10,602 research outputs found

    A Positive Test for Fermi-Dirac Distributions of Quark-Partons

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    By describing a large class of deep inelastic processes with standard parameterization for the different parton species, we check the characteristic relationship dictated by Pauli principle: broader shapes for higher first moments. Indeed, the ratios between the second and the first moment and the one between the third and the second moment for the valence partons is an increasing function of the first moment and agrees quantitatively with the values found with Fermi-Dirac distributions.Comment: 15 pages LaTeX, 2 eps figures. Final version, to appear in Mod. Phys. Lett.

    CVD of CrO2 Thin Films: Influence of the Deposition Parameters on their Structural and Magnetic Properties

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    This work reports on the synthesis of CrO2 thin films by atmospheric pressure CVD using chromium trioxide (CrO3) and oxygen. Highly oriented (100) CrO2 films containing highly oriented (0001) Cr2O3 were grown onto Al2O3(0001) substrates. Films display a sharp magnetic transition at 375 K and a saturation magnetization of 1.92 Bohr magnetons per f.u., close to the bulk value of 2 Bohr magnetons per f.u. for the CrO2. Keywords: Chromium dioxide (CrO2), Atmospheric pressure CVD, Spintronics.Comment: 5 pages, 6 figure

    A self-consistent test of Comptonization models using a long BeppoSAX observation of NGC 5548

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    We test accurate models of Comptonization spectra over the high quality data of the BeppoSAX long look at NGC 5548. The data are well represented by a plane parallel corona with an inclination angle of 30^{\circ}, a soft photon temperature of 5 eV and a hot plasma temperature and optical depth of kTekT_{\rm e}\simeq 360 keV and τ\tau\simeq 0.1, respectively. If energy balance applies, such values suggest that a more ``photon-starved'' geometry (e.g. a hemispheric region) is necessary. The spectral softening detected during a flare, appears to be associated to a decrease of the heating-to-cooling ratio, indicating a geometric and/or energetic modification of the disk plus corona system. The hot plasma temperature derived with the models above is significantly higher than that obtained fitting the same data with a power law plus high energy cut off model for the continuum. This is due to the fact that in anisotropic geometries Comptonization spectra show "intrinsic" curvature which moves the fitted high energy cut-off to higher energies.Comment: 4 pages, 2 figures, to appear in the proceedings of the conference "X-ray Astronomy '99", Bologna, Italy, September 199

    SO(10) Unified Theories and Cosmology

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    We review the status of a class of gauge unified models based on SO(10) group. After a pedagogical introduction to SO(10) gauge theories, we discuss the main phenomenological implications of these models. The upper limit on proton lifetime are obtained and the prediction for neutrino masses are compared with the astrophysical and cosmological constraints coming from solar neutrino data and dark matter problem. Possible scenarios for the production of the baryon asymmetry of the universe required by primordial nucleosynthesis are also discussed.Comment: 16 pages LaTeX, no figures, needs sprocl.sty, included. To appear in the proceedings of NANP97, Dubna, July 1997. Few misprints correcte

    CORRELATING WRITER’S BLOCK AND ESL LEARNERS’ WRITING QUALITY

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    Despite the importance of writing in the language learners’ development, there are difficulties faced by English as a Second Language (ESL) learners that stem from various factors. One of them is the presence of writer’s block that could affect writing quality. Therefore, this study aims to describe writer’s block, along with a statistically-laden analysis of the possible correlation between the blocking experiences of 55 Filipino ESL learners and the levels of easability and readability of the essays they had written.  This research employed a descriptive-correlational design using The Questionnaire in Identifying Writer’s Block (QIWB) to gauge the extent of occurrence of writer’s block and the Coh-Metrix Common Core Text Easability and Readability Assessor (hereafter Coh-Metrix T.E.R.A.), an online computational tool, to measure the levels of easability and readability of the essays. The result shows that the learners generally experienced writer’s block, and their essays collectively showed high levels of easability on the basis of narrativity, referential cohesion, and deep cohesion. However, the essays were low in syntactic simplicity and word concreteness, while the level of readability computed exceeded that of the reading ability of 10th-grade learners. Test of correlation revealed that there exists negligible relationship between writer’s block and the overall easability and readability levels of the essays, though a significant but a weak relationship was documented between lateness and word concreteness and with premature editing and deep cohesion, respectively

    The modelling of the flow-induced vibrations of periodic flat and axial-symmetric structures with a wave-based method

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    International audienceThe stochastic response of periodic flat and axial-symmetric structures, subjected to random and spatially-correlated loads, is here analysed through an approach based on the combination of a wave finite element and a transfer matrix method. Although giving a lower computational cost, the present approach keeps the same accuracy of classic finite element methods. When dealing with homogeneous structures, the accuracy is also extended to higher frequencies, without increasing the time of calculation. Depending on the complexity of the structure and the frequency range, the computational cost can be reduced more than two orders of magnitude. The presented methodology is validated both for simple and complex structural shapes, under deterministic and random loads

    Investigations about periodic design for broadband increased sound transmission loss of sandwich panels using 3D-printed models

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    International audienceTwo types of sandwich panels are designed by using the periodic structure theory. A double-wall panel with mechanical links and a sandwich panel with rectangular core are studied. An oriented optimization of the elastic bending waves' propagation versus the acoustic wavenumbers is achieved by using shifted core walls and by keeping the mass and stiffness of the system constant. Standard and optimized configurations are 3D-printed and sound transmission measurements are carried out by using a facility with an uncoupled reverberant-anechoic configuration. The experimental evidences of enlarged bending band-gaps and deformation mechanisms are proved using a reverse approach based on the acoustic radiation of the panels

    Implementasi Case Based Reasoning Untuk Sistem Diagnosis Penyakit Anjing

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    Penalaran Berbasis Kasus / Case Based Reasoning (CBR) merupakan metode yang dipergunakan untuk membangun sebuah sistem berbasis pengetahuan. Sumber pengetahuan sistem diperoleh dengan mengumpulkan penanganan kasus-kasus oleh seorang ahli/pakar. Keuntungan dengan penerapan metode ini adalah pembangun pengetahuan tidak perlu melakukan akusisi pengetahuan secara langsung dengan seorang pakar. Pada penelitian ini penulis mengimplementasikan metode CBR untuk membantu pendiagnosisan penyakit anjing. Kasus-kasus yang dipergunakan dalam sistem diperoleh dari catatan penangan kasus diagnosa penyakit anjing dari seorang dokter hewan. Sistem akan memberikan keluaran berupa kemungkinan penyakit dan saran pengobatan yang didasarkan pada kemiripan kasus baru dengan pengetahuan yang dimiliki sistem
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