Research is needed that examines theory-based risk factors for suicide in older adults. The interpersonal theory of suicide (Joiner, 2005; Van Orden et al., 2010) provides specific hypotheses regarding variables that contribute to the development and variability in death ideation and suicide ideation; however, data suggest that older adults may not report suicide ideation in research settings or to treatment providers even when they experience it (Heisel et al., 2006). The purpose of this study was to test theory-based predictions regarding variables that contribute to death ideation (i.e., a passive wish to die) and suicide ideation in older adults. This study introduces the application of zero-inflated negative binomial regression (ZINB) to the study of suicidal behavior. ZINB was used to test theory-based predictions, while also testing a hypothesis regarding variables associated with denial of suicide ideation among participants who endorsed risk factors associated with suicide risk. Participants included 239 adults aged 60 and older recruited from primary care clinics who completed a variety of self-report instruments. The results of this study indicated that perceived burdensomeness and hopelessness were significantly associated with variability in death ideation. Additional results indicated that elevated scores on thwarted belonging, the interaction between perceived burdensomeness and hopelessness, and the interaction between thwarted belonging and perceived burdensomeness were associated with a significant reduction in the probability of a participant being a suicide ideator. These results offer substantial support for the interpersonal theory of suicide. The implications of these findings are discussed.
Ecolabeling allows firms to segment a market by informing consumers about unobservable attributes of a product. Previous studies evaluate consumer preferences for products explicitly labeled as possessing positive environmental attributes. This research evaluates consumers’ willingness to pay for a product that is perceived by the consumer as having environmentally friendly attributes. We explore glass packaging for fluid milk as a case study. Data were collected through a contingent valuation survey, and a bound-and-a-half logit model was employed. The estimated premium is 59.78 cents with a premium between $0.73 and $0.92 for consumers more likely to prefer the glass alternative.
Sustainable feed formulation (defined here as nutritional and economic feed optimization) is substantial in feed chain production from crop farmers to livestock producers. Diet formulation employing a static linear programming (LP) approach, which is widely used in trading firms and feed production facilities, does not allow for intertemporal flexibility. Our approach allows the interaction between feed components over time, considering the volatile global feed prices, thereby improving sustainability in feed formulation and feed availability. The objectives of this study were to (1) develop a multi-stage LP feed model, (2) demonstrate its potential use in broiler feeding, and (3) illustrate the impact of feed input price spread (variation) on the composition of broiler diets. Modeling resulted in reciprocal relationships between conventional feeds and byproducts at different rates. Based on the price spreads expressed as a percentage of DDGS (distiller's dried grains with solubles) price compared to corn price, three positions of dietary switch were identified; corn-DDGS price spreads of higher than 94%, between 76 and 94%, and lower than 76% corresponding to limited/no inclusion, partial inclusion, and maximum replacement of corn by DDGS, respectively. Rapeseed meal inclusion was 4, 5, and 6% in the corn-based starter, grower, and finisher diets, respectively, and its potential to replace soybean meal was limited by its higher fiber content. Based on the simulated compound feed prices, the global broiler feed industry could gain 1.7 billion USD through improved resources planning.
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