The Computer Industry in Belgium.

Industry;

Properties of Stationary Nonequilibrium States in the Thermostatted Lorentz Gas I: the One Particle System

We study numerically and analytically the properties of the stationary state of a particle moving under the influence of an electric field \bE in a two dimensional periodic Lorentz gas with the energy kept constant by a Gaussian thermostat. Numerically the current appears to be a continuous function of \bE whose derivative varies very irregularly, possibly in a discontinuous manner. We argue for the non differentibility of the current as a function of \bE utilizing a symbolic description of the dynamics based on the discontinuities of the collision map. The decay of correlations and the behavior of the diffusion constant are also investigated

Sociodemographic Determinants for Oral Health Risk Profiles

The present study aimed to explore the association between caries risk profiles and different sociodemographic factors . The study sample (n = 104) was randomly selected within an urban population in Flanders, Belgium. Caries risk was assessed by anamnesis, clinical examination, salivary tests, and a questionnaire. Age, gender, and socio-economic status were extracted from social insurance data files. Social indicators were “occupational status,” “being entitled to the increased allowance for health care interventions” and having access to the “Maximum Bill” (MAF), initiatives undertaken to protect deprived families. In the bivariate analysis there were significant differences in risk profiles between occupational groups (P < .001), between entitled and non-entitled individuals to the increased allowance (P = .02), and between access or no-access to the MAF (P < .01). The multiple logistic model showed a significantly higher chance of being in the low risk group for individuals with no-access to the MAF compared to those with access (OR:14.33–95% C.I. 2.14–95.84)

Properties of Stationary Nonequilibrium States in the Thermostatted Periodic Lorentz Gas II: The many point particles system

We study the stationary nonequilibrium states of N point particles moving under the influence of an electric field E among fixed obstacles (discs) in a two dimensional torus. The total kinetic energy of the system is kept constant through a Gaussian thermostat which produces a velocity dependent mean field interaction between the particles. The current and the particle distribution functions are obtained numerically and compared for small E with analytic solutions of a Boltzmann type equation obtained by treating the collisions with the obstacles as random independent scatterings. The agreement is surprisingly good for both small and large N. The latter system in turn agrees with a self consistent one particle evolution expected to hold in the limit of N going to infinity.Comment: 14 pages, 9 figure

Asymmetries in speech articulation as reflected on palatograms: a meta-study

This paper presents the results from an investigation of asymmetries in speech articulation on the basis of 1,502 previously published palatograms of a wide variety of speech sounds in a range of languages. For each palatogram, the direction and degree of tongue-palate contact was quantified by means of an index capturing the degree of lateral asymmetry. The results of this investigation show that lingual asymmetry in the articulation of speech sounds is substantial: 83% of the palatograms are asymmetrical. With respect to the direction of the asymmetry it is found that the asymmetry is more often towards the left side of the palate (45%) than to the right side (38%). Further analysis reveals that there are significant differences in both the direction and the degree of the asymmetry as a function of manner and place of articulation

The noise properties of stochastic processes and entropy production

Based on a Fokker-Planck description of external Ornstein-Uhlenbeck noise and cross-correlated noise processes driving a dynamical system we examine the interplay of the properties of noise processes and the dissipative characteristic of the dynamical system in the steady state entropy production and flux. Our analysis is illustrated with appropriate examples.Comment: RevTex, 1 figure, To appear in Phys. Rev.

Large n limit of Gaussian random matrices with external source, Part III: Double scaling limit

We consider the double scaling limit in the random matrix ensemble with an external source \frac{1}{Z_n} e^{-n \Tr({1/2}M^2 -AM)} dM defined on $n\times n$ Hermitian matrices, where $A$ is a diagonal matrix with two eigenvalues $\pm a$ of equal multiplicities. The value $a=1$ is critical since the eigenvalues of $M$ accumulate as $n \to \infty$ on two intervals for $a > 1$ and on one interval for $0 < a < 1$. These two cases were treated in Parts I and II, where we showed that the local eigenvalue correlations have the universal limiting behavior known from unitary random matrix ensembles. For the critical case $a=1$ new limiting behavior occurs which is described in terms of Pearcey integrals, as shown by Br\'ezin and Hikami, and Tracy and Widom. We establish this result by applying the Deift/Zhou steepest descent method to a $3 \times 3$-matrix valued Riemann-Hilbert problem which involves the construction of a local parametrix out of Pearcey integrals. We resolve the main technical issue of matching the local Pearcey parametrix with a global outside parametrix by modifying an underlying Riemann surface.Comment: 36 pages, 9 figure

Allosteric modulation of the GTPase activity of a bacterial LRRK2 homolog by conformation-specific Nanobodies

Mutations in the Parkinson's disease (PD)-associated protein leucine-rich repeat kinase 2 (LRRK2) commonly lead to a reduction of GTPase activity and increase in kinase activity. Therefore, strategies for drug development have mainly been focusing on the design of LRRK2 kinase inhibitors. We recently showed that the central RocCOR domains (Roc: Ras of complex proteins; COR: C-terminal of Roc) of a bacterial LRRK2 homolog cycle between a dimeric and monomeric form concomitant with GTP binding and hydrolysis. PD-associated mutations can slow down GTP hydrolysis by stabilizing the protein in its dimeric form. Here, we report the identification of two Nanobodies (NbRoco1 and NbRoco2) that bind the bacterial Roco protein (CtRoco) in a conformation-specific way, with a preference for the GTP-bound state. NbRoco1 considerably increases the GTP turnover rate of CtRoco and reverts the decrease in GTPase activity caused by a PD-analogous mutation. We show that NbRoco1 exerts its effect by allosterically interfering with the CtRoco dimer–monomer cycle through the destabilization of the dimeric form. Hence, we provide the first proof of principle that allosteric modulation of the RocCOR dimer–monomer cycle can alter its GTPase activity, which might present a potential novel strategy to overcome the effect of LRRK2 PD mutations

Spectral properties of zero temperature dynamics in a model of a compacting granular column

The compacting of a column of grains has been studied using a one-dimensional Ising model with long range directed interactions in which down and up spins represent orientations of the grain having or not having an associated void. When the column is not shaken (zero 'temperature') the motion becomes highly constrained and under most circumstances we find that the generator of the stochastic dynamics assumes an unusual form: many eigenvalues become degenerate, but the associated multi-dimensional invariant spaces have but a single eigenvector. There is no spectral expansion and a Jordan form must be used. Many properties of the dynamics are established here analytically; some are not. General issues associated with the Jordan form are also taken up.Comment: 34 pages, 4 figures, 3 table