389 research outputs found

    The strong environmental dependence of black hole scaling relations

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    We investigate how the scaling relations between central black hole mass (Mbh) and host galaxy properties (velocity dispersion, bulge stellar mass and bulge luminosity) depend on the large scale environment. For each of a sample of 69 galaxies with dynamical black hole measurements we compile four environmental measures (nearest neighbor distance, fixed aperture number density, total halo mass, and central/satellite). We find that central and satellite galaxies follow distinctly separate scalings in each of the three relations we have examined. The Mbh - sigma relation of central galaxies is significantly steeper (6.38 +/- 0.49) than that of satellite galaxies (4.91 +/- 0.49), but has a similar intercept. This behavior remains even after restricting to a sample of only early type galaxies or after removing the 8 brightest cluster galaxies. The Mbh - sigma relation shows more modest differences when splitting the sample based on the other environmental indicators, suggesting that they are driven by the underlying satellite/central fractions. Separate relations for centrals and satellites are also seen in the power law scaling between black hole mass and bulge stellar mass or bulge luminosity. We suggest that gas rich, low mass galaxies undergo a period of rapid black hole growth in the process of becoming satellites. If central galaxies on the current Mbh - sigma relation are representative progenitors of the satellite population, the observations imply that a sigma = 120 km/s galaxy must nearly triple its central black hole mass. The elevated black hole masses of massive central galaxies are then a natural consequence of the accretion of satellites.Comment: 16 pages, MNRAS, in pres

    Exercise and MEF2–HDAC interactions.

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    Exercise increases the metabolic capacity of skeletal muscle, which improves whole-body energy homeostasis and contributes to the positive health benefits of exercise. This is, in part, mediated by increases in the expression of a number of metabolic enzymes, regulated largely at the level of transcription. At a molecular level, many of these genes are regulated by the class II histone deacetylase (HDAC) family of transcriptional repressors, in particular HDAC5, through their interaction with myocyte enhancer factor 2 transcription factors. HDAC5 kinases, including 5&prime;-AMP-activated protein kinase and protein kinase D, appear to regulate skeletal muscle metabolic gene transcription by inactivating HDAC5 and inducing HDAC5 nuclear export. These mechanisms appear to participate in exercise-induced gene expression and could be important for skeletal muscle adaptations to exercise.<br /

    Linking gravitational waves and X-ray phenomena with joint LISA and Athena observations

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    The evolution of cosmic structures, the formation and growth of the first black holes and the connection to their baryonic environment are key unsolved problems in astrophysics. The X-ray Athena mission and the gravitational-wave Laser Interferometer Space Antenna (LISA) offer independent and complementary angles on these problems. We show that up to 10 black hole binaries in the mass range 10^5 - 10^8 Msun discovered by LISA at redshift <~ 3.5 could be detected by Athena in an exposure time up to 100 ks, if prompt X-ray emission of ~ 1% - 10% of the Eddington luminosity is present. Likewise, if any LISA-detected extreme mass ratio inspirals occur in accretion disks, Athena can detect associated electromagnetic emission out to redshift ~ 1. Finally, warned by LISA, Athena can point in advance and stare at stellar-mass binary black hole mergers at redshift <~ 0.1. These science opportunities emphasise the vast discovery space of simultaneous observations from the two observatories, which would be missed if they were operated in different epochs.Comment: Published in Nature Astronom

    Creating, communicating and measuring strategic objectives through the application of a balanced scorecard: the case of the University of Alaska Fairbanks Police Department

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    Master's Project (M.A.) University of Alaska Fairbanks, 2015This project served to align the vision and mission of the University of Alaska Fairbanks Police Department with the needs of the University community through the employment of a balanced scorecard. The balanced scorecard itself is a strategic performance management framework that enables organizations to identify, manage and measure strategic objectives. While there have been instances where police agencies have attempted to implement the balanced scorecard in the past, these police agencies have been very large, and they failed to achieve the level of granularity in their balanced scorecard necessary to effectively identify and manage true strategic objectives. In case of the University of Alaska Fairbanks Police Department, the balanced scorecard served to answer four fundamental questions: how will they sustain their ability to change and improve, what business processes must they excel at, how should they be perceived by their community, and how can they be responsible stewards of the funds that they are given

