Tidal Destruction of The First Dark Microhalos

We point out that the usual self-similarity in cold dark matter models is broken by encounters with individual normal galactic stars on sub-pc scale. Tidal heating and stripping must have redefined the density and velocity structures of the population of the Earth-mass dark matter halos, which are likely to have been the first bound structures to form in the Universe. The disruption rate depends strongly on {\it galaxy types} and the orbital distribution of the microhalos; in the Milky Way, stochastic radial orbits are destroyed first by stars in the triaxial bulge, microhalos on non-planar retrograde orbits with large pericenters and/or apocenters survive the longest. The final microhalo distribution in the {\it solar neighborhood} is better described as a superposition of filamentry microstreams rather than as a set of discrete spherical clumps in an otherwise homogeneous medium. We discuss its important consequences to our detections of microhalos by direct recoil signal and indirect annihilation signal.Comment: 13 pages, 3 figures, Astrophysical Journal, accepte

Clean energy futures and place-based responses: a comparison of letters-to-the-editor in two Australian regions

A region’s cultural environment—how people communicate and how local media represent the immediate social and natural environment—is indicative of local dominant normative values that underpin potential capacities for climate change mitigation and adaptation. This article explores this premise with a comparison of two regions in Australia: Northern Rivers (New South Wales) and Ipswich-Lockyer (Queensland), and draws attention to readers’ letters published in two daily newspapers, The Queensland Times (Ipswich) and The Northern Star (Lismore), with a specific focus on the Clean Energy Legislative Package. Leximancer software is used to analyse the content of readers’ letters published over a nine-month period coinciding with the passage of the legislation through the Australian parliament. The results indicate important differences in local discourses and suggest a focus on local socio-cultural landscapes and their capacities for community dialogue are potentially useful for understanding how communities talk about, and the extent to which they will accept climate change policies

Low risk of hepatitis B virus recurrence after withdrawal of long-term hepatitis B immunoglobulin in patients receiving maintenance nucleos(t)ide analogue therapy

Hepatitis B virus (HBV) recurrence rates of 0-16% had been reported in patients maintained on nucleoside analogues (NA) after hepatitis B immunoglobulin (HBIG) discontinuation after orthotopic liver transplantation (OLT). However, follow-up in most studies was short. We aimed to determine the long-term risk of HBV recurrence using this strategy. All HBV patients who received ≥7 doses of intravenous HBIG after OLT, with no HBV recurrence while receiving HBIG, and who eventually discontinued HBIG and were maintained on NA, were included. HBV recurrence was defined as HBsAg-positive or HBV DNA ≥5 log copies/mL on 2 consecutive occasions. Twenty-one patients met the inclusion criteria. Immediate post-OLT prophylaxis was combination HBIG and NA in 15 patients, whereas 6 patients received HBIG monotherapy for 62-109 months before NA was added. HBIG was discontinued a median of 26 (range, 0.2-121) months after OLT. Median follow-up post-HBIG discontinuation was 40 (range, 5-51) months. Only 1 patient, who had 12 months of HBIG and was noncompliant to NA therapy, had HBV recurrence, 34 months after HBIG discontinuation. One patient had HBV DNA of 3.3 log copies/mL 47 and 48 months after HBIG discontinuation but remained HBsAg-negative. Lamivudine-resistant mutations were detected in both patients. Probability of HBV recurrence was 0% and 9% at 2 and 4 years after HBIG discontinuation. Three patients had 1-2 episodes of transiently detectable HBV DNA. All were HBV DNA and HBsAg negative on repeated tests over a period of 2-36 months. Maintenance therapy with NA after discontinuation of long-term HBIG therapy is associated with a low risk of HBV recurrence after OLT in compliant HBV patients. Liver Transpl 13:374–381, 2007. © 2007 AASLD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55976/1/21041_ftp.pd

