Neue Rechte und Universität

Prof. Dr. Jens Schröter, Dr. Pablo Abend und Prof. Dr. Benjamin Beil sind Herausgeber der Reihe. Die Herausgeber*innen der einzelnen Hefte sind renommierte Wissenschaftler*innen aus dem In- und Ausland. AG Siegen Denken: Pablo Abend, Armin Beverungen, Marcus Burkhardt, Timo Kaerlein, Tatjana Seitz, Nadine TahaIn dieser Ausgabe der "Navigationen" sammeln wir Ressourcen gegen die Vereinnahmung der Universität durch die so genannte Neue Rechte. Auslöser für das Themenheft sind die Geschehnisse rund um ein Seminar, das im Wintersemester 2018/19 unter dem Titel „Denken und Denken lassen. Zur Philosophie und Praxis der Meinungsfreiheit“ an der Universität Siegen angeboten wurde.Das Seminar wurde von einer Vorlesungsreihe flankiert, in der „dezidiert konservative oder rechte Denker“ eine Bühne bekamen, u.a. Marc Jongen von der AfD, und der Autor Thilo Sarrazin. Ein zentrales Anliegen dieser Ausgabe ist es, die Siegener Ereignisse zu dokumentieren, wissenschaftlich aufzuarbeiten und in verschiedenen Hinsichten zu kontextualisieren: diskursstrategisch, geographisch, historisch und politisch. Hierzu versammelt das Heft Beiträge diverser Forschungsdisziplinen – explizit auch von Vertreter*innen derjenigen Disziplinen, deren Existenzrecht von Teilen der Siegener Vortragenden in Zweifel gezogen wird. Um die Diversität der betroffenen Zugänge zu repräsentieren, sind über die Medienwissenschaft hinaus Beiträge aus der Islamwissenschaft, den Gender Studies, der Linguistik und der Soziologie im Heft vertreten

Hydrodynamic stability of rotationally supported flows: Linear and nonlinear 2D shearing box results

We present here both analytical and numerical results of hydrodynamic stability investigations of rotationally supported circumstellar flows using the shearing box formalism. Asymptotic scaling arguments justifying the shearing box approximation are systematically derived, showing that there exist two limits which we call small shearing box (SSB) and large shearing box (LSB). The physical meaning of these two limits and their relationship to model equations implemented by previous investigators are discussed briefly. Two dimensional (2D) dynamics of the SSB are explored and shown to contain transiently growing (TG) linear modes, whose nature is first discussed within the context of linear theory. The fully nonlinear regime in 2D is investigated numerically for very high Reynolds (Re) numbers. Solutions exhibiting sustained dynamics are found and manifest episodic but recurrent TG behavior and these are associated with the formation and long-term survival of coherent vortices. The life-time of this spatio-temporal complexity depends on the Re number and the strength and nature of the initial disturbance. We show results for a case in which the dynamical activity persists for the entire duration of the simulation (hundreds of box orbits). Some combinations of the Re number and the initial perturbation spectrum (and strength) show the transiently growing phenomenon to ultimately fade away or, in some instances, to be absent altogether. Because the SSB approximation used here is equivalent to a 2D incompressible flow, the dynamics can not depend on the Coriolis force. Therefore, three dimensional (3D) simulations are needed in order to decide if this force indeed suppresses nonlinear hydrodynamical instability in rotationally supported disks in the shearing box.Comment: Submitted to A+A on April 1, 2004, Accepted August 3, 200

Stability and instability of hydromagnetic Taylor–Couette flows

Decades ago S. Lundquist, S. Chandrasekhar, P. H. Roberts and R. J. Tayler first posed questions about the stability of Taylor–Couette flows of conducting material under the influence of large-scale magnetic fields. These and many new questions can now be answered numerically where the nonlinear simulations even provide the instability-induced values of several transport coefficients. The cylindrical containers are axially unbounded and penetrated by magnetic background fields with axial and/or azimuthal components. The influence of the magnetic Prandtl number Pm on the onset of the instabilities is shown to be substantial. The potential flow subject to axial fields becomes unstable against axisymmetric perturbations for a certain supercritical value of the averaged Reynolds number Rm¯=√Re⋅Rm (with Re the Reynolds number of rotation, Rm its magnetic Reynolds number). Rotation profiles as flat as the quasi-Keplerian rotation law scale similarly but only for Pm≫1 while for Pm≪1 the instability instead sets in for supercritical Rm at an optimal value of the magnetic field. Among the considered instabilities of azimuthal fields, those of the Chandrasekhar-type, where the background field and the background flow have identical radial profiles, are particularly interesting. They are unstable against nonaxisymmetric perturbations if at least one of the diffusivities is non-zero. For Pm≪1 the onset of the instability scales with Re while it scales with Rm¯ for Pm≫1. Even superrotation can be destabilized by azimuthal and current-free magnetic fields; this recently discovered nonaxisymmetric instability is of a double-diffusive character, thus excluding Pm=1. It scales with Re for Pm→0 and with Rm for Pm→∞. The presented results allow the construction of several new experiments with liquid metals as the conducting fluid. Some of them are described here and their results will be discussed together with relevant diversifications of the magnetic instability theory including nonlinear numerical studies of the kinetic and magnetic energies, the azimuthal spectra and the influence of the Hall effect

