51 research outputs found
Canonical Quantization of the BTZ Black Hole using Noether Symmetries
The well-known BTZ black hole solution of (2+1) Einstein's gravity, in the
presence of a cosmological constant, is treated both at the classical and
quantum level. Classically, the imposition of the two manifest local Killing
fields of the BTZ geometry at the level of the full action results in a
mini-superspace constraint action with the radial coordinate playing the role
of the independent dynamical variable. The Noether symmetries of this reduced
action are then shown to completely determine the classical solution space,
without any further need to solve the dynamical equations of motion. At a
quantum mechanical level, all the admissible sets of the quantum counterparts
of the generators of the above mentioned symmetries are utilized as
supplementary conditions acting on the wave-function. These additional
restrictions, in conjunction with the Wheeler-DeWitt equation, help to
determine (up to constants) the wave-function which is then treated
semiclassically, in the sense of Bohm. The ensuing space-times are, either
identical to the classical geometry, thus exhibiting a good correlation of the
corresponding quantization to the classical theory, or are less symmetric but
exhibit no Killing or event horizon and no curvature singularity, thus
indicating a softening of the classical conical singularity of the BTZ
geometry.Comment: 24 pages, no figures, LaTeX 2e source fil
Towards Canonical Quantum Gravity for G1 Geometries in 2+1 Dimensions with a Lambda--Term
The canonical analysis and subsequent quantization of the (2+1)-dimensional
action of pure gravity plus a cosmological constant term is considered, under
the assumption of the existence of one spacelike Killing vector field. The
proper imposition of the quantum analogues of the two linear (momentum)
constraints reduces an initial collection of state vectors, consisting of all
smooth functionals of the components (and/or their derivatives) of the spatial
metric, to particular scalar smooth functionals. The demand that the
midi-superspace metric (inferred from the kinetic part of the quadratic
(Hamiltonian) constraint) must define on the space of these states an induced
metric whose components are given in terms of the same states, which is made
possible through an appropriate re-normalization assumption, severely reduces
the possible state vectors to three unique (up to general coordinate
transformations) smooth scalar functionals. The quantum analogue of the
Hamiltonian constraint produces a Wheeler-DeWitt equation based on this reduced
manifold of states, which is completely integrated.Comment: Latex 2e source file, 25 pages, no figures, final version (accepted
in CQG
Second release of the CoRe database of binary neutron star merger waveforms
We present the second data release of gravitational waveforms from binaryneutron star merger simulations performed by the Computational Relativity(CoRe) collaboration. The current database consists of 254 different binaryneutron star configurations and a total of 590 individual numerical-relativitysimulations using various grid resolutions. The released waveform data containthe strain and the Weyl curvature multipoles up to . They span asignificant portion of the mass, mass-ratio,spin and eccentricity parameterspace and include targeted configurations to the events GW170817 and GW190425.CoRe simulations are performed with 18 different equations of state, seven ofwhich are finite temperature models, and three of which account fornon-hadronic degrees of freedom. About half of the released data are computedwith high-order hydrodynamics schemes for tens of orbits to merger; the otherhalf is computed with advanced microphysics. We showcase a standard waveformerror analysis and discuss the accuracy of the database in terms offaithfulness. We present ready-to-use fitting formulas for equation ofstate-insensitive relations at merger (e.g. merger frequency), luminosity peak,and post-merger spectrum.<br
Towards Canonical Quantum Gravity for Geometries Admitting Maximally Symmetric Two-dimensional Surfaces
The 3+1 (canonical) decomposition of all geometries admitting two-dimensional
space-like surfaces is exhibited. A proposal consisting of a specific
re-normalization {\bf Assumption} and an accompanying {\bf Requirement} is put
forward, which enables the canonical quantization of these geometries. The
resulting Wheeler-deWitt equation is based on a re-normalized manifold
parameterized by three smooth scalar functionals. The entire space of solutions
to this equation is analytically given, exploiting the freedom left by the
imposition of the {\bf Requirement} and contained in the third functional.Comment: 27 pages, no figures, LaTex2e source fil
Self‐Fertility in a Cultivated Diploid Potato Population Examined with the Infinium 8303 Potato Single‐Nucleotide Polymorphism Array
Conditional Symmetries and the Canonical Quantization of Constrained Minisuperspace Actions: the Schwarzschild case
A conditional symmetry is defined, in the phase-space of a quadratic in
velocities constrained action, as a simultaneous conformal symmetry of the
supermetric and the superpotential. It is proven that such a symmetry
corresponds to a variational (Noether) symmetry.The use of these symmetries as
quantum conditions on the wave-function entails a kind of selection rule. As an
example, the minisuperspace model ensuing from a reduction of the Einstein -
Hilbert action by considering static, spherically symmetric configurations and
r as the independent dynamical variable, is canonically quantized. The
conditional symmetries of this reduced action are used as supplementary
conditions on the wave function. Their integrability conditions dictate, at a
first stage, that only one of the three existing symmetries can be consistently
imposed. At a second stage one is led to the unique Casimir invariant, which is
the product of the remaining two, as the only possible second condition on
. The uniqueness of the dynamical evolution implies the need to identify
this quadratic integral of motion to the reparametrisation generator. This can
be achieved by fixing a suitable parametrization of the r-lapse function,
exploiting the freedom to arbitrarily rescale it. In this particular
parametrization the measure is chosen to be the determinant of the supermetric.
The solutions to the combined Wheeler - DeWitt and linear conditional symmetry
equations are found and seen to depend on the product of the two "scale
factors"Comment: 20 pages, LaTeX2e source file, no figure
Immunohistochemical evaluation of the mTOR pathway in intra-oral minor salivary gland neoplasms
Objectives: The aim of this study was to investigate the expression of upstream and downstream molecules of the oncogenic mTOR signaling pathway in intra-oral minor salivary gland tumors (SGTs). Materials and Methods: Tissue samples consisted of 39 malignant and 13 benign minor SGTs, and 8 controls of normal minor salivary glands (NMSG). An immunohistochemical analysis for phosphorylated Akt, 4EBP1 and S6 (total and phosphorylated), and eIF4E was performed. Results: Expression of pAkt and 4EBP1 was observed in all SGTs and in most NMSG. p4EBP1 was detected in almost all SGT cases, NMSG being negative. S6 immunoreactivity was observed in 37.5% of NMSG, 92.3% of benign and 100% of malignant SGTs, while pS6 expression was observed in 77% of benign and 95% of malignant SGTs, but not in NMSG. Finally, eIF4E was expressed in 12.5% of NMSG, 69.2% of benign, and 76.9% of malignant tumors. All molecules studied had statistically significantly lower expression in NMSG compared with SGTs. Moreover, malignant neoplasms received higher scores compared with benign tumors for all molecules with the exception of eIF4E. Conclusion: The mTOR signaling pathway is activated in SGTs, especially in malignancies. Therefore, the possible therapeutic role of targeting the mTOR pathway by rapamycin analogs in SGTs needs further investigation. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Lt
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