variables of interest and, p values were acquired to present the significances of the linear fittings, as well as the regression coefficient .Both seasons were considerably arid as the experimental site only received 233.9 mm and 276.9 mm of precipitation from the previous dormant season until harvest in 2020 and 2021, respectively .

The glucose and insulin responses after mango intake were also moderated, compared to ingesting of an isocaloric amount of white bread. While the effects of mango intake on microvascular function were not as significant as the response from other whole foods, other measures of cardiovascular health, as well as glucoregulatory benefits, warrant further study.Epidemiological studies suggest that diets rich in carotenoids can be beneficial for vision, heart, bone health, cognitive performance, and cancer prevention. The current review focuses on the potential role of the xanthophyll carotenoids lutein and zeaxanthin in eye health, specifically their potential role in reducing risk of age-related macular degeneration . We review the absorption, distribution, and metabolism of L and Z, and the current dietary recommendations for these carotenoids, then speculate about their putative role in maternal and infant health. Lastly, we discuss the potential value of goji berry within the diet as a food with the highest known amount of Z. Carotenoids contribute to the bright red, orange, and yellow color in plants. These fat-soluble phytochemicals are classified into two categories: carotenes, dutch buckets system which include only hydrocarbons, and xanthophylls that also contain oxygen. While some dietary carotenoids serve as vitamin A precursors most of the approximately 100 carotenoids found in plants do not. Among the carotenoids devoid of vitamin A activity are L and Z, along with meso-zeaxanthin , a stereoisomeric metabolite of L.

Absorption involves enterocyte uptake by CD36, scavenger receptor class B type I , and Niemann-Pick C1-like transporter 1 at the apical membrane. Xanthophylls are then secreted through the basolateral membrane of the enterocyte, mainly by ATP binding cassette A1 and carried by lipoproteins to target tissues. SR-B1, SR-B2, and CD36 transport L and Z into the tissues. Steroidogenic acute regulatory domain protein 3 has been identified as a binding protein for L in the retina, and glutathione S-transferase pi isoform for Z. Lutein, Z, and meso-Z impart a distinctive yellow color to the fovea of primates – the specialized central area of the macular region of the retina that is rich in cone photoreceptors and optimized for high-acuity central color vision. The compounds have a maximal absorbance at a wavelength near 460 nm and are most concentrated in the inner and outer plexiform layers, which consists primarily of axonal connections between the retinal layers. Their combined density is greatest in the center of the macula and decreases with increasing retinal eccentricity. In the central fovea, the concentration of Z and meso-Z is higher than L at a ratio of 2.4:1. Lutein is most abundant in the peripheral macula, with a Z + meso-Z to L ratio of 1:2 when measured by highperformance liquid charomatography. However, a newer technique, confocal resonance Raman microscopy suggests that the Z + meso-Z to L ratio is as high as 9:1 at the central fovea. Protection from blue light is critical for eye health. Compared to longer wavelengths of visible light, short blue wavelengths are higher in energy and generate reactive oxygen species .

Zeaxanthin can provide stronger oxidant defense than L during photooxidation, while lutein has a greater capacity to absorb short wavelength light irradiation in lipid membranes.20 Compared to other carotenoids , L and Z are more effective in scavenging ROS and can also reduce phospholipid peroxidation. The photoreceptor-retinal pigment epithelium complex in the outer retina is particularly susceptible to ROS damage due to its high polyunsaturated lipid content . Quenching of singlet oxygen appeared best when L, Z, and meso-Z were mixed in equal ratios rather than separately when assessed in an eye tissue model, suggesting some synergy between the these macular pigments in their antioxidant properties. The most common method to quantify xanthophylls in the retina is to assess macular pigment optical density . This parameter is measured through techniques such as heterochromatic flicker photometry , a non-invasive psychophysical technique, fundus reflectometry, resonance Raman spectroscopy, or autofluorescence imaging. The MPOD index is associated with plasma levels of L and Z, and has been used to assess the risk for AMD. However, some studies report no correlation between MPOD and risk of AMD, which suggests that other ocular measures may be useful to obtain a more complete profile of AMD risk. In human donor eyes, the amount of L and Z was inversely associated with AMD. Supplementation of L, Z, and meso-Z have been shown to significantly increase MPOD in both healthy individuals and patients diagnosed with AMD. However, studies using foods rich in L and Z have produced inconsistent results, which may be due to the relatively modest amounts of these carotenoids in foods compared to supplements. Importantly, the plasma concentration of L and Z has been more strongly associated with MPOD than the correlation between MPOD and dietary intake. 

Age-related macular degeneration is the third leading cause of blindness worldwide after uncorrected refractive errors and cataracts. An estimated 288 million people worldwide are projected to suffer from AMD by 2040. In the United States, the prevalence of early-stage AMD was 9.1 million in 2010, and this number is projected to increase to 17.8 million by 2050. AMD is characterized by a gradual loss of eyesight from the central visual field.40 Although the exact etiology of AMD is not clear, common pathologic progress includes oxidative stress, lipofuscin toxicity, lipid accumulation, immune dysregulation, and choroidal hyperperfusion. Age-related processes such as a decrease in retinal neuronal elements, alterations in the size and shape of RPE cells, and thickening of Bruch’s membrane alsoparticipate in the pathology of AMD. Damage to mitochondria in RPE cells has also been suggested to play a role. Dry AMD, also termed non-exudative AMD, involves the formation of drusen, which are mainly lipid and protein deposits that accumulate between the RPE and Bruch’s membrane in the macula. In contrast, wet AMD, also termed exudative or neovascular AMD, is a consequence of abnormal blood vessel formation arising from the choroid, known as choroidal neovascularization . Clinically, AMD is classified as early or intermediate stage based on the size and number of drusen, as well as presence of pigmentary changes.46 The AMD is considered late or advanced stage in the presence of CNV, where fluid accumulation may result in damage to the neurosensory retina and fibrous scarring, or geographic atrophy , where loss of the RPE result in damage to overlying photoreceptors and underlying choriocapillaris causing irreversible vision loss. The main risk factors for AMD are aging and smoking, although some studies have shown no difference in MPOD between healthy older individuals and healthy young. Other risk factors may include race, obesity, previous cataract surgery, presence of cardiovascular disease, and hypertension. According to the U.S. National Institutes of Health, the prevalence of AMD is highest among Caucasians as compared to other races, and higher in females than in males. Genetic factors are also associated with AMD, with several high-risk single-nucleotide polymorphisms identified from genome wide association studies. The strongest risk variants include the Y402H variant of complement factor H gene as well as those in the age-related maculopathy susceptibility 2 locus. Whether the color of the iris or sunlight exposure are related to the risk of AMD is still being explored. Dietary interventions using L- and Z-rich foods have generated inconsistent results regarding the risk of AMD. In a cohort study that assessed dietary carotenoid consumption among individuals without AMD at baseline over more than 20 years, increased predicted plasma carotenoid score of L, Z, β-carotene, α-carotene and β-cryptoxanthin were associated with a lower risk of advanced, but not early or intermediate AMD. Similarly, dutch buckets a meta-analysis of six longitudinal cohort studies found that the dietary intake of L and Z significantly reduced the risk of GA by 26% and CNV by 32%, with no apparent impact on early stages. Another metaanalysis concluded that supplementation with L, Z, and meso-Z significantly increased MPOD levels in both AMD patients and healthy individuals in a dose-response manner.70 However, whether the improvement in MPOD could be sustained after L and Z supplementation is discontinued remains unclear. The Age-Related Eye Disease Study was a multi-center study that assessed the efficacy of a dietary anti-oxidant supplements on subjects who are 50 to 80 years old, with and without AMD or cataracts, for more than seven years. The initial study used a formula containing 15 mg of β-carotene, 500 mg of vitamin C, 400 IU of vitamin E, with or without 80 mg of zinc and 2 mg of copper.

Lutein and Z were not included because the scientific evidence to include these two carotenoids was not yet clear. Compared to the placebo group, participants consuming the antioxidants plus zinc and copper showed a 28% reduction in progression to advanced AMD after five years. Subsequently, the AREDS2 was conducted with a newer formulation that included vitamins C and E, either 10 mg of L plus 2 mg of Z, and either 350 mg of docosahexaenoic acid plus 650 mg of eicosapentaenoic acid , or both. Patients were also given either 25 or 80 mg of zinc, each with 2 mg of copper. Beta-carotene was eliminated from the supplement due to a potential increased risk of lung cancer among smokers, who were already at high risk for AMD. Primary analyses of the AREDS2 formula found no additional benefit in reducing progression to advanced AMD, in comparison to the original AREDS formula. However, in a secondary analysis of combined data from AREDS and AREDS2, the progression risk in those receiving L and Z was significantly lower than in other groups. Neither formulation reduced the progression from early to intermediate AMD. These clinical trials did not monitor the MPOD status over time, thus limiting our understanding of the link between L and Z intake, retinal accumulation, and AMD development or progression. To date, the AREDS2 formula remains the standard of care for management of patients with intermediate AMD.The accumulation of L and Z in the macula starts in utero in primates and plays a critical role in visual development and maturation later in life. Lutein and Z were detected as early as 20 weeks of gestation in macular tissue from human fetuses inspected at autopsy.15 Unlike fully matured human eyes, L is the dominant macular pigment in infants under the age of two regardless of eccentricities. The retina is less mature at birth compared to other eye structures, with complete differentiation requiring four to five years. The maturation of the macula is associated with a change in the L:Z ratio over the first four years of life, which correlates with the development of cone photoreceptors. Studies in premature infants illustrate the importance of these L and Z in visual development. In preterm human neonates, extremely low levels of serum L and Z are associated with an undetectable MPOD.79 When a carotenoid-fortified formula containing 211 µg/L of combined L and Z was given to preterm infants, plasma carotenoid levels became comparable to breastfed preterm infants, and were significantly higher than those fed formulas without L or Z fortification. In a small study that monitored the concentration of L and Z in various infant formulas and breast milk from different mothers, Z was not detected in any formula but was present in all breast milk samples, while L was consistently higher in breast milk. Serum L was also noted to be six-fold higher in breastfed infants compared to those fed with a formula devoid of L. Further studies are warranted to assess the prospective effects of L- and Z-fortified formula on MPOD and visual development in infants as they enter adulthood. Lutein and Z may also protect against oxidative damage in premature infants, especially those with retinopathy of prematurity . Premature infants with ROP usually have poor visual acuity, even after laser treatment or intravitreal injection of anti-vascular endothelial growth factor agents. In a model of oxygen-induced retinopathy, mouse pups given L showed less vessel leakage and lower avascular area compared to those given a L-free control. The authors suggested that the anti-oxidant properties of L may have contributed to these results, although ROS levels were not measured. Studies that investigate L and Z supplementation in ROP babies have produced inconsistent results.

