Prediction Equations (prediction + equation)

Distribution by Scientific Domains


Selected Abstracts


Assessing Renal Function by GFR Prediction Equations in Kidney Transplantation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2005
Norberto Perico
No abstract is available for this article. [source]


A vector-valued ground motion intensity measure consisting of spectral acceleration and epsilon

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2005
Jack W. Baker
Abstract The ,strength' of an earthquake ground motion is often quantified by an Intensity Measure (IM), such as peak ground acceleration or spectral acceleration at a given period. This IM is used to predict the response of a structure. In this paper an intensity measure consisting of two parameters, spectral acceleration and epsilon, is considered. The IM is termed a vector-valued IM, as opposed to the single parameter, or scalar, IMs that are traditionally used. Epsilon (defined as a measure of the difference between the spectral acceleration of a record and the mean of a ground motion prediction equation at the given period) is found to have significant ability to predict structural response. It is shown that epsilon is an indicator of spectral shape, explaining why it is related to structural response. By incorporating this vector-valued IM with a vector-valued ground motion hazard, we can predict the mean annual frequency of exceeding a given value of maximum interstory drift ratio, or other such response measure. It is shown that neglecting the effect of epsilon when computing this drift hazard curve leads to conservative estimates of the response of the structure. These observations should perhaps affect record selection in the future. Copyright 2005 John Wiley & Sons, Ltd. [source]


Nonweight-bearing anterior knee laxity is related to anterior tibial translation during transition from nonweight bearing to weight bearing

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2006
Sandra J. Shultz
Abstract We examined the relationship between anterior knee laxity (AKL), evaluated while the knee was nonweight bearing, and anterior translation of the tibia relative to the femur (ATT), evaluated when the knee transitioned from nonweight-bearing to weight-bearing conditions in response to an applied compressive load at the foot. Twenty subjects with normal knees (10 M, 10 F; 25.2,,4.1 years, 169.8,,11.5 cm, 71.6,,16.9 kg) underwent measurements of AKL and ATT of the right knee on 2 days. AKL was measured at 133N with the KT-2000. ATT was measured with the Vermont Knee Laxity Device and electromagnetic position sensors attached to the patella and the anteromedial aspect of the proximal tibia. Three trials for each measure were averaged and analyzed. Measurement consistency was high for both AKL (ICC,=,0.97; SEM,=,0.44 mm) and ATT (ICC,=,0.88; SEM,=,0.84 mm). Linear regression revealed that AKL predicted 35.5% of the variance in ATT (p,=,0.006), with a prediction equation of YATT,=,3.20,+,0.543(XAKL). Our findings suggest that increased AKL is associated with increased ATT as the knee transitions from nonweight-bearing to weight-bearing conditions. The potential for increased knee joint laxity to disrupt normal knee biomechanics during activities such as landing from a jump, or the foot strike phase of gait deserves further study. 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:516,523, 2006 [source]


Comparison of in vitro starch digestibility methods for predicting the glycaemic index of grain foods

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2008
Kirsty A Germaine
Abstract BACKGROUND:In vitro starch digestibility tests are useful for the prediction of glycaemic index (GI). However, there are no internationally recognised methods and no one method has been found to be suitable for all food types. This study compared six in vitro methods, using four grain foods, including those with a varied particle size and soluble fibre content. Method variations included using chewing or mincing, mincing with or without amylase and incubation in a restricted versus non-restricted system. Hydrolysis index (HI) values, calculated from the starch digestibility curves and GI prediction equations were used to compare the in vitro results to GI. RESULTS: HI values for five of the six methods ranked all foods in the same order as the GI values. Using a GI prediction equation (predicted GIHI) the mincing (without amylase) non-restricted method had the smallest standard error of prediction between the predicted GIHI and GI values. This method was then validated using 14 grain foods and demonstrated a significant correlation (r = 0.93, P < 0.01) between the in vitro starch digestibility and reported GI responses. CONCLUSIONS: The non-restricted mincing method showed good potential as a new in vitro starch digestibility method for predicting GI in grain foods. Copyright 2007 Society of Chemical Industry [source]


Body composition in older orthopaedic rehabilitation inpatients: Are field methods valid?

