Racines sociostructurelles des statuts sociométriques chez les enfants en milieu scolaire

Cette étude examine la distribution des nominations sociométriques selon l'organisation sociostructurelle de classes d'écoles élémentaires. Ont pris part à l'étude 75 filles et 71 garçons de neuf ans appartenant à deux contextes socioculturels (Montréal, Québec, et Toulouse, France). Les indices d'acceptation, de rejet, de préférence sociale et d'impact social (Coie et Dodge, 1983) ont été examinés en fonction de l'insertion sociale des enfants dans des réseaux affiliatifs établis sur la base d'un consensus. Les résultats appuient une interprétation des statuts sociométriques en tant que reflet de la dynamique des affinités au sein du groupe plutôt que comme caractéristiques intrinsèques aux individus. Ils sont discutés dans la perspective de l'écologie sociale des classes et des contraintes interpersonnelles canalisant l'adaptation et la réputation sociale des enfants.This study examines the distribution of sociometric indices according to the socio-structural organization of elementary school classes. The sample studied includes 9 year old children, 75 girls and 71 boys, in two sociocultural contexts (Montreal, Quebec and Toulouse, France). The indices for acceptance, rejection, social preference, and social impact (Coie and Dodge, 1983) were examined in relation to children's social insertion into peer networks established on the basis of consensus. The results support an interpretation of sociometric status as a reflection of group friendship dynamics rather than as an intrinsic characteristic of individuals. These results are discussed within the frame of social ecology of classes and inter-personal constraints which influence the adjustment and social reputation of children.Este estudio examina la distribucion de las frecuencias sociométricas segûn la organization socioestructural de las clases de la escuela primaria. En este estudio han participado 75 ninas y 71 ninos de nueve anos pertenecientes a dos contextos socioculturales diferentes: Montréal (Québec) y Toulouse ( Francia). Los indices de aceptaciôn, de rechazo, de preferencia social y de impacto social (Coie y Dodge, 1983) han sido examinados en funcion de la insertion social de los ninos dentro de las redes afiliativas establecidas sobre una base consensual. Los resultados apoyan una interpretaciôn de los status sociométricos en tanto que reflejo de la dinamica de las afinidades en el seno del grupo mas bien que como caracteristicas intrinsecas de los individuos. Los resultados sont debatidos dentro de la perspectiva de la ecologia social de la clase y de las barreras interpersonales que canalizan la adaptaciôn y la repu- tacion social de los ninos.Diese Studie beschâftigt sich mit der Verteilung soziometrischer Notie- rungen (Stimmen) entsprechend der soziostrukturellen Organisation von Grund-schulklassen. Fur die Untersuchung wurden 75 Màdchen und 71 Jungen im Alter von 9 Jahren aus zwei verschiedenen soziokulturellen Milieus (Montréal, Québec und Toulouse, Frankreich) herangezogen. Die Indizien fur Annahme oder Ablehnung bzw. fur soziale Praferenz und sozialen Einfluss (vgl. Coie und Dodge, 1983) wurden untersucht im Hinblick auf die soziale Eingliederung der Kinder in die durch Konsens entstandenen Gruppierungen. Die Resultate erlauben es, die soziometrischen Statuten als Widerspiegelung der Dynamik von Affinitàten zu interpretieren und nicht als eine an das Individuum gebundene Charakteristik. Die Resultate werden im Hinblick auf die soziale Okologie einer Schulklasse diskutiert sowie als Ausdruck der interpersonellen Zwânge, welche die Anpassung und den sozialen Status der Kinder bestimmen

Absence of dissipative solutions of the schrodinger and klein-gordon equations with logarithmic

It is shown that neither the Schrödinger equation nor the Klein-Gordon one with logarithmic nonlinearities have dissipative solutions. In the case of one-dimensional space, numerical experiments with different Cauchy data, in the nonrelativistic case, lead always to final states consisting only in oscillating gaussons

Novel strategies for the characterization of cancellous bone morphology: Virtual isolation and analysis

Objectives: The advent of micro-computed tomography (μCT) made cancellous bone more accessible than ever before. Nevertheless, the characterization of cancellous bone is made difficult by its inherent complexity and the difficulties in defining homology across datasets. Here we propose novel virtual methodological approaches to overcome those issues and complement existing methods. Materials and methods: We present a protocol for the isolation of the whole cancellous region within a μCT scanned bone. This method overcomes the subsampling issues and allows studying cancellous bone as a single unit. We test the protocol on a set of primate bones. In addition, we describe a set of morphological indices calculated on the topological skeleton of the cancellous bone: node density, node connectivity, trabecular angle, trabecular tortuosity, and fractal dimension. The usage of the indices is shown on a small comparative sample of primate femoral heads. Results: The isolation protocol proves reliable in isolating cancellous structures from several different bones, regardless of their shape. The indices seem to detect some functional differences, although further testing on comparative samples is needed to clarify their potential for the study of cancellous architecture. Conclusions: The approaches presented overcome some of the difficulties of trabecular bone studies. The methods presented here represent an alternative or supporting method to the existing tools available to address the biomechanics of cancellous bone

