15,956 research outputs found
High speed polymer E-O modulator consisting of a MZI with a microring resonator
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
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
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
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
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
Analyzing the Response to COVID-19 in Pennsylvania State Correctional Institutions
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
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
Polaron relaxation in ferroelectric thin films
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
Superfluid and Mott Insulator phases of one-dimensional Bose-Fermi mixtures
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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