2,566 research outputs found

    Observations and analysis of polar stratospheric clouds detected by POAM III and SAGE III during the SOLVE II/VINTERSOL campaign in the 2002/2003 Northern Hemisphere winter

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    The Polar Ozone and Aerosol Measurement and Stratospheric Aerosol and Gas Experiment instruments both observed high numbers of polar stratospheric clouds (PSCs) in the polar region during the second SAGE Ozone Loss and Validation (SOLVE II) and Validation of INTERnational Satellites and Study of Ozone Loss (VINTERSOL) campaign, conducted during the 2002/2003 Northern Hemisphere winter. Between 15 November 2002 (14 November 2002) and 18 March 2003 (21 March 2003) SAGE (POAM) observed 122 (151) aerosol extinction profiles containing PSCs. PSCs were observed on an almost daily basis, from early December through 15 January, in both instruments. No PSCs were observed from either instrument from 15 January until 4 February, and from then only sparingly in three periods in mid- and late February and mid-March. In early December, PSCs were observed in the potential temperature range from roughly 375 K to 750 K. Throughout December the top of this range decreases to near 600 K. In February and March, PSC observations were primarily constrained to potential temperatures below 500 K. The PSC observation frequency as a function of ambient temperature relative to the nitric acid-trihydrate saturation point (using a nitric acid profile prior to denitrification) was used to infer irreversible denitrification. By late December 38% denitrification was inferred at both the 400–475 K and 475–550 K potential temperature ranges. By early January extensive levels of denitrification near 80% were inferred at both potential temperature ranges, and the air remained denitrified at least through early March

    On the evaluation of some three-body variational integrals

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    Stable recursive relations are presented for the numerical computation of the integrals dr1dr2r1l1r2m1r12n1exp{αr1βr2γr12}\int d{\bf r}_1 d{\bf r}_2 r_1^{l-1} r_2^{m-1} r_{12}^{n-1} \exp{\{-\alpha r_1 -\beta r_2 -\gamma r_{12}\}} (ll, mm and nn integer, α\alpha, β\beta and γ\gamma real) when the indices ll, mm or nn are negative. Useful formulas are given for particular values of the parameters α\alpha, β\beta and γ\gamma.Comment: 12 pages, 1 figure (PS) and 3 tables. Old figures 2 and 3 replaced by Tables I and III. A further table added. Paper enlarged giving some tips on the convergence of quadrature

    Ervas daninhas do Brasil. Solanaceae I. Gênero Solanum L.

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    Accounting students' expectations and transition experiences of supervised work experience

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    Political and economic discourses position employability as a responsibility of higher education, which utilise mechanisms such as supervised work experience (SWE) to embed employability into the undergraduate curriculum. However, sparse investigation of students' contextualised experiences of SWE results in little being known about the mechanisms through which students derive employability benefits from SWE. The aim of this study is to examine the impact of students' expectation and conception of workplace learning on their transition into SWE. Analysis of accounting students' experiences reveal two broad conceptions of workplace learning, the differing impacts of which on transition experience are explored using existing learning transfer perspectives. Students displaying the more common 'technical' conception construct SWE as an opportunity to develop technical, knowledge-based expertise and abilities that prioritize product-based or cognitive learning transfer. Students with an 'experiential' conception were found to construct SWE primarily as an experience through which the development of personal skills and abilities beyond technical expertise are prioritized using process-based or socio-cultural learning transfer. Further data analysis suggests that these two learning transfer approaches have differing impacts on students' employability development which may indicate a need for universities to consider how to develop appropriate student expectations of and approaches to SWE and meaningful support for students' SWE transition

    2002-2003 Arctic ozone loss deduced from POAM III satellite observations and the SLIMCAT chemical transport model

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    The SLIMCAT three-dimensional chemical transport model (CTM) is used to infer chemical ozone loss from Polar Ozone and Aerosol Measurement (POAM) III observations of stratospheric ozone during the Arctic winter of 2002-2003. Inferring chemical ozone loss from satellite data requires quantifying ozone variations due to dynamical processes. To accomplish this, the SLIMCAT model was run in a 'passive' mode from early December until the middle of March. In these runs, ozone is treated as an inert, dynamical tracer. Chemical ozone loss is inferred by subtracting the model passive ozone, evaluated at the time and location of the POAM observations, from the POAM measurements themselves. This 'CTM Passive Subtraction' technique relies on accurate initialization of the CTM and a realistic description of vertical/horizontal transport, both of which are explored in this work. The analysis suggests that chemical ozone loss during the 2002-2003 winter began in late December. This loss followed a prolonged period in which many polar stratospheric clouds were detected, and during which vortex air had been transported to sunlit latitudes. A series of stratospheric warming events starting in January hindered chemical ozone loss later in the winter of 2003. Nevertheless, by 15 March, the final date of the analysis, ozone loss maximized at 425K at a value of about 1.2ppmv, a moderate amount of loss compared to loss during the unusually cold winters in the late-1990s. SLIMCAT was also run with a detailed stratospheric chemistry scheme to obtain the model-predicted loss. The SLIMCAT model simulation also shows a maximum ozone loss of 1.2ppmv at 425K, and the morphology of the loss calculated by SLIMCAT was similar to that inferred from the POAM data. These results from the recently updated version of SLIMCAT therefore give a much better quantitative description of polar chemical ozone loss than older versions of the same model. Both the inferred and modeled loss calculations show the early destruction in late December and the region of maximum loss descending in altitude through the remainder of the winter and early spring

    The concept of solidarity: emerging from the theoretical shadows?

