3,767 research outputs found

    Quantum tunneling of the interfaces between normal-metal and superconducting regions of a type-I Pb superconductor

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    Evidence of a non-thermal magnetic relaxation in the intermediate state of a type-I superconducor is presented. It is attributed to quantum tunneling of interfaces separating normal and superconducting regions. Tunneling barriers are estimated and temperature of the crossover from thermal to quantum regime is obtained from Caldeira-Leggett theory. Comparison between theory and experiment points to tunneling of interface segments of size comparable to the coherence length, by steps of order one nanometer

    Interregional input-ouptut system for Ecuador, 2007: methodology and results

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    In this paper, we explore the structural characteristics of the interregional input-output system developed for Ecuador for the year 2007. As part of an ongoing project that aims to develop an interregional CGE model for the country, this database was developed under conditions of limited information. It provides the opportunity to better understand the spatial linkage structure associated with the national economy in the context of its 22 provinces, 15 sectors and 60 different products. This exploratory analysis is based on the description of structural coefficients and the use of traditional input-output techniques. Finally, we further explore the spatial linkage structure by looking at the regional decomposition of final demand. It is hoped that this exercise might result in a better appreciation of a broader set of dimensions that might improve our understanding of the integrated interregional economic system in Ecuador.Interregional input-output model; Ecuador; spatial linkages

    Streamlined Subglacial Bedform Sensitivity to Bed Characteristics Across the Deglaciated Northern Hemisphere

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    Streamlined subglacial bedforms observed in deglaciated landscapes provide the opportunity to assess the sensitivity of glacier dynamics to bed characteristics across broader spatiotemporal scales than is possible for contemporary glacial systems. While many studies of streamlined subglacial bedforms rely on manual mapping and qualitative (i.e., visual) assessment, we semi-automatically identify 11,628 sedimentary and bedrock bedforms, created during and following the Last Glacial Maximum across nine geologically and topographically diverse deglaciated sites in the Northern Hemisphere. Using this large dataset of landforms and associated morphometrics, we empirically test the importance of subglacial terrain on bedform morphology and ice-flow behavior. A minimum bedform length–width ratio threshold provides a constraint on minimum morphometrics needed for streamlined bedforms to develop. Similarities in bedform metric distribution regardless of bed properties indicate that all bed types may support similar distributions of warm-based ice flow conditions. Ice flow within valleys with easily erodible beds host the most elongate bedforms yet the widest range in bedform elongation and bedform surface relief. The presence of these highly elongate bedforms suggest high ice-flow velocities occur within valley settings despite spatially heterogeneous landform-generating processes. In contrast, lithified sedimentary beds within regions not constrained by topography on the scale of 1–102 km contain bedforms with high density and packing, low change in surface relief and low elongation, indicating spatially uniform and organized interactions at the ice–bed interface and consistency in ice-flow velocity. Regardless of genesis, we find a sensitivity of bedform elongation (i.e., used to interpret ice-flow speed or persistence) to topographic conditions on the scale of 1–102 km, while bedform density is sensitive to bed lithology. The findings presented in this study provide analogues for processes of subglacial erosion and deposition, ice–bed interactions and warm-based ice flow within contemporary glacial systems

    DeepSleep: A ballistocardiographic deep learning approach for classifying sleep stages

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    Current techniques for tracking sleep are either obtrusive (Polysomnography) or low in accuracy (wearables). In this early work, we model a sleep classification system using an unobtrusive Ballistocardiographic (BCG)-based heart sensor signal collected from a commercially available pressure-sensitive sensor sheet. We present DeepSleep, a hybrid deep neural network architecture comprising of CNN and LSTM layers. We further employed a 2-phase training strategy to build a pre-trained model and to tackle the limited dataset size. Our model results in a classification accuracy of 74%, 82%, 77% and 63% using Dozee BCG, MIT-BIH’s ECG, Dozee’s ECG and Fitbit’s PPG datasets, respectively. Furthermore, our model shows a positive correlation (r = 0.43) with the SATED perceived sleep quality scores. We show that BCG signals are effective for long-term sleep monitoring, but currently not suitable for medical diagnostic purposes

    Field induced magnetic transition and metastability in Co substituted Mn2SbMn_{2}Sb

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    A detailed investigation of first order ferrimagnetic (FRI) to antiferromagnetic (AFM) transition in Co (15%) doped Mn2SbMn_2Sb is carried out. These measurements demonstrate anomalous thermomagnetic irreversibility and glass-like frozen FRI phase at low temperatures. The irreversibility arising between the supercooling and superheating spinodals is distinguised in an ingenious way from the irreversibility arising due to kinetic arrest. Field annealing measurements shows reentrant FRI-AFM-FRI transition with increasing temperature. These measurements also show that kinetic arrest band and supercooling band are anitcorrelated i.e regions which are kinetically arrested at higher temperature have lower supercooling temperature and vice versa.Comment: 10 pages, 8 figure

    The PdBI Arcsecond Whirlpool Survey (PAWS): Environmental Dependence of Giant Molecular Cloud Properties in M51

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    Using data from the PdBI Arcsecond Whirlpool Survey (PAWS), we have generated the largest extragalactic Giant Molecular Cloud (GMC) catalog to date, containing 1,507 individual objects. GMCs in the inner M51 disk account for only 54% of the total 12CO(1-0) luminosity of the survey, but on average they exhibit physical properties similar to Galactic GMCs. We do not find a strong correlation between the GMC size and velocity dispersion, and a simple virial analysis suggests that 30% of GMCs in M51 are unbound. We have analyzed the GMC properties within seven dynamically-motivated galactic environments, finding that GMCs in the spiral arms and in the central region are brighter and have higher velocity dispersions than inter-arm clouds. Globally, the GMC mass distribution does not follow a simple power law shape. Instead, we find that the shape of the mass distribution varies with galactic environment: the distribution is steeper in inter-arm region than in the spiral arms, and exhibits a sharp truncation at high masses for the nuclear bar region. We propose that the observed environmental variations in the GMC properties and mass distributions are a consequence of the combined action of large-scale dynamical processes and feedback from high mass star formation. We describe some challenges of using existing GMC identification techniques for decomposing the 12CO(1-0) emission in molecule-rich environments, such as M51's inner disk.Comment: 73 pages, 18 figures, 14 tables, accepted for publication in Ap
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