The Supplemental Nutrition Assistance Program and Food Insecurity

This chapter reviews recent theory and empirical evidence regarding the effect of SNAP on food insecurity and replicates the modelling strategies used in the empirical literature. The authors find that recent evidence suggesting an ameliorative effect of SNAP on food insecurity may not be robust to specification choice or data. Most specifications mirror the existing literature in finding a positive association of food insecurity with SNAP participation. Two-stage least squares and control function methods do show that SNAP reduces food insecurity, but effects are not consistent across sub-populations and are not always statistically significant

Child Injuries and the Timing of SNAP Benefits Receipt

The Supplemental Nutrition Assistance Program (SNAP) is an important federal resource that provides nutritional assistance to low-income families. Timing of SNAP benefits can reduce childhood injuries

Three essays in health and nutrition economics

This dissertation focuses on aspects of behavior and public policy related to vulnerable populations. The first essay, coauthored with Christian Gregory and David C. Ribar, reviews recent theory and empirical evidence regarding the effect of Supplemental Nutrition Assistance Program (SNAP) participation on food insecurity and replicates the modelling strategies used in the empirical literature. We find that recent evidence suggesting the ameliorative effect of SNAP on food insecurity may not be robust to specification choice or data. Most specifications mirror the existing literature in finding a positive association of food insecurity with SNAP participation. Two-stage least squares and control function methods do show that SNAP reduces food insecurity, but effects are not consistent across sub-populations and are not always statistically significant. In the second essay, I examine the relationship between SNAP participation and food insecurity using data from the 2001-2008 Current Population Survey (CPS-FSS). A behavioral Rasch selection model is proposed and estimated using four subsamples of low-income households: unmarried parent households, married parent households, all-elderly households, and other adult-only households. The behavioral Rasch selection model assumes responses to multiple food hardship questions may be modelled as indicators of a single underlying index of food hardships, and concurrently, controls for the endogeneity of program participation. Simultaneously modelling the outcomes this way leads to more efficient estimation. The models are identified using exogenous changes in state-level polices related to SNAP. The results suggest that SNAP has a strong ameliorative effect on food insecurity for married parent households, all-elderly households, and other adult-only households, while SNAP continues to be associated with greater food hardships for unmarried parent households. Participating in SNAP reduces the probability of food insecurity by 22.4% for other adult-only households, 18% for all-elderly households, and 17% for married parent households. The third and final essay examines the relationship between underage college drinking and the initial occupational choices of male college graduates using data from the National Longitudinal Survey of Youth 1997 (NLSY97). Focusing on recent college graduates and their initial occupational choices allows me to address important timing issues not considered by the existing literature. For the multivariate analyses, I estimate multinomial logistic models of occupational choice, where the occupational choice set is specified as employed full-time in white collar occupations, other occupations, enrolled in school, and neither in school nor employed full-time. In addition, I estimate multinomial logistic selection models that control for the potential endogeneity of underage drinking. The results suggest underage college drinking is not associated with young men's initial occupational choices, with the exception of the decision to be enrolled in school. Young men with any underage college days where they drank two or more drinks are 28.9% less likely to be enrolled in school after completing a bachelor's degree

Tailoring absorptivity of highly reflective Ag powders by pulsed-direct current magnetron sputtering for additive manufacturing processes

Processing of highly reflective and high thermally conductive materials (Cu, Ag, etc.) by laser powder bed fusion (LPBF) is of increasing interest to broaden the range of materials that can be additively manufactured. However, these alloys are challenged by high reflectivity resulting in unmelted particles and porosity. This is exacerbated for in-situ alloying techniques, where divergent optical properties of blended powders further narrow the stable processing window. One possible route to improved uniformity of initial melting is through coating powders with an optically absorptive layer. In-situ alloying of Ti-Ag was chosen as a model to assess this, given the potential of Ti-Ag as a novel antimicrobial biomedical alloy, facilitating an ideal model to assess this approach. High purity Ag powder was coated with Ti via physical vapour deposition. Barriers to reliable coating were investigated, with agglomeration of particles observed at a sputtering power of 100 W. In-situ laser micro calorimetry demonstrated a significant improvement in melting performance for coated Ag powder, with continuous tracks attained at 280 W vs. 320 W for uncoated powder, and absorptivity increasing from 27 % to 45 % at 320 W incident laser power. Subsequent in-situ alloying of the Ag powder when blended with commercially pure Ti powder demonstrated that improved absorptivity allowed for more uniform densification of the blended powder bed at lower energy density (0.7 ± 1.0 vs 7.1 ± 2.0 % porosity at 133 J.m-1). Ultimately, this offers a promising route to improved alloy development via LPBF, through application of a homogeneous, relevant coating

