254 research outputs found
ALMA Observations of Circumnuclear Disks in Early Type Galaxies: 12CO(2-1) and Continuum Properties
We present results from an Atacama Large Millimeter/submillimeter Array
(ALMA) Cycle 2 program to map CO(2-1) emission in nearby early-type galaxies
(ETGs) that host circumnuclear gas disks. We obtained resolution
Band 6 observations of seven ETGs selected on the basis of dust disks in Hubble
Space Telescope images. We detect CO emission in five at high signal-to-noise
ratio with the remaining two only faintly detected. All CO emission is
coincident with the dust and is in dynamically cold rotation. Four ETGs show
evidence of rapid central rotation; these are prime candidates for
higher-resolution ALMA observations to measure the black hole masses. In this
paper we focus on the molecular gas and continuum properties. Total gas masses
and H column densities for our five CO-bright galaxies are on average
and cm over the kpc-scale
disks, and analysis suggests that these disks are stabilized against
gravitational fragmentation. The continuum emission of all seven galaxies is
dominated by a central, unresolved source, and in five we also detect a
spatially extended component. The 230 GHz nuclear continua are modeled as
power laws ranging from to within the
observed frequency band. The extended continuum profiles of the two
radio-bright (and CO-faint) galaxies are roughly aligned with their radio jet
and suggests resolved synchrotron jets. The extended continua of the CO-bright
disks are coincident with optically thick dust absorption and have spectral
slopes that are consistent with thermal dust emission.Comment: 20 pages, 10 figures; accepted for publication in Ap
A Precision Measurement of the Mass of the Black Hole in NGC 3258 from High-Resolution ALMA Observations of its Circumnuclear Disk
We present resolution Atacama Large
Millimeter/submillimeter Array (ALMA) CO(21) imaging of the arcsecond-scale
( pc) dusty molecular disk in the giant elliptical galaxy NGC
3258. The data provide unprecedented resolution of cold gas disk kinematics
within the dynamical sphere of influence of a supermassive black hole,
revealing a quasi-Keplerian central increase in projected rotation speed rising
from 280 km s at the disk's outer edge to km s near the
disk center. We construct dynamical models for the rotating disk and fit
beam-smeared model CO line profiles directly to the ALMA data cube. Our models
incorporate both flat disks and tilted-ring disks that provide a better fit of
the mildly warped structure in NGC 3258. We show that the exceptional angular
resolution of the ALMA data makes it possible to infer the host galaxy's mass
profile within pc solely from the ALMA CO kinematics, without relying
on optical or near-infrared imaging data to determine the stellar mass profile.
Our model therefore circumvents any uncertainty in the black hole mass that
would result from the substantial dust extinction in the galaxy's central
region. The best model fit yields
with a statistical model-fitting uncertainty of just 0.18\%, and systematic
uncertainties of 0.62\% from various aspects of the model construction and 12\%
from uncertainty in the distance to NGC 3258. This observation demonstrates the
full potential of ALMA for carrying out highly precise measurements of
in early-type galaxies containing circumnuclear gas disksComment: Accepted for publication in ApJ. 32 pages, 22 figure
MEASUREMENT OF THE BLACK HOLE MASS IN NGC 1332 FROM ALMA OBSERVATIONS AT 0.044 ARCSECOND RESOLUTION
We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 3 observations of CO(2-1) emission from the circumnuclear disk in the E/S0 galaxy NGC 1332 at 0.″044 resolution. The disk exhibits regular rotational kinematics and central high-velocity emission (±500 km s ) consistent with the presence of a compact central mass. We construct models for a thin, dynamically cold disk in the gravitational potential of the host galaxy and black hole and fit the beam-smeared model line profiles directly to the ALMA data cube. Model fits successfully reproduce the disk kinematics out to r = 200 pc. Fitting models just to spatial pixels within projected r = 50 pc of the nucleus (two times larger than the black hole's gravitational radius of influence), we find M =(6.64 ) × 10 M . This observation demonstrates ALMA's powerful capability to determine the masses of supermassive black holes by resolving gas kinematics on small angular scales in galaxy nuclei. -1 +0.65 8 BH -0.63
The Control of an Active Seat with Vehicle Suspension Preview Information
This paper presents a novel, simple and reliable control strategy for an active seat suspension, intended for use in a vehicle, which attenuates the harmful low-frequency vertical vibration at the driver’s seat. An advantage of this strategy is that it uses measurable preview information from the vehicle suspension. The control force is calculated from this preview information and controller gains obtained by optimising an objective function using a genetic algorithm (GA) approach. The objective function optimises ride comfort in terms of the Seat Effective Amplitude Transmissibility factor, taking into account constraints on both the allowable seat suspension stroke and actuator force capacity. This new controller is evaluated using both simulation and experimental tests in both the frequency and time domains. The simulation model is based upon a linear quarter vehicle model and a single degree of freedom seat suspension. Experimental tests are performed using a multi-axis simulation table and an active seat suspension. Finally, the performance of the active seat suspension is analysed and compared to a passive system, demonstrating significant acceleration attenuation of more than 10 dB across a broad frequency range. Consequently, this has the potential to improve ride comfort and hence reduce the driver’s fatigue using a reliable and cost-effective control method. </jats:p
