294 research outputs found
Mid-infrared properties of OH megamaser host galaxies. II: Analysis and modeling of the maser environment
We present a comparison of Spitzer IRS data for 51 OH megamaser (OHM) hosts
and 15 non-masing ULIRGs. 10-25% of OHMs show evidence for the presence of an
AGN, significantly lower than the estimated AGN fraction from previous optical
and radio studies. Non-masing ULIRGs have a higher AGN fraction (50-95%) than
OHMs, although some galaxies in both samples show evidence of co-existing
starbursts and AGN. Radiative transfer models of the dust environment reveal
that non-masing galaxies tend to have clumpy dust geometries commonly
associated with AGN, while OHMs have deeper absorption consistent with a
smooth, thick dust shell. Statistical analyses show that the major differences
between masing and non-masing ULIRGs in the mid-IR relate to the optical depth
and dust temperature, which we measure using the 9.7 um silicate depth and
30-20 um spectral slope from the IRS data. Dust temperatures of 40-80 K derived
from the IRS data are consistent with predictions of OH pumping models and with
a minimum T_dust required for maser production. The best-fit dust opacities
({\tau}_V ~ 100 - 400), however, are nearly an order of magnitude larger than
those predicted for OH inversion, and suggest that modifications to the model
may be required. These diagnostics offer the first detailed test of an OHM
pumping model based only on the properties of its host galaxy and provide
important restrictions on the physical conditions relevant to OHM production.Comment: 15 pages, 12 figures; accepted to Ap
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale XXIV: The Calibration of Tully-Fisher Relations and the Value of the Hubble Constant
This paper presents the calibration of BVRIH$ Tully-Fisher relations based on
Cepheid distances to 21 galaxies within 25 Mpc, and 23 clusters within 10,000
km/s. These relations have been applied to several distant cluster surveys in
order to derive a value for the Hubble constant, H0, mainly concentrating on an
I-band all-sky survey by Giovanelli and collaborators which consisted of total
I magnitudes and 50% linewidth data for ~550 galaxies in 16 clusters. For
comparison, we also derive the values of H0 using surveys in B-band and V-band
by Bothun and collaborators, and in H-band by Aaronson and collaborators.
Careful comparisons with various other databases from literature suggest that
the H-band data, whose magnitudes are isophotal magnitudes extrapolated from
aperture magnitudes rather than total magnitudes, are subject to systematic
uncertainties. Taking a weighted average of the estimates of Hubble constants
from four surveys, we obtain H0 = 71 +- 4 (random) +- 7 (systematic) km/s/Mpc.
We have also investigated how various systematic uncertainties affect the value
of H0 such as the internal extinction correction method used, Tully-Fisher
slopes and shapes, a possible metallicity dependence of the Cepheid
period-luminosity relation and cluster population incompleteness bias.Comment: 34 pages, 13 figure
Scaling of swimming performance in baleen whales
The scale dependence of locomotor factors has long been studied in comparative biomechanics, but remains poorly understood for animals at the upper extremes of body size. Rorqual baleen whales include the largest animals, but we lack basic kinematic data about their movements and behavior below the ocean surface. Here, we combined morphometrics from aerial drone photogrammetry, whale-borne inertial sensing tag data and hydrodynamic modeling to study the locomotion of five rorqual species. We quantified changes in tail oscillatory frequency and cruising speed for individual whales spanning a threefold variation in body length, corresponding to an order of magnitude variation in estimated body mass. Our results showed that oscillatory frequency decreases with body length (proportional to length(-0.5)(3)) while cruising speed remains roughly invariant (proportional to length(0.08)) at 2 m s(-1). We compared these measured results for oscillatory frequency against simplified models of an oscillating cantilever beam (proportional to length(-1)) and an optimized oscillating Strouhal vortex generator (proportional to length(-1)). The difference between our length-scaling exponent and the simplified models suggests that animals are often swimming non-optimally in order to feed or perform other routine behaviors. Cruising speed aligned more closely with an estimate of the optimal speed required to minimize the energetic cost of swimming (proportional to length(-1)). Our results are among the first to elucidate the relationships between both oscillatory frequency and cruising speed and body size for free-swimming animals at the largest scale
Distinct and shared functions of ALS-associated proteins TDP-43, FUS and TAF15 revealed by multisystem analyses
The RNA-binding protein (RBP) TAF15 is implicated in amyotrophic lateral sclerosis (ALS). To compare TAF15 function to that of two ALS-associated RBPs, FUS and TDP-43, we integrate CLIP-seq and RNA Bind-N-Seq technologies, and show that TAF15 binds to ∼4,900 RNAs enriched for GGUA motifs in adult mouse brains. TAF15 and FUS exhibit similar binding patterns in introns, are enriched in 3′ untranslated regions and alter genes distinct from TDP-43. However, unlike FUS and TDP-43, TAF15 has a minimal role in alternative splicing. In human neural progenitors, TAF15 and FUS affect turnover of their RNA targets. In human stem cell-derived motor neurons, the RNA profile associated with concomitant loss of both TAF15 and FUS resembles that observed in the presence of the ALS-associated mutation FUS R521G, but contrasts with late-stage sporadic ALS patients. Taken together, our findings reveal convergent and divergent roles for FUS, TAF15 and TDP-43 in RNA metabolism.National Institutes of Health (U.S.) (Grant HG007005
Lunar Water Resource Demonstration (LWRD) Test Results
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Myeloid Slc2a1-Deficient Murine Model Revealed Macrophage Activation and Metabolic Phenotype Are Fueled by GLUT1
