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- All Subjects: Nutrition
- All Subjects: Materials Science
- Creators: Wharton, Christopher (Christopher Mack), 1977-
- Member of: Theses and Dissertations
Description
Fruit and vegetable (FV) consumption continues to lag far behind US Department of Agriculture (USDA) recommendations. Interventions targeting individuals' dietary behaviors address only a small fraction of dietary influences. Changing the food environment by increasing availability of and excitement for FV through local food production has shown promise as a method for enhancing intake. However, the extent to which local production is sufficient to meet recommended FV intakes, or actual intakes, of specific populations remains largely unconsidered. This study was the first of its kind to evaluate the capacity to support FV intake of Arizona's population with statewide production of FV. We created a model to evaluate what percentage of Dietary Guidelines for Americans (DGA) recommendations, as well as actual consumption, state-level FV production could meet in a given year. Intake and production figures were amended to include estimates of only fresh, non-tropical FV. Production was then estimated by month and season to illustrate fluctuations in availability of FV. Based on our algorithm, Arizona production met 184.5% of aggregate fresh vegetable recommendations, as well as 351.9% of estimated intakes of Arizonans, but met only 29.7% of recommended and 47.8% of estimated intake of fresh, non-tropical fruit. Much of the excess vegetable production can be attributed to the dark-green vegetable sub-group category, which could meet 3204.6% and 3160% of Arizonans' aggregated recommendations and estimated intakes, respectively. Only minimal seasonal variations in the total fruit and total vegetable categories were found, but production of the five vegetable sub-groups varied between the warm and cool seasons by 19-98%. For example, in the starchy vegetable group, cool season (October to March) production met only 3.6% of recommendations, but warm season (April to November) production supplied 196.5% of recommendations. Results indicate that Arizona agricultural production has the capacity to meet a large proportion of the population's FV needs throughout much of the year, while at the same time remaining a major producer of dark-green vegetables for out-of-state markets.
ContributorsVaudrin, Nicole (Author) / Wharton, Christopher (Christopher Mack), 1977- (Thesis advisor) / Bruening, Meg (Thesis advisor) / Ohri-Vachaspati, Punam (Committee member) / Villalobos, J. Rene (Committee member) / Arizona State University (Publisher)
Created2013
Description
In recent years, overall consumption of meat products has been decreasing, and at the same time vegetarianism is on the rise. A variety of factors are likely driving changes in consumers' attitudes towards, and consumption of, meat products. Although concern regarding animal welfare may contribute to these trends, growing consumer interest in the roles that production and processing of meat play in terms of environmental degradation could also impact individuals' decisions about the inclusion of meat in their diets. Because these factors could be related to moral attitudes as well, the purpose of this study was to explore the relations among meat consumption, general environmental attitudes, and moral `foundations' of decision-making, including concern about minimizing `harm' and maximizing `care,' as well as issues of `purity' and `sanctity.' A survey was conducted among current college students using the New Ecological Paradigm scale and the Moral Foundations Questionnaire to assess environmental and moral attitudes. A food frequency questionnaire was used to assess meat consumption. Multiple linear regression analyses explored the relations of environmental and moral attitudes with meat consumption, controlling for potential confounding variables. The results showed no significant correlations among meat consumption, environmental attitudes or moral foundations of harm/care and purity/sanctity.
