2,848 research outputs found

    Effect of van-Hove singularities in single-walled carbon nanotube leads on transport through double quantum dot system

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    The double quantum dot system with single-walled metallic armchair carbon nanotube leads has been studied using Non-equilibrium Green function in the Keldysh formalism. The effect of relative spacing between the energy levels of the dots, interdot tunneling matrix-element, interdot Coulomb interaction and van-Hove singularities in density of states characteristics of quasi-one-dimensional carbon nanotube leads on the conductance of the double quantum dot system has been studied. The conductance and dot occupancies are calculated at finite temperature. It is observed that the density of states of the carbon nanotube leads play a significant role in determining the conductance profile. In particular, whenever the chemical potential of the isolated double quantum dot system is aligned with the position of a van-Hove singularity in the density of states of armchair carbon nanotube leads, the height of the corresponding conductance peak falls considerably. It is further observed that the suppression in the heights of the alternate peaks depends on the relative positions of the energy levels of the dots and their magnitude of separation.Comment: 16 pages and 16 figure

    Breathing Modes in Rotating Bose-Condensed Gas: An Exact Diagonalization Study

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    We present an exact diagonalization study of the breathing mode collective excitations for a rotating Bose-Einstein condensate of N=10N=10 spinless bosons interacting via repulsive finite-range Gaussian potential and harmonically confined in quasi-two-dimension. The yrast state and the low-lying excited states are variationally obtained in given subspaces of the quantized total angular momentum LL employing the beyond lowest Landau level approximation in slowly rotating regime with 0L<2N0 \le L < 2N. For a given LL, the low-energy eigenspectra (bands) are obtained in weakly to moderately interacting regime. Further, for a given interaction, the split in low-lying eigenenergies with increasing LL is the precursor to spontaneous symmetry breaking of the axisymmetry associated with the entry of the first vortex. With increase in repulsive interaction, the value of the first breathing mode increases for stable total angular momentum states L=0~\mbox{and}~N, but decreases for intermediate 0<L<N0<L<N metastable states. The position of the observed first breathing modes in the eigenspectrum remains unchanged as the interaction is varied over several orders of magnitude.Comment: 5 pages, 3 figures, RevTex two colum

    Analisis Faktor Yang Mempengaruhi Kemandirian Pada Pasien Cedera Kepala Yang Pernah Dirawat Di Igd RSUD Dr. R. Koesma Tuban

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    Cedera kepala akibat kecelakaan lalulintas merupakan penyebab utama disabilitas dan mortalitas. Functional Independence Measure (FIM) merupakan salah satu pengukuran kemandirian pasien cedera kepala. Beberapa faktor yang dicurigai adalah usia, mekanisme cedera, skor awal GCS, hipotensi, diameter pupil dan reaksi cahaya, CT scan, konsumsi alkohol, dan lama perawatan. Tujuan penelitian ini adalah mengetahui faktor yang mempengaruhi kemandirian pasien cedera kepala. Penelitian ini bersifat analitik observasional dengan menggunakan rancangan retrospektif terhadap107 sampel rekam medis RSUD dr. R. Koesma Tuban dari periode Januari-April 2016. Teknik sampling yang digunakan adalah teknik cluster random sampling dengan kriteria inklusi dan ekslusi. Instrumen yang digunakan lembar checklist dan lembar FIM. Analisis menggunakan uji koefisien kontingensi dan regresi logistik. Hasil uji regresi logistik menunjukan faktor yang mempengaruhi adalah GCS (p=0,996) dan Pupil (p=0,077). Persamaan yang didapat y = 0,357 + 19,434 (GCS) + 2,041 (Pupil). Hasil uji Hosmer and Lameshow menunjukan kalibrasi yang baik (p=1,000), nilai AUC menunjukan bahwa 93,6% persamaan regresi yang diperoleh mampu membedakan kemandirian pasien cedera kepala berdasarkan variabel GCS dan pupil, sisanya yaitu 6,4% dipengaruhi oleh faktor lain. Skor GCS yangrendah pada awal cedera berhubungan dengan prognosa yang buruk, sedangkan abnormalitas fungsi pupil, gangguan gerakan ekstraokular, pola-pola respons motorik yang abnormal seperti postur fleksor dan postur ekstensor, juga memprediksikan outcome yang buruk setelah cedera kepala.Kesimpulan dari penelitian ini adalah Skor awal GCS dan Pupil menjadi faktor yang dominan berpengaruh terhadap kemandirian. Oleh karena itu, perawat perlu meningkatkan manajemen pasien cedera kepala pada fase emergency dengan tidak mengabaikan pengukuran GCS dan Pupil

    Novel phases in rotating Bose-condensed gas: vortices and quantum correlation

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    We present the exact diagonalization study of rotating Bose-condensed gas interacting via finite-range Gaussian potential confined in a quasi-2D harmonic trap. The system of many-body Hamiltonian matrix is diagonalized in given subspaces of quantized total angular momentum to obtain the lowest-energy eigenstate employing the beyond lowest-Landau-level approximation. In the co-rotating frame, the quantum mechanical stability of angular momentum states is discussed for the existence of phase transition between the stable states of interacting system. Thereby analyzing the von Neumann entanglement entropy and degree of condensation provide the information about quantum phase correlation in the many-body states. Calculating the conditional probability distribution, we further probe the internal structure of quantum mechanically stable and unstable states. Much emphasis is put on finding the spatial correlation of bosonic atoms in the rotating system for the formation and entry of singly quantized vortices, and then organizing into canonical polygons with and without a central vortex at the trap center. Results are summarized in the form of a movie depicting the vortex patterns having discrete p-fold rotational symmetry with p=2,3,4,5,6p = 2,3,4,5,6.Comment: Updated version with 12 pages and 25 figures. This paper is dedicated to the memory of Professor M. Rafat (JMI), deceased on January 09, 2021, at the age of 6
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