Gas phase reaction rates of some positive ions with water at 296 K

Measuring rate constants for reactions of various gas phases with water by flowing afterglow techniqu

Ethical implication of emerging technologies

Titre de l'écran-titre (visionné le 3 mai 2007

Near mean-field behavior in the generalized Burridge-Knopoff earthquake model with variable range stress transfer

Simple models of earthquake faults are important for understanding the mechanisms for their observed behavior in nature, such as Gutenberg-Richter scaling. Because of the importance of long-range interactions in an elastic medium, we generalize the Burridge-Knopoff slider-block model to include variable range stress transfer. We find that the Burridge-Knopoff model with long-range stress transfer exhibits qualitatively different behavior than the corresponding long-range cellular automata models and the usual Burridge-Knopoff model with nearest-neighbor stress transfer, depending on how quickly the friction force weakens with increasing velocity. Extensive simulations of quasiperiodic characteristic events, mode-switching phenomena, ergodicity, and waiting-time distributions are also discussed. Our results are consistent with the existence of a mean-field critical point and have important implications for our understanding of earthquakes and other driven dissipative systems.Comment: 24 pages 12 figures, revised version for Phys. Rev.

Simulation of the Burridge-Knopoff Model of Earthquakes with Variable Range Stress Transfer

Simple models of earthquake faults are important for understanding the mechanisms for their observed behavior, such as Gutenberg-Richter scaling and the relation between large and small events, which is the basis for various forecasting methods. Although cellular automaton models have been studied extensively in the long-range stress transfer limit, this limit has not been studied for the Burridge-Knopoff model, which includes more realistic friction forces and inertia. We find that the latter model with long-range stress transfer exhibits qualitatively different behavior than both the long-range cellular automaton models and the usual Burridge-Knopoff model with nearest neighbor springs, depending on the nature of the velocity-weakening friction force. This result has important implications for our understanding of earthquakes and other driven dissipative systems.Comment: 4 pages, 5 figures, published on Phys. Rev. Let

Kinetics and mechanism of the formation of water cluster ions from O2(plus) and H2O in He, Ar, N2, and O2 at 296 K

The reaction sequence leading from O2(+) to H3O(+)-H2O was examined in He, Ar, N2 and O2 carrier gases in a flowing afterglow system. The rate constants for the reactions were measured and the kinetic analysis for their determination is presented. For M = N2, two new steps involving the formation and reaction of O2(+)-N2 were proposed and examined. The rate constants are discussed and compared with other experimental values

Positive Feedback, Memory and the Predictability of Earthquakes

We review the "critical point" concept for large earthquakes and enlarge it in the framework of so-called "finite-time singularities". The singular behavior associated with accelerated seismic release is shown to result from a positive feedback of the seismic activity on its release rate. The most important mechanisms for such positive feedback are presented. We introduce and solve analytically a novel simple model of geometrical positive feedback in which the stress shadow cast by the last large earthquake is progressively fragmented by the increasing tectonic stress. Finally, we present a somewhat speculative figure that tends to support a mechanism based on the decay of stress shadows. This figure suggests that a large earthquake in Southern California of size similar to the 1812 great event is maturing.Comment: PostScript document of 18 pages + 2 eps figure

An inhomogeneous fault model for gaps, asperities, barriers, and seismicity migration

We develop a model for a fault in which various areas of the fault plane have different stress-slip constitutive laws. The model is conceptually simple, involving nonlinear algebraic equations which can easily be solved by a graphical method of successive iterations. Application is made to the problem of explaining seismicity patterns associated with great earthquakes. The model quantitatively explains phenomena associated with seismic gaps, asperities, and barriers

Towards curricula in design for all for information and communication products, systems and services.

The aim of the Inclusive Design Curriculum Network (IDCnet) is to integrate information and identify core knowledge sets and skills for model curricula in design for all (DfA) specifically for information and communication products, systems and services. Identifying such knowledge and skills is a step towards providing designers with training and competence in inclusive design principles, methods and tools. One of the first major activities of IDCnet is a workshop to be held in Helsinki in February 2003 called ‘Design for All Curriculum: Towards a synergy of the needs of ICT industry and education.’ The workshop will be bringing together: • Experts from DfA-aware industries to discuss and suggest what they would expect from graduates they would employ who claim to have proficiency in DfA, and • Experts from the academic world, with teaching or research interests in DfA, to use their own experiences in the field to suggest key knowledge sets and skills that would be necessary for curricula in this area. This presentation will: • summarise and discuss the Helsinki results and recommendations • discuss existing fora, information resources, materials and tools which could form part of model DfA curricula • seek further views and opinions from educators, trainers, students, education policy makers and end-users, and • promote the network to a wider audience of those interested in design for all curricula in the specific field of ICT

Moderating teen drinking: Combining social marketing and education

This paper outlines a pilot study that was undertaken in Australia in 2011 that combined social marketing with education. An intervention targeting 14-16 year olds to influence attitudes and behavioural intentions towards moderate drinking was developed and tested. Game On:Know alcohol (GO:KA) is a six-module intervention that is delivered to a year level cohort in an auditorium. GO:KA combines a series of online and offline experiential activities to engage (with) students. Following social marketing benchmark criteria, formative research and competitive analysis were undertaken to create, implement and evaluate an intervention. The intervention was delivered in one all boys' and one all girls' school in April and June 2011, respectively. A total of 223 Year 10 students participated in GO:KA with the majority completing both pre- and post-surveys. Paired samples t-tests and descriptive analysis were used to assess attitudinal and behavioural intention change. Attitudinal change was observed in both schools while behavioural intentions changed for girls and not boys according to paired samples t-testing. Post hoc testing indicated gender differences. The lack of a control group is a key limitation of the current research that can be overcome in the 20 school main study to be conducted in 2013-2015. The current study provides evidence to suggest that a combined social marketing and education intervention can change teenage attitudes towards moderate drinking whilst only changing behavioural intentions for female teenagers. Analysis of the intervention provides insight into gender differences and highlights the need for a segmented approach