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Predictive Capacity (predictive + capacity)
Selected AbstractsAnti-oxidized low-density lipoprotein antibody levels are associated with the development of type 2 diabetes mellitusEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 9 2008L. Garrido-Sánchez Abstract Background, Anti-oxidized low-density lipoprotein (LDL) antibodies are associated with the oxidative capacity of plasma, but whether they protect or promote diabetes is unknown. We undertook a prospective study to determine the predictive capacity of anti-oxidized LDL antibodies for the onset of type 2 diabetes mellitus (T2DM). Materials and methods, We selected 391 non-diabetic women aged 18,65 years. The subjects were classified as being normal (oral glucose test tolerance normal, OGTT-N), or having impaired glucose tolerance (IGT), impaired fasting glucose (IFG) or T2DM according to their baseline glucose levels and after an OGTT. The same subjects were studied six years later. The levels of anti-oxidized LDL antibodies were classified as above or below the 50th percentile. Results, Of the women who were OGTT-N at the start of the study and who had anti-oxidized LDL antibody levels below the 50th percentile, only 65·1% were still OGTT-N after 6 years versus 79·5% of those who had anti-oxidized LDL antibody levels above the 50th percentile (P = 0·015). Women who had IGT or IFG at the start of the study whose anti-oxidized LDL antibody levels were below the 50th percentile had a relative risk of 9·79 (95% confidence interval, 1·40,68·45) of developing diabetes (P < 0·001). Logistic regression analysis showed that the variables predicting the development of a carbohydrate metabolism disorder in the women after 6 years were body mass index (P < 0·001) and the levels of anti-oxidized LDL antibodies (P = 0·042). Conclusions, Levels of anti-oxidized LDL antibodies are independent predictors for the development of T2DM in women. [source] Factors affecting fluid flow in strike,slip fault systems: coupled deformation and fluid flow modelling with application to the western Mount Isa Inlier, AustraliaGEOFLUIDS (ELECTRONIC), Issue 1 2009A. FORD Abstract Deformation and focused fluid flow within a mineralized system are critical in the genesis of hydrothermal ore deposits. Dilation and integrated fluid flux due to coupled deformation and fluid flow in simple strike,slip fault geometries were examined using finite difference analysis in three dimensions. A series of generic fault bend and fault jog geometries consistent with those seen in the western Mount Isa Inlier were modelled in order to understand how fault geometry parameters influence the dilation and integrated fluid flux. Fault dip, fault width, bend/jog angle, and length were varied, and a cross-cutting fault and contrasting rock types were included. The results demonstrate that low fault dips, the presence of contrasts in rock type, and wide faults produce highest dilation and integrated fluid flux values. Increasing fault bend lengths and angles increases dilation and integrated fluid flux, but increasing fault jog length or angle has the opposite effect. There is minimal difference between the outputs from the releasing and restraining fault bend and jog geometries. Model characteristics producing greater fluid flows and/or gradients can be used in a predictive capacity in order to focus exploration on regions with more favorable fault geometries, provided that the mineralized rocks had Mohr,Coulomb rheologies similar to the ones used in the models. [source] Modelling the species richness distribution of French dung beetles (Coleoptera, Scarabaeidae) and delimiting the predictive capacity of different groups of explanatory variablesGLOBAL ECOLOGY, Issue 4 2002Jorge M. Lobo Abstract Aim To predict French Scarabaeidae dung beetle species richness distribution, and to determine the possible underlying causal factors. Location The entire French territory has been studied by dividing it into 301 grid cells of 0.72 × 0.36 degrees. Method Species richness distribution was predicted using generalized linear models to relate the number of species with spatial, topographic and climate variables in grid squares previously identified as well sampled (n = 66). The predictive function includes the curvilinear relationship between variables, interaction terms and the significant third-degree polynomial terms of latitude and longitude. The final model was validated by a jack-knife procedure. The underlying causal factors were investigated by partial regression analysis, decomposing the variation in species richness among spatial, topographic and climate type variables. Results The final model accounts for 86.2% of total deviance, with a mean jack-knife predictive error of 17.7%. The species richness map obtained highlights the Mediterranean as the region richest in species, and the less well-explored south-western region as also being species-rich. The largest fraction of variability (38%) in the number of species is