2,232 research outputs found
Products of multisymplectic manifolds and homotopy moment maps
Multisymplectic geometry admits an operation that has no counterpart in
symplectic geometry, namely, taking the product of two multisymplectic
manifolds endowed with the wedge product of the multisymplectic forms. We show
that there is an L-infinity-embedding of the L-infinity-algebra of observables
of the individual factors into the observables of the product, and that
homotopy moment maps for the individual factors induce a homotopy moment map
for the product. As a by-product, we associate to every multisymplectic form a
curved L-infinity-algebra, whose curvature is the multisymplectic form itself.Comment: 27 pages. Version to be published in Journal of Lie Theor
Spin(7)-manifolds in compactifications to four dimensions
We describe off-shell M-theory compactifications down to four
dimensions in terms of eight-dimensional manifolds equipped with a topological
-structure. Motivated by the exceptionally generalized geometry
formulation of M-theory compactifications, we consider an eight-dimensional
manifold equipped with a particular set of tensors
that allow to naturally embed in a family of
-structure seven-dimensional manifolds as the leaves of a
codimension-one foliation. Under a different set of assumptions,
allows to make into a principal bundle, which is
equipped with a topological -structure if the base is equipped with a
topological -structure. We also show that can be
naturally used to describe regular as well as a singular elliptic fibrations on
, which may be relevant for F-theory applications, and prove
several mathematical results concerning the relation between topological
-structures in seven dimensions and topological -structures in
eight dimensions.Comment: 50 pages. We have included Proposition 6.4 about elliptic fibrations
in relation to a pair of vector fields. We have also included Remark 5.13,
thanks to an internal communication by Dominic Joyce. Discussion about the
relation of singular foliations and D7-branes include
Adding integrable defects to the Boussinesq equation
The purpose of this paper is to extend the store of models able to support
integrable defects by investigating the two-dimensional Boussinesq nonlinear
wave equation. As has been previously noted in many examples, insisting that a
defect contributes to energy and momentum to ensure their conservation, despite
the presence of discontinuities and the explicit breaking of translation
invariance, leads to sewing conditions relating the two fields and their
derivatives on either side of the defect. The manner in which several types of
soliton solutions to the Boussinesq equation are affected by the defect is
explored and reveals new effects that have not been observed in other
integrable systems, such as the possibility of a soliton reflecting from a
defect or of a defect decaying into one or two solitons.Comment: 28 pages, 9 figure
Integrable defects at junctions within a network
The purpose of this article is to explore the properties of integrable, purely transmitting, defects placed at the junctions of several one-dimensional domains within a network. The defect sewing conditions turn out to be quite restrictive—for example, requiring the number of domains meeting at a junction to be even—and there is a clear distinction between the behaviour of conformal and massive integrable models. The ideas are mainly developed within classical field theory and illustrated using a variety of field theory models defined on the branches of the network, including both linear and nonlinear examples
Type II defects revisited
Energy and momentum conservation in the context of a type II, purely transmitting, defect, within a single scalar relativistic two-dimensional field theory, places a severe constraint not only on the nature of the defect but also on the potentials for the scalar fields to either side of it. The constraint is of an unfamiliar type since it requires the Poisson Bracket of the defect contributions to energy and momentum with respect to the defect discontinuity and its conjugate to be balanced by the potential difference across the defect. It is shown that the only solutions to the constraint correspond to the known integrable field theories
Risk and protective factors for meningococcal disease in adolescents: matched cohort study
Objective: To examine biological and social risk factors for
meningococcal disease in adolescents.
Design: Prospective, population based, matched cohort study
with controls matched for age and sex in 1:1 matching.
Controls were sought from the general practitioner.
Setting: Six contiguous regions of England, which represent
some 65% of the country’s population.
Participants: 15-19 year olds with meningococcal disease
recruited at hospital admission in six regions (representing 65%
of the population of England) from January 1999 to June 2000,
and their matched controls.
Methods: Blood samples and pernasal and throat swabs were
taken from case patients at admission to hospital and from
cases and matched controls at interview. Data on potential risk
factors were gathered by confidential interview. Data were
analysed by using univariate and multivariate conditional
logistic regression.
Results: 144 case control pairs were recruited (74 male (51%);
median age 17.6). 114 cases (79%) were confirmed
microbiologically. Significant independent risk factors for
meningococcal disease were history of preceding illness
(matched odds ratio 2.9, 95% confidence interval 1.4 to 5.9),
intimate kissing with multiple partners (3.7, 1.7 to 8.1), being a
university student (3.4, 1.2 to 10) and preterm birth (3.7, 1.0 to
13.5). Religious observance (0.09, 0.02 to 0.6) and
meningococcal vaccination (0.12, 0.04 to 0.4) were associated
with protection.
