The Structure of Active Merger Remnant NGC 6240 from IRAC Observations

NGC 6240 is a rare object in the local universe: an active merger remnant viewed at the point of merging where two active galactic nuclei are visible. We present IRAC data of this object, providing high sensitivity maps of the stellar and PAH distribution in this complicated system. We use photometry to analyze the variation in these distributions with radius and provide an SED in the four IRAC bands: 3.6 microns, 4.5 microns, 5.8 microns and 8.0 microns. We fit the radial profiles of the 3.6 micron band to r^.25 and exponential profiles to evaluate the structure of the remnant. Finally, we compare the IRAC images with multi-wavelength data and examine how outflows in the X-ray, Halpha and CO correlate with 8 micron emission. The results support the general picture of NGC 6240 as a system experiencing a major merger and transitioning from a disk galaxy to a spheroid. The sensitivity of IRAC to low surface brightness mid-infrared features provides detailed information on the extended distributions of stars and dust in this rare system.Comment: Accepted for publication in Ap

The effect of increased convective entrainment on Asian monsoon biases in the MetUM General Circulation Model

We demonstrate that summer precipitation biases in the South Asian monsoon domain are sensitive to increasing the convective parametrisation’s entrainment and detrainment rates in the Met Office Unified Model. We explore this sensitivity to improve our understanding of the biases and inform efforts to improve convective parametrisation. We perform novel targeted experiments in which we increase the entrainment and detrainment rates in regions of especially large precipitation bias. We use these experiments to determine whether the sensitivity at a given location is a consequence of the local change to convection or is a remote response to the change elsewhere. We find that a local change leads to different mean-state responses in comparable regions. When the entrainment and detrainment rates are increased globally, feedbacks between regions usually strengthen the local responses. We choose two regions of tropical ascent that show different mean-state responses, the western equatorial Indian Ocean and western north Pacific, and analyse them as case studies to determine the mechanisms leading to the different responses. Our results indicate that several aspects of a region’s mean-state, including moisture content, sea surface temperature and circulation, play a role in local feedbacks that determine the response to increased entrainment and detrainment

Neutral Hydrogen in the Interacting Magellanic Spirals NGC 4618/4625

Asymmetry is a common trait in spiral galaxies and is particularly frequent among Magellanic spirals. To explore how morphological and kinematic asymmetry are affected by companion galaxies, we analyze neutral hydrogen observations of the interacting Magellanic spirals NGC 4618 and 4625. The analysis of the H I distribution revealed that about 10% of the total H I mass of NGC 4618 resides in a looping tidal structure that appears to wrap all the way around the galaxy. Through calculations based on derived H I profiles, we show that NGC 4618 and 4625 are no more asymmetric than non-interacting Magellanic spirals analyzed by Wilcots & Prescott (2004). We also derive rotation curves for the approaching and receding sides of each galaxy. By fitting the mean curves with an isothermal halo model, we calculate dynamical masses of 4.7 times 10^{9} M_sun and 9.8 times 10^{9} M_sun out to 6.7 kpc, for NGC 4618 and 4625 respectively. While the rotation curves had systematically higher velocities on the receding side of each galaxy, the effect was no more pronounced than in studies of non-interacting spirals (Swaters et. al. 1999). The degree of interaction-driven asymmetry in both galaxies is indistinguishable from the intrinsic degree of asymmetry of lopsided galaxies.Comment: 20 pages, 11 figures, accepted for publication in the Astronomical Journa

Spiral-Induced Star Formation in the Outer Disks of Galaxies

The outer regions of galactic disks have received increased attention since ultraviolet observations with GALEX demonstrated that nearly 30% of galaxies have UV emission beyond their optical extents, indicating star formation activity. These galaxies have been termed extended UV (XUV) disks. Here, we address whether these observations contradict the gas surface density threshold for star formation inferred from Halpha radial profiles of galaxies. We run smoothed particle hydrodynamics simulations of isolated disk galaxies with fiducial star formation prescriptions and show that over-densities owing to the presence of spiral structure can induce star formation in extended gas disks. For direct comparison with observations, we use the 3-D radiative transfer code Sunrise to create simulated FUV and K_s band images. We find that galaxies classified as Type I XUV disks are a natural consequence of spiral patterns, but we are unable to reproduce Type II XUV disks. We also compare our results to studies of the Kennicutt-Schmidt relation in outer disks.Comment: Published in Ap

