Spatial synchronization and extinction of species under external forcing

We study the interplay between synchronization and extinction of a species. Using a general model we show that under a common external forcing, the species with a quadratic saturation term in the population dynamics first undergoes spatial synchronization and then extinction, thereby avoiding the rescue effect. This is because the saturation term reduces the synchronization time scale but not the extinction time scale. The effect can be observed even when the external forcing acts only on some locations provided there is a synchronizing term in the dynamics. Absence of the quadratic saturation term can help the species to avoid extinction.Comment: 4 pages, 2 figure

Genetic analysis of foot-and-mouth disease virus serotype A of Indian origin and detection of positive selection and recombination in leader protease- and capsid-coding regions

The leader protease (Lpro) and capsid-coding sequences (P1) constitute approximately 3 kb of the foot-and-mouth disease virus (FMDV). We studied the phylogenetic relationship of 46 FMDV serotype A isolates of Indian origin collected during the period 1968-2005 and also eight vaccine strains using the neighbour-joining tree and Bayesian tree methods. The viruses were categorized under three major groups-Asian, Euro-South American and European. The Indian isolates formed a distinct genetic group among the Asian isolates. The Indian isolates were further classified into different genetic subgroups ( < 5% divergence). Post-1995 isolates were divided into two subgroups while a few isolates which originated in the year 2005 from Andhra Pradesh formed a separate group. These isolates were closely related to the isolates of the 1970s. The FMDV isolates seem to undergo reverse mutation or convergent evolution wherein sequences identical to the ancestors are present in the isolates in circulation. The eight vaccine strains included in the study were not related to each other and belonged to different genetic groups. Recombination was detected in the Lpro region in one isolate (A IND 20/82) and in the VP1 coding 1D region in another isolate (A RAJ 21/96). Positive selection was identified at aa positions 23 in the Lpro (P < 0.05; 0.046∗) and at aa 171 in the capsid protein VP1 (P < 0.01; 0.003∗∗)

Stripped Spiral Galaxies as Promising Targets for the Determination of the Cepheid distance to the Virgo Cluster

The measurement of precise galaxy distances by Cepheid observations out to the distance of the Virgo cluster is important for the determination of the Hubble constant ($H_0$). The Virgo cluster is thereby often used as an important stepping stone. The first HST measurement of the distance of a Virgo galaxy (M100) using Cepheid variables provided a value for $H_0=80(\pm 17)$ km/s/Mpc (Freedman et al. 1994). This measurement was preceeded by a ground based study of the Virgo spiral NGC4571 (Pierce et al. 1994) formally providing $H_0= 87\pm7$ km/s/Mpc. These determinations rely on the accuracy with which the position of this observed spiral galaxy can be located with respect to the Virgo cluster center. This uncertainty introduces a major error in the determination of $H_0$, together with the uncertainty in the adopted Virgo infall velocity of the Local Group. Here we propose the use of spiral galaxies which show clear signs of being stripped off their interstellar medium by the intracluster gas of the Virgo cluster as targets for the Cepheid distance measurements. We show that the stripping process and the knowledge of the intracluster gas distribution from ROSAT X-ray observations allow us to locate these galaxies with an at least three times higher precision with respect to M87 than in the case of other spirals like M100. The X-ray observations further imply that M87 is well centered within the intracluster gas halo of the Virgo cluster and that M86 is associated with a group of galaxies and a larger dark matter halo. The combination of these informations could enable us to locate the two stripped spiral galaxies quite precisely within the Virgo cluster and could greatly improve the determination of the Virgo cluster distance.Comment: 21 pages, Latex(aaspp.sty), including 6 figures, accepted for publication in ApJL (shortened abstract:

Platform-Based Internationalization of Smaller Firms: The Role of Government Policy

Governments are recognizing anticompetitive concerns and market distortions associated with the rise of e-commerce platforms. Thus, policies are being crafted to level the playing field between large platform operators and small platform sellers. In addition, policies mitigating barriers to internationalization associated with using e-commerce platforms are also being developed. This study aims to explore these policy actions impacting the platform-based internationalization of small and micro enterprises (SMEs). The case study method is adopted to provide rich insights into the Indian Government policy actions impacting the e-commerce platform-based internationalization of Indian SMEs. More specifically, this investigation analyzes the extent to which the Indian Government policy actions have mitigated the home market and industry-level barriers to export for SMEs leveraging e-commerce platforms for their internationalization efforts. Study findings provide rich policy implications and fodder for future empirical testing of key qualitative insights uncovered in this study

