The keys to get high transconductance of AlGaAs/InGaAs/GaAs pseudomorphic HEMTs devices

There are two key points to get high transconductance of pseudomorphic HEMTS (pHEMTs) devices. From the point view of materials, the transfer efficiency of the electrons from the delta -doped AlGaAs layer to the InGaAs channel must be high. From the point view of device processing, the gate recess depth must be carefully controlled. In the present work, AlGaAs/InGaAs/GaAs pHEMTs structures were grown by molecular beam epitaxy. Layer structures of the pHEMTs were optimized to get high transfer efficiency of the electrons. Gate recess depth was also optimized. A 0.2 mum pHEMT was fabricated on the materials with optimized layer structure using the optimized gate recess depth. The maximum transconductance of 650 mS/mm and the cut-off frequency of 81 GHz were achieved. (C) 2001 published by Elsevier Science Ltd.

Discovering keys to explain social policies within the social and democratic rule-of-law sate

There is a collective worldview on social policies that is expressed and understood by university professionals. However, it takes students time to construct this knowledge. Here, we provide fundamental ideas and a dynamic to facilitate learning of social policies. The preparation of a brief dictionary of significant terms is to be constructed as a group, alongside the maieutic work to be carried out by the teacher. The goal is to discover keys to understand the meaning of social policies and the underlying values that sustain a social and democratic rule-of-law state such as the one proposed in the Spanish Constitution of 1978. Attention is focused on the structure of the mixed welfare state. This is an integral proposal and comprises three dimensions. First, it considers the state and its possible welfare agents: business, market, the Church and civil society. The attitudes with which universal and inclusive social action is promoted, breaking radically with the aid-based meaning contained in other systems, are then addressed. Finally, we examine human dignity as a principle and aim of intervention, a basis for understanding other concepts such as human, social, labour and political rights. It is to be hoped that these pages prove useful for both teaching staff and students.

A synopsis of the genus Bursaphelenchus Fuchs, 1937 (Aphelenchida: Parasitaphelenchidae) with keys to species

The 75 valid species of the genus Bursaphelenchus are listed together with their synonyms. Diagnostic characters and their states are discussed and illustrated. Tabular and traditional text keys are provided for the genus. Two new subspecies are proposed to distinguish populations of B. piniperdae and B. poligraphi, as described by Rühm (1956), from the original descriptions of these species published by Fuchs (1937). Known records of Bursaphelenchus species with their associated natural vectors, plants and plant families are given. Dendrograms of species relationships (UPGMA, standard distance: mean character difference) based on combined taxonomic characters and also on spicule characters only, are provided. Discussion as to whether the species groups are natural or artificial (and therefore purely diagnostic) is based on their relationships in the dendrogram and the vector and associated plant ranges of the species. Of the six species groups distinguished, two appear to represent natural assemblages, these being the xylophilus-group (with ten species) and the hunti-group (seven species), of which two, B. cocophilus and B. dongguanensis, form the cocophilus-cluster which is separated on the dendrogram from the main clusters. The remaining four species groups appear to be artificial and purely diagnostic in function, namely the aberrans-group (four species); the eidmanni-group (six species); the borealis-group (five species), and the piniperdae-group (43 species). Two new subspecies, both in the piniperdae-group, viz. B. piniperdae ruehmpiniperdae n. subsp. and B. poligraphi ruehmpoligraphi n. subsp., are proposed and diagnosed from B. piniperdae piniperdae and B. poligraphi poligraphi the respective type subspecies. Bursaphelenchus dongguanensis is regarded as being a valid member of the genus and its transfer to Parasitaphelenchus is rejected.

Understanding the "black box" of a health-promotion program : keys to enable health among older persons aging in the context of migration

Although the need to make health services more accessible to persons who have migrated has been identified, knowledge about health-promotion programs (HPPs) from the perspective of older persons born abroad is lacking. This study explores the design experiences and content implemented in an adapted version of a group-based HPP developed in a researcher-community partnership. Fourteen persons aged 70-83 years or older who had migrated to Sweden from Finland or the Balkan Peninsula were included. A grounded theory approach guided the data collection and analysis. The findings showed how participants and personnel jointly helped raise awareness. The participants experienced three key processes that could open doors to awareness: enabling community, providing opportunities to understand and be understood, and confirming human values and abilities. Depending on how the HPP content and design are being shaped by the group, the key processes could both inhibit or encourage opening doors to awareness. Therefore, this study provides key insights into how to enable health by deepening the understanding of how the exchange of health-promoting messages is experienced to be facilitated or hindered. This study adds to the scientific knowledge base of how the design and content of HPP may support and recognize the capabilities of persons aging in the context of migration.

Social capital and culture: master keys to development

Includes bibliography

Pobres, urbanos y productividad: claves de intervención = Urban poor and productivity: keys to action

Incluye Bibliografía

Urban poor and productivity: keys to action. Public programmes aimed at raising productivity of poor sectors in urban areas of Jamaica

Includes bibliography

Volunteers Opening Doors: the Five Keys to Lead Safety

Millions of houses and apartments built before 1978 have paint that contains lead. Chips, dust, and fumes from this paint can be very dangerous if they are not handled properly. Lead is particularly hazardous to unborn babies, infants, and young children. Volunteers in painting and housing-rehabilitation programs often work in homes that contain lead paint. The work they perform can create a lead hazard if they disturb this paint and produce paint chips or dust. Volunteers Opening Doors is a video program for these volunteers. It explains how volunteers can protect housing residents,themselves, and their families from lead poisoning by using the five keys to lead safety: 1. Protect residents and their belongings. 2. Prepare the work area. 3. Protect yourself from dust and debris. 4. Work wet. 5. Work clean.

Global macrozoobenthos production and energy budget data base V150731, with link to database

I developed a new model for estimating annual production-to-biomass ratio P/B and production P of macrobenthic populations in marine and freshwater habitats. Self-learning artificial neural networks (ANN) were used to model the relationships between P/B and twenty easy-to-measure abiotic and biotic parameters in 1252 data sets of population production. Based on log-transformed data, the final predictive model estimates log(P/B) with reasonable accuracy and precision (r2 = 0.801; residual mean square RMS = 0.083). Body mass and water temperature contributed most to the explanatory power of the model. However, as with all least squares models using nonlinearly transformed data, back-transformation to natural scale introduces a bias in the model predictions, i.e., an underestimation of P/B (and P). When estimating production of assemblages of populations by adding up population estimates, accuracy decreases but precision increases with the number of populations in the assemblage.

Molecular keys to speciation: DNA polymorphism and the control of genetic exchange in enterobacteria

Speciation involves the establishment of genetic barriers between closely related organisms. The extent of genetic recombination is a key determinant and a measure of genetic isolation. The results reported here reveal that genetic barriers can be established, eliminated, or modified by manipulating two systems which control genetic recombination, SOS and mismatch repair. The extent of genetic isolation between enterobacteria is a simple mathematical function of DNA sequence divergence. The function does not depend on hybrid DNA stability, but rather on the number of blocks of sequences identical in the two mating partners and sufficiently large to allow the initiation of recombination. Further, there is no obvious discontinuity in the function that could be used to define a level of divergence for distinguishing species.