276 research outputs found

    Aspects of Labor Economics

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    Wage determination in the men's shoe industry : a case study of the shoe producing district centered around Brockton, Massachusetts

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    Thesis (Ph.D.) Massachusetts Institute of Technology. Dept. of Economics, 1949.Vita.Bibliography: leaves 441-447.by George Pratt Shultz.Ph.D

    Security Studies for the 21st Century

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    The mysteries of mammatus clouds: Observations and formation mechanisms

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    Mammatus clouds are an intriguing enigma of atmospheric fluid dynamics and cloud physics. Most commonly observed on the underside of cumulonimbus anvils, mammatus also occur on the underside of cirrus, cirrocumulus, altocumulus, altostratus, and stratocumulus, as well as in contrails from jet aircraft and pyrocumulus ash clouds from volcanic eruptions. Despite their aesthetic appearance, mammatus have been the subject of few quantitative research studies. Observations of mammatus have been obtained largely through serendipitous opportunities with a single observing system (e.g., aircraft penetrations, visual observations, lidar, radar) or tangential observations from field programs with other objectives. Theories describing mammatus remain untested, as adequate measurements for validation do not exist because of the small distance scales and short time scales of mammatus. Modeling studies of mammatus are virtually nonexistent. As a result, relatively little is known about the environment, formation mechanisms, properties, microphysics, and dynamics of mammatus. This paper presents a review of mammatus clouds that addresses these mysteries. Previous observations of mammatus and proposed formation mechanisms are discussed. These hypothesized mechanisms are anvil subsidence, subcloud evaporation/sublimation, melting, hydrometeor fallout, cloud-base detrainment instability, radiative effects, gravity waves, Kelvin-Helmholtz instability, Rayleigh-Taylor instability, and Rayleigh-Bénard-like convection. Other issues addressed in this paper include whether mammatus are composed of ice or liquid water hydrometeors, why mammatus are smooth, what controls the temporal and spatial scales and organization of individual mammatus lobes, and what are the properties of volcanic ash clouds that produce mammatus? The similarities and differences between mammatus, virga, stalactites, and reticular clouds are also discussed. Finally, because much still remains to be learned, research opportunities are described for using mammatus as a window into the microphysical, turbulent, and dynamical processes occurring on the underside of clouds. © 2006 American Meteorological Society

    'Protestantism' as a historical category

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    The term ‘Protestant’ itself is a historical accident, but the category of western Christians who have separated from Rome since 1517 remains a useful one. The confessionalisation thesis, which has dominated recent Reformation historiography, instead posits the two major Protestant confessions and Tridentine Catholicism as its categories, but this can produce a false parallelism in which the nature of the relationship between the confessions is oversimplified. Instead, this paper proposes we think of a Protestant ecosystem consisting of self-consciously confessional Lutheranism, a broad Calvinism which imagined itself as normative, and a collection of radical currents much more intimately connected to the ‘magisterial’ confessions than any of the participants wished to acknowledge. The magisterial / radical division was maintained only with constant vigilance and exemplary violence, with Calvinism in particular constantly threatening to bleed into radicalism. What gives this quarrelsome family of ‘Protestants’ analytical coherence is neither simple genealogy nor, as has been suggested, mere adherence to the Bible: since in practice both ‘radical’ and ‘magisterial’ Protestants have been more flexible and ‘spiritual’ in their use of Scripture than is generally allowed. It is, rather, the devotional experience underpinning that ‘spiritual’ use of the Bible, of an unmediated encounter with grace

    Decrease in plasma miR-27a and miR-221 after concussion in Australian football players

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    Introduction: Sports-related concussion (SRC) is a common form of brain injury that lacks reliable methods to guide clinical decisions. MicroRNAs (miRNAs) can influence biological processes involved in SRC, and measurement of miRNAs in biological fluids may provide objective diagnostic and return to play/recovery biomarkers. Therefore, this prospective study investigated the temporal profile of circulating miRNA levels in concussed male and female athletes. Methods: Pre-season baseline blood samples were collected from amateur Australian rules football players (82 males, 45 females). Of these, 20 males and 8 females sustained an SRC during the subsequent season and underwent blood sampling at 2-, 6- and 13-days post-injury. A miRNA discovery Open Array was conducted on plasma to assess the expression of 754 known/validated miRNAs. miRNA target identified were further investigated with quantitative real-time PCR (qRT-PCR) in a validation study. Data pertaining to SRC symptoms, demographics, sporting history, education history and concussion history were also collected. Results: Discovery analysis identified 18 candidate miRNA. The consequent validation study found that plasma miR-221-3p levels were decreased at 6d and 13d, and that miR-27a-3p levels were decreased at 6d, when compared to baseline. Moreover, miR-27a and miR-221-3p levels were inversely correlated with SRC symptom severity. Conclusion: Circulating levels of miR-27a-3p and miR-221-3p were decreased in the sub-acute stages after SRC, and were inversely correlated with SRC symptom severity. Although further studies are required, these analyses have identified miRNA biomarker candidates of SRC severity and recovery that may one day assist in its clinical management
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