Monte Carlo Simulations of Ultrathin Magnetic Dots

In this work we study the thermodynamic properties of ultrathin ferromagnetic dots using Monte Carlo simulations. We investigate the vortex density as a function of the temperature and the vortex structure in monolayer dots with perpendicular anisotropy and long-range dipole interaction. The interplay between these two terms in the hamiltonian leads to an interesting behavior of the thermodynamic quantities as well as the vortex density.Comment: 10 figure

Multiplicity fluctuations in hadron-hadron and nucleus-nucleus collisions and percolation of strings

We argue that recent NA49 results on multiparticle distributions and fluctuations, as a function of the number of participant nucleons, suggest that percolation plays an important role in particle production at high densities.Comment: 13 pages, 5 eps figures, late

Arbitrary bi-dimensional finite strain crack propagation

In the past two decades numerous numerical procedures for crack propagation have been developed. Lately, enrichment methods (either local, such as SDA or global, such as XFEM) have been applied with success to simple problems, typically involving some intersections. For arbitrary finite strain propagation, numerous difficulties are encountered: modeling of intersection and coalescence, step size dependence and the presence of distorted finite elements. In order to overcome these difficulties, an approach fully capable of dealing with multiple advancing cracks and self-contact is presented (see Fig.1). This approach makes use of a coupled Arbitrary Lagrangian-Eulerian method (ALE) and local tip remeshing. This is substantially less costly than a full remeshing while retaining its full versatility. Compared to full remeshing, angle measures and crack paths are superior. A consistent continuationbased linear control is used to force the critical tip to be exactly critical, while moving around the candidate set. The critical crack front is identified and propagated when one of the following criteria reaches a material limiting value: (i) the stress intensity factor; or (ii) the element-ahead tip stress. These are the control equations. The ability to solve crack intersection and coalescence problems is shown. Additionally, the independence from crack tip and step size and the absence of blade and dagger-shaped finite elements is observed. Classic benchmarks are computed leading to excellent crack path and load-deflection results, where convergence rate is quadratic

Radiocarbon and blue optically stimulated luminescence chronologies of the Oitavos consolidated dune (Western Portugal)

The dune of Oitavos, the underlying paleosol, and Helix sp. gastropod shells found within the paleosol were dated using a combination of radiocarbon and blue optically stimulated luminescence (OSL). The organic component of the paleosol produced a significantly older age (~20,000 cal BP) than the OSL age measurement (~15,000 yr), while 14C age measurements on the inorganic component and the gastropods produced ages of ~35,000 yr and ~34,000 yr, respectively. Rare-earth element analyses provide evidence that the gastropods incorporate geological carbonate, making them an unreliable indicator of the age of the paleosol. We propose that the 14C age of the small organic component of the paleosol is also likely to be unreliable due to incorporation of residual material. The OSL age measurement of the upper paleosol (~15,000 yr) is consistent with the age for the base of the dune (~14,500 yr). The younger OSL age for the top of the dune (~12,000 yr) suggests that it was built up by at least 2 sand pulses or that there was a remobilization of material at the top during its evolution, prior to consolidation

An SU(5)⊗\otimesZ_{13} Grand Unification Model

We propose an SU(5) grand unified model with an invisible axion and the unification of the three coupling constants which is in agreement with the values, at $M_Z$, of $\alpha$, $\alpha_s$, and $\sin^2\theta_W$. A discrete, anomalous, $Z_{13}$ symmetry implies that the Peccei-Quinn symmetry is an automatic symmetry of the classical Lagrangian protecting, at the same time, the invisible axion against possible semi-classical gravity effects. Although the unification scale is of the order of the Peccei-Quinn scale the proton is stabilized by the fact that in this model the standard model fields form the SU(5) multiplets completed by new exotic fields and, also, because it is protected by the $Z_{13}$ symmetry.Comment: 14 pages, more typos correcte

Distal Forearm Replantation Rehabilitation - Case Review

Actualmente, o desafio da reimplantação do membro superior pós-amputação tornou-se uma realidade alcançável e minuciosamente aperfeiçoada nas últimas décadas, e em permanente evolução. A opção cirúrgica de reimplantação deve ter em conta não apenas a análise exclusiva da viabilidade do reimplante, mas, fundamentalmente o seu potencial de recuperação funcional a longo prazo. Apresenta-se o caso clínico de um jovem de 18 anos, fumador, transferido do Hospital do Barreiro, vítima de acidente de trabalho, com traumatismo por corte, do qual resultou amputação distal do antebraço direito. O tempo de isquemia quente foi de 4horas, tendo sido submetido a cirurgia de reimplantação conjunta por Ortopedia e Cirurgia Plástica e Reconstrutiva (CPR) para reimplantação. Na sequência da cirurgia, foi precocemente referenciado a Medicina Física e de Reabilitação (MFR), realizando um programa de reabilitação funcional sequencial. Este trabalho visa enfatizar a importância do papel da MFR num precoce, criterioso e extenso programa de reabilitação, factor fundamental na recuperação funcional e prognóstico a longo prazo destas lesões e prevenção de complicações

Qualidade fisiológica da semente e estabelecimento de plantas de hortaliças no campo.

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