2,705 research outputs found

    Perbedaan House Indeks (HI) Berdasarkan Stratifikasi Daerah DBD di Wilayah Kerja UPT Puskesmas Martapura Kecamatan Martapura Kota Tahun 2012

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    Demam Berdarah Dengue (DBD) disebabkan oleh virus dan disebarkan oleh nyamuk. Penyakit ini adalah salah satu masalah bagi kesehatan masyarakat Indonesia yang cenderung terus menyebar dengan meningkatnya mobilitas dan kepadatan populasi. Dari tahun 2009 sampai dengan 2011 kasus DBD selalu ditemukan di wilayah kerja Puskesmas Martapura. Jika dilihat dari stratifikasi kasus DBD per kelurahan/desa tahun 2012, terdapat 1 kelurahan dan 3 desa yang termasuk dalam kategori daerah endemis DBD serta 7 desa yang termasuk dalam kategori daerah sporadis DBD. Belum pernah dilakukan pemeriksaan House Indeks (HI) oleh petugas P2DBD Puskesmas Martapura dan Dinas Kesehatan Kabupaten Banjar di wilayah kerja Puskesmas Martapura. Penelitian ini merupakan penelitian observasional analitik untuk mengetahui perbedaan HI daerah endemis DBD dengan daerah sporadis DBD di wilayah kerja UPT Puskesmas Martapura. Subjek penelitian adalah HI daerah endemis dan sporadis yang diuji dengan uji statistik Independent 2-samples t-test. Hasil menunjukkan bahwa tidak ada perbedaan HI antara daerah endemik dan sporadis dengue di wilayah kerja Puskesmas Martapura pada tahun 2012

    Suppression of Kondo effect in a quantum dot by external irradiation

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    We demonstrate that the external irradiation brings decoherence in the spin states of the quantum dot. This effect cuts off the Kondo anomaly in conductance even at zero temperature. We evaluate the dependence of the DC conductance in the Kondo regime on the power of irradiation, this dependence being determined by the decoherence.Comment: 4 pages, 1 figur

    Floquet states and persistent currents transitions in a mesoscopic ring

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    We consider the effect of an oscillating potential on the single-particle spectrum and the time-averaged persistent current of a one-dimensional phase-coherent mesoscopic ring with a magnetic flux. We show that in a ring with an even number of spinless electrons the oscillating potential has a strong effect on the persistent current when the excited side bands are close to the eigen levels of a pure ring. Resonant enhancement of side bands of the Floquet state generates a sign change of the persistent current.Comment: 2 figure

    Determination of the complex microwave photoconductance of a single quantum dot

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    A small quantum dot containing approximately 20 electrons is realized in a two-dimensional electron system of an AlGaAs/GaAs heterostructure. Conventional transport and microwave spectroscopy reveal the dot's electronic structure. By applying a coherently coupled two-source technique, we are able to determine the complex microwave induced tunnel current. The amplitude of this photoconductance resolves photon-assisted tunneling (PAT) in the non-linear regime through the ground state and an excited state as well. The out-of-phase component (susceptance) allows to study charge relaxation within the quantum dot on a time scale comparable to the microwave beat period.Comment: 5.5 pages, 6 figures, accepted by Phys. Rev. B (Jan. B15 2001

    Singularities, Lax degeneracies and Maslov indices of the periodic Toda chain

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    The n-particle periodic Toda chain is a well known example of an integrable but nonseparable Hamiltonian system in R^{2n}. We show that Sigma_k, the k-fold singularities of the Toda chain, ie points where there exist k independent linear relations amongst the gradients of the integrals of motion, coincide with points where there are k (doubly) degenerate eigenvalues of representatives L and Lbar of the two inequivalent classes of Lax matrices (corresponding to degenerate periodic or antiperiodic solutions of the associated second-order difference equation). The singularities are shown to be nondegenerate, so that Sigma_k is a codimension-2k symplectic submanifold. Sigma_k is shown to be of elliptic type, and the frequencies of transverse oscillations under Hamiltonians which fix Sigma_k are computed in terms of spectral data of the Lax matrices. If mu(C) is the (even) Maslov index of a closed curve C in the regular component of R^{2n}, then (-1)^{\mu(C)/2} is given by the product of the holonomies (equal to +/- 1) of the even- (or odd-) indexed eigenvector bundles of L and Lmat.Comment: 25 pages; published versio

