The longitudinal resistance of a quantum Hall system with a density gradient

Following recent experiments, we consider current flow in two dimensional electronic systems in the quantum Hall regime where a gradient in the electron density induces a spatial variation in the Hall resistivity. Describing the system in terms of a spatially varying local resistivity tensor, we show that in such a system the current density is generically non-uniform, with the current being pushed towards one side of the sample. We show that, for sufficiently large density gradient, the voltage along that side is determined by the change of the Hall resistivity, and is independent of the microscopic longitudinal resistivity, while the voltage on the opposite side is small and determined by both longitudinal and Hall resistivities. We solve some particular models in detail, and propose ways by which the microscopic longitudinal resistivity may be extracted from measurements of the longitudinal voltage on both sides of the sample.Comment: 9 pages, 3 figure

Kesiapan Profesi Personal Trainer Dalam Penyusunanprogram Latihan Dan Jasa Layanan Yang Diberikanpada Members Fitness Di YOGYAKARTA

Penelitian ini bertujuan untuk mengetahui kesiapan profesi personal trainer dalampenyusunan program latihan dan jasa layanan yang diberikan pada members fitness diYogyakarta.Penelitian ini merupakan penelitian deskriptif menggunakan metode survei denganinstrumen angket. Metode pengambilan sampel yang digunakan pada penelitian iniadalah insidental sampling pada personal trainer di Yogyakarta yang meliputikabupaten Sleman, kabupaten Bantul dan kota Yogyakarta dengan jumlah 41 orang.Untuk menganalisis data digunakan statistik deskriptif dengan persentase.Hasil penelitian menunjukkan bahwa dari 41 responden, sebanyak 1 responden(2,4 %) berkategori baik, 19 responden (46,3 %) pada kategori cukup baik, 18responden (43,9 %) berkategori kurang baik, dan 3 responden (7,4 %) berada padakategori tidak baik. Dilihat dari hasil penelitian mayoritas responden berada padakategori cukup baik (46,3 %). Berdasarkan hasil terebut diketahui kesiapan profesipersonal trainer dalam penyusunan program latihan dan jasa layanan yang diberikanpada members fitness di Yogyakarta adalah cukup baik

Generation of the second-harmonic Bessel beams via nonlinear Bragg diffraction

We generate conical second-harmonic radiation by transverse excitation of a two-dimensional annular periodically-poled nonlinear photonic structure with a fundamental Gaussian beam. We show that these conical waves are the far-field images of the Bessel beams generated in a crystal by parametric frequency conversion assisted by nonlinear Bragg diffraction.Comment: 4 pages, 5 figures. submitte

Photonic quasicrystals for general purpose nonlinear optical frequency conversion

We present a general method for the design of 2-dimensional nonlinear photonic quasicrystals that can be utilized for the simultaneous phase-matching of arbitrary optical frequency-conversion processes. The proposed scheme--based on the generalized dual-grid method that is used for constructing tiling models of quasicrystals--gives complete design flexibility, removing any constraints imposed by previous approaches. As an example we demonstrate the design of a color fan--a nonlinear photonic quasicrystal whose input is a single wave at frequency $\omega$ and whose output consists of the second, third, and fourth harmonics of $\omega$, each in a different spatial direction

Hubungan Motivasi Berprestasi, Prilaku Kepemimpinan Kepala Sekolah Dan Etos Kerja Dengan Kinerja Guru Di SMA N 1 Kubutambahan

This study aimed to determine: (1) the relationship between achievement motivation with teacher performance in SMA N 1 Kubutambahan, (2) the relationship between principal leadership behaviors with teacher performance in SMA N 1 Kubutambahan, (3) the relationship between the performance of the teachers work ethic in SMA N 1 Kubutambahan, (4) simultaneous relationship between achievement motivation, school leadership and work ethic with the performance of teachers in SMA N 1 Kubutambahan. This study was designed with a correlational design ex-post facto by using a quantitative approach.The study population was all teachers in SMA N 1 Kubutambahan. The sample retrieval technique using census study with the number 47. Data were collected by questionnaires. Data were analyzed by multiple regression and partial analysis. The results showed that: (1) there is a significant contribution to the achievement motivation with teacher performance through the regression equation Y = 95.582 + 0.669 X1 (p <0.05) with a contribution of 44.6% and the effective contribution of 18.26%, (2) there is a significant contribution between principal leadership behaviors with teacher performance through the regression equation Y = 91.918 + 0.705 X2 (p <0.05) with a contribution of 59.7% and the effective contribution of 35.95%, (3) there is a significant contribution to the work ethos of teacher performance through the regression equation Y = 83.236 + 0.762 X3 (p <0.05) with a contribution of 41.9% and the effective contribution of 18.07%, (4) there is a significant contribution between achievement motivation, school leadership behavior, and work ethos simultaneously with the performance of teachers of SMAN I Kubutambahan. through the regression equation Y = 55.794 + 0.274 X1 + 0.425 X2 + 0.328 X3 (p <0.05) with a contribution of 72.3%

Coulomb drag at \nu = 1/2: Composite fermion pairing fluctuations

We consider the Coulomb drag between two two-dimensional electron layers at filling factor \nu = 1/2 each, using a strong coupling approach within the composite fermion picture. Due to an attractive interlayer interaction, composite fermions are expected to form a paired state below a critical temperature T_c. We find that above T_c pairing fluctuations make the longitudinal transresistivity \rho_D increase with decreasing temperature. The pairing mechanism we study is very sensitive to density variations in the two layers, and to an applied current. We discuss possible relation to an experiment by Lilly et al. [Phys. Rev. Lett. 80, 1714 (1998)].Comment: REVTeX, 4 pages, 1 figur

Spin orbit effects in a GaAs quantum dot in a parallel magnetic field

We analyze the effects of spin-orbit coupling on fluctuations of the conductance of a quantum dot fabricated in a GaAs heterostructure. We argue that spin-orbit effects may become important in the presence of a large parallel magnetic field B_{||}, even if they are negligble for B_{||}=0. This should be manifest in the level repulsion of a closed dot, and in reduced conductance fluctuations in dots with a small number of open channels in each lead, for large B_{||}. Our picture is consistent with the experimental observations of Folk et al.Comment: 5 page

Dissipationless transport in low density bilayer systems

In a bilayer electronic system the layer index may be viewed as the z-component of an isospin-1/2. An XY isospin-ordered ferromagnetic phase was observed in quantum Hall systems and is predicted to exist at zero magnetic field at low density. This phase is a superfluid for opposite currents in the two layers. At B=0 the system is gapless but superfluidity is not destroyed by weak disorder. In the quantum Hall case, weak disorder generates a random gauge field which probably does not destroy superfluidity. Experimental signatures include Coulomb drag and collective mode measurements.Comment: 4 pages, no figures, submitted to Phys. Rev. Let

Nonlinear diffraction from a virtual beam

We observe experimentally a novel type of nonlinear diffraction in the process of two-wave mixing on a nonlinear quadratic grating. We demonstrate that when the nonlinear grating is illuminated simultaneously by two noncollinear beams, a second-harmonic diffraction pattern is generated by a virtual beam propagating along the bisector of the two pump beams. The observed diffraction phenomena is a purely nonlinear effect that has no analogue in linear diffraction