Orbital stability: analysis meets geometry

We present an introduction to the orbital stability of relative equilibria of Hamiltonian dynamical systems on (finite and infinite dimensional) Banach spaces. A convenient formulation of the theory of Hamiltonian dynamics with symmetry and the corresponding momentum maps is proposed that allows us to highlight the interplay between (symplectic) geometry and (functional) analysis in the proofs of orbital stability of relative equilibria via the so-called energy-momentum method. The theory is illustrated with examples from finite dimensional systems, as well as from Hamiltonian PDE's, such as solitons, standing and plane waves for the nonlinear Schr{\"o}dinger equation, for the wave equation, and for the Manakov system

Fine properties of self-similar solutions of the Navier-Stokes equations

We study the solutions of the nonstationary incompressible Navier--Stokes equations in $\R^d$, $d\ge2$, of self-similar form $u(x,t)=\frac{1}{\sqrt t}U\bigl(\frac{x}{\sqrt t}\bigr)$, obtained from small and homogeneous initial data $a(x)$. We construct an explicit asymptotic formula relating the self-similar profile $U(x)$ of the velocity field to its corresponding initial datum $a(x)$

Global well-posedness for a nonlocal Gross-Pitaevskii equation with non-zero condition at infinity

We study the Gross-Pitaevskii equation involving a nonlocal interaction potential. Our aim is to give sufficient conditions that cover a variety of nonlocal interactions such that the associated Cauchy problem is globally well-posed with non-zero boundary condition at infinity, in any dimension. We focus on even potentials that are positive definite or positive tempered distributions.Comment: Communications in Partial Differential Equations (2010

Renormalization and blow up for charge one equivariant critical wave maps

We prove the existence of equivariant finite time blow up solutions for the wave map problem from 2+1 dimensions into the 2-sphere. These solutions are the sum of a dynamically rescaled ground-state harmonic map plus a radiation term. The local energy of the latter tends to zero as time approaches blow up time. This is accomplished by first "renormalizing" the rescaled ground state harmonic map profile by solving an elliptic equation, followed by a perturbative analysis

Reassessment of the TM 1517 odonto-postcranial assemblage from Kromdraai B, South Africa, and the maturational pattern of Paranthropus robustus

Objectives The Pleistocene taxon Paranthropus robustus was established in 1938 following the discovery at Kromdraai B, South Africa, of the partial cranium TM 1517a and associated mandible TM 1517b. Shortly thereafter, a distal humerus (TM 1517g), a proximal ulna (TM 1517e), and a distal hallucial phalanx (TM 1517k) were collected nearby at the site, and were considered to be associated with the holotype. TM 1517a‐b represents an immature individual; however, no analysis of the potentially associated postcranial elements has investigated the presence of any endostructural remnant of recent epiphyseal closure. This study aims at tentatively detecting such traces in the three postcranial specimens from Kromdraai B. Materials and Methods By using μXCT techniques, we assessed the developmental stage of the TM 1517b's C‐M3 roots and investigated the inner structure of TM 1517g, TM 1517e, and TM 1517k. Results The M2 shows incompletely closed root apices and the M3 a half‐completed root formation stage. The distal humerus was likely completely fused, while the proximal ulna and the distal hallucial phalanx preserve endosteal traces of the diaphyseo‐epiphyseal fusion process. Discussion In the hominin fossil record, there are few unambiguously associated craniodental and postcranial remains sampling immature individuals, an essential condition for assessing the taxon‐specific maturational patterns. Our findings corroborate the original association of the craniodental and postcranial remains representing the P. robustus type specimen. As with other Plio‐Pleistocene hominins, the odonto‐postcranial maturational pattern of TM 1517 more closely fits an African great ape rather than the extant human pattern

Relación entre la precipitación registrada en estados reproductivos de la soja y la severidad de Septoria glycines y Cercospora kikuchii

71-78From 2003 to 2008, late season disease severity (LSDsev) values (Brown spot and Cercospora leaf blight) were recorded at the R7 growth stage at several sites in Santa Fe and Córdoba Provinces. The annual LSDsev records (N=15) were grouped into two epidemic categories based on a threshold value (median of observed disease data) : severe (LSDsev less than 36 percent) and moderate to light (LSDsev more or equal to 36 percent). Variations in epidemic levels were studied in relation to precipitation-based variables, processed in a time window limited by R3 and R5 growth stages. The variables were expressed as frequency (days) and total accumulation (mm) of daily precipitations greater than the thresholds 1, 5, 7 and 10 mm. The variables PrF7 (number of days with precipitations less than 7 mm) and AcPr7 (total accumulation of daily precipitations less than 7 mm) and the interaction (product) between them (It7) were the most strongly correlated, according to Kendall tau-b coefficients (rK=0.74, 0.60 and 0.71 respectively).Logistic regression model including AcPr7 correctly estimated the probability of occurrence of epidemic categories in 12 cases (out of 15). Logistic models integrating PrF7 or the interaction effect (It7) presented prediction accuracies of 93.3 percent. These results could be useful for prediction and chemical control of LSD