Precision Ephemerides For Gravitational Wave Searches: II. Cyg X-2

Accreting neutron stars in low-mass X-ray binaries (LMXBs) are candidate high-frequency persistent gravitational wave sources. These may be detectable with next generation interferometers such as Advanced LIGO/VIRGO within this decade. However, the search sensitivity is expected to be limited principally by the uncertainty in the binary system parameters. We combine new optical spectroscopy of Cyg X-2 obtained with the Liverpool Telescope (LT) with available historical radial velocity data, which gives us improved orbital parameter uncertainties based on a 44-year baseline. We obtained an improvement of a factor of 2.6 in the orbital period precision and a factor of 2 in the epoch of inferior conjunction T_0. The updated orbital parameters imply a mass function of 0.65 +/- 0.01 M_sun, leading to a primary mass (M_1) of 1.67 +/- 0.22 M_sun (for i=62.5 +/- 4 deg). In addition, we estimate the likely orbital parameter precision through to the expected Advanced LIGO and VIRGO detector observing period and quantify the corresponding improvement in sensitivity via the required number of templates.Comment: 7 pages, 3 figures, accepted for publication by Ap

Show Quality Quarter Horse Auctions: Price Determinants and Buy-Back Practices

This study estimates the price determinants of show quality quarter horses sold at auction. Several characteristics including genetic and physical traits, quality of pedigree, and performance record of the horse, as well as the horse's offspring, were found to significantly impact selling price. Sale order positively affected price and appears to be driven by buyers rather than intentional ordering of the horses. A common practice at horse auctions is for the seller to reject the final bid offered and buy back the horse. Model-predicted prices for these buy-back horses indicate they are not undervalued by the final bids, based on their characteristics.auction, equine, hedonic pricing, quarter horses, Demand and Price Analysis,

On the dynamic tensile strength of Zirconium

Despite its fundamental nature, the process of dynamic tensile failure (spall) is poorly understood. Spall initiation via cracks, voids, etc, before subsequent coalesce, is known to be highly microstructure-dependant. In particular, the availability of slip planes and other methods of plastic deformation controls the onset (or lack thereof) of spall. While studies have been undertaken into the spall response of BCC and FCC materials, less attention has paid to the spall response of highly anisotropic HCP materials. Here the dynamic behaviour of zirconium is investigated via plate-impact experiments, with the aim of building on an ongoing in-house body of work investigating these highly complex materials. In particular, in this paper the effect of impact stress on spall in a commercially sourced Zr rod is considered, with apparent strain-rate softening highlighted

EFFECTS OF JOINT PRODUCT MANAGEMENT STRATEGIES ON E.COLI 0157:H7 AND FEEDLOT PROFITS

The objective of this study was to determine the effect of Escherichia coli 0157:H7 on feedlot profits. Fecal samples from 711 feedlot pens in 73 feedlots in Nebraska, Kansas, Oklahoma, and Texas were tested for E. coli 0157:H7. Average daily gain and feed-to-gain ratios were computed for each feedlot pen, and managers from each feedlot provided information on various feedlot management practices. Cattle performance and E. coli 0157:H7 prevalence are both affected by feedlot management practices. The indirect effect of E. coli 0157:H7 on potential feedlot profits was determined by measuring the effects of management practices on E. coli 0157:H7 levels and cattle performance. Management practices that affect cattle performance were identified using ordinary least squares regressions. A negative binomial regression was used to identify management practices that affect E. coli 0157:H7 prevalence. Certain feedlot management practices were identified that have a joint impact on cattle performance and E. coli 0157:H7 prevalence. Using predatory insects to control flies, controlling for stray dogs, foxes, and coyotes in feed areas, removing manure from pens during finishing, and including tallow in the ration were management strategies associated with higher feedlot profits and lower E. coli 0157:H7 prevalence. Using mobile sprinklers for dust control and including alfalfa or sorghum hay or silage in the ration were associated with lower E. coli 0157:H7 prevalence and lower feedlot profits. Increasing days between cleaning water tanks and restricting movement of horses were associated with higher feedlot profits and higher E. coli 0157:H7 levels. Controlling for stray cats in feed areas and including liquid protein in the ration were associated with lower feedlot profits and higher E. coli 0157:H7 levels. These specific management strategies, which were not robust through a sensitivity analysis, should be interpreted with caution. The general categories of management strategies, however, were robust and consistent with past researchLivestock Production/Industries,

The Nature of the Secondary Star in the Black Hole X-Ray Transient V616 Mon (=A0620-00)

