682 research outputs found
The development of a cislunar space infrastructure
The primary objective of this Advanced Mission Design Program is to define the general characteristics and phased evolution of a near-Earth space infrastructure. The envisioned foundation includes a permanently manned, self-sustaining base on the lunar surface, a space station at the Libration Point between earth and the moon (L1), and a transportation system that anchors these elements to the Low Earth Orbit (LEO) station. The implementation of this conceptual design was carried out with the idea that the infrastructure is an important step in a larger plan to expand man's capabilities in space science and technology. Such expansion depends on low cost, reliable, and frequent access to space for those who wish to use the multiple benefits of this environment. The presence of a cislunar space infrastructure would greatly facilitate the staging of future planetary missions, as well as the full exploration of the lunar potential for science and industry. The rationale for, and a proposed detailed scenario in support of, the cislunar space infrastructure are discussed
Impact parameter dependence of the nuclear modification of J/psi production in d+Au collisions at sqrt(S_NN) = 200 GeV
The centrality dependence of sqrt(s_NN)= 200 GeV d+Au {J/\psi} data, measured
in 12 rapidity bins that span -2.2 < y < 2.4, has been fitted using a model
containing an effective absorption cross section combined with EPS09 NLO
shadowing. The centrality dependence of the shadowing contribution was allowed
to vary nonlinearly, employing a variety of assumptions, in an effort to
explore the limits of what can be determined from the data. The impact
parameter dependencies of the effective absorption cross section and the
shadowing parameterization are sufficiently distinct to be determined
separately. It is found that the onset of shadowing is a highly nonlinear
function of impact parameter. The mid and backward rapidity absorption cross
sections are compared with lower energy data and, for times of 0.05 fm/c or
greater, data over a broad range of collision energies and rapidities are well
described by a model in which the absorption cross section depends only on time
spent in the nucleus.Comment: 11 pages, 11 figures. Expanded discussion of methods, and added
extensive comparison of effective absorption cross sections with lower energy
data, and with theory. Corrected minor typos in table 1, corrected typos in
best fit parameters for Fig.
Hypersomnia subtypes, sleep and relapse in bipolar disorder.
BACKGROUND: Though poorly defined, hypersomnia is associated with negative health outcomes and new-onset and recurrence of psychiatric illness. Lack of definition impedes generalizability across studies. The present research clarifies hypersomnia diagnoses in bipolar disorder by exploring possible subgroups and their relationship to prospective sleep data and relapse into mood episodes. METHOD: A community sample of 159 adults (aged 18-70 years) with bipolar spectrum diagnoses, euthymic at study entry, was included. Self-report inventories and clinician-administered interviews determined features of hypersomnia. Participants completed sleep diaries and wore wrist actigraphs at home to obtain prospective sleep data. Approximately 7 months later, psychiatric status was reassessed. Factor analysis and latent profile analysis explored empirical groupings within hypersomnia diagnoses. RESULTS: Factor analyses confirmed two separate subtypes of hypersomnia (long sleep and excessive sleepiness) that were uncorrelated. Latent profile analyses suggested a four-class solution, with long sleep and excessive sleepiness again representing two separate classes. Prospective sleep data suggested that the sleep of long sleepers is characterized by a long time in bed, not long sleep duration. Longitudinal assessment suggested that excessive sleepiness at baseline predicted mania/hypomania relapse. CONCLUSIONS: This study is the largest of hypersomnia to include objective sleep measurement, and refines our understanding of classification, characterization and associated morbidity. Hypersomnia appears to be comprised of two separate subgroups: long sleep and excessive sleepiness. Long sleep is characterized primarily by long bedrest duration. Excessive sleepiness is not associated with longer sleep or bedrest, but predicts relapse to mania/hypomania. Understanding these entities has important research and treatment implications
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