103 research outputs found
Bone Density Following Long Duration Space Flight and Recovery
At approx.12 months, Bone Mineral Density (BMD) at most sites in men remained lower than would be predicted, raising concerns for long-term bone health consequences following space flight. Additional analyses based on longer follow-up are being conducted. Although the N is too small for definitive conclusions, women had lower rates of loss at load-bearing sites of the hip and spine immediately post-flight relative to men and smaller differences between observed vs. predicted BMD at most sites, both immediately and 12 months post-flight, relative to men. The role of other exposures/risk factors need to be explored to further understand these possible gender differences in BMD loss and recovery following long-duration space flight
DIAmante TESS AutoRegressive Planet Search (DTARPS): II. Hundreds of New TESS Candidate Exoplanets
The DIAmante TESS AutoRegressive Planet Search (DTARPS) project seeks to
identify photometric transiting planets from 976,814 southern hemisphere stars
observed in Year 1 of the TESS mission. This paper follows the methodology
developed by Melton et al. (Paper I) using light curves extracted and
pre-processed by the DIAmante project (Montalto et al. 2020). Paper I emerged
with a list of 7,377 light curves with statistical properties characteristic of
transiting planets but dominated by False Alarms and False Positives. Here a
multistage vetting procedure is applied including: centroid motion and crowding
metrics, False Alarm and False Positive reduction, photometric binary
elimination, and ephemeris match removal. The vetting produces a catalog of 462
DTARPS Candidates across the southern ecliptic hemisphere and 310 objects in a
spatially incomplete Galactic Plane list. Fifty-eight percent were not
previously identified as transiting systems. Candidates are flagged for
possible blending from nearby stars based on Zwicky Transient Facility data and
for possible radial velocity variations based on Gaia satellite data. Orbital
periods and planetary radii are refined using astrophysical modeling; the
resulting parameters closely match published values for Confirmed Planets.
Their properties are discussed in Paper III.Comment: 25 pages, 10 figures, submitted to AAS Journals. Machine Readable
Tables and Figure Sets for Tables 1 and 4 are available at
https://drive.google.com/drive/folders/1DyxNcNlfcHHAoCdsaipxxIbP5A2FPeyi?usp=share_lin
DIAmante TESS AutoRegressive Planet Search (DTARPS): III. Understanding the DTARPS Candidate Transiting Planet Catalogs
The DIAmante TESS AutoRegressive Planet Search (DTARPS) project, using novel
statistical methods, has identified several hundred candidates for transiting
planetary systems obtained from 0.9 million Full Frame Image light curves
obtained in the TESS Year 1 southern hemisphere survey (Melton et al. 2022a and
2022b). Several lines of evidence, including limited reconnaissance
spectroscopy, indicate that at least half are true planets rather than False
Positives. Here various population properties of these objects are examined.
Half of the DTARPS candidates are hot Neptunes, populating the 'Neptune desert'
found in Kepler planet samples. The DTARPS samples also identify dozens of
Ultra Short Period planets with orbital periods down to 5 hours, high priority
systems for atmospheric transimssion spectroscopy, and planets orbiting
low-mass M stars. DTARPS methodology is sufficiently well-characterized at each
step that preliminary planet occurrence rates can be estimated. Except for the
increase in hot Neptunes, DTARPS planet occurrence rates are consistent with
Kepler rates. Overall, DTARPS provides one of the largest and most reliable
catalog of TESS exoplanet candidates that can be tapped to improve our
understanding of various exoplanetary populations and astrophysical processes.Comment: 29 pages, 16 figures, submitted to the AAS Journals February 13, 202
DIAmante TESS AutoRegressive Planet Search (DTARPS): I. Analysis of 0.9 Million Light Curves
Nearly one million light curves from the TESS Year 1 southern hemisphere
extracted from Full Frame Images with the DIAmante pipeline are processed
through the AutoRegressive Planet Search statistical procedure. ARIMA models
remove trends and lingering autocorrelated noise, the Transit Comb Filter
identifies the strongest periodic signal in the light curve, and a Random
Forest machine learning classifier is trained and applied to identify the best
potential candidates. Classifier training sets include injections of both
planetary transit signals and contaminating eclipsing binaries. The optimized
classifier has a True Positive Rate of 92.8% and a False Positive Rate of 0.37%
from the labeled training set. The result of this DIAmante TESS autoregressive
planet search (DTARPS) analysis is a list of 7,377 potential exoplanet
candidates. The classifier has a False Positive Rate of 0.3%, a 64% recall rate
