Social and Behavioural Outcomes in Children Diagnosed with Autism Spectrum Disorders: A Longitudinal Cohort Study

ERIC Educational Resources Information Center

Russell, Ginny; Golding, Jean; Norwich, Brahm; Emond, Alan; Ford, Tamsin; Steer, Colin

2012-01-01

Objective: To compare social and behavioural outcomes between children formally diagnosed with autism spectrum disorders (ASD) with those of children who displayed autistic traits at preschool age, but remained undiagnosed as teenagers. Method: A secondary analysis of data from a birth cohort study, the Avon Longitudinal Study of Parents and…

Multivariate longitudinal data analysis with censored and intermittent missing responses.

PubMed

Lin, Tsung-I; Lachos, Victor H; Wang, Wan-Lun

2018-05-08

The multivariate linear mixed model (MLMM) has emerged as an important analytical tool for longitudinal data with multiple outcomes. However, the analysis of multivariate longitudinal data could be complicated by the presence of censored measurements because of a detection limit of the assay in combination with unavoidable missing values arising when subjects miss some of their scheduled visits intermittently. This paper presents a generalization of the MLMM approach, called the MLMM-CM, for a joint analysis of the multivariate longitudinal data with censored and intermittent missing responses. A computationally feasible expectation maximization-based procedure is developed to carry out maximum likelihood estimation within the MLMM-CM framework. Moreover, the asymptotic standard errors of fixed effects are explicitly obtained via the information-based method. We illustrate our methodology by using simulated data and a case study from an AIDS clinical trial. Experimental results reveal that the proposed method is able to provide more satisfactory performance as compared with the traditional MLMM approach. Copyright © 2018 John Wiley & Sons, Ltd.

Multivariate Analysis of Longitudinal Rates of Change

PubMed Central

Bryan, Matthew; Heagerty, Patrick J.

2016-01-01

Longitudinal data allow direct comparison of the change in patient outcomes associated with treatment or exposure. Frequently, several longitudinal measures are collected that either reflect a common underlying health status, or characterize processes that are influenced in a similar way by covariates such as exposure or demographic characteristics. Statistical methods that can combine multivariate response variables into common measures of covariate effects have been proposed by Roy and Lin [1]; Proust-Lima, Letenneur and Jacqmin-Gadda [2]; and Gray and Brookmeyer [3] among others. Current methods for characterizing the relationship between covariates and the rate of change in multivariate outcomes are limited to select models. For example, Gray and Brookmeyer [3] introduce an “accelerated time” method which assumes that covariates rescale time in longitudinal models for disease progression. In this manuscript we detail an alternative multivariate model formulation that directly structures longitudinal rates of change, and that permits a common covariate effect across multiple outcomes. We detail maximum likelihood estimation for a multivariate longitudinal mixed model. We show via asymptotic calculations the potential gain in power that may be achieved with a common analysis of multiple outcomes. We apply the proposed methods to the analysis of a trivariate outcome for infant growth and compare rates of change for HIV infected and uninfected infants. PMID:27417129

Meta-Analysis of Effect Sizes Reported at Multiple Time Points Using General Linear Mixed Model.

PubMed

Musekiwa, Alfred; Manda, Samuel O M; Mwambi, Henry G; Chen, Ding-Geng

2016-01-01

Meta-analysis of longitudinal studies combines effect sizes measured at pre-determined time points. The most common approach involves performing separate univariate meta-analyses at individual time points. This simplistic approach ignores dependence between longitudinal effect sizes, which might result in less precise parameter estimates. In this paper, we show how to conduct a meta-analysis of longitudinal effect sizes where we contrast different covariance structures for dependence between effect sizes, both within and between studies. We propose new combinations of covariance structures for the dependence between effect size and utilize a practical example involving meta-analysis of 17 trials comparing postoperative treatments for a type of cancer, where survival is measured at 6, 12, 18 and 24 months post randomization. Although the results from this particular data set show the benefit of accounting for within-study serial correlation between effect sizes, simulations are required to confirm these results.

Rasch-family models are more valuable than score-based approaches for analysing longitudinal patient-reported outcomes with missing data.

PubMed

de Bock, Élodie; Hardouin, Jean-Benoit; Blanchin, Myriam; Le Neel, Tanguy; Kubis, Gildas; Bonnaud-Antignac, Angélique; Dantan, Étienne; Sébille, Véronique

2016-10-01

The objective was to compare classical test theory and Rasch-family models derived from item response theory for the analysis of longitudinal patient-reported outcomes data with possibly informative intermittent missing items. A simulation study was performed in order to assess and compare the performance of classical test theory and Rasch model in terms of bias, control of the type I error and power of the test of time effect. The type I error was controlled for classical test theory and Rasch model whether data were complete or some items were missing. Both methods were unbiased and displayed similar power with complete data. When items were missing, Rasch model remained unbiased and displayed higher power than classical test theory. Rasch model performed better than the classical test theory approach regarding the analysis of longitudinal patient-reported outcomes with possibly informative intermittent missing items mainly for power. This study highlights the interest of Rasch-based models in clinical research and epidemiology for the analysis of incomplete patient-reported outcomes data. © The Author(s) 2013.

Comparison of endothelial changes and power settings between torsional and longitudinal phacoemulsification.

PubMed

Reuschel, Anna; Bogatsch, Holger; Barth, Thomas; Wiedemann, Renate

2010-11-01

To compare the intraoperative and postoperative outcomes of conventional longitudinal phacoemulsification and torsional phacoemulsification. Department of Ophthalmology, University of Leipzig, Germany. Randomized single-center clinical trial. Eyes with senile cataract were randomized to have phacoemulsification using the Infiniti Vision System and the torsional mode (OZil) or conventional longitudinal mode. Primary outcomes were corrected distance visual acuity (CDVA) and central endothelial cell density (ECD), calculated according to the Conference on Harmonisation-E9 Guidelines in which missing values were substituted by the median in each group (primary analysis) and the loss was then calculated using actual data (secondary analysis). Secondary outcomes were ultrasound (US) time, cumulative dissipated energy (CDE), and percentage total equivalent power in position 3. Postoperative follow-up was at 3 months. The mean preoperative CDVA was 0.41 logMAR in the torsional group and 0.38 logMAR in the longitudinal group, improving to 0.07 logMAR postoperatively in both groups. The mean ECD loss was 7.2% ± 4.6% in the torsional group (72 patients) and 7.1% ± 4.4% in the longitudinal group (76 patients), with no statistically significant differences in the primary analysis (P = .342) or secondary analysis (P = .906). The mean US time, CDE, and percentage total equivalent power in position 3 were statistically significantly lower in the torsional group (98 patients) than in the longitudinal group (94 patients) (P<.001). The torsional mode was as safe as the longitudinal mode in phacoemulsification for age-related cataract. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Shashaank; Belianinov, Alex; Okatan, Mahmut B

(001)pc textured K0.5Na0.5NbO3 (KNN) ceramic was found to exhibit a 65% improvement in the longitudinal piezoelectric response as compared to its random counterpart. Piezoresponse force microscopy study revealed the existence of larger 180 and non-180 domains for textured ceramic as compared to that of the random ceramic. Improvement in piezoresponse by the development of (001)pc texture is discussed in terms of the crystallographic nature of KNN and domain morphology. A comparative analysis performed with a rhombohedral composition suggested that the improvement in longitudinal piezoresponse of polycrystalline ceramics by the development of (001)pc texture is limited by the crystal structure.

Longitudinal structure function from logarithmic slopes of F2 at low x

NASA Astrophysics Data System (ADS)

Boroun, G. R.

2018-01-01

Using Laplace transform techniques, I calculate the longitudinal structure function FL(x ,Q2) from the scaling violations of the proton structure function F2(x ,Q2) and make a critical study of this relationship between the structure functions at leading order (LO) up to next-to-next-to leading order (NNLO) analysis at small x . Furthermore, I consider heavy quark contributions to the relation between the structure functions, which leads to compact formula for Nf=3 +Heavy . The nonlinear corrections to the longitudinal structure function at LO up to NNLO analysis are shown in the Nf=4 (light quark flavor) based on the nonlinear corrections at R =2 and R =4 GeV-1 . The results are compared with experimental data of the longitudinal proton structure function FL in the range of 6.5 ≤Q2≤800 GeV2 .

Longitudinal Trajectories of Gestural and Linguistic Abilities in Very Preterm Infants in the Second Year of Life

ERIC Educational Resources Information Center

Sansavini, Alessandra; Guarini, Annalisa; Savini, Silvia; Broccoli, Serena; Justice, Laura; Alessandroni, Rosina; Faldella, Giacomo

2011-01-01

The present study involved a systematic longitudinal analysis, with three points of assessment in the second year of life, of gestures/actions, word comprehension, and word production in a sample of very preterm infants compared to a sample of full-term infants. The relationships among these competencies as well as their predictive value on…

Detecting glaucomatous change in visual fields: Analysis with an optimization framework.

PubMed

Yousefi, Siamak; Goldbaum, Michael H; Varnousfaderani, Ehsan S; Belghith, Akram; Jung, Tzyy-Ping; Medeiros, Felipe A; Zangwill, Linda M; Weinreb, Robert N; Liebmann, Jeffrey M; Girkin, Christopher A; Bowd, Christopher

2015-12-01

Detecting glaucomatous progression is an important aspect of glaucoma management. The assessment of longitudinal series of visual fields, measured using Standard Automated Perimetry (SAP), is considered the reference standard for this effort. We seek efficient techniques for determining progression from longitudinal visual fields by formulating the problem as an optimization framework, learned from a population of glaucoma data. The longitudinal data from each patient's eye were used in a convex optimization framework to find a vector that is representative of the progression direction of the sample population, as a whole. Post-hoc analysis of longitudinal visual fields across the derived vector led to optimal progression (change) detection. The proposed method was compared to recently described progression detection methods and to linear regression of instrument-defined global indices, and showed slightly higher sensitivities at the highest specificities than other methods (a clinically desirable result). The proposed approach is simpler, faster, and more efficient for detecting glaucomatous changes, compared to our previously proposed machine learning-based methods, although it provides somewhat less information. This approach has potential application in glaucoma clinics for patient monitoring and in research centers for classification of study participants. Copyright © 2015 Elsevier Inc. All rights reserved.

Analysis of wind tunnel test results for a 9.39-per cent scale model of a VSTOL fighter/attack aircraft. Volume 2: Evaluation of prediction methodologies

NASA Technical Reports Server (NTRS)

Lummus, J. R.; Joyce, G. T.; Omalley, C. D.

1980-01-01

An evaluation of current prediction methodologies to estimate the aerodynamic uncertainties identified for the E205 configuration is presented. This evaluation was accomplished by comparing predicted and wind tunnel test data in three major categories: untrimmed longitudinal aerodynamics; trimmed longitudinal aerodynamics; and lateral-directional aerodynamic characteristics.

Predicting Children's Media Use in the USA: Differences in Cross-Sectional and Longitudinal Analysis

ERIC Educational Resources Information Center

Lee, Sook-Jung; Bartolic, Silvia; Vandewater, Elizabeth A.

2009-01-01

The purpose of this paper is to examine the predictors of children's media use in the USA, comparing cross-sectional and longitudinal analyses. Data come from Waves 1 and 2 of the Child Development Supplement (CDS-I; CDS-II), a nationally representative sample of American children aged 0-12 in 1997 and 5-18 in 2002. Twenty-four hour time use…

Longitudinal Commercial Claims-Based Cost Analysis of Diabetic Retinopathy Screening Patterns.

PubMed

Fitch, Kathryn; Weisman, Thomas; Engel, Tyler; Turpcu, Adam; Blumen, Helen; Rajput, Yamina; Dave, Purav

2015-09-01

Diabetic retinopathy is one of the most common complications of diabetes. The screening of patients with diabetes to detect retinopathy is recommended by several professional guidelines but is an underutilized service. To analyze the relationship between the frequency of retinopathy screening and the cost of care in adult patients with diabetes. Truven Health MarketScan commercial databases (2000-2013) were used to identify the diabetic population aged 18 to 64 years for the performance of a 2001-2013 annual trend analysis of patients with type 1 and type 2 diabetes and a 10-year longitudinal analysis of patients with newly diagnosed type 2 diabetes. In the trend analysis, the prevalence of diabetes, screening rate, and allowed cost per member per month (PMPM) were calculated. In the longitudinal analysis, data from 4 index years (2001-2004) of patients newly diagnosed with type 2 diabetes were combined, and the costs were adjusted to be comparable to the 2004 index year cohort, using the annual diabetes population cost trends calculated in the trend analysis. The longitudinal population was segmented into the number of years of diabetic retinopathy screening (ie, 0, 1-4, 5-7, and 8-10), and the relationship between the years of screening and the PMPM allowed costs was analyzed. The difference in mean incremental cost between years 1 and 10 in each of the 4 cohorts was compared after adjusting for explanatory variables. In the trend analysis, between 2001 and 2013, the prevalence of diabetes increased from 3.93% to 5.08%, retinal screening increased from 26.27% to 29.58%, and the average total unadjusted allowed cost of care for each patient with diabetes increased from $822 to $1395 PMPM. In the longitudinal analysis, the difference between the screening cohorts' mean incremental cost increase was $185 between the 0- and 1-4-year cohorts (P <.003) and $202 between the 0- and 5-7-year cohorts (P <.023). The cost differences between the other cohorts, including $217 between the 0- and 8-10-year cohorts (P <.066), were not statistically significant. Based on our analysis, the annual retinopathy screening rate for patients with diabetes has remained low since 2001, and has been well below the guideline-recommended screening levels. For patients with type 2 diabetes, the mean increase in healthcare expenditures over a 10-year period after diagnosis is not statistically different among those with various retinopathy screening rates, although the increase in healthcare spending is lower for patients with diabetes who were not screened for retinopathy compared with patients who did get screened.

Longitudinal Assessment of Self-Reported Recent Back Pain and Combat Deployment in the Millennium Cohort Study

DTIC Science & Technology

2016-11-15

participants who were followed for the development of back pain for an average of 3.9 years. Methods. Descriptive statistics and longitudinal...health, military personnel, occupational health, outcome assessment, statistics, survey methodology . Level of Evidence: 3 Spine 2016;41:1754–1763ack...based on the National Health and Nutrition Examination Survey.21 Statistical Analysis Descriptive and univariate analyses compared character- istics

Simulation and characterization of silicon-based 0.5-MHz ultrasonic nozzles

NASA Astrophysics Data System (ADS)

Song, Y. L.; Tsai, S. C.; Chen, W. J.; Chou, Y. F.; Tseng, T. K.; Tsai, C. S.

2004-01-01

This paper compares the simulation results with the experimental results of impedance analysis and longitudinal vibration measurement of micro-fabricated 0.5 MHz silicon-based ultrasonic nozzles. Impedance analysis serves as a good diagnostic tool for evaluation of longitudinal vibration of the nozzles. Each nozzle is made of a piezoelectric drive section and a silicon-resonator consisting of multiple Fourier horns each with half wavelength design and twice amplitude magnification. The experimental results verified the simulation prediction of one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude gain at the nozzle tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical value of 2n. Using this design, very high vibration amplitude at the nozzle tip can be achieved with no reduction in the tip cross sectional area. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.

Item Response Theory as an Efficient Tool to Describe a Heterogeneous Clinical Rating Scale in De Novo Idiopathic Parkinson's Disease Patients.

PubMed

Buatois, Simon; Retout, Sylvie; Frey, Nicolas; Ueckert, Sebastian

2017-10-01

This manuscript aims to precisely describe the natural disease progression of Parkinson's disease (PD) patients and evaluate approaches to increase the drug effect detection power. An item response theory (IRT) longitudinal model was built to describe the natural disease progression of 423 de novo PD patients followed during 48 months while taking into account the heterogeneous nature of the MDS-UPDRS. Clinical trial simulations were then used to compare drug effect detection power from IRT and sum of item scores based analysis under different analysis endpoints and drug effects. The IRT longitudinal model accurately describes the evolution of patients with and without PD medications while estimating different progression rates for the subscales. When comparing analysis methods, the IRT-based one consistently provided the highest power. IRT is a powerful tool which enables to capture the heterogeneous nature of the MDS-UPDRS.

Neuropsychometric tests in cross sectional and longitudinal studies - a regression analysis of ADAS - cog, SKT and MMSE.

PubMed

Ihl, R; Grass-Kapanke, B; Jänner, M; Weyer, G

1999-11-01

In clinical and drug studies, different neuropsychometric tests are used. So far, no empirical data have been published to compare studies using different tests. The purpose of this study was to calculate a regression formula allowing a comparison of cross-sectional and longitudinal data from three neuropsychometric tests that are frequently used in drug studies (Alzheimer's Disease Assessment Scale, ADAS-cog; Syndrom Kurz Test, SKT; Mini Mental State Examination, MMSE). 177 patients with dementia according to ICD10 criteria were studied for the cross sectional and 61 for the longitudinal analysis. Correlations and linear regressions were calculated between tests. Significance was proven with ANOVA and t-tests using the SPSS statistical package. Significant Spearman correlations and slopes in the regression occurred in the cross sectional analysis (ADAS-cog-SKT r(s) = 0.77, slope = 0.45, SKT-ADAS-cog slope = 1.3, r2 = 0.59; ADAS-cog-MMSE r2 = 0.76, slope = -0.42, MMSE-ADAS-cog slope = -1.5, r2 = 0.64; MMSE-SKT r(s) = -0.79, slope = -0.87, SKT-MMSE slope = -0.71, r2 = 0.62; p<0.001 after Bonferroni correction; N = 177) and in the longitudinal analysis (SKT-ADAS-cog, r(s) = 0.48, slope = 0.69, ADAS-cog-SKT slope = 0.69, p<0.001, r2 = 0.32, MMSE-SKT, r(s) = 0.44, slope = -0.41, SKT-MMSE, slope = -0.55, p<0.001, r2 = 0.21). The results allow calculation of ADAS-scores when SKT scores are given, and vice versa. In longitudinal studies or in the course of the disease, scores assessed with the ADAS-cog and the SKT may now be statistically compared. In all comparisons, bottom and ceiling effects of the tests have to be taken into account.

Evaluation of longitudinal tracking and data mining for an imaging informatics-based multiple sclerosis e-folder (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ma, Kevin C.; Forsyth, Sydney; Amezcua, Lilyana; Liu, Brent J.

2017-03-01

We have designed and developed a multiple sclerosis eFolder system for patient data storage, image viewing, and automatic lesion quantification results to allow patient tracking. The web-based system aims to be integrated in DICOM-compliant clinical and research environments to aid clinicians in patient treatments and data analysis. The system quantifies lesion volumes, identify and register lesion locations to track shifts in volume and quantity of lesions in a longitudinal study. We aim to evaluate the two most important features of the system, data mining and longitudinal lesion tracking, to demonstrate the MS eFolder's capability in improving clinical workflow efficiency and outcome analysis for research. In order to evaluate data mining capabilities, we have collected radiological and neurological data from 72 patients, 36 Caucasian and 36 Hispanic matched by gender, disease duration, and age. Data analysis on those patients based on ethnicity is performed, and analysis results are displayed by the system's web-based user interface. The data mining module is able to successfully separate Hispanic and Caucasian patients and compare their disease profiles. For longitudinal lesion tracking, we have collected 4 longitudinal cases and simulated different lesion growths over the next year. As a result, the eFolder is able to detect changes in lesion volume and identifying lesions with the most changes. Data mining and lesion tracking evaluation results show high potential of eFolder's usefulness in patientcare and informatics research for multiple sclerosis.

Research on FBG-based longitudinal-acousto-optic modulator with Fourier mode coupling method.

PubMed

Li, Zhuoxuan; Pei, Li; Liu, Chao; Ning, Tigang; Yu, Shaowei

2012-10-20

Fourier mode coupling model was first applied to achieve the spectra property of a fiber Bragg grating (FBG)-based longitudinal-acousto-optic modulator. Compared with traditional analysis algorithms, such as the transfer matrix method, the Fourier mode coupling model could improve the computing efficiency up to 100 times with a guarantee of accuracy. In this paper, based on the theoretical analysis of this model, the spectra characteristics of the modulator in different frequencies and acoustically induced strains were numerically simulated. In the experiment, a uniform FBG was modulated by acoustic wave (AW) at 12 different frequencies. In particular, the modulator responses at 563 and 885.5 KHz with three different lead zirconate titanate (PZT) loads applied were plotted for illustration, and the linear fitting of experimental data demonstrated a good match with the simulation result. The acoustic excitation of the longitudinal wave is obtained using a conic silica horn attached to the surface of a shear-mode PZT plate paralleled to the fiber axis. This way of generating longitudinal AW with a transversal PZT may shed light on the optimal structural design for the FBG-based longitudinal-acousto-optic modulator.

FE Analysis of Buckling Behavior Caused by Welding in Thin Plates of High Tensile Strength Steel

NASA Astrophysics Data System (ADS)

Wang, Jiangchao; Rashed, Sherif; Murakawa, Hidekazu

2014-12-01

The target of this study was to investigate buckling behavior during the entire welding process which consists of the heating and the cooling processes. For thin plate structures made of high tensile strength steel, not only residual buckling during or after cooling down but also transient buckling during heating may occur. The thermal elastic plastic FE analysis to investigate welding-induced buckling during the entire welding process is presented. Because of the high yield stress of high tensile strength steel, larger longitudinal compressive thermal stress is produced near the welding line compared with that in the case of carbon steel. Therefore, the plate may buckle due to thermal expansion, before the material nears yielding. During cooling down, the longitudinal compressive thermal stress close to the welding line disappears, and longitudinal tensile residual stress is produced due to contraction. Meanwhile, longitudinal compressive residual stress occurs far from the welding line to balance the tensile stress close to the welding line. This distribution of longitudinal residual stress would change the deformed dish shape of transient buckling into a saddle buckling type when the stress exceeds the critical buckling condition.

Comparison of longitudinal excursion of a nerve-phantom model using quantitative ultrasound imaging and motion analysis system methods: A convergent validity study.

PubMed

Paquette, Philippe; El Khamlichi, Youssef; Lamontagne, Martin; Higgins, Johanne; Gagnon, Dany H

2017-08-01

Quantitative ultrasound imaging is gaining popularity in research and clinical settings to measure the neuromechanical properties of the peripheral nerves such as their capability to glide in response to body segment movement. Increasing evidence suggests that impaired median nerve longitudinal excursion is associated with carpal tunnel syndrome. To date, psychometric properties of longitudinal nerve excursion measurements using quantitative ultrasound imaging have not been extensively investigated. This study investigates the convergent validity of the longitudinal nerve excursion by comparing measures obtained using quantitative ultrasound imaging with those determined with a motion analysis system. A 38-cm long rigid nerve-phantom model was used to assess the longitudinal excursion in a laboratory environment. The nerve-phantom model, immersed in a 20-cm deep container filled with a gelatin-based solution, was moved 20 times using a linear forward and backward motion. Three light-emitting diodes were used to record nerve-phantom excursion with a motion analysis system, while a 5-cm linear transducer allowed simultaneous recording via ultrasound imaging. Both measurement techniques yielded excellent association ( r  = 0.99) and agreement (mean absolute difference between methods = 0.85 mm; mean relative difference between methods = 7.48 %). Small discrepancies were largely found when larger excursions (i.e. > 10 mm) were performed, revealing slight underestimation of the excursion by the ultrasound imaging analysis software. Quantitative ultrasound imaging is an accurate method to assess the longitudinal excursion of an in vitro nerve-phantom model and appears relevant for future research protocols investigating the neuromechanical properties of the peripheral nerves.

Analysis of the proton longitudinal structure function from the gluon distribution function

NASA Astrophysics Data System (ADS)

Boroun, G. R.; Rezaei, B.

2012-11-01

We make a critical, next-to-leading order, study of the relationship between the longitudinal structure function F L and the gluon distribution proposed in Cooper-Sarkar et al. (Z. Phys. C 39:281, 1988; Acta Phys. Pol. B 34:2911 2003), which is frequently used to extract the gluon distribution from the proton longitudinal structure function at small x. The gluon density is obtained by expanding at particular choices of the point of expansion and compared with the hard Pomeron behavior for the gluon density. Comparisons with H1 data are made and predictions for the proposed best approach are also provided.

Longitudinal Patterns of Glycemic Control and Blood Pressure in Pregnant Women with Type 1 Diabetes Mellitus: Phenotypes from Functional Data Analysis.

PubMed

Szczesniak, Rhonda D; Li, Dan; Duan, Leo L; Altaye, Mekibib; Miodovnik, Menachem; Khoury, Jane C

2016-11-01

Objective  To identify phenotypes of type 1 diabetes control and associations with maternal/neonatal characteristics based on blood pressure (BP), glucose, and insulin curves during gestation, using a novel functional data analysis approach that accounts for sparse longitudinal patterns of medical monitoring during pregnancy. Methods  We performed a retrospective longitudinal cohort study of women with type 1 diabetes whose BP, glucose, and insulin requirements were monitored throughout gestation as part of a program-project grant. Scores from sparse functional principal component analysis (fPCA) were used to classify gestational profiles according to the degree of control for each monitored measure. Phenotypes created using fPCA were compared with respect to maternal and neonatal characteristics and outcome. Results  Most of the gestational profile variation in the monitored measures was explained by the first principal component (82-94%). Profiles clustered into three subgroups of high, moderate, or low heterogeneity, relative to the overall mean response. Phenotypes were associated with baseline characteristics, longitudinal changes in glycohemoglobin A1 and weight, and to pregnancy-related outcomes. Conclusion  Three distinct longitudinal patterns of glucose, insulin, and BP control were found. By identifying these phenotypes, interventions can be targeted for subgroups at highest risk for compromised outcome, to optimize diabetes management during pregnancy. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Longitudinal Commercial Claims–Based Cost Analysis of Diabetic Retinopathy Screening Patterns

PubMed Central

Fitch, Kathryn; Weisman, Thomas; Engel, Tyler; Turpcu, Adam; Blumen, Helen; Rajput, Yamina; Dave, Purav

2015-01-01

Background Diabetic retinopathy is one of the most common complications of diabetes. The screening of patients with diabetes to detect retinopathy is recommended by several professional guidelines but is an underutilized service. Objective To analyze the relationship between the frequency of retinopathy screening and the cost of care in adult patients with diabetes. Methods Truven Health MarketScan commercial databases (2000–2013) were used to identify the diabetic population aged 18 to 64 years for the performance of a 2001–2013 annual trend analysis of patients with type 1 and type 2 diabetes and a 10-year longitudinal analysis of patients with newly diagnosed type 2 diabetes. In the trend analysis, the prevalence of diabetes, screening rate, and allowed cost per member per month (PMPM) were calculated. In the longitudinal analysis, data from 4 index years (2001–2004) of patients newly diagnosed with type 2 diabetes were combined, and the costs were adjusted to be comparable to the 2004 index year cohort, using the annual diabetes population cost trends calculated in the trend analysis. The longitudinal population was segmented into the number of years of diabetic retinopathy screening (ie, 0, 1–4, 5–7, and 8–10), and the relationship between the years of screening and the PMPM allowed costs was analyzed. The difference in mean incremental cost between years 1 and 10 in each of the 4 cohorts was compared after adjusting for explanatory variables. Results In the trend analysis, between 2001 and 2013, the prevalence of diabetes increased from 3.93% to 5.08%, retinal screening increased from 26.27% to 29.58%, and the average total unadjusted allowed cost of care for each patient with diabetes increased from $822 to $1395 PMPM. In the longitudinal analysis, the difference between the screening cohorts’ mean incremental cost increase was $185 between the 0- and 1–4–year cohorts (P <.003) and $202 between the 0- and 5–7–year cohorts (P <.023). The cost differences between the other cohorts, including $217 between the 0- and 8–10–year cohorts (P <.066), were not statistically significant. Conclusions Based on our analysis, the annual retinopathy screening rate for patients with diabetes has remained low since 2001, and has been well below the guideline-recommended screening levels. For patients with type 2 diabetes, the mean increase in healthcare expenditures over a 10-year period after diagnosis is not statistically different among those with various retinopathy screening rates, although the increase in healthcare spending is lower for patients with diabetes who were not screened for retinopathy compared with patients who did get screened. PMID:26557224

Transverse versus Longitudinal Incisions for Femoral Artery Exposure in Treating Patients with Peripheral Vascular Disease.

PubMed

Parikh, Punam P; Rubio, Gustavo A; Patel, Kunal; Gupta, Kapil; Jones, Keith; Rey, Jorge; Robinson, Handel

2018-02-01

This study evaluates differences in wound complication rate when transverse versus longitudinal incision is utilized to expose femoral vessels in managing patients with peripheral vascular disease. A retrospective review from 2013 to 2015 was conducted of 150 patients undergoing 156 lower extremity revascularizations with femoral artery exposure through a groin incision. Patients were stratified into 2 groups, transverse versus longitudinal groin incision. Data were reviewed for 3 surgeons that utilize either transverse or longitudinal groin incision in patients undergoing common or iliofemoral endarterectomies, or where femoral artery was used as inflow and/or outflow vessel for limb revascularization. Each group had a comparative outcomes analysis based on incision type. The primary outcome was wound complication, defined as any wound infection, lymphocele, hematoma, dehiscence, pseudoaneurysm, or necrosis. Other outcomes studied included unplanned return to operating room for wound complication, wound vacuum therapy, and soft-tissue flap closure. Data were analyzed using 2-tailed chi-squared test and Student's t-test. Patients in the transverse (n = 85 cases) versus longitudinal (n = 71 cases) cohorts were similar in relation to demographics and comorbidities. Overall mean follow-up was 220 days. Patients with a transverse as compared to longitudinal incision had a significantly lower overall wound complication rate, 7% vs. 42%, respectively (P < 0.001). Furthermore, transverse incisions were associated with lower incidence of unplanned return to the operating room to manage wound complications than patients with a longitudinal incision (5% vs. 23%, respectively; P < 0.001). Transverse versus longitudinal incisions were also associated with significantly lower need for wound vacuum therapy (6% vs. 15%, respectively; P < 0.05) and muscle flap closure (0% vs. 13%, respectively; P < 0.001) for wound complications. Transverse groin incisions for femoral artery exposure may offer a lower risk of wound complications for open procedures as compared to a longitudinal incision. While longitudinal incisions may have higher wound complication rates, incisional approach is contingent on anatomical circumstance and treated disease pattern. Patients should undergo appropriate preoperative counseling regarding wound healing in preparation for limb revascularization. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of Binary Multivariate Longitudinal Data via 2-Dimensional Orbits: An Application to the Agincourt Health and Socio-Demographic Surveillance System in South Africa

PubMed Central

Visaya, Maria Vivien; Sherwell, David; Sartorius, Benn; Cromieres, Fabien

2015-01-01

We analyse demographic longitudinal survey data of South African (SA) and Mozambican (MOZ) rural households from the Agincourt Health and Socio-Demographic Surveillance System in South Africa. In particular, we determine whether absolute poverty status (APS) is associated with selected household variables pertaining to socio-economic determination, namely household head age, household size, cumulative death, adults to minor ratio, and influx. For comparative purposes, households are classified according to household head nationality (SA or MOZ) and APS (rich or poor). The longitudinal data of each of the four subpopulations (SA rich, SA poor, MOZ rich, and MOZ poor) is a five-dimensional space defined by binary variables (questions), subjects, and time. We use the orbit method to represent binary multivariate longitudinal data (BMLD) of each household as a two-dimensional orbit and to visualise dynamics and behaviour of the population. At each time step, a point (x, y) from the orbit of a household corresponds to the observation of the household, where x is a binary sequence of responses and y is an ordering of variables. The ordering of variables is dynamically rearranged such that clusters and holes associated to least and frequently changing variables in the state space respectively, are exposed. Analysis of orbits reveals information of change at both individual- and population-level, change patterns in the data, capacity of states in the state space, and density of state transitions in the orbits. Analysis of household orbits of the four subpopulations show association between (i) households headed by older adults and rich households, (ii) large household size and poor households, and (iii) households with more minors than adults and poor households. Our results are compared to other methods of BMLD analysis. PMID:25919116

A longitudinal study of changes in noticing and treating patients' overweight by Dutch GPs between 1997 and 2007.

PubMed

van Dijk, Elske; Kampen, Jarl K; Hiddink, Gerrit J; Renes, Reint Jan; van Binsbergen, Jaap J; van Woerkum, Cees M J

2012-04-01

One of the stakeholders in tackling the rise and health consequences of overweight and obesity is the general practice physician (GP). GPs are in a good position to inform and give nutrition guidance to overweight patients. Assessment of working mechanism of determinants of the nutrition guidance practice: noticing patients' overweight and guidance of treatment by GPs [linear analysis of structural relations (LISREL) path model] in a longitudinal study. This longitudinal study measured data in 1992, 1997 and 2007. The 1992 LISREL path model (Hiddink GJ, Hautvast J, van Woerkum CMJ, Fieren CJ, van t'Hof MA. Nutrition guidance by primary-care physicians: LISREL analysis improves understanding. Prev Med 1997; 26: 29-36.) demonstrated that 'noticing patients' overweight and guidance of treatment' was directly and indirectly influenced by predisposing factors, driving forces and perceived barriers. This article defines and discusses the path analysis of the 2007 data (compared with 1997). This analysis shows both similarity and differences in working mechanism of determinants of noticing patients' overweight and guidance of treatment between 1997 and 2007. The backbone of the mechanism with four predisposing factors is the similarity. The number of driving forces and of paths through intermediary factors to the dependent variable constitutes the difference. The backbone of the working mechanism of determinants of the nutrition guidance practice: noticing patients' overweight and guidance of treatment by GPs was similar in 2007 and 1997. The influence of GPs task perception on noticing patients' overweight and guidance of treatment considerably increased in 2007 compared to 1997. The longitudinal character of this article gives a strong practice-based evidence for weight management by GPs.

Extension of the Haseman-Elston regression model to longitudinal data.

PubMed

Won, Sungho; Elston, Robert C; Park, Taesung

2006-01-01

We propose an extension to longitudinal data of the Haseman and Elston regression method for linkage analysis. The proposed model is a mixed model having several random effects. As response variable, we investigate the sibship sample mean corrected cross-product (smHE) and the BLUP-mean corrected cross product (pmHE), comparing them with the original squared difference (oHE), the overall mean corrected cross-product (rHE), and the weighted average of the squared difference and the squared mean-corrected sum (wHE). The proposed model allows for the correlation structure of longitudinal data. Also, the model can test for gene x time interaction to discover genetic variation over time. The model was applied in an analysis of the Genetic Analysis Workshop 13 (GAW13) simulated dataset for a quantitative trait simulating systolic blood pressure. Independence models did not preserve the test sizes, while the mixed models with both family and sibpair random effects tended to preserve size well. Copyright 2006 S. Karger AG, Basel.

Analysis of longitudinal laboratory data in the presence of common selection mechanisms: a view toward greater emphasis on pre-marketing pharmaceutical safety.

PubMed

Schildcrout, Jonathan S; Jenkins, Cathy A; Ostroff, Jack H; Gillen, Daniel L; Harrell, Frank E; Trost, Donald C

2008-05-30

Pharmaceutical safety has received substantial attention in the recent past; however, longitudinal clinical laboratory data routinely collected during clinical trials to derive safety profiles are often used ineffectively. For example, these data are frequently summarized by comparing proportions (between treatment arms) of participants who cross pre-specified threshold values at some time during follow-up. This research is intended, in part, to encourage more effective utilization of these data by avoiding unnecessary dichotomization of continuous data, acknowledging and making use of the longitudinal follow-up, and combining data from multiple clinical trials. However, appropriate analyses require careful consideration of a number of challenges (e.g. selection, comparability of study populations, etc.). We discuss estimation strategies based on estimating equations and maximum likelihood for analyses in the presence of three response history-dependent selection mechanisms: dropout, follow-up frequency, and treatment discontinuation. In addition, because clinical trials' participants usually represent non-random samples from target populations, we describe two sensitivity analysis approaches. All discussions are motivated by an analysis that aims to characterize the dynamic relationship between concentrations of a liver enzyme (alanine aminotransferase) and three distinct doses (no drug, low dose, and high dose) of an nk-1 antagonist across four Phase II clinical trials.

Comparing Service Use of Early Head Start Families of Children with and without Disabilities

ERIC Educational Resources Information Center

Zajicek-Farber, Michaela L.; Wall, Shavaun M.; Kisker, Ellen E.; Luze, Gayle J.; Summers, Jean Ann

2011-01-01

The current study compared patterns of service utilization reported by Early Head Start (EHS) families of children with and without disabilities by secondary analysis of data from the longitudinal investigation of the effectiveness of EHS. Findings reveal comparable positive trends for both groups of families for receipt of services corresponding…

Measuring positive and negative affect in older adults over 56 days: comparing trait level scoring methods using the partial credit model.

PubMed

Erbacher, Monica K; Schmidt, Karen M; Boker, Steven M; Bergeman, Cindy S

2012-01-01

Positive (PA) and negative affect (NA) are important constructs in health and well-being research. Good longitudinal measurement is crucial to conducting meaningful research on relationships between affect, health, and well-being across the lifespan. One common affect measure, the PANAS, has been evaluated thoroughly with factor analysis, but not with Racsh-based latent trait models (RLTMs) such as the Partial Credit Model (PCM), and not longitudinally. Current longitudinal RLTMs can computationally handle few occasions of data. The present study compares four methods of anchoring PCMs across 56 occasions to longitudinally evaluate the psychometric properties of the PANAS plus additional items. Anchoring item parameters on mean parameter values across occasions produced more desirable results than using no anchor, using first occasion parameters as anchors, or allowing anchor values to vary across occasions. Results indicated problems with NA items, including poor category utilization, gaps in the item distribution, and a lack of easy-to-endorse items. PA items had much more desirable psychometric qualities.

Empirically Assessing the Importance of Computer Skills

ERIC Educational Resources Information Center

Baker, William M.

2013-01-01

This research determines which computer skills are important for entry-level accountants, and whether some skills are more important than others. Students participated before and after internships in public accounting. Longitudinal analysis is also provided; responses from 2001 are compared to those from 2008-2009. Responses are also compared to…

Field-aligned currents' scale analysis performed with the Swarm constellation

NASA Astrophysics Data System (ADS)

Lühr, Hermann; Park, Jaeheung; Gjerloev, Jesper W.; Rauberg, Jan; Michaelis, Ingo; Merayo, Jose M. G.; Brauer, Peter

2015-01-01

We present a statistical study of the temporal- and spatial-scale characteristics of different field-aligned current (FAC) types derived with the Swarm satellite formation. We divide FACs into two classes: small-scale, up to some 10 km, which are carried predominantly by kinetic Alfvén waves, and large-scale FACs with sizes of more than 150 km. For determining temporal variability we consider measurements at the same point, the orbital crossovers near the poles, but at different times. From correlation analysis we obtain a persistent period of small-scale FACs of order 10 s, while large-scale FACs can be regarded stationary for more than 60 s. For the first time we investigate the longitudinal scales. Large-scale FACs are different on dayside and nightside. On the nightside the longitudinal extension is on average 4 times the latitudinal width, while on the dayside, particularly in the cusp region, latitudinal and longitudinal scales are comparable.

Three Approaches to Modeling Gene-Environment Interactions in Longitudinal Family Data: Gene-Smoking Interactions in Blood Pressure.

PubMed

Basson, Jacob; Sung, Yun Ju; de Las Fuentes, Lisa; Schwander, Karen L; Vazquez, Ana; Rao, Dabeeru C

2016-01-01

Blood pressure (BP) has been shown to be substantially heritable, yet identified genetic variants explain only a small fraction of the heritability. Gene-smoking interactions have detected novel BP loci in cross-sectional family data. Longitudinal family data are available and have additional promise to identify BP loci. However, this type of data presents unique analysis challenges. Although several methods for analyzing longitudinal family data are available, which method is the most appropriate and under what conditions has not been fully studied. Using data from three clinic visits from the Framingham Heart Study, we performed association analysis accounting for gene-smoking interactions in BP at 31,203 markers on chromosome 22. We evaluated three different modeling frameworks: generalized estimating equations (GEE), hierarchical linear modeling, and pedigree-based mixed modeling. The three models performed somewhat comparably, with multiple overlaps in the most strongly associated loci from each model. Loci with the greatest significance were more strongly supported in the longitudinal analyses than in any of the component single-visit analyses. The pedigree-based mixed model was more conservative, with less inflation in the variant main effect and greater deflation in the gene-smoking interactions. The GEE, but not the other two models, resulted in substantial inflation in the tail of the distribution when variants with minor allele frequency <1% were included in the analysis. The choice of analysis method should depend on the model and the structure and complexity of the familial and longitudinal data. © 2015 WILEY PERIODICALS, INC.

Increased longitudinal contractility and diastolic function at rest in well-trained amateur Marathon runners: a speckle tracking echocardiography study

PubMed Central

2014-01-01

Background Regular physical activity reduces cardiovascular risk. There is concern that Marathon running might acutely damage the heart. It is unknown to what extent intensive physical endurance activity influences the cardiac mechanics at resting condition. Methods Eighty-four amateur marathon runners (43 women and 41 men) from Berlin-Brandenburg area who had completed at least one marathon previously underwent clinical examination and echocardiography at least 10 days before the Berlin Marathon at rest. Standard transthoracic echocardiography and 2D strain and strain rate analysis were performed. The 2D Strain and strain rate values were compared to previous published data of healthy untrained individuals. Results The average global longitudinal peak systolic strain of the left ventricle was -23 +/- 2% with peak systolic strain rate -1.39 +/- 0.21/s, early diastolic strain rate 2.0 +/- 0.40/s and late diastolic strain rate 1.21 +/- 0.31/s. These values are significantly higher compared to the previous published values of normal age-adjusted individuals. In addition, no age-related decline of longitudinal contractility in well-trained athletes was observed. Conclusions There is increased overall longitudinal myocardial contractility at rest in experienced endurance athletes compared to the published normal values in the literature indicating a preserved and even supra-normal contractility in the athletes. There is no age dependent decline of the longitudinal 2D Strain values. This underlines the beneficial effects of regular physical exercise even in advanced age. PMID:24571726

Longitudinal Discriminant Analysis of Hemoglobin Level for Predicting Preeclampsia

PubMed Central

Nasiri, Malihe; Faghihzadeh, Soghrat; Alavi Majd, Hamid; Zayeri, Farid; Kariman, Noorosadat; Safavi Ardebili, Nastaran

2015-01-01

Background: Preeclampsia is one of the most serious complications during pregnancy with important effects on health of mother and fetus that causes maternal and fetal morbidity and mortality. This study was performed to evaluate whether high levels of hemoglobin may increase the risk of preeclampsia. Objectives: The present study aimed to predict preeclampsia by the hemoglobin profiles through longitudinal discriminant analysis and comparing the error rate of discrimination in longitudinal and cross sectional data. Patients and Methods: In a prospective cohort study from October 2010 to July 2011, 650 pregnant women referred to the prenatal clinic of Milad Hospital in Tehran were evaluated in 3 stages. The hemoglobin level of each woman was measured in the first, second, and third trimester of pregnancy by an expert technician. The subjects were followed up to delivery and preeclampsia was the main outcome under study. The covariance pattern and linear-mixed effects models are common methods that were applied for discriminant analysis of longitudinal data. Also Student t, Mann-Whitney U, and chi-square tests were used for comparing the demographic and clinical characteristics between two groups. Statistical analyses were performed using the SAS software version 9.1. Results: The prevalence rate of preeclampsia was 7.2% (47 women). The women with preeclampsia had a higher mean of hemoglobin values and the difference was 0.46 g/dL (P = 0.003). Also the mean of hemoglobin in the first trimester was higher than that of the second trimester, and was lower than that of the third trimester and the differences were significant (P = 0.015 and P < 0.001, respectively). The sensitivity for longitudinal data and cross-sectional data in three trimesters was 90%, 67%, 72%, and 54% and the specificity was 88%, 55%, 63%, and 50%, respectively. Conclusions: The levels of hemoglobin can be used to predict preeclampsia and monitoring the pregnant women and its regular measure in 3 trimesters help us to identify women at risk for preeclampsia. PMID:26019901

Brachial artery vasomotion and transducer pressure effect on measurements by active contour segmentation on ultrasound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cary, Theodore W.; Sultan, Laith R.; Sehgal, Chandra M., E-mail: sehgalc@uphs.upenn.edu

Purpose: To use feed-forward active contours (snakes) to track and measure brachial artery vasomotion on ultrasound images recorded in both transverse and longitudinal views; and to compare the algorithm's performance in each view. Methods: Longitudinal and transverse view ultrasound image sequences of 45 brachial arteries were segmented by feed-forward active contour (FFAC). The segmented regions were used to measure vasomotion artery diameter, cross-sectional area, and distention both as peak-to-peak diameter and as area. ECG waveforms were also simultaneously extracted frame-by-frame by thresholding a running finite-difference image between consecutive images. The arterial and ECG waveforms were compared as they traced eachmore » phase of the cardiac cycle. Results: FFAC successfully segmented arteries in longitudinal and transverse views in all 45 cases. The automated analysis took significantly less time than manual tracing, but produced superior, well-behaved arterial waveforms. Automated arterial measurements also had lower interobserver variability as measured by correlation, difference in mean values, and coefficient of variation. Although FFAC successfully segmented both the longitudinal and transverse images, transverse measurements were less variable. The cross-sectional area computed from the longitudinal images was 27% lower than the area measured from transverse images, possibly due to the compression of the artery along the image depth by transducer pressure. Conclusions: FFAC is a robust and sensitive vasomotion segmentation algorithm in both transverse and longitudinal views. Transverse imaging may offer advantages over longitudinal imaging: transverse measurements are more consistent, possibly because the method is less sensitive to variations in transducer pressure during imaging.« less

Brachial artery vasomotion and transducer pressure effect on measurements by active contour segmentation on ultrasound.

PubMed

Cary, Theodore W; Reamer, Courtney B; Sultan, Laith R; Mohler, Emile R; Sehgal, Chandra M

2014-02-01

To use feed-forward active contours (snakes) to track and measure brachial artery vasomotion on ultrasound images recorded in both transverse and longitudinal views; and to compare the algorithm's performance in each view. Longitudinal and transverse view ultrasound image sequences of 45 brachial arteries were segmented by feed-forward active contour (FFAC). The segmented regions were used to measure vasomotion artery diameter, cross-sectional area, and distention both as peak-to-peak diameter and as area. ECG waveforms were also simultaneously extracted frame-by-frame by thresholding a running finite-difference image between consecutive images. The arterial and ECG waveforms were compared as they traced each phase of the cardiac cycle. FFAC successfully segmented arteries in longitudinal and transverse views in all 45 cases. The automated analysis took significantly less time than manual tracing, but produced superior, well-behaved arterial waveforms. Automated arterial measurements also had lower interobserver variability as measured by correlation, difference in mean values, and coefficient of variation. Although FFAC successfully segmented both the longitudinal and transverse images, transverse measurements were less variable. The cross-sectional area computed from the longitudinal images was 27% lower than the area measured from transverse images, possibly due to the compression of the artery along the image depth by transducer pressure. FFAC is a robust and sensitive vasomotion segmentation algorithm in both transverse and longitudinal views. Transverse imaging may offer advantages over longitudinal imaging: transverse measurements are more consistent, possibly because the method is less sensitive to variations in transducer pressure during imaging.

Brachial artery vasomotion and transducer pressure effect on measurements by active contour segmentation on ultrasound

PubMed Central

Cary, Theodore W.; Reamer, Courtney B.; Sultan, Laith R.; Mohler, Emile R.; Sehgal, Chandra M.

2014-01-01

Purpose: To use feed-forward active contours (snakes) to track and measure brachial artery vasomotion on ultrasound images recorded in both transverse and longitudinal views; and to compare the algorithm's performance in each view. Methods: Longitudinal and transverse view ultrasound image sequences of 45 brachial arteries were segmented by feed-forward active contour (FFAC). The segmented regions were used to measure vasomotion artery diameter, cross-sectional area, and distention both as peak-to-peak diameter and as area. ECG waveforms were also simultaneously extracted frame-by-frame by thresholding a running finite-difference image between consecutive images. The arterial and ECG waveforms were compared as they traced each phase of the cardiac cycle. Results: FFAC successfully segmented arteries in longitudinal and transverse views in all 45 cases. The automated analysis took significantly less time than manual tracing, but produced superior, well-behaved arterial waveforms. Automated arterial measurements also had lower interobserver variability as measured by correlation, difference in mean values, and coefficient of variation. Although FFAC successfully segmented both the longitudinal and transverse images, transverse measurements were less variable. The cross-sectional area computed from the longitudinal images was 27% lower than the area measured from transverse images, possibly due to the compression of the artery along the image depth by transducer pressure. Conclusions: FFAC is a robust and sensitive vasomotion segmentation algorithm in both transverse and longitudinal views. Transverse imaging may offer advantages over longitudinal imaging: transverse measurements are more consistent, possibly because the method is less sensitive to variations in transducer pressure during imaging. PMID:24506648

Saturday Morning Children's Television Advertising: A Longitudinal Content Analysis.

ERIC Educational Resources Information Center

Byrd-Bredbenner, Carol

2002-01-01

Content of ads on Saturday children's television programs in 1993 (n=378) and 1999 (n=385) was compared with dietary recommendations and advertising guidelines. Cereals and foods high in sugar or fat dominated ads. Results were compared with earlier studies, finding that over 30 years, ads adhered to advertising guidelines but did not reflect…

Psychological Implications of Motherhood and Fatherhood in Midlife: Evidence from Sibling Models

ERIC Educational Resources Information Center

Pudrovska, Tetyana

2008-01-01

Using data from 4,744 full, twin, half-, adopted, and stepsiblings in the Wisconsin Longitudinal Study, I examine psychological consequences of motherhood and fatherhood in midlife. My analysis includes between-family models that compare individuals across families and within-family models comparing siblings from the same family to account for…

Longitudinal change in quantitative meniscus measurements in knee osteoarthritis--data from the Osteoarthritis Initiative.

PubMed

Bloecker, Katja; Wirth, W; Guermazi, A; Hitzl, W; Hunter, D J; Eckstein, F

2015-10-01

We aimed to apply 3D MRI-based measurement technology to studying 2-year change in quantitative measurements of meniscus size and position. Forty-seven knees from the Osteoarthritis Initiative with medial radiographic joint space narrowing had baseline and 2-year follow-up MRIs. Quantitative measures were obtained from manual segmentation of the menisci and tibia using coronal DESSwe images. The standardized response mean (SRM = mean/SD change) was used as measure of sensitivity to longitudinal change. Medial tibial plateau coverage decreased from 34.8% to 29.9% (SRM -0.82; p < 0.001). Change in medial meniscus extrusion in a central image (SRM 0.18) and in the central five slices (SRM 0.22) did not reach significance, but change in extrusion across the entire meniscus (SRM 0.32; p = 0.03) and in the relative area of meniscus extrusion (SRM 0.56; p < 0.001) did. There was a reduction in medial meniscus volume (10%; p < 0.001), width (7%; p < 0.001), and height (2%; p = 0.08); meniscus substance loss was strongest in the posterior (SRM -0.51; p = 0.001) and weakest in the anterior horn (SRM -0.15; p = 0.31). This pilot study reports, for the first time, longitudinal change in quantitative 3D meniscus measurements in knee osteoarthritis. It provides evidence of improved sensitivity to change of 3D measurements compared with single slice analysis. • First longitudinal MRI-based measurements of change of meniscus position and size. • Quantitative longitudinal evaluation of meniscus change in knee osteoarthritis. • Improved sensitivity to change of 3D measurements compared with single slice analysis.

A Contextual Analysis of Differential Association, Social Control, and Strain Theories of Delinquency.

ERIC Educational Resources Information Center

Hoffmann, John P.

2003-01-01

Using national longitudinal data on 10,860 adolescents, a comparative analysis of community contextual effects on delinquency examined variables derived from three theories. Youths in areas of high male joblessness who experienced stressful life events or little parental supervision were especially likely to be involved in delinquency. The…

Analysis of longitudinal "time series" data in toxicology.

PubMed

Cox, C; Cory-Slechta, D A

1987-02-01

Studies focusing on chronic toxicity or on the time course of toxicant effect often involve repeated measurements or longitudinal observations of endpoints of interest. Experimental design considerations frequently necessitate between-group comparisons of the resulting trends. Typically, procedures such as the repeated-measures analysis of variance have been used for statistical analysis, even though the required assumptions may not be satisfied in some circumstances. This paper describes an alternative analytical approach which summarizes curvilinear trends by fitting cubic orthogonal polynomials to individual profiles of effect. The resulting regression coefficients serve as quantitative descriptors which can be subjected to group significance testing. Randomization tests based on medians are proposed to provide a comparison of treatment and control groups. Examples from the behavioral toxicology literature are considered, and the results are compared to more traditional approaches, such as repeated-measures analysis of variance.

MRI allows for longitudinal quantitative analysis of body fat composition in rats: an analysis of sibutramine-associated changes at the group level.

PubMed

Müller, Hans-Peter; Niessen, Heiko G; Kaulisch, Thomas; Ludolph, Albert C; Kassubek, Jan; Stiller, Detlef

2013-09-01

Body fat distribution changes are associated with multiple alterations in metabolism. Therefore, the assessment of body fat compartments by MRI in animal models is a promising approach to obesity research. Standard T1-weighted (T1w) whole body MRI was used here to quantify different effects in the subcutaneous and visceral fat compartments in rats under treatment with an anorexiant. Twenty rats on a high caloric diet were investigated by the identical MRI protocol at baseline and after seven weeks. Ten rats received a treatment with sibutramine, 10 rats served as vehicle control group. To longitudinally assess body fat components, MRI analysis was used with two approaches: 2D slicewise graphic analysis (SGA) was compared with an automated 3D analysis algorithm (3DA). At the group level, fat volume differences showed a longitudinal increase of subcutaneous and visceral fat volumes for the control group, whereas the sibutramine group showed stable subcutaneous fat volumes and decrease in visceral fat volumes. SGA and 3DA volume determination showed significant correlations for subcutaneous fat volume (C=0.85, p<0.001), visceral fat volume (C=0.87, p<0.001), and total fat volume (C=0.90, p<0.001). It could be demonstrated that computer-based analysis of T1w MRI could be used to longitudinally assess changes in body fat compartments in rats at the group level. In detail, it was possible to investigate the effect of sibutramine separate on the fat compartments in rats. Copyright © 2013 Elsevier Inc. All rights reserved.

Subject-specific longitudinal shape analysis by coupling spatiotemporal shape modeling with medial analysis

NASA Astrophysics Data System (ADS)

Hong, Sungmin; Fishbaugh, James; Rezanejad, Morteza; Siddiqi, Kaleem; Johnson, Hans; Paulsen, Jane; Kim, Eun Young; Gerig, Guido

2017-02-01

Modeling subject-specific shape change is one of the most important challenges in longitudinal shape analysis of disease progression. Whereas anatomical change over time can be a function of normal aging, anatomy can also be impacted by disease related degeneration. Anatomical shape change may also be affected by structural changes from neighboring shapes, which may cause non-linear variations in pose. In this paper, we propose a framework to analyze disease related shape changes by coupling extrinsic modeling of the ambient anatomical space via spatiotemporal deformations with intrinsic shape properties from medial surface analysis. We compare intrinsic shape properties of a subject-specific shape trajectory to a normative 4D shape atlas representing normal aging to isolate shape changes related to disease. The spatiotemporal shape modeling establishes inter/intra subject anatomical correspondence, which in turn enables comparisons between subjects and the 4D shape atlas, and also quantitative analysis of disease related shape change. The medial surface analysis captures intrinsic shape properties related to local patterns of deformation. The proposed framework jointly models extrinsic longitudinal shape changes in the ambient anatomical space, as well as intrinsic shape properties to give localized measurements of degeneration. Six high risk subjects and six controls are randomly sampled from a Huntington's disease image database for qualitative and quantitative comparison.

Predicting two-year longitudinal MD Anderson Dysphagia Inventory outcomes after intensity modulated radiotherapy for locoregionally advanced oropharyngeal carcinoma.

