11,323 research outputs found

    NASA's climate data system primer, version 1.2

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    This is a beginner's manual for NASA's Climate Data System (NCDS), an interactive scientific information management system that allows one to locate, access, manipulate, and display climate-research data. Additional information on the use of the system is available from the system itself

    Kennedy Space Center Timing and Countdown Interface to Kennedy Ground Control Subsystem

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    Kennedy Ground Control System (KGCS) engineers at the National Aeronautics and Space Administration (NASA) Kennedy Space Center (KSC) are developing a time-tagging process to enable reconstruction of the events during a launch countdown. Such a process can be useful in the case of anomalies or other situations where it is necessary to know the exact time an event occurred. It is thus critical for the timing information to be accurate. KGCS will synchronize all items with Coordinated Universal Time (UTC) obtained from the Timing and Countdown (T&CD) organization. Network Time Protocol (NTP) is the protocol currently in place for synchronizing UTC. However, NTP has a peak error that is too high for today's standards. Precision Time Protocol (PTP) is a newer protocol with a much smaller peak error. The focus of this project has been to implement a PTP solution on the network to increase timing accuracy while introducing and configuring the implementation of a firewall between T&CD and the KGCS network

    Value added or misattributed? A multi-institution study on the educational benefit of labs for reinforcing physics content

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    Instructional labs are widely seen as a unique, albeit expensive, way to teach scientific content. We measured the effectiveness of introductory lab courses at achieving this educational goal across nine different lab courses at three very different institutions. These institutions and courses encompassed a broad range of student populations and instructional styles. The nine courses studied had two key things in common: the labs aimed to reinforce the content presented in lectures, and the labs were optional. By comparing the performance of students who did and did not take the labs (with careful normalization for selection effects), we found universally and precisely no added value to learning from taking the labs as measured by course exam performance. This work should motivate institutions and departments to reexamine the goals and conduct of their lab courses, given their resource-intensive nature. We show why these results make sense when looking at the comparative mental processes of students involved in research and instructional labs, and offer alternative goals and instructional approaches that would make lab courses more educationally valuable.Comment: Accepted to Phys Rev PE

    Benthic and hyporheic invertebrate community responses to seasonal flow recession in a groundwater-dominated stream

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    Natural hydrological variability in lotic ecosystems can include prolonged periods of flow recession. A reduction in discharge is accompanied by abiotic changes in benthic and hyporheic habitats, often including reductions in s habitat availability. Whilst the benthic invertebrate community response to low flows is well documented, little research has considered how the composition of the community within the hyporheic zone is affected. We examined benthic and hyporheic invertebrate community composition during flow recession in a temperate karst stream, at sites with contrasting historic flow permanence regimes. Changes in the benthic invertebrate community composition primarily reflected changes in habitat availability associated with discharge variability; in particular, the population density of the dominant amphipod, Gammarus pulex, increased as the area of submerged benthic sediments declined. Concurrent significant increase in the hyporheic abundance of G. pulex, and moderate increase in the proportion of the total G. pulex population inhabiting the hyporheic zone were recorded. It is postulated that G. pulex migrated into the hyporheic zone to reduce exposure to intensifying biological interactions in the benthic sediments. Increase in the hyporheic abundance of G. pulex was particularly pronounced at sites with historic intermittent flow, which could be attributed to downwelling stream water dominating vertical hydrologic exchange. The increase in G. pulex abundance reduced community diversity in the benthic sediments, but had no apparent detrimental effects on the hyporheic invertebrate assemblages

    Impact of age and race on outcomes of a program to prevent excess weight gain and disordered eating in adolescent girls

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    Interpersonal psychotherapy (IPT) prevents weight gain and reduces loss-of-control (LOC)-eating in adults. However, IPT was not superior to health-education (HE) for preventing excess weight gain and reducing LOC-eating over 1-year in adolescent girls at risk for excess weight gain and eating disorders. Limited data suggest that older and non-White youth may be especially responsive to IPT. In secondary analyses, we examined if age or race moderated weight and LOC-eating outcomes. The 113 participants (12–17 years; 56.6% White) from the original trial were re-contacted 3 years later for assessment. At baseline and follow-up visits through 3 years, we assessed BMI, adiposity by dual energy X-ray absorptiometry, and LOC-eating presence. In linear mixed models, baseline age moderated 3-year BMI outcome; older girls in IPT had the lowest 3-year BMI gain compared to younger girls in IPT and all girls in HE, p = 0.04. A similar pattern was observed for adiposity. Race moderated 3-year LOC-eating; non-White girls in IPT were most likely to abstain from LOC-eating at 3 years compared to all other girls, p = 0.04. This hypothesis-generating analysis suggests future studies should determine if IPT is especially efficacious at reducing LOC-eating in older, non-White adolescents
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