292 research outputs found
Dilepton production at HADES: theoretical predictions
Dileptons represent a unique probe for nuclear matter under extreme
conditions reached in heavy-ion collisions. They allow to study meson
properties, like mass and decay width, at various density and temperature
regimes. Present days models allow generally a good description of dilepton
spectra in ultra-relativistic heavy ion collision. For the energy regime of a
few GeV/nucleon, important discrepancies between theory and experiment, known
as the DLS puzzle, have been observed. Various models, including the one
developed by the T\"{u}bingen group, have tried to address this problem, but
have proven only partially successful. High precision spectra of dilepton
emission in heavy-ion reactions at 1 and 2 GeV/nucleon will be released in the
near future by the HADES Collaboration at GSI. Here we present the predictions
for dilepton spectra in C+C reactions at 1 and 2 GeV/nucleon and investigate up
to what degree possible scenarios for the in-medium modification of vector
mesons properties are accessible by the HADES experiment.Comment: 12 pages, 4 figures; submitted to Phys.Lett.
Salivary cortisol and α-amylase: subclinical indicators of stress as cardiometabolic risk
Currently, the potential for cardiovascular (CV) stress-induced risk is primarily based on the theoretical (obvious) side effects of stress on the CV system. Salivary cortisol and α-amylase, produced respectively by the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic-adrenomedullary (SAM) system during stress response, are still not included in the routine evaluation of CV risk and require additional and definitive validation. Therefore, this article overviews studies published between 2010 and 2015, in which salivary cortisol and α-amylase were measured as stress biomarkers to examine their associations with CV/CMR (cardiometabolic risk) clinical and subclinical indicators. A comprehensive search of PubMed, Web of Science and Scopus electronic databases was performed, and 54 key articles related to the use of salivary cortisol and α-amylase as subclinical indicators of stress and CV/CMR factors, including studies that emphasized methodological biases that could influence the accuracy of study outcomes, were ultimately identified. Overall, the biological impact of stress measured by salivary cortisol and α-amylase was associated with CV/CMR factors. Results supported the use of salivary cortisol and α-amylase as potential diagnostic tools for detecting stress-induced cardiac diseases and especially to describe the mechanisms by which stress potentially contributes to the pathogenesis and outcomes of CV diseases
Flow probe of symmetry energy in relativistic heavy-ion reactions
Flow observables in heavy-ion reactions at incident energies up to about 1
GeV per nucleon have been shown to be very useful for investigating the
reaction dynamics and for determining the parameters of reaction models based
on transport theory. In particular, the elliptic flow in collisions of
neutron-rich heavy-ion systems emerges as an observable sensitive to the
strength of the symmetry energy at supra-saturation densities. The comparison
of ratios or differences of neutron and proton flows or neutron and hydrogen
flows with predictions of transport models favors an approximately linear
density dependence, consistent with ab-initio nuclear-matter theories.
Extensive parameter searches have shown that the model dependence is comparable
to the uncertainties of existing experimental data. Comprehensive new flow data
of high accuracy, partly also through providing stronger constraints on model
parameters, can thus be expected to improve our knowledge of the equation of
state of asymmetric nuclear matter.Comment: 20 pages, 24 figures, review to appear in EPJA special volume on
nuclear symmetry energ
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