Completeness, robustness, and safety in real-time software requirements specification

This paper presents an approach to providing a rigorous basis for ascertaining whether or not a given set of software requirements is internally complete, i.e., closed with respect to questions and inferences that can be made on the basis of information included in the specification. Emphasis is placed on aspects of software requirements specifications that previously have not been adequately handled, including timing abstractions, safety, and robustness

Void Scaling and Void Profiles in CDM Models

An analysis of voids using cosmological N-body simulations of cold dark matter models is presented. It employs a robust statistics of voids, that was recently applied to discriminate between data from the Las Campanas Redshift Survey and different cosmological models. Here we extend the analysis to 3D and show that typical void sizes D in the simulated galaxy samples obey a linear scaling relation with the mean galaxy separation lambda: D=D_0+nu*lambda. It has the same slope nu as in 2D, but with lower absolute void sizes. The scaling relation is able to discriminate between different cosmologies. For the best standard LCDM model, the slope of the scaling relation for voids in the dark matter halos is too steep as compared to the LCRS, with too small void sizes for well sampled data sets. The scaling relation of voids for dark matter halos with increasing mass thresholds is even steeper than that for samples of galaxy-mass halos where we sparse sample the data. This shows the stronger clustering of more massive halos. Further, we find a correlation of the void size to its central and environmental average density. While there is little sign of an evolution in samples of small DM halos with v_{circ} ~ 90 km/s, voids in halos with circular velocity over 200 km/s are larger at redshift z = 3 due to the smaller halo number density. The flow of dark matter from the underdense to overdense regions in an early established network of large scale structure is also imprinted in the evolution of the density profiles with a relative density decrease in void centers by 0.18 per redshift unit between z=3 and z=0.Comment: 12 pages, 9 eps figures, submitted to MNRA

Limits on Neutrino Radiative Decay from Sn1987a

We calculate limits on the properties of neutrinos using data from gamma-ray detectors on the Pioneer Venus Orbiter and Solar Max Mission satellites. A massive neutrino decaying in flight from the supernova would produce gamma rays detectable by these instruments. The lack of such a signal allows us to constrain the mass, radiative lifetime, and branching ratio to photons of a massive neutrino species produced in the supernova. Presented at Beyond The Standard Model III, June, 1992.Comment: 5 Pages, 2 Figures (avalable on request). LaTeX, WorldSci.st

Charmed Strange Pentaquarks in the Large NcN_c Limit

The properties of pentaquarks containing a heavy anti-quark and strange quarks are studied in the bound state picture. In the flavor SU(3) limit, there are many pentaquark states with the same binding energy. When the SU(3) symmetry breaking effects are included, however, three states become particularly stable due to a ``Gell-Mann--Okubo mechanism''. They are the $\bar Qsuud$ and $\bar Qsudd$ states discussed by Lipkin, and a a previously unstudied $\bar Qssud$ state. These states will have $J^P={1\over2}^+$ and their masses are estimated. These states, if exist, may be seen in experiments in the near future.Comment: 12 pages in REVTeX, no figure

The Meaning of Patent Citations: Report on the NBER/Case-Western Reserve Survey of Patentees

A survey of recent patentees was conducted to elicit their perceptions regarding the importance of their inventions, the extent of their communication with other inventors, and the relationship of both importance and communication to observed patent citations. A cohort of 1993 patentees were asked specifically about 2 patents that they had cited, and a third placebo' patent that was similar but which they did not cite. One of the two cited inventors was also surveyed. We find that inventors report significant communication, at least some of which is in forms that suggests spillovers from the cited inventor to the citing inventor. The perception of such communication was substantively and statistically significantly greater for the cited patents than for the placebos. There is, however, a large amount of noise in citations data; it appears that something like one-half of all citations do not correspond to any perceived communication, or even necessarily to a perceptible technological relationship between the inventions. We also find a significant correlation between the number of citations a patent received and its importance (both economic and technological) as perceived by the inventor.

Cosmological constraints from the X-ray gas mass fraction in relaxed lensing clusters observed with Chandra

We present precise measurements of the X-ray gas mass fraction for a sample of luminous, relatively relaxed clusters of galaxies observed with the Chandra Observatory, for which independent confirmation of the mass results is available from gravitational lensing studies. Parameterizing the total (luminous plus dark matter) mass profiles using the model of Navarro, Frenk & White (1997), we show that the X-ray gas mass fractions in the clusters asymptote towards an approximately constant value at a radius r_2500, where the mean interior density is 2500 times the critical density of the Universe at the redshifts of the clusters. Combining the Chandra results on the X-ray gas mass fraction and its apparent redshift dependence with recent measurements of the mean baryonic matter density in the Universe and the Hubble Constant determined from the Hubble Key Project, we obtain a tight constraint on the mean total matter density of the Universe, Omega_m = 0.30^{+0.04}_{-0.03}, and measure a positive cosmological constant, Omega_Lambda = 0.95^{+0.48}_{-0.72}. Our results are in good agreement with recent, independent findings based on analyses of anisotropies in the cosmic microwave background radiation, the properties of distant supernovae, and the large-scale distribution of galaxies.Comment: Accepted for publication in MNRAS Letters (6 pages, 3 figures

Applications of Wavelets to the Analysis of Cosmic Microwave Background Maps

We consider wavelets as a tool to perform a variety of tasks in the context of analyzing cosmic microwave background (CMB) maps. Using Spherical Haar Wavelets we define a position and angular-scale-dependent measure of power that can be used to assess the existence of spatial structure. We apply planar Daubechies wavelets for the identification and removal of points sources from small sections of sky maps. Our technique can successfully identify virtually all point sources which are above 3 sigma and more than 80% of those above 1 sigma. We discuss the trade-offs between the levels of correct and false detections. We denoise and compress a 100,000 pixel CMB map by a factor of about 10 in 5 seconds achieving a noise reduction of about 35%. In contrast to Wiener filtering the compression process is model independent and very fast. We discuss the usefulness of wavelets for power spectrum and cosmological parameter estimation. We conclude that at present wavelet functions are most suitable for identifying localized sources.Comment: 10 pages, 6 figures. Submitted to MNRA