90 research outputs found
Equation of State of Nuclear Matter at high baryon density
A central issue in the theory of astrophysical compact objects and heavy ion
reactions at intermediate and relativistic energies is the Nuclear Equation of
State (EoS). On one hand, the large and expanding set of experimental and
observational data is expected to constrain the behaviour of the nuclear EoS,
especially at density above saturation, where it is directly linked to
fundamental processes which can occur in dense matter. On the other hand,
theoretical predictions for the EoS at high density can be challenged by the
phenomenological findings. In this topical review paper we present the
many-body theory of nuclear matter as developed along different years and with
different methods. Only nucleonic degrees of freedom are considered. We compare
the different methods at formal level, as well as the final EoS calculated
within each one of the considered many-body schemes. The outcome of this
analysis should help in restricting the uncertainty of the theoretical
predictions for the nuclear EoS.Comment: 51 pages, to appear in J. Phys. G as Topical Revie
Asymmetric nuclear matter in a Hartree-Fock approach to non-linear QHD
The Equation of State (EOS) for asymmetric nuclear matter is discussed
starting from a phenomenological hadronic field theory of Serot-Walecka type
including exchange terms. In a model with self interactions of the scalar
sigma-meson we show that the Fock terms naturally lead to isospin effects in
the nuclear EOS. These effects are quite large and dominate over the
contribution due to isovector mesons. We obtain a potential symmetry term of
"stiff" type, i.e. increasing with baryon density and an interesting behaviour
of neutron/proton effective masses of relevance for transport properties of
asymmetric dense matter.Comment: 12 pages (LATEX), 3 Postscript figures, revised versio
Pseudovector vs. pseudoscalar coupling in one-boson exchange NN potentials
We examine the effects of pseudoscalar and pseudovector coupling of the pi
and eta mesons in one-boson exchange models of the NN interaction using two
approaches: time-ordered perturbation theory unitarized with the relativistic
Lippmann-Schwinger equation, and a reduced Bethe-Salpeter equation approach
using the Thompson equation. Contact terms in the one-boson exchange amplitudes
in time-ordered perturbation theory lead naturally to the introduction of
s-channel nucleonic cutoffs for the interaction, which strongly suppresses the
far off-shell behavior of the amplitudes in both approaches. Differences
between the resulting NN predictions of the various models are found to be
small, and particularly so when coupling constants of the other mesons are
readjusted within reasonable limits.Comment: 24 pages, 4 figure
Photo- and Electroproduction of Eta Mesons
Eta photo- and electroproduction off the nucleon is investigated in an
effective lagrangian approach that contains Born terms and both vector meson
and nucleon resonance contributions. In particular, we review and develop the
formalism for coincidence experiments with polarization degrees of freedom. The
different response functions appearing in single and double polarization
experiments have been studied. We will present calculations for structure
functions and kinematical conditions that are most sensitive to details of the
lagrangian, in particular with regard to contributions of nucleon resonances
beyond the dominant (1535) resonance.Comment: 24 pages RevTeX/LaTeX2.09, NFSS1, 13 figures (in separate file
(tar,gzip and uue)), accepted for publication in Z. Phys.
Hadron Production in Heavy Ion Collisions
We review hadron production in heavy ion collisions with emphasis on pion and
kaon production at energies below 2 AGeV and on partonic collectivity at RHIC
energies.Comment: 31 pages, 26 figures, accepted for publication in Landolt-Boernstein
Volume 1-23
Evidence of maternal QTL affecting growth and obesity in adult mice
Most quantitative trait loci (QTL) studies fail to account for the effect that the maternal genotype may have on an individual’s phenotypes, even though maternal effect QTL have been shown to account for considerable variation in growth and obesity traits in mouse models. Moreover, the fetal programming theory suggests that maternal effects influence an offspring’s adult fitness, although the genetic nature of fetal programming remains unclear. Within this context, our study focused on mapping genomic regions associated with maternal effect QTL by analyzing the phenotypes of chromosomes 2 and 7 subcongenic mice from genetically distinct dams. We analyzed 12 chromosome 2 subcongenic strains that spanned from 70 to 180 Mb with CAST/EiJ donor regions on the background of C57BL/6 J, and 14 chromosome 7 subcongenic strains that spanned from 81 to 111 Mb with BALB/cByJ donor regions on C57BL/6ByJ background. Maternal QTL analyses were performed on the basis of overlapping donor regions between subcongenic strains. We identified several highly significant (P < 5 × 10−4) maternal QTL influencing total body weight, organ weight, and fat pad weights in both sets of subcongenics. These QTL accounted for 1.9-11.7% of the phenotypic variance for growth and obesity and greatly narrowed the genomic regions associated with the maternal genetic effects. These maternal effect QTL controlled phenotypic traits in adult mice, suggesting that maternal influences at early stages of development may permanently affect offspring performance. Identification of maternal effects in our survey of two sets of subcongenic strains, representing approximately 5% of the mouse genome, supports the hypothesis that maternal effects represent significant sources of genetic variation that are largely ignored in genetic studies
Scenarios for Health Expenditure in Poland
The report is a result of the Ageing, Health Status and Determinants of Health Expenditure (AHEAD) project within the EC 6th Framework programme. The objective of the research was to present the model of future health care system revenues and expenditures in Poland and to discuss projection assumptions and results. The projections are based on methodology adopted in the International Labour Organization (ILO) Social Budget model. The projection examines impact of demographic changes and changes in health status on future (up to 2050) health expenditures. Next to it, future changes in the labour market participation and their impact on the health care system revenues are examined. Impact of demography on the health care system financial balanced is examined in four different scenarios: baseline scenario, death-related costs scenario, different longevity scenario and diversified employment rates scenario. Results indicate dynamic and systematic increase of the health expenditures in the next 30 years. Afterwards the dynamics of this process is foreseen to slow down. Despite the increase of the revenues of the health care system, the system will face deficit in the close future. This holds for each scenario, however the size of the deficit differs depending on longevity and labour market participation assumptions. Results lead to a discussion on possible reforms of the health care system
Order in Spontaneous Behavior
Brains are usually described as input/output systems: they transform sensory input into motor output. However, the motor output of brains (behavior) is notoriously variable, even under identical sensory conditions. The question of whether this behavioral variability merely reflects residual deviations due to extrinsic random noise in such otherwise deterministic systems or an intrinsic, adaptive indeterminacy trait is central for the basic understanding of brain function. Instead of random noise, we find a fractal order (resembling Lévy flights) in the temporal structure of spontaneous flight maneuvers in tethered Drosophila fruit flies. Lévy-like probabilistic behavior patterns are evolutionarily conserved, suggesting a general neural mechanism underlying spontaneous behavior. Drosophila can produce these patterns endogenously, without any external cues. The fly's behavior is controlled by brain circuits which operate as a nonlinear system with unstable dynamics far from equilibrium. These findings suggest that both general models of brain function and autonomous agents ought to include biologically relevant nonlinear, endogenous behavior-initiating mechanisms if they strive to realistically simulate biological brains or out-compete other agents
Consensus Paper: Radiological Biomarkers of Cerebellar Diseases
Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. In the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine
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