8,249 research outputs found
Background cosmological dynamics in gravity and observational constraints
In this paper, we carry out a study of viable cosmological models in
-gravity at the background level. We use observable parameters like
and to form autonomous system of equations and show that the
models under consideration exhibit two different regimes in their time
evolution, namely, a phantom phase followed by a quintessence like behavior. We
employ statefinder parameters to emphasize a characteristic discriminative
signature of these models.Comment: 6 pages, Latex style, 9 eps figures, replaced versions with new
references added, Submitted to Phys.Rev.
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Placement of Outdoor Exercise Equipment and Physical Activity: A Quasi-Experimental Study in Two Parks in Southern California.
To reduce the burden of chronic disease, the Centers for Disease Control and Prevention (CDC) funded the Orange County Partnerships to Improve Health (OC-PICH) project in Orange County, California. One of the strategies included adding outdoor exercise equipment (OEE) in two parks in Garden Grove and Anaheim. Using a quasi-experimental pre-post design, we evaluated park users' physical activity levels before and after OEE installation using the System for Observing Play and Recreation in Communities (SOPARC). The OEE was installed along a walking path in Edison Park (Anaheim) and grouped within a single area (a "fitness zone") in Garden Grove Park. In both parks, there were significantly greater odds of high-intensity physical activity overall after the installation-19% higher odds in Anaheim, and 23% higher odds in Garden Grove. However, the fitness zone area in Garden Grove had substantially higher odds of increased physical activity post-intervention (OR = 5.29, CI: 3.76-7.44, p < 0.001). While the increases in physical activity levels are consistent with past studies that link OEE to higher levels of physical activity among park users, our findings also suggest that the location and placement of equipment within a park may be an important factor to consider when improving park amenities for physical activity
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Lessons Learned and Next Steps in Energy Efficiency Measurement and Attribution: Energy Savings, Net to Gross, Non-Energy Benefits, and Persistence of Energy Efficiency Behavior
This white paper examines four topics addressing evaluation, measurement, and attribution of direct and indirect effects to energy efficiency and behavioral programs: Estimates of program savings (gross); Net savings derivation through free ridership / net to gross analyses; Indirect non-energy benefits / impacts (e.g., comfort, convenience, emissions, jobs); and, Persistence of savings
ALMA detection of dark chromospheric holes in the quiet Sun
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations
of a quiet-Sun region at a wavelength of 3 mm, obtained during the first solar
ALMA cycle on April 27, 2017, and compare them with available chromospheric
observations in the UV and visible as well as with photospheric magnetograms.
ALMA images clearly reveal the presence of distinct particularly dark/cool
areas in the millimeter maps having temperatures as low as 60% of the normal
quiet Sun at 3 mm, which are not seen in the other data. We speculate that ALMA
is sensing cool chromospheric gas, whose presence had earlier been inferred
from infrared CO spectra.Comment: 9 pages, 3 figures, accepted for publication in ApJ
The relationship between chromospheric emissions and magnetic field strength
Aims. We analyze observational data from 4 instruments to study the
correlations between chromospheric emission, spanning the heights from the
temperature minimum region to the middle chromosphere, and photospheric
magnetic field. Methods: The data consist of radio images at 3.5 mm from the
Berkeley-Illinois-Maryland Array (BIMA), UV images at 1600 A from TRACE, Ca II
K-line filtergrams from BBSO, and MDI/SOHO longitudinal photospheric
magnetograms. For the first time interferometric millimeter data with the
highest currently available resolution are included in such an analysis. We
determine various parameters of the intensity maps and correlate the
intensities with each other and with the magnetic field. Results: The
chromospheric diagnostics studied here show a pronounced similarity in their
brightness structures and map out the underlying photospheric magnetic field
relatively well. We find a power law to be a good representation of the
relationship between photospheric magnetic field and emission from
chromospheric diagnostics at all wavelengths. The dependence of chromospheric
brightness on magnetic field is found to be different for network and
internetwork regions.Comment: 13 pages, 14 figures, 3 table
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