Performance of an ablator for Space Shuttle inorbit repair in an arc-plasma airstream

An ablator patch material performed well in an arc plasma environment simulating nominal Earth entry conditions for the Space Shuttle. Ablation tests using vacuum molded cones provided data to optimize the formulation of a two part polymer system for application under space conditions. The blunt cones were made using a Teflon mold and a state of the art caulking gun. Char stability of formulations with various amounts of catalyst and diluent were investigated. The char was found to be unstable in formulations with low amounts of catalyst and high amounts of diluent. The best polymer system determined by these tests was evaluated using a half tile patch in a multiple High Temperature Reusable surface Insulation tile model. It was demonstrated that this ablator could be applied in a space environment using a state of the art caulking gun, would maintain the outer mold line of the thermal protection system during entry, and would keep the bond line temperature at the aluminum tile interface below the design limit

Circulating micrornas associated with glycemic impairment and progression in Asian Indians.

Aims/hypothesisAsian Indians have a high incidence of type 2 diabetes, but factors associated with glycemic progression in this population are not understood. MicroRNAs are emerging as important mediators of glucose homeostasis and have not been previously studied in Asian Indians. We examined microRNA (miR) expression associated with glycemic impairment and progression in Asian Indians from the San Francisco Bay Area. We studied 128 Asian Indians age 45-84 years without known cardiovascular disease and not taking diabetes medications. Oral glucose tolerance tests were performed at baseline and after 2.5 years. We quantified circulating miRs from plasma collected during the enrollment visit using a flow cytometry-based assay.ResultsGlycemic impairment was present in 57 % (n = 73) at baseline. MiR-191 was positively associated with glycemic impairment (odds ratio (OR) 1.7 (95 % CI 1.2, 2.4), p < 0.01). The prevalence of glycemic progression after 2.5 years was 24 % (n = 23). Six miRs were negatively associated with glycemic progression: miR-122 (OR 0.5 (0.2, 0.8), p < 0.01), miR-15a (OR 0.6 (0.4, 0.9), p < 0.01), miR-197 (OR 0.6 (0.4, 0.9), p < 0.01), miR-320a (OR 0.6 (0.4, 0.9), p < 0.01), miR-423 (OR 0.6 (0.4, 0.9), p < 0.01), and miR-486 (OR 0.5 (0.3, 0.8), p < 0.01). Further multivariate adjustment did not attenuate these results.Conclusions/interpretationThis is the first study to investigate circulating miRs associated with glycemic status among this high-risk ethnic group. Individual miRs were significantly associated with both glycemic impairment and glycemic progression. Further studies are needed to determine whether miR (s) might be useful clinical biomarkers for incident T2D in the Asian Indian population

Early environmental field research career exploration: An analysis of impacts on precollege apprentices

Research apprenticeships offer opportunities for deep understanding of scientific practice, transparency about research careers, and possible transformational effects on precollege youth. We examined two consecutive field-based environmental biology apprenticeship programs designed to deliver realistic career exploration and connections to research scientists. The Shaw Institute for Field Training (SIFT) program combines introductory field-skills training with research assistance opportunities, and the subsequent Tyson Environmental Research Fellowships (TERF) program provides immersive internships on university field station–based research teams. In a longitudinal mixed-methods study grounded in social cognitive career theory, changes in youth perspectives were measured during program progression from 10th grade through college, evaluating the efficacy of encouraging career path entry. Results indicate SIFT provided self-knowledge and career perspectives more aligned with reality. During SIFT, differences were found between SIFT-only participants compared with those who progressed to TERF. Transition from educational activities to fieldwork with scientists was a pivotal moment at which data showed decreased or increased interest and confidence. Continuation to TERF provided deeper relationships with role models who gave essential early-career support. Our study indicates the two-stage apprenticeship structure influenced persistence in pursuit of an environmental research career pathway. Recommendations for other precollege environmental career–exploration programs are presented

Factors that contribute to the progress of high school students in a college distance education course

This dissertation examined the factors that contributed to the high school students\u27 progress in a college-level, distance education course. Four high school students, two seniors and two juniors, were selected to participate in the study. They were simultaneously enrolled in high school and the college distance education course. The researcher in the study was also the instructor. Her lectures were presented to the students via prerecorded videotapes. The college course involved the use of three distance education technologies: video-based instruction, email, and the World Wide Web; A qualitative methodology using a multiple case study design was used in this study. The students were observed in two settings, the high school and the college campus. Data were collected for 15 weeks from January 1999 to May 1999 from multiple sources including field notes, classroom observations, student interviews, email messages, student test scores, and attendance records. A cross-case analysis identified several themes that were common across the four individual cases; Factors such as instructor support, facilitator support, and college support were factors that contributed to the students\u27 ability to complete the course. In addition, the use of video instruction offered flexibility, which enabled the students to pace their learning. Insufficient access to technology in the high school setting, outside influences such as employment, parenting, and social commitments, length of video lectures, and inconsistent course materials were factors that negatively contributed the students\u27 progress. In addition, various instructional strategies were identified for educators to use with high school students enrolled in courses that incorporate video-based instruction

