Deformation of generic submanifolds in a complex manifold

This paper shows that an arbitrary generic submanifold in a complex manifold can be deformed into a 1-parameter family of generic submanifolds satisfying strong nondegeneracy conditions. The proofs use a careful analysis of the jet spaces of embeddings satisfying certain nondegeneracy properties, and also make use of the Thom transversality theorem, as well as the stratification of real-algebraic sets. Optimal results on the order of nondegeneracy are given.Comment: 24 page

Effects of divergent selection for leg weakness on muscle and bone characteristics in Duroc swine

The dimensions and weights of front leg muscles, tendons, and bones were determined in 44 gilts that were offspring of three Duroc lines from a five-generation divergent-selection experiment on leg weakness. Lines were low, control, and high, with the low line having the greatest leg weakness and the high-line having the least leg weakness. At a slaughter weight of approximately 118 kg, the right front leg was removed from the carcasses of 14 low-, 16 control-, and 14 high-line gilts. Each intrinsic muscle was dissected from origin to insertion, removed from the leg, and measured for total length and weight. The skeleton of the front leg was disarticulated so that each bone was freed and thoroughly cleaned of muscle remnants and connective tissue. The shoulder and elbow joints were scored for the presence of osteochondral lesions. Each bone was weighed, and various dimensional traits were measured. The model used to analyze the data included the effects of line, sire within line, and weight as a covariate. The biceps brachii muscle weight and length were significantly greater in low-line pigs than in control- or high-line pigs (P \u3c 0.05). Collectively, the forearm extensor weights were significantly greater in low-line pigs than in control- or high-line pigs (P \u3c 0.05). The humeral and metacarpal bones were shorter in high-line pigs than in control- or low-line pigs (P \u3c 0.05). The head of the humerus was wider and the angle of the head of the humerus was greater in high-line pigs than in control- or low-line pigs (P \u3c 0.05). Divergent selection for differing degrees of leg soundness in Duroc swine appears to be associated with major differences in front-leg bone and muscle lengths and weights

Thermonuclear burst physics with RXTE

Recently we have made measurements of thermonuclear burst energetics and recurrence times which are unprecedented in their precision, largely thanks to the sensitivity of the Rossi X-ray Timing Explorer. In the "Clocked Burster", GS 1826-24, hydrogen burns during the burst via the rapid-proton (rp) process, which has received particular attention in recent years through theoretical and modelling studies. The burst energies and the measured variation of alpha (the ratio of persistent to burst flux) with accretion rate strongly suggests solar metallicity in the neutron star atmosphere, although this is not consistent with the corresponding variation of the recurrence time. Possible explanations include extra heating between the bursts, or a change in the fraction of the neutron star over which accretion takes place. I also present results from 4U 1746-37, which exhibits regular burst trains which are interrupted by "out of phase" bursts.Comment: 4 pages, 2 figures, AIP conference proceedings format. To appear in the proceedings of the "X-ray Timing 2003: Rossi and Beyond" meeting held in Cambridge, MA, November, 200

Revised Approaches to Estimate Lean of Pork Carcasses of Known Age or Days on Test

Carcass measurements for 185 market hogs representing two sexes and four body types, slaughtered at 91 to 132 kg, were examined as predictors of carcass composition. Dependent variables included weight of fat-standardized lean (FSL), percentage FSL in the standardized side, weight of FSL gained/day on test, and weight of FSL produced/day of age. The greatest degree of predictive accuracy in each equation occurred when longissimus muscle area and fat depth at the three-fourths location at the 10th rib were included as independent variables. Other important variables were hot carcass weight in the three equations predicting weight for FSL, age in the equation for FSL produced/ day of age, and initial weight on test and days on test for the prediction of FSL gained/day on test. Less accuracy was found when other back-fat thickness measurements or subjective scores of muscling or fatness were used as independent variables

Palaeopathology in a Cretaceous terrestrial lizard from China

The lizard genus Yabeinosaurus is a common and relatively well-known member of Chinese Lower Cretaceous Jehol Biota, found in both the Yixian and Jiufotang formations of north-eastern China. Previous research on Yabeinosaurus has revealed information on its morphology, phylogenetic position, colouration, diet, and viviparous reproductive strategy. Herein we describe a new specimen preserving the skull and postcranial skeleton. The skull shows features characteristic of Yabeinosaurus robustus, but reveals the morphology of the vomer for the first time. In the postcranial skeleton, the most significant feature is a malformation of the fibula resulting from a fracture that occurred several months before the animal died, possibly as the result of intraspecies aggression or a predation attempt

Does Pulsar B1757--24 Have a Fallback Disk?

