BOX-COX TRANSFORMATIONS AND ERROR TERM SPECIFICATION IN DEMAND MODELS

This paper analyzes the influence of error-term specification and functional form on a quarterly demand model for beef. The Box-Cox transformation is used to generalize the functional form while the equation error term is postulated to be both heteroskedastic and autoregressive. Results indicated that both functional form and error-term specification can play a major role in elasticity estimation, elasticity behavior, and hypothesis testing.Demand and Price Analysis,

ANALYSIS OF FOOD STAMP PROGRAM PARTICIPATION AND FOOD EXPENDITURES

A two equation model is developed to examine jointly the determinants of household food stamp program participation and program effects on food expenditures. The model is unique in that it postulates that the participation decision is based on a cost-benefit ratio, selected socioeconomic characteristics, and the potential for increasing both food and nonfood expenditures. Data from the 1977-78 USDA Nationwide Food Consumption Survey Supplemental Low Income Sample is used to estimate the model. Findings suggest that households, in making the participation decision place equal value on the potential for increasing their food and nonfood expenditures. However, at the margin, bonus stamp income is found to have more than twice the impact of money income on food expenditures. The model's potential for policy analysis is also examined.Food Consumption/Nutrition/Food Safety,

AN ALTERNATIVE APPROACH TO DEFINING AND ASSESSING POVERTY THRESHOLDS

This paper introduces a new method for defining poverty lines based on an individual' s self-evaluation of the household's present situation. The proposed method focuses on the minimum household income necessary to purchase food supplies evaluated by society to be barely adequate. The method is especially useful for evaluation and comparing poverty thresholds derived from different methods. It is also valuable for comparing the official U.S. poverty guidelines across households of different sizes. The approach can be extended to include estimation of thresholds differentiated by various household characteristics and comparison of thresholds across these characteristics.Food Security and Poverty,

Supernova Resonance-Scattering Profiles in the Presence of External Illumination

We discuss a simple model for the formation of a supernova spectral line by resonance scattering in the presence of external illumination of the line-forming region by light from circumstellar interaction (toplighting). The simple model provides a clear understanding of the most conspicuous toplighting effect: a rescaling or, as we prefer, a ``muting'' of the line profile relative to the continuum. This effect would be present in more realistic models, but would be harder to isolate. An analytic expression for a muting factor for a P-Cygni line is derived that depends on the ratio E of the toplighting specific intensity to the specific intensity from the supernova photosphere. If E<1, the line profile is reduced in scale or ``muted''. If E=1, the line profile vanishes altogether. If E>1, the line profile flips vertically: then having an absorption component near the observer-frame line center wavelength and a blueshifted emission component.Comment: accepted for publication in PAS

INFORMATIONAL EFFECTS OF NUTRIENT INTAKE DETERMINANTS ON CHOLESTEROL CONSUMPTION

Nutrient information and dietary data for a sample of U.S. household meal planners are used to estimate the direct and indirect effects of various dietary determinants on cholesterol intake. Holding sociodemographic and household characteristics constant, greater nutrition information translates to significantly lower intake of dietary cholesterol. Evidence supports the hypothesis that schooling promotes better health behavior through greater acquisition and use of health information. Blacks and Hispanics stand to benefit from nutrition education programs to increase their awareness of diet-health relationship. A low-calorie diet decreases the intake of cholesterol more than a low-fat diet.Food Consumption/Nutrition/Food Safety,

USDA's Healthy Eating Index and Nutrition Information

A comprehensive model is developed to measure the extent that nutrition knowledge and diet-health awareness, among other factors, influence an individual's Healthy Eating Index (HEI), USDA's measure of overall diet quality. This is the first study that rigorously attempts to examine variation in the index across population groups by controlling for personal and household characteristics and nutrition information levels, as well as test for the endogeneity of nutrition information. Results indicate that one's level of nutrition information has an important influence on one's HEI and that nutrition information and the HEI are simultaneously determined. Other factors explaining variations in HEI's across individuals are income and education levels, race, ethnicity, and age. Evidence supports the hypothesis that higher education promotes more healthful food choices through better acquisition and use of health information.diet quality, Healthy Eating Index, nutrient demand, nutrition knowledge, health inputs, health production, Food Consumption/Nutrition/Food Safety,

Spitzer Observations of Low Luminosity Isolated and Low Surface Brightness Galaxies

We examine the infrared properties of five low surface brightness galaxies (LSBGs) and compare them with related but higher surface brightness galaxies, using Spitzer Space Telescope images and spectra. All the LSBGs are detected in the 3.6 and 4.5um bands, representing the stellar population. All but one are detected at 5.8 and 8.0um, revealing emission from hot dust and aromatic molecules, though many are faint or point-like at these wavelengths. Detections of LSBGs at the far-infrared wavelengths, 24, 70, and 160um, are varied in morphology and brightness, with only two detections at 160um, resulting in highly varied spectral energy distributions. Consistent with previous expectations for these galaxies, we find that detectable dust components exist for only some LSBGs, with the strength of dust emission dependent on the existence of bright star forming regions. However, the far-infrared emission may be relatively weak compared with normal star-forming galaxies.Comment: 20 pages, 8 figures, accepted to Ap

Absolute physical calibration in the infrared

We determine an absolute calibration for the Multiband Imaging Photometer for Spitzer 24 μm band and recommend adjustments to the published calibrations for Two Micron All Sky Survey (2MASS), Infrared Array Camera (IRAC), and IRAS photometry to put them on the same scale. We show that consistent results are obtained by basing the calibration on either an average A0V star spectral energy distribution (SED), or by using the absolutely calibrated SED of the Sun in comparison with solar-type stellar photometry (the solar analog method). After the rejection of a small number of stars with anomalous SEDs (or bad measurements), upper limits of ~1.5% root mean square (rms) are placed on the intrinsic infrared (IR) SED variations in both A-dwarf and solar-type stars. These types of stars are therefore suitable as general-purpose standard stars in the IR. We provide absolutely calibrated SEDs for a standard zero magnitude A star and for the Sun to allow extending this work to any other IR photometric system. They allow the recommended calibration to be applied from 1 to 25 μm with an accuracy of ~2%, and with even higher accuracy at specific wavelengths such as 2.2, 10.6, and 24 μm, near which there are direct measurements. However, we confirm earlier indications that Vega does not behave as a typical A0V star between the visible and the IR, making it problematic as the defining star for photometric systems. The integration of measurements of the Sun with those of solar-type stars also provides an accurate estimate of the solar SED from 1 through 30 μm, which we show agrees with theoretical models

Interpreting experimental bounds on D^0 - \bar{D^0} mixing in the presence of CP violation

We analyse the most recent experimental data regarding D^0 - \bar{D^0} mixing, allowing for CP violation. We focus on the dispersive part of the mixing amplitude, M^D_{12}, which is sensitive to new physics contributions. We obtain a constraint on the mixing amplitude: |M^D_{12}| < 6.2\times 10^{-11} MeV at 95% C.L. . This constraint is weaker by a factor of about three than the one which is obtained when no CP violation is assumed.Comment: 9 pages, revtex4; One reference updated, one reference added, footnote 3 correcte