    Nonlinear Response of a Kondo system: Direct and Alternating Tunneling Currents

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    Non - equilibrium tunneling current of an Anderson impurity system subject to both constant and alternating electric fields is studied. A time - dependent Schrieffer - Wolff transformation maps the time - dependent Anderson Hamiltonian onto a Kondo one. Perturbation expansion in powers of the Kondo coupling strength is carried out up to third order, yielding a remarkably simple analytical expression for the tunneling current. It is found that the zero - bias anomaly is suppressed by an ac - field. Both dc and the first harmonic are equally enhanced by the Kondo effect, while the higher harmonics are relatively small. These results are shown to be valid also below the Kondo temperature.Comment: 7 pages, RevTeX, 3 PS figures attached, the article has been significantly developed: time - dependent Schrieffer - Wolff transformation is presented in the full form, the results are applied to the change in the direct current induced by an alternating field (2 figures are new

    Resonant Photon-Assisted Tunneling Through a Double Quantum Dot: An Electron Pump From Spatial Rabi Oscillations

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    The time average of the fully nonlinear current through a double quantum dot, subject to an arbitrary combination of ac and dc voltages, is calculated exactly using the Keldysh nonequilibrium Green function technique. When driven on resonance, the system functions as an efficient electron pump due to Rabi oscillation between the dots. The pumping current is maximum when the coupling to the leads equals the Rabi frequency.Comment: 6 pages, REVTEX 3.0, 3 postscript figure

    Unconventional Superconductivity in Heavy Fermion Systems

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    We review the studies on the emergent phases of superconductvity and magnetism in the ff-electron derived heavy-fermion (HF) systems by means of the nuclear-quadrupole-resonance (NQR) under pressure. These studies have unraveled a rich variety of the phenomena in the ground state of HF systems. In this article, we highlight the novel phase diagrams of magnetism and unconventional superconductivity (SC) in CeCu2_2Si2_2, HF antiferromagnets CeRhIn5_5, and CeIn3_3. A new light is shed on the difference and common features on the interplay between magnetism and SC on the magnetic criticality.Comment: 15 pages, 13 figures, to appear in J. Phys. Soc. JPN, 74, No.1 (2005), special issue "Kondo Effect- 40 Years after the Discovery

    Scattering Theory of Photon-Assisted Electron Transport

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    The scattering matrix approach to phase-coherent transport is generalized to nonlinear ac-transport. In photon-assisted electron transport it is often only the dc-component of the current that is of experimental interest. But ac-currents at all frequencies exist independently of whether they are measured or not. We present a theory of photon-assisted electron transport which is charge and current conserving for all Fourier components of the current. We find that the photo-current can be considered as an up- and down-conversion of the harmonic potentials associated with the displacement currents. As an example explicit calculations are presented for a resonant double barrier coupled to two reservoirs and capacitively coupled to a gate. Two experimental situations are considered: in the first case the ac-field is applied via a gate, and in the second case one of the contact potentials is modulated. For the first case we show that the relative weight of the conduction sidebands varies with the screening properties of the system. In contrast to the non-interacting case the relative weights are not determined by Bessel functions. Moreover, interactions can give rise to an asymmetry between absorption and emission peaks. In the contact driven case, the theory predicts a zero-bias current proportional to the asymmetry of the double barrier. This is in contrast to the discussion of Tien and Gordon which, in violation of basic symmetry principles, predicts a zero-bias current also for a symmetric double barrier.Comment: 15 pages, 6 figures, REVTE
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