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Various Schemes (various + scheme)

Distribution by Scientific Domains

Chemistry	40%

Selected Abstracts

ESR Imaging of Conduction Electrons in Organic Conductors

ISRAEL JOURNAL OF CHEMISTRY, Issue 1 2008
Elmar Dormann
In organic conductors built from stacks of planar aromatic hydrocarbons the mobility of the conduction electrons perpendicular to the radical cation stacks is more than four orders of magnitude smaller than the respective along-the-stack value. Thus the macroscopic properties of real single crystals of such radical cation salts are strongly influenced by the distribution of inevitable defects. Therefore, spatial resolution is required for a meaningful interpretation of the ESR data. Various schemes for 2D and 3D ESR imaging have been realized in the radio frequency and microwave frequency range with a resolution down to 10 m,m. Spatial distribution of spin density, T1, T2, and spin diffusion coefficient D were recorded, often as a function of temperature. The conducting-chain length distribution was observed. Our first attempts for the imaging of the integral and the spatially distributed carrier motion caused by an applied electric current were successful. [source]

Improving the Evaluation of Rural Development Policy Pour une meilleure évaluation de la politique de développement rural Die Evaluation der Politik zur Entwicklung des ländlichen Raums verbessern

EUROCHOICES, Issue 1 2010
David Blandford
Summary Improving the Evaluation of Rural Development Policy A previous EuroChoices (Vol. 7, No. 1) compared and contrasted approaches to rural development policy in the EU and US. This Special Issue focuses on the evaluation of these policies, drawing on a workshop held in June 2009 at OECD Conference Center in Paris. Evaluation is an activity that runs parallel with policymaking and is capable of contributing to effectiveness and efficiency at all stages. Evaluators, wherever they work and whatever aspect of rural development is their focus, face some common technical problems. These include multiple (and often ill-defined) policy objectives, the choice of appropriate indicators (especially the need to distinguish between outputs and outcomes), how to establish baseline values, where to draw boundaries in terms of impact and time, and the identification of additionality and causality. Ensuring that lessons learned from evaluation are actually applied is problematic. Experiences covered in this Issue include the use of macro and case-study approaches, and various schemes (investment in human and social capital, and agri-environment and forestry). There is an inherent tension between using a common approach across countries and regions in the interests of comparability and the flexibility needed to capture all the relevant factors in the diverse situations in which rural development actions take place. Un précédent numéro de EuroChoices (Vol. 7, No. 1) comparait et mettait en regard les approches de l'Union européenne et des États-Unis en terme de politique de développement rural. Ce numéro spécial est consacréà l'évaluation de la politique et tire parti d'un atelier qui s'est tenu en juin 2009 au Centre de Conférences de l'OCDE à Paris. L'évaluation va de pair avec l'élaboration des politiques et peut contribuer à améliorer l'efficacité et l'efficience à tous les stades. Quels que soient leur affiliation et l'aspect du développement rural sur lequel ils se concentrent, les évaluateurs sont confrontés à certains problèmes techniques communs. Il s'agit des objectifs multiples (et souvent mal définis) de la politique, du choix d'indicateurs pertinents (en particulier la nécessité de faire la différence entre produit et résultat), de la manière d'établir des valeurs de référence, de la fixation de limites en terme d'incidence et de durée, et de l'identification des effets additifs et de la causalité. Il est difficile de s'assurer que les leçons tirées des évaluations sont effectivement retenues. Les expériences rapportées dans ce numéro comprennent des approches macroéconomiques ou fondées sur des études de cas, et couvrent différents programmes (investissements dans le capital social et humain, mesures agroenvironnementales, mesures forestières). Il existe une tension évidente entre l'utilisation d'une approche commune entre chaque pays et région, qui vise la comparabilité, et la flexibilité qui permet de prendre en compte l'ensemble des différents facteurs des situations variées dans lesquelles les mesures de développement rural sont appliquées. In einer vorherigen Ausgabe von EuroChoices (7:1) wurden Herangehensweisen an die Politik zur Entwicklung des ländlichen Raums in der EU und in den USA verglichen und diskutiert. Diese Sonderausgabe beschäftigt sich auf der Grundlage eines Workshops, der im Juni 2009 am OECD-Hauptsitz in Paris abgehalten wurde, mit Politikevaluation. Die Evaluation erfolgt parallel zur Politikgestaltung und kann in jeder Phase zur Steigerung von Wirksamkeit und Effizienz beitragen. Evaluatoren stehen einigen allgemeinen technischen Problemen gegenüber , ganz gleich, wo sie arbeiten und welchen Aspekten ländlicher Entwicklung sie sich widmen. Dazu zählen multiple (und oftmals unzureichend definierte) politische Ziele; die Auswahl von geeigneten Indikatoren (hier muss insbesondere zwischen Endprodukten und Ergebnissen unterschieden werden); die Frage, wie Ausgangswerte festzulegen und wo Grenzen im Hinblick auf Auswirkungen und den zeitlichen Rahmen zu setzen sind; sowie die Identifizierung von Additionalität und Kausalität. Es ist schwierig sicherzustellen, dass die Erkenntnisse aus der Evaluation auch umgesetzt werden. Die in dieser Ausgabe aufgegriffenen Erfahrungen berücksichtigen u.a. Makro- und Fallstudienansätze sowie verschiedene Maßnahmen (Investitionen in Human-/Sozialkapital sowie Agrarumwelt und Forstwirtschaft). Es besteht eine grundsätzliche Spannung zwischen einer im Interesse der Vergleichbarkeit einheitlichen länder- und regionenübergreifenden Herangehensweise und einer Flexibilität bei der Erfassung aller relevanten Faktoren in den verschiedenen Situationen, in denen ländliche Entwicklung stattfindet. [source]