accounted for by the combined effect of the three groups of explanatory variables. The spatially structured climate component explains 21% of variation, while the pure climate and pure spatial components explain 14% and 11%, respectively. The effect of topography was negligible. Conclusions Delimiting the adequately inventoried areas and elaborating forecasting models using simple environmental variables can rapidly produce an estimate of the species richness distribution. Scarabaeidae species richness distribution seems to be mainly influenced by temperature. Minimum mean temperature is the most influential variable on a local scale, while maximum and mean temperature are the most important spatially structured variables. We suggest that species richness variation is mainly conditioned by the failure of many species to go beyond determined temperature range limits. [source] Modelling of paste flows subject to liquid phase migrationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2007M. J. Patel Abstract Particulate pastes undergoing extrusion can exhibit differential velocities between the solid and liquid phases, termed liquid phase migration (LPM). This is observed experimentally but understanding and predictive capacity for paste and extruder design is limited. Most models for LPM feature one-dimensional analyses. Here, a two-dimensional finite element model based on soil mechanics approaches (modified Cam-Clay) was developed where the liquid and the solids skeleton are treated separately. Adaptive remeshing routines were developed to overcome the significant mesh distortion arising from the large strains inherent in extrusion. Material data to evaluate the model's behaviour were taken from the literature. The predictive capacity of the model is evaluated for different ram velocities and die entry angles (smooth walls). Results are compared with experimental findings in the literature and good qualitative agreement is found. Key results are plots of pressure contributions and extrudate liquid fraction against ram displacement, and maps of permeability, liquid velocity and voids ratio. Pore liquid pressure always dominates extrusion pressure. The relationship between extrusion geometry, ram speed and LPM is complex. Overall, for a given geometry, higher ram speeds give less migration. Pastes flowing into conical entry dies give different voids ratio distributions and do not feature static zones. Copyright © 2007 John Wiley & Sons, Ltd. [source] Evaluation of physiologically based pharmacokinetic models for use in risk assessment,JOURNAL OF APPLIED TOXICOLOGY, Issue 3 2007Weihsueh A. Chiu Abstract Physiologically based pharmacokinetic (PBPK) models are sophisticated dosimetry models that offer great flexibility in modeling exposure scenarios for which there are limited data. This is particularly of relevance to assessing human exposure to environmental toxicants, which often requires a number of extrapolations across species, route, or dose levels. The continued development of PBPK models ensures that regulatory agencies will increasingly experience the need to evaluate available models for their application in risk assessment. To date, there are few published criteria or well-defined standards for evaluating these models. Herein, important considerations for evaluating such models are described. The evaluation of PBPK models intended for risk assessment applications should include a consideration of: model purpose, model structure, mathematical representation, parameter estimation, computer implementation, predictive capacity and statistical analyses. Model purpose and structure require qualitative checks on the biological plausibility of a model. Mathematical representation, parameter estimation, computer implementation involve an assessment of the coding of the model, as well as the selection and justification of the physical, physicochemical and biochemical parameters chosen to represent a biological organism. Finally, the predictive capacity and sensitivity, variability and uncertainty of the model are analysed so that the applicability of a model for risk assessment can be determined. Published in 2007 by John Wiley & Sons, Ltd. [source] The Indian Ocean dipole , the unsung driver of climatic variability in East AfricaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2007Rob Marchant Abstract A growing body of evidence suggests that an independent ocean circulation system in the Indian Ocean, the Indian Ocean dipole (IOD), is partly responsible for driving climate variability of the surrounding landmasses. The IOD had traditionally been viewed as an artefact of the El Niño,Southern Oscillation (ENSO) system although increasingly the evidence is amassing that it is separate and distinct phenomenon. We review the causes of the IOD, how it develops within the Indian Ocean, the relationships with ENSO, and the consequences for East African climate dynamics and associated impacts on ecosystems, in particular along the Eastern Arc Mountains of Kenya and Tanzania. We