10,663 research outputs found

    A Model for Judicial Leadership: Community Responses to Juvenile Substance Abuse

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    Outlines the Reclaiming Futures initiative, which brings juvenile courts and systems of care together under judges' leadership in a team effort toward systemic change. Offers lessons learned, guidance, and recommendations for starting similar projects

    Cooling Fermions in an Optical Lattice by Adiabatic Demagnetization

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    The Fermi-Hubbard model describes ultracold fermions in an optical lattice and exhibits antiferromagnetic long-ranged order below the N\'{e}el temperature. However, reaching this temperature in the lab has remained an elusive goal. In other atomic systems, such as trapped ions, low temperatures have been successfully obtained by adiabatic demagnetization, in which a strong effective magnetic field is applied to a spin-polarized system, and the magnetic field is adiabatically reduced to zero. Unfortunately, applying this approach to the Fermi-Hubbard model encounters a fundamental obstacle: the SU(2)SU(2) symmetry introduces many level crossings that prevent the system from reaching the ground state, even in principle. However, by breaking the SU(2)SU(2) symmetry with a spin-dependent tunneling, we show that adiabatic demagnetization can achieve low temperature states. Using density matrix renormalization group (DMRG) calculations in one dimension, we numerically find that demagnetization protocols successfully reach low temperature states of a spin-anisotropic Hubbard model, and we discuss how to optimize this protocol for experimental viability. By subsequently ramping spin-dependent tunnelings to spin-independent tunnelings, we expect that our protocol can be employed to produce low-temperature states of the Fermi-Hubbard Model.Comment: References adde

    A Cross-National Examination of Expected Correlation of Computer Ethical Perceptions and User Computer Attitudes

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    This study examined computer ethical perceptions and computer use attitudes among three differing groups consisting of nationalities from the United States, Singapore and Hong Kong. The purpose of the study was to determine if computer attitudes have a moderating effect on the perceptions of computer ethical use across multiple cultural backgrounds. Evidence supporting this claim would add additional insight into previously discovered differences. This study found limited support for the suggested hypotheses, but confirmed fundamental cultural differences. Future research should examine other variables to determine if significant effects can be determined from unexamined variable

    Spontaneous dressed-state polarization in the strong driving regime of cavity QED

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    We utilize high-bandwidth phase quadrature homodyne measurement of the light transmitted through a Fabry-Perot cavity, driven strongly and on resonance, to detect excess phase noise induced by a single intracavity atom. We analyze the correlation properties and driving-strength dependence of the atom-induced phase noise to establish that it corresponds to the long-predicted phenomenon of spontaneous dressed-state polarization. Our experiment thus provides a demonstration of cavity quantum electrodynamics in the strong driving regime, in which one atom interacts strongly with a many-photon cavity field to produce novel quantum stochastic behavior.Comment: 4 pages, 4 color figure

    Effects of diamagnetic levitation on bacterial growth in liquid

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    Diamagnetic levitation is a technique that uses a strong, spatially-varying magnetic field to levitate diamagnetic materials, such as water and biological cells. This technique has the potential to simulate aspects of weightlessness, on the Earth. In common with all ground-based techniques to simulate weightlessness, however, there are effects introduced by diamagnetic levitation that are not present in space. Since there have been few studies that systematically investigate these differences, diamagnetic levitation is not yet being fully exploited. For the first time, we critically assess the effect of diamagnetic levitation on a bacterial culture in liquid. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 hours, in a series of experiments to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture. The speed of sedimentation of the bacterial cells to the bottom of the container is considerably reduced. Further experiments and microarray gene analysis show that the growth enhancement is due to greater oxygen availability in the magnetically levitated sample. We demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid, an effect not present in microgravity. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause the liquid to become unstable to convection when the consumption of oxygen by the bacteria generates an oxygen concentration gradient. We propose that this convection enhances oxygen availability by transporting oxygen around the sample. Since convection is absent in space, these results are of significant importance and timeliness to researchers considering using diamagnetic levitation to explore weightless effects on living organisms and a broad range of other topics in the physical and life sciences

