5,106 research outputs found
Asymptotic Level Spacing of the Laguerre Ensemble: A Coulomb Fluid Approach
We determine the asymptotic level spacing distribution for the Laguerre
Ensemble in a single scaled interval, , containing no levels,
E_{\bt}(0,s), via Dyson's Coulomb Fluid approach. For the
Unitary-Laguerre Ensemble, we recover the exact spacing distribution found by
both Edelman and Forrester, while for , the leading terms of
, found by Tracy and Widom, are reproduced without the use of the
Bessel kernel and the associated Painlev\'e transcendent. In the same
approximation, the next leading term, due to a ``finite temperature''
perturbation (\bt\neq 2), is found.Comment: 10pp, LaTe
Eigenvalue correlations on Hyperelliptic Riemann surfaces
In this note we compute the functional derivative of the induced charge
density, on a thin conductor, consisting of the union of g+1 disjoint
intervals, with respect to an external
potential. In the context of random matrix theory this object gives the
eigenvalue fluctuations of Hermitian random matrix ensembles where the
eigenvalue density is supported on J.Comment: latex 2e, seven pages, one figure. To appear in Journal of Physics
A Framework for the Landscape
It seems likely that string theory has a landscape of vacua that includes
very many metastable de Sitter spaces. However, as emphasized by Banks, Dine
and Gorbatov, no current framework exists for examining these metastable vacua
in string theory. In this paper we attempt to correct this situation by
introducing an eternally inflating background in which the entire collection of
accelerating cosmologies is present as intermediate states. The background is a
classical solution which consists of a bubble of zero cosmological constant
inside de Sitter space, separated by a domain wall. At early and late times the
flat space region becomes infinitely big, so an S-matrix can be defined.
Quantum mechanically, the system can tunnel to an intermediate state which is
pure de Sitter space. We present evidence that a string theory S-matrix makes
sense in this background and contains metastable de Sitter space as an
intermediate state.Comment: 29+13 pages, 25 figures; v2: minor corrections, references adde
Testing statistical bounds on entanglement using quantum chaos
Previous results indicate that while chaos can lead to substantial entropy
production, thereby maximizing dynamical entanglement, this still falls short
of maximality. Random Matrix Theory (RMT) modeling of composite quantum
systems, investigated recently, entails an universal distribution of the
eigenvalues of the reduced density matrices. We demonstrate that these
distributions are realized in quantized chaotic systems by using a model of two
coupled and kicked tops. We derive an explicit statistical universal bound on
entanglement, that is also valid for the case of unequal dimensionality of the
Hilbert spaces involved, and show that this describes well the bounds observed
using composite quantized chaotic systems such as coupled tops.Comment: 5 pages, 3 figures, to appear in PRL. New title. Revised abstract and
some changes in the body of the pape
High Resolution CO and H2 Molecular Line Imaging of a Cometary Globule in the Helix Nebula
We report high resolution imaging of a prominent cometary globule in the
Helix nebula in the CO J=1-0 (2.6 mm) and H2 v=1-0 S(1) (2.12 micron) lines.
The observations confirm that globules consist of dense condensations of
molecular gas embedded in the ionized nebula. The head of the globule is seen
as a peak in the CO emission with an extremely narrow line width (0.5 km/s) and
is outlined by a limb-brightened surface of H2 emission facing the central star
and lying within the photo-ionized halo. The emission from both molecular
species extends into the tail region. The presence of this extended molecular
emission provides new constraints on the structure of the tails, and on the
origin and evolution of the globules.Comment: 12 pages, 3 figures. To appear in The Astrophysical Journal Letter
Fluctuation properties of strength functions associated with giant resonances
We performed fluctuation analysis by means of the local scaling dimension for
the strength function of the isoscalar (IS) and the isovector (IV) giant
quadrupole resonances (GQR) in Ca, where the strength functions are
obtained by the shell model calculation within up to the 2p2h configurations.
It is found that at small energy scale, fluctuation of the strength function
almost obeys the Gaussian orthogonal ensemble (GOE) random matrix theory limit.
On the other hand, we found a deviation from the GOE limit at the intermediate
energy scale about 1.7MeV for the IS and at 0.9MeV for the IV. The results
imply that different types of fluctuations coexist at different energy scales.
Detailed analysis strongly suggests that GOE fluctuation at small energy scale
is due to the complicated nature of 2p2h states and that fluctuation at the
intermediate energy scale is associated with the spreading width of the
Tamm-Dancoff 1p1h states.Comment: 14 pages including 13figure
KINETIC AND KINEMATIC CHANGES ASSOCIATED WITH ALTERING HEEL HEIGHT DURING CRICKET MEDIUM-FAST BOWLING
INTRODUCTION: During a cricket bowling delivery, the major impact with the pitch occurs at front foot impact (FFI), generating forces approximately 5.7 times body weight (BW) in the vertical plane and 3.5 BW in the horizontal plane. (Hurrion et al. 2000). Although cricket footwear has been acknowledged by researchers as worthy of investigation, to date there is no research published to inform of the potential for injury prevention. Bartold (2005) found when investigating midsole height in football footwear that a graduated rise of 1cm altered lower limb muscle activity and reduced peak pressures under the foot during treadmill running. Associated altered kinematics reported by Bartold (2005) is in accordance with reports by Eslami et al. (2005) who found a 0.4cm posterior wedge can be utilised to alter the angular variability of the subtalar joint and its proximal joints and segments in their respective planes of movement during single limb stance
IN-SHOE PLANTAR PRESSURE MEASUREMENTS DURING GOLF SWING PERFORMANCE WEARING METAL AND ALTERNATIVE SPIKED GOLF SHOES
In-shoe plantar pressures were assessed when two different golf shoes were worn. One shoe design incorporated 7 metal spikes and the other 7 alternative spikes. Eighteen male golfers (mean handicap ±SD: 12.4 ± 7.8) played 5 shots with a 7 iron while wearing each shoe on a natural grass surface. Pressures in 9 standardised foot regions were analysed to yield maximal, average and ball impact values. The greatest pressures were at the lateral regions of the front-foot from the point of ball impact when wearing the metal spike shoes. Significantly greater maximal pressures occurred when wearing the metal spike shoe (front foot: lateral 114 kPa; back foot: lateral heel 40 kPa, medial central 63 kPa;
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