2,021 research outputs found

    Rayleigh Taylor instability in a thin film bounded by a porous layer

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    The Rayleigh Taylor stability in a finite thickness layer of a viscous fluid bounded below by a densely packed thick porous thick porous layer and above by a rigid surface has been studied subject to linear anal. using approxns. in effect similar to lubrication and Stokes approxns. The problem is studied anal. It is shown that the nature of the linear stability curve is controlled by the slip parameter α and the thickness of the fluid layer h, while its shape is controlled by the ratio of the surface tension to the normal stress

    A Generative-Discriminative Basis Learning Framework to Predict Clinical Severity from Resting State Functional MRI Data

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    We propose a matrix factorization technique that decomposes the resting state fMRI (rs-fMRI) correlation matrices for a patient population into a sparse set of representative subnetworks, as modeled by rank one outer products. The subnetworks are combined using patient specific non-negative coefficients; these coefficients are also used to model, and subsequently predict the clinical severity of a given patient via a linear regression. Our generative-discriminative framework is able to exploit the structure of rs-fMRI correlation matrices to capture group level effects, while simultaneously accounting for patient variability. We employ ten fold cross validation to demonstrate the predictive power of our model on a cohort of fifty eight patients diagnosed with Autism Spectrum Disorder. Our method outperforms classical semi-supervised frameworks, which perform dimensionality reduction on the correlation features followed by non-linear regression to predict the clinical scores

    The enumeration of transitive self-complementary digraphs

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    Hot Core, Outflows and Magnetic Fields in W43-MM1 (G30.79 FIR 10)

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    We present submillimeter spectral line and dust continuum polarization observations of a remarkable hot core and multiple outflows in the high-mass star-forming region W43-MM1 (G30.79 FIR 10), obtained using the Submillimeter Array (SMA). A temperature of ∼\sim 400 K is estimated for the hot-core using CH3_3CN (J=19-18) lines, with detections of 11 K-ladder components. The high temperature and the mass estimates for the outflows indicate high-mass star-formation. The continuum polarization pattern shows an ordered distribution, and its orientation over the main outflow appears aligned to the outflow. The derived magnetic field indicates slightly super-critical conditions. While the magnetic and outflow energies are comparable, the B-field orientation appears to have changed from parsec scales to ∼\sim 0.1 pc scales during the core/star-formation process.Comment: accepted, ApJ Letter

    Study of internal motions through NQR in 6-​chloropyridin-​2-​ol

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    Temp. dependence of the 35Cl NQR of the title compd. was examd. at 77 K to room temp. The torsional frequencies and their temp. dependences were calcd. using Bayer's theory with and without Tatsuzaki's modification

    SMA outflow/disk studies in the massive star-forming region IRAS18089-1732

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    SMA observations of the massive star-forming region IRAS 18089-1732 in the 1mm and 850mu band reveal outflow and disk signatures in different molecular lines. The SiO(5--4) data show a collimated outflow in the northern direction. In contrast, the HCOOCH3(20--19) line, which traces high-density gas, is confined to the very center of the region and shows a velocity gradient across the core. The HCOOCH3 velocity gradient is not exactly perpendicular to the outflow axis but between an assumed disk plane and the outflow axis. We interpret these HCOOCH3 features as originating from a rotating disk that is influenced by the outflow and infall. Based on the (sub-)mm continuum emission, the mass of the central core is estimated to be around 38M_sun. The dynamical mass derived from the HCOOCH3 data is 22Msun, of about the same order as the core mass. Thus, the mass of the protostar/disk/envelope system is dominated by its disk and envelope. The two frequency continuum data of the core indicate a low dust opacity index beta ~ 1.2 in the outer part, decreasing to beta ~ 0.5 on shorter spatial scales.Comment: 7 pages of text, 1 table, 3 figures, accepted for ApJ Letter

    Submillimeter Array multiline observations of the massive star-forming region IRAS 18089-1732

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    Submillimeter Array (SMA) observations of the high-mass star-forming region IRAS 18089-1732 in the 1 mm and 850 μ\mum band with 1 GHz bandwidth reveal a wealth of information. We present the observations of 34 lines from 16 different molecular species. Most molecular line maps show significant contributions from the outflow, and only few molecules are confined to the inner core. We present and discuss the molecular line observations and outline the unique capabilities of the SMA for future imaging line surveys at high spatial resolution.Comment: Accepted for ApJ Letters, SMA special volum
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