18,920 research outputs found

    Advanced space system concepts and their orbital support needs (1980 - 2000). Volume 1: Executive summary

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    The likely system concepts which might be representative of NASA and DoD space programs in the 1980-2000 time period were studied along with the programs' likely needs for major space transportation vehicles, orbital support vehicles, and technology developments which could be shared by the military and civilian space establishments in that time period. Such needs could then be used by NASA as an input in determining the nature of its long-range development plan. The approach used was to develop a list of possible space system concepts (initiatives) in parallel with a list of needs based on consideration of the likely environments and goals of the future. The two lists thus obtained represented what could be done, regardless of need; and what should be done, regardless of capability, respectively. A set of development program plans for space application concepts was then assembled, matching needs against capabilities, and the requirements of the space concepts for support vehicles, transportation, and technology were extracted. The process was pursued in parallel for likely military and civilian programs, and the common support needs thus identified

    Advanced space system concepts and their orbital support needs (1980 - 2000). Volume 2: Final report

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    The results are presented of a study which identifies over 100 new and highly capable space systems for the 1980-2000 time period: civilian systems which could bring benefits to large numbers of average citizens in everyday life, much enhance the kinds and levels of public services, increase the economic motivation for industrial investment in space, expand scientific horizons; and, in the military area, systems which could materially alter current concepts of tactical and strategic engagements. The requirements for space transportation, orbital support, and technology for these systems are derived, and those requirements likely to be shared between NASA and the DoD in the time period identified. The high leverage technologies for the time period are identified as very large microwave antennas and optics, high energy power subsystems, high precision and high power lasers, microelectronic circuit complexes and data processors, mosaic solid state sensing devices, and long-life cryogenic refrigerators

    Advanced space system concepts and their orbital support needs (1980 - 2000). Volume 3: Detailed data. Part 1: Catalog of initiatives, functional options, and future environments and goals

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    The following areas were discussed in relation to a study of the commonality of space vehicle applications to future national needs: (1) index of initiatives (civilian observation, communication, support), brief illustrated description of each initiative, time periods (from 1980 to 2000+) for implementation of these initiatives; (2) data bank of functional system options, presented in the form of data sheets, one for each of the major functions, with the system option for near-term, midterm, and far-term space projects applicable to each subcategory of functions to be fulfilled; (3) table relating initiatives and desired goals (public service and humanistic, materialistic, scientific and intellectual); and (4) data on size, weight and cost estimations

    The stability of the O(N) invariant fixed point in three dimensions

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    We study the stability of the O(N) fixed point in three dimensions under perturbations of the cubic type. We address this problem in the three cases N=2,3,4N=2,3,4 by using finite size scaling techniques and high precision Monte Carlo simulations. It is well know that there is a critical value 2<Nc<42<N_c<4 below which the O(N) fixed point is stable and above which the cubic fixed point becomes the stable one. While we cannot exclude that Nc<3N_c<3, as recently claimed by Kleinert and collaborators, our analysis strongly suggests that NcN_c coincides with 3.Comment: latex file of 18 pages plus three ps figure

    Deep learning with convolutional neural networks for decoding and visualization of EEG pathology

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    We apply convolutional neural networks (ConvNets) to the task of distinguishing pathological from normal EEG recordings in the Temple University Hospital EEG Abnormal Corpus. We use two basic, shallow and deep ConvNet architectures recently shown to decode task-related information from EEG at least as well as established algorithms designed for this purpose. In decoding EEG pathology, both ConvNets reached substantially better accuracies (about 6% better, ~85% vs. ~79%) than the only published result for this dataset, and were still better when using only 1 minute of each recording for training and only six seconds of each recording for testing. We used automated methods to optimize architectural hyperparameters and found intriguingly different ConvNet architectures, e.g., with max pooling as the only nonlinearity. Visualizations of the ConvNet decoding behavior showed that they used spectral power changes in the delta (0-4 Hz) and theta (4-8 Hz) frequency range, possibly alongside other features, consistent with expectations derived from spectral analysis of the EEG data and from the textual medical reports. Analysis of the textual medical reports also highlighted the potential for accuracy increases by integrating contextual information, such as the age of subjects. In summary, the ConvNets and visualization techniques used in this study constitute a next step towards clinically useful automated EEG diagnosis and establish a new baseline for future work on this topic.Comment: Published at IEEE SPMB 2017 https://www.ieeespmb.org/2017

    On the Adsorption of Lead Iodide on the Mercury Electrode

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    The adsorption of lead iodide on the mercury electrode was studied by the potential-sweep chronoamperometric method, by recording of polarographic current-time curves and by the measurement of the differential capacity of the electric doublelayer. From the dependence of height and potential of the adsorption peak on\u27 the concentration of iodide the solubility product of PbI2 was calcula ted (Ks = 1.3 X 10-8). From polarographic current- time curves it could be concluded that the adsorption process is controlled by diffusion and the surface excess was calculated rs= 4.3 X 10-10 mole/cm 2). The kinetics of the adsorption process is potential dependent. The measurements of the differential capacity have shown that the adsoprtion of lead occurs after previous adsorption of iodide ion and that in solutions of h igh iodide concentration the compact adsorption layer is destroyed

    Joint analyses of open comments and quantitative data: Added value in a job satisfaction survey of hospital professionals.

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    To obtain a comprehensive understanding of the job opinions of hospital professionals by conducting qualitative analyses of the open comments included in a job satisfaction survey and combining these results with the quantitative results. A cross-sectional survey targeting all Lausanne University Hospital professionals was performed in the fall of 2013. The survey considered ten job satisfaction dimensions (e.g. self-fulfilment, workload, management, work-related burnout, organisational commitment, intent to stay) and included an open comment section. Computer-assisted qualitative analyses were conducted on these comments. Satisfaction rates on the included dimensions and professional groups were entered as predictive variables in the qualitative analyses. Of 10 838 hospital professionals, 4978 participated in the survey and 1067 provided open comments. Data from 1045 respondents with usable comments constituted the analytic sample (133 physicians, 393 nurses, 135 laboratory technicians, 247 administrative staff, including researchers, 67 logistic staff, 44 psycho-social workers, and 26 unspecified). Almost a third of the comments addressed scheduling issues, mostly related to problems and exhaustion linked to shifts, work-life balance, and difficulties with colleagues' absences and the consequences for quality of care and patient safety. The other two-thirds related to classic themes included in job satisfaction surveys. Although some comments were provided equally by all professional groups, others were group specific: work and hierarchy pressures for physicians, healthcare quality and patient safety for nurses, skill recognition for administrative staff. Overall, respondents' comments were consistent with their job satisfaction ratings. Open comment analysis provides a comprehensive understanding of hospital professionals' job experiences, allowing better consideration of quality initiatives that match the needs of professionals with reality

    Damped harmonic oscillator interpretation of the soft-state power spectra of Cyg X-1

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    We develop a model of an accretion disc in which the variability induced at a given radius is governed by a damped harmonic oscillator at the corresponding epicyclic frequency. That variability induces both linear and non-linear responses in the locally emitted radiation. The total observed variability of a source is the sum of these contributions over the disc radius weighted by the energy dissipation rate at each radius. It is shown that this simple model, which effectively has only three parameters including the normalization, can explain the range of the power spectra observed from Cyg X-1 in the soft state. Although a degeneracy between the black hole mass and the strength of the damping does not allow a unique determination of the mass, we can still constrain it to <16--20 solar masses. We also show that our model preserves the observed linear rms-flux relationship even in the presence of the non-linear flux response.Comment: MNRAS (Letters), in pres
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