2,444 research outputs found

    Journal Club: surveillance neuroimaging and neurologic examinations affect care for intracerebral hemorrhage

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    The article “Surveillance neuroimaging and neurologic examinations affect care for intracerebral hemorrhage”1 is reviewed. This review focuses on the methods, results, and limitations and merits of the original article

    Synlam(TM) Composite Mirror for Cyrogenic Applications

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    This presentation summarizes results of Small Business Innovation Research (SBIR) Phase I contract funded by NASA Marshall Space Flight Center and managed by Dr. H. Philip Stahl

    Further Evidence for Chemical Fractionation from Ultraviolet Observations of Carbon Monoxide

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    Ultraviolet absorption from interstellar 12CO and 13CO was detected toward rho Oph A and chi Oph. The measurements were obtained at medium resolution with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Column density ratios, N(12CO)/N(13CO), of 125 \pm 23 and 117 \pm 35 were derived for the sight lines toward rho Oph A and chi Oph, respectively. A value of 1100 \pm 600 for the ratio N(12C16O)/N(12C18O) toward rho Oph A was also obtained. Absorption from vibrationally excited H_2 (v" = 3) was clearly seen toward this star as well. The ratios are larger than the isotopic ratios for carbon and oxygen appropriate for ambient interstellar material. Since for both carbon and oxygen the more abundant isotopomer is enhanced, selective isotopic photodissociation plays the key role in the fractionation process for these directions. The enhancement arises because the more abundant isotopomer has lines that are more optically thick, resulting in more self shielding from dissociating radiation. A simple argument involving the amount of self shielding [from N(12CO)] and the strength of the ultraviolet radiation field premeating the gas (from the amount of vibrationally excited H_2) shows that selective isotopic photodissociation controls the fractionation seen in these two sight lines, as well as the sight line to zeta Oph.Comment: 40 pages, 8 figures, to appear in 10 July 2003 issue of Ap

    Science drivers and requirements for an Advanced Technology Large Aperture Space Telescope (ATLAST): Implications for technology development and synergies with other future facilities

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    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astronphysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers that define the main performance requirements for ATLAST (8 to 16 milliarcsec angular resolution, diffraction limited imaging at 0.5 {\mu}m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 {\mu}m to 2.4 {\mu}m, high stability in wavefront sensing and control). We will also discuss the synergy between ATLAST and other anticipated future facilities (e.g., TMT, EELT, ALMA) and the priorities for technology development that will enable the construction for a cost that is comparable to current generation observatory-class space missions.Comment: 12 pages, 4 figures, to appear in "Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave," edited by Jacobus M. Oschmann Jr., Mark C. Clampin, Howard A. MacEwen, Proc. of SPIE, Vol. 7731, 77312

    Predicting perceptual decision biases from early brain activity

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    Perceptual decision making is believed to be driven by the accumulation of sensory evidence following stimulus encoding. More controversially, some studies report that neural activity preceding the stimulus also affects the decision process. We used a multivariate pattern classification approach for the analysis of the human electroencephalogram (EEG) to decode choice outcomes in a perceptual decision task from spatially and temporally distributed patterns of brain signals. When stimuli provided discriminative information, choice outcomes were predicted by neural activity following stimulus encoding; when stimuli provided no discriminative information, choice outcomes were predicted by neural activity preceding the stimulus. Moreover, in the absence of discriminative information, the recent choice history primed the choices on subsequent trials. A diffusion model fitted to the choice probabilities and response time distributions showed that the starting point of the evidence accumulation process was shifted toward the previous choice, consistent with the hypothesis that choice priming biases the accumulation process toward a decision boundary. This bias is reflected in prestimulus brain activity, which, in turn, becomes predictive of future decisions. Our results provide a model of how non-stimulus-driven decision making in humans could be accomplished on a neural level

    The Advanced Technology Large Aperture Space Telescope (ATLAST): Science Drivers and Technology Developments

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    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astrophysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers and the resulting performance requirements for ATLAST (8 to 16 milliarcsecond angular resolution, diffraction limited imaging at 0.5 m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 m to 2.4 m, high stability in wavefront sensing and control). We also discuss the priorities for technology development needed to enable the construction of ATLAST for a cost that is comparable to current generation observatory-class space missions. Keywords: Advanced Technology Large-Aperture Space Telescope (ATLAST); ultraviolet/optical space telescopes; astrophysics; astrobiology; technology development

    The Advanced Technology Large Aperture Space Telescope (ATLAST): Science Drivers, Technology Developments, and Synergies with Other Future Facilities

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    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astrophysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers that define the main performance requirements for ATLAST (8 to 16 milliarcsec angular resolution, diffraction limited imaging at 0.5 m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 m to 2.4 m, high stability in wavefront sensing and control). We will also discuss the synergy between ATLAST and other anticipated future facilities (e.g., TMT, EELT, ALMA) and the priorities for technology development that will enable the construction for a cost that is comparable to current generation observatory-class space missions

    Biased agonists of the kappa opioid receptor suppress pain and itch without causing sedation or dysphoria

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    Agonists targeting the kappa opioid receptor (KOR) have been promising therapeutic candidates because of their efficacy for treating intractable itch and relieving pain. Unlike typical opioid narcotics, KOR agonists do not produce euphoria or lead to respiratory suppression or overdose. However, they do produce dysphoria and sedation, side effects that have precluded their clinical development as therapeutics. KOR signaling can be fine-tuned to preferentially activate certain pathways over others, such that agonists can bias signaling so that the receptor signals through G proteins rather than other effectors such as βarrestin2. We evaluated a newly developed G protein signaling–biased KOR agonist in preclinical models of pain, pruritis, sedation, dopamine regulation, and dysphoria. We found that triazole 1.1 retained the antinociceptive and antipruritic efficacies of a conventional KOR agonist, yet it did not induce sedation or reductions in dopamine release in mice, nor did it produce dysphoria as determined by intracranial self-stimulation in rats. These data demonstrated that biased agonists may be used to segregate physiological responses downstream of the receptor. Moreover, the findings suggest that biased KOR agonists may present a means to treat pain and intractable itch without the side effects of dysphoria and sedation and with reduced abuse potential
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