In for a penny, in for a pound: methylphenidate reduces the inhibitory effect of high stakes on persistent risky choice

Methylphenidate (MPH) is a stimulant that increases extracellular levels of dopamine and noradrenaline. It can diminish risky decision-making tendencies in certain clinical populations. MPH is also used, without license, by healthy adults, but the impact on their decision-making is not well established. Previous work has found that dopamine receptor activity of healthy adults can modulate the influence of stake magnitude on decisions to persistently gamble after incurring a loss. In this study, we tested for modulation of this effect by MPH in 40 healthy human adults. In a double-blind experiment, 20 subjects received 20 mg of MPH, while 20 matched controls received a placebo. All were provided with 30 rounds of opportunities to accept an incurred loss from their assets or opt for a "double-or-nothing" gamble that would either avoid or double it. Rounds began with a variable loss that would double with every failed gamble until it was accepted, recovered, or reached a specified maximum. Probability of recovery on any gamble was low and ambiguous. Subjects receiving placebo gambled less as the magnitude of the stake was raised and as the magnitude of accumulated loss escalated over the course of the task. In contrast, subjects treated with MPH gambled at a consistent rate, well above chance, across all stakes and trials. Trait reward responsiveness also reduced the impact of high stakes. The findings suggest that elevated catecholamine activity by MPH can disrupt inhibitory influences on persistent risky choice in healthy adults

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

Fast cholesterol flip-flop and lack of swelling in skin lipid multilayers

Atomistic simulations were performed on hydrated model lipid multilayers that are representative of the lipid matrix in the outer skin (stratum corneum). We find that cholesterol transfers easily between adjacent leaflets belonging to the same bilayer via fast orientational diffusion (tumbling) in the inter-leaflet disordered region, while at the same time there is a large free energy cost against swelling. This fast flip-flop may play an important role in accommodating the variety of curvatures that would be required in the three dimensional arrangement of the lipid multilayers in skin, and for enabling mechanical or hydration induced strains without large curvature elastic costs

The three dimensional dilute Ising magnet

The dilute Ising model with a p = 0.8 fraction of the sites occupied by spins is simulated on L3 systems for L up to 300, using a single-cluster algorithm of Wolff. In the range of reduced temperature 0.002 < (T - Tc)/Tc < 0.03 the susceptibility appears to fit a simple power with an effective exponent γ eff≈ 1.36

Systemic inflammatory cytokine analysis to monitor biomaterial augmented tissue healing.

Hernias can be repaired by reinforcement of damaged fascia using biomaterials to provide stabilisation. Repair materials are usually porous, through which cells infiltrate, proliferate and secrete ECM. Their efficacy relies on good tissue integration and resolution of host defence mechanisms. Therefore, understanding the dynamics by which biomaterials interact with tissue will provide knowledge to advance prosthesis design. Furthermore, determining host response in real time would provide significant advantage both clinically and scientifically over the current terminal process of histology.Unknow

Performance of a Ge 200-strip detector for inelastic X-ray scattering studies

Fabriction and test of a position-sensitive Ge detector with 200 strips arepresented. The detector was designed for the energy analysis of Compton scattered photons dispersed on the Rowland circle of a Cauchois-type cylindrically bent crystal. Each strip of the liquid nitrgen cooled detector, 200 μm wide and separated by a 34 μm wide grooves, is read out by an individual amplification channel. Encoding of discriminator signals enables the rejection of pulse orinating simultaneously in more than one strip. The detector combines high efficiency for 30–50 keV photons with good reproducibility of this figure for each strip. The energy resolution of about 10% is only moderate, but it may be improved by a special preamplifier design with a cooled input stage

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]