For test management, the Raspberry Pi handles another thread responsible for converting the dataset into EEG signals that are acquired by the ADC. To avoid data overlapping in the process of writing—DAC—and reading—ADC—the samples, a synchronization method is used between the two threads. Synchronization involves multiple threads efficiently waiting for each other to finish tasks. Specifically, the ADC thread waits to read the data until the DAC finishes writing the data, and the DAC waits to write new data until the ADC finishes reading the previous one. The ADC thread stores the read samples in a buffer, from which the classification thread reads them. Figure 8 illustrates the block diagram of the algorithm of the system software. As for the hardware design of this work, a proof of concept EEG-based real-time identification system using Raspberry Pi is demonstrated that integrates all the components needed for the practical use of a real subject identification system. The execution of the thread parallelism has been performed without any problem, and all the threads are synchronized to achieve their tasks without any errors. The MSE is low with respect to the range of the data conveying high similarity between the original dataset and the data generated by the DAC, which demonstrates the reliability of the results obtained during the model evaluation stage. Finally, Raspberry Pi provides portability and allows the system to be integrated into a network; hence, grow strawberry in containers the information is accessible from anywhere. We plan to develop a system for EEG acquisition and integrate it with the current Raspberry Pi-based system. The development of an acquisition system will eliminate the use of converter DAC and the need for a pre-stored dataset.

The motivation for developing our device comes from the comparison of the different commercially available products. The devices found were developed only for acquisition purposes or for more complex applications and most of them are very costly. For this reason, we are motivated to develop our own end-to-end, low-cost, real-time device involving EEG acquisition from minimum necessary channels for EEG biometrics, preprocessing, feature extraction, and subject identification. In the future, to improve our device, we will perform a deeper analysis of the hardware by studying the power and time consumption and alternative technology for minimization of cost and size of the device. The civilian use of autonomous craft for scientific as well as commercial purposes has grown significantly in the last few years. A 2018 report from the National Oceanic and Atmospheric Administration detailed the use of un-crewed systems, UxS1 , for the agency. The number of types of un-crewed aerial vehicles employed by the agency doubled in a one year period and the number of total vehicles deployed increased by 38% for the same year. Use of other UxS by the agency show a similar trend. In the same report they detail the use of UxS from space to the ocean floor and nearly every environment in between. UxS are also used to monitor dangerous environments. A New York Times article from 2021 demonstrated the use of a novel autonomous surface vessel that collected video imagery from within the eye of Hurricane Sam. There are examples in the literature of the use of UAVs to monitor wildfires and indeed commercial products exist for that purpose. UxS are in use in commercial sectors as well. In agriculture, for example, many types of systems exist for crop health monitoring, water use monitoring, crop phenotyping, and even autonomous weeding for organic crop production. Othercommercial applications exist in film making, sports broadcasting, real estate sales, house cleaning, personal use, etc. UxS are even deployed on other planets.

NASA currently has an autonomous ground vehicle on Mars, the “Perseverance,” but also a UAV specifically designed for the thin atmosphere of the planet . Clearly the use of these systems is widespread and growing. At the same time the autonomy requirements for the systems are growing more challenging. The ASV cited in the New York Times article, for example, can be deployed on missions up to one year in duration and the Mars Rover mission duration is likely longer. The implication for these longer duration missions is that vehicles must have onboard path finding capabilities, automated data capture and sample analysis, failure detection algorithms, data storage, and communication abilities to name just a few. Processing power requirements for autonomous systems are increasing as well, driven by the need for computationally expensive operations such as onboard computer vision, LiDAR sensor processing, and for evaluating machine learning models for object detection, image classification, and natural language processing. Longer duration missions and navigating complex environments place additional demands on the onboard processors. Finally, interacting in multi-agent environments, that is, environments with multiple autonomous systems adds dramatically to the complexity of the control system. Designing a modern autonomous system involves significant engineering effort and requires expertise in multiple areas. Given the widespread interest and use of autonomous systems there exists a need for a vehicle-agnostic controller—or autopilot—to enable the research and development efforts for new vehicles and new vehicle types. This autopilot should be capable of real-time computation ; easily modifiable in order to adapt to different vehicle configurations; and open-sourced in order to be accessible to a wide audience of users and contributors.

Furthermore, the autopilot may form the real-time core of a larger, distributed control system that also includes a single board computer for non-real-time tasks and a tensor processing unit to enable onboard ML capabilities. This architecture allows a developer to take advantage of the advancements in computing for SBCs and TPUs as well as to solve the issue of handling real-time tasks and non-real-time tasks simultaneously. To enable a distributed control system the autopilot must integrate with the external modules using a standard interface and a lightweight, extensible binary communication protocol. This architecture offers unique capabilities for autonomous vehicles. There are several sub-problems that can be specifically addressed with this architecture. The first is the means to develop and integrate real-time algorithms such as state estimation and vehicle control onto the autopilot. The embedded firmware operates using the simplest structure possible, with a hardware timer to dictate sensor and control update intervals. This structure allows an algorithm or sensor measurement to be encapsulated into a single function and therefore replaced or modified with minimal disruption to the remainder of the firmware. The controller can be adapted to any type of vehicle with relative ease, for example, or to evaluate different state estimation algorithms by changing one function and recompiling the firmware. Second, the SBC enables new capabilities for autonomous vehicles. Typically, the SBC has a Linux operating system providing access to standard functionality such as file storage, internet access, camera integration, USB devices, and running WiFi access points. These capabilities allow storage of sensor and vehicle state information into files from the vehicle, run mission planning software, or connect to USB peripherals such as the TPU. The OS also opens up extensive capabilities provided by open source software. For example, scientific software such as SciPy, computer vision software , ML packages , or even convex optimization software are all readily available to download onto the SBC. These advanced computational packages enable capabilities such as optimal trajectory generation, hydroponic nft channel mapping of landmarks, and advanced vision sensors. Finally, the TPU is a specialized processor that is designed to speed up ML inferencing tasks. The increased use of machine vision has made the need for onboard ML capabilities an attractive feature for many types of autonomous systems. It enables fast object detection or image classification without placing a computational burden on the SBC. For example, object detection allows for identification of landmarks or obstacles.

The TPU integrates seamlessly with the SBC via a USB interface and as in the case of the SBC runs open source software if possible. In summary, the increasing demands on autonomous systems and the technological advances in SBCs, TPUs, and sensing technology, suggest that a modular, distributed control system that includes a dedicated real-time autopilot is needed for the development of new autonomous vehicle classes. Small, resource-constrained systems benefit the most from this architecture and motivate this work. Given the proliferation of autonomous systems it is somewhat surprising that real time controllers are not more ubiquitous, few of the ones that do exist use open source firmware, and fewer still have open source hardware. The most promising one is a vehicle-agnostic control system: the modular rapid prototyping system, R2P. The project hardware and software are both open source. The system is designed so that each sensor or actuator is a standalone module called a node. The authors have developed a publisher-subscriber middleware to connect the nodes, a protocol called RTCAN. A series of connected nodes form the robot architecture. One downside to this approach is that the developer is restricted to the modules that have been developed for the system, that is, the system doesn’t have the ability to communicate directly with off-the-shelf sensors, nor can they easily be created by the user. Furthermore, each module is separately controlled with its own microcontroller and has an RJ45 wired connector so a complex system rapidly becomes unwieldy with many small boards wired together. Another downside for optimal real-time performance is the use of a real-time operating system , specifically the ChibiOS/RT. This is a powerful, lightweight and widely-used RTOS with a hardware abstraction layer that allows for re-use of peripheral drivers across different hardware platforms. However, modifying the firmware of a given module for a custom algorithm may be difficult to debug for real-time performance. For example, the inertial measurement unit module has its own attitude estimation algorithm encoded in it. If a developer needs a different attitude estimation algorithm it may be challenging to implement it and still guarantee the latency needed for the application. Nevertheless this system allows robot developers a path to quickly build and test a prototype robot, particularly if autonomy isn’t required and size of the control system is not a factor. An open source autonomous vehicle platform is found in the literature, the F1/10 platform. Although the project labels itself as an autonomous cyber-physical system platform, it is a 1/10 scale race car, employing an NVIDIA Jetson TX2 SBC running the Robot Operating System middleware. While this is a powerful SBC and ROS is a widely adopted middleware for robots, it is not real-time. In fact, the recent launch of ROS2 in part is due to the need for lower latency operations—a closer approximation to real-time, although it isn’t strictly real-time as it continues to operate on the Linux OS. In any case, this project is dedicated to a specific racing platform and therefore not easily adapted for other purposes. Aerial vehicles provide the richest source for real-time controllers, some of which have been adapted to different classes of vehicles. Table 1.1, adapted from a recent survey of open source UAV hardware controllers list the ones active as recently as 2018. Most of the platforms listed that use the STM microcontroller are designed to operate with an RTOS as the middleware, with the autopilot firmware loaded over it. The exceptions to this is the Chimera, which uses the Paparazzi autopilot firmware which has both an RTOS based firmware as well as a ‘bare metal’ implementation2 . The most prevalent autopilot firmware packages are PX4, Ardupilot, and LibrePilot . The other devices in the table, FlyMaple, APM2.8, Erle-Brain and PXFmini are no longer available. Both PX4 and Ardupilot support non-aerial vehicles to some extent. However, modifying the firmware within the RTOS is notoriously challenging due to the complexity of the code base. It is particularly difficult to implement a new vehicle type but also challenging to guarantee that latency requirements are met when modifying the estimation or control algorithms. These firmware packages are better suited to projects where modifying any of the underlying algorithms isn’t desired. The topic of an RTOS versus a bare metal application merits further discussion and will be covered in a later chapter.There are many papers on self-driving cars that describe vehicle control systems but very few discuss ones suitable for resource-constrained vehicles. For example, demonstrates a distributed architecture of a full size autonomous racecar that requires computational resources far beyond those available to resource-constrained systems. One exception to that, however, comes from, which reviews four different architectures with a focus on how resource-constrained systems can inform design choices for full size vehicles.

