Property Insurance for Ohio\u27s Urban Areas

Thirty-eight million dollars damage to property occurred in Watts in 1965, $49,000,000 in Detroit, and$10,000,000 in Newark, New Jersey in 1967, plus many others that have resulted in about $187,000,000 being paid in the five years ending in 1968. Until Watts, riot coverage was provided as an afterthought by the insurance industry with little or no additional charge. Besides this problem, insurers were faced with loss of reinsurance by foreign reinsurers alarmed by inability of Government authorities to maintain law and order

Property Insurance for Ohio\u27s Urban Areas

Thirty-eight million dollars damage to property occurred in Watts in 1965, $49,000,000 in Detroit, and$10,000,000 in Newark, New Jersey in 1967, plus many others that have resulted in about $187,000,000 being paid in the five years ending in 1968. Until Watts, riot coverage was provided as an afterthought by the insurance industry with little or no additional charge. Besides this problem, insurers were faced with loss of reinsurance by foreign reinsurers alarmed by inability of Government authorities to maintain law and order

Logarithmic corrections in the free energy of monomer-dimer model on plane lattices with free boundaries

Using exact computations we study the classical hard-core monomer-dimer models on m x n plane lattice strips with free boundaries. For an arbitrary number v of monomers (or vacancies), we found a logarithmic correction term in the finite-size correction of the free energy. The coefficient of the logarithmic correction term depends on the number of monomers present (v) and the parity of the width n of the lattice strip: the coefficient equals to v when n is odd, and v/2 when n is even. The results are generalizations of the previous results for a single monomer in an otherwise fully packed lattice of dimers.Comment: 4 pages, 2 figure

Discovery of 15-second oscillations in Hubble Space Telescope observations of WZ Sagittae following the 2001 outburst

We report the discovery of 15-s oscillations in ultraviolet observations of WZ Sge obtained with the Hubble Space Telescope approximately one month after the peak of the 2001 outburst. This is the earliest detection of oscillations in WZ Sge following an outburst and the first time that a signal near 15 s has been seen to be dominant. The oscillations are quite strong (amplitude about 5%), but not particularly coherent. In one instance, the oscillation period changed by 0.7 s between successive observations separated by less than 1 hour. We have also found evidence for weaker signals with periods near 6.5 s in some of our data. We discuss the implications of our results for the models that have been proposed to account for the 28-s oscillations seen in quiescence. If the periods of the 15-s oscillations can be identified with the periods of revolution of material rotating about the white dwarf, the mass of the white dwarf must satisfy M_WD > 0.71 M_sun. The corresponding limit for the 6.5-s signals is M_WD > 1.03 M_sun.Comment: accepted for publication in ApJ Letters; 13 pages, 4 postscript figures; new version corrects a few typos and matches version that will appear in ApJ

Spanning Trees on Lattices and Integration Identities

For a lattice $\Lambda$ with $n$ vertices and dimension $d$ equal or higher than two, the number of spanning trees $N_{ST}(\Lambda)$ grows asymptotically as $\exp(n z_\Lambda)$ in the thermodynamic limit. We present exact integral expressions for the asymptotic growth constant $z_\Lambda$ for spanning trees on several lattices. By taking different unit cells in the calculation, many integration identities can be obtained. We also give $z_{\Lambda (p)}$ on the homeomorphic expansion of $k$-regular lattices with $p$ vertices inserted on each edge.Comment: 15 pages, 3 figures, 1 tabl

What is the probability of connecting two points ?

The two-terminal reliability, known as the pair connectedness or connectivity function in percolation theory, may actually be expressed as a product of transfer matrices in which the probability of operation of each link and site is exactly taken into account. When link and site probabilities are $p$ and $\rho$, it obeys an asymptotic power-law behavior, for which the scaling factor is the transfer matrix's eigenvalue of largest modulus. The location of the complex zeros of the two-terminal reliability polynomial exhibits structural transitions as $0 \leq \rho \leq 1$.Comment: a few critical polynomials are at the end of the .tex source fil

A Tool for Developing Correct Programs by Refinement

This report reviews the requirements for tool support of refinement, and reports on the design and implementation of a new tool to support refinement based on these requirements. The main features of the new tool are close integration of refinement and proof in a single tool, good management of the refinement context, an extensible theory base that allows the tool to be adapted to new application domains, and a flexible user interface

Identification of a nearby stellar association in the Hipparcos catalog: implications for recent, local star formation

The TW Hydrae Association (~55 pc from Earth) is the nearest known region of recent star formation. Based primarily on the Hipparcos catalog, we have now identified a group of 9 or 10 co-moving star systems at a common distance (~45 pc) from Earth that appear to comprise another, somewhat older, association (``the Tucanae Association''). Together with ages and motions recently determined for some nearby field stars, the existence of the Tucanae and TW Hydrae Associations suggests that the Sun is now close to a region that was the site of substantial star formation only 10-40 million years ago. The TW Hydrae Association represents a final chapter in the local star formation history.Comment: 5 pages incl figs and table

Some Exact Results on the Potts Model Partition Function in a Magnetic Field

We consider the Potts model in a magnetic field on an arbitrary graph $G$. Using a formula of F. Y. Wu for the partition function $Z$ of this model as a sum over spanning subgraphs of $G$, we prove some properties of $Z$ concerning factorization, monotonicity, and zeros. A generalization of the Tutte polynomial is presented that corresponds to this partition function. In this context we formulate and discuss two weighted graph-coloring problems. We also give a general structural result for $Z$ for cyclic strip graphs.Comment: 5 pages, late

Error Avoiding Quantum Codes and Dynamical Stabilization of Grover's Algorithm

An error avoiding quantum code is presented which is capable of stabilizing Grover's quantum search algorithm against a particular class of coherent errors. This error avoiding code consists of states only which are factorizable in the computational basis. Furthermore, its redundancy is smaller than the one which is achievable with a general error correcting quantum code saturating the quantum Hamming bound. The fact that this code consists of factorizable states only may offer advantages for the implementation of quantum gates in the error free subspace