Remarks on a Decrumpling Model of the Universe

It is argued that when the dimension of space is a constant integer the full set of Einstein's field equations has more information than the spatial components of Einstein's equation plus the energy conservation law. Applying the former approach to the decrumpling FRW cosmology recently proposed, it is shown that the spacetime singularity cannot be avoided and that turning points are absent. This result is in contrast to the decrumpling nonsingular spacetime model with turning points previously obtained using the latter approach.Comment: 8 pages, latex, no figure

Limits on the Time Evolution of Space Dimensions from Newton's Constant

Limits are imposed upon the possible rate of change of extra spatial dimensions in a decrumpling model Universe with time variable spatial dimensions (TVSD) by considering the time variation of (1+3)-dimensional Newton's constant. Previous studies on the time variation of (1+3)-dimensional Newton's constant in TVSD theory had not been included the effects of the volume of the extra dimensions and the effects of the surface area of the unit sphere in D-space dimensions. Our main result is that the absolute value of the present rate of change of spatial dimensions to be less than about 10^{-14}yr^{-1}. Our results would appear to provide a prima facie case for ruling the TVSD model out. We show that based on observational bounds on the present-day variation of Newton's constant, one would have to conclude that the spatial dimension of the Universe when the Universe was at the Planck scale to be less than or equal to 3.09. If the dimension of space when the Universe was at the Planck scale is constrained to be fractional and very close to 3, then the whole edifice of TVSD model loses credibility.Comment: 22 pages, accepted for publication in Int.J.Mod.Phys.

Fermionic microstates within Painlev\'e-Gullstrand black hole

We consider the quantum vacuum of fermionic field in the presence of a black-hole background as a possible candidate for the stabilized black hole. The stable vacuum state (as well as thermal equilibrium states with arbitrary temperature) can exist if we use the Painlev\'e-Gullstrand description of the black hole, and the superluminal dispersion of the particle spectrum at high energy, which is introduced in the free-falling frame. Such choice is inspired by the analogy between the quantum vacuum and the ground state of quantum liquid, in which the event horizon for the low-energy fermionic quasiparticles also can arise. The quantum vacuum is characterized by the Fermi surface, which appears behind the event horizon. We do not consider the back reaction, and thus there is no guarantee that the stable black hole exists. But if it does exist, the Fermi surface behind the horizon would be the necessary attribute of its vacuum state. We also consider exact discrete spectrum of fermions inside the horizon which allows us to discuss the problem of fermion zero modes.Comment: LaTeX, 20 pages, 2 figure

Galactic Cosmic Strings as Sources of Primary Antiprotons

A possible signature of a class of superconducting cosmic strings trapped in the Milky Way plasma is the emission of low energy antiprotons due to baryon number violating processes on the string. We find the terrestrial flux and the energy spectrum of such antiprotons. Current observational bounds on the flux of low energy antiprotons place a {\it lower} bound on the string tension which is comparable to that given by the electroweak scale.Comment: 11 pages; added reference to recent observations of low energy antiproton

The Prevalence of Amblyopia in 7-year-old Schoolchildren in Iran

Purpose: To determine the prevalence of amblyopia in schoolchildren aged 7 years in Iran, its relation with refractive errors, and its determinants. Methods: In this cross-sectional study, cluster sampling was done from elementary school students in 7 cities in Iran. In all schools, an optometrist conducted all tests, including measurement of uncorrected and corrected visual acuity, cycloplegic refraction, and cover test. In this study, amblyopia was defined as best corrected visual acuity 20/30 or less or a 2-line interocular optotype acuity difference with no pathology. Results: Of the 4157 students selected for the study, 3675 participated and final analyses were done with data from 3547 children. The prevalence of amblyopia was 1.88 (95 CI: 1.24-2.52) (n=63). The prevalence was 1.91 (95 CI: 0.85-2.97) in boys and 1.85 (95 CI: 1.12-2.58) in girls (p=0.92). Among these cases, 60.30 (n=38) were unilateral. Also, 61.9 were strabismic, 27.0 were anisometropic, 9.5 were isometropic, and one case (1.6) was due to congenital cataracts. Amblyopic individuals were more hypermetropic and the mean cylinder error was significantly higher. Conclusion: Necessary attention should be paid to amblyopia, although its prevalence in Iran is mid-range when compared with other countries. Amblyopia is more common in hyperopic and astigmatic individuals and therefore it is important to pay more attention to this refractive error during childhood. Since strabismus is the most common cause of amblyopia in Iran, children need to be checked for strabismus before the age of 5 years. © 2014 Informa Healthcare USA, Inc. All rights reserved: reproduction in whole or part not permitted

