528 research outputs found
Developing an Electromechanical Carbon Dioxide Sensor for Occupancy Monitoring
The Energy Information Administration reported in 2012 that heating and cooling processes consume nearly 35% of the total energy used by commercial buildings. In an effort to limit the amount of energy wasted in conditioning empty buildings and rooms, various occupancy detection techniques have been developed that can be paired with a smart heating, ventilation, and air conditioning (HVAC) control system. This work focused on the development of a novel carbon dioxide detector that is sensitive enough to accurately determine if, and when, a room is occupied. To test the new sensor design, a customized chamber with gas inlets was used to isolate the sensors in a controlled environment. The sensors were tested in this chamber alongside various commercial-off-the-shelf options for the purpose of both validating the developed sensors and observing if they exhibited increased sensitivity and selectivity over previous designs. Following these tests, the overall performance of the sensors was compared. The results of this comparison were subsequently used to assess the capabilities of the sensor designs and to identify areas for further improvement
Molecular Hydrogen in the FUSE Translucent Lines of Sight: The Full Sample
We report total abundances and related parameters for the full sample of the
FUSE survey of molecular hydrogen in 38 translucent lines of sight. New results
are presented for the "second half" of the survey involving 15 lines of sight
to supplement data for the first 23 lines of sight already published. We assess
the correlations between molecular hydrogen and various extinction parameters
in the full sample, which covers a broader range of conditions than the initial
sample. In particular, we are now able to confirm that many, but not all, lines
of sight with shallow far-UV extinction curves and large values of the
total-to-selective extinction ratio, = / -- characteristic
of larger than average dust grains -- are associated with particularly low
hydrogen molecular fractions (). In the lines of sight with large
, there is in fact a wide range in molecular fractions, despite the
expectation that the larger grains should lead to less H formation.
However, we see specific evidence that the molecular fractions in this
sub-sample are inversely related to the estimated strength of the UV radiation
field and thus the latter factor is more important in this regime. We have
provided an update to previous values of the gas-to-dust ratio, (H)/, based on direct measurements of (H) and (H I).
Although our value is nearly identical to that found with Copernicus data, it
extends the relationship by a factor of 2 in reddening. Finally, as the new
lines of sight generally show low to moderate molecular fractions, we still
find little evidence for single monolithic "translucent clouds" with 1.Comment: 35 pages, 5 tables, 7 figures, accepted for publication in The
Astrophysical Journal Supplements Serie
Diabetes by Air, Land, and Sea: Effect of Deployments on HbA1c and BMI
INTRODUCTION: Service members (SMs) in the United States (U.S.) Armed Forces have diabetes mellitus at a rate of 2-3%. Despite having a chronic medical condition, they have deployed to environments with limited medical support. Given the scarcity of data describing how they fare in these settings, we conducted a retrospective study analyzing the changes in glycated hemoglobin (HbA1c) and body mass index (BMI) before and after deployment.
MATERIALS AND METHODS: SMs from the U.S. Army, Air Force, Navy, and Marine Corps with diabetes who deployed overseas were identified through the Military Health System (MHS) Management Analysis and Reporting Tool and the Defense Manpower Data Center. Laboratory and pharmaceutical data were obtained from the MHS Composite Health Care System and the Pharmacy Data Transaction Service, respectively. Paired t-tests were conducted to calculate changes in HbA1c and BMI before and after deployment.
