Energy conservation and numerical stability for the reduced MHD models of the non-linear JOREK code

In this paper we present a rigorous derivation of the reduced MHD models with and without parallel velocity that are implemented in the non-linear MHD code JOREK. The model we obtain contains some terms that have been neglected in the implementation but might be relevant in the non-linear phase. These are necessary to guarantee exact conservation with respect to the full MHD energy. For the second part of this work, we have replaced the linearized time stepping of JOREK by a non-linear solver based on the Inexact Newton method including adaptive time stepping. We demonstrate that this approach is more robust especially with respect to numerical errors in the saturation phase of an instability and allows to use larger time steps in the non-linear phase

Open Education and the emancipation of academic labour

I have previously argued that open education is a liberal project with a focus on the freedom of things rather than the freedom of people (Winn, Joss. 2012. “Open Education: From the Freedom of Things to the Freedom of People.” In Towards Teaching in Public: Reshaping the Modern University, edited by Michael Neary, Howard Stevenson, and Les Bell, 133– 147. London: Continuum). Furthermore, I have argued that despite an implicit critique of private property with its emphasis on ‘the commons’, the literature on open education offers no corresponding critique of academic labour (Neary, Mike, and Joss Winn. 2012. “Open Education: Common(s), Commonism and the New Common Wealth.” Ephemera: Theory & Politics in Organization 12 (4): 406–422). In this paper, I develop my critical position that an emancipatory form of education must work towards the emancipation of teachers and students from labour, the dynamic, social, creative source of value in capitalism. In making this argument, I first establish the fundamental characteristics of academic labour. I then offer a ‘form-analytic’ critique of open access, followed by a corresponding critique of its legal form. Finally, I critically discuss the potential of ‘open cooperatives’ as a transitional organisational form for the production of knowledge through which social relations become ‘transparent in their simplicity’ (Marx, Karl. 1976. Capital, Vol. 1. London: Penguin Classics, 172)

Neurobehavioral Mechanisms of Temporal Processing Deficits in Parkinson's Disease

Parkinson's disease (PD) disrupts temporal processing, but the neuronal sources of deficits and their response to dopamine (DA) therapy are not understood. Though the striatum and DA transmission are thought to be essential for timekeeping, potential working memory (WM) and executive problems could also disrupt timing.The present study addressed these issues by testing controls and PD volunteers 'on' and 'off' DA therapy as they underwent fMRI while performing a time-perception task. To distinguish systems associated with abnormalities in temporal and non-temporal processes, we separated brain activity during encoding and decision-making phases of a trial. Whereas both phases involved timekeeping, the encoding and decision phases emphasized WM and executive processes, respectively. The methods enabled exploration of both the amplitude and temporal dynamics of neural activity. First, we found that time-perception deficits were associated with striatal, cortical, and cerebellar dysfunction. Unlike studies of timed movement, our results could not be attributed to traditional roles of the striatum and cerebellum in movement. Second, for the first time we identified temporal and non-temporal sources of impaired time perception. Striatal dysfunction was found during both phases consistent with its role in timekeeping. Activation was also abnormal in a WM network (middle-frontal and parietal cortex, lateral cerebellum) during encoding and a network that modulates executive and memory functions (parahippocampus, posterior cingulate) during decision making. Third, hypoactivation typified neuronal dysfunction in PD, but was sometimes characterized by abnormal temporal dynamics (e.g., lagged, prolonged) that were not due to longer response times. Finally, DA therapy did not alleviate timing deficits.Our findings indicate that impaired timing in PD arises from nigrostriatal and mesocortical dysfunction in systems that mediate temporal and non-temporal control-processes. However, time perception impairments were not improved by DA treatment, likely due to inadequate restoration of neuronal activity and perhaps corticostriatal effective-connectivity

Jahrbuch Netzpolitik 2012 : von A wie ACTA bis Z wie Zensur

The authors give a review on different aspects of internet governance in 2012