298 research outputs found
Lake Michigan Salmonid Stocking Costs in Wisconsin
The costs of stocking salmonids in the Wisconsin waters of Lake Michigan are estimated for 1985. Estimation procedures and costs per stocked and captured fish are presented. Fingerlings of a species were found in most cases to cost more per captured fish than yearlings. However chinook salmon fingerlings were least expensive at an average cost of only 12.67 and $10.14 respectively. While a full policy evaluation awaits additional research on species specific benefits, three tentative conclusions can be drawn for the Wisconsin fishery. First, the role of brook trout in the fishery should be reviewed. Second, despite difficulties with lake trout rehabilitation, the role of lake trout in the sport fishery is encouraging and may justify continued stocking. Finally, increased stocking of the popular chinook salmon may be justified if the recent problems of low capture-per-release rates can be solved.restocking costs, benefit-cost methodology, sport fisheries, salmonids, Lake Michigan, Environmental Economics and Policy, Resource /Energy Economics and Policy,
Fatigue Countermeasure Using Automatic Real-Time Video Processing of Eye Characteristics
Fatigue is a large and growing problem for aviators and motor vehicle drivers. A fatigue countermeasure based on digital video processing of images of the subject’s face has been developed. Digital video data of drivers was collected in experiments in a driving simulator at the University of Iowa. Algorithms were developed to automatically locate the head, eyes, and face features of the driver using wide field-of-view images. The exposed eye area is quantified using the final eye target location. Automatic processing of face features in a vehicle environment is a difficult task due to the complexity of the scene and the variable lighting conditions. The use of both static and dynamic processing in parallel and the use of symmetry has lead to the development of innovative and useful algorithms for automatic face location and feature detection. The prototype system was effective in automatic feature location for all 13 subjects tested in driving simulator studies. The appearance of visible eye features is quantified and used to determine onset of potentially dangerous fatigue conditions. An alarm event is generated if the eyes remain closed longer than 1.5 seconds, or if sustained reduction in area of exposed eye features is detected (eyelid droop). Other studies in the literature have validated correlation of measures of pupil occlusion (such as PERCLOS) with operator performance lapse. The system is designed to work with an inexpensive digital video sensor mounted on the dashboard of a vehicle and runs on standard computing hardware
High-powered Gravitational News
We describe the computation of the Bondi news for gravitational radiation. We
have implemented a computer code for this problem. We discuss the theory behind
it as well as the results of validation tests. Our approach uses the
compactified null cone formalism, with the computational domain extending to
future null infinity and with a worldtube as inner boundary. We calculate the
appropriate full Einstein equations in computational eth form in (a) the
interior of the computational domain and (b) on the inner boundary. At future
null infinity, we transform the computed data into standard Bondi coordinates
and so are able to express the news in terms of its standard and
polarization components. The resulting code is stable and
second-order convergent. It runs successfully even in the highly nonlinear
case, and has been tested with the news as high as 400, which represents a
gravitational radiation power of about .Comment: 24 pages, 4 figures. To appear in Phys. Rev.
Well-Posed Initial-Boundary Evolution in General Relativity
Maximally dissipative boundary conditions are applied to the initial-boundary
value problem for Einstein's equations in harmonic coordinates to show that it
is well-posed for homogeneous boundary data and for boundary data that is small
in a linearized sense. The method is implemented as a nonlinear evolution code
which satisfies convergence tests in the nonlinear regime and is robustly
stable in the weak field regime. A linearized version has been stably matched
to a characteristic code to compute the gravitational waveform radiated to
infinity.Comment: 5 pages, 6 figures; added another convergence plot to Fig. 2 + minor
change
Black Hole Data via a Kerr-Schild Approach
We present a new approach for setting initial Cauchy data for multiple black
hole spacetimes. The method is based upon adopting an initially Kerr-Schild
form of the metric. In the case of non-spinning holes, the constraint equations
take a simple hierarchical form which is amenable to direct numerical
integration. The feasibility of this approach is demonstrated by solving
analytically the problem of initial data in a perturbed Schwarzschild geometry.Comment: 13 pages, RevTeX forma
Loss of the Heparan Sulfate Sulfotransferase, Ndst1, in Mammary Epithelial Cells Selectively Blocks Lobuloalveolar Development in Mice
