273 research outputs found

    Creative Destruction in the Information Age: The Fallout on America\u27s Latino Communities

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    The 104th Congress is in the midst of the first wholesale reform of telecommunications regulation in one-half century. The new regulatory framework emerging in the Republican-controlled Congress, if enacted, will usher in a radically deregulated, market-driven telecom environment, one in which the benefits of the emerging national information infrastructure will likely be distributed differentially, based on ethnicity and socio-economic status. Many U.S. residents may actually be charged higher rates for essential telecommunication services after deregulation (just as they did when cable television was deregulated), which may force many vulnerable users off the network. In addition, the concentration of media ownership eschews the viability of greater minority control of telecommunications and media outlets. The irony then is that although advanced, interactive technologies promise empowerment and choice, a laissez-faire approach to reform may exacerbate fault lines in the information society between those who are already advantaged and less affluent ethnic and racial minorities

    Knockout of proton-neutron pairs from 16^{16}O with electromagnetic probes

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    After recent improvements to the Pavia model of two-nucleon knockout from 16^{16}O with electromagnetic probes the calculated cross sections are compared to experimental data from such reactions. Comparison with data from a measurement of the 16^{16}O(e,e′'pn) reaction show much better agreement between experiment and theory than was previously observed. In a comparison with recent data from a measurement of the 16^{16}O(γ\gamma,pn) reaction the model over-predicts the measured cross section at low missing momentum.Comment: 6 pages, 5 figure

    uvby(-β\beta) photometry of high-velocity and metal-poor stars X. Stars of very low metal abundance: observations, reddenings, metallicities, classifications, distances, and relative ages

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    uvby(--β\beta) photometry has been obtained for an additional 411 very metal-poor stars selected from the HK survey, and used to derive basic parameters such as interstellar reddenings, metallicities, photometric classifications, distances, and relative ages... These very metal-poor stars are compared to M92 in the c_0,(b-y)_0 diagram, and evidence is seen for field stars 1-3 Gyrs younger than this globular cluster. The significance of these younger very metal-poor stars is discussed in the context of Galactic evolution, mentioning such possibilities as hierarchical star-formation/mass-infall of very metal-poor material and/or accretion events whereby this material has been acquired from other (dwarf) galaxies with different formation and chemical-enrichment historiesComment: 20 pages, 11 figures, and 9 table

    Shadowing in Inelastic Scattering of Muons on Carbon, Calcium and Lead at Low XBj

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    Nuclear shadowing is observed in the per-nucleon cross-sections of positive muons on carbon, calcium and lead as compared to deuterium. The data were taken by Fermilab experiment E665 using inelastically scattered muons of mean incident momentum 470 GeV/c. Cross-section ratios are presented in the kinematic region 0.0001 < XBj <0.56 and 0.1 < Q**2 < 80 GeVc. The data are consistent with no significant nu or Q**2 dependence at fixed XBj. As XBj decreases, the size of the shadowing effect, as well as its A dependence, are found to approach the corresponding measurements in photoproduction.Comment: 22 pages, incl. 6 figures, to be published in Z. Phys.

    Lambda and Antilambda polarization from deep inelastic muon scattering

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    We report results of the first measurements of Lambda and Antilambda polarization produced in deep inelastic polarized muon scattering on the nucleon. The results are consistent with an expected trend towards positive polarization with increasing x_F. The polarizations of Lambda and Antilambda appear to have opposite signs. A large negative polarization for Lambda at low positive x_F is observed and is not explained by existing models.A possible interpretation is presented.Comment: 9 pages, 2 figure

    The influence of age on the female/male ratio of treated incidence rates in depression

