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New Equation (new + equation)
Selected AbstractsClimate variables as predictors of basal metabolic rate: New equationsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2008Andrew W. Froehle Estimation of basal metabolic rate (BMR) and daily energy expenditure (DEE) in living humans and in fossil hominins can be used to understand the way populations adapt to different environmental and nutritional circumstances. One variable that should be considered in such estimates is climate, which may influence between-population variation in BMR. Overall, populations living in warmer climates tend to have lower BMR than those living in colder climates, even after controlling for body size and composition. Current methods of estimating BMR ignore climate, or deal with its effects in an insufficient manner. This may affect studies that use the factorial method to estimate DEE from BMR, when BMR is not measured but predicted using an equation. The present meta-analysis of published BMR uses stepwise regression to investigate whether the inclusion of climate variables can produce a generally applicable model for human BMR. Regression results show that mean annual temperature and high heat index temperature have a significant effect on BMR, along with body size, age and sex. Based on the regression analysis, equations predicting BMR from body size and climate variables were derived and compared with existing equations. The new equations are generally more accurate and more consistent across climates than the older ones. Estimates of DEE in living and fossil humans using the new equations are compared with estimates using previously published equations, illustrating the utility of including climate variables in estimates of BMR. The new equations derived here may prove useful for future studies of human energy expenditure. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc. [source] Stress Corrosion Cracking and Hydrogen Diffusion in Magnesium,ADVANCED ENGINEERING MATERIALS, Issue 8 2006A. Atrens Evaluation of recent data for hydrogen (H) diffusion in magnesium (Mg) yielded a new equation for the diffusion coefficient of H in Mg. This indicates that there can be significant H transport ahead of a stress corrosion crack in Mg at ambient temperature and that H may be involved in the mechanism of stress corrosion cracking in Mg. [source] A probabilistic investigation of infiltration in the vadose zone: proposal for a new formula of infiltration rateHYDROLOGICAL PROCESSES, Issue 21 2007Erick Carlier Abstract The infiltration rate in the unsaturated zone is analysed from a probabilistic point of view. It is shown that the empirical formulas of Horton and Kostiakov, without apparent physical basis, are explained in a probabilistic approach. Horton's formula reflects a Markovian process contrary to Kostiakov's formula. This approach made it possible to explain why Kostiakov's formula is more powerful than that of Horton. A new equation of infiltration is proposed. The three formulas were compared, for four types of soil, with the model of van Genuchten based on the Richards equation. Copyright © 2006 John Wiley & Sons, Ltd. [source] Improved accuracy for the Helmholtz equation in unbounded domainsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 15 2004Eli Turkel Abstract Based on properties of the Helmholtz equation, we derive a new equation for an auxiliary variable. This reduces much of the oscillations of the solution leading to more accurate numerical approximations to the original unknown. Computations confirm the improved accuracy of the new models in both two and three dimensions. This also improves the accuracy when one wants the solution at neighbouring wavenumbers by using an expansion in k. We examine the accuracy for both waveguide and scattering problems as a function of k, h and the forcing mode l. The use of local absorbing boundary conditions is also examined as well as the location of the outer surface as functions of k. Connections with parabolic approximations are analysed. Copyright © 2004 John Wiley & Sons, Ltd. [source] A new method of vegetation,climate classification in ChinaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2008Sun Yanling Abstract Coefficient C is a synthetic index from the third correlative equation, which represents the state of moisture in a region and may be used for assigning vegetation zonality. The third correlative equation is a new equation concerning heat and water balance from knowledge of evaporation on land. In this article, coefficient C and accumulated temperature over 5 °C (AT5) are combined to predict the distribution of vegetation zones in China. Predictions of vegetation distribution are made using observational climate data interpolated into a 25 × 25 km grid. The overall impression from examining the resulting vegetation map is that the location and distribution of vegetation zones in China are predicted fairly well. Comparison between the predicted vegetation map and the vegetation regionalization map are based on Kappa