1,024 research outputs found
Design study of a device to simulate the dynamic environment encountered under condi- tions of reduced or zero gravity final report
Design study of reduced or zero gravity environment simulation devic
Health-related quality of life and depression among participants in the Sjögren's International Collaborative Clinical Alliance registry.
ObjectiveTo examine health-related quality of life (HRQoL) and depression among participants in an international Sjögren's syndrome (SS) registry, comparing those with and without SS.MethodsCross-sectional study of participants in the Sjögren's International Collaborative Clinical Alliance (SICCA) registry. The 2016 American College of Rheumatology/European League Against Rheumatism SS classification criteria were used to determine disease status. HRQoL was assessed using the Short Form 12, version 2 Health Survey to derive scores for physical component summary (PCS) and mental component summary (MCS). Depression was assessed using the 9-Item Patient Health Questionnaire. Multivariate linear and logistic regression analyses were performed to identify predictors of HRQoL and depression while controlling for potential confounders.ResultsAmong 2401 SICCA participants who had symptoms of dry eyes and dry mouth, 1051 had SS (44%) and 1350 did not (56%). After controlling for confounders, when compared with non-SS participants, those with SS had better PCS (p<0.001, β=2.43, 95% CI 1.57 to 3.29), MCS (p=0.002, β=1.37, 95% CI 0.50 to 2.23) and lower adjusted odds of depression (p<0.001, OR 0.67, 95% CI 0.55 to 0.81). Other significant predictors of HRQoL and depression included employment, country of residence and use of medication with anticholinergic effect or for management of SS-related signs and symptoms.ConclusionOur results suggest that among symptomatic patients, having a diagnosis of SS may be associated with better emotional and psychological well-being compared with patients without a diagnosis. Having a definitive diagnosis of SS may encourage patients to obtain a better understanding of their disease and have coping mechanisms in place to better manage their symptoms
Comparative study of normal and branched alkane monolayer films adsorbed on a solid surface. I. Structure
DOI: 10.1063/1.2464091The structure of a monolayer film of the branched alkane squalane (C30H62) adsorbed on graphite has been studied by neutron diffraction and molecular dynamics (MD) simulations and compared with a similar study of the n-alkane tetracosane (n-C24H52). Both molecules have 24 carbon atoms along their backbone and squalane has, in addition, six methyl side groups. Upon adsorption, there are significant differences as well as similarities in the behavior of these molecular films. Both molecules form ordered structures at low temperatures; however, while the melting point of the two-dimensional (2D) tetracosane film is roughly the same as the bulk melting point, the surface strongly stabilizes the 2D squalane film such that its melting point is 91 K above its value in bulk. Therefore, squalane, like tetracosane, will be a poor lubricant in those nanoscale devices that require a fluid lubricant at room temperature. The neutron diffraction data show that the translational order in the squalane monolayer is significantly less than in the tetracosane monolayer. The authors' MD simulations suggest that this is caused by a distortion of the squalane molecules upon adsorption on the graphite surface. When the molecules are allowed to relax on the surface, they distort such that all six methyl groups point away from the surface. This results in a reduction in the monolayer's translational order characterized by a decrease in its coherence length and hence a broadening of the diffraction peaks. The MD simulations also show that the melting mechanism in the squalane monolayer is the same footprint reduction mechanism found in the tetracosane monolayer, where a chain melting drives the lattice melting.This work was supported by the U.S. National Science Foundation under Grant Nos. DMR-0109057 and DMR-0411748 and by the U.S. Department of Energy through Grant No. DE-FG02-01ER45912. One of the authors (A.D.E.) thanks the Oticon Foundation, Denmark, for financial support
Structure and phase transitions of monolayers of intermediate-length n-alkanes on graphite studied by neutron diffraction and molecular dynamics simulation
Priming of D1-dopamine receptor responses: long-lasting behavioral supersensitivity to a D1-dopamine agonist following repeated administration to neonatal 6-OHDA-lesioned rats
