283 research outputs found
Formation of hot heavy nuclei in supernova explosions
We point out that during the supernova II type explosion the thermodynamical
condition of stellar matter between the protoneutron star and the shock front
corresponds to the nuclear liquid-gas phase coexistence region, which can be
investigated in nuclear multifragmentation reactions. We have demonstrated,
that neutron-rich hot heavy nuclei can be produced in this region. The
production of these nuclei may influence dynamics of the explosion and
contribute to the synthesis of heavy elements.Comment: 6 pages with 4 figure
Multifragmentation of charge asymmetric nuclear systems
The multifragmentation of excited spherical nuclear sources with various N/Z
ratios and fixed mass number is studied within dynamical and statistical
models. The dynamical model treats the multifragmentation process as a final
stage of the growth of density fluctuations in unstable expanding nuclear
matter. The statistical model makes a choice of the final multifragment
configuration according to its statistical weight at a global thermal
equilibrium. Similarities and differences in the predictions of the two models
on the isotopic composition of the produced fragments are presented and the
most sensitive observable characteristics are discussed.Comment: 15 pages, 8 figure
Polarization quantum properties in type-II Optical Parametric Oscillator below threshold
We study the far field spatial distribution of the quantum fluctuations in
the transverse profile of the output light beam generated by a type II Optical
Parametric Oscillator below threshold, including the effects of transverse
walk-off. We study how quadrature field correlations depend on the
polarization. We find spatial EPR entanglement in quadrature-polarization
components: For the far field points not affected by walk-off there is almost
complete noise suppression in the proper quadratures difference of any
orthogonal polarization components. We show the entanglement of the state of
symmetric intense, or macroscopic, spatial light modes. We also investigate
nonclassical polarization properties in terms of the Stokes operators. We find
perfect correlations in all Stokes parameters measured in opposite far field
points in the direction orthogonal to the walk-off, while locally the field is
unpolarized and we find no polarization squeezing.Comment: 16 pages, 18 figure
First steps on the resistance profiling of Kawisari coffee hybrid through cytological and gene expression analyses
info:eu-repo/semantics/publishedVersio
Quantum Communication in Rindler Spacetime
A state that an inertial observer in Minkowski space perceives to be the
vacuum will appear to an accelerating observer to be a thermal bath of
radiation. We study the impact of this Davies-Fulling-Unruh noise on
communication, particularly quantum communication from an inertial sender to an
accelerating observer and private communication between two inertial observers
in the presence of an accelerating eavesdropper. In both cases, we establish
compact, tractable formulas for the associated communication capacities
assuming encodings that allow a single excitation in one of a fixed number of
modes per use of the communications channel. Our contributions include a
rigorous presentation of the general theory of the private quantum capacity as
well as a detailed analysis of the structure of these channels, including their
group-theoretic properties and a proof that they are conjugate degradable.
Connections between the Unruh channel and optical amplifiers are also
discussed.Comment: v3: 44 pages, accepted in Communications in Mathematical Physic
Signatures of Supernova Neutrino Oscillations into Extra Dimensions
We consider the mixing of muon and tau neutrinos with sterile fermion fields
propagating in extra dimensions in the context of core collapse supernova
physics, extending the analysis of the electron neutrino case done in a
previous work. We show that the potentially dramatic modifications to the
supernova evolution are prevented by a mechanism of feedback, so that no severe
bounds on the parameters of the extra dimensions need to be imposed.