    Optical Spectroscopy of Bright Fermi LAT Blazars

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    We report on HET and Palomar 5 m spectroscopy of recently identified γ\gamma-ray blazars in the {\it Fermi} LAT Bright Source List. These data provide identifications for 10 newly discovered γ\gamma-ray flat spectrum radio quasars (FSRQ) and six new BL Lacs plus improved spectroscopy for six additional BL Lacs. We substantially improve the identification completeness of the bright LAT blazars and give new redshifts and zz constraints, new estimates of the black hole masses and new measurements of the optical SED.Comment: 8 pages, 5 figures, 2 tables. Accepted for publication in Ap

    PROCESS-CONTROL EFFECTS FOR TEAM-BASEDCOMPUTER-MEDIATED DECISION ANALYSES

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    As the evolution of research in Group Support Systems (GSS) continues, focus must begin to shift away from the concentration of GSS groups versus non-GSS groups, and begin to direct scrutiny toward the examination of the group dynamics that influence the experience of the teams that use GSS. The literature has clearly established that GSS improves the quality of certain decisions. The new challenge is to discover what processes within GSS are responsible for decision improvement and how they interact with other group processes extant in work situation

    Identification of the water quality factors which prevent fingernail clams from recolonizing the Illinois River—phase III

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    TECHNICAL COMPLETION REPORT Project No. B-124-ILL Agreement No. 14-34-0001-0217The purpose of this research was to determine why fingernail clams have been unable to recolonize a 100-mile reach of the Illinois River where they were abundant prior to a die-off in the 1950's. Fingernail clams are major links in food chains leading from detritus and algae to higher level consumers valued by man, such as fish and water fowl. Three suspected toxicants and sediments from the reach where the die-off occurred were tested on intact fingernail clams (Musculium transversum) and gill preparations isolated from the clams. Concentrations of fluoride, lead and cadmium which caused a 50% reduction in the rate of beating of cilia on isolated clam gills, after 10 minutes of exposure (10-minute EC50), were 0.75, 0.02 and 0.06 mg/l , respectively. Mixtures of cadmium and fluoride were slightly more toxic to clam gills than predicted from results of bioassays with single toxicants. A fluoride concentration of 2.82 mg/l killed intact fingernail clams after eight weeks of exposure, while mortality in lesser concentrations and one higher concentration did not differ significantly from controls maintained in well water to which no fluoride had been added. Hence, the sub-lethal response exhibited by the gills is at least four times more sensitive than the lethal response. Maximum fluoride concentrations reported by the U.S. Geological Survey at two stations in the Illinois River ranged from .6 to .8 mg/l between 1979 and 1981, considerably below the concentrations which affected growth and survival of intact clams during 8-week exposures in our laboratory, but slightly above the level which affected isolated clam gills. A lead bioassay using intact clams was completed, but the results were ambiguous because concentration ranges in separate test chambers overlapped. In addition, insoluble lead precipitates accumulated in the test chambers, and the relative toxicity to clams of the soluble versus the insoluble lead was not determined. Until additional bioassays are completed, it is impossible to determine whether the maximum total lead concentrations of 0.40 mg/l which occurred in the Illinois River between 1979 and 1981 could have contributed to the failure of fingernail clams to recolonize the river. Fingernail clams exposed to sediments from lakes along the Illinois River suffered greater mortality after six weeks of exposure than clams exposed to sediment from the Mississippi River, although the differences were not statistically significant. The same sediments tested on clam gills produced statistically significant changes in ciliary beating rate and particle transport rates on the gills. Sediments from the upstream lakes cause a greater depression in the particle transport rate and ciliary beating rates than sediments from downstream lakes. In addition, sediments from the lake furthest upstream caused a drastic change from the normal metachronal beating pattern to an atypical synchronous pattern. The results with the gill assay suggest that sediments in the Illinois River contain unidentified toxic factors and that sediments in the upper river, closer to the metropolitan areas of Joliet and Chicago, are more toxic than sediments further downstream. These results should be confirmed by additional tests with intact clams, including field tests with caged organisms. Parallel chemical analyses and bioassays of extracts from the sediments should be performed to identify the toxic components.U.S. Department of the InteriorU.S. Geological SurveyOpe
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