The randomised uterine septum transsection trial (TRUST) : Design and protocol

Peer reviewedPublisher PD

Cosmic Topological Defects, Highest Energy Cosmic Rays, and the Baryon Asymmetry of the Universe

It is pointed out that the observed extremely high energy cosmic rays (EHECR) above $10^{11}$ GeV and the observed baryon asymmetry of the Universe (BAU), both may have a common origin in baryon number violating decays of supermassive ``X'' particles released from cosmic topological defects (TDs) such as cosmic strings and monopoles. The X particles produced by TDs in the recent epochs produce the EHECR, while the BAU is created by X particles released from TDs mainly in the very early Universe. In this scenario the EHECR is predicted to contain baryons as well as antibaryons with a small asymmetry between the two.Comment: 4 pages, RevTex, no figures, discussions and references added, other minor changes, version to appear in Phys. Rev. Let

TeV and Superheavy Mass-Scale Particles from Supersymmetric Topological Defects, the Extragalactic Gamma-ray Background, and the Highest Energy Cosmic Rays

Cosmic topological defects in a wide class of supersymmetric theories can simultaneously be sources of higgs particles of mass comparable to the supersymmetry breaking scale $\sim$ TeV, as well as superheavy gauge bosons of mass $\sim\eta$, where $\eta$ (>> 1 TeV) denotes the associated gauge symmetry breaking scale. For cosmic strings with $\eta\sim 10^{14}$ GeV, the higgs decay can account for the extragalactic diffuse gamma ray background above $\sim$ 10 GeV, while the gauge boson decay may explain the highest energy cosmic ray flux above $\sim 10^{11}$ GeV, provided that particle production is the dominant energy loss mechanism for cosmic strings, as recent simulations suggest. By the same token, cosmic strings with $\eta$ much above $\sim 10^{14}$ GeV will be ruled out.Comment: 4 pages, Revtex, includes 1 figure, major changes in text, arguments made more general, main conclusions unchanged, version accepted for publication in PR

Contribution of NADPH Oxidase to Membrane CD38 Internalization and Activation in Coronary Arterial Myocytes

The CD38-ADP-ribosylcyclase-mediated Ca2+ signaling pathway importantly contributes to the vasomotor response in different arteries. Although there is evidence indicating that the activation of CD38-ADP-ribosylcyclase is associated with CD38 internalization, the molecular mechanism mediating CD38 internalization and consequent activation in response to a variety of physiological and pathological stimuli remains poorly understood. Recent studies have shown that CD38 may sense redox signals and is thereby activated to produce cellular response and that the NADPH oxidase isoform, NOX1, is a major resource to produce superoxide (O2·−) in coronary arterial myocytes (CAMs) in response to muscarinic receptor agonist, which uses CD38-ADP-ribosylcyclase signaling pathway to exert its action in these CAMs. These findings led us hypothesize that NOX1-derived O2·− serves in an autocrine fashion to enhance CD38 internalization, leading to redox activation of CD38-ADP-ribosylcyclase activity in mouse CAMs. To test this hypothesis, confocal microscopy, flow cytometry and a membrane protein biotinylation assay were used in the present study. We first demonstrated that CD38 internalization induced by endothelin-1 (ET-1) was inhibited by silencing of NOX1 gene, but not NOX4 gene. Correspondingly, NOX1 gene silencing abolished ET-1-induced O2·− production and increased CD38-ADP-ribosylcyclase activity in CAMs, while activation of NOX1 by overexpression of Rac1 or Vav2 or administration of exogenous O2·−significantly increased CD38 internalization in CAMs. Lastly, ET-1 was found to markedly increase membrane raft clustering as shown by increased colocalization of cholera toxin-B with CD38 and NOX1. Taken together, these results provide direct evidence that Rac1-NOX1-dependent O2·− production mediates CD38 internalization in CAMs, which may represent an important mechanism linking receptor activation with CD38 activity in these cells