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Model Consisting (model + consisting)
Selected AbstractsModel consisting of ultrasonographic and simple blood indexes accurately identify compensated hepatitis B cirrhosisJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 8pt1 2008Yong-Peng Chen Abstract Background and Aim:, Several models for significant fibrosis or cirrhosis have been introduced for hepatitis C, but are seldom for hepatitis B. The present study retrospectively evaluates the relationship between ultrasonography, blood tests, and fibrosis stage, and constructs a model for predicting compensated cirrhosis. Methods:, A total of 653 patients with chronic hepatitis B who underwent liver biopsies, ultrasonographic scanning, and routine blood tests were retrospectively analyzed. The patients were divided into the model set and validation set. Blood tests and ultrasonographic indexes were analyzed statistically. An ultrasonographic scoring system consisting of liver parenchyma, gallbladder, hepatic vessel, and splenomegaly was introduced. Results:, There were significant differences between cirrhosis and other fibrosis stages in ultrasonographic indexes of liver parenchyma, gallbladder, hepatic vessel, and splenomegaly. Ultrasonographic scores were significantly different between F4 and other fibrosis, and significantly correlated with fibrosis stage. Apart from alanine aminotransferase and alkaline phosphatase, blood tests and patients' age were correlated with fibrosis, and were significantly different between patients with and without cirrhosis. The model for cirrhosis indexes consisting of ultrasonographic score, patient's age, and variables, including platelet, albumin, and bilirubin predicted cirrhosis with area under receiver,operator curve of 0.907 in the model set and 0.849 in the validation set. Using proper cut-off values, nearly 81% patients could be accurately assessed for the absence or presence of cirrhosis. Conclusion:, The model consisting of ultrasonographic score, patients' age, blood variables of platelet, albumin, and bilirubin can identify hepatitis B cirrhosis with a high degree of accuracy. The application of this model would greatly reduce the number of biopsies. [source] Combination of B-Type Natriuretic Peptide Levels and Non-Invasive Hemodynamic Parameters in Diagnosing Congestive Heart Failure in the Emergency DepartmentCONGESTIVE HEART FAILURE, Issue 4 2004Erin Barcarse BS This study aimed to assess whether the combination of a B-type natriuretic peptide (BNP) level with various noninvasive hemodynamic parameters can help physicians more quickly and accurately diagnose congestive heart failure and determine the type of left ventricular dysfunction present in patients presenting to the emergency department with dyspnea. Subjects were 98 men (aged 64.57±1.23 years) that presented to the VA San Diego Healthcare System. Hemodynamic parameters were measured using impedance cardiography, and BNP levels were quantified using a rapid immunoassay. All patients with a BNP <100 pg/mL (n=37) had no evidence of congestive heart failure 97% of the time. In those with a BNP >100 pg/mL (601 ±55 pg/mL; n=61), a cardiac index of 2.6 L/min/m2 is 65% sensitive and 88% specific in determining systolic dysfunction. In patients with a BNP >100 pg/mL, a multivariate model consisting of noninvasive hemodynamic measurements was able to predict cardiac deaths, readmissions, and emergency department visits within 90 days with 83% accuracy. The authors conclude that, in patients presenting to an emergency department with dyspnea, the addition of impedance cardiography measurements to BNP level measurements will more effectively diagnose congestive heart failure and determine both the type of heart dysfunction and the severity of illness. [source] Metacognition as a mediator of the effects of impairments in neurocognition on social function in schizophrenia spectrum disordersACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2010P. H. Lysaker Lysaker PH, Shea AM, Buck KD, Dimaggio G, Nicolò G, Procacci M, Salvatore G, Rand KL. Metacognition as a mediator of the effects of impairments in neurocognition on social function in schizophrenia spectrum disorders. Objective:, This study explored whether Mastery, a domain of metacognition that reflects the ability to use knowledge about mental states to respond to psychological challenges, mediated the effects of neurocognition on the frequency of social contact and persons' capacity for social relatedness. Method:, Participants were 102 adults with schizophrenia or schizoaffective disorder. Neurocognition was represented by a single factor score produced by a principal components analysis of a neurocognitive test battery. Mastery was assessed using the metacognitive assessment scale and social functioning by the quality of life scale. Results:, Using structural equation modeling, specifically measured-variable path analysis, a mediational model consisting of neurocognitive capacity linked to mastery and capacity for social relationships and mastery linked with frequency of