Universal collisionless transport of graphene

The impact of the electron-electron Coulomb interaction on the optical conductivity of graphene has led to a controversy that calls into question the universality of collisionless transport in this and other Dirac materials. Using a lattice calculation that avoids divergences present in previous nodal Dirac approaches, our work settles this controversy and obtains results in quantitative agreement with experiment over a wide frequency range. We also demonstrate that dimensional regularization methods agree, as long as the scaling properties of the conductivity and the regularization of the theory in modified dimension are correctly implemented. Tight-binding lattice and nodal Dirac theory calculations are shown to coincide at low energies even when the non-zero size of the atomic orbital wave function is included, conclusively demonstrating the universality of the optical conductivity of graphene.Comment: 4+ pages,4 figures; includes Supplemental Material (18 pages, 2 figures

Elastic response of the electron fluid in intrinsic graphene: The collisionless regime

The elastic response of an electron fluid at finite frequencies is defined by the electron viscosity $\eta(\omega)$. We determine $\eta(\omega)$ for graphene at the charge neutrality point in the collisionless regime, including the leading corrections due to the electron-electron Coulomb interaction. We find interaction corrections to $\eta(\omega)$ that are significantly larger if compared to the corresponding corrections to the optical conductivity. In addition, we find comparable contributions to the dynamic momentum flux due to single-particle and many-particle effects. We also demonstrate that $\eta(\omega)$ is directly related to the nonlocal energy-flow response of graphene at the Dirac point. The viscosity in the collisionless regime is determined with the help of the strain generators in the Kubo formalism. Here, the pseudo-spin of graphene describing its two sublattices plays an important role in obtaining a viscosity tensor that fulfills the symmetry properties of a rotationally symmetric system.Comment: 18 pages, 5 figure

Educação sob o Nacional-Socialismo. Ideologia, Programas e Prática

The article provides a condensed, introductory overview of National Socialist formation education in the Hitler Youth and school. It is based on the author’s own research and relevant presentations. Education under National Socialism was characterized by the interplay of a racist worldview and the regime’s totalitarian will to rule. For Nazi education, this meant that the political took precedence over all social issues, including all issues relevant from the perspective of educational theory. In our analysis, we distinguish between two levels: the level of standardization and the level of educational practices in the Hitler Youth and school. Particularly during World War II, political demands were increasingly rigidly enforced, and adolescents were increasingly instrumentalized for their purposes. The National Socialists’ aspirations for total control compared to the educational reality exhibited correspondences as well as discrepancies and contradictions. Against the background of traditional tasks of education, the verdict on Nazi education from a normative point of view is clearly negative. However, if one also looks at National Socialist educational practices, one notices numerous characteristic ambivalences – between the partly contradictory demands of the National Socialist regime, but also between its educational practices and its attempts at realization. On the one hand, National Socialists achieved comprehensive formative successes, while on the other hand they often failed because of their totalitarian objectives

Bernd Dühlmeier: Und die Schule bewegte sich doch. Unbekannte Reformpädagogen und ihre Projekte in der Nachkriegszeit. Bad Heilbrunn: Klinkhardt 2004 (510 S.) [Rezension]

Rezension von: Bernd Dühlmeier: Und die Schule bewegte sich doch. Unbekannte Reformpädagogen und ihre Projekte in der Nachkriegszeit. Bad Heilbrunn: Klinkhardt 2004 (510 S.; ISBN 3-7815-1328-9; 34,00 EUR)

Hans-Georg Herrlitz: Auf dem Weg zur Historischen Bildungsforschung. Studien über Schule und Erziehungswissenschaft aus siebenunddreißig Jahren. Weinheim und München: Juventa Verlag 2001 (270 S.) [Rezension]

Rezension von: Hans-Georg Herrlitz: Auf dem Weg zur Historischen Bildungsforschung. Studien über Schule und Erziehungswissenschaft aus siebenunddreißig Jahren. Weinheim und München: Juventa Verlag 2001 (270 S.; ISBN 3-7799-1427-1)

