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Kinds of Obtained Terms modified by Obtained Selected AbstractsHaptic Cues for Image DisambiguationCOMPUTER GRAPHICS FORUM, Issue 3 2000G. Faconti Haptic interfaces represent a revolution in human computer interface technology since they make it possible for users to touch and manipulate virtual objects. In this work we describe a cross-model interaction experiment to study the effect of adding haptic cues to visual cues when vision is not enough to disambiguate the images. We relate the results to those obtained in experimental psychology as well as to more recent studies on the subject. [source] Case,Based Reasoning for Assessing Intelligent Transportation Systems BenefitsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2003Adel Sadek Existing transportation planning modeling tools have critical limitations with respect to assessing the benefits of intelligent transportation systems (ITS) deployment. In this article, we present a novel framework for developing modeling tools for quantifying ITS deployments benefits. This approach is based on using case,based reasoning (CBR), an artificial intelligence paradigm, to capture and organize the insights gained from running a dynamic traffic assignment (DTA) model. To demonstrate the feasibility of the approach, the study develops a prototype system for evaluating the benefits of diverting traffic away from incident locations using variable message signs. A real,world network from the Hartford area in Connecticut is used in developing the system. The performance of the prototype is evaluated by comparing its predictions to those obtained using a detailed DTA model. The prototype system is shown to yield solutions comparable to those obtained from the DTA model, thus demonstrating the feasibility of the approach. [source] Estimation of endogenous adenosine activity at adenosine receptors in guinea-pig ileum using a new pharmacological methodACTA PHYSIOLOGICA, Issue 2 2010K. F. Nilsson Abstract Aim:, Adenosine modulates neurotransmission and in the intestine adenosine is continuously released both from nerves and from smooth muscle. The main effect is modulation of contractile activity by inhibition of neurotransmitter release and by direct smooth muscle relaxation. Estimation of adenosine concentration at the receptors is difficult due to metabolic inactivation. We hypothesized that endogenous adenosine concentrations can be calculated by using adenosine receptor antagonist and agonist and dose ratio (DR) equations. Methods:, Plexus-containing guinea-pig ileum longitudinal smooth muscle preparations were made to contract intermittently by electrical field stimulation in organ baths. Schild plot regressions were constructed with 2-chloroadenosine (agonist) and 8-(p -sulfophenyl)theophylline (8-PST; antagonist). In separate experiments the reversing or enhancing effect of 8-PST and the inhibiting effect of 2-chloroadenosine (CADO) were analysed in the absence or presence of an adenosine uptake inhibitor (dilazep), and nucleoside overflow was measured by HPLC. Results:, Using the obtained DR, baseline adenosine concentration was calculated to 28 nm expressed as CADO activity, which increased dose dependently after addition of 10,6 m dilazep to 150 nm (P < 0.05). HPLC measurements yielded a lower fractional increment (80%) in adenosine during dilazep, than found in the pharmacological determination (440%). Conclusion:, Endogenous adenosine is an important modulator of intestinal neuro-effector activity, operating in the linear part of the dose,response curve. Other adenosine-like agonists might contribute to neuromodulation and the derived formulas can be used to calculate endogenous agonist activity, which is markedly affected by nucleoside uptake inhibition. The method described should be suitable for other endogenous signalling molecules in many biological systems. [source] Kinetic studies on the influence of temperature and growth rate history on crystal growthCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2008P. M. Martins Abstract Crystallization experiments of sucrose were performed in a batch crystallizer to study the effect of temperature and growth rate history on the crystal growth kinetics. In one of the growth methods adopted, the isothermal volumetric growth rate (RV) is determined as a function of supersaturation (S) at 35, 40 and 45 ºC. In the other, crystals are allowed to grow at constant supersaturation by automatically controlling the solution temperature as the solute concentration decreased. Using the latter method RV is calculated as the solution is cooled. The obtained results are interpreted using empirical, engineering and fundamental perspectives of crystal growth. Firstly, the overall activation energy (EA) is determined from the empirical growth constants obtained in the isothermal method. The concept of falsified kinetics, widely used in chemical reaction engineering, is then extended to the crystal growth of sucrose in order to estimate the true activation energy (ET) from the diffusion-affected constant, EA. The differences found in the isothermal and constant supersaturation methods are explained from the viewpoint of the spiral nucleation mechanism, taking into account different crystal surface properties caused by the growth rate history in each method. Finally, the crystal growth curve obtained in the batch crystallizer at 40 ºC is compared with the one obtained in a fluidized bed crystallizer at the same temperature. Apparently divergent results are explained by the effects of crystal size, hydrodynamic conditions and growth rate history on the crystallization kinetics of sucrose. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation of growth kinetics and morphology of sodium fluorosilicate ice-analogue crystals in solutions and gelsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007M. J. Krasi Abstract The effect of growth method (solution or gel growth) and growth conditions on the morphology of ice analogue crystals (sodium fluorosilicate) has been studied. Many habits typical for atmospheric ice crystals (hexagonal columns, plates, different types of stars or dendrites) were obtained during experiments. The dependence of growth rate of basal and prism faces of columnar crystals on supersaturation was measured for crystals growing by evaporation of solvent. The experiments establish evaporation rate and growth rate ranges at which appearance of certain types of crystals is most probable. The experiments have also shown that good quality sodium fluorosilicate crystals can be obtained in TMS gel. These crystals were significantly bigger than those obtained in solution. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects in B,doped KDP crystals irradiated with neutrons of large spectra energyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004G. Fischfeld Abstract The results obtained for the r63 electro-optic coefficient of B-doped and undoped KDP (KH2PO4) crystals irradiated with neutrons (including thermalized neutrons) produced by scattering of 30 Mev cyclotron protons on a target of Ta201, are presented and compared to those obtained for non-irradiated doped and undoped crystals. The B-doped (H3BO3, Na2B4O7 and Li2B4O7) crystals were obtained by the conventional growth method by temperature decrease with 1 wt % dopant concentration in solution. The thermal neutron flux was around , = 1. 1010 n/cm2 s. Pulses of ,15 ,s long, in damped oscillatory mode (V= 8 kV, ,=1.95 ,s) were used for the electro-optic measurements. A Pockels cell, a photomultiplier, a He-Ne laser (,=632.8 nm, 5 mW, linearly polarized) and a Tk 720 A oscilloscope complete the experimental setup. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Evaluation of a single-platform microcapillary flow cytometer for enumeration of absolute CD4+ T-lymphocyte counts in HIV-1 infected Thai patients,,CYTOMETRY, Issue 5 2007Kovit Pattanapanyasat Abstract Background: Various assays are used to enumerate peripheral blood absolute CD4+ T-lymphocytes. Flow cytometry is considered the gold standard for this purpose. However, the high cost of available flow cytometers and monoclonal antibody reagents make it difficult to implement such methods in the resource-poor settings. In this study, we evaluated a cheaper, recently developed single-platform microcapillary cytometer for CD4+ T-lymphocyte enumeration, the personal cell analyzer (PCA), from Guava® Technologies. Methods: CD4+ and CD8+ T-lymphocyte counts in whole blood samples from 250 HIV-1 infected Thais were determined, using a two-color reagent kit and the Guava PCA, and compared with the results obtained with two reference microbead-based methods from Becton Dickinson Biosciences: the three-color TruCOUNTÔ tube method and the two-color FACSCountÔ method. Statistical correlations and agreements were determined using linear correlation and Bland,Altman analysis. Results: Absolute CD4+ T-lymphocyte counts obtained using the Guava PCA method highly correlated with those obtained using TruCOUNT method (R2 = 0.95, mean bias +13.1 cells/,l, limit of agreement [LOA] ,101.8 to +168.3 cells/,l). Absolute CD8+ T-lymphocyte counts obtained using the Guava PCA method also highly correlated with those obtained with the two reference methods (R2 = 0.92 and 0.88, respectively). Conclusion: This study shows that the enumeration of CD4+ T-lymphocytes using the Guava microcapillary cytometer PCA method performed well when compared with the two reference bead-based methods. However, like the two reference methods, this new method needs substantial technical expertise. © 2007 Clinical Cytometry Society. [source] Cell blocks allow reliable evaluation of expression of basal (CK5/6) and luminal (CK8/18) cytokeratins and smooth muscle actin (SMA) in breast carcinomaCYTOPATHOLOGY, Issue 4 2010W. D. Delgallo W. D. Delgallo, J. R. P. Rodrigues, S. P. Bueno, R. M. Viero and C. T. Soares Cell blocks allow reliable evaluation of expression of basal (CK5/6) and luminal (CK8/18) cytokeratins and smooth muscle actin (SMA) in breast carcinoma Objective:, Gene expression studies have revealed several molecular subtypes of breast carcinoma with distinct clinical and biological behaviours. DNA microarray studies correlated with immunohistochemical profiling of breast carcinomas using cytokeratin (CK) markers, Her2/neu, oestrogen receptor (ER), and basal myoepithelial cell markers have identified five breast tumour subtypes: (i) luminal A (ER+; Her2/neu,), (ii) luminal B (ER+; Her2/neu+), (iii) Her2 overexpression (ER,; Her2/neu+), (iv) basal-like (ER,; Her2/neu,, CK5/6 and 14+), and (v) negative for all markers. Luminal carcinomas express cytokeratins in a luminal pattern (CK8/18), and the basal-like type expresses CK5/6 and CK14 or basal epithelial cell markers. CK5/6, CK8/18, and smooth muscle actin (SMA) expression were assessed in cell blocks and compared with expression in surgical specimens. Methods:, Sixty-two cases of breast carcinoma diagnosed by fine needle aspiration cytology with cell blocks and available surgical specimens were included. Cell blocks containing at least 10 high-power fields each with at least 10 tumour cells and surgical specimens were immunostained for CK5/6, CK8/18 and SMA. Results:, Percentage sensitivity, specificity, positive predictive value, negative predictive value and accuracy were, respectively, 77, 100, 100, 92 and 94 for CK5/6; 98, 66, 96, 80 and 95 for CK8/18; and 92, 96, 85, 98 and 95 for SMA. Conclusion:, The identification of CK5/6, CK8/18 and SMA by immunohistochemistry in cell blocks can be a reliable method that yields results close to those obtained in surgical specimens, and can contribute to the classification of breast carcinomas with luminal and basal