Cycles of Myth Restoration One Approach to Understanding American Culture     

Jerome O. Steffen 《Journal of American culture (Malden, Mass. : 2003)》1993,16(1):25-33

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Der Entwurf strukturierter rollenbasierter Zugriffskontrollmodelle     

Steffen E. Seufert 《Informatik - Forschung und Entwicklung》2002,17(1):1-11

Zusammenfassung. In diesem Beitrag wird ein formaler Ansatz zur Ableitung von Zugriffsrechten auf der Basis eines formalen Organisationsmodells vorgestellt. Hierzu wird der Ansatz der rollenbasierten Zugriffskontrolle (engl. Role-Based Access Control, kurz RBAC) um die M?glichkeit erweitert, Aufbauorganisationen zu modellieren. Der Vorteil gegenüber rollenbasierten Ans?tzen mit einfachen Rollenhierarchien ist die klare Struktur, die einem Zugriffskontrollmodell durch die Organisationsform aufgepr?gt wird. Des Weiteren k?nnen organisatorische Regelungen, wie z.B. Urlaubsvertretung oder Weisungsbefugnis, direkt im Modell hinterlegt werden. Aufwendig zu pflegende und h?ufig inkonsistente Rollenkataloge werden obsolet. Sicherheitsstrategien mit unpr?zisen Vorgaben lassen sich mittels der vorgestellten Technik der sog. `Kompetenzerweiterung' umsetzen. Das zugrundeliegende Paradigma des vorgestellten Ansatzes unterscheidet sich stark von anderen Ans?tzen mit statischer Autorisation. Nutzer k?nnen sich Zugriffsrechte in fest definierten Grenzen selbstverantwortlich zuteilen, wobei jedoch eine nachtr?gliche Kontrolle stark vereinfacht und damit praktikabel wird. Eingegangen am 22. Februar 2001 / Angenommen am 22. Mai 2001  相似文献   

Histories of Romani Education in Slovakia: A Kazamian Perspective     

William S. New  Hristo Kyuchukov  Milan Samko 《欧洲教育》2018,50(2):185-200

Using the critical work of Andreas Kazamias on the history and methods of comparative education as conceptual framework, we investigate the education (over a 200-year period) of the Slovak Roma. We position our story as paradigmatic of the dual processes of enlightenment and obscurantism with which we are familiar in thinking about the history of racial violence. The article describes the encounter of a young British doctor, Richard Bright, with Roma and Slovaks in 1814, and explores the Enlightenment thinking about Roma in specific, and race in general, in Bright’s travelogue. We juxtapose these historical investigations with qualitative findings from research conducted recently in the same region of Slovakia. Our goal is to show that Kazamias’s calls for a return to the historical in educational research, and greater attention to the “paideia of the soul,” have relevance in considering the discouraging past and present of Roma in Slovak schools and society.  相似文献   

Television and Secondary School Children     

Milan Ljubic 《Educational Media International》2013,50(2):128-130

Abstract

The way in which children judge the general output of television, and the way in which it affects them, should be prime factors in considering programming for educational television, particularly in areas where educational television is still in its infancy, asin the Third World.

Dr Collin's article looks at the effects TV can have on young people, and considers the general programme output. From survey results he draws important lessons about these effects and how, for young people, the world of television translates into real life.  相似文献   

Unsteady flow phenomena in human undulatory swimming: a numerical approach     

Steffen Pacholak  Stefan Hochstein  Alexander Rudert  Christoph Brücker 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(2):176-194

The undulatory underwater sequence is one of the most important phases in competitive swimming. An understanding of the recurrent vortex dynamics around the human body and their generation could therefore be used to improve swimming techniques. In order to produce a dynamic model, we applied human joint kinematics to three-dimensional (3D) body scans of a female swimmer. The flow around this dynamic model was then calculated using computational fluid dynamics with the aid of moving 3D meshes. Evaluation of the numerical results delivered by the various motion cycles identified characteristic vortex structures for each of the cycles, which exhibited increasing intensity and drag influence. At maximum thrust, drag forces appear to be 12 times higher than those of a passive gliding swimmer. As far as we know, this is the first disclosure of vortex rings merging into vortex tubes in the wake after vortex recapturing. All unsteady structures were visualized using a modified Q-criterion also incorporated into our methods. At the very least, our approach is likely to be suited to further studies examining swimmers engaging in undulatory swimming during training or competition.  相似文献   

Mathematical and philosophical Newton     

Steffen Ducheyne 《Metascience》2011,20(3):467-476

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Label-free microfluidic characterization of temperature-dependent biomolecular interactions     

Nguyen T  Pei R  Landry DW  Stojanovic MN  Lin Q 《Biomicrofluidics》2011,5(3):34118-341187

We present a microfluidic approach to characterizing temperature-dependent biomolecular interactions. Solvated L-arginine vasopressin (AVP) and its immobilized RNA aptamer (spiegelmer) were allowed to achieve equilibrium binding in a microchip at a series of selected temperatures. Unbound AVP were collected and analyzed with matrix-assisted laser desorption∕ionization mass spectrometry (MALDI-MS), yielding melting curves that reveal highly temperature-dependent zones in which affinity binding (36–45 °C) or dissociation (25–33 °C and 50–65 °C) occurs. Additionally, temperature-dependent binding isotherms were constructed; from these, thermodynamic quantities involved in binding were extracted. The results illustrated a strong change in heat capacity of interaction for this system, suggesting a considerable thermodynamic influence controlling vasopressin-spiegelmer interaction.  相似文献   

Transport and separation of micron sized particles at isotachophoretic transition zones     

Gabriele Goet  Tobias Baier    Steffen Hardt 《Biomicrofluidics》2011,5(1)

Conventionally, isotachophoresis (ITP) is used for separation of ionic samples according to their electrophoretic mobilities. We demonstrate that the scope of ITP applications may be extended toward particle concentration and separation. Owing to the distributions of electrolyte concentration and electric field inside a transition zone between two electrolytes, a number of different forces act on a small particle. As far as possible, we provide estimates for the order of magnitude of these forces and analyze their scaling with the particle size and the electric-field strength. Furthermore, we experimentally demonstrate that polymer beads of 5 μm diameter dispersed in a high mobility “leading” electrolyte are picked up and carried along by an ITP transition zone which is formed with a low mobility “trailing” electrolyte. By studying the particle positions and trajectories, we show that impurities in the electrolytes play a significant role in the experiments. Additionally, it is experimentally shown that different types of beads can be separated at an ITP transition zone. In particular, beads of 1 μm diameter are not carried along with the transition zone, in contrast to the 5 μm beads. The presented technique thus adds to the portfolio of electrokinetic transport, concentration, and separation methods in microfluidics.  相似文献   

Bildung,Ausbildung und soziale Ungleichheiten im Lebenslauf     

Steffen Hillmert 《Zeitschrift für Erziehungswissenschaft》2014,17(2):73-94

This paper describes mutual links between educational attainment and social inequality from a life course perspective. Analytically we distinguish between aspects of inequality with regard to access to education, consequences of education, and social reproduction through education. A special emphasis is put on the role institutions play in these processes. The paper presents selected empirical findings, discusses theoretical mechanisms, and draws some conclusions for the conceptualisation of education systems.  相似文献   

CONFU-digital image discussion group Educational fair use guidelines for digital images,discussion draft of july 1,1996     

Jens Basanow  Pascal Neis  Steffen Neubauer  Arne Schilling  Alexander Zipf 《Archives and Museum Informatics》1996,10(2):173-184

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