9,576 research outputs found

    Computer program documentation for the pasture/range condition assessment processor

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    The processor which drives for the RANGE software allows the user to analyze LANDSAT data containing pasture and rangeland. Analysis includes mapping, generating statistics, calculating vegetative indexes, and plotting vegetative indexes. Routines for using the processor are given. A flow diagram is included

    Time maintenance of user clocks via the tracking and data relay satellite system

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    A system is described which uses the Tracking and Data Relay Satellite System (TDRSS) itself to compare the user satellite clock with a clock at the White Sands station that is referenced to Universal Time Coordinated (UTC). No command of the spacecraft by the system is required, and actual on-board clock corrections are made by the spacecraft control center at its discretion. Computer models were constructed using basic orbital parameters for user and TDRS satellites. With only first-order corrections and simple averaging techniques for constant clock rates, error measurement precision of better than one microsecond was obtained. More sophisticated computations should allow considerable improvement over this

    Personal indebtedness, community characteristics and theft crimes

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    Debt played a central role in the Great Recession, both in its cause and in its resolution, and once again, concern is rising about household indebtedness. This paper examines the relationship between personal indebtedness and theft crime using information on personal debt default. This paper builds on an established literature examining economic conditions and community crime rates, with an analytical framework provided by the Becker (1968) and Stigler (1974). Our paper is motivated from the economic, sociology and criminology literatures, and extends to a fuller consideration of the relationship between economic hardship and theft crimes in an urban setting. In particular, the sociology and criminology literature permit a much deeper understanding of the human behaviour and motivations underpinning the relationships represented in the market model of crime. Using data available at the neighbourhood level for London, UK on county court judgments (CCJ's) granted against residents in each neighbourhood as our measure of personal indebtedness, we examine the relationship between this measure, as well as a range of community characteristics, and the observed pattern of theft crimes using spatial econometric methods. Our results confirm that theft crimes in London follow a spatial process, and that personal indebtedness is positively associated with theft crimes in London. We identify a number of interesting results, for instance that there is variation in the impact of covariates across crime types, and that the covariates which are important in explaining the pattern of each crime type are largely stable across the period considered in this analysis

    Self-pulsing dynamics in a cavity soliton laser

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    The dynamics of a broad-area vertical-cavity surface-emitting laser (VCSEL) with frequency-selective feedback supporting bistable spatial solitons is analyzed experimentally and theoretically. The transient dynamics of a switch-on of a soliton induced by an external optical pulse shows strong self-pulsing at the external-cavity round-trip time with at least ten modes excited. The numerical analysis indicates an even broader bandwidth and a transient sweep of the center frequency. It is argued that mode-locking of spatial solitons is an interesting and viable way to achieve three-dimensional, spatio-temporal self-localization and that the transients observed are preliminary indications of a transient cavity light bullet in the dynamics, though on a non negligible background

    Options for managing human threats to high seas biodiversity

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    Areas beyond national jurisdiction (ABNJ) constitute 61% of the world's oceans and are collectively managed by countries under the United Nations Convention on the Law of the Sea (UNCLOS). Growing concern regarding the deteriorating state of the oceans and ineffective management of ABNJ has resulted in negotiations to develop an international legally binding instrument (ILBI) for the conservation and sustainable use of biodiversity beyond national jurisdiction under UNCLOS. To inform these negotiations, we identified existing and emerging human activities and influences that affect ABNJ and evaluated management options available to mitigate the most pervasive, with highest potential for impact and probability of emergence. The highest-ranking activities and influences that affect ABNJ were fishing/hunting, maritime shipping, climate change and its associated effects, land-based pollution and mineral exploitation. Management options are diverse and available through a variety of actors, although their actions are not always effective. Area-based management tools (ABMTs), including marine protected areas (MPAs), were the only consistently effective option to mitigate impacts across high-ranked activities and influences. However, addressing land-based pollution will require national action to prevent this at its source, and MPAs offer only a partial solution for climate change. A new ABNJ ILBI could help unify management options and actors to conserve marine biodiversity and ensure sustainable use. Incorporating a mechanism to establish effective ABMTs into the ILBI will help deliver multiple objectives based on the ecosystem approach

    Field-Induced Magnetic and Structural Domain Alignment in PrO2

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    We present a neutron diffraction study of the magnetic structure of single crystal PrO2 under applied fields of 0-6 T. As the field is increased, changes are observed in the magnetic Bragg intensities. These changes are found to be irreversible when the field is reduced, but the original intensities can be recovered by heating to T > 122 K, then re-cooling in zero field. The antiferromagnetic ordering temperature TN = 13.5 K and the magnetic periodicity are unaffected by the applied field. We also report measurements of the magnetic susceptibility of single crystal PrO2 under applied fields of 0-7 T. These show strong anisotropy, as well as an anomaly at T = 122 +/- 2 K which coincides with the temperature TD = 120 +/- 2 K at which a structural distortion occurs. For fields applied along the [100] direction the susceptibility increases irreversibly with field in the temperature range TN < T < TD. However, for fields along [110] the susceptibility is independent of field in this range. We propose structural domain alignment, which strongly influences the formation of magnetic domains below TN, as the mechanism behind these changes.Comment: 11 pages, 13 figures, 5 tables. Minor typographical changes in v

    Long-range ferromagnetism of Mn12 acetate single-molecule magnets under a transverse magnetic field

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    We use neutron diffraction to probe the magnetization components of a crystal of Mn12 single-molecule magnets. Each of these molecules behaves, at low temperatures, as a nanomagnet with spin S = 10 and strong anisotropy along the crystallographic c axis. Application of a magnetic field perpendicular to c induces quantum tunneling between opposite spin orientations, enabling the spins to attain thermal equilibrium. Below approximately 0.9 K, intermolecular interactions turn this equilibrium state into a ferromagnetically ordered phase. However, long range ferromagnetic correlations nearly disappear for fields larger 5.5 T, possibly suggesting the existence of a quantum critical point.Comment: 4 pages, 4 figure
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