20,387 research outputs found
Is a Dominant Service-Centric Sector Good for Diversity of Provision?
An obvious assumption underpinning the immense interest in service-oriented computing is that it is an inherently Good Thing, by which we mean that robust processes and tools for developing service-based systems will bring benefits for service providers and service consumers. The arguments, in terms of consumer choice and flexibility, are certainly quite convincing. However, in this position paper, we question the nature of the underlying assumption, in a world where requirements are as many and varied as potential users and ask if safeguards are needed to ensure that diversity of provision is maintained
Initial post-buckling behavior of toroidal shell segments
Initial post-buckling behavior of toroidal shell segment
Buckling of imperfect cylindrical shells under axial compression and external pressure
Axisymmetric deformation effects on cylindrical shell buckling under axial compressio
Fisher Hartwig determinants, conformal field theory and universality in generalised XX models
We discuss certain quadratic models of spinless fermions on a 1D lattice, and
their corresponding spin chains. These were studied by Keating and Mezzadri in
the context of their relation to the Haar measures of the classical compact
groups. We show how these models correspond to translation invariant models on
an infinite or semi-infinite chain, which in the simplest case reduce to the
familiar XX model. We give physical context to mathematical results for the
entanglement entropy, and calculate the spin-spin correlation functions using
the Fisher-Hartwig conjecture. These calculations rigorously demonstrate
universality in classes of these models. We show that these are in agreement
with field theoretic and renormalization group arguments that we provide
On relations between one-dimensional quantum and two-dimensional classical spin systems
We exploit mappings between quantum and classical systems in order to obtain
a class of two-dimensional classical systems with critical properties
equivalent to those of the class of one-dimensional quantum systems discussed
in a companion paper (J. Hutchinson, J. P. Keating, and F. Mezzadri,
arXiv:1503.05732). In particular, we use three approaches: the Trotter-Suzuki
mapping; the method of coherent states; and a calculation based on commuting
the quantum Hamiltonian with the transfer matrix of a classical system. This
enables us to establish universality of certain critical phenomena by extension
from the results in our previous article for the classical systems identified.Comment: 36 page
Nonlinear quantum optical computing via measurement
We show how the measurement induced model of quantum computation proposed by
Raussendorf and Briegel [Phys. Rev. Letts. 86, 5188 (2001)] can be adapted to a
nonlinear optical interaction. This optical implementation requires a Kerr
nonlinearity, a single photon source, a single photon detector and fast feed
forward. Although nondeterministic optical quantum information proposals such
as that suggested by KLM [Nature 409, 46 (2001)] do not require a Kerr
nonlinearity they do require complex reconfigurable optical networks. The
proposal in this paper has the benefit of a single static optical layout with
fixed device parameters, where the algorithm is defined by the final
measurement procedure.Comment: 14 pages, 4 figures, 4 table
Commentary : missing targets on drugs-related deaths, and a Scottish paradox
The 10-year drug strategy for England and Wales was published in February 2008. It dropped drugs-related deaths (DRDs) as a key performance indicator. Scotland retained a necessary strong focus on DRDs. Scotland's DRDs numbered 1006 in 2000–02 and 1009 in 2003–05. The previous Scottish administration's claim that its number of current injectors had decreased substantially between 2000 and 2003 implied, paradoxically, that their DRD rate would have to have increased. Worse was to come: Scotland's DRDs had increased to 876 in 2006 + 2007. We analyse UK's DRDs by sex and age-group to reveal temporal trends (2000–02 versus 2003–05 versus 2006 + 2007) with different public health and epidemiological implications. We also address the above Scottish paradox and assess, by age-group, how consistent Scotland's 876 DRDs in 2006 + 2007 are with Scottish injectors’ DRD rate in 2003–05 of around 1 per 100 injector-years. Public health success in the UK in reducing DRDs at younger ages should not be overshadowed by the late consequence in terms of older-age DRDs of UK's injector epidemics; in the early 1980s in Scotland, and late 1980s in England and Wales. Targets for reducing DRDs should pay heed to UK's injector epidemics
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