689 research outputs found
Striking the right balance in right whale conservation
Author Posting. © The Authors, 2009. This article is posted here by permission of NRC Research Press for personal use, not for redistribution. The definitive version was published in Canadian Journal of Fisheries and Aquatic Sciences 66 (2009): 1399-1403, doi:10.1139/F09-115.Despite many years of study and protection, the North Atlantic right whale (Eubalaena glacialis) remains on the brink of extinction. There is a crucial gap in our understanding of their habitat use in the migratory corridor along the eastern seaboard of the United States. Here, we characterize habitat suitability in migrating right whales in relation to depth, distance to shore, and the recently enacted ship speed regulations near major ports. We find that the range of suitable habitat exceeds previous estimates and that, as compared with the enacted 20 nautical mile buffer, the originally proposed 30 nautical mile buffer would protect more habitat for this critically endangered species.This work was supported in part by SERDP/DoD grant
W912HQ-04-C-0011 to A.J. Read and P.N. Halpin as well
as a James B. Duke Fellowship and a Harvey L. Smith Dissertation
Year Fellowship to R.S. Schick
Very Low-Mass Stellar and Substellar Companions to Solar-Like Stars from MARVELS I: A Low Mass Ratio Stellar Companion to TYC 4110-01037-1 in a 79-day Orbit
TYC 4110-01037-1 has a low-mass stellar companion, whose small mass ratio and
short orbital period are atypical amongst solar-like (Teff ~< 6000 K) binary
systems. Our analysis of TYC 4110-01037-1 reveals it to be a moderately aged
(~<5 Gyr) solar-like star having a mass of 1.07 +/- 0.08 MSun and radius of
0.99 +/- 0.18 RSun. We analyze 32 radial velocity measurements from the
SDSS-III MARVELS survey as well as 6 supporting radial velocity measurements
from the SARG spectrograph on the 3.6m TNG telescope obtained over a period of
~2 years. The best Keplerian orbital fit parameters were found to have a period
of 78.994 +/- 0.012 days, an eccentricity of 0.1095 +/- 0.0023, and a
semi-amplitude of 4199 +/- 11 m/s. We determine the minimum companion mass (if
sin i = 1) to be 97.7 +/- 5.8 MJup. The system's companion to host star mass
ratio, >0.087 +/- 0.003, places it at the lowest end of observed values for
short period stellar companions to solar-like (Teff ~< 6000 K) stars. One
possible way to create such a system would be if a triple-component stellar
multiple broke up into a short period, low q binary during the cluster
dispersal phase of its lifetime. A candidate tertiary body has been identified
in the system via single-epoch, high contrast imagery. If this object is
confirmed to be co-moving, we estimate it would be a dM4 star. We present these
results in the context of our larger-scale effort to constrain the statistics
of low mass stellar and brown dwarf companions to FGK-type stars via the
MARVELS survey.Comment: 22 pages; accepted in A
Metabolic Remodeling of Human Skeletal Myocytes by Cocultured Adipocytes Depends on the Lipolytic State of the System
Adipocyte infiltration of the musculoskeletal system is well recognized as a hallmark of aging, obesity, and type 2 diabetes. Intermuscular adipocytes might serve as a benign storage site for surplus lipid or play a role in disrupting energy homeostasis as a result of dysregulated lipolysis or secretion of proinflammatory cytokines. This investigation sought to understand the net impact of local adipocytes on skeletal myocyte metabolism. Interactions between these two tissues were modeled using a coculture system composed of primary human adipocytes and human skeletal myotubes derived from lean or obese donors. Metabolic analysis of myocytes was performed after coculture with lipolytically silent or activated adipocytes and included transcript and metabolite profiling along with assessment of substrate selection and insulin action. Cocultured adipocytes increased myotube mRNA expression of genes involved in oxidative metabolism, regardless of the donor and degree of lipolytic activity. Adipocytes in the basal state sequestered free fatty acids, thereby forcing neighboring myotubes to rely more heavily on glucose fuel. Under this condition, insulin action was enhanced in myotubes from lean but not obese donors. In contrast, when exposed to lipolytically active adipocytes, cocultured myotubes shifted substrate use in favor of fatty acids, which was accompanied by intracellular accumulation of triacylglycerol and even-chain acylcarnitines, decreased glucose oxidation, and modest attenuation of insulin signaling. The effects of cocultured adipocytes on myocyte substrate selection and insulin action depended on the metabolic state of the system. These findings are relevant to understanding the metabolic consequences of intermuscular adipogenesis
Experiencing mindfulness meditation—a client narrative perspective
The study was based on the non-participant involvement of the researcher in four six-to-eight weeks' mindfulness meditation training courses led by chartered psychologists. The participants suffered from stress/sleeplessness, depression or agoraphobia in the presented cases. They were selected on the basis of recommendations by the psychologist who was the course instructor, who described them as positive and suitable. The participants wrote diaries on a weekly basis, and they were interviewed at the beginning, middle and end of the course. An in-depth analysis of three individual cases will be presented in the form of narratives constructed from their own words. The narratives demonstrate the unique and embodied changes of the individual participant's experiences during the training course. The purpose was to illustrate richly what happens and how changes happen during these weeks of learning and practicing mindfulness meditation. It is not the intention to give evidence about the effectiveness of mindfulness meditation in general, but to present the whats and hows of cases where mindfulness meditation appears to improve quality of life, health and well-being
X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey
The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey of the
entire sky. While X-ray source counterparts are known to range from distant
quasars to nearby M dwarfs, the RASS data alone are often insufficient to
determine the nature of an X-ray source. As a result, large-scale follow-up
programs are required to construct samples of known X-ray emitters. We use
optical data produced by the Sloan Digital Sky Survey (SDSS) to identify 709
stellar X-ray emitters cataloged in the RASS and falling within the SDSS Data
Release 1 footprint. Most of these are bright stars with coronal X-ray emission
unsuitable for SDSS spectroscopy, which is designed for fainter objects (g > 15
mag). Instead, we use SDSS photometry, correlations with the Two Micron All Sky
Survey and other catalogs, and spectroscopy from the Apache Point Observatory
3.5 m telescope to identify these stellar X-ray counterparts. Our sample of 707
X-ray-emitting F, G, K, and M stars is one of the largest X-ray-selected
samples of such stars. We derive distances to these stars using photometric
parallax relations appropriate for dwarfs on the main sequence, and use these
distances to calculate LX. We also identify a previously unknown cataclysmic
variable (CV) as a RASS counterpart. Separately, we use correlations of the
RASS and the SDSS spectroscopic catalogs of CVs and white dwarfs (WDs) to study
the properties of these rarer X-ray-emitting stars. We examine the relationship
between (fX/fg) and the equivalent width of the Hbeta emission line for 46
X-ray-emitting CVs and discuss tentative classifications for a subset based on
these quantities. We identify 17 new X-ray-emitting DA (hydrogen) WDs, of which
three are newly identified WDs. (abridged)Comment: 23 pages, 15 figures, 8 tables; full catalog available online onl
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b
We present the highest fidelity spectrum to date of a planetary-mass object.
