Roughening and preroughening in the six vertex model with an extended range of interaction

We study the phase diagram of the BCSOS model with an extended interaction range using transfer matrix techniques, pertaining to the (100) surface of single component fcc and bcc crystals. The model shows a 2x2 reconstructed phase and a disordered flat phase. The deconstruction transition between these phases merges with a Kosterlitz-Thouless line, showing an interplay of Ising and Gaussian degrees of freedom. As in studies of the fully frustrated XY model, exponents deviating from Ising are found. We conjecture that tri-critical Ising behavior may be a possible explanation for the non-Ising exponents found in those models.Comment: 25 pages in RevTeX 3.0, seven uuencoded postscript figures, REPLACED because of submission error (figures were not included

An observation on the experimental measurement of dislocation density

The common practice of ignoring the elastic strain gradient in measurements of geometrically necessary dislocation (GND) density is critically examined. It is concluded that the practice may result in substantial errors. Our analysis points to the importance of spatial variations of the elastic strain field in relation to its magnitude in inferring estimates of dislocation density from measurements

Eléments pour une Politique du Volontariat

This report describes the voluntary sector in Belgium and abroad. It describes improvements that could be made to the juridical situation that governs the third sector. Additionally, it acknowledges the societal contribution of volunteers and the non-profit organisations for which they work

Dynamical transitions in incommensurate systems

In the dynamics of the undamped Frenkel-Kontorova model with kinetic terms, we find a transition between two regimes, a floating incommensurate and a pinned incommensurate phase. This behavior is compared to the static version of the model. A remarkable difference is that, while in the static case the two regimes are separated by a single transition (the Aubry transition), in the dynamical case the transition is characterized by a critical region, in which different phenomena take place at different times. In this paper, the generalized angular momentum we have previously introduced, and the dynamical modulation function are used to begin a characterization of this critical region. We further elucidate the relation between these two quantities, and present preliminary results about the order of the dynamical transition.Comment: 7 pages, 6 figures, file 'epl.cls' necessary for compilation provided; subm. to Europhysics Letter

Is surface melting a surface phase transition?

Monte Carlo or Molecular Dynamics calculations of surfaces of Lennard-Jones systems often indicate, apart from a gradual disordering of the surface called surface melting, the presence of a phase transition at the surface, but cannot determine the nature of the transition. In the present paper, we provide for a link between the continuous Lennard-Jones system and a lattice model. We apply the method for the (001) surface of a Lennard-Jones fcc structure pertaining to Argon. The corresponding lattice model is a Body Centered Solid on Solid model with an extended range of interaction, showing in principle rough, flat and disordered flat phases. We observe that entropy effects considerably lower the strength of the effective couplings between the atoms. The Argon (001) face is shown to exhibit a phase transition at T=70.5 +- 0.5 K, and we identify this transition as roughening. The roughening temperature is in good correspondence with experimental results for Argon.Comment: 17 pages REVTeX, 14 uuencoded postscript figures appende

Food policy volatility and EU policies

Changes in global food prices have affected EU producers and consumers and have triggered policy reactions through the EU's political process. In particular, the EU and member states responded by social policies to protect their consumers, attempts to regulate 'speculation' on agricultural commodities, revisions of sustainability requirements for biofuels, international development and food aid, and changes in the EU's Common Agricultural Policy (CAP). With the exception of biofuel regulations, policy changes have been relatively limited and the effects on global food markets minor. The reasons are that the impact of global price volatility on EU consumers has been limited and the link between the CAP and the world market is much smaller than it was twenty years ago

Spatial decay in transient heat conduction for general elongated regions

Zanaboni's procedure for establishing Saint-Venant's principle is ex- tended to anisotropic homogeneous transient heat conduction on regions that are successively embedded in each other to become indefinitely elon- gated. No further geometrical restrictions are imposed. The boundary of each region is maintained at zero temperature apart from the common surface of intersection which is heated to the same temperature assumed to be of bounded time variation. Heat sources are absent. Subject to these conditions, the thermal energy, supposed bounded in each region, becomes vanishingly small in those parts of the regions suficiently remote from the heated common surface. As with the original treatment, the proof involves certain monotone bounded sequences, and does not depend upon differential inequalities or the maximum principle. A definition is presented of an elongated region.Peer ReviewedPostprint (author's final draft

Spatial behaviour in thermoelastostatic cylinders of indefinitely increasing cross-section

The final publication is available at Springer via http://dx.doi.org/10.1007/s10659-015-9523-8Alternative growth and decay estimates, reminiscent of the classical Phragmén-Lindelöf principle, are derived for a linearised thermoelastic body whose plane crosssections increase unboundedly with respect to a given direction. The proof uses a modified Poincaré inequality to construct a differential inequality for a weighted linear combination of the cross-sectional mechanical and thermal energy fluxes. Decay estimates are deduced also for the cross-sectional mean square measures of the displacement and temperature. An explicit upper bound in terms of base data is established for the amplitude occurring in the decay estimates.Peer ReviewedPostprint (author’s final draft

Treatment of Pelvic Ring Fractures with Pelvic Circumferential Compression Divices

__Abstract__ High energy pelvic fractures are life-threatening injuries and are among the most challenging injuries to treat. Complete evaluation of the patient with a high energy pelvic fracture is essential because this is rarely an isolated injury. Most deaths in patients with pelvic fractures are not caused by the pelvic fracture itself but are linked to associated injuries. The same forces that lead to disruption of the pelvic ring are frequently associated with abdominal, head, and thoracic injury. Bleeding remains the leading cause of death in patients with pelvic fractures but is rarely the only cause of blood loss in the patient with multiple injuries. In addition to bleeding from the fracture surfaces (i.e., cancellous bone) bleeding from the venous plexus and arterial lesions in a patient with a pelvic ring fracture potentially causes serious complications. These anatomical structures that are at risk are discussed into more detail in the pelvic anatomy section below