582 research outputs found
Static Cosmological Solutions of the Einstein-Yang-Mills-Higgs Equations
Numerical evidence is presented for the existence of a new family of static,
globally regular `cosmological' solutions of the spherically symmetric
Einstein-Yang-Mills-Higgs equations. These solutions are characterized by two
natural numbers (, ), the number of nodes of the Yang-Mills
and Higgs field respectively. The corresponding spacetimes are static with
spatially compact sections with 3-sphere topology.Comment: 7 pages, 5 figures, LaTe
Non-Abelian black holes: The inside story
Recent progress in understanding of the internal structure of non-Abelian
black holes is discussed.
Talk given at the international Workshop on The Internal Structure of Black
Holes and Spacetime Singularities, Haifa, Israel, June 29 -- July 3, 1997.Comment: 23 pages, latex, contains 12 eps files combined in 8 figure
Self-similar solutions of semilinear wave equations with a focusing nonlinearity
We prove that in three space dimensions a nonlinear wave equation
with being an odd integer has a countable
family of regular spherically symmetric self-similar solutions.Comment: 12 pages, 3 figures, minor corrections to match the published versio
Mass inflation inside non-Abelian black holes
The interior geometry of static, spherically symmetric black holes of the Einstein-Yang-Mills-Higgs theory is analyzed. It is found that in contrast to the Abelian case generically no inner (Cauchy) horizon is formed inside non-Abelian black holes. Instead the solutions come close to a Cauchy horizon but then undergo an enormous growth of the mass function, a phenomenon which can be termed `mass inflation' in analogy to what is observed for perturbations of the Reissner-Nordstr{Ăž}m solution. A significant difference between the theories with and without a Higgs field is observed. Without a Higgs field the YM field induces repeated cycles of mass inflation -- taking the form of violent `explosions' -- interrupted by quiescent periods and subsequent approaches to an almost Cauchy horizon. With the Higgs field no such cycles occur. Besides the generic solutions there are non-generic families with a Schwarzschild, Reissner-Nordstr{Ăž}m and a pseudo Reissner-Nordstr{Ăž}m type singularity at $r=0
Universality of global dynamics for the cubic wave equation
We consider the initial value problem for the spherically symmetric, focusing
cubic wave equation in three spatial dimensions. We give numerical and
analytical evidence for the existence of a universal attractor which
encompasses both global and blowup solutions. As a byproduct we get an explicit
description of the critical behavior at the threshold of blowup.Comment: 13 pages, 15 figures. Uses IOP-style. Updated to conform with
published versio
The effect of post-meal walking on 24-hour central blood pressure in young women with and without excess adiposity
Post-meal walking (PMW) performed after breakfast, lunch, and dinner has been demonstrated to reduce blood glucose. However, no studies have examined the potential additive benefits of post-meal walking exercise on daytime central blood pressure (BP) in young women. METHODS: Thirteen physically inactive, non-hypertensive women (Age: 20±1 years; percent body fat: 28.2±13%) completed the study during the early follicular or placebo phase of their contraceptive cycle. Participants completed a control day (CON; no exercise/excess physical activity) and PMW day (3 bouts x 15 minutes of brisk walking) over five days in random order. Daytime ambulatory BP and accelerometry data (to estimate METs) were measured and compared. RESULTS: PMW increased metabolic expenditure (PMW= 35.8±1.44 vs. CON= 33.7±0.94 METs, p0.05 for all). CONCLUSION: PMW does not lead to reductions in central BP in young, physically inactive women
Harrison transformation of hyperelliptic solutions and charged dust disks
We use a Harrison transformation on solutions to the stationary axisymmetric
Einstein equations to generate solutions of the Einstein-Maxwell equations. The
case of hyperelliptic solutions to the Ernst equation is studied in detail.
Analytic expressions for the metric and the multipole moments are obtained. As
an example we consider the transformation of a family of counter-rotating dust
disks. The resulting solutions can be interpreted as disks with currents and
matter with a purely azimuthal pressure or as two streams of freely moving
charged particles. We discuss interesting limiting cases as the extreme limit
where the charge becomes identical to the mass, and the ultrarelativistic limit
where the central redshift diverges.Comment: 20 pages, 9 figure
SK2 channels are required for function and long-term survival of efferent synapses on mammalian outer hair cells
Cochlear hair cells use SK2 currents to shape responses to cholinergic efferent feedback from the brain. Using SK2-/- mice, we demonstrate that, in addition to their previously defined role in modulating hair cell membrane potentials, SK2 channels are necessary for long-term survival of olivocochlear fibers and synapses. Loss of the SK2 gene also results in loss of electrically driven olivocochlear effects in vivo, and down regulation of ryanodine receptors involved in calcium-induced calcium release, the main inducer of nAChR evoked SK2 activity. Generation of double-null mice lacking both the α10 nAChR gene, loss of which results in hypertrophied olivocochlear terminals, and the SK2 gene, recapitulates the SK2-/- synaptic phenotype and gene expression, and also leads to down regulation of α9 nAChR gene expression. The data suggest a hierarchy of activity necessary to maintain early olivocochlear synapses at their targets, with SK2 serving an epistatic, upstream, role to the nAChRs.Fil: Murthy, Vidya. Tufts University; Estados UnidosFil: Maison, StĂ©phane F.. Massachusetts Eye and Ear Infirmary; Estados Unidos. Harvard Medical School; Estados UnidosFil: Taranda, Julian. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; Argentina. Tufts University; Estados UnidosFil: Haque, Nadeem. University of Notre Dame; Estados UnidosFil: Bond, Chris T.. Oregon Health Sciences University; Estados UnidosFil: Elgoyhen, Ana Belen. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Adelman, John P.. Oregon Health Sciences University; Estados UnidosFil: Liberman, M. Charles. Massachusetts Eye and Ear Infirmary; Estados Unidos. Harvard Medical School; Estados UnidosFil: Vetter, Douglas E.. Tufts University; Estados Unido
Cylindrically symmetric solitons in Einstein-Yang-Mills theory
Recently new Einstein-Yang-Mills (EYM) soliton solutions were presented which
describe superconducting strings with Kasner asymptotic (hep-th/0610183). Here
we study the static cylindrically symmetric SU(2) EYM system in more detail.
The ansatz for the gauge field corresponds to superposition of the azimuthal
and the longitudinal components of the color magnetic field. We
derive sum rules relating data on the symmetry axis to asymptotic data and show
that generic asymptotic structure of regular solutions is Kasner. Solutions
starting with vacuum data on the axis generically are divergent. Regular
solutions correspond to some bifurcation manifold in the space of parameters
which has the low-energy limiting point corresponding to string solutions in
flat space (with the divergent total energy) and the high-curvature point where
gravity is crucial. Some analytical results are presented for the low energy
limit, and numerical bifurcation curves are constructed in the gravitating
case. Depending on the parameters, the solution looks like a straight string or
a pair of straight and circular strings. The existence of such non-linear
superposition of two strings becomes possible due to self-interaction terms in
the Yang-Mills action which suppress contribution of the circular string near
the polar axis.Comment: 21 pages, 11 figure
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