ContributorsSpringer, LeeAnn (Author) / Wharton, Christopher (Christopher Mack), 1977- (Thesis advisor) / Hekler, Eric (Thesis advisor) / Ohri-Vachaspati, Punam (Committee member) / Hall, Rick (Committee member) / Arizona State University (Publisher)
Created2013
Description
In October, 2009, participants of the Arizona Special Supplemental Nutrition Program for Women, Infants and Children (WIC) began receiving monthly Cash Value Vouchers (CVV) worth between six and 10 dollars towards the purchase of fresh fruits and vegetables. Data from the Arizona Department of Health Services (ADHS) showed CVV redemption rates in the first two years of the program were lower than the national average of 77% redemption. In response, the ADHS WIC Food List was expanded to also include canned and frozen fruits and vegetables. More recent data from ADHS suggest that redemption rates are improving, but variably exist among different WIC sub-populations. The purpose of this project was to identify themes related to the ease or difficulty of WIC CVV use amongst different categories of low-redeeming WIC participants. A total of 8 focus groups were conducted, four at a clinic in each of two Valley cities: Surprise and Mesa. Each of the four focus groups comprised one of four targeted WIC participant categories: pregnant, postpartum, breastfeeding, and children with participation ranging from 3-9 participants per group. Using the general inductive approach, recordings of the focus groups were transcribed, hand-coded and uploaded into qualitative analysis software resulting in four emergent themes including: interactions and shopping strategies, maximizing WIC value, redemption issues, and effect of rule change. Researchers identified twelve different subthemes related to the emergent theme of interactions and strategies to improve their experience, including economic considerations during redemption. Barriers related to interactions existed that made their purchase difficult, most notably anger from the cashier and other shoppers. However, participants made use of a number of strategies to facilitate WIC purchases or extract more value out of WIC benefits, such as pooling their CVV. Finally, it appears that the fruit and vegetable rule change was well received by those who were aware of the change. These data suggest a number of important avenues for future research, including verifying these themes are important within a larger, representative sample of Arizona WIC participants, and exploring strategies to minimize barriers identified by participants, such as use of electronic benefits transfer-style cards (EBT).
ContributorsBertmann, Farryl M. W (Author) / Wharton, Christopher (Christopher Mack), 1977- (Thesis advisor) / Ohri-Vachaspati, Punam (Committee member) / Johnston, Carol (Committee member) / Hampl, Jeffrey (Committee member) / Dixit-Joshi, Sujata (Committee member) / Barroso, Cristina (Committee member) / Arizona State University (Publisher)
Created2013
Description
This dissertation is on the study of structural and optical properties of some III-V and II-VI compound semiconductors. The first part of this dissertation is a study of the deformation mechanisms associated with nanoindentation and nanoscratching of InP, GaN, and ZnO crystals. The second part is an investigation of some fundamental issues regarding compositional fluctuations and microstructure in GaInNAs and InAlN alloys. In the first part, the microstructure of (001) InP scratched in an atomic force microscope with a small diamond tip has been studied as a function of applied normal force and crystalline direction in order to understand at the nanometer scale the deformation mechanisms in the zinc-blende structure. TEM images show deeper dislocation propagation for scratches along <110> compared to <100>. High strain fields were observed in <100> scratches, indicating hardening due to locking of dislocations gliding on different slip planes. Reverse plastic flow have been observed in <110> scratches in the form of pop-up events that result from recovery of stored elastic strain. In a separate study, nanoindentation-induced plastic deformation has been studied in c-, a-, and m-plane ZnO single crystals and c-plane GaN respectively, to study the deformation mechanism in wurtzite hexagonal structures. TEM results reveal that the prime deformation mechanism is slip on basal planes and in some cases, on pyramidal planes, and strain built up along particular directions. No evidence of phase transformation or cracking was observed in both materials. CL imaging reveals quenching of near band-edge emission by dislocations. In the second part, compositional inhomogeneity in quaternary GaInNAs and ternary InAlN alloys has been studied using TEM. It is shown that exposure to antimony during growth of GaInNAs results in uniform chemical composition in the epilayer, as antimony suppresses the surface mobility of adatoms that otherwise leads to two-dimensional growth and elemental segregation. In a separate study, compositional instability is observed in lattice-matched InAlN films grown on GaN, for growth beyond a certain thickness. Beyond 200 nm of thickness, two sub-layers with different indium content are observed, the top one with lower indium content.
