28,058 research outputs found
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 -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
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
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
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
SIMLA: Simulating laser-particle interactions via classical and quantum electrodynamics
We present the Fortran code SIMLA, which is designed for the study of charged
particle dynamics in laser and other background fields. This can be done
classically via the Landau-Lifshitz equation, or alternatively, via the
simulation of photon emission events determined by strong-field
quantum-electrodynamics amplitudes and implemented using Monte-Carlo type
routines. Multiple laser fields can be included in the simulation and the
propagation direction, beam shape (plane wave, focussed paraxial, constant
crossed, or constant magnetic), and time envelope of each can be independently
specified.Comment: Submitted to Comp. Phys. Comm. The associated computer program and
corresponding manual will be made available on the CPC librar
Non-equilibrium phenomena and molecular reaction dynamics: mode space, energy space and conformer space
status: publishe
A Q-methodology study of parental understandings of infant immunisation : implications for health-care advice.
This study used Q-methodology to explore systematically parental judgements about infant immunisation. A total of 45 parents completed a 31-statement Q-sort. Data were collected after vaccination in general practitioner practices or a private day nursery. Q factor analysis revealed four distinct viewpoints: a duty to immunise based on medical benefits, child-orientated protection based on parental belief, concern and distress and surprise at non-compliance. Additionally, there was a common view among parents that they did not regret immunising their children. Implications of these results are discussed in terms of health-care policy and future research
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