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Dynamic Variables (dynamic + variable)
Selected AbstractsDynamic Analysis of Exercise Oxygen Consumption Predicts Outcomes in Advanced Heart FailureCONGESTIVE HEART FAILURE, Issue 6 2007Guy A. MacGowan MD It is unclear whether cardiopulmonary stress testing provides prognostic information in patients with very advanced heart failure receiving contemporary medical therapy. Analysis of cardiopulmonary treadmill stress data in a group of patients with advanced heart failure and severe functional impairment was performed (N=102, peak exercise oxygen consumption [VO2] ,14 mL/kg/min, 47% receiving ,-blockers). Dynamic variables (peak - baseline values) better predicted outcomes than did single value peak measurements, especially ,VO2. Multivariate analysis showed that usage of ,-blockers and ,VO2 (both P<.05) independently and significantly predicted outcomes. Subgroup analysis showed that ,VO2 was particularly useful in predicting outcomes in patients with ischemic cardiomyopathy or who were not receiving ,-blockers. Thus, in patients with very advanced heart failure, cardiopulmonary stress testing-derived ,VO2 provides important prognostic information useful to help predict clinical deterioration or death, particularly for patients with ischemic cardiomyopathy or who are not receiving ,-blockers. [source] Effect of Alendronate on the Age-Specific Incidence of Symptomatic Osteoporotic FracturesJOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2005Marc C Hochberg MD Abstract Analyses of data from 3658 postmenopausal women with osteoporosis enrolled in the Fracture Intervention Trial showed that alendronate is effective in reducing the risk of symptomatic osteoporotic fractures across a spectrum of ages. Introduction: Most osteoporosis studies examine the relative risk of fracture based on the entire duration of treatment. Because older patients tend to be at higher risk for osteoporosis-related fractures, this analysis examined the effect of alendronate treatment on the relative risk of fracture in terms of the age that patients attained during the study. Materials and Methods: We studied 3658 postmenopausal women with osteoporosis 55-80 years of age at baseline enrolled in the Fracture Intervention Trial, a large randomized, double-blind, placebo-controlled study. Patients were treated with placebo or with alendronate at a daily dose of 5 mg for 2 years followed by 10 mg for an additional 1-2.5 years, and monitored for clinical fractures. Age, rather than study time, was the dynamic variable in our analysis. Results: The relative risk reductions for hip, clinical spine, and wrist fractures were constant across age groups, without evidence of a decline at older ages. Specifically, alendronate reduced the risk of clinical fracture by 53% at the hip (relative risk [RR] = 0.47; 95% CI = 0.27-0.81; p < 0.01), 45% at the spine (RR = 0.55; 95% CI = 0.37-0.83; p < 0.01), and 31% at the wrist (RR = 0.69; 95% CI = 0.50-0.98; p = 0.038). In addition, alendronate produced a significant risk reduction of 40% (RR = 0.60; 95% CI = 0.47-0.77; p < 0.01) for the composite event of clinical hip, spine, and wrist fractures. As a consequence of the constant relative risk model, the absolute risk reduction with alendronate treatment increased with age because of the age-related increase in fracture risk in the placebo group. The absolute risk reduction for the composite event (hip, spine, and wrist fractures together) for alendronate treatment versus placebo was 65, 80, 111, and 161 women with fractures per 10,000 PYR for the 55 to <65, 65 to <70, 70 to <75, and 75-85 year age groups, respectively. Conclusions: These data show that alendronate is effective in reducing the risk of symptomatic osteoporotic fractures across a spectrum of ages. The effectiveness is somewhat greater in patients with femoral neck T score , ,2.5 than in those with a T score , ,2.0. [source] ,-Dynamics free energy simulation methodsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 11 2009Jennifer L. Knight Abstract Free energy calculations are fundamental to obtaining accurate theoretical estimates of many important biological phenomena including hydration energies, protein-ligand binding affinities and energetics of conformational changes. Unlike traditional free energy perturbation and thermodynamic integration methods, ,-dynamics treats the conventional "," as a dynamic variable in free energy simulations and simultaneously evaluates thermodynamic properties for multiple states in a single simulation. In the present article, we provide an overview of the theory of ,-dynamics, including the use of biasing and restraining potentials to facilitate conformational sampling. We review how ,-dynamics has been used to rapidly and reliably compute relative hydration free energies and binding affinities for series of ligands, to accurately identify crystallographically observed binding modes starting from incorrect orientations, and to model the effects of mutations upon protein stability. Finally, we suggest how ,-dynamics may be extended to facilitate modeling efforts in structure-based drug design. © 2009 Wiley Periodicals, Inc. J Comput Chem 2009 [source] The effect of discordance among violence and general recidivism risk estimates on predictive accuracyCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 3 2006Jeremy F. Mills Introduction,Previous research has shown that the prediction of short-term inpatient violence is negatively affected when clinicians' inter-rater agreement is low and when confidence in the estimate of risk is low. This study examined the effect of discordance between risk assessment instruments used to predict long-term general and violence risk in offenders. Methods,The Psychopathy Checklist , Revised (PCL,R), Level of Service Inventory , Revised (LSI,R), Violence Risk Appraisal Guide (VRAG), and the General Statistical Information on Recidivism (GSIR) were the four risk-prediction instruments used to predict post-release general and violent recidivism within a sample of 209 offenders. Results,The findings lend empirical support to the assumption that predictive accuracy is threatened where there is discordance between risk estimates. Discordance between instruments had the impact of reducing predictive accuracy for all instruments except the GSIR. Further, the influence of discordance was shown to be greater on certain instruments over others. Discordance had a moderating effect on both the PCL,R and LSI,R but not on the VRAG and GSIR. Conclusions,There is a distinct advantage when attempting to predict recidivism to employing measures such as the LSI-R, which includes dynamic variables and intervention-related criminogenic domains, over a measure purely of fixed characteristics, such as the GSIR; however, if there is discordance between the risk estimates, caution should be exercised and more reliance on the more static historically based instrument may be indicated. Copyright © 2006 John Wiley & Sons, Ltd. [source] An arbitrary Lagrangian,Eulerian finite element method for finite strain plasticityINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2003Francisco Armero Abstract This paper presents a new arbitrary Lagrangian,Eulerian (ALE) finite element formulation for finite strain plasticity in non-linear solid mechanics. We consider the models of finite strain plasticity defined by the multiplicative decomposition of the deformation gradient in an elastic and a plastic part (F = FeFp), with the stresses given by a hyperelastic relation. In contrast with more classical ALE approaches based on plastic models of the hypoelastic type, the ALE formulation presented herein considers the direct interpolation of the motion of the material with respect to the reference mesh together with the motion of the spatial mesh with respect to this same reference mesh. This aspect is shown to be crucial for a simple treatment of the advection of the plastic internal variables and dynamic variables. In fact, this advection is carried out exactly through a particle tracking in the reference mesh, a calculation that can be accomplished very efficiently with the use of the connectivity graph of the fixed reference mesh. A staggered scheme defined by three steps (the smoothing, the advection and the Lagrangian steps) leads to an efficient method for the solution of the resulting equations. We present several representative numerical simulations that illustrate the performance of the newly proposed methods. Both quasi-static and dynamic conditions are considered in these model examples. Copyright © 2003 John Wiley & Sons, Ltd. [source] Water Resources Modeling of the Ganges-Brahmaputra-Meghna River Basins Using Satellite Remote Sensing Data,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2009Bushra Nishat Nishat, Bushra and S.M. Mahbubur Rahman, 2009. Water Resources Modeling of the Ganges-Brahmaputra-Meghna River Basins Using Satellite Remote Sensing Data. Journal of the American Water Resources Association (JAWRA) 45(6):1313-1327. Abstract:, Large-scale water resources modeling can provide useful insights on future water availability scenarios for downstream nations in anticipation of proposed upstream water resources projects in large international river basins (IRBs). However, model set up can be challenging due to the large amounts of data requirement on both static states (soils, vegetation, topography, drainage network, etc.) and dynamic variables (rainfall, streamflow, soil moisture, evapotranspiration, etc.) over the basin from multiple nations and data collection agencies. Under such circumstances, satellite remote sensing provides a more pragmatic and convenient alternative because of the vantage of space and easy availability from a single data platform. In this paper, we demonstrate a modeling effort to set up a water resources management model, MIKE BASIN, over the Ganges, Brahmaputra, and Meghna (GBM) river basins. The model is set up with the objective of providing Bangladesh, the lowermost riparian nation in the GBM basins, a framework for assessing proposed water diversion scenarios in the upstream transboundary regions of India and deriving quantitative impacts on water availability. Using an array of satellite remote sensing data on topography, vegetation, and rainfall from the transboundary regions, we demonstrate that it is possible to calibrate MIKE BASIN to a satisfactory level and predict streamflow in the Ganges and Brahmaputra rivers at the entry points of Bangladesh at relevant scales of water resources management. Simulated runoff for the Ganges and Brahmaputra