26,835 research outputs found

    The strong nonlinear interaction of Tollmien-Schlichting waves and Taylor-Goertler vortices in curved channel flow

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    Viscous fluid flows with curved streamlines can support both centrifugal and viscous traveling wave instabilities. Here the interaction of these instabilities in the context of the fully developed flow in a curved channel is discussed. The viscous (Tollmein-Schlichting) instability is described asymptotically at high Reynolds numbers and it is found that it can induce a Taylor-Goertler flow even at extremely small amplitudes. In this interaction, the Tollmein-Schlichting wave can drive a vortex state with wavelength either comparable with the channel width or the wavelength of lower branch viscous modes. The nonlinear equations which describe these interactions are solved for nonlinear equilibrium states

    Rutger's CAM2000 chip architecture

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    This report describes the architecture and instruction set of the Rutgers CAM2000 memory chip. The CAM2000 combines features of Associative Processing (AP), Content Addressable Memory (CAM), and Dynamic Random Access Memory (DRAM) in a single chip package that is not only DRAM compatible but capable of applying simple massively parallel operations to memory. This document reflects the current status of the CAM2000 architecture and is continually updated to reflect the current state of the architecture and instruction set

    Tau Appearance In Atmospheric Neutrino Interactions

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    If the correct interpretation of the Super-Kamiokande atmospheric neutrino data is \nu_\mu -> \nu_\tau oscillation, the contained data sample should already have more than 10 tau appearance events. We study the challenging task of detecting the tau, focussing on the decay chain \tau^\pm -> \rho^\pm -> \pi^\pm \pi^0 in events with quasi-elastic tau production. The background level, which is currently quite uncertain because of a lack of relevant neutral current data, can be measured by the near detector in the K2K experiment. Our estimates of the background suggest that it may be possible to detect tau appearance in Super-Kamiokande with 5-10 years of running.Comment: 13 pages, uses psfi

    Recent developments in the application of risk analysis to waste technologies.

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    The European waste sector is undergoing a period of unprecedented change driven by business consolidation, new legislation and heightened public and government scrutiny. One feature is the transition of the sector towards a process industry with increased pre-treatment of wastes prior to the disposal of residues and the co-location of technologies at single sites, often also for resource recovery and residuals management. Waste technologies such as in-vessel composting, the thermal treatment of clinical waste, the stabilisation of hazardous wastes, biomass gasification, sludge combustion and the use of wastes as fuel, present operators and regulators with new challenges as to their safe and environmentally responsible operation. A second feature of recent change is an increased regulatory emphasis on public and ecosystem health and the need for assessments of risk to and from waste installations. Public confidence in waste management, secured in part through enforcement of the planning and permitting regimes and sound operational performance, is central to establishing the infrastructure of new waste technologies. Well-informed risk management plays a critical role. We discuss recent developments in risk analysis within the sector and the future needs of risk analysis that are required to respond to the new waste and resource management agenda

    Content addressable memory project

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    A parameterized version of the tree processor was designed and tested (by simulation). The leaf processor design is 90 percent complete. We expect to complete and test a combination of tree and leaf cell designs in the next period. Work is proceeding on algorithms for the computer aided manufacturing (CAM), and once the design is complete we will begin simulating algorithms for large problems. The following topics are covered: (1) the practical implementation of content addressable memory; (2) design of a LEAF cell for the Rutgers CAM architecture; (3) a circuit design tool user's manual; and (4) design and analysis of efficient hierarchical interconnection networks

    Oscillations of solar and atmospheric neutrinos

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    Motivated by recent results from SuperKamiokande, we study both solar and atmospheric neutrino fluxes in the context of oscillations of the three known neutrinos. We aim at a global view which identifies the various possibilities, rather than attempting the most accurate determination of the parameters of each scenario. For solar neutrinos we emphasise the importance of performing a general analysis, independent of any particular solar model and we consider the possibility that any one of the techniques --- chlorine, gallium or water Cerenkov --- has a large unknown systematic error, so that its results should be discarded. The atmospheric neutrino anomaly is studied by paying special attention to the ratios of upward and downward going nu_e and nu_mu fluxes. Both anomalies can be described in a minimal scheme where the respective oscillation frequencies are widely separated or in non-minimal schemes with two comparable oscillation frequencies. We discuss explicit forms of neutrino mass matrices in which both atmospheric and solar neutrino fluxes are explained. In the minimal scheme we identify only two `zeroth order' textures that can result from unbroken symmetries. Finally we discuss experimental strategies for the determination of the various oscillation parameters.Comment: 20 pages, 7 figures. Final version: one reference added; fit of atmospheric neutrinos improve

    Exactly solvable model of dissipative vortex tunneling

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    I consider the problem of vortex tunneling in a two-dimensional superconductor. The vortex dynamics is governed by the Magnus force and the Ohmic friction force. Under-barrier motion in the vicinity of the saddle point of the pinning potential leads to a model with quadratic Hamiltonian which can be analytically diagonalized. I find the dependence of the tunneling probability on the normal state quasiparticle relaxation time τ\tau with a minimum at ω0τ1\omega_0\tau\sim 1, where ω0\omega_0 is the level spacing of the quasiparticle bound states inside the vortex core. The results agree qualitatively with the available experimental data.Comment: RevTeX, 6 pages, 2 figures. Published versio

    Manipulating Self-Assembly in Silver(I) Complexes of 1,3-Di-\u3cem\u3eN\u3c/em\u3e-pyrazolylorganyls

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    Three di-N-pyrazolylorganyls with different conformational flexibilities in the three-atom organyl spacers have been prepared, and the self-assembly properties with AgBF4 have been studied both in solution and in the solid state. All ligands give low-coordinate silver(I) centers that are capable of participating in multiple noncovalent interactions, but only the rigid 1,8-dipyrazolylnaphthalene ligand promotes very short Ag−Ag contacts

    Association between osteoarthritis and cardiovascular disease: systematic review and meta-analysis

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    Background: To examine for a possible relationship between osteoarthritis and cardiovascular disease (CVD). Design: A systematic review and meta-analysis Methods: Published and unpublished literature from: MEDLINE, EMBASE, CINAHL, the Cochrane Library, OpenGrey and clinical trial registers. Search to 22nd November 2014. Cohort, case-control, randomised and non-randomised controlled trial papers reporting the prevalence of CVD in osteoarthritis were included. Results: Fifteen studies with 32,278,744 individuals were eligible. Pooled prevalence for overall CVD pathology in people with osteoarthritis was 38.4% (95% Confidence interval (CI): 37.2% to 39.6%). Individuals with osteoarthritis were almost three times as likely to have heart failure (Relative Risk (RR): 2.80; 95% CI: 2.25 to 3.49) or ischaemic heart disease (RR: 1.78; 95% CI: 1.18 to 2.69) compared to matched non-osteoarthritis cohorts. No significant difference was detected between the two groups for the risk of experiencing myocardial infarction or stroke. There was a three-fold decrease in the risk of experiencing a transient ischaemic attack in the osteoarthritis cohort compared to the non-osteoarthritis group. Conclusions: Prevalence of CVD in patients with OA is significant. There was an observed increased risk of incident heart failure and ischaemic heart disease in people with OA compared to matched controls. However the relationship between OA and CVD is not straight-forward and there is a need to better understand the potential common pathways linking pathophysiological mechanisms
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