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

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