We have used NIRSPEC on Keck II to obtain $K$-band spectroscopy of the low mass X-ray binary V616 Mon (= A0620$-$00). V616 Mon is the proto-typical soft x-ray transient containing a black hole primary. As such it is important to constrain the masses of the binary components. The modeling of the infrared observations of ellipsoidal variations in this system lead to a derived mass of 11.0 M_{\sun} for the black hole. The validity of this derivation has been called into question due to the possiblity that the secondary star's spectral energy distribution is contaminated by accretion disk emission (acting to dilute the variations). Our new $K$-band spectrum of V616 Mon reveals a late-type K dwarf secondary star, but one that has very weak $^{\rm 12}$CO absorption features. Comparison of V616 Mon with SS Cyg leads us to estimate that the accretion disk supplies only a small amount of $K$-band flux, and the ellipsoidal variations are not seriously contaminated. If true, the derived orbital inclination of V616 Mon is not greatly altered, and the mass of the black hole remains large. A preliminary stellar atmosphere model for the $K$-band spectrum of V616 Mon reveals that the carbon abundance is approximately 50% of the solar value. We conclude that the secondary star in V616 Mon has either suffered serious contamination from the accretion of supernova ejecta that created the black hole primary, or it is the stripped remains of a formerly more massive secondary star, one in which the CNO cycle had been active.Comment: 20 pages, 5 figure

Defining childhood severe falciparum malaria for intervention studies.

Background Clinical trials of interventions designed to prevent severe falciparum malaria in children require a clear endpoint. The internationally accepted definition of severe malaria is sensitive, and appropriate for clinical purposes. However, this definition includes individuals with severe nonmalarial disease and coincident parasitaemia, so may lack specificity in vaccine trials. Although there is no “gold standard” individual test for severe malaria, malaria-attributable fractions (MAFs) can be estimated among groups of children using a logistic model, which we use to test the suitability of various case definitions as trial endpoints. Methods and Findings A total of 4,583 blood samples were taken from well children in cross-sectional surveys and from 1,361 children admitted to a Kenyan District hospital with severe disease. Among children under 2 y old with severe disease and over 2,500 parasites per microliter of blood, the MAFs were above 85% in moderate- and low-transmission areas, but only 61% in a high-transmission area. HIV and malnutrition were not associated with reduced MAFs, but gastroenteritis with severe dehydration (defined by reduced skin turgor), lower respiratory tract infection (clinician's final diagnosis), meningitis (on cerebrospinal fluid [CSF] examination), and bacteraemia were associated with reduced MAFs. The overall MAF was 85% (95% confidence interval [CI] 83.8%–86.1%) without excluding these conditions, 89% (95% CI 88.4%–90.2%) after exclusions, and 95% (95% CI 94.0%–95.5%) when a threshold of 2,500 parasites/μl was also applied. Applying a threshold and exclusion criteria reduced sensitivity to 80% (95% CI 77%–83%). Conclusions The specificity of a case definition for severe malaria is improved by applying a parasite density threshold and by excluding children with meningitis, lower respiratory tract infection (clinician's diagnosis), bacteraemia, and gastroenteritis with severe dehydration, but not by excluding children with HIV or malnutrition

A Black Hole in the X-Ray Nova Velorum 1993

We have obtained 17 moderate-resolution (~2.5 A) optical spectra of the Galactic X-ray Nova Velorum 1993 in quiescence with the Keck-II telescope. The orbital period (P) is 0.285206 +/- 0.0000014 d, and the semiamplitude (K_2) is 475.4 +/- 5.9 km/s. Our derived mass function, f(M_1) = PK_2^3 /2 pi G = 3.17 +/- 0.12 M_sun, is close to the conventional absolute limiting mass for a neutron star (~ 3.0-3.2 M_sun) -- but if the orbital inclination i is less than 80 degrees (given the absences of eclipses), then M_1 is greater than 4.2-4.4 M_sun for nominal secondary-star masses of 0.5 M_sun (M0) to 0.65 M_sun (K6). The primary star is therefore almost certainly a black hole rather than a neutron star. The velocity curve of the primary from H-alpha emission has a semiamplitude (K_1) of 65.3 +/- 7.0 km/s, but with a phase offset by 237 degrees (rather than 180 degrees) from that of the secondary star. The nominal mass ratio q = M_2/M_1 = K_1/K_2 = 0.137 +/- 0.015, and hence for M_2 = 0.5-0.65 M_sun we derive M_1 = 3.64-4.74 M_sun. An adopted mass M_1 ~ 4.4 M_sun is significantly below the typical value of ~ 7 M_sun found for black holes in other low-mass X-ray binaries. Keck observations of MXB 1659-29 (V2134 Oph) in quiescence reveal a probable optical counterpart at R = 23.6 +/- 0.4 mag.Comment: 16 pages, 9 figures, added references, revised per. referee's comments Accepted for publication in August 1999 issue of PAS

An Enantioselective Artificial Suzukiase Based on the Biotin–Streptavidin Technology

Introduction of a biotinylated monophosphine palladium complex within streptavidin affords an enantioselective artificial Suzukiase. Site-directed mutagenesis allowed the optimization of the activity and the enantioselectivity of this artificial metalloenzyme. A variety of atropisomeric biaryls were produced in good yields and up to 90% ee. The hybrid catalyst described herein shows comparable TOF to the previous aqueous-asymmetric Suzuki catalysts, and excellent stability under the reaction conditions to realize higher TON through longer reaction time