PubMed

Goepfert, Ryan P; Lewin, Jan S; Barrow, Martha P; Fuller, C David; Lai, Stephen Y; Song, Juhee; Hobbs, Brian P; Gunn, G Brandon; Beadle, Beth M; Rosenthal, David I; Garden, Adam S; Kies, Merrill S; Papadimitrakopoulou, Vali A; Schwartz, David L; Hutcheson, Katherine A

2017-04-01

To determine the factors associated with longitudinal patient-reported dysphagia as measured by the MD Anderson Dysphagia Inventory (MDADI) in locoregionally advanced oropharyngeal carcinoma (OPC) survivors treated with split-field intensity modulated radiotherapy (IMRT). Retrospective patient analysis. A retrospective analysis combined data from three single-institution clinical trials for stage III/IV head and neck carcinoma. According to trial protocols, patients had prospectively collected MDADI at baseline, 6, 12, and 24 months after treatment. OPC patients with baseline and at least one post-treatment MDADI were included. Longitudinal analysis was completed with multivariate linear mixed effects modeling. There were 116 patients who met inclusion criteria. Mean baseline MDADI composite was 88.3, dropping to 73.8 at 6 months, and rising to 78.6 and 83.3 by 12 and 24 months, respectively (compared to baseline, all P < .0001). Tumor stage and smoking status were significant predictors of longitudinal MDADI composite scores. Patients with T1, T2, and T3 tumors had 15.9 (P = .0001), 10.9 (P = .0049), and 7.5 (P = .0615), respectively, higher mean MDADI composite than those with T4 tumors, and current smokers had a 9.4 (P = .0007) lower mean MDADI composite than never smokers. Patients report clinically meaningful dysphagia early after split-field IMRT for locoregionally advanced OPC that remains apparent 6 months after treatment. MDADI scores recover slowly thereafter, but remain depressed at 24 months compared to baseline. Higher tumor stage and smoking status are important markers of patient-reported function through the course of treatment, suggesting these are important groups for heightened surveillance and more intensive interventions to optimize swallowing outcomes. 4 Laryngoscope, 127:842-848, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Joint longitudinal data analysis in detecting determinants of CD4 cell count change and adherence to highly active antiretroviral therapy at Felege Hiwot Teaching and Specialized Hospital, North-west Ethiopia (Amhara Region).

PubMed

Seyoum, Awoke; Ndlovu, Principal; Temesgen, Zewotir

2017-03-16

Adherence and CD4 cell count change measure the progression of the disease in HIV patients after the commencement of HAART. Lack of information about associated factors on adherence to HAART and CD4 cell count reduction is a challenge for the improvement of cells in HIV positive adults. The main objective of adopting joint modeling was to compare separate and joint models of longitudinal repeated measures in identifying long-term predictors of the two longitudinal outcomes: CD4 cell count and adherence to HAART. A longitudinal retrospective cohort study was conducted to examine the joint predictors of CD4 cell count change and adherence to HAART among HIV adult patients enrolled in the first 10 months of the year 2008 and followed-up to June 2012. Joint model was employed to determine joint predictors of two longitudinal response variables over time. Furthermore, the generalized linear mixed effect model had been used for specification of the marginal distribution, conditional to correlated random effect. A total of 792 adult HIV patients were studied to analyze the longitudinal joint model study. The result from this investigation revealed that age, weight, baseline CD4 cell count, ownership of cell phone, visiting times, marital status, residence area and level of disclosure of the disease to family members had significantly affected both outcomes. From the two-way interactions, time * owner of cell phone, time * sex, age * sex, age * level of education as well as time * level of education were significant for CD4 cell count change in the longitudinal data analysis. The multivariate joint model with linear predictor indicates that CD4 cell count change was positively correlated (p ≤ 0.0001) with adherence to HAART. Hence, as adherence to HAART increased, CD4 cell count also increased; and those patients who had significant CD4 cell count change at each visiting time had been encouraged to be good adherents. Joint model analysis was more parsimonious as compared to separate analysis, as it reduces type I error and subject-specific analysis improved its model fit. The joint model operates multivariate analysis simultaneously; and it has great power in parameter estimation. Developing joint model helps validate the observed correlation between the outcomes that have emerged from the association of intercepts. There should be a special attention and intervention for HIV positive adults, especially for those who had poor adherence and with low CD4 cell count change. The intervention may be important for pre-treatment counseling and awareness creation. The study also identified a group of patients who were with maximum risk of CD4 cell count change. It is suggested that this group of patients needs high intervention for counseling.

Component mode synthesis and large deflection vibrations of complex structures. [beams and trusses

NASA Technical Reports Server (NTRS)

Mei, C.

1984-01-01

The accuracy of the NASTRAN modal synthesis analysis was assessed by comparing it with full structure NASTRAN and nine other modal synthesis results using a nine-bay truss. A NASTRAN component mode transient response analysis was also performed on the free-free truss structure. A finite element method was developed for nonlinear vibration of beam structures subjected to harmonic excitation. Longitudinal deformation and inertia are both included in the formula. Tables show the finite element free vibration results with and without considering the effects of longitudinal deformation and inertia as well as the frequency ratios for a simply supported and a clamped beam subjected to a uniform harmonic force.

Improvement or selection? A longitudinal analysis of students' views about experimental physics in their lab courses

NASA Astrophysics Data System (ADS)

Wilcox, Bethany R.; Lewandowski, H. J.

2017-12-01

Laboratory courses represent a unique and potentially important component of the undergraduate physics curriculum, which can be designed to allow students to authentically engage with the process of experimental physics. Among other possible benefits, participation in these courses throughout the undergraduate physics curriculum presents an opportunity to develop students' understanding of the nature and importance of experimental physics within the discipline as a whole. Here, we present and compare both a longitudinal and pseudolongitudinal analysis of students' responses to a research-based assessment targeting students' views about experimental physics—the Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS)—across multiple, required lab courses at a single institution. We find that, while pseudolongitudinal averages showed increases in students' E-CLASS scores in each consecutive course, analysis of longitudinal data indicates that this increase was not driven by a cumulative impact of laboratory instruction. Rather, the increase was driven by a selection effect in which students who persisted into higher-level lab courses already had more expertlike beliefs, attitudes, and expectations than their peers when they started the lower-level courses.

Propagation Constant of a Rectangular Waveguides Completely Full of Ferrite Magnetized Longitudinally

NASA Astrophysics Data System (ADS)

Sakli, Hedi; Benzina, Hafedh; Aguili, Taoufik; Tao, Jun Wu

2009-08-01

This paper is an analysis of rectangular waveguide completely full of ferrite magnetized longitudinally. The analysis is based on the formulation of the transverse operator method (TOM), followed by the application of the Galerkin method. We obtain an eigenvalue equation system. The propagation constant of some homogenous and anisotropic waveguide structures with ferrite has been obtained. The results presented here show that the transverse operator formulation is not only an elegant theoretical form, but also a powerful and efficient analysis method, it is useful to solve a number of the propagation problems in electromagnetic. One advantage of this method is that it presents a fast convergence. Numerical examples are given for different cases and compared with the published results. A good agreement is obtained.

A randomised crossover study to compare the cross-sectional and longitudinal approaches to ultrasound-guided peripheral venepuncture in a model.

PubMed

Griffiths, James; Carnegie, Amadeus; Kendall, Richard; Madan, Rajeev

2017-12-01

Ultrasound-guided peripheral intravenous access may present an alternative to central or intraosseous access in patients with difficult peripheral veins. Using venepuncture of a phantom model as a proxy, we investigated whether novice ultrasound users should adopt a cross-sectional or longitudinal approach when learning to access peripheral veins under ultrasound guidance. This result would inform the development of a structured training method for this procedure. We conducted a randomised controlled trial of 30 medical students. Subjects received 35 min of training, then attempted to aspirate 1 ml of synthetic blood from a deep vein in a training model under ultrasound guidance. Subjects attempted both the cross-sectional and longitudinal approaches. Group 1 used cross-sectional first, followed by longitudinal. Group 2 used longitudinal first, then cross-sectional. We measured the time from first puncture of the model's skin to aspiration of fluid, and the number of attempts required. Subjects also reported difficulty ratings for each approach. Paired sample t-tests were used for statistical analysis. The mean number of attempts was 1.13 using the cross-sectional approach, compared with 1.30 using the longitudinal approach (p = 0.17). Mean time to aspiration of fluid was 45.1 s using the cross-sectional approach and 52.8 s using the longitudinal approach (p = 0.43). The mean difficulty score out of 10 was 3.97 for the cross-sectional approach and 3.93 for the longitudinal approach (p = 0.95). We found no significant difference in effectiveness between the cross-sectional and longitudinal approaches to ultrasound-guided venepuncture when performed on a model. We believe that both approaches should be included when teaching ultrasound-guided peripheral vascular access. To confirm which approach would be best in clinical practice, we advocate future testing of both approaches on patients.

Regularities in travel demand : an international perspective

DOT National Transportation Integrated Search

2000-12-01

The major mobility variables from about 30 travel surveys in more than 10 countries are compared in this paper. The analysis of cross-sectional and longitudinal data broadly confirms some earlier findings of regularities in time and money expenditure...

White matter microstructural changes in adolescent anorexia nervosa including an exploratory longitudinal study.

PubMed

Vogel, Katja; Timmers, Inge; Kumar, Vinod; Nickl-Jockschat, Thomas; Bastiani, Matteo; Roebroek, Alard; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Goebel, Rainer; Seitz, Jochen

2016-01-01

Anorexia nervosa (AN) often begins in adolescence, however, the understanding of the underlying pathophysiology at this developmentally important age is scarce, impeding early interventions. We used diffusion tensor imaging (DTI) to investigate microstructural white matter (WM) brain changes including an experimental longitudinal follow-up. We acquired whole brain diffusion-weighted brain scans of 22 adolescent female hospitalized patients with AN at admission and nine patients longitudinally at discharge after weight rehabilitation. Patients (10-18 years) were compared to 21 typically developing controls (TD). Tract-based spatial statistics (TBSS) were applied to compare fractional anisotropy (FA) across groups and time points. Associations between average FA values of the global WM skeleton and weight as well as illness duration parameters were analyzed by multiple linear regression. We observed increased FA in bilateral frontal, parietal and temporal areas in AN patients at admission compared to TD. Higher FA of the global WM skeleton at admission was associated with faster weight loss prior to admission. Exploratory longitudinal analysis showed this FA increase to be partially normalized after weight rehabilitation. Our findings reveal a markedly different pattern of WM microstructural changes in adolescent AN compared to most previous results in adult AN. This could signify a different susceptibility and reaction to semi-starvation in the still developing brain of adolescents or a time-dependent pathomechanism differing with extend of chronicity. Higher FA at admission in adolescents with AN could point to WM fibers being packed together more closely.

A comparison of multiple imputation methods for incomplete longitudinal binary data.

PubMed

Yamaguchi, Yusuke; Misumi, Toshihiro; Maruo, Kazushi

2018-01-01

Longitudinal binary data are commonly encountered in clinical trials. Multiple imputation is an approach for getting a valid estimation of treatment effects under an assumption of missing at random mechanism. Although there are a variety of multiple imputation methods for the longitudinal binary data, a limited number of researches have reported on relative performances of the methods. Moreover, when focusing on the treatment effect throughout a period that has often been used in clinical evaluations of specific disease areas, no definite investigations comparing the methods have been available. We conducted an extensive simulation study to examine comparative performances of six multiple imputation methods available in the SAS MI procedure for longitudinal binary data, where two endpoints of responder rates at a specified time point and throughout a period were assessed. The simulation study suggested that results from naive approaches of a single imputation with non-responders and a complete case analysis could be very sensitive against missing data. The multiple imputation methods using a monotone method and a full conditional specification with a logistic regression imputation model were recommended for obtaining unbiased and robust estimations of the treatment effect. The methods were illustrated with data from a mental health research.

Analysis of radial and longitudinal field of plasma wakefield generated by a Laguerre-Gauss laser pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Firouzjaei, Ali Shekari; Shokri, Babak

In the present paper, we study the wakes known as the donut wake which is generated by Laguerre-Gauss (LG) laser pulses. Effects of the special spatial profile of a LG pulse on the radial and longitudinal wakefields are presented via an analytical model in a weakly non-linear regime in two dimensions. Different aspects of the donut-shaped wakefields have been analyzed and compared with Gaussian-driven wakes. There is also some discussion about the accelerating-focusing phase of the donut wake. Variations of longitudinal and radial wakes with laser amplitude, pulse length, and pulse spot size have been presented and discussed. Finally, wemore » present the optimum pulse duration for such wakes.« less

A Study of the Factors Associated with Risk for Development of Pressure Ulcers: A Longitudinal Analysis.

PubMed

Thomas, Elizebeth; Vinodkumar, Sudhaya; Mathew, Silvia; Setia, Maninder Singh

2015-01-01

Pressure ulcers (PUs) are prevalent in hospitalized patients; they may cause clinical, psychological, and economic problems in these patients. Previous studies are cross-sectional, have used pooled data, or cox-regression models to assess the risk for developing PU. However, PU risk scores change over time and models that account for time varying variables are useful for cohort analysis of data. The present longitudinal study was conducted to compare the risk of PU between surgical and nonsurgical patients, and to evaluate the factors associated with the development of these ulcers over a period of time. We evaluated 290 hospitalized patients over a 4 months period. The main outcomes for our analysis were: (1) Score on the pressure risk assessment scale; and (2) the proportion of individuals who were at severe risk for developing PUs. We used random effects models for longitudinal analysis of the data. The mean PU score was significantly higher in the nonsurgical patients compared with surgical patients at baseline (15.23 [3.86] vs. 9.33 [4.57]; P < 0.01). About 7% of the total patients had a score of >20 at baseline and were considered as being at high-risk for PU; the proportion was significantly higher among the nonsurgical patients compared with the surgical patients (14% vs. 4%, P = 0.003). In the adjusted models, there was no difference for severe risk for PU between surgical and nonsurgical patients (odds ratios [ORs]: 0.37, 95% confidence interval [CI]: 0.01-12.80). An additional day in the ward was associated with a significantly higher likelihood of being at high-risk for PU (OR: 1.47, 95% CI: 1.16-1.86). There were no significant differences between patients who were admitted for surgery compared with those who were not. An additional day in the ward, however, is important for developing a high-risk score for PU on the monitoring scale, and these patients require active interventions.

A Systematic Review and Meta-Analysis of The Effect of Low Vitamin D on Cognition.

PubMed

Goodwill, Alicia M; Szoeke, Cassandra

2017-10-01

With an aging population and no cure for dementia on the horizon, risk factor modification prior to disease onset is an urgent health priority. Therefore, this review examined the effect of low vitamin D status or vitamin D supplementation on cognition in midlife and older adults without a diagnosis of dementia. Systematic review and random effect meta-analysis. Observational (cross-sectional and longitudinal cohort) studies comparing low and high vitamin D status and interventions comparing vitamin D supplementation with a control group were included in the review and meta-analysis. Studies including adults and older adults without a dementia diagnosis were included. Medline (PubMed), AMED, Psych INFO, and Cochrane Central databases were searched for articles until August 2016. The Newcastle-Ottawa Scale and Physiotherapy Evidence Database assessed methodological quality of all studies. Twenty-six observational and three intervention studies (n = 19-9,556) were included in the meta-analysis. Low vitamin D was associated with worse cognitive performance (OR = 1.24, CI = 1.14-1.35) and cognitive decline (OR = 1.26, CI = 1.09-1.23); with cross-sectional yielding a stronger effect compared to longitudinal studies. Vitamin D supplementation showed no significant benefit on cognition compared with control (SMD = 0.21, CI = -0.05 to 0.46). Observational evidence demonstrates low vitamin D is related to poorer cognition; however, interventional studies are yet to show a clear benefit from vitamin D supplementation. From the evidence to date, there is likely a therapeutic age window relevant to the development of disease and therefore vitamin D therapy. Longitudinal lifespan studies are necessary to depict the optimal timing and duration in which repletion of vitamin D may protect against cognitive decline and dementia in aging, to better inform trials and practice towards a successful therapy. © 2017, Copyright the Authors Journal compilation © 2017, The American Geriatrics Society.

A Preliminary Bayesian Analysis of Incomplete Longitudinal Data from a Small Sample: Methodological Advances in an International Comparative Study of Educational Inequality

ERIC Educational Resources Information Center

Hsieh, Chueh-An; Maier, Kimberly S.

2009-01-01

The capacity of Bayesian methods in estimating complex statistical models is undeniable. Bayesian data analysis is seen as having a range of advantages, such as an intuitive probabilistic interpretation of the parameters of interest, the efficient incorporation of prior information to empirical data analysis, model averaging and model selection.…

Improved spatial regression analysis of diffusion tensor imaging for lesion detection during longitudinal progression of multiple sclerosis in individual subjects

NASA Astrophysics Data System (ADS)

Liu, Bilan; Qiu, Xing; Zhu, Tong; Tian, Wei; Hu, Rui; Ekholm, Sven; Schifitto, Giovanni; Zhong, Jianhui

2016-03-01

Subject-specific longitudinal DTI study is vital for investigation of pathological changes of lesions and disease evolution. Spatial Regression Analysis of Diffusion tensor imaging (SPREAD) is a non-parametric permutation-based statistical framework that combines spatial regression and resampling techniques to achieve effective detection of localized longitudinal diffusion changes within the whole brain at individual level without a priori hypotheses. However, boundary blurring and dislocation limit its sensitivity, especially towards detecting lesions of irregular shapes. In the present study, we propose an improved SPREAD (dubbed improved SPREAD, or iSPREAD) method by incorporating a three-dimensional (3D) nonlinear anisotropic diffusion filtering method, which provides edge-preserving image smoothing through a nonlinear scale space approach. The statistical inference based on iSPREAD was evaluated and compared with the original SPREAD method using both simulated and in vivo human brain data. Results demonstrated that the sensitivity and accuracy of the SPREAD method has been improved substantially by adapting nonlinear anisotropic filtering. iSPREAD identifies subject-specific longitudinal changes in the brain with improved sensitivity, accuracy, and enhanced statistical power, especially when the spatial correlation is heterogeneous among neighboring image pixels in DTI.

Biventricular myocardial strain analysis in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) using cardiovascular magnetic resonance feature tracking.

PubMed

Heermann, Philipp; Hedderich, Dennis M; Paul, Matthias; Schülke, Christoph; Kroeger, Jan Robert; Baeßler, Bettina; Wichter, Thomas; Maintz, David; Waltenberger, Johannes; Heindel, Walter; Bunck, Alexander C

2014-10-07

Fibrofatty degeneration of myocardium in ARVC is associated with wall motion abnormalities. The aim of this study was to examine whether Cardiovascular Magnetic Resonance (CMR) based strain analysis using feature tracking (FT) can serve as a quantifiable measure to confirm global and regional ventricular dysfunction in ARVC patients and support the early detection of ARVC. We enrolled 20 patients with ARVC, 30 with borderline ARVC and 22 subjects with a positive family history but no clinical signs of a manifest ARVC. 10 healthy volunteers (HV) served as controls. 15 ARVC patients received genotyping for Plakophilin-2 mutation (PKP-2), of which 7 were found to be positive. Cine MR datasets of all subjects were assessed for myocardial strain using FT (TomTec Diogenes Software). Global strain and strain rate in radial, circumferential and longitudinal mode were assessed for the right and left ventricle. In addition strain analysis at a segmental level was performed for the right ventricular free wall. RV global longitudinal strain rates in ARVC (-0.68 ± 0.36 sec⁻¹) and borderline ARVC (-0.85 ± 0.36 sec⁻¹) were significantly reduced in comparison with HV (-1.38 ± 0.52 sec⁻¹, p ≤ 0.05). Furthermore, in ARVC patients RV global circumferential strain and strain rates at the basal level were significantly reduced compared with HV (strain: -5.1 ± 2.7 vs. -9.2 ± 3.6%; strain rate: -0.31 ± 0.13 sec(-1) vs. -0.61 ± 0.21 sec⁻¹). Even for patients with ARVC or borderline ARVC and normal RV ejection fraction (n=30) global longitudinal strain rate proved to be significantly reduced compared with HV (-0.9 ± 0.3 vs. -1.4 ± 0.5 sec(-1); p < 0.005). In ARVC patients with PKP-2 mutation there was a clear trend towards a more pronounced impairment in RV global longitudinal strain rate. On ROC analysis RV global longitudinal strain rate and circumferential strain rate at the basal level proved to be the best discriminators between ARVC patients and HV (AUC: 0.9 and 0.92, respectively). CMR based strain analysis using FT is an objective and useful measure for quantification of wall motion abnormalities in ARVC. It allows differentiation between manifest or borderline ARVC and HV, even if ejection fraction is still normal.

Is hypercortisolism in anorexia nervosa detectable using hair samples?

PubMed

Ritschel, Franziska; Clas, Sabine; Geisler, Daniel; Haas, Verena; Seidel, Maria; Steding, Julius; Roessner, Veit; Kirschbaum, Clemens; Ehrlich, Stefan

2018-03-01

Anorexia nervosa (AN) is a severe mental disorder accompanied by extensive metabolic and endocrine abnormalities. It has been associated with hypercortisolism using short-term measurement methods such as 24 h-urine, saliva, and blood. The aim of this study was to examine whether the proposed hypercortisolism in acutely underweight AN (acAN) is also reflected in a long-term measure: hair cortisol (HCC). To gain further insight, we compared hair cortisol to a well-established classical cortisol measure (24 h-urine; UCC) longitudinally in acAN. Hair samples were collected and analyzed using a LC-MS/MS-based method to provide a monthly cortisol value. We compared HCC in samples of 40 acAN with 40 pairwise age-matched healthy controls (HC) as well as 23 long-term recovered AN participants (recAN) with 23 pairwise age-matched HC (cross-sectional design). In the second part, UCC collected weekly during 14 weeks of weight-restoration therapy in 16 acAN was compared with the (time-corresponding) HCC using linear mixed models and bivariate correlations (longitudinal design). No group differences in HCC occurred comparing acAN and recAN to HC (cross-sectional study). The longitudinal analysis revealed a decrease of UCC but not HCC with weight gain. Furthermore, there was no overall significant association between UCC and HCC. Only in the last four weeks of weight-restoration therapy we found a significant moderate correlation between UCC and HCC. HCC did not reflect the expected hypercortisolism in acAN and did not decrease during short-term weight-restoration. Time-corresponding measurements of UCC and HCC were not consistently associated in our longitudinal analysis of acAN undergoing inpatient treatment. Given the drastic metabolic disturbances in acutely underweight AN our findings could be interpreted as disturbed cortisol incorporation or altered activity of 11-β-HSD-enzymes in the hair follicle. Copyright © 2017. Published by Elsevier Ltd.

Competing regression models for longitudinal data.

PubMed

Alencar, Airlane P; Singer, Julio M; Rocha, Francisco Marcelo M

2012-03-01

The choice of an appropriate family of linear models for the analysis of longitudinal data is often a matter of concern for practitioners. To attenuate such difficulties, we discuss some issues that emerge when analyzing this type of data via a practical example involving pretest-posttest longitudinal data. In particular, we consider log-normal linear mixed models (LNLMM), generalized linear mixed models (GLMM), and models based on generalized estimating equations (GEE). We show how some special features of the data, like a nonconstant coefficient of variation, may be handled in the three approaches and evaluate their performance with respect to the magnitude of standard errors of interpretable and comparable parameters. We also show how different diagnostic tools may be employed to identify outliers and comment on available software. We conclude by noting that the results are similar, but that GEE-based models may be preferable when the goal is to compare the marginal expected responses. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clinical Evaluation of a Fully-automatic Segmentation Method for Longitudinal Brain Tumor Volumetry

NASA Astrophysics Data System (ADS)

Meier, Raphael; Knecht, Urspeter; Loosli, Tina; Bauer, Stefan; Slotboom, Johannes; Wiest, Roland; Reyes, Mauricio

2016-03-01

Information about the size of a tumor and its temporal evolution is needed for diagnosis as well as treatment of brain tumor patients. The aim of the study was to investigate the potential of a fully-automatic segmentation method, called BraTumIA, for longitudinal brain tumor volumetry by comparing the automatically estimated volumes with ground truth data acquired via manual segmentation. Longitudinal Magnetic Resonance (MR) Imaging data of 14 patients with newly diagnosed glioblastoma encompassing 64 MR acquisitions, ranging from preoperative up to 12 month follow-up images, was analysed. Manual segmentation was performed by two human raters. Strong correlations (R = 0.83-0.96, p < 0.001) were observed between volumetric estimates of BraTumIA and of each of the human raters for the contrast-enhancing (CET) and non-enhancing T2-hyperintense tumor compartments (NCE-T2). A quantitative analysis of the inter-rater disagreement showed that the disagreement between BraTumIA and each of the human raters was comparable to the disagreement between the human raters. In summary, BraTumIA generated volumetric trend curves of contrast-enhancing and non-enhancing T2-hyperintense tumor compartments comparable to estimates of human raters. These findings suggest the potential of automated longitudinal tumor segmentation to substitute manual volumetric follow-up of contrast-enhancing and non-enhancing T2-hyperintense tumor compartments.

Clinical Evaluation of a Fully-automatic Segmentation Method for Longitudinal Brain Tumor Volumetry.

PubMed

Meier, Raphael; Knecht, Urspeter; Loosli, Tina; Bauer, Stefan; Slotboom, Johannes; Wiest, Roland; Reyes, Mauricio

2016-03-22

Information about the size of a tumor and its temporal evolution is needed for diagnosis as well as treatment of brain tumor patients. The aim of the study was to investigate the potential of a fully-automatic segmentation method, called BraTumIA, for longitudinal brain tumor volumetry by comparing the automatically estimated volumes with ground truth data acquired via manual segmentation. Longitudinal Magnetic Resonance (MR) Imaging data of 14 patients with newly diagnosed glioblastoma encompassing 64 MR acquisitions, ranging from preoperative up to 12 month follow-up images, was analysed. Manual segmentation was performed by two human raters. Strong correlations (R = 0.83-0.96, p < 0.001) were observed between volumetric estimates of BraTumIA and of each of the human raters for the contrast-enhancing (CET) and non-enhancing T2-hyperintense tumor compartments (NCE-T2). A quantitative analysis of the inter-rater disagreement showed that the disagreement between BraTumIA and each of the human raters was comparable to the disagreement between the human raters. In summary, BraTumIA generated volumetric trend curves of contrast-enhancing and non-enhancing T2-hyperintense tumor compartments comparable to estimates of human raters. These findings suggest the potential of automated longitudinal tumor segmentation to substitute manual volumetric follow-up of contrast-enhancing and non-enhancing T2-hyperintense tumor compartments.

Clinical Evaluation of a Fully-automatic Segmentation Method for Longitudinal Brain Tumor Volumetry

PubMed Central

Meier, Raphael; Knecht, Urspeter; Loosli, Tina; Bauer, Stefan; Slotboom, Johannes; Wiest, Roland; Reyes, Mauricio

2016-01-01

Information about the size of a tumor and its temporal evolution is needed for diagnosis as well as treatment of brain tumor patients. The aim of the study was to investigate the potential of a fully-automatic segmentation method, called BraTumIA, for longitudinal brain tumor volumetry by comparing the automatically estimated volumes with ground truth data acquired via manual segmentation. Longitudinal Magnetic Resonance (MR) Imaging data of 14 patients with newly diagnosed glioblastoma encompassing 64 MR acquisitions, ranging from preoperative up to 12 month follow-up images, was analysed. Manual segmentation was performed by two human raters. Strong correlations (R = 0.83–0.96, p < 0.001) were observed between volumetric estimates of BraTumIA and of each of the human raters for the contrast-enhancing (CET) and non-enhancing T2-hyperintense tumor compartments (NCE-T2). A quantitative analysis of the inter-rater disagreement showed that the disagreement between BraTumIA and each of the human raters was comparable to the disagreement between the human raters. In summary, BraTumIA generated volumetric trend curves of contrast-enhancing and non-enhancing T2-hyperintense tumor compartments comparable to estimates of human raters. These findings suggest the potential of automated longitudinal tumor segmentation to substitute manual volumetric follow-up of contrast-enhancing and non-enhancing T2-hyperintense tumor compartments. PMID:27001047

Interviewer effects on non-response propensity in longitudinal surveys: a multilevel modelling approach

PubMed Central

Vassallo, Rebecca; Durrant, Gabriele B; Smith, Peter W F; Goldstein, Harvey

2015-01-01

The paper investigates two different multilevel approaches, the multilevel cross-classified and the multiple-membership models, for the analysis of interviewer effects on wave non-response in longitudinal surveys. The models proposed incorporate both interviewer and area effects to account for the non-hierarchical structure, the influence of potentially more than one interviewer across waves and possible confounding of area and interviewer effects arising from the non-random allocation of interviewers across areas. The methods are compared by using a data set: the UK Family and Children Survey. PMID:25598587

'TIME': A Web Application for Obtaining Insights into Microbial Ecology Using Longitudinal Microbiome Data.

PubMed

Baksi, Krishanu D; Kuntal, Bhusan K; Mande, Sharmila S

2018-01-01

Realization of the importance of microbiome studies, coupled with the decreasing sequencing cost, has led to the exponential growth of microbiome data. A number of these microbiome studies have focused on understanding changes in the microbial community over time. Such longitudinal microbiome studies have the potential to offer unique insights pertaining to the microbial social networks as well as their responses to perturbations. In this communication, we introduce a web based framework called 'TIME' (Temporal Insights into Microbial Ecology'), developed specifically to obtain meaningful insights from microbiome time series data. The TIME web-server is designed to accept a wide range of popular formats as input with options to preprocess and filter the data. Multiple samples, defined by a series of longitudinal time points along with their metadata information, can be compared in order to interactively visualize the temporal variations. In addition to standard microbiome data analytics, the web server implements popular time series analysis methods like Dynamic time warping, Granger causality and Dickey Fuller test to generate interactive layouts for facilitating easy biological inferences. Apart from this, a new metric for comparing metagenomic time series data has been introduced to effectively visualize the similarities/differences in the trends of the resident microbial groups. Augmenting the visualizations with the stationarity information pertaining to the microbial groups is utilized to predict the microbial competition as well as community structure. Additionally, the 'causality graph analysis' module incorporated in TIME allows predicting taxa that might have a higher influence on community structure in different conditions. TIME also allows users to easily identify potential taxonomic markers from a longitudinal microbiome analysis. We illustrate the utility of the web-server features on a few published time series microbiome data and demonstrate the ease with which it can be used to perform complex analysis.

Longitudinal and Cross-Sectional Analyses of Visual Field Progression in Participants of the Ocular Hypertension Treatment Study (OHTS)

PubMed Central

Chauhan, Balwantray C; Keltner, John L; Cello, Kim E; Johnson, Chris A; Anderson, Douglas R; Gordon, Mae O; Kass, Michael A

2014-01-01

Purpose Visual field progression can be determined by evaluating the visual field by serial examinations (longitudinal analysis), or by a change in classification derived from comparison to age-matched normal data in single examinations (cross-sectional analysis). We determined the agreement between these two approaches in data from the Ocular Hypertension Treatment Study (OHTS). Methods Visual field data from 3088 eyes of 1570 OHTS participants (median follow-up 7 yrs, 15 tests with static automated perimetry) were analysed. Longitudinal analyses were performed with change probability with total and pattern deviation, and cross-sectional analysis with Glaucoma Hemifield Test, Corrected Pattern Standard Deviation, and Mean Deviation. The rates of Mean Deviation and General Height change were compared to estimate the degree of diffuse loss in emerging glaucoma. Results The agreement on progression in longitudinal and cross-sectional analyses ranged from 50% to 61% and remained nearly constant across a wide range of criteria. In contrast, the agreement on absence of progression ranged from 97% to 99.7%, being highest for the stricter criteria. Analyses of pattern deviation were more conservative than total deviation, with a 3 to 5 times lesser incidence of progression. Most participants developing field loss had both diffuse and focal change. Conclusions Despite considerable overall agreement, between 40 to 50% of eyes identified as having progressed with either longitudinal or cross-sectional analyses were identified with only one of the analyses. Because diffuse change is part of early glaucomatous damage, pattern deviation analyses may underestimate progression in patients with ocular hypertension. PMID:21149774

Hypothesis testing in functional linear regression models with Neyman's truncation and wavelet thresholding for longitudinal data.

PubMed

Yang, Xiaowei; Nie, Kun

2008-03-15

Longitudinal data sets in biomedical research often consist of large numbers of repeated measures. In many cases, the trajectories do not look globally linear or polynomial, making it difficult to summarize the data or test hypotheses using standard longitudinal data analysis based on various linear models. An alternative approach is to apply the approaches of functional data analysis, which directly target the continuous nonlinear curves underlying discretely sampled repeated measures. For the purposes of data exploration, many functional data analysis strategies have been developed based on various schemes of smoothing, but fewer options are available for making causal inferences regarding predictor-outcome relationships, a common task seen in hypothesis-driven medical studies. To compare groups of curves, two testing strategies with good power have been proposed for high-dimensional analysis of variance: the Fourier-based adaptive Neyman test and the wavelet-based thresholding test. Using a smoking cessation clinical trial data set, this paper demonstrates how to extend the strategies for hypothesis testing into the framework of functional linear regression models (FLRMs) with continuous functional responses and categorical or continuous scalar predictors. The analysis procedure consists of three steps: first, apply the Fourier or wavelet transform to the original repeated measures; then fit a multivariate linear model in the transformed domain; and finally, test the regression coefficients using either adaptive Neyman or thresholding statistics. Since a FLRM can be viewed as a natural extension of the traditional multiple linear regression model, the development of this model and computational tools should enhance the capacity of medical statistics for longitudinal data.

Drug awareness in adolescents attending a mental health service: analysis of longitudinal data.

PubMed

Arnau, Jaume; Bono, Roser; Díaz, Rosa; Goti, Javier

2011-11-01

One of the procedures used most recently with longitudinal data is linear mixed models. In the context of health research the increasing number of studies that now use these models bears witness to the growing interest in this type of analysis. This paper describes the application of linear mixed models to a longitudinal study of a sample of Spanish adolescents attending a mental health service, the aim being to investigate their knowledge about the consumption of alcohol and other drugs. More specifically, the main objective was to compare the efficacy of a motivational interviewing programme with a standard approach to drug awareness. The models used to analyse the overall indicator of drug awareness were as follows: (a) unconditional linear growth curve model; (b) growth model with subject-associated variables; and (c) individual curve model with predictive variables. The results showed that awareness increased over time and that the variable 'schooling years' explained part of the between-subjects variation. The effect of motivational interviewing was also significant.

Residual Strength Pressure Tests and Nonlinear Analyses of Stringer- and Frame-Stiffened Aluminum Fuselage Panels with Longitudinal Cracks

NASA Technical Reports Server (NTRS)

Young, Richard D.; Rouse, Marshall; Ambur, Damodar R.; Starnes, James H., Jr.

1999-01-01

The results of residual strength pressure tests and nonlinear analyses of stringer- and frame-stiffened aluminum fuselage panels with longitudinal cracks are presented. Two types of damage are considered: a longitudinal crack located midway between stringers, and a longitudinal crack adjacent to a stringer and along a row of fasteners in a lap joint that has multiple-site damage (MSD). In both cases, the longitudinal crack is centered on a severed frame. The panels are subjected to internal pressure plus axial tension loads. The axial tension loads are equivalent to a bulkhead pressure load. Nonlinear elastic-plastic residual strength analyses of the fuselage panels are conducted using a finite element program and the crack-tip-opening-angle (CTOA) fracture criterion. Predicted crack growth and residual strength results from nonlinear analyses of the stiffened fuselage panels are compared with experimental measurements and observations. Both the test and analysis results indicate that the presence of MSD affects crack growth stability and reduces the residual strength of stiffened fuselage shells with long cracks.

Residual Strength Pressure Tests and Nonlinear Analyses of Stringer-and Frame-Stiffened Aluminum Fuselage Panels with Longitudinal Cracks

NASA Technical Reports Server (NTRS)

Young, Richard D.; Rouse, Marshall; Ambur, Damodar R.; Starnes, James H., Jr.

1998-01-01

The results of residual strength pressure tests and nonlinear analyses of stringer- and frame-stiffened aluminum fuselage panels with longitudinal cracks are presented. Two types of damage are considered: a longitudinal crack located midway between stringers, and a longitudinal crack adjacent to a stringer and along a row of fasteners in a lap joint that has multiple-site damage (MSD). In both cases, the longitudinal crack is centered on a severed frame. The panels are subjected to internal pressure plus axial tension loads. The axial tension loads are equivalent to a bulkhead pressure load. Nonlinear elastic-plastic residual strength analyses of the fuselage panels are conducted using a finite element program and the crack-tip-opening-angle (CTOA) fracture criterion. Predicted crack growth and residual strength results from nonlinear analyses of the stiffened fuselage panels are compared with experimental measurements and observations. Both the test and analysis results indicate that the presence of MSD affects crack growth stability and reduces the residual strength of stiffened fuselage shells with long cracks.

Assessing the comparative efficiency of urban mass transit systems in Ohio : longitudinal analysis.

DOT National Transportation Integrated Search

2013-12-01

A mass transit system not only improves passenger mobility, it also affects the level of economic activities (e.g., working and shopping). Thus, changes wrought by mass transit service planning can heavily influence regional economic growth. This pla...

Longitudinal study of fingerprint recognition.

PubMed

Yoon, Soweon; Jain, Anil K

2015-07-14

Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject's age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis.

Longitudinal study of fingerprint recognition

PubMed Central

Yoon, Soweon; Jain, Anil K.

2015-01-01

Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject’s age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis. PMID:26124106

A Longitudinal Analysis of Risk Factors for Child Maltreatment: Findings of a 17-Year Prospective Study of Officially Recorded and Self-Reported Child Abuse and Neglect.

ERIC Educational Resources Information Center

Brown, Jocelyn; Cohen, Patricia; Johnson, Jeffrey G.; Salzinger, Suzanne

1998-01-01

Repeated surveys assessing demographic variables, family relationships, parental behavior, and parent/child characteristics were administered to 664 families and compared with child abuse and neglect data from state records and retrospective self-reports. Analysis found maternal youth and sociopathy predicted general child maltreatment, but…

White matter microstructural changes in adolescent anorexia nervosa including an exploratory longitudinal study

PubMed Central

Vogel, Katja; Timmers, Inge; Kumar, Vinod; Nickl-Jockschat, Thomas; Bastiani, Matteo; Roebroek, Alard; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Goebel, Rainer; Seitz, Jochen

2016-01-01

Background Anorexia nervosa (AN) often begins in adolescence, however, the understanding of the underlying pathophysiology at this developmentally important age is scarce, impeding early interventions. We used diffusion tensor imaging (DTI) to investigate microstructural white matter (WM) brain changes including an experimental longitudinal follow-up. Methods We acquired whole brain diffusion-weighted brain scans of 22 adolescent female hospitalized patients with AN at admission and nine patients longitudinally at discharge after weight rehabilitation. Patients (10–18 years) were compared to 21 typically developing controls (TD). Tract-based spatial statistics (TBSS) were applied to compare fractional anisotropy (FA) across groups and time points. Associations between average FA values of the global WM skeleton and weight as well as illness duration parameters were analyzed by multiple linear regression. Results We observed increased FA in bilateral frontal, parietal and temporal areas in AN patients at admission compared to TD. Higher FA of the global WM skeleton at admission was associated with faster weight loss prior to admission. Exploratory longitudinal analysis showed this FA increase to be partially normalized after weight rehabilitation. Conclusions Our findings reveal a markedly different pattern of WM microstructural changes in adolescent AN compared to most previous results in adult AN. This could signify a different susceptibility and reaction to semi-starvation in the still developing brain of adolescents or a time-dependent pathomechanism differing with extend of chronicity. Higher FA at admission in adolescents with AN could point to WM fibers being packed together more closely. PMID:27182488

Interrupted Time Series Versus Statistical Process Control in Quality Improvement Projects.

PubMed

Andersson Hagiwara, Magnus; Andersson Gäre, Boel; Elg, Mattias

2016-01-01

To measure the effect of quality improvement interventions, it is appropriate to use analysis methods that measure data over time. Examples of such methods include statistical process control analysis and interrupted time series with segmented regression analysis. This article compares the use of statistical process control analysis and interrupted time series with segmented regression analysis for evaluating the longitudinal effects of quality improvement interventions, using an example study on an evaluation of a computerized decision support system.

Influence of Social Engagement on Mortality in Korea: Analysis of the Korean Longitudinal Study of Aging (2006-2012).

PubMed

Kim, Jae-Hyun; Lee, Sang Gyu; Kim, Tae-Hyun; Choi, Young; Lee, Yunhwan; Park, Eun-Cheol

2016-07-01

The objective of this study was to investigate the impact of social engagement and patterns of change in social engagement over time on mortality in a large population, aged 45 years or older. Data from the Korean Longitudinal Study of Aging from 2006 and 2012 were assessed using longitudinal data analysis. We included 8,234 research subjects at baseline (2006). The primary analysis was based on Cox proportional hazards models to examine our hypothesis. The hazard ratio of all-cause mortality for the lowest level of social engagement was 1.841-times higher (P < 0.001) compared with the highest level of social engagement. Subgroup analysis results by gender showed a similar trend. A six-class linear solution fit the data best, and class 1 (the lowest level of social engagement class, 7.6% of the sample) was significantly related to the highest mortality (HR: 4.780, P < 0.001). Our results provide scientific insight on the effects of the specificity of the level of social engagement and changes in social engagement on all-cause mortality in current practice, which are important for all-cause mortality risk. Therefore, protection from all-cause mortality may depend on avoidance of constant low-levels of social engagement.

Advanced analytical methodologies for measuring healthy ageing and its determinants, using factor analysis and machine learning techniques: the ATHLOS project

PubMed Central

Félix Caballero, Francisco; Soulis, George; Engchuan, Worrawat; Sánchez-Niubó, Albert; Arndt, Holger; Ayuso-Mateos, José Luis; Haro, Josep Maria; Chatterji, Somnath; Panagiotakos, Demosthenes B.

2017-01-01

A most challenging task for scientists that are involved in the study of ageing is the development of a measure to quantify health status across populations and over time. In the present study, a Bayesian multilevel Item Response Theory approach is used to create a health score that can be compared across different waves in a longitudinal study, using anchor items and items that vary across waves. The same approach can be applied to compare health scores across different longitudinal studies, using items that vary across studies. Data from the English Longitudinal Study of Ageing (ELSA) are employed. Mixed-effects multilevel regression and Machine Learning methods were used to identify relationships between socio-demographics and the health score created. The metric of health was created for 17,886 subjects (54.6% of women) participating in at least one of the first six ELSA waves and correlated well with already known conditions that affect health. Future efforts will implement this approach in a harmonised data set comprising several longitudinal studies of ageing. This will enable valid comparisons between clinical and community dwelling populations and help to generate norms that could be useful in day-to-day clinical practice. PMID:28281663

Advanced analytical methodologies for measuring healthy ageing and its determinants, using factor analysis and machine learning techniques: the ATHLOS project.

PubMed

Caballero, Francisco Félix; Soulis, George; Engchuan, Worrawat; Sánchez-Niubó, Albert; Arndt, Holger; Ayuso-Mateos, José Luis; Haro, Josep Maria; Chatterji, Somnath; Panagiotakos, Demosthenes B

2017-03-10

A most challenging task for scientists that are involved in the study of ageing is the development of a measure to quantify health status across populations and over time. In the present study, a Bayesian multilevel Item Response Theory approach is used to create a health score that can be compared across different waves in a longitudinal study, using anchor items and items that vary across waves. The same approach can be applied to compare health scores across different longitudinal studies, using items that vary across studies. Data from the English Longitudinal Study of Ageing (ELSA) are employed. Mixed-effects multilevel regression and Machine Learning methods were used to identify relationships between socio-demographics and the health score created. The metric of health was created for 17,886 subjects (54.6% of women) participating in at least one of the first six ELSA waves and correlated well with already known conditions that affect health. Future efforts will implement this approach in a harmonised data set comprising several longitudinal studies of ageing. This will enable valid comparisons between clinical and community dwelling populations and help to generate norms that could be useful in day-to-day clinical practice.

Gene expression models for prediction of longitudinal dispersion coefficient in streams

NASA Astrophysics Data System (ADS)

Sattar, Ahmed M. A.; Gharabaghi, Bahram

2015-05-01

Longitudinal dispersion is the key hydrologic process that governs transport of pollutants in natural streams. It is critical for spill action centers to be able to predict the pollutant travel time and break-through curves accurately following accidental spills in urban streams. This study presents a novel gene expression model for longitudinal dispersion developed using 150 published data sets of geometric and hydraulic parameters in natural streams in the United States, Canada, Europe, and New Zealand. The training and testing of the model were accomplished using randomly-selected 67% (100 data sets) and 33% (50 data sets) of the data sets, respectively. Gene expression programming (GEP) is used to develop empirical relations between the longitudinal dispersion coefficient and various control variables, including the Froude number which reflects the effect of reach slope, aspect ratio, and the bed material roughness on the dispersion coefficient. Two GEP models have been developed, and the prediction uncertainties of the developed GEP models are quantified and compared with those of existing models, showing improved prediction accuracy in favor of GEP models. Finally, a parametric analysis is performed for further verification of the developed GEP models. The main reason for the higher accuracy of the GEP models compared to the existing regression models is that exponents of the key variables (aspect ratio and bed material roughness) are not constants but a function of the Froude number. The proposed relations are both simple and accurate and can be effectively used to predict the longitudinal dispersion coefficients in natural streams.

Longitudinal in vivo muscle function analysis of the DMSXL mouse model of myotonic dystrophy type 1.

PubMed

Decostre, Valérie; Vignaud, Alban; Matot, Béatrice; Huguet, Aline; Ledoux, Isabelle; Bertil, Emilie; Gjata, Bernard; Carlier, Pierre G; Gourdon, Geneviève; Hogrel, Jean-Yves

2013-12-01

Myotonic dystrophy is the most common adult muscle dystrophy. In view of emerging therapies, which use animal models as a proof of principle, the development of reliable outcome measures for in vivo longitudinal study of mouse skeletal muscle function is becoming crucial. To satisfy this need, we have developed a device to measure ankle dorsi- and plantarflexion torque in rodents. We present an in vivo 8-month longitudinal study of the contractile properties of the skeletal muscles of the DMSXL mouse model of myotonic dystrophy type 1. Between 4 and 12 months of age, we observed a reduction in muscle strength in the ankle dorsi- and plantarflexors of DMSXL compared to control mice although the strength per muscle cross-section was normal. Mild steady myotonia but no abnormal muscle fatigue was also observed in the DMSXL mice. Magnetic resonance imaging and histological analysis performed at the end of the study showed respectively reduced muscle cross-section area and smaller muscle fibre diameter in DMSXL mice. In conclusion, our study demonstrates the feasibility of carrying out longitudinal in vivo studies of muscle function over several months in a mouse model of myotonic dystrophy confirming the feasibility of this method to test preclinical therapeutics. Copyright © 2013 Elsevier B.V. All rights reserved.

A longitudinal investigation of nutrition and dietary patterns in children of mothers with eating disorders.

PubMed

Easter, Abigail; Naumann, Ulrike; Northstone, Kate; Schmidt, Ulrike; Treasure, Janet; Micali, Nadia

2013-07-01

To investigate dietary patterns and nutritional intake in children of mothers with eating disorders. Mothers (N = 9423) from a longitudinal general population birth cohort study, the Avon Longitudinal Study of Parents and Children, completed Food Frequency Questionnaires on their children at 3, 4, 7, and 9 years of age. Macronutrient intake was estimated, and dietary patterns were obtained using principal components analysis. Linear regression and mixed-effects models were used to assess dietary patterns and nutritional intake among children of women with lifetime anorexia nervosa (AN, n = 140), bulimia nervosa (BN, n = 170), or AN+BN (n = 71), compared with children of women without eating disorders (unexposed women, n = 9037). Children in the maternal AN and BN groups had higher scores on the "health conscious/vegetarian" dietary pattern compared with unexposed children. Less adherence to the "traditional" dietary pattern was observed in children of exposed mothers, with more pronounced differences in early childhood. Children of women with AN and BN had higher intake of energy and children of women with BN had higher intake of carbohydrates and starch and lower intake of fat, compared with children in the unexposed group. Maternal eating disorders are associated with altered offspring dietary patterns and macronutrient intake. Longitudinal changes in patterns of diet in children of women with eating disorders may increase the risk of weight gain or disordered eating later in life. Copyright © 2013 Mosby, Inc. All rights reserved.

Predicting longitudinal trajectories of health probabilities with random-effects multinomial logit regression.

PubMed

Liu, Xian; Engel, Charles C

2012-12-20

Researchers often encounter longitudinal health data characterized with three or more ordinal or nominal categories. Random-effects multinomial logit models are generally applied to account for potential lack of independence inherent in such clustered data. When parameter estimates are used to describe longitudinal processes, however, random effects, both between and within individuals, need to be retransformed for correctly predicting outcome probabilities. This study attempts to go beyond existing work by developing a retransformation method that derives longitudinal growth trajectories of unbiased health probabilities. We estimated variances of the predicted probabilities by using the delta method. Additionally, we transformed the covariates' regression coefficients on the multinomial logit function, not substantively meaningful, to the conditional effects on the predicted probabilities. The empirical illustration uses the longitudinal data from the Asset and Health Dynamics among the Oldest Old. Our analysis compared three sets of the predicted probabilities of three health states at six time points, obtained from, respectively, the retransformation method, the best linear unbiased prediction, and the fixed-effects approach. The results demonstrate that neglect of retransforming random errors in the random-effects multinomial logit model results in severely biased longitudinal trajectories of health probabilities as well as overestimated effects of covariates on the probabilities. Copyright © 2012 John Wiley & Sons, Ltd.

Equatorial Plasma Bubbles: Effect of Thermospheric Winds Modulated by DE3 Tidal Waves

NASA Astrophysics Data System (ADS)

Sidorova, L. N.; Filippov, S. V.

2018-03-01

A hypothesis about the effect of the tropospheric source on the longitudinal distributions of the equatorial plasma bubbles observed in the topside ionosphere was proposed earlier. It was supposed that this influence is transferred mainly by the thermospheric winds modulated by the DE3 tropospheric tidal waves. This conclusion was based on the discovered high degree correlation ( R ≅ 0.79) between the variations of the longitudinal distribution of the plasma bubbles and the neutral atmospheric density. In this work, the hypothesis of the effect of the thermospheric tidal waves on the plasma bubbles at the stage of their generation is subjected to further verification. With this purpose, the longitudinal distributions of the frequency of the plasma bubble observations at the different ionospheric altitudes ( 600 km, ROCSAT-1; 1100 km, ISS-b) are analyzed; their principal similarity is revealed. Comparative analysis of these distributions with the longitudinal profile of the deviations of the zonal thermospheric wind ( 400 km, CHAMP) modulated by the DE3 tidal wave is carried out; their considerable correlation ( R ≅ 0.69) is revealed. We conclude that the longitudinal variations of the zonal wind associated with DE3 tidal waves can effect the longitudinal variations in the appearance frequency of the initial "seeding" perturbations, which further evolve into the plasma bubbles.

Socio-demographic and lifestyle factors for child’s physical growth and adiposity rebound of Japanese children: a longitudinal study of the 21st century longitudinal survey in newborns

PubMed Central

2014-01-01

Background It is unknown whether childhood physical development in Asian populations differs from western populations, since no longitudinal analysis has been performed in Asian countries yet. Utilizing the 21st Century Longitudinal Survey in Newborns, we studied the timing of adiposity rebound (AR) among Japanese children and determined whether AR occurs earlier in obese children compared to nonobese children. Furthermore, we identified important demographic, social, and lifestyle factors that affect their physical development. Methods We used data from the annual surveillance of Japanese children born in 2001, with 45,392 eligible subjects. We applied survival analysis to evaluate the AR and a trajectory method for the BMI transition across 5 ½ years. Time-dependent and time-independent factors affecting BMI changes were investigated using longitudinal analysis. Accounting for the known difference in prevalence between Japanese and Western children, we adopted a 95th percentile of BMI as criterion for obesity. Results Mean BMI at birth and at ages 1 ½, 2 ½, 3 ½, 4 ½, and 5 ½ years for all subjects were 12.6, 16.3, 16.1, 15.8, 15.5, and 15.4, respectively, showing a progressive reduction after 1 ½ years. However, among obese children at 5 ½ years, 39.6% had experienced AR as early as at age 4 ½ years. Controlling for sex, Cox’s proportional hazards model showed that obese children had a 48.5% higher hazard to experience AR than nonobese children. The difference in BMI transition between obese and non-obese children was also captured by a trajectory method. In longitudinal analysis, BMI was lower for children who had a longer gestational period whereas children who received parental care from non-family members gained higher BMI values. Conclusions With the 95th percentile cutoff for children obesity, obese Japanese children developed AR earlier than nonobese Japanese children, similar to those in Western countries reported in the literature. Primary caretakers and length of gestational period were the most important socio-demographic factors affecting physical development. PMID:24716901

Effectiveness of Student Admission Essays in Identifying Attrition.

ERIC Educational Resources Information Center

Sadler, Judith

2003-01-01

From a longitudinal sample of nursing students, 193 completers and 43 noncompleters were compared, revealing significant differences in the groups' mean scores on admission essays but not admission grade point averages. Content analysis revealed how completers had internalized the role of nurse. (Contains 12 references.) (SK)

Exposure enriched outcome dependent designs for longitudinal studies of gene-environment interaction.

PubMed

Sun, Zhichao; Mukherjee, Bhramar; Estes, Jason P; Vokonas, Pantel S; Park, Sung Kyun

2017-08-15

Joint effects of genetic and environmental factors have been increasingly recognized in the development of many complex human diseases. Despite the popularity of case-control and case-only designs, longitudinal cohort studies that can capture time-varying outcome and exposure information have long been recommended for gene-environment (G × E) interactions. To date, literature on sampling designs for longitudinal studies of G × E interaction is quite limited. We therefore consider designs that can prioritize a subsample of the existing cohort for retrospective genotyping on the basis of currently available outcome, exposure, and covariate data. In this work, we propose stratified sampling based on summaries of individual exposures and outcome trajectories and develop a full conditional likelihood approach for estimation that adjusts for the biased sample. We compare the performance of our proposed design and analysis with combinations of different sampling designs and estimation approaches via simulation. We observe that the full conditional likelihood provides improved estimates for the G × E interaction and joint exposure effects over uncorrected complete-case analysis, and the exposure enriched outcome trajectory dependent design outperforms other designs in terms of estimation efficiency and power for detection of the G × E interaction. We also illustrate our design and analysis using data from the Normative Aging Study, an ongoing longitudinal cohort study initiated by the Veterans Administration in 1963. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Prevention of Substance Use among Adolescents through Social and Emotional Training in School: A Latent-Class Analysis of a Five-Year Intervention in Sweden

ERIC Educational Resources Information Center

Kimber, Birgitta; Sandell, Rolf

2009-01-01

The study considers the impact of a program for social and emotional learning in Swedish schools on use of drugs, volatile substances, alcohol and tobacco. The program was evaluated in an effectiveness study. Intervention students were compared longitudinally with non-intervention students using nonparametric latent class analysis to identify…

Longitudinal Double Spin Asymmetries of π0 - Jet Correlations in Polarized Proton Collisions at s = 510 GeV at STAR

NASA Astrophysics Data System (ADS)

Wang, Yaping

One of the primary goals of the spin physics program at STAR is to constrain the polarized gluon distribution function, Δg(x), by measuring the longitudinal double-spin asymmetry (ALL) of various final-state channels. Using a jet in the mid-rapidity region |η| < 0.9 correlated with an azimuthally back-to-back π0 in the forward rapidity region 0.8 < η < 2.0 provides a new possibility to access the Δg(x) distribution at Bjorken-x down to 0.01. Compared to inclusive jet or inclusive π0 measurements, this channel also allows to constrain the initial parton kinematics. In these proceedings, we will present the status of the analysis of the π0-jet ALL in longitudinally polarized proton+proton collisions at s =510 GeV with 80 pb‑1 of data taken during the 2012 RHIC run. We also compare the projected ALL uncertainties to theoretical predictions of the ALL by next-to-leading order (NLO) model calculations with different polarized parton distribution functions.

Integrating longitudinal information in hippocampal volume measurements for the early detection of Alzheimer's disease.

PubMed

Chincarini, Andrea; Sensi, Francesco; Rei, Luca; Gemme, Gianluca; Squarcia, Sandro; Longo, Renata; Brun, Francesco; Tangaro, Sabina; Bellotti, Roberto; Amoroso, Nicola; Bocchetta, Martina; Redolfi, Alberto; Bosco, Paolo; Boccardi, Marina; Frisoni, Giovanni B; Nobili, Flavio

2016-01-15

Structural MRI measures for monitoring Alzheimer's Disease (AD) progression are becoming instrumental in the clinical practice, and more so in the context of longitudinal studies. This investigation addresses the impact of four image analysis approaches on the longitudinal performance of the hippocampal volume. We present a hippocampal segmentation algorithm and validate it on a gold-standard manual tracing database. We segmented 460 subjects from ADNI, each subject having been scanned twice at baseline, 12-month and 24month follow-up scan (1.5T, T1 MRI). We used the bilateral hippocampal volume v and its variation, measured as the annualized volume change Λ=δv/year(mm(3)/y). Four processing approaches with different complexity are compared to maximize the longitudinal information, and they are tested for cohort discrimination ability. Reference cohorts are Controls vs. Alzheimer's Disease (CTRL/AD) and CTRL vs. Mild Cognitive Impairment who subsequently progressed to AD dementia (CTRL/MCI-co). We discuss the conditions on v and the added value of Λ in discriminating subjects. The age-corrected bilateral annualized atrophy rate (%/year) were: -1.6 (0.6) for CTRL, -2.2 (1.0) for MCI-nc, -3.2 (1.2) for MCI-co and -4.0 (1.5) for AD. Combined (v, Λ) discrimination ability gave an Area under the ROC curve (auc)=0.93 for CTRL vs AD and auc=0.88 for CTRL vs MCI-co. Longitudinal volume measurements can provide meaningful clinical insight and added value with respect to the baseline provided the analysis procedure embeds the longitudinal information. Copyright © 2015 Elsevier Inc. All rights reserved.

