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System Features (system + feature)
Selected AbstractsOptimization of Full-Scale Permanganate ISCO System Operation: Laboratory and Numerical StudiesGROUND WATER MONITORING & REMEDIATION, Issue 4 2008Jeffrey L. Heiderscheidt Laboratory characterization studies, one-dimensional flow-through studies, and numerical model simulations were conducted to examine site conditions and system features that may have adversely affected in situ chemical oxidation (ISCO) performance at the Naval Training Center's (NTC) Operable Unit 4 located in Orlando, Florida, and to identify potential ISCO system modifications to achieve the desired remediation performance. At the NTC site, ISCO was implemented using vertical injection wells to deliver potassium permanganate into a ground water zone for treatment of tetrachloroethylene and its breakdown products. However, oxidant distribution was much more limited than anticipated. Characterization studies revealed that the ground water zone being treated by ISCO was very fine sand with a small effective particle size and low uniformity coefficient, along with a high organic carbon content, high natural oxidant demand (NOD), and a high ground water dissolved solids concentration, all of which contributed to full-scale ISCO application difficulties. These site conditions contributed to injection well permeability loss and an inability to achieve the design oxidant injection flow rate, limiting the actual oxidant distribution at the site. Flow-through experiments demonstrated that more favorable oxidant delivery and distribution conditions are enabled by applying a lower oxidant concentration at a faster delivery rate for a greater number of pore volumes. Numerical simulations, run for a variety of conditions (injection/extraction well flow rates, injected oxidant concentration, amount of NOD present, and NOD oxidation rate), also revealed that low,oxidant concentration injection at a high flow rate is a more effective method to deliver the required mass of oxidant to the target treatment zone. [source] Integrating evidence into clinical practice: an alternative to evidence-based approachesJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 3 2006Mark R. Tonelli MD MA Abstract Evidence-based medicine (EBM) has thus far failed to adequately account for the appropriate incorporation of other potential warrants for medical decision making into clinical practice. In particular, EBM has struggled with the value and integration of other kinds of medical knowledge, such as those derived from clinical experience or based on pathophysiologic rationale. The general priority given to empirical evidence derived from clinical research in all EBM approaches is not epistemically tenable. A casuistic alternative to EBM approaches recognizes that five distinct topics, 1) empirical evidence, 2) experiential evidence, 3) pathophysiologic rationale, 4) patient goals and values, and 5) system features are potentially relevant to any clinical decision. No single topic has a general priority over any other and the relative importance of a topic will depend upon the circumstances of the particular case. The skilled clinician must weigh these potentially conflicting evidentiary and non-evidentiary warrants for action, employing both practical and theoretical reasoning, in order to arrive at the best choice for an individual patient. [source] Transitions in search tactics during the Web-based search processJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 11 2010Iris Xie Although many studies have identified search tactics, few studies have explored tactic transitions. This study investigated the transitions of search tactics during the Web-based search process. Bringing their own 60 search tasks, 31 participants, representing the general public with different demographic characteristics, participated in the study. Data collected from search logs and verbal protocols were analyzed by applying both qualitative and quantitative methods. The findings of this study show that participants exhibited some unique Web search tactics. They overwhelmingly employed accessing and evaluating tactics; they used fewer tactics related to modifying search statements, monitoring the search process, organizing search results, and learning system features. The contributing factors behind applying most and least frequently employed search tactics are in relation to users' efforts, trust in information retrieval (IR) systems, preference, experience, and knowledge as well as limitation of the system design. A matrix of search-tactic transitions was created to show the probabilities of transitions from one tactic to another. By applying fifth-order Markov chain, the results also presented the most common search strategies representing patterns of tactic transition occurring at the beginning, middle, and ending phases within one search session. The results of this study generated detailed and useful guidance for IR system design to support the most frequently applied tactics and transitions, to reduce unnecessary transitions, and support transitions at different phases. [source] A