4,541 research outputs found

    The Impacts of Food Safety Information on Meat Demand: A Cross-Commodity Approach Using U.S. Household Data

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    The potential impacts of a food safety event on consumer demand for meat is of significant concern to producers, packers, processors, retail businesses, and the USDA. This study investigates whether publicized food safety information from the printed media on beef, pork, and poultry, impacts the demand for these commodities. A four commodity complete demand system is employed using monthly household level data on meat purchases collected by the Nielsen Company, with separate food safety indices incorporated for beef, pork, and poultry. Results from the analysis indicate that consumers purchase relatively high levels of pre-committed quantities of pork, chicken, and turkey, while beef consumption appears to be primarily from supernumerary expenditures. The results also indicate that seasonal demand patterns are statistically significant in explaining the quantity of meat and poultry demanded. However, the food safety variables are not jointly statistically significant from zero.Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,

    Application of digital particle image velocimetry to insect aerodynamics: measurement of the leading-edge vortex and near wake of a Hawkmoth.

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    Some insects use leading-edge vortices to generate high lift forces, as has been inferred from qualitative smoke visualisations of the flow around their wings. Here we present the first Digital Particle Image Velocimetry (DPIV) data and quantitative analysis of an insect’s leading-edge vortex and near wake at two flight speeds. This allows us to describe objectively 2D slices through the flow field of a tethered Tobacco Hawkmoth (Manduca sexta). The near-field vortex wake appears to braodly resemble elliptical vortex loops. The presence of a leading-edge vortex towards the end of the downstroke is found to coincide with peak upward force production measured by a six-component force–moment balance. The topology of Manduca’s leading-edge vortex differs from that previously described because late in the downstroke, the structure extends continuously from wingtip across the thorax to the other wingtip

    Shaped nozzles for cryogenic buffer gas beam sources

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    Cryogenic buffer gas beams are important sources of cold molecules. In this work we explore the use of a converging-diverging nozzle with a buffer-gas beam. We find that, under appropriate circumstances, the use of a nozzle can produce a beam with improved collimation, lower transverse temperatures, and higher fluxes per solid angle

    Relational efficacy beliefs in physical activity classes: a test of the tripartite model

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    This study explored the predictive relationships between students’ (N = 516, Mage = 18.48, SD = 3.52) tripartite efficacy beliefs and key outcomes in undergraduate physical activity classes. Students reported their relational efficacy perceptions (i.e., other-efficacy and relation-inferred self-efficacy, or RISE) with respect to their instructor before a class, and instruments measuring self-efficacy, enjoyment, and effort were administered separately following the class. The following week, an independent observer assessed student achievement. Latent variable path analyses that accounted for nesting within classes revealed (a) that students were more confident in their own ability when they reported favorable other-efficacy and RISE appraisals, (b) a number of direct and indirect pathways through which other-efficacy and RISE predicted adaptive in-class outcomes, and (c) that self-efficacy directly predicted enjoyment and effort, and indirectly predicted achievement. Although previous studies have examined isolated aspects within the tripartite framework, this represents the first investigation to test the full range of direct and indirect pathways associated with the entire model

    In vivo parasitological measures of artemisinin susceptibility

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    Parasite clearance data from 18,699 patients with falciparum malaria treated with an artemisinin derivative in areas of low (n=14,539), moderate (n=2077), and high (n=2083) levels of malaria transmission across the world were analyzed to determine the factors that affect clearance rates and identify a simple in vivo screening measure for artemisinin resistance. The main factor affecting parasite clearance time was parasite density on admission. Clearance rates were faster in high-transmission settings and with more effective partner drugs in artemisinin-based combination treatments (ACTs). The result of the malaria blood smear on day 3 (72 h) was a good predictor of subsequent treatment failure and provides a simple screening measure for artemisinin resistance. Artemisinin resistance is highly unlikely if the proportion of patients with parasite densities of <100,000 parasites/microL given the currently recommended 3-day ACT who have a positive smear result on day 3 is <3%; that is, for n patients the observed number with a positive smear result on day 3 does not exceed (n + 60)/24

    Experiences and barriers to Health-Related Quality of Life following liver transplantation: a qualitative analysis of the perspectives of pediatric patients and their parents

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    This paper examines health-related quality of life (HRQOL) experiences and barriers facing young people who have received a liver transplant (LT). Semi-structured qualitative interviews were conducted with children and adolescents who have undergone LT and their parents. Findings indicate that LT fosters substantially improved child and adolescent HRQOL; however, young people also experience challenges such as difficulties with medication compliance, self-management of care routines, physical activity restrictions, and undesirable medical procedures. Implications and recommendations for clinical practice and research are discussed

    Computation in Classical Mechanics

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    There is a growing consensus that physics majors need to learn computational skills, but many departments are still devoid of computation in their physics curriculum. Some departments may lack the resources or commitment to create a dedicated course or program in computational physics. One way around this difficulty is to include computation in a standard upper-level physics course. An intermediate classical mechanics course is particularly well suited for including computation. We discuss the ways we have used computation in our classical mechanics courses, focusing on how computational work can improve students' understanding of physics as well as their computational skills. We present examples of computational problems that serve these two purposes. In addition, we provide information about resources for instructors who would like to include computation in their courses.Comment: 6 pages, 3 figures, submitted to American Journal of Physic

    The Eyes Have It: Measuring Spatial Orientation in Virtual Worlds to Explain Gender Differences in Real Ones

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    Here, we explore how 3D, networked virtual worlds - in particular Second Life, which enables users to create and modify their own environments - can act as a kind of \u27virtual\u27 laboratory for studying gender difference. By tracking users\u27 eye movements as they navigate a virtual rendition of the Morris Water Maze (the \u27gold standard\u27 for measuring gender difference in spatial orientation, navigation and mobility), this work constitutes an empirical basis for claims that we have attempted to make in the context of ethnographic work with female and male video game players, both novice and expert: that mastery of, and the ability to competently navigate through space, both real and virtual, is as much (if not more) learned and acquired, as it inheres in the bodies and brains of differently-sexed subjects
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