2,802 research outputs found

    Long term frequency stability analysis of the GPS NAVSTAR 6 Cesium clock

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    Time domain measurements, taken between the NAVSTAR 6 Spacecraft Vehicle (SV) and the Vandenberg Global Positioning System (GPS) Monitor Site, by a pseudo random noise receiver, were collected over an extended period of time and analyzed to estimate the long term frequency stability of the NAVSTAR 6 onboard frequency standard, referenced to the Vandenberg MS frequency standard. The technique employed separates the clock offset from the composite signal by first applying corrections for equipment delays, ionospheric delay, tropospheric delay, Earth rotation and the relativistic effect. The data are edited and smoothed using the predicted SV ephemeris to calculate the geometric delay. Then all available passes from each of the four GPS monitor stations, are collected at 1-week intervals and used to calculate the NAVSTAR orbital elements. The procedure is then completed by subtracting the corrections and the geometric delay, using the final orbital elements, from the composite signal, thus leaving the clock offset and random error

    Factors that influence mental health services utilization by children who have experienced adversity

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    Adverse childhood experiences (ACEs) are linked to increased mental health problems in children, but their association with mental health services utilization is not well known. This secondary analysis used 2016 National Survey of Children’s Health data from two samples: children aged 6-17-years-old with a mental or behavioral condition in need of treatment or counseling (N = 5,723); and a subsample of children who experienced at least one ACE (n = 3,812). Multiple logistic regression and latent class analysis (LCA) were performed to examine the association between ACEs and mental health services utilization. Multiple logistic regressions also examined the associations of parent/caretaker vulnerability, school-system, and medical-system factors on mental health services utilization for children with ACEs using the Gelberg-Andersen Behavioral Model for Vulnerable Populations and a Systems of Care approach as the framework for model building. Children with increased ACE scores did not have higher odds of utilizing mental health services compared to children at lower levels of or no ACEs. For children who experienced adversity, increased parent/caretaker vulnerability was associated with lower odds and the current receipt of special education services with increased odds of mental health services utilization in adjusted models. Strengths of this study included the large dataset and generalizability to the U.S. population. There were limitations to the measurement of ACEs and other key variables. The current study identified children who experienced adversity as an underserviced population for mental health services

    Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic Strings

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    We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of Z=100Z = 100 to the present and calculated the anisotropies which they induce. Based on a limited number of realizations, we have compared the results of our simulations with the observations of the COBE-DMR experiment. We have obtained a preliminary estimate of the string mass-per-unit-length μ\mu in the cosmic string scenario.Comment: 8 pages of TeX - [Color] Postscript available by anonymous ftp at ftp://fnas08.fnal.gov:/pub/Publications/Conf-94-197-A, FERMILAB-Conf-94/197-

    Hispanic Subgroups, Acculturation, and Substance Abuse Treatment Outcomes

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    This study explored Hispanic subgroup differences in substance use treatment outcomes, and the relationship of acculturation characteristics to these outcomes. Data were from a multisite randomized clinical trial of motivational enhancement therapy versus treatment as usual in a sample of Spanish-speaking substance abusers. Participants were Cuban American (n = 34), Mexican American (n = 209), Puerto Rican (n = 78), and other Hispanic American (n = 54). Results suggested that Cuban Americans and individuals with more connection to Hispanic culture had lower treatment retention. Hispanics born in the U.S and those who spoke English at home had a lower percentage of days abstinent during weeks 5–16, although Puerto Ricans born in the U.S. and Cuban Americans living more years in the U.S. had a higher percentage of days abstinent in weeks 1–4 and 5–16, respectively. Results may inform future hypothesis-driven studies in larger Hispanic treatment seeking samples of the relationship between acculturation and treatment outcome

    Explaining the Frequency of Alcohol Consumption in a Conflict Zone: Jews and Palestinians in Israel

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    Experiencing stress and exposure to terrorism may have an adverse effect on health risk behaviors. Few studies have examined alcohol use among adults living in Israel under chronic, stressful terrorism-related conditions. In this study, we examined the relationships of demographics, past stressful events, and terrorism exposure to the frequency of alcohol use and the mediating roles of depressive and post-traumatic stress disorder (PTSD) symptoms. We used three waves of data from a 2007–2008 nationally representative sample of Jewish and Palestinian adults in Israel. We assessed past stressful events, in addition to direct and indirect exposures to terrorism. Results indicated that past stressful events and exposure to terrorism were not directly associated with alcohol use, but were indirectly associated and mediated by depressive and PTSD symptomology. Mental health symptoms were differentially associated with alcohol use. More frequent drinking was mediated by higher levels of depression, including for women and Palestinians; however, PTSD symptom severity was related to less frequent drinking. Mental health may play a prominent role in the frequency of alcohol use among adults exposed to terrorism in Israel. Alcohol use, as a coping mechanism, may differ by demographic characteristics (gender and ethnicity) and psychological symptomology for adults living in a conflict zone in Israel

    A Demonstration of LISA Laser Communication

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    Over the past few years questions have been raised concerning the use of laser communications links between sciencecraft to transmit phase information crucial to the reduction of laser frequency noise in the LISA science measurement. The concern is that applying medium frequency phase modulations to the laser carrier could compromise the phase stability of the LISA fringe signal. We have modified the table-top interferometer presented in a previous article by applying phase modulations to the laser beams in order to evaluate the effects of such modulations on the LISA science fringe signal. We have demonstrated that the phase resolution of the science signal is not degraded by the presence of medium frequency phase modulations.Comment: minor corrections found in the CQG versio

    Developing young people's sense of self and place through sport

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    Previous research has recognized positive health implications, both physical and mental, as an outcome of participation in leisure pursuits. They provide opportunities for self-expression and stress reduction, as well as an environment in which people can socialize. Leisure activities, specifically sport activities, can play a significant role in young people's identity development. This paper explores the leisure activities in which young people in Adelaide, Australia participate. It examines the role of leisure activities in terms of young people's identity and feelings towards their hometown. This study consisted of semi-structured focus groups conducted with 24 senior high school students, followed by a survey resulting in 226 useable responses. Respondents were aged between 16 and 18 years of age. From the range of activities identified and explored, the results revealed sports activities to have the greatest impact on young people's lives. The results demonstrated that frequency of participation has a significant effect on young people's involvement levels and how they identify with the activity
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