1,865 research outputs found

    Statistics of conductance and shot-noise power for chaotic cavities

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    We report on an analytical study of the statistics of conductance, gg, and shot-noise power, pp, for a chaotic cavity with arbitrary numbers N1,2N_{1,2} of channels in two leads and symmetry parameter β=1,2,4\beta = 1,2,4. With the theory of Selberg's integral the first four cumulants of gg and first two cumulants of pp are calculated explicitly. We give analytical expressions for the conductance and shot-noise distributions and determine their exact asymptotics near the edges up to linear order in distances from the edges. For 0<g<10<g<1 a power law for the conductance distribution is exact. All results are also consistent with numerical simulations.Comment: 7 pages, 3 figures. Proc. of the 3rd Workshop on Quantum Chaos and Localisation Phenomena, Warsaw, Poland, May 25-27, 200

    Operational multipartite entanglement classes for symmetric photonic qubit states

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    We present experimental schemes that allow to study the entanglement classes of all symmetric states in multiqubit photonic systems. In addition to comparing the presented schemes in efficiency, we will highlight the relation between the entanglement properties of symmetric Dicke states and a recently proposed entanglement scheme for atoms. In analogy to the latter, we obtain a one-to-one correspondence between well-defined sets of experimental parameters and multiqubit entanglement classes inside the symmetric subspace of the photonic system.Comment: 5 pages, 1 figur

    Thermogeologic mapping of the Moon from lunar orbit

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    The Infrared Scanning Radiometer (ISR) onboard the Apollo 17 Command-Service Module (CSM) mapped thermal emission of the lunar surface from orbit. Measured temperature values span the diurnal range of lunar temperatures (85 K to 400 K) and have an accuracy of approximately plus or minus 2 K. Surface spatial resolution at nadir is 2.2 km. This Apollo data is being revisited using data presentation software for the Macintosh computer, which was not available 20 years ago, even on mainframes. The new thermal images exhibit subtleties in the delineation of geophysical surface units that were unappreciated in the original survey of the data. Looking first at nighttime thermal emission from the ground tracks over Oceanus Procellarum to Mare Orientale, we have confirmed and expanded on earlier observations of regolith differences between mare and highlands and of a scheme for relative age-dating of larger impact craters of the Copernican age. We see an impact crater near Lenz, just north of Orientale, which exhibits an extraordinarily fresh ejecta blanket. Photography of this area is extremely poor, but we can see the feature in the Galileo data. We plan to derive geophysical surface properties of the overflown region using thermal models of regolith structures

    Quantum entanglement and teleportation in pulsed cavity-optomechanics

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    Entangling a mechanical oscillator with an optical mode is an enticing and yet a very challenging goal in cavity optomechanics. Here we consider a pulsed scheme to create Einstein-Podolsky-Rosen-type entanglement between a traveling-wave light pulse and a mechanical oscillator. The entanglement can be verified unambiguously by a pump-probe sequence of pulses. In contrast to schemes that work in a steady-state regime under a continuous-wave drive, this protocol is not subject to stability requirements that normally limit the strength of achievable entanglement. We investigate the protocol's performance under realistic conditions, including mechanical decoherence, in full detail. We discuss the relevance of a high mechanical Qf product for entanglement creation and provide a quantitative statement on which magnitude of the Qf product is necessary for a successful realization of the scheme. We determine the optimal parameter regime for its operation and show it to work in current state-of-the-art systems.Comment: 10 pages, 2 figure

    The Effects of Positive Behavior Interventions and Supports in the Elementary Classroom

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    The benefits of Positive Behavioral Interventions and Supports (PBIS) are being recognized in education for helping reduce misbehaviors. This paper includes research from three primary classrooms: kindergarten, first grade music, and second grade. Data was collected over the course of six weeks. Teachers recorded the number of times each student received a warning, consequence for misbehavior, positive behavior slip, or demonstrated a misbehavior using individual student tracking sheets, tally sheets, and a reflection journal. Throughout the six weeks, students were given a check-in sheet to record their understanding and learning of the behavior system. Students recorded a much greater understanding of behavior expectations and intervention strategies over the course of the research. The results showed a slight decrease in misbehaviors. Teachers suggested beginning the behavioral intervention at the beginning of the year and implementing PBIS for a longer period of time to note more positive changes in behaviors

    New, extended hairpin form of the TAR-2 RNA domain points to the structural polymorphism at the 5′ end of the HIV-2 leader RNA

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    The HIV-2 TAR RNA domain (TAR-2) plays a key role in the trans-activation of HIV-2 transcription as it is the target for the Tat-2 protein and several cell factors. Here, we show that the TAR-2 domain exists in vitro in two global, alternative forms: a new, extended hairpin form with two conformers and the already proposed branched hairpins form. This points strongly to the structural polymorphism of the 5′ end of the HIV-2 leader RNA. The evidence comes from the non-denaturing PAGE mobility assay, 2D structure prediction, enzymatic and Pb(2+)- or Mg(2+)-induced RNA cleavages. Existence of the TAR-2 extended form was further proved by the examination of engineered TAR-2 mutants stabilized either in the branched or extended structure. The TAR-2 extended form predominates with an increasing magnesium concentration. Gel retardation assays reveal that both TAR-2 wt and its mutant, unable to form branched structure, bind Tat-2 protein with comparable, high affinity, while RNA hairpins I and II, derived from TAR-2 branched structure model, show much less protein binding. We propose that an internal loop region of the TAR-2 extended hairpin form is a potential Tat-2 binding site
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