6,417 research outputs found

    HOUSEHOLD SIZE AND COMPOSITION IMPACTS ON MEAT DEMAND IN MEXICO: A CENSORED DEMAND SYSTEM APPROACH

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    The proposed paper adopts the censored demand system approach of Lee and Pitt (1986) to examine the structure of Mexican food demand. This approach uses the concept of virtual prices to explain specific purchase patterns. The contribution of our selected paper is the incorporation of the endogenous equivalence scale function proposed by Phlipps (1998) within this censored system. The contribution of this analysis is not only in terms of the use of an endogenous scaling function within a censored demand system, but we also will be use simulated maximum likelihood techniques which allows for the specification and estimation of significantly larger sized demand systems without the imposition of restrictive distributional assumptions on the equation error terms. We use a Gibbs sampling techniques to evaluate higher order truncated distributions required to implement the Lee and Pitt (1986) model specification.Demand and Price Analysis,

    A Workshop About Land-Use Decision-Making in the Context of Community/Societal Values

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    Community based land-use decision-making is often left to an oligarchy who are familiar with the planning process. Stakeholders are frequently under-represented, possibly because of their unwillingness to participate due to the unfamiliarity with the process. The workshop described here develops participants\u27 understanding of a land-use planning process and the complexity of socio-economic values using individual reflection and shared perspective through writing, model-making, presentations, and discussions. Using consensus-building strategies, along with a documentary film, participants engage in several hands-on group activities. Shared values in combination with new community perspectives are realized through a series of workshop activities

    Abracadabra, Making the Visible Less Visible: Reducing the Effects of Stigma Through Invisible Work

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    Dirty work involves tasks that are considered disgusting or degrading. Individuals engaged in dirty work are often stigmatized, and this stigma may negatively affect the workers’ job-related attitudes. Although dirty work is often cast in a negative light, we explore an aspect of jobs that might lessen the detrimental effects of performing dirty work: invisibility. Using a sample of 329 working adults, we investigate the impact of invisibility on job satisfaction and occupational identification of marginalized dirty workers. Results indicate that performing dirty work, and being marginalized, each negatively impact job-related attitudes. In dirty occupations, relationships were weaker for employees reporting higher levels of invisibility with invisible employees reporting higher levels of occupational identification than their more visible counterparts. These findings shed new light on developing positive workplace experiences by suggesting that invisibility may be the key to reducing the stigmas associated with dirty work. Theoretical implications, directions for future research, and practical implications are discussed

    The Influence of Fallback Foods on Great Ape Tooth Enamel

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    Lucas and colleagues recently proposed a model based on fracture and deformation concepts to describe how mammalian tooth enamel may be adapted to the mechanical demands of diet (Lucas et al.: Bioessays 30[2008] 374-385). Here we review the applicability of that model by examining existing data on the food mechanical properties and enamel morphology of great apes (Pan, Pongo, and Gorilla). Particular attention is paid to whether the consumption of fallback foods is likely to play a key role in influencing great ape enamel morphology. Our results suggest that this is indeed the case. We also consider the implications of this conclusion on the evolution of the dentition of extinct hominins

    Fracture in teeth—a diagnostic for inferring bite force and tooth function

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    Teeth are brittle and highly susceptible to cracking. We propose that observations of such cracking can be used as a diagnostic tool for predicting bite force and inferring tooth function in living and fossil mammals. Laboratory tests on model tooth structures and extracted human teeth in simulated biting identify the principal fracture modes in enamel. Examination of museum specimens reveals the presence of similar fractures in a wide range of vertebrates, suggesting that cracks extended during ingestion or mastication. The use of ‘fracture mechanics’ from materials engineering provides elegant relations for quantifying critical bite forces in terms of characteristic tooth size and enamel thickness. The role of enamel microstructure in determining how cracks initiate and propagate within the enamel (and beyond) is discussed. The picture emerges of teeth as damage-tolerant structures, full of internal weaknesses and defects and yet able to contain the expansion of seemingly precarious cracks and fissures within the enamel shell. How the findings impact on dietary pressures forms an undercurrent of the study

    Stellar Population Models and Individual Element Abundances. I. Sensitivity of Stellar Evolution Models

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    Integrated light from distant galaxies is often compared to stellar population models via the equivalent widths of spectral features—spectral indices—whose strengths rely on the abundances of one or more elements. Such comparisons hinge not only on the overall metal abundance, but also on relative abundances. Studies have examined the influence of individual elements on synthetic spectra but little has been done to address similar issues in the stellar evolution models that underlie most stellar population models. Stellar evolution models will primarily be influenced by changes in opacities. In order to explore this issue in detail, 12 sets of stellar evolution tracks and isochrones have been created at constant heavy element mass fraction Z that self-consistently account for varying heavy element mixtures. These sets include scaled-solar, α-enhanced, and individual cases where the elements C, N, O, Ne, Mg, Si, S, Ca, Ti, and Fe have been enhanced above their scaled-solar values. The variations that arise between scaled-solar and the other cases are examined with respect to the H-R diagram and main-sequence lifetimes

    Enhanced Tissue Integration During Cartilage RepairIn VitroCan Be Achieved by Inhibiting Chondrocyte Death at the Wound Edge

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    Objective: Experimental wounding of articular cartilage results in cell death at the lesion edge. The objective of this study was to investigate whether inhibition of this cell death results in enhanced integrative cartilage repair. Methods: Bovine articular cartilage discs (6mm) were incubated in media containing inhibitors of necrosis (Necrostatin-1, Nec-1) or apoptosis (Z-VAD-FMK, ZVF) before cutting a 3mm inner core. This core was left in situ to create disc/ring composites, cultured for up to 6 weeks with the inhibitors, and analyzed for cell death, sulfated glycosaminoglycan release, and tissue integration. Results: Creating the disc/ring composites resulted in a significant increase in necrosis. ZVF significantly reduced necrosis and apoptosis at the wound edge. Nec-1 reduced necrosis. Both inhibitors reduced the level of wound-induced sulfated glycosaminoglycan loss. Toluidine blue staining and electron microscopy of cartilage revealed significant integration of the wound edges in disc/ring composites treated with ZVF. Nec-1 improved integration, but to a lesser extent. Push-out testing revealed that ZVF increased adhesive strength compared to control composites. Conclusions: This study shows that treatment of articular cartilage with cell death inhibitors during wound repair increases the number of viable cells at the wound edge, prevents matrix loss, and results in a significant improvement in cartilage-cartilage integration

    Stellar Population Models and Individual Element Abundances I: Sensitivity of Stellar Evolution Models

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    Integrated light from distant galaxies is often compared to stellar population models via the equivalent widths of spectral features--spectral indices--whose strengths rely on the abundances of one or more elements. Such comparisons hinge not only on the overall metal abundance but also on relative abundances. Studies have examined the influence of individual elements on synthetic spectra but little has been done to address similar issues in the stellar evolution models that underlie most stellar population models. Stellar evolution models will primarily be influenced by changes in opacities. In order to explore this issue in detail, twelve sets of stellar evolution tracks and isochrones have been created at constant heavy element mass fraction Z that self-consistently account for varying heavy element mixtures. These sets include scaled-solar, alpha-enhanced, and individual cases where the elements C, N, O, Ne, Mg, Si, S, Ca, Ti, and Fe have been enhanced above their scaled-solar values. The variations that arise between scaled-solar and the other cases are examined with respect to the H-R diagram and main sequence lifetimes.Comment: 33 pages, 13 figures, accepted to Ap
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