    The environmental dependence of rapidly-quenching and rejuvenating galaxies

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    By combining Ha flux measurements from the Sloan Digital Sky Survey (SDSS) with UV flux observations from the Galaxy Evolution Explorer (GALEX), we examine the environmental dependence (through central/satellite distinction) of the rapid quenching and rejuvenation of galaxies. Ha emissions trace the most massive stars, thereby indicating star-formation on timescales of ~ 10 Myr, while UV emission traces star-formation on timescales of ~ 100 Myr. These varying timescales are exploited to probe the most recent star-formation histories of galaxies. In this work, we define a class of transient galaxies which have UV emission typical of star formation but negligible Ha emission. We find that the occurrence of these transients has a strong stellar mass dependence in both the satellite and central population. However, while at stellar masses greater than M* ~ 10^10 Msun they occur with equal frequency regardless of environmental class, at lower stellar masses they are more common in satellites only, with an excess of about 1 per cent across all low stellar mass galaxies. These satellite transients also have a strong halo mass and group-centric radial dependence suggesting they are driven by an environmental process. Finally, we show that `rejuvenating' galaxies, those with Ha emission but not UV emission, are few in number and do not have a strong difference in their occurrence rate in centrals or satellites. These unique probes point to an environmental quenching mechanism which occurs on short timescales after the satellite has been in the group environment for a significant time -- consistent with `delayed-then-rapid' quenching

    Using The Balanced Scorecard To Reform University Policing: An Illustrative Example

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    Since the death of George Floyd, protestors nationwide have called for police reform, including on college campuses. This paper provides an illustrative example of how a balanced scorecard approach was utilized in the strategic reform of a campus police department. The study highlights how decision-makers can integrate the balanced scorecard’s use to successfully reform the campus police department and to create buy-in throughout the process

    Metallicity beats sSFR: The connection between superluminous supernova host galaxy environments and the importance of metallicity for their production

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    We analyse 33 Type I superluminous supernovae (SLSNe) taken from ZTF's Bright Transient Survey to investigate the local environments of their host galaxies. We use a spectroscopic sample of galaxies from the SDSS to determine the large-scale environmental density of the host galaxy. Noting that SLSNe are generally found in galaxies with low stellar masses, high star formation rates, and low metallicities, we find that SLSN hosts are also rarely found within high-density environments. Only 3+913\substack{+9 \\-1} per cent of SLSN hosts were found in regions with 2 or more bright galaxies within 2 Mpc. For comparison, we generate a sample of 662 SDSS galaxies matched to the photometric properties of the SLSN hosts. This sample is also rarely found within high-density environments, suggesting that galaxies with properties required for SLSN production favour more isolated environments. Furthermore, we select galaxies within the Illustris-TNG simulation to match SLSN host galaxy properties in colour and stellar mass. We find that the fraction of simulated galaxies in high-density environments quantitatively matches the observed SLSN hosts only if we restrict to simulated galaxies with metallicity 12+log(12+\log(O/H)8.12) \leq 8.12. In contrast, limiting to only the highest sSFR galaxies in the sample leads to an overabundance of SLSN hosts in high-density environments. Thus, our measurement of the environmental density of SLSN host galaxies appears to break the degeneracy between low-metallicity or high-sSFR as the driver for SLSN hosts and provides evidence that the most constraining factor on SLSN production is low-metallicity.Comment: Accepted to MNRAS, 10 pages, 6 figures. Re-uploaded for updating reference

    Metabolic profile analysis of zebrafish embryos

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    A growing goal in the field of metabolism is to determine the impact of genetics on different aspects of mitochondrial function. Understanding these relationships will help to understand the underlying etiology for a range of diseases linked with mitochondrial dysfunction, such as diabetes and obesity. Recent advances in instrumentation, has enabled the monitoring of distinct parameters of mitochondrial function in cell lines or tissue explants. Here we present a method for a rapid and sensitive analysis of mitochondrial function parameters in vivo during zebrafish embryonic development using the Seahorse bioscience XF 24 extracellular flux analyser. This protocol utilizes the Islet Capture microplates where a single embryo is placed in each well, allowing measurement of bioenergetics, including: (i) basal respiration; (ii) basal mitochondrial respiration (iii) mitochondrial respiration due to ATP turnover; (iv) mitochondrial uncoupled respiration or proton leak and (iv) maximum respiration. Using this approach embryonic zebrafish respiration parameters can be compared between wild type and genetically altered embryos (mutant, gene over-expression or gene knockdown) or those manipulated pharmacologically. It is anticipated that dissemination of this protocol will provide researchers with new tools to analyse the genetic basis of metabolic disorders in vivo in this relevant vertebrate animal model
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