Chandra Observations of Gas Stripping in the Elliptical Galaxy NGC 4552 in the Virgo Cluster

We use a 54.4 ks Chandra observation to study ram-pressure stripping in NGC4552 (M89), an elliptical galaxy in the Virgo Cluster. Chandra images in the 0.5-2 keV band show a sharp leading edge in the surface brightness 3.1 kpc north of the galaxy center, a cool (kT =0.51^{+0.09}_{-0.06} keV) tail with mean density n_e ~5.4 +/- 1.7 x 10^{-3} cm^{-3} extending ~10 kpc to the south of the galaxy, and two 3-4 kpc horns of emission extending southward away from the leading edge. These are all features characteristic of supersonic ram-pressure stripping of galaxy gas, due to NGC4552's motion through the surrounding Virgo ICM. Fitting the surface brightness profile and spectra across the leading edge, we find the galaxy gas inside the edge is cooler (kT = 0.43^{+0.03}_{-0.02} keV) and denser (n_e ~ 0.010 cm^{-3}) than the surrounding Virgo ICM (kT = 2.2^{+0.7}_{-0.4} keV and n_e = 3.0 +/- 0.3 x 10^{-4} cm^{-3}). The resulting pressure ratio between the free-streaming ICM and cluster gas at the stagnation point is ~7.6^{+3.4}_{-2.0} for galaxy gas metallicities of 0.5^{+0.5}_{-0.3} Zsolar, which suggests that NGC4552 is moving supersonically through the cluster with a velocity v ~ 1680^{+390}_{-220} km/s (Mach 2.2^{+0.5}_{-0.3}) at an angle xi ~ 35 +/- 7 degrees towards us with respect to the plane of the sky.Comment: 31 pages, 12 figures, ApJ, in press; paper split into 2 parts, Paper I(sec 1-3) here, added figs and discussion to conform to published version; Paper II (sec. 4) in astro-ph/060440

Untangling the X-ray Emission From the Sa Galaxy NGC1291 With Chandra

We present a Chandra ACIS-S observation of the nearby bulge-dominated Sa galaxy NGC1291. The X-ray emission from the bulge resembles the X-ray emission from a sub-class of elliptical and S0 galaxies with low L_X/L_B luminosity ratios. The X-ray emission is composed of a central point-like nucleus, ~50 point sources that are most likely low mass X-ray binaries (LMXBs), and diffuse gas detectable out to a radius of 120" (5.2 kpc). The diffuse gas has a global temperature of 0.32^{+0.04}_{-0.03} keV and metallicity of 0.06 +/- 0.02 solar, and both quantities marginally decrease with increasing radius. The hot gas fills the hole in the HI distribution, and the softening of the spectrum of the X-ray gas with radius might indicate a thermal coupling of the hot and cold phases of the interstellar medium as previously suggested. The integrated X-ray luminosity of the LMXBs, once normalized by the optical luminosity, is a factor of 1.4 less than in the elliptical galaxy NGC4697 or S0 galaxy NGC1553. The difference in L_{X,stellar}/L_B between the galaxies appears to be because of a lack of very bright sources in NGC1291. No sources above 3 x 10^38 ergs/s were found in NGC1291 when ~7 were expected from scaling from NGC4697 and NGC1553. The cumulative L_{X,stellar}/L_B value including only sources below 1.0 x 10^38 ergs/s is remarkably similar between NGC1291 and NGC4697, if a recent surface brightness fluctuation-determined distance is assumed for NGC4697. If this is a common feature of the LMXB population in early-type systems, it might be used as a distance indicator. Finally, a bright, variable (1.6-3.1 x 10^39 ergs/s) source was detected at the optical center of the galaxy. Its spectrum shows excess soft emission superimposed on a highly absorbed power law component, similar to what has been found in several other low luminosity AGN (ABRIDGED).Comment: 13 pages in emulateapj5 style with 11 embedded Postscript figures; minor revisions since last version; accepted by Ap

Fused Deposition of Ceramics: Progress Towards a Robust and Controlled Process for Commercialization

The feasibility of using the Fused Deposition ofCeramics (FDC) process to rapidly fabricate functional quality advanced ceramic components has been demonstratedl - 5 . This direct manufacturing technique, by eliminating the need for costly tooling, dramatically reduces functional prototype development time. This makes it suitable for small quantity production runs and complex parts. The move from 'feasibility" to a robust, reliable commercial fabrication tool requires that every aspect ofthe manufacturing be understood and brought under control. An overview ofthe five basic process steps in FDC: batch compounding, filament fabrication, fused deposition, binder burnout and sintering will be presented in light ofthis drive toward a robust process. Tools such as Statistical Process Control and Experimental Design techniques are being used to monitor, improve, and stabilize each step and sub-process. Hardware and software modifications have been made to the FD machine to effect the required changes. This paper will identify the remaining technical barriers to commercialization and our progress in addressing these issues.Mechanical Engineerin

