3,168 research outputs found

    The effects of Venus' thermal structure on buoyant magma ascent

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    The recent Magellan images have revealed a broad spatial distribution of surface volcanism on Venus. Previous work in modeling the ascent of magma on both Venus and Earth has indicated that the planetary thermal structure significantly influences the magmatic cooling rates and thus the amount of magma that can be transported to the surface before solidification. In order to understand which aspects of the thermal structure have the greatest influence on the cooling of ascending magma, we have constructed magma cooling curves for both plutonic and crack buoyant ascent mechanisms, and evaluated the curves for variations in the planetary mantle temperature, thermal gradient curvature with depth, surface temperature gradient, and surface temperature. The planetary thermal structure is modeled as T/T(sub 0) = 1-tau(1-Z/Z(sub 0)(exp n), where T is the temperature, T(sub 0) is the source depth temperature, tau = 1-(T(sub s)/T(sub 0)) where T(sub s) is the planetary surface temperature, Z is the depth, Z(sub 0) is the source depth, and n is a constant that controls thermal gradient curvature with depth. The equation is used both for mathematical convenience and flexibility, as well as its fit to the thermal gradients predicted by the cooling half-space models. We assume a constant velocity buoyant ascent, body-averaged magma temperatures and properties, an initially crystal-free magma, and the same liquidus and solidus for both Venus and Earth

    A Search for various Double Beta Decay Modes of Cd, Te and Zn Isotopes

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    Various double beta decay modes of Cd, Zn and Te isotopes are explored with the help of CdTe and CdZnTe semiconductor detectors. The data set is splitted in an energy range below 1 MeV having a statistics of 134.5 g⋅\cdotd and one above 1 MeV resulting in 532 g⋅\cdotd. No signals were observed in all channels under investigation. New improved limits for the neutrinoless double beta decay of Zn70 of T1/2>1.3⋅1016yrsT_{1/2} > 1.3 \cdot 10^{16} yrs (90% CL), the longest standing limit of all double beta isotopes, and 0νβ+\nu\beta^+EC of Te120 of T1/2>2.2⋅1016yrsT_{1/2} > 2.2 \cdot 10^{16} yrs (90% CL) are given. For the first time a limit on the half-life of the 2ν\nuECEC of 120^{120}Te of T1/2>9.4⋅1015yrsT_{1/2} > 9.4 \cdot 10^{15} yrs (90% CL) is obtained. In addition, limits on 2ν\nuECEC for ground state transitions of Cd106, Cd108 and Zn64 are improved. The obtained results even under rough background conditions show the reliability of CdTe semiconductor detectors for rare nuclear decay searches.Comment: Extended introduction and summar

    PHYCOERYTHROCYANINS FROM Westiellopsis prolifica AND Nostoc rivulare: CHARACTERIZATION OF THE PHYCOVIOLOBILIN CHROMOPHORE IN BOTH STATES

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    Phycoerythrocyanin or fractions enriched in it have been isolated from the filamentous cyanobacteria, Westiellopsis prolifica ARM 365 and Nostoc rivulare ARM 212. Both show the photoreversible photochromism (difference maxima at 503 and 570 nm) characteristic of this pigment, which is related to the phycoviolobilin chromophore on the α-subunit. Native phycoerythrocyanin and its β-subunit show little if any reversible photochemistry in the 600–620 nm region, where the phycocyanobilin chromophores absorb maximally. Instead the phycocyanobilin chromophores are bleached irreversibly. At the same time, the data show that reversible photochemistry is a useful analytical tool to detect phycoerythrocyanin in cyanobacterial extracts. Fluorescence measurements indicate that: (i) the 510 nm absorbing isomer of the violobilin chromophore has only little fluorescence; and (ii) the energy transfer from the violobilin chromophores to the cyanin chromophores is efficient only in the 570 nm form

    A new approach to the inverse problem for current mapping in thin-film superconductors

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    A novel mathematical approach has been developed to complete the inversion of the Biot-Savart law in one- and two-dimensional cases from measurements of the perpendicular component of the magnetic field using the well-developed Magneto-Optical Imaging technique. Our approach, especially in the 2D case, is provided in great detail to allow a straightforward implementation as opposed to those found in the literature. Our new approach also refines our previous results for the 1D case [Johansen et al., Phys. Rev. B 54, 16264 (1996)], and streamlines the method developed by Jooss et al. [Physica C 299, 215 (1998)] deemed as the most accurate if compared to that of Roth et al. [J. Appl. Phys. 65, 361 (1989)]. We also verify and streamline the iterative technique, which was developed following Laviano et al. [Supercond. Sci. Technol. 16, 71 (2002)] to account for in-plane magnetic fields caused by the bending of the applied magnetic field due to the demagnetising effect. After testing on magneto-optical images of a high quality YBa2Cu3O7 superconducting thin film, we show that the procedure employed is effective

    Statistics of Mars' topography from the Mars Orbiter Laser Altimeter: Slopes, correlations, and physical Models

