75 research outputs found
Scientific optimization of a ground-based CMB polarization experiment
We investigate the science goals achievable with the upcoming generation of
ground-based Cosmic Microwave Background polarization experiments and calculate
the optimal sky coverage for such an experiment including the effects of
foregrounds. We find that with current technology an E-mode measurement will be
sample-limited, while a B-mode measurement will be detector-noise-limited. We
conclude that a 300 sq deg survey is an optimal compromise for a two-year
experiment to measure both E and B-modes, and that ground-based polarization
experiments can make an important contribution to B-mode surveys. Focusing on
one particular experiment, QUaD, a proposed bolometric polarimeter operating
from the South Pole, we find that a ground-based experiment can make a high
significance measurement of the acoustic peaks in the E-mode spectrum, and will
be able to detect the gravitational lensing signal in the B-mode spectrum. Such
an experiment could also directly detect the gravitational wave component of
the B-mode spectrum if the amplitude of the signal is close to current upper
limits. We also investigate how a ground-based experiment can improve
constraints on the cosmological parameters. We estimate that by combining two
years of QUaD data with the four-year WMAP data, an optimized ground-based
polarization experiment can improve constraints on cosmological parameters by a
factor of two. If the foreground contamination can be reduced, the measurement
of the tensor-to-scalar ratio can be improved by up to a factor of six over
that obtainable from WMAP alone.Comment: 17 pages, 11 figures replaced with version accepted by MNRA
QUaD: A High-Resolution Cosmic Microwave Background Polarimeter
We describe the QUaD experiment, a millimeter-wavelength polarimeter designed
to observe the Cosmic Microwave Background (CMB) from a site at the South Pole.
The experiment comprises a 2.64 m Cassegrain telescope equipped with a
cryogenically cooled receiver containing an array of 62 polarization-sensitive
bolometers. The focal plane contains pixels at two different frequency bands,
100 GHz and 150 GHz, with angular resolutions of 5 arcmin and 3.5 arcmin,
respectively. The high angular resolution allows observation of CMB temperature
and polarization anisotropies over a wide range of scales. The instrument
commenced operation in early 2005 and collected science data during three
successive Austral winter seasons of observation.Comment: 23 pages, author list and text updated to reflect published versio
Obesity Prevalence and Dietary Factors Among Preschool-Aged Head Start Children in Remote Alaska Native Communities: Baseline Data from the ‘‘Got Neqpiaq?’’ Study
Background: American Indian and Alaska Native preschool-aged children experience a high prevalence of obesity, yet are underrepresented in obesity prevention research. This study examined obesity prevalence and dietary risk factors among Alaska Native
preschool-aged children in southwest Alaska.
Methods: The study used baseline data from ‘‘Got Neqpiaq?’’ a culturally centered multilevel intervention focused on Yup’ik
Alaska Native children, aged 3–5 years, enrolled in Head Start in 12 communities in southwest Alaska (n = 155). The primary
outcomes were BMI percentile, overweight, and obesity. Dietary factors of interest were measured using biomarkers: traditional food
intake (nitrogen stable isotope ratio biomarker), ultraprocessed food intake (carbon stable isotope ratio biomarker), and vegetable
and fruit intake (skin carotenoid status biomarker measured by the Veggie Meter). Cardiometabolic markers (glycated hemoglobin
[HbA1c] and blood cholesterol) were also measured.
Results: Among the Yup’ik preschool-aged children in the study, the median BMI percentile was 91, and the prevalence of
overweight or obesity was 70%. The traditional food intake biomarker was negatively associated with BMI, whereas the ultraprocessed foods and vegetable and fruit biomarkers were not associated with BMI. HbA1c and blood cholesterol were within healthy
levels.
Conclusions: The burden of overweight and obesity is high among Yup’ik preschool-aged children. Traditional food intake is
inversely associated with BMI, which underscores the need for culturally grounded interventions that emphasize traditional values
and knowledge to support the traditional food systems in Alaska Native communities in southwest Alaska. Registered with ClinicalTrials.gov #NCT03601299.Ye
‘The First Major Step in the Peace Process’? Exploring the Impact of the Anglo-Irish Agreement on Irish Republican Thinking
Polarization Calibration of the QUaD Experiment
We describe the polarization calibration of the QUaD experiment, including determination of the polarization efficiency of the detectors and their orientation angles. QUaD is a millimeter-wavelength polarimeter that observed the Cosmic Microwave Background (CMB) from a site at the South Pole. The experiment comprises a 2.64 m Cassegrain telescope equipped with a cryogenically cooled receiver containing an array of 62 polarization-sensitive bolometers. The focal plane contains pixels at two different frequency bands, 100 GHz and 150 GHz, with angular resolutions of 5prime and 3farcm5, respectively. The high angular resolution allows observation of CMB temperature and polarization anisotropies over a wide range of scales. The instrument commenced operation in early 2005 and collected science data during three successive Austral winter seasons of observation
Rat neonates renal function after beta-receptors and adrenoceptors blockade during pregnancy
Crash patterns in two Chinese secondary cities, with comparisons to crash patterns in the United States
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