1,444 research outputs found

    Classical approximation for ionization by heavy particle impact

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    Classical binary approximation for ionization by proton impac

    Classical calculations of charge transfer cross sections

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    Calculations of charge transfer cross section

    User's guide: Programs for processing altimeter data over inland seas

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    The programs described were developed to process GEODYN-formatted satellite altimeter data, and to apply the processed results to predict geoid undulations and gravity anomalies of inland sea areas. These programs are written in standard FORTRAN 77 and are designed to run on the NSESCC IBM 3081(MVS) computer. Because of the experimental nature of these programs they are tailored to the geographical area analyzed. The attached program listings are customized for processing the altimeter data over the Black Sea. Users interested in the Caspian Sea data are expected to modify each program, although the required modifications are generally minor. Program control parameters are defined in the programs via PARAMETER statements and/or DATA statements. Other auxiliary parameters, such as labels, are hard-wired into the programs. Large data files are read in or written out through different input or output units. The program listings of these programs are accompanied by sample IBM job control language (JCL) images. Familiarity with IBM JCL and the TEMPLATE graphic package is assumed

    Analysis of altimetry over inland seas

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    Satellite-based altimetric data taken by GEOS-3 and SEASAT over the Black Sea and Caspian Sea are analyzed and a least squares collocation technique is used to predict the geoid undulation on a .25-degree by .25-degree grid and to transform these geoid undulations to free air gravity anomalies. This project entailed processing satellite altimeter data over inland seas for recovery of area mean gravity information. Gravity information in this area of the world is not readily available, so the possibility of obtaining it from the processing of altimeter observations is attractive. The principal objective was to complete and extend analyses done in a previous study, verify those results, and document the results and techniques. A secondary objective was to improve the algorithms and results, if possible. The approach used involved editing geoid height data to remove overland data; evaluating geoid height differences at crossover points; removing orbit errors from geoid heights using crossover differences; gridding geoid height data at .25-degree by .25-degree intervals; and estimating the gravity anomalies from gridded geoid heights using the collocation technique

    Imaging dielectric relaxation in nanostructured polymers by frequency modulation electrostatic force microscopy

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    We have developed a method for imaging the temperature-frequency dependence of the dynamics of nanostructured polymer films with spatial resolution. This method provides images with dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe the local frequency-dependent (0.1–100 Hz) dielectric response through measurement of the amplitude and phase of the force gradient in response to an oscillating applied electric field. When the phase is imaged at fixed frequency, it reveals the spatial variation in dielectric losses, i.e., the spatial variation in molecular/dipolar dynamics, with 40 nm lateral resolution. This is demonstrated by using as a model system; a phase separated polystyrene/polyvinyl-acetate (PVAc) blend. We show that nanoscale dynamic domains of PVAc are clearly identifiable in phase images as those which light-up in a band of temperature, reflecting the variations in the molecular/dipolar dynamics approaching the glass transition temperature of PVAc

    Galaxy merger histories and the role of merging in driving star formation at z>1

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    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We use Horizon-AGN, a hydrodynamical cosmological simulation, to explore the role of mergers in the evolution of massive (M > 10^10 MSun) galaxies around the epoch of peak cosmic star formation (1zR(4:1 3 are 'blue' (i.e. have significant associated star formation), the proportion of 'red' mergers increases rapidly at ztodays stellar mass was formed.Peer reviewe

    Hospital revascularisation capability and quality of care after an acute coronary syndrome in Switzerland.

