3,561,313 research outputs found
Kinematic variations due to changes in pace during men's and women's 5 km road running
The purpose of this study was to investigate variations in kinematic parameters in men's and women's 5 km road racing. Athletes often vary their pace and changes particularly tend to occur towards the end of a race due to fatigue and sprint finishes. Twenty competitive distance runners (10 male, 10 female) were videoed as they completed the English National 5 km championships. Three-dimensional kinematic data were analysed using motion analysis software (SIMI, Munich). Data were recorded at 950 m, 2,400 m and 3,850 m. Repeated measures ANOVA showed significant decreases in speed due to reduced step length and cadence in both men and women. These decreases predominantly occurred between the first two measurement points. The hip, knee, ankle and shoulder angles at both initial contact and toe-off did not change significantly, but there were significant reductions in the elbow angle for both men (at initial contact) and women (at toe-off)
Electric potential variations associated with yearly lake level variations
Electric potential variations have been recorded from November 1995 to February 1996 and continuously since October 1996 at 14 measurement points on a one km wide ridge separating two lakes in the French Alps. The levels of the lakes vary by several tens of meters on a yearly cycle, inducing stress variations and fluid percolation. At one point, unambiguous variations as large as 120 mV are observed over a year, linearly correlated with the levels of the lakes with a magnitude of 2 mV per meter of water level change. This particular measurement point lies at the edge of a SP anomaly, which supports the presence of a localized zone of ground water flow forced by the lake level, suggesting an electrokinetic mechanism. The observed correlation implies a ζâpotential of the order of â8 mV for a 60 Ωm electrolyte, in agreement with laboratory measurements
Variations on Prequantization
We extend known prequantization procedures for Poisson and presymplectic
manifolds by defining the prequantization of a Dirac manifold P as a principal
U(1)-bundle Q with a compatible Dirac-Jacobi structure. We study the action of
Poisson algebras of admissible functions on P on various spaces of locally
(with respect to P) defined functions on Q, via hamiltonian vector fields.
Finally, guided by examples arising in complex analysis and contact geometry,
we propose an extension of the notion of prequantization in which the action of
U(1) on Q is permitted to have some fixed points.Comment: 33 pages; contribution to the proceedings of the conference Poisson
200
The Goldstini Variations
We study the 'goldstini' scenario of Cheung, Nomura, and Thaler, in which
multiple independent supersymmetry (SUSY) breaking sectors lead to multiple
would-be goldstinos, changing collider and cosmological phenomenology. In
supergravity, potentially large corrections to the previous prediction of twice
the gravitino mass for goldstini masses can arise when their scalar partners
are stabilized far from the origin. Considerations arising from the complexity
of realistic string compactifications indicate that many of the independent
SUSY-breaking sectors should be conformally sequestered or situated in warped
Randall-Sundrum-like throats, further changing the predicted goldstini masses.
If the sequestered hidden sector is a metastable SUSY-breaking sector of the
Intriligator-Seiberg-Shih (ISS) type then multiple goldstini can originate from
within a single sector, along with many supplementary 'modulini', all with
masses of order twice the gravitino mass. These fields can couple to the
Supersymmetric Standard Model (SSM) via the 'Goldstino Portal'. Collider
signatures involving SSM sparticle decays can provide strong evidence for
warped-or-conformally-sequestered sectors, and of the ISS mechanism of SUSY
breaking. Along with axions and photini, the Goldstino Portal gives another
potential window to the hidden sectors of string theory.Comment: 30 pages, 3 figures; v2 minor changes, references adde
Variations on leptogenesis
We study variations of the standard leptogenesis scenario that can arise if
an additional mass scale related to the breaking of some new symmetry (as for
example a flavor or the B-L symmetry) is present below the mass of
the lightest right-handed Majorana neutrino. Our scheme is inspired by U(1)
models of flavor \`a la Froggatt-Nielsen, and involves new vectorlike heavy
fields . We show that depending on the specific hierarchy between
and the mass scale of the fields , qualitatively different realizations of
leptogenesis can emerge. We compute the CP asymmetries in decays in all
the relevant cases, and we conclude that in most situations leptogenesis could
be viable at scales much lower than in the standard scenario.Comment: One error corrected, several references added, results unchanged. 17
page
Dark matter variations
In this short presentation, we remind of significant unknowns regarding the
distribution of Dark Matter in our immediate neighborhood, and review the
recent improvements in the obtained limits on its abundance.Comment: 6 pages 1 figure uses \psfrag Corfu Summer Institute Proceeding
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