146 research outputs found
Fine Structure Constant, Domain Walls, and Generalized Uncertainty Principle in the Universe
We study the corrections to the fine-structure constant from the generalized
uncertainty principle in the spacetime of a domain wall. We also calculate the
corrections to the standard formula to the energy of the electron in the
hydrogen atom to the ground state, in the case of spacetime of a domain wall
and generalized uncertainty principle. The results generalize the cases known
in literature.Comment: 8 pages. Accepted for publication in International Journal of
Mathematics and Mathematical Science
Spontaneous Generation of Magnetic Field in Three Dimensional QED at Finite Temperature
We investigate the effects of thermal fluctuations on the spontaneous
magnetic condensate in three dimensional QED coupled with P-odd Dirac fermions.
Our results show that the phenomenon of the spontaneous generation of the
constant background magnetic field survives to the thermal corrections even at
infinite temperature. We also study the thermal corrections to the fermionic
condensate in presence of the magnetic field.Comment: Final version, to appear in Phys. Lett.
Dynamical Generation of the Primordial Magnetic Field by Ferromagnetic Domain Walls
The spontaneous generation of uniform magnetic condensate in gives
rise to ferromagnetic domain walls at the electroweak phase transition. These
ferromagnetic domain walls are caracterized by vanishing effective surface
energy density avoiding, thus, the domain wall problem. Moreover we find that
the domain walls generate a magnetic field at the
electroweak scale which account for the seed field in the so called dynamo
mechanism for the cosmological primordial magnetic field. We find that the
annihilation processes of walls with size could release an
energy of order indicating the invisible ferromagnetic walls as
possible compact sources of Gamma Ray Bursts.Comment: LaTeX, 8 pages, 1 figur
Generalized Gaussian Effective Potential: Second Order Thermal Corrections
We discuss the finite temperature generalized Gaussian effective potential.
We put out a very simple relation between the thermal corrections to the
generalizedGaussian effective potential and those of the effective potential.
We evaluate explicitly the second order thermal corrections in the case of the
selfinteracting scalar field in one spatial dimension.Comment: 13 pages, uuencoded compressed (using GNU's gzip) tar file containing
1 TeX file, 3 Postscript figure
Fractal universe and cosmic acceleration in a Lema\^itre-Tolman-Bondi scenario
In this paper we attempt to answer to the question: can cosmic acceleration
of the Universe have a fractal solution? We give an exact solution of a
Lema\^itre-Tolman-Bondi (LTB) Universe based on the assumption that such a
smooth metric is able to describe, on average, a fractal distribution of
matter. While the LTB model has a center, we speculate that, when the fractal
dimension is not very different from the space dimension, this metric applies
to any point of the fractal structure when chosen as center so that, on
average, there is not any special point or direction. We examine the observed
magnitude-redshift relation of type Ia supernovae (SNe Ia), showing that the
apparent acceleration of the cosmic expansion can be explained as a consequence
of the fractal distribution of matter when the corresponding space-time metric
is modeled as a smooth LTB one and if the fractal dimension on scales of a few
hundreds Mpc is .Comment: 6 pages, 4 figures, accepted for publication in Classical and Quantum
Gravit
Pathogenesis of the obstetric antiphospholipid syndrome: the key role of beta 2 glycoprotein I
Antiphospholipid syndrome (APS) is defined by recurrent pregnancy morbidity and/or vascular thrombosis associated with the persistent presence of antibodies against anionic phospholipid-binding proteins. Beta 2 glycoprotein I (β2GPI) and prothrombin (PT) are the major antigens for antiphospholipid antibodies (aPL) detectable by functional coagulation [lupus anticoagulant (LA)] or solid-phase assays [anti-β2GPI-dependent cardiolipin (aCL) and anti-β2GPI]. β2GPI-dependent aPL are responsible for the positivity of the three classification laboratory criteria. While medium/high titers of antibodies against β2GPI are risk factors for both the vascular and the obstetric manifestations of APS, persistent low titers are also associated with pregnancy complications. There is evidence from animal models of aPL-dependent fetal loss and from in vitro systems that β2GPI-dependent aPL can be pathogenic. β2GPI is physiologically found in large quantities at the placental level being available for the specific antibodies circulating in the maternal blood. Once bound to the protein, the antibodies trigger a local inflammation via the activation of the complement cascade and affect trophoblast and decidual function. The final result is represented by defective placentation, while thrombotic events are apparently less important. β2GPI is a pleiotropic molecule with scavenging properties towards several molecules including apoptotic material and displays anti-oxidant activity. These functions may explain the β2GPI placental localization in an area of intensive tissue remodeling and low oxygen tension. Since β2GPI interacts also with the complement and the coagulation cascade, its binding with specific antibodies may affect the physiology of placentation in several ways
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PROTECTIVE EFFECT OF γ-IRRADIATION AGAINST HYPOCHLOROUS ACID- INDUCED HAEMOLYSIS IN HUMAN ERYTHROCYTES
Radiations may trigger protective response within a threshold of doses applied. Exposures above an upper threshold are generally detrimental, while exposures below a lower threshold may or may not increase risks for health. We recently reported that a cellular protective response occurs in interventional cardiologists to counteract the oxidative damage caused by radiation. Here, we demonstrated in an in vitro model represented by whole blood of healthy donors γ-irradiated with 220-440 mGy, that haemolysis of erythrocytes induced by hypochlorous acid was reduced by 40%. The protection triggered by γ- radiations made erythrocytes more resistant to oxidative insult caused by hypochlorous acid which was induced 3 h after irradiation and involved biochemical changes in the syn- thesis and turnover of glutathione. Overall, the biochemical remodelling induced by exposure to γ-radiations might contribute to generate new guidelines in professionally exposed workers
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