454 research outputs found
Optical Activity From Extra Dimension
Optical activity, like Faraday effect, is a rotation of the plane of
polarization of propagating light in a medium and can be attributed to
different sources with distinct signatures. In this note we discuss the effect
of optical activity {\it{in vacuum}} due to Kaluza-Klein scalar field ,
in the presence of an external electro-magnetic field. The astrophysical
implication of this effect is indicated. We also point out the possibility of
observing the same in laboratory conditions.Comment: Four Page
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The scope of the Weatherization Assistance Program: Profile of the population in need
The U.S. Department of Energy (DOE) is conducting a national evaluation of its Weatherization Assistance Program, an energy efficiency program that provides financial assistance to qualifying low-income households for the {open_quotes}weatherization{close_quotes} of their housing units. The evaluation, being conducted for the Department by Oak Ridge National Laboratory (ORNL), is comprised of five studies. One of the five is a two-part analysis of the scope of the Weatherization Assistance Program and other resources devoted to low-income energy efficiency, including the number of dwellings weatherized to date and the population remaining to be served. This study is referred to here as the {open_quotes}Scope{close_quotes} study. This report presents the results of the second part of the {open_quotes}Scope{close_quotes} study, which investigates the characteristics of the population eligible for and in need of the DOE Weatherization Assistance Program - The Profile of the Population in Need. The {open_quotes}Profile{close_quotes} study is an attempt to use the Energy Information Administration`s Residential Energy Consumption Survey (RECS) for 1990 to define the weatherization-related characteristics of the low-income population. The RECS, a national survey with a sample size of 5,095 households, is the most reliable source for information regarding residential energy-use and housing characteristics because data is collected from fuel vendors on actual household energy bills and consumption for a large and representative sample of households
Minimal Noncanonical Cosmologies
We demonstrate how much it is possible to deviate from the standard
cosmological paradigm of inflation-assisted LambdaCDM, keeping within current
observational constraints, and without adding to or modifying any theoretical
assumptions. We show that within a minimal framework there are many new
possibilities, some of them wildly different from the standard picture. We
present three illustrative examples of new models, described phenomenologically
by a noncanonical scalar field coupled to radiation and matter. These models
have interesting implications for inflation, quintessence, reheating,
electroweak baryogenesis, and the relic densities of WIMPs and other exotics.Comment: 20 pages, 5 figures, 3 table
Abundance analysis, spectral variability, and search for the presence of a magnetic field in the typical PGa star HD 19400
The aim of this study is to carry out an abundance determination, to search for spectral variability and for the presence of a weak magnetic field in the typical PGa star HD 19400. High-resolution, high signal-to-noise High Accuracy Radial-velocity Planet Searcher (HARPS) spectropolarimetric observations of HD 19400 were obtained at three different epochs in 2011 and 2013. For the first time, we present abundances of various elements determined using an ATLAS12 model, including the abundances of a number of elements not analysed by previous studies, such as Ne I, Ga II, and Xe II. Several lines of As II are also present in the spectra of HD 19400. To study the variability, we compared the behaviour of the line profiles of various elements. We report on the first detection of anomalous shapes of line profiles belonging to Mn and Hg, and the variability of the line profiles belonging to the elements Hg, P, Mn, Fe, and Ga. We suggest that the variability of the line profiles of these elements is caused by their non-uniform surface distribution, similar to the presence of chemical spots detected in HgMn stars. The search for the presence of a magnetic field was carried out using the moment technique and the Singular Value Decomposition (SVD) method. Our measurements of the magnetic field with the moment technique using 22 Mn II lines indicate the potential existence of a weak variable longitudinal magnetic field on the first epoch. The SVD method applied to the Mn II lines indicates <Bz> = -76 ± 25 G on the first epoch, and at the same epoch the SVD analysis of the observations using the Fe II lines shows <Bz> = -91 ± 35 G. The calculated false alarm probability values, 0.008 and 0.003, respectively, are above the value 10-3, indicating no detection.</p
Nitrate stable isotopes and major ions in snow and ice samples from four Svalbard sites
Increasing reactive nitrogen (N-r) deposition in the Arctic may adversely impact N-limited ecosystems. To investigate atmospheric transport of N-r to Svalbard, Norwegian Arctic, snow and firn samples were collected from glaciers and analysed to define spatial and temporal variations (1 10 years) in major ion concentrations and the stable isotope composition (delta N-15 and delta O-18) of nitrate (NO3-) across the archipelago. The delta N-15(NO3-) and delta O-18(NO3-) averaged -4 parts per thousand and 67 parts per thousand in seasonal snow (2010-11) and -9 parts per thousand and 74 parts per thousand in firn accumulated over the decade 2001-2011. East-west zonal gradients were observed across the archipelago for some major ions (non-sea salt sulphate and magnesium) and also for delta N-15(NO3-) and delta O-18(NO3-) in snow, which suggests a different origin for air masses arriving in different sectors of Svalbard. We propose that snowfall associated with long-distance air mass transport over the Arctic Ocean inherits relatively low delta N-15(NO3-) due to in-transport N isotope fractionation. In contrast, faster air mass transport from the north-west Atlantic or northern Europe results in snowfall with higher delta N-15(NO3-) because in-transport fractionation of N is then time-limited
Regulation of 5-HT Receptors and the Hypothalamic-Pituitary-Adrenal Axis
Disturbances in the serotonin (5-HT) system is the neurobiological abnormality most consistently associated with suicide. Hyperactivity of the hypothalmic-pituitary-adrenal (HPA) axis is also described in suicide victims. The HPA axis is the classical neuroendocrine system that responds to stress and whose final product, corticosteroids, targets components of the limbic system, particularly the hippocampus. We will review resulsts from animal studies that point to the possibility that many of the 5-HT receptor changes observed in suicide brains may be a result of, or may be worsened by, the HPA overactivity that may be present in some suicide victims. The results of these studies can be summarized as follows: (1) chronic unpredictable stress produces high corticosteroid levels in rats; (2) chronic stress also results in changes in specific 5-HT receptors (increases in cortical 5-HT2A and decreases in hipocampal 5-HT1A and 5-HT1B); (3) chronic antidepressant administration prevents many of the 5-HT receptor changes observed after stress; and (4) chronic antidepressant administration reverses the overactivity of the HPA axis. If indeed 5-HT receptors have a partial role in controlling affective states, then their modulation by corticosteroids provides a potential mechanism by which these hormones may regulate mood. These data may also provide a biological understanding of how stressful events may increase the risk for suicide in vulnerable individuals and may help us elucidate the neurobiological underpinnings of treatment resistance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73437/1/j.1749-6632.1997.tb52357.x.pd
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