The hysteretic softening at small dynamic strains (Payne effect) related to the rolling resistance and viscoelastic losses of tires was studied as a function of particle size, filler volume fraction, and temperature for carbon black (CB) reinforced uncrosslinked styrene-butadiene rubber (SBR) and a paste-like material composed of CB-filled paraffin oil. The low strain limit for dynamic storage modulus was found to be remarkably similar for CB-filled oil compared to CB-filled SBR. Small-angle X-ray scattering (SAXS) measurements on the simple composites and detailed data analysis confirmed that the aggregate structures and nature of filler branching/networking of carbon black were virtually identical within oil compared to the high molecular weight polymer matrix. The combined dynamic rheology and SAXS results provide clear evidence that the deformation-induced breaking (unjamming) of the filler network – characterized by filler-filler contacts that are percolated throughout the material – is the main cause for the Payne effect. However, the polymer matrix does play a secondary role as demonstrated by a reduction in Payne effect magnitude with increasing temperature for the CB-reinforced rubber, which was not observed to a significant extent for the oil-CB system.

The dynamic connectome perspective states that brain functions arise from the functional integration of distributed and/or partly overlapping networks. Diffuse low-grade gliomas (DLGG) have a slow infiltrating character. Here we addressed whether and how anatomical disconnection following DLGG growth and resection might interfere with functional resting-state connectivity, specifically in relation to picture naming. Thirty-nine native French persons with a left DLGG were included. All underwent awake surgical resection of the tumor using direct brain electrostimulation to preserve critical eloquent regions. The anatomical disconnectivity risk following the DLGG volume and the resection, and the functional connectivity of resting-state fMRI images in relation to picture naming were evaluated prior to and three months after surgery. Resting-state connectivity patterns were compared with nineteen healthy controls. It was demonstrated that picture naming was strongly dependent on the semantic network that emerged from the integration and interaction of regions within multiple resting-state brain networks, in which their specific role could be explained in the light of the broader resting-state network they take part in. It emphasized the importance of a whole brain approach with specific clinical data input, during resting-state analysis in case of lesion. Adaptive plasticity was found in secondary regions, functionally connected to regions close to the tumor and/or cavity, marked by an increased connectivity of the right and left inferior parietal lobule with the left inferior temporal gyrus. In addition, an important role was identified for the superior parietal lobe, connected with the frontal operculum, suggesting functional compensation by means of attentional resources in order to name a picture via recruitment of the frontoparietal attention network.

Les nanocomposites de polymères, systèmes de polymères contenant des nanoparticules (NP), sont des systèmes fascinants qui ont de nombreuses applications en science des matériaux, en biologie et en médecine, mais qui posent également des défis en physique théorique. L’un des problèmes fondamentaux de la physique des nanocomposites est de comprendre comment la structure et la dynamique du système dépendent de paramètres clés, tels que la taille et la fraction volumique des NP et la taille typique du maillage polymère. Dans cette thèse, nous utilisons des simulations de dynamique moléculaire pour étudier les propriétés structurelles et dynamiques des NP incorporées dans des nanocomposites de polymères liquides et solides. Nous observons que lorsque des NP faiblement attractives et bien dispersées sont ajoutées à une solution de polymères dense, les polymères et les NP subissent un ralentissement dynamique. Nous trouvons que, en accord qualitatif avec les expériences, ce ralentissement dynamique est capturé par un paramètre de confinement sous la forme h/λ, où h est la distance moyenne entre les surfaces des NP voisines (interparticle distance). Nous pouvons montrer que pour les NP, λ peut être interprété comme le rayon hydrodynamique des NP, alors que pour les polymères il se comporte comme une échelle de longueur de coopérativité. En simulant des réseaux de polymères polydispersés désordonnés contenant des NP purement répulsives, nous constatons que les petites NP peuvent diffuser librement à travers le maillage d’enchevêtrement, tandis que les grosses NP sont piégées de façon transitoire et ne peuvent se déplacer que par une séquence de “sauts” (mouvement de hopping). Nous constatons que le paramètre contrôlant la localisation des NP est le rapport entre le diamètre des NP et la longueur de localisation des crosslinks. Enfin, nous proposons une nouvelle méthode pour caractériser le maillage géométrique dans les liquides de polymères, une quantité importante pour décrire la diffusion des NP dans un milieu désordonné.