Through our work, we demonstrated a way to map out the Berry curvature distribution over the Brillouin zone and provide a direct probe of the topological character of strongly spin-orbit-coupled materials. This stands in contrast with transport measurement of spin and charge which reflect the global momentum-space average of the Berry curvature. In this regards, CD-ARPES can be a useful experimental tool to investigate certain aspects of the phase in electron wave functions if one can disentangle different contributions in the CD-ARPES. This work was supported by Research Resettlement Fund for the new faculty of Seoul National University and the research program of Institute for Basic Science . S. R. P. acknowledges support from the National Research Foundation of Korea . The Advanced Light Source is supported by the Office of Basic Energy Sciences of the U.S. DOE under Contract No. DE-AC02-05CH11231.In the momentum space of atomically thin transition metal dichalcogenides , a pair of degenerate exciton states are present at the K and K’-valleys, producing a valley degree of freedom that is analogous to the electron spin. The electrons in the K and K’-valleys acquire a finite Berry phase when they traverse in a loop around the band extrema, with the phase equal in magnitude but opposite in sign at the K and K’-valleys, as required by the time-reversal symmetry. The Berry phase not only has close connections to the optical selection rules that allow optical generation and detection of the valley-polarized carriers by circularly polarized photons, dutch bucket for tomatoes but also plays a central role in novel electron dynamics and transport phenomena in TMD and graphene layers, such as the valley Hall effect.

In principle the Berry phase, together with other effects from inversion symmetry breaking, can have profound consequences for the wave function and energy spectrum of the excited states in two-dimensional materials. TMD monolayers are known to host strongly bound excitons with a remarkably large exciton binding energy due to enhanced Coulomb interactions in 2D. It was recently predicted that the Berry curvature of Bloch states can add an anomalous term to the group velocity of electrons and holes and creates an energy splitting between exciton states with opposite angular momentum. Fig. 1a shows a simplified exciton energy spectrum illustrating the exciton fine structure based on our ab initio GW-Bethe-Salpeter equation calculations. The 2p+ and 2p− exciton states are split in energy with opposite order for the K and K’ valleys due to the opposite chirality in the two valleys. Such novel exciton fine structure, which embodies important wave function properties arising from the Bloch band geometry, can strongly modify the intraexcitonic light-matter interactions. Experimental observation of this predicted exciton spectrum, however, has been challenging, because it requires new spectroscopic probe that can distinguish both the momentum valley and the exciton angular momentum. Here, we report the first observation of the Berry-phase effect in the exciton spectrum of MoSe2 monolayer using intraexciton optical Stark spectroscopy. We demonstrate that the degeneracy between the 2p±-exciton states is lifted by the Berry phase effect, and enabling a valley-dependent Autler-Townes doublet from strong intraexciton light-matter coupling.

We coherently drive the intraexciton transitions using circularly-polarized infrared radiation, which couples the 1s exciton to the 2p+ or 2p− states selectively through the pumpphoton polarization . The pump-induced changes in the 1s exciton transition are detected by circularly polarized probes, which selectively measure the K or K’-valley excitons. Independent control of pump and probe photon polarization enables us to distinguish the exciton fine structures in the K and K’-valleys. We determine an energy splitting of 14 meV between the 2p+ and 2p− exciton states within a single valley, and this energy splitting changes sign between K and K’-valleys. We determine the 1s-2p transition dipole moment to be 55±6 Debye. This leads to an optical Stark shift that is almost 40 times larger than the interband counterpart under the same pump detuning and driving optical field strength. Such strong and valley-dependent intraexciton transitions open-up new pathways for the coherent manipulation of quantum states in 2D semiconducting materials using infrared radiation. To investigate the fine structure of the excitonic p-manifold, we fabricated a high quality MoSe2 monolayer that is encapsulated in hexagonal boron nitride layers using mechanical exfoliation and stacking following Ref. 21. The sandwiched hBN-MoSe2-hBN heterostructure was then transferred to an alumina-coated silver surface . The device was kept in vacuum at 77K for all optical measurements. This Aexciton peak arises from the optical transition between the ground state and the lowest energy 1s exciton state in MoSe2 monolayer, which is well-separated from the higher-lying exciton states due to strong Coulomb interactions in TMD monolayers10,11,20,24. We use intraexciton optical Stark spectroscopy with helicity-defined pump and probe light to selectively access the 2p+ or 2p− exciton states in the K and K’-valleys.

Quantum-mechanical coupling between the infrared photon field and the 1s-2p+ electronic transition leads to an avoided-crossing behavior that modifies the 1s-exciton state systematically with the changing infrared photon energy, as illustrated in Fig. 1d. When the infrared photon energy is below the 1s-2p+ resonance, the non-resonant hybridization leads to a decreased energy for the 1s exciton state.Since the infrared pump photon energy is much lower than the transition energy of 1s exciton, our measurement scheme probes only the coherent optical Stark effects without non-coherent contribution from real carrier generation. The colors in Fig. 2a-c represent the pump-induced change of the probe reflectivity Δ R, which is directly proportional to the change of absorption. The positive Δ R, is proportional to the decrease of absorption. The horizontal and vertical axes show the probe energy and pump-probe time delay, respectively. Strong transient signals are present for pump-probe delay closed to zero and they become negligible at pump-probe delays larger than 500fs. These instantaneous signals confirm the optical responses arise from coherent optical Stark effects.The evolution of the 1s exciton absorption in monolayer MoSe2 under coherent infrared driving can be better visualized directly from the optical absorption spectra characterized by the imaginary part of optical susceptibility.It shows clearly that the 1s exciton transition exhibits avoided-crossing behavior in both valleys, which evolves gradually from energy blueshift to splitting and then to redshift as the pump photon energy is decreased. It shows that the 1s-2 p+ intraexciton transition energy differs by 14 meV for the K and K’ valleys. Due to the time-reversal symmetry between K and K’-valleys in MoSe2 monolayer, this observation also indicates that the 2p+ and 2p− exciton states are non-degenerate and has an energy difference of 14 meV in a single valley. We further plot the blue- and red-shifted 1s resonance as a function of the infrared pump photon energy in Fig. 3b. We find that the energy shifts induced by the intraexciton optical Stark effect are almost 40 times larger than its interband counterpart at the same pump intensity and resonance detuning. To better understand the experimental results, we performed ab initio GW-BSE calculations using the BerkeleyGW package to determine the exciton energy levels and optical selection rules of exciton and intraexciton transitions in monolayer MoSe2. In these calculations, blueberry grow pot environmental screening effects from the hexagonal boron nitride encapsulation layers are included from first-principles . The simulation confirms the energy level diagram of the 1s, 2p+, and 2p− excitons and the optical selection rules in K and K’- valleys in Fig. 1a. Our calculations find that the energies of the 1s and 2p− exciton states are separated by 117 meV, with 2p+ exciton states further separated by 7 meV in K-valley. The energetic order of 2p+ , and 2p− excitons states is opposite in the K’-valley, as a result of time-reversal symmetry. Although the 2p± excitons are dark in linear optics, they are optically active when coupled to the 1s exciton with circularly-polarized light . The 1s-2p− intraexciton transition, on the other hand, coupled exclusively to the right-handed circularly polarized light. The experimentally observed intraexciton dipole moment and valley-dependent exciton fine structure match reasonably well with the ab initio GW-BSE calculations. The combination of 2p±-exciton splitting and extremely strong intraexcitonic light-matter interaction allow us to observe valley-dependent Autler-Townes doublets at higher pump intensity in MoSe2 monolayer. Towards this goal, we fabricated a hBN-encapsulated MoSe2 heterostructure on a zinc-sulphide substrate, where the local field factor on the sample for the infrared pump light is more favorable than that for MoSe2 on alumina coated silver substrate . In this device the 1s-2p+ intraexciton transition energies for the K and K’-valleys are determined to be 150 meV and 138 meV, respectively .This Autler-Townes doublet leads to a valleydependent electromagnetically induced transparency in the 1s exciton transition, where the absorption at the 1s exciton resonance is reduced by more than 10-fold compared to the undriven exciton . Our findings offer a new and effective pathway to coherently manipulate the quantum states and excitonic excitations using infrared radiation coupled to the 1s-2p+ intraexciton transition.Sample Fabrication. The MoSe2 monolayer encapsulated in hBN flakes were prepared with a polyethylene terephthalate stamp by a dry transfer method21. Monolayer MoSe2 and hBN flakes were first exfoliated onto silicon substrate with a 90 nm oxide layer. We used PET stamp to pick-up the top hBN flake, monolayer MoSe2, and bottom hBN flake in sequence with accurate alignment based on an optical microscope. The hBN/MoSe2/hBN heterostructure was then stamped on a silver substrate coated with a 85 nm alumina layer or on a zinc sulphide substrate.

Polymer and samples were heated to 60oC for the pickup and 130oC for the stamping process. Finally, the PET was dissolved in dichloromethane for 12 hours at room temperature. The sample temperature was kept at 77 K in a liquidnitrogen cooled cryostat equipped with BaF2 window during optical measurements. Intraexciton Optical Stark Spectroscopy. Pump-probe spectroscopy study is based on a regenerative amplifier seed by a mode-locked oscillator . The regenerative amplifier delivers femoto second pulses at a repetition rate of 150 kHz and a pulse duration of 250 fs, which were split into two beams. One beam was used to pump an optical parametric amplifier and the other beam was focused onto a sapphire crystal to generate super continuum light for probe pulses. Femto second mid-infrared pump pulses with tunable photon energies were generated via difference frequency mixing of the idler pulses from the optical parametric amplifier and residual of fundamental output from regenerative amplifier in a 1 mm thick silver gallium sulphide crystal. The mid-infrared pulse duration is ~350 fs. The pump-probe time delay was controlled by a motorized delay stage. The helicity of pump and probe pulses was independently controlled using Fresnel rhomb and broadband quarter-wave plates, respectively. The experiment followed a reflection configuration with a normal incidence and collinear pump-probe geometry, where the absorption spectra are extracted from the reflectance contrast as described in the supporting information.This work was primarily supported by the Center for Computational Study of Excited State Phenomena in Energy Materials, which is funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05CH11231, as part of the Computational Materials Sciences Program which provided the experimental measurements and GW-BSE calculations. The sample fabrication and linear optical spectroscopy was supported by the US Army Research Office under MURI award W911NF-17-1-0312. The pump-probe setup was supported by the ARO MURI award W911NF- 15-1-0447. This research used resources of the National Energy Research Scientific Computing Center , a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, and the Extreme Science and Engineering Discovery Environment , which is supported by National Science Foundation grant number ACI-1548562. S.T. acknowledges support from NSF DMR-1552220. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and the CREST , JST. E.C.R acknowledges support from the Department of Defense through the National Defense Science & Engineering Graduate Fellowship Program. C.-K.Y. and C.S.O. acknowledges useful discussion with Prof. Ajit Srivastava. Viruses are obligate intracellular pathogens that require living host cells to replicate and spread in the infected plant. During compatible interactions, viruses overcome the plant immune system and hijack host cellular processes to establish active infections .