NUTRITION & DIETETICS, Issue 3 2010
Alison YAXLEY
Abstract Aim:, The assessment of body composition is an important aspect of the determination of nutritional health. This cross-sectional measurement study aimed to assess the relative validity of a range of field techniques for the measurement of body composition in a sample of older orthopaedic inpatients participating in rehabilitation. Methods:, Assessment of percent fat-free mass of 31 adults, aged 65 years and over, was conducted under fasting conditions by two types of bioelectrical impedance analysis (multi-frequency and single frequency,using manufacturer's pre-programmed prediction equation) and compared with percent fat-free mass estimated by dual energy X-ray absorptiometry, a reference technique. Data from multi-frequency bioelectrical impedance analysis were also used to calculate percent fat-free mass from the prediction equation of Dey et al. for comparison. Skeletal muscle mass was derived from assessment of corrected arm muscle area and compared with skeletal muscle mass from dual energy X-ray absorptiometry analysis. Bland-Altman analysis was performed to determine the level of agreement between each field technique and dual energy X-ray absorptiometry. Results:, Mean bias and limits of agreement between single frequency bioelectrical impedance analysis and dual energy X-ray absorptiometry were ,5.7% (,24.0, 12.6), between multi-frequency bioelectrical impedance analysis (manufacturer's pre-programmed prediction equation) and dual energy X-ray absorptiometry were 1.4% (,13.4, 16.1), between multi-frequency bioelectrical impedance analysis (Dey et al. prediction equation) and dual energy X-ray absorptiometry were ,5.0% (,16.6, 6.6) and between skeletal muscle mass as derived from assessment of corrected arm muscle area and skeletal muscle mass from dual energy X-ray absorptiometry analysis ,0.97 kg (,8.37, 6.43). Conclusion:, None of the methods assessed are clinically acceptable for assessment of body composition in older orthopaedic rehabilitation patients; however, estimation of skeletal muscle mass, as derived from corrected arm muscle area, is likely to be of more use in the clinical setting as there is no requirement for patients to be fasted. [source]


Comparison of body fat estimates using 3D digital laser scans, direct manual anthropometry, and DXA in men,,

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2010
Todd N. Garlie
Objectives: The purpose of this study was to assess the feasibility of utilizing three dimensional whole body laser surface scanning (3DS) to obtain specific anthropometric measurements to estimate percent body fat (BF). Methods: Percent BF estimates from 37 male volunteers, of age 18,62 yr, were determined by inputting manual anthropometric (MA) and 3DS anthropometric measurements into the current Army BF prediction equation for males. The results were compared with each other and to BF values from Dual Energy X-ray Absorptiometry (DXA), employed as a reference method. Results: Mean percent BF estimates (SD) derived from MA, 3DS and from DXA were 18.4(3.8), 18.8(3.9), and 18.9(4.7), respectively. Analysis of Variance tests revealed no statistical difference between the mean values. Correlation analysis comparing MA and 3DS derived percent BF estimates to each other and to those measured by DXA revealed moderate to strong Pearson correlation coefficients (r), small to moderate standard errors of the estimate (SEE), and were statistically significant (p < 0.05). Conclusions: Correlation coefficients and SEE results for this sample were: (1) DXA vs 3DS; r = 0.74, SEE = 3.2, (2) MA vs DXA; r = 0.82, SEE = 2.8, and (3) MA vs 3DS; r = 0.96, SEE = 1.0. Lin's concordance analysis, including Bland-Altman limits of agreement (LOA), revealed statistically significant measurement agreement among the three measurement modalities (p < 0.05). The application of 3DS scanning to estimate percent BF from commonly used anthropometric measurements are in close agreement with BF estimates derived from analogous MA measurements and from DXA scanning. Am. J. Hum. Biol. 22:695-701, 2010. Published 2010Wiley-Liss, Inc. [source]


Ethnicity-related skeletal muscle differences across the lifespan

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010
Analiza M. Silva
Despite research and clinical significance, limited information is available on the relations between skeletal muscle (SM) and age in adults, specifically among Hispanics, African Americans (AA), and Asians. The aim was to investigate possible sex and ethnic SM differences in adults over an age range of 60 years. Subjects were 468 male and 1280 female adults (,18 years). SM was estimated based on DXA-measured appendicular lean-soft tissue using a previously reported prediction equation. Locally weighted regression smoothing lines were fit to examine SM trends and to localize age cutoffs; piecewise multiple linear regression models were then applied, controlling for weight and height, to identify age cutoffs for sex-specific changes in SM among the ethnic groups. The age of 27 years was identified for women and men as the cut-off after which SM starts to show a negative association with age. Both sexes had a similar ethnic pattern for expected mean SM at the age cutoff, with AA presenting the highest SM values, followed by Whites, Hispanics, and Asians. After the age cutoffs, the lowering of SM differed by ethnicity and sex: AA women showed the greatest SM lowering whereas Hispanic women had the least. Hispanic men tended to show a higher negative association of SM with age followed by AA and Whites. To conclude, significant sex and ethnic differences exist in the magnitude of negative associations of SM with age >27 years. Further studies using a longitudinal design are needed to explore the associations of ethnicity-related decline of SM with health risks. Am. J. Hum. Biol. 2010. 2009 Wiley-Liss, Inc. [source]