Sample size determination for mediation analysis of longitudinal data.

PubMed

Pan, Haitao; Liu, Suyu; Miao, Danmin; Yuan, Ying

2018-03-27

Sample size planning for longitudinal data is crucial when designing mediation studies because sufficient statistical power is not only required in grant applications and peer-reviewed publications, but is essential to reliable research results. However, sample size determination is not straightforward for mediation analysis of longitudinal design. To facilitate planning the sample size for longitudinal mediation studies with a multilevel mediation model, this article provides the sample size required to achieve 80% power by simulations under various sizes of the mediation effect, within-subject correlations and numbers of repeated measures. The sample size calculation is based on three commonly used mediation tests: Sobel's method, distribution of product method and the bootstrap method. Among the three methods of testing the mediation effects, Sobel's method required the largest sample size to achieve 80% power. Bootstrapping and the distribution of the product method performed similarly and were more powerful than Sobel's method, as reflected by the relatively smaller sample sizes. For all three methods, the sample size required to achieve 80% power depended on the value of the ICC (i.e., within-subject correlation). A larger value of ICC typically required a larger sample size to achieve 80% power. Simulation results also illustrated the advantage of the longitudinal study design. The sample size tables for most encountered scenarios in practice have also been published for convenient use. Extensive simulations study showed that the distribution of the product method and bootstrapping method have superior performance to the Sobel's method, but the product method was recommended to use in practice in terms of less computation time load compared to the bootstrapping method. A R package has been developed for the product method of sample size determination in mediation longitudinal study design.

Joint modelling of longitudinal CEA tumour marker progression and survival data on breast cancer

NASA Astrophysics Data System (ADS)

Borges, Ana; Sousa, Inês; Castro, Luis

2017-06-01

This work proposes the use of Biostatistics methods to study breast cancer in patients of Braga's Hospital Senology Unit, located in Portugal. The primary motivation is to contribute to the understanding of the progression of breast cancer, within the Portuguese population, using a more complex statistical model assumptions than the traditional analysis that take into account a possible existence of a serial correlation structure within a same subject observations. We aim to infer which risk factors aect the survival of Braga's Hospital patients, diagnosed with breast tumour. Whilst analysing risk factors that aect a tumour markers used on the surveillance of disease progression the Carcinoembryonic antigen (CEA). As survival and longitudinal processes may be associated, it is important to model these two processes together. Hence, a joint modelling of these two processes to infer on the association of these was conducted. A data set of 540 patients, along with 50 variables, was collected from medical records of the Hospital. A joint model approach was used to analyse these data. Two dierent joint models were applied to the same data set, with dierent parameterizations which give dierent interpretations to model parameters. These were used by convenience as the ones implemented in R software. Results from the two models were compared. Results from joint models, showed that the longitudinal CEA values were signicantly associated with the survival probability of these patients. A comparison between parameter estimates obtained in this analysis and previous independent survival[4] and longitudinal analysis[5][6], lead us to conclude that independent analysis brings up bias parameter estimates. Hence, an assumption of association between the two processes in a joint model of breast cancer data is necessary. Results indicate that the longitudinal progression of CEA is signicantly associated with the probability of survival of these patients. Hence, an assumption of association between the two processes in a joint model of breast cancer data is necessary.

Application of variable-gain output feedback for high-alpha control

NASA Technical Reports Server (NTRS)

Ostroff, Aaron J.

1990-01-01

A variable-gain, optimal, discrete, output feedback design approach that is applied to a nonlinear flight regime is described. The flight regime covers a wide angle-of-attack range that includes stall and post stall. The paper includes brief descriptions of the variable-gain formulation, the discrete-control structure and flight equations used to apply the design approach, and the high performance airplane model used in the application. Both linear and nonlinear analysis are shown for a longitudinal four-model design case with angles of attack of 5, 15, 35, and 60 deg. Linear and nonlinear simulations are compared for a single-point longitudinal design at 60 deg angle of attack. Nonlinear simulations for the four-model, multi-mode, variable-gain design include a longitudinal pitch-up and pitch-down maneuver and high angle-of-attack regulation during a lateral maneuver.

LADES: a software for constructing and analyzing longitudinal designs in biomedical research.

PubMed

Vázquez-Alcocer, Alan; Garzón-Cortes, Daniel Ladislao; Sánchez-Casas, Rosa María

2014-01-01

One of the most important steps in biomedical longitudinal studies is choosing a good experimental design that can provide high accuracy in the analysis of results with a minimum sample size. Several methods for constructing efficient longitudinal designs have been developed based on power analysis and the statistical model used for analyzing the final results. However, development of this technology is not available to practitioners through user-friendly software. In this paper we introduce LADES (Longitudinal Analysis and Design of Experiments Software) as an alternative and easy-to-use tool for conducting longitudinal analysis and constructing efficient longitudinal designs. LADES incorporates methods for creating cost-efficient longitudinal designs, unequal longitudinal designs, and simple longitudinal designs. In addition, LADES includes different methods for analyzing longitudinal data such as linear mixed models, generalized estimating equations, among others. A study of European eels is reanalyzed in order to show LADES capabilities. Three treatments contained in three aquariums with five eels each were analyzed. Data were collected from 0 up to the 12th week post treatment for all the eels (complete design). The response under evaluation is sperm volume. A linear mixed model was fitted to the results using LADES. The complete design had a power of 88.7% using 15 eels. With LADES we propose the use of an unequal design with only 14 eels and 89.5% efficiency. LADES was developed as a powerful and simple tool to promote the use of statistical methods for analyzing and creating longitudinal experiments in biomedical research.

Longitudinal multigroup invariance analysis of the satisfaction with food-related life scale in university students.

PubMed

Schnettler, Berta; Miranda, Horacio; Miranda-Zapata, Edgardo; Salinas-Oñate, Natalia; Grunert, Klaus G; Lobos, Germán; Sepúlveda, José; Orellana, Ligia; Hueche, Clementina; Bonilla, Héctor

2017-06-01

This study examined longitudinal measurement invariance in the Satisfaction with Food-related Life (SWFL) scale using follow-up data from university students. We examined this measure of the SWFL in different groups of students, separated by various characteristics. Through non-probabilistic longitudinal sampling, 114 university students (65.8% female, mean age: 22.5) completed the SWFL questionnaire three times, over intervals of approximately one year. Confirmatory factor analysis was used to examine longitudinal measurement invariance. Two types of analysis were conducted: first, a longitudinal invariance by time, and second, a multigroup longitudinal invariance by sex, age, socio-economic status and place of residence during the study period. Results showed that the 3-item version of the SWFL exhibited strong longitudinal invariance (equal factor loadings and equal indicator intercepts). Longitudinal multigroup invariance analysis also showed that the 3-item version of the SWFL displays strong invariance by socio-economic status and place of residence during the study period over time. Nevertheless, it was only possible to demonstrate equivalence of the longitudinal factor structure among students of both sexes, and among those older and younger than 22 years. Generally, these findings suggest that the SWFL scale has satisfactory psychometric properties for longitudinal measurement invariance in university students with similar characteristics as the students that participated in this research. It is also possible to suggest that satisfaction with food-related life is associated with sex and age. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Study of the Factors Associated with Risk for Development of Pressure Ulcers: A Longitudinal Analysis

PubMed Central

Thomas, Elizebeth; Vinodkumar, Sudhaya; Mathew, Silvia; Setia, Maninder Singh

2015-01-01

Background: Pressure ulcers (PUs) are prevalent in hospitalized patients; they may cause clinical, psychological, and economic problems in these patients. Previous studies are cross-sectional, have used pooled data, or cox-regression models to assess the risk for developing PU. However, PU risk scores change over time and models that account for time varying variables are useful for cohort analysis of data. Aims and Objectives: The present longitudinal study was conducted to compare the risk of PU between surgical and nonsurgical patients, and to evaluate the factors associated with the development of these ulcers over a period of time. Materials and Methods: We evaluated 290 hospitalized patients over a 4 months period. The main outcomes for our analysis were: (1) Score on the pressure risk assessment scale; and (2) the proportion of individuals who were at severe risk for developing PUs. We used random effects models for longitudinal analysis of the data. Results: The mean PU score was significantly higher in the nonsurgical patients compared with surgical patients at baseline (15.23 [3.86] vs. 9.33 [4.57]; P < 0.01). About 7% of the total patients had a score of >20 at baseline and were considered as being at high-risk for PU; the proportion was significantly higher among the nonsurgical patients compared with the surgical patients (14% vs. 4%, P = 0.003). In the adjusted models, there was no difference for severe risk for PU between surgical and nonsurgical patients (odds ratios [ORs]: 0.37, 95% confidence interval [CI]: 0.01–12.80). An additional day in the ward was associated with a significantly higher likelihood of being at high-risk for PU (OR: 1.47, 95% CI: 1.16–1.86). Conclusion: There were no significant differences between patients who were admitted for surgery compared with those who were not. An additional day in the ward, however, is important for developing a high-risk score for PU on the monitoring scale, and these patients require active interventions. PMID:26677269

Big data in multiple sclerosis: development of a web-based longitudinal study viewer in an imaging informatics-based eFolder system for complex data analysis and management

NASA Astrophysics Data System (ADS)

Ma, Kevin; Wang, Ximing; Lerner, Alex; Shiroishi, Mark; Amezcua, Lilyana; Liu, Brent

2015-03-01

In the past, we have developed and displayed a multiple sclerosis eFolder system for patient data storage, image viewing, and automatic lesion quantification results stored in DICOM-SR format. The web-based system aims to be integrated in DICOM-compliant clinical and research environments to aid clinicians in patient treatments and disease tracking. This year, we have further developed the eFolder system to handle big data analysis and data mining in today's medical imaging field. The database has been updated to allow data mining and data look-up from DICOM-SR lesion analysis contents. Longitudinal studies are tracked, and any changes in lesion volumes and brain parenchyma volumes are calculated and shown on the webbased user interface as graphical representations. Longitudinal lesion characteristic changes are compared with patients' disease history, including treatments, symptom progressions, and any other changes in the disease profile. The image viewer is updated such that imaging studies can be viewed side-by-side to allow visual comparisons. We aim to use the web-based medical imaging informatics eFolder system to demonstrate big data analysis in medical imaging, and use the analysis results to predict MS disease trends and patterns in Hispanic and Caucasian populations in our pilot study. The discovery of disease patterns among the two ethnicities is a big data analysis result that will help lead to personalized patient care and treatment planning.

Against Conventional Wisdom: Factors Influencing Hispanic Students' Reading Achievement

ERIC Educational Resources Information Center

Percell, Jay C.; Kaufman, Kristina

2013-01-01

The researchers performed a variable analysis of the 2002 Educational Longitudinal Study data investigating factors that influence students' reading scores on standardized tests. Hispanic and non-Hispanic Scores were analyzed and controlling variables were compared to determine the effect of each on both populations. Certain variables commonly…

An early and late peak in microglial activation in Alzheimer's disease trajectory.

PubMed

Fan, Zhen; Brooks, David J; Okello, Aren; Edison, Paul

2017-03-01

Amyloid-β deposition, neuroinflammation and tau tangle formation all play a significant role in Alzheimer's disease. We hypothesized that there is microglial activation early on in Alzheimer's disease trajectory, where in the initial phase, microglia may be trying to repair the damage, while later on in the disease these microglia could be ineffective and produce proinflammatory cytokines leading to progressive neuronal damage. In this longitudinal study, we have evaluated the temporal profile of microglial activation and its relationship between fibrillar amyloid load at baseline and follow-up in subjects with mild cognitive impairment, and this was compared with subjects with Alzheimer's disease. Thirty subjects (eight mild cognitive impairment, eight Alzheimer's disease and 14 controls) aged between 54 and 77 years underwent 11C-(R)PK11195, 11C-PIB positron emission tomography and magnetic resonance imaging scans. Patients were followed-up after 14 ± 4 months. Region of interest and Statistical Parametric Mapping analysis were used to determine longitudinal alterations. Single subject analysis was performed to evaluate the individualized pathological changes over time. Correlations between levels of microglial activation and amyloid deposition at a voxel level were assessed using Biological Parametric Mapping. We demonstrated that both baseline and follow-up microglial activation in the mild cognitive impairment cohort compared to controls were increased by 41% and 21%, respectively. There was a longitudinal reduction of 18% in microglial activation in mild cognitive impairment cohort over 14 months, which was associated with a mild elevation in fibrillar amyloid load. Cortical clusters of microglial activation and amyloid deposition spatially overlapped in the subjects with mild cognitive impairment. Baseline microglial activation was increased by 36% in Alzheimer's disease subjects compared with controls. Longitudinally, Alzheimer's disease subjects showed an increase in microglial activation. In conclusion, this is one of the first longitudinal positron emission tomography studies evaluating longitudinal changes in microglial activation in mild cognitive impairment and Alzheimer's disease subjects. We found there is an initial longitudinal reduction in microglial activation in subjects with mild cognitive impairment, while subjects with Alzheimer's disease showed an increase in microglial activation. This could reflect that activated microglia in mild cognitive impairment initially may adopt a protective activation phenotype, which later change to a cidal pro-inflammatory phenotype as disease progresses and amyloid clearance fails. Thus, we speculate that there might be two peaks of microglial activation in the Alzheimer's disease trajectory; an early protective peak and a later pro-inflammatory peak. If so, anti-microglial agents targeting the pro-inflammatory phenotype would be most beneficial in the later stages of the disease. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Patient safety in the clinical laboratory: a longitudinal analysis of specimen identification errors.

PubMed

Wagar, Elizabeth A; Tamashiro, Lorraine; Yasin, Bushra; Hilborne, Lee; Bruckner, David A

2006-11-01

Patient safety is an increasingly visible and important mission for clinical laboratories. Attention to improving processes related to patient identification and specimen labeling is being paid by accreditation and regulatory organizations because errors in these areas that jeopardize patient safety are common and avoidable through improvement in the total testing process. To assess patient identification and specimen labeling improvement after multiple implementation projects using longitudinal statistical tools. Specimen errors were categorized by a multidisciplinary health care team. Patient identification errors were grouped into 3 categories: (1) specimen/requisition mismatch, (2) unlabeled specimens, and (3) mislabeled specimens. Specimens with these types of identification errors were compared preimplementation and postimplementation for 3 patient safety projects: (1) reorganization of phlebotomy (4 months); (2) introduction of an electronic event reporting system (10 months); and (3) activation of an automated processing system (14 months) for a 24-month period, using trend analysis and Student t test statistics. Of 16,632 total specimen errors, mislabeled specimens, requisition mismatches, and unlabeled specimens represented 1.0%, 6.3%, and 4.6% of errors, respectively. Student t test showed a significant decrease in the most serious error, mislabeled specimens (P < .001) when compared to before implementation of the 3 patient safety projects. Trend analysis demonstrated decreases in all 3 error types for 26 months. Applying performance-improvement strategies that focus longitudinally on specimen labeling errors can significantly reduce errors, therefore improving patient safety. This is an important area in which laboratory professionals, working in interdisciplinary teams, can improve safety and outcomes of care.

A Primer on Longitudinal Data Analysis in Education. Technical Report #1320

ERIC Educational Resources Information Center

Nese, Joseph F. T.; Lai, Cheng-Fei; Anderson, Daniel

2013-01-01

Longitudinal data analysis in education is the study growth over time. A longitudinal study is one in which repeated observations of the same variables are recorded for the same individuals over a period of time. This type of research is known by many names (e.g., time series analysis or repeated measures design), each of which can imply subtle…

Clustering of longitudinal data by using an extended baseline: A new method for treatment efficacy clustering in longitudinal data.

PubMed

Schramm, Catherine; Vial, Céline; Bachoud-Lévi, Anne-Catherine; Katsahian, Sandrine

2018-01-01

Heterogeneity in treatment efficacy is a major concern in clinical trials. Clustering may help to identify the treatment responders and the non-responders. In the context of longitudinal cluster analyses, sample size and variability of the times of measurements are the main issues with the current methods. Here, we propose a new two-step method for the Clustering of Longitudinal data by using an Extended Baseline. The first step relies on a piecewise linear mixed model for repeated measurements with a treatment-time interaction. The second step clusters the random predictions and considers several parametric (model-based) and non-parametric (partitioning, ascendant hierarchical clustering) algorithms. A simulation study compares all options of the clustering of longitudinal data by using an extended baseline method with the latent-class mixed model. The clustering of longitudinal data by using an extended baseline method with the two model-based algorithms was the more robust model. The clustering of longitudinal data by using an extended baseline method with all the non-parametric algorithms failed when there were unequal variances of treatment effect between clusters or when the subgroups had unbalanced sample sizes. The latent-class mixed model failed when the between-patients slope variability is high. Two real data sets on neurodegenerative disease and on obesity illustrate the clustering of longitudinal data by using an extended baseline method and show how clustering may help to identify the marker(s) of the treatment response. The application of the clustering of longitudinal data by using an extended baseline method in exploratory analysis as the first stage before setting up stratified designs can provide a better estimation of treatment effect in future clinical trials.

Hollow-cylinder waveguide isolators for use at millimeter wavelengths

NASA Technical Reports Server (NTRS)

Kanda, M.; May, W. G.

1974-01-01

A semiconductor waveguide isolator consisting of a hollow column of a semiconductor mounted coaxially is considered in a circular waveguide in a longitudinal dc magnetic field. An elementary and physical analysis based on the excitation of plane waves in the guide and a more rigorous mode matching analysis are presented. These theoretical predictions are compared with experimental results for an InSb isolator at 94GHz and 75 K.

Mild thyroid hormone excess is associated with a decreased physical function in elderly men.

PubMed

Ceresini, Graziano; Ceda, Gian Paolo; Lauretani, Fulvio; Maggio, Marcello; Bandinelli, Stefania; Guralnik, Jack M; Cappola, Anne R; Usberti, Elisa; Morganti, Simonetta; Valenti, Giorgio; Ferrucci, Luigi

2011-12-01

In the adult, subclinical hyperthyroidism (Shyper) may alter skeletal muscle mass and strength. However, whether these effects are present in elderly subjects is not known. We explored the relationship between mild hyperthyroidism and physical function in a population-based sample of older persons. In a cross-sectional analysis, calf muscle cross-sectional area (CMA), handgrip strength, nerve conduction velocity (NCV), and Short Physical Performance Battery (SPPB) scores were compared between 364 euthyroid (Eut) and 28 Shyper men as well as between 502 Eut and 39 Shyper women. In a longitudinal analysis, we evaluated the relationship between baseline plasma TSH, FT3 and FT4 and the 3-year change in SPPB score in 304 men and 409 women who were euthyroid at enrolment. At the cross-sectional analysis, Shyper men, but not women, had a significantly (p = 0.02) lower SPPB score than Eut controls, although with comparable CMA, grip strength and NCV, and were more likely to have poor physical performance (odds ratio = 2.97, p < 0.05). Longitudinal analysis showed that in Eut men higher baseline FT4 was significantly (p = 0.02) predictive of a lower SPPB score at the 3-year follow-up. Even a modest thyroid hormone excess is associated with a reduced physical function in elderly men.

The effects of variable sample biomass on comparative metagenomics.

PubMed

Chafee, Meghan; Maignien, Loïs; Simmons, Sheri L

2015-07-01

Longitudinal studies that integrate samples with variable biomass are essential to understand microbial community dynamics across space or time. Shotgun metagenomics is widely used to investigate these communities at the functional level, but little is known about the effects of combining low and high biomass samples on downstream analysis. We investigated the interacting effects of DNA input and library amplification by polymerase chain reaction on comparative metagenomic analysis using dilutions of a single complex template from an Arabidopsis thaliana-associated microbial community. We modified the Illumina Nextera kit to generate high-quality large-insert (680 bp) paired-end libraries using a range of 50 pg to 50 ng of input DNA. Using assembly-based metagenomic analysis, we demonstrate that DNA input level has a significant impact on community structure due to overrepresentation of low-GC genomic regions following library amplification. In our system, these differences were largely superseded by variations between biological replicates, but our results advocate verifying the influence of library amplification on a case-by-case basis. Overall, this study provides recommendations for quality filtering and de-replication prior to analysis, as well as a practical framework to address the issue of low biomass or biomass heterogeneity in longitudinal metagenomic surveys. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Differential rate in decline in ovarian reserve markers in women with polycystic ovary syndrome compared with control subjects: results of a longitudinal study.

PubMed

Ahmad, Asima K; Kao, Chia-Ning; Quinn, Molly; Lenhart, Nikolaus; Rosen, Mitchell; Cedars, Marcelle I; Huddleston, Heather

2018-03-01

To estimate rates of ovarian aging in polycystic ovary syndrome (PCOS) subjects versus a community control population. Longitudinal. Tertiary academic center. PCOS subjects diagnosed according to the 2004 Rotterdam criteria were systematically enrolled in a PCOS cohort study. The comparison control subjects were from the Ovarian Aging study, a prospective longitudinal study of ovarian aging in healthy women with regular menstrual cycles. Clinical data collection over two study visits. Antral follicle count (AFC), ovarian volume (OV), and antimüllerian hormone level (AMH). PCOS subjects were found to have higher baseline values for all ovarian reserve markers compared with control subjects. Univariate models indicated that, compared with control subjects, PCOS patients experienced significantly faster rates of decline for both AFC and AMH. Change in OV did not differ significantly. To account for potential confounder effects, multiple analysis of covariance models were evaluated for the best fit, considering age, body mass index, and baseline ovarian reserve markers. Adjusted models demonstrated that PCOS patients do not experience a significant difference in AFC decline compared with control subjects, but they do experience a faster rate of decline in AMH (P<.01) and slower rate of decline in OV (P<.01). Ovarian aging in PCOS is characterized by a more rapid decline in AMH and a slower decline in OV compared with control subjects. Copyright © 2017 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Association of left ventricular longitudinal and circumferential systolic dysfunction with diastolic function in hypertension: a nonlinear analysis focused on the interplay with left ventricular geometry.

PubMed

Ballo, Piercarlo; Nistri, Stefano; Cameli, Matteo; Papesso, Barbara; Dini, Frank Lloyd; Galderisi, Maurizio; Zuppiroli, Alfredo; Mondillo, Sergio

2014-02-01

The relationships of left ventricular (LV) longitudinal and circumferential systolic dysfunction with diastolic performance in hypertensive patients have never been compared. In 532 asymptomatic hypertensive patients, circumferential function was assessed with the use of midwall fractional shortening (mFS) and stress-corrected mFS (SCmFS), whereas longitudinal function was assessed with the use of left atrioventricular plane displacement (AVPD) and systolic mitral annulus velocity (s'). Early diastolic annular velocity (e') and the E/e' ratio were measured. Global longitudinal and circumferential strain were determined in a subset of 210 patients. e' was linearly related to all systolic indexes (AVPD: R = 0.40; s': R = 0.39; mFS: R = 0.16; SCmFS: R = 0.17; all P < .0001), but the correlations were stronger with longitudinal indexes than with circumferential ones (P < .0001). E/e' was nonlinearly related to AVPD (R = -0.49; P < .0001) and s' (R = -0.34; P < .0001) and showed no relationship with mFS and SCmFS. Longitudinal indexes were superior to circumferential ones in predicting e' <8 cm/s, E/e' <8, and E/e' ≥13. The effect of LV geometry on LV diastolic function was evident among patients with preserved systolic longitudinal function, but was blunted among patients with impaired longitudinal function. In multivariable analyses, only longitudinal indexes remained associated with e' and E/e'. Analyses using strains provided similar results. In asymptomatic hypertensive subjects, LV diastolic performance is independently associated with longitudinal systolic dysfunction, but not with circumferential systolic dysfunction. Subtle longitudinal systolic impairment plays a role in mediating the effect of LV geometry on diastolic performance. These findings may support the need of critically revising the concept of isolated diastolic dysfunction in these patients. Copyright © 2014 Elsevier Inc. All rights reserved.

Estimation of Covariance Matrix on Bi-Response Longitudinal Data Analysis with Penalized Spline Regression

NASA Astrophysics Data System (ADS)

Islamiyati, A.; Fatmawati; Chamidah, N.

2018-03-01

The correlation assumption of the longitudinal data with bi-response occurs on the measurement between the subjects of observation and the response. It causes the auto-correlation of error, and this can be overcome by using a covariance matrix. In this article, we estimate the covariance matrix based on the penalized spline regression model. Penalized spline involves knot points and smoothing parameters simultaneously in controlling the smoothness of the curve. Based on our simulation study, the estimated regression model of the weighted penalized spline with covariance matrix gives a smaller error value compared to the error of the model without covariance matrix.

Comparison of Segmental Versus Longitudinal Intravascular Ultrasound Analysis for Pediatric Cardiac Allograft Vasculopathy.

PubMed

Kuhn, M A; Burch, M; Chinnock, R E; Fenton, M J

2017-10-01

Intravascular ultrasound (IVUS) has been routinely used in some centers to investigate cardiac allograft vasculopathy in pediatric heart transplant recipients. We present an alternative method using more sophisticated imaging software. This study presents a comparison of this method with an established standard method. All patients who had IVUS performed in 2014 were retrospectively evaluated. The standard technique consisted of analysis of 10 operator-selected segments along the vessel. Each study was re-evaluated using a longitudinal technique, taken at every third cardiac cycle, along the entire vessel. Semiautomatic edge detection software was used to detect vessel imaging planes. Measurements included outer and inner diameter, total and luminal area, maximal intimal thickness (MIT), and intimal index. Each IVUS was graded for severity using the Stanford classification. All results were given as mean ± standard deviation (SD). Groups were compared using Student t test. A P value <.05 was considered significant. There were 59 IVUS studies performed on 58 patients. There was no statistically significant difference between outer diameter, inner diameter, or total area. In the longitudinal group, there was a significantly smaller luminal area, higher MIT, and higher intimal index. Using the longitudinal technique, there was an increase in Stanford classification in 20 patients. The longitudinal technique appeared more sensitive in assessing the degree of cardiac allograft vasculopathy and may play a role in the increase in the degree of thickening seen. It may offer an alternative way of grading severity of cardiac allograft vasculopathy in pediatric heart transplant recipients. Copyright © 2017 Elsevier Inc. All rights reserved.

Longitudinal plasma metanephrines preceding pheochromocytoma diagnosis: a retrospective case-control serum repository study.

PubMed

Olson, S W; Yoon, S; Baker, T; Prince, L K; Oliver, D; Abbott, K C

2016-03-01

Plasma metanephrines (PMN) are highly sensitive for diagnosis of pheochromocytoma, but the natural history of PMN before pheochromocytoma diagnosis has not been previously described. The aim of the study was to compare the progression of PMN before pheochromocytoma diagnosis to matched healthy and essential hypertension disease controls. A retrospective case-control Department of Defense Serum Repository (DoDSR) study. We performed a DoDSR study that compared three longitudinal pre-diagnostic PMN for 30 biopsy-proven pheochromocytoma cases to three longitudinal PMN for age, sex, race, and age of serum sample matched healthy and essential hypertension disease controls. Predominant metanephrine (MN) or normetanephrine (NMN) production was identified for each case and converted to a percentage of the upper limit of normal to allow analysis of all cases together. PMN were measured by Quest Diagnostics. The predominant plasma metanephrine (PPM) was >100 and 300% of the upper limit of normal a median of 6.6 and 4.1 years before diagnosis respectively. A greater percentage of pheochromocytoma patients had a PPM >100 and >300% of the upper limit of normal compared with combined healthy and essential hypertension disease controls <2, 2-8, and >8 years prior to diagnosis. For patients with a baseline PPM 90-300% of the upper limit of normal, a 25% rate of rise per year was 100% specific for pheochromocytoma. PPMs elevate years before diagnosis which suggests that delayed diagnoses are common. For mild PMN elevations, follow-up longitudinal PMN trends may provide a highly specific and economical diagnostic tool. © 2016 European Society of Endocrinology.

The enduring effects of psychodynamic treatments vis-a-vis alternative treatments: A multilevel longitudinal meta-analysis

NASA Astrophysics Data System (ADS)

Kivlighan, D. Martin, III

Although evidence suggests that the benefits of psychodynamic treatments are sustained over time, presently it is unclear whether these sustained benefits are superior to non-psychodynamic treatments. Additionally, the extant literature comparing the sustained benefits of psychodynamic treatments compared to alternative treatments is limited with methodological shortcomings. The purpose of the current study was to conduct a rigorous test of the growth of the benefits of psychodynamic treatments relative to alternative treatments across distinct domains of change (i.e., all outcome measures, targeted outcome measures, non-targeted outcome measures, and personality outcome measures). To do so, the study employed strict inclusion criteria to identify randomized clinical trials that directly compared at least one bona fide psychodynamic treatment and one bona fide non-psychodynamic treatment. Hierarchical linear modeling (Raudenbush, Bryk, Cheong & Congdon, du Toit, 2011) was used to longitudinally model the impact of psychodynamic treatments compared to non-psychodynamic treatments at post-treatment and to compare the growth (i.e., slope) of effects beyond treatment completion. Findings from the present meta-analysis indicated that psychodynamic treatments and non-psychodynamic treatments were equally efficacious at post-treatment and at follow-up for combined outcomes ( k = 20), targeted outcomes (k =19), non-targeted outcomes (k =17), and personality outcomes (k =6). Clinical implications, directions for future research, and limitations are discussed.

Selecting a Separable Parametric Spatiotemporal Covariance Structure for Longitudinal Imaging Data

PubMed Central

George, Brandon; Aban, Inmaculada

2014-01-01

Longitudinal imaging studies allow great insight into how the structure and function of a subject’s internal anatomy changes over time. Unfortunately, the analysis of longitudinal imaging data is complicated by inherent spatial and temporal correlation: the temporal from the repeated measures, and the spatial from the outcomes of interest being observed at multiple points in a patients body. We propose the use of a linear model with a separable parametric spatiotemporal error structure for the analysis of repeated imaging data. The model makes use of spatial (exponential, spherical, and Matérn) and temporal (compound symmetric, autoregressive-1, Toeplitz, and unstructured) parametric correlation functions. A simulation study, inspired by a longitudinal cardiac imaging study on mitral regurgitation patients, compared different information criteria for selecting a particular separable parametric spatiotemporal correlation structure as well as the effects on Type I and II error rates for inference on fixed effects when the specified model is incorrect. Information criteria were found to be highly accurate at choosing between separable parametric spatiotemporal correlation structures. Misspecification of the covariance structure was found to have the ability to inflate the Type I error or have an overly conservative test size, which corresponded to decreased power. An example with clinical data is given illustrating how the covariance structure procedure can be done in practice, as well as how covariance structure choice can change inferences about fixed effects. PMID:25293361

Factor structure and longitudinal measurement invariance of the demand control support model: an evidence from the Swedish Longitudinal Occupational Survey of Health (SLOSH).

PubMed

Chungkham, Holendro Singh; Ingre, Michael; Karasek, Robert; Westerlund, Hugo; Theorell, Töres

2013-01-01

To examine the factor structure and to evaluate the longitudinal measurement invariance of the demand-control-support questionnaire (DCSQ), using the Swedish Longitudinal Occupational Survey of Health (SLOSH). A confirmatory factor analysis (CFA) and multi-group confirmatory factor analysis (MGCFA) models within the framework of structural equation modeling (SEM) have been used to examine the factor structure and invariance across time. Four factors: psychological demand, skill discretion, decision authority and social support, were confirmed by CFA at baseline, with the best fit obtained by removing the item repetitive work of skill discretion. A measurement error correlation (0.42) between work fast and work intensively for psychological demands was also detected. Acceptable composite reliability measures were obtained except for skill discretion (0.68). The invariance of the same factor structure was established, but caution in comparing mean levels of factors over time is warranted as lack of intercept invariance was evident. However, partial intercept invariance was established for work intensively. Our findings indicate that skill discretion and decision authority represent two distinct constructs in the retained model. However removing the item repetitive work along with either work fast or work intensively would improve model fit. Care should also be taken while making comparisons in the constructs across time. Further research should investigate invariance across occupations or socio-economic classes.

Factor Structure and Longitudinal Measurement Invariance of the Demand Control Support Model: An Evidence from the Swedish Longitudinal Occupational Survey of Health (SLOSH)

PubMed Central

Chungkham, Holendro Singh; Ingre, Michael; Karasek, Robert; Westerlund, Hugo; Theorell, Töres

2013-01-01

Objectives To examine the factor structure and to evaluate the longitudinal measurement invariance of the demand-control-support questionnaire (DCSQ), using the Swedish Longitudinal Occupational Survey of Health (SLOSH). Methods A confirmatory factor analysis (CFA) and multi-group confirmatory factor analysis (MGCFA) models within the framework of structural equation modeling (SEM) have been used to examine the factor structure and invariance across time. Results Four factors: psychological demand, skill discretion, decision authority and social support, were confirmed by CFA at baseline, with the best fit obtained by removing the item repetitive work of skill discretion. A measurement error correlation (0.42) between work fast and work intensively for psychological demands was also detected. Acceptable composite reliability measures were obtained except for skill discretion (0.68). The invariance of the same factor structure was established, but caution in comparing mean levels of factors over time is warranted as lack of intercept invariance was evident. However, partial intercept invariance was established for work intensively. Conclusion Our findings indicate that skill discretion and decision authority represent two distinct constructs in the retained model. However removing the item repetitive work along with either work fast or work intensively would improve model fit. Care should also be taken while making comparisons in the constructs across time. Further research should investigate invariance across occupations or socio-economic classes. PMID:23950957

A New Local Failure Model with Application to the Longitudinal Tensile Behavior of Continuously Reinforced Titanium Composites

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2000-01-01

A new model for local fiber failures in composite materials loaded longitudinally is presented. In developing the model, the goal was to account for the effects of fiber breakage on the global response of a composite in a relatively simple and efficient manner. Towards this end, the model includes the important feature of local stress unloading, even as global loading of the composite continues. The model has been incorporated into NASA Glenn's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) and was employed to simulate the longitudinal tensile deformation and failure behavior of several silicon carbide fiber/titanium matrix (SiC/Ti) composites. The model is shown to be quite realistic and capable of accurate predictions for various temperatures, fiber volume fractions, and fiber diameters. Further- more, the new model compares favorably to Curtin's (1993) effective fiber breakage model, which has also been incorporated into MAC/GMC.

Power analysis on the time effect for the longitudinal Rasch model.

PubMed

Feddag, M L; Blanchin, M; Hardouin, J B; Sebille, V

2014-01-01

Statistics literature in the social, behavioral, and biomedical sciences typically stress the importance of power analysis. Patient Reported Outcomes (PRO) such as quality of life and other perceived health measures (pain, fatigue, stress,...) are increasingly used as important health outcomes in clinical trials or in epidemiological studies. They cannot be directly observed nor measured as other clinical or biological data and they are often collected through questionnaires with binary or polytomous items. The Rasch model is the well known model in the item response theory (IRT) for binary data. The article proposes an approach to evaluate the statistical power of the time effect for the longitudinal Rasch model with two time points. The performance of this method is compared to the one obtained by simulation study. Finally, the proposed approach is illustrated on one subscale of the SF-36 questionnaire.

Subterahertz Longitudinal Phonon Modes Propagating in a Lipid Bilayer Immersed in an Aqueous Medium

NASA Astrophysics Data System (ADS)

Zakhvataev, V. E.

2018-04-01

The properties of subterahertz longitudinal acoustic phonon modes in the hydrophobic region of a lipid bilayer immersed in a compressible viscous aqueous medium are investigated theoretically. An approximate expression is obtained for the Mandelstam-Brillouin components of the dynamic structure factor of a bilayer. The analysis is based on a generalized hydrodynamic model of the "two-dimensional lipid bilayer + three-dimensional fluid medium" system, as well as on known sharp estimates for the frequencies and lifetimes of long-wavelength longitudinal acoustic phonons in a free hydrated lipid bilayer and in water, obtained from inelastic X-ray scattering experiments and molecular dynamics simulations. It is shown that, for characteristic values of the parameters of the membrane system, subterahertz longitudinal phonon-like excitations in the hydrophobic part of the bilayer are underdamped. In this case, the contribution of the viscous flow of the aqueous medium to the damping of a longitudinal membrane mode is small compared with the contribution of the lipid bilayer. Quantitative estimates of the damping ratio agree well with the experimental results for the vibration mode of the enzyme lysozyme in aqueous solution [1]. It is also shown that a coupling between longitudinal phonon modes of the bilayer and relaxation processes in its fluid environment gives rise to an additional peak in the scattering spectrum, which corresponds to a non-propagating mode.

A bidimensional finite mixture model for longitudinal data subject to dropout.

PubMed

Spagnoli, Alessandra; Marino, Maria Francesca; Alfò, Marco

2018-06-05

In longitudinal studies, subjects may be lost to follow up and, thus, present incomplete response sequences. When the mechanism underlying the dropout is nonignorable, we need to account for dependence between the longitudinal and the dropout process. We propose to model such a dependence through discrete latent effects, which are outcome-specific and account for heterogeneity in the univariate profiles. Dependence between profiles is introduced by using a probability matrix to describe the corresponding joint distribution. In this way, we separately model dependence within each outcome and dependence between outcomes. The major feature of this proposal, when compared with standard finite mixture models, is that it allows the nonignorable dropout model to properly nest its ignorable counterpart. We also discuss the use of an index of (local) sensitivity to nonignorability to investigate the effects that assumptions about the dropout process may have on model parameter estimates. The proposal is illustrated via the analysis of data from a longitudinal study on the dynamics of cognitive functioning in the elderly. Copyright © 2018 John Wiley & Sons, Ltd.

Spatio-Temporal Regularization for Longitudinal Registration to Subject-Specific 3d Template

PubMed Central

Guizard, Nicolas; Fonov, Vladimir S.; García-Lorenzo, Daniel; Nakamura, Kunio; Aubert-Broche, Bérengère; Collins, D. Louis

2015-01-01

Neurodegenerative diseases such as Alzheimer's disease present subtle anatomical brain changes before the appearance of clinical symptoms. Manual structure segmentation is long and tedious and although automatic methods exist, they are often performed in a cross-sectional manner where each time-point is analyzed independently. With such analysis methods, bias, error and longitudinal noise may be introduced. Noise due to MR scanners and other physiological effects may also introduce variability in the measurement. We propose to use 4D non-linear registration with spatio-temporal regularization to correct for potential longitudinal inconsistencies in the context of structure segmentation. The major contribution of this article is the use of individual template creation with spatio-temporal regularization of the deformation fields for each subject. We validate our method with different sets of real MRI data, compare it to available longitudinal methods such as FreeSurfer, SPM12, QUARC, TBM, and KNBSI, and demonstrate that spatially local temporal regularization yields more consistent rates of change of global structures resulting in better statistical power to detect significant changes over time and between populations. PMID:26301716

Facebook: an effective tool for participant retention in longitudinal research.

PubMed

Mychasiuk, R; Benzies, K

2012-09-01

Facebook is currently one of the world's most visited websites, and home to millions of users who access their accounts on a regular basis. Owing to the website's ease of accessibility and free service, demographic characteristics of users span all domains. As such, Facebook may be a valuable tool for locating and communicating with participants in longitudinal research studies. This article outlines the benefit gained in a longitudinal follow-up study, of an intervention programme for at-risk families, through the use of Facebook as a search engine. Using Facebook as a resource, we were able to locate 19 participants that were otherwise 'lost' to follow-up, decreasing attrition in our study by 16%. Additionally, analysis indicated that hard-to-reach participants located with Facebook differed significantly on measures of receptive language and self-esteem when compared to their easier-to-locate counterparts. These results suggest that Facebook is an effective means of improving participant retention in a longitudinal intervention study and may help improve study validity by reaching participants that contribute differing results. © 2011 Blackwell Publishing Ltd.

Mendelian randomization analysis of a time-varying exposure for binary disease outcomes using functional data analysis methods.

PubMed

Cao, Ying; Rajan, Suja S; Wei, Peng

2016-12-01

A Mendelian randomization (MR) analysis is performed to analyze the causal effect of an exposure variable on a disease outcome in observational studies, by using genetic variants that affect the disease outcome only through the exposure variable. This method has recently gained popularity among epidemiologists given the success of genetic association studies. Many exposure variables of interest in epidemiological studies are time varying, for example, body mass index (BMI). Although longitudinal data have been collected in many cohort studies, current MR studies only use one measurement of a time-varying exposure variable, which cannot adequately capture the long-term time-varying information. We propose using the functional principal component analysis method to recover the underlying individual trajectory of the time-varying exposure from the sparsely and irregularly observed longitudinal data, and then conduct MR analysis using the recovered curves. We further propose two MR analysis methods. The first assumes a cumulative effect of the time-varying exposure variable on the disease risk, while the second assumes a time-varying genetic effect and employs functional regression models. We focus on statistical testing for a causal effect. Our simulation studies mimicking the real data show that the proposed functional data analysis based methods incorporating longitudinal data have substantial power gains compared to standard MR analysis using only one measurement. We used the Framingham Heart Study data to demonstrate the promising performance of the new methods as well as inconsistent results produced by the standard MR analysis that relies on a single measurement of the exposure at some arbitrary time point. © 2016 WILEY PERIODICALS, INC.

Longitudinal Analysis of Corporate Social Responsibility on Company Websites

ERIC Educational Resources Information Center

Smith, Katherine Taken

2017-01-01

As social issues increase, so does the scope of corporate social responsibility (CSR). Companies are expanding their CSR activities and making the terminology used to describe them more specific. This study compares website content of "Fortune" 500 companies in 2015 with content collected in 2011. Traditionally, two CSR issues have been…

Mean-Level Change and Intraindividual Variability in Self-Esteem and Depression among High-Risk Children

ERIC Educational Resources Information Center

Kim, Jungmeen; Cicchetti, Dante

2009-01-01

This study investigated mean-level changes and intraindividual variability of self-esteem among maltreated (N = 142) and nonmaltreated (N = 109) school-aged children from low-income families. Longitudinal factor analysis revealed higher temporal stability of self-esteem among maltreated children compared to nonmaltreated children. Cross-domain…

[Prematurity: longitudinal analysis of executive functions].

PubMed

Sastre-Riba, S

2009-02-27

Understanding cognitive development requires an interdisciplinary and neuropsychological approach. Executive functions facilitates cognitive activity and they are related to progressive cerebral configuration during pregnancy and infancy. One of the aims of the actual neuropsychology is the ontogeny of executive functions and their capacity to explain differential and normative developmental trends, specially because of its consequences on mental flexibility, monitoring, planning and cognitive control; they are also essential for good performance at school. The incidence of developmental risk factors as prematurity could affect long-term executive functioning expressed in learning difficulties or behavioral control. We studied, comparatively and longitudinally, the individual activity on objects displayed by typical babies (n = 25), and preterm babies (n = 10) from 1.5 to 2 years-old. Applying systematic observational methodology, spontaneous babies' activity is registered. Double intra and inter-group analysis compare the data from the resolution of a non-verbal task through a multifaceted design. Results obtained show us differential pattern of early executive functioning among the groups studied. The growth of executive functioning is showed, too, through the ages studied for every group.

Association of Combined Patterns of Tobacco and Cannabis Use in Adolescence With Psychotic Experiences

PubMed Central

Gage, Suzanne H.; Heron, Jon; Hickman, Matthew; Lewis, Glyn; Munafò, Marcus R.; Zammit, Stanley

2018-01-01

Importance There is concern about potentially causal effects of tobacco use on psychosis, but epidemiological studies have been less robust in attempts to minimize effects of confounding than studies of cannabis use have been. Objectives To examine the association of patterns of cigarette and cannabis use with preceding and subsequent psychotic experiences, and to compare effects of confounding across these patterns. Design, Setting, and Participants This cohort study used data from the Avon Longitudinal Study of Parents and Children, which initially consisted of 14 062 children. Data were collected periodically from September 6, 1990, with collection ongoing, and analyzed from August 8, 2016, through June 14, 2017. Cigarette and cannabis use data were summarized using longitudinal latent class analysis to identify longitudinal classes of substance use. Associations between classes and psychotic experiences at age 18 years were assessed. Exposures Depending on the analysis model, exposures were longitudinal classes of substance use or psychotic experiences at age 12 years. Main Outcomes and Measures Logistic regression was used to examine the associations between substance use longitudinal classes and subsequent onset of psychotic experiences. Results Longitudinal classes were derived using 5300 participants (56.1% female) who had at least 3 measures of cigarette and cannabis use from ages 14 to 19 years. Prior to adjusting for a range of potential confounders, there was strong evdience that early-onset cigarette-only use (4.3%), early-onset cannabis use (3.2%), and late-onset cannabis use (11.9%) (but not later-onset cigarette-only use [14.8%]) latent classes were associated with increased psychotic experiences compared with nonusers (65.9%) (omnibus P < .001). After adjusting for confounders, the association for early-onset cigarette-only use attenuated substantially (unadjusted odds ratio [OR], 3.03; 95% CI, 1.13-8.14; adjusted OR, 1.78; 95% CI, 0.54-5.88), whereas those for early-onset cannabis use (adjusted OR, 3.70; 95% CI, 1.66-8.25) and late-onset cannabis use (adjusted OR, 2.97; 95% CI, 1.63-5.40) remained consistent. Conclusions and Relevance In this study, our findings indicate that while individuals who use cannabis or cigarettes during adolescence have an increased risk of subsequent psychotic experiences, epidemiological evidence is substantively more robust for cannabis use than it is for tobacco use. PMID:29344610

Longitudinal outcomes after tibioperoneal angioplasty alone compared to tibial stenting and atherectomy for critical limb ischemia.

PubMed

Reynolds, Shaun; Galiñanes, Edgar Luis; Dombrovskiy, Viktor Y; Vogel, Todd R

2013-10-01

There are limited data available evaluating longitudinal outcomes after tibioperoneal angioplasty (TA) alone compared to adjunctive tibial procedures including stenting and atherectomy. Using the Centers for Medicare & Medicaid Services inpatient claims (2005-2007), patients evaluated TA only, TA plus stent placement (TA + S), and TA plus atherectomy (TA + A). A total of 2080 patients with critical limb ischemia underwent percutaneous tibioperoneal intervention for the indication of ulceration. Procedures included TA (56.3%), TA + S (16.2%), and TA + A (27.5%). Rates of amputation were not statistically different between the groups at 30, 90, and 365 days after the intervention. Mean total hospital charges were TA ($35,867), TA + A ($41,698; P = .0004), and TA + S ($51,040; P < .0001). Patients undergoing TA alone compared to concomitant stenting or atherectomy for ulceration demonstrated no improvement in limb salvage. Future analysis of adjunctive tibioperoneal interventions is essential to temper cost, as they fail to improve long-term limb salvage.

Progressive brain changes in children and adolescents with early-onset psychosis: A meta-analysis of longitudinal MRI studies.

PubMed

Fraguas, David; Díaz-Caneja, Covadonga M; Pina-Camacho, Laura; Janssen, Joost; Arango, Celso

2016-06-01

Studies on longitudinal brain volume changes in patients with early-onset psychosis (EOP) are particularly valuable for understanding the neurobiological basis of brain abnormalities associated with psychosis. However, findings have not been consistent across studies in this population. We aimed to conduct a meta-analysis on progressive brain volume changes in children and adolescents with EOP. A systematic literature search of magnetic resonance imaging (MRI) studies comparing longitudinal brain volume changes in children and adolescents with EOP and healthy controls was conducted. The annualized rates of relative change in brain volume by region of interest (ROI) were used as raw data for the meta-analysis. The effect of age, sex, duration of illness, and specific diagnosis on volume change was also evaluated. Five original studies with 156 EOP patients (mean age at baseline MRI in the five studies ranged from 13.3 to 16.6years, 67.31% males) and 163 age- and sex-matched healthy controls, with a mean duration of follow-up of 2.46years (range 2.02-3.40), were included. Frontal gray matter (GM) was the only region in which significant differences in volume change over time were found between patients and controls (Hedges' g -0.435, 95% confidence interval (CI): -0.678 to -0.193, p<0.001). Younger age at baseline MRI was associated with greater loss of temporal GM volume over time in patients as compared with controls (p=0.005). Within patients, a diagnosis of schizophrenia was related to greater occipital GM volume loss over time (p=0.001). Compared with healthy individuals, EOP patients show greater progressive frontal GM loss over the first few years after illness onset. Age at baseline MRI and diagnosis of schizophrenia appear to be significant moderators of particular specific brain volume changes. Copyright © 2014 Elsevier B.V. All rights reserved.

Longitudinal changes in body mass index of children affected by the Great East Japan Earthquake.

PubMed

Zheng, W; Yokomichi, H; Matsubara, H; Ishikuro, M; Kikuya, M; Isojima, T; Yokoya, S; Tanaka, T; Kato, N; Chida, S; Ono, A; Hosoya, M; Tanaka, S; Kuriyama, S; Kure, S; Yamagata, Z

2017-04-01

The evacuation and disruption in housing caused by the 2011 Great East Japan Earthquake and following nuclear radiation may have influenced child health in many respects. However, studies regarding longitudinal childhood growth are limited. Therefore, in this study we aimed to explore the influence of the earthquake on longitudinal changes in body mass index in preschool children. Participants were children from nursery schools who cooperated with the study in the Iwate, Miyagi and Fukushima prefectures. The exposed group consisted of children who experienced the earthquake during their preschool-age period (4-5 years old). The historical control group included children who were born 2 years earlier than the exposed children in the same prefectures. Trajectories regarding body mass index and prevalence of overweight/obesity were compared between the two groups using multilevel analysis. Differences in the changes in BMI between before and after the earthquake, and proportion of overweight/obesity was compared between the two groups. We also conducted subgroup analysis by defining children with specific personal disaster experiences within the exposed group. A total of 9722 children were included in the study. Children in the exposed group had higher body mass indices and a higher proportion of overweight after the earthquake than the control group. These differences were more obvious when confined to exposed children with specific personal disaster experiences. Children's growth and development-related health issues such as increased BMI after natural disasters should evoke great attention.

Identifying reprioritization response shift in a stroke caregiver population: a comparison of missing data methods.

PubMed

Sajobi, Tolulope T; Lix, Lisa M; Singh, Gurbakhshash; Lowerison, Mark; Engbers, Jordan; Mayo, Nancy E

2015-03-01

Response shift (RS) is an important phenomenon that influences the assessment of longitudinal changes in health-related quality of life (HRQOL) studies. Given that RS effects are often small, missing data due to attrition or item non-response can contribute to failure to detect RS effects. Since missing data are often encountered in longitudinal HRQOL data, effective strategies to deal with missing data are important to consider. This study aims to compare different imputation methods on the detection of reprioritization RS in the HRQOL of caregivers of stroke survivors. Data were from a Canadian multi-center longitudinal study of caregivers of stroke survivors over a one-year period. The Stroke Impact Scale physical function score at baseline, with a cutoff of 75, was used to measure patient stroke severity for the reprioritization RS analysis. Mean imputation, likelihood-based expectation-maximization imputation, and multiple imputation methods were compared in test procedures based on changes in relative importance weights to detect RS in SF-36 domains over a 6-month period. Monte Carlo simulation methods were used to compare the statistical powers of relative importance test procedures for detecting RS in incomplete longitudinal data under different missing data mechanisms and imputation methods. Of the 409 caregivers, 15.9 and 31.3 % of them had missing data at baseline and 6 months, respectively. There were no statistically significant changes in relative importance weights on any of the domains when complete-case analysis was adopted. But statistical significant changes were detected on physical functioning and/or vitality domains when mean imputation or EM imputation was adopted. There were also statistically significant changes in relative importance weights for physical functioning, mental health, and vitality domains when multiple imputation method was adopted. Our simulations revealed that relative importance test procedures were least powerful under complete-case analysis method and most powerful when a mean imputation or multiple imputation method was adopted for missing data, regardless of the missing data mechanism and proportion of missing data. Test procedures based on relative importance measures are sensitive to the type and amount of missing data and imputation method. Relative importance test procedures based on mean imputation and multiple imputation are recommended for detecting RS in incomplete data.

Longitudinal Study of Body Mass Index in Young Males and the Transition to Fatherhood

PubMed Central

Garfield, Craig F.; Duncan, Greg; Gutina, Anna; Rutsohn, Joshua; McDade, Thomas W.; Adam, Emma K.; Coley, Rebekah Levine; Chase-Lansdale, P. Lindsay

2017-01-01

Despite a growing understanding that the social determinants of health have an impact on body mass index (BMI), the role of fatherhood on young men’s BMI is understudied. This longitudinal study examines BMI in young men over time as they transition from adolescence into fatherhood in a nationally representative sample. Data from all four waves of the National Longitudinal Study of Adolescent Health supported a 20-year longitudinal analysis of 10,253 men beginning in 1994. A “fatherhood-year” data set was created and changes in BMI were examined based on fatherhood status (nonfather, nonresident father, resident father), fatherhood years, and covariates. Though age is positively associated with BMI over all years for all men, comparing nonresident and resident fathers with nonfathers reveals different trajectories based on fatherhood status. Entrance into fatherhood is associated with an increase in BMI trajectory for both nonresident and resident fathers, while nonfathers exhibit a decrease over the same period. In this longitudinal, population-based study, fatherhood and residence status play a role in men’s BMI. Designing obesity prevention interventions for young men that begin in adolescence and carry through young adulthood should target the distinctive needs of these populations, potentially improving their health outcomes. PMID:26198724

Weight loss in the healthy elderly might be a non-cognitive sign of preclinical Alzheimer's disease.

PubMed

Jimenez, Amanda; Pegueroles, Jordi; Carmona-Iragui, María; Vilaplana, Eduard; Montal, Victor; Alcolea, Daniel; Videla, Laura; Illán-Gala, Ignacio; Pané, Adriana; Casajoana, Anna; Belbin, Olivia; Clarimón, Jordi; Moizé, Violeta; Vidal, Josep; Lleó, Alberto; Fortea, Juan; Blesa, Rafael

2017-12-01

Weight loss has been proposed as a sign of pre-clinical Alzheimer Disease (AD). To test this hypothesis, we have evaluated the association between longitudinal changes in weight trajectories, cognitive performance, AD biomarker profiles and brain structure in 363 healthy controls from the Alzheimer´s Disease Neuroimaging Initiative (mean follow-up 50.5±30.5 months). Subjects were classified according to body weight trajectory into a weight loss group (WLG; relative weight loss ≥ 5%) and a non-weight loss group (non-WLG; relative weight loss < 5%). Linear mixed effects models were used to estimate the effect of body weight changes on ADAS-Cognitive score across time. Baseline CSF tau/AΔ 42 ratio and AV45 PET uptake were compared between WLG and non-WLG by analysis of covariance. Atrophy maps were compared between groups at baseline and longitudinally at a 2-year follow-up using Freesurfer. WLG showed increased baseline levels of cerebrospinal fluid tau/AΔ 42 ratio, increased PET amyloid uptake and diminished cortical thickness at baseline. WLG also showed faster cognitive decline and faster longitudinal atrophy. Our data support weight loss as a non-cognitive manifestation of pre-clinical AD.

Weight loss in the healthy elderly might be a non-cognitive sign of preclinical Alzheimer's disease

PubMed Central

Carmona-Iragui, María; Vilaplana, Eduard; Montal, Victor; Alcolea, Daniel; Videla, Laura; Illán-Gala, Ignacio; Pané, Adriana; Casajoana, Anna; Belbin, Olivia; Clarimón, Jordi; Moizé, Violeta; Vidal, Josep; Lleó, Alberto; Fortea, Juan; Blesa, Rafael

2017-01-01

Weight loss has been proposed as a sign of pre-clinical Alzheimer Disease (AD). To test this hypothesis, we have evaluated the association between longitudinal changes in weight trajectories, cognitive performance, AD biomarker profiles and brain structure in 363 healthy controls from the Alzheimer´s Disease Neuroimaging Initiative (mean follow-up 50.5±30.5 months). Subjects were classified according to body weight trajectory into a weight loss group (WLG; relative weight loss ≥ 5%) and a non-weight loss group (non-WLG; relative weight loss < 5%). Linear mixed effects models were used to estimate the effect of body weight changes on ADAS-Cognitive score across time. Baseline CSF tau/AΔ42 ratio and AV45 PET uptake were compared between WLG and non-WLG by analysis of covariance. Atrophy maps were compared between groups at baseline and longitudinally at a 2-year follow-up using Freesurfer. WLG showed increased baseline levels of cerebrospinal fluid tau/AΔ42 ratio, increased PET amyloid uptake and diminished cortical thickness at baseline. WLG also showed faster cognitive decline and faster longitudinal atrophy. Our data support weight loss as a non-cognitive manifestation of pre-clinical AD. PMID:29285207

Two-dimensional speckle-tracking strain echocardiography in long-term heart transplant patients: a study comparing deformation parameters and ejection fraction derived from echocardiography and multislice computed tomography.

