Statistical models of mixtures with a biaxial nematic phase

We consider a simple Maier-Saupe statistical model with the inclusion of disorder degrees of freedom to mimic the phase diagram of a mixture of rod-like and disc-like molecules. A quenched distribution of shapes leads to the existence of a stable biaxial nematic phase, in qualitative agreement with experimental findings for some ternary lyotropic liquid mixtures. An annealed distribution, however, which is more adequate to liquid mixtures, precludes the stability of this biaxial phase. We then use a two-temperature formalism, and assume a separation of relaxation times, to show that a partial degree of annealing is already sufficient to stabilize a biaxial nematic structure.Comment: 11 pages, 2 figure

Antiferromagnetic spherical spin-glass model

We study the thermodynamic properties and the phase diagrams of a multi-spin antiferromagnetic spherical spin-glass model using the replica method. It is a two-sublattice version of the ferromagnetic spherical p-spin glass model. We consider both the replica-symmetric and the one-step replica-symmetry-breaking solutions, the latter being the most general solution for this model. We find paramagnetic, spin-glass, antiferromagnetic and mixed or glassy antiferromagnetic phases. The phase transitions are always of second order in the thermodynamic sense, but the spin-glass order parameter may undergo a discontinuous change.Comment: 12 pages, 6 figure

Deformation of Crystals: Connections with Statistical Physics

We give a bird's-eye view of the plastic deformation of crystals aimed at the statistical physics community, as well as a broad introduction to the statistical theories of forced rigid systems aimed at the plasticity community. Memory effects in magnets, spin glasses, charge density waves, and dilute colloidal suspensions are discussed in relation to the onset of plastic yielding in crystals. Dislocation avalanches and complex dislocation tangles are discussed via a brief introduction to the renormalization group and scaling. Analogies to emergent scale invariance in fracture, jamming, coarsening, and a variety of depinning transitions are explored. Dislocation dynamics in crystals challenge nonequilibrium statistical physics. Statistical physics provides both cautionary tales of subtle memory effects in nonequilibrium systems and systematic tools designed to address complex scale-invariant behavior on multiple length scales and timescales

El modelo de Educación Deportiva y la orientación. Efectos en la satisfacción con la vida, las inteligencias múltiples, las necesidades psicológicas básicas y las percepciones sobre el modelo de los adolescentes

The aim of this study was to assess the effects of a Sport Education (SE) model-based teaching unit through orienteering on grade 9 (14-17 years) students’ life satisfaction, multiple intelligences, basic psychological needs and curricular model perceptions.81 students (Mage = 14.62; SD = .80) allocated in three intact groups from a high-school in Region of Murcia (Spain), took part in this unit. Based on a quasi-experimental design (pretest-posttest measures), data were collected from interviews (teacher perspective) and both quantitative and qualitative questionnaires (student perspective). Significant improvements were obtained on the development of the three main SE goals (competency, literacy and enthusiasm), whereas no significant changes were found on life satisfaction and multiple intelligences. Findings confirmed orienteering as a suitable content to be taught according through the pedagogical principles of SE model.Likewise, results showed its benefits on the development of the objectives this pursues.Se examinaron los efectos de una unidad didáctica de orientación deportiva (OD) basada en el modelo de Educación Deportiva (ED) sobre la satisfacción con la vida, las inteligencias múltiples, las necesidades psicológicas básicas y las percepciones del modelo en estudiantesde tercer curso de educación secundaria. La muestra estuvo comprendida por 81 estudiantes (M de edad = 14.62; DT = .80) distribuidos en tres grupos naturales, pertenecientes a un instituto ubicado en la Región de Murcia (España). A partir de un diseño cuasi-experimental (medidas pretest-postest), se recabaron datos mediante entrevistas (percepción docente), cuestionarios cuantitativos y cualitativos (percepción discente). Se obtuvieronmejoras significativas en el desarrollo de los tres objetivos que persigue el modelo (competencia, cultura deportiva y entusiasmo), al tiempo queno se revelaron cambios significativos en la satisfacción con la vida y en las inteligencias múltiples. Los resultados constatan a la OD como contenido apto para ser abordado mediante los principios del modelo de ED y respaldansu eficaciarespecto a los objetivos que este últimopersigue

Quantitative Trait Loci Involved in Sex Determination and Body Growth in the Gilthead Sea Bream (Sparus aurata L.) through Targeted Genome Scan

Among vertebrates, teleost fish exhibit a considerably wide range of sex determination patterns that may be influenced by extrinsic parameters. However even for model fish species like the zebrafish Danio rerio the precise mechanisms involved in primary sex determination have not been studied extensively. The zebrafish, a gonochoristic species, is lacking discernible sex chromosomes and the sex of juvenile fish is difficult to determine. Sequential protandrous hermaphrodite species provide distinct determination of the gender and allow studying the sex determination process by looking at the mechanism of sex reversal. This is the first attempt to understand the genetic basis of phenotypic variation for sex determination and body weight in a sequential protandrous hermaphrodite species, the gilthead sea bream (Sparus aurata). This work demonstrates a fast and efficient strategy for Quantitative Trait Loci (QTL) detection in the gilthead sea bream, a non-model but target hermaphrodite fish species. Therefore a comparative mapping approach was performed to query syntenies against two other Perciformes, the European sea bass (Dicentrarchus labrax), a gonochoristic species and the Asian sea bass (Lates calcarifer) a protandrous hermaphrodite. In this manner two significant QTLs, one QTL affecting both body weight and sex and one QTL affecting sex, were detected on the same linkage group. The co-segregation of the two QTLs provides a genomic base to the observed genetic correlation between these two traits in sea bream as well as in other teleosts. The identification of QTLs linked to sex reversal and growth, will contribute significantly to a better understanding of the complex nature of sex determination in S. aurata where most individuals reverse to the female sex at the age of two years through development and maturation of the ovarian portion of the gonad and regression of the testicular area. [Genomic sequences reported in this manuscript have been submitted to GenBank under accession numbers HQ021443–HQ021749.

Deformation of Crystals: Connections with Statistical Physics

We give a bird's-eye view of the plastic deformation of crystals aimed at the statistical physics community, as well as a broad introduction to the statistical theories of forced rigid systems aimed at the plasticity community. Memory effects in magnets, spin glasses, charge density waves, and dilute colloidal suspensions are discussed in relation to the onset of plastic yielding in crystals. Dislocation avalanches and complex dislocation tangles are discussed via a brief introduction to the renormalization group and scaling. Analogies to emergent scale invariance in fracture, jamming, coarsening, and a variety of depinning transitions are explored. Dislocation dynamics in crystals challenge nonequilibrium statistical physics. Statistical physics provides both cautionary tales of subtle memory effects in nonequilibrium systems and systematic tools designed to address complex scale-invariant behavior on multiple length scales and timescales

Lifelong testicular differentiation in Pleurodeles waltl (Amphibia, Caudata)

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