Plasmon resonant amplification of a hot electron-driven photodiode

Nano Research - We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal (Au/Al2O3/graphene) heterostructure. In this device, hot electrons, excited...     

Comparison of the frequency and enjoyability of pleasant events in cocaine abusers vs. non-abusers using a standardized behavioral inventory

AIMS: To examine whether cocaine abusers differ from non-abusers in their frequency and enjoyability of engaging in various "pleasant events", in order to approximate the density of positive reinforcement experienced in their natural environment. DESIGN: Comparisons of cocaine abusers to normative data and matched controls. SETTING: An outpatient substance abuse treatment center in Burlington, Vermont, USA. PARTICIPANTS: Subjects included 100 individuals enrolled in outpatient treatment for cocaine abuse or dependence and 50 community volunteers without histories of drug abuse or other major psychiatric illness and matched to cocaine-dependent patients on age, sex and SES. MEASUREMENTS: Diagnostic assessments were based upon clinical interviews using the DSM-III-R checklist. The primary focus of this study was the Pleasant Events Schedule (PES), a self-rated behavioral inventory of the frequency and enjoyability of engaging in "pleasant" activities. Cocaine use history, treatment outcome and other relevant variables were also assessed. FINDINGS: Cocaine abusers reliably reported lower frequency of non-social, introverted, passive outdoor and mood-related activities than controls. These differences remained after controlling for demographic and life-style differences between groups, with the exception of mood-related activities. Perceived enjoyability of the activities did not differ across groups. Intravenous cocaine use and prior treatment for cocaine abuse predicted particularly low frequency of pleasant activities. Greater frequency of non-social activities predicted better treatment outcome. CONCLUSIONS: Drug abuse is associated with low density of certain types of non-drug reinforcement. Systematic increases in these activities may improve treatment outcome.     

Phase identification of micro and macro bubbles at the interface of directly bonded GaAs on sapphire

Direct wafer bonding (DWB) of 3 GaAs and R-cut sapphire was performed in a microcleanroom using ultra pure water as cleaning agent. The initial bonding is mediated by Van der Waals forces and hydrogen bridges. The bond energy is released by subsequent heating up to temperatures of 500°C. During heating the formation of macroscopic bubbles at the interface was observed. Details of the interface structure were investigated by cross-sectional as well as plan-view transmission electron microscope (TEM) micrographs. The chemical composition of the elements at the interface was measured by energy dispersive X-ray analysis (EDX) and electron energy loss spectroscopy (EELS). A high density of micro bubbles in bonded areas, a network of micro channels in the transition region and macro bubbles in debonded areas could be distinguished. The macro bubbles are filled with a porous oxide. X-ray diffraction (XRD) and selected area electron diffraction (SAED) revealed the growth of textured -Ga2O3 and elemental arsenic. © 1998 Chapman & Hall     

Voltammetric reduction of nickel and cobalt dimethylglyoximate

The determination of cobalt and nickel in aqueous solutions by stripping voltammetry after adsorptive preconcentration is an established procedure. The method is highly sensitive, but there is some controversy concerning the reasons for the excellent sensitivity. Using a variety of voltammetric techniques, we have determined that the reduction of nickel dimethylglyoximate in an ammonia buffer is consistent with an overall process involving 16 or possibly 18 electrons. This hypothesis is confirmed by independently measuring the total quantity of metal adsorptively deposited on the mercury electrode and comparing the amount with the quantity of electricity required for its reduction.     

Co-constructing with stakeholders a role-playing game to initiate collective management of erosive runoff risks at the watershed scale