Pharmacological Fingerprints of Contextual Uncertainty

Successful interaction with the environment requires flexible updating of our beliefs about the world. By estimating the likelihood of future events, it is possible to prepare appropriate actions in advance and execute fast, accurate motor responses. According to theoretical proposals, agents track the variability arising from changing environments by computing various forms of uncertainty. Several neuromodulators have been linked to uncertainty signalling, but comprehensive empirical characterisation of their relative contributions to perceptual belief updating, and to the selection of motor responses, is lacking. Here we assess the roles of noradrenaline, acetylcholine, and dopamine within a single, unified computational framework of uncertainty. Using pharmacological interventions in a sample of 128 healthy human volunteers and a hierarchical Bayesian learning model, we characterise the influences of noradrenergic, cholinergic, and dopaminergic receptor antagonism on individual computations of uncertainty during a probabilistic serial reaction time task. We propose that noradrenaline influences learning of uncertain events arising from unexpected changes in the environment. In contrast, acetylcholine balances attribution of uncertainty to chance fluctuations within an environmental context, defined by a stable set of probabilistic associations, or to gross environmental violations following a contextual switch. Dopamine supports the use of uncertainty representations to engender fast, adaptive responses. \ua9 2016 Marshall et al

Comparing Food Insecurity Among the U.S. Military and Civilian Adult Populations

Readiness is a cornerstone of military service. Military readiness includes cognitive and physical abilities to train and execute missions. Previous studies among civilians demonstrate that food security is associated with cognitive function and body mass index. Therefore, food security is vital to maintaining military readiness. While no analyses have been conducted on the prevalence of food insecurity for a representative sample of the active duty U.S. military, studies of individual military installations have demonstrated food insecurity rates between 15 and 33 percent. The authors compared food insecurity among the U.S. military and civilian adult populations, using data from the 2018 and 2020 Status of Forces Survey of Active Duty Members and the Current Population Survey Food Security Supplement. A weighting procedure was used to ensure the military and civilian adult populations were demographically equivalent. The findings show that the prevalence of food insecurity was 25.3 percent among the military population compared with 10.1 percent among a demographically equivalent civilian adult population. A more severe form of food insecurity, very low food security, was estimated to be 10.5 percent of the military population in 2018 and 2020, compared with 3.6 percent of the comparable civilian adult population during this period. The findings demonstrate that the military population is at elevated risk for food insecurity and that food insecurity measures can be used to reliably construct measures of active duty service members’ food insecurity for monitoring and research purposes

Comparing Food Insecurity Among the U.S. Military and Civilian Adult Populations

Readiness is a cornerstone of military service. Military readiness includes cognitive and physical abilities to train and execute missions. Previous studies among civilians demonstrate that food security is associated with cognitive function and body mass index. Therefore, food security is vital to maintaining military readiness. While no analyses have been conducted on the prevalence of food insecurity for a representative sample of the active duty U.S. military, studies of individual military installations have demonstrated food insecurity rates between 15 and 33 percent. The authors compared food insecurity among the U.S. military and civilian adult populations, using data from the 2018 and 2020 Status of Forces Survey of Active Duty Members and the Current Population Survey Food Security Supplement. A weighting procedure was used to ensure the military and civilian adult populations were demographically equivalent. The findings show that the prevalence of food insecurity was 25.3 percent among the military population compared with 10.1 percent among a demographically equivalent civilian adult population. A more severe form of food insecurity, very low food security, was estimated to be 10.5 percent of the military population in 2018 and 2020, compared with 3.6 percent of the comparable civilian adult population during this period. The findings demonstrate that the military population is at elevated risk for food insecurity and that food insecurity measures can be used to reliably construct measures of active duty service members’ food insecurity for monitoring and research purposes

SNAP Households Adjust Their Expenditures and How They Spend Their Time in Response to Changes in Program Benefits

The American Recovery and Reinvestment Act of 2009 (ARRA) mandated higher monthly benefits for households participating in USDA’s Supplemental Nutrition Assistance Program (SNAP). Subsequent legislation ended these higher benefits in November 2013. Researchers found that SNAP households spent less time on food shopping and meal preparation and more time in income-generating work following the sunset of the higher ARRA-mandated benefits

SNAP Households Adjust Their Expenditures and How They Spend Their Time in Response to Changes in Program Benefits

The American Recovery and Reinvestment Act of 2009 (ARRA) mandated higher monthly benefits for households participating in USDA’s Supplemental Nutrition Assistance Program (SNAP). Subsequent legislation ended these higher benefits in November 2013. Researchers found that SNAP households spent less time on food shopping and meal preparation and more time in income-generating work following the sunset of the higher ARRA-mandated benefits