rivers follow the trends in the rated discharge for the calibration period. However, monthly flow volume differs from the actual rated flow by (,) 8% to (+) 20% in the Ganges basin, by (,) 15 to (+) 12% in the Brahmaputra basin, and by (,) 15 to (+) 19% in the Meghna basin. Our large-scale modeling initiative is generic enough for other downstream nations in IRBs to adopt for their own modeling needs. [source] Static and dynamic mechanics of the temporomandibular joint: plowing forces, joint load and tissue stressORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 3 2009J Nickel Structured Abstract Authors,,, Nickel J, Spilker R, Iwasaki L, Gonzalez Y, McCall WD, Ohrbach R, Beatty MW, Marx D Objectives,,, To determine the combined effects 1) of stress-field aspect ratio and velocity and compressive strain and 2) joint load, on temporomandibular joint (TMJ) disc mechanics. Setting and Sample Population,,, Fifty-two subjects (30 ,; 22 ,) participated in the TMJ load experiments. Material and Methods,,, In the absence of human tissue, pig TMJ discs were used to determine the effects of variables 1) on surface plowing forces, and to build a biphasic finite element model (bFEM) to test the effect of human joint loads and 2) on tissue stresses. In the laboratory, discs received a 7.6 N static load via an acrylic indenter before cyclic movement. Data were recorded and analysed using anova. To determine human joint loads, Research Diagnostic Criteria calibrated investigators classified subjects based on signs of disc displacement (DD) and pain (+DD/+pain, n = 18; +DD/,pain, n = 17; ,DD/,pain, n = 17). Three-dimensional geometries were produced for each subject and used in a computer model to calculate joint loads. Results,,, The combined effects of compressive strain, and aspect ratio and velocity of stress-field translation correlated with plowing forces (R2 = 0.85). +DD/,pain subjects produced 60% higher joint loads (anova, p < 0.05), which increased bFEM-calculated compressive strain and peak total normal stress. Conclusions,,, Static and dynamic variables of the stress-field and subject-dependent joint load significantly affect disc mechanics. [source] Energy Efficiency of Two-Phase Mixing in a Modified Bubble ColumnTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2007Subrata Kumar Majumder Abstract Energy efficiency for gas liquid mixing in a modified downflow bubble column reactor has been analyzed in this paper. Efficiencies of the different parts of the bubble column have been assessed on the basis of energy dissipation. Prediction of the energy dissipation coefficient as well as energy utilization efficiency due to gas-liquid mixing as a function of different physical, geometric and dynamic variables of the system has been done by correlation method. The distribution of energy utilization in the different zones of the column has also been analyzed. Experiments were carried out with air-water and air-aqueous solutions of carboxy methyl cellulose with different concentrations. Dans cet article on a analysé l'efficacité énergétique pour le mélange gaz-liquide dans un réacteur à colonne à bulles à écoulement descendant modifié. Les efficacités des différentes régions de la colonne à bulles ont été évaluées sur la base de la dissipation d'énergie. On a utilisé une méthode de corrélation pour prédire le coefficient de dissipation d'énergie ainsi que l'efficacité d'utilisation de l'énergie due au mélange gaz-liquide en fonction des différentes variables physiques, géométriques et dynamiques du système. La distribution de l'utilisation de l'énergie dans les différentes régions de la colonne a également été analysée. Des expériences ont été menées avec des solutions air-eau et air-solutions aqueuses de carboxyméthylcellulose à différentes concentrations. [source] Diagnostic study of generalized moist potential vorticity in a non-uniformly saturated atmosphere with heavy precipitationTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 650 2010Zhaoming Liang Abstract A Meiyu front accompanied by a band of heavy precipitation in East Asia is typically characterized by a much larger moisture gradient than temperature gradient. Many previous studies have suggested use of equivalent potential temperature as a thermodynamic variable under this circumstance. However, dynamic variables coupled with such a thermodynamic variable, e.g. a derived moist potential vorticity (MPV) based on equivalent potential temperature, does not provide useful dynamic insight into these systems. In this study, generalized moist potential vorticity (GMPV) is derived based on a generalized form of potential temperature. Diagnoses of numerical simulations for three typical Meiyu rainfall events show that GMPV provides remarkably accurate tracking of rainfall location, suggesting its potential use as a dynamic tracer for heavy rainfall events such as Meiyu rain bands. Copyright © 2010 Royal Meteorological Society [source] Short-Term Assessment of Risk and Treatability (START): the case for a new structured professional judgment schemeBEHAVIORAL SCIENCES & THE LAW, Issue 6 2006Christopher D. Webster Ph.D. The Short-Term Assessment of Risk and Treatability (START) is a new structured professional judgment scheme intended to inform multiple risk domains relevant to everyday psychiatric