On calculating estimates of stratified error-components models

This note provides an AECM (alternating expectation conditional maximization) algorithm for calculating maximum-likelihood estimates of stratified error-components models. An advantage it has over other algorithms is that it can be easily modified to incorporate useful restrictions on the variance components. The new algorithm is applied in an example that illustrates the variance restrictions.

Some Monte Carlo results for a generalized error component model with heteroskedastic disturbances

This note provides Monte Carlo evidence illustrating that feasible and true GLS estimators of the Baltagi and Griffin (1988) generalized error component model do not have the same sampling behavior. Indeed, while the true GLS estimator is consistent, a feasible GLS estimator need not be, an observation corroborated by the Monte Carlo results.

Improving Supports for Youth of Color Traumatized by Violence

Many boys and young men of color live in communities where violence occurs too often and has a significant impact on their lives. This report examines the problem, offers strategies for various youth systems, and provides examples of approaches with strong outcomes for working with males of color who have witnessed or experienced violence

Targeting Intracellular Calcium Stores Alleviates Neurological Morbidities in a DFP-Based Rat Model of Gulf War Illness

Gulf War Illness (GWI) is a chronic multi-symptom disorder afflicting the veterans of the First Gulf War, and includes neurological symptoms characterized by depression and memory deficits. Chronic exposure to organophosphates (OP) is considered a leading cause for GWI, yet its pathobiology is not fully understood. We recently observed chronic elevations in neuronal Ca2+ levels ([Ca2+]i) in an OP- diisopropyl fluorophosphate (DFP) based rat model for GWI. This study was aimed at identifying mechanisms underlying elevated [Ca2+]i in this DFP model and investigating whether their therapeutic targeting could improve GWI-like neurological morbidities. Male Sprague-Dawley rats (9-wks) were exposed to DFP (0.5 mg/kg, s.c, 1x-daily for 5-d) and at 3-mos post DFP exposure, behavior was assessed and rats were euthanized for protein estimations and ratiometric Fura-2 [Ca2+]i estimations in acutely dissociated hippocampal neurons. In DFP rats, a sustained elevation in intracellular Ca2+ levels occurred, and pharmacological blockade of Ca2+-induced Ca2+-release mechanisms significantly lowered elevated [Ca2+]i in DFP neurons. Significant reductions in the protein levels of the ryanodine receptor (RyR) stabilizing protein Calstabin2 were also noted. Such a post-translational modification would render RyR leaky resulting in sustained DFP [Ca2+]i elevations. Antagonism of RyR with levetiracetam significantly lower elevated [Ca2+]i in DFP neurons and improved GWI-like behavioral symptoms. Since Ca2+ is a major second messenger molecule, such chronic increases in its levels could underlie pathological synaptic plasticity that expresses itself as GWI morbidities. Our studies show that treatment with drugs targeted at blocking intracellular Ca2+ release could be effective therapies for GWI neurological morbidities

Hidden Charge 2e Boson in Doped Mott Insulators: Field Theory of Mottness

We construct the low energy theory of a doped Mott insulator, such as the high-temperature superconductors, by explicitly integrating over the degrees of freedom far away from the chemical potential. For either hole or electron doping, a charge 2e bosonic field emerges at low energy. The charge 2e boson mediates dynamical spectral weight transfer across the Mott gap and creates a new charge e excitation by binding a hole. The result is a bifurcation of the electron dispersion below the chemical potential as observed recently in angle-resolved photoemission on Pb-doped Bi_2Sr_2CaCu_2O_{8+\delta} (Pb2212).Comment: 4 pages, 2 figures: Correct version to appear in PRL. Revisions include a derivation of the electron operator at low energies which reveals a branching structure seen recently in ARPES on Pb221

Self-Selection and Tests for Bias and Risk in Mortgage Lending: Can You Price the Mortgage If You Don't Know the Process?

There is increasing interest in understanding the determinants of mortgage rejection by lenders and default by borrowers. Although many researchers have proposed simple single-equation models of rejection and default, we argue that far more complex econometric specifications are needed. This paper focuses attention on problems of sample selection in the process creating a sample of applicants for conventional mortgages. We illustrate that corrections for sample selection bias may have a substantial effect on estimation results and hence should not be ignored in studies of mortgage rejection or default.

A new index of coincident economic activity for Houston

Economic indicators ; Economic conditions

Interpretation of the northern boundary of Ishtar Terra from Magellan images and altimetry

Part of the controversy on the origin of western Ishtar Terra (IT) concerns the nature of Uorsar Rupes (UR), the northern boundary of IT. In the hypothesis of lithospheric convergence and underthrusting, UR is held to be the main boundary thrust fault at the toe of an accretionary wedge. A topographic rise parallel to the scarp was interpreted as a flexural bulge similar to those of terrestrial subduction zones, and quantitative models of this feature seemed broadly consistent with the expected lithospheric structure of Venus. In the alternative mantle upwelling hypothesis for western IT, the outer margins of the highland are thought to be collapsing, and UR has been interpreted as a normal fault. Herein, Magellan images and altimetry are interpreted for this region and the hypothesis that a flexural signature can be distinguished is reassessed. The Magellan images of IT show evidence of crustal shortening adjacent to UR, but extension and burial dominate northwards. Altimetric profiles display the same long wavelength trends visible in Venera data, but no clear evidence of the lithospheric flexure. A model of regional extension and burial is herein favored, but regional compression cannot be ruled out