8,783 research outputs found

    The making of Britain’s first urban landscapes: the case of late Iron Age and Roman Essex

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    This paper presents preliminary research into the social and economic impact of early urban settlement in Britain, focusing on the case-study area of Late Iron Age to Roman Essex. Through fresh analysis of ceramic assemblages from Colchester and Heybridge, we describe hitherto unrecognised socio-cultural groupings and identities through subtle differences in the deposition of pottery in the generations before and after conquest. The concluding discussion concentrates on problems that we still have to address in describing the economic basis of early urban society in Britain

    Mixings, Lifetimes, Spectroscopy and Production of Heavy Flavor at the Tevatron

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    The Fermilab Tevatron offers unique opportunities to perform measurements of the heavier B hadrons that are not accessible at the Upsilon(4S) resonance. In this summary, we describe some recent heavy flavor results from the DO and CDF collaborations and discuss prospects for future measurements.Comment: To appear in Proceedings of the XXI International Symposium on lepton and Photon Interactions at High Energies, Fermilab, August 200

    Models of Type Theory Based on Moore Paths

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    This paper introduces a new family of models of intensional Martin-L\"of type theory. We use constructive ordered algebra in toposes. Identity types in the models are given by a notion of Moore path. By considering a particular gros topos, we show that there is such a model that is non-truncated, i.e. contains non-trivial structure at all dimensions. In other words, in this model a type in a nested sequence of identity types can contain more than one element, no matter how great the degree of nesting. Although inspired by existing non-truncated models of type theory based on simplicial and cubical sets, the notion of model presented here is notable for avoiding any form of Kan filling condition in the semantics of types.Comment: This is a revised and expanded version of a paper with the same name that appeared in the proceedings of the 2nd International Conference on Formal Structures for Computation and Deduction (FSCD 2017

    Ethnic Diversity and Organizational Performance: Assessing Diversity Effects at the Managerial and Street Levels

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    As the public sector workforce becomes more ethnically diverse and as government agencies make attempts to "manage" that diversity, the importance of understanding how diversity affects workplace interactions and work-related outcomes increases. Little public sector research has examined the impact of diversity on performance outcomes. This paper seeks to fill this gap by studying the effects of the ethnic diversity of managers and street level bureaucrats on work-related outcomes. We use basic in-group/out-group theories from psychology to form hypotheses relating diversity to performance. The results of diversity research using social identification and categorization theory and similarity/attraction theory led us to form the hypothesis that greater levels of ethnic diversity among public managers and street-level bureaucrats will lead to lower organizational performance, when the task requires significant coordination and collaboration. Diversity research that uses the information and decision-making theory, while scant, led us to form a second hypothesis that greater levels of ethnic diversity among public managers and street-level bureaucrats will lead to higher organizational performance, when the task does not require significant coordination and collaboration. Our results were mixed. We found support for the first hypothesis with respect to street-level bureaucrats but not for managers. The results did not support our second hypothesis -- we actually found an opposite relationship for street-level bureaucrats from what we expected. Overall, the results support previous research that suggests that increased levels of ethnic diversity can lead to process-oriented difficulties in the workplace and negatively affect workrelated outcomes. Working Paper 06-3

    Smoking: taxing health and Social Security

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    Cigarette smoking is costly in terms of not only its effects on smokers' health but also the direct and indirect financial costs it imposes on smokers and their families. For instance, premature death caused by smoking may redistribute Social Security income in unexpected ways that affect behavior and reduce the economic well-being of smokers and their dependents. ; This article examines the effects of smoking-attributable mortality on the net marginal Social Security tax rate (NMSSTR)—the difference between the statutory payroll tax rate and the present value of future benefits to which a covered worker is entitled. ; The analysis shows that smokers, as a result of shorter life expectancies, incur a higher NMSSTR than nonsmokers. This higher tax rate could have implications for both labor supply behavior and the Social Security System's funding. ; The authors note that smoking status should be considered in assessing Social Security legislative proposals designed to reduce system inequities or promote social adequacy—in particular, amendments designed to reduce poverty among young widows and widowers. Failure to take smoking status into account may unintentionally promote behavior that is detrimental to health.Social security

    Smoking: taxing health and Social Security

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    While the health risks associated with smoking are well known, the impact on income distributions is not. This paper extends the literature by examining the distributional effects of a behavioral choice, in this case smoking, on net marginal Social Security tax rates (NMSSTR). The results show that smokers, as a result of shorter life expectancies, incur a higher NMSSTR than nonsmokers. In addition, as low-earnings workers have a higher smoking prevalence than high-earnings workers, smoking works to widen the income distribution. This higher tax rate could have implications for both labor supply behavior and Social Security system funding.

    In-flight direct-strike lightning research

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    Tests designed to investigate the lightning-generated electromagnetic environment affecting aircraft are discussed. An F-106B aircraft specially instrumented for lightning electromagnetic measurements was used. The instrumentation system is reviewed and typical results recorded by the instrumentation during simulated-lightning ground tests performed for a safety survey are presented. Several examples of data obtained during summer flight testing are presented and future plans are discussed

    The 1981 direct strike lightning data

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    Data waveforms obtained during the 1981 direct strike lightning tests, utilizing the NASA F-106B aircraft specially instrumented for lightning electromagnetic measurements are presented. The aircraft was operated in a thunderstorm environment to elicit strikes. Electromagnetic field data were recorded for both attached lightning and free field excitation of the aircraft

    Empirical studies of upper atmospheric species

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    The first month of spin-scan ozone imaging (SOI) data (October 1981) was processed and compared with total ozone mapping spectrometer and ground based data. Short term variations in the ozone field have been revealed using animated sequences of SOI data. High correlations were observed between SOI ozone and upper tropospheric meteorological data. The relationship between ozone and temperature in the stratosphere was investigated by examining Nimbus 4 backscattered ultraviolet ozone and selective chopper radiometer temperature measurements as well as solar Nimbus 7 solar backscattered ultraviolet ozone and stratospheric and mesospheric sounder temperature measurements. Results from these ozone temperature studies were compared with calculations from theoretical 2-D models. All of the lims infrared monitor of the stratosphere data was processed at 10 pressure levels and correlations between various species have been performed. The Venus Atmospheric Drag model was modified taking into account recent investigations on the Venus thermosphere and the resulting model was considered for incorporation into the Venus International Reference Atmosphere
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