Gelingensbedingungen von Schulreform. Bildungshistorische Befunde als Schlüssel zum pädagogischen Verständnis von Schulentwicklungsprozessen und als Erweiterung des Theorienverbundes zur Schulreform

Historische Schulforschung und Schulentwicklungsforschung haben an schulischen Reformprozessen zwar ein vergleichbares Forschungsinteresse, stehen aber bislang nicht im wissenschaftlichen Dialog. Gleichwohl existierten nahezu sämtliche Praxen der gegenwärtigen Schul- und Unterrichtsentwicklung bereits in den Schulreformprozessen der historischen Reformpädagogik. Auf der Grundlage von elf bildungshistorischen und schulpädagogischen Quellenstudien wird ein Struktur- und Handlungsmodell gelingender Schulreformprozesse entwickelt, das sich aus der akteursnahen Eigenlogik pädagogisch-praktischer Reformprozesse ableitet. Die Studien analysieren fallorientiert und quellengestützt die Reformpraxen an historischen Reformschulen des 20. Jahrhunderts und geben vertiefte Einblicke in historische Schul(reform)praxis. Bezugspunkt ist dabei jeweils die Einzelschule als pädagogische Handlungseinheit. Die historisch-empirisch entwickelte „Fünf-plus-zwei-K-Struktur gelingender Schulreformprozesse“ wurde an 100 gegenwärtigen Reformschulen überprüft und konnte im Ergebnis in einem Zeitraum von rund einhundert Jahren als wiederkehrend validiert werden. Die Befunde tragen insgesamt zum pädagogischen Verständnis von Schulreformprozessen bei und bilden eine professionsnahe Referenz für die Theoriebildung innerhalb der Schulentwicklungsforschung. (DIPF/Orig.)This work presents a structural and operative model of successful processes of school reform, based on eleven source-based studies on the history of educational and school-based pedagogy. Oriented on real-world cases and sources, these studies analyse the reform practices of historical reform schools during the twentieth century. The point of reference in each case is the individual school as a pedagogical unit of action. The studies are historically and empirically grounded and provide in-depth insights into the historical practices of schools as well as historical school reforms. The term “conditions for success” is employed here to focus on organisational structures and pedagogical patterns of action within historical processes of reform. The findings are derived from the inherent logic of practical pedagogical processes of reform. These are structures and patterns of action developed by the pedagogical professionals themselves through social processes. The results of the educational-historical source studies are collated here in a model of recurring professional patterns of pedagogical action and structure. The resulting historically and empirically developed “Five-plus-two-K Structure of Successful School Reform Processes” was tested on 100 modern day reform schools and it could be shown that these processes recur over a period of about one hundred years. Following the inherent logic of pedagogical processes in schools, the “Five-plus-two-K Structure of Successful School Reform Processes” was developed through a process of professional pedagogical action, shaped by professional pedagogical action and interaction, and was differentiated for professional pedagogical action. This model is integrative on the basis that it is primarily pedagogically constituted and was closely developed with educational professionals. The model is thus an educational-historical contribution to a theory of school reform processes and contributes to the pedagogical understanding of the processes of school development. (DIPF/Orig.

Bildungssystem im Wandel – Zwischen Eigendynamik, Politik und Pädagogik

Die hier vorgelegten Analysen zeigen jetzt, in welcher Weise man sinnvoll über die ‚Eigenbewegung‘ und ‚Eigendynamik‘ des (deutschen) Bildungswesens im 19. und 20. Jahrhundert sprechen kann. Die Beiträge analysieren auch schon, welche Dimensionen der Wandel hat, ob er primär oder gar allein systemisch zu beobachten ist oder auch auf der Ebene der pädagogischen Interaktion, auf der Ebene der Reflexion oder auch in der forschenden Behandlung des Bildungswesens. Die Autoren geben eine Einleitung zu den folgenden Artikeln des Heftes. (DIPF/Orig./jk.