ContributorsHuang, Jingyi (Author) / Ponce, Fernando A. (Thesis advisor) / Carpenter, Ray W (Committee member) / Smith, David J. (Committee member) / Yu, Hongbin (Committee member) / Treacy, Michael Mj (Committee member) / Arizona State University (Publisher)
Created2013
Description
High electron mobility transistors (HEMTs) based on Group III-nitride heterostructures have been characterized by advanced electron microscopy methods including off-axis electron holography, nanoscale chemical analysis, and electrical measurements, as well as other techniques. The dissertation was organized primarily into three topical areas: (1) characterization of near-gate defects in electrically stressed AlGaN/GaN HEMTs, (2) microstructural and chemical analysis of the gate/buffer interface of AlN/GaN HEMTs, and (3) studies of the impact of laser-liftoff processing on AlGaN/GaN HEMTs. The electrical performance of stressed AlGaN/GaN HEMTs was measured and the devices binned accordingly. Source- and drain-side degraded, undegraded, and unstressed devices were then prepared via focused-ion-beam milling for examination. Defects in the near-gate region were identified and their correlation to electrical measurements analyzed. Increased gate leakage after electrical stressing is typically attributed to "V"-shaped defects at the gate edge. However, strong evidence was found for gate metal diffusion into the barrier layer as another contributing factor. AlN/GaN HEMTs grown on sapphire substrates were found to have high electrical performance which is attributed to the AlN barrier layer, and robust ohmic and gate contact processes. TEM analysis identified oxidation at the gate metal/AlN buffer layer interface. This thin a-oxide gate insulator was further characterized by energy-dispersive x-ray spectroscopy and energy-filtered TEM. Attributed to this previously unidentified layer, high reverse gate bias up to −30 V was demonstrated and drain-induced gate leakage was suppressed to values of less than 10−6 A/mm. In addition, extrinsic gm and ft * LG were improved to the highest reported values for AlN/GaN HEMTs fabricated on sapphire substrates. Laser-liftoff (LLO) processing was used to separate the active layers from sapphire substrates for several GaN-based HEMT devices, including AlGaN/GaN and InAlN/GaN heterostructures. Warpage of the LLO samples resulted from relaxation of the as-grown strain and strain arising from dielectric and metal depositions, and this strain was quantified by both Newton's rings and Raman spectroscopy methods. TEM analysis demonstrated that the LLO processing produced no detrimental effects on the quality of the epitaxial layers. TEM micrographs showed no evidence of either damage to the ~2 μm GaN epilayer generated threading defects.
ContributorsJohnson, Michael R. (Author) / Mccartney, Martha R (Thesis advisor) / Smith, David J. (Committee member) / Goodnick, Stephen (Committee member) / Shumway, John (Committee member) / Chen, Tingyong (Committee member) / Arizona State University (Publisher)
Created2012
Description
Health knowledge alone does not appear to lead to sustained healthy behavior, suggesting the need for alternative methods for improving diet. Recent research shows a possible role of moral contexts of food production on diet related behaviors; however no studies have been conducted to specifically explore the relationship between moral constructs and food consumption. This study examined the relationship between fast food consumption and two measures of morality, Moral Foundations Questionnaire (MFQ), specifically harm/care and purity/sanctity foundations, and the Ethical Concern in food choice (EC) questionnaire, which includes animal welfare, environment protection, political values, and religion subscales. The study also examined the association between the measures of morality. 739 participants, primarily female (71.4%) and non-Hispanic Whites (76.5%), completed an online survey that included the MFQ, the EC questionnaire, and a brief fast food screener. Participant's morality scores in relation to their fast food consumption were examined first using bivariate ANOVA analysis and then using logistic regression to control for covariates. The MFQ foundations were compared with the EC subscales using Pearson correlation coefficient. Significant bivariate relationships were seen between fast food consumption and the MFQ's purity/sanctity foundation and EC's religion subscales (p<0.05). However these significant bivariate relationships did not hold after controlling for gender, race, university education, and religion in the logistic regression analysis. The foundations of the MFQ were positively correlated with the subscales for the EC questionnaire (r values ranging from .233-.613 (p<0.01). MFQ's purity/sanctity foundation and EC's religion subscale were the two most highly correlated (r=.613, p<0.01) showing that moral intuitions may be associated with eating decision making. The study did not find significant associations between MFQ or EC scores and fast food consumption.