expression patterns, providing helpful information in the choice of treatment and in the evaluation of prognostic and predictive factors. [source] Beneficial effects of aminoguanidine on the cardiovascular system of diabetic ratsDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2005Krisztián Stadler Abstract Background The study focused on investigating the effect of aminoguanidine on cardiovascular damages in diabetes and the possible mechanisms of its action. Methods Aminoguanidine (AMNG) was used to treat streptozotocin-induced diabetic rats, and the effects were compared to those obtained under insulin treatment. Blood metabolic parameters, ,NO and ONOO, as well as protein carbonyl levels and cardiac hypertrophy were determined. Results Diabetic animals showed increased ,NO levels and markedly increased ONOO, generation in the aorta, along with a significant hypertrophy and protein carbonylation in the cardiac tissue. Both AMNG and insulin treatment suppressed the levels of overproduced ,NO or ONOO, in the vasculature, but only AMNG was able to prevent hypertrophic alterations and reduce protein carbonylation in the cardiac tissue. Conclusions Oxidative protein modification, together with cardiac hypertrophy and high generation of ,NO and ONOO,, are important early events in the development of cardiovascular complications in diabetes. Aminoguanidine could prevent hypertrophy through inhibition of production of nonenzymatic glycation products rather than via inhibition of ,NO production. Copyright © 2004 John Wiley & Sons, Ltd. [source] Leptin,a predictor of abnormal glucose tolerance and prognosis in patients with myocardial infarction and without previously known Type 2 diabetesDIABETIC MEDICINE, Issue 8 2008M. Wallander Abstract Aims High levels of leptin and low adiponectin are associated with Type 2 diabetes mellitus (T2DM) and cardiovascular (CV) disease. We studied the prognostic implications of leptin and adiponectin in patients with acute myocardial infarction (AMI) without previously known Type 2 DM. Methods One hundred and eighty-one patients were included. Based on an oral glucose tolerance test at hospital discharge (day 4,5), 168 (67% men) had normal or abnormal glucose tolerance (AGT), defined as impaired glucose tolerance or T2DM. Sex- and age-matched healthy persons served as control subjects (n = 185). The associations between fasting serum leptin and adiponectin (day 2) and newly discovered AGT and CV events (CV mortality, non-fatal stroke, reinfarction or severe heart failure) during a median follow-up of 34 months were investigated. Results Compared with control subjects, patients of both genders had significantly higher levels of leptin 2 days after an AMI. These levels were higher than those obtained at hospital discharge and 3 months later. Circulating levels of (ln) leptin 2 days after the AMI predicted AGT at discharge (odds ratio 2.03, P = 0.042). Ln leptin at day 2 was the only biochemical variable that significantly predicted CV events both on univariate [hazard ratio (HR) 1.60, P = 0.018] and on multivariate analysis (HR 1.75, P = 0.045). Adiponectin levels did not differ between patients and control subjects and did not relate to AGT or CV events. Conclusions Elevated circulating levels of leptin on the first morning after an AMI are associated with the presence of AGT at discharge and with a poorer long-term prognosis. [source] Differences in endoscopic views during biopsy through the right and left lower biopsy channels of the upper gastrointestinal endoscopeDIGESTIVE ENDOSCOPY, Issue 3 2004Naoki Mantani Background:, It has not been established as to which side the biopsy (instrument) channel should be placed in the tip of a front-viewing upper gastrointestinal (GI) endoscope to allow an en-face approach to lesions on various aspects of the stomach wall. Methods:, Using a front-viewing two-channel endoscope, we identi,ed a difference in endoscopic views during biopsy between lower-right and lower-left channels. Colored marks were distributed on the lesser curvature (LC), greater curvature (GC), anterior wall (AW), and posterior wall (PW) in the ,stomach' of a dummy for mock-performance of upper GI endoscopy. When biopsy forceps through the different channels touched the marks, an endoscopic photograph was taken. Furthermore, when biopsy specimens were obtained from PW lesions in several patients, endoscopic views were compared between the two biopsy channels. Results:, In the dummy study, no remarkable difference was detected in targeting the marks on AW, LC, or GC of the stomach. The dummy and the patient study showed that the lower-right approach could target PW lesions with a more adequate endoscopic view than from the lower left. The lower-left approach targeted PW lesions on the higher body with a nearly blinded endoscopic view. Specimens from PW of the upper body, which could be precisely obtained under direct visual control through the lower-right channel, were no smaller than those obtained using the channel on the lower left. Conclusion:, The present study suggests that the lower-right channel may be preferable to the lower-left channel in the tip of a front-viewing upper GI endoscope. [source] Predicting global abundance of a threatened species from its occurrence: implications for conservation planningDIVERSITY AND DISTRIBUTIONS, Issue 1 2009Marcos S. L. Figueiredo Abstract Aim, Global abundance is an important characteristic of a species that is correlated with geographical distribution and body size. Despite its importance these estimates are not available since reliable field estimates are either expensive or difficult to obtain. Based on the relationship between a species' local abundance and distribution, some authors propose that abundance can be obtained through spatial distribution data from maps plotted at different scales. This has never been tested over the