VHS 1256 b is a 20 M widely separated (8\arcsec, a =
150 au), young, planetary-mass companion that shares photometric colors and
spectroscopic features with the directly imaged exoplanets HR 8799 c, d, and e.
As an L-to-T transition object, VHS 1256 b exists along the region of the
color-magnitude diagram where substellar atmospheres transition from cloudy to
clear. We observed VHS 1256~b with \textit{JWST}'s NIRSpec IFU and MIRI MRS
modes for coverage from 1 m to 20 m at resolutions of 1,000 -
3,700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium
are observed in several portions of the \textit{JWST} spectrum based on
comparisons from template brown dwarf spectra, molecular opacities, and
atmospheric models. The spectral shape of VHS 1256 b is influenced by
disequilibrium chemistry and clouds. We directly detect silicate clouds, the
first such detection reported for a planetary-mass companion.Comment: Accepted ApJL Iterations of spectra reduced by the ERS team are
hosted at this link:
https://github.com/bemiles/JWST_VHS1256b_Reduction/tree/main/reduced_spectr
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems IV: NIRISS Aperture Masking Interferometry Performance and Lessons Learned
We present a performance analysis for the aperture masking interferometry
(AMI) mode on board the James Webb Space Telescope Near Infrared Imager and
Slitless Spectrograph (JWST/NIRISS). Thanks to self-calibrating observables,
AMI accesses inner working angles down to and even within the classical
diffraction limit. The scientific potential of this mode has recently been
demonstrated by the Early Release Science (ERS) 1386 program with a deep search
for close-in companions in the HIP 65426 exoplanetary system. As part of ERS
1386, we use the same dataset to explore the random, static, and calibration
errors of NIRISS AMI observables. We compare the observed noise properties and
achievable contrast to theoretical predictions. We explore possible sources of
calibration errors, and show that differences in charge migration between the
observations of HIP 65426 and point-spread function calibration stars can
account for the achieved contrast curves. Lastly, we use self-calibration tests
to demonstrate that with adequate calibration, NIRISS AMI can reach contrast
levels of mag. These tests lead us to observation planning
recommendations and strongly motivate future studies aimed at producing
sophisticated calibration strategies taking these systematic effects into
account. This will unlock the unprecedented capabilities of JWST/NIRISS AMI,
with sensitivity to significantly colder, lower mass exoplanets than
ground-based setups at orbital separations inaccessible to JWST coronagraphy.Comment: 20 pages, 12 figures, submitted to AAS Journal
The \textit{JWST} Early Release Science Program for Direct Observations of Exoplanetary Systems III: Aperture Masking Interferometric Observations of the star HIP\,65426 at
We present aperture masking interferometry (AMI) observations of the star HIP
65426 at as a part of the \textit{JWST} Direct Imaging Early
Release Science (ERS) program obtained using the Near Infrared Imager and
Slitless Spectrograph (NIRISS) instrument. This mode provides access to very
small inner working angles (even separations slightly below the Michelson limit
of for an interferometer), which are inaccessible with the
classical inner working angles of the \textit{JWST} coronagraphs. When combined
with \textit{JWST}'s unprecedented infrared sensitivity, this mode has the
potential to probe a new portion of parameter space across a wide array of
astronomical observations. Using this mode, we are able to achieve a contrast
of \,mag relative to the host star at a separation
of {\sim}0.07\arcsec but detect no additional companions interior to the
known companion HIP\,65426\,b. Our observations thus rule out companions more
massive than 10{-}12\,\rm{M\textsubscript{Jup}} at separations
from HIP\,65426, a region out of reach of ground or
space-based coronagraphic imaging. These observations confirm that the AMI mode
on \textit{JWST} is sensitive to planetary mass companions orbiting at the
water frost line, even for more distant stars at 100\,pc. This result
will allow the planning and successful execution of future observations to
probe the inner regions of nearby stellar systems, opening essentially
unexplored parameter space.Comment: 15 pages, 9 figures, submitted to ApJ Letter
Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial
Background: The EMPA KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population. Methods: EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110. Findings: Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5–2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62–0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16–1·59), representing a 50% (42–58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1). Interpretation: In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease. Funding: Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council
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