Three labor-intensive control activities are currently used to reduce SWD-related yield losses: increasing the frequency of harvests, performing field sanitation, and implementing trapping programs to detect the presence of SWD populations. Further compounding these direct labor costs, the productivity of harvesting labor decreases as more frequent harvests and fruit losses due to SWD reduce the availability of marketable fruit to pick. Labor-intensive management activities are more intensely utilized by organic producers due to the lack of efficacious organic chemicals. Increasing the frequency of raspberry harvests means that fruit is harvested sooner, thus reducing the availability of ripe fruit in the field. SWD primarily targets red fruit that is fully ripened or overripe. While SWD also infest fruit before they ripen, this damage is less pervasive. Even if SWD infestations are present in less ripe fruit, the damage is less likely to be visible if the fruit is quickly harvested and cooled. Once fruit enters the cold chain, SWD development slows dramatically. As a result, a common practice among raspberry growers facing SWD damage has been to harvest a day sooner. Prior to the SWD invasion, raspberries were typically harvested every two to six days depending on the time of the season. Decreasing this interval to every one to five days implies a potential 20% to 100% increase in the frequency of harvests due to SWD, depending on the time of the season. Labor-intensive field sanitation efforts, which include pickers removing fallen and damaged fruit, nft growing system is another means of reducing the availability of fruit for SWD to infest. Removal of such unmarketable fruit from the field eliminates one potential source of SWD population growth, though external SWD populations can still be a significant source of damage.

Field sanitation is a recommended practice for all raspberry production even in the absence of SWD, but extensive field sanitation efforts are more likely to be observed with organic producers due to their greater damage rates and the costliness of such activities. Field sanitation is costly because pickers must be compensated. A common practice is to pay pickers a secondary, lower piece-rate for harvesting and disposing damaged fruit. Pickers performing field sanitation have been observed allocating as much as a quarter of their harvesting time to removing unmarketable fruit.26 For example, Rogers, Burkness, and Hutchison 34 examined SWD infestations in Minnesota raspberries and found that the average percentage of unmarketable fruit in untreated open plots was 29%. SWD infestations were found in 81% of sampled berries in these untreated open plots. Similarly, De Ros et al. 28 observed Italian berry growers allocating approximately a labor-hour per hectare each harvest day for sanitation efforts intended to control SWD. Growers who don’t remove fallen and damaged fruit have been observed to sustain increased damage rates as well as a higher probability of rejection of the whole shipment. A final labor-intensive management practice performed by many growers is the construction and maintenance of attractant-based traps. The materials required to produce these traps are inexpensive, but the construction and placement of the traps can be a labor-intensive activity. Growers utilize these traps to detect the presence of significant SWD populations in the fields they manage. However, available traps and attractants are nonspecific and capture many species of vinegar flies. In general, fly captures are a weak predictor of fruit losses. Producers often respond with more frequent insecticide applications and more intensive field sanitation when trap captures indicate the presence of large vinegar fly populations. Overall, the primary benefit of trapping programs has been to alert producers to the presence of SWD in areas where SWD had never been detected before. Regional trapping programs implemented by SWD researchers have also provided a rough measure of adult SWD activity at a given time of the year.

Sampling fruit directly provides a more accurate estimate of damage because virtually all fruit fly infestations in commercially viable California raspberries are SWD. However, direct sampling of fruit for infestations is time consuming for raspberry growers, who must transport their highly perishable product to a shipper within hours of a harvest. It is also a post facto measure since the fruit infestation measured has already occurred, so control at that time is of no value. In addition to growers implementing these labor-intensive SWD management practices, more frequent harvesting and fruit losses due to SWD limit how efficiently a grower can utilize labor. More frequent harvesting and fruit losses reduce fruit density in a field. Workers’ harvesting productivity is negatively impacted when they must spend additional time searching for marketable fruit that is less densely available. The harvest rate per raspberry picker can vary from one to five trays per hour depending on worker skill and fruit availability. An experienced picker can harvest up to 2.5 times more quickly than a novice, and yield alone can cause worker productivity to vary by a factor of two. SWD damage has the potential to reduce raspberry yields by up to 50% over a season and up to 100% in a specific harvest; therefore, it is clear that SWD damage can significantly affect workers’ productivity. Further compounding these labor-utilization issues, growers must offer a higher piecerate when productivity is low in order to retain their labor force and increased variability in available yield for harvest makes it more difficult for managers to allocate labor appropriately. The market for raspberry pickers is highly competitive. Workers who believe they can earn more money elsewhere, because less fruit is damaged, may leave during a harvest or not return for a subsequent harvest. The potential resulting labor shortage in fields with significant SWD damage could further exacerbate fruit losses due to SWD as unharvested fruit become overripe and act as a SWD breeding ground. Further, agricultural labor costs are also rising over time as the supply of labor from Mexico is shrinking due to improving economic conditions. It is difficult to observe these increased labor costs directly, but it is clear that they are not negligible. In 2015, a tray of 12 six ounce clam shells of conventional raspberries sold at an average price of $15.98 per tray based on Salinas-Watsonville and Oxnard district shipping point prices. According to a 2012 UC Davis study of raspberry production costs and returns, production costs were estimated to be $10 per tray of raspberries. Labor costs accounted for approximately half of these production costs, and the study did not report any SWD-targeting activities. The piece-rate alone averaged $4 per tray in a season. If one were to assume, conservatively, that these additional labor costs associated with managing SWD increased total labor costs by as little as 2% and 4% for conventional and organic raspberry producers, respectively, then these activities would account for a 1% and 2% increase in total production costs. Thus, a 1% increase is production costs would reduce a conventional raspberry grower’s profit margin by approximately 1.67%. If a similar cost structure is assumed for organic raspberry producers, then one would expect approximately a 3.34% reduction in profit margin resulting from the additional labor costs associated with managing SWD. Labor costs are assumed to increase by a greater percentage for organic producers because they are more reliant on labor-intensive SWD control methods.SWD’s invasion into North America has significantly harmed the California raspberry industry. We examined revenue losses and management costs associated with this invasive pest. Using a combination of field trial data and expert observations, nft hydroponic system we calculated that SWD has accounted for approximately $39.8 million in revenue losses, equivalent to 2.19% of realized revenues, for the California raspberry industry between 2009 and 2014. Conventional producers accounted for $36.4 million of these losses, equivalent to 2.07% of their realized revenues. Organic producers accounted for $3.43 million of these losses, equivalent to 5.74% of their realized revenues. SWD management activities have also significantly increased production costs for raspberry growers. We calculated that the cost of chemical purchases increased annual per hectare production costs for conventional and organic producers by $1,161.28 and $2,933.01, respectively. We also calculated that the cost of labor-intensive SWD management activities decreased conventional and organic raspberry producers’ profits by 1.67% and 3.34%, respectively.

Even though the industry has managed to adapt to the pest, these revenue losses and management costs have significantly reduced the profitability of the commercial production of fresh raspberries. Looking into the future, it is unclear whether SWD will remain a threat to California’s raspberry producers. On one hand, the primary biological reason that SWD has become such an economically damaging pest in both North America and Europe following its invasion is the absence of an effective natural enemy. In Asia, where SWD originates, the presence of effective natural enemies greatly reduces damages associated with the pest. Thus, the introduction of an effective biological control agent could dramatically reduce these estimated losses in the future. On the other hand, California’s raspberry producers rely heavily on chemical management options to reduce yield losses associated with SWD infestations. If SWD populations were to develop significant resistance to these chemicals over time or restrictions were placed on their use, then these estimated losses could increase dramatically. Agriculture is a key human activity in terms of food production, economic importance and impact on the global carbon cycle. As the human population heads toward 9 billion or beyond by 2050, there is an acute need to balance agricultural output with its impact on the environment, especially in terms of greenhouse gas production. An evolving set of tools, approaches and metrics are being employed under the term “climate smart agriculture” to help—from small and industrial scale growers to local and national policy setters—develop techniques at all levels and find solutions that strike that production-environment balance and promote various ecosystem services. California epitomizes the agriculture-climate challenge, as well as its opportunities. As the United States’ largest agricultural producing state agriculture also accounted for approximately 8% of California’s greenhouse gas emissions statewide for the period 2000–2013. At the same time, California is at the forefront of innovative approaches to CSA . Given the state’s Mediterranean climate, part of an integrated CSA strategy will likely include perennial crops, such as winegrapes, that have a high market value and store C long term in woody biomass. Economically, wine production and retail represents an important contribution to California’s economy, generating $61.5 billion in annual economic impact. In terms of land use, 230,000 ha in California are managed for wine production, with 4.2 million tons of winegrapes harvested annually with an approximate $3.2 billion farm gate value. This high level of production has come with some environmental costs, however, with degradation of native habitats, impacts to wildlife, and over abstraction of water resources. Although many economic and environmental impacts of wine production systems are actively being quantified, and while there is increasing scientific interest in the carbon footprint of vineyard management activities, efforts to quantify C capture and storage in annual and perennial biomass remain less well-examined. Studies from Mediterranean climates have focused mostly on C cycle processes in annual agroecosystems or natural systems. Related studies have investigated sources of GHGs, on-site energy balance, water use and potential impacts of climate change on productivity and the distribution of grape production. The perennial nature and extent of vineyard agroecosystems have brought increasing interest from growers and the public sector to reduce the GHG footprint associated with wine production. The ongoing development of carbon accounting protocols within the international wine industry reflects the increased attention that industry and consumers are putting on GHG emissions and offsets. In principle, an easy-to-use, wine industry specific, GHG protocol would measure the carbon footprints of winery and vineyard operations of all sizes. However, such footprint assessment protocols remain poorly parameterized, especially those requiring time-consuming empirical methods. Data collected from the field, such as vine biomass, cover crop biomass, and soil carbon storage capacity are difficult to obtain and remain sparse, and thus limit the further development of carbon accounting in the wine sector. Simple yet accurate methods are needed to allow vineyard managers to measure C stocks in situ and thereby better parameterize carbon accounting protocols. Not only would removing this data bottleneck encourage broader participation in such activities, it would also provide a reliable means to reward climate smart agriculture.