Wandering Black Hole Candidates in Dwarf Galaxies at VLBI Resolution
Thirteen dwarf galaxies have recently been found to host radio-selected
accreting massive black hole (MBH) candidates, some of which are ``wandering"
in the outskirts of their hosts. We present 9 GHz Very Long Baseline Array
(VLBA) observations of these sources at milliarcsecond resolution. Our
observations have beam solid angles times smaller than the
previous Very Large Array (VLA) observations at 9 GHz, with comparable point
source sensitivities. We detect milliarcsecond-scale radio sources at the
positions of the four VLA sources most distant from the photo-centers of their
associated dwarf galaxies. These sources have brightness temperatures of
, consistent with active galactic nuclei (AGNs), but the
significance of their preferential location at large distances
(-value~) favors a background AGN interpretation. The VLBA
non-detections toward the other 9 galaxies indicate that the VLA sources are
resolved out on scales of tens of milliarcseconds, requiring extended radio
emission and lower brightness temperatures consistent with either star
formation or radio lobes associated with AGN activity. We explore the star
formation explanation by calculating the expected radio emission for these nine
VLBA non-detections, finding that about 5 have VLA luminosities that are
inconsistent with this scenario. Of the remaining four, two are associated with
spectroscopically confirmed AGNs that are consistent with being located at
their galaxy photo-centers. There are therefore between 5 and 7 wandering MBH
candidates out of the 13 galaxies we observed, although we cannot rule out
background AGNs for five of them with the data in hand.Comment: 13 pages, 3 figures, Accepted in Ap
Magnitude of and Prognostic Factors Associated With 1-Year Mortality After Hospital Discharge for Acute Decompensated Heart Failure Based on Ejection Fraction Findings
BACKGROUND: Limited data exist about the magnitude of and the factors associated with prognosis within 1 year for patients discharged from the hospital after acute decompensated heart failure. Data are particularly limited from the more generalizable perspective of a population-based investigation and should be further stratified according to currently recommended ejection fraction (EF) findings.
METHODS AND RESULTS: The hospital medical records of residents of the Worcester, Massachusetts, metropolitan area who were discharged after acute decompensated heart failure from all 11 medical centers in central Massachusetts during 1995, 2000, 2002, 2004, and 2006 were reviewed. The average age of the 4025 study patients was 75 years, 93% were white, and 44% were men. Of these, 35% (n=1414) had reduced EF ( \u3c /=40%), 13% (n=521) had borderline preserved EF (41-49%), and 52% (n=2090) had preserved EF ( \u3e /=50%); at 1 year after discharge, death rates were 34%, 30%, and 29%, respectively (P=0.03). Older age, a history of chronic obstructive pulmonary disease, systolic blood pressure findings \u3c 150 mm Hg on admission, and hyponatremia were important predictors of 1-year mortality for all study patients, whereas several comorbidities and physiological factors were differentially associated with 1-year death rates in patients with reduced, borderline preserved, and preserved EF.
CONCLUSIONS: This population-based study highlights the need for further contemporary research into the characteristics, treatment practices, natural history, and long-term outcomes of patients with acute decompensated heart failure and varying EF findings and reinforces ongoing discussions about whether different treatment guidelines may be needed for these patients to design more personalized treatment plans
Survival after hospital discharge for ST-segment elevation and non-ST-segment elevation acute myocardial infarction: a population-based study
BACKGROUND: Limited recent data are available describing differences in long-term survival, and factors affecting prognosis, after ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI), especially from the more generalizable perspective of a population-based investigation. The objectives of this study were to examine differences in post-discharge prognosis after hospitalization for STEMI and NSTEMI, with a particular focus on factors associated with reduced long-term survival.
METHODS: We reviewed the medical records of residents of the Worcester, MA, USA metropolitan area hospitalized at eleven central Massachusetts medical centers for acute myocardial infarction (AMI) during 2001, 2003, 2005, and 2007.
RESULTS: A total of 3762 persons were hospitalized with confirmed AMI; of these, 2539 patients (67.5%) were diagnosed with NSTEMI. The average age of study patients was 70.3 years and 42.9% were women. Patients with NSTEMI experienced higher post-discharge death rates with 3-month, 1-year, and 2-year death rates of 12.6%, 23.5%, and 33.2%, respectively, compared to 6.1%, 11.5%, and 16.4% for patients with STEMI. After multivariable adjustment, patients with NSTEMI were significantly more likely to have died after hospital discharge (adjusted hazards ratio 1.28; 95% confidence interval 1.14-1.44). Several demographic (eg, older age) and clinical (eg, history of stroke) factors were associated with reduced long-term survival in patients with NSTEMI and STEMI.