Mobility prediction and routing in ad hoc wireless networks

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2001
William Su
By exploiting non-random behaviors for the mobility patterns that mobile users exhibit, we can predict the future state of network topology and perform route reconstruction proactively in a timely manner. Moreover, by using the predicted information on the network topology, we can eliminate transmissions of control packets otherwise needed to reconstruct the route and thus reduce overhead. In this paper, we propose various schemes to improve routing protocol performances by using mobility prediction. We then evaluate the effectiveness of using mobility prediction via simulation. Copyright © 2001 John Wiley & Sons, Ltd. [source]

WHY IS THE TAKE-UP OF MICROINSURANCE SO LOW?

THE DEVELOPING ECONOMIES, Issue 1 2010
EVIDENCE FROM A HEALTH INSURANCE SCHEME IN INDIA
F35; O19 Insurance for the poor, called microinsurance, has recently drawn the attention of practitioners in developing countries. There are common problems among the various schemes: (1) low take-up rates, (2) high claim rates, and (3) low renewal rates. In the present paper, we investigate take-up decisions using household data collected in Karnataka, India, focusing on prospect theory, hyperbolic preference, and adverse selection. Prospect theory presumes that people behave in a risk-averse way when evaluating gains but in a risk-loving way when evaluating losses. Because insurance covers losses, the risk-loving attitude toward losses might explain the low take-up rates, and we find weak empirical support for this. Households with hyperbolic preference were more likely to purchase insurance, consistent with our theoretical prediction of demand for commitment. We also find some evidence on the existence of adverse selection: households with a higher ratio of sick members were more likely to purchase insurance. [source]

High Pressure Processing , a Database of Kinetic Information

CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 8 2008
R. Buckow
Abstract Hydrostatic high pressure technology is relatively new to food industry and is more and more considered as an alternative to traditional preservation methods like heat processing. The inactivation of bacteria, spores, viruses and enzymes has been demonstrated in numerous papers, and various schemes for modelling the experimental inactivation data have been suggested. Although there are similarities to heat inactivation kinetics it is generally agreed that the heat process safety assessment with its typical indicator organisms cannot simply be transferred to high pressure treatment. In this paper a database is introduced which aims at the comparison of published kinetic high pressure inactivation data by using suitable mathematical modelling tools. For the sake of clarity, the functional associations of pressure, temperature and exposure time is presented by means of pressure-temperature diagrams (pT -diagrams), which show pressure-temperature combinations yielding to a desired reaction (e.g. inactivation) rate constant. Thus, the database software was particularly designed to enable the user to call up pressure-temperature dependent function equations for a number of micro-organisms, enzymes and food constituents and to visualize them in pT -diagrams for predetermined treatment times or as kinetics under predetermined p - T conditions. In addition, the database also features a simple calculator tool which allows the user to make an entry in three of the four process conditions (pressure level, temperature level, inactivation level, dwell time) and calculate the remaining forth process condition. The database is accessible through the internet and is continuously updated on the basis of the most recent publications and own experimental data. [source]