PubMed

Syeda, Bonni; Höfer, Peter; Pichler, Philipp; Vertesich, Markus; Bergler-Klein, Jutta; Roedler, Susanne; Mahr, Stephane; Goliasch, Georg; Zuckermann, Andreas; Binder, Thomas

2011-07-01

Longitudinal strain determined by speckle tracking is a sensitive parameter to detect systolic left ventricular dysfunction. In this study, we assessed regional and global longitudinal strain values in long-term heart transplants and compared deformation indices with ejection fraction as determined by transthoracic echocardiography (TTE) and multislice computed tomographic coronary angiography (MSCTA). TTE and MSCTA were prospectively performed in 31 transplant patients (10.6 years post-transplantation) and in 42 control subjects. Grey-scale apical views were recorded for speckle tracking (EchoPAC 7.0, GE) of the 16 segments of the left ventricle. The presence of coronary artery disease (CAD) was assessed by MSCTA. Strain analysis was performed in 1168 segments [496 in transplant patients (42.5%), 672 in control subjects (57.7%)]. Global longitudinal peak systolic strain was significantly lower in the transplant recipients than in the healthy population (-13.9 ± 4.2 vs. -17.4 ± 5.8%, P< 0.01). This was still the case after exclusion of the nine transplant patients with CAD (-14.1 ± 4.4 vs. -17.4 ± 5.8%, P=0.03). Transplant patients exhibited significantly lower regional strain values in 9 of the 16 segments. Left ventricular ejection fraction (%) (MSCTA/Simpsons method) was 60.7 ± 10.1%/60.2 ± 6.7% in transplant recipients vs. 64.7 ± 6.4%/63.0 ± 6.2% in the healthy population, P=ns. Even though 'healthy' heart transplants without CAD exhibit normal ejection fraction, deformation indices are reduced in this population when compared with control subjects. Our findings suggests that strain analysis is more sensitive than assessment of ejection fraction for the detection of abnormalities of systolic function.

Bipolar mood state reflected in cortico-amygdala resting state connectivity: A cohort and longitudinal study.

PubMed

Brady, Roscoe O; Margolis, Allison; Masters, Grace A; Keshavan, Matcheri; Öngür, Dost

2017-08-01

Using resting-state functional magnetic resonance imaging (rsfMRI), we previously compared cohorts of bipolar I subjects in a manic state to those in a euthymic state to identify mood state-specific patterns of cortico-amygdala connectivity. Our results suggested that mania is reflected in the disruption of emotion regulation circuits. We sought to replicate this finding in a group of subjects with bipolar disorder imaged longitudinally across states of mania and euthymia METHODS: We divided our subjects into three groups: 26 subjects imaged in a manic state, 21 subjects imaged in a euthymic state, and 10 subjects imaged longitudinally across both mood states. We measured differences in amygdala connectivity between the mania and euthymia cohorts. We then used these regions of altered connectivity to examine connectivity in the longitudinal bipolar group using a within-subjects design. Our findings in the mania vs euthymia cohort comparison were replicated in the longitudinal analysis. Bipolar mania was differentiated from euthymia by decreased connectivity between the amygdala and pre-genual anterior cingulate cortex. Mania was also characterized by increased connectivity between amygdala and the supplemental motor area, a region normally anti-correlated to the amygdala in emotion regulation tasks. Stringent controls for movement effects limited the number of subjects in the longitudinal sample. In this first report of rsfMRI conducted longitudinally across mood states, we find that previously observed between-group differences in amygdala connectivity are also found longitudinally within subjects. These results suggest resting state cortico-amygdala connectivity is a biomarker of mood state in bipolar disorder. Copyright © 2017 Elsevier B.V. All rights reserved.

Reference tissue normalization in longitudinal (18)F-florbetapir positron emission tomography of late mild cognitive impairment.

PubMed

Shokouhi, Sepideh; Mckay, John W; Baker, Suzanne L; Kang, Hakmook; Brill, Aaron B; Gwirtsman, Harry E; Riddle, William R; Claassen, Daniel O; Rogers, Baxter P

2016-01-15

Semiquantitative methods such as the standardized uptake value ratio (SUVR) require normalization of the radiotracer activity to a reference tissue to monitor changes in the accumulation of amyloid-β (Aβ) plaques measured with positron emission tomography (PET). The objective of this study was to evaluate the effect of reference tissue normalization in a test-retest (18)F-florbetapir SUVR study using cerebellar gray matter, white matter (two different segmentation masks), brainstem, and corpus callosum as reference regions. We calculated the correlation between (18)F-florbetapir PET and concurrent cerebrospinal fluid (CSF) Aβ1-42 levels in a late mild cognitive impairment cohort with longitudinal PET and CSF data over the course of 2 years. In addition to conventional SUVR analysis using mean and median values of normalized brain radiotracer activity, we investigated a new image analysis technique-the weighted two-point correlation function (wS2)-to capture potentially more subtle changes in Aβ-PET data. Compared with the SUVRs normalized to cerebellar gray matter, all cerebral-to-white matter normalization schemes resulted in a higher inverse correlation between PET and CSF Aβ1-42, while the brainstem normalization gave the best results (high and most stable correlation). Compared with the SUVR mean and median values, the wS2 values were associated with the lowest coefficient of variation and highest inverse correlation to CSF Aβ1-42 levels across all time points and reference regions, including the cerebellar gray matter. The selection of reference tissue for normalization and the choice of image analysis method can affect changes in cortical (18)F-florbetapir uptake in longitudinal studies.

Temporal Patterns of Variable Relationships in Person-Oriented Research: Longitudinal Models of Configural Frequency Analysis

ERIC Educational Resources Information Center

von Eye, Alexander; Mun, Eun Young; Bogat, G. Anne

2008-01-01

This article reviews the premises of configural frequency analysis (CFA), including methods of choosing significance tests and base models, as well as protecting [alpha], and discusses why CFA is a useful approach when conducting longitudinal person-oriented research. CFA operates at the manifest variable level. Longitudinal CFA seeks to identify…

The balanced survivor average causal effect.

PubMed

Greene, Tom; Joffe, Marshall; Hu, Bo; Li, Liang; Boucher, Ken

2013-05-07

Statistical analysis of longitudinal outcomes is often complicated by the absence of observable values in patients who die prior to their scheduled measurement. In such cases, the longitudinal data are said to be "truncated by death" to emphasize that the longitudinal measurements are not simply missing, but are undefined after death. Recently, the truncation by death problem has been investigated using the framework of principal stratification to define the target estimand as the survivor average causal effect (SACE), which in the context of a two-group randomized clinical trial is the mean difference in the longitudinal outcome between the treatment and control groups for the principal stratum of always-survivors. The SACE is not identified without untestable assumptions. These assumptions have often been formulated in terms of a monotonicity constraint requiring that the treatment does not reduce survival in any patient, in conjunction with assumed values for mean differences in the longitudinal outcome between certain principal strata. In this paper, we introduce an alternative estimand, the balanced-SACE, which is defined as the average causal effect on the longitudinal outcome in a particular subset of the always-survivors that is balanced with respect to the potential survival times under the treatment and control. We propose a simple estimator of the balanced-SACE that compares the longitudinal outcomes between equivalent fractions of the longest surviving patients between the treatment and control groups and does not require a monotonicity assumption. We provide expressions for the large sample bias of the estimator, along with sensitivity analyses and strategies to minimize this bias. We consider statistical inference under a bootstrap resampling procedure.

Longitudinal changes and correlations of bioimpedance and anthropometric measurements in pregnancy: Simple possible bed-side tools to assess pregnancy evolution.

PubMed

Piuri, Gabriele; Ferrazzi, Enrico; Bulfoni, Camilla; Mastricci, Luciana; Di Martino, Daniela; Speciani, Attilio Francesco

2017-12-01

The aim of this study was to assess longitudinal changes of bioimpedance analysis compared with anthropometric measurements in low-risk pregnant woman recruited in the first trimester and to observe possible differences in these indices in women who developed high-risk pregnancies. Bioimpedance indices for the three trimesters of pregnancies were calculated separately for uneventful pregnancies delivered of newborns > the 10th centile. These findings were compared with anthropometric measurements. Data of women who developed hypertensive disorders of pregnancy (HDP) or delivered SGA newborns were calculated and compared. Significantly longitudinal increases were observed in these pregnancies for total body water (TBW), free fat mass, fat mass, and extra-cellular water. These increases were paralleled body mass index (BMI), skinfolds, and waist measurements. The correlations between these two sets of findings were poor. Women who developed HDP with AGA fetuses showed significantly different bioimpedance from normal cases. TBW indices were highly significantly different since the first trimester. In pregnancies delivered of SGA newborns, these indices were opposite of the values observed in patients with HDP-AGA, TBW in these patients was significantly reduced compared with normal pregnancies. The bioelectrical impedance is a fast, simple, noninvasive way to assess the TBW content in pregnancy. Our findings are in agreement with the hypothesis that bioimpedance might help to identify early in gestation patients at risk of developing different clinical phenotypes of hypertensive disease of pregnancy and SGA fetuses.

Element free Galerkin formulation of composite beam with longitudinal slip

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Dzulkarnain; Mokhtaram, Mokhtazul Haizad; Badli, Mohd Iqbal

2015-05-15

Behaviour between two materials in composite beam is assumed partially interact when longitudinal slip at its interfacial surfaces is considered. Commonly analysed by the mesh-based formulation, this study used meshless formulation known as Element Free Galerkin (EFG) method in the beam partial interaction analysis, numerically. As meshless formulation implies that the problem domain is discretised only by nodes, the EFG method is based on Moving Least Square (MLS) approach for shape functions formulation with its weak form is developed using variational method. The essential boundary conditions are enforced by Langrange multipliers. The proposed EFG formulation gives comparable results, after beenmore » verified by analytical solution, thus signify its application in partial interaction problems. Based on numerical test results, the Cubic Spline and Quartic Spline weight functions yield better accuracy for the EFG formulation, compares to other proposed weight functions.« less

Healthy brain connectivity predicts atrophy progression in non-fluent variant of primary progressive aphasia.

PubMed

Mandelli, Maria Luisa; Vilaplana, Eduard; Brown, Jesse A; Hubbard, H Isabel; Binney, Richard J; Attygalle, Suneth; Santos-Santos, Miguel A; Miller, Zachary A; Pakvasa, Mikhail; Henry, Maya L; Rosen, Howard J; Henry, Roland G; Rabinovici, Gil D; Miller, Bruce L; Seeley, William W; Gorno-Tempini, Maria Luisa

2016-10-01

Neurodegeneration has been hypothesized to follow predetermined large-scale networks through the trans-synaptic spread of toxic proteins from a syndrome-specific epicentre. To date, no longitudinal neuroimaging study has tested this hypothesis in vivo in frontotemporal dementia spectrum disorders. The aim of this study was to demonstrate that longitudinal progression of atrophy in non-fluent/agrammatic variant primary progressive aphasia spreads over time from a syndrome-specific epicentre to additional regions, based on their connectivity to the epicentre in healthy control subjects. The syndrome-specific epicentre of the non-fluent/agrammatic variant of primary progressive aphasia was derived in a group of 10 mildly affected patients (clinical dementia rating equal to 0) using voxel-based morphometry. From this region, the inferior frontal gyrus (pars opercularis), we derived functional and structural connectivity maps in healthy controls (n = 30) using functional magnetic resonance imaging at rest and diffusion-weighted imaging tractography. Graph theory analysis was applied to derive functional network features. Atrophy progression was calculated using voxel-based morphometry longitudinal analysis on 34 non-fluent/agrammatic patients. Correlation analyses were performed to compare volume changes in patients with connectivity measures of the healthy functional and structural speech/language network. The default mode network was used as a control network. From the epicentre, the healthy functional connectivity network included the left supplementary motor area and the prefrontal, inferior parietal and temporal regions, which were connected through the aslant, superior longitudinal and arcuate fasciculi. Longitudinal grey and white matter changes were found in the left language-related regions and in the right inferior frontal gyrus. Functional connectivity strength in the healthy speech/language network, but not in the default network, correlated with longitudinal grey matter changes in the non-fluent/agrammatic variant of primary progressive aphasia. Graph theoretical analysis of the speech/language network showed that regions with shorter functional paths to the epicentre exhibited greater longitudinal atrophy. The network contained three modules, including a left inferior frontal gyrus/supplementary motor area, which was most strongly connected with the epicentre. The aslant tract was the white matter pathway connecting these two regions and showed the most significant correlation between fractional anisotropy and white matter longitudinal atrophy changes. This study showed that the pattern of longitudinal atrophy progression in the non-fluent/agrammatic variant of primary progressive aphasia relates to the strength of connectivity in pre-determined functional and structural large-scale speech production networks. These findings support the hypothesis that the spread of neurodegeneration occurs by following specific anatomical and functional neuronal network architectures. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Incidence and rates of visual field progression after longitudinally measured optic disc change in glaucoma.

PubMed

Chauhan, Balwantray C; Nicolela, Marcelo T; Artes, Paul H

2009-11-01

To determine whether glaucoma patients with progressive optic disc change have subsequent visual field progression earlier and at a faster rate compared with those without disc change. Prospective, longitudinal, cohort study. Eighty-one patients with open-angle glaucoma. Patients underwent confocal scanning laser tomography and standard automated perimetry every 6 months. The complete follow-up was divided into initial and subsequent periods. Two initial periods-first 3 years (Protocol A) and first half of the total follow-up (Protocol B)-were used, with the respective remainder being the subsequent follow-up. Disc change during the initial follow-up was determined with liberal, moderate, or conservative criteria of the Topographic Change Analysis. Subsequent field progression was determined with significant pattern deviation change in >or=3 locations (criterion used in the Early Manifest Glaucoma Trial). As a control analysis, field change during the initial follow-up was determined with significant pattern deviation change in >or=1, >or=2, or >or=3 locations. Survival time to subsequent field progression, rates of mean deviation (MD) change, and positive and negative likelihood ratios. The median (interquartile range) total follow-up was 11.0 (8.0-12.0) years with 22 (18-24) examinations. More patients had disc changes during the initial follow-up compared with field changes. The mean time to field progression was consistently shorter (protocol A, 0.8-1.7 years; protocol B, 0.3-0.7 years) in patients with prior disc change. In the control analysis, patients with prior field change had statistically earlier subsequent field progression (protocol A, 2.9-3.0 years; protocol B, 0.7-0.9). Similarly, patients with either prior disc or field change always had worse mean rates of subsequent MD change, although the distributions overlapped widely. Patients with subsequent field progression were up to 3 times more likely to have prior disc change compared with those without, and up to 5 times more likely to have prior field change compared with those without. Longitudinally measured optic disc change is predictive of subsequent visual field progression and may be an efficacious end point for functional outcomes in clinical studies and trials in glaucoma.

An analysis of the effects of aeroelasticity on static longitudinal stability and control of a swept-wing airplane

NASA Technical Reports Server (NTRS)

Skoog, Richard B

1957-01-01

A theoretical analysis has been made of the effects of aeroelasticity on the static longitudinal stability and elevator angle required for balance of an airplane. The analysis is based on the familiar stability equation expressing the contribution of wing and tail to longitudinal stability. Effects of wing, tail, and fuselage flexibility are considered. Calculated effects are shown for a swept-wing bomber of relatively high flexibility.

Heat Transfer to Longitudinal Laminar Flow Between Cylinders

NASA Technical Reports Server (NTRS)

Sparrow, Ephraim M.; Loeffler, Albert L. Jr.; Hubbard, H. A.

1960-01-01

Consideration is given to the fully developed heat transfer characteristics for longitudinal laminar flow between cylinders arranged in an equilateral triangular array. The analysis is carried out for the condition of uniform heat transfer per unit length. Solutions are obtained for the temperature distribution, and from these, Nusselt numbers are derived for a wide range of spacing-to-diameter ratios. It is found that as the spacing ratio increases, so also does the wall-to-bulk temperature difference for a fixed heat transfer per unit length. Corresponding to a uniform surface temperature around the circumference of a cylinder, the circumferential variation of the local heat flux is computed. For spacing ratios of 1.5 - 2.0 and greater, uniform peripheral wall temperature and uniform peripheral heat flux are simultaneously achieved. A simplified analysis which neglects circumferential variations is also carried out, and the results are compared with those from the more exact formulation.

Tract specific analysis in patients with sickle cell disease

NASA Astrophysics Data System (ADS)

Chai, Yaqiong; Coloigner, Julie; Qu, Xiaoping; Choi, Soyoung; Bush, Adam; Borzage, Matt; Vu, Chau; Lepore, Natasha; Wood, John

2015-12-01

Sickle cell disease (SCD) is a hereditary blood disorder in which the oxygen-carrying hemoglobin molecule in red blood cells is abnormal. It affects numerous people in the world and leads to a shorter life span, pain, anemia, serious infections and neurocognitive decline. Tract-Specific Analysis (TSA) is a statistical method to evaluate white matter alterations due to neurocognitive diseases, using diffusion tensor magnetic resonance images. Here, for the first time, TSA is used to compare 11 major brain white matter (WM) tracts between SCD patients and age-matched healthy subjects. Alterations are found in the corpus callosum (CC), the cortico-spinal tract (CST), inferior fronto-occipital fasciculus (IFO), inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus (SLF), and uncinated fasciculus (UNC). Based on previous studies on the neurocognitive functions of these tracts, the significant areas found in this paper might be related to several cognitive impairments and depression, both of which are observed in SCD patients.

Changing Attitudes Toward Euthanasia and Suicide for Terminally Ill Persons, 1977 to 2016: An Age-Period-Cohort Analysis.

PubMed

Attell, Brandon K

2017-01-01

Several longitudinal studies show that over time the American public has become more approving of euthanasia and suicide for terminally ill persons. Yet, these previous findings are limited because they derive from biased estimates of disaggregated hierarchical data. Using insights from life course sociological theory and cross-classified logistic regression models, I better account for this liberalization process by disentangling the age, period, and cohort effects that contribute to longitudinal changes in these attitudes. The results of the analysis point toward a continued liberalization of both attitudes over time, although the magnitude of change was greater for suicide compared with euthanasia. More fluctuation in the probability of supporting both measures was exhibited for the age and period effects over the cohort effects. In addition, age-based differences in supporting both measures were found between men and women and various religious affiliations.

Supersonic full-potential methods for missile body analysis

NASA Technical Reports Server (NTRS)

Pittman, James L.

1992-01-01

Accounts are presented of representative applications to missile bodies of arbitrary shape of methods based on the steady form of the full potential equation. The NCOREL and SIMP full-potential codes are compared, and their results are evaluated for the cases of an arrow wing and a wing-body configuration. Attention is given to the effect of cross-sectional and longitudinal geometries. Comparisons of surface pressure and longitudinal force and moment data for circular and elliptic bodies have shown that the full-potential methods yielded excellent results in attached-flow conditions. Results are presented for a conical star body, waveriders, the Shuttle Orbiter, and a highly swept wing-body cruising at Mach 4.

Photoelastic Analysis of Cracked Thick Walled Cylinders

NASA Astrophysics Data System (ADS)

Pastramă, Ştefan Dan

2017-12-01

In this paper, the experimental determination of the stress intensity factor in thick walled cylinders subject to uniform internal pressure and having longitudinal non-penetrating cracks is presented. Photoelastic measurements were used together with the expressions of the stress field near the crack tip for Mode I crack extension and a specific methodology for stress intensity factor determination. Two types of longitudinal cracks - internal and external - were considered. Four plane models were manufactured and analyzed in a plane polariscope at different values of the applied internal pressure. The values of the normalized stress intensity factor were calculated and the results were compared to those reported by other authors. A good accuracy was noticed, showing the reliability of the experimental procedure.

Longitudinal Analysis of Superficial Midfacial Fat Volumes Over a 10-Year Period.

PubMed

Tower, Jacob; Seifert, Kimberly; Paskhover, Boris

2018-04-11

Volumetric changes to facial fat that occur with aging remain poorly understood. The aim of this study was to evaluate for longitudinal changes to midfacial fat volumes in a group of individuals. We conducted a retrospective longitudinal study of adult subjects who underwent multiple facial computed tomographic (CT) scans timed at least 8 years apart. Subjects who underwent facial surgery or suffered facial trauma were excluded. Facial CT scans were analyzed, and superficial cheek fat volumes were measured and compared to track changes that occurred with aging. Fourteen subjects were included in our analysis of facial aging (5 male, 9 female; mean initial age 50.9 years; mean final age 60.4 years). In the right superficial cheek there was an increase in mean (SD) superficial fat volume from 10.33 (2.01) to 10.50 (1.80) cc, which was not statistically significant (P = 0.75). Similar results were observed in the left cheek. There were no statistically significant longitudinal changes to caudal, middle, or cephalad subdivisions of bilateral superficial cheek fat. A simple linear regression was performed to predict superficial cheek fat pad volume based on age which did not reach statistical significance (P = 0.31), with an R 2 of 0.039. This study is the first to quantitatively assess for longitudinal changes to midfacial fat in a group of individuals. Superficial cheek fat remained stable as subjects aged from approximately 50 to 60 years old, with no change in total volume or redistribution within a radiographically defined compartment. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Relationship Between Urban Sprawl and Weight of United States Youth

PubMed Central

Ewing, Reid; Brownson, Ross C.; Berrigan, David

2007-01-01

Background Among United States youth there is an obesity epidemic with potential lifelong health implications. To date, relationships between the built environment and body mass index (BMI) have not been evaluated for youth, and have not been evaluated longitudinally. Objective To determine if urban sprawl is associated with BMI for U.S. youth. Method Using data from the 1997 National Longitudinal Survey of Youth (NLSY97), both cross-sectional and longitudinal analyses were conducted. Hierarchical modeling was used to relate characteristics of individuals, households, and places to BMI. Individual and household data were extracted from the NLSY97. The independent variable of interest was the county sprawl index, which was derived with principal components analyses from census and other data. Results In a cross-sectional analysis, the likelihood of U.S. adolescents (aged 12–17 years) being overweight or at risk of overweight (≥85th percentile relative to the Centers for Disease Control [CDC] growth charts) was associated with county sprawl (p=0.022). In another cross-sectional analysis, after controlling for sociodemographic and behavioral covariates, the likelihood of young adults (aged 18–23 years) being obese was also associated with county sprawl (p=0.048). By contrast, in longitudinal analyses, BMI growth curves for individual youth over the 7 years of NLSY97, and BMI changes for individual youth who moved between counties, were not related to county sprawl (although coefficient signs were as expected). Conclusions Cross-sectional analyses suggest that urban form is associated with overweight among U.S. youth. The strength of these relationships proved comparable to those previously reported for adults. Longitudinal analyses show no such relationship. It is unclear why these approaches give different results, but sample sizes, latent effects, and confounders may contribute. PMID:17169708

Relationship between urban sprawl and weight of United States youth.

PubMed

Ewing, Reid; Brownson, Ross C; Berrigan, David

2006-12-01

Among United States youth there is an obesity epidemic with potential life-long health implications. To date, relationships between the built environment and body mass index (BMI) have not been evaluated for youth, and have not been evaluated longitudinally. To determine if urban sprawl is associated with BMI for U.S. youth. Using data from the 1997 National Longitudinal Survey of Youth (NLSY97), both cross-sectional and longitudinal analyses were conducted. Hierarchical modeling was used to relate characteristics of individuals, households, and places to BMI. Individual and household data were extracted from the NLSY97. The independent variable of interest was the county sprawl index, which was derived with principal components analyses from census and other data. In a cross-sectional analysis, the likelihood of U.S. adolescents (aged 12-17 years) being overweight or at risk of overweight (> or =85th percentile relative to the Centers for Disease Control growth charts) was associated with county sprawl (p=0.022). In another cross-sectional analysis, after controlling for sociodemographic and behavioral covariates, the likelihood of young adults (aged 18-23 years) being obese was also associated with county sprawl (p=0.048). By contrast, in longitudinal analyses, BMI growth curves for individual youth over the 7 years of NLSY97, and BMI changes for individual youth who moved between counties, were not related to county sprawl (although coefficient signs were as expected). Cross-sectional analyses suggest that urban form is associated with being overweight among U.S. youth. The strength of these relationships proved comparable to those previously reported for adults. Longitudinal analyses show no such relationship. It is unclear why these approaches give different results, but sample sizes, latent effects, and confounders may contribute.

Method for Studying Helicopter Longitudinal Maneuver Stability

NASA Technical Reports Server (NTRS)

Amer, Kenneth B

1954-01-01

A theoretical analysis of helicopter maneuver stability is made and the results are compared with experimental results for both a single and a tandem rotor helicopter. Techniques are described for measuring in flight the significant stability derivatives for use with the theory to aid in design studies of means for achieving marginal maneuver stability for a prototype helicopter.

Expectations versus Reality: The Case of Liberal Studies in Hong Kong's New Senior Secondary Reforms

ERIC Educational Resources Information Center

Fung, Dennis

2016-01-01

This article reports the findings of a five-year longitudinal study investigating the introduction of Liberal Studies in the context of Hong Kong's new senior secondary educational reforms. The aim of this empirical research, which adopted diachronic analysis to allow comparisons over time, was to compare teachers' and students' perceptions of the…

The Health of Caregiving Grandmothers: A Rural-Urban Comparison

ERIC Educational Resources Information Center

Bigbee, Jeri L.; Musil, Carol; Kenski, Diane

2011-01-01

Purpose: The purpose of this study was to compare the characteristics of rural versus urban caregiving grandmothers along with their physical and mental health status. Methods: A secondary analysis of data produced from the first wave of a longitudinal study of 485 Ohio grandmothers was conducted. Health status was measured using the SF-36 Health…

Analysis of Subsequent Educational Decisions of High School Dropouts and Their Life Outcomes.

ERIC Educational Resources Information Center

Chan, Chi-Keung; Kato, Kentaro; Davenport, Ernest C., Jr.; Guven, Kamil

This study used data for a representative sample of 8th graders from the National Educational Longitudinal Study of 1988. The intent was to (1) compare student's dropout status with variables such as demographics, academic and economic factors, limited English proficiency status, and other risk factors of dropping out, (2) distinguish factors…

The Economic Consequences of the Dissolution of Cohabiting Unions

ERIC Educational Resources Information Center

Avellar, Sarah; Smock, Pamela J.

2005-01-01

Although the economic effects of divorce have been well studied, a similar exploration of cohabitation has not been conducted. For this analysis, we use a sample from the National Longitudinal Survey of Youth (N=2,372) documenting changes in economic well-being at the end of a cohabiting relationship and comparing these results to a sample of…

An evaluation of intraoperative and postoperative outcomes of torsional mode versus longitudinal ultrasound mode phacoemulsification: a Meta-analysis.

PubMed

Leon, Pia; Umari, Ingrid; Mangogna, Alessandro; Zanei, Andrea; Tognetto, Daniele

2016-01-01

To evaluate and compare the intraoperative parameters and postoperative outcomes of torsional mode and longitudinal mode of phacoemulsification. Pertinent studies were identified by a computerized MEDLINE search from January 2002 to September 2013. The Meta-analysis is composed of two parts. In the first part the intraoperative parameters were considered: ultrasound time (UST) and cumulative dissipated energy (CDE). The intraoperative values were also distinctly considered for two categories (moderate and hard cataract group) depending on the nuclear opacity grade. In the second part of the study the postoperative outcomes as the best corrected visual acuity (BCVA) and the endothelial cell loss (ECL) were taken in consideration. The UST and CDE values proved statistically significant in support of torsional mode for both moderate and hard cataract group. The analysis of BCVA did not present statistically significant difference between the two surgical modalities. The ECL count was statistically significant in support of torsional mode (P<0.001). The Meta-analysis shows the superiority of the torsional mode for intraoperative parameters (UST, CDE) and postoperative ECL outcomes.

An evaluation of intraoperative and postoperative outcomes of torsional mode versus longitudinal ultrasound mode phacoemulsification: a Meta-analysis

PubMed Central

Leon, Pia; Umari, Ingrid; Mangogna, Alessandro; Zanei, Andrea; Tognetto, Daniele

2016-01-01

AIM To evaluate and compare the intraoperative parameters and postoperative outcomes of torsional mode and longitudinal mode of phacoemulsification. METHODS Pertinent studies were identified by a computerized MEDLINE search from January 2002 to September 2013. The Meta-analysis is composed of two parts. In the first part the intraoperative parameters were considered: ultrasound time (UST) and cumulative dissipated energy (CDE). The intraoperative values were also distinctly considered for two categories (moderate and hard cataract group) depending on the nuclear opacity grade. In the second part of the study the postoperative outcomes as the best corrected visual acuity (BCVA) and the endothelial cell loss (ECL) were taken in consideration. RESULTS The UST and CDE values proved statistically significant in support of torsional mode for both moderate and hard cataract group. The analysis of BCVA did not present statistically significant difference between the two surgical modalities. The ECL count was statistically significant in support of torsional mode (P<0.001). CONCLUSION The Meta-analysis shows the superiority of the torsional mode for intraoperative parameters (UST, CDE) and postoperative ECL outcomes. PMID:27366694

Effectiveness of diffusion tensor imaging in differentiating early-stage subcortical ischemic vascular disease, Alzheimer's disease and normal ageing.

PubMed

Tu, Min-Chien; Lo, Chung-Ping; Huang, Ching-Feng; Hsu, Yen-Hsuan; Huang, Wen-Hui; Deng, Jie Fu; Lee, Yung-Chuan

2017-01-01

To describe and compare diffusion tensor imaging (DTI) parameters between patients with subcortical ischemic vascular disease (SIVD) and Alzheimer's disease (AD) diagnosed using structuralized neuropsychiatric assessments, and investigate potential neuronal substrates related to cognitive performance. Thirty-five patients with SIVD, 40 patients with AD, and 33 cognitively normal control (NC) subjects matched by age and education level were consecutively recruited and underwent cognitive function assessments and DTI examinations. Comparisons among these three subgroups with regards to cognitive performance and DTI parameters including fractional anisotropy (FA) and mean diffusivity (MD) values were performed. Partial correlation analysis after controlling for age and education was used to evaluate associations between cognitive performance and DTI parameters. With regards to cognitive performance, the patients with SIVD had lower total scores in frontal assessment battery (FAB) compared to those with AD (p < 0.05) in the context of comparable Mini-Mental Status Examination and Cognitive Abilities Screening Instrument scores. With regards to DTI parameters, there were more regions of significant differences in FA among these three subgroups compared with MD. Compared with NC group, the patients with SIVD had significant global reductions in FA (p < 0.001 ~ 0.05), while significant reductions in FA among the patients with AD were regionally confined within the left superior longitudinal fasciculus, genu and splenium of the corpus callosum, and bilateral forceps major, and the anterior thalamic radiation, uncinate fasciculus, and cingulum of the left side (p < 0.01 ~ 0.05). Analysis of FA values within the left forceps major, left anterior thalamic radiation, and genu of the corpus callosum revealed a 71.8% overall correct classification (p < 0.001) with sensitivity of 69.4%, specificity of 73.8%, positive predictive value of 69.4%, and negative predictive value of 73.8% in discriminating patients with SIVD from those with AD. In combined analysis of the patients with SIVD and AD (n = 75), the total FAB score was positively correlated with FA within the bilateral forceps minor, genu of the corpus callosum, left forceps major, left uncinate fasciculus, and right inferior longitudinal fasciculus (p = 0.001 ~ 0.038), and inversely correlated with MD within the right superior longitudinal fasciculus, genu and body of the corpus callosum, bilateral forceps minor, right uncinate fasciculus, and right inferior longitudinal fasciculus (p = 0.003 ~ 0.040). Our findings suggest the effectiveness of DTI measurements in distinguishing patients with early-stage AD from those with SIVD, with discernible changes in spatial distribution and magnitude of significance of the DTI parameters. Strategic FA assessments provided the most robust discriminative power to differentiate SIVD from AD, and FAB may serve as an additional cognitive marker. We also identified the neuronal substrates responsible for FAB performance.

Methodological issues in volumetric magnetic resonance imaging of the brain in the Edinburgh High Risk Project.

PubMed

Whalley, H C; Kestelman, J N; Rimmington, J E; Kelso, A; Abukmeil, S S; Best, J J; Johnstone, E C; Lawrie, S M

1999-07-30

The Edinburgh High Risk Project is a longitudinal study of brain structure (and function) in subjects at high risk of developing schizophrenia in the next 5-10 years for genetic reasons. In this article we describe the methods of volumetric analysis of structural magnetic resonance images used in the study. We also consider potential sources of error in these methods: the validity of our image analysis techniques; inter- and intra-rater reliability; possible positional variation; and thresholding criteria used in separating brain from cerebro-spinal fluid (CSF). Investigation with a phantom test object (of similar imaging characteristics to the brain) provided evidence for the validity of our image acquisition and analysis techniques. Both inter- and intra-rater reliability were found to be good in whole brain measures but less so for smaller regions. There were no statistically significant differences in positioning across the three study groups (patients with schizophrenia, high risk subjects and normal volunteers). A new technique for thresholding MRI scans longitudinally is described (the 'rescale' method) and compared with our established method (thresholding by eye). Few differences between the two techniques were seen at 3- and 6-month follow-up. These findings demonstrate the validity and reliability of the structural MRI analysis techniques used in the Edinburgh High Risk Project, and highlight methodological issues of general concern in cross-sectional and longitudinal studies of brain structure in healthy control subjects and neuropsychiatric populations.

Hollow-cylinder waveguide isolators for use at millimeter wavelengths

NASA Technical Reports Server (NTRS)

Kanda, M.; May, W. G.

1974-01-01

The device considered in this study is a semiconductor waveguide isolator consisting of a hollow column of a semiconductor mounted coaxially in a circular waveguide in a longitudinal dc magnetic field. An elementary and physical analysis based on the excitation of plane waves in the guide and a more rigorous mode-matching analysis (MMA) are presented. These theoretical predictions are compared with experimental results for an InSb isolator at 94 GHz and 75 K.

Methodological issues underlying multiple decrement life table analysis.

PubMed

Mode, C J; Avery, R C; Littman, G S; Potter, R G

1977-02-01

In this paper, the actuarial method of multiple decrement life table analysis of censored, longitudinal data is examined. The discussion is organized in terms of the first segment of usage of an intrauterine device. Weaknesses of the actuarial approach are pointed out, and an alternative approach, based on the classical model of competing risks, is proposed. Finally, the actuarial and the alternative method of analyzing censored data are compared, using data from the Taichung Medical Study on Intrauterine Devices.

Mild thyroid hormone excess is associated with a decreased physical function in elderly men

PubMed Central

Ceresini, Graziano; Ceda, Gian Paolo; Lauretani, Fulvio; Maggio, Marcello; Bandinelli, Stefania; Guralnik, Jack M.; Cappola, Anne R.; Usberti, Elisa; Morganti, Simonetta; Valenti, Giorgio; Ferrucci, Luigi

2015-01-01

Introduction In the adult, subclinical hyperthyroidism (Shyper) may alter skeletal muscle mass and strength. However, whether these effects are present in elderly subjects is not known. We explored the relationship between mild hyperthyroidism and physical function in a population-based sample of older persons. Methods In a cross-sectional analysis, calf muscle cross-sectional area (CMA), handgrip strength, nerve conduction velocity (NCV), and Short Physical Performance Battery (SPPB) scores were compared between 364 euthyroid (Eut) and 28 Shyper men as well as between 502 Eut and 39 Shyper women. In a longitudinal analysis, we evaluated the relationship between baseline plasma TSH, FT3 and FT4 and the 3-year change in SPPB score in 304 men and 409 women who were euthyroid at enrolment. Results At the cross-sectional analysis, Shyper men, but not women, had a significantly (p = 0.02) lower SPPB score than Eut controls, although with comparable CMA, grip strength and NCV, and were more likely to have poor physical performance (odds ratio = 2.97, p< 0.05). Longitudinal analysis showed that in Eut men higher baseline FT4 was significantly (p=0.02) predictive of a lower SPPB score at the 3-year follow-up. Conclusion Even a modest thyroid hormone excess is associated with a reduced physical function in elderly men. PMID:21875391

Ontogeny of modern human longitudinal body and transverse shoulder proportions.

PubMed

Frelat, Mélanie A; Coquerelle, Michael; Trinkaus, Erik

2017-03-01

Whereas variation of modern human adult body size and shape has been widely studied in the context of ecogeographical clines, little is known about the differential growth patterns of transverse and longitudinal dimensions among human populations. Our study explored the ontogenetic variation of those body proportions in modern humans. We compared results from four different approaches to study cross-sectional skeletal samples of Africans (n = 43), Amerindians (n = 69) and Europeans (n = 40) from 0 to 14 years of age. Clavicle, humerus, and femur intermetaphyseal lengths, and femoral distal metaphyseal breadth, were measured. Average ontogenetic trajectories were computed in order to compare the growth patterns of the three groups. Our findings demonstrated that the three geographical groups shared similar absolute and relative patterns of change with age for the four dimensions considered. Although interpopulation differences existed in transverse to longitudinal as well as in interlimb proportions, those differences did not seem to remain constant throughout ontogeny, similar to what has been shown for intralimb proportions. Growth rates of transverse shoulder proportions differed between populations from different regions after 10 years, whereas those for longitudinal proportions were very similar. The ontogeny of transverse shoulder proportions is more complex than what is observed for bi-iliac breadth, suggesting that transverse shoulder to limb proportions are not solely influenced by ecogeographical conditions. Our analysis demonstrates that methodologies that incorporate critical dimensions of body form could shed new light on human adaptation in both paleontological and neontological contexts. © 2016 Wiley Periodicals, Inc.

Composite marginal quantile regression analysis for longitudinal adolescent body mass index data.

PubMed

Yang, Chi-Chuan; Chen, Yi-Hau; Chang, Hsing-Yi

2017-09-20

Childhood and adolescenthood overweight or obesity, which may be quantified through the body mass index (BMI), is strongly associated with adult obesity and other health problems. Motivated by the child and adolescent behaviors in long-term evolution (CABLE) study, we are interested in individual, family, and school factors associated with marginal quantiles of longitudinal adolescent BMI values. We propose a new method for composite marginal quantile regression analysis for longitudinal outcome data, which performs marginal quantile regressions at multiple quantile levels simultaneously. The proposed method extends the quantile regression coefficient modeling method introduced by Frumento and Bottai (Biometrics 2016; 72:74-84) to longitudinal data accounting suitably for the correlation structure in longitudinal observations. A goodness-of-fit test for the proposed modeling is also developed. Simulation results show that the proposed method can be much more efficient than the analysis without taking correlation into account and the analysis performing separate quantile regressions at different quantile levels. The application to the longitudinal adolescent BMI data from the CABLE study demonstrates the practical utility of our proposal. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Risk prediction for chronic kidney disease progression using heterogeneous electronic health record data and time series analysis.

PubMed

Perotte, Adler; Ranganath, Rajesh; Hirsch, Jamie S; Blei, David; Elhadad, Noémie

2015-07-01

As adoption of electronic health records continues to increase, there is an opportunity to incorporate clinical documentation as well as laboratory values and demographics into risk prediction modeling. The authors develop a risk prediction model for chronic kidney disease (CKD) progression from stage III to stage IV that includes longitudinal data and features drawn from clinical documentation. The study cohort consisted of 2908 primary-care clinic patients who had at least three visits prior to January 1, 2013 and developed CKD stage III during their documented history. Development and validation cohorts were randomly selected from this cohort and the study datasets included longitudinal inpatient and outpatient data from these populations. Time series analysis (Kalman filter) and survival analysis (Cox proportional hazards) were combined to produce a range of risk models. These models were evaluated using concordance, a discriminatory statistic. A risk model incorporating longitudinal data on clinical documentation and laboratory test results (concordance 0.849) predicts progression from state III CKD to stage IV CKD more accurately when compared to a similar model without laboratory test results (concordance 0.733, P<.001), a model that only considers the most recent laboratory test results (concordance 0.819, P < .031) and a model based on estimated glomerular filtration rate (concordance 0.779, P < .001). A risk prediction model that takes longitudinal laboratory test results and clinical documentation into consideration can predict CKD progression from stage III to stage IV more accurately than three models that do not take all of these variables into consideration. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association.

Temporally-Constrained Group Sparse Learning for Longitudinal Data Analysis in Alzheimer’s Disease

PubMed Central

Jie, Biao; Liu, Mingxia; Liu, Jun

2016-01-01

Sparse learning has been widely investigated for analysis of brain images to assist the diagnosis of Alzheimer’s disease (AD) and its prodromal stage, i.e., mild cognitive impairment (MCI). However, most existing sparse learning-based studies only adopt cross-sectional analysis methods, where the sparse model is learned using data from a single time-point. Actually, multiple time-points of data are often available in brain imaging applications, which can be used in some longitudinal analysis methods to better uncover the disease progression patterns. Accordingly, in this paper we propose a novel temporally-constrained group sparse learning method aiming for longitudinal analysis with multiple time-points of data. Specifically, we learn a sparse linear regression model by using the imaging data from multiple time-points, where a group regularization term is first employed to group the weights for the same brain region across different time-points together. Furthermore, to reflect the smooth changes between data derived from adjacent time-points, we incorporate two smoothness regularization terms into the objective function, i.e., one fused smoothness term which requires that the differences between two successive weight vectors from adjacent time-points should be small, and another output smoothness term which requires the differences between outputs of two successive models from adjacent time-points should also be small. We develop an efficient optimization algorithm to solve the proposed objective function. Experimental results on ADNI database demonstrate that, compared with conventional sparse learning-based methods, our proposed method can achieve improved regression performance and also help in discovering disease-related biomarkers. PMID:27093313

Genome-Wide Meta-Analysis of Longitudinal Alcohol Consumption Across Youth and Early Adulthood.

PubMed

Adkins, Daniel E; Clark, Shaunna L; Copeland, William E; Kennedy, Martin; Conway, Kevin; Angold, Adrian; Maes, Hermine; Liu, Youfang; Kumar, Gaurav; Erkanli, Alaattin; Patkar, Ashwin A; Silberg, Judy; Brown, Tyson H; Fergusson, David M; Horwood, L John; Eaves, Lindon; van den Oord, Edwin J C G; Sullivan, Patrick F; Costello, E J

2015-08-01

The public health burden of alcohol is unevenly distributed across the life course, with levels of use, abuse, and dependence increasing across adolescence and peaking in early adulthood. Here, we leverage this temporal patterning to search for common genetic variants predicting developmental trajectories of alcohol consumption. Comparable psychiatric evaluations measuring alcohol consumption were collected in three longitudinal community samples (N=2,126, obs=12,166). Consumption-repeated measurements spanning adolescence and early adulthood were analyzed using linear mixed models, estimating individual consumption trajectories, which were then tested for association with Illumina 660W-Quad genotype data (866,099 SNPs after imputation and QC). Association results were combined across samples using standard meta-analysis methods. Four meta-analysis associations satisfied our pre-determined genome-wide significance criterion (FDR<0.1) and six others met our 'suggestive' criterion (FDR<0.2). Genome-wide significant associations were highly biological plausible, including associations within GABA transporter 1, SLC6A1 (solute carrier family 6, member 1), and exonic hits in LOC100129340 (mitofusin-1-like). Pathway analyses elaborated single marker results, indicating significant enriched associations to intuitive biological mechanisms, including neurotransmission, xenobiotic pharmacodynamics, and nuclear hormone receptors (NHR). These findings underscore the value of combining longitudinal behavioral data and genome-wide genotype information in order to study developmental patterns and improve statistical power in genomic studies.

Selecting a separable parametric spatiotemporal covariance structure for longitudinal imaging data.

PubMed

George, Brandon; Aban, Inmaculada

2015-01-15

Longitudinal imaging studies allow great insight into how the structure and function of a subject's internal anatomy changes over time. Unfortunately, the analysis of longitudinal imaging data is complicated by inherent spatial and temporal correlation: the temporal from the repeated measures and the spatial from the outcomes of interest being observed at multiple points in a patient's body. We propose the use of a linear model with a separable parametric spatiotemporal error structure for the analysis of repeated imaging data. The model makes use of spatial (exponential, spherical, and Matérn) and temporal (compound symmetric, autoregressive-1, Toeplitz, and unstructured) parametric correlation functions. A simulation study, inspired by a longitudinal cardiac imaging study on mitral regurgitation patients, compared different information criteria for selecting a particular separable parametric spatiotemporal correlation structure as well as the effects on types I and II error rates for inference on fixed effects when the specified model is incorrect. Information criteria were found to be highly accurate at choosing between separable parametric spatiotemporal correlation structures. Misspecification of the covariance structure was found to have the ability to inflate the type I error or have an overly conservative test size, which corresponded to decreased power. An example with clinical data is given illustrating how the covariance structure procedure can be performed in practice, as well as how covariance structure choice can change inferences about fixed effects. Copyright © 2014 John Wiley & Sons, Ltd.

Evaluation of Right Ventricular Myocardial Mechanics Using Velocity Vector Imaging of Cardiac MRI Cine Images in Transposition of the Great Arteries Following Atrial and Arterial Switch Operations.

PubMed

Thattaliyath, Bijoy D; Forsha, Daniel E; Stewart, Chad; Barker, Piers C A; Campbell, Michael J

2015-01-01

The aim of the study was to determine right and left ventricle deformation parameters in patients with transposition of the great arteries who had undergone atrial or arterial switch procedures. Patients with transposition are born with a systemic right ventricle. Historically, the atrial switch operation, in which the right ventricle remains the systemic ventricle, was performed. These patients have increased rates of morbidity and mortality. We used cardiac MRI with Velocity Vector Imaging analysis to characterize and compare ventricular myocardial deformation in patients who had an atrial switch or arterial switch operation. Patients with a history of these procedures, who had a clinically ordered cardiac MRI were included in the study. Consecutive 20 patients (75% male, 28.7 ± 1.8 years) who underwent atrial switch operation and 20 patients (60% male, 17.7 ± 1.9 years) who underwent arterial switch operation were included in the study. Four chamber and short-axis cine images were used to determine longitudinal and circumferential strain and strain rate using Vector Velocity Imaging software. Compared with the arterial switch group, the atrial switch group had decreased right ventricular ejection fraction and increased end-diastolic and end-systolic volumes, and no difference in left ventricular ejection fraction and volumes. The atrial switch group had decreased longitudinal and circumferential strain and strain rate. When compared with normal controls multiple strain parameters in the atrial switch group were reduced. Myocardial deformation analysis of transposition patients reveals a reduction of right ventricular function and decreased longitudinal and circumferential strain parameters in patients with an atrial switch operation compared with those with arterial switch operation. A better understanding of the mechanisms of right ventricle failure in transposition of great arteries may lead to improved therapies and adaptation. © 2015 Wiley Periodicals, Inc.

Early seizures and temporal lobe trauma predict post-traumatic epilepsy: A longitudinal study.

PubMed

Tubi, Meral A; Lutkenhoff, Evan; Blanco, Manuel Buitrago; McArthur, David; Villablanca, Pablo; Ellingson, Benjamin; Diaz-Arrastia, Ramon; Van Ness, Paul; Real, Courtney; Shrestha, Vikesh; Engel, Jerome; Vespa, Paul M; Agoston, Denes; Au, Alicia; Bell, Michael J; Branch, Craig; Buitrago Blanco, Manuel; Bullock, Ross; Claassen, Jan; Clarke, Robert; Cloyd, James; Coles, Lisa; Crawford, Karen; Diaz-Arrastia, Ramon; Duncan, Dominique; Ellingson, Benjamin; Engel, Jerome; Foreman, Brandon; Galanopoulou, Aristea; Gilmore, Emily; Olli, Grohn; Harris, Neil; Hartings, Jed; Lawrence, Hirsch; Hunn, Martin; Jette, Nathalie; Johnston, Leigh; Jones, Nigel; Kanner, Andres; McArthur, David; Monti, Martin; Morokoff, Andrew; Moshe, Solomon; Mowrey, Wenzhu; Naughton, Tomas; O'Brien, Terence; O'Phelan, Kristine; Pitkanen, Asla; Raman, Rema; Robertson, Courtney; Rosenthal, Eric; Shultz, Sandy; Snutch, Terrance; Staba, Richard; Toga, Arthur; Van Horn, Jack; Vespa, Paul; Willyerd, Frederick; Zimmermann, Lara

2018-05-31

Injury severity after traumatic brain injury (TBI) is a well-established risk factor for the development of post-traumatic epilepsy (PTE). However, whether lesion location influences the susceptibility of seizures and development of PTE longitudinally has yet to be defined. We hypothesized that lesion location, specifically in the temporal lobe, would be associated with an increased incidence of both early seizures and PTE. As secondary analysis measures, we assessed the degree of brain atrophy and functional recovery, and performed a between-group analysis, comparing patients who developed PTE with those who did not develop PTE. We assessed early seizure incidence (n = 90) and longitudinal development of PTE (n = 46) in a prospective convenience sample of patients with moderate-severe TBI. Acutely, patients were monitored with prospective cEEG and a high-resolution Magnetic Resonance Imaging (MRI) scan for lesion location classification. Chronically, patients underwent a high-resolution MRI, clinical assessment, and were longitudinally monitored for development of epilepsy for a minimum of 2 years post-injury. Early seizures, occurring within the first week post-injury, occurred in 26.7% of the patients (n = 90). Within the cohort of subjects who had evidence of early seizures (n = 24), 75% had a hemorrhagic temporal lobe injury on admission. For longitudinal analyses (n = 46), 45.7% of patients developed PTE within a minimum of 2 years post-injury. Within the cohort of subjects who developed PTE (n = 21), 85.7% had a hemorrhagic temporal lobe injury on admission and 38.1% had early (convulsive or non-convulsive) seizures on cEEG monitoring during their acute ICU stay. In a between-group analysis, patients with PTE (n = 21) were more likely than patients who did not develop PTE (n = 25) to have a hemorrhagic temporal lobe injury (p < 0.001), worse functional recovery (p = 0.003), and greater temporal lobe atrophy (p = 0.029). Our results indicate that in a cohort of patients with a moderate-severe TBI, 1) lesion location specificity (e.g. the temporal lobe) is related to both a high incidence of early seizures and longitudinal development of PTE, 2) early seizures, whether convulsive or non-convulsive in nature, are associated with an increased risk for PTE development, and 3) patients who develop PTE have greater chronic temporal lobe atrophy and worse functional outcomes, compared to those who do not develop PTE, despite matched injury severity characteristics. This study provides the foundation for a future prospective study focused on elucidating the mechanisms and risk factors for epileptogenesis. Copyright © 2017. Published by Elsevier Inc.

From HIV infection to therapeutic response: a population-based longitudinal HIV cascade-of-care study in KwaZulu-Natal, South Africa.

PubMed

Haber, Noah; Tanser, Frank; Bor, Jacob; Naidu, Kevindra; Mutevedzi, Tinofa; Herbst, Kobus; Porter, Kholoud; Pillay, Deenan; Bärnighausen, Till

2017-05-01

Standard approaches to estimation of losses in the HIV cascade of care are typically cross-sectional and do not include the population stages before linkage to clinical care. We used indiviual-level longitudinal cascade data, transition by transition, including population stages, both to identify the health-system losses in the cascade and to show the differences in inference between standard methods and the longitudinal approach. We used non-parametric survival analysis to estimate a longitudinal HIV care cascade for a large population of people with HIV residing in rural KwaZulu-Natal, South Africa. We linked data from a longitudinal population health surveillance (which is maintained by the Africa Health Research Institute) with patient records from the local public-sector HIV treatment programme (contained in an electronic clinical HIV treatment and care database, ARTemis). We followed up all people who had been newly detected as having HIV between Jan 1, 2006, and Dec 31, 2011, across six cascade stages: three population stages (first positive HIV test, HIV status knowledge, and linkage to care) and three clinical stages (eligibility for antiretroviral therapy [ART], initiation of ART, and therapeutic response). We compared our estimates to cross-sectional cascades in the same population. We estimated the cumulative incidence of reaching a particular cascade stage at a specific time with Kaplan-Meier survival analysis. Our population consisted of 5205 individuals with HIV who were followed up for 24 031 person-years. We recorded 598 deaths. 4539 individuals gained knowledge of their positive HIV status, 2818 were linked to care, 2151 became eligible for ART, 1839 began ART, and 1456 had successful responses to therapy. We used Kaplan-Meier survival analysis to adjust for censorship due to the end of data collection, and found that 8 years after testing positive in the population health surveillance, 16% had died. Among living patients, 82% knew their HIV status, 45% were linked to care, 39% were eligible for ART, 35% initiated ART, and 33% had reached therapeutic response. Median times to transition for these cascade stages were 52 months, 52 months, 20 months, 3 months, and 9 months, respectively. Compared with the population stages in the cascade, the transitions across the clinical stages were fast. Over calendar time, rates of linkage to care have decreased and patients presenting for the first time for care were, on average, healthier. HIV programmes should focus on linkage to care as the most important bottleneck in the cascade. Cascade estimation should be longitudinal rather than cross-sectional and start with the population stages preceding clinical care. Wellcome Trust, PEPFAR. Copyright © 2017 Elsevier Ltd. All rights reserved.

Regression Models for the Analysis of Longitudinal Gaussian Data from Multiple Sources

PubMed Central

O’Brien, Liam M.; Fitzmaurice, Garrett M.

2006-01-01

We present a regression model for the joint analysis of longitudinal multiple source Gaussian data. Longitudinal multiple source data arise when repeated measurements are taken from two or more sources, and each source provides a measure of the same underlying variable and on the same scale. This type of data generally produces a relatively large number of observations per subject; thus estimation of an unstructured covariance matrix often may not be possible. We consider two methods by which parsimonious models for the covariance can be obtained for longitudinal multiple source data. The methods are illustrated with an example of multiple informant data arising from a longitudinal interventional trial in psychiatry. PMID:15726666

HCIT Contrast Performance Sensitivity Studies: Simulation Versus Experiment

NASA Technical Reports Server (NTRS)

Sidick, Erkin; Shaklan, Stuart; Krist, John; Cady, Eric J.; Kern, Brian; Balasubramanian, Kunjithapatham

2013-01-01

Using NASA's High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory, we have experimentally investigated the sensitivity of dark hole contrast in a Lyot coronagraph for the following factors: 1) Lateral and longitudinal translation of an occulting mask; 2) An opaque spot on the occulting mask; 3) Sizes of the controlled dark hole area. Also, we compared the measured results with simulations obtained using both MACOS (Modeling and Analysis for Controlled Optical Systems) and PROPER optical analysis programs with full three-dimensional near-field diffraction analysis to model HCIT's optical train and coronagraph.

Longitudinal and Circumferential Strain of the Proximal Aorta

PubMed Central

Bell, Vanessa; Mitchell, William A.; Sigurðsson, Sigurður; Westenberg, Jos J. M.; Gotal, John D.; Torjesen, Alyssa A.; Aspelund, Thor; Launer, Lenore J.; de Roos, Albert; Gudnason, Vilmundur; Harris, Tamara B.; Mitchell, Gary F.

2014-01-01

Background Accurate assessment of mechanical properties of the proximal aorta is a requisite first step for elucidating the pathophysiology of isolated systolic hypertension. During systole, substantial proximal aortic axial displacement produces longitudinal strain, which we hypothesize causes variable underestimation of ascending aortic circumferential strain compared to values in the longitudinally constrained descending aorta. Methods and Results To assess effects of longitudinal strain, we performed magnetic resonance imaging in 375 participants (72 to 94 years old, 204 women) in the Age, Gene/Environment Susceptibility‐Reykjavik Study and measured aortic circumferential and longitudinal strain. Circumferential ascending aortic area strain uncorrected for longitudinal strain was comparable in women and men (mean [95% CI], 8.3 [7.8, 8.9] versus 7.9 [7.4, 8.5]%, respectively, P=0.3). However, longitudinal strain was greater in women (8.5±2.5 versus 7.0±2.5%, P<0.001), resulting in greater longitudinally corrected circumferential ascending aortic strain (14.4 [13.6, 15.2] versus 13.0 [12.4, 13.7]%, P=0.010). Observed circumferential descending aortic strain, which did not require correction (women: 14.0 [13.2, 14.8], men: 12.4 [11.6, 13.2]%, P=0.005), was larger than uncorrected (P<0.001), but comparable to longitudinally corrected (P=0.12) circumferential ascending aortic strain. Carotid‐femoral pulse wave velocity did not correlate with uncorrected ascending aortic strain (R=−0.04, P=0.5), but was inversely related to longitudinally corrected ascending and observed descending aortic strain (R=−0.15, P=0.004; R=−0.36, P<0.001, respectively). Longitudinal strain was also inversely related to carotid‐femoral pulse wave velocity and other risk factors for higher aortic stiffness including treated hypertension. Conclusions Longitudinal strain creates substantial and variable errors in circumferential ascending aortic area strain measurements, particularly in women, and should be considered to avoid misclassification of ascending aortic stiffness. PMID:25523153

Comparing meta-analysis and ecological-longitudinal analysis in time-series studies. A case study of the effects of air pollution on mortality in three Spanish cities

PubMed Central

Saez, M; Figueiras, A; Ballester, F; Perez-Hoyos, S; Ocana, R; Tobias, A

2001-01-01

STUDY OBJECTIVE—The objective of this paper is to introduce a different approach, called the ecological-longitudinal, to carrying out pooled analysis in time series ecological studies. Because it gives a larger number of data points and, hence, increases the statistical power of the analysis, this approach, unlike conventional ones, allows the complementation of aspects such as accommodation of random effect models, of lags, of interaction between pollutants and between pollutants and meteorological variables, that are hardly implemented in conventional approaches.
DESIGN—The approach is illustrated by providing quantitative estimates of the short-term effects of air pollution on mortality in three Spanish cities, Barcelona, Valencia and Vigo, for the period 1992-1994. Because the dependent variable was a count, a Poisson generalised linear model was first specified. Several modelling issues are worth mentioning. Firstly, because the relations between mortality and explanatory variables were non-linear, cubic splines were used for covariate control, leading to a generalised additive model, GAM. Secondly, the effects of the predictors on the response were allowed to occur with some lag. Thirdly, the residual autocorrelation, because of imperfect control, was controlled for by means of an autoregressive Poisson GAM. Finally, the longitudinal design demanded the consideration of the existence of individual heterogeneity, requiring the consideration of mixed models.
MAIN RESULTS—The estimates of the relative risks obtained from the individual analyses varied across cities, particularly those associated with sulphur dioxide. The highest relative risks corresponded to black smoke in Valencia. These estimates were higher than those obtained from the ecological-longitudinal analysis. Relative risks estimated from this latter analysis were practically identical across cities, 1.00638 (95% confidence intervals 1.0002, 1.0011) for a black smoke increase of 10 µg/m3 and 1.00415 (95% CI 1.0001, 1.0007) for a increase of 10 µg/m3 of sulphur dioxide. Because the statistical power is higher than in the individual analysis more interactions were statistically significant, especially those among air pollutants and meteorological variables.
CONCLUSIONS—Air pollutant levels were related to mortality in the three cities of the study, Barcelona, Valencia and Vigo. These results were consistent with similar studies in other cities, with other multicentric studies and coherent with both, previous individual, for each city, and multicentric studies for all three cities.


