The continuum limit of the quark mass step scaling function in quenched lattice QCD

The renormalisation group running of the quark mass is determined non-perturbatively for a large range of scales, by computing the step scaling function in the Schroedinger Functional formalism of quenched lattice QCD both with and without O(a) improvement. A one-loop perturbative calculation of the discretisation effects has been carried out for both the Wilson and the Clover-improved actions and for a large number of lattice resolutions. The non-perturbative computation yields continuum results which are regularisation independent, thus providing convincing evidence for the uniqueness of the continuum limit. As a byproduct, the ratio of the renormalisation group invariant quark mass to the quark mass, renormalised at a hadronic scale, is obtained with very high accuracy.Comment: 23 pages, 3 figures; minor changes, references adde

Universal Rights and Wrongs

This paper argues for the important role of customers as a source of competitive advantage and firm growth, an issue which has been largely neglected in the resource-based view of the firm. It conceptualizes Penrose’s (1959) notion of an ‘inside track’ and illustrates how in-depth knowledge about established customers combines with joint problem-solving activities and the rapid assimilation of new and previously unexploited skills and resources. It is suggested that the inside track represents a distinct and perhaps underestimated way of generating rents and securing long-term growth. This also implies that the sources of sustainable competitive advantage in important respects can be sought in idiosyncratic interfirm relationships rather than within the firm itself

Solubility of Cellulose in Supercritical Water Studied by Molecular Dynamics Simulations

The insolubility of cellulose in ambient water and most aqueous systems presents a major scientific and practical challenge. Intriguingly though, the dissolution of cellulose has been reported to occur in supercritical water. In this study, cellulose solubility in ambient and supercritical water of varying density (0.2, 0.7, and 1.0 g cm^–3) was studied by atomistic molecular dynamics simulations using the CHARMM36 force field and TIP3P water. The Gibbs energy of dissolution was determined between a nanocrystal (4 × 4 × 20 anhydroglucose residues) and a fully dissociated state using the two-phase thermodynamics model. The analysis of Gibbs energy suggested that cellulose is soluble in supercritical water at each of the studied densities and that cellulose dissolution is typically driven by the entropy gain upon the chain dissociation while simultaneously hindered by the loss of solvent entropy. Chain dissociation caused density augmentation around the cellulose chains, which improved water–water bonding in low density supercritical water whereas the opposite occurred in ambient and high density supercritical water

Dynamics of cellulose-water interfaces: NMR spin-lattice relaxation times calculated from atomistic computer simulations

International audienc

Modulation of social influence by methylphenidate

The ability to infer value from the reactions of other people is a common and essential ability with a poorly understood neurobiology. Commonly, social learning matches one's values and behavior to what is perceived as normal for one's social group. This is known as conformity. Conformity of value correlates with neural activity shared by cognitions that depend on optimum catecholamine levels, but catecholamine involvement in conformity has not been tested empirically. Methylphenidate (MPH) is an indirect dopamine and noradrenalin agonist, commonly used for the treatment of attention-deficit hyperactivity disorder for which it reduces undesirable behavior as evaluated by peers and authority figures, indicative of increased conformity. We hypothesized that MPH might increase conformity of value. In all, 38 healthy adult females received either a single oral 20 mg dose of MPH or placebo (PL). Each subject rated 153 faces for trustworthiness followed immediately by the face's mean rating from a group of peers. After 30 min and a 2-back continuous-performance working-memory task, subjects were unexpectedly asked to rate all the faces again. Both the groups tended to change their ratings towards the social norm. The MPH group exhibited twice the conformity effect of the PL group following moderate social conflict, but this did not occur following large conflicts. This suggests that MPH might enhance signals that would otherwise be too weak to evoke conformity. MPH did not affect 2-back performance. We provide a new working hypothesis of a neurocognitive mechanism by which MPH reduces socially disruptive behavior. We also provide novel evidence of catecholamine mediation of social learning [corrected]