Home About us Contact
|
Home About us Contact | ||
|
|
||
Individual Parameters (individual + parameter)
Selected AbstractsKinetic and Statistical Studies of Adsorptive Desulfurization of Diesel Fuel on Commercial Activated CarbonsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2008M. Muzic Abstract Diesel fuel desulfurization by different commercial activated carbons was studied in a batch adsorber. Experiments, carried out to determine the sulfur adsorption dependency on time, were used to perform kinetic characterization and to screen the best performing activated carbon. The equilibrium characterization of the adsorption process was also performed. The statistical study of the process was undertaken by way of a two-level one-half fractional factorial experimental design with five process parameters. Individual parameters and their interaction effects on sulfur adsorption were determined and a statistical model of the process was developed. Chemviron Carbon SOLCARBTM C3 was found to be the most efficient adsorbent. The kinetic pseudo-second order model and Freundlich isotherm are shown to exhibit the best fits of experimental data. The lowest achieved sulfur concentration in treated diesel fuel was 9.1,mg kg,1. [source] Analysis of rainfall-runoff relation in paddy fields by diffusive tank modelHYDROLOGICAL PROCESSES, Issue 13 2003Rong-Song Chen Abstract Due to the occurrence of ponding during the period of rice growth, the analyses of rainfall-runoff in paddy fields are different from those in general lands. The diffusive tank model has been successfully applied in rainfall-runoff simulations in paddy fields because it can well describe the features of the local water flow. In most of the applications of this model, although the determination of the related model parameters is important, detailed investigations on each individual parameter are definitely needed to improve the accuracy of the results. In the study, an improved procedure is proposed to determine certain variables involved in the diffusive tank model and the application is conducted in a field area in Taiwan. In the application, the roughness of the river channel was assessed according to the actual field conditions. Instead of using the observed water levels in each rainfall event, the notch width of the rectangular contracted weir per unit area was evaluated by direct field measurements to calibrate the discharge coefficient. Test results from the selected field in six rainfall events showed that the local average value of the notch width of the rectangular contracted weir per unit area was 1·025 m/ha. Compared to the results of field measurements, the relative errors of the predictions were within 3% in all tests of rainfall events. In addition, for different types of catchment partitions, it was found that the corresponding weir discharge coefficients remained roughly unchanged. Copyright © 2003 John Wiley & Sons, Ltd. [source] Prognostic Indicators of Occult Metastases in Oral CancerTHE LARYNGOSCOPE, Issue 7 2002Mario Russolo MD Abstract Objective We evaluated the importance of several tumor factors related to predicting the presence of occult metastases in the oral cavity. Study Design Retrospective case study. Methods The study comprises 29 patients treated at the Department of Otorhinolaryngology (University of Trieste, Cattinara Hospital, Trieste, Italy) between January 1990 and December 2000, who had T1-T2 carcinoma of the oral cavity that had or had not extended to the oropharynx and were clinically evaluated as N0 neck. The patients all underwent surgery with removal of tumor and neck dissection. Four tumor-related parameters were examined with the aim of evaluating their predictivity of metastasis: tumor class, degree of keratinization, degree of differentiation according to Brooler's histopathological grading, and invasive cell grading (ICG). With the exception of tumor class, these parameters were evaluated both in the biopsy and in the surgical specimen and the findings were then compared. We evaluated existing correlations between each individual parameter and the histopathological presence of micrometastases (pN+) and extracapsular spread revealed when specimens from the neck were examined. Results There was a highly significant correlation between ICG equal to or greater than 13 (range, 5,20) and the presence of occult metastases (P = .0017). On the basis of our findings, the ICG parameter correctly identified 9 of 10 (pN+) patients and could have reduced overtreatment from 65.5% to 17.2% in histopathologically negative necks (pN0). Conclusion It would appear that with