An Essay Concerning Some Problems with the Constitutional-Doubt Canon

The constitutional-doubt canon instructs that statutes should be interpreted in a way that avoids placing their constitutionality in doubt. This canon is often said to rest on the presumption that Congress does not intend to exceed its constitutional authority. That presumption, however, is inconsistent with the notion that government actors tend to exceed their lawful authority—a notion that motivates our constitutional structure, and in particular the series of checks and balances that the Constitution creates. This tension between the constitutional- doubt canon and the Constitution’s structure would be acceptable if the canon accurately reflected the manner in which the public understands legislative enactments. But it doesn’t. Thus, the only possible justification for the constitutional-doubt canon is stare decisis

The Pseudophosphatase MK-STYX Induces Neuronal Differentiation in PC12 Cells

MK-STYX [MAPK (mitogen-activated protein kinase) phosphoserine/threonine/ tyrosine binding protein] is a pseudophosphatase of the MAPK phosphatase family. Though structurally related to the MAPK dual specificity phosphatases, MK-STYX lacks both the critical nucleophilic cysteine and adjacent histidine residues in the active site signature motif (HCX5R) required for catalysis. Thus, MK-STYX is catalytically inactive. Despite its lack of catalytic activity, MK-STYX maintains its ability to bind phosphorylated proteins but not dephosphorylate them. This thesis focuses on the role of MK-STYX in neuronal differentiation signal transduction cascades. The rat pheochromocytoma (PC12) cell line was used as a model system to study neuronal differentiation. Prior studies have shown that stimulation by neurotrophin nerve growth factor initiates sustained activation of a Ras-dependent MAPK phosphorylation cascade. Specifically, it is the sustained activation of extracellular signal-regulated kinase (ERK) 1/2 that leads to neuronal differentiation in PC12 cells. The results presented here confirm that MK-STYX causes neuronal differentiation in PC12 cells, suggesting a role in modulation of the MAPK pathway. Initially, MK-STYX modulation of the small G- protein Ras was investigated, because activation of Ras is known to lead to activation of the MAPK signal transduction cascade. This thesis shows that MK-STYX causes a very transient decrease in the activation of Ras. To further investigate the role of MK-STYX in the MAPK cascade, the kinase activity of MEK was inhibited.Without MEK activation of ERK 1/2, PC12 cells should not be able to differentiate. However, despite the presence of an inhibitor, MK-STYX continued to induce neuronal differentiation, suggesting MK- STYX acts independently of the MAPK pathway. This finding led to investigation of the small G-protein, RhoA. RhoA is involved in actin cytoskeleton remodeling. Prior studies have shown that activation of RhoA inhibits the initiation of neuronal outgrowths, whereas inactivation of RhoA promotes it. These studies provide evidence that MK- STYX decreases activation RhoA leading to the induction of neurite outgrowth. In summary, this thesis demonstrates that MK-STYX can induce PC12 neuronal differentiation through inactivation of RhoA and independently of the MAPK pathway. This strongly supports a model in which the pseudophosphatase MK-STYX has a critical role as a regulator in PC12 neuronal differentiation

Facing the Inevitable: The Inevitable Disclosure Doctrine and the Defend Trade Secrets Act of 2016

Multiple federal courts have recognized and applied the inevitable disclosure doctrine in cases brought by employers against former employees under the DTSA. The inevitable disclosure doctrine allows a business to temporarily enjoin the new employment of a former employee by a competitor on the theory that the employee learned confidential information while working for that business which the employee cannot possibly forget or refrain from relying on during her employment with the competitor. The application of this doctrine under the DTSA is controversial for two reasons. First, some states refuse to recognize the inevitable disclosure doctrine due, in part, to its restrictive effect on labor mobility. Secondly, the application is controversial because some practitioners thought that the language of the DTSA preempted the application of this doctrine at the federal level

Age related factors influence HIV testing within subpopulations: a cross sectional survey of MSM within the Celtic nations

Objectives: Despite a recent fall in the incidence of HIV within the UK, men who have sex with men (MSM) continue to be disproportionately affected. As biomedical prevention technologies including pre-exposure prophylaxis are increasingly taken up to reduce transmission, the role of HIV testing has become central to the management of risk. Against a background of lower testing rates among older MSM, this study aimed to identify age-related factors influencing recent (≤12 months) HIV testing. Methods: Cross-sectional subpopulation data from an online survey of sexually active MSM in the Celtic nations—Scotland, Wales, Northern Ireland and Ireland (n=2436)—were analysed to compare demographic, behavioural and sociocultural factors influencing HIV testing between MSM aged 16–25 (n=447), 26–45 (n=1092) and ≥46 (n=897). Results: Multivariate logistic regression demonstrated that for men aged ≥46, not identifying as gay (OR 0.62, CI 0.41 to 0.95), location (Wales) (OR 0.49, CI 0.32 to 0.76) and scoring higher on the personalised Stigma Scale (OR 0.97, CI 0.94 to 1.00) significantly reduced the odds for HIV testing in the preceding year. Men aged 26–45 who did not identify as gay (OR 0.61, CI 0.41 to 0.92) were also significantly less likely to have recently tested for HIV. For men aged 16–25, not having a degree (OR 0.48, CI 0.29 to 0.79), location (Republic of Ireland) (OR 0.55, CI 0.30 to 1.00) and scoring higher on emotional competence (OR 0.57, CI 0.42 to 0.77) were also significantly associated with not having recently tested for HIV. Conclusion: Key differences in age-related factors influencing HIV testing suggest health improvement interventions should accommodate the wide diversities among MSM populations across the life course. Future research should seek to identify barriers and enablers to HIV testing among the oldest and youngest MSM, with specific focus on education and stigma