Increasing the efficiency of pooled estimation with a block covariance structure

Econometrics ; Econometric models

U.S. banks, competition, and the Mexican banking system: how much will NAFTA matter?

Bank competition ; North American Free Trade Agreement ; Mexico

Individual Differences in Emotion Expression: Hierarchical Structure and Relations with Psychological Distress

Several constructs reflecting individual differences in emotion expression have been described in the literature, yet their structural organization is unknown. The present study provided a taxonomy of these individual differences and determined their relations to depression and anxiety symptoms. Exploratory factor analyses suggested seven emotion-expression factors-Affect Intensity, Ambivalence About Expression Disclosure of Negative Emotion, Disclosure of Emotion, Disclosure of Lack of Affect, Expression of Positive Emotion, and Secret Keeping-are explained by two second-order factors: Emotional Constraint and Emotional Expression. Multiple regression and canonical correlation analyses suggested that a reluctance to express emotions is related to heightened psychological symptoms. These findings bridge constructs from disparate literatures, and they provide support for emotion dysregulation models of affective disorders

An analysis of ultraviolet spectra of Extreme Helium Stars and new clues to their origins

Abundances of about 18 elements including the heavy elements Y and Zr are determined from Hubble Space Telescope Space Telescope Imaging Spectrograph ultraviolet spectra of seven extreme helium stars (EHes): LSE 78, BD+10 2179, V1920 Cyg, HD 124448, PV Tel, LS IV -1 2, and FQ Aqr. New optical spectra of the three stars -- BD+10 2179, V1920 Cyg, and HD 124448 were analysed. The abundance analyses is done using LTE line formation and LTE model atmospheres especially constructed for these EHe stars. The stellar parameters derived from an EHe's UV spectrum are in satisfactory agreement with those derived from its optical spectrum. Adopted abundances for the seven EHes are from a combination of the UV and optical analyses. Published results for an additional ten EHes provide abundances obtained in a nearly uniform manner for a total of 17 EHes, the largest sample on record. The initial metallicity of an EHe is indicated by the abundance of elements from Al to Ni; Fe is adopted to be the representative of initial metallicity. Iron abundances range from approximately solar to about one-hundredth of solar. Clues to EHe evolution are contained within the H, He, C, N, O, Y, and Zr abundances. Two novel results are (i) the O abundance for some stars is close to the predicted initial abundance yet the N abundance indicates almost complete conversion of initial C, N, and O to N by the CNO-cycles; (ii) three of the seven stars with UV spectra show a strong enhancement of Y and Zr attributable to an s-process. The observed compositions are discussed in light of expectations from accretion of a He white dwarf by a CO white dwarf.Comment: 126 pages, 15 figures, 20 Tables, accepted for publication in the Ap

Possible Stellar Metallicity Enhancements from the Accretion of Planets

A number of recently discovered extrasolar planet candidates have surprisingly small orbits, which may indicate that considerable orbital migration takes place in protoplanetary systems. A natural consequence of orbital migration is for a series of planets to be accreted, destroyed, and then thoroughly mixed into the convective envelope of the central star. We study the ramifications of planet accretion for the final main sequence metallicity of the star. If maximum disk lifetimes are on the order of 10 Myr, stars with masses near 1 solar mass are predicted to have virtually no metallicity enhancement. On the other hand, early F and late A type stars with masses of 1.5--2.0 solar masses can experience significant metallicity enhancements due to their considerably smaller convection zones during the first 10 Myr of pre-main-sequence evolution. We show that the metallicities of an aggregate of unevolved F stars are consistent with an average star accreting about 2 Jupiter-mass planets from a protoplanetary disk having a 10 Myr dispersal time.Comment: 14 pages, AAS LaTeX, 3 figures, accepted to ApJ Letter

Direct measurement of molecular stiffness and damping in confined water layers

We present {\em direct} and {\em linear} measurements of the normal stiffness and damping of a confined, few molecule thick water layer. The measurements were obtained by use of a small amplitude (0.36 $\textrm{\AA}$), off-resonance Atomic Force Microscopy (AFM) technique. We measured stiffness and damping oscillations revealing up to 7 layers separated by 2.56 $\pm$ 0.20 $\textrm{\AA}$. Relaxation times could also be calculated and were found to indicate a significant slow-down of the dynamics of the system as the confining separation was reduced. We found that the dynamics of the system is determined not only by the interfacial pressure, but more significantly by solvation effects which depend on the exact separation of tip and surface. Thus ` solidification\rq seems to not be merely a result of pressure and confinement, but depends strongly on how commensurate the confining cavity is with the molecule size. We were able to model the results by starting from the simple assumption that the relaxation time depends linearly on the film stiffness.Comment: 7 pages, 6 figures, will be submitted to PR

