3,077 research outputs found

    Inter- and Intramolecular recombinations in the Cucumber Mosaic Virus genome related to adaptation to Alstroemeria

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    In four distinct alstroemeria-infecting cucumber mosaic virus (CMV) isolates, additional sequences of various lengths were present in the 3' nontranslated regions of their RNAs 2 and 3, apparently the result of intra- and intermolecular recombination events. Competition experiments revealed that these recombined RNA 2 and 3 segments increased the biological fitness of CMV in alstroemeri

    Adaptation to climate change on arable farms in the Dutch province of Flevoland. An inventory for the AgriAdapt project

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    In Flevoland, arable farming is the most dominant land use. Adaptation options related to water, pests and diseases have been studied using a literature review. The green-blue zone Oostvaarderswold in Flevoland contributes to water storage, to nature conservation and to recreation. Compensation costs for structural wetting that are associated with various frequencies of flooding have been calculated. At inundation frequencies greater than once in 5 years, buying the agricultural land might be a better option than compensating for inundation damage or income loss. Various policies will have an effect on future agriculture in the province. A literature survey of spatial policy plans shows that urbanisation will increase and that some cities, like Almere, Lelystad, Dronten and Emmeloord, will continue to grow and expand. As a consequence, more inhabitants will require more space for nature and recreational activities, which in turn will lead to agricultural land being required

    The Price of Anarchy for Selfish Ring Routing is Two

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    We analyze the network congestion game with atomic players, asymmetric strategies, and the maximum latency among all players as social cost. This important social cost function is much less understood than the average latency. We show that the price of anarchy is at most two, when the network is a ring and the link latencies are linear. Our bound is tight. This is the first sharp bound for the maximum latency objective.Comment: Full version of WINE 2012 paper, 24 page

    Levels of total mercury in predatory fish sold in Canada in 2005

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    Total mercury was analysed in 188 samples of predatory fish purchased at the retail level in Canada in 2005. The average concentrations (ng g−1, range) were: sea bass 329 (38–1367), red snapper 148 (36–431), orange roughy 543 (279–974), fresh water trout 55 (20–430), grouper 360 (8–1060), black cod 284 (71–651), Arctic char 37 (28–54), king fish 440 (42–923), tilefish 601 (79–1164) and marlin 854 (125–2346). The Canadian standard for maximum total mercury allowed in the edible portions of fish sold at the retail level is 1000 ng g−1 for shark, swordfish, marlin, orange roughy, escolar and both fresh and frozen tuna. The standard is 500 ng g−1 for all other types of fish. In this study, despite the small number of samples of each species, the 1000 ng g–1 maximum was exceeded in five samples of marlin (28%). The 500 ng g−1 maximum was exceeded by six samples of sea bass (20%), four of tilefish (50%), five of grouper (24%), six of king fish (40%) and one of black cod (13%)

    Operation of a DNA-Based Autocatalytic Network in Serum

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    The potential for inferring the presence of cancer by the detection of miRNA in human blood has motivated research into the design and operation of DNA-based chemical amplifiers that can operate in bodily fluids. As a first step toward this goal, we have tested the operation of a DNA-based autocatalytic network in human serum and mouse serum. With the addition of sodium dodecyl sulfate to prevent degradation by nuclease activity, the network was found to operate successfully with both DNA and RNA catalysts

    Closed Strings with Low Harmonics and Kinks

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    Low-harmonic formulas for closed relativistic strings are given. General parametrizations are presented for the addition of second- and third-harmonic waves to the fundamental wave. The method of determination of the parametrizations is based upon a product representation found for the finite Fourier series of string motion in which the constraints are automatically satisfied. The construction of strings with kinks is discussed, including examples. A procedure is laid out for the representation of kinks that arise from self-intersection, and subsequent intercommutation, for harmonically parametrized cosmic strings.Comment: 39, CWRUTH-93-

    The pseudogap state in superconductors: Extended Hartree approach to time-dependent Ginzburg-Landau Theory

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    It is well known that conventional pairing fluctuation theory at the Hartree level leads to a normal state pseudogap in the fermionic spectrum. Our goal is to extend this Hartree approximated scheme to arrive at a generalized mean field theory of pseudogapped superconductors for all temperatures TT. While an equivalent approach to the pseudogap has been derived elsewhere using a more formal Green's function decoupling scheme, in this paper we re-interpret this mean field theory and BCS theory as well, and demonstrate how they naturally relate to ideal Bose gas condensation. Here we recast the Hartree approximated Ginzburg-Landau self consistent equations in a T-matrix form. This recasting makes it possible to consider arbitrarily strong attractive coupling, where bosonic degrees of freedom appear at T T^* considerably above TcT_c. The implications for transport both above and below TcT_c are discussed. Below TcT_c we find two types of contributions. Those associated with fermionic excitations have the usual BCS functional form. That they depend on the magnitude of the excitation gap, nevertheless, leads to rather atypical transport properties in the strong coupling limit, where this gap (as distinct from the order parameter) is virtually TT-independent. In addition, there are bosonic terms arising from non-condensed pairs whose transport properties are shown here to be reasonably well described by an effective time-dependent Ginzburg-Landau theory.Comment: 14 pages, 5 figures, REVTeX4, submitted to PRB; clarification of the diagrammatic technique added, one figure update

    Molecular dynamics study of melting of a bcc metal-vanadium II : thermodynamic melting

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    We present molecular dynamics simulations of the thermodynamic melting transition of a bcc metal, vanadium using the Finnis-Sinclair potential. We studied the structural, transport and energetic properties of slabs made of 27 atomic layers with a free surface. We investigated premelting phenomena at the low-index surfaces of vanadium; V(111), V(001), and V(011), finding that as the temperature increases, the V(111) surface disorders first, then the V(100) surface, while the V(110) surface remains stable up to the melting temperature. Also, as the temperature increases, the disorder spreads from the surface layer into the bulk, establishing a thin quasiliquid film in the surface region. We conclude that the hierarchy of premelting phenomena is inversely proportional to the surface atomic density, being most pronounced for the V(111) surface which has the lowest surface density
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