4,655 research outputs found
Retardation of Particle Evaporation from Excited Nuclear Systems Due to Thermal Expansion
Particle evaporation rates from excited nuclear systems at equilibrium matter
density are studied within the Harmonic-Interaction Fermi Gas Model (HIFGM)
combined with Weisskopf's detailed balance approach. It is found that thermal
expansion of a hot nucleus, as described quantitatively by HIFGM, leads to a
significant retardation of particle emission, greatly extending the validity of
Weisskopf's approach. The decay of such highly excited nuclei is strongly
influenced by surface instabilities
One-body energy dissipation in fusion reaction from mean-field theory
Information on dissipation in the entrance channel of heavy-ion collisions is
extracted by macroscopic reduction procedure of Time-Dependent Hartree-Fock
theory. The method gives access to a fully microscopic description of the
friction coefficient associated with transfer of energy from the relative
motion towards intrinsic degrees of freedom. The reduced friction coefficient
exhibits a universal behavior, i.e. almost independent of systems investigated,
whose order of magnitude is comparable with the calculations based on linear
response theory. Similarly to nucleus-nucleus potential, especially close to
the Coulomb barrier, there are sizable dynamical effects on the magnitude and
form factor of friction coefficient.Comment: 7 pages, 10 figure
Probing the Concept of Statistical Independence of Intermediate-Mass Fragment Production in Heavy-Ion Collisions
It is found that the total IMF-transverse-energy (E_t) spectra in multi-IMF
events are well represented by synthetic spectra obtained by folding of the
single-IMF spectrum. Using the experimental IMF multiplicity distribution, the
observed trends in the IMF multiplicity distribution for fixed values of E_t
are reproduced. The synthetic distributions show binomial reducibility and
Arrhenius-like scaling, similar to that reported in the literature. Similar
results are obtained when the above folding-type synthesis is replaced with one
based on mixing events with different IMF multiplicities. For statistically
independent IMF emission, the observed binomial reducibility and Arrhenius-type
scaling are merely reflections of the shape of the single-IMF transverse-energy
spectrum. Hence, a valid interpretation of IMF distributions in terms of a
particular production scenario has to explain independently the observed shape
of the single-IMF E_t spectrum.Comment: 13 pages with 8 figur
Detection of vancomycin resistances in enterococci within 3 1/2 Hours
Vancomycin resistant enterococci (VRE) constitute a challenging problem in health care institutions worldwide. Novel methods to rapidly identify resistances are highly required to ensure an early start of tailored therapy and to prevent further spread of the bacteria. Here, a spectroscopy-based rapid test is presented that reveals resistances of enterococci towards vancomycin within 3.5 hours. Without any specific knowledge on the strain, VRE can be recognized with high accuracy in two different enterococci species. By means of dielectrophoresis, bacteria are directly captured from dilute suspensions, making sample preparation very easy. Raman spectroscopic analysis of the trapped bacteria over a time span of two hours in absence and presence of antibiotics reveals characteristic differences in the molecular response of sensitive as well as resistant Enterococcus faecalis and Enterococcus faecium. Furthermore, the spectroscopic fingerprints provide an indication on the mechanisms of induced resistance in VRE
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