Effects of an Anabolic Implant and Transport on Metabolic Status and Muscle Traits of Feedlot Steers

A study was repeated over 2 years to determine the effect of feeding different levels of dry distillers grains with solubles (DDGS) and wet distillers grains with solubles (WDGS) on the performance of finishing cattle. In each year, 120 steers (756 ± 22 lb) were weighed, and randomly allocated to 15 pens. The pens were then assigned to one of five treatments: 1) corn-soybean meal (CON); 2) 20% DDGS; 3) 20% WDGS; 4) 40% DDGS; or 5) 40% WDGS. The basal diet consisted of 10% alfalfa hay, 4% molasses, 2% supplement, 10.5% SBM and 73.5% cracked corn. The WDGS and DDGS were added to replace all the SBM and part of the cracked corn. Steers were fed these diets for 138 and 129 days in years 1 and 2, respectively. Body weight was recorded prior to feeding at the start of the trial and every 28 days. Steers were harvested at a commercial facility and carcass data were collected. No treatment x year interactions occurred, thus data were pooled over the 2 years. There was an interaction between wet vs. dry and 20% vs. 40% distillers grains with solubles (DGS) for cumulative DMI. Steers fed 20% and 40% DDGS had the highest DMI, but feeding 40% WDGS significantly depressed (P \u3c 0.01) DMI. Cumulative ADG was similar across all treatments; however, steers fed 40% DGS had greater G:F (P \u3c 0.05) than those fed 20% DGS, and those fed WDGS were more efficient (P \u3c 0.01) than those fed DDGS. Pooled carcass data showed that steers fed DGS had greater (P \u3c 0.01) 12th rib fat compared to CON resulting in steers fed DGS having greater (P \u3c 0.05) Yield Grades compared to CON steers. Steers fed 20% DDGS and 20% WDGS had numerically higher (P \u3c 0.05) marbling scores compared to steers fed CON, 40% DDGS and 40% WDGS. Hot carcass weight, ribeye area, and percent kidney, pelvic, and heart fat were similar across all treatments. In conclusion, feeding DDGS and WDGS at 20 and 40% of the diet DM can be used to replace SBM in finishing diets to achieve similar gains and efficiencies. However, Yield Grades were greater for steers fed DGS compared to those fed the corn-soybean meal diet

Discovery of Five New R Coronae Borealis Stars in the MACHO Galactic Bulge Database

We have identified five new R Coronae Borealis (RCB) stars in the Galactic bulge using the MACHO Project photometry database, raising the total number of known Galactic RCB stars to about 40. We have obtained spectra to confirm the identifications. The fact that four out of the five newly identified RCB stars are ``cool'' (T(eff) 6000 K) suggests that the preponderance of warm RCB stars among the existing sample is a selection bias. These cool RCB stars are redder and fainter than their warm counterparts and may have been missed in surveys done with blue plates. Based on the number of new RCB stars discovered in the MACHO bulge fields, there may be ~250 RCB stars in the reddened "exclusion" zone toward the bulge.Comment: 16 pages, 5 figures, AJ in press High resolution versions of Figures 1 and 2 can be downloaded from http://morpheus.phys.lsu.edu/~gclayton/figs.pdf (more typos corrected

A new photon recoil experiment: towards a determination of the fine structure constant

We report on progress towards a measurement of the fine structure constant to an accuracy of $5\times 10^{-10}$ or better by measuring the ratio of the Planck constant to the mass of the cesium atom. Compared to similar experiments, ours is improved in three significant ways: (i) simultaneous conjugate interferometers, (ii) multi-photon Bragg diffraction between same internal states, and (iii) an about 1000 fold reduction of laser phase noise to -138 dBc/Hz. Combining that with a new method to simultaneously stabilize the phases of four frequencies, we achieve 0.2 mrad effective phase noise at the location of the atoms. In addition, we use active stabilization to suppress systematic effects due to beam misalignment.Comment: 12 pages, 9 figure