Radio pulsars are thought to spin-down primarily due to torque from magnetic dipole radiation (MDR) emitted by the time-varying stellar magnetic field as the star rotates. This assumption yields a `characteristic age' for a pulsar which has generally been assumed to be comparable to the actual age. Recent observational limits on the proper motion of pulsar B1757-24, however, revealed that the actual age (>39 kyr) of this pulsar is much greater than its MDR characteristic age (16 kyr) - calling into question the assumption of pure MDR spin-down for this and other pulsars. To explore the possible cause of this discrepancy, we consider a scenario in which the pulsar acquired an accretion disk from supernova ejecta, and the subsequent spin-down occurred under the combined action of MDR and accretion torques. A simplified model of the accretion torque involving a constant mass inflow rate at the pulsar magnetosphere can explain the age and period derivative of the pulsar for reasonable values of the pulsar magnetic field and inflow rate. We discuss testable predictions of this model.Comment: Accepted by ApJ Letters. 15 pages with 1 figur

HST Observations of SGR 0526-66: New Constraints on Accretion and Magnetar Models

Soft Gamma-ray Repeaters (SGRs) are among the most enigmatic sources known today. Exhibiting huge X- and Gamma-ray bursts and flares, as well as soft quiescent X-ray emission, their energy source remains a mystery. Just as mysterious are the Anomalous X-ray pulsars (AXPs), which share many of the same characteristics. Thanks to recent Chandra observations, SGR 0526-66, the first SGR, now appears to be a transition object bridging the two classes, and therefore observations of it have implications for both SGRs and AXPs. The two most popular current models for their persistent emission are accretion of a fossil disk or decay of an enormous (~10^15 G) magnetic field in a magnetar. We show how deep optical observations of SGR 0526-66, the only SGR with small enough optical extinction for meaningful observations, show no evidence of an optical counterpart. These observation place strong new constraints on both accretion disk and magnetar models, and suggest that the spectral energy distribution may peak in the hard-UV. Almost all accretion disks are excluded by the optical data, and a magnetar would require a ~10^15-10^16 G field.Comment: 23 pages, 5 figures. Accepted by Ap

Staphylococcus aureus nasal colonization in HIV-seropositive and HIV-seronegative drug users

Nasal colonization plays an important role in the pathogenesis of Staphylococcus aureus infections. To identify characteristics associated with colonization, we studied a cross-section of a well-described cohort of HIV-seropositive and -seronegative active and former drug users considered at risk for staphylococcal infections. Sixty percent of the 217 subjects were Hispanic, 36% were women, 25% actively used injection drugs, 23% actively used inhalational drugs, 23% received antibiotics, and 35% were HIV-seropositive. Forty-one percent of subjects had positive nasal cultures for S. aureus. The antibiotic susceptibility patterns were similar to the local hospital's outpatient isolates and no dominant strain was identified by arbitrarily primed polymerase chain reaction (AB-PCR). Variables significantly and independently associated with colonization included antibiotic use (odds ratio [OR] = 0.37; confidence interval [CI] = 0.18-0.77), active inhalational drug use within the HIV-seropositive population (OR = 2.36; CI = 1.10-5.10) and female gender (OR = 1.97; CI = 1.09-3.57). Characteristics not independently associated included injection drug use, HIV status, and CD4 count. The association with active inhalational drug use, a novel finding, may reflect alterations in the integrity of the nasal mucosa. The lack of association between HIV infection and S. aureus colonization, which is contrary to most previous studies, could be explained by our rigorous control for confounding variables or by a limited statistical power due to the sample sizes