Are brook trout streams in western Virginia and Shenandoah National Park recovering from acidification?

Streamwater composition data obtained through periodic sampling of streams that support brook trout (Salvelinus fontinalis) in the mountains of western Virginia were examined for evidence of recovery from acidification during the 1988-2001 period. Measurements of sulfate deposition in precipitation indicate that sulfate deposition in the region declined approximately 40% between 1985 and 2000. While no significant regional trends in acid-base constituents were observed for the set (n = 65) of western Virginia study streams, significant regional trends were observed for a subset (n = 14) of streams in Shenandoah National Park (SNP). For the subset of SNP streams, the median increase in acid-neutralizing capacity (ANC) was 0.168 microequiv L(-1) year(-1) and the median decrease in sulfate concentration was -0.229 microequiv L(-1) year(-1). Although these trends are consistent with recovery from acidification, the degree of apparent recovery is small compared to estimates of historic acidification in SNP streams and much less than observed in other, more northern regions in the United States. Correlation between sulfate concentration trends and current sulfate concentrations in streamwater suggests that recovery from stream acidification in the western Virginia region is determined by sulfur retention processes in watershed soils. A transient increase in nitrate concentrations that occurred among some western Virginia streams following forest defoliation by the gypsy moth (Lymantria dispar) complicates interpretation of the observed patterns of change in acid-base status.     

Regional patterns of affirmative action compliance costs

In this paper we estimate the amount by which firms' labor costs are increased by compliance with affirmative action regulations imposed on federal contractors for 160 SMSAs in 1980. The paper focuses on determining the cause(s) for variation in these compliance costs across SMSAs and in identifying areas of high and low compliance cost. We find that compliance costs are lower in larger SMSAs, more rapidly growing SMSAs, and SMSAs that have relatively large proportions of minorities and females in the labor market.The authors would like to thank Fred Wildes and Long Gen Ying, both of San Diego State University, for their assistance on this project. In addition, support for Prof. Getis' work was provided by the National Science Foundation, Grant No. SES-9123832.This paper was presented at the annual conference of the Western Regional Science Association in Tucson, Arizona.     

Processing speed, working memory, and IQ: A developmental model of cognitive deficits following cranial radiation therapy.

IQ decrements following cranial radiation therapy (CRT) for acute lymphoblastic leukemia (ALL) are most apparent years after treatment. The authors examined a developmental model for delayed deficits by evaluating the relationship between processing speed, working memory, and IQ in long-term survivors of childhood ALL (n?=?27) compared with demographically matched controls (n?≠??7). The ALL group treated with CRT showed deficits in IQ, working memory, and processing speed relative to controls. Differences in IQ between the CRT group and controls were mediated by differences in working memory. Processing speed did not fully account for the working memory deficit in the CRT group. Participants with ALL treated only with chemotherapy showed similar working memory and processing speed as matched controls. Data suggest that deficits in processing speed and working memory following CRT may underlie declines in IQ. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Zippering: Managing intermittent connectivity in DIANA

This paper describes an approach for handling intermittent connectivity between mobile clients and networkresident applications, which we call zippering. When the client connects with the application, communication between the client and the application is synchronous. When the client intermittently connects with the application, communication becomes asynchronous. The DIANA (DeviceIndependent, Asynchronous Network Access) approach allows the client to perform a variety of operations while disconnected. Finally, when the client reconnects with the application, the operations performed independently on the client are replayed to the application in the order they were originally done. Zippering allows the user at the client to fix errors detected during reconciliation and continues the transaction gracefully instead of aborting the whole transaction when errors are detected.     

Team task analysis: identifying tasks and jobs that are team based

This paper presents initial information on the development and validation of three team task analysis scales. These scales were designed to quantitatively assess the extent to which a group of tasks or a job is team based. During a 2-week period, 52 male students working in 4-person teams were trained to perform a complex highly interdependent computer-simulated combat mission consisting of both individual- and team-based tasks. Our results indicated that the scales demonstrated high levels of interrater agreement. In addition, the scales differentiated between tasks that were predetermined to be individual versus team based. Finally, the results indicated that job-level ratings of team workflow were more strongly related to team performance than were aggregated task-level ratings of team-relatedness or team workflow. These results suggest that the scales presented here are an effective means of quantifying the extent to which tasks or jobs are team based. A research and practical implication of our findings is that the team task analysis scales could serve as criterion measures in the evaluation of team training interventions or predictors of team performance.     

