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Models Available (models + available)
Selected AbstractsLaboratory Models Available to Study Alcohol-Induced Organ Damage and Immune Variations: Choosing the Appropriate ModelALCOHOLISM, Issue 9 2010Nympha B. D'Souza El-Guindy The morbidity and mortality resulting from alcohol-related diseases globally impose a substantive cost to society. To minimize the financial burden on society and improve the quality of life for individuals suffering from the ill effects of alcohol abuse, substantial research in the alcohol field is focused on understanding the mechanisms by which alcohol-related diseases develop and progress. Since ethical concerns and inherent difficulties limit the amount of alcohol abuse research that can be performed in humans, most studies are performed in laboratory animals. This article summarizes the various laboratory models of alcohol abuse that are currently available and are used to study the mechanisms by which alcohol abuse induces organ damage and immune defects. The strengths and weaknesses of each of the models are discussed. Integrated into the review are the presentations that were made in the symposium "Methods of Ethanol Application in Alcohol Model,How Long is Long Enough" at the joint 2008 Research Society on Alcoholism (RSA) and International Society for Biomedical Research on Alcoholism (ISBRA) meeting, Washington, DC, emphasizing the importance not only of selecting the most appropriate laboratory alcohol model to address the specific goals of a project but also of ensuring that the findings can be extrapolated to alcohol-induced diseases in humans. [source] Duration of strong ground motion during Mexican earthquakes in terms of magnitude, distance to the rupture area and dominant site periodEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2001Eduardo Reinoso Abstract A study of the duration of strong ground motion using accelerometric data of subduction and normal-faulting Mexican earthquakes is presented. Duration is obtained based on the time between 2.5 and 97.5 per cent of the Arias intensity. An expression to predict this duration in terms of the magnitude, distance to the rupture area and site period is proposed and compared with predictions available in the literature. The effect of large duration for very distant sites and the contribution of soft soils to the duration of strong ground motion are widely discussed. We have found that large magnitude not only yields long duration at the source, but also proportionally longer duration with distance and with dominant site period compared to small magnitude. The duration obtained from the regression is used as a parameter to obtain input and hysteretic energy and on the use of damage models available in the literature. Finally, duration is used together with the random vibration theory to predict response spectra. Copyright © 2001 John Wiley & Sons, Ltd. [source] ACCUMULATING DOBZHANSKY-MULLER INCOMPATIBILITIES: RECONCILING THEORY AND DATAEVOLUTION, Issue 6 2004John J. Welch Abstract Theoretical models of the accumulation of Dobzhansky-Muller incompatibilities (DMIs) are studied, and in particular, the framework introduced by Orr (1995) and a verbal model introduced by Kondrashov et al. (2002). These models embody very different assumptions about the relationship between the substitution process underlying evolutionary divergence and the formation of incompatibilities. These differences have implications for our ability to make inferences about the divergence from patterns in the relevant data. With this in mind, the models are investigated for their ability to account for three patterns evident in this data: (1) the asymmetrical nature of incompatibilities under reciprocal introgression; (2) the finding that multiple concurrent introgressions may be necessary for an incompatibility to form; and (3) the finding that the probability of obtaining an incompatibility by introgressing a single amino acid remains roughly constant over a wide range of genetic distances. None of the models available in the literature can account for all of the empirical patterns. However, modified versions of the models can do so. Ways of discriminating between the different models are then discussed. [source] Assessment of two-equation turbulence modelling for high Reynolds number hydrofoil flowsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2004N. Mulvany Abstract This paper presents an evaluation of the capability of turbulence models available in the commercial CFD code FLUENT 6.0 for their application to hydrofoil turbulent boundary layer separation flow at high Reynolds numbers. Four widely applied two-equation RANS turbulence models were assessed through comparison with experimental data at Reynolds numbers of 8.284×106 and 1.657×107. They were the standard k,,model, the realizable k,,model, the standard k,,model and the shear-stress-transport (SST) k,,model. It has found that the realizable k,,turbulence model used with enhanced wall functions and near-wall modelling techniques, consistently