Summary of NASA landing-gear research

Research relative to tire tread, powered-wheel taxiing, air cushion landing systems, and crosswind landing gear is discussed

Summary of NASA landing-gear research

This paper presents a brief summary of the airplane landing gear research underway at NASA. The technology areas include: ground handling simulator, antiskid braking systems, space shuttle nose-gear shimmy, active control landing gear, wire brush skid landing gear, air cushion landing systems, tire/surface friction characteristics, tire mechanical properties, tire-tread materials, powered wheels for taxiing, and crosswind landing gear. This paper deals mainly with the programs on tire-tread materials, powered wheel taxiing, air cushion landing systems, and crosswind landing gear research with particular emphasis on previously unreported results of recently completed flight tests. Work in the remaining areas is only mentioned

Nociceptive-Evoked Potentials Are Sensitive to Behaviorally Relevant Stimulus Displacements in Egocentric Coordinates.

Feature selection has been extensively studied in the context of goal-directed behavior, where it is heavily driven by top-down factors. A more primitive version of this function is the detection of bottom-up changes in stimulus features in the environment. Indeed, the nervous system is tuned to detect fast-rising, intense stimuli that are likely to reflect threats, such as nociceptive somatosensory stimuli. These stimuli elicit large brain potentials maximal at the scalp vertex. When elicited by nociceptive laser stimuli, these responses are labeled laser-evoked potentials (LEPs). Although it has been shown that changes in stimulus modality and increases in stimulus intensity evoke large LEPs, it has yet to be determined whether stimulus displacements affect the amplitude of the main LEP waves (N1, N2, and P2). Here, in three experiments, we identified a set of rules that the human nervous system obeys to identify changes in the spatial location of a nociceptive stimulus. We showed that the N2 wave is sensitive to: (1) large displacements between consecutive stimuli in egocentric, but not somatotopic coordinates; and (2) displacements that entail a behaviorally relevant change in the stimulus location. These findings indicate that nociceptive-evoked vertex potentials are sensitive to behaviorally relevant changes in the location of a nociceptive stimulus with respect to the body, and that the hand is a particularly behaviorally important site

A comparison between ion characteristics observed by the POLAR and DMSP spacecraft in the high-latitude magnetosphere

We study here the injection and transport of ions in the convection-dominated region of the Earth’s magnetosphere. The total ion counts from the CAMMICE MICS instrument aboard the POLAR spacecraft are used to generate occurrence probability distributions of magnetospheric ion populations. MICS ion spectra are characterised by both the peak in the differential energy flux, and the average energy of ions striking the detector. The former permits a comparison with the Stubbs et al. (2001) survey of He2+ ions of solar wind origin within the magnetosphere. The latter can address the occurrences of various classifications of precipitating particle fluxes observed in the topside ionosphere by DMSP satellites (Newell and Meng, 1992). The peak energy occurrences are consistent with our earlier work, including the dawn-dusk asymmetry with enhanced occurrences on the dawn flank at low energies, switching to the dusk flank at higher energies. The differences in the ion energies observed in these two studies can be explained by drift orbit effects and acceleration processes at the magnetopause, and in the tail current sheet. Near noon at average ion energies of _1 keV, the cusp and open LLBL occur further poleward here than in the Newell and Meng survey, probably due to convectionrelated time-of-flight effects. An important new result is that the pre-noon bias previously observed in the LLBL is most likely due to the component of this population on closed field lines, formed largely by low energy ions drifting earthward from the tail. There is no evidence here of mass and momentum transfer from the solar wind to the LLBL by nonreconnection coupling. At higher energies (_2–20 keV), we observe ions mapping to the auroral oval and can distinguish between the boundary and central plasma sheets. We show that ions at these energies relate to a transition from dawnward to duskward dominated flow, this is evidence of how ion drift orbits in the tail influence the location and behaviour of the plasma populations in the magnetosphere

Prospective associations of different contexts of physical activity with psychological distress and well-being among middle-aged adults: an analysis of the 1970 British Cohort Study

