Adult age differences in sensitivity to semantic structure of prose.

50 18–33 yr olds and 43 62–67 yr olds from low- and high-education populations heard narrative passages at different presentation rates and difficulty levels in 2 experiments. Immediately after listening to a tape-recorded version of each story, Ss orally recalled it. Results consistently demonstrate that younger Ss remembered more than older ones, but Ss from all groups favored the main ideas in their recalls. Also, Ss from all ages and educational levels were equally able to identify the important information in the stories. It is suggested that sensitivity to the semantic structure of prose is not a major component of adult age differences in discourse comprehension. It is further suggested that adult age differences observed on discourse comprehension tasks may reflect an age-related decline in processing capacity. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Economics of Dynamic Pricing in a Reputation Brokered Agent Mediated Marketplace

We present a framework to study the microeconomic effects in a reputation brokered Agent mediated Knowledge Marketplace, when we introduce dynamic pricing algorithms. We study the market with computer simulations of multiagent interactions. In this marketplace, the seller reputations are updated in a collaborative fashion based on the performance of the user in the delegated tasks. To the best of our knowledge this is the first agent mediated marketplace where the agents use dynamic pricing based on dynamically updated reputations. The framework can be used to investigate the different equilibria reached, based on the level of intelligence of the selling agents, the level of price-importance elasticity of the buying agents, and the level of unemployment in the marketplace. Preliminary experiments addressing these issues are presented.     

Rapid determination of safranal in the quality control of saffron spice (Crocus sativus L.)

A method to determine safranal content based on non-polar solvent extraction followed by UV–Vis analysis available in the industry for quality control of saffron spice has been studied. Ultrasound-assisted extraction of safranal was carried out and optimised with respect to the solvent: diethyl ether, hexane and chloroform; the time of extraction; and the concentration of saffron in each organic solvent. Best extraction conditions were obtained when 20 g L^?1 of saffron was extracted with chloroform for 15 min. Intra-laboratory validation of the optimised conditions and analysis by UV–Vis spectrophotometry showed satisfactory results in linearity, repeatability, intermediate precision and recovery. The limit of detection was 1 mg safranal kg^?1 saffron and the limit of quantification was 3 mg safranal kg^?1 saffron.     

Social value creation through digital activism in an online health community

The study explores how online health communities produce social value by uniting individuals under a common purpose, to advance healthcare in post‐conflict states. We selected MedicineAfrica – a digital platform known for creating social value by providing medical education in regions with under‐resourced healthcare systems – and drew on multiple data collection methods. We found that it is through a unique form of digital health activism that social value is created in this context. Drawing on a sociological understanding of digital health activism, we make the following contributions: First, we identify three types of non‐economic, social value: cognitive, professional and epistemic. Second, we indicate that social value creation is enabled by three emergent forms of digital health activism (ie, philanthropic, moral and reciprocal activity). Third, we elicit three enabling mechanisms explaining how these forms of activism are technically and socially afforded through the platform's connective capacity and emerging collective practices in tandem with its members' growing commitment. Our article contributes to the growing IS literature on digital activism by offering a framework that elucidates how digital health activism relates to social value creation. The article provides practical implications as to how platforms can enable sustainable online (health) communities.     

Recent advances on hydrogen embrittlement of structural materials

This paper presents a critical review of current understanding of the effect of hydrogen on fracture and fatigue of metals and alloys. First, microstructures found immediately beneath hydrogen-induced fracture surfaces in various materials are presented. Then, recent progress toward the fundamentals of hydrogen-induced fracture is reported. Lastly, a recent attempt to model hydrogen embrittlement by linking the macroscale (e.g. applied load and hydrogen content) and the operating microscopic degradation mechanism at the local microstructural defect level is reviewed.     

Calcite Reinforced Silica–Silica Joints in the Biocomposite Skeleton of Deep‐Sea Glass Sponges

The hierarchically structured glass sponge Caulophacus species uses the first known example of a silica and calcite biocomposite to join the spicules of its skeleton together. In the stalk and body skeleton of this poorly known deep‐sea glass sponge siliceous spicules are modified by the addition of conical calcite seeds, which then form the basis for further silica secretion to form a spinose region. Spinose regions on adjacent spicules are then joined by siliceous crosslinks, leading to unusually strong cross‐spicule linkages. In addition to the biomaterials implications it is now clear, from this first record of a biomineral other than silica, that the hexactinellid sponges are capable of synthesizing calcite, the ancestral skeletal material. We propose that, while the low concentrations of calcium in deep sea waters drove the evolution of silica skeletons, the brittleness of silica has led to retention of the more resilient calcite in very low concentrations at the skeletal joints.     

Mesh-particle interpolations on graphics processing units and multicore central processing units

Particle-mesh interpolations are fundamental operations for particle-in-cell codes, as implemented in vortex methods, plasma dynamics and electrostatics simulations. In these simulations, the mesh is used to solve the field equations and the gradients of the fields are used in order to advance the particles. The time integration of particle trajectories is performed through an extensive resampling of the flow field at the particle locations. The computational performance of this resampling turns out to be limited by the memory bandwidth of the underlying computer architecture. We investigate how mesh-particle interpolation can be efficiently performed on graphics processing units (GPUs) and multicore central processing units (CPUs), and we present two implementation techniques. The single-precision results for the multicore CPU implementation show an acceleration of 45-70×, depending on system size, and an acceleration of 85-155× for the GPU implementation over an efficient single-threaded C++ implementation. In double precision, we observe a performance improvement of 30-40× for the multicore CPU implementation and 20-45× for the GPU implementation. With respect to the 16-threaded standard C++ implementation, the present CPU technique leads to a performance increase of roughly 2.8-3.7× in single precision and 1.7-2.4× in double precision, whereas the GPU technique leads to an improvement of 9× in single precision and 2.2-2.8× in double precision.