2,761 research outputs found
A dark matter solution from the supersymmetric axion model
We study the effect of the late decaying saxino (the scalar superpartner of
the axion) and find out that there is a possible dark matter solution from a
class of supersymmetric extensions of the invisible axion model. In this class
of models, the saxino which decays into two axions acts as the late decaying
particle which reconciles the cold dark matter model with high values of the
Hubble constant. Recent observations of the Hubble constant are converging to
, which would be
inconsistent with the standard mixed dark matter model. This class of models
provides a plausible framework for the alternative cold dark matter plus late
decaying particle model, with the interesting possibility that both cold dark
matter and the extra radiation consist of axion.Comment: 11 pages, no figure, REVTEX 3.
Natural Dye For Dye Sensitized Solar Cells (DSSCs) Using Mangosteen Pericarp And Adenium Obesum Flower
Dye sensitized solar cells is now a significant research in the last two decades due to its fundamental solution in the energy conversion at lowest cost. Besides that, the ease of fabrication, flexibility and widely available materials have made the dye sensitized solar cell a promising technology towards future innovation in low cost solar cell. Although the novel organic synthetic dyes provide a high efficiency and durability compared to natural dye, there are several limitations such as high cost and complexity of synthesis and toxicity of materials. These setbacks had opened up for further research of utilizing the natural sensitizers which is environmental friendly and ease in preparation. The main objective of this research is to determine the optimum condition of types of solvent, extraction temperature and pH value for extraction in improving the efficiency of natural dye using mangosteen pericarp and adenium obesum flower. The mangosteen pericarp extracted with acetone solvent shows the highest light absorption intensity and power conversion efficiency value. The optimum pH condition for the mangosteen pericarp extract is at pH 1.93 with the highest efficiency. For the adenium obesum extract, the optimum temperature for the extraction is at 40ºC and the adenium obesum extracted at pH 4.01 shows a high efficiency. The mixture of mangosteen pericarp-adenium obesum shows significantly the highest light absorption intensity and photoelectrochemical values compared to its pure extracts. The optimum pH for the mixture extract is at pH value of 2.93
Community participation among people who are homeless
Thesis (Sc.D.)--Boston UniversityCommunity participation has been regarded as a goal for people with rehabilitation needs, but there is a lack of consensus about the definition and measurement of community participation. In addition, there is limited knowledge about the community participation of individuals who are homeless. This dissertation contains three studies aimed at furthering our understanding about community participation among individuals who are, or were previously, homeless. Study 1 systematically reviewed instruments that measure community participation in people with disabilities and compared these instruments by analyzing the content based on the International Classification of Functioning, Disability and Health Perspective (ICF) classification. Seventeen instruments were identified as containing community participation items. None of these instruments covered the full breadth of community participation domains, but each addressed community participation to some extent. Furthermore, most of the instruments lose precision by treating diverse activities as a single concept. [TRUNCATED]2018-09-0
Two-body hadronic decays of Xi^{0}_c in light front approach
In this study, we investigate the nonleptonic decays of the charmed-baryon
Xi^ {0} _ c induced by the c -> u(d\bar{d})/(s\bar{s}) transition. Utilizing
the factorization assumption, we decompose the decay amplitudes in terms of
transition form factors which are then calculated within the light-front quark
model. We employ helicity amplitudes to analyze the nonleptonic decay modes of
the charmed-baryon Xi^ {0} _c and derive benchmark results for decay widths and
branching fractions. Our calculations suggest that the branching fractions for
some of these rare nonleptonic decays are at the order of 10^ {-4} - 10^ {-3},
which are likely to be detectable at experiments such as LHCb or BESIII. The
potential data accumulated in the future may help to further our understanding
of the decay mechanism in the presence of charm quarks.Comment: 10 pages,4 figure
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