The effects of high energy particles on planetary missions

Researchers review the background and motivation for the detailed study of the variability and uncertainty of the particle environment from a space systems planning perspective. The engineering concern raised by each environment is emphasized rather than the underlying physics of the magnetosphere or the sun. Missions now being planned span the short term range of one to three years to periods over ten years. Thus the engineering interest is beginning to stretch over periods of several solar cycles. Coincidentally, detailed measurements of the environment are now becoming available over that period of time. Both short term and long term environmental predictions are needed for proper mission planning. Short term predictions, perhaps based on solar indices, real time observations, or short term systematics, are very useful in near term planning -- launches, EVAs (extravehicular activities), coordinated observations, and experiments which require the magnetosphere to be in a certain state. Long term predictions of both average and extreme conditions are essential to mission design. Engineering considerations are many times driven by the worst case environment. Knowledge of the average conditions and their variability allows trade-off studies to be made, implementation of designs which degrade gracefully under multi-stress environments

Historic Cemeteries as Contested Grounds

The author comments on the articles This Church is for the Livinig : An Assessment of Archaeological Standards for the Removal of Cemeteries in Rhode Island and Massachusetts by James Garman and Where Angels Fear to Tread : Cemetery Preservation Efforts by the Massachusetts Historical Commission by Edward Bell

Long-Term Optical Observations Of Two Lmxbs: Uw Crb (=Ms 1603+260) And V1408 Aql (=4U 1957+115)

We present new optical photometry of two low-mass X-ray binary stars, UW CrB (MS 1603+260) and V1408 Aql (4U 1957+115). UW CrB is an eclipsing binary and we refine its eclipse ephemeris and measure an upper limit to the rate of change of its orbital period, vertical bar P vertical bar < 4.2 x 10(-11) (unitless). The light curve of UW CrB shows optical counterparts of type I X-ray bursts. We tabulate the times, orbital phases, and fluences of 33 bursts and show that the optical flux in the bursts comes primarily from the accretion disk, not from the secondary star. The new observations are consistent with a model in which the accretion disk in UW CrB is asymmetric and precesses in the prograde direction with a period of similar to 5.5 days. The light curve of V1408 Aql has a low-amplitude modulation at its 9.33 hr orbital period. The modulation remained a nearly pure sine curve in the new data as it was in 1984 and 2008, but its mean amplitude was lower, 18% against 23% in the earlier data. A model in which the orbital modulation is caused by the varying aspect of the heated face of the secondary star continues to give an excellent fit to the light curve. We derive a much improved orbital ephemeris for the system.NSF 0958783Astronom

Market Reactions To Company Layoffs: Evidence On The Financial Distress Versus Potential Benefit Hypothesis And The Effect Of Predisclosure Information

The current study extends theory developed by Malatesta and Thompson (1985) to the area of corporate downsizing, and finds that the magnitude of the stock price reaction to announcements of corporate layoffs is a function of two factors, (1) the economic impact of the announced layoff, and, (2) the degree to which the announcement and signal about the underlying conditions related to the announcement have been anticipated by investors and incorporated previously into the stock price (predisclosure information).&nbsp;For firms experiencing a negative overall stock price reaction at the date of a layoff announcement, the larger the layoff (proxy for economic impact), the more negative the stock price reaction.&nbsp; Also for these firms, the smaller the firm size (proxy for the level of predisclosure information), the more negative the stock price reaction. This provides evidence that for some firms, the financial distress effect dominates, and the market incorporates previously unknown negative information into the stock price, which results in the negative stock price reaction.&nbsp; For these firms, the larger the impact and the less the event is anticipated, the more negative is the stock price reaction.&nbsp;For firms experiencing a positive overall stock price reaction at the date of a layoff announcement, the larger the layoff (proxy for economic impact), the more positive the stock price reaction.&nbsp; Also for these firms, the smaller the firm size (proxy for level of predisclosure information), the more positive the stock price reaction. This provides evidence that for some firms, the potential benefit effect dominates.&nbsp; The market has previously incorporated negative information associated with the conditions leading up the layoff, and is now incorporating positive information about the benefits to be achieved by the layoff, which results in the positive stock price reaction.&nbsp; For these firms, the larger the impact and the less the event is anticipated, the more positive is the stock price reaction.&nbsp;In this study, hypotheses are developed which combine the effects of both economic impact and predisclosure information with the financial distress and potential benefit hypotheses developed in prior research in corporate downsizing.&nbsp; Instead of offering the these two hypotheses as competing and mutually exclusive, evidence is provided that supports the conclusion that these hypotheses simultaneously explain concurrent and additive effects on the stock price reaction to announcements of company layoffs.&nbsp; Finally, results indicate that the relationship between economic impact, predisclosure information and stock price reaction to layoff announcements depends on the relative dominance of the signals provided by the layoff about both financial distress and potential benefit

A creep model for metallic composites based on matrix testing: Application to Kanthal composites

An anisotropic creep model is formulated for metallic composites with strong fibers and low to moderate fiber volume percent (less than 40 percent). The idealization admits no creep in the local fiber direction and assumes equal creep strength in longitudinal and transverse shear. Identification of the matrix behavior with that of the isotropic limit of the theory permits characterization of the composite through uniaxial creep tests on the matrix material. Constant and step-wise creep tests are required as a data base. The model provides an upper bound on the transverse creep strength of a composite having strong fibers embedded in a particular matrix material. Comparison of the measured transverse strength with the upper bound gives an assessment of the integrity of the composite. Application is made to a Kanthal composite, a model high-temperature composite system. Predictions are made of the creep response of fiber reinforced Kanthal tubes under interior pressure

The Second Annual International Space University Alumni Conference

The papers presented at the conference reflect the multidisciplinary nature of the International Space University (ISU) and its alumni. The first papers presented hold special relevance to the design projects, and cover such topics as lunar-based astronomical instrumentation, solar lunar power generation, habitation on the moon, and the legal issues governing multinational astronauts conducting research in space. The next set of papers cover various technical issues such as project success assessment, satellite networks and space station dynamics, thus reflecting the diverse backgrounds of the ISU alumni

Toward a descriptive model of galactic cosmic rays in the heliosphere

Researchers review the elements that enter into phenomenological models of the composition, energy spectra, and the spatial and temporal variations of galactic cosmic rays, including the so-called anomalous cosmic ray component. Starting from an existing model, designed to describe the behavior of cosmic rays in the near-Earth environment, researchers suggest possible updates and improvements to this model, and then propose a quantitative approach for extending such a model into other regions of the heliosphere