ContributorsMartinelli, Sarah (Author) / Ohri-Vachaspati, Punam (Thesis advisor) / Hekler, Eric B. (Committee member) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Johnston, Carol (Committee member) / Arizona State University (Publisher)
Created2013
Description
HgCdTe is currently the dominant material for infrared sensing and imaging, and is usually grown on lattice-matched bulk CdZnTe (CZT) substrates. There have been significant recent efforts to identify alternative substrates to CZT as well as alternative detector materials to HgCdTe. In this dissertation research, a wide range of transmission electron microscopy (TEM) imaging and analytical techniques was used in the characterization of epitaxial HgCdTe and related materials and substrates for third generation IR detectors. ZnTe layers grown on Si substrates are considered to be promising candidates for lattice-matched, large-area, and low-cost composite substrates for deposition of II-VI and III-V compound semiconductors with lattice constants near 6.1 Å. After optimizing MBE growth conditions including substrate pretreatment prior to film growth, as well as nucleation and growth temperatures, thick ZnTe/Si films with high crystallinity, low defect density, and excellent surface morphology were achieved. Changes in the Zn/Te flux ratio used during growth were also investigated. Small-probe microanalysis confirmed that a small amount of As was present at the ZnTe/Si interface. A microstructural study of HgCdTe/CdTe/GaAs (211)B and CdTe/GaAs (211)B heterostructures grown using MBE was carried out. High quality MBE-grown CdTe on GaAs(211)B substrates was demonstrated to be a viable composite substrate platform for HgCdTe growth. In addition, analysis of interfacial misfit dislocations and residual strain showed that the CdTe/GaAs interface was fully relaxed. In the case of HgCdTe/CdTe/ GaAs(211)B, thin HgTe buffer layers between HgCdTe and CdTe were also investigated for improving the HgCdTe crystal quality. A set of ZnTe layers epitaxially grown on GaSb(211)B substrates using MBE was studied using high resolution X-ray diffraction (HRXRD) measurements and TEM characterization in order to investigate conditions for defect-free growth. HRXRD results gave critical thickness estimates between 350 nm and 375 nm, in good agreement with theoretical predictions. Moreover, TEM results confirmed that ZnTe layers with thicknesses of 350 nm had highly coherent interfaces and very low dislocation densities, unlike samples with the thicker ZnTe layers.
ContributorsKim, Jae Jin (Author) / Smith, David J. (Thesis advisor) / McCartney, Martha R. (Committee member) / Alford, Terry L. (Committee member) / Crozier, Peter A. (Committee member) / Arizona State University (Publisher)
Created2012
Description
Background: Previous research suggests a healthy eater schema (i.e., identifying yourself as a healthy eater) may be a useful concept to target in interventions. A "stealth" intervention that discussed the moral issues related to food worked better at promoting healthful eating than an intervention focused on the health benefits. No research has explored the relationship between moral foundations, a theoretical model focused on delineating core "foundations" for making a moral decision, and healthy eater self-identity or self-efficacy. Purpose: We explored the relationship between moral foundations (i.e., harm/care, fairness/reciprocity, in-group/loyalty, authority/respect, & purity/sanctity) and health eater self-identity and fruit and vegetable self-efficacy (FVSE). Methods: 542 participants completed an online cross-sectional survey, which included moral foundations (i.e., MFQ), political views, healthy eater self-identity (i.e., HESS), and FVSE measures. Logistic regression was used to assess the relationship between moral foundations between healthy eater self-identity after controlling for age, gender, major, BMI, and political beliefs. OLS regression was used to explore the relationship between self-efficacy and the moral foundations after controlling for the covariates. Results: 75.6% of the sample were college students, with a mean age of 25.27 (SD=8.61). 25.1% of students were nutrition majors. Harm/care, authority/respect, and ingroup/loyalty were significantly associated with healthy eater schema, (i.e., OR=1.7, p<.001, OR=1.5, p=.009, and OR=1.4, p=.027, respectively). Ingroup/loyalty, authority/respect, and purity/sanctity were related to FVSE (p=.006, p=.002, p=.04, respectively). Conclusion: Among college students, harm/care and authority/respect were associated with a healthy eater schema. Future research should explore possible uses of these moral foundations in interventions (e.g., a plant-based diet based on reduced harm to animals or eating fewer processed views based on "traditional" values).
