15,286 research outputs found

    High speed polymer E-O modulator consisting of a MZI with a microring resonator

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    A Mach-Zehnder interferometer with an polymer electro-optic micro-ring resonator on one of its branches is realized in a polymer layerstack and characterized. Electro-optic coefficients of 10 pm/V and modulation frequencies of 1 GHz were measured

    A novel high-speed polymeric EO modulator based on a combination of a microring resonator and an MZI

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    A Mach-Zehnder interferometer with an electrooptic polymer mircroring resonator adjacent to one of its branches is realized in a polymer layer stack. The microresonator is defined by reactive ion etching in the nonlinear PMMA-DR1 polymer and waveguide definition is done without etching, by using a negative photoresist (SU8) as waveguide layer. Electrooptic coefficients of 10 pm/V and modulation frequencies of 1 GHz were measured

    Feshbach-Einstein condensates

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    We investigate the phase diagram of a two-species Bose-Hubbard model describing atoms and molecules on a lattice, interacting via a Feshbach resonance. We identify a region where the system exhibits an exotic super-Mott phase and regions with phases characterized by atomic and/or molecular condensates. Our approach is based on a recently developed exact quantum Monte Carlo algorithm: the Stochastic Green Function algorithm with tunable directionality. We confirm some of the results predicted by mean-field studies, but we also find disagreement with these studies. In particular, we find a phase with an atomic but no molecular condensate, which is missing in all mean-field phase diagrams.Comment: 4 pages, 6 figure

    Beyond the 2nd Fermi Pulsar Catalog

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    Over thirteen times more gamma-ray pulsars have now been studied with the Large Area Telescope on NASA's Fermi satellite than the ten seen with the Compton Gamma-Ray Observatory in the nineteen-nineties. The large sample is diverse, allowing better understanding both of the pulsars themselves and of their roles in various cosmic processes. Here we explore the prospects for even more gamma-ray pulsars as Fermi enters the 2nd half of its nominal ten-year mission. New pulsars will naturally tend to be fainter than the first ones discovered. Some of them will have unusual characteristics compared to the current population, which may help discriminate between models. We illustrate a vision of the future with a sample of six pulsars discovered after the 2nd Fermi Pulsar Catalog was written.Comment: 6 pages, to appear in the proceedings of "The Fast and the Furious: Energetic Phenomena in Isolated Neutron Stars, Pulsar Wind Nebulae and Supernova Remnants",ESAC, Madrid, Spain, 22 - 24 May 2013 http://xmm.esac.esa.int/external/xmm_science/workshops/2013_science/, to be published as a regular issue of the Astronomische Nachrichten / Astronomical Notes (AN

    Development of a 75-watt 60-GHz traveling-wave tube for intersatellite communications

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    This program covers the initial design and development of a 75 watt, 60 GHz traveling-wave tube for intersatellite communications. The objective frequency band was 59 to 64 GHz, with a minimum tube gain of 35 dB. The objective overall efficiency at saturation was 40 percent. The tube, designated the 961H, used a coupled-cavity interaction circuit with periodic permanent magnet beam focusing to minimize the weight. For efficiency enhancement, it incorporated a four-stage depressed collector capable of radiation cooling in space. The electron gun had a low-temperature (type-M) cathode and an isolated anode. Two tubes were built and tested; one feasibility model with a single-stage collector and one experimental model that incorporated the multistage collector

    Polaron relaxation in ferroelectric thin films

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    We report a dielectric relaxation in ferroelectric thin films of the ABO3 family. We have compared films of different compositions with several growth modes: sputtering (with and without magnetron) and sol-gel. The relaxation was observed at cryogenic temperature (T<100K) for frequencies from 100Hz up to 10MHz. This relaxation activation energy is always lower than 200meV. It is very similar to the polaron relaxation that we reported in the parent bulk perovskites. Being independent of the materials size, morphology and texture, this relaxation can be a useful probe of defects in actual integrated capacitors with no need for specific shapin

    Analyzing the Response to COVID-19 in Pennsylvania State Correctional Institutions

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    To evaluate the effects of the COVID-19 outbreak on the Pennsylvania prison system, I collected data from the Pennsylvania Department of Corrections, the Pennsylvania Department of Health, and the Marshall Project. I supplemented the data with opinion pieces and journal articles discussing the specific issues that this pandemic imposes upon prisons in the United States. In sum, population data collected from the Department of Corrections showed that only a few State Correctional Institutions saw a steady decrease in population over the 25 day study period from from June 18th through July 13th (Pennsylvania Department of Corrections, 2020). Combining testing data collected in part from the DOC and in part from the Department of Health, I compared testing rates of surrounding communities (Pennsylvania Department of Health, 2020 & PA DOC, 2020). The Marshall Project data demonstrates that testing rates are higher and COVID-19 diagnosis rates are lower among incarcerated persons than among the general population (The Marshall Project, 2020). However, this finding did not hold true for correctional staff, who had a higher rate of diagnosis coupled with a lower testing rate compared to all of Pennsylvania (The Marshall Project, 2020)

    The Role of Cannabinoids and Terpenes in Cannabis Mediated Analgesia in Rats

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    Objective: This research examined the contributions of terpenes (volatile oil) and cannabinoids in cannabis mediated analgesia in rats. Methods: In experiment 1, separate groups of rats received IP administration of either vehicle, 5, 10, or 15 mg/kg cannabis extract, one of three concentrations of volatile oil alone in these cannabis extracts, one of three concentrations of these extracts with volatile oils removed, 2.5, 5, or 7.5 mg/kg Δ9-THC, or 10 or 18 mg/kg morphine 30 m before hotplate and tail-flick tests of thermal nociception. One week later, separate groups of rats received a second administration of these test articles IP 30 m before testing in the acetic acid writhing test of inflammatory nociception. Results: Both tail-flick and hotplate latencies were longer than controls for all drug groups/doses except the isolated volatile oil groups. The 15 mg/kg dose of the cannabis extract and 7.5mg/kg Δ9 -THC group showed analgesic effects similar to the 18 mg/kg morphine group. In the inflammatory nociceptive assay, all drug groups/doses showed decreased writhes compared to the control except the isolated volatile oil groups. Conclusions: These tests revealed that terpenes do not significantly contribute to the analgesic action of cannabis extracts. Further, these tests revealed that THC alone produced robust analgesia equivalent to the whole cannabis extract. This leads to the conclusion that THC alone mediates these analgesic actions of cannabis extracts and other components do not significantly affect the analgesic activity of the extract

    Superfluid and Mott Insulator phases of one-dimensional Bose-Fermi mixtures

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    We study the ground state phases of Bose-Fermi mixtures in one-dimensional optical lattices with quantum Monte Carlo simulations using the Canonical Worm algorithm. Depending on the filling of bosons and fermions, and the on-site intra- and inter-species interaction, different kinds of incompressible and superfluid phases appear. On the compressible side, correlations between bosons and fermions can lead to a distinctive behavior of the bosonic superfluid density and the fermionic stiffness, as well as of the equal-time Green functions, which allow one to identify regions where the two species exhibit anticorrelated flow. We present here complete phase diagrams for these systems at different fillings and as a function of the interaction parameters.Comment: 8 pages, 12 figure
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