324 research outputs found

    Pengaruh Latihan Pliometrik Terhadap Hasil Tendangan Bola Siswa Sekolah Sepak Bola IKIP Semarang

    Full text link
    The purpose of this study is to test the effects of plyometric program on the distance of ball kick of the students of Soccer School, IKIP Semarang. This research was carried out by applying an experimental method. Sixty persons were taken as sample through random sampling procedure from 72 students of the soccer school. To test the hypothesis, analysis of variance was used. The results indicated that there was no significant difference between the linear plyometric program and non-linear on the distance of ball kick. There was a clear interaction found between plyometric program and the level of movement speed on the distance of ball kic

    Temperature Dependence of Blue Phosphorescent Cyclometalated Ir(III) Complexes

    Get PDF
    The photophysical properties for a series of facial (fac) cyclometalated Ir(III) complexes (fac-Ir(C^N)_3 (C^N = 2-phenylpyridyl (ppy), 2-(4,6-difluorophenyl)pyridyl (F2ppy), 1-phenylpyrazolyl (ppz), 1-(2,4-difluorophenyl)pyrazolyl) (F2ppz), and 1-(2-(9,9′-dimethylfluorenyl))pyrazolyl (flz)), fac-Ir(C^N)_2(C^N′) (C^N = ppz or F2ppz and C^N′ = ppy or F2ppy), and fac-Ir(CC′)_3 (C^C′ = 1-phenyl-3-methylbenzimidazolyl (pmb)) have been studied in dilute 2-methyltetrahydrofuran (2-MeTHF) solution in a temperature range of 77−378 K. Photoluminescent quantum yields (Φ) for the 10 compounds at room temperature vary between near zero and unity, whereas all emit with high efficiency at low temperature (77 K). The quantum yield for fac-Ir(ppy)_3 (Φ = 0.97) is temperature-independent. For the other complexes, the temperature-dependent data indicates that the luminescent efficiency is primarily determined by thermal deactivation to a nonradiative state. Activation energies and rate constants for both radiative and nonradiative processes were obtained using a Boltzmann analysis of the temperature-dependent luminescent decay data. Activation energies to the nonradiative state are found to range between 1600 and 4800 cm^−1. The pre-exponential factors for deactivation are large for complexes with C^N ligands (1011−1013 s^−1) and significantly smaller for fac-Ir(pmb)_3 (109 s^−1). The kinetic parameters for decay and results from density functional theory (DFT) calculations of the triplet state are consistent with a nonradiative process involving Ir−N (Ir−C for fac-Ir(pmb)_3) bond rupture leading to a five-coordinate species that has triplet metal-centered (^3MC) character. Linear correlations are observed between the activation energy and the energy difference calculated for the emissive and ^3MC states. The energy level for the ^3MC state is estimated to lie between 21700 and 24000 cm^−1 for the fac-Ir(C^N)_3 complexes and at 28000 cm^−1 for fac-Ir(pmb)_3

    Perencanaan Dan Pembuatan Modem Sebagai Alat Bantu Untuk Hubungan Antar Mikrokomputer IBM PC Melalui Saluran Telepon.

    Get PDF
    Modem berfungsi sebagai media pengirim dan penerima data dari suatu mikrokomputer, disamping itu modem juga dapat menerima dan mengirimkan dalam bentuk file. dalam perencanaan dan pembuatan peralatan modem saluran telepon yang dibuat ini menggunakan teknik modulasi QAM, transmisi asynchronous dan mempunyai kecepatan 9600 bps modem tersebut mempunyai karakteristik dengan type V.42 modem tersebut menggunakan dua buah IC yaitu IC 89C026FT dan IC 89027, IC 89C027FT berfungsi sebagai IC controller dari serial port komputer. IC 89027 berfungsi sebagai IC mode

    The Nature of the Hall Insulator

    Full text link
    We have conducted an experimental study of the linear transport properties of the magnetic-field induced insulating phase which terminates the quantum Hall (QH) series in two dimensional electron systems. We found that a direct and simple relation exists between measurements of the longitudinal resistivity, ρxx\rho_{xx}, in this insulating phase and in the neighboring QH phase. In addition, we find that the Hall resistivity, ρxy\rho_{xy}, can be quantized in the insulating phase. Our results indicate that a close relation exists between the conduction mechanism in the insulator and in the QH liquid.Comment: RevTeX, 4 pages, 4 figure