evaluate current research initiatives focussed on characterizing and constraining the IOD and examine how effective these will be in determining climate change impacts on East African ecosystems and how such predictive capacity can be used in developing policy. Résumé Un nombre croissant de preuves suggère qu'un système indépendant de circulation des eaux de l'océan Indien, le Dipôle de l'océan Indien (IOD), est partiellement responsable de la variabilité du climat des terres environnantes. L'IOD est habituellement considéré comme un artéfact de l'Oscillation Méridionale El Niño (ENSO) bien que les preuves s'accumulent pour montrer que c'est un phénomène séparé et distinct. Nous revoyons les causes de l'IOD, comment il se développe au sein de l'océan Indien, ses liens avec l'ENSO et ses conséquences pour la dynamique du climat de l'Afrique de l'Est, ainsi que son impact sur les écosystèmes, particulièrement sur la chaîne des montagnes orientales au Kenya et en Tanzanie. Nous évaluons les initiatives de recherches actuelles qui visent à caractériser et à circonscrire l'impact de l'IOD et nous examinons dans quelle mesure elles seront efficaces pour déterminer les impacts du changement climatique sur les écosystèmes est-africains et comment on pourra se servir d'un tel moyen de prévision pour mettre au point des politiques. [source] Population pharmacokinetics of cefepime in neonates with severe nosocomial infectionsJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 3 2008V. Lima-Rogel MD Summary Objective:, To define the pharmacokinetic behaviour of cefepime in neonates with severe nosocomial infections using a mixed effects model. Patients and methods:, Thirty-one newborn infants were included in the study; 10 additional infants participated in the validation of the pharmacokinetic model. Cefepime CL and V were determined using an open monocompartmental model with first-order elimination. The influence of demographic and clinical characteristics on the model was evaluated. The non-linear mixed effect model (nonmem) program was used to determine the pharmacokinetic population model. Results:, The mean corrected gestational age for infants participating in the construction and validation of the model were 35 and 33 weeks, respectively. Factors included in the final pharmacokinetic model were body surface area (BSA) and calculated CLCR. The final population model was CL (L/h) = 0·457 BSA (m2) + 0·243 CLCR (L/h) and V(L) = 4·12 BSA (m2). This model explains 33·3% of the interindividual variability for CL and 12·8% for V. This model was validated in ten neonates with nosocomial infections by assessing the predictive capacity of plasma cefepime concentrations using a priori and Bayesian strategies. Conclusions:, The predictive performance of this population model for cefepime plasma concentrations was adequate for clinical purposes and can be used for individualizing cefepime therapy in newborn infants with severe infections. Cefepime plasma concentrations can be predicted based on BSA and calculated CLCR. Cefepime therapy using a 250 mg/m2 dose administered every 12 h is adequate to achieve plasma concentrations greater than 8 ,g/mL during more than 60% of the dosing interval and is expected to be effective in the treatment of bloodstream infections caused by most gram negative organisms in newborn infants. A dose of 550 mg/m2 would be required for the treatment of infections caused by Pseudomonas sp. [source] Asthma prediction in school children; the value of combined IgE-antibodies and obstructive airways disease severity score,ALLERGY, Issue 9 2010K. C. Lødrup Carlsen To cite this article: Lødrup Carlsen KC, Söderström L, Mowinckel P, Håland G, Pettersen M, Munthe Kaas MC, Devulapalli CS, Buchmann M, Ahlstedt S, Carlsen K-H. Asthma prediction in school children; the value of combined IgE-antibodies and obstructive airways disease severity score. Allergy 2010; 65: 1134,1140. Abstract Background:, Allergic sensitisation increases the risk for asthma development. In this prospective birth cohort (Environment and Childhood Asthma) study, we hypothesized that combining quantitative measures of IgE antibodies (,-IgE) and Severity score of obstructive airways disease (OAD) at 2 years of age (Severity score) is superior to predict current asthma (CA) at 10 years than either measure alone. Secondarily, we assessed if gender modified the prediction of CA. Methods:, A follow-up study at 10 years of age was performed in 371 2-year-old children with recurrent (n = 219) or no (n = 152) bronchial obstruction with available serum analysed for ,-IgE to common food and inhalant allergens through a panel test, Phadiatop Infant® (Phadia, Uppsala, Sweden). Clinical variables included allergic sensitisation and exercise testing to characterise children with CA vs not CA at 10 years and the Severity score (0,12, 0 indicating no OAD) was used to assess risk modification. Results:, Severity score alone explained 24% (Nagelkerke R2 = 0.24) of the variation in CA, whereas ,-IgE explained only 6% (R2 = 0.06). Combining the two increased the explanatory capacity to R2 = 0.30. Gender interacted significantly with ,-IgE; whereas Severity score predicted CA in both genders, the predictive capacity of ,-IgE for CA at 10 years was significant in boys only. Conclusion:, Combining ,-IgE to inhalant allergens and Severity score at 2 years was superior to predict asthma at 10 years than either alone. Severity score predicted CA in both genders, whereas ,-IgE significantly predicted CA in boys only. [source] A New Micromechanically Based Approach for the Elastic Response of Rubber,like Materials at Large StrainsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003Serdar Göktepe M. Sc. The approach models the elasticity of a rubber,like materials based on micro,structure that can be symbolized by a micro,sphere. The proposed model incorporates both non,a.ne deformation of unconstrained chains and superimposed constraint e.ects of tube,like topological formations in a consistent manner. Framework of the constitutive modeling and numerical examples illustrating the excellent predictive capacity of the model are presented. [source] Improved Wildcat Modelling of Mineral ProspectivityRESOURCE GEOLOGY, Issue 2 2010Emmanuel John M. Carranza Abstract Wildcat modelling of mineral prospectivity has been proposed for greenfields geologically-permissive terranes where mineral targets have not yet been discovered but a geological map is available as a source of spatial data of predictors of mineral prospectivity. This paper (i) revisits the initial way of assigning wildcat scores (Sc) to predictors of mineral prospectivity and (ii) proposes an improvement by transforming Sc into improved wildcat scores (ISc) by using a logistic function. This was shown in wildcat modelling of prospectivity for low-sulphidation epithermal-Au (LSEG) deposits in Aroroy district (Philippines). Based on knowledge of characteristics of and controls on LSEG mineralization in the Philippines, the spatial predictors of LSEG prospectivity used in the study are proximity to porphyry plutonic stocks, faults/fractures and fault/fracture intersections. The Sc and ISc of spatial predictors are input separately to principal components analysis to extract a favourability function that can be interpreted as a wildcat model of LSEG prospectivity. The predictive capacity of the wildcat model of LSEG prospectivity based on the ISc of geological predictors is roughly 70% higher than that of the wildcat model of LSEG prospectivity based on the Sc of geological predictors. A slight increase of predictive capacity of wildcat modelling of LSEG prospectivity is also achieved when the ISc of geological predictors are integrated with the ISc of geochemical anomalies, but not with the Sc of geochemical anomalies. The proposed improvement is significant because if the study district were a greenfields exploration area, then a wildcat model of LSEG prospectivity based on the old wildcat methodology would have caused several LSEG targets to be missed. [source] N1S3: A revised staging system for head and neck cutaneous squamous cell carcinoma with lymph node metastasesCANCER, Issue 5 2010Results of 2 Australian Cancer Centers Abstract BACKGROUND. A staging system was designed for metastatic cutaneous squamous cell carcinoma (SCC) that would incorporate the parotid as a regional level and facilitate a better prognostic discrimination between subgroups. METHODS. A retrospective review of clinical and pathological information of patients treated for metastatic cutaneous SCC to the parotid and/or neck was conducted. Potential prognostic factors were analyzed using univariate and multivariate analyses. A staging system was elaborated and externally validated. RESULTS. Two hundred fifteen patients were included. All patients had surgery as their primary treatment; 148 had parotidectomy with neck dissection, 50 parotidectomy alone, and 18 neck dissection alone. One hundred seventy-five patients received postoperative radiotherapy. On univariate analysis, the number of involved lymph nodes (P < .001), maximal size (P = .01), and extracapsular spread (P = .003) were found to be significant predictors of survival. On Cox regression, the number of involved lymph nodes as single or multiple (P = .006) was significant. The N1S3 staging system incorporates involved lymph nodes from parotid and neck (single or multiple) and the size (< or >3 cm). This system demonstrates significant predictive capacity for locoregional control (P < .001), disease-specific survival (P<.0001), and overall survival (P<.0001). N1S3 was tested on a different cohort of 250 patients, and the results confirmed those obtained from our primary analyses. CONCLUSIONS. The N1S3 system stages patients according to the number of involved lymph nodes and size, and incorporates parotid as 1 of the regional levels. These 2 predictors are easily applied on both clinical and pathological data. Cancer 2010. © 2010 American Cancer Society. 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