statistics and indicate very good agreement for the cold,temperate coniferous forest zone, the subtropical evergreen broadleaved forest zone, and the temperate mixed coniferous,broadleaved forest zone. Agreement is good for the warm,temperate deciduous broadleaved forest zone, the temperate steppe zone, the temperate desert zone, and the Tibetan high-cold plateau zone. Agreement between the regionalization map and the produced map is fair for the tropical rainforest and monsoon forest zone. Compared with those produced by the Holdridge, Thornthwaite, Penman, and the Kira models, as well as the Budyko method, the Kappa statistics in this article are all better except for the cold,temperate (boreal) coniferous forest zone and the temperate desert zone. The results are particularly superior for the Tibetan high-cold plateau zone. Coefficient C provides important information for predicting the distribution of vegetation zones in China, and this article attempts to study vegetation,climate classification on a large scale using coefficient C and AT5. Copyright © 2007 Royal Meteorological Society [source] Terminal settling velocity and drag coefficient of biofilm-coated particles at high Reynolds numbersAICHE JOURNAL, Issue 10 2010Mehran Andalib Abstract The drag force (Fd) on bio-coated particles taken from two laboratory-scale liquid,solid circulating fluidized bed bioreactors (LSCFBBR) was studied. The terminal velocities (ut) and Reynolds numbers (Ret) of particles observed were higher than reported in the literature. Literature equations for determining ut were found inadequate to predict drag coefficient (Cd) in Ret > 130. A new equation for determining Fd as an explicit function of terminal settling velocity was generated based on Archimedes numbers (Ar) of the biofilm-coated particle. The proposed equation adequately predicted the terminal settling velocity of other literature data at lower Ret of less than 130, with an accuracy >85%. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Extension of a biochemical model for the generalized stoichiometry of electron transport limited C3 photosynthesisPLANT CELL & ENVIRONMENT, Issue 10 2004X. YIN ABSTRACT The widely used steady-state model of Farquhar et al. (Planta 149: 78,90, 1980) for C3 photosynthesis was developed on the basis of linear whole-chain (non-cyclic) electron transport. In this model, calculation of the RuBP-regeneration limited CO2 -assimilation rate depends on whether it is insufficient ATP or NADPH that causes electron transport limitation. A new, generalized equation that allows co-limitation of NADPH and ATP on electron transport is presented herein. The model is based on the assumption that other thylakoid pathways (the Q-cycle, cyclic photophosphorylation, and pseudocyclic electron transport) interplay with the linear chain to co-contribute to a balanced production of NADPH and ATP as required by stromal metabolism. The original model assuming linear electron transport limited either by NADPH or by ATP, predicts quantum yields for CO2 uptake that represent the highest and the lowest values, respectively, of the range given by the new equation. The applicability of the new equation is illustrated for a number of C3 crop species, by curve fitting to gas exchange data in the literature. In comparison with the original model, the new model enables analysis of photosynthetic regulation via the electron transport pathways in response to environmental stresses. [source] Experimental investigation of the energy balance for the metering zone of a twin screw extruderPOLYMER ENGINEERING & SCIENCE, Issue 2 2000Stephan Tenge The object of this study is to investigate experimentally the mechanical power transported from the screws to the polymer melt, the heat dissipated in the polymer melt, and the heat transferred to the barrel of the metering zone of a co-rotating twin screw extruder. For the experimental investigations, different screw elements, mixing elements, and kneading discs are used. The experimental results for the dissipation show good agreement with known calculation models. For the calculation of the heat transfer, a new equation is used to calculate the mean temperature difference under consideration of the dissipation. The Nusselt-number can be calculated in good agreement with the experimental results as a function of the Brinkmann-number. [source] A novel equation of state (EOS) for prediction of solute solubility in supercritical carbon dioxide: Experimental determination and correlationTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009Sh. Jafari Nejad Abstract Solubility data of organophosphorous metal extractants in supercritical fluids (SCF) are crucial for designing metal extraction processes. We have developed a new equation of state (EOS) based on virial equation including an untypical parameter as BP/RT, reduced temperature and pressure for prediction of solute solubility in supercritical carbon dioxide (SC CO2). Solubility experimental data (solubility of tributylphosphate in SC CO2) were correlated with the two cubic equations of