social contact and capacity for social relatedness showed acceptable fit to the observed data. This persisted after controlling for negative and cognitive symptoms. Conclusion:, Results suggest that certain forms of metacognition mediate the influence of neurocognition upon function in schizophrenia. [source] Integrated Enzymatic Synthesis and Adsorption of Isomaltose in a Multiphase Fluidized Bed ReactorENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2006M. Ergezinger Abstract Dextransucrase catalyzes the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. A process on a technical scale with immobilized enzyme was established to produce isomaltose, a disaccharide of industrial interest. Isomaltose is also a reactant for dextransucrase and has to be quickly taken out of the reaction solution. This was realized by integrated adsorption of isomaltose on zeolites. In the case of biotransformation the reactor works with a fluidized bed of immobilized enzyme and the in situ separation is realized with a suspension flow of adsorbent. This process was investigated experimentally and theoretically. With a design model consisting of hydrodynamics, kinetics of enzymatic synthesis, and thermodynamics of adsorption, a comparison was made between experimental and calculated data. [source] Stability Constants and Dissociation Rates of the EDTMP Complexes of Samarium(III) and Yttrium(III)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008Ferenc Krisztián Kálmán Abstract The stability constants of Sm(EDTMP) (log,KML = 20.71) and Y(EDTMP) (log,KML = 19.19) were determined by a competition reaction between the Ln3+ ion (Ln3+ = Sm3+ or Y3+) and Cu2+ for the EDTMP ligand by spectrophotometry at pH , 10, in the presence of an excess amount of citrate (0.15 M NaCl, 25 °C). For determining the stability constants of Cu(EDTMP) (log,KML = 19.36) and Ca(EDTMP) (log,KML = 8.71) pH,potentiometry was used. In the pH range 4,9 the EDTMP complexes are present in the form of nonprotonated and mono-, di- and triprotonated species. The Ca2+ ion forms a dinuclear complex with Ln(EDTMP). In a simplified blood plasma model consisting of Sm3+, Ca2+ and Zn2+ metal ions, EDTMP, citrate, cysteine and histidine ligands, Sm3+ is practically present in the form of [Sm(HEDTMP)Ca]2,, whereas Zn2+ predominantly forms [Zn(HEDTMP)]5, and [Zn(H2EDTMP)]4, complexes. For studying the dissociation rates of the complexes, the kinetics of the metal exchange (transmetallation) reactions between the Ln(EDTMP) complexes and Cu2+,citrate were investigated in the pH range 7,9 by the stopped-flow method. The rates of the exchange reactions are independent of the Cu2+ concentration and increase with the H+ concentration. The rate constants, characterizing the proton-assisted dissociation of the Ln(EDTMP) complexes, are several orders of magnitude higher than those of the similar Ln(EDTA) complexes, because the protonation constants of Ln(EDTMP) are high and the protonated Ln(HEDTMP) and Ln(H2EDTMP) species are present in higher concentration. The half-times of dissociation of Sm(EDTMP) and Y(EDTMP) at pH = 7.4 and 25 °C are 4.9 and 7.5 s, respectively. These relatively short dissociation half-time values do not predict the deposition of Ln3+ ions in bones in the form of intact Ln(EDTMP) complexes. It is more probable that sorption of the EDTMP ligand and Sm3+ or Y3+ ions occurs independently after the dissociation of complexes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Professional burnout and work engagement among dentistsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2007Hans Te Brake A recent development within burnout research is the shift to its conceptual opposite: work engagement. This study aimed to unravel the concepts of burnout and work engagement, and to determine their levels among dentists. A representative sample of 497 Dutch general dental practitioners was included (survey response rate of 59%), consisting of 372 men and 121 women (the gender of 4 dentists remained unknown). The hypothesized three-factor structure of work engagement (vigor, dedication, and absorption), as measured by the Utrecht Work Engagement Scale (UWES), was substantiated among dentists. It was also found that work engagement was related negatively to burnout, as measured by the Maslach Burnout Inventory (MBI). However, a model consisting of a reduced (,core') burnout factor and an ,enhanced' engagement factor (composed of the three original factors plus the burnout factor, personal accomplishment) showed the best fit. Overall burnout levels among dentists are low, and the levels of engagement indicate that dentists have a positive working attitude. [source] The role of metabolic memory in the ATP paradox and energy homeostasisFEBS JOURNAL, Issue 21 2008Juan C. Aledo In yeast, a sudden transition from glucose limitation to glucose excess leads to a new steady state at increased metabolic fluxes with a sustained decrease in the ATP concentration. Although this behaviour has been rationalized as an adaptive metabolic strategy, the mechanism behind it remains unclear. Nevertheless, it