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    BACKGROUND: Poor data exist on the influence of psychosocial variables on the female/male ratio of depression because of the small number of cases and the resulting limited numbers of variables available for investigation. For this investigation a large number of first admitted depressed patients (N = 2599) was available which offered the unique opportunity to calculate age specific sex ratios for different marital and employment status categories. METHODS: Age and sex specific population based depression rates were calculated for first ever admissions for single year intervals. Moving averages with interpolated corrections for marginal values in the age distribution were employed. RESULTS: For the total group the female/male ratio of depression showed an inverted U-shape over the life-cycle. This pattern was influenced by the group of married persons, which showed a sex-ratio of 3:1 between the age of 30–50, but ratios of around 1:1 at younger and older ages. For not married persons the female/male ratio was already around 2:1 at the age of 18 and rose to 2.5:1 in mid-life and declined to 1 at around 55. The almost parallel decline of depression rates in employed men and women resulted in a female/male ratio of about 2:1 from age 18 to age 50 and became 1 after the age of 60. The female/male ratio among the not employed was about 1, in mid-life it became negative. CONCLUSIONS: Our analyses show that the gender-gap in first admitted depressed patients is age dependent and that psychosocial factors modify the sex ratio

    Measurements of 12C(&#8594;γ,pp) photon asymmetries for Eγ= 200–450 MeV

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    The 12C (&#8594;γ ,pp) reaction has been studied in the photon energy range 200-450 MeV at the Mainz microtron MAMI-C, where linearly polarised photons were energy-tagged using the Glasgow-Mainz Tagged Photon Spectrometer and protons were detected in the Crystal Ball detector. The photon asymmetry Σ has been measured over a wider Eγ range than previous measurements. The strongest asymmetries were found at low missing energies where direct emission of nucleon pairs is expected. Cuts on the difference in azimuthal angles of the two ejected protons increased the magnitude of the observed asymmetries. At low missing energies the Σ data exhibit a strong angular dependence, similar to deuteron photodisintegration

    The ARCH Projects: design and rationale (IAASSG 001)

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    OBJECTIVE A number of factors limit the effectiveness of current aortic arch studies in assessing optimal neuroprotection strategies, including insufficient patient numbers, heterogenous definitions of clinical variables, multiple technical strategies, inadequate reporting of surgical outcomes and a lack of collaborative effort. We have formed an international coalition of centres to provide more robust investigations into this topic. METHODS High-volume aortic arch centres were identified from the literature and contacted for recruitment. A Research Steering Committee of expert arch surgeons was convened to oversee the direction of the research. RESULTS The International Aortic Arch Surgery Study Group has been formed by 41 arch surgeons from 10 countries to better evaluate patient outcomes after aortic arch surgery. Several projects, including the establishment of a multi-institutional retrospective database, randomized controlled trials and a prospectively collected database, are currently underway. CONCLUSIONS Such a collaborative effort will herald a turning point in the surgical management of aortic arch pathologies and will provide better powered analyses to assess the impact of varying surgical techniques on mortality and morbidity, identify predictors for neurological and operative risk, formulate and validate risk predictor models and review long-term survival outcomes and quality-of-life after arch surger

    Determination of the E2/M1 Ratio in the \gamma N \to \Delta(1232) Transition from a Simultaneous Measurement of p(\vec{\gamma},p)\pi^0 and p(\vec{\gamma},\pi^+)n

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    Tagged linearly polarized photons have been used at the Mainz Microtron MAMI for simultaneous measurements of the p(\vec{\gamma},p)\pi^0 and p(\vec{\gamma},\pi^+)n reaction channels to study the \gamma N \to \Delta(1232) transition. The energy dependence of the magnetic dipole M_{1+}^{3/2} and electric quadrupole E_{1+}^{3/2} amplitudes have been extracted from these data in the photon energy range from 270 to 420 MeV. The E2/M1 ratio for the \gamma N \to \Delta(1232) transition has been determined to be - (2.5+-0.1_{stat}+-0.2_{sys}) % at the resonance position delta_{33}=90^0.Comment: 25 pages Latex including 13 postscript figures submitted for publication in Phys. Rev.
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