provides superior performance in predicting the flow characteristics around the hydrofoil. Copyright © 2004 John Wiley & Sons, Ltd. [source] Comparison of solar radiation correlations for ,zmir, TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2002K. Ulgen Abstract In this study, empirical correlations are developed to estimate the monthly average daily global solar radiation on a horizontal surface (H) for the city of ,zmir in Turkey. Experimental data were measured in the Solar,Meteorological Station of the Solar Energy Institute at Ege University. The present models are then compared with the 25 models available in the literature for calculating H based on the main percentage error, root mean error, the main bias error, and correlation coefficient. It can be concluded that the present models predict the values of H for ,zmir better than other available models. Copyright © 2002 John Wiley & Sons, Ltd. [source] Carbon monoxide poisoning of proton exchange membrane fuel cellsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2001J. J. Baschuk Abstract Proton exchange membrane fuel cell (PEMFC) performance degrades when carbon monoxide (CO) is present in the fuel gas; this is referred to as CO poisoning. This paper investigates CO poisoning of PEMFCs by reviewing work on the electrochemistry of CO and hydrogen, the experimental performance of PEMFCs exhibiting CO poisoning, methods to mitigate CO poisoning and theoretical models of CO poisoning. It is found that CO poisons the anode reaction through preferentially adsorbing to the platinum surface and blocking active sites, and that the CO poisoning effect is slow and reversible. There exist three methods to mitigate the effect of CO poisoning: (i) the use of a platinum alloy catalyst, (ii) higher cell operating temperature and (iii) introduction of oxygen into the fuel gas flow. Of these three methods, the third is the most practical. There are several models available in the literature for the effect of CO poisoning on a PEMFC and from the modeling efforts, it is clear that small CO oxidation rates can result in much increased performance of the anode. However, none of the existing models have considered the effect of transport phenomena in a cell, nor the effect of oxygen crossover from the cathode, which may be a significant contributor to CO tolerance in a PEMFC. In addition, there is a lack of data for CO oxidation and adsorption at low temperatures, which is needed for detailed modeling of CO poisoning in PEMFCs. Copyright © 2001 John Wiley & Sons, Ltd. [source] Prostate inflammation and its potential impact on prostate cancer: A current reviewJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2008Jessica Haverkamp Abstract Recent studies have identified a role for inflammation in the development and progression of several cancers, such as liver, stomach and the large intestine. Data from several studies has shown correlations between soluble inflammatory mediators, such as cytokines, chemokines and growth factors. However, a direct relationship between inflammation and prostate cancer has yet to be identified. Two major hurdles currently exist which limit the study of this relationship are first that animal models available for studying prostate inflammation are lmited, and secondly that relatively little is known about the inflammatory response in the prostate. Here we first review the data demonstrating a correlation between inflammation and prostate cancer as well as review what is currently known about the inflammatory response in the prostate and the impact this inflammation has on the prostate tissue. J. Cell. Biochem. 103: 1344,1353, 2008. © 2007 Wiley-Liss, Inc. [source] MATHEMATICAL MODELLING OF THIN-LAYER DRYING OF KIWIFRUIT SLICESJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2009M DOYMAZ ABSTRACT The effect of temperature on the drying kinetics of kiwifruit was investigated. The drying process was carried out at temperatures of 50, 55 and 60C, air velocity of 2.4 m/s and relative humidity between 10,25%. Drying time decreased considerably with increased air temperature. Drying process took place in the falling rate period. Twelve mathematical models available in the literature were fitted to the experimental data. The models were compared by four statistical parameters; i.e., determination of coefficient, mean relative percent error, reduced chi-square and root mean square error, and the best-fit model was selected. The modified Henderson and Pabis and Verma et al. models were given the best results in describing thin-layer drying of kiwifruits. The effective diffusivity of water during air-drying varied from 1.743 to 2.241 × 10,10 m2/s over the temperature range investigated, with activation energy equal to 22.48 kJ/mol. PRACTICAL APPLICATIONS Drying can be described as an industrial preservation method in which water content and activity of agricultural products are decreased by heated air to minimize biochemical, chemical and microbiological deterioration. Kiwifruit has a very short life because of softening and vitamin loss