a delay in programming a neck dissection so as to consider ICG in combination with thickness, as in seven recent patients, identification of locoregional occult metastases (pN+) might be more precise. [source] Board Structure, Process and Performance: evidence from public-listed companies in SingaporeCORPORATE GOVERNANCE, Issue 2 2005David Wan Past literature in board research has centred on board structure and company performance. Over the years, empirical studies do not reveal a conclusive relationship between these two variables (Dalton and Daily, 1999. Across the Board, March, 28,32). Until recently, the literature on board processes has been sparse. The reason for insufficient empirical work on board processes possibly is due to the difficulty of gaining access to boards. In this paper, we propose a conceptual model and tested the model on publicly listed companies in Singapore. Based on a sample of 212 company responses and 299 directors, we conclude that board structure does not affect board process while board process is related to board performance. In terms of individual parameters, effort norms, cognitive conflict and the presence and usage of skills are positively related to board roles and board transparency. Also, affective and process conflicts are negatively related to board roles and board transparency. Finally, board process does not mediate the relationship between board structure and board performance. [source] Can a Novel Echocardiographic Score Better Predict Outcome after Percutaneous Balloon Mitral Valvuloplasty?ECHOCARDIOGRAPHY, Issue 2 2009Osama Rifaie M.D. Objective: The assessment of patients with mitral stenosis before percutaneous balloon mitral valvuloplasty (PBMV) is crucial to predict outcome after the procedure. We tried to explore the prognostic power of a novel echocardiographic score to predict immediate postprocedural outcome in comparison to the standard score. Methods: We enrolled 50 consecutive patients with moderate to severe mitral stenosis admitted to undergo PBMV. For all patients, we assessed both the standard Massachusetts General Hospital (MGH) score and a novel score based on calcification (especially commissural) and subvalvular involvement. Patients underwent PBMV with the double balloon technique. Thereafter, patients were classified into two groups: group 1 (poor outcome) defined as no procedural success and/or increase of MR by more than 1 grade and group 2 (optimal outcome) defined as procedural success with increase of MR by 1 grade or less. Results: The total MGH score did not differ significantly between the two groups. However, among the individual parameters of the score, both calcification and subvalvular affection were significantly higher in group 1 versus group 2 (2.8 ± 0.4 versus 1.7 ± 0.8, and 2.4 ± 0.5 versus 1.6 ± 0.4, respectively, P < 0.01 for both). The total novel score and its two individual parameters (calcification and subvalvular involvement) were all significantly higher in group 1 versus group 2 (6 ± 1.5 versus 2.9 ± 1.9, 4.9 ± 1.2 versus 2.4 ± 1.5, 1.5 ± 1.6 versus 0.5 ± 0.9, respectively, P < 0.01 for all). Multivariate analysis demonstrated the novel score to be the only independent predictor of poor outcome. Conclusion: The novel score is more reliable and correlates with outcome better than the standard score. [source] Hierarchical model of the population dynamics of hippocampal dentate granule cellsHIPPOCAMPUS, Issue 5 2002G.A. Chauvet Abstract A hierarchical modeling approach is used as the basis for a mathematical representation of the population activity of hippocampal dentate granule cells. Using neural field equations, the variation in time and space of dentate granule cell activity is derived from the summed synaptic potential and summed action potential responses of a population of granule cells evoked by monosynaptic excitatory input from entorhinal cortical afferents. In this formulation of the problem, we have considered a two-level hierarchy: the synapses of entorhinal cortical axons define the first level of organization, and dentate granule cells, which include these synapses, define the second, higher level of organization. The model is specified by two state field variables, for membrane potential and for synaptic efficacy, respectively, with both evolving according to different time scales. The two state field variables introduce new parameters, physiological and anatomical, which characterize the dentate from the point of view of neuronal and synaptic populations: (1) a set of geometrical constraints corresponding to the morphological properties of granule cells