Determination of the stiffness of the nuclear symmetry energy from isospin diffusion

With an isospin- and momentum-dependent transport model, we find that the degree of isospin diffusion in heavy ion collisions at intermediate energies is affected by both the stiffness of the nuclear symmetry energy and the momentum dependence of the nucleon potential. Using a momentum dependence derived from the Gogny effective interaction, recent experimental data from NSCL/MSU on isospin diffusion are shown to be consistent with a nuclear symmetry energy given by $E_{\text{sym}}(\rho)\approx 31.6(\rho /\rho_{0})^{1.05}$ at subnormal densities. This leads to a significantly constrained value of about -550 MeV for the isospin-dependent part of the isobaric incompressibility of isospin asymmetric nuclear matter.Comment: 4 pages, 4 figures, 1 table, revised version, to appear in PR

A contact-based social network of lizards is defined by low genetic relatedness among strongly connected individuals

Author version made available in accordance with the Publisher's policy, after an embargo period of 24 months from the date of publication. © 2015. Licensed under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Social organization is widespread; even largely solitary species must organize themselves to enable contacts with mates and reduce competition with conspecifics. Although the forms of social structure can be subtle in solitary species, understanding the factors that influence them may be important for understanding how different forms of social organization evolved. We investigated the influence of genetic relatedness and spatial structure on social associations in a solitary living Australian scincid lizard, Tiliqua rugosa. We derived the genetic relatedness of 46 lizards from analysis of genotypes at 15 microsatellite DNA loci, and described social networks from GPS locations of all the lizards every 10 min for 81 days during their main activity period of the year. We found that connected male dyads were significantly more related than expected by chance, whereas connected male–female and female–female dyads had lower relatedness than expected. Among neighbouring male–male and male–female dyads, the strongest social relationships were between lizards that were the least related. Explanations of this pattern may include the avoidance of inbreeding in male–female dyads, or the direction of aggressive behaviour towards less related individuals in male–male dyads. Observed social associations (inferred through synchronous spatial proximity) were generally lower than expected from null models derived from home range overlap, and many close neighbours did not make social contact. This supports our hypothesis for the presence of deliberate avoidance between some neighbouring individuals. We suggest that lizards can discriminate between different levels of relatedness in their neighbours, directing their social interactions towards those that are less related. This highlights differences in how social associations are formed between species that are solitary (where associations form between unrelated conspecifics) and species that maintain stable social groups structured by kinship.Our sleepy lizard research was funded by the Australian Research Council

Should the visceral peritoneum at the bladder flap closed at caesarean sections a post partum sonographic and clinical assessment?

Objective. To compare cesarean section (CS) using open or closed visceral peritoneum of the bladder flap (BF) in relation to fluid collection in vesico-uterine space (VUS) by ultrasound (US) and clinical outcome. Material and methods. A prospective cohort of repeat CS in 474 in advanced first and second stage of labor was studied. All women underwent a Misgav Ladach CS, in local combined anesthesia. These were divided into two groups by surgical management of the BF at the time of CS: Group I (n?262), with visceral peritoneum left open and Group II (n?212), with visceral peritoneum closed. An US check for the fluid collections in the VUS was done in the third post-operative day. The two groups were also clinically compared for: intra-operative estimated blood loss, the need for post-CS pain killers, febrile morbidity and duration of hospital stay. Results. Visceral peritoneum (VP) closure resulted in a significant increase blood collections in the VUS (p50.05). VP closure resulted in a significantly higher morbidity in all the following parameters. Rate of BFHs, post-operative fever, need for post-operative analgesia, require antibiotic administration and prolonged hospitalisation (p50.05). Conclusions. VP suturing of women requiring CS for dystocia is associated to increased rate of blood collection in the VUS, which could possibly explain the higher rate of puerperal complications in these patients. These data clearly indicate that suturing the VP of the BF in women undergoing CS for dystocia is contraindicated. This data could be probably extrapolated to all cesarean deliveries

Instrumentação e processamento de dados para avaliação de aumento de escala em reator do tipo air-lift.

Entrada correta: FARINAS, C. S

Surface Incompressibility from Semiclassical Relativistic Mean Field Calculations

By using the scaling method and the Thomas-Fermi and Extended Thomas-Fermi approaches to Relativistic Mean Field Theory the surface contribution to the leptodermous expansion of the finite nuclei incompressibility has been self-consistently computed. The validity of the simplest expansion, which contains volume, volume-symmetry, surface and Coulomb terms, is examined by comparing it with self-consistent results of the finite nuclei incompressibility for some currently used non-linear sigma-omega parameter sets. A numerical estimate of higher-order contributions to the leptodermous expansion, namely the curvature and surface-symmetry terms, is made.Comment: 18 pages, REVTeX, 3 eps figures, changed conten

A microscopic estimate of the nuclear matter compressibility and symmetry energy in relativistic mean-field models

The relativistic mean-field plus RPA calculations, based on effective Lagrangians with density-dependent meson-nucleon vertex functions, are employed in a microscopic analysis of the nuclear matter compressibility and symmetry energy. We compute the isoscalar monopole and the isovector dipole response of $^{208}$Pb, as well as the differences between the neutron and proton radii for $^{208}$Pb and several Sn isotopes. The comparison of the calculated excitation energies with the experimental data on the giant monopole resonance in $^{208}$Pb, restricts the nuclear matter compression modulus of structure models based on the relativistic mean-field approximation to $K_{\rm nm}\approx 250 - 270$ MeV. The isovector giant dipole resonance in $^{208}$Pb, and the available data on differences between neutron and proton radii, limit the range of the nuclear matter symmetry energy at saturation (volume asymmetry) to 32 MeV $\leq a_4 \leq$ 36 MeV.Comment: 16 pages, 6 figure

Observation of single collisionally cooled trapped ions in a buffer gas

Individual Ba ions are trapped in a gas-filled linear ion trap and observed with a high signal-to-noise ratio by resonance fluorescence. Single-ion storage times of ~5 min (~1 min) are achieved using He (Ar) as a buffer gas at pressures in the range 8e-5 - 4e-3 torr. Trap dynamics in buffer gases are experimentally studied in the simple case of single ions. In particular, the cooling effects of light gases such as He and Ar and the destabilizing properties of heavier gases such as Xe are studied. A simple model is offered to explain the observed phenomenology.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. A. Minor text and figure change

A unique spinodal region in asymmetric nuclear matter

Asymmetric nuclear matter at sub-saturation densities is shown to present only one type of instabilities. The associated order parameter is dominated by the isoscalar density and so the transition is of liquid-gas type. The instability goes in the direction of a restoration of the isospin symmetry leading to a fractionation phenomenon. These conclusions are model independent since they can be related to the general form of the asymmetry energy. They are illustrated using density functional approaches.Comment: 4 pages, 5 figures, to appear in Phys. Rev.