ContributorsKiser, Sarah (Author) / Hekler, Eric B. (Thesis advisor) / Ohri-Vachaspati, Punam (Committee member) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Johnston, Carol (Committee member) / Arizona State University (Publisher)
Created2013
Description
The increase in obesity since the 1980's has been associated with fast-food consumption. In hopes that calorie labeling will be an effective tool to combat obesity, congress included a provision in the Patient Protection and Affordable Care Act of 2010 (ACA) that will require all restaurants with twenty or more locations to post calorie information for each menu item. Current research has provided mixed results regarding the effectiveness of calorie labeling, but overall seems to suggest that calorie labeling may only be effective among certain populations. In September, 2012 McDonald's began to post calorie labels on their menu boards before it was federally mandated under the ACA. This policy provided the opportunity to study the impact of calorie labeling on the purchasing behavior of McDonald's patrons. This cross-sectional study was designed to determine if self-perception of diet, self-perception of health, smoking, physical activity, fruit and vegetable intake, or knowledge of daily calorie requirements is associated with the likelihood of noticing or using calorie labels, or total calories purchased. In addition, relationships between noticing or using calorie labels with total calories purchased were also examined. Receipts and survey responses were collected from 330 participants who purchased food and beverage items from 27 different McDonald's locations within a 20 mile radius of downtown Phoenix, Arizona. Results indicated that only 16.1% of the sample reported using calorie labels, and those who reported using calorie labels purchased an average of 136 fewer calories. Multivariate analysis indicated there were no statistically significant relationships between self-perception of diet, self-perception of health, smoking, physical activity, fruit and vegetable intake, or knowledge of daily calorie requirements with the likelihood of noticing or using calorie labels, or total calories purchased. However, it is possible that the small sample size of participants using calorie labeling precluded any statistically significant relationships among these variables from emerging. Further research with larger sample sizes should be conducted, to investigate individual level factors that may be associated with use of calorie labeling.
ContributorsBrown, Alan (Author) / Ohri-Vachaspati, Punam (Thesis advisor) / Bruening, Meredith (Committee member) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Arizona State University (Publisher)
Created2013
Description
The research described in this dissertation involved the use of transmission electron microscopy (TEM) to characterize II-VI and III-V compound semiconductor quantum dots (QDs) and dilute-nitride alloys grown by molecular beam epitaxy (MBE) and intended for photovoltaic applications. The morphology of CdTe QDs prepared by the post-annealing MBE method were characterized by various microscopy techniques including high-resolution transmission electron microscopy (HR-TEM), and high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM). Extensive observations revealed that the of QD shapes were not well-defined, and the QD size and spatial distribution were not determined by the amount of CdTe deposition. These results indicated that the formation of II-VI QDs using a post-annealing treatment did not follow the conventional growth mechanism for III-V and IV-IV materials. The structural properties of dilute-nitride GaAsNx films grown using plasma-assisted MBE were characterized by TEM and HAADF-STEM. A significant amount of the nitrogen incorporated into the dilute nitride films was found to be interstitial, and that fluctuations in local nitrogen composition also occurred during growth. Post-growth partial relaxation of strain resulted in the formation of {110}-oriented microcracks in the sample with the largest substitutional nitrogen composition. Single- and multi-layered InAs QDs grown on GaAsSb/GaAs composite substrates were investigated using HR-TEM and HAADF-STEM. Correlation between the structural and optoelectronic properties revealed that the GaAsSb barrier layers had played an important role in tuning the energy-band alignments but without affecting the overall structural morphology. However, according to both XRD measurement and electron microscopy the densities of dislocations increased as the number of QD layers built up. An investigation of near-wetting layer-free InAs QDs incorporated with AlAs/GaAs spacer layers was carried out. The microscopy observations revealed that both embedded and non-embedded near-wetting layer-free InAs QDs did not have well-defined shapes unlike conventional InAs QDs. According to AFM analysis and plan-view TEM characterization, the InAs QDs incorporated with spacer layers had smaller dot density and more symmetrical larger sizes with an apparent bimodal size distribution (two distinct families of large and small dots) in comparison with conventional InAs QDs grown without any spacer layer.
ContributorsTang, Dinghao (Author) / Smith, David J. (Thesis advisor) / Crozier, Peter A. (Committee member) / Liu, Jingyue (Committee member) / Mccartney, Martha R (Committee member) / Arizona State University (Publisher)
Created2014