Beam shaping using genetically optimized two-dimensional photonic crystals

We propose the use of two-dimensional photonic crystals with engineered defects for the generation of an arbitrary-profile beam from a focused input beam. The cylindrical harmonics expansion of complex-source beams is derived and used to compute the scattered wavefunction of a 2D photonic crystal via the multiple scattering method. The beam shaping problem is then solved using a genetic algorithm. We illustrate our procedure by generating different orders of Hermite-Gauss profiles, while maintaining reasonable losses and tolerance to variations in the input beam and the slab refractive index

Psychopolitics: Peter Sedgwick’s legacy for mental health movements

This paper re-considers the relevance of Peter Sedgwick's Psychopolitics (1982) for a politics of mental health. Psychopolitics offered an indictment of ‘anti-psychiatry’ the failure of which, Sedgwick argued, lay in its deconstruction of the category of ‘mental illness’, a gesture that resulted in a politics of nihilism. ‘The radical who is only a radical nihilist’, Sedgwick observed, ‘is for all practical purposes the most adamant of conservatives’. Sedgwick argued, rather, that the concept of ‘mental illness’ could be a truly critical concept if it was deployed ‘to make demands upon the health service facilities of the society in which we live’. The paper contextualizes Psychopolitics within the ‘crisis tendencies’ of its time, surveying the shifting welfare landscape of the subsequent 25 years alongside Sedgwick's continuing relevance. It considers the dilemma that the discourse of ‘mental illness’ – Sedgwick's critical concept – has fallen out of favour with radical mental health movements yet remains paradigmatic within psychiatry itself. Finally, the paper endorses a contemporary perspective that, while necessarily updating Psychopolitics, remains nonetheless ‘Sedgwickian’

The phenomenon of "pe-ischaemic conditioning" in the brain only partly involves the NMDA receptor: A magnetic resonance study

We have investigated in more detail our previous observations on a form of ischaemic pre-conditioning "metabolic adaptation", i.e.-that sequential metabolic insults (hypoxia followed 40 min later by combined hypoxia + hypoglycaemia, or vice versa) are less injurious (monitored by increased [Ca 2+] i and decreased PCr) than the immediate combined insult. We have now observed that the "adaptation" occurs between 10 and 20 min. Pre-treatment of the tissues with 10 μM-MK801 showed that it had no effect on the increase in [Ca 2+] i caused by the sequential insult and only partially blocked the increase observed by exposure to the immediate combined insult. Exposure to both the delayed and immediate combined insults with low extracellular Ca 2+ resulted in a two-fold increase in [Ca 2+] i , similar to the increase observed with normal extracellular Ca 2+ in the presence of MK801. The results are discussed in terms of the possible origins of the increases in [Ca 2+] i