The spatially-explicit nature of the model allows for robust representation of varying canopy architectures and their effect on berry temperature. The objective of this study was to accurately simulate the spatial and temporal grape berry temperature fluctuations from different vineyard designs, such that model predictions are robust to changes in vineyard configuration such as row spacing, trellis system, and row orientation.The 3D geometry of the ground, woody tissues, leaves, and grape berries were represented using a mesh of triangular and rectangular elements within the Helios 3D modeling framework. The procedural plant model generator in Helios allows the user to specify average and random geometric parameter values in order to create a given canopy geometry. Grape berries were represented in 3D as tessellated spheres composed of triangular elements, the ground surface was represented as a planar grid of rectangular elements, woody tissues were represented as a cylindrical mesh of triangular elements, and leaves were represented as a planar rectangle that is masked to the shape of a leaf using the transparency channel of a PNG image.When the terrain was flat, only one grapevine plant geometry was represented in the model, but with periodic boundary conditions applied in the horizontal directions which effectively yielded a horizontally infinite canopy. For inclined terrain, 7 rows of grapevine plants were represented in the slope-normal direction, and periodic boundary conditions were enforced in the slope-parallel direction .For triangular elements corresponding to grape berries, it was assumed that, large round pot since the density of lenticels after veraison is low, the latent heat flux was negligible.

In terms of Eq. 3.1, this assumption was implemented by setting gw = 0 for berry elements. It was also assumed that heat released from metabolic activity within the fruit is negligible, and thus no metabolic heat source term was included in Eq. 3.1. The formulation given by Eq. 3.1 also inherently assumes that the surface temperature at any point is representative of the entire temperature of the object . Furthermore, since the surface of the berry is discretized into many triangular elements that could have different temperatures, it was effectively assumed that each triangle corresponds to a “slice” of berry volume subtended by the triangle, which is at the same temperature of that triangular surface element, and responds to ambient changes with a time constant equal to that of the entire berry . Average berry element radiative properties for PAR and NIR bands are given in Table 3.1, which were measured for 3 replicates in the field . For rectangular elements comprising the ground surface, Eq. 3.1 was applied without the latent heat term , thus assuming that latent cooling due to water evaporation from the soil was minimal. The heat storage term in Eq. 3.1 was retained and used an assumed value of CprA of 30 kJ K−1 m−2. Clearly, the assumption of uniform temperature in the soil column when calculating the heat storage term is incorrect. However, the chosen value of CprA provided a reasonable temperature response time scale for the soil on the order of an hour and gave midday storage values between 20 and 30% of the net radiation flux, which is generally consistent with observations. Furthermore, since the focus of this work was on modeling the temperature of the berries and not the ground specifically, this approximation was deemed acceptable given that the ground temperature only has a secondary effect on modeled berry temperature in terms of long-wave emission.

Note also that convective heat transfer between the ground and berries was not modeled directly, but rather was specified using measured temperature and humidity near the berries.To validate the 3D model, field experiments were conducted in four Vitis vinifera L. cv. Cabernet Sauvignon vineyards from Sept 19th to Oct 10th during the 2018 and ´ 2019 seasons. Two study vineyards were located in Davis, CA and two others were located in Napa, CA , with each vineyard having a different trellis type. At the research site in Davis, the vines were on a flat terrain, and in Napa the vines were terraced along an east facing slope of approximately 30 degrees. The grapevines sampled in Davis were trained to the vertical shoot position trellis system and the Wye trellis system , while the Napa grapevines were trained to a Unilateral cordon and a Goblet system . The Unilateral vineyard was configured with one vine in each terrace level, while for Goblet there were two per level. The sampled vine in Goblet was adjacent to the terrace slope leading upward to the next row. The Napa Unilateral and Goblet grapevines were on the same slope at approximately the same elevation and row orientation. Thus it can be reasonably assumed that these two systems experienced nearly the same ambient conditions, making possible a comparison of the effects of canopy architecture. While the Davis VSP and Wye grapevines were in adjacent blocks with the same orientation, a direct comparison is not possible because measurements were collected in different years, and thus ambient weather conditions were different. For the four experiments, berry temperature was measured using 0.076 mm diameter type ‘E’ thermocouples . The thermocouples were inserted into the center of the berries in exposed clusters facing the east and west side of the vine, and at each side of the vine 4 thermocouples were placed in different berries within the cluster. Because berries could develop necrosis from being punctured by the thermocouple, thermocouples were relocated to adjacent exposed berries at least every 12 days to maintain relatively fresh conditions.In order to remove the effects of canopy-scale energy and momentum transfer and focus only on berry-scale transfer, ambient measurements were made near the clusters and used to force the model.

A weather station was installed at each study site immediately adjacent to the grapevines chosen for temperature measurements. The environmental variable inputs that were measured included incoming above-canopy photosynthetically active solar radiation , wind speed , relative humidity and air temperature . The incoming solar radiation was measured at a height of 3 m and was used to calibrate the incoming solar flux model in Helios as mentioned previously. The wind speed, relative humidity and air temperature were measured directly adjacent to the vine at the cluster height in order to estimate microclimatic conditions just outside of the berry boundary-layer. The sampling period for all weather data was 5 min. Specific humidity was estimated using the measured air temperature and relative humidity data, and since atmospheric pressure was not measured at the site, hourly average air pressure data from the National Oceanic and Atmospheric Administration local weather stations in Davis and Napa. To evaluate the model’s ability to simulate spatial and temporal fluctuations in grape berry temperature, experimental data measured on clear-sky days was used to drive the model and generate predicted berry temperatures. These temperatures were then separately averaged over east-facing and west-facing clusters and compared to average experimental values for the same exposure. The accuracy of the model was evaluated using the statistical error indices of normalized root mean square error , big round plant pot the coefficient of determination , and the index of agreement .An average characterization of weather conditions during the roughly 3-week period in which the weather stations were deployed is provided in Table 3.3. A more detailed graphical depiction of the measured air temperature, air relative humidity, wind speed, and of the calculated specific humidity time series data for the different experimental vineyard designs over the chosen validation period is shown in Fig. 3.2. During the 3-week period, the daily average air temperature was similar in VSP and Wye, with a wider average daily range of temperature in VSP compared to Wye . The daily average and average of maximum and minimum relative humidity were significantly higher in VSP compared to Wye, while the maximum wind speed measured in VSP was similar to Wye. Architectural differences between Wye and VSP were characterized by higher berry height, wider row spacing, and increased self-shading in Wye relative to VSP. Recalling that air temperature, humidity, and wind speed measurements were made at the height of the berry clusters, the higher berry height in Wye likely created daytime conditions of lower convective and radiative heat transfer from the warm ground to the fruiting zone, and overall greater turbulent mixing of warm, moist air out of the canopy. Specifically, during the validation day, the greater wind speed measured in Wye was likely responsible for the reduced air temperature and humidity at the measurement height compared to VSP . For Goblet and Unilateral, during the 3-week period, the daily average and average range of temperature were similar. However, the average maximum relative humidity in Goblet was greater compared to Unilateral and the maximum wind speed was significantly higher in Unilateral compared to Goblet . The architectural differences between Goblet and Unilateral were dominated by the higher berry height and wider row spacing in Unilateral relative to Goblet. Additionally, the close proximity of the Goblet vines to the adjacent terrace slope created an even larger ground view factor. During the validation day, similar to that observed in VSP relative to Wye, the proximity of the clusters to the ground and low wind speeds due to the tight row spacing in Goblet likely contributed to the increased air temperature and humidity fluctuations compared to Unilateral .Spatial and temporal variation in measured and simulated berry temperature is depicted graphically in Figs. 3.3 and 3.4, respectively. A sample visualization of the 3D distribution of the surface-air temperature difference for each vineyard is shown in Fig. 3.1.

During the night, all berry temperatures were near the ambient air temperature, and thus the spatial variability in berry temperature was small and did not vary noticeably among the vineyard designs. During daytime hours, berries in the shade tended to closely match the ambient air temperature, and could reach over 10◦C above ambient when in direct sunlight. The maximum berry temperature increase over air temperature measured in the field was 12.4◦C for VSP, 11.3◦C for Wye, 12.2◦C for Goblet and 14.0◦C for Unilateral . Besides, the closed canopy in Wye that limited berry sun exposure compared to VSP, it is likely that the greater wind speeds in Wye contributed to the enhanced sensible heat flux exchange and thus the reduced temperature as compared with VSP. For the Goblet and Unilateral vineyards, the east-facing slope and the ratio between plant height and plant spacing mainly determined the hours of berry exposure at the different positions, and therefore, the spatial berry temperature fluctuations. High berry temperatures tended to occur in berries in the west side of the vine during the afternoon when air temperature was warmer and there was exposure to direct sunlight . Measurements taken on berries of the west-facing clusters showed that the warmer afternoon temperature increased berry temperature up to 10◦C more than that of a similar east-facing cluster. As shown in Fig. 3.3 the highest temperatures on the west side occurred between 15:00 and 17:00 for VSP and Wye , and between 14:00 and 16:00 for Unilateral and Goblet . It is possible that in Goblet the lower wind speeds, along with proximity of berries to the slope, resulted in less canopy-scale turbulent mixing and a subsequent heating of within-canopy air near the berries compared to Unilateral.Modeled berry temperatures fluctuated rapidly with changes in absorbed radiation, sensible heat, and heat storage. Maximum values of simulated cluster absorbed radiation for the NW-SE orientations in VSP and Wye occurred about 3 hours before noon in the east side of the vine and 4 hours after noon in the west side . Horizontal canopy division in Wye increased self shading early and late in the day compared to VSP, which minimized exposure to direct sunlight. The widely spaced vines and high berry height in Unilateral favored greater berry light interception early in the morning compared to Goblet. In Goblet and Unilateral vineyard systems, the large difference in bunch exposure between the east and west side of the vines appeared to be dominated by the east-facing slope, which reduced the absorbed radiation in the west side of the vines compared to the east side. Vineyard geometry had a significant impact on the timing of cluster shading, primarily because of variation in row spacing relative to the plant height. While the absorbed radiation fluxes were positive during the day, the sensible heat fluxes tended to be negative during the day because the berries were warmer than the ambient air. Overall, the sensible heat losses were greater in the afternoon due to the greater difference between berry and air temperature during these hours.