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    The concept of solidarity has been relatively neglected by social scientists since Durkheim's pioneering work in the late 19th century. The discipline of politics has been guilty of overlooking this 'subjective' element of community life, but recent works by Stjernø and Brunkhorst reflect a growing awareness of the theoretical significance of the concept. Whereas early liberal attempts to theorise solidarity took the nation state to be the appropriate community for its realisation, the emergence of globalisation raises the possibility of human solidarity developing in the global community. Traditional forms of solidarity have been dissipated by the social changes accompanying globalisation, but they were often locked into the defence of particular interests. New forms may be emerging to rekindle the broader vision of human solidarity. Recent work by writers such as Habermas, Honneth, Rorty and Touraine focuses on widening and deepening democratic participation and/or the articulation of our ethical obligations in various ways. It is argued here that these perspectives need to be supplemented by a radical humanist approach grounded in a normative theory of human self-realisation

    Amygdala and Nucleus Accumbens Activation to Emotional Facial Expressions in Children and Adolescents at Risk for Major Depression

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    Objective. Offspring of parents with major depressive disorder (MDD) face three-fold higher risk for MDD than offspring without a family history. Although MDD is a major cause of morbidity and mortality, neural correlates of risk for MDD remain poorly understood. This study compares amygdala and nucleus accumbens activation in children and adolescents at high and low risk for MDD under varying attentional and emotional conditions. Methods. Thirty-nine juveniles, 17 offspring of parents with MDD (high-risk group) and 22 offspring of parents without histories of MDD, anxiety or psychotic disorders (low-risk group) completed a functional magnetic resonance imaging study. During imaging, subjects viewed faces that varied in intensity of emotional expressions across blocks of trials; while attention was unconstrained (passive viewing), and constrained (rate nose width on face; rate subjective fear while viewing face). Results. When attention was unconstrained, high-risk, relative to low-risk, subjects showed greater amygdala and nucleus accumbens (NAcc) activation to fearful faces, and lower NAcc activation to happy faces (p values \u3c .05, small volume corrected for the amygdala and NAcc). No group differences emerged in amygdala or NAcc activation during constrained attention. Exploratory analysis showed that constraining attention was associated with greater medial prefrontal cortex activation in the high-risk than low-risk group. Conclusions. Amygdala and NAcc responses to affective stimuli may reflect vulnerability for MDD. Constraining attention may normalize emotion-related neural function, possibly via engagement of the medial prefrontal cortex; face-viewing with unconstrained attention may engage aberrant processes associated with risk for MDD

    Psychoanalytic sociology and the traumas of history: Alexander Mitscherlich between the disciplines

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    This article examines the way aspects of recent history were excluded in key studies emerging from psychoanalytic social psychology of the mid-twentieth century. It draws on work by Erikson, Marcuse and Fromm, but focuses in particular on Alexander Mitscherlich. Mitscherlich, a social psychologist associated with the later Frankfurt school, was also the most important psychoanalytic figure in postwar Germany. This makes his work significant for tracing ways in which historical experience of the war and Nazism was filtered out of psychosocial narratives in this period, in favour of more structural analyses of the dynamics of social authority. Mitscherlich?s 1967 work The Inability to Mourn, co-authored with Margarete Mitscherlich, is often cited as the point at which the ?missing? historical experience flooded back into psychoanalytic accounts of society. I argue that this landmark publication doesn?t hail the shift towards the psychoanalysis of historical experience with which it is often associated. These more sociological writers of the mid-century were writing before the impact of several trends occurring in the 1980s-90s which decisively shifted psychoanalytic attention away from the investigation of social authority and towards a focus on historical trauma. Ultimately this is also a narrative about the transformations which occur when psychoanalysis moves across disciplines

    Geometric Algorithm for Abelian-Gauge Models

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    Motivated by the sign problem in several systems, we have developed a geometric simulation algorithm based on the strong coupling expansion which can be applied to abelian pure gauge models. We have studied the algorithm in the U(1) model in 3 and 4 dimensions, and seen that it is practical and is similarly efficient to the standard heat-bath algorithm, but without the ergodicity problems which comes from the presence of vortices. We have also applied the algorithm to the Ising gauge model at the critical point, and we find hints of a better asymptotic behaviour of the autocorrelation time, which therefore suggests the possibility of a smaller dynamical critical exponent with respect to the standard heat-bath algorithm.Comment: 16 pages, 11 figure
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