Influence of the number of orientational domains on avalanche criticality in ferroelastic transitions.

We study the relationship between avalanche criticality and the number of orientational domains in ferroelastic transitions. To this end, we use a general Ginzburg-Landau model appropriate for displacive transitions of the square lattice. The model includes disorder as a quenched distribution of local transition temperatures. We focus on the square-to-rectangle and the square-to-oblique ferroelastic transitions, which have two and four orientational domains, respectively, which in turn determine the corresponding degeneracy of the ground state of the system. The phase transitions are driven by temperature under the assumption of a strict athermal behavior. That is, we assume that thermal fluctuations do not play any role. Numerical results are obtained using a purely relaxational dynamics, and it is shown that both the square-to-rectangle and the square-to-oblique transitions occur intermittently in the form of avalanches. Avalanche sizes and avalanche energies are found to display power-law distributions, which corroborates avalanche criticality. We compare and contrast the dependence of avalanche criticality on the number of orientational domains of the low-symmetry phase. It is found that the critical exponents depend on that number, in agreement with recent experimental results.

Characteristics and prognosis of patients admitted to a hospital emergency department for traumatic brain injury and with anticoagulant or antiplatelet treatment. / Características y pronóstico de pacientes ingresados en un servicio de urgencias hospitalario por traumatismo craneoencefálico y con tratamiento anticoagulante o antiagregante.

BACKGROUND AND OBJECTIVE: To determine mortality and complications of patients with traumatic brain injury (TBI) with antiplatelet or anticoagulant treatment in a hospital emergency department. MATERIALS AND METHODS: Study of hospital cohorts of the 243 patients who attended with pure TBI to the emergency service of the Arnau de Vilanova University Hospital in Lleida between June 1, 2015 and June 1, 2016. Sociodemographic, clinical and other variables related to clinical management were collected. Presence of complications and in-hospital mortality were registered at 24hours, at 48hours and one week after TBI. RESULTS: Overall, 50.2% of patients were men, with median age of 80.8years, and without CT-scan findings at admission in 62.3% of cases. A total of 14 patients died (5.8%). Overall mortality was associated with comorbidity, with knowledge loss and with fluctuation of the Glasgow comma scale in the acute process. Patients treated with anticoagulants (39.5%) or antiplatelet agents (33.3%) were older, with higher degree of dependency and more comorbidity, but did not present more complications. Without reaching statistical significance, higher mortality was observed during the first week in anticoagulated patients (7.3% vs 4.8%, P=.585) or with antiplatelet treatment (8.6% vs 4.3%, P=.241) with respect to those not treated. CONCLUSIONS: No worse results have been observed in number of complications in patients with TBI treated with anticoagulant or antiplatelet treatment, so clinical management seems appropriate. The higher mortality could be explained by the greater complexity of these patients. It would be necessary to carry out more studies, preferably prospective with follow-up after discharge, in order to establish causal mechanisms between clinical management and mortality or associated complications to TBI.

Thermodynamics of multicaloric effects in multiferroic materials: application to metamagnetic shape-memory alloys and ferrotoroidics.

We develop a general thermodynamic framework to investigate multicaloric effects in multiferroic materials. This is applied to the study of both magnetostructural and magnetoelectric multiferroics. Landau models with appropriate interplay between the corresponding ferroic properties (order parameters) are proposed for metamagnetic shape-memory and ferrotoroidic materials, which, respectively, belong to the two classes of multiferroics. For each ferroic property, caloric effects are quantified by the isothermal entropy change induced by the application of the corresponding thermodynamically conjugated field. The multicaloric effect is obtained as a function of the two relevant applied fields in each class of multiferroics. It is further shown that multicaloric effects comprise the corresponding contributions from caloric effects associated with each ferroic property and the cross-contribution arising from the interplay between these ferroic properties.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

Influence of elastic anisotropy on structural nanoscale textures.

We study the influence of elastic anisotropy on nanoscale precursor textures that exist in some shape-memory alloys and show that tweed occurs in the limit of high elastic anisotropy while a nanocluster phase-separated state occurs for values of anisotropy inhibiting the formation of martensite. These results are consistent with specific heat data, elastic constant measurements, and zero-field cooling or field cooling experiments in nonstoichiometric NiTi alloys.