The Pancharatnam–Berry phase was discovered by Pancharatnam in studies of polarized light and introduced by Berry as a topological phase for matter wave functions. For light, the Pancharatnam–Berry phase is measured in laser interferometers and exploited in optical elements. Excitons are matter waves that directly transform to photons inheriting their coherence and polarization. This makes excitons a unique interface between matter and light and a unique system for exploring the Pancharatnam–Berry phase for matter waves by light interference experiments. Recent studies led to the discovery of polarization textures in light emission of indirect excitons and exciton–polaritons. This connection of the Pancharatnam–Berry phase to polarization makes it an intrinsic phenomenon for polarization textures. An IX is a bound pair of an electron and a hole confined in spatially separated layers. IXs are realized in coupled quantum well structures. Due to their long lifetimes IXs can cool below the temperature of quantum degeneracy and form a condensate in momentum space. IX condensation is detected by measurement of IX spontaneous coherence with a coherence length much larger than in a classical gas. The large coherence length observed in an IX condensate, reaching ~10 μm, indicates coherent IX transport with suppressed scattering, in agreement with theory. A cold IX gas is realized in the regions of the external ring and localized bright spot rings in the IX emission. These rings form on the boundaries of electron-rich and hole-rich regions created by current through the structure and optical excitation, respectively; see ref. and references therein. An LBS is a stable, well defined, square plastic plant pots and tunable source of cold IXs, thus an ideal system for studying coherence and polarization phenomena.

Different LBS offer IX sources of different strength and spatial extension; furthermore, these parameters can be controlled by optical excitation and voltage. This variability gives the opportunity to measure correlations between coherence and polarization. Here, we explore LBS to uncover the Pancharatnam–Berry phase in a condensate of IXs.The experiment shows that the phase shifts correlate with the polarization pattern of IX emission and onset of IX spontaneous coherence. The correlation between the phase shift and the polarization change identifies the phase as the Pancharatnam–Berry phase acquired in a condensate of IXs. This phenomenon is discussed below. The spatial separation of an electron and a hole in an IX reduces the overlap of the electron and hole wave functions suppressing the spin relaxation mechanism due to electron–hole exchange. In a classical IX gas, spin transport in the studied structure is limited by 1−2 μm due to Dyakonov–Perel spin relaxation. As a result, for uncondensed IXs at r < rcoh, the spin relaxation is fast and coherent spin precession is not observed. However, the suppression of scattering in IX condensate results in the suppression of the Dyakonov–Perel and Elliott–Yafet mechanisms of spin relaxation enabling long-range coherent spin transport in IX condensate. Therefore, IX condensation at r > rcoh dramatically enhances the spin relaxation time leading to coherent spin precession and, in turn, precession of the polarization state of IX emission. This precession generates the evolving Pancharatnam–Berry phase of IXs, which is detected as the shift of interference fringes.

Figure 4d shows that no decay of the evolving Pancharatnam–Berry phase is observed over macroscopic lengths exceeding 10 μm. This indicates the achievement of macroscopic long-range coherent spin transport in the IX condensate.According to current climate projections, we face an increase in the intensity, frequency, and duration of heat waves in the coming years . Therefore, it is imperative that the grape and wine industry study the effects of these heat events on different wine growing regions around the world. Extreme temperatures can have detrimental effects on grapevines including but not limited to decreases in yield, unwanted changes in berry composition, and decreases in overall grape quality . High temperatures cause increased water loss via evapotranspirative cooling and overall stress on grapevines, so irrigation practices can be useful in mitigating the negative impacts of HWs by altering vine water status, leaf and berry temperature. Shade cloths, cover crops, rootstock selection, changes in row orientation and trellis system to protect from solar radiation with misting, or increased irrigation throughout HWs, are further strategies being implemented in current wine regions to mitigate their adverse effects . However, with growing water scarcity, a more efficient use of water and a deeper understanding of the effects of HWs and water use during different grapevine phenological stages will be required . Although grapevines are resilient crops that can tolerate drought and extreme temperatures , it is important to explore alternative grape cultivars that may be better suited for these warmer scenarios. Two widely used irrigation methods are regulated deficit irrigation and partial root-zone drying . In RDI, irrigation is reduced or completely stopped for specific periods during the growing season.

A study done in South Australia showed that water deficit after flowering resulted in the “greatest reduction in berry weight compared with that of well-watered vines” . This is important to note because this may not have been the result had water deficit been practiced before flowering, thus showing that timing is crucial. In turn, water deficit after veraison only had a minor effect on berry weight at maturity and berries were not affected by water deficit during the month before harvest. With PRD, half of the root system is maintained in a dry state while the other half is irrigated . The theory behind PRD is that the watered roots maintain a favorable plant water status, while the dry roots result in chemical signals, such as increases in abscisic acid production, that are transported to leaves to reduce growth and therefore vigor. Deficit irrigation has two main effects on grape berry composition: a decrease in berry size and the upregulation of genes in the phenylpropanoid and flavonoid pathways. In terms of berry size, the skin to pulp ratio increases, which causes phenolic compounds to become more concentrated. In terms of transcriptomics, the upregulation of genes in the phenylpropanoid and flavonoid pathways causes an increase in anthocyanin synthesis due to signaling from an increase in abscisic acid . Alternatively, the effect of deficit irrigation on tannins is largely due to a reduction in berry size rather than an impact on their biosynthesis. . It is important to note that the beneficial aspects of deficit irrigation may not be the same in the future due to projected climate warming, and the combined effects of greater heat and water stress with deficit irrigation may be detrimental to berry quality . Berry development follows a double sigmoidal curve, which is divided into three stages . The first phase occurs after fruit set and is characterized by cell division and cell expansion . This is then followed by a lag phase, which is a period of little to no growth, but is characterized by a rapid accumulation of organic acids, particularly malic acid. The last stage is characterized by the onset of veraison . During this second growth phase, berries soften, accumulate sugar, and grow larger. In red varieties, anthocyanins begin to synthesize, allowing for the red and purple pigments to show in the skins . High temperatures affect berry development primarily at post fruit set, veraison, and mid ripening . A decrease in berry size before veraison caused by high temperatures is due to effects on cell division , whereas post veraison, this decrease is likely due to a stop in cell expansion and an increase in transpiration. Closer to maturity, high temperature seems to be linked to cell death, loss in berry mass, and increased water loss, leading to shriveling and sunburn . With global warming, square pot plastic increasing mean temperatures are further correlated with an earlier onset of phenological stages in the grapevine and the shortening of the duration of these stages . Moreover, since most viticultural regions are currently at or near their optimal growing temperatures for the grape cultivars grown there , global warming intensifies the pressure of exploring new varieties that better suit these regions. Additionally, the effects of HWs on grapevines will depend on the timing of the heat event during specific phenological stages. Although the effects of elevated temperatures throughout the growing season vary by cultivar, literature has consistently shown that flowering is a period that is more sensitive to heat, and the length of the interval from bud burst to flowering is more susceptible to a decrease than other phenological intervals. . During grape development, fruit set shows resistance to elevated temperatures, whereas veraison and mid-ripening are more sensitive to heat . From a berry chemistry perspective, exposure to high temperatures has an important impact on primary and secondary metabolite production in the berry.

Studies have shown that grape berry metabolism is sensitive to both day and nighttime temperatures and the magnitude of these diurnal temperature changes . Primary metabolites of grape berries include sugars, amino acids, and organic acids. While they contribute to the support of normal growth and reproduction, secondary metabolites serve ecological functions, such as defense to abiotic or biotic pressures . Among the secondary metabolites produced by the grapevine, phenolic compounds and aromatic compounds are of major interest due to their impact on grape and wine quality. The Shikimate, phenylpropanoid, and flavonoid pathways are responsible for the biosynthesis of the different phenolic compounds that can be found in grapes . Grape phenolics can be divided into two groups: non-flavonoids and flavonoids. Flavonoids are most relevant to wine quality and are divided into three groups: flavan-3-ols, anthocyanins, and flavonols . Flavan-3-ols are mainly present in the form of proanthocyanidins and contribute to the bitterness and astringency of wine . Anthocyanins are responsible for the color of red wine , and flavonols act as UV protectants and copigments . All three groups of flavonoids are affected by environmental factors including high temperature in different ways. Flavonols are synthesized from the flavonoid biosynthetic pathway and also give rise to anthocyanins and proanthocyanidins . They are primarily located in the skin and mainly function as UV protectants and as copigments with anthocyanins to form stable pigments . The major flavonol compounds found in grapes include quercetin, myricetin, and kaempferol . Flavonol synthesis begins at flowering, reaches peak concentrations after veraison, and decreases during development as the berries increase in size . Flavonol synthesis is light dependent, and sunlight has a greater impact on development than temperature does. While shading has modest effects on berry development, it significantly decreases flavonol synthesis . It has been found that high temperatures don’t have a significant impact on flavonol content when compared to other grape berry metabolites . Gouot et al., studied the combined effects of high temperature duration and intensity on phenolic metabolism of Shiraz berries. They found that flavonol content of berries exposed to 46 °C showed no significant difference to those exposed to 35 °C. However, flavonols were degraded in berries exposed to 54 °C. This shows that high temperature has indirect effects on flavonol levels, while sunlight remains the key influencing factor. Anthocyanins are pigmented molecules responsible for the color of red wines and begin their synthesis in grape berries after veraison, reach maximum values close to maturity, and then decrease . Previous studies have shown that high temperatures affect anthocyanin levels in two ways: inhibiting anthocyanin biosynthesis and promoting degradation . Literature suggests that anthocyanin accumulation in grapes is more influenced by temperature rather than light when photon fluxes are above 100 µmol/m2 /s . Anthocyanins reach critical metabolic temperature for synthesis around 30ºC , but signs of inhibition begin beyond this temperature, where reduction in the activity of enzymes involved in the phenylpropanoid and flavonoid pathways, such as phenylalanine ammonia lyase , VIMYBA2, and UDP-glucose flavonoid-3-O-glucosyltransferase , have been observed . Additionally, it has been found that while anthocyanins were suppressed at transcriptional and enzymatic levels, peroxidase activity had increased, suggesting that peroxidase plays a key role in degradation . Studies carried out in Cabernet Sauvignon by Mori et al., found that biosynthesis of anthocyanins was not affected by high temperatures and the decrease of anthocyanin levels was mainly due to chemical and enzymatic degradation. Flavan-3-ols are the most abundant phenolic compounds in grapes and wine , and they are composed of monomeric catechins and oligomeric or polymeric proanthocyanidins . In terms of sensory effects, proanthocyanidins are responsible for astringency and bitterness perceived in grapes and wine . These compounds also have antioxidant properties and interact with anthocyanins to form stable pigments .