Background: Our aim was to investigate whether different types and social contexts of physical activity (PA) participation are prospectively associated with psychological distress and well-being among middle-aged adults. / Methods: Data from the 1970 British Cohort Study was used (N=5,144-2,733 women). At age 42y, participants reported their type of leisure-time PA, which was classified as individual PA or group PA (exposure). At age 46y, participants reported co-primary outcomes: psychological distress (Malaise Inventory) and well-being (Warwick-Edinburgh scale). Highest academic achievement, employment status, country of interview, baseline values of psychological distress and well-being, smoking, alcohol use, TV-viewing and total physical activity at 42y were used as covariates. Main analyses included linear regression stratifying by sex. / Results: Jogging, cross-country, road-running (both sexes) as well as team sports (men) were associated with higher well-being. Health, fitness, gym or conditioning activities and jogging, cross-country (women), road-running (women) and team sports (men) were associated with lower psychological distress. Participation in both individual and group PA were associated with lower psychological distress and higher well-being for both sexes in crude models. However, adjusted models revealed that only group PA was associated with lower psychological distress (B: -0.106; 95%CI:-0.188 to -0.025) and higher well-being (0.835; 0.050 to 1.619) among men but not women. In the sensitivity analysis, group PA was associated with higher well-being (0.855; 0.094 to 1.616) when compared with individual PA among men. Group PA was not associated with psychological distress among both sexes and well-being among women when compared with individual PA. / Conclusion: Group PA was prospectively associated with lower psychological distress and higher well-being among men but not females. Future PA interventions could focus on group activities for males. Further research to understand the relationship between individual/group PA and mental health is required in females

Solar system constraints on the Dvali-Gabadadze-Porrati braneworld theory of gravity

A number of proposals have been put forward to account for the observed accelerating expansion of the Universe through modifications of gravity. One specific scenario, Dvali-Gabadadze-Porrati (DGP) gravity, gives rise to a potentially observable anomaly in the solar system: all planets would exhibit a common anomalous precession, dw/dt, in excess of the prediction of General Relativity. We have used the Planetary Ephemeris Program (PEP) along with planetary radar and radio tracking data to set a constraint of |dw/dt| < 0.02 arcseconds per century on the presence of any such common precession. This sensitivity falls short of that needed to detect the estimated universal precession of |dw/dt| = 5e-4 arcseconds per century expected in the DGP scenario. We discuss the fact that ranging data between objects that orbit in a common plane cannot constrain the DGP scenario. It is only through the relative inclinations of the planetary orbital planes that solar system ranging data have sensitivity to the DGP-like effect of universal precession. In addition, we illustrate the importance of performing a numerical evaluation of the sensitivity of the data set and model to any perturbative precession.Comment: 9 pages, 2 figures, accepted for publication in Phys. Rev.

Nociceptive-Evoked Potentials Are Sensitive to Behaviorally Relevant Stimulus Displacements in Egocentric Coordinates.

Feature selection has been extensively studied in the context of goal-directed behavior, where it is heavily driven by top-down factors. A more primitive version of this function is the detection of bottom-up changes in stimulus features in the environment. Indeed, the nervous system is tuned to detect fast-rising, intense stimuli that are likely to reflect threats, such as nociceptive somatosensory stimuli. These stimuli elicit large brain potentials maximal at the scalp vertex. When elicited by nociceptive laser stimuli, these responses are labeled laser-evoked potentials (LEPs). Although it has been shown that changes in stimulus modality and increases in stimulus intensity evoke large LEPs, it has yet to be determined whether stimulus displacements affect the amplitude of the main LEP waves (N1, N2, and P2). Here, in three experiments, we identified a set of rules that the human nervous system obeys to identify changes in the spatial location of a nociceptive stimulus. We showed that the N2 wave is sensitive to: (1) large displacements between consecutive stimuli in egocentric, but not somatotopic coordinates; and (2) displacements that entail a behaviorally relevant change in the stimulus location. These findings indicate that nociceptive-evoked vertex potentials are sensitive to behaviorally relevant changes in the location of a nociceptive stimulus with respect to the body, and that the hand is a particularly behaviorally important site

The Psychosocial Consequences of Sports Participation for Individuals with Severe Mental Illness: A Metasynthesis Review