Non-iterative equivalent linearization of inelastic SDOF systems for earthquakes in Japan and California

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2010
Katsuichiro Goda
Abstract The seismic performance of existing structures can be assessed based on nonlinear static procedures, such as the Capacity Spectrum Method. This method essentially approximates peak responses of an inelastic single-degree-of-freedom (SDOF) system using peak responses of an equivalent linear SDOF model. In this study, the equivalent linear models of inelastic SDOF systems are developed based on the constant strength approach, which does not require iteration for assessing the seismic performance of existing structures. To investigate the effects of earthquake type and seismic region on the equivalent linear models, four ground-motion data sets,Japanese crustal/interface/inslab records and California crustal records,are compiled and used for nonlinear dynamic analysis. The analysis results indicate that: (1) the optimal equivalent linear model parameters (i.e. equivalent vibration period ratio and damping ratio) decrease with the natural vibration period, whereas they increase with the strength reduction factor; (2) the impacts of earthquake type and seismic region on the equivalent linear model parameters are not significant except for short vibration periods; and (3) the degradation and pinching effects affect the equivalent linear model parameters. We develop prediction equations for the optimal equivalent linear model parameters based on nonlinear least-squares fitting, which improve and extend the current nonlinear static procedure for existing structures with degradation and pinching behavior. Copyright 2010 John Wiley & Sons, Ltd. [source]


Estimation of nitrogen concentration and in vitro dry matter digestibility of herbage of warm-season grass pastures from canopy hyperspectral reflectance measurements

GRASS & FORAGE SCIENCE, Issue 2 2008
P. J. Starks
Abstract Remote sensing of nitrogen (N) concentration and in vitro dry matter digestibility (IVDMD) in herbage can help livestock managers make timely decisions for adjusting stocking rate and managing pastures during the grazing season. Traditional laboratory analyses of N and IVDMD are time-consuming and costly. Non-destructive measurements of canopy hyperspectral reflectance of pasture may provide a rapid and inexpensive means of estimating these measures of nutritive value. Using a portable spectroradiometer, canopy reflectance was measured in eight warm-season grass pastures in the USA in June and July in 2002 and 2003 to develop and validate algorithms for estimating N concentration and IVDMD of herbage. Nitrogen concentration of herbage was linearly correlated (r = 082; P < 0001) with a ratio of reflectance in the 705- and 1685-nm wavebands (R705/R1685) and IVDMD was correlated with R705/R535 (r = 074; P < 0001). Compared with simple linear regressions of N concentration and IVDMD in herbage with two-waveband reflectance ratios, multiple regression, using maximum r2 improvement, band-depth analysis with step-wise regression, and partial least-squares regression enhanced the correlation between N concentration and IVDMD of herbage and canopy reflectance values (081 , |r| , 090; P < 0001). Validation of the prediction equations indicated that multiple regression only slightly improved accuracy of a model for predicting N concentration and IVDMD of herbage compared with simple linear regression of reflectance ratios. Results suggest that the N concentration and IVDMD of herbage of warm-season grass pastures can be rapidly and non-destructively estimated during the grazing season using canopy reflectance in a few narrow wavebands. [source]


Sleep and Headache Disorders: Clinical Recommendations for Headache Management

HEADACHE, Issue 2006
Jeanetta C. Rains PhD
Clinical practice points were drawn from a review of sleep and headache disorders published in the regular issue of Headache (released in tandem with this supplement). The recommendations include: (1) Sleep as well as psychiatric disorders tend to become prevalent in more complex and severe headache patterns and regulation of sleep and mood may favorably impact headache threshold; (2) Specific headache patterns, irrespective of headache diagnosis, are suggestive of a potential sleep disorder (eg, "awakening" or morning headache, chronic daily headache); (3) Sleep disorders most implicated with headache include obstructive sleep apnea, primary insomnia, and circadian phase abnormalities, and treatment of such sleep disorders may improve or resolve headache; (4) Inexpensive screening tools (eg, sleep history interview, headache/sleep diary, validated questionnaires, prediction equations) aid identification of patients warranting polysomnography; and (5) Pharmacologic and behavioral therapies are effective in the regulation of sleep and are compatible with usual headache care. [source]