entire geographical range of a species. Thus, the aim of this study was to estimate global abundance of the Neotropical primate Brachyteles hypoxanthus (northern muriqui) and compare the results with available field estimates. Location, From southern Bahia to Minas Gerais and Espírito Santo states, in the Brazilian Atlantic rain forest. Methods, We compiled 25 recent occurrence localities of B. hypoxanthus and plotted them in grid cells of five different sizes (1, 25, 50, 75 and 100 km per side) to evaluate the performance and accuracy of abundance estimates over a wide range of scales. The abundance estimates were obtained by the negative binomial distribution (NBD) method and corrected by average group size to take into account primate social habits. To assess the accuracy of the method, the predicted abundances were then compared to recent independent field estimates. Results, The NBD estimates were quite accurate in predicting B. hypoxanthus global abundance, once the gregarious habits of this species are taken into account. The predicted abundance estimates were not statistically different from those obtained from field estimates. Main conclusions, The NBD method seems to be a quick and reliable approach to estimate species abundance once several limiting factors are taken into account, and can greatly impact conservation planning, but further applications in macroecological and ecological theory testing needs improvement of the method. [source] Suspended sediment transport in a small Mediterranean agricultural catchmentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2009Joan Estrany Abstract The aim of this study is to analyze suspended sediment transport in a Mediterranean agricultural catchment under traditional soil and water conservation practices. Field measurements were conducted in Can Revull, a small ephemeral catchment (1.03 km2) on the island of Mallorca. This study uses continuous turbidity records to analyse suspended sediment transport regimes, construct and interpret multiple regression models of total suspended sediment concentration (SSC) and of SSC related to stormflow discharge, and assess the sediment loads and yields of three hydrological years (2004,2005 to 2006,2007). An annual average SSC of 17.3 mg l,1, with a maximum of 2270 mg l,1, was recorded in the middle of the winter period when rainfall intensities are high and headwater slopes are ploughed and thus bare. Strong seasonal contrasts of baseflow dynamics associated with different degrees of dilution provide a large scatter in SSC and in the derived rating curves, reflecting that other factors control the supply of suspended sediment. Multiple regression models identify rainfall intensity as the most significant variable in sediment supply. However, under baseflow conditions, physical and biological processes generate sediment in the channel that is subsequently removed during high flow. In contrast, when baseflow is not present, rainfall intensity is the only process that supplies sediment to the channel, mostly from hillslopes. Considering the study period as average in terms of total annual rainfall and intensities, suspended sediment yields were an order of magnitude lower than those obtained in other Mediterranean catchments, a factor that can be related to the historical use of soil conservation practices. Copyright © 2009 John Wiley & Sons, Ltd. [source] Efficient sampling and data reduction techniques for probabilistic seismic lifeline risk assessmentEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2010Nirmal Jayaram Abstract Probabilistic seismic risk assessment for spatially distributed lifelines is less straightforward than for individual structures. While procedures such as the ,PEER framework' have been developed for risk assessment of individual structures, these are not easily applicable to distributed lifeline systems, due to difficulties in describing ground-motion intensity (e.g. spectral acceleration) over a region (in contrast to ground-motion intensity at a single site, which is easily quantified using Probabilistic Seismic Hazard Analysis), and since the link between the ground-motion intensities and lifeline performance is usually not available in closed form. As a result, Monte Carlo simulation (MCS) and its variants are well suited for characterizing ground motions and computing resulting losses to lifelines. This paper proposes a simulation-based framework for developing a small but stochastically representative catalog of earthquake ground-motion intensity maps that can be used for lifeline risk assessment. In this framework, Importance Sampling is used to preferentially sample ,important' ground-motion intensity maps, and K -Means Clustering is used to identify and combine redundant maps in order to obtain a small catalog. The effects of sampling and clustering are accounted for through a weighting on each remaining map, so that the resulting catalog is still a probabilistically correct representation. The feasibility of the proposed simulation framework is illustrated by using it to assess the seismic risk of a simplified model of the San Francisco Bay Area transportation network. A catalog of just 150 intensity maps is generated to represent hazard at 1038 sites from 10 regional fault segments causing earthquakes with magnitudes between five and eight. The risk estimates obtained using these maps are consistent with those obtained using conventional MCS utilizing many orders of magnitudes more ground-motion intensity maps. Therefore, the proposed technique can be used to drastically reduce the computational expense of a simulation-based risk assessment, without compromising the accuracy of the risk estimates. This will facilitate computationally intensive risk analysis of systems such as transportation networks. Finally, the study shows that the uncertainties in the ground-motion intensities and the