The purpose of the current metasynthesis review was to explore the psychosocial benefits of sport and psychosocial factors which impact on sports participation for individuals with severe mental illness. AMED, CINAHL Plus, Medline, EMBASE, ProQuest Nursing & Allied Health Source, and Science Citation Index were searched from inception until January 2014. Articles included use qualitative methods to examine the psychosocial effects of sports participation in people with severe mental illness. Methodological quality was assessed using the Consolidated Criteria for Reporting Qualitative Studies and a case study tool. Included studies were analysed within a metasynthesis approach. Eight articles involving 56 patients met the inclusion criteria. The results identified the broader and direct psychosocial benefits of sport. Sport provided a ?normal? environment and interactions that were not associated with an individual?s mental illness. Sport provided individuals with a sense of meaning, purpose, belonging, identity, and achievement. Other findings are discussed. Direct psychosocial benefits are a consequence of sports participation for the vast majority of individuals with severe mental illness. Further to this, sports participation was associated with a reduction in social isolation and an increase in social confidence, autonomy, and independence

Physical activity and healthy ageing: A systematic review and meta-analysis of longitudinal cohort studies.

BACKGROUND: Older people constitute a significant proportion of the total population and their number is projected to increase by more than half by 2030. This increasing probability of late survival comes with considerable individual, economic and social impact. Physical activity (PA) can influence the ageing process but the specific relationship with healthy ageing (HA) is unclear. METHODS: We conducted a systematic review and meta-analysis of longitudinal studies examining the associations of PA with HA. Studies were identified from a systematic search across major electronic databases from inception as January 2017. Random-effect meta-analysis was performed to calculate a pooled effect size (ES) and 95% CIs. Studies were assessed for methodological quality. RESULTS: Overall, 23 studies were identified including 174,114 participants (30% men) with age ranges from 20 to 87 years old. There was considerable heterogeneity in the definition and measurement of HA and PA. Most of the identified studies reported a significant positive association of PA with HA, six reported a non-significant. Meta-analysis revealed that PA is positively associated with HA (ES: 1.39, 95% CI=1.23-1.57, n=17) even if adjusted for publication bias (ES: 1.27, 95% CI=1.11-1.45, n=20). CONCLUSIONS: There is consistent evidence from longitudinal observational studies that PA is positively associated with HA, regardless of definition and measurement. Future research should focus on the implementation of a single metric of HA, on the use of objective measures for PA assessment and on a full-range of confounding adjustment. In addition, our research indicated the limited research on ageing in low-and-middle income countries

Epidemiology of depression with psychotic experiences and its association with chronic physical conditions in 47 low- and middle-income countries

BackgroundThe co-existence of depression and psychotic experiences (PEs) is associated with more pronounced adverse health outcomes compared to depression alone. However, data on its prevalence and correlates are lacking in the general adult population, and there is no published data on its association with chronic physical conditions.MethodCross-sectional, community-based data from 201 337 adults aged ⩾18 years from 47 low- and middle-income countries from the World Health Survey were analyzed. The presence of past 12-month PE and DSM-IV depression was assessed with the Composite International Diagnostic Interview (CIDI). Information on six chronic medical conditions (chronic back pain, edentulism, arthritis, angina, asthma, diabetes) were obtained by self-report. Multivariable logistic regression analysis was performed.ResultsThe crude overall prevalence of co-morbid depression/PEs was 2.5% [95% confidence interval (CI) 2.3–2.7%], with the age- and sex-adjusted prevalence ranging from 0.1% (Sri Lanka, Vietnam) to 9.03% (Brazil). Younger age, urban setting, current smoking, alcohol consumption, and anxiety were significant correlates of co-existing depression/PEs. Co-occurring depression/PEs was associated with significantly higher odds for arthritis, angina, and diabetes beyond that of depression alone after adjusting for sociodemographics, anxiety, and country, with odds ratios (depression/PEs v. depression only) being: arthritis 1.30 (95% CI 1.07–1.59, p = 0.0086); angina 1.40 (95% CI 1.18–1.67, p = 0.0002); diabetes 1.65 (95% CI 1.21–2.26, p = 0.0017).ConclusionsThe prevalence of co-existing depression/PEs was non-negligible in most countries. Our study suggests that when depression/PE or a chronic condition (e.g. arthritis, angina, diabetes) is detected, screening for the other may be important to improve clinical outcomes.</jats:sec