Black hole singularities: a numerical approach

The singularity structure of charged spherical collapse is studied by considering the evolution of the gravity-scalar field system. A detailed examination of the geometry at late times strongly suggests the validity of the mass-inflation scenario~\cite{PI:90}. Although the area of the two-spheres remains finite at the Cauchy horizon, its generators are eventually focused to zero radius. Thus the null, mass-inflation singularity {\em generally}\/ precedes a crushing $r=0$ singularity deep inside the black hole core. This central singularity is spacelike.Comment: 4 pages Phys. Rev. style including five figures, provided as compressed postscript files. To appear in Physical Review Letter

Vegetative Spread of Dioecious Hydrilla Colonies in Experimental Ponds

Stolon formation and fragmentation are two vegetative mechanisms by which hydrilla colonies expand. These two mechanisms of spread were studied in ponds located in Lewisville, TX over a two-year period. Stolons were determined to be the predominant mechanism for localized expansion in undisturbed areas. While some fragments were produced, they accounted for only 0.1% of the establishment of rooted plants in new quadrats. Peak production of fragments occurred in October and November, with fragment densities of 0.15 N m-2 d-1. Expansion by stolons occurred between June and November of each year, with higher rates of spread (up to 4.0 cm d-1 radial growth) observed in the second season

Estimation of pedigree errors in the UK dairy population using microsatellite markers and the impact on selection

The proportion of cows in the UK dairy herd whose sires were misidentified was estimated using DNA markers. Genetic marker genotypes were determined on 568 cows (from 168 milk samples and 400 hair samples) and 96 putative sires (from semen samples). The estimated pedigree error rate from the hair samples was 8.8%, and from the milk samples, 13.1%, giving an overall estimate of the error rate of 10%. This level of pedigree errors will have a relatively large impact on the efficiency of progeny testing and the accuracy of cow predicted breeding values. We predict a loss of response to selection of approximately 2 to 3% given this error rate

Moral hazard under commercial and universal banking

Many claims have been made about the potential benefits, and the potential costs, of adopting a system of universal banking in the United States. We evaluate these claims using a model where there is a moral hazard problem between banks and “borrowers,” a moral hazard problem between banks and a deposit insurer, and a costly state verification problem. Under conditions we describe, allowing banks to take equity positions in firms strengthens their ability to extract surplus, and exacerbates problems of moral hazard. The incentives of universal banks to take equity positions will often be strongest when these problems are most severe.Universal banks

Sunderland Software City: The Impact of a Collaborative Project to Develop the Software Industry within the North East of England

This paper uses a case study approach to evaluate the impact of a collaborative initiative within the North East of England which sets out to grow and sustain a software industry, based on the strengths of regional players. The project Sunderland Software City has the ambitious aim of developing the people, the infrastructure and the business and enterprise culture to create and sustain a software industry. This paper focuses upon the impact of the project, and presents some lessons learned to date

Modelling the Fluid Mechanics of Cilia and Flagella in Reproduction and Development

Cilia and flagella are actively bending slender organelles, performing functions such as motility, feeding and embryonic symmetry breaking. We review the mechanics of viscous-dominated microscale flow, including time-reversal symmetry, drag anisotropy of slender bodies, and wall effects. We focus on the fundamental force singularity, higher order multipoles, and the method of images, providing physical insight and forming a basis for computational approaches. Two biological problems are then considered in more detail: (1) left-right symmetry breaking flow in the node, a microscopic structure in developing vertebrate embryos, and (2) motility of microswimmers through non-Newtonian fluids. Our model of the embryonic node reveals how particle transport associated with morphogenesis is modulated by the gradual emergence of cilium posterior tilt. Our model of swimming makes use of force distributions within a body-conforming finite element framework, allowing the solution of nonlinear inertialess Carreau flow. We find that a three-sphere model swimmer and a model sperm are similarly affected by shear-thinning; in both cases swimming due to a prescribed beat is enhanced by shear-thinning, with optimal Deborah number around 0.8. The sperm exhibits an almost perfect linear relationship between velocity and the logarithm of the ratio of zero to infinite shear viscosity, with shear-thickening hindering cell progress.Comment: 20 pages, 24 figure

Deposit insurance: a reconsideration

This paper undertakes a simple general equilibrium analysis of the consequences of deposit insurance programs, the way in which they are priced and the way in which they fund revenue shortfalls. We show that the central issue is how the government will make up any FDIC losses. Under one scheme for making up the losses, we show that FDIC policy is irrelevant: it does not matter what premium is charged, nor does it matter how big FDIC losses are. Under another scheme, all that matters is the magnitude of the losses. And there is no presumption that small losses are “good.” We also show that multiple equilibria can be observed and Pareto ranked. Some economies may be “trapped” in equilibria with inefficient financial systems. Our analysis provides counterexamples to the following propositions. (1) Actuarially fair pricing of deposit insurance is always desirable. (2) Implicit FDIC subsidization of banks through deposit insurance is always undesirable. (3) “Large” FDIC losses are necessarily symptomatic of a poorly designed deposit insurance system.Deposit insurance

The correlation space of Gaussian latent tree models and model selection without fitting

We provide a complete description of possible covariance matrices consistent with a Gaussian latent tree model for any tree. We then present techniques for utilising these constraints to assess whether observed data is compatible with that Gaussian latent tree model. Our method does not require us first to fit such a tree. We demonstrate the usefulness of the inverse-Wishart distribution for performing preliminary assessments of tree-compatibility using semialgebraic constraints. Using results from Drton et al. (2008) we then provide the appropriate moments required for test statistics for assessing adherence to these equality constraints. These are shown to be effective even for small sample sizes and can be easily adjusted to test either the entire model or only certain macrostructures hypothesized within the tree. We illustrate our exploratory tetrad analysis using a linguistic application and our confirmatory tetrad analysis using a biological application.Comment: 15 page

Towards a Theory of Services Supply Chain Management

Much research has been performed to develop the supply chain management construct for manufacturing goods producing firms. However, the service sector continues to grow its dominance in the percentage of GDP in high, middle and low income countries, and with it, a corresponding growth in the percentage of purchasing spend across the globe. While research continues in the manufacturing supply chain arena, much work is yet to be done to understand the differences for services. The objectives of this research project were threefold: 1) to analyze the services supply chain management construct in order to determine how it differs from the more rigorously analyzed manufacturing supply chain management construct. The outcome is expected to be a fully developed and validated parsimonious measurement instrument for services supply chain management practices, 2) to validate a proposed framework relating the nature of the service, services supply chain management practices, information technology, operational performance and business performance. This framework, as developed, was built upon the relational view of the network and the resource based view of the firm, and 3) to propose a new topology for the services supply chain management construct. A survey instrument to capture the operational measures for the service\u27s supply chain management construct was developed based upon an extensive literature review of current supply chain management research, previously proposed service frameworks and service operations management research relevant to this topic. A rigorous instrument development process was conducted to ensure the final instrument meets all requirements to satisfy the criteria for unidimensionality, convergent, discriminant, and predictive validity. A cross-sectional mail survey focused towards service industry sourcing leaders within firms in the United States was completed. Structural Equation Modeling was utilized for developing the model, determining the strength of the hypotheses, and evaluat