Keywords: air pollution; mortality; longitudinal studies PMID:11351001

Estimating Body Composition in Adolescent Sprint Athletes: Comparison of Different Methods in a 3 Years Longitudinal Design

PubMed Central

Aerenhouts, Dirk

2015-01-01

A recommended field method to assess body composition in adolescent sprint athletes is currently lacking. Existing methods developed for non-athletic adolescents were not longitudinally validated and do not take maturation status into account. This longitudinal study compared two field methods, i.e., a Bio Impedance Analysis (BIA) and a skinfold based equation, with underwater densitometry to track body fat percentage relative to years from age at peak height velocity in adolescent sprint athletes. In this study, adolescent sprint athletes (34 girls, 35 boys) were measured every 6 months during 3 years (age at start = 14.8 ± 1.5yrs in girls and 14.7 ± 1.9yrs in boys). Body fat percentage was estimated in 3 different ways: 1) using BIA with the TANITA TBF 410; 2) using a skinfold based equation; 3) using underwater densitometry which was considered as the reference method. Height for age since birth was used to estimate age at peak height velocity. Cross-sectional analyses were performed using repeated measures ANOVA and Pearson correlations between measurement methods at each occasion. Data were analyzed longitudinally using a multilevel cross-classified model with the PROC Mixed procedure. In boys, compared to underwater densitometry, the skinfold based formula revealed comparable values for body fatness during the study period whereas BIA showed a different pattern leading to an overestimation of body fatness starting from 4 years after age at peak height velocity. In girls, both the skinfold based formula and BIA overestimated body fatness across the whole range of years from peak height velocity. The skinfold based method appears to give an acceptable estimation of body composition during growth as compared to underwater densitometry in male adolescent sprinters. In girls, caution is warranted when interpreting estimations of body fatness by both BIA and a skinfold based formula since both methods tend to give an overestimation. PMID:26317426

SU-F-T-478: Effect of Deconvolution in Analysis of Mega Voltage Photon Beam Profiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muthukumaran, M; Manigandan, D; Murali, V

2016-06-15

Purpose: To study and compare the penumbra of 6 MV and 15 MV photon beam profiles after deconvoluting different volume ionization chambers. Methods: 0.125cc Semi-Flex chamber, Markus Chamber and PTW Farmer chamber were used to measure the in-plane and cross-plane profiles at 5 cm depth for 6 MV and 15 MV photons. The profiles were measured for various field sizes starting from 2×2 cm till 30×30 cm. PTW TBA scan software was used for the measurements and the “deconvolution” functionality in the software was used to remove the volume averaging effect due to finite volume of the chamber along lateralmore » and longitudinal directions for all the ionization chambers. The predicted true profile was compared and the change in penumbra before and after deconvolution was studied. Results: After deconvoluting the penumbra decreased by 1 mm for field sizes ranging from 2 × 2 cm till 20 x20 cm. This is observed for along both lateral and longitudinal directions. However for field sizes from 20 × 20 till 30 ×30 cm the difference in penumbra was around 1.2 till 1.8 mm. This was observed for both 6 MV and 15 MV photon beams. The penumbra was always lesser in the deconvoluted profiles for all the ionization chambers involved in the study. The variation in difference in penumbral values were in the order of 0.1 till 0.3 mm between the deconvoluted profile along lateral and longitudinal directions for all the chambers under study. Deconvolution of the profiles along longitudinal direction for Farmer chamber was not good and is not comparable with other deconvoluted profiles. Conclusion: The results of the deconvoluted profiles for 0.125cc and Markus chamber was comparable and the deconvolution functionality can be used to overcome the volume averaging effect.« less

A comparison of longitudinal and transverse approaches to ultrasound-guided axillary vein cannulation by experienced operators.

PubMed

He, Yi-Zhou; Zhong, Ming; Wu, Wei; Song, Jie-Qiong; Zhu, Du-Ming

2017-04-01

The axillary vein is an easily accessible vessel that can be used for ultrasound-guided central vascular access and offers an alternative to the internal jugular and subclavian veins. The objective of this study was to identify which transducer orientation, longitudinal or transverse, is better for imaging the axillary vein with ultrasound. We analyzed 236 patients who had undergone central venous cannulation of axillary vein in this retrospective study. Patients were divided into two groups, the longitudinal approach group (n=120) and transverse approach group (n=116). Recorded the one-attempt success rate, operation time, arterial puncture rate and pneumothorax rate. We perform chest radiography to confirm pneumothorax on all patients. We compared the one-attempt success rate, operation time, arterial puncture rate and pneumothorax rate between the two groups. The two groups were comparable with clinical characters of patients. The overall success rates of the longitudinal group and the transverse group were both 100%. The rate of one-attempt success in the longitudinal approach group is higher than the transverse approach group (91.7% vs. 82.8%, P=0.040). The transverse approach group had shorter operation time than the longitudinal group (184.7±8.1 vs. 287.5±19.6 seconds, P=0.000). The two groups had lower postoperative complications. Arterial puncture occurred in 1 of 120 longitudinal and 2 of 116 transverse attempts and this difference was no significant (P=0.541). No pneumothorax occurred in the two groups. The longitudinal approach during ultrasound-guided axillary vein cannulation is associated with greater one-attempt success rate compared with the transverse approach by experienced operators. The transverse approach has shorter operation time. The two groups have lower postoperative complications and are comparable with pneumothorax and arterial puncture.

Bayesian Covariate Selection in Mixed-Effects Models For Longitudinal Shape Analysis

PubMed Central

Muralidharan, Prasanna; Fishbaugh, James; Kim, Eun Young; Johnson, Hans J.; Paulsen, Jane S.; Gerig, Guido; Fletcher, P. Thomas

2016-01-01

The goal of longitudinal shape analysis is to understand how anatomical shape changes over time, in response to biological processes, including growth, aging, or disease. In many imaging studies, it is also critical to understand how these shape changes are affected by other factors, such as sex, disease diagnosis, IQ, etc. Current approaches to longitudinal shape analysis have focused on modeling age-related shape changes, but have not included the ability to handle covariates. In this paper, we present a novel Bayesian mixed-effects shape model that incorporates simultaneous relationships between longitudinal shape data and multiple predictors or covariates to the model. Moreover, we place an Automatic Relevance Determination (ARD) prior on the parameters, that lets us automatically select which covariates are most relevant to the model based on observed data. We evaluate our proposed model and inference procedure on a longitudinal study of Huntington's disease from PREDICT-HD. We first show the utility of the ARD prior for model selection in a univariate modeling of striatal volume, and next we apply the full high-dimensional longitudinal shape model to putamen shapes. PMID:28090246

A mechanical analysis of conduit arteries accounting for longitudinal residual strains.

PubMed

Wang, Ruoya; Gleason, Rudolph L

2010-04-01

Identification of an appropriate stress-free reference configuration is critically important in providing a reasonable prediction of the intramural stress distribution when performing biomechanical analyses on arteries. The stress-free state is commonly approximated as a radially cut ring that typically opens into a nearly circular sector, relieving much of the circumferential residual strains that exist in the traction-free configuration. An opening angle is often used to characterize this sector. In this study, we first present experimental results showing significant residual deformations in the longitudinal direction of two commonly studied arteries in the pig: the common carotid artery and the left anterior descending coronary artery. We concluded that a radially cut ring cannot completely describe the stress-free state of the arteries. Instead, we propose the use of a longitudinal opening angle, in conjunction with the traditional circumferential opening angle, to experimentally quantify the stress-free state of an artery. Secondly, we propose a new kinematic model to account for the addition of longitudinal residual strains through employing the longitudinal opening angle and performed a stress analysis. We found that with the inclusion of longitudinal residual strains in the stress analysis, the predicted circumferential stress gradient was decreased by 3-fold and the predicted longitudinal stress gradient was increased by 5.7-fold. Thus, inclusion of longitudinal residual strains has a significant effect on the predicted stress distribution in arteries.

The longitudinal offset technique for apodization of coupled resonator optical waveguide devices: concept and fabrication tolerance analysis.

PubMed

Doménech, José David; Muñoz, Pascual; Capmany, José

2009-11-09

In this paper, a novel technique to set the coupling constant between cells of a coupled resonator optical waveguide (CROW) device, in order to tailor the filter response, is presented. The technique is demonstrated by simulation assuming a racetrack ring resonator geometry. It consists on changing the effective length of the coupling section by applying a longitudinal offset between the resonators. On the contrary, the conventional techniques are based in the transversal change of the distance between the ring resonators, in steps that are commonly below the current fabrication resolution step (nm scale), leading to strong restrictions in the designs. The proposed longitudinal offset technique allows a more precise control of the coupling and presents an increased robustness against the fabrication limitations, since the needed resolution step is two orders of magnitude higher. Both techniques are compared in terms of the transmission esponse of CROW devices, under finite fabrication resolution steps.

Interaction of a shock with a longitudinal vortex

NASA Technical Reports Server (NTRS)

Erlebacher, Gordon; Hussaini, M. Y.; Shu, Chi-Wang

1996-01-01

In this paper we study the shock/longitudinal vortex interaction problem in axisymmetric geometry. Linearized analysis for small vortex strength is performed, and compared with results from a high order axisymmetric shock-fitted Euler solution obtained for this purpose. It is confirmed that for weak vortices, predictions from linear theory agree well with results from nonlinear numerical simulations at the shock location. To handle very strong longitudinal vortices, which may ultimately break the shock, we use an axisymmetric high order essentially non-oscillatory (ENO) shock capturing scheme. Comparison of shock-captured and shock-fitted results are performed in their regions of common validity. We also study the vortex breakdown as a function of Mach number ranging from 1.3 to 10, thus extending the range of existing results. For vortex strengths above a critical value. a triple point forms on the shock and a secondary shock forms to provide the necessary deceleration so that the fluid velocity can adjust to downstream conditions at the shock.

Scattering of a longitudinal Bessel beam by a sphere embedded in an isotropic elastic solid.

PubMed

Leão-Neto, J P; Lopes, J H; Silva, G T

2017-11-01

The scattering of a longitudinal Bessel beam of arbitrary order by a sphere embedded in an isotropic solid matrix is theoretically analyzed. The spherical inclusion can be made of a viscoelastic, elastic, or fluid-filled isotropic material. In the analysis, the absorbing, scattering, and extinction efficiency factors are obtained, e.g., the corresponding power per characteristic beam intensity per sphere's cross-section area. Furthermore, the extended optical theorem, which expresses the extinction efficiency in terms of an integral of the longitudinal scattering function is derived. Several features of zeroth- and first-order Bessel beams scattering in solids are illustrated considering a polymer adhesive (cured) sphere embedded in a stainless steel matrix. For instance, omnidirectional scattering can be achieved by choosing specific values of the half-cone angle of the Bessel beam, which is the beam's geometrical parameter. Additionally, it is demonstrated that mode suppression leads to lower absorption inside the inclusion when compared to plane wave scattering results.

Longitudinal analysis of the effect of academic failure tolerance on academic achievement fluctuation in medical school students.

PubMed

Chae, Su Jin; Kim, Miran; Chang, Ki Hong

2016-03-01

Academic failure tolerance (AFT) is one of the important psychological concepts in education, but its applications in medical education are rare. Thus, the purpose of this study was to investigate the effect of academic failure tolerance on academic achievement fluctuation among medical school students using a longitudinal research design. The subjects were 43 medical students who responded to the AFT test. This study analyzed the longitudinal data of achievement scores up to the 2nd academic year (2012-2013) among students who were divided into academic achievement improvement and decline groups. Comparing the improvement and decline groups' mean academic achievement fluctuation scores demonstrated that behavior and preferred task difficulty showed high scores whereas feeling scores were lower in the improvement group (p<0.05). In the improvement group, despite the higher negative feeling scores during academic failure, the students favored the more difficult subjects and were more assiduous in their studies. This will form an important basis for enhancing academic achievement among medical students.

Productivity or discrimination? An economic analysis of excess-weight penalty in the Swedish labor market.

PubMed

Dackehag, Margareta; Gerdtham, Ulf-G; Nordin, Martin

2015-07-01

This article investigates the excess-weight penalty in income for men and women in the Swedish labor market, using longitudinal data. It compares two identification strategies, OLS and individual fixed effects, and distinguishes between two main sources of excess-weight penalties, lower productivity because of bad health and discrimination. For men, the analysis finds a significant obesity penalty related to discrimination when applying individual fixed effects. We do not find any significant excess-weight penalty for women.

Empowering Students to Create Better Virtual Reality Applications: A Longitudinal Study of a VR Capstone Course

ERIC Educational Resources Information Center

Takala, Tuukka M.; Malmi, Lauri; Pugliese, Roberto; Takala, Tapio

2016-01-01

In this paper we present our experiences of teaching an annually organized virtual reality (VR) capstone course. We review three iterations of the course, during which a total of 45 students completed the course and 16 VR applications were implemented. Our comparative analysis describes the students' evaluation of the course, the applications…

Dropouts from the Chicago Public Schools: An Analysis of the Classes of 1982, 1983, 1984.

ERIC Educational Resources Information Center

Hess, G. Alfred, Jr.; Lauber, Diana

Many studies of high school dropout rates have compared the number of graduates with the number of enrolled freshmen. An adequate representation of the dropout rate, however, must combine all categories of leaving school before graduation, and a longitudinal approach must be employed. A joint venture between the Chicago Panel on Public School…

Longitudinal influence of alcohol and marijuana use on academic performance in college students.

PubMed

Meda, Shashwath A; Gueorguieva, Ralitza V; Pittman, Brian; Rosen, Rivkah R; Aslanzadeh, Farah; Tennen, Howard; Leen, Samantha; Hawkins, Keith; Raskin, Sarah; Wood, Rebecca M; Austad, Carol S; Dager, Alecia; Fallahi, Carolyn; Pearlson, Godfrey D

2017-01-01

Alcohol and marijuana are the two most abused substances in US colleges. However, research on the combined influence (cross sectional or longitudinal) of these substances on academic performance is currently scant. Data were derived from the longitudinal 2-year Brain and Alcohol Research in College Students (BARCS) study including 1142 freshman students who completed monthly marijuana use and alcohol consumption surveys. Subjects were classified into data-driven groups based on their alcohol and marijuana consumption. A linear mixed-model (LMM) was employed using this grouping factor to predict grade point average (GPA), adjusted for a variety of socio-demographic and clinical factors. Three data-driven clusters emerged: 1) No/low users of both, 2) medium-high alcohol/no-low marijuana, and 3) medium-high users of both substances. Individual cluster derivations between consecutive semesters remained stable. No significant interaction between clusters and semester (time) was noted. Post-hoc analysis suggest that at the outset, compared to sober peers, students using moderate to high levels of alcohol and low marijuana demonstrate lower GPAs, but this difference becomes non-significant over time. In contrast, students consuming both substances at moderate-to-high levels score significantly lower at both the outset and across the 2-year investigation period. Our follow-up analysis also indicate that when students curtailed their substance use over time they had significantly higher academic GPA compared to those who remained stable in their substance use patterns over the two year period. Overall, our study validates and extends the current literature by providing important implications of concurrent alcohol and marijuana use on academic achievement in college.

Longitudinal course of cortical thickness decline in amyotrophic lateral sclerosis.

PubMed

Schuster, Christina; Kasper, Elisabeth; Machts, Judith; Bittner, Daniel; Kaufmann, Jörn; Benecke, Reiner; Teipel, Stefan; Vielhaber, Stefan; Prudlo, Johannes

2014-10-01

To determine longitudinal rates of cortical atrophy in classical Amyotrophic lateral sclerosis (ALS) and ALS variants. Rates of cortical thinning were determined between 2 scans, 3-15 months apart, in 77 ALS patients: 51 classical, 12 upper motor neuron (UMN), and 14 lower motor neuron (LMN) ALS variants. Cortical thickness at the first assessment was compared with 60 healthy controls matched by age and gender. Atrophy rates were compared between patient sub-groups and correlated with disease duration, progression, and severity. Using a cross-sectional analysis, we found a significant difference in cortical thickness between ALS patients and controls in the motor and extra-motor areas (left medial orbito frontal gyrus, left inferior parietal gyrus, bilateral insular cortex, right fusiform gyrus, bilateral precuneus). Using a longitudinal analysis, we found a significant decline of cortical thickness in frontal, temporal, and parietal regions over the course of the study in ALS patients. Effects were independent of the clinical subtype, with exception of the precentral gyrus (p < 0.001). The LMN ALS variants demonstrated the highest rates of cortical thinning in the precentral gyrus, the UMN-dominant subjects exhibited intermediate rates of atrophy, and the classical ALS patients exhibited no such change. Atrophy of the precentral gyrus in classical ALS indicates a floor effect at the first assessment, resulting in a lack of further atrophy over time. Structural loss of the precentral gyrus appears to be an early sign of classical ALS. Over time, patterns of cortical thinning in extra-motor areas can be identified in ALS, regardless of the phenotype.

Comparing multiple imputation methods for systematically missing subject-level data.

PubMed

Kline, David; Andridge, Rebecca; Kaizar, Eloise

2017-06-01

When conducting research synthesis, the collection of studies that will be combined often do not measure the same set of variables, which creates missing data. When the studies to combine are longitudinal, missing data can occur on the observation-level (time-varying) or the subject-level (non-time-varying). Traditionally, the focus of missing data methods for longitudinal data has been on missing observation-level variables. In this paper, we focus on missing subject-level variables and compare two multiple imputation approaches: a joint modeling approach and a sequential conditional modeling approach. We find the joint modeling approach to be preferable to the sequential conditional approach, except when the covariance structure of the repeated outcome for each individual has homogenous variance and exchangeable correlation. Specifically, the regression coefficient estimates from an analysis incorporating imputed values based on the sequential conditional method are attenuated and less efficient than those from the joint method. Remarkably, the estimates from the sequential conditional method are often less efficient than a complete case analysis, which, in the context of research synthesis, implies that we lose efficiency by combining studies. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Progression of white matter damage in progressive supranuclear palsy with predominant parkinsonism.

PubMed

Caso, Francesca; Agosta, Federica; Ječmenica-Lukić, Milica; Petrović, Igor; Meani, Alessandro; Kostic, Vladimir S; Filippi, Massimo

2018-04-01

Progressive supranuclear palsy with predominant parkinsonism (PSP-P) accounts for 14-35% of all PSP cases. A few cross-sectional MRI studies in PSP-P showed a remarkable white matter (WM) damage. Progression of brain structural damage in these patients remains unknown. Longitudinal clinical, cognitive and diffusion tensor (DT) MRI data were obtained over a mean 1.6 year follow up in 10 PSP-P patients. At study entry, patients were compared with 36 healthy controls. Voxelwise statistical analysis of white matter DT MRI data (mean, axial and radial diffusivity, and fractional anisotropy) was carried out using tract-based spatial statistics. During the 1.6 year follow up, PSP-P patients showed significant decline of motor, cognitive and mood disturbances. DT MRI analysis revealed at baseline a widespread pattern of WM alterations. Over time, PSP-P patients exhibited progression of WM damage in supratentorial tracts compared to baseline. No WM changes were detected in cerebellar WM. In PSP-P patients, WM damage significantly progressed over time. Longitudinal DT MRI measures are a potential in vivo marker of disease progression in PSP-P. Copyright © 2018 Elsevier Ltd. All rights reserved.

Right Ventricular Strain and Dyssynchrony Assessment in Arrhythmogenic Right Ventricular Cardiomyopathy: Cardiac Magnetic Resonance Feature-Tracking Study.

PubMed

Prati, Giulio; Vitrella, Giancarlo; Allocca, Giuseppe; Muser, Daniele; Buttignoni, Sonja Cukon; Piccoli, Gianluca; Morocutti, Giorgio; Delise, Pietro; Pinamonti, Bruno; Proclemer, Alessandro; Sinagra, Gianfranco; Nucifora, Gaetano

2015-11-01

Analysis of right ventricular (RV) regional dysfunction by cardiac magnetic resonance (CMR) imaging in arrhythmogenic RV cardiomyopathy (ARVC) may be inadequate because of the complex contraction pattern of the RV. Aim of this study was to determine the use of RV strain and dyssynchrony assessment in ARVC using feature-tracking CMR analysis. Thirty-two consecutive patients with ARVC referred to CMR imaging were included. Thirty-two patients with idiopathic RV outflow tract arrhythmias and 32 control subjects, matched for age and sex to the ARVC group, were included for comparison purpose. CMR imaging was performed to assess biventricular function; feature-tracking analysis was applied to the cine CMR images to assess regional and global longitudinal, circumferential, and radial RV strains and RV dyssynchrony (defined as the SD of the time-to-peak strain of the RV segments). RV global longitudinal strain (-17±5% versus -26±6% versus -29±6%; P<0.001), global circumferential strain (-9±4% versus -12±4% versus -13±5%; P=0.001), and global radial strain (18 [12-26]% versus 22 [15-32]% versus 27 [20-39]%; P=0.015) were significantly lower and SD of the time-to-peak RV strain in all 3 directions were significantly higher among patients with ARVC compared with patients with RV outflow tract arrhythmias and controls. RV global longitudinal strain >-23.2%, SD of the time-to-peak RV longitudinal strain >113.1 ms, and SD of the time-to-peak RV circumferential strain >177.1 ms allowed correct identification of 88%, 75%, and 63% of ARVC patients with no or only minor CMR criteria for ARVC diagnosis. Strain analysis by feature-tracking CMR helps to objectively quantify global and regional RV dysfunction and RV dyssynchrony in patients with ARVC and provides incremental value over conventional cine CMR imaging. © 2015 American Heart Association, Inc.

Determination of longitudinal aerodynamic derivatives using flight data from an icing research aircraft

NASA Technical Reports Server (NTRS)

Ranaudo, R. J.; Batterson, J. G.; Reehorst, A. L.; Bond, T. H.; Omara, T. M.

1989-01-01

A flight test was performed with the NASA Lewis Research Center's DH-6 icing research aircraft. The purpose was to employ a flight test procedure and data analysis method, to determine the accuracy with which the effects of ice on aircraft stability and control could be measured. For simplicity, flight testing was restricted to the short period longitudinal mode. Two flights were flown in a clean (baseline) configuration, and two flights were flown with simulated horizontal tail ice. Forty-five repeat doublet maneuvers were performed in each of four test configurations, at a given trim speed, to determine the ensemble variation of the estimated stability and control derivatives. Additional maneuvers were also performed in each configuration, to determine the variation in the longitudinal derivative estimates over a wide range of trim speeds. Stability and control derivatives were estimated by a Modified Stepwise Regression (MSR) technique. A measure of the confidence in the derivative estimates was obtained by comparing the standard error for the ensemble of repeat maneuvers, to the average of the estimated standard errors predicted by the MSR program. A multiplicative relationship was determined between the ensemble standard error, and the averaged program standard errors. In addition, a 95 percent confidence interval analysis was performed for the elevator effectiveness estimates, C sub m sub delta e. This analysis identified the speed range where changes in C sub m sub delta e could be attributed to icing effects. The magnitude of icing effects on the derivative estimates were strongly dependent on flight speed and aircraft wing flap configuration. With wing flaps up, the estimated derivatives were degraded most at lower speeds corresponding to that configuration. With wing flaps extended to 10 degrees, the estimated derivatives were degraded most at the higher corresponding speeds. The effects of icing on the changes in longitudinal stability and control derivatives were adequately determined by the flight test procedure and the MSR analysis method discussed herein.

Optimising qualitative longitudinal analysis: Insights from a study of traumatic brain injury recovery and adaptation.

PubMed

Fadyl, Joanna K; Channon, Alexis; Theadom, Alice; McPherson, Kathryn M

2017-04-01

Knowledge about aspects that influence recovery and adaptation in the postacute phase of disabling health events is key to understanding how best to provide appropriate rehabilitation and health services. Qualitative longitudinal research makes it possible to look for patterns, key time points and critical moments that could be vital for interventions and supports. However, strategies that support robust data management and analysis for longitudinal qualitative research in health-care are not well documented in the literature. This article reviews three challenges encountered in a large longitudinal qualitative descriptive study about experiences of recovery and adaptation after traumatic brain injury in New Zealand, and the strategies and technologies used to address them. These were (i) tracking coding and analysis decisions during an extended analysis period; (ii) navigating interpretations over time and in response to new data; and (iii) exploiting data volume and complexity. Concept mapping during coding review, a considered combination of information technologies, employing both cross-sectional and narrative analysis, and an expectation that subanalyses would be required for key topics helped us manage the study in a way that facilitated useful and novel insights. These strategies could be applied in other qualitative longitudinal studies in healthcare inquiry to optimise data analysis and stimulate important insights. © 2016 John Wiley & Sons Ltd.

A Longitudinal Analysis of Family Migration and the Gender Gap in Earnings in the United States and Great Britain

PubMed Central

COOKE, THOMAS J.; BOYLE, PAUL; COUCH, KENNETH; FEIJTEN, PETEKE

2009-01-01

This article uses longitudinal data for the United States and Great Britain to examine the impact of residential mobility and childbirth on the earnings of women, their family earnings, and the related division of earnings by gender. This project is the first to compare explicitly the impact of childbirth and family migration on women’s earnings, and it extends prior cross-sectional and longitudinal studies on isolated countries by providing a direct contrast between two major industrialized nations, using comparable measures. The results indicate that families respond in similar ways in both countries to migration and childbirth. In response to both migration and childbirth, women’s earnings fall at the time of the event and recover slowly afterward, but the magnitude of the impact is roughly twice as large for childbirth as for migration. However, migration—but not the birth of a child—is also associated with a significant increase in total family earnings because of increased husbands’ earnings. As a result, the effect of migration on the relative earnings of wives to husbands is similar to the effect of childbirth. These results suggest that family migration should be given consideration in the literature on the gender earnings gap. PMID:19348113

NASTRAN DMAP Fuzzy Structures Analysis: Summary of Research

NASA Technical Reports Server (NTRS)

Sparrow, Victor W.

2001-01-01

The main proposed tasks of Cooperative Agreement NCC1-382 were: (1) developing MSC/NASTRAN DMAP language scripts to implement the Soize fuzzy structures approach for modeling the dynamics of complex structures; (2) benchmarking the results of the new code to those for a cantilevered beam in the literature; and (3) testing and validating the new code by comparing the fuzzy structures results to NASA Langley experimental and conventional finite element results for two model test structures representative of aircraft fuselage sidewall construction: (A) a small aluminum test panel (SLP, single longeron panel) with a single longitudinal stringer attached with bolts; and (B) a 47 by 72 inch flat aluminum fuselage panel (AFP, aluminum fuselage panel) including six longitudinal stringers and four frame stiffeners attached with rivets.

Life satisfaction and resilience in medical school – a six-year longitudinal, nationwide and comparative study

PubMed Central

Kjeldstadli, Kari; Tyssen, Reidar; Finset, Arnstein; Hem, Erlend; Gude, Tore; Gronvold, Nina T; Ekeberg, Oivind; Vaglum, Per

2006-01-01

Background This study examined the relationship between life satisfaction among medical students and a basic model of personality, stress and coping. Previous studies have shown relatively high levels of distress, such as symptoms of depression and suicidal thoughts in medical undergraduates. However despite the increased focus on positive psychological health and well-being during the past decades, only a few studies have focused on life satisfaction and coping in medical students. This is the first longitudinal study which has identified predictors of sustained high levels of life satisfaction among medical students. Methods This longitudinal, nationwide questionnaire study examined the course of life satisfaction during medical school, compared the level of satisfaction of medical students with that of other university students, and identified resilience factors. T-tests were used to compare means of life satisfaction between and within the population groups. K-means cluster analyses were applied to identify subgroups among the medical students. Analysis of Variance (ANOVA) and logistic regression analyses were used to compare the subgroups. Results Life satisfaction decreased during medical school. Medical students were as satisfied as other students in the first year of study, but reported less satisfaction in their graduation year. Medical students who sustained high levels of life satisfaction perceived medical school as interfering less with their social and personal life, and were less likely to use emotion focused coping, such as wishful thinking, than their peers. Conclusion Medical schools should encourage students to spend adequate time on their social and personal lives and emphasise the importance of health-promoting coping strategies. PMID:16984638

The Latent Curve ARMA (P, Q) Panel Model: Longitudinal Data Analysis in Educational Research and Evaluation

ERIC Educational Resources Information Center

Sivo, Stephen; Fan, Xitao

2008-01-01

Autocorrelated residuals in longitudinal data are widely reported as common to longitudinal data. Yet few, if any, researchers modeling growth processes evaluate a priori whether their data have this feature. Sivo, Fan, and Witta (2005) found that not modeling autocorrelated residuals present in longitudinal data severely biases latent curve…

A Comparison of Various MRA Methods Applied to Longitudinal Evaluation Studies in Vocational Education.

ERIC Educational Resources Information Center

Kapes, Jerome T.; And Others

Three models of multiple regression analysis (MRA): single equation, commonality analysis, and path analysis, were applied to longitudinal data from the Pennsylvania Vocational Development Study. Variables influencing weekly income of vocational education students one year after high school graduation were examined: grade point averages (grades…

A State Space Modeling Approach to Mediation Analysis

ERIC Educational Resources Information Center

Gu, Fei; Preacher, Kristopher J.; Ferrer, Emilio

2014-01-01

Mediation is a causal process that evolves over time. Thus, a study of mediation requires data collected throughout the process. However, most applications of mediation analysis use cross-sectional rather than longitudinal data. Another implicit assumption commonly made in longitudinal designs for mediation analysis is that the same mediation…

A 2-D numerical simulation study on longitudinal solute transport and longitudinal dispersion coefficient

NASA Astrophysics Data System (ADS)

Zhang, Wei

2011-07-01

The longitudinal dispersion coefficient, DL, is a fundamental parameter of longitudinal solute transport models: the advection-dispersion (AD) model and various deadzone models. Since DL cannot be measured directly, and since its calibration using tracer test data is quite expensive and not always available, researchers have developed various methods, theoretical or empirical, for estimating DL by easier available cross-sectional hydraulic measurements (i.e., the transverse velocity profile, etc.). However, for known and unknown reasons, DL cannot be satisfactorily predicted using these theoretical/empirical formulae. Either there is very large prediction error for theoretical methods, or there is a lack of generality for the empirical formulae. Here, numerical experiments using Mike21, a software package that implements one of the most rigorous two-dimensional hydrodynamic and solute transport equations, for longitudinal solute transport in hypothetical streams, are presented. An analysis of the evolution of simulated solute clouds indicates that the two fundamental assumptions in Fischer's longitudinal transport analysis may be not reasonable. The transverse solute concentration distribution, and hence the longitudinal transport appears to be controlled by a dimensionless number ?, where Q is the average volumetric flowrate, Dt is a cross-sectional average transverse dispersion coefficient, and W is channel flow width. A simple empirical ? relationship may be established. Analysis and a revision of Fischer's theoretical formula suggest that ɛ influences the efficiency of transverse mixing and hence has restraining effect on longitudinal spreading. The findings presented here would improve and expand our understanding of longitudinal solute transport in open channel flow.

Controlled pattern imputation for sensitivity analysis of longitudinal binary and ordinal outcomes with nonignorable dropout.

PubMed

Tang, Yongqiang

2018-04-30

The controlled imputation method refers to a class of pattern mixture models that have been commonly used as sensitivity analyses of longitudinal clinical trials with nonignorable dropout in recent years. These pattern mixture models assume that participants in the experimental arm after dropout have similar response profiles to the control participants or have worse outcomes than otherwise similar participants who remain on the experimental treatment. In spite of its popularity, the controlled imputation has not been formally developed for longitudinal binary and ordinal outcomes partially due to the lack of a natural multivariate distribution for such endpoints. In this paper, we propose 2 approaches for implementing the controlled imputation for binary and ordinal data based respectively on the sequential logistic regression and the multivariate probit model. Efficient Markov chain Monte Carlo algorithms are developed for missing data imputation by using the monotone data augmentation technique for the sequential logistic regression and a parameter-expanded monotone data augmentation scheme for the multivariate probit model. We assess the performance of the proposed procedures by simulation and the analysis of a schizophrenia clinical trial and compare them with the fully conditional specification, last observation carried forward, and baseline observation carried forward imputation methods. Copyright © 2018 John Wiley & Sons, Ltd.

Changes in aerobic power of men, ages 25-70 yr

NASA Technical Reports Server (NTRS)

Jackson, A. S.; Beard, E. F.; Wier, L. T.; Ross, R. M.; Stuteville, J. E.; Blair, S. N.

1995-01-01

This study quantified and compared the cross-sectional and longitudinal influence of age, self-report physical activity (SR-PA), and body composition (%fat) on the decline of maximal aerobic power (VO2peak). The cross-sectional sample consisted of 1,499 healthy men ages 25-70 yr. The 156 men of the longitudinal sample were from the same population and examined twice, the mean time between tests was 4.1 (+/- 1.2) yr. Peak oxygen uptake was determined by indirect calorimetry during a maximal treadmill exercise test. The zero-order correlations between VO2peak and %fat (r = -0.62) and SR-PA (r = 0.58) were significantly (P < 0.05) higher that the age correlation (r = -0.45). Linear regression defined the cross-sectional age-related decline in VO2peak at 0.46 ml.kg-1.min-1.yr-1. Multiple regression analysis (R = 0.79) showed that nearly 50% of this cross-sectional decline was due to %fat and SR-PA, adding these lifestyle variables to the multiple regression model reduced the age regression weight to -0.26 ml.kg-1.min-1.yr-1. Statistically controlling for time differences between tests, general linear models analysis showed that longitudinal changes in aerobic power were due to independent changes in %fat and SR-PA, confirming the cross-sectional results.

Global strength assessment in oblique waves of a large gas carrier ship, based on a non-linear iterative method

NASA Astrophysics Data System (ADS)

Domnisoru, L.; Modiga, A.; Gasparotti, C.

2016-08-01

At the ship's design, the first step of the hull structural assessment is based on the longitudinal strength analysis, with head wave equivalent loads by the ships' classification societies’ rules. This paper presents an enhancement of the longitudinal strength analysis, considering the general case of the oblique quasi-static equivalent waves, based on the own non-linear iterative procedure and in-house program. The numerical approach is developed for the mono-hull ships, without restrictions on 3D-hull offset lines non-linearities, and involves three interlinked iterative cycles on floating, pitch and roll trim equilibrium conditions. Besides the ship-wave equilibrium parameters, the ship's girder wave induced loads are obtained. As numerical study case we have considered a large LPG liquefied petroleum gas carrier. The numerical results of the large LPG are compared with the statistical design values from several ships' classification societies’ rules. This study makes possible to obtain the oblique wave conditions that are inducing the maximum loads into the large LPG ship's girder. The numerical results of this study are pointing out that the non-linear iterative approach is necessary for the computation of the extreme loads induced by the oblique waves, ensuring better accuracy of the large LPG ship's longitudinal strength assessment.

The ONS Longitudinal Study--a prestigious past and a bright future.

PubMed

Goldring, Shayla; Newman, Jim

2010-01-01

This issue of Population Trends includes a number of articles and reports resulting from research based on the ONS Longitudinal Study (ONS LS). They have been drawn together in one issue to highlight the value of this type of study for demographic research.2009 marked the 35th anniversary of the establishment of the ONS LS. The study now contains data from the last four censuses (1971 to 2001), linked to vital events data since 1971, for a sample of one per cent of the population of England and Wales.More recently, sister studies have been established in Scotland and Northern Ireland. The Scottish Longitudinal Study (SLS) started with 1991 Census data and the Northern Ireland Longitudinal Study (NILS)started with 2001 Census data.The lead article in this issue comes from an exemplar project that was established to explore how to utilise the three studies to carry out UK-wide longitudinal analysis. Two different methods were used to analyse socio-economic and country level differences in health and mortality across the studies. The article summarises the results of this analysis, reports on the relative strengths of the different methods used, and draws attention to a number of new resources that have been developed by the project researchers as aids to using all three studies.This is an excellent example of collaborative working across the UK, involving researchers from the Centre for Longitudinal Study Information and User Support (CeLSIUS) at the London School of Hygiene and Tropical Medicine, the Longitudinal Studies Centre - Scotland (LSCS) at the University of St.Andrews and the Northern Ireland Longitudinal Study - Research Support Unit (NILS-RSU) at Queen's University Belfast. The project also involved collaboration between ONS, the General Register Office for Scotland (GROS) and the Northern Ireland Statistics and Research Agency (NISRA) to ensure the secure transfer and handling of data from the three studies so that it could be brought together in one place for analysis.The other ONS LS-based articles and reports in this edition largely focus on research into issues related to families and households, as summarised below: A collaborative project involving Ben Wilson (ONS) and Rachel Stuchbury (CeLSIUS) comparing the stability of partnerships involving marriage and cohabitation.A project looking at transitions in children's experience of living in a workless household and how this varies by ethnic group, submitted by Lucinda Platt (Institute for Social & Economic Research, University of Essex).An article on the effect of a change in the census definition of a child between 1991 and 2001 submitted by Emily Grundy, Rachel Stuchbury and Harriet Young (CeLSIUS).The remainder of this introductory article will focus on the ONS LS, its history and some examples of its use, and gives a summary of planned developments over the coming years. Please refer to the contact details at the end of the article if you require further information on any of the three longitudinal studies.

Experimental Aerodynamic Characteristics of the Pegasus Air-Launched Booster and Comparisons with Predicted and Flight Results

NASA Technical Reports Server (NTRS)

Rhode, M. N.; Engelund, Walter C.; Mendenhall, Michael R.

1995-01-01

Experimental longitudinal and lateral-directional aerodynamic characteristics were obtained for the Pegasus and Pegasus XL configurations over a Mach number range from 1.6 to 6 and angles of attack from -4 to +24 degrees. Angle of sideslip was varied from -6 to +6 degrees, and control surfaces were deflected to obtain elevon, aileron, and rudder effectiveness. Experimental data for the Pegasus configuration are compared with engineering code predictions performed by Nielsen Engineering & Research, Inc. (NEAR) in the aerodynamic design of the Pegasus vehicle, and with results from the Aerodynamic Preliminary Analysis System (APAS) code. Comparisons of experimental results are also made with longitudinal flight data from Flight #2 of the Pegasus vehicle. Results show that the longitudinal aerodynamic characteristics of the Pegasus and Pegasus XL configurations are similar, having the same lift-curve slope and drag levels across the Mach number range. Both configurations are longitudinally stable, with stability decreasing towards neutral levels as Mach number increases. Directional stability is negative at moderate to high angles of attack due to separated flow over the vertical tail. Dihedral effect is positive for both configurations, but is reduced 30-50 percent for the Pegasus XL configuration because of the horizontal tail anhedral. Predicted longitudinal characteristics and both longitudinal and lateral-directional control effectiveness are generally in good agreement with experiment. Due to the complex leeside flowfield, lateral-directional characteristics are not as well predicted by the engineering codes. Experiment and flight data are in good agreement across the Mach number range.

Second- to Third-Trimester Longitudinal Growth Assessment for the Prediction of Largeness for Gestational Age and Macrosomia in an Unselected Population.

PubMed

Caradeux, Javier; Eixarch, Elisenda; Mazarico, Edurne; Basuki, Tri Rahmat; Gratacós, Eduard; Figueras, Francesc

2018-01-01

Prenatal detection of excessive growth remains inaccurate. Most strategies rely on a single cross-sectional evaluation of fetal size during the third trimester. To compare second- to third-trimester longitudinal growth assessment with cross-sectional evaluation at the third trimester in the prediction of largeness for gestational age (LGA) and macrosomia. A cohort of 2,696 unselected singleton pregnancies scanned at 21 ± 2 and 32 ± 2 weeks was created. Abdominal circumference (AC) measurements were transformed to z values according to the INTERGROWTH-21st standards. Longitudinal growth assessment was performed by calculation of z velocity and conditional growth. Both methods were compared to cross-sectional assessment at 32 ± 2 weeks. Predictive performance for LGA and macrosomia was determined by receiver operating characteristic curve analysis. A total of 188 (7%) newborns qualified for LGA and 182 (6.8%) for macrosomia. The areas under the curve (AUCs) for 32-week AC z score, AC z velocity, and conditional AC were 0.78, 0.61, and 0.55, respectively, for the prediction of LGA, and 0.75, 0.61, and 0.55, respectively, for the prediction of macrosomia. Both AUCs of AC z velocity and conditional AC were significantly lower (p < 0.001) than the AUC of cross-sectional AC z scores. In the general population, second- to third-trimester longitudinal assessment of fetal growth is inferior to third-trimester cross-sectional evaluation of size in the prediction of LGA and macrosomia. © 2017 S. Karger AG, Basel.

An empirical analysis of the public's attitudes toward advertising hospital services: a comparative cross-sectional study.

PubMed

Moser, H Ronald; Freeman, Gordon L

2014-01-01

This study investigates current opinions about hospital advertising and compares them to the attitudes expressed 25 years ago. It replicates a survey done in 1985, using the same questionnaire and population to compare responses longitudinally. The study indicates some changes in the public's opinions of hospital advertising. Although the image of hospitals remains positive, most of the 2010 respondents' opinions were rather mixed regarding whether it is proper for hospitals to advertise. The study also confirmed that the quality of service and reputation of hospitals remain more important to the public than price.

Use of Repeated Blood Pressure and Cholesterol Measurements to Improve Cardiovascular Disease Risk Prediction: An Individual-Participant-Data Meta-Analysis

PubMed Central

Barrett, Jessica; Pennells, Lisa; Sweeting, Michael; Willeit, Peter; Di Angelantonio, Emanuele; Gudnason, Vilmundur; Nordestgaard, Børge G.; Psaty, Bruce M; Goldbourt, Uri; Best, Lyle G; Assmann, Gerd; Salonen, Jukka T; Nietert, Paul J; Verschuren, W. M. Monique; Brunner, Eric J; Kronmal, Richard A; Salomaa, Veikko; Bakker, Stephan J L; Dagenais, Gilles R; Sato, Shinichi; Jansson, Jan-Håkan; Willeit, Johann; Onat, Altan; de la Cámara, Agustin Gómez; Roussel, Ronan; Völzke, Henry; Dankner, Rachel; Tipping, Robert W; Meade, Tom W; Donfrancesco, Chiara; Kuller, Lewis H; Peters, Annette; Gallacher, John; Kromhout, Daan; Iso, Hiroyasu; Knuiman, Matthew; Casiglia, Edoardo; Kavousi, Maryam; Palmieri, Luigi; Sundström, Johan; Davis, Barry R; Njølstad, Inger; Couper, David; Danesh, John; Thompson, Simon G; Wood, Angela

2017-01-01

Abstract The added value of incorporating information from repeated blood pressure and cholesterol measurements to predict cardiovascular disease (CVD) risk has not been rigorously assessed. We used data on 191,445 adults from the Emerging Risk Factors Collaboration (38 cohorts from 17 countries with data encompassing 1962–2014) with more than 1 million measurements of systolic blood pressure, total cholesterol, and high-density lipoprotein cholesterol. Over a median 12 years of follow-up, 21,170 CVD events occurred. Risk prediction models using cumulative mean values of repeated measurements and summary measures from longitudinal modeling of the repeated measurements were compared with models using measurements from a single time point. Risk discrimination (C-index) and net reclassification were calculated, and changes in C-indices were meta-analyzed across studies. Compared with the single-time-point model, the cumulative means and longitudinal models increased the C-index by 0.0040 (95% confidence interval (CI): 0.0023, 0.0057) and 0.0023 (95% CI: 0.0005, 0.0042), respectively. Reclassification was also improved in both models; compared with the single-time-point model, overall net reclassification improvements were 0.0369 (95% CI: 0.0303, 0.0436) for the cumulative-means model and 0.0177 (95% CI: 0.0110, 0.0243) for the longitudinal model. In conclusion, incorporating repeated measurements of blood pressure and cholesterol into CVD risk prediction models slightly improves risk prediction. PMID:28549073

Cross-Sectional Analysis of Longitudinal Mediation Processes.

PubMed

O'Laughlin, Kristine D; Martin, Monica J; Ferrer, Emilio

2018-01-01

Statistical mediation analysis can help to identify and explain the mechanisms behind psychological processes. Examining a set of variables for mediation effects is a ubiquitous process in the social sciences literature; however, despite evidence suggesting that cross-sectional data can misrepresent the mediation of longitudinal processes, cross-sectional analyses continue to be used in this manner. Alternative longitudinal mediation models, including those rooted in a structural equation modeling framework (cross-lagged panel, latent growth curve, and latent difference score models) are currently available and may provide a better representation of mediation processes for longitudinal data. The purpose of this paper is twofold: first, we provide a comparison of cross-sectional and longitudinal mediation models; second, we advocate using models to evaluate mediation effects that capture the temporal sequence of the process under study. Two separate empirical examples are presented to illustrate differences in the conclusions drawn from cross-sectional and longitudinal mediation analyses. Findings from these examples yielded substantial differences in interpretations between the cross-sectional and longitudinal mediation models considered here. Based on these observations, researchers should use caution when attempting to use cross-sectional data in place of longitudinal data for mediation analyses.

A patient-specific segmentation framework for longitudinal MR images of traumatic brain injury

NASA Astrophysics Data System (ADS)

Wang, Bo; Prastawa, Marcel; Irimia, Andrei; Chambers, Micah C.; Vespa, Paul M.; Van Horn, John D.; Gerig, Guido

2012-02-01

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Robust, reproducible segmentations of MR images with TBI are crucial for quantitative analysis of recovery and treatment efficacy. However, this is a significant challenge due to severe anatomy changes caused by edema (swelling), bleeding, tissue deformation, skull fracture, and other effects related to head injury. In this paper, we introduce a multi-modal image segmentation framework for longitudinal TBI images. The framework is initialized through manual input of primary lesion sites at each time point, which are then refined by a joint approach composed of Bayesian segmentation and construction of a personalized atlas. The personalized atlas construction estimates the average of the posteriors of the Bayesian segmentation at each time point and warps the average back to each time point to provide the updated priors for Bayesian segmentation. The difference between our approach and segmenting longitudinal images independently is that we use the information from all time points to improve the segmentations. Given a manual initialization, our framework automatically segments healthy structures (white matter, grey matter, cerebrospinal fluid) as well as different lesions such as hemorrhagic lesions and edema. Our framework can handle different sets of modalities at each time point, which provides flexibility in analyzing clinical scans. We show results on three subjects with acute baseline scans and chronic follow-up scans. The results demonstrate that joint analysis of all the points yields improved segmentation compared to independent analysis of the two time points.

Novel Longitudinal and Propensity Score Matched Analysis of Hands-On Cooking and Nutrition Education versus Traditional Clinical Education among 627 Medical Students

PubMed Central

Monlezun, Dominique J.; Leong, Benjamin; Joo, Esther; Birkhead, Andrew G.; Sarris, Leah; Harlan, Timothy S.

2015-01-01

Background. Physicians are inadequately equipped to respond to the global obesity and nutrition-associated chronic disease epidemics. We investigated superiority of simulation-based medical education with deliberate practice (SBME-DP) hands-on cooking and nutrition elective in a medical school-based teaching kitchen versus traditional clinical education for medical students. Materials and Methods. A 59-question panel survey was distributed to an entire medical school twice annually from September 2012 to May 2014. Student diet and attitudes and competencies (DACs) counseling patients on nutrition were compared using conditional multivariate logistic regression, propensity score-weighted, and longitudinal panel analyses. Inverse-variance weighted meta-analysis (IVWM) was used for planned subgroup analysis by year and treatment estimates across the three methods. Results. Of the available 954 students, 65.72% (n = 627) unique students were followed to produce 963 responses. 11.32% (n = 109) of responses were from 84 subjects who participated in the elective. SBME-DP versus traditional education significantly improved fruit and vegetable diet (OR = 1.38, 95% CI: 1.07–1.79, p = 0.013) and attitudes (OR = 1.81, 95% CI: 1.40–2.35, p < 0.001) and competencies (OR = 1.72, 95% CI: 1.54–1.92, p < 0.001). Conclusions. This study reports for the first time superiority longitudinally for SBME-DP style nutrition education for medical students which has since expanded to 13 schools. PMID:26435851

Tight interplay in early pregnancy between follistatin and anti-mullerian hormone in women with polycystic ovarian syndrome (PCOS).

PubMed

Köninger, Angela; Kampmeier, Antje; Mach, Pawel; Schmidt, Boerge; Strowitzki, Thomas; Kimmig, Rainer; Gellhaus, Alexandra

2018-05-01

Follistatin levels increase during the course of pregnancy and may play a role in ovarian arrest, reflected by the simultaneous decrease of anti-mullerian-hormone (AMH) levels. The aim of the study was to investigate AMH and follistatin levels during the hormonal window at the beginning of pregnancy. Since both parameters are described as deregulated in polycystic ovarian syndrome (PCOS), subgroup analysis of PCOS patients may additionally elucidate their interplay and effects on ovarian activity. Serum samples were retrospectively analyzed using the AMH Gen II ELISA and the Human Follistatin Quantikine ELISA Kit. Samples were collected longitudinally from 57 patients (32 with PCOS and 25 controls) before conception and during the first trimester. In 18 patients, measurements from the early and the late first trimester were available. Potential associations of AMH and follistatin levels with PCOS-related parameters were compared between the subgroups as well as longitudinally before and in the first trimester of pregnancy. For statistical analysis, the Spearman's correlation, Wilcoxon test, t test, Friedman test and multiple linear regression analysis was performed. In contrast to AMH, follistatin levels differed not between controls and PCOS patients before and in pregnancy. In both subgroups, AMH levels significantly decreased and follistatin levels significantly increased in longitudinally performed measurements before conceiving and in the first trimester of pregnancy. Follistatin levels are not suited as a biomarker for PCOS, but could be involved in suppressing ovarian activity, as reflected by AMH levels at the beginning of pregnancy.

Bumps in river profiles: uncertainty assessment and smoothing using quantile regression techniques

NASA Astrophysics Data System (ADS)

Schwanghart, Wolfgang; Scherler, Dirk

2017-12-01

The analysis of longitudinal river profiles is an important tool for studying landscape evolution. However, characterizing river profiles based on digital elevation models (DEMs) suffers from errors and artifacts that particularly prevail along valley bottoms. The aim of this study is to characterize uncertainties that arise from the analysis of river profiles derived from different, near-globally available DEMs. We devised new algorithms - quantile carving and the CRS algorithm - that rely on quantile regression to enable hydrological correction and the uncertainty quantification of river profiles. We find that globally available DEMs commonly overestimate river elevations in steep topography. The distributions of elevation errors become increasingly wider and right skewed if adjacent hillslope gradients are steep. Our analysis indicates that the AW3D DEM has the highest precision and lowest bias for the analysis of river profiles in mountainous topography. The new 12 m resolution TanDEM-X DEM has a very low precision, most likely due to the combined effect of steep valley walls and the presence of water surfaces in valley bottoms. Compared to the conventional approaches of carving and filling, we find that our new approach is able to reduce the elevation bias and errors in longitudinal river profiles.

Self-Concept and Academic Achievement: A Meta-Analysis of Longitudinal Relations

ERIC Educational Resources Information Center

Huang, Chiungjung

2011-01-01

The relation between self-concept and academic achievement was examined in 39 independent and longitudinal samples through the integration of meta-analysis and path analysis procedures. For relations with more than 3 independent samples, the mean observed correlations ranged from 0.20 to 0.27 between prior self-concept and subsequent academic…

Why Are Child Poverty Rates Higher in Britain Than in Germany? A Longitudinal Perspective. Working Paper.

ERIC Educational Resources Information Center

Jenkins, Stephen P.; Schluter, Christian

This study analyzed why child poverty rates were so much higher in Great Britain than in Western Germany during the 1990s, focusing on why child poverty exit rates were lower and child poverty entry rates were higher in Great Britain. Researchers used a form of decomposition analysis comparing cross-nationally the prevalence of events that…

Long-Term Effects of Child Death on Parents' Health-Related Quality of Life: A Dyadic Analysis

ERIC Educational Resources Information Center

Song, Jieun; Floyd, Frank J.; Seltzer, Marsha Mailick; Greenberg, Jan S.; Hong, Jinkuk

2010-01-01

This study examines the long-term effects of child death on bereaved parents' health-related quality of life (HRQoL). Using data from the Wisconsin Longitudinal Study, we compared 233 bereaved couples and 229 comparison couples (mean age = 65.11 years) and examined the life course effects of child death on parents' HRQoL. Variations in bereavement…

Capturing the Cumulative Effects of School Reform: An 11-Year Study of the Impacts of America's Choice on Student Achievement

ERIC Educational Resources Information Center

May, Henry; Supovitz, Jonathan A.

2006-01-01

This article presents the results of an 11-year longitudinal study of the impact of America's Choice comprehensive school reform (CSR) design on student learning gains in Rochester, New York. A quasi-experimental interrupted time-series approach using Bayesian hierarchical growth curve analysis with crossed random effects is used to compare the…

Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (86th, Kansas City, Missouri, July 30-August 2, 2003). Advertising Division.

ERIC Educational Resources Information Center

2003

The Advertising Division of the proceedings contains the following 20 papers: "Stereotyping the 'Model Minority': A Longitudinal Analysis of U.S. Primetime Network Commercials, Comparing Asian Female and Male Characters to Themselves and Others" (Dennis J. Ganahl, Liang Ge and Kwangok Kim); "Cultivation Effects of Television…

Network and Mutual Support for Parents Bereaved Following the Violent Deaths of Their 12- to 28-Year Old Children: A Longitudinal, Prospective Analysis.

ERIC Educational Resources Information Center

Murphy, Shirley A.; Lohan, Janet; Dimond, Margaret; Fan, Juanjuan

1998-01-01

Examines types and frequency of posttreatment contacts among bereaved parents who participated in an experimental support program. Compares those who reported high versus low social support and high versus low numbers of network confidants on selected outcome and coping variables. Number of network confidants did not significantly affect the…

The Use of Print Materials in the Internet Age: A Comparative Study of Academic Library Circulation Patterns

ERIC Educational Resources Information Center

Haley, Daniel Joseph

2010-01-01

The circulation records from 1997/98 to 2007/08 for UCLA and from 2000/01 to 2007/08 for Pasadena City College (PCC) were analyzed to examine patterns in the use of print materials during a period of increasingly available online digital information resources. The analysis included examinations of longitudinal circulation patterns broken down by…

A Comparison of Classroom and Online Asynchronous Problem-Based Learning for Students Undertaking Statistics Training as Part of a Public Health Masters Degree

ERIC Educational Resources Information Center

de Jong, N.; Verstegen, D. M. L.; Tan, F. E. S.; O'Connor, S. J.

2013-01-01

This case-study compared traditional, face-to-face classroom-based teaching with asynchronous online learning and teaching methods in two sets of students undertaking a problem-based learning module in the multilevel and exploratory factor analysis of longitudinal data as part of a Masters degree in Public Health at Maastricht University. Students…

Longitudinal Analysis of Student Performance between Host and Cooperating College Learners in the Dental Hygiene Program at Northcentral Technical College in Wausau, Wisconsin.

ERIC Educational Resources Information Center

Olmsted, Jodi L.