Prediction of concentrated flow width in ephemeral gully channels

HYDROLOGICAL PROCESSES, Issue 10 2002
J. Nachtergaele
Abstract Empirical prediction equations of the form W = aQb have been reported for rills and rivers, but not for ephemeral gullies. In this study six experimental data sets are used to establish a relationship between channel width (W, m) and flow discharge (Q, m3 s,1) for ephemeral gullies formed on cropland. The resulting regression equation (W = 251 Q0412; R2 = 072; n = 67) predicts observed channel width reasonably well. Owing to logistic limitations related to the respective experimental set ups, only relatively small runoff discharges (i.e. Q < 002 m3s,1) were covered. Using field data, where measured ephemeral gully channel width was attributed to a calculated peak runoff discharge on sealed cropland, the application field of the regression equation was extended towards larger discharges (i.e. 5 10,4m3s,1 < Q < 01 m3s,1). Comparing W,Q relationships for concentrated flow channels revealed that the discharge exponent (b) varies from 03 for rills over 04 for gullies to 05 for rivers. This shift in b may be the result of: (i) differences in flow shear stress distribution over the wetted perimeter between rills, gullies and rivers, (ii) a decrease in probability of a channel formed in soil material with uniform erosion resistance from rills over gullies to rivers and (iii) a decrease in average surface slope from rills over gullies to rivers. The proposed W,Q equation for ephemeral gullies is valid for (sealed) cropland with no significant change in erosion resistance with depth. Two examples illustrate limitations of the W,Q approach. In a first example, vertical erosion is hindered by a frozen subsoil. The second example relates to a typical summer situation where the soil moisture profile of an agricultural field makes the top 002 m five times more erodible than the underlying soil material. For both cases observed W values are larger than those predicted by the established channel width equation for concentrated flow on cropland. For the frozen soils the equation W = 317 Q0368 (R2 = 078; n = 617) was established, but for the summer soils no equation could be established. Copyright 2002 John Wiley & Sons, Ltd. [source]


Comparison of in vitro starch digestibility methods for predicting the glycaemic index of grain foods

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2008
Kirsty A Germaine
Abstract BACKGROUND:In vitro starch digestibility tests are useful for the prediction of glycaemic index (GI). However, there are no internationally recognised methods and no one method has been found to be suitable for all food types. This study compared six in vitro methods, using four grain foods, including those with a varied particle size and soluble fibre content. Method variations included using chewing or mincing, mincing with or without amylase and incubation in a restricted versus non-restricted system. Hydrolysis index (HI) values, calculated from the starch digestibility curves and GI prediction equations were used to compare the in vitro results to GI. RESULTS: HI values for five of the six methods ranked all foods in the same order as the GI values. Using a GI prediction equation (predicted GIHI) the mincing (without amylase) non-restricted method had the smallest standard error of prediction between the predicted GIHI and GI values. This method was then validated using 14 grain foods and demonstrated a significant correlation (r = 0.93, P < 0.01) between the in vitro starch digestibility and reported GI responses. CONCLUSIONS: The non-restricted mincing method showed good potential as a new in vitro starch digestibility method for predicting GI in grain foods. Copyright 2007 Society of Chemical Industry [source]


Chemical and sensory stability of roasted high-oleic peanuts from Argentina

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2006
Valeria Nepote
Abstract The purpose of this work was to determine the chemical and sensory stability of roasted peanuts prepared with a high-oleic cultivar, Granoleico (GO-RP), in comparison to a regular cultivar, Tegua (T-RP), from Argentina. Consumer test of fresh products, oxidative stability estimated by chemical indicators (peroxide and p -anisidine values, conjugated dienes and trienes) and descriptive analyses during storage (at 23 and 40 C) were performed on the roasted peanuts. GO-RP did not differ from T-RP as regards consumer acceptance. Chemical indicator values and oxidized and cardboard flavors showed lower increments for GO-RP than T-RP during storage. Roasted peanutty flavor decreased for both samples at 23 and 40 C. Using prediction equations, roasted peanuts prepared with kernels of high-oleic contents had shelf lives of 25 (at 23 C) and 10 (at 40 C) times longer than those elaborated with normal peanuts. Copyright 2006 Society of Chemical Industry [source]