RESULTS: SMs with diabetes completed 11,325 deployments of greater than 90 days from 2005 to 2017. Of these, 474 (4.2%) SMs had both HbA1c and BMI measurements within 90 days prior to departure and within 90 days of return. Most (84.2%) required diabetes medications: metformin in 67.3%, sulfonylureas in 19.0%, dipeptidyl peptidase-4 inhibitors in 13.9%, and insulin in 5.5%. Most SMs deployed with an HbA1c \u3c 7.0% (67.1%), with a mean predeployment HbA1c of 6.8%. Twenty percent deployed with an HbA1c between 7.0 and 7.9%, 7.2% deployed with an HbA1c between 8.0 and 8.9%, and 5.7% deployed with an HbA1c of 9.0% or higher. In the overall population and within each military service, there was no significant change in HbA1c before and after deployment. However, those with predeployment HbA1c \u3c 7.0% experienced a rise in HbA1c from 6.2 to 6.5% (P \u3c 0.001), whereas those with predeployment HbA1c values ≥7.0% experienced a decline from 8.0 to 7.5% (P \u3c 0.001). Those who deployed between 91 and 135 days had a decline in HbA1c from 7.1 to 6.7% (P = 0.010), but no significant changes were demonstrated in those with longer deployment durations. BMI declined from 29.6 to 29.3 kg/m2 (P \u3c 0.001), with other significant changes seen among those in the Army, Navy, and deployment durations up to 315 days.
CONCLUSIONS: Most SMs had an HbA1c \u3c 7.0%, suggesting that military providers appropriately selected well-managed SMs for deployment. HbA1c did not seem to deteriorate during deployment, but they also did not improve despite a reduction in BMI. Concerning trends included the deployment of some SMs with much higher HbA1c, utilization of medications with adverse safety profiles, and the lack of HbA1c and BMI evaluation proximal to deployment departures and returns. However, for SMs meeting adequate glycemic targets, we demonstrated that HbA1c remained stable, supporting the notion that some SMs may safely deploy with diabetes. Improvement in BMI may compensate for factors promoting hyperglycemia in a deployed setting, such as changes in diet and medication availability. Future research should analyze in a prospective fashion, where a more complete array of diabetes and readiness-related measures to comprehensively evaluate the safety of deploying SMs with diabetes
Rapid radiocarbon (14C) analysis of coral and carbonate samples using a continuous-flow accelerator mass spectrometry (CFAMS) system
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 26 (2011): PA4212, doi:10.1029/2011PA002174.Radiocarbon analyses of carbonate materials provide critical information for understanding the last glacial cycle, recent climate history and paleoceanography. Methods that reduce the time and cost of radiocarbon (14C) analysis are highly desirable for large sample sets and reconnaissance type studies. We have developed a method for rapid radiocarbon analysis of carbonates using a novel continuous-flow accelerator mass spectrometry (CFAMS) system. We analyzed a suite of deep-sea coral samples and compared the results with those obtained using a conventional AMS system. Measurement uncertainty is <0.02 Fm or 160 Ryr for a modern sample and the mean background was 37,800 Ryr. Radiocarbon values were repeatable and in good agreement with those from the conventional AMS system. Sample handling and preparation is relatively simple and the method offered a significant increase in speed and cost effectiveness. We applied the method to coral samples from the Eastern Pacific Ocean to obtain an age distribution and identify samples for further analysis. This paper is intended to update the paleoceanographic community on the status of this new method and demonstrate its feasibility as a choice for rapid and affordable radiocarbon analysis.This work was performed under NSF
Cooperative Agreement OCE‐0753487, and also NSF‐OPP awards 0636787
and 0944474
A high-performance 14C accelerator mass spectrometry system
Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2010. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 52 (2010): 228-235.A new and unique radiocarbon accelerator mass spectrometry (AMS) facility has been constructed at the
Woods Hole Oceanographic Institution. The defining characteristic of the new system is its large-gap optical elements that
provide a larger-than-standard beam acceptance. Such a system is ideally suited for high-throughput, high-precision measurements
of 14C. Details and performance of the new system are presented
Science Extraction from TESS Observations of Known Exoplanet Hosts
The transit method of exoplanet discovery and characterization has enabled
numerous breakthroughs in exoplanetary science. These include measurements of
planetary radii, mass-radius relationships, stellar obliquities, bulk density
constraints on interior models, and transmission spectroscopy as a means to
study planetary atmospheres. The Transiting Exoplanet Survey Satellite (TESS)