spatial correlations between ground-motion intensities at various sites must be modeled in order to obtain unbiased estimates of lifeline risk. Copyright © 2010 John Wiley & Sons, Ltd. [source] A Rosenbrock-W method for real-time dynamic substructuring and pseudo-dynamic testingEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2009C. P. Lamarche Abstract A variant of the Rosenbrock-W integration method is proposed for real-time dynamic substructuring and pseudo-dynamic testing. In this variant, an approximation of the Jacobian matrix that accounts for the properties of both the physical and numerical substructures is used throughout the analysis process. Only an initial estimate of the stiffness and damping properties of the physical components is required. It is demonstrated that the method is unconditionally stable provided that specific conditions are fulfilled and that the order accuracy can be maintained in the nonlinear regime without involving any matrix inversion while testing. The method also features controllable numerical energy dissipation characteristics and explicit expression of the target displacement and velocity vectors. The stability and accuracy of the proposed integration scheme are examined in the paper. The method has also been verified through hybrid testing performed of SDOF and MDOF structures with linear and highly nonlinear physical substructures. The results are compared with those obtained from the operator splitting method. An approach based on the modal decomposition principle is presented to predict the potential effect of experimental errors on the overall response during testing. Copyright © 2009 John Wiley & Sons, Ltd. [source] Empirical estimate of fundamental frequencies and damping for Italian buildingsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2009Maria Rosaria Gallipoli Abstract The aim of this work is to estimate the fundamental translational frequencies and relative damping of a large number of existing buildings, performing ambient vibration measurements. The first part of the work is devoted to the comparison of the results obtained with microtremor measurements with those obtained from earthquake recordings using four different techniques: horizontal-to-vertical spectral ratio, standard spectral ratio, non-parametric damping analysis (NonPaDAn) and half bandwidth method. We recorded local earthquakes on a five floors reinforced concrete building with a pair of accelerometers located on the ground and on top floor, and then collected microtremors at the same location of the accelerometers. The agreement between the results obtained with microtremors and earthquakes has encouraged extending ambient noise measurements to a large number of buildings. We analysed the data with the above-mentioned methods to obtain the two main translational frequencies in orthogonal directions and their relative damping for 80 buildings in the urban areas of Potenza and Senigallia (Italy). The frequencies determined with different techniques are in good agreement. We do not have the same satisfactory results for the estimates of damping: the NonPaDAn provides estimates that are less dispersed and grouped around values that appear to be more realistic. Finally, we have compared the measured frequencies with other experimental results and theoretical models. Our results confirm, as reported by previous authors, that the theoretical period,height relationships overestimate the experimental data. Copyright © 2008 John Wiley & Sons, Ltd. [source] Parameter identification of framed structures using an improved finite element model-updating method,Part I: formulation and verificationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2007Eunjong Yu Abstract In this study, we formulate an improved finite element model-updating method to address the numerical difficulties associated with ill conditioning and rank deficiency. These complications are frequently encountered model-updating problems, and occur when the identification of a larger number of physical parameters is attempted than that warranted by the information content of the experimental data. Based on the standard bounded variables least-squares (BVLS) method, which incorporates the usual upper/lower-bound constraints, the proposed method (henceforth referred to as BVLSrc) is equipped with novel sensitivity-based relative constraints. The relative constraints are automatically constructed using the correlation coefficients between the sensitivity vectors of updating parameters. The veracity and effectiveness of BVLSrc is investigated through the simulated, yet realistic, forced-vibration testing of a simple framed structure using its frequency response function as input data. By comparing the results of BVLSrc with those obtained via (the competing) pure BVLS and regularization methods, we show that BVLSrc and regularization methods yield approximate solutions with similar and sufficiently high accuracy, while pure BVLS method yields physically inadmissible solutions. We further demonstrate that BVLSrc is computationally more efficient, because, unlike regularization methods, it does not require the laborious a priori calculations to determine an optimal penalty parameter, and its results are far less sensitive to the initial estimates of the updating parameters. Copyright © 2006 John Wiley & Sons, Ltd. [source] Influence of dynamic soil,structure interaction on the nonlinear response and seismic reliability of multistorey systemsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2007Armando Bárcena Abstract A set of reinforced concrete structures with gravitational loads and mechanical properties (strength and stiffness) representative of systems designed for earthquake resistance in accordance with current criteria and methods is selected to study the influence of dynamic soil,structure interaction on seismic response, ductility