Investments in water-related data and information platforms have the potential for large payoffs by helping entities make more informed decisions. Unfortunately, despite the clear importance for practical decision making, a persistent lack of appropriate water accounting information hinders analysis of likely outcomes of water policy choices. By narrowing crucial information gaps, agencies may improve prospects for agriculture, ecosystems, and underrepresented communities as they confront less reliable and potentially lower overall, water supply allocations in the future . Better and timely monitoring and measurement at the watershed level will also provide a clearer picture of how actions in one part of a watershed may impact other parts of the watershed thereby providing policy makers with a more complete understanding of the consequences and trade-offs of any particular action within the watershed. Universities and other institutions have long supported productivity growth and improved environmental performance of agriculture in California and elsewhere with research and outreach . R&D has contributed improved varieties, irrigation, and drainage technology and improved farm practices that have saved resources and improved environmental outcomes. Progress may come from better integrating social and biophysical sciences for socially just adaptations that value farmers’ knowledge and experience to assist in transitioning to more resilient systems. Developing a coherent research agenda to better integrate climate projections, pest/disease forecasting, soil ecosystems, new genotypes, black plant pots plastic and system designs into agricultural management is needed. More and better organized and documented openaccess water data and models can make further significant contributions to informing policy and decision-making.

The high costs of water transactions, including among farmers, service areas and regions, and for groundwater recharge makes adaptation to climate change more difficult. During 2023, California facilitated some recharge efforts to take advantage of the extreme wet conditions and rebuild groundwater storage. Unfortunately, such measures fell far short of their potential. In addition to infrastructure limitations, permitting delays and other institutional constraints limited the extent of recharge. California’s adaptation to climate extremes would benefit from agile state and local regulation and coordination to facilitate recharge. More integrated water and climate policy will follow from early coordinated and collaborative management and governance to exchange ideas and understand impacts of a wide and inclusive set of scenarios . Careful planning across the policy landscape could foster climate smart policies that leverage current incentives for GHG reductions and offsets to promote adaptation.Like many agricultural regions worldwide, California is facing extreme climate challenges, including increases in water scarcity and water supply variability. Growing competition for water to better support ecosystems and added regulatory oversight will continue to demand innovations to incentivize farms to produce more value with fewer resources. Innovations are often motivated by scarcity and high costs of resources, such as labor, land, and water. Moving forward, more innovation will need to be devoted to reconciling agriculture with ecosystem health, in the context of evolving knowledge and changing climate. External costs and benefits, along with third party impacts, are likely to connect with global food market forces, to drive the direction of agricultural responses. The increased economic, ecological, and community benefits associated with enhanced knowledge of these connections will require significant efforts and commitments on the part of governments and institutions to be realized.

California can enhance climate resilience stewardship by adopting policies and practices to reduce vulnerabilities to climate extremes. Irrigation practices and technology of the recent past, such as those that ignore the importance of groundwater recharge and return flows, and adoption of permanent crops that have minimal year-to-year flexibility in water demand, are increasingly recognized as costly and risky. California is recognizing the value of more flexible water use, both temporally in terms of reservoir storage and carryover rules and spatially in terms of water trading. Moving toward more flexible irrigation water use with smaller negative impacts on rural communities and the environment . Water markets can better direct water to the most valuable social uses by considering third-party impacts water reallocation. Though climate change presents a more variable and uncertain future, it provides opportunities to adapt agricultural landscapes to better steward the environment. Bold measures are urgently needed as water availability limits have already been exceeded and adaptation pathways adequate to address these challenges require faster interventions than current trends . Approaches that decrease exposures to stress, reduce vulnerabilities, and enhance stress resistance and recovery, are important for California to address its climate change challenges. These measures include i) developing a capacity to integrate climate projections, pest/disease forecasting, new genotypes, and system designs into agricultural management, ii) reducing and redistributing irrigation water to recognize the value of ecosystem services, iii) improving prevention, monitoring, and surveillance of droughts and floods, and iv) leveraging GHG reduction and offset policies to promoting biodiversity, and ecosystem resilience. Effective adaptations must go beyond managing the conventionally measured impacts of water variability and toward food systems that address the market and social and ecological drivers . Investing in transdisciplinary research and education to support context-specific adaptations is especially relevant to address the potential social, environmental, and economic tradeoffs.

Building strong and inclusive networks for research, knowledge sharing, and planning is critical to reduce mistakes and scale up the most effective measures that mitigate and adapt to a changing climate.Initiatives to offer more organic, local, or fairly traded foods on the nation’s colleges and universities are spreading throughout the country. These efforts, often called “farm-to-college” or “farm-to-university”, aim to utilize institutional purchasing power to support local growers and principles of sustainable food systems, while providing fresh and healthy food to the campus community. Farm-to-college programs are part of a larger effort to change the food systems in the institutional food service sector, including schools, hospitals, and prisons. Such programs could be a lifeline for small-scale farmers struggling to stay afloat, and would improve the eating habits of millions of Americans. Moreover, if institutional food buyers embrace sustainably produced goods, such as organic or fair-trade products, the environmental and social gains would be significant. The health, economic, and sustainability potential of farm-to-college programs is intertwined with their ability to meet the needs of the campus communities they serve. Knowing the interests and needs of their customers will enable program managers to better gauge “effective demand” and develop programs consonant with the desires of their customer base. To date, while there are a few studies about farm-to-college programs, there has been no research on the preferences and perspectives of campus consumers. Since the success of farm-to-college programs involves their ability to meet the needs of campus consumers, we undertook a study of our local campus, the University of California, Santa Cruz, large plastic pots for plants to learn about the perspectives and preferences of campus food consumers. This research brief reports the results of that study and discusses their implications for the development of farm-to-college programs. The study was conducted in collaboration with groups at UC Santa Cruz working to improve the campus food system. These groups include the UC Santa Cruz Food Systems Working Group, UC Santa Cruz Dining Services, the Community Agroecology Network, and the Students for Sustainability . The questionnaire was developed by Jan Perez, Patricia Allen, and Phil Howard at the UC Santa Cruz Center for Agroecology and Sustainable Food Systems, in consultation with representatives from the groups mentioned above. An online survey was designed to elicit responses on food-related concerns, interests, and level of support for specific food criteria. In addition, questions were included to assess how food concerns rank compared to other national issues, and preferred methods for people to learn about their food. In November 2005, UCSC students, staff and faculty were contacted via email and invited to take the survey online. The survey was available online for people to take until mid January, 2006, and 4 followup emails were sent. There were 36 emails that bounced back, and 464 people completed at least a portion of the survey, resulting in a 25% response rate.UC Santa Cruz is a mid-sized university located on the west coast of California. The campus community tends to be relatively liberal on economic and political issues and enjoys a mild climate that makes possible a diverse supply of fresh fruits and vegetables for most months of the year. Table 1 shows the distribution of respondents in terms of gender , ethnicity , age, and grade level. The table also shows the percentage of students , staff , and faculty who responded to the survey.

These proportions closely approximate those in the campus community: 77% students, 16% staff, and 7% faculty or academic staff. Although food issues are inevitably bundled with general environmental, economic, and social issues, we wanted to get a sense of their importance relative to “non-food” issues, such as strengthening the nation’s economy and terrorism, which have been ranked as top priorities in national opinion polls . Respondents were asked to rank a set of issues on a Likert scale ranging from 4 to 1 . As shown in table 2, food issues were comparatively important to survey respondents. Combining categories of top priority and important, only one issue, protecting the environment, ranked higher than the food issue of access for low-income people . Other important food issues had to do with environment and health—food safety and pesticides in the food system —and working conditions . Food issues that were the least important to respondents were developing local food systems and limiting genetic engineering of foods , which ranked only slightly above protecting the country from terrorism.We also wanted to get a sense of the relative level of interest in specific food system issues to the UCSC community. To gauge this, we asked respondents to rank their level of interest in a series of topics on a scale of 1 to 10 . The topics in which people are most interested are personal—the safety and nutrition of their food, both of which ranked, on average, greater than 8 . Working conditions of workers and environmental impacts of food were of next highest interest, both with an average ranking of 8. Next in line are the wages of workers and the treatment of animals, with an average ranking of 7.71 and 7.65, respectively. This was closely followed by the influence of large corporations . The topic in which people were least interested by a significant margin was the distance food travels from its point of production, at an average ranking of 5.94. Inferences about preferred food qualities can be made from the issues in which respondents are most interested. However, a more direct way of assessing the qualities that people would like to see in their campus food is to determine their level of interest in existing labels that promote different food qualities. We asked respondents to rate their level of interest in purchasing food with the following labels: fair trade, certified organic, locally produced, water quality protection, humane treatment of animals, U.S. grown, and union. The percent of respondents with a “strong interest” in the label , was high, above 50%, for organic, humane treatment, water quality, fair trade, and locally grown . Although the percent with strong interests varies , the differences between the levels of interest in these five labels are not statistically significant. However, interest in U.S. grown and a union label was much lower, and was statistically different than interest in the top five labels. It is perplexing that interest in a union label is significantly lower than in a Fair Trade label, since both deal with providing fair wages and fair working conditions or rules. The negative publicity towards unions in an age where free market principles dominate has likely played a role in these results. In addition, people may have been personally affected by union labor actions such as teacher and bus driver strikes and may have had conflicted reactions as to the merits of such activities. The Fair Trade label, on the other hand, is a relatively new initiative. This newness allows a greater focus on principles and less on the difficult issues that develop when ideals are put into practice. Understanding more about the differential support for unions and fair trade would be worthwhile to explore in future research.

