483 research outputs found
How we eat what we eat: identifying meal routines and practices most strongly associated with healthy and unhealthy dietary factors among young adults
Abstract Objective (i) To examine associations between young adults’ meal routines and practices (e.g. food preparation, meal skipping, eating on the run) and key dietary indicators (fruit/vegetable, fast-food and sugar-sweetened beverage intakes) and (ii) to develop indices of protective and risky meal practices most strongly associated with diet. Design Cross-sectional survey. Setting Minneapolis/St. Paul metropolitan area, Minnesota (USA). Subjects A diverse sample of community college and public university students ( n 1013). Results Meal routines and practices most strongly associated with healthy dietary patterns were related to home food preparation (i.e. preparing meals at home, preparing meals with vegetables) and meal regularity (i.e. routine consumption of evening meals and breakfast). In contrast, factors most strongly associated with poor dietary patterns included eating on the run, using media while eating and purchasing foods/beverages on campus. A Protective Factors Index, summing selected protective meal routines and practices, was positively associated with fruit/vegetable consumption and negatively associated with fast-food and sugar-sweetened beverage consumption ( P <0·001). A Risky Factors Index yielded significant, positive associations with fast-food and sugar-sweetened beverage consumption ( P <0·001). The probability test for the association between the Risky Factors Index and fruit/vegetable intake was P= 0·05. Conclusions Meal routines and practices were significantly associated with young adults’ dietary patterns, suggesting that ways in which individuals structure mealtimes and contextual characteristics of eating likely influence food choice. Thus, in addition to considering specific food choices, it also may be important to consider the context of mealtimes in developing dietary messaging and guidelines
Ferromagnetic semiconductors
The current status and prospects of research on ferromagnetism in
semiconductors are reviewed. The question of the origin of ferromagnetism in
europium chalcogenides, chromium spinels and, particularly, in diluted magnetic
semiconductors is addressed. The nature of electronic states derived from 3d of
magnetic impurities is discussed in some details. Results of a quantitative
comparison between experimental and theoretical results, notably for Mn-based
III-V and II-VI compounds, are presented. This comparison demonstrates that the
current theory of the exchange interactions mediated by holes in the valence
band describes correctly the values of Curie temperatures T_C magnetic
anisotropy, domain structure, and magnetic circular dichroism. On this basis,
chemical trends are examined and show to lead to the prediction of
semiconductor systems with T_C that may exceed room temperature, an expectation
that are being confirmed by recent findings. Results for materials containing
magnetic ions other than Mn are also presented emphasizing that the double
exchange involving hoping through d states may operate in those systems.Comment: 18 pages, 8 figures; special issue of Semicon. Sci. Technol. on
semiconductor spintronic
A Measurement of the Correlation of Galaxy Surveys with CMB Lensing Convergence Maps from the South Pole Telescope
We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, WISE, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 deg^2 of sky, we detect a correlation between the SPT convergence maps and each of the galaxy density maps at >4σ, with zero correlation robustly ruled out in all cases. The amplitude and shape of the cross-power spectra are in good agreement with theoretical expectations and the measured galaxy bias is consistent with previous work. The detections reported here utilize a small fraction of the full 2500 deg^2 SPT survey data and serve as both a proof of principle of the technique and an illustration of the potential of this emerging cosmological probe
Measurements of Sub-degree B-mode Polarization in the Cosmic Microwave Background from 100 Square Degrees of SPTpol Data
We present a measurement of the -mode polarization power spectrum (the
spectrum) from 100 of sky observed with SPTpol, a
polarization-sensitive receiver currently installed on the South Pole
Telescope. The observations used in this work were taken during 2012 and early
2013 and include data in spectral bands centered at 95 and 150 GHz. We report
the spectrum in five bins in multipole space, spanning the range , and for three spectral combinations: 95 GHz 95 GHz, 95
GHz 150 GHz, and 150 GHz 150 GHz. We subtract small ( in units of statistical uncertainty) biases from these spectra and
account for the uncertainty in those biases. The resulting power spectra are
inconsistent with zero power but consistent with predictions for the
spectrum arising from the gravitational lensing of -mode polarization. If we
assume no other source of power besides lensed modes, we determine a
preference for lensed modes of . After marginalizing over
tensor power and foregrounds, namely polarized emission from galactic dust and
extragalactic sources, this significance is . Fitting for a single
parameter, , that multiplies the predicted lensed -mode
spectrum, and marginalizing over tensor power and foregrounds, we find
, indicating that our measured spectra are
consistent with the signal expected from gravitational lensing. The data
presented here provide the best measurement to date of the -mode power
spectrum on these angular scales.Comment: 21 pages, 4 figure
A Measurement of the Cosmic Microwave Background Gravitational Lensing Potential from 100 Square Degrees of SPTpol Data
We present a measurement of the cosmic microwave background (CMB)
gravitational lensing potential using data from the first two seasons of
observations with SPTpol, the polarization-sensitive receiver currently
installed on the South Pole Telescope (SPT). The observations used in this work
cover 100 deg of sky with arcminute resolution at 150 GHz. Using a
quadratic estimator, we make maps of the CMB lensing potential from
combinations of CMB temperature and polarization maps. We combine these lensing
potential maps to form a minimum-variance (MV) map. The lensing potential is
measured with a signal-to-noise ratio of greater than one for angular
multipoles between . This is the highest signal-to-noise mass map
made from the CMB to date and will be powerful in cross-correlation with other
tracers of large-scale structure. We calculate the power spectrum of the
lensing potential for each estimator, and we report the value of the MV power
spectrum between as our primary result. We constrain the ratio
of the spectrum to a fiducial CDM model to be . Restricting ourselves to
polarized data only, we find . This measurement rejects the hypothesis of no lensing at
using polarization data alone, and at using both
temperature and polarization data.Comment: 16 pages, 8 figure
Design and Bolometer Characterization of the SPT-3G First-year Focal Plane
During the austral summer of 2016-17, the third-generation camera, SPT-3G,
was installed on the South Pole Telescope, increasing the detector count in the
focal plane by an order of magnitude relative to the previous generation.
Designed to map the polarization of the cosmic microwave background, SPT-3G
contains ten 6-in-hexagonal modules of detectors, each with 269 trichroic and
dual-polarization pixels, read out using 68x frequency-domain multiplexing.
Here we discuss design, assembly, and layout of the modules, as well as early
performance characterization of the first-year array, including yield and
detector properties.Comment: Conference proceeding for Low Temperature Detectors 2017. Accepted
for publication: 27 August 201
Detection of B-mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope
Gravitational lensing of the cosmic microwave background generates a curl
pattern in the observed polarization. This "B-mode" signal provides a measure
of the projected mass distribution over the entire observable Universe and also
acts as a contaminant for the measurement of primordial gravity-wave signals.
In this Letter we present the first detection of gravitational lensing B modes,
using first-season data from the polarization-sensitive receiver on the South
Pole Telescope (SPTpol). We construct a template for the lensing B-mode signal
by combining E-mode polarization measured by SPTpol with estimates of the
lensing potential from a Herschel-SPIRE map of the cosmic infrared background.
We compare this template to the B modes measured directly by SPTpol, finding a
non-zero correlation at 7.7 sigma significance. The correlation has an
amplitude and scale-dependence consistent with theoretical expectations, is
robust with respect to analysis choices, and constitutes the first measurement
of a powerful cosmological observable.Comment: Two additional null tests, matches version published in PR
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