Mitigation of Electrostatic Hazards on Spacecraft

Spacecraft are complex systems operating in challenging environments that require customized testing procedures designed to mitigate the unique hazards of a space launch environment. As an example of those testing procedures, we describe the test methodology and recommendations developed to mitigate electrostatic discharges that could have triggered an explosion of the Space Shuttle during launch, return to launch site, abort after one orbit, or during normal landing

Development and evaluation of predictive models for measuring the biological integrity of streams

The ratio of the number of observed taxa to that expected to occur in the absence of human-caused stress (OIE) is an intuitive and ecologically meaningful measure of biological integrity. We examined how OIE ratios derived from stream invertebrate data varied among 234 unimpaired reference sites and 254 test sites potentially impaired by past logging. Data were collected from streams in three montane ecoregions in California. Two sets of River Invertebrate Prediction and Classification System (RIVPACS) predictive models were built: one set of models was based on near-species taxonomic resolution; the other was based on family identifications. Two models were built for each level of taxonomic resolution: one calculated 0 and E based on all taxa with probabilities of capture (PC) \u3e 0; the other calculated 0 and E based on only those taxa with PC2 0.5. Evaluations of the performance of each model were based on three criteria: (1) how well models predicted the taxa found at unimpaired sites, (2) the degree to which OIE values differed among unimpaired reference sites and potentially impaired test sites, and (3) the degree to which test site OIE values were correlated with independent measures of watershed alteration. Predictions of species models were more accurate than those of family models, and predictions of the PC2 0.5 species model were more robust than predictions of the PC2 0 model. OIE values derived from both species models were related to land use variables, but only assessments based on the PC2 0.5 model were insensitive to naturally occurring differences among streams, ecoregions, and year

What tweets tell us about MOOC participation

In this research paper, the authors analyze the collected Twitter data output during MobiMOOC 2011. This six-week data stream includes all tweets that contain the MOOC's hashtag (#mobiMOOC) and it has been analyzed using qualitative methodology. The analysis sought to examine the emotive vocabulary used, to determine if there was content-sharing via tweets, and to analyze the folksonomic trends of the tweets. In Addition sought a deeper understanding of what, and how, MOOC participants share what they share on the MOOC's Twitter channel. The aim of this study is to provide a little more insight into MOOC learner behaviors on Twitter so that future MOOC designers and facilitators can better engage with their learners.Facultad de Ciencias Exacta

Dust Removal Technolgy for a Mars In Situ Resource Utilization System

Several In Situ Resource Utilization (lSRU) systems being considered to enable future manned exploration of Mars require capture of Martian atmospheric gas to extract oxygen and other commodities. However, the Martian atmosphere contains relatively large amounts of dust which must be removed in tbe collection systems of the ISRU chambers. The amount of atmospheric dust varies largely with the presence of daily dust devils and the less frequent but much more powerful global dust storms. A common and mature dust removal technology for terrestrial systems is the electrostatic precipitator. With this technology, dust particles being captured are imparted an electrostatic charge by means of a corona discharge. Charged dust particles are then driven to a region of high electric field which forces the particles onto a collector for capture. Several difficulties appear when this technology is adapted to the Martian atmospheric environment At the low atmospheric pressure of Mars, electrical breakdown occurs at much lower voltages than on Earth and corona discharge is difficult to sustain. In this paper, we report on our efforts to obtain a steady corona/glow discharge in a simulated Martian atmosphere of carbon dioxide at 9 millibars of pressure. We also present results on the design of a dust capture system under these atmospheric conditions

Structural, item, and test generalizability of the psychopathology checklist - revised to offenders with intellectual disabilities

The Psychopathy Checklist–Revised (PCL-R) is the most widely used measure of psychopathy in forensic clinical practice, but the generalizability of the measure to offenders with intellectual disabilities (ID) has not been clearly established. This study examined the structural equivalence and scalar equivalence of the PCL-R in a sample of 185 male offenders with ID in forensic mental health settings, as compared with a sample of 1,212 male prisoners without ID. Three models of the PCL-R’s factor structure were evaluated with confirmatory factor analysis. The 3-factor hierarchical model of psychopathy was found to be a good fit to the ID PCL-R data, whereas neither the 4-factor model nor the traditional 2-factor model fitted. There were no cross-group differences in the factor structure, providing evidence of structural equivalence. However, item response theory analyses indicated metric differences in the ratings of psychopathy symptoms between the ID group and the comparison prisoner group. This finding has potential implications for the interpretation of PCL-R scores obtained with people with ID in forensic psychiatric settings

"A different world" exploring and understanding the climate of a recently re-rolled sexual offender prison

Understanding how sexual offenders experience prison and its environment is important because such experiences can impact on rehabilitation outcomes. The purpose of this research investigation was to explore the rehabilitative and therapeutic climate of a recently re-rolled sexual offender prison. The research took a mixed methods approach and consisted of quantitative and qualitative phases. There were differences between prisoners and staff on their perception of the prison climate and for prisoner and staff relationships. The qualitative results helped to explain the quantitative findings and added a more nuanced understanding of the experience of the prison, the nature of prisoner and staff relationships and the opportunities for personal growth within the prison. The study has important implications for prisons that co-locate sexual offenders and want to provide an environment conducive to rehabilitation