    Spontaneous Interlayer Charge Transfer near the Magnetic Quantum Limit

    Full text link
    Experiments reveal that a confined electron system with two equally-populated layers at zero magnetic field can spontaneously break this symmetry through an interlayer charge transfer near the magnetic quantum limit. New fractional quantum Hall states at unusual total filling factors such as \nu = 11/15 (= 1/3 + 2/5) stabilize as signatures that the system deforms itself, at substantial electrostatic energy cost, in order to gain crucial correlation energy by "locking in" separate incompressible liquid phases at unequal fillings in the two layers (e.g., layered 1/3 and 2/5 states in the case of \nu = 11/15).Comment: 4 pages, 4 figures (1 color) included in text. Related papers at http://www.ee.princeton.edu/~hari/papers.htm

    Resistivity peak values at transition between fractional quantum Hall states

    Full text link
    Experimental data available in the literature for peak values of the diagonal resistivity in the transitions between fractional quantum Hall states are compared with the theoretical predictions. It is found that the majority of the peak values are close to the theoretical values for two-dimensional systems with moderate mobilities.Comment: 3 pages, 1 figur

    Quantum Correlated Interstitials and the Hall Resistivity of the Magnetically Induced Wigner Crystal

    Full text link
    We study a trial wavefunction for an interstitial in a Wigner crystal. We find that the electron correlations, ignored in a conventional Hartree-Fock treatment, dramatically lower the interstitial energy, especially at fillings close to an incompressible liquid state. The correlation between the interstitial electron and the lattice electrons at ν<1/m\nu <1/m is introduced by constructing a trial wave- function which bears a Jastrow factor of a Laughlin state at ν=1/m\nu=1/m. For fillings close to but just below ν=1/m\nu=1/m, we find that a perfect Wigner crystal becomes unstable against formation of such interstitials. It is argued that conduction due to correlated interstitials in the presence of weak disorder leads to the {\it classical} Hall resistivity, as seen experimentally.Comment: 10 pages, RevTe

    The Quantized Hall Insulator: A New Insulator in Two-Dimensions

    Full text link
    Quite generally, an insulator is theoretically defined by a vanishing conductivity tensor at the absolute zero of temperature. In classical insulators, such as band insulators, vanishing conductivities lead to diverging resistivities. In other insulators, in particular when a high magnetic field (B) is added, it is possible that while the magneto-resistance diverges, the Hall resistance remains finite, which is known as a Hall insulator. In this letter we demonstrate experimentally the existence of another, more exotic, insulator. This insulator, which terminates the quantum Hall effect series in a two-dimensional electron system, is characterized by a Hall resistance which is approximately quantized in the quantum unit of resistance h/e^2. This insulator is termed a quantized Hall insulator. In addition we show that for the same sample, the insulating state preceding the QHE series, at low-B, is of the HI kind.Comment: 4 page

    Wigner Crystalization in the Lowest Landau Level for ν1/5\nu \ge 1/5

    Full text link
    By means of exact diagonalization we study the low-energy states of seven electrons in the lowest Landau level which are confined by a cylindric external potential modelling the rest of a macroscopic system and thus controlling the filling factor ν\nu . Wigner crystal is found to be the ground state for filling factors between ν=1/3 \nu = 1/3 and ν=1/5 \nu = 1/5 provided electrons interact via the bare Coulomb potential. Even at ν=1/5\nu =1/5 the solid state has lower energy than the Laughlin's one, although the two energies are rather close. We also discuss the role of pseudopotential parameters in the lowest Landau level and demonstrate that the earlier reported gapless state, appearing when the short-range part of the interaction is suppressed, has nothing in common with the Wigner crystalization in pure Coulomb case.Comment: 9 pages, LaTex, 8 figure

    Modular Invariant Partition Functions in the Quantum Hall Effect

    Get PDF
    We study the partition function for the low-energy edge excitations of the incompressible electron fluid. On an annular geometry, these excitations have opposite chiralities on the two edges; thus, the partition function takes the standard form of rational conformal field theories. In particular, it is invariant under modular transformations of the toroidal geometry made by the angular variable and the compact Euclidean time. The Jain series of plateaus have been described by two types of edge theories: the minimal models of the W-infinity algebra of quantum area-preserving diffeomorphisms, and their non-minimal version, the theories with U(1)xSU(m) affine algebra. We find modular invariant partition functions for the latter models. Moreover, we relate the Wen topological order to the modular transformations and the Verlinde fusion algebra. We find new, non-diagonal modular invariants which describe edge theories with extended symmetry algebra; their Hall conductivities match the experimental values beyond the Jain series.Comment: Latex, 38 pages, 1 table (one minor error has been corrected
    corecore