Macrophages (MΦs) are heterogeneous and metabolically flexible, with metabolism strongly affecting immune activation. A classic response to proinflammatory activation is increased flux through glycolysis with a downregulation of oxidative metabolism, whereas alternative activation is primarily oxidative, which begs the question of whether targeting glucose metabolism is a viable approach to control MΦ activation. We created a murine model of myeloid-specific glucose transporter GLUT1 (Slc2a1) deletion. Bone marrow-derived MΦs (BMDM) from Slc2a1M-/- mice failed to uptake glucose and demonstrated reduced glycolysis and pentose phosphate pathway activity. Activated BMDMs displayed elevated metabolism of oleate and glutamine, yet maximal respiratory capacity was blunted in MΦ lacking GLUT1, demonstrating an incomplete metabolic reprogramming. Slc2a1M-/- BMDMs displayed a mixed inflammatory phenotype with reductions of the classically activated pro- and anti-inflammatory markers, yet less oxidative stress. Slc2a1M-/- BMDMs had reduced proinflammatory metabolites, whereas metabolites indicative of alternative activation-such as ornithine and polyamines-were greatly elevated in the absence of GLUT1. Adipose tissue MΦs of lean Slc2a1M-/- mice had increased alternative M2-like activation marker mannose receptor CD206, yet lack of GLUT1 was not a critical mediator in the development of obesity-associated metabolic dysregulation. However, Ldlr-/- mice lacking myeloid GLUT1 developed unstable atherosclerotic lesions. Defective phagocytic capacity in Slc2a1M-/- BMDMs may have contributed to unstable atheroma formation. Together, our findings suggest that although lack of GLUT1 blunted glycolysis and the pentose phosphate pathway, MΦ were metabolically flexible enough that inflammatory cytokine release was not dramatically regulated, yet phagocytic defects hindered MΦ function in chronic diseases
Dark sectors 2016 Workshop: community report
This report, based on the Dark Sectors workshop at SLAC in April 2016,
summarizes the scientific importance of searches for dark sector dark matter
and forces at masses beneath the weak-scale, the status of this broad
international field, the important milestones motivating future exploration,
and promising experimental opportunities to reach these milestones over the
next 5-10 years
A Two-Component Probability Distribution Function Describes the mid-IR Emission from the Disks of Star-Forming Galaxies
High-resolution JWST-MIRI images of nearby spiral galaxies reveal emission
with complex substructures that trace dust heated both by massive young stars
and the diffuse interstellar radiation field. We present high angular (0."85)
and physical resolution (20-80 pc) measurements of the probability distribution
function (PDF) of mid-infrared (mid-IR) emission (7.7-21 m) from 19 nearby
star-forming galaxies from the PHANGS-JWST Cycle-1 Treasury. The PDFs of mid-IR
emission from the disks of all 19 galaxies consistently show two distinct
components: an approximately log-normal distribution at lower intensities and a
high-intensity power-law component. These two components only emerge once
individual star-forming regions are resolved. Comparing with locations of HII
regions identified from VLT/MUSE H-mapping, we infer that the power-law
component arises from star-forming regions and thus primarily traces dust
heated by young stars. In the continuum-dominated 21 m band, the power-law
is more prominent and contains roughly half of the total flux. At 7.7-11.3
m, the power-law is suppressed by the destruction of small grains
(including PAHs) close to HII regions while the log-normal component tracing
the dust column in diffuse regions appears more prominent. The width and shape
of the log-normal diffuse emission PDFs in galactic disks remain consistent
across our sample, implying a log-normal gas column density
(H)cm shaped by supersonic turbulence with typical
(isothermal) turbulent Mach numbers . Finally, we describe how the
PDFs of galactic disks are assembled from dusty HII regions and diffuse gas,
and discuss how the measured PDF parameters correlate with global properties
such as star-formation rate and gas surface density.Comment: 30 pages without appendix, 17 figures, (with appendix images of full
sample: 56 pages, 39 figures), accepted in A
The impact of general practitioners working in or alongside emergency departments: a rapid realist review
Objectives Worldwide, emergency healthcare systems are under intense pressure from ever-increasing demand and evidence is urgently needed to understand how this can be safely managed. An estimated 10%–43% of emergency department patients could be treated by primary care services. In England, this has led to a policy proposal and £100 million of funding (US$130 million), for emergency departments to stream appropriate patients to
a co-located primary care facility so they are ‘free to care for the sickest patients’. However, the research evidence to support this initiative is weak.
Design Rapid realist literature review.
Setting Emergency departments.
Inclusion criteria Articles describing general practitioners working in or alongside emergency departments.
Aim: To develop context-specific theories that explain how and why general practitioners working in or alongside emergency departments affect: patient flow; patient experience; patient safety and the wider healthcare system.
Results: Ninety-six articles contributed data to theory development sourced from earlier systematic reviews, updated database searches (Medline, Embase, CINAHL, Cochrane DSR & CRCT, DARE, HTA Database, BSC, PsycINFO and SCOPUS) and citation tracking. We developed theories to explain: how staff interpret the streaming system; different roles general practitioners adopt in the emergency department setting (traditional, extended, gatekeeper or emergency clinician) and how these factors influence patient (experience and safety) and organisational (demand and cost-effectiveness) outcomes.
Conclusions: Multiple factors influence the effectiveness of emergency department streaming to general practitioners; caution is needed in embedding the policy until further research and evaluation are available. Service models that encourage the traditional general practitioner approach may have shorter process times for non-urgent patients; however, there is little evidence that this frees up emergency department staff to care for the sickest
patients. Distinct primary care services offering increased patient choice may result in provider-induced demand. Economic evaluation and safety requires further research.
PROSPERO registration number CRD42017069741
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