A Massive Protostar Embedded in the Scuba Core JCMT 18354-0649S

We report the discovery of an extremely red object embedded in the massive SCUBA core JCMT 18354-0649S. This object is not associated with any known radio or far-IR source, though it appears in Spitzer IRAC data obtained as part of the GLIMPSE survey. At shorter wavelengths, this embedded source exhibits an extreme color, K – L' = 6.7. At an assumed distance of 5.7 kpc, this source has a near-IR luminosity of ~1000 L_☉. Its spectral energy distribution (SED) rises sharply from 2.1 μm to 8 μm, similar to that of a Class 0 young stellar object. Theoretical modeling of the SED indicates that the central star has a mass of 6-12 M_☉, with an optical extinction of more than 30. As both inflow and outflow motions are present in JCMT 18354-0649S, we suggest that this deeply embedded source is (1) a massive protostar in the early stages of accretion, and (2) the driving source of a massive molecular outflow evident in HCN J = 3-2 profiles observed toward this region

Recovery of fitness of a live attenuated simian immunodeficiency virus through compensation in both the coding and non-coding regions of the viral genome

We have analyzed a SIV deletion mutant that was compromised both in viral replication and RNA packaging. Serial passage of this variant in two different T-cell lines resulted in compensatory reversion and the generation of independent groups of point mutations within each cell line. Within each group, single point mutations were shown to contribute to increased viral infectivity and the rescue of wild-type replication kinetics. The complete recovery of viral fitness ultimately correlated with the restoration of viral RNA packaging. Consistent with the latter finding was the rescue of Pr55 Gag processing, also restoring proper virus core morphology in mature virions. These seemingly independently arising groups of compensatory mutations were functionally interchangeable in regard to the recovery of wild type replication in rhesus PBMCs. These findings indicate that viral reversion that overcomes a genetic bottleneck is not limited to a single pathway, and illustrates the remarkable adaptability of lentiviruses

Controlling the Sign of Magnetoconductance in Andreev Quantum Dots

We construct a theory of coherent transport through a ballistic quantum dot coupled to a superconductor. We show that the leading-order quantum correction to the two-terminal conductance of these Andreev quantum dots may change sign depending on (i) the number of channels carried by the normal leads or (ii) the magnetic flux threading the dot. In contrast, spin-orbit interaction may affect the magnitude of the correction, but not always its sign. Experimental signatures of the effect include a non-monotonic magnetoconductance curve and a transition from an insulator-like to a metal-like temperature dependence of the conductance. Our results are applicable to ballistic or disordered dots.Comment: Final version (4pages 3figs)- improved presentation and fig 3, and updated reference

Assessment of the effectiveness of head only and back-of-the-head electrical stunning of chickens

The study assesses the effectiveness of reversible head-only and back-of-the-head electrical stunning of chickens using 130–950 mA per bird at 50 Hz AC

Calf pre-weaning traits and immunoglobulin response to bovine viral diarrhea virus vaccination

Calfhood vaccination for bovine viral diarrhea virus (BVDV) is a relatively new concept, and protocols are evolving. Our objective was to determine effects of BVDV type I vaccination protocol, calf behavior (chute score, and chute exit velocity), and gender on calf gain and immunoglobulin (Ig) response. Crossbred calves (n = 64) were randomly allotted to one of two vaccination protocols. In protocol 1, calves were vaccinated at 60 d of age (d 0) and at weaning (d 147). Calves assigned to protocol 2 were vaccinated against BVDV type I at 21 d prior to (d 126) and at weaning (d 147). Blood samples were collected from half of the calves in each protocol group on d 0 (60 days of age), d 21, d 126 (21 days prior to weaning), and d 147 (at weaning); serum was harvested and Ig titers were determined. Titers for BVDV type I were transformed (log base 2) and analyzed using a mixed model procedure. Calves vaccinated at d 0 and weaning had larger (P \u3c 0.0001) titers than calves vaccinated at d 126 and weaning (7.5 ± 0.36 and 5.1 ± 0.36, respectively). Mean BVDV titers were larger (P \u3c 0.0001) on d 147 when compared with d 126, d 21, and d 0 (8.3 ± 0.39, 5.1 ± 0.40, 5.9 ± 0.39 and 5.7 ± 0.39, respectively). A treatment × day interaction (P \u3c 0.0001) also affected BVDV titers. However, BVDV titers were not affected (P \u3e 0.05) by calf gender, chute score, or chute exit velocity. Weaning weight and pre-weaning average daily gain (ADG) were not related to BVDV type I titers. This study indicated that vaccinating beef calves against BVDV was effective in triggering an Ig response. Furthermore, our results suggest that calves should be vaccinated against BVDV type I at 60 d of age for greater disease resistance

3-D Models of Embedded High-Mass Stars: Effects of a Clumpy Circumstellar Medium

We use 3-D radiative transfer models to show the effects of clumpy circumstellar material on the observed infrared colors of high mass stars embedded in molecular clouds. We highlight differences between 3-D clumpy and 1-D smooth models which can affect the interpretation of data. We discuss several important properties of the emergent spectral energy distribution (SED): More near-infrared light (scattered and direct from the central source) can escape than in smooth 1-D models. The near- and mid-infrared SED of the same object can vary significantly with viewing angle, depending on the clump geometry along the sightline. Even the wavelength-integrated flux can vary with angle by more than a factor of two. Objects with the same average circumstellar dust distribution can have very different near-and mid-IR SEDs depending on the clump geometry and the proximity of the most massive clump to the central source. Although clumpiness can cause similar objects to have very different SEDs, there are some observable trends. Near- and mid-infrared colors are sensitive to the weighted average distance of clumps from the central source and to the magnitude of clumpy density variations (smooth-to-clumpy ratio). Far-infrared emission remains a robust measure of the total dust mass. We present simulated SEDs, colors, and images for 2MASS and Spitzer filters. We compare to observations of some UCHII regions and find that 3-D clumpy models fit better than smooth models. In particular, clumpy models with fractal dimensions in the range 2.3-2.8, smooth to clumpy ratios of <50%, and density distributions with shallow average radial density profiles fit the SEDs best.Comment: accepted to ApJ; version with full-res figures: http://www.astro.virginia.edu/~ri3e/clumpy3d.pd

Herschel Observations of a Newly Discovered UX Ori Star in the Large Magellanic Cloud

The LMC star, SSTISAGE1C J050756.44-703453.9, was first noticed during a survey of EROS-2 lightcurves for stars with large irregular brightness variations typical of the R Coronae Borealis (RCB) class. However, the visible spectrum showing emission lines including the Balmer and Paschen series as well as many Fe II lines is emphatically not that of an RCB star. This star has all of the characteristics of a typical UX Ori star. It has a spectral type of approximately A2 and has excited an H II region in its vicinity. However, if it is an LMC member, then it is very luminous for a Herbig Ae/Be star. It shows irregular drops in brightness of up to 2 mag, and displays the reddening and "blueing" typical of this class of stars. Its spectrum, showing a combination of emission and absorption lines, is typical of a UX Ori star that is in a decline caused by obscuration from the circumstellar dust. SSTISAGE1C J050756.44-703453.9 has a strong IR excess and significant emission is present out to 500 micron. Monte Carlo radiative transfer modeling of the SED requires that SSTISAGE1C J050756.44-703453.9 has both a dusty disk as well as a large extended diffuse envelope to fit both the mid- and far-IR dust emission. This star is a new member of the UX Ori subclass of the Herbig Ae/Be stars and only the second such star to be discovered in the LMC.Comment: ApJ, in press. 9 pages, 5 figure