Conclusions: Activities and events increasing risk for
meningococcal disease in adolescence are different from in
childhood. Students are at higher risk. Altering personal
behaviours could moderate the risk. However, the development
of further effective meningococcal vaccines remains a key
public health priority
A novel protocol for the one-pot borylation/Suzuki reaction provides easy access to hinge-binding groups for kinase inhibitors
The one-pot borylation/Suzuki reaction is a very efficient means of accessing cross-coupling products of two aryl-halide partners that generally requires the use of specific catalysts or ligands and/or relatively long reaction times. This new microwave-assisted method provides a quick one-pot borylation/Suzuki reaction protocol that we applied to the synthesis of various bi- or poly-aryl scaffolds, including a variety of aryl and heteroaryl ring systems and the core frameworks of kinase inhibitors vemurafenib and GDC-0879
Tropical to extratropical : marine environmental changes associated with Superstorm Sandy prior to its landfall
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 41 (2014): 8935–8943, doi:10.1002/2014GL061357.Superstorm Sandy was a massive storm that impacted the U.S. East Coast on 22–31 October 2012, generating large waves, record storm surges, and major damage. The Coupled Ocean-Atmosphere-Wave-Sediment Transport modeling system was applied to hindcast this storm. Sensitivity experiments with increasing complexity of air-sea-wave coupling were used to depict characteristics of this immense storm as it underwent tropical to extratropical transition. Regardless of coupling complexity, model-simulated tracks were all similar to the observations, suggesting the storm track was largely determined by large-scale synoptic atmospheric circulation, rather than by local processes resolved through model coupling. Analyses of the sea surface temperature, ocean heat content, and upper atmospheric shear parameters showed that as a result of the extratropical transition and despite the storm encountering much cooler shelf water, its intensity and strength were not significantly impacted. Ocean coupling was not as important as originally thought for Sandy.Research support provided by USGS Coastal Process Project, NOAA grant NA11NOS0120033, and NASA grant NNX13AD80G is much appreciated.2015-06-1
Nonadiabatic effects in the dynamics of atoms confined in a cylindric time-orbiting-potential magnetic trap
In a time-orbiting-potential magnetic trap the neutral atoms are confined by
means of an inhomogeneous magnetic field superimposed to an uniform rotating
one. We perform an analytic study of the atomic motion by taking into account
the nonadiabatic effects arising from the spin dynamics about the local
magnetic field. Geometric-like magnetic-fields determined by the Berry's phase
appear within the quantum description. The application of a variational
procedure on the original quantum equation leads to a set of dynamical
evolution equations for the quantum average value of the position operator and
of the spin variables. Within this approximation we derive the
quantum-mechanical ground state configuration matching the classical adiabatic
solution and perform some numerical simulations.Comment: 12 pages, 4 figure
Anwendung des Penetrationsmodells von Chlorid bei der Beurteilung des Zustands beim BrĂĽckenmanagement
Although there is a large number of established Bridge Management Systems worldwide, there seems to be a lack of those that utilise the knowledge on material properties and environmental loading. Hence, as a supplement to current practice, the paper examines the use of the chloride ingress model, supported by the International Federation for Structural Concrete, for preliminary assessment in bridge management. The focus is set on analysing application of the model in realistic situations on existing concrete bridges for which the information on material and environmental properties is lacking.Iako se danas diljem svijeta primjenjuju brojni sustavi za gospodarenje mostovima, čini se da ipak nema dovoljno sustava u kojima bi se koristilo znanje o svojstvima materijala i opterećenju iz okoliša. U ovom se radu, kao doprinos sadašnjoj praksi, analizira primjena modela prodora klorida, što podržava Međunarodni savez za betonske konstrukcije, a koristi se za preliminarno ocjenjivanje u okviru gospodarenja mostovima. Prije svega, analizira se primjena modela u realnim situacijama za ocjenu postojećih betonskih mostova za koje ne postoje podaci o materijalima i svojstvima okoliša.Obwohl heute weltweit zahlreiche Brückenmanagementsysteme angewendet werden, scheint es jedoch nicht ausreichend Systeme zu geben, in denen die Kenntnisse über die Materialeigenschaften und die Umweltbelastung angewendet werden. In dieser Abhandlung wird als Beitrag zur aktuellen Praxis die Anwendung des Penetrationsmodells von Chlorid analysiert, was vom Internationalen Verband für Betonkonstruktionen unterstützt wird, und wird als vorläufige Beurteilung im Rahmen des Brückenmanagements angewendet. Zunächst wird die Anwendung des Modells unter realen Bedingungen für die Beurteilung der bestehenden Betonbrücken analysiert, zu denen Daten über die Materialien und die Umwelteigenschaften vorliegen.The authors would like to show their gratitude for the support received during the project “Life – Cycle Assessment for Railway Structures”, funded by the ÖBB-Infrastruktur Bau AG, Vienna. For the support in the analysis of existing standards, authors would like to express special appreciation to Smart Minerals GmbH
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