demands and reliability levels. The buildings are considered located at soft soil sites in the Valley of Mexico and subjected to ground motion time histories simulated in accordance with characteristic parameters of the maximum probable earthquake likely to occur during the system's expected life. For the near-resonance condition the effects of soil,structure interaction on the ductility demands depend mainly on radiation damping. According to the geometry of the structures studied this damping is strongly correlated with the aspect ratio, obtained by dividing the building height by its width. In this way, for structures with aspect ratio greater than 1.4 the storey and global ductility demands increase with respect to those obtained with the same structures but on rigid base, while for structures with aspect ratio less than 1.4 the ductility demands decrease with respect to those for the structures on rigid base. For the cases when the fundamental period of the structure has values very different from the dominant ground period, soil,structure interaction leads in all cases to a reduction of the ductility demands, independently of the aspect ratio. The reliability index , is obtained as a function of the base shear ratio and of the seismic intensity acting on the nonlinear systems subjected to the simulated motions. The resulting reliability functions are very similar for systems on rigid or on flexible foundation, provided that in the latter case the base rotation and the lateral displacement are removed from the total response of the system. Copyright © 2006 John Wiley & Sons, Ltd. [source] Local Dysfunction and Asymmetrical Deformation of Mitral Annular Geometry in Ischemic Mitral Regurgitation: A Novel Computerized 3D Echocardiographic AnalysisECHOCARDIOGRAPHY, Issue 4 2008Masao Daimon M.D. Objective: Most studies of the pathogenesis of functional mitral regurgitation (MR) have focused on alterations in ventricular function and geometry. We used a novel 3D echocardiographic method to assess abnormalities in mitral annular (MA) geometry and motion in patients with ischemic MR (IMR) and compared these data to those obtained from normal subjects and from patients with MR caused by dilated cardiomyopathy (DMR). Methods: Real time 3D echo was performed in 12 normal subjects, 25 with IMR, and 14 with DMR. Eight points along the saddle-shaped MA were identified using our software at systole and diastole. From these eight points, four annular diameters at each cardiac phase were determined. Annular motion was assessed by measuring local displacement (LD) of a given point between systole and diastole. Results: Annular motion was different between groups: IMR had smaller LD in posterior MA segments than did normals (2.6 ± 1.1 vs 4.8 ± 1.9 mm, P < 0.01), while DMR had globally reduced LD. In IMR systolic MA dilatation was striking in the anterior,posterior (diameter; IMR vs controls, 28.3 ± 3.5 vs 22.5 ± 2.2 mm, P< 0.05) and anterolateral,posteromedial (31.7 ± 3.5 vs 25.1 ± 2.2 mm, P < 0.05) directions; in IMR, systolic MA diameters in these two directions correlated with MR severity(P = 0.02). MA dilatation occurred globally in DMR. Conclusion: This novel 3D echo method demonstrated that MA motion and dilatation were asymmetric in IMR and symmetric in DMR. These differences in MA geometry and motion may aid in the development of distinct new therapies for IMR and DMR. [source] Response of collembolan communities to land-use change and grassland successionECOGRAPHY, Issue 2 2007Matthieu Chauvat This study focuses on the long-term changes of collembolan communities occurring after the conversion of arable land to managed grassland. We analysed collembolan communities at grassland sites of different age that had been gradually converted over a period of 50 yr. Abundance and biomass responded rapidly and very positively to the conversion of arable land to grassland, while species richness was not affected. Collembolan assemblages changed only little during grassland maturation. The impact of land-use change on community structure was more obvious at the functional level because the colonization processes observed in our study mostly relied on hemiedaphic species. Vegetation and soil parameters were good predictors of collembolan community structure during development of managed grassland. The present study demonstrated that past landscape patterns and processes like land-use conversion and subsequent succession had a considerable impact on the present day pattern of species richness and community composition of Collembola within a landscape. Our results strongly differ from those obtained for other invertebrate groups, highlighting on the one hand the very diverse reactions of invertebrates to a common factor, and on the other hand the need to survey more than one taxa in order to draw conclusions on effects of land-use change on faunistic communities. [source] Bacteria divert resources from growth for magellanic penguin chicksECOLOGY LETTERS, Issue 6 2002Jaime Potti Abstract The influence of bacteria on the growth of their wild avian hosts is unknown. We tested experimentally whether administration of a wide-spectrum antibiotic (cephalosporine) during early development of magellanic penguin (Spheniscus magellanicus) chicks had any effect on their growth rates in the wild. Chicks that were injected in two occasions with cephalosporine grew faster than control untreated chicks. The positive effect of medication on nestling growth disappeared after the treatment ceased, did not alter haematological indices indicative of health status, had no influence on chick survival until near independence and was related to a changed bacterial composition of the faecal microbiota of treated chicks when compared with that from control chicks. These results were similar to those obtained for poultry with antimicrobials promoting growth and chick