North Carolina State University

About: North Carolina State University is a education organization based out in Raleigh, North Carolina, United States. It is known for research contribution in the topics: Population & Thin film. The organization has 44161 authors who have published 101744 publications receiving 3456774 citations. The organization is also known as: NCSU & North Carolina State University at Raleigh.

Does Food Safety Information Impact U.S. Meat Demand

Abstract: A theoretical model of consumer response to publicized food safety information on meat demand is developed with an empirical application to U.S. meat consumption. Evidence is found for the existence of pre-committed levels of consumption, seasonal factors, time trends, and contemporaneous own- and cross-commodity food safety concerns. The average demand response to food safety concerns is small, especially in comparison to price effects, and to previous estimates of health related issues. This small average effect masks periods of significantly larger responses corresponding with prominent food safety events, but these larger impacts are short-lived with no apparent food safety lagged effects on Food safety concerns in the United States have dramatically increased in the past decade with regard to incidences of contaminated meat products. Concerns have arisen because contaminated meat products can result in serious risk to the well being and health of consumers. Contamination comes from a myriad of sources, including but not limited to, outbreaks of Listeria monocytogenes, Escherichia coli (E. coli), and Salmonella (Centers for Disease Control and Prevention). Food safety problems are not isolated to the United States as other unsafe contaminates in meats have emerged across the world, including highly publicized outbreaks of Bovine Spongiform Encephalopathy (BSE) in Europe. The potential impacts of publicized food safety events on consumer’s demand for meat products in the United States include own-effects on the demand for the contaminated meat involved as well as cross-effects impacting the demand for other meats. The objective of this article is to investigate whether publicized food safety concerns surrounding beef, pork, and poultry (chicken and turkey) have impacted meat consumption. Food safety indices are constructed separately for beef, pork, and poultry

Genome-wide patterns of nucleotide polymorphism in domesticated rice

Abstract: Domesticated Asian rice (Oryza sativa) is one of the oldest domesticated crop species in the world, having fed more people than any other plant in human history. We report the patterns of DNA sequence variation in rice and its wild ancestor, O. rufipogon, across 111 randomly chosen gene fragments, and use these to infer the evolutionary dynamics that led to the origins of rice. There is a genome-wide excess of high-frequency derived single nucleotide polymorphisms (SNPs) in O. sativa varieties, a pattern that has not been reported for other crop species. We developed several alternative models to explain contemporary patterns of polymorphisms in rice, including a (i) selectively neutral population bottleneck model, (ii) bottleneck plus migration model, (iii) multiple selective sweeps model, and (iv) bottleneck plus selective sweeps model. We find that a simple bottleneck model, which has been the dominant demographic model for domesticated species, cannot explain the derived nucleotide polymorphism site frequency spectrum in rice. Instead, a bottleneck model that incorporates selective sweeps, or a more complex demographic model that includes subdivision and gene flow, are more plausible explanations for patterns of variation in domesticated rice varieties. If selective sweeps are indeed the explanation for the observed nucleotide data of domesticated rice, it suggests that strong selection can leave its imprint on genome-wide polymorphism patterns, contrary to expectations that selection results only in a local signature of variation.

The sixth mass coextinction: are most endangered species parasites and mutualists?

Abstract: The effects of species declines and extinction on biotic interactions remain poorly understood. The loss of a species is expected to result in the loss of other species that depend on it (coextinction), leading to cascading effects across trophic levels. Such effects are likely to be most severe in mutualistic and parasitic interactions. Indeed, models suggest that coextinction may be the most common form of biodiversity loss. Paradoxically, few historical or contemporary coextinction events have actually been recorded. We review the current knowledge of coextinction by: (i) considering plausible explanations for the discrepancy between predicted and observed coextinction rates; (ii) exploring the potential consequences of coextinctions; (iii) discussing the interactions and synergies between coextinction and other drivers of species loss, particularly climate change; and (iv) suggesting the way forward for understanding the phenomenon of coextinction, which may well be the most insidious threat to global biodiversity.

Improving inferences in population studies of rare species that are detected imperfectly

Abstract: For the vast majority of cases, it is highly unlikely that all the individuals of a population will be encountered during a study. Furthermore, it is unlikely that a constant fraction of the population is encountered over times, locations, or species to be compared. Hence, simple counts usually will not be good indices of population size. We recommend that detection probabilities (the probability of including an individual in a count) be estimated and incorporated into inference procedures. However, most techniques for estimating detection probability require moderate sample sizes, which may not be achievable when studying rare species. In order to improve the reliability of inferences from studies of rare species, we suggest two general approaches that researchers may wish to consider that incorporate the concept of imperfect detectability: (1) borrowing information about detectability or the other quantities of interest from other times, places, or species; and (2) using state variables other than abundance (e.g., species richness and occupancy). We illustrate these suggestions with examples and discuss the relative benefits and drawbacks of each approach.

New Cartesian grid methods for interface problems using the finite element formulation

Abstract: New finite element methods based on Cartesian triangulations are presented for two dimensional elliptic interface problems involving discontinuities in the coefficients. The triangulations in these methods do not need to fit the interfaces. The basis functions in these methods are constructed to satisfy the interface jump conditions either exactly or approximately. Both non-conforming and conforming finite element spaces are considered. Corresponding interpolation functions are proved to be second order accurate in the maximum norm. The conforming finite element method has been shown to be convergent. With Cartesian triangulations, these new methods can be used as finite difference methods. Numerical examples are provided to support the methods and the theoretical analysis.