On the Integrability and Chaos of an N=2 Maxwell-Chern-Simons-Higgs Mechanical Model

We apply different integrability analysis procedures to a reduced (spatially homogeneous) mechanical system derived from an off-shell non-minimally coupled N=2 Maxwell-Chern-Simons-Higgs model that presents BPS topological vortex excitations, numerically obtained with an ansatz adopted in a special - critical coupling - parametric regime. As a counterpart of the regularity associated to the static soliton-like solution, we investigate the possibility of chaotic dynamics in the evolution of the spatially homogeneous reduced system, descendant from the full N=2 model under consideration. The originally rich content of symmetries and interactions, N=2 susy and non-minimal coupling, singles out the proposed model as an interesting framework for the investigation of the role played by (super-)symmetries and parametric domains in the triggering/control of chaotic behavior in gauge systems. After writing down effective Lagrangian and Hamiltonian functions, and establishing the corresponding canonical Hamilton equations, we apply global integrability Noether point symmetries and Painleveproperty criteria to both the general and the critical coupling regimes. As a non-integrable character is detected by the pair of analytical criteria applied, we perform suitable numerical simulations, as we seek for chaotic patterns in the system evolution. Finally, we present some Comments on the results and perspectives for further investigations and forthcoming communications.Comment: 18 pages, 5 figure

Phenotypic variation of Fucus ceranoides, F. spiralis and F. vesiculosus in a temperate coast (NW Portugal)

Brown algae includes several species of Fucus, reported both in the tidal and intertidal zones of cold and temperate regions. Environmental parameters induce wide biological variability in intertidal algae, manifested by alterations at several levels, and this has lead to the failure of some reports to discriminate between closely related taxa, particularly Fucus species. As the genus Fucus is widely represented on the Portuguese coast, the biometric parameters of three species (F spiralis, F. vesiculosus and F. ceranoides) collected from several sampling sites in Portugal, were studied over twelve months. Environmental parameters (water temperature, pH, dissolved oxygen, salinity, phosphorous - orthophosphate and total phosphate, nitrate, nitrite and ammonia) were analysed. The objective of this study was to understand how environmental parameters influence and establish morphological variation in the Fucus species. Canonical Correspondence Analysis (CCA), which helps define the relationships between morphological and physicochemical variables, was carried out for each species in order to determine which physicochemical parameter most affects the morphology of Fucus. The variable biometric that strongly separates the three Fucus species is the number of receptacles per thalli, and this parameter was highly correlated with F ceranoides. The two others species were distinguished principally by the height of the bigger receptacle, the midrib height of the holdfast, the height of the smaller receptacle, and the midrib width of the holdfast. The CCA analysis also showed that the dominant factor influencing morphometric parameters was salinity, being always in strict correlation with water temperatures and orthophosphate. For F ceranoides, physicochemical parameters (especially a higher concentration of orthophosphate and lower salinity) seem to influence morphological parameters, mainly in the raised number of receptacles per thalli. Salinity was the most important environmental parameter to distinguishing F spiralis and F vesiculosus in northern Portugal.FCT/CONTROL project - PDCTM/C/MAR/15266/199

Criticality in the 2+1-dimensional compact Higgs model and fractionalized insulators

We use a novel method of computing the third moment M_3 of the action of the 2+1-dimensional compact Higgs model in the adjoint representation with q=2 to extract correlation length and specific heat exponents nu and alpha, without invoking hyperscaling. Finite-size scaling analysis of M_3 yields the ratio (1+alpha)/nu and 1/nu separately. We find that alpha and nu vary along the critical line of the theory, which however exhibits a remarkable resilience of Z_2 criticality. We propose this novel universality class to be that of the quantum phase transition from a Mott-Hubbard insulator to a charge-fractionalized insulator in two spatial dimensions.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let

Post-partum anoestrus in Anglo-Nubian and Saanen goats raised in semi-arid of North-eastern Brazil.

The aim of this study was to verify the length of post-partum anoestrus (PPA) in Anglo-Nubian and Saanen goats raised in North-eastern Brazi

The relation between the erythrocyte nitric oxide and hemorheological parameters

© 2006 – IOS Press and the authors. All rights reservedWe stimulated human erythrocytes obtained from patients with hypercholesterolemia (HC; n = 42), renal transplantation (RT; n = 18) and hypertension (HT; n = 10) with acetylcholine (ACh 10 μM) and measured the amperometric NO production, comparing with the NO levels achieved on erythrocytes of healthy persons (n = 27). We also measured the hemoglobin, hematocrit, erythrocyte aggregation, erythrocyte deformability, plasma viscosity and fibrinogen concentration from human blood samples. The erythrocytes NO levels were of 2.5 ± 0.7 nM (P = 0.038, HC), 2.4 ± 1.1 nM (RT) and 2.2 ± 0.8 nM (HT) against the 2.0 ± 0.8 nM for the control groups. For each group and at each shear stress value, the erythrocytes deformability decreases with the increase of the NO concentration after ACh stimulation. We observed a significant increase of the control values on the erythrocyte aggregation results on each patient group. Besides the lower erythrocyte deformability obtained on HC, RT and HT blood samples, the erythrocytes produced higher NO levels after ACh stimulation than the healthy ones. The power of erythrocyte hemorheological behaviour could be compensated by the NO production at the presence of acetylcholine. We can hypothesises that cholinergic drugs could be used as co-adjuvants of specific therapeutics compounds on these studied diseases.This work was supported by “Fundação para a Ciência e Tecnologia”, Portugal

Spin Josephson effect in ferromagnet/ferromagnet tunnel junctions

We consider the tunnel spin current between two ferromagnetic metals from a perspective similar to the one used in superconductor/superconductor tunnel junctions. We use fundamental arguments to derive a Josephson-like spin tunnel current $I_J^{\rm spin}\propto\sin(\theta_1-\theta_2)$. Here the phases are associated with the planar contribution to the magnetization, $\sim e^{i\theta}$. The crucial step in our analysis is the fact that the $z$-component of the spin is canonically conjugate to the phase of the planar contribution: $[\theta,S^z]=i$. This is analogous to the commutation relation $[\phi,N]=i$ in superconductors, where $\phi$ is the phase associated to the superconducting order parameter and $N$ is the Cooper pair number operator. We briefly discuss the experimental consequences of our theoretical analysis.Comment: LaTex, seven pages, no figures; version to appear in Europhys. Lett.; in order to make room for a more extended microscopic analysis, the phenomenological discussion contained in v2 was remove

Portuguese Adaptation of Students Engagement in Schools International Scale (SESIS)

The importance of student’s engagement has been recently pointed out in research. However, there has been a lack of engagement assessment instrument, pertaining psychometric qualities. Objective: This paper presents the Portuguese adaptation of the “Student’s Engagement in School International Scale” (SESIS), drawn up from a12 countries international study (Lam et al., 2012; Lam et al., in press). Method: Psychometric properties of this scale were examined with data from 685 students from different grades (6th, 7th, 9th and 10th), from both sexes, and different regions of the country. Results: Factorial analysis of the results, with varimax rotation, lead to three different factors which explain 50.88% of the variance. The scale integrates the original 33 items, and cognitive, affective and behavioural dimensions. For the external validity study, the relationship between student’s engagement in school results and other school variables — academic performance, self-concept — was considered, and significant relations were observed, as expected. Conclusion: The data presented highlights the qualities of SESIS, as well as its usefulness for research purposes. Suggestion: It is suggested the investigation of the extension of SESIS’s three-dimensionality, in future studiesKeywords: Innovation, technology, research projects, etc. [Arial 10-point, justified alignment]