is thought that, on glucose addition, a metabolite derived from glycolysis may up-regulate ATP-consuming reactions. The adenine nucleotides themselves have been ruled out as the signals that mediate this regulation. This is mainly because, in that case, it would be expected that the new steady state at increased fluxes would be accompanied by an increased stationary ATP concentration. In this study, we present a core model consisting of a monocyclic interconvertible enzyme system. Using a supply,demand approach, we demonstrate that this system can account for the empirical observations without involving metabolites other than the adenine nucleotides as effectors. Moreover, memory is an emerging property of such a system, which may allow the cell to sense both the current energy status and the direction of the changes. [source] A transportable mb(Lg) scale for central Europe and implications for low-magnitude Ms,mb discriminationGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2005Howard J. Patton SUMMARY We have extended the mb(Lg) method of Nuttli using root-mean-square (rms) amplitudes corrected for noise and a ,,1 dependence for geometrical spreading. Lg waves recorded on the German Regional Seismic Network (GRSN) for earthquakes in south-central Europe were used to develop an mb(Lg) formula requiring a new calibration constant Crms to keep rms mb(Lg) on the same baseline as Nuttli's traditional formula based on 3rd-peak amplitudes. GRSN stations had to be calibrated for site terms and for Lg attenuation. Lateral variations in LgQ appear to be significant across the study area, and a regional Q model consisting of constant- Q partitions north, south and in the central Alps was developed using measurements based on interstation and two-event, single-station methods. When plotted against surface wave estimates of Mw, rms mb(Lg) measurements in central Europe are found to be consistent with Mw,mb(Lg) relationships for north America and southern Asia, thus supporting the transportability of our mb(Lg) formula. Frequency,wavenumber processing of Gräfenberg Array data enabled us to extract Rayleigh waves for small events, and regional Ms were measured using the Marshall and Basham formula. Our Ms,mb(Lg) relationship extends to Ms 2.5 and agrees well with observations in other regions including the western United States. The discrimination potential of Ms,mb(Lg) observations was examined under realistic monitoring conditions, where path corrections were inferred from earthquake data and applied uniformly to natural sources and explosions. Under these conditions, mb(Pn, P) are greater than mb(Lg) for large NTS explosions; however, Ms,mb scaling slopes are steeper for P waves than they are for Lg, and Ms,mb observations for NTS explosions converge near mb 4. Thus, allowing for measurement errors and additional uncertainty in mb(Pn) due to regional bias, there is little difference in the discrimination potential for Pn and Lg waves at small magnitudes. As such, a regional Ms,mb discriminant based on Lg might be preferred owing to the better detectability of Lg waves for small earthquakes. These results need to be confirmed for explosions at other test sites. Compared to teleseismic experience, regional Ms,mb observations extend the discrimination capability to lower magnitudes by at least one Ms unit. [source] Relationship of serum fibrosis markers with liver fibrosis stage and collagen content in patients with advanced chronic hepatitis C,HEPATOLOGY, Issue 3 2008Robert J. Fontana This study determined the utility of a panel of serum fibrosis markers along with routine laboratory tests in estimating the likelihood of histological cirrhosis in a cohort of prior nonresponders with chronic hepatitis C. The relationship between serum markers and quantitative hepatic collagen content was also determined. Liver biopsy samples from 513 subjects enrolled in the HALT-C trial were assigned Ishak fibrosis scores. The collagen content of 386 sirius-red stained, nonfragmented biopsy samples was quantified using computerized morphometry. Serum tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), amino-terminal peptide of type III procollagen (PIIINP), hyaluronic acid (HA), and YKL-40 levels were determined using commercially available assays. Sixty-two percent of patients had noncirrhotic fibrosis (Ishak stage 2-4) whereas 38% had cirrhosis (Ishak stage 5,6). Multivariate analysis identified a 3-variable model (HA, TIMP-1, and platelet count) that had an area under the receiver operating curve (AUROC) of 0.81 for estimating the presence of cirrhosis. This model was significantly better than that derived from the cirrhosis discriminant score (AUROC 0.70), the AST-to-platelet ratio (AUROC 0.73), and a prior model developed in HALT-C patients (AUROC 0.79). Multivariate analysis demonstrated that the serum fibrosis markers correlated substantially better with Ishak fibrosis scores than with the log hepatic collagen content (AUROC 0.84 versus 0.72). Conclusion: A 3-variable model consisting of serum HA, TIMP-1, and platelet count was better than