5,585 research outputs found
Laplacian modes as a filter
We compute low-lying eigenmodes of the gauge covariant Laplace operator on
the lattice at finite temperature. For classical configurations we show how the
lowest mode localizes the monopole constituents inside calorons and that it
hops upon changing the boundary conditions. The latter effect we observe for
thermalized backgrounds, too, analogously to what is known for fermion zero
modes.
We propose a new filter for equilibrium configurations which provides link
variables as a truncated sum involving the Laplacian modes. This method not
only reproduces classical structures, but also preserves the confining
potential, even when only a few modes are used.Comment: talk presented by FB at the Workshop on Computational Hadron Physics,
Nikosia (Cyprus), Sept. 14-17, 2005; compared to hep-lat/0509020 and
hep-lat/0509087 we have added the following points: 1. the kinetic term
(square of the covariant derivative) as an analyzing observable, 2. the
correlation of filtered link variables to the original ones, 3. the filtered
string tension from modes with shifted ordinal number; 8 pages, 8 figures,
uses espcrc2.st
Gravitational Geons Revisited
A careful analysis of the gravitational geon solution found by Brill and
Hartle is made. The gravitational wave expansion they used is shown to be
consistent and to result in a gauge invariant wave equation. It also results in
a gauge invariant effective stress-energy tensor for the gravitational waves
provided that a generalized definition of a gauge transformation is used. To
leading order this gauge transformation is the same as the usual one for
gravitational waves. It is shown that the geon solution is a self-consistent
solution to Einstein's equations and that, to leading order, the equations
describing the geometry of the gravitational geon are identical to those
derived by Wheeler for the electromagnetic geon. An appendix provides an
existence proof for geon solutions to these equations.Comment: 18 pages, ReVTeX. To appear in Physical Review D. Significant changes
include more details in the derivations of certain key equations and the
addition of an appendix containing a proof of the existence of a geon
solution to the equations derived by Wheeler. Also a reference has been added
and various minor changes have been mad
Flight Measurements of the Wing-dropping Tendency of a Straight-wing Jet Airplane at High Subsonic Mach Numbers
Heteronuclear Decoupling by Multiple Rotating Frame Technique
The paper describes the multiple rotating frame technique for designing
modulated rf-fields, that perform broadband heteronuclear decoupling in
solution NMR spectroscopy. The decoupling is understood by performing a
sequence of coordinate transformations, each of which demodulates a component
of the Rf-field to a static component, that progressively averages the chemical
shift and dipolar interaction. We show that by increasing the number of
modulations in the decoupling field, the ratio of dispersion in the chemical
shift to the strength of the rf-field is successively reduced in progressive
frames. The known decoupling methods like continuous wave decoupling, TPPM etc,
are special cases of this method and their performance improves by adding
additional modulations in the decoupling field. The technique is also expected
to find use in designing decoupling pulse sequences in Solid State NMR
spectroscopy and design of various excitation, inversion and mixing sequences.Comment: 18 pages , 5 figure
Systematic Approach to Using Isentropic Stress Reverberation Techniques in Approximating Equation of State
Isentropic stress reverberations are used to obtain multiple Hugoniot states from a single plate impact experiment using a layered plate geometry, where a low impedance inner layer is embedded within a high impedance bulk structure. The mathematical framework used in this technique uses the classical Rankine-Hugoniot equations in the method of impedance matching, where the bulk material is required to have a known Hugoniot. Factors including the wave velocities in the materials, input pulse duration, inner layer thickness, and diameter of the test samples affect the number of states that can be generated from a single experiment. Experiments using 6061 aluminum and polycarbonate, respectively, as the bulk material and inner layer, accurately generated six Hugoniot states for the polycarbonate. Experiments using A572 grade 50 structural steel as the bulk material accurately generated ten Hugoniot states for the polycarbonate. For each experiment, the method can be used to generate a Hugoniot equation defining the material response of the inner layer within the domain encompassed by the specific test. The method is also confined to the low to moderate stress regions, within which Hugoniot and isentropic representations of the material are almost identical
Temporal expression pattern of genes during the period of sex differentiation in human embryonic gonads
Abstract The precise timing and sequence of changes in expression of key genes and proteins during human sex-differentiation and onset of steroidogenesis was evaluated by whole-genome expression in 67 first trimester human embryonic and fetal ovaries and testis and confirmed by qPCR and immunohistochemistry (IHC). SRY/SOX9 expression initiated in testis around day 40 pc, followed by initiation of AMH and steroidogenic genes required for androgen production at day 53 pc. In ovaries, gene expression of RSPO1, LIN28, FOXL2, WNT2B, and ETV5, were significantly higher than in testis, whereas GLI1 was significantly higher in testis than ovaries. Gene expression was confirmed by IHC for GAGE, SOX9, AMH, CYP17A1, LIN28, WNT2B, ETV5 and GLI1. Gene expression was not associated with the maternal smoking habits. Collectively, a precise temporal determination of changes in expression of key genes involved in human sex-differentiation is defined, with identification of new genes of potential importance
Cost–benefit analysis of controlling rabies: placing economics at the heart of rabies control to focus political will
Rabies is an economically important zoonosis. This paper describes the extent of the economic impacts of the disease and some of the types of economic analyses used to understand those impacts, as well as the trade-offs between efforts to manage rabies and efforts to eliminate it. In many cases, the elimination of rabies proves more cost-effective over time than the continual administration of postexposure prophylaxis, animal testing and animal vaccination. Economic analyses are used to inform and drive policy decisions and focus political will, placing economics at the heart of rabies control
Genetic partitioning of interleukin-6 signalling in mice dissociates Stat3 from Smad3-mediated lung fibrosis
Idiopathic pulmonary fibrosis (IPF) is a fatal disease that is unresponsive to current therapies and characterized by excessive collagen deposition and subsequent fibrosis. While inflammatory cytokines, including interleukin (IL)-6, are elevated in IPF, the molecular mechanisms that underlie this disease are incompletely understood, although the development of fibrosis is believed to depend on canonical transforming growth factor (TGF)-β signalling. We examined bleomycin-induced inflammation and fibrosis in mice carrying a mutation in the shared IL-6 family receptor gp130. Using genetic complementation, we directly correlate the extent of IL-6-mediated, excessive Stat3 activity with inflammatory infiltrates in the lung and the severity of fibrosis in corresponding gp130757F mice. The extent of fibrosis was attenuated in B lymphocyte-deficient gp130757F;µMT−/− compound mutant mice, but fibrosis still occurred in their Smad3−/− counterparts consistent with the capacity of excessive Stat3 activity to induce collagen 1α1 gene transcription independently of canonical TGF-β/Smad3 signalling. These findings are of therapeutic relevance, since we confirmed abundant STAT3 activation in fibrotic lungs from IPF patients and showed that genetic reduction of Stat3 protected mice from bleomycin-induced lung fibrosis
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