The academic performance of students enrolled in a distance education dental hygiene program at Northcentral Technical College (NTC) in Wausau, Wisconsin, was analyzed in a comparative, quasi-experimental study. The study sample consisted of five cohorts of program graduates (students graduating in 1997-2001). The experiment groups were divided…

Comparing the Psychometric Properties of Two Physical Activity Self-Efficacy Instruments in Urban, Adolescent Girls: Validity, Measurement Invariance, and Reliability

PubMed Central

Voskuil, Vicki R.; Pierce, Steven J.; Robbins, Lorraine B.

2017-01-01

Aims: This study compared the psychometric properties of two self-efficacy instruments related to physical activity. Factorial validity, cross-group and longitudinal invariance, and composite reliability were examined. Methods: Secondary analysis was conducted on data from a group randomized controlled trial investigating the effect of a 17-week intervention on increasing moderate to vigorous physical activity among 5th–8th grade girls (N = 1,012). Participants completed a 6-item Physical Activity Self-Efficacy Scale (PASE) and a 7-item Self-Efficacy for Exercise Behaviors Scale (SEEB) at baseline and post-intervention. Confirmatory factor analyses for intervention and control groups were conducted with Mplus Version 7.4 using robust weighted least squares estimation. Model fit was evaluated with the chi-square index, comparative fit index, and root mean square error of approximation. Composite reliability for latent factors with ordinal indicators was computed from Mplus output using SAS 9.3. Results: Mean age of the girls was 12.2 years (SD = 0.96). One-third of the girls were obese. Girls represented a diverse sample with over 50% indicating black race and an additional 19% identifying as mixed or other race. Both instruments demonstrated configural invariance for simultaneous analysis of cross-group and longitudinal invariance based on alternative fit indices. However, simultaneous metric invariance was not met for the PASE or the SEEB instruments. Partial metric invariance for the simultaneous analysis was achieved for the PASE with one factor loading identified as non-invariant. Partial metric invariance was not met for the SEEB. Longitudinal scalar invariance was achieved for both instruments in the control group but not the intervention group. Composite reliability for the PASE ranged from 0.772 to 0.842. Reliability for the SEEB ranged from 0.719 to 0.800 indicating higher reliability for the PASE. Reliability was more stable over time in the control group for both instruments. Conclusions: Results suggest that the intervention influenced how girls responded to indicator items. Neither of the instruments achieved simultaneous metric invariance making it difficult to assess mean differences in PA self-efficacy between groups. PMID:28824487

Robotic longitudinal pancreaticojejunostomy for chronic pancreatitis: Comparison of clinical outcomes and cost to the open approach.

PubMed

Kirks, Russell C; Lorimer, Patrick D; Fruscione, Michael; Cochran, Allyson; Baker, Erin H; Iannitti, David A; Vrochides, Dionisios; Martinie, John B

2017-09-01

This study compares clinical and cost outcomes of robot-assisted laparoscopic (RAL) and open longitudinal pancreaticojejunostomy (LPJ) for chronic pancreatitis. Clinical and cost data were retrospectively compared between open and RAL LPJ performed at a single center from 2008-2015. Twenty-six patients underwent LPJ: 19 open and 7 RAL. Two robot-assisted cases converted to open were included in the open group for analysis. Patients undergoing RAL LPJ had less intraoperative blood loss, a shorter surgical length of stay, and lower medication costs. Operation supply cost was higher in the RAL group. No difference in hospitalization cost was found. Versus the open approach, RAL LPJ performed for chronic pancreatitis shortens hospitalization and reduces medication costs; hospitalization costs are equivalent. A higher operative cost for RAL LPJ is mitigated by a shorter hospitalization. Decreased morbidity and healthcare resource economy support use of the robotic approach for LPJ when appropriate. Copyright © 2017 John Wiley & Sons, Ltd.

Comparison of torsional and microburst longitudinal phacoemulsification: a prospective, randomized, masked clinical trial.

PubMed

Vasavada, Abhay R; Raj, Shetal M; Patel, Udayan; Vasavada, Vaishali; Vasavada, Viraj

2010-01-01

To compare intraoperative performance and postoperative outcome of three phacoemulsification technologies in patients undergoing microcoaxial phacoemulsification through 2.2-mm corneal incisions. The prospective, randomized, single-masked study included 360 eyes randomly assigned to torsional (Infiniti Vision System; Alcon Laboratories, Fort Worth, TX), microburst with longitudinal (Infiniti), or microburst with longitudinal (Legacy Everest, Alcon Laboratories) ultrasound. Assessments included surgical clock time, fluid volume, and intraoperative complications, central corneal thickness on day 1 and months 1 and 3 postoperatively, and endothelial cell density at 3 months postoperatively. Comparisons among groups were conducted. Torsional ultrasound required significantly less surgical clock time and fluid volume than the other groups. There were no intraoperative complications. Change in central corneal thickness and endothelial cell loss was significantly lower in the torsional ultrasound group at all postoperative visits (P < .001, Kruskal-Wallis test) compared to microburst longitudinal ultrasound modalities. Torsional ultrasound demonstrated quantitatively superior intraoperative performance and showed less increase in corneal thickness and less endothelial cell loss compared to microburst longitudinal ultrasound. Copyright 2010, SLACK Incorporated.

Application of pattern mixture models to address missing data in longitudinal data analysis using SPSS.

PubMed

Son, Heesook; Friedmann, Erika; Thomas, Sue A

2012-01-01

Longitudinal studies are used in nursing research to examine changes over time in health indicators. Traditional approaches to longitudinal analysis of means, such as analysis of variance with repeated measures, are limited to analyzing complete cases. This limitation can lead to biased results due to withdrawal or data omission bias or to imputation of missing data, which can lead to bias toward the null if data are not missing completely at random. Pattern mixture models are useful to evaluate the informativeness of missing data and to adjust linear mixed model (LMM) analyses if missing data are informative. The aim of this study was to provide an example of statistical procedures for applying a pattern mixture model to evaluate the informativeness of missing data and conduct analyses of data with informative missingness in longitudinal studies using SPSS. The data set from the Patients' and Families' Psychological Response to Home Automated External Defibrillator Trial was used as an example to examine informativeness of missing data with pattern mixture models and to use a missing data pattern in analysis of longitudinal data. Prevention of withdrawal bias, omitted data bias, and bias toward the null in longitudinal LMMs requires the assessment of the informativeness of the occurrence of missing data. Missing data patterns can be incorporated as fixed effects into LMMs to evaluate the contribution of the presence of informative missingness to and control for the effects of missingness on outcomes. Pattern mixture models are a useful method to address the presence and effect of informative missingness in longitudinal studies.

Topological analysis of the brainstem of the bowfin, Amia calva.

PubMed

Heijdra, Y F; Nieuwenhuys, R

1994-01-01

This paper presents a survey of the cell masses in the brainstem of the generalized actinopterygian fish Amia calva, based on transversely cut Nissl-, Klüver-Barrera-, and Bodian-stained serial sections. This study is intended to serve a double purpose. First it forms part of a now almost complete series of publications on the structure of the brainstem in representative species of all groups of vertebrates. Within the framework of this comparative program the cell masses in the brainstem and their positional relations are analyzed in the light of the Herrick-Johnston concept; according to this the brainstem nuclei are arranged in four longitudinal, functional zones or columns, the boundaries of which are marked by ventricular sulci. The procedure employed in this analysis essentially involves two steps: first, the cell masses and large individual cells are projected upon the ventricular surface, and next, the ventricular surface is flattened out, that is, subjected to a one-to-one continuous topological transformation (Nieuwenhuys [1974] J. Comp. Neurol. 156:255-267). The second purpose of the present paper is to provide a cytoarchitectonic basis for experimental analysis of the fiber connectivity in the brainstem of Amia. Five longitudinal sulci--the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis, and the sulcus lateralis mesencephali--could be distinguished. Some shorter grooves, present in the isthmal region, clearly deviate from the overall longitudinal pattern of the other sulci. Although in Amia most neuronal perikarya are contained within a diffuse periventricular gray, 40 cell masses could be delineated: Eight of these are primary efferent or motor nuclei, 10 are primary afferent or sensory centers, seven are considered to be components of the reticular formation, and the remaining 15 may be interpreted as "relay" nuclei. The topological analysis yielded the following results. In the rhombencephalon the gray matter is arranged in four longitudinal columns or areas, termed area ventralis, area intermedioventralis, area intermediodorsalis, and area dorsalis. The sulcus intermedius ventralis, the sulcus limitans, and the sulcus intermedius dorsalis mark the boundaries between these morphological entities. These longitudinal areas coincide largely, but not entirely, with the functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the viscerosensory nucleus of the solitary tract, several general somatosensory and special somatosensory nuclei.(ABSTRACT TRUNCATED AT 400 WORDS)

Longitudinal Changes in Access to Health Care by Immigrant Status among Older Adults: The Importance of Health Insurance as a Mediator

ERIC Educational Resources Information Center

Choi, Sunha

2011-01-01

Purpose: This longitudinal study examined the role of health insurance in access to health care among older immigrants. Design and Methods: Using data from the Second Longitudinal Study of Aging, the longitudinal trajectories of having a usual source of care were compared between 3 groups (all 70+ years): (a) late-life immigrants with less than 15…

A Longitudinal Analysis of the Causal Factors in Major Maritime Accidents in the USA and Canada (1996-2006)

NASA Technical Reports Server (NTRS)

Johnson, C. W.; Holloway, C, M.

2007-01-01

Accident reports provide important insights into the causes and contributory factors leading to particular adverse events. In contrast, this paper provides an analysis that extends across the findings presented over ten years investigations into maritime accidents by both the US National Transportation Safety Board (NTSB) and Canadian Transportation Safety Board (TSB). The purpose of the study was to assess the comparative frequency of a range of causal factors in the reporting of adverse events. In order to communicate our findings, we introduce J-H graphs as a means of representing the proportion of causes and contributory factors associated with human error, equipment failure and other high level classifications in longitudinal studies of accident reports. Our results suggest the proportion of causal and contributory factors attributable to direct human error may be very much smaller than has been suggested elsewhere in the human factors literature. In contrast, more attention should be paid to wider systemic issues, including the managerial and regulatory context of maritime operations.

Participants' Accounts on Their Decision to Join a Cohort Study With an Attached Biobank: A Qualitative Content Analysis Study Within Two German Studies.

PubMed

Nobile, Hélène; Bergmann, Manuela M; Moldenhauer, Jennifer; Borry, Pascal

2016-07-01

Reliable participation and sustained retention rates are crucial in longitudinal studies involving human subjects and biomaterials. Understanding the decision to enroll is an essential step to develop adequate strategies promoting long-term participation. Semi-structured interviews were implemented with newly recruited and long-term participants randomly drawn from two ongoing longitudinal studies with a biobank component in Germany. Iterative qualitative content analysis was applied to the transcribed interviews. Participants (n = 31) expressed their decision to enroll or remain in the study as the result of the complex interplay of individual factors, institutional cues, study-related features, and societal dynamics. Different forms of trust were identified as central within the elements used to explain participation and could be compared to Dibben, Morris, and Lean's dynamic model of interpersonal trust. Given these high levels of trust, an investigation of the morality of the trustful relationship at stake between participants and research(ers) is warranted. © The Author(s) 2016.

A comparative analysis of longitudinal computed tomography and histopathology for evaluating the potential of mesenchymal stem cells in mitigating radiation-induced pulmonary fibrosis.

PubMed

Perez, Jessica R; Lee, Sangkyu; Ybarra, Norma; Maria, Ola; Serban, Monica; Jeyaseelan, Krishinima; Wang, Li Ming; Seuntjens, Jan; Naqa, Issam El

2017-08-22

Radiation-induced pulmonary fibrosis (RIPF) is a debilitating side effect that occurs in up to 30% of thoracic irradiations in breast and lung cancer patients. RIPF remains a major limiting factor to dose escalation and an obstacle to applying more promising new treatments for cancer cure. Limited treatment options are available to mitigate RIPF once it occurs, but recently, mesenchymal stem cells (MSCs) and a drug treatment stimulating endogenous stem cells (GM-CSF) have been investigated for their potential in preventing this disease onset. In a pre-clinical rat model, we contrasted the application of longitudinal computed tomography (CT) imaging and classical histopathology to quantify RIPF and to evaluate the potential of MSCs in mitigating RIPF. Our results on histology demonstrate promises when MSCs are injected endotracheally (but not intravenously). While our CT analysis highlights the potential of GM-CSF treatment. Advantages and limitations of both analytical methods are contrasted in the context of RIPF.

[Comparative study of N, P output and eutrophication risk in runoff water in cross ridge and longitudinal ridge].

PubMed

Yu, Xing-Xiu; Ma, Qian; Liu, Qian-Jin; Lü, Guo-An

2011-02-01

Field in-situ rainfall simulation tests with two rainfall intensities (40 mm x h(-1) and 70 mm x h(-1)), which were conducted at typical sloping cropland in Yimeng mountainous area, were designed to analyze the output characteristics of dissolved inorganic nitrogen, Inorganic-N (NO3(-)-N, NH4(+) -N) and dissolved phosphorus (DP) in runoff water, as well as to compare the eutrophication risk in this water by calculating three ratios of Inorganic-N/DP, NO3(-) -N/DP, and NH4(+)-N/DP, respectively, in cross ridge and longitudinal ridge tillage methods. Results showed that, under the same rainfall intensity, the DP level in runoff water was higher in cross ridge than longitudinal ridge, while the change of different Inorganic-N level between the two tillage methods were not consistent. Cross ridge could effectively reduce runoff and the output rate of Inorganic-N and DP when compared to the longitudinal ridge tillage, which would be more outstanding with the increases of rainfall intensities. The losses of Inorganic-N and DP in runoff water were 43% and 5% less, respectively, in cross ridge than longitudinal ridge at the 40 mm x h(-1) rainfall intensity, and were 68% and 55%, respectively, at 70 mm x h(-1). The higher Inorganic-N/DP and NO3(-) -N/DP ratios suggest that runoff water from either cross ridge or longitudinal ridge tillage have a certain eutrophication risk, which present an increasing trend during the precipitation-runoff process. Compared with longitudinal ridge, cross ridge can not only hinder the increasing trend of eutrophication risk, but also can significantly lower it, and thus effectively reduce the effect of sloping cropland runoff on the eutrophication processes of receiving waters.

Comparing meta-analysis and ecological-longitudinal analysis in time-series studies. A case study of the effects of air pollution on mortality in three Spanish cities.

PubMed

Saez, M; Figueiras, A; Ballester, F; Pérez-Hoyos, S; Ocaña, R; Tobías, A

2001-06-01

The objective of this paper is to introduce a different approach, called the ecological-longitudinal, to carrying out pooled analysis in time series ecological studies. Because it gives a larger number of data points and, hence, increases the statistical power of the analysis, this approach, unlike conventional ones, allows the complementation of aspects such as accommodation of random effect models, of lags, of interaction between pollutants and between pollutants and meteorological variables, that are hardly implemented in conventional approaches. The approach is illustrated by providing quantitative estimates of the short-term effects of air pollution on mortality in three Spanish cities, Barcelona, Valencia and Vigo, for the period 1992-1994. Because the dependent variable was a count, a Poisson generalised linear model was first specified. Several modelling issues are worth mentioning. Firstly, because the relations between mortality and explanatory variables were non-linear, cubic splines were used for covariate control, leading to a generalised additive model, GAM. Secondly, the effects of the predictors on the response were allowed to occur with some lag. Thirdly, the residual autocorrelation, because of imperfect control, was controlled for by means of an autoregressive Poisson GAM. Finally, the longitudinal design demanded the consideration of the existence of individual heterogeneity, requiring the consideration of mixed models. The estimates of the relative risks obtained from the individual analyses varied across cities, particularly those associated with sulphur dioxide. The highest relative risks corresponded to black smoke in Valencia. These estimates were higher than those obtained from the ecological-longitudinal analysis. Relative risks estimated from this latter analysis were practically identical across cities, 1.00638 (95% confidence intervals 1.0002, 1.0011) for a black smoke increase of 10 microg/m(3) and 1.00415 (95% CI 1.0001, 1.0007) for a increase of 10 microg/m(3) of sulphur dioxide. Because the statistical power is higher than in the individual analysis more interactions were statistically significant, especially those among air pollutants and meteorological variables. Air pollutant levels were related to mortality in the three cities of the study, Barcelona, Valencia and Vigo. These results were consistent with similar studies in other cities, with other multicentric studies and coherent with both, previous individual, for each city, and multicentric studies for all three cities.

A comparison of longitudinal and transverse approaches to ultrasound-guided axillary vein cannulation by experienced operators

PubMed Central

He, Yi-Zhou; Zhong, Ming; Wu, Wei; Song, Jie-Qiong

2017-01-01

Background The axillary vein is an easily accessible vessel that can be used for ultrasound-guided central vascular access and offers an alternative to the internal jugular and subclavian veins. The objective of this study was to identify which transducer orientation, longitudinal or transverse, is better for imaging the axillary vein with ultrasound. Methods We analyzed 236 patients who had undergone central venous cannulation of axillary vein in this retrospective study. Patients were divided into two groups, the longitudinal approach group (n=120) and transverse approach group (n=116). Recorded the one-attempt success rate, operation time, arterial puncture rate and pneumothorax rate. We perform chest radiography to confirm pneumothorax on all patients. We compared the one-attempt success rate, operation time, arterial puncture rate and pneumothorax rate between the two groups. Results The two groups were comparable with clinical characters of patients. The overall success rates of the longitudinal group and the transverse group were both 100%. The rate of one-attempt success in the longitudinal approach group is higher than the transverse approach group (91.7% vs. 82.8%, P=0.040). The transverse approach group had shorter operation time than the longitudinal group (184.7±8.1 vs. 287.5±19.6 seconds, P=0.000). The two groups had lower postoperative complications. Arterial puncture occurred in 1 of 120 longitudinal and 2 of 116 transverse attempts and this difference was no significant (P=0.541). No pneumothorax occurred in the two groups. Conclusions The longitudinal approach during ultrasound-guided axillary vein cannulation is associated with greater one-attempt success rate compared with the transverse approach by experienced operators. The transverse approach has shorter operation time. The two groups have lower postoperative complications and are comparable with pneumothorax and arterial puncture. PMID:28523170

Longitudinal Course of Depression Scores with and without Insomnia in Non-Depressed Individuals: A 6-Year Follow-Up Longitudinal Study in a Korean Cohort

PubMed Central

Suh, Sooyeon; Kim, Hyun; Yang, Hae-Chung; Cho, Eo Rin; Lee, Seung Ku; Shin, Chol

2013-01-01

Study Objective: This is a population-based longitudinal study that followed insomnia symptoms over a 6-year period in non-depressed individuals. The purpose of the study was to (1) investigate the longitudinal course of depression based on number of insomnia episodes; and (2) describe longitudinal associations between insomnia and depression, and insomnia and suicidal ideation. Design: Population-based longitudinal study. Setting: Community-based sample from the Korean Genome and Epidemiology Study (KoGES). Participants: 1,282 non-depressed individuals (44% male, mean age 52.3 ± 7.14 years) Measurements and Results: This study prospectively assessed insomnia, depression, and suicidal ideation with 4 time points. Individuals were classified into no insomnia (NI), single episode insomnia (SEI), and persistent insomnia (PI; ≥ insomnia at 2+ time points) groups based on number of times insomnia was indicated. Mixed effects modeling indicated that depression scores increased significantly faster in the PI group compared to the NI (P < 0.001) and SEI (P = 0.02) groups. Additionally, the PI group had significantly increased odds of depression as compared to NI or SEI (OR 2.44, P = 0.001) groups, with 18.7% meeting criteria for depression compared to the NI (5.3%) and SEI (11.6%) groups at end point. The PI group also had significantly increased odds of suicidal ideation as compared to NI or SEI (OR 1.86, P = 0.002) groups. Conclusions: Persistent insomnia significantly increases the rate in which depression occurs over time in non-depressed individuals, which ultimately leads to higher risk for depression. Additionally, having persistent insomnia also increased the risk of suicidal ideation. Citation: Suh S; Kim H; Yang HC; Cho ER; Lee SK; Shin C. Longitudinal course of depression scores with and without insomnia in non-depressed individuals: a 6-year follow-up longitudinal study in a Korean cohort. SLEEP 2013;36(3):369-376. PMID:23449814

User’s Guide for the Longitudinal Scalogram Analysis Program

DTIC Science & Technology

1991-01-01

cannabis, pills, psychedelics , cocaine, and heroin. The LSA analysis was restricted to these respondents (n = 791), because complete information about...Total n = 791. 0 = not passed, I = passed. Items am legal drugs, cannabis, pills, psychedelics , cocaine, and heroin. Asterisks denote longitudinal

Association of atopic diseases and attention-deficit/hyperactivity disorder: A systematic review and meta-analyses.

PubMed

Schans, Jurjen van der; Çiçek, Rukiye; de Vries, Tjalling W; Hak, Eelko; Hoekstra, Pieter J

2017-03-01

Over the last decades, the hypothesis has been raised that an atopic response could lead to the development of attention-deficit/hyperactivity disorder (ADHD). This study systematically reviews the observational cross-sectional and longitudinal studies that assessed the association between atopic disorders including asthma, atopic eczema, allergic rhinitis, and ADHD in children and adolescents. For longitudinal studies, a weighted Mantel-Haenszel odds ratio of these associations was estimated. The majority of cross-sectional and longitudinal studies reported a statistically significant positive association. The meta-analysis of longitudinal studies revealed an overall weighted odds ratio for asthma of 1.34 (95% confidence interval [CI] 1.24-1.44), 1.32 (95% CI 1.20-1.45) for atopic eczema, and 1.52 (95% CI 1.43-1.63) for allergic rhinitis. Heterogeneity of study data was low (I 2 : 0%, p=0.46 and p=0.64, respectively) for both studies examining asthma and eczema but substantial for rhinitis studies (I 2 : 82%, p=0.004). This current systematic review provides strong evidence that ADHD is associated with atopic diseases and that individuals have a 30% to 50% greater chance of developing ADHD compared to controls. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bayesian analysis of longitudinal dyadic data with informative missing data using a dyadic shared-parameter model.

PubMed

Ahn, Jaeil; Morita, Satoshi; Wang, Wenyi; Yuan, Ying

2017-01-01

Analyzing longitudinal dyadic data is a challenging task due to the complicated correlations from repeated measurements and within-dyad interdependence, as well as potentially informative (or non-ignorable) missing data. We propose a dyadic shared-parameter model to analyze longitudinal dyadic data with ordinal outcomes and informative intermittent missing data and dropouts. We model the longitudinal measurement process using a proportional odds model, which accommodates the within-dyad interdependence using the concept of the actor-partner interdependence effects, as well as dyad-specific random effects. We model informative dropouts and intermittent missing data using a transition model, which shares the same set of random effects as the longitudinal measurement model. We evaluate the performance of the proposed method through extensive simulation studies. As our approach relies on some untestable assumptions on the missing data mechanism, we perform sensitivity analyses to evaluate how the analysis results change when the missing data mechanism is misspecified. We demonstrate our method using a longitudinal dyadic study of metastatic breast cancer.

Matrix-assisted laser desorption/ionization mass spectrometric imaging for the rapid segmental analysis of methamphetamine in a single hair using umbelliferone as a matrix.

PubMed

Wang, Hang; Wang, Ying

2017-07-04

Segmental hair analysis offers a longer period for retrospective drug detection than blood or urine. Hair is a keratinous fiber and is strongly hydrophobic. The embedding of drugs in hydrophobic hair at low concentrations makes it difficult for extraction and detection with matrix-assisted laser desorption/ionization (MALDI) coupled with mass spectrometric imaging (MSI). In this study, a single scalp hair was longitudinally cut with a cryostat section to a length of 4 mm and fixed onto a stainless steel MALDI plate. Umbelliferone was used as a new hydrophobic matrix to enrich and assist the ionization efficiency of methamphetamine in the hair sample. MALDI-Fourier transform ion cyclotron resonance (FTICR)-MS profiling and imaging were performed for direct detection and mapping of methamphetamine on the longitudinal sections of the single hair sample in positive ion mode. Using MALDI-MSI, the distribution of methamphetamine was observed throughout five longitudinally sectioned hair samples from a drug abuser. The changes of methamphetamine were also semi-quantified by comparing the ratios of methamphetamine/internal standard (I.S). This method improves the detection sensitivity of target drugs embedded in a hair matrix for imaging with mass spectrometry. The method could provide a detection level of methamphetamine down to a nanogram per milligram incorporated into hair. The results were also compared with the conventional high performance liquid chromatography -tandem mass spectrometry (HPLC-MS/MS) method. Changes in the imaging results over time by the MSI method showed good semi-quantitative correlation to the results from the HPLC-MS/MS method. This study provides a powerful tool for drug abuse control and forensic medicine analysis in a narrow time frame, and a reduction in the sample amount required. Copyright © 2017 Elsevier B.V. All rights reserved.

Factors associated with repeated refusal to participate in longitudinal population-based HIV surveillance in rural South Africa: an observational study, regression analyses

PubMed Central

Giordano, Katie; McGrath, Nuala; Snow, Rachel; Harlow, Siobán; Newell, Marie-Louise

2014-01-01

Background For many estimation purposes, individuals who repeatedly refuse to participate in longitudinal HIV surveillance pose a bigger threat to valid inferences than individuals who participate at least occasionally. We investigate the determinants of repeated refusal to consent to HIV testing in a population-based longitudinal surveillance in rural South Africa. Methods We used data from two years (2005 & 2006) of the annual HIV surveillance conducted by the Africa Centre for Health and Population Studies, linking the HIV surveillance data to demographic and socioeconomic data. The outcome for the analysis was “repeated refusal”. Demographic variables included sex, age, highest educational attainment, and place of residence. We also included a measure of wealth and the variable “ever had sex”. To compare the association of each variable with the outcome, unadjusted odds ratios and standard errors were estimated. Multivariable logistic regression was used to estimate adjusted odds ratios and their standard errors. Data were analyzed using STATA 10.0. Results Of 15,557 eligible individuals, 46% refused to test for HIV in both rounds. Males were significantly more likely than females to repeatedly refuse testing. Holding all other variables constant, individuals in the middle age groups were more likely to repeatedly refuse testing compared with younger and older age groups. The odds of repeated refusal increased with increasing level of education and relative wealth. People living in urban areas were significantly more likely to repeatedly refuse an HIV test than people living in peri-urban or rural areas. Compared to those who had ever had sex, both males and females who had not yet had sex were significantly more likely to refuse to participate. Conclusions The likelihood of repeated refusal to test for HIV in this longitudinal surveillance increases with education, wealth, urbanization, and primary sexual abstinence. Since the factors determining repeated HIV testing refusal are likely associated with HIV status, it is critical that selection effects are controlled for in the analysis of HIV surveillance data. Interventions to increase consent to HIV testing should consider targeting the relatively well educated and wealthy, people in urban areas, and individuals who have not yet sexually debuted. PMID:25621095

Preliminary Rural Analysis of the Early Childhood Longitudinal Study--Kindergarten Cohort. Rural Early Childhood Brief Number 2

ERIC Educational Resources Information Center

National Center for Rural Early Childhood Learning Initiatives - Mississippi State University Early Childhood Institute, 2005

2005-01-01

This brief introduces the first results from a rural analysis of selected national datasets. Provided are key findings concerning kindergarten readiness of rural children from an analysis of the Kindergarten Cohort of the Early Childhood Longitudinal Study (ECLS). Future briefs will summarize the findings concerning the health of the Kindergarten…

Longitudinal influence of alcohol and marijuana use on academic performance in college students

PubMed Central

Meda, Shashwath A.; Gueorguieva, Ralitza V.; Pittman, Brian; Rosen, Rivkah R.; Aslanzadeh, Farah; Tennen, Howard; Leen, Samantha; Hawkins, Keith; Raskin, Sarah; Wood, Rebecca M.; Austad, Carol S.; Dager, Alecia; Fallahi, Carolyn; Pearlson, Godfrey D.

2017-01-01

Background Alcohol and marijuana are the two most abused substances in US colleges. However, research on the combined influence (cross sectional or longitudinal) of these substances on academic performance is currently scant. Methods Data were derived from the longitudinal 2-year Brain and Alcohol Research in College Students (BARCS) study including 1142 freshman students who completed monthly marijuana use and alcohol consumption surveys. Subjects were classified into data-driven groups based on their alcohol and marijuana consumption. A linear mixed-model (LMM) was employed using this grouping factor to predict grade point average (GPA), adjusted for a variety of socio-demographic and clinical factors. Results Three data-driven clusters emerged: 1) No/low users of both, 2) medium-high alcohol/no-low marijuana, and 3) medium-high users of both substances. Individual cluster derivations between consecutive semesters remained stable. No significant interaction between clusters and semester (time) was noted. Post-hoc analysis suggest that at the outset, compared to sober peers, students using moderate to high levels of alcohol and low marijuana demonstrate lower GPAs, but this difference becomes non-significant over time. In contrast, students consuming both substances at moderate-to-high levels score significantly lower at both the outset and across the 2-year investigation period. Our follow-up analysis also indicate that when students curtailed their substance use over time they had significantly higher academic GPA compared to those who remained stable in their substance use patterns over the two year period. Conclusions Overall, our study validates and extends the current literature by providing important implications of concurrent alcohol and marijuana use on academic achievement in college. PMID:28273162

The Willowbrook futures project: a longitudinal analysis of person-centered planning.

PubMed

Holburn, Steve; Jacobson, John W; Schwartz, Allen A; Flory, Michael J; Vietze, Peter M

2004-01-01

We conducted a longitudinal comparative evaluation of person-centered planning processes and outcomes for 20 individuals with intellectual disabilities and problem behavior (former residents of Willowbrook) and a matched contrast group, who received traditional interdisciplinary service planning (ISP). At the inception of the study, all participants were living in one of four other developmental centers (institutions) in New York City. Process and outcome data obtained from questionnaires completed by team members approximately every 8 months at four time periods showed that the rate of improvement in both person-centered planning process and outcomes for the intervention group was significantly greater than that of the comparison group. Eighteen of 19 person-centered planning participants moved to community living arrangements, as did 5 of 18 in the contrast group.

Physical exercise and cognitive function across the life span: Results of a nationwide population-based study.

PubMed

Gaertner, Beate; Buttery, Amanda K; Finger, Jonas D; Wolfsgruber, Steffen; Wagner, Michael; Busch, Markus A

2018-05-01

To examine cross-sectional and longitudinal associations between physical exercise and cognitive function across different age groups in a nationwide population-based sample of adults aged 18-79 years in Germany. Cross-sectional/prospective. Cognitive function was assessed in the mental health module of the German Health Interview and Examination Survey for Adults (DEGS1-MH, 2009-2012, n=3535), using a comprehensive neuropsychological test battery. Cognitive domain scores for executive function and memory were derived from confirmatory factor analysis. Regular physical exercise in the last three months was assessed by self-report and defined as no exercise, <2 and ≥2h (hours) of exercise per week. A subgroup of DEGS1-MH participants who previously participated in the German National Health Interview and Examination Survey 1998 (GNHIES98, 1997-1999, n=1624) enabled longitudinal analyses with a mean follow-up of 12.4 years. Compared to no exercise, more weekly physical exercise was associated with better executive function in cross-sectional (<2h: β=0.12; ≥2h: β=0.17; all p<0.001) and longitudinal analyses (<2h: β=0.14, p<0.001; ≥2h: β=0.15, p=0.001) using linear regression models adjusted for age, sex, education, smoking, alcohol consumption, fruit and vegetable consumption and obesity. Slightly weaker associations were found for memory in cross-sectional (<2h: β=0.08, p=0.009; ≥2h: β=0.08, p=0.026) and longitudinal analysis (<2h: β=0.09, p=0.036; ≥2h: β=0.08, p=0.114). There was no evidence of interaction between physical exercise and age. Higher levels of physical exercise were associated with better executive function and memory in cross-sectional and longitudinal analyses with no evidence for differential effects by age. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Comparison of three longitudinal analysis models for the health-related quality of life in oncology: a simulation study.

PubMed

Anota, Amélie; Barbieri, Antoine; Savina, Marion; Pam, Alhousseiny; Gourgou-Bourgade, Sophie; Bonnetain, Franck; Bascoul-Mollevi, Caroline

2014-12-31

Health-Related Quality of Life (HRQoL) is an important endpoint in oncology clinical trials aiming to investigate the clinical benefit of new therapeutic strategies for the patient. However, the longitudinal analysis of HRQoL remains complex and unstandardized. There is clearly a need to propose accessible statistical methods and meaningful results for clinicians. The objective of this study was to compare three strategies for longitudinal analyses of HRQoL data in oncology clinical trials through a simulation study. The methods proposed were: the score and mixed model (SM); a survival analysis approach based on the time to HRQoL score deterioration (TTD); and the longitudinal partial credit model (LPCM). Simulations compared the methods in terms of type I error and statistical power of the test of an interaction effect between treatment arm and time. Several simulation scenarios were explored based on the EORTC HRQoL questionnaires and varying the number of patients (100, 200 or 300), items (1, 2 or 4) and response categories per item (4 or 7). Five or 10 measurement times were considered, with correlations ranging from low to high between each measure. The impact of informative missing data on these methods was also studied to reflect the reality of most clinical trials. With complete data, the type I error rate was close to the expected value (5%) for all methods, while the SM method was the most powerful method, followed by LPCM. The power of TTD is low for single-item dimensions, because only four possible values exist for the score. When the number of items increases, the power of the SM approach remained stable, those of the TTD method increases while the power of LPCM remained stable. With 10 measurement times, the LPCM was less efficient. With informative missing data, the statistical power of SM and TTD tended to decrease, while that of LPCM tended to increase. To conclude, the SM model was the most powerful model, irrespective of the scenario considered, and the presence or not of missing data. The TTD method should be avoided for single-item dimensions of the EORTC questionnaire. While the LPCM model was more adapted to this kind of data, it was less efficient than the SM model. These results warrant validation through comparisons on real data.

Disability Measurement for Korean Community-Dwelling Adults With Stroke: Item-Level Psychometric Analysis of the Korean Longitudinal Study of Ageing

PubMed Central

2018-01-01

Objective To investigate the psychometric properties of the activities of daily living (ADL) instrument used in the analysis of Korean Longitudinal Study of Ageing (KLoSA) dataset. Methods A retrospective study was carried out involving 2006 KLoSA records of community-dwelling adults diagnosed with stroke. The ADL instrument used for the analysis of KLoSA included 17 items, which were analyzed using Rasch modeling to develop a robust outcome measure. The unidimensionality of the ADL instrument was examined based on confirmatory factor analysis with a one-factor model. Item-level psychometric analysis of the ADL instrument included fit statistics, internal consistency, precision, and the item difficulty hierarchy. Results The study sample included a total of 201 community-dwelling adults (1.5% of the Korean population with an age over 45 years; mean age=70.0 years, SD=9.7) having a history of stroke. The ADL instrument demonstrated unidimensional construct. Two misfit items, money management (mean square [MnSq]=1.56, standardized Z-statistics [ZSTD]=2.3) and phone use (MnSq=1.78, ZSTD=2.3) were removed from the analysis. The remaining 15 items demonstrated good item fit, high internal consistency (person reliability=0.91), and good precision (person strata=3.48). The instrument precisely estimated person measures within a wide range of theta (−4.75 logits < θ < 3.97 logits) and a reliability of 0.9, with a conceptual hierarchy of item difficulty. Conclusion The findings indicate that the 15 ADL items met Rasch expectations of unidimensionality and demonstrated good psychometric properties. It is proposed that the validated ADL instrument can be used as a primary outcome measure for assessing longitudinal disability trajectories in the Korean adult population and can be employed for comparative analysis of international disability across national aging studies. PMID:29765888

Idiopathic Pulmonary Fibrosis: Data-driven Textural Analysis of Extent of Fibrosis at Baseline and 15-Month Follow-up.

PubMed

Humphries, Stephen M; Yagihashi, Kunihiro; Huckleberry, Jason; Rho, Byung-Hak; Schroeder, Joyce D; Strand, Matthew; Schwarz, Marvin I; Flaherty, Kevin R; Kazerooni, Ella A; van Beek, Edwin J R; Lynch, David A

2017-10-01

Purpose To evaluate associations between pulmonary function and both quantitative analysis and visual assessment of thin-section computed tomography (CT) images at baseline and at 15-month follow-up in subjects with idiopathic pulmonary fibrosis (IPF). Materials and Methods This retrospective analysis of preexisting anonymized data, collected prospectively between 2007 and 2013 in a HIPAA-compliant study, was exempt from additional institutional review board approval. The extent of lung fibrosis at baseline inspiratory chest CT in 280 subjects enrolled in the IPF Network was evaluated. Visual analysis was performed by using a semiquantitative scoring system. Computer-based quantitative analysis included CT histogram-based measurements and a data-driven textural analysis (DTA). Follow-up CT images in 72 of these subjects were also analyzed. Univariate comparisons were performed by using Spearman rank correlation. Multivariate and longitudinal analyses were performed by using a linear mixed model approach, in which models were compared by using asymptotic χ 2 tests. Results At baseline, all CT-derived measures showed moderate significant correlation (P < .001) with pulmonary function. At follow-up CT, changes in DTA scores showed significant correlation with changes in both forced vital capacity percentage predicted (ρ = -0.41, P < .001) and diffusing capacity for carbon monoxide percentage predicted (ρ = -0.40, P < .001). Asymptotic χ 2 tests showed that inclusion of DTA score significantly improved fit of both baseline and longitudinal linear mixed models in the prediction of pulmonary function (P < .001 for both). Conclusion When compared with semiquantitative visual assessment and CT histogram-based measurements, DTA score provides additional information that can be used to predict diminished function. Automatic quantification of lung fibrosis at CT yields an index of severity that correlates with visual assessment and functional change in subjects with IPF. © RSNA, 2017.

Accounting for the dead in the longitudinal analysis of income-related health inequalities

PubMed Central

Petrie, Dennis; Allanson, Paul; Gerdtham, Ulf-G.

2011-01-01

This paper develops an accounting framework to consider the effect of deaths on the longitudinal analysis of income-related health inequalities. Ignoring deaths or using Inverse Probability Weights (IPWs) to re-weight the sample for mortality-related attrition can produce misleading results. Incorporating deaths into the longitudinal analysis of income-related health inequalities provides a more complete picture in terms of the evaluation of health changes in respect to socioeconomic status. We illustrate our work by investigating health mobility from 1999 till 2004 using the British Household Panel Survey (BHPS). We show that for Scottish males explicitly accounting for the dead rather than using IPWs to account for mortality-related attrition changes the direction of the relationship between relative health changes and initial income position, from negative to positive, while for other groups it significantly increases the strength of the positive relationship. Incorporating the dead may be vital in the longitudinal analysis of health inequalities. PMID:21820193

Accounting for the dead in the longitudinal analysis of income-related health inequalities.

PubMed

Petrie, Dennis; Allanson, Paul; Gerdtham, Ulf G

2011-09-01

This paper develops an accounting framework to consider the effect of deaths on the longitudinal analysis of income-related health inequalities. Ignoring deaths or using Inverse Probability Weights (IPWs) to re-weight the sample for mortality-related attrition can produce misleading results. Incorporating deaths into the longitudinal analysis of income-related health inequalities provides a more complete picture in terms of the evaluation of health changes in respect to socioeconomic status. We illustrate our work by investigating health mobility from 1999 till 2004 using the British Household Panel Survey (BHPS). We show that for Scottish males explicitly accounting for the dead rather than using IPWs to account for mortality-related attrition changes the direction of the relationship between relative health changes and initial income position, from negative to positive, while for other groups it significantly increases the strength of the positive relationship. Incorporating the dead may be vital in the longitudinal analysis of health inequalities. Copyright © 2011 Elsevier B.V. All rights reserved.

A biomechanical comparison of three sternotomy closure techniques.

PubMed

Cohen, David J; Griffin, Lanny V

2002-02-01

A biomechanical study of three sternotomy closure techniques (figure-of-eight stainless-steel wires, Pectofix Dynamic Sternal Fixation [DSF] stainless-steel plates, and figure-of-eight stainless-steel cables) was conducted to compare strength and stiffness variables in three clinically relevant loading modes (anterior-posterior shear, longitudinal shear, and lateral distraction). All tests were conducted on polyurethane foam sternal models that simulate the properties of cancellous bone. Each model was divided longitudinally and reconstructed using one of the sternotomy closure repair techniques. Tests were performed using a materials testing system that applies a continuously increasing amount of force in one direction to the model until it catastrophically breaks. A total of six trials of each fixation type in each of three test groups were prepared and tested, for a total of 54 tests. Strength and stiffness variables as well as a post-yield analysis of failure were evaluated. Sternums repaired using the DSF plate system are a more rigid construct than sternums repaired using the stainless-steel wires or cables in the distraction and transverse shear modes and they are not significantly different from sternums repaired with wires or cables in the longitudinal shear mode. The DSF plate system offers a 25% improvement in resistance to failure (yield) compared to wires when a transverse shear force is applied to the model. The cable system had a higher resistance to failure than the wires in all modes although the differences were not statistically significant. Additionally, the DSF plate system provides substantial reduction of the implant's cutting into the sternal model under loading as evidenced by the post-yield displacement when compared with either cables or wires for the distraction and longitudinal shear modes. For the transverse shear mode, the cables or wires would completely fail at the load for which cutting begins for the DSF. Both the DSF plate system and the stainless-steel cable system offer important advantages over figure-of-eight wire for sternal closure.

The impact of different strategies to handle missing data on both precision and bias in a drug safety study: a multidatabase multinational population-based cohort study

PubMed Central

Martín-Merino, Elisa; Calderón-Larrañaga, Amaia; Hawley, Samuel; Poblador-Plou, Beatriz; Llorente-García, Ana; Petersen, Irene; Prieto-Alhambra, Daniel

2018-01-01

Background Missing data are often an issue in electronic medical records (EMRs) research. However, there are many ways that people deal with missing data in drug safety studies. Aim To compare the risk estimates resulting from different strategies for the handling of missing data in the study of venous thromboembolism (VTE) risk associated with antiosteoporotic medications (AOM). Methods New users of AOM (alendronic acid, other bisphosphonates, strontium ranelate, selective estrogen receptor modulators, teriparatide, or denosumab) aged ≥50 years during 1998–2014 were identified in two Spanish (the Base de datos para la Investigación Farmacoepidemiológica en Atención Primaria [BIFAP] and EpiChron cohort) and one UK (Clinical Practice Research Datalink [CPRD]) EMR. Hazard ratios (HRs) according to AOM (with alendronic acid as reference) were calculated adjusting for VTE risk factors, body mass index (that was missing in 61% of patients included in the three databases), and smoking (that was missing in 23% of patients) in the year of AOM therapy initiation. HRs and standard errors obtained using cross-sectional multiple imputation (MI) (reference method) were compared to complete case (CC) analysis – using only patients with complete data – and longitudinal MI – adding to the cross-sectional MI model the body mass index/smoking values as recorded in the year before and after therapy initiation. Results Overall, 422/95,057 (0.4%), 19/12,688 (0.1%), and 2,051/161,202 (1.3%) VTE cases/participants were seen in BIFAP, EpiChron, and CPRD, respectively. HRs moved from 100.00% underestimation to 40.31% overestimation in CC compared with cross-sectional MI, while longitudinal MI methods provided similar risk estimates compared with cross-sectional MI. Precision for HR improved in cross-sectional MI versus CC by up to 160.28%, while longitudinal MI improved precision (compared with cross-sectional) only minimally (up to 0.80%). Conclusion CC may substantially affect relative risk estimation in EMR-based drug safety studies, since missing data are not often completely at random. Little improvement was seen in these data in terms of power with the inclusion of longitudinal MI compared with cross-sectional MI. The strategy for handling missing data in drug safety studies can have a large impact on both risk estimates and precision.

The impact of different strategies to handle missing data on both precision and bias in a drug safety study: a multidatabase multinational population-based cohort study.

PubMed

Martín-Merino, Elisa; Calderón-Larrañaga, Amaia; Hawley, Samuel; Poblador-Plou, Beatriz; Llorente-García, Ana; Petersen, Irene; Prieto-Alhambra, Daniel

2018-01-01

Missing data are often an issue in electronic medical records (EMRs) research. However, there are many ways that people deal with missing data in drug safety studies. To compare the risk estimates resulting from different strategies for the handling of missing data in the study of venous thromboembolism (VTE) risk associated with antiosteoporotic medications (AOM). New users of AOM (alendronic acid, other bisphosphonates, strontium ranelate, selective estrogen receptor modulators, teriparatide, or denosumab) aged ≥50 years during 1998-2014 were identified in two Spanish (the Base de datos para la Investigación Farmacoepidemiológica en Atención Primaria [BIFAP] and EpiChron cohort) and one UK (Clinical Practice Research Datalink [CPRD]) EMR. Hazard ratios (HRs) according to AOM (with alendronic acid as reference) were calculated adjusting for VTE risk factors, body mass index (that was missing in 61% of patients included in the three databases), and smoking (that was missing in 23% of patients) in the year of AOM therapy initiation. HRs and standard errors obtained using cross-sectional multiple imputation (MI) (reference method) were compared to complete case (CC) analysis - using only patients with complete data - and longitudinal MI - adding to the cross-sectional MI model the body mass index/smoking values as recorded in the year before and after therapy initiation. Overall, 422/95,057 (0.4%), 19/12,688 (0.1%), and 2,051/161,202 (1.3%) VTE cases/participants were seen in BIFAP, EpiChron, and CPRD, respectively. HRs moved from 100.00% underestimation to 40.31% overestimation in CC compared with cross-sectional MI, while longitudinal MI methods provided similar risk estimates compared with cross-sectional MI. Precision for HR improved in cross-sectional MI versus CC by up to 160.28%, while longitudinal MI improved precision (compared with cross-sectional) only minimally (up to 0.80%). CC may substantially affect relative risk estimation in EMR-based drug safety studies, since missing data are not often completely at random. Little improvement was seen in these data in terms of power with the inclusion of longitudinal MI compared with cross-sectional MI. The strategy for handling missing data in drug safety studies can have a large impact on both risk estimates and precision.

Temporal patterns of variable relationships in person-oriented research: longitudinal models of configural frequency analysis.

PubMed

von Eye, Alexander; Mun, Eun Young; Bogat, G Anne

2008-03-01

This article reviews the premises of configural frequency analysis (CFA), including methods of choosing significance tests and base models, as well as protecting alpha, and discusses why CFA is a useful approach when conducting longitudinal person-oriented research. CFA operates at the manifest variable level. Longitudinal CFA seeks to identify those temporal patterns that stand out as more frequent (CFA types) or less frequent (CFA antitypes) than expected with reference to a base model. A base model that has been used frequently in CFA applications, prediction CFA, and a new base model, auto-association CFA, are discussed for analysis of cross-classifications of longitudinal data. The former base model takes the associations among predictors and among criteria into account. The latter takes the auto-associations among repeatedly observed variables into account. Application examples of each are given using data from a longitudinal study of domestic violence. It is demonstrated that CFA results are not redundant with results from log-linear modeling or multinomial regression and that, of these approaches, CFA shows particular utility when conducting person-oriented research.

Longitudinal quasi-static stability predicts changes in dog gait on rough terrain

PubMed Central

Reeve, Michelle A.; Haynes, G. Clark; Revzen, Shai; Koditschek, Daniel E.; Spence, Andrew J.

2017-01-01

ABSTRACT Legged animals utilize gait selection to move effectively and must recover from environmental perturbations. We show that on rough terrain, domestic dogs, Canis lupus familiaris, spend more time in longitudinal quasi-statically stable patterns of movement. Here, longitudinal refers to the rostro-caudal axis. We used an existing model in the literature to quantify the longitudinal quasi-static stability of gaits neighbouring the walk, and found that trot-like gaits are more stable. We thus hypothesized that when perturbed, the rate of return to a stable gait would depend on the direction of perturbation, such that perturbations towards less quasi-statically stable patterns of movement would be more rapid than those towards more stable patterns of movement. The net result of this would be greater time spent in longitudinally quasi-statically stable patterns of movement. Limb movement patterns in which diagonal limbs were more synchronized (those more like a trot) have higher longitudinal quasi-static stability. We therefore predicted that as dogs explored possible limb configurations on rough terrain at walking speeds, the walk would shift towards trot. We gathered experimental data quantifying dog gait when perturbed by rough terrain and confirmed this prediction using GPS and inertial sensors (n=6, P<0.05). By formulating gaits as trajectories on the n-torus we are able to make tractable the analysis of gait similarity. These methods can be applied in a comparative study of gait control which will inform the ultimate role of the constraints and costs impacting locomotion, and have applications in diagnostic procedures for gait abnormalities, and in the development of agile legged robots. PMID:28264903

Longitudinal quasi-static stability predicts changes in dog gait on rough terrain.

PubMed

Wilshin, Simon; Reeve, Michelle A; Haynes, G Clark; Revzen, Shai; Koditschek, Daniel E; Spence, Andrew J

2017-05-15

Legged animals utilize gait selection to move effectively and must recover from environmental perturbations. We show that on rough terrain, domestic dogs, Canis lupus familiaris , spend more time in longitudinal quasi-statically stable patterns of movement. Here, longitudinal refers to the rostro-caudal axis. We used an existing model in the literature to quantify the longitudinal quasi-static stability of gaits neighbouring the walk, and found that trot-like gaits are more stable. We thus hypothesized that when perturbed, the rate of return to a stable gait would depend on the direction of perturbation, such that perturbations towards less quasi-statically stable patterns of movement would be more rapid than those towards more stable patterns of movement. The net result of this would be greater time spent in longitudinally quasi-statically stable patterns of movement. Limb movement patterns in which diagonal limbs were more synchronized (those more like a trot) have higher longitudinal quasi-static stability. We therefore predicted that as dogs explored possible limb configurations on rough terrain at walking speeds, the walk would shift towards trot. We gathered experimental data quantifying dog gait when perturbed by rough terrain and confirmed this prediction using GPS and inertial sensors ( n =6, P <0.05). By formulating gaits as trajectories on the n -torus we are able to make tractable the analysis of gait similarity. These methods can be applied in a comparative study of gait control which will inform the ultimate role of the constraints and costs impacting locomotion, and have applications in diagnostic procedures for gait abnormalities, and in the development of agile legged robots. © 2017. Published by The Company of Biologists Ltd.

Analysis of factors associated with cracked teeth.

PubMed

Seo, Deog-Gyu; Yi, Young-Ah; Shin, Su-Jung; Park, Jeong-Won

2012-03-01

The purpose of this study was to analyze the characteristics, distribution, and associated factors of longitudinal fractured teeth according to the well-defined criteria of the American Association of Endodontists (AAE). One hundred seven teeth with longitudinal fracture from 103 patients were diagnosed and analyzed. The patients' signs, symptoms, age, and sex were noted as well as the tooth number, dental arch, filling materials, size/classification of restoration, crack direction, pulp vitality, whether the patient had undergone endodontic treatment, bite test results, percussion test results, wear facet, and periodontal pocket depth. Eighty-seven teeth were diagnosed with a cracked tooth (81.3%), 14 were diagnosed with vertical root fracture (VRF, 13.1%), 4 had a split tooth (3.7%), and 2 had a fractured cusp (1.9%); 82.2% showed a sensitive reaction on the bite test. Longitudinal tooth fractures were observed most frequently in patient in their 40s. The upper first molar (28.0%) was most frequently cracked, followed by the lower first molar (25.2%), the lower second molar (20.6%), and the upper second molar (16.8%). Most longitudinal tooth fractures (72.0%) occurred mainly in restored teeth, whereas only 28.0% were found in intact teeth. Compared with resin (4.7%) or porcelain (0.9%), the use of nonbonded inlay restoration materials such as gold (20.5%) or amalgam (18.7%) increased the occurrence of longitudinal tooth fractures. Out of 107 of longitudinal fractured teeth, 33 (30.8%) were treated endodontically and 74 (69.2%) were not. VRF was associated with endodontic treatment. The bite test is most reliable for reproducing symptoms. The combined use of various examination methods is recommended for detecting cracks and minutely inspecting all directions of a tooth. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Is 2D speckle tracking echocardiography useful for detecting and monitoring myocardial dysfunction in adult m.3243A>G carriers? - a retrospective pilot study.

PubMed

Koene, S; Timmermans, J; Weijers, G; de Laat, P; de Korte, C L; Smeitink, J A M; Janssen, M C H; Kapusta, L

2017-03-01

Cardiomyopathy is a common complication of mitochondrial disorders, associated with increased mortality. Two dimensional speckle tracking echocardiography (2DSTE) can be used to quantify myocardial deformation. Here, we aimed to determine the usefulness of 2DSTE in detecting and monitoring subtle changes in myocardial dysfunction in carriers of the 3243A>G mutation in mitochondrial DNA. In this retrospective pilot study, 30 symptomatic and asymptomatic carriers of the mitochondrial 3243A>G mutation of whom two subsequent echocardiograms were available were included. We measured longitudinal, circumferential and radial strain using 2DSTE. Results were compared to published reference values. Speckle tracking was feasible in 90 % of the patients for longitudinal strain. Circumferential and radial strain showed low face validity (low number of images with sufficient quality; suboptimal tracking) and were therefore rejected for further analysis. Global longitudinal strain showed good face validity, and was abnormal in 56-70 % (depending on reference values used) of the carriers (n = 27). Reproducibility was good (mean difference of 0.83 for inter- and 0.40 for intra-rater reproducibility; ICC 0.78 and 0.89, respectively). The difference between the first and the second measurement exceeded the measurement variance in 39 % of the cases (n = 23; feasibility of follow-up 77 %). Even in data collected as part of clinical care, two-dimensional strain echocardiography seems a feasible method to detect and monitor subtle changes in longitudinal myocardial deformation in adult carriers of the mitochondrial 3243A>G mutation. Based on our data and the reported accuracy of global longitudinal strain in other studies, we suggest the use of global longitudinal strain in a prospective follow-up or intervention study.

Changes in HRM in Europe: A Longitudinal Comparative Study among 18 European Countries

ERIC Educational Resources Information Center

Nikandrou, Irene; Apospori, Eleni; Papalexandris, Nancy

2005-01-01

Purpose: To examine HRM strategies and practices and HRM position within organizations in various cultural, economic and sociopolitical contexts from a longitudinal perspective. Design/methodology/approach: The study uses the 1995 and 1999 Cranet data in a longitudinal methodological framework to explore the changes and trends in 18 European…

A SIR/CAR Systems Analysis of the Longitudinal Changes in Little League Baseball Comparing Windsor with the Rest of Ontario and Canada.

ERIC Educational Resources Information Center

Zarebski, John; Moriarty, Dick

The trends and changes occurring in Windsor District 5 Little League Baseball between 1971 and 1978 were closely monitored in order for researchers to discern the results of Sports Institute for Research/Change Agent Research (SIR/CAR) intervention in these programs. Comparisons of the 1972, 1976, and 1978 studies reveal that the values focus of…

Occupational Stratification over the Life Course: A Comparison of Occupational Trajectories across Race and Gender during the 1980s and 1990s.

ERIC Educational Resources Information Center

Miech, Richard A.; Eaton, William; Liang, Kung-Yee

2003-01-01

Growth curve analysis was used on data from the National Longitudinal Survey (n=9,532) and Baltimore (n=3,481) to determine whether disparities in the occupational standing of white men compared to women and minorities grew with advancing age. Results indicate that disparities remained constant over the life course for all but African Americans…

The reciprocal relationships among parents' expectations, adolescents' expectations, and adolescents' achievement: a two-wave longitudinal analysis of the NELS data.

PubMed

Zhang, Yanyan; Haddad, Eileen; Torres, Bernadeth; Chen, Chuansheng

2011-04-01

Previous research has consistently demonstrated the importance of parents' expectations and adolescents' expectations on adolescents' academic achievement. Less is known, however, about the reciprocal relationships among these constructs. To address this issue, we analyzed two waves of data from the National Education Longitudinal Study of 1988 (NELS:88) using longitudinal cross-lagged path models. The sample consisted of 14,376 students (51.1% females; 6.5% Asian, 11.1% Hispanic, 9.2% African American, and 73.2% White). Results indicated that there was a reciprocal relationship between parents' expectations and adolescents' expectations (i.e., they had mutual influence on each other). Moreover, there was a reciprocal relationship between expectations (both parents' and adolescents') and adolescents' academic achievement. Multiple-group analyses of gender and ethnicity revealed that the effects of parents' expectations on students' expectations were stronger among males than among females. With respect to ethnic differences, the effects of adolescents' expectations were weakest on parents' expectations among African Americans as compared to the other ethnic groups (i.e., Asian, Hispanic and White). Implications of these findings are discussed.

Integrating prospective longitudinal data: modeling personality and health in the Terman Life Cycle and Hawaii Longitudinal Studies.

