470 research outputs found
Caddisflies (Trichoptera) of Wildcat Creek, Pickens County, South Carolina
Sixty-two species of caddisflies (Trichoptera) were identified from collections make from Wildcat Creek over a period of 33 years. A new distributional record for South Carolina was obtained for Diplectrona metaqui. Eight species, Polycentropus carlsoni, Wormaldia thyria, Neotrichia collata, Stactobiella delira, Neophylax atlanta, Goera fuscula, Pseudogoera singularis, and Agarodes griseus, are considered to be threatened in South Carolina
Assessment Of Student Performance And Attitudes For Courses Taught Online Versus Onsite
This paper assesses the differences in performance and attitudes of students taught online versus onsite. Students completed a course evaluation designed to determine student satisfaction in specific areas. Student performance was measured by means of a comprehensive exam that tested all material covered in the course. Results support the contention that students in online courses learn as much or more than students in traditional onsite courses and are as satisfied with the course and the instruction as their onsite counterparts
Aquatic Insects of Upper Three Runs Creek, Savannah River Plant, South Carolina. Part IV: Caddisflies (Trichoptera) of the Lower Reaches
Ninety-three species of caddisflies, representing 14 families, were identified from collections obtained from two localities on Upper Three Runs Creek, Savannah River Site, Aiken County, South Carolina. Collections of adult caddisflies were made biweekly over a 1-yr period with ultraviolet light traps. The similarity index, Jaccard\u27s Coefficient of Communities, showed that the two sites were over 78% similar with 73 species in common. Three species, Oxyethira setosa Denning, Triaenodes smithi Ross, and Nyctiophylax serratus Lago & Harris, are new distributional records for South Carolina. Two species of Triaenodes are new to science. Other species, which were considered to be endemic to the Upper Three Runs Creek drainage, rare outside of the drainage, or of limited distribution, included Cheumatopsyche richardsoni Gordon, Oxyethira dunbartonensis Kelley, Protoptila morettii Morse, Hydrophysche elissoma Ross, Triaenodes ochraceus (Betten and Mosely), Neotrichia falca Ross, Oecetis morsei Bueno-Soria, and Pycnopsyche virginica (Banks)
The Momentum of Human Behavior in a Natural Setting
Adults with mental retardation in a group home received popcorn or coffee reinforcers for sorting plastic dinnerware. In Part 1 of the experiment, reinforcers were dispensed according to a variable-interval 60-s schedule for sorting dinnerware of one color and according to a variable-interval 240-s schedule for sorting dinnerware of a different color in successive components of a multiple schedule. Sorting rates were similar in baseline, but when a video program was shown concurrently, sorting of dinnerware was more resistant to distraction when correlated with a higher rate of reinforcement. In Part 2 of the experiment, popcorn or coffee reinforcers were contingent upon sorting both colors of dinnerware according to variable-interval 60-s schedules, but additional reinforcers were given independently of sorting according to a variable-time 30-s schedule during one dinnerware-color component. Baseline sorting rate was lower but resistance to distraction by the video program was greater in the component with additional variable-time reinforcers. These results demonstrate that resistance to distraction depends on the rate of reinforcers obtained in the presence of component stimuli but is independent of baseline response rates and response-reinforcer contingencies. Moreover, these results are similar to those obtained in laboratory studies with pigeons, demonstrating that the determination of resistance to change by stimulus-reinforcer relations is not confined to controlled laboratory settings or unique to the pigeon
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LANSCE personnel access control system
The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. The Personnel Access Control System (PACS) is a component of the RSS that is designed to prevent personnel access to areas where prompt radiation is a hazard. PACS was designed to replace several older personnel safety systems (PSS) with a single modem unified design. Lessons learned from the operation over the last 20 years were incorporated into a redundant sensor, single-point failure safe, fault tolerant, and tamper-resistant system that prevents access to the beam areas by controlling the access keys and beam stoppers. PACS uses a layered philosophy to the physical and electronic design. The most critical assemblies are battery backed up, relay logic circuits; less critical devices use Programmable Logic Controllers (PLCs) for timing functions and communications. Outside reviewers have reviewed the operational safety of the design. The design philosophy, lessons learned, hardware design, software design, operation, and limitations of the device are described
How the toughness in metallic glasses depends on topological and chemical heterogeneity
To gain insight into the large toughness variability observed between metallic glasses (MGs), we examine the origin of fracture toughness through bending experiments and molecular dynamics (MD) simulations for two binary MGs: Pd_(82)Si_(18) and Cu_(46)Zr_(54). The bending experiments show that Pd_(82)Si_(18) is considerably tougher than Cu_(46)Zr_(54), and the higher toughness of Pd_(82)Si_(18) is attributed to an ability to deform plastically in the absence of crack nucleation through cavitation. The MD simulations study the initial stages of cavitation in both materials and extract the critical factors controlling cavitation. We find that for the tougher Pd_(82)Si_(18), cavitation is governed by chemical inhomogeneity in addition to topological structures. In contrast, no such chemical correlations are observed in the more brittle Cu_(46)Zr_(54), where topological low coordination number polyhedra are still observed around the critical cavity. As such, chemical inhomogeneity leads to more difficult cavitation initiation in Pd_(82)Si_(18) than in Cu_(46)Zr_(54), leading to a higher toughness. The absence of chemical separation during cavitation initiation in Cu_(46)Zr_(54) decreases the energy barrier for a cavitation event, leading to lower toughness
The effect of HIV and antiretroviral therapy on characteristics of pulmonary tuberculosis in northern Malawi: a cross-sectional study.