and anatomical characteristics of entorhinal-dentate connections; and (2) a set of neuronal parameters corresponding to physiological mechanisms. Assuming no interaction between granule cells, i.e., neither ephaptic nor synaptic coupling, the model is shown to be mathematically tractable and allows solution of the field equations leading to the determination of activity. This treatment leads to the definition of two state variables, volume of stimulated synapses and firing time, which describe observed activity. Numerical simulations are used to investigate the populational characterization of the dentate by individual parameters: (1) the relationship between the conditions of stimulation of active perforant path fibers, e.g., stimulating intensity, and activity in the granule cell layer; and (2) the influence of geometry on the generation of activity, i.e., the influence of neuron density and synaptic density-connectivity. As an example application of the model, the granule cell population spike is reconstructed and compared with experimental data. Hippocampus 2002;12:698,712. © 2002 Wiley-Liss, Inc. [source] Effect of conditioning electrical stimuli on temporalis electromyographic activity during sleepJOURNAL OF ORAL REHABILITATION, Issue 3 2008F. JADIDI Summary, Inhibitory reflexes during voluntary contractions are well described; however, few studies have attempted to use such reflex-mechanisms to modulate electromyographic (EMG) activity in jaw-closing muscles during sleep. The aim was to apply a new intelligent biofeedback device (Grindcare®) using electrical pulses to inhibit EMG activity in the temporalis muscle during sleep. Fourteen volunteers participated who were aware of jaw-clenching activity as indicated by complaints from sleep partner, soreness or pain in the jaw-muscle upon awakening and tooth wear facets. The EMG activity was recorded from the temporalis muscle, online analysed and the frequency content determined using a signal recognition algorithm. Based on specific individual parameters for pattern recognition, an electrical square-wave pulse train, which was adjusted to a clear, but non-painful intensity (range 1,7 mA) was applied through the EMG electrodes, if jaw-clenching activity was detected. All volunteers had baseline EMG recordings for five to seven consecutive nights, followed by 3-weeks EMG recordings with the feedback turned on, 2 weeks without the feedback and finally 3 weeks with the biofeedback on. There were no session effects on the average duration of sleep hours (P = 0·626). The number of EMG episodes/hour sleep was significantly reduced during the two sessions with biofeedback (54 ± 14%; 55 ± 17%, P < 0·001) compared with baseline EMG activity and the session without biofeedback. The present study suggests that biofeedback with electrical pulses does not cause major disruption in sleep and is associated with pronounced reduction in temporalis EMG activity during sleep. [source] Microbial contaminants in food: a big issue for a working group of the MoniQA NoE projectQUALITY ASSURANCE & SAFETY OF CROPS & FOOD, Issue 2 2009A. Hoehl Abstract Introduction The MoniQA Network of Excellence is an EC funded project working towards the harmonization of analytical methods for monitoring food quality and safety along the food supply chain. This paper summarises both the structure and tasks of the working group on microbial contaminants within the MoniQA NoE and specifically focuses on harmonisation strategies important in the microbiological analysis of food. Objectives There is a need for rapid microbiological methods in order to quickly and efficiently identify harmful pathogens in food sources. However, one of the major problems encountered with many new methods is their market acceptance, as they have to pass extensive validation/standardisation studies before they can be declared as official standard methods. Methods The working group on microbiological contaminants aims to contribute towards speeding up these prerequisites by collecting information on food law, quality assurance, quality control, sampling, economic impact, measurement uncertainty, validation protocols, official standard methods and alternative methods. Results The present report provides an overview of currently existing methodologies and regulations and addresses issues concerning harmonisation needs. One of the deliverables of the working group is the development of extended fact sheets and reviews based on relevant ,hot' topics and methods. The selection of food borne analytes for these fact sheets have been selected based on global, local and individual