during cold storage. The use of drying prolongs the shelf-life of the kiwifruit, as the water content reduction slows down deterioration reactions. In this study, drying characteristics of kiwifruits were studied in a convectional hot-air dryer. The objectives of the present study were to determine experimentally the thin-layer drying characteristics and rehydration capacity of samples, and to fit the experimental data to 12 mathematical models available from the literature. [source] New implications for the QUAKING RNA binding protein in human diseaseJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2008Carol Anne Chénard Abstract The use of spontaneously occurring mouse models has proved to be a valuable tool throughout the years to delineate the signals required for nervous system development. This is especially true in the field of myelin biology, with a large number of different models available. The quaking viable mouse models dysmyelination in the nervous system and links the QUAKING RNA binding proteins to myelination and cell fate decisions. In this Mini-Review, we highlight the biological functions attributed to this KH-type RNA binding protein and the recent achievements linking it to human disorders. © 2007 Wiley-Liss, Inc. [source] Progress and limitations in the use of in vitro cell cultures to serve as a permeability screen for the blood-brain barrierJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2001Mark Gumbleton Abstract A relatively simple, widely applicable, and robust in vitro method of predicting blood-brain barrier (BBB) permeability to central nervous system-acting drugs is an increasing need. A cell-based model offers the potential to account for transcellular and paracellular drug diffusional processes, metabolism, and active transport processes, as well as nondefined interactions between a drug and cellular material that may impact upon a membrane's overall permeability profile. Any in vitro BBB cell model to be utilized for the transendothelial BBB permeability screening of potential central nervous system drugs must display reproducible solute permeability, and a number of other general criteria including: a restrictive paracellular barrier; a physiologically realistic cell architecture; the functional expression of key transporter mechanisms; and allow ease of culture to meet the technical and time constraints of a screening program. This article reviews the range of in vitro cell-based BBB models available, including the primary/low passage bovine and porcine brain endothelial cultures as well as the spectrum of immortalized brain endothelial cell lines that have been established. The article further discusses the benefits and limitations of exploiting such systems as in vitro BBB permeability screens. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1681,1698, 2001 [source] SIMULTANEOUS ESTIMATIONS OF MULTIPLE PRODUCT SIMILARITIES USING A NEW DISCRIMINATION PROTOCOLJOURNAL OF SENSORY STUDIES, Issue 5 2007BENOÎT ROUSSEAU ABSTRACT This research investigated new paradigms that permit the simultaneous comparison of more than two samples in a discrimination study. Three successive experiments were conducted. All involved noncarbonated orange beverages. In experiment I, Torgerson's method of triads was found to be more discriminating than the multiple dual-pair method and was used in the subsequent two experiments. In experiments II and III, subjects discriminated among stimuli using the Torgerson's method as well as traditional duo,trios. In experiment II, the univariate Thurstonian model with four distributions was found to provide a suitable fit of the data, and the d, values obtained using the traditional duo,trio methodology were not found to be significantly different from those obtained with Torgerson's method. In experiment III, a multivariate, but not univariate, model provided a good fit of the data. Furthermore, d, values from the Torgerson's method were not found to be significantly different from those obtained using the traditional duo,trio methodology. PRACTICAL APPLICATIONS This research supported the use of a Thurstonian model for Torgerson's method of triads and uncovered the usefulness of the method when comparing more than two samples using a discrimination methodology, which has applications in situations involving samples with inherent intra-product variations. Flexibility in the models available also permits the estimation of the dimensionality of the differences among the stimuli involved, providing valuable information that can be obtained more efficiently than running multiple pair-wise traditional discrimination trials. [source] An in vitro biofilm model of subgingival plaqueMOLECULAR ORAL MICROBIOLOGY, Issue 3 2007C. Walker Introduction:, Numerous biofilm models have been described for the study of bacteria associated with the supragingival plaque. However, there are fewer models available for the study of subgingival plaque. The purpose of this study was to develop and validate a model that closely mimicked the composition of the subgingival flora. Methods:, The