Self-expanding stents are more flexible and restrained within a covering sheath, and by removing the sheath and uncovering the stent; the stent expands. The common materials used to make stents are stainless steel , platinum-iridium, Nitinol, cobalt-based alloys, titanium, and tantalum, along with some biodegradable, bio-resorbable materials such as magnesium and resorbable polymers. Because of anticipated growth in children, self-expandable stents are ideal to be used in children. There are several varieties of stent design that have been used in congenital field, including mesh, coilloop, ring and slotted tube, closed cell, open cell, and welded tube. Here some of the investigation that others did to create an optimum stent is reviewed. Such a stent is not yet available that combines all these requirements, however in this investigation it was tried to address some of these features in the designed stent. Sullivan et al., investigated the effect of the endovascular stent strut geometry on vascular injury, myointimal hyperplasia and restenosis. The authors used a Palmaz stent with rectangular struts and smooth corners and a novel stent with thicker struts and sharper corners to induce larger wall stress concentrations in a 90 days study. Sullivan et al., found that the thicker strut and sharper corners resulted in a statistically higher incidence rate of deep vascular injury compared to the Palmaz stent. As a result, square plant pot a higher restenosis rate observed with thicker and sharp corner struts.

At the end of their study the authors concluded that maintenance of an intact internal elastic lamina is crucial to prevent myointimal hyperplasia and restenosis in stented porcine iliac arteries. Sullivan et al., also found that superficial injury elicits a response that is independent of the stent strut geometry and vessel wall compression. Stent strut profile may, however, increase local vessel wall stress concentrations, leading to IEL rupture and an exaggerated response injury. Therefore, when stents are designed, extra attention should be given to the strut geometry. Bedoya et al., designed some generic stent models that represent the characteristics present commercially available stents. The authors deployed each stent in a homogeneous nonlinear hyperplastic artery model and evaluated them using commercially available finite element analysis software. Using computer simulation modeling Bedoya et al., suggested that stent designs incorporating a large axial strut spacing, blunt corners at bends, and higher amplitudes exposed smaller area of the artery to high stresses, while keeping enough radial force that is enough to keep the lumen open and restore flow. The mentioned articles were reviewed along with several others and they were used to characterize and design the self-expanding stent for this investigation. In this chapter, endovascular stenting and its effect on vascular arteries as well as how to design an optimum stent was reviewed.

A study summarizing the stent grafts that inhibited the growth of the arteries in rapid growing piglets was investigated. Also, clinical studies in children was reviewed and reported that a commercially available self-expanding stent grew with the artery; however, stents migrated in two cases and in other cases these stents caused significant stenosis and obstruction of the lumen in the patients. The effect of the chronic outward force on the lumen of the artery and how over stretching the arteries can cause neointima proliferation was reviewed. In addition, several papers discussing the requirements of a stent for pediatric application as well as how to design an optimum stent that can distribute the force and minimizes the damage to the arterial wall was reviewed. Utilizing all the findings we attempted to design a stent that can grow with small rapid growing arteries and induces the least response. Four potential pediatric self-expanding stent designs with varying numbers of struts, width, thickness, shape, length and architecture were created using Creo Parametric CAD as shown in Figure 1. The crimp profile of each design was simulated using SIMULIA Abaqus FEA software . Through crimp profile simulation, each design underwent iterations by adjusting the number of struts, width, and thickness in order to achieve the following pre-determined traits: crimp profile of < 6Fr, unconstraint diameter of 20mm, and length of 15 to 20mm with a radial force able to withstand vessel recoil after angioplasty. Radio-opacity for visualization under fluoroscopy was also a required but was not simulated.

A stent design with a single row, high amplitude, and low number of struts was selected that could be easily crimped to <6 Fr as indicated by an arrow in Figure 3.1. This design served as the basis for sub-selection of specific candidate stents. All histopathology analysis was performed at CVPath Institute Inc . Before processing for the histology, digital photograph was taken of the vessel and obtained Faxitron digital radiographs in the anterior-posterior and the lateral views. The radiographs demonstrated four nitinol bare metal stents, two measuring 15 mm long and two 20mm long and 10 to 18 mm in greatest diameter for 180 days study and two stents each 15mm length and 12 to 13mm in greatest diameter for 90 days study. An approximate 5 mm non-stented segment was present between the stents. The stents were submitted for embedding in Spurr resin and sectioning by the Exakt method. Proximal, mid, and distal non-stented aortic segments were submitted for paraffin embedding and routine histologic sectioning. To prepare the samples for plastic histology the stented aortic segments were dehydrated in a graded series of ethanol and infiltrated and embedded them in Spurr resin. After polymerization, transverse sections were sawed approximately 4 millimeters in thickness from the stents. Final slides were grounded from each of the plastic blocks to a final thickness of 19 to 90 microns using EXAKT Linear Grinding Technology. Each sample then polished and stained ground sections with hematoxylin and eosin . The mid-section of each stented segment was stained with Trichrome staining. All sections were examined by light microscopy for vessel wall integrity and inflammatory response. Proximal, mid, and distal non-stented aortic segments were submitted for paraffin embedding and routine histologic sectioning. After dehydration in a graded series of ethanol and infiltration with paraffin, the transverse sections for each segment were cut. Each block was sectioned at 4-6 microns and mounted them onto slides and stained with hematoxylin and eosin and Movat’s Pentachrome . All sections were examined by light microscopy for vessel wall integrity and inflammatory response. Representative fabricated self-expanding stents were tested in the radial force tester as explained in the method section and the hysteresis for each stent was generated . The angiographic images were analyzed, and the vessel diameter was measured for each stent prior to the implantation and after the duration of the study as explained in the method section. From the radial force study and the hysteresis results it was possible to find the amount of force exerted on the vessel at the time of implantation as reported in Table 4.1. The growth measurements and the stent chronic outward forces at the time of implantation was plotted in Figure 4.4. A strong correlation between the vessel growth and the stent force was not identified, rather a correlation between the location of the stent and growth and injury was observed. The low force stents in the distal side of the artery grew more than the high force stents in the proximal side. Stenting has emerged as a generally superior option as compared to balloon angioplasty and surgical repair for CoA in infants and children. Nevertheless, square pot the exponential growth of the arteries in children limits the use of stents and requires serial stent redialation and sometimes even fracture or surgical removal. Thus, among pediatric interventional cardiologists, there is a high level of interest in stents that can resorb or grow with the artery. Such stents could eliminate or reduce future reinterventions. This study represents the first effort to evaluate the effects of a purpose-built self-expanding stents on rapidly growing vessels. A range of novel self-expanding nitinol stents were specifically designed and manufactured and used to examine the effects of radial force and stents geometry on the biology of rapidly growing arteries.By varying the geometry and thickness of the nitinol in the stents, four stents with a variety of radial forces were designed, manufactured and tested. The outward force of each stent was measured at each diameter and used to correlate the effects of radial force on biology. These custom-made novel stents easily and reliably crimped and deployed in all the animals with good apposition to the aortic wall.

None of the stents limited arterial growth and there was continuing stent expansion with time, without erosion of the stents completely through the vessels. On average stented vessels grew 14% and 26% more in diameter at 90 and 180 days respectively than the distal and proximal non-stented segments of the vessels, suggesting that the force against the stented artery segments was higher than needed in all cases. The small vessels grew to larger degrees as compared to larger vessels . The experience with these stents suggests that even lower radial force stents may be ideal for this application. There was a favorable neointimal response and no aneurysm was noted in any of the stented vessels. Thus, angiographic results of each implantation universally showed that the stents were able to grow with and beyond the native arteries.Neointimal in growth after use of self-expanding stent has been reported to lead to the narrowing or stenosis of the arterial lumen, thus reducing the luminal area. Compression and tension by the stent struts, wall injury, and peri-strut inflammation due to responses to a foreign body object can cause in-stent stenosis as well as a disruption to the arterial wall leading to long term aneurysms and dissections. All the stents tested in this study formed a mature neointima layer around the stent struts and none had significant luminal stenoses . However, a wide range of damage to the IEL and media was observed: Figure 5.1A shows stent 4 in the iliac artery, with IEL and media laceration. Furthermore, Figure 5.1B shows Stent 4 in the abdominal aorta with compressed but intact IEL and media. All stented segments showed patency without any intraluminal thrombus or obstruction, with ˂20% stenosis in the worst case, despite compression and injuries of the IEL and the medial layer at 90 and 180 days. The long-term effects of the medial lacerations could not be assessed in a six month study. Fortunately, early re-endothelialization was ubiquitous: there was 100% endothelialization of all stents. The radial force of the stents could not be correlated with the stent’s effect on histopathology. No significant correlation was observed between the neointima formation and the forces in the designed stents. Overall injury, and inflammation, value for each stented section were scored according to Schwartz et al.’s scoring scheme . These criteria have been widely used in stent literatures. High injury scores, particularly scores of 2–3, have been reported to yield thicker neointima formation in the porcine coronary arteries. Because the force on each stented artery was a function of both the stent type as well as the diameter of the stented vessel, an attempt was made to correlate radial force with vascular injury and histopathology. While the outward force of the stents did not correlate to biological response, it was noted that smaller arteries in general had higher levels of injury and stenosis regardless of stent force. The mean average injury score was comparable among all stents with higher percent stenosis for stents on the distal side of the abdominal aorta. It is hoped that the data presented in this study will aid in the design of the ideal self expanding pediatric stent. Clearly, this observations in this limited study support the idea that such a device has the potential to improve outcomes in pediatric stenting. Nonetheless, many parameters need to be optimized in designing a pediatric self-expanding stent. This stent needs to have the ability to deploy via a 4-5 Fr system and then expand to 14-20 mm without overstretching the arterial lumen and causing stenosis, medial laceration or unwanted inflammatory responses. It needs to have enough force to at least growth with the vessel even after neointima formation. In this study, the stents in smaller vessels had higher mean nominal stent diameter to artery diameter ratios and higher degrees on medial injury. However, the long-term consequences of this medial injury remain unknown and it can be mitigated using lower radial force stents.