456 research outputs found
The key parameters controlling the photodesorption yield in interstellar CO ice analogs: Influence of ice deposition temperature and thickness
The overabundance of gas molecules in the coldest regions of space point to a
non-thermal desorption process. Laboratory simulations show an efficient
desorption of CO ice exposed to ultraviolet radiation, known as
photodesorption, which decreases for increasing ice deposition temperature.
However, the understanding of this abnormal phenomenon has remained elusive. In
this work we show the same phenomenon, and in particular, a dramatic drop in
the photodesorption yield is observed when the deposition temperature is 19 K
and higher. Also the minimum ice thickness that accounts for a constant
photodesorption yield of CO ice is deposition temperature dependent, an
observation reported here for the first time. We propose that the key
parameters that dominate the absorbed photon energy transfer in CO ice, and
contribute to the measured photodesorption yields are the energy transfer
length, single ice layer contributed desorption yield, and relative effective
surface area. This set of parameters should be incorporated in astrophysical
models that simulate photodesorption of the top CO-rich ice layer on icy dust
populations with the size distribution which is ice thickness related.Comment: 8 pages, 4 figure
Optical modeling and polarization calibration for CMB measurements with ACTPol and Advanced ACTPol
The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization
sensitive upgrade to the Atacama Cosmology Telescope. Located at an elevation
of 5190 m, ACTPol measures the Cosmic Microwave Background (CMB) temperature
and polarization with arcminute-scale angular resolution. Calibration of the
detector angles is a critical step in producing maps of the CMB polarization.
Polarization angle offsets in the detector calibration can cause leakage in
polarization from E to B modes and induce a spurious signal in the EB and TB
cross correlations, which eliminates our ability to measure potential
cosmological sources of EB and TB signals, such as cosmic birefringence. We
present our optical modeling and measurements associated with calibrating the
detector angles in ACTPol.Comment: 12 pages, 8 figures, conference proceedings submitted to Proceedings
of SPIE; added reference in section 2 and merged repeated referenc
Disparities in registration and use of an online patient portal among older adults: findings from the LitCog cohort
(C) The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved.Financial disclosure: This project was supported by the
National Institute on Aging (R01 AG030611), the National
Center for Research Resources (5UL1RR025741), and the
National Center for Advancing Translational Sciences (Grant
8UL1TR000150). The content is solely the responsibility of the
authors and does not necessarily represent the official views of
the National Institutes of Health. Smith is currently supported
by a Cancer Research UK Fellowship
Results from the Atacama B-mode Search (ABS) Experiment
The Atacama B-mode Search (ABS) is an experiment designed to measure cosmic
microwave background (CMB) polarization at large angular scales (). It
operated from the ACT site at 5190~m elevation in northern Chile at 145 GHz
with a net sensitivity (NEQ) of 41 K. It employed an
ambient-temperature sapphire half-wave plate rotating at 2.55 Hz to modulate
the incident polarization signal and reduce systematic effects. We report here
on the analysis of data from a 2400 deg patch of sky centered at
declination and right ascension . We perform a blind
analysis. After unblinding, we find agreement with the Planck TE and EE
measurements on the same region of sky. We marginally detect polarized dust
emission and give an upper limit on the tensor-to-scalar ratio of (95%
cl) with the equivalent of 100 on-sky days of observation. We also present a
new measurement of the polarization of Tau A and introduce new methods
associated with HWP-based observations.Comment: 38 pages, 11 figure
L-Edge Spectroscopy of Dilute, Radiation-Sensitive Systems Using a Transition-Edge-Sensor Array
We present X-ray absorption spectroscopy and resonant inelastic X-ray
scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous
ferricyanide. These measurements demonstrate the ability of high-throughput
transition-edge-sensor (TES) spectrometers to access the rich soft X-ray
(100-2000eV) spectroscopy regime for dilute and radiation-sensitive samples.
