32,378 research outputs found
Subroutines GEORGE and DRASTC simplify operation of automatic digital plotter
FORTRAN language subroutines enable the production of a tape for a 360-30 tape unit that controls the CALCOMP 566 Digital Incremental Plotter. This provides the plotter with instructions for graphically displaying data points with the proper scaling of axes, numbering, lettering, and tic marking
NRQCD results on the MILC extra coarse ensemble
We present preliminary results using NRQCD to describe heavy quarks on the
MILC 2+1 flavour dynamical extra coarse ensemble. We calculate the spectra of
low lying states in bottomonium to complement earlier results on the finer MILC
ensembles. We then exploit the coarseness of the lattices to calculate charm
propagators using NRQCD. These are used to examine the charmonium spectrum and
to calclate the mass of the using NRQCD. Finally we look breifly at the
and systems using the imporoved staggered formalism to describe the
light valence quarks.Comment: 6 pages, Talk presented at Lattice 2005 (Heavy Quarks), Dublin, 25-30
July 200
Fracture mechanics approach to design analysis of notches, steps and internal cut-outs in planar components
A new approach to the assessment and optimization of geometric stress-concentrating features is proposed on the basis of the correspondence between sharp crack or corner stressfield intensity factors and conventional elastic stress concentration factors (SCFs) for radiused transitions. This approach complements the application of finite element analysis (FEA) and the use of standard SCF data from the literature. The method makes it possible to develop closed-form solutions for SCFs in cases where corresponding solutions for the sharp crack geometries exist. This is helpful in the context of design optimization. The analytical basis of the correspondence is shown, together with the limits on applicability where stress-free boundaries near the stress concentrating feature are present or adjacent features interact. Examples are given which compare parametric results derived from FEA with closed-form solutions based on the proposed method. New information is given on the stress state at a 90° corner or width step, where the magnitude of the stress field intensity is related to that of the corresponding crack geometry. This correspondence enables the user to extend further the application of crack-tip stress-field intensity information to square-cornered steps, external U-grooves, and internal cut-outs
Potential structural material problems in a hydrogen energy system
Potential structural material problems that may be encountered in the three components of a hydrogen energy system - production, transmission/storage, and utilization - were identified. Hydrogen embrittlement, corrosion, oxidation, and erosion may occur during the production of hydrogen. Hydrogen embrittlement is of major concern during both transmission and utilization of hydrogen. Specific materials research and development programs necessary to support a hydrogen energy system are described
Representation of Equilibrium Conditions for the Carbon Monoxide - Carbon Dioxide - Steel System
Proper conditioning of atmospheres for carburizing, for heat treating, and for carrying out other high temperature metallurgical processes depends in general on control of each system with regard to its equilibrium conditions. In connection with steel processing, numerous investigations have been made to determine equilibrium conditions for the most common gas-steel reactions. One such reaction that has been studied extensively takes place when certain mixtures of carbon monoxide and carbon dioxide come in contact with ordinary carbon steel at elevated temperatures. The purpose of this paper is to review some of the methods that have been used to represent equilibrium for this gas-steel reaction and to present a condensed but more comprehensive treatment of equilibrium for the system
Quantum memories based on engineered dissipation
Storing quantum information for long times without disruptions is a major
requirement for most quantum information technologies. A very appealing
approach is to use self-correcting Hamiltonians, i.e. tailoring local
interactions among the qubits such that when the system is weakly coupled to a
cold bath the thermalization process takes a long time. Here we propose an
alternative but more powerful approach in which the coupling to a bath is
engineered, so that dissipation protects the encoded qubit against more general
kinds of errors. We show that the method can be implemented locally in four
dimensional lattice geometries by means of a toric code, and propose a simple
2D set-up for proof of principle experiments.Comment: 6 +8 pages, 4 figures, Includes minor corrections updated references
and aknowledgement
Dipyridamole plus aspirin versus aspirin alone in the secondary prevention after TIA or stroke: a meta-analysis by risk
Objectives: Our aim was to study the effect of combination therapy with aspirin and dipyridamole (A+D) over aspirin alone (ASA) in secondary prevention after transient
ischemic attack or minor stroke of presumed arterial origin and to perform subgroup analyses to identify patients that might benefit most from secondary prevention with A+D.
Data sources: The previously published meta-analysis of individual patient data was updated with data from ESPRIT (N=2,739); trials without data on the comparison of A+D versus ASA were excluded.
Review methods: A meta-analysis was performed using Cox regression, including several subgroup analyses and following baseline risk stratification.
Results: A total of 7,612 patients (5 trials) were included in the analyses, 3,800 allocated to A+D and 3,812 to ASA alone. The trial-adjusted hazard ratio for the composite event of vascular death, non-fatal myocardial infarction and non-fatal stroke was 0.82 (95% confidence interval 0.72-0.92). Hazard ratios did not differ in subgroup analyses based on age, sex, qualifying event, hypertension, diabetes, previous stroke, ischemic heart disease,
aspirin dose, type of vessel disease and dipyridamole formulation, nor across baseline risk strata as assessed with two different risk scores. A+D were also more effective than ASA alone in preventing recurrent stroke, HR 0.78 (95% CI 0.68 – 0.90).
Conclusion: The combination of aspirin and dipyridamole is more effective than aspirin alone in patients with TIA or ischemic stroke of presumed arterial origin in the secondary
prevention of stroke and other vascular events. This superiority was found in all subgroups and was independent of baseline risk. ---------------------------7dc3521430776
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Halke
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