BACKGROUND:Neuroimaging studies suggest that social distress and suicidal vulnerability share common cerebral bases. Moreover, increased peripheral inflammatory activity is involved in both social distress and suicidal behavior.OBJECTIVE:To evaluate, in suicidal and non-suicidal individuals, the association between the activation of specific cerebral regions (anterior cingulate, insula and orbitofrontal cortex) during experimental social exclusion and the baseline blood levels of the pro-inflammatory cytokines interleukin-6 (IL-6), interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) and of the anti-inflammatory cytokine interleukin-2 (IL-2).METHODS:In total, 101 euthymic women were recruited: 42 suicide attempters (SA), 40 affective controls (AC), and 19 healthy controls (HC). During functional MRI (fMRI), they performed the Cyberball game, a validated social exclusion task. Blood levels of IL-1β, IL-6, TNF-α and IL-2 were measured prior to fMRI. The activation of insula, orbitofrontal cortex (OFC) and anterior cingulate cortex (ACC) during the explicit social exclusion (ESE) vs social inclusion (INC) conditions of the Cyberball game was analyzed in function of the baseline cytokine levels.RESULTS:IL-1β was negatively associated with right OFC activation (p = 0.01) in ESE vs. INC, whereas IL-2 was positively associated with activation of the right ACC (p = 0.02), insula (p = 0.002) and OFC (p = 0.004) in ESE vs. INC. These associations remained significant after controlling for group, indicating that they were independent of the suicidal status.CONCLUSION:Baseline IL-1β and IL-2 blood levels are differentially associated with cerebral activation involved in the perception of social exclusion, independently of suicidal behavior. Our results may help to better understand the role of basal inflammation in social distress and its link with mood disorder pathophysiology.

I discuss the infrared mass spectrum of strongly-coupled gauge theories, thatinduce the Higgs as a composite pseudo-Nambu-Goldstone boson. The set ofcomposite states accompanying the Higgs is determined by the symmetries of thetheory. Here we estimate their mass spectrum by non-perturbative techniquesinspired by QCD, as well as by exploiting gauge-gravity duality. 1 CompositeHiggs: motivations and relevant energy scales As the Large Hadron Collider (LHC)did not find new states significantly coupled to the Standard Model (SM) belowthe TeV scale, any SM extension by such heavy states suffers from a littlehierarchy problem, as the mass of the scalar Higgs boson lies close to the 100GeV scale. Still, some SM extensions have the potential to address the bighierarchy between the TeV scale and the Planck scale. One possibility is toavoid elementary scalar fields, and assume the observed Higgs is a compositeobject, with a compositeness scale f 1 TeV. This scenario requires a strongly-coupled sector, whose spectrum generically includes several additional compositestates besides the Higgs. The mass of the lowest-lying states cannot exceed ∼4πf , and some could be significantly lighter and within the LHC reach. Definitepredictions for the mass spectrum require to specify the strongly-coupled theoryin the ultraviolet (UV). Here we will assume it is a gauge theory of fermions,that confines in the infrared. We will estimate its mass spectrum in some well-defined approximations, by employing non-perturbative techniques inspired by QCD1) , as well as gauge-gravity duality techniques 2). In models where the Higgsis a pseudo-Nambu-Goldstone boson (pNGB) the electroweak scale, v 246 GeV, isinduced in two steps. The theory has a global (flavour) symmtry G F , that isspontaneously broken to a subgroup H F at the scale f. The electroweak symmetrySU (2) L × U (1) Y is embedded in 91