state (EOS) models, namely the Peng,Robinson EOS (PR-EOS) and the Soave,Redlich,Kwong EOS (SRK-EOS), together with two adjustable parameter van der Waals mixing and combining rules and our proposed EOS. The AARD of our EOS is significantly lower than that obtained from the other EOS models. The proposed EOS presented more accurate correlation for solubility data in SC CO2. It can be employed to speed up the process of SCF applications in industry. Les données de solubilité d'extractants de métaux organo-phosphorés dans des fluides supercritiques (FSC) sont cruciales pour concevoir des processus d'extraction des métaux. Nous avons développé une nouvelle équation d'état (ÉÉ) basée sur une équation d'état du viriel comprenant un paramètre atypique tel que la température et la pression réduite pour la prédiction de la solubilité du soluté dans du dioxyde de carbone supercritique. Les données expérimentales de solubilité (solubilité du phosphate de tributyle dans CO2 SC) ont été corrélées avec les deux modèles d'équations d'état cubiques, soit l'ÉÉ Peng,Robinson (ÉÉ-PR) et l'ÉÉ Soave,Redlich,Kwong (ÉÉ-SRK), avec deux paramètres ajustables, les règles de mélange et de combinaison van der Waals et notre ÉÉ proposée. L'AARD de notre ÉÉ est significativement plus faible que celui obtenu à partir des autres modèles d'ÉÉ. L'ÉÉ proposée présentait une corrélation plus exacte pour les données de solubilité dans le CO2 SC. Elle peut être employée pour accélérer les processus des applications de FSC dans l'industrie. [source] General Gyrokinetic Equations for Edge PlasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7-9 2006H. Qin Abstract During the pedestal cycle of H-mode edge plasmas in tokamak experiments, large-amplitude pedestal build-up and destruction coexist with small-amplitude drift wave turbulence. The pedestal dynamics simultaneously includes fast time-scale electromagnetic instabilities, long time-scale turbulence-induced transport processes, and more interestingly the interaction between them. To numerically simulate the pedestal dynamics from first principles, it is desirable to develop an effective algorithm based on the gyrokinetic theory. However, existing gyrokinetic theories cannot treat fully nonlinear electromagnetic perturbations with multi-scale-length structures in spacetime, and therefore do not apply to edge plasmas. A set of generalized gyrokinetic equations valid for the edge plasmas has been derived. This formalism allows large-amplitude, time-dependent background electromagnetic fields to be developed fully nonlinearly in addition to small-amplitude, short-wavelength electromagnetic perturbations. It turns out that the most general gyrokinetic theory can be geometrically formulated. The Poincaré-Cartan-Einstein 1-form on the 7D phase space determines particles' worldlines in the phase space, and realizes the momentum integrals in kinetic theory as fiber integrals. The infinitesimal generator of the gyro-symmetry is then asymptotically constructed as the base for the gyrophase coordinate of the gyrocenter coordinate system. This is accomplished by applying the Lie coordinate perturbation method to the Poincaré-Cartan-Einstein 1-form. General gyrokinetic Vlasov-Maxwell equations are then developed as the Vlasov-Maxwell equations in the gyrocenter coordinate system, rather than a set of new equations. Because the general gyrokinetic system developed is geometrically the same as the Vlasov-Maxwell equations, all the coordinate-independent properties of the Vlasov-Maxwell equations, such as energy conservation, momentum conservation, and phase space volume conservation, are automatically carried over to the general gyrokinetic system. The pullback transformation associated with the coordinate transformation is shown to be an indispensable part of the general gyrokinetic Vlasov-Maxwell equations. As an example, the pullback transformation in the gyrokinetic Poisson equation is explicitly expressed in terms of moments of the gyrocenter distribution function, with the important gyro-orbit squeezing effect due to the large electric field shearing in the edge and the full finite Larmour radius effect for short wavelength fluctuations. The familiar "polarization drift density" in the gyrocenter Poisson equation is replaced by a more general expression. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect on energy expenditure of walking on gradients or carrying burdensAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2010Patricia Ann Kramer The effectiveness of people walking while carrying burdens and/or on gradients has been of interest to anthropologists for some time. No empirical equation exists, however, to assess the energetic expenditure of individuals traveling downhill with burdens and whether or not all people increase their energetic expenditure over unburdened level travel when carrying relatively light burdens (<20% of body mass) remains unclear. To begin to rectify this lacunae, gait parameters, physiological variables, and the energetic expenditure of 11 adults were assessed as they walked