comprehensive and systematic model of user evaluation of Web search engines: II.JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 13 2003An evaluation by undergraduates This paper presents an application of the model described in Part I to the evaluation of Web search engines by undergraduates. The study observed how 36 undergraduate used four major search engines to find information for their own individual problems and how they evaluated these engines based on actual interaction with the search engines. User evaluation was based on 16 performance measures representing five evaluation criteria: relevance, efficiency, utility, user satisfaction, and connectivity. Non-performance (user-related) measures were also applied. Each participant searched his/her own topic on all four engines and provided satisfaction ratings for system features and interaction and reasons for satisfaction. Each also made relevance judgements of retrieved items in relation to his/her own information need and participated in post-search interviews to provide reactions to the search results and overall performance. The study found significant differences in precision PR1, relative recall, user satisfaction with output display, time saving, value of search results, and overall performance among the four engines and also significant engine by discipline interactions on all these measures. In addition, the study found significant differences in user satisfaction with response time among four engines, and significant engine by discipline interaction in user satisfaction with search interface. None of the four search engines dominated in every aspect of the multidimensional evaluation. Content analysis of verbal data identified a number of user criteria and users evaluative comments based on these criteria. Results from both quantitative analysis and content analysis provide insight for system design and development, and useful feedback on strengths and weaknesses of search engines for system improvement. [source] Mining for robust transcriptional and metabolic responses to long-term salt stress: a case study on the model legume Lotus japonicusPLANT CELL & ENVIRONMENT, Issue 4 2010DIEGO H. SANCHEZ ABSTRACT Translational genomics, the use of model species to generate knowledge about biological processes and the functions of genes, offers great promise to biotechnologists. Few studies have sought robust responses of model plants to environmental stresses, such as salinity, by altering the stress dosage or by repeating experiments in consecutive years and/or different seasons. We mined our published and unpublished data on legume salt acclimation for robust system features at the ionomic, transcriptomic and metabolomic levels. We analysed data from the model legume Lotus japonicus, obtained through six independent, long-term, non-lethal salt stress experiments which were carried out over two consecutive years. Best possible controlled greenhouse conditions were applied and two main questions asked: how reproducible are results obtained from physiologically meaningful salinity experiments, and what degree of bias may be expected if conclusions are drawn from less well-repeated sampling? A surprisingly large fraction of the transcriptional and metabolic responses to salt stress were not reproducible between experiments. A core set of robust changes was found that was shared between experiments. Many of these robust responses were qualitatively and quantitatively conserved between different accessions of the same species, indicating that the robust responses may be a sound starting point for translational genomics. [source] Evolution of the reverse link of CDMA-based systems to support high-speed dataBELL LABS TECHNICAL JOURNAL, Issue 3 2002Nandu Gopalakrishnan Development of an upcoming release of the CDMA2000* family of standards is expected to focus on enhancing the reverse link (RL) operation to support high-speed packet data applications. The challenge is to design a system that yields substantial throughput gain while causing only minimal perturbations to the existing standard. We are proposing a system that evolves features already present in the CDMA2000 Release B and IS-856 (1xEV-DO) standards and reuses concepts and capabilities that have been introduced for high-speed packet data support on the forward link (FL) in Release C of the CDMA2000 standard. The RL of Release C of the CDMA2000 standard supports a relatively slow scheduled operation of this link using signaling messages. Scheduling with shorter latencies can be achieved by moving this functionality to the physical layer. Concurrently, both the FL and RL channel conditions may be tracked, and users may be scheduled based on this knowledge. To further manage the power and bandwidth cost on the FL, that is, of scheduling users' transmissions on the RL, the mobile station (MS) is permitted to operate in either a scheduled mode or an autonomous mode. A capability is provided for the MS station to switch the mode of operation. Performance impact of, and gain from, some of the system features is characterized through simulation results. © 2003 Lucent Technologies Inc. [source] | ||||||||||