Shape-phase transitions in odd-mass γ\gamma-soft nuclei with mass A≈130A\approx 130

Quantum phase transitions between competing equilibrium shapes of nuclei with an odd number of nucleons are explored using a microscopic framework of nuclear energy density functionals and a particle-boson core coupling model. The boson Hamiltonian for the even-even core nucleus, as well as the spherical single-particle energies and occupation probabilities of unpaired nucleons, are completely determined by a constrained self-consistent mean-field calculation for a specific choice of the energy density functional and pairing interaction. Only the strength parameters of the particle-core coupling have to be adjusted to reproduce a few empirical low-energy spectroscopic properties of the corresponding odd-mass system. The model is applied to the odd-A Ba, Xe, La and Cs isotopes with mass $A\approx 130$, for which the corresponding even-even Ba and Xe nuclei present a typical case of $\gamma$-soft nuclear potential. The theoretical results reproduce the experimental low-energy excitation spectra and electromagnetic properties, and confirm that a phase transition between nearly spherical and $\gamma$-soft nuclear shapes occurs also in the odd-A systems.Comment: 13 pages, 15 figures, 9 table

Signatures of shape phase transitions in odd-mass nuclei

Quantum phase transitions between competing ground-state shapes of atomic nuclei with an odd number of protons or neutrons are investigated in a microscopic framework based on nuclear energy density functional theory and the particle-plus-boson-core coupling scheme. The boson-core Hamiltonian, as well as the single-particle energies and occupation probabilities of the unpaired nucleon, are completely determined by constrained self-consistent mean-field calculations for a specific choice of the energy density functional and paring interaction, and only the strength parameters of the particle-core coupling are adjusted to reproduce selected spectroscopic properties of the odd-mass system. We apply this method to odd-A Eu and Sm isotopes with neutron number $N \approx 90$, and explore the influence of the single unpaired fermion on the occurrence of a shape phase transition. Collective wave functions of low-energy states are used to compute quantities that can be related to quantum order parameters: deformations, excitation energies, E2 transition rates and separation energies, and their evolution with the control parameter (neutron number) is analysed.Comment: 15 pages, 13 figures; Accepted for publication in Phys. Rev.

Social behaviour of dolphins

Dupini (Delphinidae) su najraznovrsnija porodica morskih sisavaca. Spadaju u red kitova (Cetacea). Niz specifičnih prilagodbi na život u moru, vrlo razvijen mozak i izrazita inteligencija ih izdvaja od ostalih skupina sisavaca. Istraživanja socijalne evolucije dupina i usporedba s kopnenim sisavcima donijeli su suprotne zaključke, od kojih je jedan konvergencija s nekim kopnenim sisavcima, a drugi društveno ponašanje potpuno različito od ostatka životinjskog svijeta. Dupini žive u grupama koje, ovisno o vrsti i još nekim čimbenicima, variraju u veličini i dužini trajanja. Život u grupi ima brojne prednosti kao što su: brži i uspješniji lov, zaštita od predatora, obrana teritorija i veća mogućnost socijalnih interakcija koje uključuju parenje, brigu za mlade, te prijenos informacija i znanja. Do agresivnog ponašanja unutar grupe najčešće dolazi zbog kompeticije za hranu ili seksualnog partnera. Osim spolnih odnosa radi reprodukcije, često je homoseksualno ponašanje radi pokazivanja dominacije, ali i zajedništva. Seksualno ponašanje mladih može biti vježba ili samo dio igre. Dupini imaju izrazito dugi period brige za mlade, u kojem ih štite od predatora i uče vještinama lova potrebnim za samostalan život. Koriste najčešće akustičnu komunikaciju, koja može biti vokalna i ne-vokalna. Kod nekih vrsta primijećeni su specifični oblici vokalne komunikacije. Orke imaju različite dijalekte, a dobri dupini i još nekoliko vrsta potpisne zvižduke. Osim zajedničkog života unutar jedne vrste, mnogi dupini su viđeni u društvu drugih vrsta. Zbog složenih društvenih odnosa i sofisticiranih načina prenošenja znanja dupini se ubrajaju među najinteligentnije i najdruštvenije životinje.Dolphins (Delphinidae) are the most diversified family of all marine mammals. They belong to the order Cetacea. Many specific adaptations to aquatic life, a very developed brain and high intelligence single them out from other mammal species. The research of social evolution of dolphins and the comparison to land mammals brought contrary conclusions: one is convergence towards some land mammals, and the other is a social behaviour totally different from the rest of the animal world. Dolphins live in groups that, depending on species and on other factors, vary in size and duration. Life in a group has many advantages such as more successful hunting, defence from predators and protection of territory. It also provides greater possibility of social interactions which include mating, parental care and transfer of information and knowledge. Competition for food and sexual partners often leads to aggressive behaviour. Beside sexual intercourse, dolphins often have homosexual interactions in order to show dominance, or communion. Sexual behaviour of juveniles can be considered as a part of practice or just as a game. Dolphins have an exceptionally long period of parental care, in which they protect their infants from predators and teach them hunting techniques essential for independent life. They usually use acoustic communication, which can be vocal and non-vocal. In some species particularly developed forms of vocal communication were observed. Orcas have different dialects, bottlenose dolphins and some other species have signature whistles. Beside group life within one species, many dolphins were seen in company of other species. Because of their complex social relationships and sophisticated learning skills, dolphins are among the most intelligent and sociable animals

