The Most Detailed Picture Yet of an Embedded High-mass YSO

High-mass star formation is not well understood chiefly because examples are deeply embedded, relatively distant, and crowded with sources of emission. Using VLA and VLBA observations of water and SiO maser emission, we have mapped in detail the structure and proper motion of material 20-500 AU from the closest high-mass YSO, radio source-I in the Orion KL region. We observe streams of material driven in a rotating, wide angle, bipolar wind from the surface of an edge-on accretion disk. The example of source-I provides strong evidence that high-mass star formation proceeds via accretionComment: typo corrected and word added to abstract 6 pages including 4 B&W figures. To appear in the Proceeding of IAU Symposium 221, Star Formation at High Angular Resolution, Editors M. Burton, R. Jayawardhana & T. Bourke, Astronomical Society of the Pacifi

The interferon-stimulated gene IFITM3 restricts infection and pathogenesis of arthritogenic and encephalitic alphaviruses

Host cells respond to viral infections by producing type I interferon (IFN), which induces the expression of hundreds of interferon-stimulated genes (ISGs). Although ISGs mediate a protective state against many pathogens, the antiviral functions of the majority of these genes have not been identified. IFITM3 is a small transmembrane ISG that restricts a broad range of viruses, including orthomyxoviruses, flaviviruses, filoviruses, and coronaviruses. Here, we show that alphavirus infection is increased in Ifitm3(−/−) and Ifitm locus deletion (Ifitm-del) fibroblasts and, reciprocally, reduced in fibroblasts transcomplemented with Ifitm3. Mechanistic studies showed that Ifitm3 did not affect viral binding or entry but inhibited pH-dependent fusion. In a murine model of chikungunya virus arthritis, Ifitm3(−/−) mice sustained greater joint swelling in the ipsilateral ankle at days 3 and 7 postinfection, and this correlated with higher levels of proinflammatory cytokines and viral burden. Flow cytometric analysis suggested that Ifitm3(−/−) macrophages from the spleen were infected at greater levels than observed in wild-type (WT) mice, results that were supported by experiments with Ifitm3(−/−) bone marrow-derived macrophages. Ifitm3(−/−) mice also were more susceptible than WT mice to lethal alphavirus infection with Venezuelan equine encephalitis virus, and this was associated with greater viral burden in multiple organs. Collectively, our data define an antiviral role for Ifitm3 in restricting infection of multiple alphaviruses. IMPORTANCE The interferon-induced transmembrane protein 3 (IFITM3) inhibits infection of multiple families of viruses in cell culture. Compared to other viruses, much less is known about the antiviral effect of IFITM3 on alphaviruses. In this study, we characterized the antiviral activity of mouse Ifitm3 against arthritogenic and encephalitic alphaviruses using cells and animals with a targeted gene deletion of Ifitm3 as well as deficient cells transcomplemented with Ifitm3. Based on extensive virological analysis, we demonstrate greater levels of alphavirus infection and disease pathogenesis when Ifitm3 expression is absent. Our data establish an inhibitory role for Ifitm3 in controlling infection of alphaviruses

Analysis of biopharma raw materials by electrophoresis microchips with contactless conductivity detection

Detailed information concerning the composition of the raw materials employed in the production of biologics is important for the efficient control and optimization of bioprocesses. We demonstrate the application of electrophoresis microchips with capacitively-coupled contactless conductivity detection (C4D) to the analysis of wa-ter-soluble vitamins and metal cations in raw material solutions that are subse-quently fed into bioreactors for the production of biologics

Dynamics of Polymerization of Macromolecules with Multiple Binding Sites

In Nature, there are many examples of biological polymerizations in which the monomers possess multiple binding sites. Under certain circumstances, such branched polymerizations may produce a large macroparticle that constitutes a significant fraction of the monomers. In this paper, we show that the polymerizations of antibodies with antigens and the polymerization of fibrin are of this type. We then present the results of stochastic simulations for the time-evolutions of these processes, and characterize their gel transitions. Finally, we relate the innate fluctuations of these processes to the gel transition, and demonstrate the necessity of using a stochastic approach to quantify polymerization kinetics

New Analysis Indicates No Thermal Inversion in the Atmosphere of HD 209458b

An important focus of exoplanet research is the determination of the atmospheric temperature structure of strongly irradiated gas giant planets, or hot Jupiters. HD 209458b is the prototypical exoplanet for atmospheric thermal inversions, but this assertion does not take into account recently obtained data or newer data reduction techniques. We re-examine this claim by investigating all publicly available Spitzer Space Telescope secondary-eclipse photometric data of HD 209458b and performing a self-consistent analysis. We employ data reduction techniques that minimize stellar centroid variations, apply sophisticated models to known Spitzer systematics, and account for time-correlated noise in the data. We derive new secondary-eclipse depths of 0.119 +/- 0.007%, 0.123 +/- 0.006%, 0.134 +/- 0.035%, and 0.215 +/- 0.008% in the 3.6, 4.5, 5.8, and 8.0 micron bandpasses, respectively. We feed these results into a Bayesian atmospheric retrieval analysis and determine that it is unnecessary to invoke a thermal inversion to explain our secondary-eclipse depths. The data are well-fitted by a temperature model that decreases monotonically between pressure levels of 1 and 0.01 bars. We conclude that there is no evidence for a thermal inversion in the atmosphere of HD 209458b.Comment: 8 pages, 5 figures; accepted for publication in Ap

Kinetics of random aggregation-fragmentation processes with multiple components

A computationally efficient algorithm is presented for exact simulation of the stochastic time evolution of spatially homogeneous aggregation-fragmentation processes featuring multiple components or conservation laws. The algorithm can predict the average size and composition distributions of aggregating particles as well as their fluctuations, regardless of the functional form (e.g., composition dependence) of the aggregation or fragmentation kernels. Furthermore, it accurately predicts the complete time evolutions of all moments of the size and composition distributions, even for systems that exhibit gel transitions. We demonstrate the robustness and utility of the algorithm in case studies of linear and branched polymerization processes, the last of which is a two-component process. These simulation results provide the stochastic description of these processes and give new insights into their gel transitions, fluctuations, and long-time behavior when deterministic approaches to aggregation kinetics may not be reliable

Intrinsic properties of the magnetically collimated water maser jet of W43A

Water maser polarization observations in the precessing jet of W43A have revealed that it is magnetically collimated. Here we present a detailed description of the physical properties of the water maser environment in the jet. We discuss the maser saturation level and beaming angle as well as the intrinsic temperatures and densities. Additionally, we show that the polarization angle of the strongest red-shifted maser feature undergoes a fast rotation of 90 degrees across the maser. Along with the variation of linear polarization fraction, this strongly supports the current theoretical description of maser linear polarization.Comment: 4 pages, 4 figures, accepted for publication in ApJ Letter