298 research outputs found

    Glass fiber processing for the Moon/Mars program: Center director's discretionary fund final report

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    Glass fiber has been produced from two lunar soil simulants. These two materials simulate lunar mare soil and lunar highland soil compositions, respectively. Short fibers containing recrystallized areas were produced from the as-received simulants. Doping the highland simulant with 8 weight percent B2-O3 yielded a material which could be spun continuously. The effects of lunar gravity on glass fiber formation were studied utilizing NASA's KC-135 aircraft. Gravity was found to play a major role in final fiber diameter

    Ab-initio calculation of the electronic and optical excitations in polythiophene: effects of intra- and interchain screening

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    We present an calculation of the electronic and optical excitations of an isolated polythiophene chain as well as of bulk polythiophene. We use the GW approximation for the electronic self-energy and include excitonic effects by solving the electron-hole Bethe-Salpeter equation. The inclusion of interchain screening in the case of bulk polythiophene drastically reduces both the quasi-particle band gap and the exciton binding energies, but the optical gap is hardly affected. This finding is relevant for conjugated polymers in general.Comment: 4 pages, 1 figur

    Process Demonstration For Lunar In Situ Resource Utilization-Molten Oxide Electrolysis (MSFC Independent Research and Development Project No. 5-81)

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    The purpose of this Focus Area Independent Research and Development project was to conduct, at Marshall Space Flight Center, an experimental demonstration of the processing of simulated lunar resources by the molten oxide electrolysis process to produce oxygen and metal. In essence, the vision was to develop two key technologies, the first to produce materials (oxygen, metals, and silicon) from lunar resources and the second to produce energy by photocell production on the Moon using these materials. Together, these two technologies have the potential to greatly reduce the costs and risks of NASA s human exploration program. Further, it is believed that these technologies are the key first step toward harvesting abundant materials and energy independent of Earth s resources

    Ab-initio prediction of the electronic and optical excitations in polythiophene: isolated chains versus bulk polymer

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    We calculate the electronic and optical excitations of polythiophene using the GW approximation for the electronic self-energy, and include excitonic effects by solving the electron-hole Bethe-Salpeter equation. Two different situations are studied: excitations on isolated chains and excitations on chains in crystalline polythiophene. The dielectric tensor for the crystalline situation is obtained by modeling the polymer chains as polarizable line objects, with a long-wavelength polarizability tensor obtained from the ab-initio polarizability function of the isolated chain. With this model dielectric tensor we construct a screened interaction for the crystalline case, including both intra- and interchain screening. In the crystalline situation both the quasi-particle band gap and the exciton binding energies are drastically reduced in comparison with the isolated chain. However, the optical gap is hardly affected. We expect this result to be relevant for conjugated polymers in general.Comment: 15 pages including 4 figures; to appear in Phys. Rev. B, 6/15/200

    Geology of Niobrara State Park, Knox County, Nebraska, and Adjacent Areas, with a Brief History of the Park, Gavins Point Dam, and Lewis and Clark Lake

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    Location Niobrara State Park is located in northwestern Knox County, Nebraska, just west of the town of Niobrara and on the west side of the Niobrara River. The present park was opened in the summer of 1987. Mostly north of Nebraska Highway 12, the site is hilly with bluffs overlooking the Missouri and Niobrara rivers. Excellent facilities include paved roads, cabins, an outdoor swimming pooi, hiking trails, picnic and camping sites, horseback riding trails, playgrounds, restrooms, a group lodge, and an interpretive shelter. Many vantage points in the park have beautiful views of the lower Niobrara Valley and the middle Missouri Valley. Lovers of native plants and wildlife can see many different species in and near the park. Park grounds are open all year. The park office, about 1.5 miles northwest of the park entrance, is open daily from mid-April to mid-November, and weekdays at other times of the year (figs. 1 and 2). Purposes This educational circular describes the prehistory and history of Niobrara State Park, Gavins Point Dam and its reservoir-Lewis and Clark Lake-and several aspects of the geology of the park and nearby or adjoining areas. Sections include information on minerals, fossils, stratigraphy, and geologic history, but the principal focuses of this circular are on the work of and changes in the Niobrara River and on geologic hazards in the area. Cautions Caution is advised when visiting the park or any other area. A void walking on landslide areas. Stay away from steep hill slopes. Be careful when working on dark shale exposures on hot days because temperatures on these shales reach well above 100 degrees F. Poison ivy, stinging insects, and other such hazards occur. Be careful! We remind readers that collecting of any kind is prohibited in the park and that permission must be obtained from property owners before going on or collecting from private property