Effective numbers of charge carriers in doped graphene: The generalized Fermi liquid approach

The single-band current-dipole Kubo formula for the dynamical conductivity of heavily doped graphene from Kup\v{c}i\'{c} [Phys. Rev. B 91, 205428 (2015)] is extended to a two-band model for conduction $\pi$ electrons in lightly doped graphene. Using a posteriori relaxation-time approximation in the two-band quantum transport equations, with two different relaxation rates and one quasi-particle lifetime, we explain a seemingly inconsistent dependence of the dc conductivity $\sigma^{\rm dc}_{\alpha \alpha}$ of ultraclean and dirty lightly doped graphene samples on electron doping, in a way consistent with the charge continuity equation. It is also shown that the intraband contribution to the effective number of conduction electrons in $\sigma^{\rm dc}_{\alpha \alpha}$ vanishes at $T=0$ K in the ultraclean regime, but it remains finite in the dirty regime. The present model is shown to be consistent with a picture in which the intraband and interband contributions to $\sigma^{\rm dc}_{\alpha \alpha}$ are characterized by two different mobilities of conduction electrons, the values of which are well below the widely accepted value of mobility in ultraclean graphene. The dispersions of Dirac and $\pi$ plasmon resonances are reexamined to show that the present, relatively simple expression for the dynamical conductivity tensor can be used to study simultaneously single-particle excitations in the dc and optical conductivity and collective excitations in energy loss spectroscopy experiments.Comment: 13 pages, 11 figure

Random-phase approximation based on relativistic point-coupling models

The matrix equations of the random-phase approximation (RPA) are derived for the point-coupling Lagrangian of the relativistic mean-field (RMF) model. Fully consistent RMF plus (quasiparticle) RPA illustrative calculations of the isoscalar monopole, isovector dipole and isoscalar quadrupole response of spherical medium-heavy and heavy nuclei, test the phenomenological effective interactions of the point-coupling RMF model. A comparison with experiment shows that the best point-coupling effective interactions accurately reproduce not only ground-state properties, but also data on excitation energies of giant resonances.Comment: 24 pages, 4 figures, accepted for publication in Physical Review

Microscopic self-consistent description of induced fission dynamics: finite temperature effects

The dynamics of induced fission of $^{226}$Th is investigated in a theoretical framework based on the finite-temperature time-dependent generator coordinate method (TDGCM) in the Gaussian overlap approximation (GOA). The thermodynamical collective potential and inertia tensor at temperatures in the interval $T=0 - 1.25$ MeV are calculated using the self-consistent multidimensionally constrained relativistic mean field (MDC-RMF) model, based on the energy density functional DD-PC1. Pairing correlations are treated in the BCS approximation with a separable pairing force of finite range. Constrained RMF+BCS calculations are carried out in the collective space of axially symmetric quadrupole and octupole deformations for the asymmetric fissioning nucleus $^{226}$Th. The collective Hamiltonian is determined by the temperature-dependent free energy surface and perturbative cranking inertia tensor, and the TDGCM+GOA is used to propagate the initial collective state in time. The resulting charge and mass fragment distributions are analyzed as functions of the internal excitation energy. The model can qualitatively reproduce the empirical triple-humped structure of the fission charge and mass distributions already at $T=0$, but the precise experimental position of the asymmetric peaks and the symmetric-fission yield can only be accurately reproduced when the potential and inertia tensor of the collective Hamiltonian are determined at finite temperature, in this particular case between $T=0.75$ MeV and $T=1$ MeV.Comment: 9 pages, 7 figure

Parental Quality of Life in the Framework of Paediatric Chronic Gastrointestinal Disease

Chronic gastrointestinal diseases, such as inflammatory bowel disease (IBD) and celiac disease (CD), might have impact not only on the affected child but also on their parents since inside the family framework, a change in each member may have influence on the whole system. The aim of this study was to test the hypothesis that parents whose children have IBD or CD will have a lower quality of life (QoL) compared to parents of healthy children, as well as that lower QoL will be found among parents who perceive lower health related quality of life (HRQOL) of their child. 55 parents of children with IBD, 49 of CD and 53 parents of healthy children were included in the study. Children were aged 7–18 years. In order to measure parental QoL, a Croatian version of the WHOQOL-BREF questionnaire was administered, with four domains: physical health, psychological health, social relationship and environment. The Total QoL was calculated as a sum of all domain items. The parent-proxy report of children’s HRQOL, PedsQLTM 4.0 Generic Core Scales was used.Main result shows that parents of children with IBD report a significantly lower psychological health, compared to parents of other children, and significantly lower physical health compared to parents of healthy children. Among parents of children with CD and parents of healthy children, better parental Total QoL was significantly correlated with better parental report of children’s HRQOL, while for parents of children with IBD those associations were not found. Results of study show association between presence of the disease in offspring with poorer parental QoL, thus highlight the importance of supporting not only children with chronic disease but also involving their parents in psychosocial interventions, as well as supporting the patient’s association groups which gather both children with chronic disease and their parents