142 research outputs found
On Charged Black Holes in Anti-de Sitter Space
We study the region inside the event horizon of charged black holes in five
dimensional asymptotically anti-de Sitter space, using as a probe two-sided
correlators which are dominated by spacelike geodesics penetrating the horizon.
The spacetimes we investigate include the Reissner-Nordstrom black hole and
perturbations thereof. The perturbed spacetimes can be found exactly, enabling
us to perform a local scan of the region between the inner and outer horizons.
Surprisingly, the two-sided correlators we calculate seem to be geometrically
protected from the instability of the inner horizon.Comment: 1+37 pages, 20 ps and eps figures, LaTeX. References added and
changes made to section
Transformation of in-plane in at fixed oxygen content
This paper reveals the origin of variation in the magnitude and temperature
dependence of the normal state resistivity frequently observed in different
YBCO single crystal or thin film samples with the same . We investigated
temperature dependence of resistivity in thin films
with 7- and 6.90, which were subjected to annealing in argon at
400-420 K (). Before annealing these films exhibited a non-linear
, with a flattening below 230 K, similar to and
observed in untwinned and twinned YBCO crystals, respectively.
For all films the annealing causes an increase of resistivity and a
transformation of from a non-linear dependence towards a more
linear one (less flattening). In films with 7- the increase of
resistivity is also associated with an increase in . We proposed the
model that provides an explanation of these phenomena in terms of thermally
activated redistribution of residual O(5) oxygens in the chain-layer of YBCO.
Good agreement between the experimental data for , where t is
the annealing time, and numerical calculations was obtained.Comment: 8 pages, 9 figures, submitted to PR
Dark Energy from structure: a status report
The effective evolution of an inhomogeneous universe model in any theory of
gravitation may be described in terms of spatially averaged variables. In
Einstein's theory, restricting attention to scalar variables, this evolution
can be modeled by solutions of a set of Friedmann equations for an effective
volume scale factor, with matter and backreaction source terms. The latter can
be represented by an effective scalar field (`morphon field') modeling Dark
Energy.
The present work provides an overview over the Dark Energy debate in
connection with the impact of inhomogeneities, and formulates strategies for a
comprehensive quantitative evaluation of backreaction effects both in
theoretical and observational cosmology. We recall the basic steps of a
description of backreaction effects in relativistic cosmology that lead to
refurnishing the standard cosmological equations, but also lay down a number of
challenges and unresolved issues in connection with their observational
interpretation.
The present status of this subject is intermediate: we have a good
qualitative understanding of backreaction effects pointing to a global
instability of the standard model of cosmology; exact solutions and
perturbative results modeling this instability lie in the right sector to
explain Dark Energy from inhomogeneities. It is fair to say that, even if
backreaction effects turn out to be less important than anticipated by some
researchers, the concordance high-precision cosmology, the architecture of
current N-body simulations, as well as standard perturbative approaches may all
fall short in correctly describing the Late Universe.Comment: Invited Review for a special Gen. Rel. Grav. issue on Dark Energy, 59
pages, 2 figures; matches published versio
Spinor model of a perfect fluid and their applications in Bianchi type-I and FRW models
Different characteristic of matter influencing the evolution of the Universe
has been simulated by means of a nonlinear spinor field. Exploiting the spinor
description of perfect fluid and dark energy evolution of the Universe given by
an anisotropic Bianchi type-I (BI) or isotropic Friedmann-Robertson-Walker
(FRW) one has been studied.Comment: 10 pages, 8 Figure
Malnutrition as assessed by nutritional risk index is associated with worse outcome in patients admitted with acute decompensated heart failure: an ACAP-HF data analysis
Malnutrition is common at hospital admission and tends to worsen during hospitalization. This controlled population study aimed to determine if serum albumin or moderate and severe nutritional depletion by Nutritional Risk Index (NRI) at hospital admission are associated with increased length of hospital stay (LOS) in patients admitted with acute decompensated heart failure (ADHF). Serum albumin levels and lymphocyte counts were retrospectively determined at hospital admission in 1740 consecutive patients admitted with primary and secondary diagnosis of ADHF. The Nutrition Risk Score (NRI) developed originally in AIDS and cancer populations was derived from the serum albumin concentration and the ratio of actual to usual weight, as follows: NRI = (1.519 × serum albumin, g/dL) + {41.7 × present weight (kg)/ideal body weight(kg)}. Patients were classified into four groups as no, mild, moderate or severe risk by NRI. Multiple logistic regressions were used to determine the association between nutritional risk category and LOS
Conformal and Affine Hamiltonian Dynamics of General Relativity
The Hamiltonian approach to the General Relativity is formulated as a joint
nonlinear realization of conformal and affine symmetries by means of the Dirac
scalar dilaton and the Maurer-Cartan forms. The dominance of the Casimir vacuum
energy of physical fields provides a good description of the type Ia supernova
luminosity distance--redshift relation. Introducing the uncertainty principle
at the Planck's epoch within our model, we obtain the hierarchy of the Universe
energy scales, which is supported by the observational data. We found that the
invariance of the Maurer-Cartan forms with respect to the general coordinate
transformation yields a single-component strong gravitational waves. The
Hamiltonian dynamics of the model describes the effect of an intensive vacuum
creation of gravitons and the minimal coupling scalar (Higgs) bosons in the
Early Universe.Comment: 37 pages, version submitted to Gen. Rel. Gra
The statistics of string/M theory vacua
We discuss systematic approaches to the classification of string/M theory
vacua, and physical questions this might help us resolve. To this end, we
initiate the study of ensembles of effective Lagrangians, which can be used to
precisely study the predictive power of string theory, and in simple examples
can lead to universality results. Using these ideas, we outline an approach to
estimating the number of vacua of string/M theory which can realize the
Standard Model.Comment: harvmac, 72pp (v4: fixed error in discussion of quiver ensembles
“God is Hidden in the Earthly Kingdom:” The Lutheran Two-Kingdoms Theory as Foundation of Scandavanian Secularity
Martin Luther’s signature “two kingdoms” teaching of the sixteenth century was an early and innovative theory of secularization that lies at the heart of historical Scandinavian culture. Defying the organic medieval models of Western Christendom, Luther separated the heavenly and earthly kingdoms, the saint and the sinner, faith and reason, church and the state, Gospel and the Law, as well as the spiritual and secular uses of law, government and authority. Though God is separated from day-to-day life, Luther wrote, God is still hidden in the earthly kingdom” and can be seen through various “masks,” “mists,” and “mimes.” Though the visible church is separated from the state and other institutions, religion remains pervasive in the common callings of every person to be God’s prophet, priest and king in every vocation and location of life. Luther’s two kingdoms theory is a complicated and controversial part of this thinking, but it is worth re-exploring today as pluralistic Scandinavia faces strong new pressures of both sacralization and secularization and seeks to discern anew “the hidden sacraliity of the secular.
- …