1,924 research outputs found

    Detection of alteration associated with a porphyry copper deposit in southern Arizona

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    Computer processing of Landsat MSS data was performed using contrast stretching and band-to-band ratioing. A false color ratio composite picture showed color anomalies which coincided with known areas of alteration on and about Red Mountain. A helicopter survey of the study area was undertaken using a portable field reflectance spectrometer. One hundred fifty-six spectra were obtained in the 0.4 to 2.5 micrometer wavelength region. The spectra were digitized, and contour maps for 24 wavelength intervals were produced; no spectral anomalies were evident for the known altered areas. A contour map produced from the 1.6 and 2.2 micrometer ratio generally delineated the alteration areas. The 1.3, 1.6, and 2.2 micrometer wavelength data were canonically transformed using a transformation empirically derived from discriminant function analysis of altered and unaltered materials for the Goldfield, Nevada region, and a contour map was produced for the first canonical variable. The known areas of alteration were clearly defined on the contour map

    Central European foreign exchange markets: a cross-spectral analysis of the 2007 financial crisis

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    This paper investigates co-movements between currency markets of Czech Republic, Poland, Hungary, Slovakia and the Euro in the year following the drying up of money markets in August 2007. The paper shows that assessing the degree of foreign currency co-movement by correlation can lead to concluding, erroneously, that financial contagion has not occurred. Using cross-spectral methods, the paper shows that defining contagion as changes in the structure of co-movements of asset prices encompasses more of the complex nature of exchange rate dynamics. What is shown is that, following August 2007, there is increased in the intensity of co-movements, but non-linearly. Focusing on the activities of a mix of banks and currency managers, it is suggested that changes in the structure of currency interaction present an unfavourable view of the contagion experienced by at least three of these currencies

    The evolution of dosage-compensation mechanisms

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    Novel Techniques for Decomposing Diffuse Backgrounds

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    The total anisotropy of a diffuse background composed of two or more sources, such as the Fermi-Large Area Telescope (LAT)-measured gamma-ray background, is set by the anisotropy of each source population and the contribution of each population to the total intensity. The total anisotropy as a function of energy (the anisotropy energy spectrum) will modulate as the relative contributions of the sources change, implying that the anisotropy energy spectrum also encodes the intensity spectrum of each source class. We develop techniques, applicable to any such diffuse background, for unraveling the intensity spectrum of each component source population given a measurement of the total intensity spectrum and the total anisotropy energy spectrum, without introducing a priori assumptions about the spectra of the source classes. We demonstrate the potential of these methods by applying them to example scenarios for the composition of the Fermi-LAT gamma-ray background consistent with current data and feasible within 10 yr of observation

    Practical Student Self-affirmation

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    This research paper focuses on student peer interactional relationships in a tertiary level classroom setting in Japan. The research is based on the use of one piece of technology, Microsoft PowerPoint, to illustrate student peer interactional relationships during presentation tasks throughout the 2015 Spring Semester. The application of the particular software used in this research is of little importance, in that any piece of software could be used to investigate student interaction. The important findings of this research indicate that students can be made aware of their self-affirmation through an application of sociolinguistics and an introduction of critical pedagogy that encompasses a significant reduction in the influence of the traditional ‘teacher’ role to the benefit of student empowerment. The role of the student changes from being the passive object to that of a more active Subject role, as that of the ‘teacher,’ or better termed ‘facilitator,’ dispenses their traditional paternalistic, authoritative Subject position, in favor of being one that helps to bring about ‘…an outcome (as learning, productivity, or communication) by providing indirect or unobtrusive assistance, guidance, or supervision,’ on the part of the ‘facilitator,’ as it is defined in the Miriam-Webster dictionary (2015). For students to adopt a more active role requires a change in study habits, which requires more effort. However, this adheres perfectly to the Kyoai College motto; ‘You can develop your ability though it might be hard’ (Kyoai, 2015)

    Chiasma

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    Newspaper reporting on events at the Boston University School of Medicine in the 1960s

    The detection of geothermal areas from Skylab thermal data

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    Skylab-4 X-5 thermal data of the geysers area was analyzed to determine the feasibility of using midday Skylab images to detect geothermal areas. The hottest ground areas indicated on the Skylab image corresponded to south-facing barren or sparsely vegetated slopes. A geothermal area approximately 15 by 30 m coincided with one of the hottest areas indicated by Skylab. This area could not be unambiguously distinguished from the other areas which are believed to be hotter than their surroundings as a result of their topography, and micrometeorological conditions. A simple modification of a previous thermal model was performed and the predicted temperatures for the hottest slopes using representative values was in general agreement with the observed data. It is concluded that data from a single midday Skylab pass cannot be used to locate geothermal areas

    The detectability of dark matter annihilation with Fermi using the anisotropy energy spectrum of the gamma-ray background

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    The energy-dependence of the anisotropy (the anisotropy energy spectrum) of the large-scale diffuse gamma-ray background can reveal the presence of multiple source populations. Annihilating dark matter in the substructure of the Milky Way halo could give rise to a modulation in the anisotropy energy spectrum of the diffuse gamma-ray emission measured by Fermi, enabling the detection of a dark matter signal. We determine the detectability of a dark-matter-induced modulation for scenarios in which unresolved blazars are the primary contributor to the measured emission above ~1 GeV and find that in some scenarios pair-annihilation cross sections of order the value expected for thermal relic dark matter can produce a detectable feature. We anticipate that the sensitivity of this technique to specific dark matter models could be improved by tailored likelihood analysis methods.Comment: 9 pages, 7 figures; figures updated, other minor revisions, published in Ap

    Gamma-ray signatures of annihilation to charged leptons in dark matter substructure

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    Due to their higher concentrations and small internal velocities, Milky Way subhalos can be at least as important as the smooth halo in accounting for the GeV positron excess via dark matter annihilation. After showing how this can be achieved in various scenarios, including in Sommerfeld models, we demonstrate that, in this case, the diffuse inverse-Compton emission resulting from electrons and positrons produced in substructure leads to a nearly-isotropic signal close to the level of the isotropic GeV gamma-ray background seen by Fermi. Moreover, we show that HESS cosmic-ray electron measurements can be used to constrain multi-TeV internal bremsstrahlung gamma rays arising from annihilation to charged leptons.Comment: 8 pages, 4 figures; minor updates to match published versio

    Research and education in management of large-scale technical programs

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    A research effort is reported which was conducted by NASA in conjunction with Drexel University, and which was aimed at an improved understanding of large scale systems technology and management
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