COMPARISONS OF HISPANIC HOUSEHOLDS' DEMAND FOR MEATS WITH OTHER ETHNIC GROUPS

The objective of this research was to analyze the demand patterns of Hispanic households for meats in comparison with other ethnic groups using data from the 1998 Consumer Expenditure Survey. A system of demand equations of the LinQuad form were estimated for ten meat products using an incomplete system of censored equations. Hispanic households showed a clear preference for beef. Price, income, and household-size elasticities were estimated for each meat product by ethnic group. The demand for ground beef was the most income-inelastic product regardless of ethnicity. Household size had a positive effect on the probability of consuming a particular meat product but a negative effect on actual item expenditures.Consumer/Household Economics, Demand and Price Analysis,

A CENSORED SYSTEM ESTIMATION OF HISPANIC HOUSEHOLD FOOD CONSUMPTION PATTERNS

A system of nine censored Engel curve equations was estimated for Hispanic households in the U.S.: grains, vegetables, fruits, milk, meat, legumes, fats, sugar, and beverages. Income and household size elasticities, with their respective confidence intervals, are reported and the results compared with other ethnic groups in the U.S.Food Consumption/Nutrition/Food Safety,

Variation in the sternal notches of suboscine passeriform birds

The present study was undertaken to record the variations of the posterior border of the sternum of the New World suboscines, in an attempt to determine the reliability of this area of the sternum as a taxonomic character. The conclusions drawn from this survey (of 993 specimens) are that, within a broad range of variants, two basic kinds of sternal configuration are found: two-notched (Types 2-3-4, as defined), and four-notched (Types 5-6). The four-notched sternum is not confined to genera in the Rhinocryptidae and Conopophaga, as previously believed. Variations within the twoand four-notched sterna may not be considered taxonomically significant unless they can be shown to be consistent in a large series of specimens. In no case should a single specimen of a species be assumed to show the only sternal configuration of the species. The possible adaptive significance of the observed range of variation is briefly discussed, but no conclusions may be drawn until a functional analysis of the passerine sternum can be made

The anatomy and systematic position of the antpipits Conopophaga and Corythopis

The anatomical characters of the passerine family Conopophagidae have been reexamined. The sternum, syrinx, tarsus, antorbital osteology and pterylosis of Conopophaga and Corythopis were compared with a broad sample of other suboscines, with particular attention to the Formicariidae and Rhinocryptidae. Conopophaga was found to lie well within the range of variation of the Formicariidae in the principal characters (sternum and syrinx) used by Forbes in describing the Conopophagidae. The key character was the apparent presence in Conopophaga of a four-notched sternum. In nearly all specimens of Conopophaga, however, we found the sternum to have two notches and two large medial fenestrae. The four-notched condition is found in some species of Grallaria and Pittasoma, both considered to be formicariid. In most of the other characters studied also, Conopophaga strongly resembles Grallaria. The genus Corythopis differs from Conopophaga and all other furnarioids in the major diagnostic characters examined. In several respects, particularly the pterylosis and syringeal structure, it shows strong affinities with the Tyrannidae. It is recommended that Conopophaga be returned to its former position, near Grallaria in the Formicariidae. Corythopis must be moved from the Furnarioidea to the Tyrannoidea; its proper position appears to be in the family Tyrannidae

The profile of an emission line from relativistic outflows around a black hole

Recent observations show strong evidence for the presence of Doppler-shifted emission lines in the spectrum of both black hole candidates and active galactic nuclei. These lines are likely to originate from relativistic outflows (or jets) in the vicinity of the central black hole. Consequently, the profile of such a line should be distorted by strong gravitational effects near the black hole, as well as special relativistic effects. In this paper, we present results from a detailed study on how each process affects the observed line profile. We found that the profile is sensitive to the intrinsic properties of the jets (Lorentz factor, velocity profile, and emissivity law), as well as to the spin of the black hole and the viewing angle (with respect to the axis of the jets). More specifically, in the case of approaching jets, an intrisically narrow line (blue-shifted) is seen as simply broadened at small viewing angles, but it shows a doubly peaked profile at large viewing angles for extreme Kerr black holes (due to the combination of gravitational focusing and Doppler effects); the profile is always singly peaked for Schwarzschild black holes. For receding jets, however, the line profile becomes quite complicated owing to complicated photon trajectories. To facilitate comparison with observations, we searched a large parameter space to derive representative line profiles. We show the results and discuss how to use emission lines as a potential tool for probing the inner region of a black hole jet system.Comment: 16 pages in emulateapj style, 11 figure