other published models in identifying cirrhosis in HALT-C Trial subjects. The stronger correlation of the serum markers with Ishak scores suggests that serum fibrosis markers reflect the pattern of fibrosis more closely than the quantity of hepatic collagen. (HEPATOLOGY 2008.) [source] A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis CHEPATOLOGY, Issue 2 2003Chun-Tao Wai Information on the stage of liver fibrosis is essential in managing chronic hepatitis C (CHC) patients. However, most models for predicting liver fibrosis are complicated and separate formulas are needed to predict significant fibrosis and cirrhosis. The aim of our study was to construct one simple model consisting of routine laboratory data to predict both significant fibrosis and cirrhosis among patients with CHC. Consecutive treatment-naive CHC patients who underwent liver biopsy over a 25-month period were divided into 2 sequential cohorts: training set (n = 192) and validation set (n = 78). The best model for predicting both significant fibrosis (Ishak score , 3) and cirrhosis in the training set included platelets, aspartate aminotransferase (AST), and alkaline phosphatase with an area under ROC curves (AUC) of 0.82 and 0.92, respectively. A novel index, AST to platelet ratio index (APRI), was developed to amplify the opposing effects of liver fibrosis on AST and platelet count. The AUC of APRI for predicting significant fibrosis and cirrhosis were 0.80 and 0.89, respectively, in the training set. Using optimized cut-off values, significant fibrosis could be predicted accurately in 51% and cirrhosis in 81% of patients. The AUC of APRI for predicting significant fibrosis and cirrhosis in the validation set were 0.88 and 0.94, respectively. In conclusion, our study showed that a simple index using readily available laboratory results can identify CHC patients with significant fibrosis and cirrhosis with a high degree of accuracy. Application of this index may decrease the need for staging liver biopsy specimens among CHC patients. [source] Perceived purposes of performance appraisal: Correlates of individual- and position-focused purposes on attitudinal outcomesHUMAN RESOURCE DEVELOPMENT QUARTERLY, Issue 3 2007Satoris S. Youngcourt Performance appraisals have traditionally been directed at individuals, serving either an administrative or developmental purpose. They may serve a role definition purpose as well. This study sought to identify and more broadly define the purposes of performance appraisals to include this role definition purpose. Furthermore, this study examined purposes of performance appraisals as perceived by the role incumbent, as opposed to the stated organizational purposes. The relationships between these perceived purposes with several attitudinal outcomes, including satisfaction with the performance appraisal, job satisfaction, affective commitment, and role ambiguity, are reported. Data from 599 retail service employees were used to test the hypothesized relationships. Results suggested support for a model consisting of three performance appraisal purposes having differential relationships with the outcomes examined, suggesting the purpose of the performance appraisal may influence ratees' perceptions of and attitudes toward their jobs. [source] Modelling and optimization of district heating and industrial energy system,an approach to a locally deregulated heat marketINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2004Alemayehu Gebremedhin Abstract Regions with densely concentration of industries and district heating systems (DHS) could be interesting study object from the light of an integrated heat market on local basis. System analysis with a widened system boundary could be used as an approach to evaluate the benefit of an integrated heat supply system. In this study, an energy system model consisting of totally seven different participants is designed and the optimization results of the system analysis are presented. With applied data and assumptions, the study shows that a significant amount of the heat demand within two sub-systems can be covered by heat supply from the heat market (the entire heat comes from two industries). Shadow prices, which can be used for heat pricing, indicate the advantage of an integrated system. The system cost reduction through integration and the availability of several actors with diverse energy supply system, makes the region under study an interesting area to prove a locally deregulated heat market. Copyright © 2004 John Wiley & Sons, Ltd. [source] Local atomic structure in tetragonal pure ZrO2 nanopowdersJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2010Leandro M. Acuña The local atomic structures around the Zr atom of pure (undoped) ZrO2 nanopowders with different average crystallite sizes, ranging from 7 to 40,nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2 nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr,O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye,Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to the z