The new galaxy evolution paradigm revealed by the Herschel surveys

The Herschel Space Observatory has revealed a very different galaxyscape from that shown by optical surveys, which presents a challenge for galaxy-evolution models. The Herschel surveys reveal (1) that there was rapid galaxy evolution in the very recent past and (2) that galaxies lie on a a single Galaxy Sequence (GS) rather than a star-forming ‘main sequence’ and a separate region of ‘passive’ or ‘red-and-dead’ galaxies. The form of the GS is now clearer because far-infrared surveys such as the Herschel ATLAS pick up a population of optically-red star-forming galaxies that would have been classified as passive using most optical criteria. The space-density of this population is at least as high as the traditional star-forming population. By stacking spectra of H-ATLAS galaxies over the redshift range 0.001 < z < 0.4, we show that the galaxies responsible for the rapid low-redshift evolution have high stellar masses, high star-formation rates but, even several billion years in the past, old stellar populations— they are thus likely to be relatively recent ancestors of early-type galaxies in the Universe today. The form of the GS is inconsistent with rapid quenching models and neither the analytic bathtub model nor the hydrodynamical EAGLE simulation can reproduce the rapid cosmic evolution. We propose a new gentler model of galaxy evolution that can explain the new Herschel results and other key properties of the galaxy population

The causes of the red sequence, the blue cloud, the green valley, and the green mountain

The galaxies found in optical surveys fall in two distinct regions of a diagram of optical colour versus absolute magnitude: the red sequence and the blue cloud with the green valley in between. We show that the galaxies found in a submillimetre survey have almost the opposite distribution in this diagram, forming a `green mountain'. We show that these distinctive distributions follow naturally from a single, continuous, curved Galaxy Sequence in a diagram of specific star-formation rate versus stellar mass without there being the need for a separate star-forming galaxy Main Sequence and region of passive galaxies. The cause of the red sequence and the blue cloud is the geometric mapping between stellar mass/specific star-formation rate and absolute magnitude/colour, which distorts a continuous Galaxy Sequence in the diagram of intrinsic properties into a bimodal distribution in the diagram of observed properties. The cause of the green mountain is Malmquist bias in the submillimetre waveband, with submillimetre surveys tending to select galaxies on the curve of the Galaxy Sequence, which have the highest ratios of submillimetre-to-optical luminosity. This effect, working in reverse, causes galaxies on the curve of the Galaxy Sequence to be underrepresented in optical samples, deepening the green valley. The green valley is therefore not evidence (1) for there being two distinct populations of galaxies, (2) for galaxies in this region evolving more quickly than galaxies in the blue cloud and the red sequence, (c) for rapid quenching processes in the galaxy population

The causes of the red sequence, the blue cloud, the green valley, and the green mountain

The galaxies found in optical surveys fall in two distinct regions of a diagram of optical colour versus absolute magnitude: the red sequence and the blue cloud, with the green valley in between. We show that the galaxies found in a submillimetre survey have almost the opposite distribution in this diagram, forming a \u27green mountain\u27. We show that these distinctive distributions follow naturally from a single, continuous, curved Galaxy Sequence in a diagram of specific star formation rate versus stellar mass, without there being the need for a separate star-forming galaxy main sequence and region of passive galaxies. The cause of the red sequence and the blue cloud is the geometric mapping between stellar mass/specific star formation rate and absolute magnitude/colour, which distorts a continuous Galaxy Sequence in the diagram of intrinsic properties into a bimodal distribution in the diagram of observed properties. The cause of the green mountain isMalmquist bias in the submillimetre waveband, with submillimetre surveys tending to select galaxies on the curve of the Galaxy Sequence, which have the highest ratios of submillimetre-to-optical luminosity. This effect, working in reverse, causes galaxies on the curve of the Galaxy Sequence to be underrepresented in optical samples, deepening the green valley. The green valley is therefore not evidence (1) for there being two distinct populations of galaxies, (2) for galaxies in this region evolving more quickly than galaxies in the blue cloud and the red sequence, and (3) for rapid-quenching processes in the galaxy population