The present study demonstrates that repeated administration of SKF- 38393, a D1-dopamine agonist, is necessary for maximal behavioral supersensitivity of D1-dopamine receptor responses in neonatal 6-OHDA- lesioned rats, confirming earlier work. This repeated administration of SKF-38393, which is referred to as priming of D1-dopamine receptor responses, resulted in a progressive increase in locomotor activity, as well as several other behaviors. This priming phenomenon lasted at least 6 months. Repeated administration of the D2-dopamine agonist LY- 171555 also increased behavioral responses to the D1-dopamine agonist. However, previous administration of a D2-dopamine agonist was not necessary for priming of D1-dopamine receptor responses, because D1- dopamine receptor priming could be produced in the presence of a D2- dopamine receptor antagonist. Blockade of D1-dopamine receptors with SCH-23390 prior to injection of SKF-38393 prevented the increasing responsiveness following repeated administration of this D1-dopamine agonist. Selective neonatal destruction of dopamine-containing neurons produced the same result as did destruction of catecholamine-containing neurons, indicating that the noradrenergic system is not involved in this phenomenon. Priming of D1-dopamine receptor responses by repeated administration of SKF-38393 was not observed in unlesioned controls or in rats that received catecholamine-depleting lesions as adults. Repeated administration of scopolamine also was able to prime behavioral responses to SKF-38393 in neonatal 6-OHDA-lesioned rats, indicating that endogenous release of dopamine can prime D1-dopamine receptor responses in neonatally lesioned rats. In addition, responses to indirect-acting agonists were enhanced in rats that had been primed with a D1-dopamine agonist when compared wit responses in unprimed animals.(ABSTRACT TRUNCATED AT 250 WORDS
Lunar Outgassing, Transient Phenomena and The Return to The Moon, I: Existing Data
Herein the transient lunar phenomena (TLP) report database is subjected to a
discriminating statistical filter robust against sites of spurious reports, and
produces a restricted sample that may be largely reliable. This subset is
highly correlated geographically with the catalog of outgassing events seen by
the Apollo 15, 16 and Lunar Prospector alpha-particle spectrometers for
episodic Rn-222 gas release. Both this robust TLP sample and even the larger,
unfiltered sample are highly correlated with the boundary between mare and
highlands, as are both deep and shallow moonquakes, as well as Po-210, a
long-lived product of Rn-222 decay and a further tracer of outgassing. This
offers another significant correlation relating TLPs and outgassing, and may
tie some of this activity to sagging mare basalt plains (perhaps mascons).
Additionally, low-level but likely significant TLP activity is connected to
recent, major impact craters (while moonquakes are not), which may indicate the
effects of cracks caused by the impacts, or perhaps avalanches, allowing
release of gas. The majority of TLP (and Rn-222) activity, however, is confined
to one site that produced much of the basalt in the Procellarum Terrane, and it
seems plausible that this TLP activity may be tied to residual outgassing from
the formerly largest volcanic ffusion sites from the deep lunar interior. With
the coming in the next few years of robotic spacecraft followed by human
exploration, the study of TLPs and outgassing is both promising and imperiled.
We will have an unprecedented pportunity to study lunar outgassing, but will
also deal with a greater burden of anthropogenic lunar gas than ever produced.
There is a pressing need to study lunar atmosphere and its sources while still
pristine. [Abstract abridged.]Comment: 35 pages, 3 figures, submitted to Icarus. Other papers in series
found at http://www.astro.columbia.edu/~arlin/TLP
Brain Regional Differences in the Effect of Ethanol on GABA Release from Presynaptic Terminals
Whereas ethanol has behavioral actions consistent with increased GABAergic function, attempts to demonstrate a direct enhancement of GABA-gated currents by ethanol have produced mixed results. Recent work has suggested that a part of the GABAergic profile of ethanol may result from enhanced GABA release from presynaptic terminals. The present study examines the effect of ethanol on GABA release in several brain regions to assess the regional nature of ethanol-induced GABA release. Whole-cell voltage clamp recording of spontaneous inhibitory postsynaptic currents (sIPSCs) from mechanically dissociated neurons and miniature inhibitory postsynaptic currents (mIPSCs) and paired-pulse ratio (PPR) from a slice preparation were used to quantify GABA release. Ethanol produced a concentration-dependent increase in the frequency of sIPSCs recorded from mechanically dissociated cerebellar Purkinje neurons and mIPSCs from substantia nigra neurons without having an effect on sIPSCs recorded from lateral septal or cerebrocortical neurons. This regional difference in the effect of ethanol on GABA release was confirmed with PPR recording from brain slices. These data indicate that ethanol can act on presynaptic terminals to increase GABA release in some brain regions while having little or no effect on GABA release in others. This regional difference is consistent with earlier in vivo studies in which ethanol affected neural activity and sensitivity to GABA in some, but not all, brain sites
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