direction; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments. [source] Initial biofilm formation of Streptococcus sobrinus on various orthodontics appliancesJOURNAL OF ORAL REHABILITATION, Issue 11 2004D. Steinberg summary, Biofilms accumulate on hard and soft surface in the oral cavity. Accumulation of biofilms on orthodontic appliance bear scientific and clinical interest. The objection of this study was to examine the formation of dental biofilm by Streptococcus sobrinus on different types of orthodontics appliances, using a model consisting of host and bacterial constituents. The adsorption pattern of saliva to the orthodontics appliances was determined by means of gel electrophoresis coupled with computerized densitometry techniques. The amount of salivary proteins adsorbed onto the surfaces was measured using the Bradford method. Sucrose-dependent bacterial adhesion to the saliva-coated orthodontics appliances was tested by radioactive-labelled S. sobrinus. Our results show different adsorption patterns of salivary proteins to the various orthodontic appliances as modules, brackets, springs and intra oral elastics. Modules and brackets demonstrated the most affinity to salivary proteins. A surface dependent adhesion profile was recorded, showing a high affinity of albumin and amylase to modules. Bacterial accumulation was the highest on modules compared with springs which demonstrated the least bacterial adhesion. Our study demonstrates the specificity of biofilm formation on the different orthodontic appliances. Formation of a variety of dental biofilms has a significant impact on the progression of dental diseases associated with orthodontic treatment. [source] Using Difference-Based Methods for Inference in Regression with Fractionally Integrated ProcessesJOURNAL OF TIME SERIES ANALYSIS, Issue 6 2007Wen-Jen Tsay Abstract., This paper suggests a difference-based method for inference in the regression model involving fractionally integrated processes. Under suitable regularity conditions, our method can effectively deal with the inference problems associated with the regression model consisting of nonstationary, stationary and intermediate memory regressors, simultaneously. Although the difference-based method provides a very flexible modelling framework for empirical studies, the implementation of this method is extremely easy, because it completely avoids the difficult problems of choosing a kernel function, a bandwidth parameter, or an autoregressive lag length for the long-run variance estimation. The asymptotic local power of our method is investigated with a sequence of local data-generating processes (DGP) in what Davidson and MacKinnon [Canadian Journal of Economics. (1985) Vol. 18, pp. 38,57] call ,regression direction'. The simulation results indicate that the size control of our method is excellent even when the sample size is only 100, and the pattern of power performance is highly consistent with the theoretical finding from the asymptotic local power analysis conducted in this paper. [source] Mathematical modeling of 980-nm and 1320-nm endovenous laser treatmentLASERS IN SURGERY AND MEDICINE, Issue 3 2007Serge R. Mordon PhD Abstract Background and Objectives Endovenous laser treatment (ELT) has been proposed as an alternative in the treatment of reflux of the great saphenous vein (GSV) and small saphenous vein (SSV). Numerous studies have since demonstrated that this technique is both safe and efficacious. ELT was presented initially using diode lasers of 810 nm, 940 nm, and 980 nm. Recently, a 1,320-nm Nd:YAG laser was introduced for ELT. This study aims to provide mathematical modeling of ELT in order to compare 980 nm and 1,320 nm laser-induced damage of saphenous veins. Study Design/Materials and Methods The model is based on calculations describing light distribution using the diffusion approximation of the transport theory, the temperature rise using the bioheat equation, and the laser-induced injury using the Arrhenius damage model. The geometry to simulate ELT was based on a 2D model consisting of a cylindrically symmetric blood vessel including a vessel wall and surrounded by an infinite homogenous tissue. The mathematical model was implemented using the Macsyma-Pdease2D software (Macsyma, Inc., Arlington, MA). Calculations were performed so as to determine the damage induced in the intima tunica, the externa tunica and inside the peri-venous tissue for 3 mm and 5 mm vessels (considered after tumescent anesthesia) and different linear endovenous energy densities (LEED) usually reported in the literature. Results Calculations were performed for two different vein diameters: 3 mm and 5 mm and with LEED typically reported in the literature. For 980 nm, LEED: 50 to 160 J/cm (CW mode, 2 mm/second pullback speed, power: 10 W to 32 W) and for 1,320 nm, LEED: 50 to 80 J/cm (pulsed mode, pulse duration 1.2 milliseconds, peak power: 135 W, repetition rate 30 Hz to 50 Hz). Discussion and Conclusion Numerical simulations are in agreement with LEED reported in clinical studies. Mathematical modeling shows clearly that 1,320 nm, with a better absorption