Symmetry-preserving discrete schemes for some heat transfer equations

Lie group analysis of differential equations is a generally recognized method, which provides invariant solutions, integrability, conservation laws etc. In this paper we present three characteristic examples of the construction of invariant difference equations and meshes, where the original continuous symmetries are preserved in discrete models. Conservation of symmetries in difference modeling helps to retain qualitative properties of the differential equations in their difference counterparts.Comment: 21 pages, 4 ps figure

A microscopic approach to critical phenomena at interfaces: an application to complete wetting in the Ising model

We study how the formalism of the Hierarchical Reference Theory (HRT) can be extended to inhomogeneous systems. HRT is a liquid state theory which implements the basic ideas of Wilson momentum shell renormalization group (RG) to microscopic Hamiltonians. In the case of homogeneous systems, HRT provides accurate results even in the critical region, where it reproduces scaling and non-classical critical exponents. We applied the HRT to study wetting critical phenomena in a planar geometry. Our formalism avoids the explicit definition of effective surface Hamiltonians but leads, close to the wetting transition, to the same renormalization group equation already studied by RG techiques. However, HRT also provides information on the non universal quantities because it does not require any preliminary coarse graining procedure. A simple approximation to the infinite HRT set of equations is discussed. The HRT evolution equation for the surface free energy is numerically integrated in a semi-infinite three-dimensional Ising model and the complete wetting phase transition is analyzed. A renormalization of the adsorption critical amplitude and of the wetting parameter is observed. Our results are compared to available Monte Carlo simulations.Comment: To be published in Phy. Rev.

Setting the stage: social-environmental and motivational predictors of optimal training engagement

In this paper, we will firstly explore the central tenets of SDT. Research that has examined the social-environmental and motivation-related correlates of optimal training, performance and health-related engagement through the theoretical lens of SDT will be reviewed. Drawing from SDT-driven work undertaken in educational, sport and dance settings, we will draw conclusions and suggest future directions from a research and applied perspective

Dynamic communicability predicts infectiousness

Using real, time-dependent social interaction data, we look at correlations between some recently proposed dynamic centrality measures and summaries from large-scale epidemic simulations. The evolving network arises from email exchanges. The centrality measures, which are relatively inexpensive to compute, assign rankings to individual nodes based on their ability to broadcast information over the dynamic topology. We compare these with node rankings based on infectiousness that arise when a full stochastic SI simulation is performed over the dynamic network. More precisely, we look at the proportion of the network that a node is able to infect over a fixed time period, and the length of time that it takes for a node to infect half the network.We find that the dynamic centrality measures are an excellent, and inexpensive, proxy for the full simulation-based measures

Solving the time-dependent Schr\"odinger equation with absorbing boundary conditions and source terms in Mathematica 6.0

In recent decades a lot of research has been done on the numerical solution of the time-dependent Schr\"odinger equation. On the one hand, some of the proposed numerical methods do not need any kind of matrix inversion, but source terms cannot be easily implemented into this schemes; on the other, some methods involving matrix inversion can implement source terms in a natural way, but are not easy to implement into some computational software programs widely used by non-experts in programming (e.g. Mathematica). We present a simple method to solve the time-dependent Schr\"odinger equation by using a standard Crank-Nicholson method together with a Cayley's form for the finite-difference representation of evolution operator. Here, such standard numerical scheme has been simplified by inverting analytically the matrix of the evolution operator in position representation. The analytical inversion of the N x N matrix let us easily and fully implement the numerical method, with or without source terms, into Mathematica or even into any numerical computing language or computational software used for scientific computing.Comment: 15 pages, 7 figure