79,260 research outputs found
Computer code to interchange CDS and wave-drag geometry formats
A computer program has been developed on the PRIME minicomputer to provide an interface for the passage of aircraft configuration geometry data between the Rockwell Configuration Development System (CDS) and a wireframe geometry format used by aerodynamic design and analysis codes. The interface program allows aircraft geometry which has been developed in CDS to be directly converted to the wireframe geometry format for analysis. Geometry which has been modified in the analysis codes can be transformed back to a CDS geometry file and examined for physical viability. Previously created wireframe geometry files may also be converted into CDS geometry files. The program provides a useful link between a geometry creation and manipulation code and analysis codes by providing rapid and accurate geometry conversion
Striking at the Roots of Crime: The Impact of Social Welfare Spending on Crime During the Great Depression
The Great Depression of the 1930s led contemporaries to worry that people hit by hard times would turn to crime in their efforts to survive. Franklin Roosevelt argued that the unprecedented and massive expansion in relief efforts “struck at the roots of crime” by providing subsistence income to needy families. After constructing a panel data set for 81 large American cities for the years 1930 through 1940, we estimate the impact of relief spending by all levels of government on crime rates. The analysis suggests that a ten percent increase in relief spending during the 1930s lowered property crime by roughly 1.5 percent. By limiting the amount of free time for relief recipients, work relief was more effective than direct relief in reducing crime. More generally, our results indicate that social insurance, which tends to be understudied in economic analyses of crime, should be more explicitly and more carefully incorporated into the analysis of temporal and spatial variations in criminal activity.
Topological gravity localization on a delta-function like Brane
Besides the String Theory context, the quantum General Relativity can be
studied by the use of constrained topological field theories. In the celebrated
Plebanski formalism, the constraints connecting topological field theories and
gravity are imposed in space-times with trivial topology. In the braneworld
context there are two distinct regions of the space-time, namely, the bulk and
the braneworld volume. In this work we show how to construct topological
gravity in a scenario containing one extra dimension and a delta-function like
3-brane which naturally emerges from a spontaneously broken discrete symmetry.
Starting from a D=5 theory we obtain the action for General Relativity in the
Palatini form in the bulk as well as in the braneworld volume. This result is
important for future insights about quantum gravity in brane scenarios.Comment: 4 page
A Method for Reducing the Severity of Epidemics by Allocating Vaccines According to Centrality
One long-standing question in epidemiological research is how best to
allocate limited amounts of vaccine or similar preventative measures in order
to minimize the severity of an epidemic. Much of the literature on the problem
of vaccine allocation has focused on influenza epidemics and used mathematical
models of epidemic spread to determine the effectiveness of proposed methods.
Our work applies computational models of epidemics to the problem of
geographically allocating a limited number of vaccines within several Texas
counties. We developed a graph-based, stochastic model for epidemics that is
based on the SEIR model, and tested vaccine allocation methods based on
multiple centrality measures. This approach provides an alternative method for
addressing the vaccine allocation problem, which can be combined with more
conventional approaches to yield more effective epidemic suppression
strategies. We found that allocation methods based on in-degree and inverse
betweenness centralities tended to be the most effective at containing
epidemics.Comment: 10 pages, accepted to ACM BCB 201
Exact supersymmetry in the relativistic hydrogen atom in general dimensions -- supercharge and the generalized Johnson-Lippmann operator
A Dirac particle in general dimensions moving in a 1/r potential is shown to
have an exact N = 2 supersymmetry, for which the two supercharge operators are
obtained in terms of (a D-dimensional generalization of) the Johnson-Lippmann
operator, an extension of the Runge-Lenz-Pauli vector that relativistically
incorporates spin degrees of freedom. So the extra symmetry (S(2))in the
quantum Kepler problem, which determines the degeneracy of the levels, is so
robust as to accommodate the relativistic case in arbitrary dimensions.Comment: 4 pages, 1 figur
Development of shape memory metal as the actuator of a fail safe mechanism
A small, compact, lightweight device was developed using shape memory alloy (SMA) in wire form to actuate a pin-puller that decouples the flanges of two shafts. When the SMA is heated it contracts producing a useful force and stroke. As it cools, it can be reset (elongated in this case) by applying a relatively small force. Resistive heating is accomplished by running a current through the SMA wire for a controlled length of time. The electronics to drive the device are not elaborate or complicated, consisting of a timed current source. The total available contraction is 3 percent of the length of the wire. This device, the engineering properties of the SMA, and the tests performed to verify the design concept are described
Containment experiments in vortex tubes with radial outflow and large superimposed axial flows
Containment tests of vortexes with radial outflow in basic vortex tube, and in axial-flow vortex tub
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