4,915 research outputs found
B-Meson Observables in the Maximally CP-Violating MSSM with Minimal Flavour Violation
Additional sources of CP violation in the MSSM may affect B-meson mixings and
decays, even in scenarios with minimal flavour violation (MFV). We formulate
the maximally CP-violating and minimally flavour-violating (MCPMFV) variant of
the MSSM, which has 19 parameters, including 6 phases that violate CP. We then
develop a manifestly flavour-covariant effective Lagrangian formalism for
calculating Higgs-mediated FCNC observables in the MSSM at large tan(beta), and
analyze within the MCPMFV framework FCNC and other processes involving B
mesons. We include a new class of dominant subleading contributions due to
non-decoupling effects of the third-generation quarks. We present illustrative
numerical results that include effects of the CP-odd MCPMFV parameters on Higgs
and sparticle masses, the B_s and B_d mass differences, and on the decays B_s
--> mu+ mu-, B_u --> tau nu and b --> s gamma. We use these results to derive
illustrative constraints on the MCPMFV parameters imposed by D0, CDF, BELLE and
BABAR measurements of B mesons, demonstrating how a potentially observable
contribution to the CP asymmetry in the b --> s gamma decay may arise in the
MSSM with MCPMFV.Comment: 47 pages, 8 eps figures, comments and references added, accepted for
publication in Physical Review D, Eq.(3.2) correcte
A model for correlations in stock markets
We propose a group model for correlations in stock markets. In the group
model the markets are composed of several groups, within which the stock price
fluctuations are correlated. The spectral properties of empirical correlation
matrices reported in [Phys. Rev. Lett. {\bf 83}, 1467 (1999); Phys. Rev. Lett.
{\bf 83}, 1471 (1999.)] are well understood from the model. It provides the
connection between the spectral properties of the empirical correlation matrix
and the structure of correlations in stock markets.Comment: two pages including one EPS file for a figur
Differences in citation frequency of clinical and basic science papers in cardiovascular research
In this article, a critical analysis is performed on differences in citation frequency of basic and clinical cardiovascular papers. It appears that the latter papers are cited at about 40% higher frequency. The differences between the largest number of citations of the most cited papers are even larger. It is also demonstrated that the groups of clinical and basic cardiovascular papers are also heterogeneous concerning citation frequency. It is concluded that none of the existing citation indicators appreciates these differences. At this moment these indicators should not be used for quality assessment of individual scientists and scientific niches with small numbers of scientists
Structural basis for the role of inhibition in facilitating adult brain plasticity
Although inhibition has been implicated in mediating plasticity in the adult brain, the underlying mechanism remains unclear. Here we present a structural mechanism for the role of inhibition in experience-dependent plasticity. Using chronic in vivo two-photon microscopy in the mouse neocortex, we show that experience drives structural remodeling of superficial layer 2/3 interneurons in an input- and circuit-specific manner, with up to 16% of branch tips undergoing remodeling. Visual deprivation initially induces dendritic branch retractions, and this is accompanied by a loss of inhibitory inputs onto neighboring pyramidal cells. The resulting decrease in inhibitory tone, also achievable pharmacologically using the antidepressant fluoxetine, provides a permissive environment for further structural adaptation, including addition of new synapse-bearing branch tips. Our findings suggest that therapeutic approaches that reduce inhibition, when combined with an instructive stimulus, could facilitate restructuring of mature circuits impaired by damage or disease, improving function and perhaps enhancing cognitive abilities
Perturbative Expansion around the Gaussian Effective Action: The Background Field Method
We develop a systematic method of the perturbative expansion around the
Gaussian effective action based on the background field method. We show, by
applying the method to the quantum mechanical anharmonic oscillator problem,
that even the first non-trivial correction terms greatly improve the Gaussian
approximation.Comment: 16 pages, 3 eps figures, uses RevTeX and epsf. Errors in Table 1 are
corrected and new references are adde
Protein Inhibitor of Activated STAT3 (PIAS3) Is Down-Regulated in Eutopic Endometrium of Women with Endometriosis