PubMed

Kern, Margaret L; Hampson, Sarah E; Goldberg, Lewis R; Friedman, Howard S

2014-05-01

The present study used a collaborative framework to integrate 2 long-term prospective studies: the Terman Life Cycle Study and the Hawaii Personality and Health Longitudinal Study. Within a 5-factor personality-trait framework, teacher assessments of child personality were rationally and empirically aligned to establish similar factor structures across samples. Comparable items related to adult self-rated health, education, and alcohol use were harmonized, and data were pooled on harmonized items. A structural model was estimated as a multigroup analysis. Harmonized child personality factors were then used to examine markers of physiological dysfunction in the Hawaii sample and mortality risk in the Terman sample. Harmonized conscientiousness predicted less physiological dysfunction in the Hawaii sample and lower mortality risk in the Terman sample. These results illustrate how collaborative, integrative work with multiple samples offers the exciting possibility that samples from different cohorts and ages can be linked together to directly test life span theories of personality and health. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

The Longitudinal Interplay of Maternal Warmth and Adolescents' Self-Disclosure in Predicting Maternal Knowledge

ERIC Educational Resources Information Center

Blodgett Salafia, Elizabeth H.; Gondoli, Dawn M.; Grundy, Amber M.

2009-01-01

This study examined the longitudinal associations among maternal warmth, adolescents' self-disclosure, and maternal knowledge during the transition to adolescence. Three years of self-report data were collected from 131 married mothers and their adolescents. Results from longitudinal analysis using adolescent reports indicated that greater…

Multivariate Longitudinal Methods for Studying Developmental Relationships between Depression and Academic Achievement

ERIC Educational Resources Information Center

Grimm, Kevin J.

2007-01-01

Recent advances in methods and computer software for longitudinal data analysis have pushed researchers to more critically examine developmental theories. In turn, researchers have also begun to push longitudinal methods by asking more complex developmental questions. One such question involves the relationships between two developmental…

Child incarceration and long-term adult health outcomes: a longitudinal study.

PubMed

Barnert, Elizabeth S; Abrams, Laura S; Tesema, Lello; Dudovitz, Rebecca; Nelson, Bergen B; Coker, Tumaini; Bath, Eraka; Biely, Christopher; Li, Ning; Chung, Paul J

2018-03-12

Purpose Although incarceration may have life-long negative health effects, little is known about associations between child incarceration and subsequent adult health outcomes. The paper aims to discuss this issue. Design/methodology/approach The authors analyzed data from 14,689 adult participants in the National Longitudinal Study of Adolescent to Adult Health (Add Health) to compare adult health outcomes among those first incarcerated between 7 and 13 years of age (child incarceration); first incarcerated at>or=14 years of age; and never incarcerated. Findings Compared to the other two groups, those with a history of child incarceration were disproportionately black or Hispanic, male, and from lower socio-economic strata. Additionally, individuals incarcerated as children had worse adult health outcomes, including general health, functional limitations (climbing stairs), depressive symptoms, and suicidality, than those first incarcerated at older ages or never incarcerated. Research limitations/implications Despite the limitations of the secondary database analysis, these findings suggest that incarcerated children are an especially medically vulnerable population. Practical implications Programs and policies that address these medically vulnerable children's health needs through comprehensive health and social services in place of, during, and/or after incarceration are needed. Social implications Meeting these unmet health and social service needs offers an important opportunity to achieve necessary health care and justice reform for children. Originality/value No prior studies have examined the longitudinal relationship between child incarceration and adult health outcomes.

Right-sizing statistical models for longitudinal data.

PubMed

Wood, Phillip K; Steinley, Douglas; Jackson, Kristina M

2015-12-01

Arguments are proposed that researchers using longitudinal data should consider more and less complex statistical model alternatives to their initially chosen techniques in an effort to "right-size" the model to the data at hand. Such model comparisons may alert researchers who use poorly fitting, overly parsimonious models to more complex, better-fitting alternatives and, alternatively, may identify more parsimonious alternatives to overly complex (and perhaps empirically underidentified and/or less powerful) statistical models. A general framework is proposed for considering (often nested) relationships between a variety of psychometric and growth curve models. A 3-step approach is proposed in which models are evaluated based on the number and patterning of variance components prior to selection of better-fitting growth models that explain both mean and variation-covariation patterns. The orthogonal free curve slope intercept (FCSI) growth model is considered a general model that includes, as special cases, many models, including the factor mean (FM) model (McArdle & Epstein, 1987), McDonald's (1967) linearly constrained factor model, hierarchical linear models (HLMs), repeated-measures multivariate analysis of variance (MANOVA), and the linear slope intercept (linearSI) growth model. The FCSI model, in turn, is nested within the Tuckerized factor model. The approach is illustrated by comparing alternative models in a longitudinal study of children's vocabulary and by comparing several candidate parametric growth and chronometric models in a Monte Carlo study. (c) 2015 APA, all rights reserved).

Fatigue Following Traumatic Brain Injury in Children and Adolescents: A Longitudinal Follow-Up 6 to 12 Months After Injury.

PubMed

Crichton, Alison; Anderson, Vicki; Oakley, Ed; Greenham, Mardee; Hearps, Stephen; Delzoppo, Carmel; Beauchamp, Miriam H; Hutchison, James S; Guerguerian, Anne-Marie; Boutis, Kathy; Babl, Franz E

Longitudinal fatigue data in children suffering from traumatic brain injury (TBI) are lacking. To examine the effects of time postinjury (6-12 months) and injury severity on fatigue after childhood TBI. Secondarily, we compared fatigue 12 months postinjury against published control data. Three tertiary children's hospitals across Australia (n = 1) and Canada (n = 2). Parents (n = 109) of children (mean [M] = 9.9 years at injury; range, 1.0-16.9 years) admitted to one of 3 participating hospitals with mild (n = 69) or moderate/severe (n = 37) TBI. Longitudinal prospective study. Primary: Pediatric Quality of Life Multidimensional Fatigue Scale (total, general, sleep/rest, and cognitive), rated by parents 6 and 12 months postinjury. Secondary: Pediatric Injury Functional Outcome Scale (fatigue and sleep items, rated on recruitment and 6 and 12 months postinjury). Demographic and children data were collected at recruitment. Mixed-models analysis demonstrated nonsignificant effects of time (6 vs 12 months postinjury) on multidimensional fatigue scores. Cognitive fatigue worsened over time. Moderate/severe TBI was associated with worse fatigue 12 months postinjury (general, P = .03; cognitive, P = .02). Across all severities, fatigue 12 months postinjury was significantly worse compared with control data (total fatigue, P < .001; all domains, all Ps < .025). Fatigue remains significant at 12 months since injury, particularly for those with moderate/severe TBI.

Modeling Longitudinal Data Containing Non-Normal Within Subject Errors

NASA Technical Reports Server (NTRS)

Feiveson, Alan; Glenn, Nancy L.

2013-01-01

The mission of the National Aeronautics and Space Administration’s (NASA) human research program is to advance safe human spaceflight. This involves conducting experiments, collecting data, and analyzing data. The data are longitudinal and result from a relatively few number of subjects; typically 10 – 20. A longitudinal study refers to an investigation where participant outcomes and possibly treatments are collected at multiple follow-up times. Standard statistical designs such as mean regression with random effects and mixed–effects regression are inadequate for such data because the population is typically not approximately normally distributed. Hence, more advanced data analysis methods are necessary. This research focuses on four such methods for longitudinal data analysis: the recently proposed linear quantile mixed models (lqmm) by Geraci and Bottai (2013), quantile regression, multilevel mixed–effects linear regression, and robust regression. This research also provides computational algorithms for longitudinal data that scientists can directly use for human spaceflight and other longitudinal data applications, then presents statistical evidence that verifies which method is best for specific situations. This advances the study of longitudinal data in a broad range of applications including applications in the sciences, technology, engineering and mathematics fields.

Does relationship satisfaction and financial aid from offspring influence the quality of life of older parents?: a longitudinal study based on findings from the Korean longitudinal study of aging, 2006-2012.

PubMed

Ju, Yeong Jun; Han, Kyu-Tae; Lee, Tae-Hoon; Kim, Woorim; Kim, Juyeong; Park, Eun-Cheol

2016-07-26

Quality of life (QoL) in old age is of major importance because the global population is aging rapidly. Offspring support, including financial and emotional support, is important in later life and directly affects the wellbeing of elderly individuals. The aim of this study was to examine the relationship between QoL in older parents and offspring support. We used baseline data from the 2006-2012 Korean Longitudinal Study of Aging, from 3,274 individuals aged 65 years or older. We measured the individual's QoL using a visual analog scale and included both relationship satisfaction and regular economic support as variables. A generalized estimating equation (GEE) model was used to perform longitudinal regression analysis on the data. Regarding the QoL of older parents, those with an unsatisfying relationship with their offspring had a QoL of -21.93 (SE = 0.55; P < 0.0001) compared to those with satisfying offspring relationships. Those receiving no regular financial aid from their offspring had a QoL of -0.92 (SE = 0.38; P = 0.0171) compared to those who received such economic support. Combination effects were observed, with cases living alone - and having poor offspring relationships and no regular financial support from their offspring - showing the most drastic decrease in QoL (-23.46; SE = 1.03; P < 0.0001). Offspring support influences the QoL of elderly individuals, and Korean children appear to play a crucial role in the QoL of their (older) parents. Considering that the role of offspring is rapidly diminishing due to industrialization policies, initiatives are required to revitalize offspring support for elderly parents.

Psychiatric Disorders and General Functioning in Low Birth Weight Adults: A Longitudinal Study.

PubMed

Lærum, Astrid M W; Reitan, Solveig Klæbo; Evensen, Kari Anne I; Lydersen, Stian; Brubakk, Ann-Mari; Skranes, Jon; Indredavik, Marit S

2017-02-01

To examine psychiatric morbidity and overall functioning in adults born with low birth weight compared with normal birth weight controls at age 26 years and to study longitudinal trajectories of psychiatric morbidity from early adolescence to adulthood. Prospective cohort study wherein 44 preterm very low birth weight (≤1500 g), 64 term small for gestational age (SGA; <10th percentile), and 81 control adults were examined using the MINI-International Neuropsychiatric Interview: M.I.N.I. Plus, Norwegian version, the Global Assessment of Functioning, and questions on daily occupation and level of education. Prevalence of psychiatric disorders from previous follow-ups at age 14 and 19 years were included for longitudinal analysis. From adolescence to adulthood, the term SGA group had a marked increase in the estimated probability of psychiatric disorders from 9% (95% confidence interval, 4-19) to 39% (95% confidence interval, 28-51). At 26 years, psychiatric diagnoses were significantly more prevalent in the preterm very low birth weight group (n = 16, 36%; P = .003) and the term SGA group (n = 24, 38%; P = .019) compared with the control group (n = 11, 14%). Both low birth weight groups had lower educational level and functioning scores than controls and a higher frequency of unemployment and disability benefit. Low birth weight was a substantial risk factor for adult psychiatric morbidity and lowered overall functioning. The results underscore the need for long-term follow-up of low birth weight survivors through adolescence and adulthood, focusing on mental health. The longitudinal increase in psychiatric morbidity in the term SGA group calls for additional investigation. Copyright © 2017 by the American Academy of Pediatrics.

Early detection of cardiac involvement in sarcoidosis with 2-dimensional speckle-tracking echocardiography.

PubMed

Schouver, Elie-Dan; Moceri, Pamela; Doyen, Denis; Tieulie, Nathalie; Queyrel, Viviane; Baudouy, Delphine; Cerboni, Pierre; Gibelin, Pierre; Leroy, Sylvie; Fuzibet, Jean-Gabriel; Ferrari, Emile

2017-01-15

Cardiac sarcoidosis (CS) is associated with high morbidity and sudden death. The absence of specific symptoms and lack of diagnostic gold standard technique is challenging. New imaging methods could improve the diagnosis of CS. The aim of our study was to assess the role of left ventricular (LV) longitudinal and circumferential strain as estimated by 2D speckle-tracking imaging in patients with diagnosed sarcoidosis without cardiac involvement according to the current guidelines. We investigated the prevalence of LV strain impairment in this population and assessed its relationship with clinical outcomes, composite of mortality, heart failure, arrhythmia and/or secondarily development of CS and cardiac device implantation. We performed a prospective case-control longitudinal study including 35 patients with diagnosed sarcoidosis and normal cardiac function as assessed by standard transthoracic echocardiography and 35 healthy age- and gender-matched controls. All patients underwent a comprehensive echocardiographic study. Mean age of patients was 47.9±14.8years old (22 women). Compared with controls, global LV longitudinal strain (LV GLS) was reduced in sarcoidosis patients: (-17.2±3.1 vs -21.3±1.5%, p<0.0001). Circumferential LV strain was preserved in patients compared to controls (-19.9±-4.3% vs -21.3±1.5%, p=0.12). Impaired LV GLS was significantly associated with clinical outcomes (HR 1.56; [1.16-2.11], p<0.01) on univariate analysis. Speckle-tracking echocardiography revealed decreased longitudinal LV strain in sarcoidosis patients that was associated with outcomes. LV GLS may represent an early marker of myocardial involvement in sarcoidosis patients that needs to be studied further. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Rapid simultaneous high-resolution mapping of myelin water fraction and relaxation times in human brain using BMC-mcDESPOT.

PubMed

Bouhrara, Mustapha; Spencer, Richard G

2017-02-15

A number of central nervous system (CNS) diseases exhibit changes in myelin content and magnetic resonance longitudinal, T 1 , and transverse, T 2 , relaxation times, which therefore represent important biomarkers of CNS pathology. Among the methods applied for measurement of myelin water fraction (MWF) and relaxation times, the multicomponent driven equilibrium single pulse observation of T 1 and T 2 (mcDESPOT) approach is of particular interest. mcDESPOT permits whole brain mapping of multicomponent T 1 and T 2 , with data acquisition accomplished within a clinically realistic acquisition time. Unfortunately, previous studies have indicated the limited performance of mcDESPOT in the setting of the modest signal-to-noise range of high-resolution mapping, required for the depiction of small structures and to reduce partial volume effects. Recently, we showed that a new Bayesian Monte Carlo (BMC) analysis substantially improved determination of MWF from mcDESPOT imaging data. However, our previous study was limited in that it did not discuss determination of relaxation times. Here, we extend the BMC analysis to the simultaneous determination of whole-brain MWF and relaxation times using the two-component mcDESPOT signal model. Simulation analyses and in-vivo human brain studies indicate the overall greater performance of this approach compared to the stochastic region contraction (SRC) algorithm, conventionally used to derive parameter estimates from mcDESPOT data. SRC estimates of the transverse relaxation time of the long T 2 fraction, T 2,l , and the longitudinal relaxation time of the short T 1 fraction, T 1,s , clustered towards the lower and upper parameter search space limits, respectively, indicating failure of the fitting procedure. We demonstrate that this effect is absent in the BMC analysis. Our results also showed improved parameter estimation for BMC as compared to SRC for high-resolution mapping. Overall we find that the combination of BMC analysis and mcDESPOT, BMC-mcDESPOT, shows excellent performance for accurate high-resolution whole-brain mapping of MWF and bi-component transverse and longitudinal relaxation times within a clinically realistic acquisition time. Published by Elsevier Inc.

Exercise and Cardiometabolic Risk Factors in Graduate Students: A Longitudinal, Observational Study

ERIC Educational Resources Information Center

Racette, Susan B.; Inman, Cindi L.; Clark, B. Ruth; Royer, Nathaniel K.; Steger-May, Karen; Deusinger, Susan S.

2014-01-01

Objective: To evaluate cardiometabolic risk of students longitudinally and compare them with age-matched national samples. Participants: Participants are 134 graduate students enrolled between August 2005 and May 2010. Methods: Students were assessed at the beginning and end of their 3-year curriculum. Comparative samples included 966 National…

Removed from the List: A Comparative Longitudinal Case Study of a Reconstitution-Eligible School.

ERIC Educational Resources Information Center

Mac Iver, Douglas J.; Ruby, Allen; Balfanz, Robert; Byrnes, Vaughan

2002-01-01

Longitudinal case study of reform efforts centering on the Talent Development Middle School model at low-performing, high-poverty middle school in Philadelphia. Finds that student gains in mathematics, science, and reading achievement at subject school exceeded that of students in comparable school. (Contains 19 references.) (PKP)

Forward-backward multiplicity fluctuation and longitudinal harmonics in high-energy nuclear collisions

DOE PAGES

Jia, Jiangyong; Radhakrishnan, Sooraj; Zhou, Mingliang

2016-04-18

In this paper, an analysis method is proposed to study the forward-backward (FB) multiplicity fluctuation in high-energy nuclear collisions, built on the earlier work of Bzdak and Teaney [Phys. Rev. C 87, 024906 (2013)]. The method allows the decomposition of the centrality dependence of average multiplicity from the dynamical event-by-event (EbyE) fluctuation of multiplicity in pseudorapidity. Application of the method to AMPT (A Multi-Phase Transport model) and HIJING (Heavy Ion Jet INteraction Generator) models shows that the long-range component of the FB correlation is captured by a few longitudinal harmonics, with the first component driven by the asymmetry in themore » number of participating nucleons in the two colliding nuclei. The higher-order longitudinal harmonics are found to be strongly damped in AMPT compared to HIJING, due to weaker short-range correlations as well as the final-state effects present in the AMPT model. Two-particle pseudorapidity correlation reveals interesting charge-dependent short-range structures that are absent in HIJING model. Lastly, the proposed method opens an avenue to elucidate the particle production mechanism and early time dynamics in heavy-ion collisions. Future analysis directions and prospects of using the pseudorapidity correlation function to understand the centrality bias in p + p, p + A, and A + A collisions are discussed.« less

Mixed-effects varying-coefficient model with skewed distribution coupled with cause-specific varying-coefficient hazard model with random-effects for longitudinal-competing risks data analysis.

PubMed

Lu, Tao; Wang, Min; Liu, Guangying; Dong, Guang-Hui; Qian, Feng

2016-01-01

It is well known that there is strong relationship between HIV viral load and CD4 cell counts in AIDS studies. However, the relationship between them changes during the course of treatment and may vary among individuals. During treatments, some individuals may experience terminal events such as death. Because the terminal event may be related to the individual's viral load measurements, the terminal mechanism is non-ignorable. Furthermore, there exists competing risks from multiple types of events, such as AIDS-related death and other death. Most joint models for the analysis of longitudinal-survival data developed in literatures have focused on constant coefficients and assume symmetric distribution for the endpoints, which does not meet the needs for investigating the nature of varying relationship between HIV viral load and CD4 cell counts in practice. We develop a mixed-effects varying-coefficient model with skewed distribution coupled with cause-specific varying-coefficient hazard model with random-effects to deal with varying relationship between the two endpoints for longitudinal-competing risks survival data. A fully Bayesian inference procedure is established to estimate parameters in the joint model. The proposed method is applied to a multicenter AIDS cohort study. Various scenarios-based potential models that account for partial data features are compared. Some interesting findings are presented.

Associations of Dairy Intake with Arterial Stiffness in Brazilian Adults: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

PubMed

Ribeiro, Amanda Gomes; Mill, José Geraldo; Cade, Nágela Valadão; Velasquez-Melendez, Gustavo; Matos, Sheila Maria Alvim; Molina, Maria Del Carmen Bisi

2018-05-31

Recent studies have suggested the possible effect of dairy product intake on cardiovascular risk markers, including arterial stiffness. Our aim was to investigate whether dairy food intake is associated with arterial stiffness, which we assessed by carotid-femoral pulse wave velocity (cfPWV) and pulse pressure (PP) in a cross-sectional analysis of baseline data (2008⁻2010; n = 12,892) of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Dairy consumption was evaluated with a validated food-frequency questionnaire (FFQ) by computing servings per day for total and subgroups of dairy products. Dairy consumption was described in four categories (≤1 serving/day to >4 servings/day). Covariance analysis (ANCOVA) was used to compare cfPWV across increasing intake of dairy food, adjusting for confounding factors, including non-dairy food groups. The intake of total dairy was inversely associated with cfPWV and PP (-0.13 m/s and -1.3 mmHg, from the lowest and to the highest category of dairy intake). Low-fat dairy, fermented dairy and cheese showed an inverse relationship with cfPWV and PP. These findings suggest a beneficial effect of dairy consumption to reduce arterial stiffness. However, further evidence from longitudinal studies or long-term intervention is needed to support reduction of cfPWV and PP mediating the beneficial effects of dairy products on cardiovascular health.

Characterization and Strain-Hardening Behavior of Friction Stir-Welded Ferritic Stainless Steel

NASA Astrophysics Data System (ADS)

Sharma, Gaurav; Dwivedi, Dheerendra Kumar; Jain, Pramod Kumar

2017-12-01

In this study, friction stir-welded joint of 3-mm-thick plates of 409 ferritic stainless steel (FSS) was characterized in light of microstructure, x-ray diffraction analysis, hardness, tensile strength, ductility, corrosion and work hardening properties. The FSW joint made of ferritic stainless steel comprises of three distinct regions including the base metal. In stir zone highly refined ferrite grains with martensite and some carbide precipitates at the grain boundaries were observed. X-ray diffraction analysis also revealed precipitation of Cr23C6 and martensite formation in heat-affected zone and stir zone. In tensile testing of the transverse weld samples, the failure eventuated within the gauge length of the specimen from the base metal region having tensile properties overmatched to the as-received base metal. The tensile strength and elongation of the longitudinal (all weld) sample were found to be 1014 MPa and 9.47%, respectively. However, in potentiodynamic polarization test, the corrosion current density of the stir zone was highest among all the three zones. The strain-hardening exponent for base metal, transverse and longitudinal (all weld) weld samples was calculated using various equations. Both the transverse and longitudinal weld samples exhibited higher strain-hardening exponents as compared to the as-received base metal. In Kocks-Mecking plots for the base metal and weld samples at least two stages of strain hardening were observed.

Variability and Reproducibility of Segmental Longitudinal Strain Measurement: A Report From the EACVI-ASE Strain Standardization Task Force.

PubMed

Mirea, Oana; Pagourelias, Efstathios D; Duchenne, Jurgen; Bogaert, Jan; Thomas, James D; Badano, Luigi P; Voigt, Jens-Uwe

2018-01-01

In this study, we compared left ventricular (LV) segmental strain measurements obtained with different ultrasound machines and post-processing software packages. Global longitudinal strain (GLS) has proven to be a reproducible and valuable tool in clinical practice. Data about the reproducibility and intervendor differences of segmental strain measurements, however, are missing. We included 63 volunteers with cardiac magnetic resonance-proven infarct scar with segmental LV function ranging from normal to severely impaired. Each subject was examined within 2 h by a single expert sonographer with machines from multiple vendors. All 3 apical views were acquired twice to determine the test-retest and the intervendor variability. Segmental longitudinal peak systolic, end-systolic, and post-systolic strain were measured using 7 vendor-specific systems (Hitachi, Tokyo, Japan; Esaote, Florence, Italy; GE Vingmed Ultrasound, Horten, Norway; Philips, Andover, Massachusetts; Samsung, Seoul, South Korea; Siemens, Mountain View, California; and Toshiba, Otawara, Japan) and 2 independent software packages (Epsilon, Ann Arbor, Michigan; and TOMTEC, Unterschleissheim, Germany) and compared among vendors. Image quality and tracking feasibility differed among vendors (analysis of variance, p < 0.05). The absolute test-retest difference ranged from 2.5% to 4.9% for peak systolic, 2.6% to 5.0% for end-systolic, and 2.5% to 5.0% for post-systolic strain. The average segmental strain values varied significantly between vendors (up to 4.5%). Segmental strain parameters from each vendor correlated well with the mean of all vendors (r 2 range 0.58 to 0.81) but showed very different ranges of values. Bias and limits of agreement were up to -4.6 ± 7.5%. In contrast to GLS, LV segmental longitudinal strain measurements have a higher variability on top of the known intervendor bias. The fidelity of different software to follow segmental function varies considerably. We conclude that single segmental strain values should be used with caution in the clinic. Segmental strain pattern analysis might be a more robust alternative. Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Organised Motion in a Tall Spruce Canopy: Temporal Scales, Structure Spacing and Terrain Effects

NASA Astrophysics Data System (ADS)

Thomas, Christoph; Foken, Thomas

2007-01-01

This study investigates the organised motion near the canopy-atmosphere interface of a moderately dense spruce forest in heterogeneous, complex terrain. Wind direction is used to assess differences in topography and surface properties. Observations were obtained at several heights above and within the canopy using sonic anemometers and fast-response gas analysers over the course of several weeks. Analysed variables include the three-dimensional wind vector, the sonic temperature, and the concentration of carbon dioxide. Wavelet analysis was used to extract the organised motion from time series and to derive its temporal scales. Spectral Fourier analysis was deployed to compute power spectra and phase spectra. Profiles of temporal scales of ramp-like coherent structures in the vertical and longitudinal wind components showed a reversed variation with height and were of similar size within the canopy. Temporal scales of scalar fields were comparable to those of the longitudinal wind component suggesting that the lateral scalar transport dominates. The existence of a 1 power law in the longitudinal power spectra was confirmed for a few cases only, with a majority showing a clear 5/3 decay. The variation of effective scales of organised motion in the longitudinal velocity and temperature were found to vary with atmospheric stability, suggesting that both Kelvin-Helmholtz instabilities and attached eddies dominate the flow with increasing convectional forcing. The canopy mixing-layer analogy was observed to be applicable for ramp-like coherent structures in the vertical wind component for selected wind directions only. Departures from the prediction of m = Λ w L {/s -1} = 8 10 (where Λ w is the streamwise spacing of coherent structures in the vertical wind w and L s is a canopy shear length scale) were caused by smaller shear length scales associated with large-scale changes in the terrain as well as the vertical structure of the canopy. The occurrence of linear gravity waves was related to a rise in local topography and can therefore be referred to as mountain-type gravity waves. Temporal scales of wave motion and ramp-like coherent structures were observed to be comparable.

Statistical inference methods for sparse biological time series data.

PubMed

Ndukum, Juliet; Fonseca, Luís L; Santos, Helena; Voit, Eberhard O; Datta, Susmita

2011-04-25

Comparing metabolic profiles under different biological perturbations has become a powerful approach to investigating the functioning of cells. The profiles can be taken as single snapshots of a system, but more information is gained if they are measured longitudinally over time. The results are short time series consisting of relatively sparse data that cannot be analyzed effectively with standard time series techniques, such as autocorrelation and frequency domain methods. In this work, we study longitudinal time series profiles of glucose consumption in the yeast Saccharomyces cerevisiae under different temperatures and preconditioning regimens, which we obtained with methods of in vivo nuclear magnetic resonance (NMR) spectroscopy. For the statistical analysis we first fit several nonlinear mixed effect regression models to the longitudinal profiles and then used an ANOVA likelihood ratio method in order to test for significant differences between the profiles. The proposed methods are capable of distinguishing metabolic time trends resulting from different treatments and associate significance levels to these differences. Among several nonlinear mixed-effects regression models tested, a three-parameter logistic function represents the data with highest accuracy. ANOVA and likelihood ratio tests suggest that there are significant differences between the glucose consumption rate profiles for cells that had been--or had not been--preconditioned by heat during growth. Furthermore, pair-wise t-tests reveal significant differences in the longitudinal profiles for glucose consumption rates between optimal conditions and heat stress, optimal and recovery conditions, and heat stress and recovery conditions (p-values <0.0001). We have developed a nonlinear mixed effects model that is appropriate for the analysis of sparse metabolic and physiological time profiles. The model permits sound statistical inference procedures, based on ANOVA likelihood ratio tests, for testing the significance of differences between short time course data under different biological perturbations.

Influences of the Big Five personality traits on the treatment response and longitudinal course of depression in patients with acute coronary syndrome: A randomised controlled trial.

PubMed

Kim, Seon-Young; Stewart, Robert; Bae, Kyung-Yeol; Kim, Sung-Wan; Shin, Il-Seon; Hong, Young Joon; Ahn, Youngkeun; Jeong, Myung Ho; Yoon, Jin-Sang; Kim, Jae-Min

2016-10-01

Influences of the Big Five personality traits on the treatment response and longitudinal course of depression in patients with acute coronary syndrome: A randomised controlled trial. This naturalistic observational study initially recruited 1152 ACS patients; 685 patients completed personality assessments at baseline, of whom 630 were followed-up one year later. Of the 294 patients with depression, 207 participated in a 24-week double blind trial of escitalopram or placebo. The remaining 87 patients who received medical treatment only and the 391 who had not depression were also followed in a one year naturalistic observational study. The Big five personality traits were assessed using the Big Five Inventory. The influences of personality on the Hamilton Depression Rating Scale score changes were analysed using a mixed-model repeated-measures analysis of covariance. A Cluster analysis identified two personality types: resilient and vulnerable. The vulnerable personality type was characterized by lower extraversion, agreeableness, and conscientiousness - but higher neuroticism - than the resilient type. This personality type was independently associated with a poorer outcome of depression in ACS patients during the 24-week treatment period and the one year longitudinal follow-up period compared to the resilient personality type, irrespective of treatment allocation. Recruitment from a single institution may limit generalisability. Personality traits were investigated 12-weeks after ACS; thus, the responses may have been influenced by the prior receipt of escitalopram. Personality types influences the treatment outcome and longitudinal course of depression in ACS patients independent of antidepressant treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

A Meta-Analysis of Cognitive Impairment and Decline Associated with Adjuvant Chemotherapy in Women with Breast Cancer

PubMed Central

Ono, Miyuki; Ogilvie, James M.; Wilson, Jennifer S.; Green, Heather J.; Chambers, Suzanne K.; Ownsworth, Tamara; Shum, David H. K.

2015-01-01

A meta-analysis was performed to quantify the magnitude and nature of the association between adjuvant chemotherapy and performance on a range of cognitive domains among breast cancer patients. A total of 27 studies (14 cross-sectional, 8 both cross-sectional and prospective, and 5 prospective) were included in the analyses, involving 1562 breast cancer patients who had undergone adjuvant chemotherapy and 2799 controls that included breast cancer patients who did not receive adjuvant chemotherapy. A total of 737 effect sizes (Cohen’s d) were calculated for cross-sectional and prospective longitudinal studies separately and classified into eight cognitive domains. The mean effect sizes varied across cross-sectional and prospective longitudinal studies (ranging from −1.12 to 0.62 and −0.29 to 1.12, respectively). Each cognitive domain produced small effect sizes for cross-sectional and prospective longitudinal studies (ranging from −0.25 to 0.41). Results from cross-sectional studies indicated a significant association between adjuvant chemotherapy and cognitive impairment that held across studies with varied methodological approaches. For prospective studies, results generally indicated that cognitive functioning improved over time after receiving adjuvant chemotherapy. Greater cognitive impairment was reported in cross-sectional studies comparing chemotherapy groups with healthy control groups. Results suggested that cognitive impairment is present among breast cancer patients irrespective of a history of chemotherapy. Prospective longitudinal research is warranted to examine the degree and persisting nature of cognitive impairment present both before and after chemotherapy, with comparisons made to participants’ cognitive function prior to diagnosis. Accurate understanding of the effects of chemotherapy is essential to enable informed decisions regarding treatment and to improve quality of life among breast cancer patients. PMID:25806355

A Comparison of Missing-Data Procedures for Arima Time-Series Analysis

ERIC Educational Resources Information Center

Velicer, Wayne F.; Colby, Suzanne M.

2005-01-01

Missing data are a common practical problem for longitudinal designs. Time-series analysis is a longitudinal method that involves a large number of observations on a single unit. Four different missing-data methods (deletion, mean substitution, mean of adjacent observations, and maximum likelihood estimation) were evaluated. Computer-generated…

Profiles of Intrinsic and Extrinsic Motivations in Elementary School: A Longitudinal Analysis

ERIC Educational Resources Information Center

Corpus, Jennifer Henderlong; Wormington, Stephanie V.

2014-01-01

The authors used a person-centered, longitudinal approach to identify and evaluate naturally occurring combinations of intrinsic and extrinsic motivations among 490 third- through fifth-grade students. Cluster analysis revealed 3 groups, characterized by high levels of both motivations ("high quantity"): high intrinsic motivation but low…

Issues in Longitudinal Research on Motivation

ERIC Educational Resources Information Center

Stoel, Reinoud D.; Roeleveld, Jaap; Peetsma, Thea; van den Wittenboer, Godfried; Hox, Joop

2006-01-01

This paper discusses two methodological issues regarding the analysis of longitudinal data using structural equation modeling that emerged during the reconsideration of the analysis of a recent study on the relationship between academic motivation and language achievement in elementary education [Stoel R.D., Peetsma, T.T.D. and Roeleveld, J.…

Three-dimensional Speckle Tracking Echocardiography in Light Chain Cardiac Amyloidosis: Examination of Left and Right Ventricular Myocardial Mechanics Parameters.

PubMed

Urbano-Moral, Jose Angel; Gangadharamurthy, Dakshin; Comenzo, Raymond L; Pandian, Natesa G; Patel, Ayan R

2015-08-01

The study of myocardial mechanics has a potential role in the detection of cardiac involvement in patients with amyloidosis. This study aimed to characterize 3-dimensional-speckle tracking echocardiography-derived left and right ventricular myocardial mechanics in light chain amyloidosis and examine their relationship with brain natriuretic peptide. In patients with light chain amyloidosis, left ventricular longitudinal and circumferential strain (n=40), and right ventricular longitudinal strain and radial displacement (n=26) were obtained by 3-dimensional-speckle tracking echocardiography. Brain natriuretic peptide levels were determined. All myocardial mechanics measurements showed differences when compared by brain natriuretic peptide level tertiles. Left and right ventricular longitudinal strain were highly correlated (r=0.95, P<.001). Left ventricular longitudinal and circumferential strain were reduced in patients with cardiac involvement (-9±4 vs -16±2; P<.001, and -24±6 vs -29±4; P=.01, respectively), with the most prominent impairment at the basal segments. Right ventricular longitudinal strain and radial displacement were diminished in patients with cardiac involvement (-9±3 vs -17±3; P<.001, and 2.7±0.8 vs 3.8±0.3; P=.002). On multivariate analysis, left ventricular longitudinal strain was associated with the presence of cardiac involvement (odds ratio = 1.6; 95% confidence interval, 1.04 to 2.37; P=.03) independent of the presence of brain natriuretic peptide and troponin I criteria for cardiac amyloidosis. Three-dimensional-speckle tracking echocardiography-derived left and right ventricular myocardial mechanics are increasingly altered as brain natriuretic peptide increases in light chain amyloidosis. There appears to be a strong association between left ventricular longitudinal strain and cardiac involvement, beyond biomarkers such as brain natriuretic peptide and troponin I. Copyright © 2015 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Projected impact of the ICD-10-CM/PCS conversion on longitudinal data and the Joint Commission Core Measures.

PubMed

Fenton, Susan H; Benigni, Mary Sue

2014-01-01

The transition from ICD-9-CM to ICD-10-CM/PCS is expected to result in longitudinal data discontinuities, as occurred with cause-of-death in 1999. The General Equivalence Maps (GEMs), while useful for suggesting potential maps do not provide guidance regarding the frequency of any matches. Longitudinal data comparisons can only be reliable if they use comparability ratios or factors which have been calculated using records coded in both classification systems. This study utilized 3,969 de-identified dually coded records to examine raw comparability ratios, as well as the comparability ratios between the Joint Commission Core Measures. The raw comparability factor results range from 16.216 for Nicotine dependence, unspecified, uncomplicated to 118.009 for Chronic obstructive pulmonary disease, unspecified. The Joint Commission Core Measure comparability factor results range from 27.15 for Acute Respiratory Failure to 130.16 for Acute Myocardial Infarction. These results indicate significant differences in comparability between ICD-9-CM and ICD-10-CM code assignment, including when the codes are used for external reporting such as the Joint Commission Core Measures. To prevent errors in decision-making and reporting, all stakeholders relying on longitudinal data for measure reporting and other purposes should investigate the impact of the conversion on their data.

Abnormal skeletal growth patterns in adolescent idiopathic scoliosis--a longitudinal study until skeletal maturity.

PubMed

Yim, Annie P Y; Yeung, Hiu-Yan; Hung, Vivian W Y; Lee, Kwong-Man; Lam, Tsz-Ping; Ng, Bobby K W; Qiu, Yong; Cheng, Jack C Y

2012-08-15

A cross-sectional and prospective longitudinal study on the anthropometric parameters and growth pattern of girls with adolescent idiopathic scoliosis (AIS). To investigate the growth pattern of girls with AIS with different severities, using cross-sectional and prospective longitudinal data set in comparison with age-matched healthy controls. AIS occurs in children during their pubertal growth spurt. Although there is no clear consensus on the difference in body height between girls with AIS and healthy controls, it is generally thought that the development and curve progression in girls with AIS is closely associated with their growth rate. There is no concrete prospective longitudinal study to document clearly the growth pattern and growth rate of subjects with AIS . A total of 611 girls with AIS and 296 healthy age-matched controls were included in the study and among them, 194 girls with AIS and 116 healthy controls were followed up until skeletal maturity. The girls with AIS were grouped into moderate (AIS20) and severe curve (AIS40) groups on the basis of maximum curve magnitude at skeletal maturity. Clinical data and detailed anthropometric parameters were recorded. In the cross-sectional analysis, the groups of subjects were compared within different age groups (from the age of 12-16 yr). In the longitudinal study, linear mixed modeling with respect to age or years since menarche was employed to formulate the growth trajectory of different anthropometric parameters. In the cross-sectional analysis, the girls with AIS were generally taller, with longer arm span and lower body mass index than the healthy controls. The girls with AIS40 were found to be significantly shorter in height (P = 0.006) and arm span (P = 0.025) at the age of 12 years but caught up and overtook the control group at the age of 14 to 16 years. In the longitudinal study, the average growth rate of arm span in girls with AIS40 was significantly higher than that in girls with AIS20 (> 30%) (P = 0.004) and controls (> 70%) (P = 0.0004). The age of menarche of girls with AIS40 was significantly delayed by 5.9 months and 3.8 months when compared with the control group and girls with AIS20, respectively (P < 0.05). The growth patterns of girls with AIS with confirmed curve severities were significantly different from healthy age-matched controls. Girls with severe AIS had delayed menarche with faster skeletal growth rate during the age of 12 to 16 years. Monitoring the rate of change of arm span of girls with AIS could be an important additional clinical parameter in helping predict curve severity in girls with AIS.

Effect of miscarriage history on maternal-infant bonding during the first year postpartum in the first baby study: a longitudinal cohort study.

PubMed

Bicking Kinsey, Cara; Baptiste-Roberts, Kesha; Zhu, Junjia; Kjerulff, Kristen H

2014-07-15

Miscarriage, the unexpected loss of pregnancy before 20 weeks gestation, may have a negative effect on a mother's perception of herself as a capable woman and on her emotional health when she is pregnant again subsequent to the miscarriage. As such, a mother with a history of miscarriage may be at greater risk for difficulties navigating the process of becoming a mother and achieving positive maternal-infant bonding with an infant born subsequent to the loss. The aim of this study was to examine the effect of miscarriage history on maternal-infant bonding after the birth of a healthy infant to test the hypothesis that women with a history of miscarriage have decreased maternal-infant bonding compared to women without a history of miscarriage. We completed secondary analysis of the First Baby Study, a longitudinal cohort study, to examine the effect of a history of miscarriage on maternal-infant bonding at 1 month, 6 months, and 12 months after women experienced the birth of their first live-born baby. In a sample of 2798 women living in Pennsylvania, USA, we tested our hypothesis using linear regression analysis of Shortened Postpartum Bonding Questionnaire (S-PBQ) scores, followed by longitudinal analysis using a generalized estimating equations model with repeated measures. We found that women with a history of miscarriage had similar S-PBQ scores as women without a history of miscarriage at each of the three postpartum time points. Likewise, longitudinal analysis revealed no difference in the pattern of maternal-infant bonding scores between women with and without a history of miscarriage. Women in the First Baby Study with a history of miscarriage did not differ from women without a history of miscarriage in their reported level of bonding with their subsequently born infants. It is important for clinicians to recognize that even though some women may experience impaired bonding related to a history of miscarriage, the majority of women form a healthy bond with their infant despite this history.

Effect of miscarriage history on maternal-infant bonding during the first year postpartum in the First Baby Study: a longitudinal cohort study

PubMed Central

2014-01-01

Background Miscarriage, the unexpected loss of pregnancy before 20 weeks gestation, may have a negative effect on a mother’s perception of herself as a capable woman and on her emotional health when she is pregnant again subsequent to the miscarriage. As such, a mother with a history of miscarriage may be at greater risk for difficulties navigating the process of becoming a mother and achieving positive maternal-infant bonding with an infant born subsequent to the loss. The aim of this study was to examine the effect of miscarriage history on maternal-infant bonding after the birth of a healthy infant to test the hypothesis that women with a history of miscarriage have decreased maternal-infant bonding compared to women without a history of miscarriage. Methods We completed secondary analysis of the First Baby Study, a longitudinal cohort study, to examine the effect of a history of miscarriage on maternal-infant bonding at 1 month, 6 months, and 12 months after women experienced the birth of their first live-born baby. In a sample of 2798 women living in Pennsylvania, USA, we tested our hypothesis using linear regression analysis of Shortened Postpartum Bonding Questionnaire (S-PBQ) scores, followed by longitudinal analysis using a generalized estimating equations model with repeated measures. Results We found that women with a history of miscarriage had similar S-PBQ scores as women without a history of miscarriage at each of the three postpartum time points. Likewise, longitudinal analysis revealed no difference in the pattern of maternal-infant bonding scores between women with and without a history of miscarriage. Conclusions Women in the First Baby Study with a history of miscarriage did not differ from women without a history of miscarriage in their reported level of bonding with their subsequently born infants. It is important for clinicians to recognize that even though some women may experience impaired bonding related to a history of miscarriage, the majority of women form a healthy bond with their infant despite this history. PMID:25028056

Otoacoustic emissions versus audiometry in monitoring hearing loss after long-term noise exposure - a systematic review.

PubMed

Helleman, Hiske W; Eising, Hilde; Limpens, Jacqueline; Dreschler, Wouter A

2018-03-15

Objectives The objective of this systematic review was to compare otoacoustic emissions (OAE) with audiometry in their effectiveness to monitor effects of long-term noise exposure on hearing. Methods We conducted a systematic search of MEDLINE, Embase and the non-MEDLINE subset of PubMed up to March 2016 to identify longitudinal studies on effects of noise exposure on hearing as determined by both audiometry and OAE. Results This review comprised 13 articles, with 30-350 subjects in the longitudinal analysis. A meta-analysis could not be performed because the studies were very heterogeneous in terms of measurement paradigms, follow-up time, age of included subjects, inclusion of data points, outcome parameters and method of analysis. Overall there seemed to be small changes in both audiometry and OAE over time. Individual shifts were detected by both methods but a congruent pattern could not be observed. Some studies found that initial abnormal or low-level emissions might predict future hearing loss but at the cost of low specificity due to a high number of false positives. Other studies could not find such predictive value. Conclusions The reported heterogeneity in the studies calls for more uniformity in including, reporting and analyzing longitudinal data for audiometry and OAE. For the overall results, both methods showed small changes from baseline towards a deterioration in hearing. OAE could not reliably detect threshold shifts at individual level. With respect to the predictive value of OAE, the evidence was not conclusive and studies were not in agreement. The reported predictors had low specificity.

Relationship between white matter lesions and regional cerebral blood flow changes during longitudinal follow up in Alzheimer's disease.

PubMed

Hanaoka, Takuya; Kimura, Noriyuki; Aso, Yasuhiro; Takemaru, Makoto; Kimura, Yuki; Ishibashi, Masato; Matsubara, Etsuro

2016-07-01

The aim of the present study was to evaluate the relationship between baseline white matter lesions (WML) and changes in regional cerebral blood flow during longitudinal follow up of patients with Alzheimer's disease (AD). A total of 38 patients with AD were included in the study (16 men, 22 women; mean age 77.8 years). All patients were evaluated using the Mini-Mental State Examination and brain perfusion single-photon emission computed tomography at baseline with an approximately 2-year follow up. The patients were divided into two subgroups according to the presence of WML on magnetic resonance imaging. Single-photon emission computed tomography data were analyzed using a voxel-by-voxel group analysis with Statistical Parametric Mapping 8 and region of interest analysis using FineSRT. Changes in Mini-Mental State Examination scores and regional cerebral blood flow were analyzed using the Wilcoxon signed-rank test. Mean Mini-Mental State Examination scores in AD patients with WML significantly decreased from 19.4 ± 4.8 to 15.5 ± 6.5 (P = 0.003). Statistical Parametric Mapping 8 and FineSRT analysis showed more severe and widespread regional cerebral blood flow reduction, mainly in the frontal and mesial temporal regions in AD patients with WML compared with those without WML. Baseline WML could predict a rapid progression of cognitive and brain functional impairment during longitudinal follow up in AD. Geriatr Gerontol Int 2016; 16: 836-842. © 2015 Japan Geriatrics Society.

Applying the Nominal Response Model within a Longitudinal Framework to Construct the Positive Family Relationships Scale

ERIC Educational Resources Information Center

Preston, Kathleen Suzanne Johnson; Parral, Skye N.; Gottfried, Allen W.; Oliver, Pamella H.; Gottfried, Adele Eskeles; Ibrahim, Sirena M.; Delany, Danielle

2015-01-01

A psychometric analysis was conducted using the nominal response model under the item response theory framework to construct the Positive Family Relationships scale. Using data from the Fullerton Longitudinal Study, this scale was constructed within a long-term longitudinal framework spanning middle childhood through adolescence. Items tapping…

Training, Innovation and Business Performance: An Analysis of the Business Longitudinal Survey.

ERIC Educational Resources Information Center

Dockery, A. Michael

This paper uses the Australian Bureau of Statistics' Business Longitudinal Survey to explore relationships between training, innovation, and firm performance for Australian businesses with less than 200 employees. The longitudinal nature of the data is used to test various hypotheses about the nature of the link between training, business changes,…

Young adult outcomes of children growing up with chronic illness: an analysis of the National Longitudinal Study of Adolescent Health.

PubMed

Maslow, Gary R; Haydon, Abigail A; Ford, Carol Ann; Halpern, Carolyn Tucker

2011-03-01

To examine young adult outcomes in a nationally representative US cohort of young adults growing up with a chronic illness. Secondary analysis of nationally representative data from wave III (in 2001) of the National Longitudinal Study of Adolescent Health. United States. The analytic sample comprised 13 236 young adults aged 18 to 28 years at wave III. Self-report of a chronic physical illness (asthma, cancer, diabetes mellitus, or epilepsy) in adolescence. Respondents with asthma or nonasthmatic chronic illness (cancer, diabetes mellitus, or epilepsy) were compared with individuals without these conditions. Self-report of high school graduation, ever having employment, currently having employment, living with a parent/guardian, and ever receiving public assistance. Three percent of young adults had nonasthmatic chronic illness (cancer, diabetes, or epilepsy), and 16.0% had asthma. Most young adults with chronic illness graduated high school (81.3%) and currently had employment (60.4%). However, compared with healthy young adults, those with nonasthmatic chronic illness were significantly less likely to graduate high school, ever have had employment, or currently have employment and were more likely to receive public assistance. Compared with young adults with asthma, those with nonasthmatic chronic illness again had significantly worse young adult outcomes on all measures. Most young adults growing up with a chronic illness graduate high school and have employment. However, these young adults are significantly less likely than their healthy peers to achieve these important educational and vocational milestones.

Transversely polarized source cladding for an optical fiber

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

1994-01-01

An optical fiber comprising a fiber core having a longitudinal symmetry axis is provided. An active cladding surrounds a portion of the fiber core and comprises light-producing sources which emit light in response to chemical or light excitation. The cladding sources are oriented transversely with respect to the longitudinal axis of the fiber core. This polarization results in a superior power efficiency compared to active cladding sources that are randomly polarized or longitudinally polarized parallel with the longitudinal symmetry axis.

Vocal fold immobility: a longitudinal analysis of etiology over 20 years.

PubMed

Rosenthal, Laura H Swibel; Benninger, Michael S; Deeb, Robert H

2007-10-01

To determine the current etiology of vocal fold immobility, identify changing trends over the last 20 years, and compare results to historical reports. The present study is a retrospective analysis of all patients seen within a tertiary care institution between 1996 and 2005 with vocal fold immobility. The results were combined with a previous study of patients within the same institution from 1985 through 1995. Results were compared to the literature. The medical records of all patients assigned a primary or additional diagnostic code for vocal cord paralysis were obtained from the electronic database. Eight hundred twenty-seven patients were available for analysis (435 from the most recent cohort), which is substantially larger than any reported series to date. Vocal fold immobility was most commonly associated with a surgical procedure (37%). Nonthyroid surgeries (66%), such as anterior cervical approaches to the spine and carotid endarterectomies, have surpassed thyroid surgery (33%) as the most common iatrogenic causes. These data represent a change from historical figures in which extralaryngeal malignancies were considered the major cause of unilateral immobility. Thyroidectomy continues to cause the majority (80%) of iatrogenic bilateral vocal fold immobility and 30% of all bilateral immobility. This 20-year longitudinal assessment revealed that the etiology of unilateral vocal fold immobility has changed such that there has been a shift from extralaryngeal malignancies to nonthyroid surgical procedures as the major cause. Thyroid surgery remains the most common cause of bilateral vocal fold immobility.

The reduction of health care costs associated with alcoholism treatment: a 14-year longitudinal study.

PubMed

Holder, H D; Blose, J O

1992-07-01

This study utilized two separate research designs to examine whether the initiation of alcoholism treatment is associated with a change in overall medical care cost in a population of alcoholics enrolled under a health plan sponsored by a large midwestern manufacturing corporation. In the longest longitudinal study of alcoholism treatment costs to date, a review of claims filed from 1974 to 1987 identified 3,729 alcoholics (3,068 of whom received treatment and 661 of whom did not). In one design, a time-series analysis found that following treatment initiation the total health care costs of treated alcoholics--including the cost of alcoholism treatment--declined by 23% to 55% from their highest pretreatment levels. Costs for identified but untreated alcoholics rose following identification. In a second design, analysis of variance was used to control for group differences including pretreatment health status and age. This analysis indicated that the posttreatment costs of treated alcoholics were 24% lower than comparable costs for untreated alcoholics. The study provides considerable evidence that alcoholism treatment can reduce overall medical costs in a heterogeneous alcoholic population (white collar/blue collar; fee-for-service/HMO).

Strategies for Longitudinal Analysis of the Career Paths of Beginning Teachers: Results from the First through Fourth Waves of the 2007-08 Beginning Teacher Longitudinal Study. Research and Development Report. NCES 2013-336

ERIC Educational Resources Information Center

Gray, Lucinda; Brauen, Marsha

2013-01-01

To learn more about the early career patterns of beginning teachers, the National Center for Education Statistics (NCES) of the Institute of Education Sciences within the U.S. Department of Education undertook the Beginning Teacher Longitudinal Study (BTLS). The ultimate purpose of this report is to develop a strategy for the longitudinal analysis…

Depression as a risk factor for dementia and mild cognitive impairment: a meta-analysis of longitudinal studies.

PubMed

Gao, Yuan; Huang, Changquan; Zhao, Kexiang; Ma, Louyan; Qiu, Xuan; Zhang, Lei; Xiu, Yun; Chen, Lin; Lu, Wei; Huang, Chunxia; Tang, Yong; Xiao, Qian

2013-05-01

This study examined whether depression was a risk factor for onset of dementia including Alzheimer's disease (AD), vascular dementia (VD) and any dementia, and mild cognitive impairment (MCI) by using a quantitative meta-analysis of longitudinal studies. EMBASE and MEDLINE were searched for articles published up to February 2011. All studies that examined the relationship between depression and the onset of dementia or MCI were included. Pooled relative risk was calculated using fixed-effects models. Twelve studies met our inclusion criteria for this meta-analysis. All subjects were without dementia or MCI at baseline. Four, two, five, and four studies compared the incidence of AD, VD, any dementia, and MCI between subjects with or without depression, respectively. After pooling all the studies, subjects with depression had higher incidence of AD (relative risk (RR):1.66, 95% confidence interval (CI): 1.29-2.14), VD (RR: 1.89, 95% CI: 1.19-3.01), any dementia (RR: 1.55, 95% CI: 1.31-2.83), and MCI (RR: 1.97, 95% CI: 1.53-2.54) than those without depression. The quantitative meta-analysis showed that depression was a major risk factor for incidence of dementia (including AD, VD, and any dementia) and MCI. Copyright © 2012 John Wiley & Sons, Ltd.

Improving the clinical correlation of multiple sclerosis black hole volume change by paired-scan analysis.

PubMed

Tam, Roger C; Traboulsee, Anthony; Riddehough, Andrew; Li, David K B

2012-01-01

The change in T 1-hypointense lesion ("black hole") volume is an important marker of pathological progression in multiple sclerosis (MS). Black hole boundaries often have low contrast and are difficult to determine accurately and most (semi-)automated segmentation methods first compute the T 2-hyperintense lesions, which are a superset of the black holes and are typically more distinct, to form a search space for the T 1w lesions. Two main potential sources of measurement noise in longitudinal black hole volume computation are partial volume and variability in the T 2w lesion segmentation. A paired analysis approach is proposed herein that uses registration to equalize partial volume and lesion mask processing to combine T 2w lesion segmentations across time. The scans of 247 MS patients are used to compare a selected black hole computation method with an enhanced version incorporating paired analysis, using rank correlation to a clinical variable (MS functional composite) as the primary outcome measure. The comparison is done at nine different levels of intensity as a previous study suggests that darker black holes may yield stronger correlations. The results demonstrate that paired analysis can strongly improve longitudinal correlation (from -0.148 to -0.303 in this sample) and may produce segmentations that are more sensitive to clinically relevant changes.

A comprehensive tractography study of patients with bipolar disorder and their unaffected siblings.

PubMed

Sprooten, Emma; Barrett, Jennifer; McKay, D Reese; Knowles, Emma E; Mathias, Samuel R; Winkler, Anderson M; Brumbaugh, Margaret S; Landau, Stefanie; Cyr, Lindsay; Kochunov, Peter; Glahn, David C

2016-10-01

Diffusion tensor imaging studies show reductions in fractional anisotropy (FA) in individuals with bipolar disorder and their unaffected siblings. However, the use of various analysis methods is an important source of between-study heterogeneity. Using tract-based spatial statistics, we previously demonstrated widespread FA reductions in patients and unaffected relatives. To better interpret the neuroanatomical pattern of this previous finding and to assess the influence of methodological heterogeneity, we here applied tractography to the same sample. Diffusion-weighted images were acquired for 96 patients, 69 unaffected siblings and 56 controls. We applied TRACULA, an extension of a global probabilistic tractography algorithm, to automatically segment 18 major fiber tracts. Average FA within each tract and at each cross-section along each tract was compared between groups. Patients had reduced FA compared to healthy controls and their unaffected siblings in general, and in particular in the parietal part of the superior longitudinal fasciculus. In unaffected siblings, FA was nominally reduced compared to controls in the corpus callosum. Point-wise analyses indicated that similar effects were present along extended sections, but with variable effect sizes. Current symptom severity negatively correlated with FA in several fronto-limbic association tracts. The differential sensitivity of analysis techniques likely explains between-study heterogeneity in anatomical localization of FA reductions. The present tractography analysis confirms the presence of overall FA reductions in patients with bipolar disorder, which are most pronounced in the superior longitudinal fasciculus. Unaffected siblings may display similar, albeit more subtle and anatomically restricted FA reductions. Hum Brain Mapp 37:3474-3485, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Prediction of coefficients of thermal expansion for unidirectional composites

NASA Technical Reports Server (NTRS)

Bowles, David E.; Tompkins, Stephen S.

1989-01-01

Several analyses for predicting the longitudinal, alpha(1), and transverse, alpha(2), coefficients of thermal expansion of unidirectional composites were compared with each other, and with experimental data on different graphite fiber reinforced resin, metal, and ceramic matrix composites. Analytical and numerical analyses that accurately accounted for Poisson restraining effects in the transverse direction were in consistently better agreement with experimental data for alpha(2), than the less rigorous analyses. All of the analyses predicted similar values of alpha(1), and were in good agreement with the experimental data. A sensitivity analysis was conducted to determine the relative influence of constituent properties on the predicted values of alpha(1), and alpha(2). As would be expected, the prediction of alpha(1) was most sensitive to longitudinal fiber properties and the prediction of alpha(2) was most sensitive to matrix properties.

X-ray measurements of the strain and shape of dielectric/metallic wrap-gated InAs nanowires

NASA Astrophysics Data System (ADS)

Eymery, J.; Favre-Nicolin, V.; Fröberg, L.; Samuelson, L.

2009-03-01

Wrap-gate (111) InAs nanowires (NWs) were studied after HfO2 dielectric coating and Cr metallic deposition by a combination of grazing incidence x-ray techniques. In-plane and out-of-plane x-ray diffraction (crystal truncation rod analysis) allow determining the strain tensor. The longitudinal contraction, increasing with HfO2 and Cr deposition, is significantly larger than the radial dilatation. For the Cr coating, the contraction along the growth axis is quite large (-0.95%), and the longitudinal/radial deformation ratio is >10, which may play a role on the NW transport properties. Small angle x-ray scattering shows a smoothening of the initial hexagonal bare InAs NW shape and gives the respective core/shell thicknesses, which are compared to flat surface values.

Electromagnetic scaling functions within the Green's function Monte Carlo approach

DOE PAGES

Rocco, N.; Alvarez-Ruso, L.; Lovato, A.; ...