Incidence and prevalence of patellofemoral pain: a systematic review and meta-analysis

Background: Patellofemoral pain is considered one of the most common forms of knee pain, affecting adults, adolescents, and physically active populations. Inconsistencies in reported incidence and prevalence exist and in relation to the allocation of healthcare and research funding, there is a clear need to accurately understand the epidemiology of patellofemoral pain. Methods: An electronic database search was conducted, as well as grey literature databases, from inception to June 2017. Two authors independently selected studies, extracted data and appraised methodological quality. If heterogeneous, data were analysed descriptively. Where studies were homogeneous, data were pooled through a meta-analysis. Results: 23 studies were included. Annual prevalence for patellofemoral pain in the general population was reported as 22.7%, and adolescents as 28.9%. Incidence rates in military recruits ranged from 9.7 – 571.4/1,000 person-years, amateur runners in the general population at 1080.5/1,000 person-years and adolescents amateur athletes 5.1% - 14.9% over 1 season. One study reported point prevalence within military populations as 13.5%. The pooled estimate for point prevalence in adolescents was 7.2% (95% Confidence Interval: 6.3% - 8.3%), and in female only adolescent athletes was 22.7% (95% Confidence Interval 17.4% - 28.0%). Conclusion: This review demonstrates high incidence and prevalence levels for patellofemoral pain. Within the context of this, and poor long term prognosis and high disability levels, PFP should be an urgent research priority

Smart rollerski - radius pultrusion in application: Poster presentedt at 5th International Composites Conference, ICC 2019, 10. - 12. September 2019, Stuttgart, im Rahmen der Fachmesse COMPOSITES EUROPE

Lightweight applications made of fiber-reinforced plastics have been used in top-class sports for many years. With an innovative rollerski – developed in the joint project "SmartFrame +" funded by the BMBF – different target groups are addressed. On the one hand, users who are looking for fun and physical exercise. On the other hand, there are winter sports enthusiasts who want to improve their skiing skills during the summer break. Especially in this case, the challenge is to achieve a congruence in motion compared to the classic winter ski and thus to train the motor skills and muscle groups targeted. This will be supported by integrated sensors

Smartes Leichtgewicht auf Rollen: Sensorierter Skiroller in Leichtbauweise aus Glas- und Kohlenstofffaserhalbzeugen

Leichte Anwendungen aus Faser-Kunststoff-Verbunden werden bereits seit Jahrzehnten im Spitzensport eingesetzt. Ein innovativer Skiroller – entwickelt in dem vom BMBF geförderten Verbundvorhaben „SmartFrame

Neuartige Belastungssensoren für den Leichtbau

Leichtbaustrukturen lassen sich optimieren indem das Leichtbaupotential durch eine Reduzierung des Sicherheitsfaktors effizienter ausgeschöpft wird. Bei Reduzierung von Sicherheitsreserven ist es sinnvoll eine Belastungsüberwachung zu implementieren. Durch eine Belastungsüberwachung ist es außerdem möglich die maximale Standzeit von Bauteilen den real aufgetretenen Beanspruchungen entsprechend auszunutzen. Eine Belastungsüberwachung bietet auch die Möglichkeit Überbeanspruchungen oder Fehlhandhabungen zu erkennen und unberechtigte Gewährleistungsfälle zu vermeiden. Konventionelle Systeme zur Belastungsüberwachung weisen wesentliche Nachteile hinsichtlich Ermüdungsbeständigkeit, Sensitivität, Dehnbarkeit oder Kosten auf. Eine neuartige Sensortechnologie basierend auf einer Formgedächtnislegierung stellt einen Lösungsansatz zur Überwindung dieser Nachteile dar. Formgedächtnislegierungen lassen sich in Drahtform als Sensorfilament in faserverstärkte Kunststoffstrukturen integrieren. Die Umsetzbarkeit im Pultrusionsprozess und die Nutzung des Messsignals eines strukturintegrierten Sensorfilament zur Ermittlung von Biege- beziehungsweise Zug- und Druckbelastungen wurde am Fraunhofer IWU erstmals nachgewiesen. Teile dieser Arbeit entstanden im Rahmen des Bundesexzellenzcluster EXC 1075 „Technologiefusion für multifunktionale Leichtbaustrukturen“ und wurde von der Deutschen Forschungsgemeinschaft gefördert. Die Autoren danken für die finanzielle Unterstützung