    Do You Need a Foot-in-the-Door or Is A Toe Enough? Scripting Introductions That Induce Tailoring and Increase Participation in Telephone Interviews

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    Substantial research and practical experience shows that a telephone interviewer is most successful at gaining cooperation and avoiding refusals when they are free to tailor their introductory pitch to the potential respondent or household informant they reach. However, survey designers are often uncomfortable allowing interviewers to work “off-script,” and instruct interviewers to read introductory text verbatim. Further, some interviewers report being more comfortable with a script than without one. To bridge this gap between research and practice we asked, “Can we create a scripted introduction that engages the potential respondent, gets a foot-in-the-door, and facilitates interviewer tailoring?” This paper reports on a randomized experimental test of two such scripts, each implemented within the Washington Behavioral Risk Factor Surveillance System (BRFSS), a random digit dial (RDD) phone survey. In both phases of the experiment, sampled phone numbers were randomized to the standard BRFSS introduction or the new script. Phase 1 (August, 2018) implemented a “conversational” introduction that added or revised three features of the standard BRFSS introduction: First, the introduction included three “hook questions” (e.g., “Have you heard of the survey?”). One hook question was randomly displayed each time a phone number was called. Second, the script displayed on the first three CATI screens was modified to sound more conversational and less abrupt. Third, pause points were created to make sure the interviewer slows down and listens to the potential respondent. Each of these features is hypothesized to increase tailoring, and thus cooperation, by encouraging interaction between the interviewer and potential respondent. Phase 2 (September, 2018) replaced the conversational introduction with a “progressive scheduling” script that instructed interviewers to ask for a good time to call back to complete the interview rather than asking for complete cooperation on the call. This approach encourages a dynamic that shows respect for the respondent’s time. It also changes a large, unexpected request to a small one that the respondent can plan. While call-backs are sometimes considered undesirable outcomes, they can be a good “toe-in-the-door” technique that leads to full cooperation later. Our primary outcomes are cooperation, scheduled callbacks, and refusals. Additionally, a more conversational introduction might influence answers to questions within the interview, such as if increased rapport depresses reports of sensitive behaviors. Thus, we will also assess the effect of the modified scripts on responses to assess the nonresponse / measurement error trade-offs of this approach

    Shifted phase of EEG cross-frequency coupling in individuals with Phelan-McDermid syndrome

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    Background Phelan-McDermid Syndrome (PMS) is a rare condition caused by deletion or mutation of the SHANK3 gene. Individuals with PMS frequently present with intellectual disability, autism spectrum disorder, and other neurodevelopmental challenges. Electroencephalography (EEG) can provide a window into network-level function in PMS. Methods Here, we analyze EEG data collected across multiple sites in individuals with PMS (n = 26) and typically developing individuals (n = 15). We quantify oscillatory power, alpha-gamma phase-amplitude coupling strength, and phase bias, a measure of the phase of cross frequency coupling thought to reflect the balance of feedforward (bottom-up) and feedback (top-down) activity. Results We find individuals with PMS display increased alpha-gamma phase bias (U = 3.841, p < 0.0005), predominantly over posterior electrodes. Most individuals with PMS demonstrate positive overall phase bias while most typically developing individuals demonstrate negative overall phase bias. Among individuals with PMS, strength of alpha-gamma phase-amplitude coupling was associated with Sameness, Ritualistic, and Compulsive behaviors as measured by the Repetitive Behavior Scales-Revised (Beta = 0.545, p = 0.011). Conclusions Increased phase bias suggests potential circuit-level mechanisms underlying phenotype in PMS, offering opportunities for back-translation of findings into animal models and targeting in clinical trials
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