has added to the exoplanet inventory by observing a significant fraction of the
celestial sphere, including many stars already known to host exoplanets. Here
we describe the science extraction from TESS observations of known exoplanet
hosts during the primary mission. These include transit detection of known
exoplanets, discovery of additional exoplanets, detection of phase signatures
and secondary eclipses, transit ephemeris refinement, and asteroseismology as a
means to improve stellar and planetary parameters. We provide the statistics of
TESS known host observations during Cycle 1 & 2, and present several examples
of TESS photometry for known host stars observed with a long baseline. We
outline the major discoveries from observations of known hosts during the
primary mission. Finally, we describe the case for further observations of
known exoplanet hosts during the TESS extended mission and the expected science
yield.Comment: 12 pages, 7 figures, accepted for publication in PAS
Validation of Kepler's Multiple Planet Candidates. III: Light Curve Analysis & Announcement of Hundreds of New Multi-planet Systems
The Kepler mission has discovered over 2500 exoplanet candidates in the first
two years of spacecraft data, with approximately 40% of them in candidate
multi-planet systems. The high rate of multiplicity combined with the low rate
of identified false-positives indicates that the multiplanet systems contain
very few false-positive signals due to other systems not gravitationally bound
to the target star (Lissauer, J. J., et al., 2012, ApJ 750, 131). False
positives in the multi- planet systems are identified and removed, leaving
behind a residual population of candidate multi-planet transiting systems
expected to have a false-positive rate less than 1%. We present a sample of 340
planetary systems that contain 851 planets that are validated to substantially
better than the 99% confidence level; the vast majority of these have not been
previously verified as planets. We expect ~2 unidentified false-positives
making our sample of planet very reliable. We present fundamental planetary
properties of our sample based on a comprehensive analysis of Kepler light
curves and ground-based spectroscopy and high-resolution imaging. Since we do
not require spectroscopy or high-resolution imaging for validation, some of our
derived parameters for a planetary system may be systematically incorrect due
to dilution from light due to additional stars in the photometric aperture.
None the less, our result nearly doubles the number of verified exoplanets.Comment: 138 pages, 8 Figures, 5 Tables. Accepted for publications in the
Astrophysical Journa
TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
Data from the newly-commissioned \textit{Transiting Exoplanet Survey
Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf
located 15 pc away. The planet has a radius of and
orbits the star every 11 hours. Although the existence of an atmosphere around
such a strongly irradiated planet is questionable, the star is bright enough
(, ) for this possibility to be investigated with transit and
occultation spectroscopy. The star's brightness and the planet's short period
will also facilitate the measurement of the planet's mass through Doppler
spectroscopy.Comment: 10 pages, 4 figures. Submitted to ApJ Letters. This letter makes use
of the TESS Alert data, which is currently in a beta test phase, using data
from the pipelines at the TESS Science Office and at the TESS Science
Processing Operations Cente
Planetary Candidates Observed by Kepler IV: Planet Sample From Q1-Q8 (22 Months)
We provide updates to the Kepler planet candidate sample based upon nearly
two years of high-precision photometry (i.e., Q1-Q8). From an initial list of
nearly 13,400 Threshold Crossing Events (TCEs), 480 new host stars are
identified from their flux time series as consistent with hosting transiting
planets. Potential transit signals are subjected to further analysis using the
pixel-level data, which allows background eclipsing binaries to be identified
through small image position shifts during transit. We also re-evaluate Kepler
Objects of Interest (KOI) 1-1609, which were identified early in the mission,
using substantially more data to test for background false positives and to
find additional multiple systems. Combining the new and previous KOI samples,
we provide updated parameters for 2,738 Kepler planet candidates distributed
across 2,017 host stars. From the combined Kepler planet candidates, 472 are
new from the Q1-Q8 data examined in this study. The new Kepler planet
candidates represent ~40% of the sample with Rp~1 Rearth and represent ~40% of
the low equilibrium temperature (Teq<300 K) sample. We review the known biases
in the current sample of Kepler planet candidates relevant to evaluating planet
population statistics with the current Kepler planet candidate sample.Comment: 12 pages, 8 figures, Accepted ApJ Supplemen
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