24,035 research outputs found
NLO Corrections to Deeply-Virtual Compton Scattering
We have calculated the NLO corrections to the twist-2 part of the
deeply-virtual Compton scattering amplitude. Our results for the transverse and
antisymmetric parts agree with recent calculations by Ji and Osborne and by
Belitsky and M\"uller. In addition we present NLO results for the longitudinal
part of the amplitude.Comment: 8 pages, Latex. Error in polarised gluonic coefficient in Eq.(8)
correcte
A simulation of solar convection at supergranulation scale
We present here numerical simulations of surface solar convection which cover
a box of 303.2 Mm with a resolution of
31582, which is used to investigate the dynamics of scales
larger than granulation. No structure resembling supergranulation is present;
possibly higher Reynolds numbers (i.e. higher numerical resolution), or
magnetic fields, or greater depth are necessary. The results also show
interesting aspects of granular dynamics which are briefly presented, like
extensive p-mode ridges in the k- diagram and a ringlike distribution
of horizontal vorticity around granules. At large scales, the horizontal
velocity is much larger than the vertical velocity and the vertical motion is
dominated by p-mode oscillations.Comment: Contribution to the proceedings of the workshop entitled "THEMIS and
the new frontiers of solar atmosphere dynamics" (March 2001), 6 pages, to
appear in Nuovo Cimento
Adjointness Relations as a Criterion for Choosing an Inner Product
This is a contribution to the forthcoming book "Canonical Gravity: {}From
Classical to Quantum" edited by J. Ehlers and H. Friedrich. Ashtekar's
criterion for choosing an inner product in the quantisation of constrained
systems is discussed. An erroneous claim in a previous paper is corrected and a
cautionary example is presented.Comment: 6 pages, MPA-AR-94-
Control of multiferroic domains by external electric fields in TbMnO3
The control of multiferroic domains through external electric fields has been
studied by dielectric measurements and by polarized neutron diffraction on
single-crystalline TbMnO. Full hysteresis cycles were recorded by varying
an external field of the order of several kV/mm and by recording the chiral
magnetic scattering as well as the charge in a sample capacitor. Both methods
yield comparable coercive fields that increase upon cooling.Comment: 12 pages, 6 figure
Research review: young people leaving care
This paper reviews the international research on young people leaving care. Set in the context of a social exclusion framework, it explores young people's accelerated and compressed transitions to adulthood, and discusses the development and classification of leaving care services in responding to their needs. It then considers the evidence from outcome studies and argues that adopting a resilience framework suggests that young people leaving care may fall into three groups: young people 'moving on', 'survivors' and 'victims'. In concluding, it argues that these three pathways are associated with the quality of care young people receive, their transitions from care and the support they receive after care
Flexible provisioning of Web service workflows
Web services promise to revolutionise the way computational resources and business processes are offered and invoked in open, distributed systems, such as the Internet. These services are described using machine-readable meta-data, which enables consumer applications to automatically discover and provision suitable services for their workflows at run-time. However, current approaches have typically assumed service descriptions are accurate and deterministic, and so have neglected to account for the fact that services in these open systems are inherently unreliable and uncertain. Specifically, network failures, software bugs and competition for services may regularly lead to execution delays or even service failures. To address this problem, the process of provisioning services needs to be performed in a more flexible manner than has so far been considered, in order to proactively deal with failures and to recover workflows that have partially failed. To this end, we devise and present a heuristic strategy that varies the provisioning of services according to their predicted performance. Using simulation, we then benchmark our algorithm and show that it leads to a 700% improvement in average utility, while successfully completing up to eight times as many workflows as approaches that do not consider service failures
Magnetoelastic coupling in RETiO3 (RE = La, Nd, Sm, Gd, Y)
A detailed analysis of the crystal structure in RETiO3 with RE = La, Nd, Sm,
Gd, and Y reveals an intrinsic coupling between orbital degrees of freedom and
the lattice which cannot be fully attributed to the structural deformation
arising from bond-length mismatch. The TiO6 octahedra in this series are all
irregular with the shape of the distortion depending on the RE ionic radius.
These octahedron distortions vary more strongly with temperature than the tilt
and rotation angles. Around the Ti magnetic ordering all compounds exhibit
strong anomalies in the thermal-expansion coefficients, these anomalies exhibit
opposite signs for the antiferromagnetic and ferromagnetic compounds.
Furthermore the strongest effects are observed in the materials close to the
magnetic cross-over from antiferromagnetic to ferromagnetic order
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