A graph-spectral approach to shape-from-shading

In this paper, we explore how graph-spectral methods can be used to develop a new shape-from-shading algorithm. We characterize the field of surface normals using a weight matrix whose elements are computed from the sectional curvature between different image locations and penalize large changes in surface normal direction. Modeling the blocks of the weight matrix as distinct surface patches, we use a graph seriation method to find a surface integration path that maximizes the sum of curvature-dependent weights and that can be used for the purposes of height reconstruction. To smooth the reconstructed surface, we fit quadrics to the height data for each patch. The smoothed surface normal directions are updated ensuring compliance with Lambert's law. The processes of height recovery and surface normal adjustment are interleaved and iterated until a stable surface is obtained. We provide results on synthetic and real-world imagery

Typification and economic analysis of beef-producing farms in Spain

In spite of different economic agents’ interests, as well as the Administration’s effort in promoting extensive beef-producing systems over the last years, this kind of activity still hasn’t reached the desirable levels, being necessary that farmers perceive an appropriate benefit which supports their activity. In this sense, this paper, using the data obtained by a statistical survey representing all the extensive beef-producing farms existing in Castile and Leon (Spain), aims to analyze the economical results of extensive beef-producing farms, previously classified in representative groups according a quantitative method. The study is a preliminary research which intends to generate additional knowledge about the role of the different variables which make part of the economic results, and takes part of a research project financed by Castile and Leon Regional Governments, Education and Culture Council, through the annual program to support research projects (Order EDU/1143/2004).Cluster Analysis, extensive beef producing systems, economic accounts, Livestock Production/Industries,

Equation of state of a seven-dimensional hard-sphere fluid. Percus-Yevick theory and molecular dynamics simulations

Following the work of Leutheusser [Physica A 127, 667 (1984)], the solution to the Percus-Yevick equation for a seven-dimensional hard-sphere fluid is explicitly found. This allows the derivation of the equation of state for the fluid taking both the virial and the compressibility routes. An analysis of the virial coefficients and the determination of the radius of convergence of the virial series are carried out. Molecular dynamics simulations of the same system are also performed and a comparison between the simulation results for the compressibility factor and theoretical expressions for the same quantity is presented.Comment: 12 pages, 4 figures; v3: Equation (A.19) corrected (see http://dx.doi.org/10.1063/1.2390712

Dual contribution to amplification in the mammalian inner ear

The inner ear achieves a wide dynamic range of responsiveness by mechanically amplifying weak sounds. The enormous mechanical gain reported for the mammalian cochlea, which exceeds a factor of 4,000, poses a challenge for theory. Here we show how such a large gain can result from an interaction between amplification by low-gain hair bundles and a pressure wave: hair bundles can amplify both their displacement per locally applied pressure and the pressure wave itself. A recently proposed ratchet mechanism, in which hair-bundle forces do not feed back on the pressure wave, delineates the two effects. Our analytical calculations with a WKB approximation agree with numerical solutions.Comment: 4 pages, 4 figure

Banning open carry of unloaded handguns decreases firearm-related fatalities and hospital utilization.

BackgroundSince 1967, in California it has been illegal to openly carry a loaded firearm in public except when engaged in hunting or law enforcement. However, beginning January 1, 2012, public open carry of unloaded handguns also became illegal. Fatal and non-fatal (NF) firearm injuries were examined before and after adoption of the 2012 ban to quantify the effect of the new law on public health.MethodsState-level data were obtained directly from California and nine other US state inpatient and emergency department (ED) discharge databases, and the Centers for Disease Control Web-Based Injury Statistics Query and Reporting System. Case numbers of firearm fatalities, NF hospitalizations, NF ED visits, and state-level population estimates were extracted. Each incident was classified as unintentional, self-inflicted, or assault. Crude incidence rates were calculated. The strength of gun laws was quantified using the Brady grade. There were no changes to open carry in these nine states during the study. Using a difference-in-difference technique, the rate trends 3 years preban and postban were compared.ResultsThe 2012 open carry ban resulted in a significantly lower incident rate of both firearm-related fatalities and NF hospitalizations (p<0.001). The effect of the law remained significant when controlling for baseline state gun laws (p<0.001). Firearm incident rate drops in California were significant for male homicide (p=0.023), hospitalization for NF assault (p=0.021  male; p=0.025 female), and ED NF assault visits (p=0.04). No significant decreases were observed by sex for suicides or unintentional injury. Changing the law saved an estimated 337 lives (3.6% fewer deaths) and 1285 NF visits in California during the postban period.DiscussionOpen carry ban decreases fatalities and healthcare utilization even in a state with baseline strict gun laws. The most significant impact is from decreasing firearm-related fatal and NF assaults.Level of evidenceIII, epidemiology