Considerable evidence indicates that heparan sulfate is essential for the development of tissues consisting of branching ducts and tubules. However, there are few examples where specific sulfate residues regulate a specific stage in the formation of such tissues.We examined the role of heparan sulfation in mammary gland branching morphogenesis, lactation and lobuloalveolar development by inactivation of heparan sulfate GlcNAc N-deacetylase/N-sulfotransferase genes (Ndst) in mammary epithelial cells using the Cre-loxP system. Ndst1 deficiency resulted in an overall reduction in glucosamine N-sulfation and decreased binding of FGF to mammary epithelial cells in vitro and in vivo. Mammary epithelia lacking Ndst1 underwent branching morphogenesis, filling the gland with ductal tissue by sexual maturity to the same extent as wildtype epithelia. However, lobuloalveolar expansion did not occur in Ndst1-deficient animals, resulting in insufficient milk production to nurture newly born pups. Lactational differentiation of isolated mammary epithelial cells occurred appropriately via stat5 activation, further supporting the notion that the lack of milk production was due to lack of expansion of the lobuloalveoli.These findings demonstrate a selective, highly penetrant, cell autonomous effect of Ndst1-mediated sulfation on lobuloalveolar development
Grazing Collisions of Black Holes via the Excision of Singularities
We present the first simulations of non-headon (grazing) collisions of binary
black holes in which the black hole singularities have been excised from the
computational domain. Initially two equal mass black holes are separated a
distance and with impact parameter . Initial data are
based on superposed, boosted (velocity ) solutions of single black
holes in Kerr-Schild coordinates. Both rotating and non-rotating black holes
are considered. The excised regions containing the singularities are specified
by following the dynamics of apparent horizons. Evolutions of up to are obtained in which two initially separate apparent horizons are present
for . At that time a single enveloping apparent horizon forms,
indicating that the holes have merged. Apparent horizon area estimates suggest
gravitational radiation of about 2.6% of the total mass. The evolutions end
after a moderate amount of time because of instabilities.Comment: 2 References corrected, reference to figure update
Dynamic scaling for 2D superconductors, Josephson junction arrays and superfluids
The value of the dynamic critical exponent is studied for two-dimensional
superconducting, superfluid, and Josephson Junction array systems in zero
magnetic field via the Fisher-Fisher-Huse dynamic scaling. We find
, a relatively large value indicative of non-diffusive
dynamics. Universality of the scaling function is tested and confirmed for the
thinnest samples. We discuss the validity of the dynamic scaling analysis as
well as the previous studies of the Kosterlitz-Thouless-Berezinskii transition
in these systems, the results of which seem to be consistent with simple
diffusion (). Further studies are discussed and encouraged.Comment: 19 pages in two-column RevTex, 8 embedded EPS figure
Helping the Working Poor: Employer- vs. Employee-Based Subsidies
In the United States and Europe there has been renewed interest in subsidizing firms that employ disadvantaged workers as a means of addressing poverty and other social problems. In contrast, the prevailing practice is largely to provide social welfare benefits directly to individuals. Which approach is better? We re-examine the relative merits of employee- versus employer-based labor market subsidies and conclude there are good reasons to continue to rely on the direct, employee-based approach. In practice, low-wage workers are seldom either low-skill or low-income workers. Furthermore, workers who might quality for a firm-based subsidy are reluctant to so identify themselves for fear of being stigmatized or labeled as needy. Thus, employer-based subsidy programs have lower participation rates and correspondingly higher per capita expenditures than employee-based subsidy programs
The hERG channel is dependent upon the Hsp90α isoform for maturation and trafficking
Heat shock protein 90 (Hsp90) has emerged as a promising therapeutic target for the treatment of cancer. Several Hsp90 inhibitors have entered clinical trials. However, some toxicological detriments have arisen, such as cardiotoxicity resulting from hERG inhibition following the administration of Hsp90 inhibitors. We sought to investigate this toxicity as hERG has been previously reported as a client protein that depends upon Hsp90 for its maturation and functional trafficking. In this study we show that hERG depends upon a single Hsp90 isoform. hERG preferentially co-immunoprecipitated with Hsp90α and genetic knockdown of Hsp90α, but not Hsp90β, resulted in a trafficking-defective hERG channel. This study demonstrates the importance of delineating the isoform dependence of Hsp90 client proteins and provides rationale for the design of isoform-selective Hsp90 inhibitors that avoid detrimental effect
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