BACKGROUND: HIV infection reduces the likelihood that individuals with pulmonary tuberculosis are smear positive and that they have cavitatory disease. Antiretroviral therapy (ART) may shift the pattern of disease to be more similar to that of HIV negative patients. This would aid diagnosis--which often depends on sputum smears--but would also increase infectiousness. We assessed the effect of HIV and ART on smear positivity and cavitatory disease in laboratory-confirmed pulmonary TB patients. METHODS: Three sputum samples were collected per pulmonary TB suspect and were examined using microscopy and culture. Chest radiographs were available for a subset of patients as part of another study. The effect of HIV and ART status on sputum smear positivity and lung cavitation were evaluated using multivariable logistic regression. RESULTS: Of 1024 laboratory-confirmed pulmonary TB patients who were identified between January 2005 and December 2011, 766 had HIV and ART status available. Positive sputum smears were significantly more common among HIV negative individuals than HIV positive individuals (adjusted OR = 2.91, 95% CI 1.53-5.55). Compared to those HIV positive but not on ART, patients on ART were more likely to be smear positive (adjusted OR = 2.33, 95% CI 1.01-5.39) if they had been on ART ≤ 6 months, but only slightly more likely to be smear positive (adjusted OR = 1.43, 95% CI 0.68-2.99) if they were on ART > 6 months. HIV negative patients were more likely than HIV positive patients to have cavitatory disease (adjusted OR = 1.97, 95% CI 1.20-3.23). Patients on ART > 6 months had a slight increase in cavitatory disease compared to HIV positive patients not on ART (adjusted OR = 1.68, CI 0.78-3.63). CONCLUSIONS: HIV infection is associated with less smear positivity and cavitation in pulmonary TB patients. Among HIV positive patients, the use of ART shifts the presentation of disease towards that seen in HIV-negative individuals, which facilitates diagnosis but which also could increase infectiousness
Oral Corticosterone Administration Reduces Insulitis but Promotes Insulin Resistance and Hyperglycemia in Male Nonobese Diabetic Mice
© 2017 American Society for Investigative Pathology Steroid-induced diabetes is the most common form of drug-induced hyperglycemia. Therefore, metabolic and immunological alterations associated with chronic oral corticosterone were investigated using male nonobese diabetic mice. Three weeks after corticosterone delivery, there was reduced sensitivity to insulin action measured by insulin tolerance test. Body composition measurements revealed increased fat mass and decreased lean mass. Overt hyperglycemia (\u3e250 mg/dL) manifested 6 weeks after the start of glucocorticoid administration, whereas 100% of the mice receiving the vehicle control remained normoglycemic. This phenotype was fully reversed during the washout phase and readily reproducible across institutions. Relative to the vehicle control group, mice receiving corticosterone had a significant enhancement in pancreatic insulin-positive area, but a marked decrease in CD3+ cell infiltration. In addition, there were striking increases in both citrate synthase gene expression and enzymatic activity in skeletal muscle of mice in the corticosterone group relative to vehicle control. Moreover, glycogen synthase expression was greatly enhanced, consistent with elevations in muscle glycogen storage in mice receiving corticosterone. Corticosterone-induced hyperglycemia, insulin resistance, and changes in muscle gene expression were all reversed by the end of the washout phase, indicating that the metabolic alterations were not permanent. Thus, male nonobese diabetic mice allow for translational studies on the metabolic and immunological consequences of glucocorticoid-associated interventions in a mouse model with genetic susceptibility to autoimmune disease
Discovery of a Powerful >1061 erg AGN Outburst in the Distant Galaxy Cluster SPT-CLJ0528-5300
We present ~103 ks of Chandra observations of the galaxy cluster SPT-CLJ0528-5300 (SPT0528, z = 0.768). This cluster harbors the most radio-loud (L 1.4GHz = 1.01 × 1033 erg s−1 Hz−1) central active galactic nucleus (AGN) of any cluster in the South Pole Telescope (SPT) Sunyaev–Zeldovich survey with available X-ray data. We find evidence of AGN-inflated cavities in the X-ray emission, which are consistent with the orientation of the jet direction revealed by Australia Telescope Compact Array radio data. The combined probability that two such depressions—each at ~1.4–1.8σ significance, oriented ~180° apart and aligned with the jet axis—would occur by chance is 0.1%. At gsim1061 erg, the outburst in SPT0528 is among the most energetic known in the universe, and certainly the most powerful known at z > 0.25. This work demonstrates that such powerful outbursts can be detected even in shallow X-ray exposures out to relatively high redshifts (z ~ 0.8), providing an avenue for studying the evolution of extreme AGN feedback. The ratio of the cavity power ( erg s−1) to the cooling luminosity (L cool = (1.5 ± 0.5) × 1044 erg s−1) for SPT0528 is among the highest measured to date. If, in the future, additional systems are discovered at similar redshifts with equally high P cav/L cool ratios, it would imply that the feedback/cooling cycle was not as gentle at high redshifts as in the low-redshift universe
Glassy steel optimized for glass-forming ability and toughness
An alloy development strategy coupled with toughness assessments and ultrasonic measurements is implemented to design a series of iron-based glass-forming alloys that demonstrate improved glass-forming ability and toughness. The combination of good glass-forming ability and high toughness demonstrated by the present alloys is uncommon in Fe-based systems, and is attributed to the ability of these compositions to form stable glass configurations associated with low activation barriers for shear flow, which tend to promote plastic flow and give rise to a toughness higher than other known Fe-based bulk-glass-forming systems
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