Endometriosis is a major cause of chronic pelvic pain and infertility. Activation of STAT3 appears central to the inflammatory phenotype of eutopic endometrium in women with endometriosis. However, the molecular mechanism by which this occurs remains unknown. Our objective is to determine how STAT3 activity is regulated in endometriosis. Protein inhibitor of activated STAT3 (PIAS3) is a negative regulator of STAT3 activity. We examined the levels of PIAS3 in endometrium from women with and without endometriosis using Western blot analysis and immunohistochemistry. Levels of PIAS3 are significantly lower, in contrast with phosphorylation of STAT3, in women with endometriosis compared to women without endometriosis. Furthermore, induction of endometriosis in the baboon showed a significant reduction of PIAS3 expression during the progression of the disease. Interferon-γ (INFγ) reduces PIAS3 protein levels and increases phospho-STAT3 levels through CXCL10 in endometrial cells, Ishikawa, and 12Z cells. These results suggest that attenuation of PIAS3 causes aberrant activation of STAT3 in endometriosis, leading to inflammatory changes that may impair fertility or cause pain
Bibliometric data in clinical cardiology revisited. The case of 37 Dutch professors
In this paper, we assess the bibliometric parameters of 37 Dutch professors in clinical cardiology. Those are the Hirsch index (h-index) based on all papers, the h-index based on first authored papers, the number of papers, the number of citations and the citations per paper. A top 10 for each of the five parameters was compiled. In theory, the same 10 professors might appear in each of these top 10s. Alternatively, each of the 37 professors under assessment could appear one or more times. In practice, we found 22 out of these 37 professors in the 5 top 10s. Thus, there is no golden parameter. In addition, there is too much inhomogeneity in citation characteristics even within a relatively homogeneous group of clinical cardiologists. Therefore, citation analysis should be applied with great care in science policy. This is even more important when different fields of medicine are compared in university medical centres. It may be possible to develop better parameters in the future, but the present ones are simply not good enough. Also, we observed a quite remarkable explosion of publications per author which can, paradoxical as it may sound, probably not be interpreted as an increase in productivity of scientists, but as the effect of an increase in the number of co-authors and the strategic effect of networks
Anomalous Roughness in Dimer-Type Surface Growth
We point out how geometric features affect the scaling properties of
non-equilibrium dynamic processes, by a model for surface growth where
particles can deposit and evaporate only in dimer form, but dissociate on the
surface. Pinning valleys (hill tops) develop spontaneously and the surface
facets for all growth (evaporation) biases. More intriguingly, the scaling
properties of the rough one dimensional equilibrium surface are anomalous. Its
width, , diverges with system size , as
instead of the conventional universal value . This originates
from a topological non-local evenness constraint on the surface configurations.Comment: Published version in PR
Renormalized Thermodynamic Entropy of Black Holes in Higher Dimensions
We study the ultraviolet divergent structures of the matter (scalar) field in
a higher D-dimensional Reissner-Nordstr\"{o}m black hole and compute the matter
field contribution to the Bekenstein-Hawking entropy by using the Pauli-Villars
regularization method. We find that the matter field contribution to the black
hole entropy does not, in general, yield the correct renormalization of the
gravitational coupling constants. In particular we show that the matter field
contribution in odd dimensions does not give the term proportional to the area
of the black hole event horizon.Comment: Final Revision Form as to be published in Physical Review D, ReVTeX,
No Figure
Gravity from Quantum Information
It is suggested that the Einstein equation can be derived from Landauer's
principle applied to an information erasing process at a local Rindler horizon
and Jacobson's idea linking the Einstein equation with thermodynamics. When
matter crosses the horizon, the information of the matter disappears and the
horizon entanglement entropy increases to compensate the entropy reduction. The
Einstein equation describes an information-energy relation during this process,
which implies that entropic gravity is related to the quantum entanglement of
the vacuum and has a quantum information theoretic origin.Comment: 7 pages, revtex4-1, 2 figures, recent supporting results adde
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