Alfven node-free vibrations of white dwarf in the model of solid star with toroidal magnetic field

In the context of the white dwarf asteroseismology, we investigate vibrational properties of a non-convective solid star with an axisymmetric purely toroidal intrinsic magnetic field of two different shapes. Focus is laid on regime of node-free global Lorentz-force-driven vibrations about symmetry axis at which material displacements have one and the same form as those for nodeless spheroidal and torsional vibrations restored by Hooke's force of elastic shear stresses. Particular attention is given to the even-parity poloidal Alfven modes whose frequency spectra are computed in analytic form showing how the purely toroidal magnetic fields completely buried beneath the star surface can manifest itself in seismic vibrations of non-magnetic white dwarfs. The obtained spectral formulae are discussed in juxtaposition with those for Alfven modes in the solid star model with the poloidal, homogeneous internal and dipolar external, magnetic field whose inferences are relevant to Alfven vibrations in magnetic white dwarfs.Comment: Accepted for publication in Astrophysics & Space Scienc

Quantitation of angiogenesis in vitro induced by VEGF-A and FGF-2 in two different human endothelial cultures : an all-in-one assay

Angiogenic therapy is considered to be a promising tool for treatment of ischemic diseases. Many in vivo and in vitro assays have been developed to identify potential proangiogenic drugs and to investigate their mode of action. However, until now no validated system exists that would allow quantitation of angiogenesis in vitro in only one assay. Here, a previously established all-in-one in vitro assay based on staging of the angiogenic cascade was validated by quantitation of the effects of the known proangiogenic factors VEGF-A and FGF-2. Both growth factors were applied separately or in combination to human endothelial cell cultures derived from the heart and the foreskin, and angiogenesis was quantitated over 30 days of culture. Additionally, gene expression of VEGFR-1, VEGFR-2 and FGFR-1 at 3, 10, 20 or 40 days of cultivation was quantitated by RT-qPCR. In both cultures, VEGF-A as well as FGF-2 induced a run through all defined stages of angiogenesis in vitro. Application of VEGF-A only led to formation of irregular globular endothelial structures, while FGF-2 resulted in development of regular capillary-like structures. Quantitation of the angiogenic effects of VEGF-A and transcripts of VEGFR-1 and VEGFR-2 showed that a high VEGFR-1/VEGFR-2 ratio evoked deceleration of angiogenesis

Congruences of lines in P5\mathbb{P}^5, quadratic normality, and completely exceptional Monge-Amp\`ere equations

The existence is proved of two new families of locally Cohen-Macaulay sextic threefolds in $\mathbb{P}^5$, which are not quadratically normal. These threefolds arise naturally in the realm of first order congruences of lines as focal loci and in the study of the completely exceptional Monge-Amp\`ere equations. One of these families comes from a smooth congruence of multidegree $(1,3,3)$ which is a smooth Fano fourfold of index two and genus 9.Comment: 16 page

Quantum Gravitational Corrections to the Real Klein-Gordon Field in the Presence of a Minimal Length

The (D+1)-dimensional $(\beta,\beta')$-two-parameter Lorentz-covariant deformed algebra introduced by Quesne and Tkachuk [C. Quesne and V. M. Tkachuk, J. Phys. A: Math. Gen. \textbf {39}, 10909 (2006).], leads to a nonzero minimal uncertainty in position (minimal length). The Klein-Gordon equation in a (3+1)-dimensional space-time described by Quesne-Tkachuk Lorentz-covariant deformed algebra is studied in the case where $\beta'=2\beta$ up to first order over deformation parameter $\beta$. It is shown that the modified Klein-Gordon equation which contains fourth-order derivative of the wave function describes two massive particles with different masses. We have shown that physically acceptable mass states can only exist for $\beta<\frac{1}{8m^{2}c^{2}}$ which leads to an isotropic minimal length in the interval $10^{-17}m<(\bigtriangleup X^{i})_{0}<10^{-15}m$. Finally, we have shown that the above estimation of minimal length is in good agreement with the results obtained in previous investigations.Comment: 10 pages, no figur

Investigation of dosimetry in four human head models for planar monopole antenna with a coupling feed for LTE/WWAN/WLAN internal mobile phone