The Ionized Gas Kinematics of the LMC-Type Galaxy NGC 1427A in the Fornax Cluster

NGC 1427A is a LMC-like irregular galaxy in the Fornax cluster with an extended pattern of strong star formation around one of its edges, which is probably due to some kind of interaction with the cluster environment. We present H-alpha velocities within NGC 1427A, obtained through long-slit spectroscopy at seven different positions, chosen to fall on the brightest HII regions of the galaxy. Due to its location very near the center of the cluster this object is an excellent candidate to study the effects that the cluster environment has on gas-rich galaxies embedded in it. The rotation of NGC 1427A is modeled in two different ways. The global ionized gas kinematics is reasonably well described by solid-body rotation, although on small scales it shows a chaotic behaviour. In this simple model, the collision with a smaller member of the cluster as being responsible for the peculiar morphology of NGC 1427A is very unlikely, since the only candidate intruder falls smoothly into the general velocity pattern of the main galaxy. In a more elaborate model, for which we obtain a better solution, this object does not lie in the same plane of NGC 1427A, in which case we identify it as a satellite bound to the galaxy. These results are discussed in the context of a normal irregular versus one interacting with some external agent. Based on several arguments and quantitative estimates, we argue that the passage through the hot intracluster gas of the Fornax cluster is a very likely scenario to explain the morphological properties of NGC 1427A.Comment: 31 pages, LaTeX2e, uses aas2pp4.sty and psfig.sty, including 7 Postscript figures; accepted for publication in ApJ, Vol. 530, February 200

ROSAT Evidence for Intrinsic Oxygen Absorption in Cooling Flow Galaxies and Groups

Using spatially resolved, deprojected ROSAT PSPC spectra of 10 of the brightest cooling flow galaxies and groups with low Galactic column densities we have detected intrinsic absorption over energies ~0.4-0.8 keV in half of the sample. Since no intrinsic absorption is indicated for energies below ~0.4 keV, the most reasonable model for the absorber is collisionally ionized gas at temperatures T=10^{5-6} K with most of the absorption arising from ionized states of oxygen but with a significant contribution from carbon and nitrogen. The soft X-ray emission of this warm gas can explain the sub-Galactic column densities of cold gas inferred within the central regions of most of the systems. Attributing the absorption to ionized gas reconciles the large columns of cold H and He inferred from EINSTEIN and ASCA with the lack of such columns inferred from ROSAT. Within the central ~10-20 kpc, where the constraints are most secure, the estimated mass of the ionized absorber is consistent with most (perhaps all) of the matter deposited by a cooling flow over the lifetime of the flow. Since the warm absorber produces no significant H or He absorption the large absorber masses are consistent with the negligible atomic and molecular H inferred from HI and CO observations of cooling flows. It is also found that if T > ~2x10^5 K then the optical and UV emission implied by the warm gas does not violate published constraints. Finally, we discuss how the prediction of warm ionized gas as the product of mass drop-out in these and other cooling flows can be verified with new CHANDRA and XMM observations. (Abridged)Comment: 17 pages (5 figures), Accepted for publication in ApJ, expanded discussion of multiphase spectral models, theoretical implications of warm gas in cooling flows, and the statistical significance of the oxygen absorptio

Working Group Report: Neutrino and Astroparticle Physics

This is the report of neutrino and astroparticle physics working group at WHEPP-8. We present the discussions carried out during the workshop on selected topics in the above fields and also indicate progress made subsequently. The neutrino physics subgroup studied the possibilites of constraining neutrino masses, mixing and CPT violation in lepton sector from future experiments. Neutrino mass models in the context of abelian horizontal symmetries, warped extra dimensions and in presence of triplet Higgs were studied. Effect of threshold corrections on radiative magnification of mixing angles was investigated. The astroparticle physics subgroup focused on how various particle physics inputs affect the CMBR fluctuation spectrum, and on brane cosmology. This report also contains an introduction on how to use the publicly available code CMBFAST to calculate the CMBR fluctuations.Comment: Prepared for the 8th Workshop on High-Energy Physics Phenomenology (WHEPP-8), IIT Mumbai, India, 5-16 Jan 200