11,142 research outputs found
Antioxidant Supplementation in the Treatment of Aging-Associated Diseases
Oxidative stress is generally considered as the consequence of an imbalance between pro- and antioxidants species, which often results into indiscriminate and global damage at the organismal level. Elderly people are more susceptible to oxidative stress and this depends, almost in part, from a decreased performance of their endogenous antioxidant system. As many studies reported an inverse correlation between systemic levels of antioxidants and several diseases, primarily cardiovascular diseases, but also diabetes and neurological disorders, antioxidant supplementation has been foreseen as an effective preventive and therapeutic intervention for aging-associated pathologies. However, the expectations of this therapeutic approach have often been partially disappointed by clinical trials. The interplay of both endogenous and exogenous antioxidants with the systemic redox system is very complex and represents an issue that is still under debate. In this review a selection of recent clinical studies concerning antioxidants supplementation and the evaluation of their influence in aging-related diseases is analyzed. The controversial outcomes of antioxidants supplementation therapies, which might partially depend from an underestimation of the patient specific metabolic demand and genetic background, are presented
Chiral Lagrangians with tensor sources
The implementation of tensor sources in Chiral Lagrangians allows the
computation of Green functions and form factors involving tensor currents, that
is, quark bilinears of the form \bar{q}_i\sigma^{\mu\nu}q_j. Whereas only four
new terms show up at O(p^4), we find around a hundred of them at O(p^6). So it
becomes essential to ensure that this set o operators is indeed minimal and
non-redundant (i.e., it is a basis). We discuss two phenomenological
applications in the context of vector meson resonances and the radiative pion
decay.Comment: Talk given at the 4th International Worshop on Quantum
ChromoDynamics, Theory and experiment, June 16-20, 2007. Martina Franca -
Valle d'Itria - Ital
Test particle motion in a gravitational plane wave collision background
Test particle geodesic motion is analysed in detail for the background
spacetimes of the degenerate Ferrari-Ibanez colliding gravitational wave
solutions. Killing vectors have been used to reduce the equations of motion to
a first order system of differential equations which have been integrated
numerically. The associated constants of the motion have also been used to
match the geodesics as they cross over the boundary between the single plane
wave and interaction zones.Comment: 11 pages, 6 Postscript figure
Neutrino current in a gravitational plane wave collision background
The behaviour of a massless Dirac field on a general spacetime background
representing two colliding gravitational plane waves is discussed in the
Newman-Penrose formalism. The geometrical properties of the neutrino current
are analysed and explicit results are given for the special Ferrari-Ibanez
solution.Comment: 17 pages, 6 Postscript figures, accepted by International Journal of
Modern Physics
Analytical results for long time behavior in anomalous diffusion
We investigate through a Generalized Langevin formalism the phenomenon of
anomalous diffusion for asymptotic times, and we generalized the concept of the
diffusion exponent. A method is proposed to obtain the diffusion coefficient
analytically through the introduction of a time scaling factor . We
obtain as well an exact expression for for all kinds of diffusion.
Moreover, we show that is a universal parameter determined by the
diffusion exponent. The results are then compared with numerical calculations
and very good agreement is observed. The method is general and may be applied
to many types of stochastic problem
A novel stepwise micro-TESE approach in non obstructive azoospermia
Background: The purpose of the study was to investigate whether micro-TESE can improve sperm retrieval rate
(SRR) compared to conventional single TESE biopsy on the same testicle or to contralateral multiple TESE, by
employing a novel stepwise micro-TESE approach in a population of poor prognosis patients with non-obstructive
azoospermia (NOA).
Methods: Sixty-four poor prognosis NOA men undergoing surgical testicular sperm retrieval for ICSI, from March
2007 to April 2013, were included in this study. Patients inclusion criteria were a) previous unsuccessful TESE, b)
unfavorable histology (SCOS, MA, sclerahyalinosis), c) Klinefelter syndrome. We employed a stepwise micro-TESE
consisting three-steps: 1) single conventional TESE biopsy; 2) micro-TESE on the same testis; 3) contralateral multiple
TESE.
Results: SRR was 28.1 % (18/64). Sperm was obtained in both the initial single conventional TESE and in the
following micro-TESE. The positive or negative sperm retrieval was further confirmed by a contralateral multiple
TESE, when performed. No significant pre-operative predictors of sperm retrieval, including patients’ age, previous
negative TESE or serological markers (LH, FSH, inhibin B), were observed at univariate or multivariate analysis.
Micro-TESE (step 2) did not improve sperm retrieval as compared to single TESE biopsy on the same testicle
(step 1) or multiple contralateral TESE (step 3).
Conclusions: Stepwise micro-TESE could represent an optimal approach for sperm retrieval in NOA men. In
our view, it should be offered to NOA patients in order to gradually increase surgical invasiveness, when
necessary. Stepwise micro-TESE might also reduce the costs, time and efforts involved in surgery
Dynamics and Hadronization at intermediate transverse momentum at RHIC
The ultra-relativistic heavy-ion program at RHIC has shown that at
intermediate transverse momenta (-6 GeV) standard (independent)
parton fragmentation can neither describe the observed baryon-to-meson ratios
nor the empirical scaling of the hadronic elliptic flow () according to
the number of valence quarks. Both aspects find instead a natural explanation
in a coalescence plus fragmentation approach to hadronization. After a brief
review of the main results for light quarks, we focus on heavy quarks showing
that a combined fragmentation and quark-coalescence framework is relevant also
here. Moreover, within relativistic Langevin simulations we find evidence for
the importance of heavy-light resonances in the Quark-Gluon Plasma (QGP) to
explain the strong energy loss and collective flow of heavy-quark spectra as
inferred from non-photonic electron observables. Such heavy-light resonances
can pave the way to a unified understanding of the microscopic structure of the
QGP and its subsequent hadronization by coalescence.Comment: Proceedings of the International Workshop on QCD - Martina Franca
(Italy), June 2007. To be published in AIP. 6 pages, 6 figure
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