nutrient assimilation rates. Gram-positive bacilli in the diphtheroid genus Corynebacterium are likely candidates to cause decreased growth rates in magellanic penguin chicks. [source] GMM with Weak IdentificationECONOMETRICA, Issue 5 2000James H. Stock This paper develops asymptotic distribution theory for GMM estimators and test statistics when some or all of the parameters are weakly identified. General results are obtained and are specialized to two important cases: linear instrumental variables regression and Euler equations estimation of the CCAPM. Numerical results for the CCAPM demonstrate that weak-identification asymptotics explains the breakdown of conventional GMM procedures documented in previous Monte Carlo studies. Confidence sets immune to weak identification are proposed. We use these results to inform an empirical investigation of various CCAPM specifications; the substantive conclusions reached differ from those obtained using conventional methods. [source] The Effects of Screening and Monitoring on Credit Rationing of SMEsECONOMIC NOTES, Issue 2 2008Mariarosaria Agostino In this paper, we seek to empirically assess which determinants of the capability and incentives of banks to screen and monitor firms are significant in explaining credit rationing to Italian SMEs. After testing for the presence of non-random selection bias and the potential endogeneity of some determinants of interest, the probit model results we obtain suggest that the average banking size and the multiple banking relationship phenomenon are statistically significant factors affecting credit rationing, presumably through their impact on the aforementioned banks' capability and incentives. Other potential determinants of banks' incentives to monitor and screen, such as local banking competition and firm' capacity to collateralize, are never significant. However, when we split the sample according to the level of competition in credit markets, we find that the estimated marginal effects of all significant determinants of interest are larger in absolute value than those obtained when using the whole sample. [source] Tris(2,2,-bipyridyl)ruthenium(II) Electrogenerated Chemiluminescence Sensor Based on Platinized Carbon Nanotube,Zirconia,Nafion Composite FilmsELECTROANALYSIS, Issue 12 2010Hyun Yoon Abstract Mesoporous films of platinized carbon nanotube,zirconia,Nafion composite have been used for the immobilization of tris(2,2,-bipyridyl)ruthenium (II) (Ru(bpy)32+) on an electrode surface to yield a solid-state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt,CNT,zirconia,Nafion exhibit much larger pore diameter (3.55,nm) than that of Nafion (2.82,nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia,Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt,CNT,zirconia,Nafion gave a linear response (R2=0.999) for TPA concentration from 3.0,nM to 1.0,mM with a remarkable detection limit (S/N=3) of 1.0,nM, which is much lower compared to those obtained with the ECL sensors based on other types of sol-gel ceramic,Nafion composite films such as silica,Nafion and titania,Nafion. [source] Engineered Pyranose 2-Oxidase: Efficiently Turning Sugars into Electrical EnergyELECTROANALYSIS, Issue 7-8 2010Oliver Spadiut Abstract Due to the recent interest in enzymatic biofuel cells (BFCs), sugar oxidizing enzymes other than the commonly used glucose oxidase are gaining more importance as possible bioelements of implantable microscale-devices, which can, for example, be used in biosensors and pacemakers. In this study we used rational and semi-rational protein design to improve the catalytic activity of the enzyme pyranose 2-oxidase (P2Ox) with its alternative soluble electron acceptors 1,4-benzoquinone and ferricenium ion, which can serve as electron mediators, to possibly boost the power output of enzymatic BFCs. Using a screening assay based on 96-well plates, we identified the variant H450G, which showed lower KM and higher kcat values for both 1,4-benzoquinone and ferricenium ion compared to the wild-type enzyme, when either D -glucose or D -galactose were used as saturating electron donors. Besides this variant, we analyzed the variants V546C and T169G/V546C for their possible application in enzymatic BFCs. The results obtained in homogeneous solution were compared with those obtained when P2Ox was immobilized on the surface of graphite electrodes and either "wired" to an osmium redox polymer or using soluble 1,4-benzoquinone as mediator. According to the spectrophotometrically determined kinetic constants, the possible energy output, measured in flow injection analysis experiments with these variants, increased up to 4-fold compared to systems employing the wild-type enzyme. [source] Bioelectrochemical Characterization of Horseradish and Soybean PeroxidasesELECTROANALYSIS, Issue 21 2009Marco Frasconi Abstract Heme peroxidase are ubiquitous enzymes catalyzing the oxidation of a broad range of substrates by hydrogen peroxide. In this paper the bioelectrochemical characterization of horseradish peroxidase (HRP) and soybean peroxidase (SBP), belonging to class III of the plant peroxidase superfamily, was studied. The homogeneous reactions between peroxidases and some common redox mediators in the presence of hydrogen peroxide have been carried out by cyclic voltammetry. The electrochemical characterization of the reactions involving enzyme, substrate and mediators concentrations allowed us to calculate the kinetic parameters for the substrate,enzyme reaction (KMS) and for the redox mediator,enzyme reaction (KMM). A full characterization of the direct electron transfer kinetic parameters between the electrode and enzyme active site was also performed by opportunely modeling data obtained from cyclic voltammetry and square wave voltammetry experiments. The experimental data obtained with immobilized peroxidases show enhanced direct electron