In Situ Characterization of Ultraintense Laser Pulses

We present a method for determining the characteristics of an intense laser pulse by probing it with a relativistic electron beam. After an initial burst of very high-energy $\gamma$-radiation the electrons proceed to emit a series of attosecond duration X-ray pulses as they leave the field. These flashes provide detailed information about the interaction, allowing us to determine properties of the laser pulse: something that is currently a challenge for ultra-high intensity laser systems.Comment: 9 pages, 8 figure

Transverse spreading of electrons in high-intensity laser fields

We show that for collisions of electrons with a high-intensity laser, discrete photon emissions introduce a transverse beam spread which is distinct from that due to classical (or beam shape) effects. Via numerical simulations, we show that this quantum induced transverse momentum gain of the electron is manifest in collisions with a realistic laser pulse of intensity within reach of current technology, and we propose it as a measurable signature of strong-field quantum electrodynamics.Comment: 5 pages, 3 figures. Accepted for publication in Physical Review Letter

Marx's Economy and Beyond

Following renewed interest in Marx?s political economy in the wake of the financial crisis, the paper aims to make a contribution to debates re-evaluating Marx?s theory of capitalism and his conceptualisation of the relationship between the polity and economy. We bring together our approaches from political philosophy, economic sociology, and political economy, making the case for a renewal of historical materialism. We develop a perspective of a radically politicised economy, rather than treating polity and economy as separate spheres. The political implications of this perspective involve an insistence on political and economic democratisation and human rights as an integral part of any socially egalitarian alternatives to capitalist political economies. The paper, written without the full academic paraphernalia, engages with current defences of the classical Marxist understanding of exploitation, especially the labour theory of value, and presents an alternative, neo-Polanyian analysi

Non-equilibrium phenomena and molecular reaction dynamics: mode space, energy space and conformer space

status: publishe

Natio et gens: Venice biennale 2009

The following is an informal reflection on the changing place of nationality and national consciousness in cultural life with reference to last year’s Biennale. Having drawn tentative inferences regarding the roles of these, we offer a selective review of what appear to us to be the most memorable national representations. These in turn suggest a paradoxical benefit which an awareness of localised histories may bring to artistic production

Synergies between processing and memory in children's reading span.

Previous research has established the relevance of working memory for cognitive development. Yet the factors responsible for shaping performance in the complex span tasks used to assess working memory capacity are not fully understood. We report a study of reading span in 7- to 11-year old children that addresses several contemporary theoretical issues. We demonstrate that both the timing and the accuracy of recall are affected by the presence or absence of a semantic connection between the processing requirement and the memoranda. Evidence that there can be synergies between processing and memory argues against the view that complex span simply measures the competition between these activities. We also demonstrate a consistent relationship between the rate of completing processing operations (sentence reading) and recall accuracy. At the same time, the shape and strength of this function varies with the task configuration. Taken together, these results demonstrate the potential for reconstructive influences to shape working memory performance among children

Weight One Jacobi Forms and Umbral Moonshine

We analyze holomorphic Jacobi forms of weight one with level. One such form plays an important role in umbral moonshine, leading to simplifications of the statements of the umbral moonshine conjectures. We prove that non-zero holomorphic Jacobi forms of weight one do not exist for many combinations of index and level, and use this to establish a characterization of the McKay--Thompson series of umbral moonshine in terms of Rademacher sums.Comment: 41 pages, 39 table