for previously confirmed exoplanets, and a 78% negative recall rate for known
False Positives. The completeness map of the injected planetary signals shows
high recall rates for planets with 8 - 30 R(Earth) radii and periods 0.6-13
days and poor completeness for planets with radii < 2 R(Earth) or periods < 1
day. The list has many False Alarms and False Positives that need to be culled
with multifaceted vetting operations (Paper II).Comment: 46 pages, 21 figures, submitted to AAS Journals. A Machine Readable
Table for Table 3 is available at
https://drive.google.com/drive/folders/1DyxNcNlfcHHAoCdsaipxxIbP5A2FPey
Gristhorpe Man: an Early Bronze Age log-coffin burial scientifically defined
© 2010 Antiquity PublicationsA log-coffin excavated in the early nineteenth century proved to be well enough preserved in the early twenty-first century for the fill armoury of modern scientific investigation to give its occupants and contents new identity, new origins and a new date. In many ways the interpretation is much the same as before: a local big man buried looking out to sea. Modern analytical techniques can create a person more real, more human and more securely anchored in history. This research team shows how.The project has been funded by grants from the British Academy, British Association for
the Advancement of Science, Natural Environment Research Council, Royal Archaeological
Institute and Scarborough Museums Trust. CJK’s participation in this project was funded
by a Leverhulme Research Fellowship (RF/6/RFG/2008/0253)
The future of evapotranspiration : global requirements for ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources
The fate of the terrestrial biosphere is highly uncertain given recent and projected changes in climate. This is especially acute for impacts associated with changes in drought frequency and intensity on the distribution and timing of water availability. The development of effective adaptation strategies for these emerging threats to food and water security are compromised by limitations in our understanding of how natural and managed ecosystems are responding to changing hydrological and climatological regimes. This information gap is exacerbated by insufficient monitoring capabilities from local to global scales. Here, we describe how evapotranspiration (ET) represents the key variable in linking ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources, and highlight both the outstanding science and applications questions and the actions, especially from a space-based perspective, necessary to advance them
Southeastern Association of Law Libraries Annual Meeting
The 2009 SEAALL Annual Meeting was held in Athens Georgia, April 16-18, 2009
Treatment with a corticotrophin releasing factor 2 receptor agonist modulates skeletal muscle mass and force production in aged and chronically ill animals
<p>Abstract</p> <p>Background</p> <p>Muscle weakness is associated with a variety of chronic disorders such as emphysema (EMP) and congestive heart failure (CHF) as well as aging. Therapies to treat muscle weakness associated with chronic disease or aging are lacking. Corticotrophin releasing factor 2 receptor (CRF2R) agonists have been shown to maintain skeletal muscle mass and force production in a variety of acute conditions that lead to skeletal muscle wasting.</p> <p>Hypothesis</p> <p>We hypothesize that treating animals with a CRF2R agonist will maintain skeletal muscle mass and force production in animals with chronic disease and in aged animals.</p> <p>Methods</p> <p>We utilized animal models of aging, CHF and EMP to evaluate the potential of CRF2R agonist treatment to maintain skeletal muscle mass and force production in aged animals and animals with CHF and EMP.</p> <p>Results</p> <p>In aged rats, we demonstrate that treatment with a CRF2R agonist for up to 3 months results in greater extensor digitorum longus (EDL) force production, EDL mass, soleus mass and soleus force production compared to age matched untreated animals. In the hamster EMP model, we demonstrate that treatment with a CRF2R agonist for up to 5 months results in greater EDL force production in EMP hamsters when compared to vehicle treated EMP hamsters and greater EDL mass and force in normal hamsters when compared to vehicle treated normal hamsters. In the rat CHF model, we demonstrate that treatment with a CRF2R agonist for up to 3 months results in greater EDL and soleus muscle mass and force production in CHF rats and normal rats when compared to the corresponding vehicle treated animals.</p> <p>Conclusions</p> <p>These data demonstrate that the underlying physiological conditions associated with chronic diseases such as CHF and emphysema in addition to aging do not reduce the potential of CRF2R agonists to maintain skeletal muscle mass and force production.</p
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