The objective of the present study is to evaluate the Specific Absorption Rate (SAR) within the human head model exposed to the radiation of planar monopole antenna with T-shaped coupling feed and an inductive shorting strip. The presented design has a compact structure, a planar configuration and occupying a small size of 36×20mm2. Two wide bands can be generated by the proposed antenna 546 MHz (734-1280 MHz) and 1066 MHz (1934-3000 MHz) for the LTE/WWAN/WLAN internal mobile phone. The antenna performance parameters comprising return loss, radiation patterns, and gain are discussed. In this research work four different human head models have been implemented: homogenous spherical head, spherical seven layer model, Specific Anthropomorphic Mannequin (SAM) phantom and HUGO human head model. On the other hand the effects of operating frequency and gap distance between the mobile phone antenna and the human head model on distributions of the SAR inside the human head are investigated. All the simulations are done for three different distances between the antenna and the head model (5 mm, 10 mm and 20 mm). Moreover, the SAR levels for the head tissues are calculated in accordance to the two currently accepted standards: Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP)

Multicomponent theory of buoyancy instabilities in magnetized plasmas: The case of magnetic field parallel to gravity

We investigate electromagnetic buoyancy instabilities of the electron-ion plasma with the heat flux based on not the magnetohydrodynamic (MHD) equations, but using the multicomponent plasma approach when the momentum equations are solved for each species. We consider a geometry in which the background magnetic field, gravity, and stratification are directed along one axis. The nonzero background electron thermal flux is taken into account. Collisions between electrons and ions are included in the momentum equations. No simplifications usual for the one-fluid MHD-approach in studying these instabilities are used. We derive a simple dispersion relation, which shows that the thermal flux perturbation generally stabilizes an instability for the geometry under consideration. This result contradicts to conclusion obtained in the MHD-approach. We show that the reason of this contradiction is the simplified assumptions used in the MHD analysis of buoyancy instabilities and the role of the longitudinal electric field perturbation which is not captured by the ideal MHD equations. Our dispersion relation also shows that the medium with the electron thermal flux can be unstable, if the temperature gradients of ions and electrons have the opposite signs. The results obtained can be applied to the weakly collisional magnetized plasma objects in laboratory and astrophysics.Comment: Accepted for publication in Astrophysics & Space Scienc

Lepton Dipole Moments and Rare Decays in the CP-violating MSSM with Nonuniversal Soft-Supersymmetry Breaking

We investigate the muon anomalous magnetic dipole moment (MDM), the muon electric dipole moment (EDM) and the lepton-flavour-violating decays of the $\tau-$lepton, $\tau \to \mu \gamma$ and $\tau\to 3\mu$, in the CP-violating Minimal Supersymmetric Standard Model (MSSM) with nonuniversal soft-supersymmetry breaking. We evaluate numerically the muon EDM and the branching ratios $B(\tau \to \mu\gamma)$ and $B(\tau \to 3\mu)$, after taking into account the experimental constraints from the electron EDM and muon MDM. Upon imposition of the experimental limits on our theoretical predictions for the aforementioned branching ratios and the muon MDM, we obtain an upper bound of about $10^{-23} e\cdot cm$ on the muon EDM which lies well within the explorable reach of the proposed experiment at BNL.Comment: Latex, 26 pages, 8 figures, accepted for publication in Phys. Rev.

Frequency spectrum of toroidal Alfv\'en mode in a neutron star with Ferraro's form of nonhomogeneous poloidal magnetic field

Using the energy variational method of magneto-solid-mechanical theory of a perfectly conducting elastic medium threaded by magnetic field, the frequency spectrum of Lorentz-force-driven global torsional nodeless vibrations of a neutron star with Ferraro's form of axisymmetric poloidal nonhomogeneous internal and dipole-like external magnetic field is obtained and compared with that for this toroidal Alfv\'en mode in a neutron star with homogeneous internal and dipolar external magnetic field. The relevance of considered asteroseismic models to quasi-periodic oscillations of the X-ray flux during the ultra powerful outbursts of SGR 1806-20 and SGR 1900+14 is discussed.Comment: Accepted for publication in Astrophysics & Space Scienc

Astrophysical Axion Bounds

Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational consequences include a modification of the solar sound-speed profile, an increase of the solar neutrino flux, a reduction of the helium-burning lifetime of globular-cluster stars, accelerated white-dwarf cooling, and a reduction of the supernova SN 1987A neutrino burst duration. We review and update these arguments and summarize the resulting axion constraints.Comment: Contribution to Axion volume of Lecture Notes in Physics, 20 pages, 3 figure