970 research outputs found

    Real and virtual photon structure from dijet events

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    Jet production in epep collisions is sensitive to the partonic structure of photon. The latest measurements of dijet production from the H1 experiment provide new results of the gluon density of real photons at low xx and, for the first time, on the partonic density of virtual photons. Properties of the photon remnant were measured as a function of the hard scale defined by the pTp_T of the jets. The comparison of dijet cross sections with the NLO QCD calculation shows the non-triviality of the concept of virtual photon structure.Comment: 4 pages, Latex with 4 ps figures, references for section 5 updated, Talk presented at DIS99 Workshop at Zeuthen, April 199

    Nuclear radiation analysis

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    A study program of radiation shielding against the deleterious effects of nuclear radiation on man and equipment is reported. The methods used to analyze the radiation environment from bremsstrahlung photons are discussed along with the methods employed by transport code users. The theory and numerical methods used to solve transport of neutrons and gammas are described, and the neutron and cosmic fluxes that would be present on the gamma-ray telescope were analyzed

    Neighbors' income, public goods, and well‐being

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    How does neighbors' income affect individual well‐being? Our analysis is based on rich U.S. local data from the Behavioral Risk Factor Surveillance System, which contains information on where respondents live and their self‐reported well‐being. We find that the effect of neighbors' income on individuals' self‐reported well‐being varies with the size of the neighborhood included. In smaller areas such as ZIP codes, we find a positive relationship between median income and individuals' life satisfaction, whereas it is the opposite at the county, MSA, and state levels. We provide evidence that local public goods and local area characteristics such as unemployment, criminality, and poverty rates drive the association between satisfaction and neighbors' income at the ZIP code level. The neighbors' income effects are mainly concentrated among poorer individuals and are as large as one quarter of the effect of own income on self‐reported well‐being

    Organic Matter Sources in North Atlantic Fjord Sediments

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    To better constrain the global carbon cycle fundamental knowledge of the role of carbon cycling on continental margins is crucial. Fjords are particularly important shelf areas for carbon burial due to relatively high sedimentation rates and high organic matter fluxes. As terrigenous organic matter is more resistant to remineralization than marine organic matter, a comprehensive knowledge of the carbon source is critical to better constrain the efficiency of organic carbon burial in fjord sediments. Here we investigated highly productive fjords in northern Norway and compare our results with both existing and new organic carbon to organic nitrogen ratios and carbon stable isotope compositions from fjords in mid‐Norway, west Svalbard, and east Greenland. The marine organic carbon contribution varies significantly between these fjords, and the contribution of marine organic carbon in Norwegian fjords is much larger than previously suggested for fjords in NW Europe and also globally. Additionally, northern Norwegian fjords show very high marine carbon burial rates (73.6 gC · m‐2 · year‐1) suggesting that these fjords are probably very distinct carbon burial hotspots. We argue that the North Atlantic Current inflow sustains these high burial rates and changes in the current strength due to ongoing climate change are likely to have a pronounced effect on carbon burial in North Atlantic fjords

    Obtaining data linkage consent for children: factors influencing outcomes and potential biases

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    Understanding factors associated with consent for data linkage has largely focussed on adults, but parents or guardians can also be asked to consent on behalf of children for whom they are responsible. A framework for consent decision is presented, and is tested using a large nationally representative survey asking mothers to consent for both themselves and their children for two sets of records. Nearly all mothers give the same consent outcome for all their children. Consent rates are higher for education records than for health records and higher for mothers than children. Multivariate analyses suggest that minorities are generally less likely to consent, while more trust increases chances of consent. Several survey environment factors are important, with harder-to-contact respondents less likely to consent, while the presence of others and higher interviewer-respondent rapport lead to a higher chance of consent. These findings suggest potential methodologies to improve consent rates and possibly minimise bias. This is important given significant demographic differences between children across consent outcomes. However, data from a survey of 10?15 year olds in the study shows fewer differences for several important behaviours and attitudes across consent outcomes

    Shared Perceptions of Supervisor Support: What Processes Make Supervisors and Employees See Eye to Eye?

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    This paper aims to find out what processes contribute to horizontal (between employees) and vertical (between employees and their supervisor) shared perceptions of supervisor support by public frontline supervisors. Informed by a multilevel qualitative study among supervisors and teachers in public secondary schools, we develop theoretical propositions regarding these processes. We propose that employees’ expectations based on experiences with previous supervisors can decrease horizontal shared perceptions. Subsequently, a contingent or consistent approach to supporting employees contribute to the development of horizontal and vertical shared perceptions, depending on the legitimacy attributed by employees to the reason behind this approach. Over time, supervisor support experienced by employees at meaningful work-life events contributes to the emergence of horizontal and vertical shared perceptions. This research shows that instead of merely looking for correlates of shared perceptions, scrutinizing the processes that contribute to horizontal and vertical shared perceptions increases our understanding of this complex phenomenon

    The influence of Ga+^+-irradiation on the transport properties of mesoscopic conducting thin films

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    We studied the influence of 30keV Ga+^+-ions -- commonly used in focused ion beam (FIB) devices -- on the transport properties of thin crystalline graphite flake, La0.7_{0.7}Ca0.3_{0.3}MnO3_3 and Co thin films. The changes of the electrical resistance were measured in-situ during irradiation and also the temperature and magnetic field dependence before and after irradiation. Our results show that the transport properties of these materials strongly change at Ga+^+ fluences much below those used for patterning and ion beam induced deposition (IBID), limiting seriously the use of FIB when the intrinsic properties of the materials of interest are of importance. We present a method that can be used to protect the sample as well as to produce selectively irradiation-induced changes.Comment: 14 pages, 11 figures, will be published in Nanotechnology 201

    Propensity to consent to data linkage: experimental evidence on the role of three survey design features in a UK longitudinal panel

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    When performing data linkage, survey respondents need to provide their informed consent. Since not all respondents agree to this request, the linked data-set will have fewer observations than the survey data-set alone and bias may be introduced. By focusing on the role that survey design features play in gaining respondents’ consent, this paper provides an innovative contribution to the studies in this field. Analysing experimental data collected in a nationally representative household panel survey of the British population, we find that interview features such as question format (dependent/independent questions) and placement of the consent question within the questionnaire have an impact on consent rates
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