by the vessel wall, requires less energy to achieve wall damage. In the 810,1,320-nm range, blood plays only a minor role. Consequently, the classification of these lasers into hemoglobin-specific laser wavelengths (810, 940, 980 nm) and water-specific laser wavelengths (1,320 nm) is inappropriate. In terms of closure rate, 980 nm and 1,320 nm can lead to similar results and, as reported by the literature, to similar side effects. This model should serve as a useful tool to simulate and better understand the mechanism of action of the ELT. Lasers Surg. Med. 39:256,265, 2007. © 2007 Wiley-Liss, Inc. [source] Relativistic ionized accretion disc models of MCG,6-30-15MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2001D.R. Ballantyne We present results from fitting of ionized accretion disc models to three long ASCA observations of the Seyfert 1 galaxy MCG,6-30-15. All three data sets can be fitted by a model consisting of ionized reflection from the inner region of the accretion disc (with twice solar Fe abundance) and a separate disc-line component from farther out on the disc. The disc-line is required to fit the height of the observed Fe K, line profile. However, we show that a much simpler model of reflection from a very weakly ionized constant-density disc also fits the data. In this case only a single cold Fe K, line at 6.4 keV is required to fit the observed line. The ionized disc models predict that O viii K,, C vi K,, Fe xvii L, and Fe xviii L, lines will appear in the soft X-ray region of the reflection spectrum, but are greatly blurred as a result of Compton scattering. The equivalent width (EW) of O viii K, is estimated to be about 10 eV and seems to be as strong as the blend of the Fe L lines. This result creates difficulty for the claim of a strong relativistic O viii line in the XMM - Newton grating spectrum of MCG,6-30-15, although we cannot strictly rule it out since MCG,6-30-15 was in an anomalously low state during that observation. We find that increasing the O abundance or breaking the continuum below 2 keV will not significantly strengthen the line. The second Fe K, line component in the ionized disc model may arise from neutral reflection from a flared disc, or from a second illumination event. The data cannot distinguish between the two cases, and we conclude that single-zone ionized disc models have difficulty fitting these hard X-ray data of MCG,6-30-15. [source] Observation of developmental processes in loosely attached diatom (Bacillariophyceae) communitiesPHYCOLOGICAL RESEARCH, Issue 2 2000Akihiro Tuji SUMMARY The succession of attached algal communities was studied in Lake Biwa and the Omiya River. After the ,climax' which was characterized by large numbers of Cymbella turgidula Grunow and Gomphoneis quadripunctatum (Østrup) P. Dawson, the community was dominated by species attached directly to stalks or tangled among stalks. Stalks produced by species of the previous phase are important as secondary substrata. The dominant species of the new phase were ,loosely attached species', as defined by Hudon and Bourget (1983). I propose a new model consisting of phase 1, characterized by the first colonizers, including large rosette-type species and motile type species; phase 2, characterized by the stalk-producing species; and phase 3, characterized by the growth of loosely attached species. [source] Modeling of spatially inhomogeneous solar cells by a multi-diode approachPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2005P. O. Grabitz Abstract An equivalent circuit model consisting of parallel connected diodes with different electronic quality simulates the electronic properties of solar cells with spatially inhomogeneous material quality. Variations of the local saturation current density result in a degradation of the open circuit voltage, the fill factor and, in consequence, of the overall power conversion efficiency. However, a local series resistance introduced into this network limits this degradation by preventing areas with high saturation current density to dominate the electronic losses of the entire device. Analyzing the integral current/voltage-curves of the networks shows the diode ideality larger than unity to result from resistive limitations to the spatially inhomogeneous current flow. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of temperature distribution and current crowding on the performance of lateral GaN-based light-emitting diodesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010Dongpyo Han Abstract Current crowding effect is detrimental for the performance of light-emitting diodes (LEDs), causing non-uniform light emission and local heat generation. In particular, heat generated by non-uniform current distribution can badly influence the performance of LED devices. In this paper, we examine the temperature distributions of lateral InGaN/GaN multiple-quantum-well LEDs in relation to current crowding, using both simulation and experimental results. Simulation results are obtained from a 3-dimensional electrical circuit model consisting of resistances and intrinsic diodes. Temperature and luminance distributions are investigated by images taken by an infrared camera and a charge-coupled-device camera, respectively. Finally, the internal quantum efficiency is taken for each device and compared. We show that the thermal property in the lateral LED is affected by the current crowding due to the local Joule heating nearby electrodes. Therefore, uniform current spreading is very important not only for uniform luminance distribution but also for good thermal property in the LED device. