Reflexive Learning and Performative Failure

In this paper we emphasize the importance of context for student learning. Based on reflective logs and interview data, we explore how students learn outside of the classroom as they undertake an experiential dissertation project. We identify three different forms of reflexive learning and critique, all triggered by some form of performative failure; scholarly critique, engaged critique and engaged action. Drawing on Butler’s theory of performativity we illustrate how reflexivity is not purely the action of any individual student, rather it is a practice that is co-created within a certain context. As such, we contest individualistic understandings of reflexivity and encourage a careful consideration of the places students and managers are encouraged to be reflexive

Decentering the learner through alternative organizations

This paper builds on previous studies of experiential learning, reflexivity in management learning, and accounts of teaching through alternative organizations. We theorize management learning from the perspective of students who worked with and researched organizations that present an alternative to typical organizational forms and performative intent. Through an analysis of interviews and reflective diaries, we investigate how students learn in such environments and argue that theories of learning must account for how contexts, in which the performance of profit-orientation breaks down, induce reflexivity. In particular, we draw attention to the role such contexts play in challenging students to dwell in inconsistencies, ambiguities, contradictions and non-linear ideas. Drawing upon the work of Judith Butler’s theory of performativity we illustrate that such reflexivity is not an individual capacity but a contextual practice. Subsequently, by ‘decentering the learner’ we develop upon existing ideas on reflexive practitioners and develop the burgeoning literature on alternative organizations. We conclude by making the argument that management education, whether critical or not, needs to go beyond awareness and through to responsible action. Such action does not rely on more tools or concepts for individuals but experiences of inhabiting an increasingly ambiguous and complex world

Hairy Black Holes, Horizon Mass and Solitons

Properties of the horizon mass of hairy black holes are discussed with emphasis on certain subtle and initially unexpected features. A key property suggests that hairy black holes may be regarded as `bound states' of ordinary black holes without hair and colored solitons. This model is then used to predict the qualitative behavior of the horizon properties of hairy black holes, to provide a physical `explanation' of their instability and to put qualitative constraints on the end point configurations that result from this instability. The available numerical calculations support these predictions. Furthermore, the physical arguments are robust and should be applicable also in more complicated situations where detailed numerical work is yet to be carried out.Comment: 25 pages, 5 (new) figures. Revtex file. Final version to appear in CQ

Global Extensions of Spacetimes Describing Asymptotic Final States of Black Holes

We consider a globally hyperbolic, stationary spacetime containing a black hole but no white hole. We assume, further, that the event horizon, \tn, of the black hole is a Killing horizon with compact cross-sections. We prove that if surface gravity is non-zero constant throughout the horizon one can {\it globally} extend such a spacetime so that the image of $\cal N$ is a proper subset of a regular bifurcate Killing horizon in the enlarged spacetime. The necessary and sufficient conditions are given for the extendibility of matter fields to the enlarged spacetime. These conditions are automatically satisfied if the spacetime is static (and, hence ``$t$"-reflection symmetric) or stationary-axisymmetric with ``$t-\phi$" reflection isometry and the matter fields respect the reflection isometry. In addition, we prove that a necessary and sufficient condition for the constancy of the surface gravity on a Killing horizon is that the exterior derivative of the twist of the horizon Killing field vanish on the horizon. As a corollary of this, we recover a result of Carter that constancy of surface gravity holds for any black hole which is static or stationary- axisymmetric with the ``$t-\phi$" reflection isometry. No use of Einstein's equation is made in obtaining any of the above results. Taken together, these results support the view that any spacetime representing the asymptotic final state of a black hole formed by gravitational collapse may be assumed to possess a bifurcate Killing horizon or a Killing horizon with vanishing surface gravity.Comment: 20 pages, plain te

CD4 T cells remain the major source of HIV-1 during end stage disease.

OBJECTIVE: To assess the source of HIV-1 production in lymphoid tissue biopsies from HIV-infected patients, with no prior anti-retroviral protease inhibitor treatment, with a CD4 cell count > 150 x 10(6)/l (group I) or < 50 x 10(6)/l (group II), co-infected with Mycobacterium tuberculosis or Mycobacterium avium complex. DESIGN AND METHODS: Lymphoid tissue biopsies from 11 HIV-1-infected patients, taken for diagnostic purposes, were studied by HIV-1 RNA in situ hybridization and immunohistochemistry. RESULTS: Patients of group I showed well organized granulomas, in contrast with patients of group II, in which granuloma formation was absent. HIV-1 RNA-positive cells in group I patients were found mainly around the granulomas, whereas in group II HIV-1-producing cells were confined to areas with remaining intact lymphoid tissue. Despite the abundant presence of macrophages, the productively infected HIV-1-positive cells in both groups were almost exclusively CD4 T cells. CONCLUSION: In contrast with previously published data, CD4 T cells appear to remain the major source of HIV-1 production in end-stage disease

Mechanisms of THz generation from silver nanoparticle and nanohole arrays illuminated by 100 fs pulses of infrared light

Copyright © 2014 American Physical SocietyWe study THz pulses generated from plasmonic metal nanostructures under femtosecond illumination of near-IR light. We find two regimes of excitation, according to the order of the dependence of the THz fluence on the incident near-IR intensity: less then second order at low intensities, changing to approximately fourth order for higher intensities. These regimes are most likely associated with two THz generation mechanisms: optical rectification, and the ponderomotive acceleration of ejected electrons. These data provide evidence that both mechanisms can be at work in the same experiment.Hungarian Scientific Research FundBolyai FellowshipPostdoctoral Fellowship of the Hungarian Academy of SciencesMarie Curie Fellowship of the EU (project acronym `UPNEX'

Mechanisms of THz generation from silver nanoparticle and nanohole arrays illuminated by 100 fs pulses of infrared light

Copyright © 2014 American Physical SocietyWe study THz pulses generated from plasmonic metal nanostructures under femtosecond illumination of near-IR light. We find two regimes of excitation, according to the order of the dependence of the THz fluence on the incident near-IR intensity: less then second order at low intensities, changing to approximately fourth order for higher intensities. These regimes are most likely associated with two THz generation mechanisms: optical rectification, and the ponderomotive acceleration of ejected electrons. These data provide evidence that both mechanisms can be at work in the same experiment.Hungarian Scientific Research FundBolyai FellowshipPostdoctoral Fellowship of the Hungarian Academy of SciencesMarie Curie Fellowship of the EU (project acronym `UPNEX'

Autoreactive marginal zone B cells are spontaneously activated but lymph node B cells require T cell help

In K/BxN mice, arthritis is induced by autoantibodies against glucose-6-phosphate-isomerase (GPI). To investigate B cell tolerance to GPI in nonautoimmune mice, we increased the GPI-reactive B cell frequency using a low affinity anti-GPI H chain transgene. Surprisingly, anti-GPI B cells were not tolerant to this ubiquitously expressed and circulating autoantigen. Instead, they were found in two functionally distinct compartments: an activated population in the splenic marginal zone (MZ) and an antigenically ignorant one in the recirculating follicular/lymph node (LN) pool. This difference in activation was due to increased autoantigen availability in the MZ. Importantly, the LN anti-GPI B cells remained functionally competent and could be induced to secrete autoantibodies in response to cognate T cell help in vitro and in vivo. Therefore, our study of low affinity autoreactive B cells reveals two distinct but potentially concurrent mechanisms for their activation, of which one is T cell dependent and the other is T cell independent