with burdens of 5 and 10 kg on a level treadmill and while they walked unburdened on gradients ±8 and ±16%. These data were then compared to predictive equations and data available from the literature. Velocity and body mass were combined with gradient and burden mass, where appropriate, as independent covariates to create predictive equations, which explained >80% of the variation in energetic expenditure. These new equations are appropriate for predicting energetic expenditure in people carrying burdens of <20% of total body mass or walking up and downhill at gradients of <20%. Am. J. Hum. Biol. 2010. © 2010 Wiley-Liss, Inc. [source] Climate variables as predictors of basal metabolic rate: New equationsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2008Andrew W. Froehle Estimation of basal metabolic rate (BMR) and daily energy expenditure (DEE) in living humans and in fossil hominins can be used to understand the way populations adapt to different environmental and nutritional circumstances. One variable that should be considered in such estimates is climate, which may influence between-population variation in BMR. Overall, populations living in warmer climates tend to have lower BMR than those living in colder climates, even after controlling for body size and composition. Current methods of estimating BMR ignore climate, or deal with its effects in an insufficient manner. This may affect studies that use the factorial method to estimate DEE from BMR, when BMR is not measured but predicted using an equation. The present meta-analysis of published BMR uses stepwise regression to investigate whether the inclusion of climate variables can produce a generally applicable model for human BMR. Regression results show that mean annual temperature and high heat index temperature have a significant effect on BMR, along with body size, age and sex. Based on the regression analysis, equations predicting BMR from body size and climate variables were derived and compared with existing equations. The new equations are generally more accurate and more consistent across climates than the older ones. Estimates of DEE in living and fossil humans using the new equations are compared with estimates using previously published equations, illustrating the utility of including climate variables in estimates of BMR. The new equations derived here may prove useful for future studies of human energy expenditure. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc. [source] Stature estimation formulae for indigenous North American populationsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Benjamin M. Auerbach Abstract Stature estimation methods for adult indigenous humans from the Americas have generally relied on a limited number of regression equations. The available equations, however, are not broadly applicable to the diversity of the populations that lived in the New World prior to European colonization. Furthermore, some equations that have been used were originally derived from inappropriate reference samples, such as the "Mongoloid" group measured by Trotter and Gleser (Am J Phys Anthropol 16 [1958] 79-123). This study develops new stature estimation equations for long bones of the lower limb from a geographically diverse sample of North American archaeological sites. Statures were reconstructed from 967 skeletons from 75 archaeological sites using the revised Fully anatomical technique (Raxter et al., Am J Phys Anthropol 130 [2006] 374-384). Archaeological samples were grouped according to general body proportions, using relative tibia and femur length to stature as guides. On the basis of differences in these proportions, three broad groupings were identified: a high latitude "arctic" group, a general "temperate" group, and a Great Plains group. Sex-specific ordinary least squares regression formulae were developed based on femoral and tibial lengths for each of these groups. Comparisons of the new stature estimation equations with previously available equations were conducted using several archaeological test samples. In most cases, the new stature estimation equations are more precise than those previously available, and we recommend their use throughout most of North America. The equations developed by Genovés for Mesoamerican and US Southwest samples are a useful alternative for these regions. Applicability of the new equations to South American samples awaits further testing. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] New predictive equations for spirometric reference values and comparison with Morris equation in a Korean populationRESPIROLOGY, Issue 3 2008Chang-Hoon LEE Background and objective: The clinical importance of the differences between actual and predicted spirometric indices in non-Western populations is poorly defined. This study evaluated the differences between the spirometric values derived from Morris equation, traditionally used in South Korea, and the actual values, in the classification and detection of patients with respiratory diseases, and developed new predictive equations for the calculation of reference spirometric values for healthy Koreans. Methods: Data derived from a subset of the population who completed the initial baseline survey of the Korean Health and Genome Study were used to develop new predictive equations for spirometric reference values, using multiple linear regression. The effects of the new equations relative to those of Morris on the detection and classification of patients with respiratory diseases were then evaluated. Results: In total, 9999 people completed the baseline survey; a subgroup of 1314 met the study inclusion criteria and were used to develop the new predictive equations. Morris equation are 53.8% less accurate in detecting people with restrictive disorders and 15.8% less accurate in estimating the severity of COPD than the newly derived equations, although the differences between values derived from the traditional equations and values from the new equations were as small as 3.3,7.6%. Conclusions: The use of spirometric reference values that underestimate the actual parameters, despite the small differences, may have a significant influence on the detection of patients with restrictive disorders and the staging of COPD. [source] The relationships between half-life (t1/2) and mean residence time (MRT) in the two-compartment open body modelBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2004Eyal Sobol Abstract Rationale. In the one-compartment model following i.v. administration the mean residence time (MRT) of a drug is always greater than its half-life (t1/2). However, following i.v. administration, drug plasma concentration (C) versus time (t) is best described by a two-compartment model or a two exponential equation: C=Ae,,t+Be,,t, where A and B are concentration unit-coefficients and , and , are exponential coefficients. The relationships between t1/2 and MRT in the two-compartment model have not been explored and it is not clear whether in this model too MRT is always greater than t1/2. Methods. In the current paper new equations have been developed that describe the relationships between the terminal t1/2 (or t1/2,) and MRT in the two-compartment model following administration of i.v. bolus, i.v. infusion (zero order input) and oral administration (first order input). Results. A critical value (CV) equals to the quotient of (1,ln2) and (1,,/,) (CV=(1,ln2)/(1,,/,)=0.307/(1,,/,)) has been derived and was compared with the fraction (f1) of drug elimination or AUC (AUC-area under C vs t curve) associated with the first exponential term of the two-compartment equation (f1=A/,/AUC). Following i.v. bolus, CV ranges between a minimal value of 0.307 (1,ln2) and infinity. As long as f1 A new accurate method for predicting lithium clearance and daily dosage requirements in adult psychiatric patientsBIPOLAR DISORDERS, Issue 3 2008Hisham S Abou-Auda Objective:, The present study aimed to derive new equations for estimating lithium clearance and daily dosage requirements needed to achieve an intended lithium serum level for adult psychiatric inpatients and outpatients. Methods:, Data were retrospectively collected from 60 adult psychiatric patients (34 males and 26 females, aged between 18,80 years) in both inpatient and outpatient settings. All variables that might affect lithium clearance and/or lithium serum concentration were included and analyzed by stepwise multiple linear regression to produce equations describing lithium clearance and daily dosage requirements for these patients. The validation of the developed equations was performed by application to another 60 psychiatric subjects in both the inpatient and outpatient settings. The bias and accuracy of the new methods were also compared to those set forth by the empirical method and the a priori methods developed by Zetin, Pepin, Jermain and Terao and colleagues. Results:, The following prediction equations for lithium clearance (CLLi) were obtained: CLLi (inpatients) = 0.932 + 0.185CLCr and CLLi (outpatients) = 1.021 + 0.141CLCr. The equations derived for daily dosage requirements were: daily dose (inpatients, mg) = 350.15 + 289.92 (desired lithium level, mmol/L) + 0.84 (weight, kg) , 1.76 (age, years) + 34.43 [tricyclic antidepressant (TCA), yes = 1, no = 0] + 62.1(CLCr, L/h) + 13.1 [blood urea nitrogen (BUN), mmol/L] + 40.9 (sex, male = 1, female = 0) and daily dose (outpatients, mg) = 784.92 + 530.22 (desired lithium level, mmol/L) + 8.61 (weight, kg) , 12.09 (age, years) , 11.14 (TCA, yes = 1, no = 0) , 7.63 (CLCr, L/h) , 42.62 (BUN, mmol/L) , 23.43 (sex, male = 1, female = 0). In the present method, the prediction error for clearance was 10.31% and 6.62% for inpatients and outpatients, respectively, and the prediction error for daily dosage requirements was 3.96% and 2.95% for inpatients and outpatients, respectively. Conclusions:, Compared to previously reported methods, the present method proved to be accurate and can be safely used for the prediction of lithium clearance and daily dosage requirements in psychiatric inpatients and outpatients. [source]
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