1,678 research outputs found

    Vortex Redistribution below the First-Order Transition Temperature in the \beta-Pyrochlore Superconductor KOs_2O_6

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    A miniature Hall sensor array was used to detect magnetic induction locally in the vortex states of the β\beta-pyrochlore superconductor KOs2_2O6_6. Below the first-order transition at Tp8T_{\rm p}\sim 8 K, which is associated with a change in the rattling motion of K ions, the lower critical field and the remanent magnetization both show a distinct decrease, suggesting that the electron-phonon coupling is weakened below the transition. At high magnetic fields, the local induction shows an unexpectedly large jump at TpT_{\rm p} whose sign changes with position inside the sample. Our results demonstrate a novel redistribution of vortices whose energy is reduced abruptly below the first-order transition at TpT_{\rm p}.Comment: 5 pages, 4 figures, to be published in Phys. Rev. Let

    Архаїчні рушники Півдня України (сюжети і семантика)

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    Groundwater is a life-sustaining resource that supplies water to billions of people, plays a central part in irrigated agriculture and influences the health of many ecosystems1,2. Most assessments of global water resources have focused on surface water3–6, but unsustainable depletion of groundwater has recently been documented on both regional7,8 and global scales9–11. It remains unclear how the rate of global groundwater depletion compares to the rate of natural renewal and the supply needed to support ecosystems. Here we define the groundwater footprint (the area required to sustain groundwater use and groundwater-dependent ecosystem services) and show that humans are overexploiting groundwater in many large aquifers that are critical to agriculture, especially in Asia and North America. We estimate that the size of the global groundwater footprint is currently about 3.5 times the actual area of aquifers and that about 1.7 billion people live in areas where groundwater resources and/or groundwater-dependent ecosystems are under threat. That said, 80 per cent of aquifers have a groundwater footprint that is less than their area, meaning that the net global value is driven by a few heavily overexploited aquifers. The groundwater footprint is the first tool suitable for consistently evaluating the use, renewal and ecosystem requirements of groundwater at an aquifer scale. It can be combined with the water footprint and virtual water calculations12–14, and be used to assess the potential for increasing agricultural yields with renewable groundwaterref15. The method could be modified to evaluate other resources with renewal rates that are slow and spatially heterogeneous, such as fisheries, forestry or soil

    Vortex Solid-Liquid Transition in Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta} with a High Density of Strong Pins

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    The introduction of a large density of columnar defects in %underdoped Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta} crystals does not, at sufficiently low vortex densities, increase the irreversibility line beyond the first order transition (FOT) field of pristine crystals. At such low fields, the flux line wandering length rwr_{w} behaves as in pristine %Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta} crystals. Next, vortex positional correlations along the cc--axis in the vortex Bose glass at fields above the FOT are smaller than in the low--field vortex solid. Third, the Bose-glass-to-vortex liquid transition is signaled by a rapid decrease in c-axis phase correlations. These observations are understood in terms of the ``discrete superconductor'' model.Comment: 4 pages, 4 figures Submitted to Phys. Rev. B Rapid Comm. 16-1-2004 Revised version 18-3-200

    Концепция управления персоналом банка

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    Рассмотрены проблемы управления персоналом в коммерческих банках Украины в современных условиях перехода страны к рыночным отношениям. Даны предложения о том, что концепция работы с персоналом в Национальном банке может быть построена на взаимосвязи ее основных механизмов.Розглянуті проблеми управління персоналом в комерційних банках України в сучасних умовах переходу країни до ринкових відносин. Дані пропозиції про те, що концепція роботи з персоналом в Національному банку може бути побудований на взаємозв'язку її основних механізмів.The problems of personnel management in the commercial banks of Ukraine in the modern terms of transition of country to the market conditions are considered. Suggestions that conception of work with a personnel in the National bank can be built on intercommunication of its basic mechanisms are given

    Magnetization Decay due to Vortex Phase Boundary Motion in BSCCO

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    We identify a new regime of decay of the irreversible magnetization in clean Bi2_{2}Sr2_{2}CaCu2_{2}O8_{8} crystals, at induction values close to the ``second peak field'' at which the bulk critical current density steeply increases. A time window is identified during which the decay of the induction is controlled by the slow propagation of the phase transformation front across the sample.Comment: 2 pages, 3 figures Paper submitted to the conference proceedings of M2S-2000 Houston T

    New High Field State of Flux Line Lattice in Unconventional Superconductor CeCoIn_5

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    Ultrasound velocity measurements of the unconventional superconductor CeCoIn_5 with extremely large Pauli paramagnetic susceptibility reveal an unusual structural transformation of the flux line lattice (FLL) in the vicinity of the upper critical field. The transition field coincides with that at which heat capacity measurements reveal a second order phase transition. The lowering of the sound velocity at the transition is consistent with the collapse of the FLL tilt modulus and a crossover to quasi two-dimensional FLL pinning. These results provide a strong evidence that the high field state is the Fulde-Ferrel-Larkin-Ovchinikov phase, in which the order parameter is spatially modulated and has planar nodes aligned perpendicular to the vortices.Comment: 5 pages, 4 figure

    Severe leptospirosis in a Dutch traveller returning from the Dominican Republic, October 2011

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    In October 2011, a case of leptospirosis was identified in a Dutch traveller returning from the Dominican Republic to the Netherlands. The 51-year-old man had aspired muddy water in the Chavón river on 29 September. Twenty days later he presented with fever, nausea, vomiting, diarrhoea, arthralgia, headache, conjunctival suffusion and icterus. Leptospira serovar Icterohaemorrhagiae or Australis infection was confirmed ten days later by laboratory testing

    On Distributive Subalgebras of Qualitative Spatial and Temporal Calculi

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    Qualitative calculi play a central role in representing and reasoning about qualitative spatial and temporal knowledge. This paper studies distributive subalgebras of qualitative calculi, which are subalgebras in which (weak) composition distributives over nonempty intersections. It has been proven for RCC5 and RCC8 that path consistent constraint network over a distributive subalgebra is always minimal and globally consistent (in the sense of strong nn-consistency) in a qualitative sense. The well-known subclass of convex interval relations provides one such an example of distributive subalgebras. This paper first gives a characterisation of distributive subalgebras, which states that the intersection of a set of n3n\geq 3 relations in the subalgebra is nonempty if and only if the intersection of every two of these relations is nonempty. We further compute and generate all maximal distributive subalgebras for Point Algebra, Interval Algebra, RCC5 and RCC8, Cardinal Relation Algebra, and Rectangle Algebra. Lastly, we establish two nice properties which will play an important role in efficient reasoning with constraint networks involving a large number of variables.Comment: Adding proof of Theorem 2 to appendi
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