The Alzheimer's Disease-Associated Amyloid β-Protein Is an Antimicrobial Peptide

Background: The amyloid $\beta$-protein (A$\beta$) is believed to be the key mediator of Alzheimer's disease (AD) pathology. A$\beta$ is most often characterized as an incidental catabolic byproduct that lacks a normal physiological role. However, A$\beta$ has been shown to be a specific ligand for a number of different receptors and other molecules, transported by complex trafficking pathways, modulated in response to a variety of environmental stressors, and able to induce pro-inflammatory activities. Methodology/Principal Findings: Here, we provide data supporting an in vivo function for A$\beta$ as an antimicrobial peptide (AMP). Experiments used established in vitro assays to compare antimicrobial activities of A$\beta$ and LL-37, an archetypical human AMP. Findings reveal that A$\beta$ exerts antimicrobial activity against eight common and clinically relevant microorganisms with a potency equivalent to, and in some cases greater than, LL-37. Furthermore, we show that AD whole brain homogenates have significantly higher antimicrobial activity than aged matched non-AD samples and that AMP action correlates with tissue A$\beta$ levels. Consistent with A$\beta$-mediated activity, the increased antimicrobial action was ablated by immunodepletion of AD brain homogenates with anti-A$\beta$ antibodies. Conclusions/Significance: Our findings suggest A$\beta$ is a hitherto unrecognized AMP that may normally function in the innate immune system. This finding stands in stark contrast to current models of A$\beta$-mediated pathology and has important implications for ongoing and future AD treatment strategies

The role of taxonomic expertise in interpretation of metabarcoding studies

Abstract The performance of DNA metabarcoding approaches for characterizing biodiversity can be influenced by multiple factors. Here, we used morphological assessment of taxa in zooplankton samples to develop a large barcode database and to assess the congruence of taxonomic identification with metabarcoding under different conditions. We analysed taxonomic assignment of metabarcoded samples using two genetic markers (COI, 18S V1–2), two types of clustering into molecular operational taxonomic units (OTUs, ZOTUs), and three methods for taxonomic assignment (RDP Classifier, BLASTn to GenBank, BLASTn to a local barcode database). The local database includes 1042 COI and 1108 18S (SSU) barcode sequences, and we added new high-quality sequences to GenBank for both markers, including 109 contributions at the species level. The number of phyla detected and the number of taxa identified to phylum varied between a genetic marker and among the three methods used for taxonomic assignments. Blasting the metabarcodes to the local database generated multiple unique contributions to identify OTUs and ZOTUs. We argue that a multi-marker approach combined with taxonomic expertise to develop a curated, vouchered, local barcode database increases taxon detection with metabarcoding, and its potential as a tool for zooplankton biodiversity surveys

Quality standards for managing children and adolescents with bronchiectasis: an international consensus

The global burden of bronchiectasis in children and adolescents is being recognised increasingly. However, marked inequity exists between, and within, settings and countries for resources and standards of care afforded to children and adolescents with bronchiectasis compared with those with other chronic lung diseases. The European Respiratory Society (ERS) clinical practice guideline for the management of bronchiectasis in children and adolescents was published recently. Here we present an international consensus of quality standards of care for children and adolescents with bronchiectasis based upon this guideline. The panel used a standardised approach that included a Delphi process with 201 respondents from the parents and patients’ survey, and 299 physicians (across 54 countries) who care for children and adolescents with bronchiectasis. The seven quality standards of care statements developed by the panel address the current absence of quality standards for clinical care related to paediatric bronchiectasis. These internationally derived, clinician-, parent-and patient-informed, consensus-based quality standards statements can be used by parents and patients to access and advocate for quality care for their children and themselves, respectively. They can also be used by healthcare professionals to advocate for their patients, and by health services as a monitoring tool, to help optimise health outcomes.</p

Speech Communication

Contains reports on two research projects.National Institutes of Health (Grant 2 ROl1 NS04332)National Institutes of Health (Training Grant 5 T32 NS07040)C.J. LeBel FellowshipsNational Science Foundation (Grant BNS77-26871

Altered hippocampal-prefrontal neural dynamics in mouse models of Down syndrome

Altered neural dynamics in the medial prefrontal cortex (mPFC) and hippocampus may contribute to cognitive impairments in the complex chromosomal disorder Down syndrome (DS). Here, we demonstrate non-overlapping behavioral differences associated with distinct abnormalities in hippocampal and mPFC electrophysiology during a canonical spatial working memory task in three partially trisomic mouse models of DS (Dp1Tyb, Dp10Yey, and Dp17Yey) that together cover all regions of homology with human chromosome 21 (Hsa21). Dp1Tyb mice show slower decision-making (unrelated to the gene dose of DYRK1A, which has been implicated in DS cognitive dysfunction) and altered theta dynamics (reduced frequency, increased hippocampal-mPFC coherence, and increased modulation of hippocampal high gamma); Dp10Yey mice show impaired alternation performance and reduced theta modulation of hippocampal low gamma; and Dp17Yey mice are not significantly different from the wild type. These results link specific hippocampal and mPFC circuit dysfunctions to cognitive deficits in DS models and, importantly, map them to discrete regions of Hsa21