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Confirmatory factor analysis of the KABC-II in preschool children,PSYCHOLOGY IN THE SCHOOLS, Issue 6 2009Kimberly E. Morgan The present study assessed the Kaufman Assessment Battery for Children, Second Edition (KABC-II) in relation to the synthesized Cattell,Horn,Carroll (CHC) theory of intelligence with a preschool sample. Participants were 200 preschool children between four and five years of age. A confirmatory factor analysis (CFA) was conducted, and different variations of the CHC model were examined to determine which provided the best representation of the proposed underlying CHC constructs tested by the KABC-II. The models included one similar to Spearman's g, a contemporary two-stratum model consisting of fluid and crystallized intelligence (Gf-Gc model), and a synthesized CHC broad factor +g model. The last was the empirically validated theory of interest in this study. Results of the CFA revealed that the broad factor +g CHC model was the best overall design to explain KABC-II results. © 2009 Wiley Periodicals, Inc. [source] Mathematical Modelling of Non-Isothermal Venturi ScrubbersTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2005Amir Rahimi Abstract A mathematical model consisting of differential equations for energy, momentum and material exchange is developed for a non-isothermal Venturi-type scrubber. By this model, the effects of heat and mass transfer on droplets concentration distribution and removal efficiency of particulate in a non-isothermal Venturi scrubber can be investigated. In order to approach a realistic model, the liquid film flow on the walls and droplet size distribution are considered. The model is validated by comparing the results of mathematical model by plant and experimental data reported in the literature. The Results section of this work reveals that the inlet humidity and temperature of the gas can affect the removal efficiency of the scrubber. On a mis au point un modèle d'équations différentielles pour l'échange d'énergie, de quantité de mouvement et de matière pour un épurateur venturi non isotherme. Grâce à ce modèle, on peut étudier les effets du transfert de chaleur et de matière sur la distribution de concentration des gouttelettes et l'efficacité de retrait des particules dans un épurateur venturi non isotherme. Pour s'approcher le plus possible d'un modèle réaliste, l'écoulement liquide sur les parois et la distribution de taille des gouttelettes sont considérés. Le modèle est validé en comparant les résultats du modèle mathématique à des données expérimentales parues dans la littérature scientifique et des données d'usine. Les résultats de ce travail révèlent que l'humidité et la température de gaz à l'entrée peuvent influer sur l'efficacité de retrait de l'épurateur. [source] Analysis of Specific Absorption Rate and Current Density in Biological Tissues Surrounding Energy Transmission Transformer for an Artificial Heart: Using Magnetic Resonance Imaging-based Human Body ModelARTIFICIAL ORGANS, Issue 1 2010Naoya Higaki Abstract The transcutaneous energy transmission system used for artificial hearts is a transmission system that uses electromagnetic induction. Use of the TETS improves quality of life and reduces the risk of infection caused by percutaneous connections. This article reports the changes in the electromagnetic effects of TETS that influence a human body when the locations of the air-core coils of the transcutaneous transformer are changed. The specific absorption rate and current density in a model consisting of a human trunk that included 24 different organs are analyzed using an electromagnetic simulator. The air-core coils are located on the pectoralis major muscle near the collarbone in model 1, whereas they are located on the axillary region of the serratus anterior musle, which overlies the rib in model 2. The maximum current densities in models 1 and 2 are 5.2 A/m2 and 6.1 A/m2, respectively. The current density observed in model 2 slightly exceeds the limiting value prescribed by International Commission on Non-Ionizing Radiation Protection (ICNIRP). When the volumes of biological tissues whose current densities exceed the limiting value of current density for general public exposure are compared, the volume in model 2 (156.1 cm3) is found to be larger than that in model 1 (93.7 cm3). Hence, it is speculated that the presence of the ribs caused an increase in the current density. Therefore, it is concluded that model 1 satisfies the ICNIRP standards. [source] | ||||||||||||||||||||||