Erosive runoff is a recurring problem and is a source of sometimes deadly muddy floods in the Pays de Caux (France). The risk results from a conjunction of natural factors and human activity. Efficient actions against runoff in agricultural watersheds are well known. However they are still difficult to implement as they require co-operation between stakeholders. Local actors thus need tools to help them understand the collective consequences of their individual decisions and help to initiate a process of negotiation between them. We decided to use a participatory approach called companion modelling (ComMod), and, in close collaboration with one of the first group of local stakeholders, to create a role-playing game (RPG) to facilitate negotiations on the future management of erosive runoff. This paper describes and discusses the development of the RPG and its use with other groups of local stakeholders within the framework of two game sessions organized by two different watershed management committees. During the joint construction step, stakeholders shared their viewpoints about the environment, agents, rules, and how to model runoff in preparation for the creation of the RPG. During the RPG sessions, two groups of eight players, including farmers, mayors and watershed advisors, were confronted with disastrous runoff in a fictive agricultural watershed. Results showed that they managed to reduce runoff by 20–50% by engaging a dialogue about grass strips, storage ponds and management of the intercrop period. However, further progress is still needed to better control runoff through the implementation of better agricultural practices because, during the RPG sessions, the watershed advisors did not encourage farmers to do so. Because of the complexity of management problems, results of jointly constructing the game and the RPG sessions showed that modelling and simulation can be a very useful way of accompanying the collective learning process. This new way of working was welcomed by the participants who expressed their interest in organizing further RPG sessions.     

Enhanced display of scientific articles using extended metadata

Although the Web has transformed science publishing, scientific papers themselves are still essentially “black boxes”, with much of their content intended for human readers only. Typically, computer-readable metadata associated with an article is limited to bibliographic details. By expanding article metadata to include taxonomic names, identifiers for cited material (e.g., publications, sequences, specimens, and other data), and geographical coordinates, publishers could greatly increase the scientific value of their digital content. At the same time this will provide novel ways for users to discover and navigate through this content, beyond the relatively limited linkage provided by bibliographic citation.As a proof of concept, my entry in the Elsevier Grand Challenge extracted extended metadata from a set of articles from the journal Molecular Phylogeny and Evolution and used it to populate an entity-attribute-value database. A simple web interface to this database enables an enhanced display of the content of an article, including a map of localities mentioned either explicitly or implicitly (through links to geotagged data), taxonomic coverage, and both data and citation links. Metadata extraction was limited to information listed in tables in the articles, such as GenBank sequences and specimen codes. The body of the article was not used, a restriction that was deliberate to demonstrate that making extended metadata available does not require a journal’s publisher to make the full-text freely available (although this is desirable for other reasons).     

Adventure tourism and adventure sports injury: the New Zealand experience

The primary aims of this study were to establish a client injury baseline for the New Zealand adventure tourism and adventure sport sector, and to examine patterns and trends in claims for injury during participation in adventure activities. Content analysis of narrative text data for compensated injuries occurring in a place for recreation and sport over a 12-month period produced over 15,000 cases involving adventure tourism and adventure sport. As found in previous studies in New Zealand, highest claim counts were observed for activities that are often undertaken independently, rather than commercially. Horse riding, tramping, surfing and mountain biking were found to have highest claim counts, while hang gliding/paragliding/parasailing and jet boating injuries had highest claim costs, suggesting greatest injury severity. Highest claim incidence was observed for horse riding, with female claimants over-represented for this activity. Younger male claimants comprised the largest proportion of adventure injuries, and falls were the most common injury mechanism.     

Small-angle neutron scattering study of creep cavity nucleation and growth in sintered alumina

The early stages of creep cavitation in sintered alumina are characterized using small-angle neutron scattering (SANS). It is found that the initial cavity density is of the order of 10¹¹ cm^–3, and that the average initial pore is approximately 60 nm in radius. The incubation time for nucleating additional pores during subsequent creep is extremely short, in agreement with the theory based on the precipitation of grain-boundary diffusing vacancies. Pore density at constant stress and temperature is a linearly increasing function of time, as predicted by classical nucleation theory. However, a local stress of 10^–2 E is required to achieve the measured nucleation rate. Cavities are observed to lie primarily on two-grain junctions in linear arrays, with an average cavity radius of approximately 60 nm. It is hypothesized that the cavities nucleate at grain boundary ledges which provide the necessary local stress concentrations. Calculation of the individual cavity growth rate yields a zero or near zero value. This suggests a rapid transient growth period following nucleation which quickly decreases to a negligible growth rate.     

Mining frequent conjunctive queries in relational databases through dependency discovery

We present an approach for mining frequent conjunctive in arbitrary relational databases. Our pattern class is the simple, but appealing subclass of simple conjunctive queries. Our algorithm, called Conqueror $^+$ , is capable of detecting previously unknown functional and inclusion dependencies that hold on the database relations as well as on joins of relations. These newly detected dependencies are then used to prune redundant queries. We propose an efficient database-oriented implementation of our algorithm using SQL and provide several promising experimental results.