The X-ray Spectrum of Soft Gamma Repeater 1806-20

Soft Gamma Repeaters (SGRs) are a class of rare, high-energy galactic transients that have episodes of short (~0.1 sec), soft (~30 keV), intense (~100 Crab), gamma-ray bursts. We report an analysis of the x-ray emission from 95 SGR1806-20 events observed by the International Cometary Explorer. The spectral shape remains remarkably constant for bursts that differ in intensity by a range of 50. Below 15 keV the number spectrum falls off rapidly such that we can estimate the total intensity of the events. Assuming that SGR1806-20 is associated with the supernova remnant G10.0-0.3 (Kulkarni and Frail, Murakami \etal), the brightest events had a total luminosity of ~1.8 x 10^42 erg sec^-1, a factor of 2 x 10^4 above the Eddington limit. A third of the emission was above 30 keV. There are at least three processes that are consistent with the spectral rollover below 15 keV. (1)The rollover is consistent with some forms of self absorption. Typical thermal temperatures are ~20 keV and require an emitting surface with a radius between 10 and 50 km. The lack of spectral variability implies that only the size of the emitting surface varies between events. If the process is thermal synchrotron the required magnetic field might be too small to confine the plasma against the super Eddington flux. (2)The low energy rollover could be due to photoelectric absorption by ~10^24 Hydrogen atoms cm^-2 of neutral material with a cosmic abundance assuming a continuum similar to TB with T= ~22 keV. (3) Emission in the two lowest harmonics from a 1.3 x 10^12 Gauss field would appear as Doppler broadened lines and fall off rapidly below 15 keV.Comment: TeX: 32 pg+ 8 appended postscript figures, in press ApJ(9/94

Risk mitigation decisions for it security

Enterprises must manage their information risk as part of their larger operational risk management program. Managers must choose how to control for such information risk. This article defines the flow risk reduction problem and presents a formal model using a workflow framework. Three different control placement methods are introduced to solve the problem, and a comparative analysis is presented using a robust test set of 162 simulations. One year of simulated attacks is used to validate the quality of the solutions. We find that the math programming control placement method yields substantial improvements in terms of risk reduction and risk reduction on investment when compared to heuristics that would typically be used by managers to solve the problem. The contribution of this research is to provide managers with methods to substantially reduce information and security risks, while obtaining significantly better returns on their security investments. By using a workflow approach to control placement, which guides the manager to examine the entire infrastructure in a holistic manner, this research is unique in that it enables information risk to be examined strategically. © 2014 ACM

Constraints on the Gamma-ray Burst Luminosity Function from PVO and BATSE

We examine the width of the gamma-ray burst luminosity function through the distribution of GRB peak fluxes as detected by the Pioneer Venus Orbiter (PVO) and the Burst and Transient Source Experiment (BATSE). The strength of the analysis is greatly enhanced by using a merged catalog of peak fluxes from both instruments with good cross-calibration of their sensitivities. The range of peak fluxes is increased by approximately a factor of 20 relative to the BATSE catalog. Thus, more sensitive investigations of the $\log N-\log P$ distribution are possible. We place constraints on the width of the luminosity function of gamma-ray bursts brighter than the BATSE completeness limit by comparing the intensity distribution in the merged catalog with those produced by a variety of spatial density and luminosity functions. For the models examined, $90\%$ of the {\em detectable\/} bursts have peak luminosities within a range of 10, indicating that the peak luminosities of gamma-ray bursts span a markedly less wide range of values than many other of their measurable properties. We also discuss for which slopes of a power-law luminosity function the observed width is at the upper end of the constrained range. This is important in determining the power-law slopes for which luminosity-duration correlations could be important.Comment: 10 pages latex + 2 uuencoded figures; APJL accepte

Cultivating the Librarian Within: Effectively lntegrating Library lnstruction into Freshman Composition

It has become common practice for library instruction to be included in lower-level college composition courses. Students are typically required to visit the library once or twice a semester to receive instruction on how to find books and journal articles for an upcoming writing assignment that incorporates formal research. But does this current model of instruction truly address course outcomes that seek to produce students who are information literate, critical thinkers and life-long learners? Faculty who teach such courses are often reluctant to surrender precious class time to a librarian, but this paper argues that the merging of bibliographic instruction with composition curriculum can more effectively tackle course goals with minimal interruption to the class schedule. The aim of this paper is to challenge the conventional relationship between library instruction and lower-level composition courses by assessing and discussing the implementation of a new freshman writing course that fully integrates library instruction into the course and into the classroom

Representation in State Legislatures: A Focus on Missouri

In Summer 2003, the Institute of Public Policy conducted a mail survey of state legislators in Arizona, Colorado, Missouri, New Jersey, North Dakota, Pennsylvania, South Carolina, and South Dakota. We found that the number of requests for casework a legislative office receives in an average week during session varied greatly by state. Pennsylvania reported 107 cases on average, which was more than four times that of any other state (North Dakota, 24; South Carolina, 17; Arizona, 16; Missouri, 15; New Jersey, 12; South Dakota, 8; and Colorado, 7).Includes bibliographical reference

Alternative Energy Choices, Conservation, and Management: A Primer for Advanced Manufacturing Managers

Manufacturing managers need to understand the interrelated links between advanced manufacturing technology, primary and alternative energy choices, energy output values and costs, and energy conservation over the life of a project. Through an overview of these topics and the manager’s energy conservation processing optimization model developed in this paper, manufacturing managers, engineering technologists, and academics gain greater insight to the impacts of energy technologies upon manufacturing activities