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    Data obtained recently by the Mars Orbiter Laser Altimeter (MOLA) were used to study the statistical properties of the topography and slopes on Mars. We find that the hemispheric dichotomy, manifested as an elevation difference, can be described by long baseline tilts but in places is expressed as steeper slopes. The bimodal hypsometry of elevations on Mars becomes unimodal when referenced to the center of figure, contrary to the Earth, for which the bimodality is retained. However, ruling out a model in which the elevation difference is expressed in a narrow equatorial topographic step cannot be done by the hypsometry alone. Mars' slope distribution is longer tailed than those of Earth and Venus, indicating a lower efficiency of planation processes relative to relief-building tectonics and volcanics. We define and compute global maps of statistical estimators, including the interquartile scale, RMS and median slope, and characteristic decorrelation length of the surface. A correspondence between these parameters and geologic units on Mars is inferred. Surface smoothness is distinctive in the vast northern hemisphere plains, where slopes are typically <0.5°. Amazonis Planitia exhibits a variation in topography of <1 m over 35-km baselines. The region of hematite mineralization in Sinus Meridiani is also smooth, with median slopes lower than 0.4°, but does not form a closed basin. The shallower long-wavelength portion of the lowlands' topographic power spectrum relative to the highlands' can be accounted for by a simple model of sedimentation such as might be expected at an ocean's floor. The addition of another process such as cratering is necessary to explain the spectral slope in short wavelengths. Among their application, these MOLA-derived roughness measurements can help characterize sites for landing missions

    Perangkap Kemiskinan pada Warga Relokasi (Studi Korelasional: Unsur-unsur Perangkap Kemiskinan pada Warga Relokasi Pucang Mojo Kedungtungkul Mojosongo Jebres Surakarta)

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    This study is the result of the interpretation of the theory of "Poverty Trap" Robert Chambers (1983) to the social facts paradigm (Emile Dhurkheim, 1964). The purpose of this study was to determine whether or not the resident relocation poverty trap, by way of explaining whether or not the relationship between the elements of the poverty trap in this case: powerlessness, vulnerability, physical weakness, material poverty, and isolation of the Public Service, the citizens relocation Pucang Mojo, Kedungtungkul, Mojosongo, Surakarta. This study uses poverty approach both structurally and culturally. This research is survey research with an explanatory strategy. The study population was all heads of households in Housing Relocation Pucang mojo, Mojosongo, Surakarta.The number of sample was taken 50% out of total population. This study employed quantitative data with triangulation using qualitative data as the confirmer. The qualitative data used was the one derived from result of interview and observation. To examine the relationship between the elements of poverty trap, Product Moment Correlation test was used that was processed with SPSS 19.0 version IBM. The dominant result of statistic data processing in this study was then combined with qualitative data in the discussion. The result of discussion showed that: out of ten relationships between variables or elements existing, only four categorized into significant relationship, while the other six elements were proved insignificant. The four elements are shown to have a significant association among others: the poverty of material with physical weakness, material poverty with vulnerability, physical weakness with vulnerability, and isolation of the public service with the helplessness while the sixth has no correlation relationships such as: poverty with insulating material to public servants, the material poverty with powerlessness, physical weakness with insulation against public servants, physical weakness with powerlessness, isolation against public servants with vulnerability, and vulnerability to helplessness. This finding showed that not all hypotheses suggested by Robert Chambers (1983) could be proved in the context of urban poverty, particularly among the relocated people in Pucangmojo, Kedungtungkul, Mojosongo, Jebres, Surakarta

    From modular invariants to graphs: the modular splitting method

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    We start with a given modular invariant M of a two dimensional su(n)_k conformal field theory (CFT) and present a general method for solving the Ocneanu modular splitting equation and then determine, in a step-by-step explicit construction, 1) the generalized partition functions corresponding to the introduction of boundary conditions and defect lines; 2) the quantum symmetries of the higher ADE graph G associated to the initial modular invariant M. Notice that one does not suppose here that the graph G is already known, since it appears as a by-product of the calculations. We analyze several su(3)_k exceptional cases at levels 5 and 9.Comment: 28 pages, 7 figures. Version 2: updated references. Typos corrected. su(2) example has been removed to shorten the paper. Dual annular matrices for the rejected exceptional su(3) diagram are determine

    The Relationship between the UniProt Knowledgebase (UniProtKB) and the IntAct Molecular Interaction Databases

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    IntAct provides a freely available, open source database system and analysis tools for protein interaction data. All interactions are derived from literature curation or direct user submission and all experimental information relating to binary protein-protein&#xd;&#xa;interactions is entered into the IntAct database by curators, via a web-based editor. Interaction information is added to the SUBUNIT comment and the RP line of the relevant publication within the UniProtKB entry. There may be a single INTERACTION comment present within a UniProtKB entry, which conveys information relevant to binary protein-protein interactions. This is automatically derived from the IntAct database and is updated on a triweekly basis. Interactions can be derived by any appropriate experimental method but must be confirmed by a second interaction if resulting from a single yeast2hybrid experiment. For large-scale experiments, interactions are considered if a high confidence score is assigned by the authors. The INTERACTION line contains a direct link to IntAct that provides detailed information for the experimental support. These lines are not changed manually and any discrepancy is reported to IntAct for updates. There is also a database crossreference line within the UniProtKB entry i.e.: DR IntAct _UniProtKB AC, which directs the user to additional interaction data for that molecule. &#xd;&#xa;UniProt is supported by grants from the National Institutes of Health, European Commission, Swiss Federal Government and PATRIC BRC.&#xd;&#xa;IntAct is funded by the European Commission under FELICS, contract number 021902 (RII3) within the Research Infrastructure Action of the FP6 &#x22;Structuring the European Research Area&#x22; Programme
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