Nevertheless, the supernova core evolution is significantly modified. We
discuss the consequences on the delayed explosion mechanism and the
compatibility with the SN1987A signal. Then, for the cases of both nu_{mu,tau}
and nu_e mixing with bulk fermions, we analyse the distinctive features of the
signal on Earth.Comment: 16 pages, 7 figures; v2: minor changes, matches published versio
Statistical approach for supernova matter
We formulate a statistical model for description of nuclear composition and
equation of state of stellar matter at subnuclear densities and temperature up
to 20 MeV, which are expected during the collapse and explosion of massive
stars. The model includes nuclear, electromagnetic and weak interactions
between all kinds of particles, under condition of statistical equilibrium. We
emphasize importance of realistic description of the nuclear composition for
understanding stellar dynamics and nucleosynthesis. It is demonstrated that the
experience accumulated in studies of nuclear multifragmentation reactions can
be used for better modelling properties of stellar medium.Comment: 35 pages including 23 figures, submitted to Nuclear Physics
Percolation of Color Sources and the Shear Viscosity of the QGP in Central A-A Collisions at RHIC and LHC Energies
The Color String Percolation Model (CSPM) is used to determine the shear
viscosity to entropy ratio () of the Quark-Gluon Plasma (QGP) produced
in Au-Au collisions at = 200 GeV at RHIC and Pb-Pb at
= 2.76 TeV at LHC. The relativistic kinetic theory relation for
is evaluated using CSPM values for the temperature and the mean free
path of the QGP constituents. The experimental charged hadron transverse
momentum spectrum is used to determine the percolation density parameter
in Au-Au collisions (STAR). For Pb-Pb at = 2.76 TeV
values are obtained from the extrapolation at RHIC energy. The value of
is 0.2040.020 and 0.2620.026 at the CSPM initial
temperatures of 193.63 MeV (RHIC) and 262.2 13 MeV (LHC)
respectively. These values are 2.5 and 3.3 times the AdS/CFT conjectured lower
bound . We compare the CSPM analytic expression with weak
coupling (wQGP) and strong coupling (sQGP) calculations. This indicates that
the QGP is a strongly coupled fluid in the phase transition region.Comment: 4 pages, 3 figures Accepted for publication in European Physical
Journal C (Particles & Fields
Twenty-six years of HIV science: an overview of anti-HIV drugs metabolism
From the identification of HIV as the agent causing AIDS, to the development of effective antiretroviral drugs, the scientific achievements in HIV research over the past twenty-six years have been formidable. Currently, there are twenty-five anti-HIV compounds which have been formally approved for clinical use in the treatment of AIDS. These compounds fall into six categories: nucleoside reverse transcriptase inhibitors (NRTIs), nucleotide reverse transcriptase inhibitors (NtRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), cell entry inhibitors or fusion inhibitors (FIs), co-receptor inhibitors (CRIs), and integrase inhibitors (INIs). Metabolism by the host organism is one of the most important determinants of the pharmacokinetic profile of a drug. Formation of active or toxic metabolites will also have an impact on the pharmacological and toxicological outcomes. Therefore, it is widely recognized that metabolism studies of a new chemical entity need to be addressed early in the drug discovery process. This paper describes an overview of the metabolism of currently available anti-HIV drugs.Da identificação do HIV como o agente causador da AIDS, ao desenvolvimento de fármacos antirretrovirais eficazes, os avanços científicos na pesquisa sobre o HIV nos últimos vinte e seis anos foram marcantes. Atualmente, existem vinte e cinco fármacos anti-HIV formalmente aprovados pelo FDA para utilização clínica no tratamento da AIDS. Estes compostos são divididos em seis classes: inibidores nucleosídeos de transcriptase reversa (INTR), inibidores nucleotídeos de transcriptase reversa (INtTR), inibidores não-nucleosídeos de transcriptase reversa (INNTR), inibidores de protease (IP), inibidores da entrada celular ou inibidores de fusão (IF), inibidores de co-receptores (ICR) e inibidores de integrase (INI). O metabolismo consiste em um dos maiores determinantes do perfil farmacocinético de um fármaco. A formação de metabólitos ativos ou tóxicos terá impacto nas respostas farmacológicas ou toxicológicas do fármaco. Portanto, é amplamente reconhecido que estudos do metabolismo de uma nova entidade química devem ser realizados durante as fases iniciais do processo de desenvolvimento de fármacos. Este artigo descreve uma abordagem do metabolismo dos fármacos anti-HIV atualmente disponíveis na terapêutica
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