transfer and excellent electrocatalytical performance for H2O2. Despite the structural similarities and common catalytic cycle, HRP and SBP exhibit differences in their substrate affinity and catalytic efficiency. Basing on our results, it can be concluded that peroxidase from soybean represents an interesting alternative to the classical and largely employed one obtained from horseradish as biorecognition element of electrochemical mediated biosensors. [source] A Study of Nafion-Coated Bismuth-Film Electrode for the Determination of Zinc, Lead, and Cadmium in Blood SamplesELECTROANALYSIS, Issue 21 2008Benzhi Liu Abstract In this article a sensitive differential pulse stripping voltammetry technique on Nafion-coated bismuth-film electrode (NCBFE) was studied for the simultaneous determination of zinc, cadmium, and lead ions in blood samples at ultra trace levels. The measurement results were in excellent agreement with those obtained from atomic absorption spectroscopy. Various operational parameters were investigated and discussed in terms of their effect on the measurement signals. Under optimal conditions, calibration curves for the simultaneous determination of zinc, cadmium, and lead ions were achieved, based on three times the standard deviation of the baseline, the limits of detection were 0.09,,g L,1 for Cd(II), 0.13,,g L,1 for Pb(II), and 0.97,,g L,1 for Zn(II) respectively. [source] The utility of online panel surveys versus computer-assisted interviews in obtaining substance-use prevalence estimates in the NetherlandsADDICTION, Issue 10 2009Renske Spijkerman ABSTRACT Aims Rather than using the traditional, costly method of personal interviews in a general population sample, substance-use prevalence rates can be derived more conveniently from data collected among members of an online access panel. To examine the utility of this method, we compared the outcomes of an online survey with those obtained with the computer-assisted personal interviews (CAPI) method. Design Data were gathered from a large sample of online panellists and in a two-stage stratified sample of the Dutch population using the CAPI method. Setting The Netherlands. Participants The online sample comprised 57 125 Dutch online panellists (15,64 years) of Survey Sampling International LLC (SSI), and the CAPI cohort 7204 respondents (15,64 years). Measurements All participants answered identical questions about their use of alcohol, cannabis, ecstasy, cocaine and performance-enhancing drugs. The CAPI respondents were asked additionally about internet access and online panel membership. Both data sets were weighted statistically according to the distribution of demographic characteristics of the general Dutch population. Findings Response rates were 35.5% (n = 20 282) for the online panel cohort and 62.7% (n = 4516) for the CAPI cohort. The data showed almost consistently lower substance-use prevalence rates for the CAPI respondents. Although the observed differences could be due to bias in both data sets, coverage and non-response bias were higher in the online panel survey. Conclusions Despite its economic advantage, the online panel survey showed stronger non-response and coverage bias than the CAPI survey, leading to less reliable estimates of substance use in the general population. [source] Carbon Ceramic Electrodes Modified with Laccase from Trametes hirsuta: Fabrication, Characterization and Their Use for Phenolic Compounds DetectionELECTROANALYSIS, Issue 9 2007Behzad Haghighi Abstract Fungal laccase (Lc) from the basidiomycete Trametes hirsuta was immobilized on top of a carbon ceramic electrode using physical absorption. Direct, unmediated heterogeneous electron transfer between Lc and the carbon ceramic electrode (CCE) under aerobic conditions was shown. The bioelectrocatalytic reduction of oxygen on Lc-CCE started at about 430,mV vs. Ag|AgCl|KClsat at pH,3.5 and moved with about 57,mV in the cathodic region per pH unit. The Lc-modified CCE was then used as a biosensing detection element in a single line flow injection system for the amperometric determination of a variety of phenolic substrates of the enzyme. The experimental conditions were studied and optimized for catechol serving as a model compound. Statistical aspects were applied and the sensor characteristics and Michaelis-Menten constants of the investigated phenolic compounds were calculated and compared with those obtained for solid graphite electrodes modified with Trametes hirsuta laccase. The results showed that the CCE based biosensor in comparison with the solid graphite based biosensor offers a lower detection limit, a wider linear dynamic range, and excellent operational stability with no sensor passivation, indicating that the sol,gel lattice improves the electrochemical behavior of the biosensor. [source] Photoelectro-Synergistic Catalysis at Ti/TiO2/PbO2 Electrode and Its Application on Determination of Chemical Oxygen DemandELECTROANALYSIS, Issue 22 2006Jiaqing Li Abstract In this paper, photoelectro-synergistic catalysis oxidation of organics in water on Ti/TiO2/PbO2 electrode was investigated by the method of electrochemistry. Furthermore, the results were compared with those obtained from photocatalysis and electrocatalysis. The method proposed was applied to determine the chemical oxygen demand (COD) value, Ti/TiO2/PbO2 electrode functioning as the work electrode during the process. It was shown that the method of photoelectro-synergistic catalysis had lower detection limit and wider linear range than the methods of electroassisted photocatalysis and electrocatalysis. The results obtained by the proposed method and conventional one were compared by carrying out the experiment on 8 wastewater samples. The correlation of the results using different methods was satisfactory and the relative bias was below ±6.0%. [source] | ||||||||||||||||||||||||||||||||||||||||||||||