Normative reference values for lung transfer factor in Isfahan, Iran

RESPIROLOGY, Issue 4 2006
Babak AMRA
Objectives and background: Transfer factor or carbon monoxide diffusing capacity (DLCO) is a particularly valuable test of the appropriateness of gas exchange across the alveolocapillary membrane. The purpose of this study is to derive predictive equations for DLCO and its derivative volume-corrected DLCO (DLCO/VA) measured by single-breath method in a large non-smoking population sample in Isfahan. Methodology: We evaluated 1429 randomly selected subjects (732 men, aged 5,85 years). Gender-specific linear prediction equations were developed by multiple regression analysis; with measured DLCO, and DLCO/VA values (mmol/min/kPa), as dependent variables regressed against age (A), height (H) and body surface area (BSA). Results: For both genders, age had negative effects on DLCO, while height had a positive effect on DLCO and DLCO/VA (P < 0.01). The prediction equations for DLCO and DLCO/VA are: ,0.152 height , 0.056 age , 11.595' and ,,0.12 age + 2.467', for men and: ,,0.035 age , 0.133 height , 10.707' and ,,0.012 age , 0.02 height + 2.755', for women, respectively. Conclusions: Our results therefore provide an original frame of reference for either DLCO or DLCO/VA in Iranian population, obtained from a standardized single-breath technique. [source]


Measurement of total body composition changes of common carp by computer tomography

AQUACULTURE RESEARCH, Issue 12 2003
Csaba Hancz
Abstract The crude fat and protein content of the total body was estimated by X-ray computer tomography (CT) and determined by chemical analyses during a feeding experiment with sexually matured common carp. Between 21 and 35 serial scans were taken of altogether 41 fish and samples from the homogenized body were prepared for chemical analyses. Experimental fish with an average body weight of 1453 g originated from a commercial stock of mirror carp. Two feeding regimes (carp feed and carp feed+ad libitum maize) were applied for 57 days and followed by a fasting period of 27 days. Both feeding regimes significantly increased the crude fat content of the whole body that did not decrease during fasting in spite of high water temperature (22C). No significant changes were observed in crude protein content. The variables used for producing the prediction equations were taken from the density values of the Hounsfield scale, on a range between ,90 and +160, by summing the frequencies within each interval of 10 values. Whole body fat content could be estimated with R2=0.89,0.91 accuracy with the principal component analysis using data of all (seven) body regions and only dorsal fin region respectively. Adequate linear regression model could not be calculated by the same procedure for crude protein. Three-dimensional ,volumetric' estimation of fat tissue was also carried out on the basis of fat index showing high correlation with measured fat content. The changes of body composition of individual fish can be followed by sequential CT scanning. [source]


A new accurate method for predicting lithium clearance and daily dosage requirements in adult psychiatric patients

BIPOLAR DISORDERS, Issue 3 2008
Hisham 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]


The validity of the Computer Science and Applications activity monitor for use in coronary artery disease patients during level walking

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2002
Ulf Ekelund
Summary The principal aim of the present study was to examine the validity of the Computer Science and Applications (CSA) activity monitor during level walking in coronary artery disease (CAD) patients. As a secondary aim, we evaluated the usefulness of two previously published energy expenditure (EE) prediction equations. Thirty-four subjects (29 men and five women), all with diagnosed CAD, volunteered to participate. Oxygen uptake (VO2) was measured by indirect calorimetry during walking on a motorized treadmill at three different speeds (32, 48 and 64 km h,1). Physical activity was measured simultaneously using the CSA activity monitor, secured directly to the skin on the lower back (i.e. lumbar vertebrae 4,5) with an elastic belt. The mean (SD) activity counts were 1208 429, 3258 753 and 5351 876 counts min,1, at the three speeds, respectively (P<0001). Activity counts were significantly correlated to speed (r=092; P<0001), VO2 (ml kg,1 min,1; r=087; P<0001) and EE (kcal min,1; r=085, P<0001). A stepwise linear regression analysis showed that activity counts and body weight together explained 75% of the variation in EE. Predicted EE from previously published equations differed significantly when used in this group of CAD patients. In conclusion, the CSA activity monitor is a valid instrument for assessing the intensity of physical activity during treadmill walking in CAD patients. Energy expenditure can be predicted from body weight and activity counts. [source]