1,042 research outputs found
Detrended Fluctuation analysis of Bach's Inventions and Sinfonias pitches
Detrended Fluctuation Analysis (DFA), suitable for the analysis of
nonstationary time series, is used to investigate power law in some of the
Bach's pitches series. Using DFA method, which also is a well-established
method for the detection of long-range correlations, frequency series of Bach's
pitches have been analyzed. In this view we find same Hurts exponents in the
range (0.7-0.8) in his Inventions and sinfonia.Comment: 5 pages, 4 figure
Signature change from Schutz's canonical quantum cosmology and its classical analogue
We study the signature change in a perfect fluid Friedmann-Robertson-Walker
quantum cosmological model. In this work the Schutz's variational formalism is
applied to recover the notion of time. This gives rise to a
Schrodinger-Wheeler-DeWitt equation with arbitrary ordering for the scale
factor. We use the eigenfunctions in order to construct wave packets and
evaluate the time-dependent expectation value of the scale factor which
coincides with the ontological interpretation. We show that these solutions
exhibit signature transitions from a finite Euclidean to a Lorentzian domain.
Moreover, such models are equivalent to a classical system where, besides the
perfect fluid, a repulsive fluid is present.Comment: 15 pages, 4 figures, to appear in PR
Quantum Stephani Universe in vicinity of the symmetry center
We study a class of spherically symmetric Stephani cosmological models in the
presence of a self-interacting scalar field in both classical and quantum
domains. We discuss the construction of `canonical' wave packets resulting from
the solutions of a class of Wheeler-DeWitt equations in the Stephani Universe.
We suggest appropriate initial conditions which result in wave packets
containing some desirable properties, most importantly good classical and
quantum correspondence. We also study the situation from de-Broglie Bohm
interpretation of quantum mechanics to recover the notion of time and compare
the classical and Bohmian results. We exhibit that the usage of the canonical
prescription and appropriate choices of expansion coefficients result in the
suppression of the quantum potential and coincidence between classical and
Bohmian results. We show that, in some cases, contrary to
Friedmann-Robertson-Walker case, the bound state solutions also exist for all
positive values of the cosmological constant.Comment: 22 pages, 19 figures, to appear in JCA
Quantum Stephani exact cosmological solutions and the selection of time variable
We study perfect fluid Stephani quantum cosmological model. In the present
work the Schutz's variational formalism which recovers the notion of time is
applied. This gives rise to Wheeler-DeWitt equation for the scale factor. We
use the eigenfunctions in order to construct wave packets for each case. We
study the time-dependent behavior of the expectation value of the scale factor,
using many-worlds and deBroglie-Bohm interpretations of quantum mechanics.Comment: 19 pages, 7 figure
Estrogen receptor-beta prevents cardiac fibrosis.
Development of cardiac fibrosis portends the transition and deterioration from hypertrophy to dilation and heart failure. Here we examined how estrogen blocks this important development. Angiotensin II (AngII) and endothelin-1 induce cardiac hypertrophy and fibrosis in humans. and we find that these agents directly stimulate the transition of the cardiac fibroblast to a myofibroblast. AngII and endothelin-1 stimulated TGFβ1 synthesis in the fibroblast, an inducer of fibrosis that signaled via c-jun kinase to Sma- and Mad-related protein 3 phosphorylation and nuclear translocation in myofibroblasts. As a result, mesenchymal proteins fibronectin and vimentin were produced, as were collagens I and III, the major forms found in fibrotic hearts. 17β-Estradiol (E2) or dipropylnitrile, an estrogen receptor (ER)β agonist, comparably blocked all these events, reversed by estrogen receptor (ER)β small interfering RNA. E2 and dipropylnitrile signaling through cAMP and protein kinase A prevented myofibroblast formation and blocked activation of c-jun kinase and important events of fibrosis. In the hearts of ovariectomized female mice, cardiac hypertrophy and fibrosis were induced by AngII infusion and prevented by E2 administration to wild type but not ERβ knockout rodents. Our results establish the cardiac fibroblast as an important target for hypertrophic/fibrosis-inducing peptides the actions of which were mitigated by E2/ERβ acting in these stromal cells
Fractional Loop Group and Twisted K-Theory
We study the structure of abelian extensions of the group of
-differentiable loops (in the Sobolev sense), generalizing from the case of
central extension of the smooth loop group. This is motivated by the aim of
understanding the problems with current algebras in higher dimensions. Highest
weight modules are constructed for the Lie algebra. The construction is
extended to the current algebra of supersymmetric Wess-Zumino-Witten model. An
application to the twisted K-theory on is discussed.Comment: Final version in Commun. Math. Phy
Canonical wave packets in quantum cosmology
We discuss the construction of wave packets resulting from the solutions of a
class of Wheeler-DeWitt equations in Robertson-Walker type cosmologies, for
arbitrary curvature. We show that there always exists a ``canonical initial
slope" for a given initial wave function, which optimizes some desirable
properties of the resulting wave packet, most importantly good
classical-quantum correspondence. This can be properly denoted as a canonical
wave packet. We introduce a general method for finding these canonical initial
slopes which is generalization of our earlier work.Comment: 19 pages, 8 figure
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