Home About us Contact
|
Home About us Contact | ||
|
|
||
Methodological Features (methodological + feature)
Selected AbstractsOn-line dynamic security assessment to mitigate the risk of blackout in the Italian power systemEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 8 2008Diego Cirio Abstract This paper provides a comprehensive survey of the major initiatives and research projects recently carried out by the Italian system operator, Cesi Ricerca, and Universities on power system monitoring, defense, and security assessment. The technological and methodological features of an advanced wide area measurement system (WAMS) are described and the main aspects of an adaptive system for event-based automatic load shedding are presented. Then preventive and corrective security assessment, with particular emphasis to dynamic security assessment,DSA, is introduced. Results from an EU project, where the Italian power system served as a test site for on-line experimentation, are reported. Considering the need for very fast assessment by stability indices, a complementary approach to the above "conventional" DSA, currently under way, is described in further detail. The methodology relies on a correlation model relating significant power system measurements with local loadability margins. Results of some tests on the Italian power system are presented and discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Aquatic Microbial Ecology: Water Desert, Microcosm, Ecosystem.INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4-5 2008What's Next? Abstract Aquatic microbial ecology aims at nothing less than explaining the world from "ecological scratch". It develops theories, concepts and models about the small and invisible living world that is at the bottom of every macroscopic aquatic system. In this paper we propose to look at the development of Aquatic Microbial Ecology as a reiteration of classical (eukaryotic) limnology and oceanography. This was conceptualized moving historically from the so-called water desert to microcosm to ecosystem. Each of these concepts characterizes a particular historical field of knowledge that embraces also practices and theories about living beings in aquatic environments. Concerning the question of "who is there", however, Aquatic Microbial Ecology historically developed in reverse order. Repetition, reiteration and replication notwithstanding, Aquatic Microbial Ecology has contributed new ideas, theories and methods to the whole field of ecology as well as to microbiology. The disciplining of Aquatic Microbial Ecology happened in the larger field of plankton biology, and it is still attached to this biological domain, even conceiving of itself very self-consciously as a discipline of its own. Today, Aquatic Microbial Ecology as a discipline is much broader than plankton ecology ever was, for it includes not only oceans and freshwaters but also benthic, interstitial and groundwater systems. The success of Aquatic Microbial Ecology is expressed by its influence on other fields in ecology. The challenge is to further develop its theoretical and methodological features while at the same time contributing to current pressing problems such as climate change or the management of global water resources. And then it may not be fanciful to suppose that even in the year nineteen hundred and nineteen a great number of minds are still only partially lit up by the cold light of knowledge. It is the most capricious illuminant. They are still apt to ruminate, without an overpowering bias to the truth, whether a kingfisher's body shows which way the wind blows; whether an ostrich digests iron; whether owls and ravens herald ill-fortune; and the spilling of salt bad luck; what the tingling of ears forebodes, and even to toy pleasantly with more curious speculations as to the joints of elephants and the politics of storks, which came within the province of the more fertile and better-informed brain of the author (1919) Virginia Woolf from the essay "Reading", In: Leonard Woolf (ed.), 1950: The Captain's Death Bed and Other Essays, , London: Hogarth Press, p. 157. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A practical valence bond method: A configuration interaction method approach with perturbation theoretic facilityJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2004Lingchun Song Abstract The previously developed valence bond configuration interaction (VBCI) method (Wu, W.; Song, L.; Cao, Z.; Zhang, Q.; Shaik, S., J. Phys. Chem. A, 2002, 105, 2721) that borrows the general CI philosophy of the MO theory, is further extended in this article, and its methodological features are improved, resulting in three accurate and cost-effective procedures: (a) the effect of quadruplet excitation is incorporated using the Davidson correction, such that the new procedure reduces size consistency problems, with due improvement in the quality of the computational results. (b) A cost-effective procedure, named VBCI(D, S), is introduced. It includes doubly excited structures for active electrons and singly excited structures for inactive pairs. The computational results of VBCI(D, S) match those of VBCISD with much less computational effort than VBCISD. (c) Finally, a second-order perturbation theory is utilized as a means of configuration selection, and lead to considerable reduction of the computational cost, with little or no loss in accuracy. Applications of the new procedures to bond energies and barriers of chemical reactions are presented and discussed. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 472,478, 2004 [source] The Effectiveness of Corrective Feedback in SLA: A Meta-AnalysisLANGUAGE LEARNING, Issue 2 2010Shaofeng Li This study reports on a meta-analysis on the effectiveness of corrective feedback in second language acquisition. By establishing a different set of inclusion/exclusion criteria than previous meta-analyses and performing a series of methodological moves, it is intended to be an update and complement to previous meta-analyses. Altogether 33 primary studies were retrieved, including 22 published studies and 11 Ph.D. dissertations. These studies were coded for 17 substantive and methodological features, 14 of which were identified as independent and moderator variables. It was found that (a) there was a medium overall effect for corrective feedback and the effect was maintained over time, (b) the effect of implicit feedback was better maintained than that of explicit feedback, (c) published studies did not show larger effects than dissertations, (d) lab-based studies showed a larger effect than classroom-based studies, (e) shorter treatments generated a larger effect size than longer treatments, and (f) studies conducted in foreign language contexts produced larger effect sizes than those in second language contexts. Possible explanations for the results were sought through data cross-tabulation and with reference to the theoretical constructs of SLA. [source] Establishment of a pharmacoepidemiological database in Germany: methodological potential, scientific value and practical limitationsPHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 3 2008Dipl., Iris Pigeot Dr rer.nat. Abstract Purpose We present a new population-based pharmacoepidemiological (PE) database obtained from statutory health insurances (SHIs) that is able to generate signals, to monitor prescribed drugs and to describe drug utilisation. We discuss methodological features of the database and we assess to which degree this database reflects basic demographic characteristics and hospitalisation rates of the general population. Methods Files of three SHIs were linked with drug dispensation data from a pharmacies' electronic data processing centre on an individual basis using the unique subject identification number (ID) at a trusted third party centre. Plausibility checks and descriptive analyses were carried out. Results The database covers 3.6 million SHI-members, provides drug utilisation data and data on hospitalisations. SHI membership is fairly stable over time. Our data indicate marked differences in socio-demographic characteristics between SHIs. Hospital admission rates standardised for age vary between 0.164 and 0.229 per person year, which is in good agreement with official statistics (0.20). The age distribution shows good agreement for men and some underrepresentation for women above the age of 60 as compared to the general population. Conclusions Confounder information on medical conditions, concomitant medications and socio-demographic variables can be obtained from the database, while the assessment of confounders related to lifestyle requires supplementary data collection. The database allows for a population-based approach and reflects daily practice including off-label use of drugs. Independent recording of exposure and outcome data prevents reporting bias on medication or outcome. Legal conditions that allow continuous updating of the database need to be settled. Copyright © 2008 John Wiley & Sons, Ltd. [source] Is there gender bias in nursing research?RESEARCH IN NURSING & HEALTH, Issue 5 2008Denise F. Polit Abstract Using data from a consecutive sample of 259 studies published in four leading nursing research journals in 2005,2006, we examined whether nurse researchers favor females as study participants. On average, 75.3% of study participants were female, and 38% of studies had all-female samples. The bias favoring female participants was statistically significant and persistent. The bias was observed regardless of funding source, methodological features, and other participant and researcher characteristics, with one exception: studies that had male investigators had more sex-balanced samples. When designing studies, nurse researchers need to pay close attention to who will benefit from their research and to whether they are leaving out a specific group about which there is a gap in knowledge. © 2008 Wiley Periodicals, Inc. Res Nurs Health 31:417,427, 2008 [source] | ||||||||||