Structured writing about stressful events: Exploring potential psychological mediators of positive health effects.

In a previous study, the authors found that structured writing about stressful events improved symptomatology in 112 patients with rheumatoid arthritis and asthma relative to patients who did not write (J. Smyth, A. Stone, A. Hurewitz, & A. Kaell, 1999). However, little is currently known about the pathways from the intervention to alterations in outcomes. In addition to measuring symptom outcomes after the intervention in the previous study, the authors monitored perceived stress, quality of sleep, affect, substance use, and medication use on a momentary basis for the 7 days prior to writing, during the 3 intervention days, and for the 14 days following the intervention (N?=?105). These variables were tested in a secondary data analysis to determine whether they mediated the effects observed in the J. Smyth, A. Stone, et al. study. No evidence was found supporting mediation, and the mechanism underlying structured writing about stressful events remains unknown. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactions of fuel-nitrogen compounds under conditions of inert pyrolysis

As part of a study of the chemical mechanisms involved in the conversion of fuel-nitrogen compounds to nitric oxide during combustion, fossil fuels and model nitrogen compounds were pyrolysed in helium in a small quartz flow reactor. Hydrogen cyanide was the major nitrogen-containing product obtained in all cases indicating that hydrogen cyanide is formed during the initial pre-flame stages of combustion and is the principal intermediate in the formation of fuel nitric oxide. At a nominal residence time of one second, 50% decomposition of pyrrole, quinoline, benzonitrile and pyridine occurs at 905, 910, 922 and 954 °C, respectively. The fraction of the nitrogen in pyridine that is converted to hydrogen cyanide increases from 40% at 960 °C to 100% at 1100 °C. Benzonitrile produces similar amounts of hydrogen cyanide (49 and 82%). The hydrogen cyanide yields from coals and residual fuel oils increase from the range of 15–25% at 950 °C to 23–42% at 1100 °C. It is not possible to determine from these single-stage experiments if most of the hydrogen cyanide forms in the primary pyrolysis process or in secondary reactions.     

A Note on EMP Safety Hazards

The character of transient electric fields induced in spherical homogeneous tissue models of man and animals by incident electromagnetic fields similar to that originating from lightning and EMP generators has been theoretically determined. The magnitude of the induced fields is found to be approximately proportional to the time rate of change of the incident field and independent of the pulsewidth. It was also found that maximum EMP induced field in spherical shaped bodies is nearly proportional to the radius of the body. Therefore, for EMP safety standards, more consideration should be given to the time rate of change of the incident field rather than to the pulsewidth, and when laboratory animal data are used as a guide they should be extrapolated to account for body size.     

Evolution of the oxide structure of 9CrODS steel exposed to supercritical water

The corrosion behavior and oxide structure of 9CrODS steel in supercritical water has been studied. Samples were exposed to supercritical water at 500 and 600 °C for times of 2, 4 and 6 weeks. The oxide structure was studied using microbeam synchrotron X-ray diffraction and fluorescence analysis. The 600 °C samples exhibited a three-layer structure with Fe₃O₄ in the outer layer, a mixture of FeCr₂O₄ and Fe₃O₄ in the inner layer, and a mixture of metal and oxide grains (FeCr₂O₄ and Cr₂O₃) in the diffusion layer. Between the 2 and 4-week samples exposed to 600 °C supercritical water, a Cr₂O₃ film appeared at the diffusion layer-metal interface which appears to be associated with slower oxidation of the metal. The 500 °C samples also showed a three-layer structure, but both the outer and inner oxide layers contained mainly Fe₃O₄, and the diffusion layer contained much fewer oxide precipitates and was a solid solution of oxygen ahead of the oxide front.