clinical practice (e.g. risk to others, suicide, self-harm, self-neglect, substance abuse, unauthorized leave, and victimization). The article describes the processes involved in establishing an interdisciplinary approach to risk assessment and management. The authors present a review of the rationale for START, including the value of dynamic variables, the importance of strengths, and the extent to which clinicians must be attentive to multiple risk domains, reflecting theoretical and scientific evidence of the overlap among risks. Using the development, validation, and implementation of START as an example, the authors describe the processes by which other researchers, clinicians, and administrators could adapt existing assessment schemes or create new ones to bridge some remaining gaps in the risk assessment and management continuum. Copyright © 2006 John Wiley & Sons, Ltd. [source] Alfuzosin 10 mg once daily for treating benign prostatic hyperplasia: a 3-year experience in real-life practiceBJU INTERNATIONAL, Issue 7 2008Guy Vallancien OBJECTIVES To assess the 3-year efficacy and safety of the selective ,1 -blocker alfuzosin at 10 mg once daily in men with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) in ,real-life practice'. The influence of treatment response on the risk of acute urinary retention (AUR) and BPH-related surgery was also analysed. PATIENTS AND METHODS In all, 689 European men (mean age 67.6 years) were enrolled by general practitioners in a 3-year open-label study with alfuzosin at 10 mg once daily. They were asked to complete the International Prostate Symptom Score (IPSS), its eighth question (bother score), and the Danish Prostatic Symptom Score for sexual function (DAN-PSSsex). Efficacy was analysed at the endpoint in the intent-to-treat population. The impact of baseline variables (age, PSA level, IPSS and bother severity) and dynamic variables (IPSS worsening of ,4 points and bother at the last available assessment under treatment) on the risk of AUR and BPH-related surgery was evaluated. RESULTS With alfuzosin, IPSS improved by 6.4 points (,33.4%) from baseline (P < 0.001), reaching ,3 points and >6 points in 71.3% and 47.2% of men, respectively. There were also significant (P < 0.001) improvements from baseline in nocturia (,0.8, ,25.5%), bother score (,1.7, ,40.7%) and DAN-PSSsex weighted scores with treatment. Symptom relief was rapid and maintained over 3 years. Overall, 78 men (12.4%) had an IPSS worsening of ,4 points, 16 (2.6%) had AUR, and 36 (5.7%) required BPH-related surgery. Symptom deterioration during treatment and high baseline PSA values were the best predictors of AUR and BPH-related surgery. Alfuzosin was well tolerated, dizziness being the most frequent adverse event (4.5%) possibly related to vasodilatation. Ejaculatory disorders were uncommon (0.4%). Changes in blood pressure remained marginal, including in men aged ,65 years and those receiving antihypertensive agents. CONCLUSION Alfuzosin administered for 3 years at 10 mg once daily in real-life practice is effective and well tolerated. High PSA values and symptom worsening under treatment appear the best predictors of AUR and BPH-related surgery in the long term. Treatment with alfuzosin might thus help to identify patients at risk of LUTS/BPH progression in order to optimize their management. [source] Managing the progression of lower urinary tract symptoms/benign prostatic hyperplasia: therapeutic options for the man at riskBJU INTERNATIONAL, Issue 2 2007Mark Emberton There are two fairly divergent reviews in this month's issue. The first is a paper which concentrates on the progression of LUTS and BPH. Previous papers on LUTS and BPH were focused on changes in urinary flow rates and symptom scores, a rather static view of things. The first author in this review introduced the concept of dynamic variables in LUTS and BPH, and this, along with the idea of progression of the disease which the MTOPS study brought to our notice, has lead to a major change to our approach to trials of therapy in LUTS and BPH. The second review is really statement of a theory, an expression of a concept being proposed by the author, which hopefully will be of interest to the reader. In benign prostatic hyperplasia (BPH), increased prostate volume has been shown to be associated with future symptom deterioration and progression to acute urinary retention (AUR) or BPH-related surgery. Dihydrotestosterone (DHT) is the primary androgen responsible for prostate growth. Inhibition by 5,-reductase inhibitors (5-ARIs) of the enzyme responsible for the production of DHT decreases prostate volume. This translates to an overall improvement in symptoms and a reduction in the risk of AUR and/or BPH-related surgery. Selective blockage of ,1 -adrenoceptors, principally in the region of the prostate, results in rapid symptom relief for the patient but this does not translate into a long-term reduction in the risk of AUR or BPH-related surgery. Given their different modes of action the rationale has always existed for using 5ARIs and ,-blockers together in men deemed to be both symptomatic and at risk of progression. The factors that predict this progression and the methods available to reduce the risk of it occurring are the subjects of this review. [source] | |||||||||||||||||||