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    BACKGROUND: Patients with acute coronary syndrome (ACS) transferred to regional nonacademic hospitals after percutaneous coronary intervention (PCI) may receive fewer preventive interventions than patients who remain in university hospitals. We aimed at comparing hospitals with and without PCI facilities regarding guidelines-recommended secondary prevention interventions after an ACS. METHODS: We studied patients with ACS admitted to a university hospital with PCI facilities in Switzerland, and either transferred within 48 hours to regional nonacademic hospitals without PCI facilities or directly discharged from the university hospital. We measured prescription rates of evidence-based recommended therapies after ACS including reasons for nonprescription of aspirin, statins, β-blockers, angiotensin converting-enzyme inhibitors (ACEI) / angiotensin II receptor blockers (ARB), along with cardiac rehabilitation attendance and delivery of a smoking cessation intervention. RESULTS: Overall, 720 patients with ACS were enrolled; 541 (75.1%) were discharged from the hospital with PCI facilities, 179 (24.9%) were transferred to hospitals without PCI facilities. Concomitant prescription of aspirin, β-blockers, ACEI/ARB and statins at discharge was similar in hospitals with and without PCI facilities, reaching 83.9% and 85.5%, respectively (p = 0.62). Attendance at cardiac rehabilitation reached 55.5% for the hospital with PCI facilities and 65.7% for hospitals without PCI facilities (p = 0.02). In-hospital smoking cessation interventions were delivered to 70.8% patients exclusively at the hospital with PCI facilities. CONCLUSION: Quality of care for patients with ACS discharged from hospitals without PCI facilities was similar to that of patients directly discharged from the hospital with PCI facilities, except for in-hospital smoking cessation counselling and cardiac rehabilitation attendance

    Topological representations of matroid maps

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    The Topological Representation Theorem for (oriented) matroids states that every (oriented) matroid can be realized as the intersection lattice of an arrangement of codimension one homotopy spheres on a homotopy sphere. In this paper, we use a construction of Engstr\"om to show that structure-preserving maps between matroids induce topological mappings between their representations; a result previously known only in the oriented case. Specifically, we show that weak maps induce continuous maps and that the process is a functor from the category of matroids with weak maps to the homotopy category of topological spaces. We also give a new and conceptual proof of a result regarding the Whitney numbers of the first kind of a matroid.Comment: Final version, 21 pages, 8 figures; Journal of Algebraic Combinatorics, 201

    Fluorinated benzalkylsilane molecular rectifiers

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    We report on the synthesis and electrical properties of nine new alkylated silane self-assembled monolayers (SAMs) – (EtO)3Si(CH2)nN = CHPhX where n = 3 or 11 and X = 4-CF[subscript 3], 3,5-CF[subscript 3], 3-F-4-CF[subscript 3], 4-F, or 2,3,4,5,6-F, and explore their rectification behavior in relation to their molecular structure. The electrical properties of the films were examined in a metal/insulator/metal configuration, with a highly-doped silicon bottom contact and a eutectic gallium-indium liquid metal (EGaIn) top contact. The junctions exhibit high yields (>90%), a remarkable resistance to bias stress, and current rectification ratios (R) between 20 and 200 depending on the structure, degree of order, and internal dipole of each molecule. We found that the rectification ratio correlates positively with the strength of the molecular dipole moment and it is reduced with increasing molecular length.National Science Foundation (U.S.) (Award ECCS 1254757)Wake Forest University (Pilot Research Grant

    Enhancing accuracy and precision of transparent synthetic soil modelling

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    Over recent years non-intrusive modelling techniques have been developed to investigate soil-structure interaction problems of increasingly complex geometry. This paper concerns the development of a small-scale, 1 g, modelling technique using a transparent analogue for soil with particle image velocimetry for internal displacement measurement. Larger model geometry achieved in this research using fine-grained transparent synthetic soils has led to an increased need for rigorous photogrammetric correction techniques. A correction framework, based upon a modified version of the pinhole camera model, is presented that corrects for lens and camera movement induced errors as well as scaling from image space to object space. An additional statistical approach is also developed to enhance the system precision, by minimising the impact of increased non-coplanarity between the photogrammetry control plane and the target plane. The enhanced data correction and statistical precision is demonstrated using a case study examining the failure mechanism around a double helical screw pile installed in transparent synthetic soil representative of a soft clay
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