Endogeneity and Heterogeneity in LDV Panel Data Models

We extend three existing cross-sectional limited dependent variable (LDV) estimators, that allow for endogenous regressors, to a panel data model. We focus on estimation of effects of timeinvariant endogenous regressors, since to our knowledge, besides joint maximum likelihood, no other alternative consistent parametric estimators than the ones suggested here exist. We compare their small sample performance of estimates of marginal effects to i.i.d. LDV estimators as well as to linear estimators by means of Monte Carlo Studies. Some notable differences in the performance of the LDV estimators appear. One estimator, the 2SIV, performs reasonably well in terms of bias, even with weak instruments. Another type, the AGLS estimators, have a large small sample bias when no endogeneity is present. The 2SCML estimators seem to perform reasonable in most scenarios even under some types of misspecification. In addition, 2SLS performed relatively well, but had a substantial MSE with weak instruments and substantial bias in misspecified scenarios. Although potentially important because of heterogeneity bias, our extension of LDV models to the panel case did not give improvements in small sample performance over the cross-sectional estimators.Two-Step Estimation; Panel Data; Endogenous Regressor; Time-Invariant Regressor; Linear Approximation

Liver-based infant complementary food

Abstract- Weaning of infants involves the gradual introduction of solid foods and fluids along with the usual milk fed in their diet. After around six month of age, it becomes difficult to meet the nutritional requirements from the breast milk alone. This study developed beef liver based infant food as a complementary food for infants and determined its nutrient composition and sensory quality. Addition of liver to the vegetable base-formulation significantly improved the nutrient composition (P < 0.05) and consumer acceptance (P < 0.05) ofthe infant food compared to the treatments formulated with vegetables alone. The results of this study supports the importance of incorporating beef liver in to infant complementary food

Estimating and Modeling Red Oak Acorn Yield and Abundance in the Mississippi Alluvial Valley

Red oaks (Quercus spp.; Section Erythrobalanus) produce acorns which are valuable forage for wildlife especially mallards (Anas platyrhynchos) and wood ducks (Aix sponsa). Scientists have limited information on amount, timing, and persistence of these acorns in the Mississippi Alluvial Valley (MAV). Conservation planners rely on precise estimates of acorns and other forage to estimate habitat needed by waterfowl in the MAV and other regions. My study provided premiere landscape-scale, multi-year estimates of red oak acorn yield and on-ground abundance in the MAV. Mean yield of acorns was 534 kg(dry)/ha (42.3 acorns/ m2) across all sites, years (falls-winters 2009-2012), and oak species. Yield varied more within years (CV = 11 - 29%) than when data were combined across years (CV = 11%). Yield was not synchronized in any year among MAV sites. However, yield usually was synchronized among species within sites suggesting local factors influenced acorn yield more than landscape-scale factors. Among sites and years, acorn abundance generally was greatest in January (sample mean = 371 kg/ha) and least in November (198 kg/ha). Acorns persisted to February only in years of above-average yield. Except for Nuttall oak (Quercus texana), acorn persistence generally was stable regardless of yield from parent trees. Nuttall oak acorn persistence increased with yield perhaps revealing an evolutionary pressure that encourages masting. Red oak acorn abundance was linearly related to percentage of red oaks in the overstory, but this relationship differed in years of above- and below-average yield. Currently, conservation planners use 166 kg/ha as a forage estimate of red oak acorns, moist-soil seeds, and aquatic macro-invertebrates in bottomland hardwood forests with 100% red oak canopy. I sampled at 5 sites throughout the MAV over 3 years; therefore, I recommend conservation planners consider adopting my predicted estimate of 247 kg of acorns/ha of forest land with 100% red oak canopy. Because acorns persist through most winters and generally reach peak abundance in January, often concomitant with peak abundance of mallards and other ducks in the MAV, biologists and conservation planners may have undervalued the potential of bottomland hardwood forests to support ducks in mid-late winter

Does mass accretion lead to field decay in neutron stars

The recent discovery of cyclotron lines from gamma-ray bursts indicates that the strong magnetic fields of isolated neutron stars might not decay. The possible inverse correlation between the strength of the magnetic field and the mass accreted by the neutron star suggests that mass accretion itself may lead to the decay of the magnetic field. The spin and magnetic field evolution of the neutron star was calculated under the hypothesis of the accretion-induced field decay. It is shown that the calculated results are consistent with the observations of binary and millisecond radio pulsars