28,200 research outputs found

    A study of the temporal changes recorded by ERTS and their geological significance

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    The temporal changes that are recorded by ERTS were evaluated for an area around Bathurst Inlet in the North West Territories. The seasons represented by the images included: early winter, spring, early summer, summer, and fall. Numerous surface characteristics (vegetation, drainage patterns, surface texture, lineament systems and topographic relief, etc.) were used to relate the change in observable features with the different seasons. It was found that the time of year when an observation is made has a strong control over the amount and type of information that can be derived by an experienced interpreter. It was concluded that a detailed study of temporal changes is an important part of any ERTS interpretation for geology

    Upper Bound on the Dark Matter Total Annihilation Cross Section

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    We consider dark matter annihilation into Standard Model particles and show that the least detectable final states, namely neutrinos, define an upper bound on the total cross section. Calculating the cosmic diffuse neutrino signal, and comparing it to the measured terrestrial atmospheric neutrino background, we derive a strong and general bound. This can be evaded if the annihilation products are dominantly new and truly invisible particles. Our bound is much stronger than the unitarity bound at the most interesting masses, shows that dark matter halos cannot be significantly modified by annihilations, and can be improved by a factor of 10--100 with existing neutrino experiments.Comment: 4 pages, 3 figures; version accepted for publication in PR

    Do People Make the Place?: An Examination of the Attraction-Selection-Attrition Hypothesis

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    This study tests the hypotheses that (1) congruence between internal need states and external environments drives the organizational-choice process, and (2) those attracted to particular organizations are more homogeneous than the applicant pool in general. Subjects were evaluated on fourteen needs using the Jackson Personality Research Form. They then viewed two video-taped segments of simulated campus interviews to gain information about two distinct organizational types. The interview segments entered the discussion in-progress to avoid any reference to a particular job which might introduce an occupational confound. Subjects received job offers from both organizations and were asked to indicate which of the two organizations they found more attractive by accepting one of the offers. Analysis of variance results indicated only weak support for the congruency hypothesis. Differences were observed in n Ach between the groups of subjects attracted to each organization. No differences were found for any of the other need strength measures. This suggests that the subjects attracted to the ifferent organizations are substantially similar. Implications for the homogeneity hypothesis are discussed and suggestions for further study of this concept are offered

    On General Off-Shell Representations of Worldline (1D) Supersymmetry

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    Every finite-dimensional unitary representation of the N-extended worldline supersymmetry without central charges may be obtained by a sequence of differential transformations from a direct sum of minimal Adinkras, simple supermultiplets that are identifiable with representations of the Clifford algebra. The data specifying this procedure is a sequence of subspaces of the direct sum of Adinkras, which then opens an avenue for classification of the continuum of so constructed off-shell supermultiplets.Comment: 21 pages, 5 illustrations; references update

    The beginnings of geography teaching and research in the University of Glasgow: the impact of J.W. Gregory

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    J.W. Gregory arrived in Glasgow from Melbourne in 1904 to take up the post of foundation Professor of Geology in the University of Glasgow. Soon after his arrival in Glasgow he began to push for the setting up of teaching in Geography in Glasgow, which came to pass in 1909 with the appointment of a Lecturer in Geography. This lecturer was based in the Department of Geology in the University's East Quad. Gregory's active promotion of Geography in the University was matched by his extensive writing in the area, in textbooks, journal articles and popular books. His prodigious output across a wide range of subject areas is variably accepted today, with much of his geomorphological work being judged as misguided to varying degrees. His 'social science' publications - in the areas of race, migration, colonisation and economic development of Africa and Australia - espouse a viewpoint that is unacceptable in the twenty-first century. Nonetheless, that viewpoint sits squarely within the social and economic traditions of Gregory's era, and he was clearly a key 'Establishment' figure in natural and social sciences research in the first half of the twentieth century. The establishment of Geography in the University of Glasgow remains enduring testimony of J.W. Gregory's energy, dedication and foresight

    The level and duration of RSV-specific maternal IgG in infants in Kilifi Kenya

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    Background Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infection in infants. The rate of decay of RSV-specific maternal antibodies (RSV-matAb), the factors affecting cord blood levels, and the relationship between these levels and protection from infection are poorly defined. Methods A birth cohort (n = 635) in rural Kenya, was studied intensively to monitor infections and describe age-related serological characteristics. RSV specific IgG antibody (Ab) in serum was measured by the enzyme linked immunosorbent assay (ELISA) in cord blood, consecutive samples taken 3 monthly, and in paired acute and convalescent samples. A linear regression model was used to calculate the rate of RSV-matAb decline. The effect of risk factors on cord blood titres was investigated. Results The half-life of matAb in the Kenyan cohort was calculated to be 79 days (95% confidence limits (CL): 76–81 days). Ninety seven percent of infants were born with RSV-matAb. Infants who subsequently experienced an infection in early life had significantly lower cord titres of anti-RSV Ab in comparison to infants who did not have any incident infection in the first 6 months (P = 0.011). RSV infections were shown to have no effect on the rate of decay of RSV-matAb. Conclusion Maternal-specific RSV Ab decline rapidly following birth. However, we provide evidence of protection against severe disease by RSV-matAb during the first 6–7 months. This suggests that boosting maternal-specific Ab by RSV vaccination may be a useful strategy to consider

    MACHOs, White Dwarfs, and the Age of the Universe

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    (Abridged Abstract) A favored interpretation of recent microlensing measurements towards the Large Magellanic Cloud implies that a large fraction (i.e. 10--50%) of the mass of the galactic halo is composed of white dwarfs. We compare model white dwarf luminosity functions to the data from the observational surveys in order to determine a lower bound on the age of any substantial white dwarf halo population (and hence possibly on the age of the Universe). We compare various theoretical white dwarf luminosity functions, in which we vary hese three parameters, with the abovementioned survey results. From this comparison, we conclude that if white dwarfs do indeed constitute more than 10% of the local halo mass density, then the Universe must be at least 10 Gyr old for our most extreme allowed values of the parameters. When we use cooling curves that account for chemical fractionation and more likely values of the IMF and the bolometric correction, we find tighter limits: a white dwarf MACHO fraction of 10% (30%) requires a minimum age of 14 Gyr (15.5 Gyr). Our analysis also indicates that the halo white dwarfs almost certainly have helium-dominated atmospheres.Comment: Final version accepted for publication, straight TeX formate, 6 figs, 22 page

    Interventions to Improve Adolescent Vaccination What May Work and What Still Needs to Be Tested

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    This article is being published concurrently in the American Journal of Preventive Medicine and Vaccine. The articles are identical except for stylistic changes in keeping with each journalʼs style. Either of these versions may be used in citing this article. See: Dempsey, A. F., & Zimet, G. D. (2015). Interventions to Improve Adolescent Vaccination: What May Work and What Still Needs to Be Tested. Vaccine, 33, Supplement 4, D106–D113. http://doi.org/10.1016/j.vaccine.2015.09.032Since the development of the “adolescent platform” of vaccination in 1997, hundreds of studies have been conducted, identifying barriers to and facilitators of adolescent vaccination. More recent research has focused on developing and evaluating interventions to increase uptake of adolescent vaccines. This review describes a selection of recent intervention studies for increasing adolescent vaccination, divided into three categories: those with promising results that may warrant more widespread implementation, those with mixed results requiring more research, and those with proven effectiveness in other domains that have not yet been tested with regard to adolescent vaccination
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