687 research outputs found
Noise induced hearing loss: the role of oxidative stress
Introduction: Noise-induced hearing loss (NIHL) is a relevant source of hearing disability affecting the general population, and accounts for about 16% of all the reported cases of disabling hearing loss in the adult population worldwide. NIHL can follow workplace-related and recreational noise exposure, and can be influenced by individual factors such as age, sex, genetic predisposition and socio-economic factors. Objectives: The aim of this paper is to provide a quick overview of the principal ndings in noise induced hearing loss, focusing on the role of oxidative stress and antioxidant intervention. Review: Oxidative stress plays a central role in leading to a condition of NIHL. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) largely participate in cellular mechanisms that underlie mainly the outer hair cell death after noise exposure and lead to sensorineural hearing loss. The beneficial effects of antioxidant supplementation have been demonstrated by several experimental studies in animals, while the observed results in humans are mixed. Conclusion: NIHL still represents a widespread condition among the general population; with a higher prevalence in developing countries among workers, and in developed countries among young adults exposed to leisure noise. Extensive literature confirms that increasing antioxidant levels in the organ of Corti may be an appropriate approach towards understanding NIHL in humans by increasing the endogenous antioxidant response or by administering antioxidant molecules systemically or locally
Charmed Hadrons from Coalescence plus Fragmentation in relativistic nucleus-nucleus collisions at RHIC and LHC
In a coalescence plus fragmentation approach we calculate the heavy
baryon/meson ratio and the spectra of charmed hadrons ,
and in a wide range of transverse momentum from low up
to about 10 GeV and discuss their ratios from RHIC to LHC energies without any
change of the coalescence parameters. We have included the contribution from
decays of heavy hadron resonances and also the one due to fragmentation of
heavy quarks which do not undergo the coalescence process. The coalescence
process is tuned to have all charm quarks hadronizing in the
limit and at finite charm quarks not undergoing coalescence are
hadronized by independent fragmentation. The dependence of the
baryon/meson ratios are found to be sensitive to the masses of coalescing
quarks, in particular the can reach values of about at \mbox{GeV}, or larger, similarly to the light
baryon/meson ratio like and , however a marked difference is
a quite weak dependence with respect to the light case, such that a
larger value at intermediate implies a relatively large value also for
the integrated yields. A comparison with other coalescence model and with the
prediction of thermal model is discussed.Comment: 13 pages, 9 figures. Fig. 5 updated and some minor changes in the
tex
Heavy Flavor Production, Flow and Energy Loss
Abstract An overview of the current status of the heavy quarks as probe of the hot QCD in-medium interaction is presented. Heavy quarks that produced out-of-equilibrium but strongly interacting with the created quark-gluon plasma (QGP) bulk medium offer the unique opportunity to have a probe that thermalize in a time scale comparable with the lifetime of the QGP. Finally, the possible role of heavy quark for probing the initial strong electromagnetic field created in relativistic heavy-ion collisions is discussed
Impact of off-shell dynamics on the transport properties and the dynamical evolution of Charm Quarks at RHIC and LHC temperatures
We evaluate drag and diffusion transport coefficients comparing a
quasi-particle approximation with on-shell constituents of the QGP medium and a
dynamical quasi-particles model with off-shell bulk medium at finite
temperature T. We study the effects of the width of the particles of
the bulk medium on the charm quark transport properties exploring the range
where . We find that off-shell effects are in general quite
moderate and can induce a reduction of the drag coefficient at low momenta that
disappear already at moderate momenta, . We also
observe a moderate reduction of the breaking of the Fluctuation-Dissipation
theorem (FDT) at finite momenta.
Moreover, we have performed a first study of the dynamical evolution of HQ
elastic energy loss in a bulk medium at fixed temperature extending the
Boltzmann (BM) collision integral to include off-shell dynamics. A comparison
among the Langevin dynamics, the BM collisional integral with on-shell and the
BM extension to off-shell dynamics shows that the evolution of charm energy
when off-shell effects are included remain quite similar to the case of the
on-shell BM collision integral.Comment: 13 pages, 14 figure
- …