The LAMAR: A high throughput X-ray astronomy facility for a moderate cost mission

The performance of a large area modular array of reflectors (LAMAR) is considered in several hypothetical observations relevant to: (1) cosmology, the X-ray background, and large scale structure of the universe; (2) clusters of galaxies and their evolution; (3) quasars and other active galactic nuclei; (4) compact objects in our galaxy; (5) stellar coronae; and (6) energy input to the interstellar medium

The methods café: An innovative idea for methods teaching at conference meetings

Interpretive research methods of various sorts have long been used to study "the political," but the full range of such methods is not widely known, and many are curious about what they entail. Others, who begin to use one or another of them, have questions about how to proceed. For those just learning about these methods, questions may be as basic as: "What does ethnomethodology mean?" "What is semiotic analysis?" "Are these approaches recognized as legitimate in political science?" Scholars engaging, or perhaps teaching, these methods might ask, e.g., "How do ethnographers overcome problems of accessing their field site, talking to strangers, and turning a year's worth of observational and interview notes into concise text?"

RHESSI and SOHO/CDS Observations of Explosive Chromospheric Evaporation

Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) onboard SOHO. For the first time, co-spatial imaging and spectroscopy have been used to observe explosive evaporation within a hard X-ray emitting region. RHESSI X-ray images and spectra were used to determine the flux of non-thermal electrons accelerated during the impulsive phase of an M2.2 flare. Assuming a thick-target model, the injected electron spectrum was found to have a spectral index of ~7.3, a low energy cut-off of ~20 keV, and a resulting flux of >4x10^10 ergs cm^-2 s^-1. The dynamic response of the atmosphere was determined using CDS spectra, finding a mean upflow velocity of 230+/-38 km s^-1 in Fe XIX (592.23A), and associated downflows of 36+/-16 km s^-1 and 43+/-22 km s^-1 at chromospheric and transition region temperatures, respectively, relative to an averaged quiet-Sun spectra. The errors represent a 1 sigma dispersion. The properties of the accelerated electron spectrum and the corresponding evaporative velocities were found to be consistent with the predictions of theory.Comment: 5 pages, 4 figures, ApJL (In Press

Random field Ising systems on a general hierarchical lattice: Rigorous inequalities

Random Ising systems on a general hierarchical lattice with both, random fields and random bonds, are considered. Rigorous inequalities between eigenvalues of the Jacobian renormalization matrix at the pure fixed point are obtained. These inequalities lead to upper bounds on the crossover exponents $\{\phi_i\}$.Comment: LaTeX, 13 pages, figs. 1a,1b,2. To be published in PR

Complete chaotic synchronization in mutually coupled time-delay systems

Complete chaotic synchronization of end lasers has been observed in a line of mutually coupled, time-delayed system of three lasers, with no direct communication between the end lasers. The present paper uses ideas from generalized synchronization to explain the complete synchronization in the presence of long coupling delays, applied to a model of mutually coupled semiconductor lasers in a line. These ideas significantly simplify the analysis by casting the stability in terms of the local dynamics of each laser. The variational equations near the synchronization manifold are analyzed, and used to derive the synchronization condition that is a function of the parameters. The results explain and predict the dependence of synchronization on various parameters, such as time-delays, strength of coupling and dissipation. The ideas can be applied to understand complete synchronization in other chaotic systems with coupling delays and no direct communication between synchronized sub-systems.Comment: 22 pages, 6 figure

Limits on the small scale structure of the diffuse cosmic X-rays

Autocorrelation functions for diffuse cosmic X ray

An interval logic for higher-level temporal reasoning

Prior work explored temporal logics, based on classical modal logics, as a framework for specifying and reasoning about concurrent programs, distributed systems, and communications protocols, and reported on efforts using temporal reasoning primitives to express very high level abstract requirements that a program or system is to satisfy. Based on experience with those primitives, this report describes an Interval Logic that is more suitable for expressing such higher level temporal properties. The report provides a formal semantics for the Interval Logic, and several examples of its use. A description of decision procedures for the logic is also included

Critical Behavior of the 3d Random Field Ising Model: Two-Exponent Scaling or First Order Phase Transition?

In extensive Monte Carlo simulations the phase transition of the random field Ising model in three dimensions is investigated. The values of the critical exponents are determined via finite size scaling. For a Gaussian distribution of the random fields it is found that the correlation length $\xi$ diverges with an exponent $\nu=1.1\pm0.2$ at the critical temperature and that $\chi\sim\xi^{2-\eta}$ with $\eta=0.50\pm0.05$ for the connected susceptibility and $\chi_{\rm dis}\sim\xi^{4-\bar{\eta}}$ with $\bar{\eta}=1.03\pm0.05$ for the disconnected susceptibility. Together with the amplitude ratio $A=\lim_{T\to T_c}\chi_{\rm dis}/\chi^2(h_r/T)^2$ being close to one this gives further support for a two exponent scaling scenario implying $\bar{\eta}=2\eta$. The magnetization behaves discontinuously at the transition, i.e. $\beta=0$, indicating a first order transition. However, no divergence for the specific heat and in particular no latent heat is found. Also the probability distribution of the magnetization does not show a multi-peak structure that is characteristic for the phase-coexistence at first order phase transition points.Comment: 14 pages, RevTeX, 11 postscript figures (fig9.ps and fig11.ps should be printed separately

Establishment of a mini-advanced technology development center

Issued as Quarterly reports no. [1-3] and Final report, Project no. L-30-802 (subproject is B-558/P.D. Loveless

Continuation of the mini-technology development center program in Barrow, Madison, and Jackson counties

Issued as Quarterly reports, nos. 1-3, and Final reports, nos. 1-2, Project no. L-30-812(subproject is B-562