Our low-concentration data are in agreement with high-concentration
measurements recorded by conventional grating-based spectrometers. These
results show that soft X-ray RIXS spectroscopy acquired by high-throughput TES
spectrometers can be used to study the local electronic structure of dilute
metal-centered complexes relevant to biology, chemistry and catalysis. In
particular, TES spectrometers have a unique ability to characterize frozen
solutions of radiation- and temperature-sensitive samples.Comment: 19 pages, 4 figure
Instrumental performance and results from testing of the BLAST-TNG receiver, submillimeter optics, and MKID arrays
Polarized thermal emission from interstellar dust grains can be used to map
magnetic fields in star forming molecular clouds and the diffuse interstellar
medium (ISM). The Balloon-borne Large Aperture Submillimeter Telescope for
Polarimetry (BLASTPol) flew from Antarctica in 2010 and 2012 and produced
degree-scale polarization maps of several nearby molecular clouds with
arcminute resolution. The success of BLASTPol has motivated a next-generation
instrument, BLAST-TNG, which will use more than 3000 linear polarization
sensitive microwave kinetic inductance detectors (MKIDs) combined with a 2.5m
diameter carbon fiber primary mirror to make diffraction-limited observations
at 250, 350, and 500 m. With 16 times the mapping speed of BLASTPol,
sub-arcminute resolution, and a longer flight time, BLAST-TNG will be able to
examine nearby molecular clouds and the diffuse galactic dust polarization
spectrum in unprecedented detail. The 250 m detector array has been
integrated into the new cryogenic receiver, and is undergoing testing to
establish the optical and polarization characteristics of the instrument.
BLAST-TNG will demonstrate the effectiveness of kilo-pixel MKID arrays for
applications in submillimeter astronomy. BLAST-TNG is scheduled to fly from
Antarctica in December 2017 for 28 days and will be the first balloon-borne
telescope to offer a quarter of the flight for "shared risk" observing by the
community.Comment: Presented at SPIE Millimeter, Submillimeter, and Far-Infrared
Detectors and Instrumentation for Astronomy VIII, June 29th, 201
Gender Differences in the Relationships between Perceived Stress, Eating Behaviors, Sleep, Dietary Risk, and Body Mass Index
Background: Obesity is a growing epidemic among university students, and the high levels of stress reported by this population could contribute to this issue. Singular relationships between perceived stress; engagement in restrained, uncontrolled, and emotional eating; sleep; dietary risk; and body mass index (BMI) have been reported in the current body of literature; however, these constructs interact with each other, and the complex relationships among them are infrequently examined. Therefore, the aim of the present study was to explore the complex relationships between these constructs using mediation and moderation analyses stratified by gender. Methods: A cross-sectional study, enrolling university students from the United States (U.S.), the Netherlands, South Korea, Malaysia, Ireland, Ghana, and China, was conducted between October 2020 and January 2021 during the COVID-19 pandemic. Perceived stress; maladaptive eating behaviors including restrained, uncontrolled, and emotional eating; sleep duration and quality; dietary risk; and BMI were assessed using validated questionnaires, which were distributed through an online platform. Results: A total of 1392 students completed the online survey (379 male, 973 female, and 40 who self-identified as “other”). Uncontrolled and emotional eating mediated the relationship between perceived stress and dietary risk for both males and females; higher sleep quality weakened this relationship among female students but not males. Emotional eating mediated the relationship between perceived stress and BMI for both males and females, but higher sleep quality weakened this relationship only among females. Conclusions: Our findings suggest that students in higher education are likely to benefit from interventions to reduce uncontrolled and emotional eating. Programs that improve sleep quality, especially during highly stressful periods, may be helpful
Lactobacillus rhamnosus GG-supplemented formula expands butyrate-producing bacterial strains in food allergic infants.
Dietary intervention with extensively hydrolyzed casein formula supplemented with Lactobacillus rhamnosus GG (EHCF+LGG) accelerates tolerance acquisition in infants with cow's milk allergy (CMA). We examined whether this effect is attributable, at least in part, to an influence on the gut microbiota. Fecal samples from healthy controls (n=20) and from CMA infants (n=19) before and after treatment with EHCF with (n=12) and without (n=7) supplementation with LGG were compared by 16S rRNA-based operational taxonomic unit clustering and oligotyping. Differential feature selection and generalized linear model fitting revealed that the CMA infants have a diverse gut microbial community structure dominated by Lachnospiraceae (20.5±9.7%) and Ruminococcaceae (16.2±9.1%). Blautia, Roseburia and Coprococcus were significantly enriched following treatment with EHCF and LGG, but only one genus, Oscillospira, was significantly different between infants that became tolerant and those that remained allergic. However, most tolerant infants showed a significant increase in fecal butyrate levels, and those taxa that were significantly enriched in these samples, Blautia and Roseburia, exhibited specific strain-level demarcations between tolerant and allergic infants. Our data suggest that EHCF+LGG promotes tolerance in infants with CMA, in part, by influencing the strain-level bacterial community structure of the infant gut
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