CONCLUSIONS: The results of this study in residents of central Massachusetts suggest that patients with NSTEMI are at higher risk for dying after hospital discharge, and several subgroups are at particularly increased risk
Black Hole Mass Measurements of Radio Galaxies NGC 315 and NGC 4261 Using ALMA CO Observations
We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 5 and
Cycle 6 observations of CO(21) and CO(32) emission at 0.2''0.3''
resolution in two radio-bright, brightest group/cluster early-type galaxies,
NGC 315 and NGC 4261. The data resolve CO emission that extends within their
black hole (BH) spheres of influence (), tracing regular
Keplerian rotation down to just tens of parsecs from the BHs. The projected
molecular gas speeds in the highly inclined () disks rises at least
500 km s near their galaxy centers. We fit dynamical models of thin-disk
rotation directly to the ALMA data cubes, and account for the extended stellar
mass distributions by constructing galaxy surface brightness profiles corrected
for a range of plausible dust extinction values. The best-fit models yield
for NGC 315 and
for NGC 4261, the latter of which is larger than previous estimates by a factor
of 3. The BH masses are broadly consistent with the relations between BH
masses and host galaxy properties. These are among the first ALMA observations
to map dynamically cold gas kinematics well within the BH-dominated regions of
radio galaxies, resolving the respective by factors of
510. The observations demonstrate ALMA's ability to precisely measure
BH masses in active galaxies, which will enable more confident probes of
accretion physics for the most massive galaxies.Comment: 24 pages, 11 figures, 4 tables. Accepted for publication in Ap
BEAGLE: An Application Programming Interface and High-Performance Computing Library for Statistical Phylogenetics
Phylogenetic inference is fundamental to our understanding of most aspects of the origin and evolution of life, and in recent years, there has been a concentration of interest in statistical approaches such as Bayesian inference and maximum likelihood estimation. Yet, for large data sets and realistic or interesting models of evolution, these approaches remain computationally demanding. High-throughput sequencing can yield data for thousands of taxa, but scaling to such problems using serial computing often necessitates the use of nonstatistical or approximate approaches. The recent emergence of graphics processing units (GPUs) provides an opportunity to leverage their excellent floating-point computational performance to accelerate statistical phylogenetic inference. A specialized library for phylogenetic calculation would allow existing software packages to make more effective use of available computer hardware, including GPUs. Adoption of a common library would also make it easier for other emerging computing architectures, such as field programmable gate arrays, to be used in the future. We present BEAGLE, an application programming interface (API) and library for high-performance statistical phylogenetic inference. The API provides a uniform interface for performing phylogenetic likelihood calculations on a variety of compute hardware platforms. The library includes a set of efficient implementations and can currently exploit hardware including GPUs using NVIDIA CUDA, central processing units (CPUs) with Streaming SIMD Extensions and related processor supplementary instruction sets, and multicore CPUs via OpenMP. To demonstrate the advantages of a common API, we have incorporated the library into several popular phylogenetic software packages. The BEAGLE library is free open source software licensed under the Lesser GPL and available from http://beagle-lib.googlecode.com. An example client program is available as public domain software.This work was supported by the National Science Foundation [grant numbers DBI-0755048, DEB-0732920, DEB-1036448, DMS-0931642, EF-0331495, EF-0905606, EF-0949453]; the National Institutes of Health [grant numbers R01-HG006139, R01-GM037841, R01-GM078985, R01-GM086887, R01-NS063897]; the Biotechnology and Biological Sciences Research Council [grant number BB/H011285/1]; the Wellcome Trust [grant number WT092807MA]; and Google Summer of Code
TraDIS-Xpress: a high-resolution whole-genome assay identifies novel mechanisms of triclosan action and resistance
Understanding the genetic basis for a phenotype is a central goal in biological research. Much has been learnt about bacterial genomes by creating large mutant libraries and looking for conditionally important genes. However, current genome-wide methods are largely unable to assay essential genes which are not amenable to disruption. To overcome this limitation, we developed a new version of “TraDIS” (transposon directed insertion-site sequencing) that we term “TraDIS-Xpress” that combines an inducible promoter into the transposon cassette. This allows controlled overexpression and repression of all genes owing to saturation of inserts adjacent to all open reading frames as well as conventional inactivation. We applied TraDIS-Xpress to identify responses to the biocide triclosan across a range of concentrations. Triclosan is endemic in modern life, but there is uncertainty about its mode of action with a concentration-dependent switch from bacteriostatic to bactericidal action unexplained. Our results show a concentration-dependent response to triclosan with different genes important in survival between static and cidal exposures. These genes include those previously reported to have a role in triclosan resistance as well as a new set of genes, including essential genes. Novel genes identified as being sensitive to triclosan exposure include those involved in barrier function, small molecule uptake, and integrity of transcription and translation. We anticipate the approach we show here, by allowing comparisons across multiple experimental conditions of TraDIS data, and including essential genes, will be a starting point for future work examining how different drug conditions impact bacterial survival mechanisms
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