parameters. The working group has identified 5 groups of stakeholders (governmental bodies, standardisation/validation organisations, test kit/equipment manufacturers, food industry and consumers). Conclusion Current challenges of food microbiology are driven by new analytical methods, changes in the food market and altered consumer desires. The MoniQA NoE is contributing in overcoming these risks and challenges by providing a profound platform on microbiological rapid methods in food analysis to all stakeholders and it is expected that strong interaction within the network and beyond will foster harmonization. [source] Local stimulation of articular cartilage repair by transplantation of encapsulated chondrocytes overexpressing human fibroblast growth factor 2 (FGF-2) in vivo,THE JOURNAL OF GENE MEDICINE, Issue 1 2006Gunter Kaul Abstract Background Defects of articular cartilage are an unsolved problem in orthopaedics. In the present study, we tested the hypothesis that gene transfer of human fibroblast growth factor 2 (FGF-2) via transplantation of encapsulated genetically modified articular chondrocytes stimulates chondrogenesis in cartilage defects in vivo. Methods Lapine articular chondrocytes overexpressing a lacZ or a human FGF-2 gene sequence were encapsulated in alginate and further characterized. The resulting lacZ or FGF-2 spheres were applied to cartilage defects in the knee joints of rabbits. In vivo, cartilage repair was assessed qualitatively and quantitatively at 3 and 14 weeks after implantation. Results In vitro, bioactive FGF-2 was secreted, leading to a significant increase in the cell numbers in FGF-2 spheres. In vivo, FGF-2 continued to be expressed for at least 3 weeks without leading to differences in FGF-2 concentrations in the synovial fluid between treatment groups. Histological analysis revealed no adverse pathologic effects on the synovial membrane at any time point. FGF-2 gene transfer enhanced type II collagen expression and individual parameters of chondrogenesis, such as the cell morphology and architecture of the new tissue. Overall articular cartilage repair was significantly improved at both time points in vivo. Conclusions The data suggest that localized overexpression of FGF-2 enhances the repair of cartilage defects via stimulation of chondrogenesis, without adverse effects on the synovial membrane. These results may lead to the development of safe gene-based therapies for human articular cartilage defects. Copyright © 2005 John Wiley & Sons, Ltd. [source] Analytische Herleitung von Anforderungen an den Luftschallschutz zwischen RäumenBAUPHYSIK, Issue 4 2009Beratender Ingenieur VBI Wolfgang Moll Prof. Ing. Schall; Technische Regelwerke; sound protection and acoustics; technical recommendations Abstract Vor dem Hintergrund der Auseinandersetzungen um die Höhe des Schallschutzes der zurzeit überarbeiteten DIN 4109 "Schallschutz im Hochbau" befasst sich der Autor kritisch mit der bisherigen Art der Festlegung bauakustischer Anforderungen. In Anbetracht der fehlenden physikalischen Legitimation dieser Anforderungen , früher an die Schalldämmwerte, jetzt an die Schallschutzwerte , schlägt der Verfasser die gezielte Berechnung der nachhallzeitbezogenen Schallschutzanforderungen vor, und zwar auf der Basis allgemein bekannter Ausgangsdaten, wie z. B. der Schallleistung der einzelnen Quellen, der Verdeckung durch den Grundpegel etc. Das Verfahren wird ausführlich erläutert und beispielhaft erklärt. Für die Abstufungen Mindestschallschutz, erhöhter Schallschutz, hoher Schallschutz werden Basiswerte vorgeschlagen, die dann in die gezielte Bestimmung der Anforderungsgrößen einfließen. Analytical derivation of requirements for airborne sound insulation between rooms. Against the background of the debate about sound protection levels in the current revision of DIN 4109 "Sound insulation in buildings" the author critically examines the existing methodology for determining acoustic requirements. In view of the lack of physical legitimation of these requirements , previously sound insulation values, now sound protection values , the author proposes targeted calculation of reverberation-related sound protection requirements based on generally known basic data, including the sound power levels of individual sources, masking through background noise, etc. The technique is explained in detail and illustrated by means of examples. Basic values are proposed for minimum sound protection, increased sound protection and high sound protection, which are then used for determining the requirements for individual parameters. [source] | ||||||||||||||||