model was developed as follows: calcium hydroxyapatite disks were coated overnight with 10% sterile saliva, placed in flat-bottomed tissue culture plates containing trypticase-soy broth, directly inoculated with a small aliquot of dispersed subgingival plaque, incubated anaerobically, and transferred to fresh medium at 48-h intervals until climax (steady-state) biofilms were formed (,10 days). Results:, The model, based on samples from eight periodontitis patients and eight healthy subjects, yielded a multi-species, heterogeneous biofilm, consisting of both gram-positive and gram-negative species, and comprising 15,20 cultivable species associated with the subgingival flora. The species present and their proportions were reflective of the initial cultivable subgingival flora. Comparisons of the initial plaque samples from healthy subjects and the mature biofilms showed 81% similarity in species and 70% similarity in the proportions present. Biofilms formed from samples obtained from periodontally diseased subjects were 69% similar in species and 57% similar in the proportions present. Conclusions:, The biofilm model described here closely reproduces the composition of the cultivable subgingival plaque both in the species present and in their relative proportions. Differences existed between biofilms grown from diseased and non-diseased sites with the former being characterized by the presence of periodontal pathogens at microbially significant levels. [source] Engineering Design for Six Sigma,a systematic approachQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 4 2010Torben Hasenkamp Abstract While the concept of engineering design is well established and clearly defined, Design for Six Sigma (DFSS) is a relatively new concept aiming at Six Sigma performance by improved design activity. There are different engineering design models available in the literature which characterize design stages and thereby describe how engineering design activity can be systematized. The actual connection of DFSS with the more established contents of engineering design activity has been less emphasized in the literature. By reviewing the existing literature this paper clarifies the contributions of DFSS to the different stages of a systematic engineering design process. First engineering design models available in the literature are presented and the choice for one systematic design process is motivated. This process is then used as a reference for where and how DFSS contributions can take place. Copyright © 2010 John Wiley & Sons, Ltd. [source] Model Selection for Integrated Recovery/Recapture DataBIOMETRICS, Issue 4 2002R. King Summary. Catchpole et al. (1998, Biometrics 54, 33,46) provide a novel scheme for integrating both recovery and recapture data analyses and derive sufficient statistics that facilitate likelihood computations. In this article, we demonstrate how their efficient likelihood expression can facilitate Bayesian analyses of these kinds of data and extend their methodology to provide a formal framework for model determination. We consider in detail the issue of model selection with respect to a set of recapture/recovery histories of shags (Phalacrocorax aristotelis) and determine, from the enormous range of biologically plausible models available, which best describe the data. By using reversible jump Markov chain Monte Carlo methodology, we demonstrate how this enormous model space can be efficiently and effectively explored without having to resort to performing an infeasibly large number of pairwise comparisons or some ad hoc stepwise procedure. We find that the model used by Catchpole et al. (1998) has essentially zero posterior probability and that, of the 477,144 possible models considered, over 60% of the posterior mass is placed on three neighboring models with biologically interesting interpretations. [source] Force Field Evaluation for Biomolecular Simulation: Free Enthalpies of Solvation of Polar and Apolar Compounds in Various SolventsCHEMPHYSCHEM, Issue 3 2006Daan P. Geerke Abstract Recently, the GROMOS biomolecular force field parameter set 53A6,which has been parametrized to reproduce experimentally determined free enthalpies of hydration and solvation in cyclohexane of amino acid side-chain analogs,was presented. To investigate the transferability of the new parameter set, we calculated free enthalpies of solvation of a range of polar and apolar compounds in different solvents (methanol, dimethyl sulfoxide (DMSO), acetonitrile, and acetone) from molecular dynamics simulations using the GROMOS 53A6 force field. For methanol and DMSO, parameters were used that are available in the 53A6 parameter set. For acetonitrile, a recently developed model was taken and for acetone, two models available in literature were used. We found that trends in and values for the solvation free enthalpies are in satisfactory agreement with experiment, except for the solvation in acetone for which deviations from experiment can be explained in terms of the properties of the models used. [source] | |||||||||||||||||||