95,954 research outputs found
Approximating -foliations
We extend the Eliashberg-Thurston theorem on approximations of taut oriented
-foliations of 3-manifolds by both positive and negative contact
structures to a large class of taut oriented -foliations, where by
foliation, we mean a foliation with continuous tangent plane field.
These -foliations can therefore be approximated by weakly
symplectically fillable, universally tight, contact structures. This allows
applications of -foliation theory to contact topology and Floer theory to
be generalized and extended to constructions of -foliations.Comment: 52 pages, 5 figures. Final version with updated references,
corrections and terminolog
Exposing the dressed quark's mass
This snapshot of recent progress in hadron physics made in connection with
QCD's Dyson-Schwinger equations includes: a perspective on confinement and
dynamical chiral symmetry breaking (DCSB); a pre'cis on the physics of
in-hadron condensates; results on the hadron spectrum, including
dressed-quark-core masses for the nucleon and Delta, their first radial
excitations, and the parity-partners of these states; an illustration of the
impact of DCSB on the electromagnetic pion form factor, thereby exemplifying
how data can be used to chart the momentum-dependence of the dressed-quark mass
function; and a prediction that F_1^{p,d}/F_1^{p,u} passes through zero at
Q^2\approx 5m_N^2 owing to the presence of nonpointlike scalar and axial-vector
diquark correlations in the nucleon.Comment: 10 pages, 4 figures, 2 tables. Contribution to the Proceedings of the
4th Workshop on Exclusive Reactions at High Momentum Transfer, Thomas
Jefferson National Accelerator Facility Newport News, Virginia, 18-21 May
201
Motion in a Bose condensate: IX. Crow instability of antiparallel vortex pairs
The Gross-Pitaevskii (GP) equation admits a two-dimensional solitary wave
solution representing two mutually self-propelled, anti-parallel straight line
vortices. The complete sequence of such solitary wave solutions has been
computed by Jones and Roberts (J. Phys. A, 15, 2599, 1982). These solutions are
unstable with respect to three-dimensional perturbations (the Crow
instability). The most unstable mode has a wavelength along the direction of
the vortices of the same order as their separation. The growth rate associated
with this mode is evaluated here, and it is found to increase very rapidly with
decreasing separation. It is shown, through numerical integrations of the GP
equation that, as the perturbations grow to finite amplitude, the lines
reconnect to produce a sequence of almost circular vortex rings.Comment: Submitted to J. Phys. A: Math. Gen.; Corrected reference
Going the same 'weigh': spousal correlations in obesity in the UK
The obesity epidemic has received widespread media and research attention. However, the social phenomenon of obesity is still not well understood. Data from the 2004 and 2006 waves of the British Household Panel Survey (BHPS) show positive and significant correlations in spousal body mass index (BMI). This paper explores three mechanisms of shared individual characteristics, social influence and shared environment to explain this correlation. A number of econometric specifications are used to investigate the role of observed individual characteristics, own health, spouse health, social influence, contextual effects and unobserved individual effects on the influence of these three hypotheses on the correlation in spousal BMI. Results indicate that social influence and shared individual characteristics, which may arise through assortative matching, both contribute to correlation in spousal BMI
An approach to market analysis for lighter than air transportation of freight
An approach is presented to marketing analysis for lighter than air vehicles in a commercial freight market. After a discussion of key characteristics of supply and demand factors, a three-phase approach to marketing analysis is described. The existing transportation systems are quantitatively defined and possible roles for lighter than air vehicles within this framework are postulated. The marketing analysis views the situation from the perspective of both the shipper and the carrier. A demand for freight service is assumed and the resulting supply characteristics are determined. Then, these supply characteristics are used to establish the demand for competing modes. The process is then iterated to arrive at the market solution
Cardiovascular Effects of Vibration Semiannual Report, 1 Aug. 1965 - 28 Feb. 1966
Vibration induced cardiovascular changes in anesthetized dog
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