2017-07-24

We have studied the scaling properties of the electromagnetic response functions of 4He and 12C nuclei computed by the Green's function Monte Carlo approach, retaining only the one-body current contribution. Longitudinal and transverse scaling functions have been obtained in the relativistic and nonrelativistic cases and compared to experiment for various kinematics. The characteristic asymmetric shape of the scaling function exhibited by data emerges in the calculations in spite of the nonrelativistic nature of the model. The results are mostly consistent with scaling of zeroth, first, and second kinds. Our analysis reveals a direct correspondence between the scaling and the nucleon-densitymore » response functions. In conclusion, the scaling function obtained from the proton-density response displays scaling of the first kind, even more evidently than the longitudinal and transverse scaling functions« less

Electromagnetic scaling functions within the Green's function Monte Carlo approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocco, N.; Alvarez-Ruso, L.; Lovato, A.

We have studied the scaling properties of the electromagnetic response functions of 4He and 12C nuclei computed by the Green's function Monte Carlo approach, retaining only the one-body current contribution. Longitudinal and transverse scaling functions have been obtained in the relativistic and nonrelativistic cases and compared to experiment for various kinematics. The characteristic asymmetric shape of the scaling function exhibited by data emerges in the calculations in spite of the nonrelativistic nature of the model. The results are mostly consistent with scaling of zeroth, first, and second kinds. Our analysis reveals a direct correspondence between the scaling and the nucleon-densitymore » response functions. In conclusion, the scaling function obtained from the proton-density response displays scaling of the first kind, even more evidently than the longitudinal and transverse scaling functions« less

A high accuracy sequential solver for simulation and active control of a longitudinal combustion instability

NASA Technical Reports Server (NTRS)

Shyy, W.; Thakur, S.; Udaykumar, H. S.

1993-01-01

A high accuracy convection scheme using a sequential solution technique has been developed and applied to simulate the longitudinal combustion instability and its active control. The scheme has been devised in the spirit of the Total Variation Diminishing (TVD) concept with special source term treatment. Due to the substantial heat release effect, a clear delineation of the key elements employed by the scheme, i.e., the adjustable damping factor and the source term treatment has been made. By comparing with the first-order upwind scheme previously utilized, the present results exhibit less damping and are free from spurious oscillations, offering improved quantitative accuracy while confirming the spectral analysis reported earlier. A simple feedback type of active control has been found to be capable of enhancing or attenuating the magnitude of the combustion instability.

"Development in Reverse?" A Longitudinal Analysis of Armed Conflict, Fragility and School Enrolment

ERIC Educational Resources Information Center

Shields, Robin; Paulson, Julia

2015-01-01

This paper presents a longitudinal analysis of cross-national data on armed conflict, state fragility, and enrolment in primary and secondary schooling. The study is motivated by questions raised in the 2012 "Human Security Report," which challenges the widely held assumption that conflict is necessarily detrimental to educational…

Modeling Associations among Multivariate Longitudinal Categorical Variables in Survey Data: A Semiparametric Bayesian Approach

ERIC Educational Resources Information Center

Tchumtchoua, Sylvie; Dey, Dipak K.

2012-01-01

This paper proposes a semiparametric Bayesian framework for the analysis of associations among multivariate longitudinal categorical variables in high-dimensional data settings. This type of data is frequent, especially in the social and behavioral sciences. A semiparametric hierarchical factor analysis model is developed in which the…

A Longitudinal Analysis of Factors Related to Survival in Old Age.

ERIC Educational Resources Information Center

Shahtahmasebi, Said; And Others

1992-01-01

Used data from a longitudinal study of elderly which began in 1979 with 534 individuals in rural North Wales to study relationship between social circumstances and longevity. Multivariate analysis demonstrated there is no prima facie evidence that survival is affected by social networks or quality of life factors. However, socioeconomic factors…

Applying Longitudinal Mean and Covariance Structures (LMACS) Analysis to Assess Construct Stability Over Two Time Points: An Example Using Psychological Entitlement

ERIC Educational Resources Information Center

Bashkov, Bozhidar M.; Finney, Sara J.

2013-01-01

Traditional methods of assessing construct stability are reviewed and longitudinal mean and covariance structures (LMACS) analysis, a modern approach, is didactically illustrated using psychological entitlement data. Measurement invariance and latent variable stability results are interpreted, emphasizing substantive implications for educators and…

Construction strength analysis of landing craft tank conversion to passenger ship using finite element method

NASA Astrophysics Data System (ADS)

Nurul Misbah, Mohammad; Setyawan, Dony; Murti Dananjaya, Wisnu

2018-03-01

This research aims to determine the longitudinal strength of passenger ship which was converted from Landing Craft Tank with 54 m of length as stated by BKI (Biro Klasifikasi Indonesia / Indonesian Classification Bureau). Verification of strength value is done to 4 (four) loading conditions which are (1) empty load condition during sagging wave, (2) empty load condition during hogging wave, (3) full load condition during sagging wave and (4) full load condition during hogging wave. Analysis is done using Finite Element Analysis (FEA) software by modeling the entire part of passenger ship and its loading condition. The back and upfront part of ship centerline were used as the boundary condition. From that analysis it can be concluded that the maximum stress for load condition (1) is 72,393 MPa, 74,792 MPa for load condition (2), 129,92 MPa for load condition (3), and 132,4 MPa for load condition (4). Longitudinal strength of passenger ship fulfilled the criteria of empty load condition having smaller stress value than allowable stress which is 90 MPa, and during full load condition with smaller stress value than allowable stress which is 150 MPa. Analysis on longitudinal strength comparison with entire ship plate thickness variation of ± 2 mm from initial plate was also done during this research. From this research it can be concluded that plate thickness reduction causes the value of longitudinal strength to decrease, while plate thickness addition causes the value of longitudinal strength to increase.

Event History Data and Survey Recall. An Analysis of the Longitudinal Survey of Youth 1979 Recall Experiment.

ERIC Educational Resources Information Center

Pierret, Charles R.

2001-01-01

To test the effect of less-frequent interviews on data quality in longitudinal surveys, event history data from the National Longitudinal Survey of Youth 1979 regarding welfare and employment were analyzed. Due to the longer recall period, respondents failed to report short spells of welfare, employment, and unemployment. (SK)

Using Longitudinal Assessment Data to Improve Retention and Student Experiences

ERIC Educational Resources Information Center

Trosset, Carol; Weisler, Steven

2010-01-01

The Wabash National Study of Liberal Arts Education presents a longitudinal analysis of how students change on a number of scales that purport to measure many of the outcomes of liberal learning over the span of a college education. The Wabash Study is designed to collect information longitudinally from students at the beginning and end of their…

Application of the Levenshtein Distance Metric for the Construction of Longitudinal Data Files

ERIC Educational Resources Information Center

Doran, Harold C.; van Wamelen, Paul B.

2010-01-01

The analysis of longitudinal data in education is becoming more prevalent given the nature of testing systems constructed for No Child Left Behind Act (NCLB). However, constructing the longitudinal data files remains a significant challenge. Students move into new schools, but in many cases the unique identifiers (ID) that should remain constant…

Differences in neutral foot positions when measured barefoot compared to in shoes with varying stiffnesses.

PubMed

Shultz, R; Birmingham, T B; Jenkyn, T R

2011-12-01

This study examined the absolute differences in neutral positions of the joints of the foot with different footwear. This addresses the question of whether separate static trials should be collected for each footwear condition to establish neutral positions. A multi-segment kinematic foot model and optical motion analysis system measured four inter-segmental joints of the foot: (1) hindfoot-to-midfoot in the frontal plane, (2) forefoot-to-midfoot in the frontal plane, (3) hallux-to-forefoot in the sagittal plane, and (4) the height-to-length ratio of the medial longitudinal arch. Barefoot was compared to three shoe condition using Nike Free trainers of varying longitudinal torsional stiffness in ten male volunteers. There was high variability both within subjects and shoe conditions. Shoes in general tended to raise the medial longitudinal arch and dorsiflex the hallux compared to barefoot condition. For the hallux, a minimum important difference of 5° or more was found between shoe conditions and the barefoot condition for majority of the subjects in all three shoe conditions (90% for control, 60% for least stiff, 50% for most stiff). This was less for the frontal plane inter-segmental joints of the foot where 50% of the subjects experience a change above 5° for at least one of the conditions. The choice of using condition-specific neutral trials versus a single common neutral trials should be considered carefully. A single common trial allows for differences in absolute joint angles to be compared between footwear conditions. This can be important clinically to determine whether a joint is approaching its end-of-range and therefore at risk of injury. Several condition-specific neutral trials allows for subtleties in kinematic waveforms to be better compared between conditions, since absolute shifts in joint angles due to changing neutral position are removed and the waveforms are better aligned. Copyright © 2011. Published by Elsevier Ltd.

Longitudinal bunch monitoring at the Fermilab Tevatron and Main Injector synchrotrons

DOE PAGES

Thurman-Keup, R.; Bhat, C.; Blokland, W.; ...

2011-10-17

The measurement of the longitudinal behavior of the accelerated particle beams at Fermilab is crucial to the optimization and control of the beam and the maximizing of the integrated luminosity for the particle physics experiments. Longitudinal measurements in the Tevatron and Main Injector synchrotrons are based on the analysis of signals from resistive wall current monitors. This study describes the signal processing performed by a 2 GHz-bandwidth oscilloscope together with a computer running a LabVIEW program which calculates the longitudinal beam parameters.

Regional vulnerability of longitudinal cortical association connectivity: Associated with structural network topology alterations in preterm children with cerebral palsy.

PubMed

Ceschin, Rafael; Lee, Vince K; Schmithorst, Vince; Panigrahy, Ashok

2015-01-01

Preterm born children with spastic diplegia type of cerebral palsy and white matter injury or periventricular leukomalacia (PVL), are known to have motor, visual and cognitive impairments. Most diffusion tensor imaging (DTI) studies performed in this group have demonstrated widespread abnormalities using averaged deterministic tractography and voxel-based DTI measurements. Little is known about structural network correlates of white matter topography and reorganization in preterm cerebral palsy, despite the availability of new therapies and the need for brain imaging biomarkers. Here, we combined novel post-processing methodology of probabilistic tractography data in this preterm cohort to improve spatial and regional delineation of longitudinal cortical association tract abnormalities using an along-tract approach, and compared these data to structural DTI cortical network topology analysis. DTI images were acquired on 16 preterm children with cerebral palsy (mean age 5.6 ± 4) and 75 healthy controls (mean age 5.7 ± 3.4). Despite mean tract analysis, Tract-Based Spatial Statistics (TBSS) and voxel-based morphometry (VBM) demonstrating diffusely reduced fractional anisotropy (FA) reduction in all white matter tracts, the along-tract analysis improved the detection of regional tract vulnerability. The along-tract map-structural network topology correlates revealed two associations: (1) reduced regional posterior-anterior gradient in FA of the longitudinal visual cortical association tracts (inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiation, posterior thalamic radiation) correlated with reduced posterior-anterior gradient of intra-regional (nodal efficiency) metrics with relative sparing of frontal and temporal regions; and (2) reduced regional FA within frontal-thalamic-striatal white matter pathways (anterior limb/anterior thalamic radiation, superior longitudinal fasciculus and cortical spinal tract) correlated with alteration in eigenvector centrality, clustering coefficient (inter-regional) and participation co-efficient (inter-modular) alterations of frontal-striatal and fronto-limbic nodes suggesting re-organization of these pathways. Both along tract and structural topology network measurements correlated strongly with motor and visual clinical outcome scores. This study shows the value of combining along-tract analysis and structural network topology in depicting not only selective parietal occipital regional vulnerability but also reorganization of frontal-striatal and frontal-limbic pathways in preterm children with cerebral palsy. These finding also support the concept that widespread, but selective posterior-anterior neural network connectivity alterations in preterm children with cerebral palsy likely contribute to the pathogenesis of neurosensory and cognitive impairment in this group.

Comparison between a new computer program and the reference software for gray-scale median analysis of atherosclerotic carotid plaques.

PubMed

Casella, Ivan Benaduce; Fukushima, Rodrigo Bono; Marques, Anita Battistini de Azevedo; Cury, Marcus Vinícius Martins; Presti, Calógero

2015-03-01

To compare a new dedicated software program and Adobe Photoshop for gray-scale median (GSM) analysis of B-mode images of carotid plaques. A series of 42 carotid plaques generating ≥50% diameter stenosis was evaluated by a single observer. The best segment for visualization of internal carotid artery plaque was identified on a single longitudinal view and images were recorded in JPEG format. Plaque analysis was performed by both programs. After normalization of image intensity (blood = 0, adventitial layer = 190), histograms were obtained after manual delineation of plaque. Results were compared with nonparametric Wilcoxon signed rank test and Kendall tau-b correlation analysis. GSM ranged from 00 to 100 with Adobe Photoshop and from 00 to 96 with IMTPC, with a high grade of similarity between image pairs, and a highly significant correlation (R = 0.94, p < .0001). IMTPC software appears suitable for the GSM analysis of carotid plaques. © 2014 Wiley Periodicals, Inc.

A Multi-Stage Longitudinal Comparative Design Stage II Evaluation of the Changing Lives Program: The Life Course Interview (RDA-LCI)

ERIC Educational Resources Information Center

Arango, Lisa Lewis; Kurtines, William M.; Montgomery, Marilyn J.; Ritchie, Rachel

2008-01-01

The study reported in this article, a Multi-Stage Longitudinal Comparative Design Stage II evaluation conducted as a planned preliminary efficacy evaluation (psychometric evaluation of measures, short-term controlled outcome studies, etc.) of the Changing Lives Program (CLP), provided evidence for the reliability and validity of the qualitative…

Joint principal trend analysis for longitudinal high-dimensional data.

PubMed

Zhang, Yuping; Ouyang, Zhengqing

2018-06-01

We consider a research scenario motivated by integrating multiple sources of information for better knowledge discovery in diverse dynamic biological processes. Given two longitudinal high-dimensional datasets for a group of subjects, we want to extract shared latent trends and identify relevant features. To solve this problem, we present a new statistical method named as joint principal trend analysis (JPTA). We demonstrate the utility of JPTA through simulations and applications to gene expression data of the mammalian cell cycle and longitudinal transcriptional profiling data in response to influenza viral infections. © 2017, The International Biometric Society.

Peer Influence on Academic Performance: A Social Network Analysis of Social-Emotional Intervention Effects.

PubMed

DeLay, Dawn; Zhang, Linlin; Hanish, Laura D; Miller, Cindy F; Fabes, Richard A; Martin, Carol Lynn; Kochel, Karen P; Updegraff, Kimberly A

2016-11-01

Longitudinal social network analysis (SNA) was used to examine how a social-emotional learning (SEL) intervention may be associated with peer socialization on academic performance. Fifth graders (N = 631; 48 % girls; 9 to 12 years) were recruited from six elementary schools. Intervention classrooms (14) received a relationship building intervention (RBI) and control classrooms (8) received elementary school as usual. At pre- and post-test, students nominated their friends, and teachers completed assessments of students' writing and math performance. The results of longitudinal SNA suggested that the RBI was associated with friend selection and peer influence within the classroom peer network. Friendship choices were significantly more diverse (i.e., less evidence of social segregation as a function of ethnicity and academic ability) in intervention compared to control classrooms, and peer influence on improved writing and math performance was observed in RBI but not control classrooms. The current findings provide initial evidence that SEL interventions may change social processes in a classroom peer network and may break down barriers of social segregation and improve academic performance.

Retrenched Welfare Regimes Still Lessen Social Class Inequalities in Health: A Longitudinal Analysis of the 2003-2010 EU-SILC in 23 European Countries.

PubMed

Muntaner, C; Davis, O; McIsaack, K; Kokkinen, L; Shankardass, K; O'Campo, P

2017-07-01

This article builds on recent work that has explored how welfare regimes moderate social class inequalities in health. It extends research to date by using longitudinal data from the EU-SILC (2003-2010) and examines how the relationship between social class and self-reported health and chronic conditions varies across 23 countries, which are split into five welfare regimes (Nordic, Anglo-Saxon, Eastern, Southern, and Continental). Our analysis finds that health across all classes was only worse in Eastern Europe (compared with the Nordic countries). In contrast, we find evidence that the social class gradient in both measures of health was significantly wider in the Anglo-Saxon and Southern regimes. We suggest that this evidence supports the notion that welfare regimes continue to explain differences in health according to social class location. We therefore argue that although downward pressures from globalization and neoliberalism have blurred welfare regime typologies, the Nordic model may continue to have an important mediating effect on class-based inequalities in health.

Impaired right ventricular contractile function in childhood obesity and its association with right and left ventricular changes: a cine DENSE cardiac magnetic resonance study.

PubMed

Jing, Linyuan; Pulenthiran, Arichanah; Nevius, Christopher D; Mejia-Spiegeler, Abba; Suever, Jonathan D; Wehner, Gregory J; Kirchner, H Lester; Haggerty, Christopher M; Fornwalt, Brandon K

2017-06-28

Pediatric obesity is a growing public health problem, which is associated with increased risk of cardiovascular disease and premature death. Left ventricular (LV) remodeling (increased myocardial mass and thickness) and contractile dysfunction (impaired longitudinal strain) have been documented in obese children, but little attention has been paid to the right ventricle (RV). We hypothesized that obese/overweight children would have evidence of RV remodeling and contractile dysfunction. One hundred and three children, ages 8-18 years, were prospectively recruited and underwent cardiovascular magnetic resonance (CMR), including both standard cine imaging and displacement encoding with stimulated echoes (DENSE) imaging, which allowed for quantification of RV geometry and function/mechanics. RV free wall longitudinal strain was quantified from the end-systolic four-chamber DENSE image. Linear regression was used to quantify correlations of RV strain with LV strain and measurements of body composition (adjusted for sex and height). Analysis of variance was used to study the relationship between RV strain and LV remodeling types (concentric remodeling, eccentric/concentric hypertrophy). The RV was sufficiently visualized with DENSE in 70 (68%) subjects, comprising 36 healthy weight (13.6 ± 2.7 years) and 34 (12.1 ± 2.9 years) obese/overweight children. Obese/overweight children had a 22% larger RV mass index (8.2 ± 0.9 vs 6.7 ± 1.1 g/m 2.7 , p < 0.001) compared to healthy controls. RV free wall longitudinal strain was impaired in obese/overweight children (-16 ± 4% vs -19 ± 5%, p = 0.02). Ten (14%) out of 70 children had LV concentric hypertrophy, and these children had the most impaired RV longitudinal strain compared to those with normal LV geometry (-13 ± 4% vs -19 ± 5%, p = 0.002). RV longitudinal strain was correlated with LV longitudinal strain (r = 0.34, p = 0.004), systolic blood pressure (r = 0.33, p = 0.006), as well as BMI z-score (r = 0.28, p = 0.02), waist (r = 0.31, p = 0.01), hip (r = 0.40, p = 0.004) and abdominal (r = 0.38, p = 0.002) circumference, height and sex adjusted. Obese/overweight children have evidence of RV remodeling (increased RV mass) and RV contractile dysfunction (impaired free wall longitudinal strain). Moreover, RV longitudinal strain correlates with LV longitudinal strain, and children with LV concentric hypertrophy show the most impaired RV function. These results suggest there may be a common mechanism underlying both remodeling and dysfunction of the left and right ventricles in obese/overweight children.

The State of PR Graduate Curriculum as We Know It: A Longitudinal Analysis

ERIC Educational Resources Information Center

Briones, Rowena L.; Toth, Elizabeth L.

2013-01-01

This longitudinal content analysis study uses the Commission on Public Relations Education's 2006 report as a benchmark to determine whether master's education in public relations has evolved over the past decade. Findings show a lack of uniformity across the 75 programs studied. In addition, there is a lack of adherence to the Commission on…

Friendship Quality and School Achievement: A Longitudinal Analysis during Primary School

ERIC Educational Resources Information Center

Zucchetti, Giulia; Candela, Filippo; Sacconi, Beatrice; Rabaglietti, Emanuela

2015-01-01

This study examined the longitudinal relationship between friendship quality (positive and negative) and school achievement among 228 school-age children (51% girls, M = 8.09, SD = 0.41). A three-wave cross-lagged analysis was used to determine the direction of influence between these domains across school years. Findings revealed that: (a) school…

Social Capital, Self-Esteem, and Use of Online Social Network Sites: A Longitudinal Analysis

ERIC Educational Resources Information Center

Steinfield, Charles; Ellison, Nicole B.; Lampe, Cliff

2008-01-01

A longitudinal analysis of panel data from users of a popular online social network site, Facebook, investigated the relationship between intensity of Facebook use, measures of psychological well-being, and bridging social capital. Two surveys conducted a year apart at a large U.S. university, complemented with in-depth interviews with 18 Facebook…

Accolades and Recommendations: A Longitudinal Analysis of Monitoring Reports for Two Charter Schools Serving Native American Students

ERIC Educational Resources Information Center

Anderson, Derek L.; Holder, K. C.

2012-01-01

This longitudinal case study examines 10 years' worth of annual monitoring reports for two rural Native American Charter Schools. Using data from multiple sources including interviews, site visits, and document analyses, the authors used provisional coding and constant comparison analysis to categorize the accolades and recommendations embedded in…

Sensitivity Analysis of Mixed Models for Incomplete Longitudinal Data

ERIC Educational Resources Information Center

Xu, Shu; Blozis, Shelley A.

2011-01-01

Mixed models are used for the analysis of data measured over time to study population-level change and individual differences in change characteristics. Linear and nonlinear functions may be used to describe a longitudinal response, individuals need not be observed at the same time points, and missing data, assumed to be missing at random (MAR),…

Examining the Influence of Campus Climate on Students' Time to Degree: A Multilevel Discrete-Time Survival Analysis

ERIC Educational Resources Information Center

Zhou, Ji; Castellanos, Michelle

2013-01-01

Utilizing longitudinal data of 3477 students from 28 institutions, we examine the effects of structural diversity and quality of interracial relation on students' persistence towards graduation within six years. We utilize multilevel discrete-time survival analysis to account for the longitudinal persistence patterns as well as the nested…

Time-to-Event Analysis of Individual Variables Associated with Nursing Students' Academic Failure: A Longitudinal Study

ERIC Educational Resources Information Center

Dante, Angelo; Fabris, Stefano; Palese, Alvisa

2013-01-01

Empirical studies and conceptual frameworks presented in the extant literature offer a static imagining of academic failure. Time-to-event analysis, which captures the dynamism of individual factors, as when they determine the failure to properly tailor timely strategies, impose longitudinal studies which are still lacking within the field. The…

Longitudinal assessment of treatment effects on pulmonary ventilation using 1H/3He MRI multivariate templates

NASA Astrophysics Data System (ADS)

Tustison, Nicholas J.; Contrella, Benjamin; Altes, Talissa A.; Avants, Brian B.; de Lange, Eduard E.; Mugler, John P.

2013-03-01

The utitlity of pulmonary functional imaging techniques, such as hyperpolarized 3He MRI, has encouraged their inclusion in research studies for longitudinal assessment of disease progression and the study of treatment effects. We present methodology for performing voxelwise statistical analysis of ventilation maps derived from hyper­ polarized 3He MRI which incorporates multivariate template construction using simultaneous acquisition of IH and 3He images. Additional processing steps include intensity normalization, bias correction, 4-D longitudinal segmentation, and generation of expected ventilation maps prior to voxelwise regression analysis. Analysis is demonstrated on a cohort of eight individuals with diagnosed cystic fibrosis (CF) undergoing treatment imaged five times every two weeks with a prescribed treatment schedule.

Experimental demonstration of electron longitudinal-phase-space linearization by shaping the photoinjector laser pulse.

PubMed

Penco, G; Danailov, M; Demidovich, A; Allaria, E; De Ninno, G; Di Mitri, S; Fawley, W M; Ferrari, E; Giannessi, L; Trovó, M

2014-01-31

Control of the electron-beam longitudinal-phase-space distribution is of crucial importance in a number of accelerator applications, such as linac-driven free-electron lasers, colliders and energy recovery linacs. Some longitudinal-phase-space features produced by nonlinear electron beam self- fields, such as a quadratic energy chirp introduced by geometric longitudinal wakefields in radio-frequency (rf) accelerator structures, cannot be compensated by ordinary tuning of the linac rf phases nor corrected by a single high harmonic accelerating cavity. In this Letter we report an experimental demonstration of the removal of the quadratic energy chirp by properly shaping the electron beam current at the photoinjector. Specifically, a longitudinal ramp in the current distribution at the cathode linearizes the longitudinal wakefields in the downstream linac, resulting in a flat electron current and energy distribution. We present longitudinal-phase-space measurements in this novel configuration compared to those typically obtained without longitudinal current shaping at the FERMI linac.

Using a Large Scale Computational Model to Study the Effect of Longitudinal and Radial Electrical Coupling in the Cochlea

NASA Astrophysics Data System (ADS)

Mistrík, Pavel; Ashmore, Jonathan

2009-02-01

We describe a large scale computational model of electrical current flow in the cochlea which is constructed by a flexible Modified Nodal Analysis algorithm to incorporate electrical components representing hair cells and the intercellular radial and longitudinal current flow. The model is used as a laboratory to study the effects of changing longitudinal gap junctional coupling, and shows the way in which cochlear microphonic spreads and tuning is affected. The process for incorporating mechanical longitudinal coupling and feedback is described. We find a difference in tuning and attenuation depending on whether longitudinal or radial couplings are altered.

Differences in Causal Estimates from Longitudinal Analyses of Residualized versus Simple Gain Scores: Contrasting Controls for Selection and Regression Artifacts

ERIC Educational Resources Information Center

Larzelere, Robert E.; Ferrer, Emilio; Kuhn, Brett R.; Danelia, Ketevan

2010-01-01

This study estimates the causal effects of six corrective actions for children's problem behaviors, comparing four types of longitudinal analyses that correct for pre-existing differences in a cohort of 1,464 4- and 5-year-olds from Canadian National Longitudinal Survey of Children and Youth (NLSCY) data. Analyses of residualized gain scores found…

The Etiology of Variation in Language Skills Changes with Development: A Longitudinal Twin Study of Language from 2 to 12 Years

ERIC Educational Resources Information Center

Hayiou-Thomas, Marianna E.; Dale, Philip S.; Plomin, Robert

2012-01-01

The present study is the first long-term longitudinal examination of the etiology of individual differences in language from early childhood through to adolescence. We applied a multivariate latent factor genetic model to longitudinal data from the Twins Early Development Study in order to (a) compare the magnitude of genetic and environmental…

Stigma, sex work, and substance use: a comparative analysis.

PubMed

Benoit, Cecilia; McCarthy, Bill; Jansson, Mikael

2015-03-01

Stigma is a widely used concept in social science research and an extensive literature claims that stigmatisation contributes to numerous negative health outcomes. However, few studies compare groups that vary in the extent to which they are stigmatised and even fewer studies examine stigma's independent and mediating effects. This article addresses these gaps in a comparative study of perceived stigma and drug use among three low-income feminised service occupations: sex work, food and alcoholic beverage serving, and barbering and hairstyling. An analysis of longitudinal data shows positive associations between sex work, perceived stigma, and socially less acceptable drug use (for example, heroin and cocaine), and that stigma mediates part of the link between sex work and the use of these drugs. Our overall findings suggest that perceived stigma is pronounced among those who work in the sex industry and negatively affects health independently of sex work involvement. © 2015 Foundation for the Sociology of Health & Illness.

Reassessing the educational environment among undergraduate students in a chiropractic training institution: A study over time.

PubMed

Palmgren, Per J; Sundberg, Tobias; Laksov, Klara Bolander

2015-10-01

The aim of the study was twofold: (1) to compare the perceived educational environment at 2 points in time and (2) to longitudinally examine potential changes in perceptions of the educational environment over time. The validated Dundee Ready Educational Environment Measure (DREEM), a 50-item, self-administered Likert-type inventory, was used in this prospective study. Employing convenience sampling, undergraduate chiropractic students were investigated at 2 points in time: 2009 (n = 124) and 2012 (n = 127). An analysis of 2 matching samples was performed on 27% (n = 34) of the respondents in 2009. A total of 251 students (79%) completed the inventory, 83% (n = 124) in 2009 and 75% (n = 127) in 2012. The overall DREEM scores in both years were excellent: 156 (78%) and 153 (77%), respectively. The students' perceptions of teachers differed significantly between the 2 cohort years, decreasing from 77% to 73%. Three items received deprived scores: limited support for stressed students, authoritarian teachers, and an overemphasis on factual learning; the latter significantly decreased in 2012. In the longitudinal sample these items also displayed scores below the expected mean. Students viewed the educational environment as excellent both in 2009 and 2012. The perceptions of teachers declined with time; however, this could be attributed to teachers' new roles. Certain aspects of the educational environment factored prominently during the comparative points in time, as well as longitudinally, and these ought to be further investigated and addressed to provide an enhanced educational environment.

The association between childhood sexual and physical abuse with incident adult severe obesity across 13 years of the National Longitudinal Study of Adolescent Health

PubMed Central

Richardson, Andrea S.; Dietz, William H.; Gordon-Larsen, Penny

2013-01-01

Background Severe obesity has increased yet childhood antecedents of adult severe obesity are not well understood. Objective Estimate adult-onset severe obesity risk in individuals with history of childhood physical and/or sexual abuse compared to those who did not report abuse. Methods Longitudinal analysis of participants from the U.S. National Longitudinal Study of Adolescent Health (N=10,774) Wave II (1996; aged 12–22 years) followed through Wave IV (2008–09; aged 24–34 years). New cases of adult-onset severe obesity (BMI≥40 kg/m2 using measured height and weight) in individuals followed over 13 years who were not severely obese during adolescence (BMI <120% of 95th percentile CDC/NCHS growth curves). Results The combined occurrence of self-reported sexual and physical abuse during childhood was associated with an increased risk of incident severe obesity in adulthood in non-minority females (Hazard Ratio=2.5; 1.3, 4.8) and males (Hazard Ratio=3.6; 1.5, 8.5) compared to individuals with no history of abuse. Conclusion In addition to other social and emotional risks, exposure to sexual and physical abuse during childhood may increase risk of severe obesity later in life. Consideration of the confluence of childhood abuse might be considered as part of preventive and therapeutic approaches to address severe obesity. PMID:24115589

Inducible displacement of cemented tibial components ten years after total knee arthroplasty.

PubMed

Lam Tin Cheung, K; Lanting, B A; McCalden, R W; Yuan, X; MacDonald, S J; Naudie, D D; Teeter, M G

2018-02-01

The aim of this study was to evaluate the long-term inducible displacement of cemented tibial components ten years after total knee arthroplasty (TKA). A total of 15 patients from a previously reported prospective trial of fixation using radiostereometric analysis (RSA) were examined at a mean of 11 years (10 to 11) postoperatively. Longitudinal supine RSA examinations were acquired at one week, one year, and two years postoperatively and at final follow-up. Weight-bearing RSA examinations were also undertaken with the operated lower limb in neutral and in maximum internal rotation positions. Maximum total point motion (MTPM) was calculated for the longitudinal and inducible displacement examinations (supine versus standing, standing versus internal rotation, and supine versus standing with internal rotation). All patients showed some inducible displacement. Two patients with radiolucent lines had greater mean standing-supine MTPM displacement (1.35; sd 0.38) compared with the remaining patients (0.68; sd 0.36). These two patients also had a greater mean longitudinal MTPM at ten years (0.64; sd 0.50) compared with the remaining patients (0.39; sd 0.13 mm). Small inducible displacements in well-fixed cemented tibial components were seen ten years postoperatively, of a similar magnitude to that which has been reported for well-fixed components one to two years postoperatively. Greater displacements were found in components with radiolucent lines. Cite this article: Bone Joint J 2018;100-B:170-5. ©2018 The British Editorial Society of Bone & Joint Surgery.

Longitudinal associations between parenting style and adolescent disordered eating behaviors.

PubMed

Zubatsky, Max; Berge, Jerica; Neumark-Sztainer, Dianne

2015-06-01

The main purpose of this study was to identify the longitudinal association between specific parenting styles (authoritarian, authoritative, permissive, and neglectful) and adolescent disordered eating behaviors. The current study uses longitudinal data from a 5-year study to examine the associations between parenting style and disordered eating behaviors among adolescents. Data from adolescents (n = 2516) participating in Project EAT (Eating Among Teens), a population-based study from 31 Minnesota schools, were used in the analysis. Time 1 data were collected using in-class assessments of adolescents from Minneapolis/St. Paul schools, and Time 2 data were collected using mailed surveys 5 years later. General Linear Models were used to predict adolescent-reported disordered eating behaviors at Time 2 from adolescent-reported parenting style at Time 1. Adolescent boys and girls who had authoritarian mothers at Time 1 had a higher probability of extreme weight control behaviors 5 years later compared to adolescents with authoritative, permissive, or neglectful mothers. Adolescent girls with authoritarian mothers at Time 1 had a higher probability of engaging in binge-eating behaviors at Time 2 compared to adolescent girls with authoritative or permissive mothers. There were no significant associations between paternal parenting style and adolescent disordered eating behaviors. Although authoritarian parenting style served as a possible risk factor for disordered eating behaviors in adolescents, the findings were not conclusive. Future studies should investigate further the association between parenting style and weight control behaviors in adolescents.

Time-Course Gene Set Analysis for Longitudinal Gene Expression Data

PubMed Central

Hejblum, Boris P.; Skinner, Jason; Thiébaut, Rodolphe

2015-01-01

Gene set analysis methods, which consider predefined groups of genes in the analysis of genomic data, have been successfully applied for analyzing gene expression data in cross-sectional studies. The time-course gene set analysis (TcGSA) introduced here is an extension of gene set analysis to longitudinal data. The proposed method relies on random effects modeling with maximum likelihood estimates. It allows to use all available repeated measurements while dealing with unbalanced data due to missing at random (MAR) measurements. TcGSA is a hypothesis driven method that identifies a priori defined gene sets with significant expression variations over time, taking into account the potential heterogeneity of expression within gene sets. When biological conditions are compared, the method indicates if the time patterns of gene sets significantly differ according to these conditions. The interest of the method is illustrated by its application to two real life datasets: an HIV therapeutic vaccine trial (DALIA-1 trial), and data from a recent study on influenza and pneumococcal vaccines. In the DALIA-1 trial TcGSA revealed a significant change in gene expression over time within 69 gene sets during vaccination, while a standard univariate individual gene analysis corrected for multiple testing as well as a standard a Gene Set Enrichment Analysis (GSEA) for time series both failed to detect any significant pattern change over time. When applied to the second illustrative data set, TcGSA allowed the identification of 4 gene sets finally found to be linked with the influenza vaccine too although they were found to be associated to the pneumococcal vaccine only in previous analyses. In our simulation study TcGSA exhibits good statistical properties, and an increased power compared to other approaches for analyzing time-course expression patterns of gene sets. The method is made available for the community through an R package. PMID:26111374

Timoshenko-Type Theory in the Stability Analysis of Corrugated Cylindrical Shells

NASA Astrophysics Data System (ADS)

Semenyuk, N. P.; Neskhodovskaya, N. A.

2002-06-01

A technique is proposed for stability analysis of longitudinally corrugated shells under axial compression. The technique employs the equations of the Timoshenko-type nonlinear theory of shells. The geometrical parameters of shells are specified on discrete set of points and are approximated by segments of Fourier series. Infinite systems of homogeneous algebraic equations are derived from a variational equation written in displacements to determine the critical loads and buckling modes. Specific types of corrugated isotropic metal and fiberglass shells are considered. The calculated results are compared with those obtained within the framework of the classical theory of shells. It is shown that the Timoshenko-type theory extends significantly the possibility of exact allowance for the geometrical parameters and material properties of corrugated shells compared with Kirchhoff-Love theory.

Sexual Behavior and Contraceptive Use among 18- to 19-Year-Old Adolescent Women by Weight Status: A Longitudinal Analysis.

PubMed

Chang, Tammy; Davis, Matthew M; Kusunoki, Yasamin; Ela, Elizabeth J; Hall, Kelli S; Barber, Jennifer S

2015-09-01

To describe the association between weight status and sexual practices among 18- to 19-year-old women. We analyzed a population-based longitudinal study of 18- to 19-year-old women residing in a Michigan county at cohort inception. Weekly journal surveys measured sexual practices, including contraceptive behaviors. Outcomes included proportion of weeks with a partner, proportion of weeks with sexual intercourse, number of partners, average length of relationships, proportion of weeks with contraception use, and proportion of weeks where contraception was used consistently. We examined 26,545 journal surveys from 900 women over the first study year. Ordinary least squares regression models for each outcome examined differences by weight status, controlling for sociodemographic characteristics. The mean proportion of weeks in which adolescents reported sexual intercourse was 52%; there was no difference by weight status. Among weeks in which adolescents reported sexual activity, obese adolescents had a lower proportion of weeks where any contraception was used compared with normal weight adolescents (84% vs 91%, P = .011). Among weeks in which adolescents reported sexual activity and contraceptive use, obese adolescents had a lower proportion of weeks with consistent contraceptive use (68% vs 78%, P = .016) and oral contraceptive pill use (27% vs 45%, P = .001) compared with normal weight adolescents. All other relationships by weight status were not statistically significant. In this longitudinal study, obese adolescent women were less likely to use contraception, and less likely to use it consistently when compared with normal weight peers. Findings suggest obesity may be an important factor associated with adolescent women's sexual behavior. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Dental Homes for Children With Autism: A Longitudinal Analysis of Iowa Medicaid's I-Smile Program.

PubMed

Chi, Donald L; Momany, Elizabeth T; Mancl, Lloyd A; Lindgren, Scott D; Zinner, Samuel H; Steinman, Kyle J

2016-05-01

Medicaid-enrolled children with autism spectrum disorder (ASD) encounter significant barriers to dental care. Iowa's I-Smile Program was implemented in 2006 to improve dental use for all children in Medicaid. This study compared dental home and preventive dental utilization rates for Medicaid-enrolled children by ASD status and within three time periods (pre-implementation, initial implementation, maturation) and determined I-Smile's longitudinal influence on ASD-related dental use disparities. Data from 2002-2011 were analyzed for newly Medicaid-enrolled children aged 3-17 years (N=30,059); identified each child's ASD status; and assessed whether the child had a dental home or utilized preventive dental care. Log-linear regression models were used to generate rate ratios. Analyses were conducted in 2015. In 2003-2011, 9.8% of children with ASD had dental homes compared with 8% of children without ASD; 36.3% of children with ASD utilized preventive care compared to 45.7% of children without ASD. There were no significant differences in dental home rates by ASD status during pre-implementation, initial implementation, or maturation. There were no significant differences in preventive dental utilization by ASD status during pre-implementation or initial implementation, but children with ASD were significantly less likely to utilize preventive care during maturation (rate ratio=0.79, p<0.001). Longitudinal trends in dental home and preventive dental utilization rates were not significant (p=0.54 and p=0.71, respectively). Among newly Medicaid-enrolled children in Iowa's I-Smile Program, those with ASDs were not less likely than those without ASD to have dental homes but were significantly less likely to utilize preventive dental care. Copyright © 2016 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Sexual Behavior and Contraceptive Use Among 18 to 19 year old Adolescent Women By Weight Status: A Longitudinal Analysis

PubMed Central

Chang, Tammy; Davis, Matthew M.; Kusunoki, Yasamin; Ela, Elizabeth J.; Hall, Kelli S.; Barber, Jennifer S.

2015-01-01

Objective To describe the association between weight status and sexual practices among 18-19 year-old women. Study design We analyzed a population-based longitudinal study of 18-19 year-old women residing in a Michigan county at cohort inception. Weekly journal surveys measured sexual practices, including contraceptive behaviors. Outcomes included proportion of weeks with a partner, proportion of weeks with sexual intercourse, number of partners, average length of relationships, proportion of weeks with contraception use, and proportion of weeks where contraception was used consistently. We examined 26,545 journal surveys from 900 women over the first study year. Ordinary least squares regression models for each outcome examined differences by weight status, controlling for sociodemographic characteristics. Results The mean proportion of weeks in which adolescents reported sexual intercourse was 52%; there was no difference by weight status. Among weeks in which adolescents reported sexual activity, obese adolescents had a lower proportion of weeks where any contraception was used compared with normal-weight adolescents (84% vs 91%, p=0.011). Among weeks in which adolescents reported sexual activity and contraceptive use, obese adolescents had a lower proportion of weeks with consistent contraceptive use (68% vs 78%, p=0.016) and oral contraceptive pill use (27% vs 45%, p=0.001) compared with normal-weight adolescents. All other relationships by weight status were not statistically significant. Conclusions In this longitudinal study, obese adolescent women were less likely to use contraception, and less likely to use it consistently when compared with normal-weight peers. Findings suggest obesity may be an important factor associated with adolescent women’s sexual behavior. PMID:26143383

First stable isotope analysis of Asiatic wild ass tail hair from the Mongolian Gobi.

PubMed

Horacek, Micha; Sturm, Martina Burnik; Kaczensky, Petra

Stable isotope analysis has become a powerful tool to study feeding ecology, water use or movement pattern in contemporary, historic and ancient species. Certain hair and teeth grow continuously, and when sampled longitudinally can provide temporally explicit information on dietary regime and movement pattern. In an initial trial, we analysed a tail sample of an Asiatic wild ass ( Equus hemionus ) from the Mongolian Gobi. We found seasonal variations in H, C and N isotope patterns, likely being the result of temporal variations in available feeds, water supply and possibly physiological status. Thus stable isotope analysis shows promise to study the comparative ecology of the three autochthonous equid species in the Mongolian Gobi.

Analysis of multi lobe journal bearings with surface roughness using finite difference method

NASA Astrophysics Data System (ADS)

PhaniRaja Kumar, K.; Bhaskar, SUdaya; Manzoor Hussain, M.

2018-04-01

Multi lobe journal bearings are used for high operating speeds and high loads in machines. In this paper symmetrical multi lobe journal bearings are analyzed to find out the effect of surface roughnessduring non linear loading. Using the fourth order RungeKutta method, time transient analysis was performed to calculate and plot the journal centre trajectories. Flow factor method is used to evaluate the roughness and the finite difference method (FDM) is used to predict the pressure distribution over the bearing surface. The Transient analysis is done on the multi lobe journal bearings for threedifferent surface roughness orientations. Longitudinal surface roughness is more effective when compared with isotopic and traverse surface roughness.

DVH- and NTCP-based dosimetric comparison of different longitudinal margins for VMAT-IMRT of esophageal cancer.

PubMed

Münch, S; Oechsner, M; Combs, S E; Habermehl, D

2017-08-15

To cover the microscopic tumor spread in squamous cell carcinoma of the esophagus (SCC), longitudinal margins of 3-4 cm are used for radiotherapy (RT) protocols. However, smaller margins of 2-3 cm might be reasonable when advanced diagnostic imaging is integrated into target volume delineation. Purpose of this study was to compare the dose distribution and deposition to the organs at risk (OAR) for different longitudinal margins using a DVH- and NTCP-based approach. Ten patients with SCC of the middle or lower third were retrospectively selected. Three planning target volumes (PTV) with longitudinal margins of 4 cm, 3 cm and 2 cm and an axial margin of 1.5 cm to the gross target volume (GTV) were defined for each patient. For each PTV two treatment plans with total doses of 41.4 Gy (neoadjuvant treatment) and 50.4 Gy (definite treatment) were calculated. Dose to the lungs, heart, myelon and liver were then evaluated and compared between different PTVs. When using a longitudinal margin of 3 cm instead of 4 cm, all dose parameters (Dmin, Dmean, Dmedian and V5-V35), except Dmax could be significantly reduced for the lungs. Regarding the heart, a significant reduction was seen for Dmean and V5, but not for Dmin, Dmax, Dmedian and V10-V35. When comparing a longitudinal margin of 4 cm to a longitudinal margin of 2 cm, a significant difference was calculated for Dmin, Dmean, Dmedian and V5-V35 of the lungs and for Dmax, Dmean and V5-V35 of the heart. Nevertheless, no difference was seen for median heart dose. An additional dose reduction for V10 of the heart was achieved for definite treatment plans when using a longitudinal margin of 3 cm. The NTCP-based risk of pneumonitis was significantly reduced by a margin reduction to 2 cm for neoadjuvant and definite treatment plans. Reduction of longitudinal margins from 4 cm to 3 cm can significantly reduce the dose to lungs and Dmean of the heart. Despite clinical benefit and oncologic outcome remain unclear, reduction of the longitudinal margins might provide the opportunity to reduce side effects of chemoradiation (CRT) for SCC in upcoming studies.

The Mutual Relationship Between Men's Drinking and Depression: A 4-Year Longitudinal Analysis.

PubMed

Lee, Soo Bi; Chung, Sulki; Lee, HaeKook; Seo, Jeong Seok

2018-03-17

The purpose of the current study was to examine the longitudinal reciprocal relationship between depression and drinking among male adults from the general population. This study used a panel dataset from the Korean Welfare Panel (from 2011 to 2014). The subjects were 2511 male adults aged between 20 and 65 years. Based on the Korean Version of the Alcohol Use Disorders Identification Test (AUDIT-K) scores, 2191 subjects were categorized as the control group (AUDIT-K < 12) and 320 subjects were categorized as the problem drinking group (AUDIT-K ≥ 12). An autoregressive cross-lagged modelling analysis was performed to investigate the mutual relationship between problem drinking and depression measured consecutively over time. The results indicated that alcohol drinking and depression were stable over time. In the control group, there was no significant causal relationship between problem drinking and depression while in the problem drinking group, drinking in the previous year significantly influenced depression in the following second, third and fourth years. This study compared normal versus problem drinkers and showed a 4-year mutual causal relationship between depression and drinking. No longitudinal interaction between drinking and depression occurred in normal drinkers, while drinking intensified depression over time in problem drinkers. This study found that problem drinking was a risk factor for development of depression. Therefore, more attention should be given to problem alcohol use in the general population and evaluation of past alcohol use history in patients with depressive disorders.

Fourier crosstalk analysis of multislice and cone-beam helical CT

NASA Astrophysics Data System (ADS)

La Riviere, Patrick J.

2004-05-01

Multi-slice helical CT scanners allow for much faster scanning and better x-ray utilization than do their single-slice predecessors, but they engender considerably more complicated data sampling patterns due to the interlacing of the samples from different rows as the patient is translated. Characterizing and optimizing this sampling is challenging because the conebeam geometry of such scanners means that the projections measured by each detector row are at least slightly oblique, making it difficult to apply standard multidimensional sampling analyses. In this study, we seek to apply a more general framework for analyzing sampled imaging systems known as Fourier crosstalk analysis. Our purpose in this preliminary work is to compare the information content of the data acquired in three different scanner geometries and operating conditions with ostensibly equivalent volume coverage and average longitudinal sampling interval: a single-slice scanner operating at pitch 1, a four-slice scanner operating at pitch 3 and a 15-slice scanner operating at pitch 15. We find that moving from a single-slice to a multi-slice geometry introduces longitudinal crosstalk characteristic of the longitudinal sampling interval between periods of individual each detector row, and not of the overall interlaced sampling pattern. This is attributed to data inconsistencies caused by the obliqueness of the projections in a multi-slice/conebeam configuration. However, these preliminary results suggest that the significance of this additional crosstalk actually decreases as the number of detector rows increases.

A community-based cross-sectional and longitudinal study uncovered asymptomatic proteinuria in Japanese adults with low body weight.

PubMed

Muneyuki, Toshitaka; Sugawara, Hitoshi; Suwa, Kaname; Oshida, Haruki; Saito, Masafumi; Hori, Yumiko; Seta, Setsuko; Ishida, Takeshi; Kakei, Masafumi; Momomura, Shin-ichi; Nakajima, Kei

2013-12-01

Although proteinuria is highly prevalent in obese individuals, the association between proteinuria and low body weight is equivocal. In this study we determine whether low body weight is more strongly associated with proteinuria compared with normal weight. The association between body mass index (BMI) and proteinuria was examined in a cross-sectional study of 62,582 asymptomatic individuals aged 20-70 years without known kidney diseases recruited, based on the results of medical checkups in 1999. We also examined the incidence of recurrent or nonrecurrent proteinuria in an 8-year longitudinal analysis of 12,493 individuals without proteinuria at baseline. The prevalence of proteinuria showed a J-shaped relationship with BMI. Multivariate regression analysis showed that BMI of 27.0 kg/m(2) and above or 18.9 kg/m(2) and less was significantly associated with proteinuria relative to BMI 21.0-22.9 kg/m(2), even after adjusting for relevant cardiometabolic risk factors. In the longitudinal study, similar J-shaped relationships between the incident rates of proteinuria and baseline BMI groups were observed at post-baseline checkups. Baseline BMI 27.0 kg/m(2) and above was associated with significantly greater risk for recurrent and nonrecurrent proteinuria, whereas BMI 18.9 kg/m(2) and less was only associated with nonrecurrent proteinuria. Thus, obesity and low body weight may be associated with different types of proteinuria independent of cardiometabolic risk factors.

Everyday Cognition in Prodromal Huntington Disease

PubMed Central

Williams, Janet K.; Kim, Ji-In; Downing, Nancy; Farias, Sarah; Harrington, Deborah L.; Long, Jeffrey D.; Mills, James A.; Paulsen, Jane S.

2014-01-01

Objective Assessment of daily functions affected by cognitive loss in prodromal Huntington disease (HD) is necessary in practice and clinical trials. We evaluated baseline and longitudinal sensitivity of the Everyday Cognition (ECog) scales in prodromal HD and compared self- and companion-ratings. Method Everyday cognition was self-assessed by 850 participants with prodromal HD and 768 companions. We examined internal structure using confirmatory factor analysis (CFA) on baseline data. For longitudinal analysis, we stratified participants into Low, Medium, and High disease progression groups. We examined ECog scores for group differences and participant-and-companion differences using linear mixed effects regression (LMER). Comparison with the Total Functional Capacity (TFC) scale was made. Results CFA revealed good fit of a 5-factor model having a global factor (total score), and sub factors (subscales) of memory, language, visuospatial perception, and executive function. At study entry, participants and companions in the Medium and High groups reported significantly worsened everyday cognition as well as significant functional decline over time. Losses became more pronounced and participant and companion ratings diverged as individuals progressed. TFC showed significant functional loss over time in the High group but not in the Medium group. Conclusions Disease progression is associated with reduced self- and companion-reported everyday cognition in prodromal HD participants who are less than 13 years to estimated motor onset. Our findings suggest companion ratings are more sensitive than participants’ for detecting longitudinal change in daily cognitive function. ECog appears more sensitive to specific functional changes in the prodrome of HD than the TFC. PMID:25000321

Employment contracts: cross-sectional and longitudinal relations with quality of working life, health and well-being.

PubMed

Kompier, Michiel; Ybema, Jan Fekke; Janssen, Julia; Taris, Toon

2009-01-01

The aim of this study was to enhance (i) insight in the relationship between different types of employment contract and the quality of working life, health and well-being, and (ii) our causal understanding of these relationships by comparing employees whose contract type changes across time. Analyses were based on a two-year prospective cohort study. Cross-sectional analyses were based upon a sample of 2,454 Dutch employees (2004). Longitudinal data were available for 1,865 respondents (2004-2006). We distinguished among 5 contract types, and subgroups of 'Upward' (i.e., towards permanent employment) and 'Downward' (towards temporary employment) movers across time. Data were analysed with analysis of variance and cross table analysis. Cross-sectionally, we found differences between contract types in quality of working life: generally permanent employees had better jobs, whereas temporary agency workers and on call workers had more 'bad work characteristics'. We also found a difference in health behaviour (smoking) and that psychological health was worst among temporary agency workers. In longitudinal analyses we found some evidence that a positive change in employment contract was associated with a better quality of working life and better psychological health, whereas the opposite was true for a negative contract change. The quality of working life, health and well-being are unequally distributed over employment contract groups. Temporary agency workers and on-call workers deserve special attention in terms of job design and human resource management.

Changes in aerobic power of women, ages 20-64 yr

NASA Technical Reports Server (NTRS)

Jackson, A. S.; Wier, L. T.; Ayers, G. W.; Beard, E. F.; Stuteville, J. E.; Blair, S. N.

1996-01-01

This study quantified and compared the cross-sectional and longitudinal influence of age, self-report physical activity (SR-PA), and body composition (%fat) on the decline of maximal aerobic power (VO2peak) of women. The cross-sectional sample consisted of 409 healthy women, ages 20-64 yr. The 43 women of the longitudinal sample were from the same population and examined twice, the mean time between tests was 3.7 (+/-2.2) yr. Peak oxygen uptake was determined by indirect calorimetry during a maximal treadmill test. The zero-order correlation of -0.742 between VO2peak and %fat was significantly (P < 0.05) higher then the SR-PA (r = 0.626) and age correlations (r = -0.633). Linear regression defined the cross-sectional age-related decline in VO2peak at 0.537 ml.kg-1.min-1.yr-1. Multiple regression analysis (R = 0.851) showed that adding %fat and SR-PA and their interaction to the regression model reduced the age regression weight of -0.537, to -0.265 ml.kg-1.min-1.yr-1. Statistically controlling for time differences between tests, general linear models analysis showed that longitudinal changes in aerobic power were due to independent changes in %fat and SR-PA, confirming the cross-sectional results. These findings are consistent with men's data from the same lab showing that about 50% of the cross-sectional age-related decline in VO2peak was due to %fat and SR-PA.

Role of multiple cusps in tooth fracture.

PubMed

Barani, Amir; Bush, Mark B; Lawn, Brian R

2014-07-01

The role of multiple cusps in the biomechanics of human molar tooth fracture is analysed. A model with four cusps at the bite surface replaces the single dome structure used in previous simulations. Extended finite element modelling, with provision to embed longitudinal cracks into the enamel walls, enables full analysis of crack propagation from initial extension to final failure. The cracks propagate longitudinally around the enamel side walls from starter cracks placed either at the top surface (radial cracks) or from the tooth base (margin cracks). A feature of the crack evolution is its stability, meaning that extension occurs steadily with increasing applied force. Predictions from the model are validated by comparison with experimental data from earlier publications, in which crack development was followed in situ during occlusal loading of extracted human molars. The results show substantial increase in critical forces to produce longitudinal fractures with number of cuspal contacts, indicating a capacity for an individual tooth to spread the load during mastication. It is argued that explicit critical force equations derived in previous studies remain valid, at the least as a means for comparing the capacity for teeth of different dimensions to sustain high bite forces. Copyright © 2014 Elsevier Ltd. All rights reserved.

Longitudinal changes in ventral and dorsal neck muscle layers during loading against gravity in healthy volunteers using speckle tracking.

PubMed

Peolsson, Anneli; Peolsson, Michael

2014-05-01

This study aimed to describe and compare the longitudinal mechanical activity, deformation, and deformation rate of the different layers of dorsal and ventral neck muscles in healthy volunteers during head lifts against gravity. The cross-sectional study included 19 healthy volunteers (mean age, 28 years; SD, 7 years). Ultrasound with speckle-tracking analysis was used to investigate longitudinal mechanical activation, deformation, and deformation rate of dorsal and ventral neck muscles in real time during a head lift. Significance levels were set as P = .025 or P = .0125, depending on the number of comparisons. The dorsal neck muscles did not significantly differ in deformation (P > .04); however, the multifidus had a higher deformation rate than all other dorsal muscles (P < .003). The sternocleidomastoid had significantly higher deformation than the longus capitis (P = .005) and colli (P = .001) but a lower deformation rate than the longus colli (P = .02). The sternocleidomastoid deformed more than the deeper muscles, but it did significantly slower than the longus colli. Among the dorsal muscles, the deepest (the multifidus) had the highest deformation rate. Copyright © 2014 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

A longitudinal analysis of shooter games and their relationship with conduct disorder and cself-reported delinquency.

PubMed

Smith, Sven; Ferguson, Chris; Beaver, Kevin

Despite several decades of research, little scholarly consensus has emerged regarding the role of violent video games in the development of youth psychopathology or crime. The current study employed the Avon Longitudinal Study of Parents and Children longitudinal dataset to examine the impact of the shooter game genre ownership in childhood on later adolescent conduct disorder and criminal behavior. Multivariate Poisson regressions with the robust estimator correlation matrix were performed comparing effects of independent and confounding variables. Results revealed that early childhood mental health symptoms at age seven related to ADHD, depression and early conduct disorder predicted criminal behavior at age fifteen. Male gender also predicted criminal behavior at age fifteen. However, exposure to shooter games did not predict adolescent conduct disorder or criminal behavior. We have found support that suggests that the role of violent video games in the development of youth psychopathology or crime is very little if any. Lack of a relationship between exposure to shooter games and later conduct and criminal behavior problems may be understood within the context of the Catalyst Model. Copyright © 2018 Elsevier Ltd. All rights reserved.

Joint models for longitudinal and time-to-event data: a review of reporting quality with a view to meta-analysis.

PubMed

Sudell, Maria; Kolamunnage-Dona, Ruwanthi; Tudur-Smith, Catrin

2016-12-05

Joint models for longitudinal and time-to-event data are commonly used to simultaneously analyse correlated data in single study cases. Synthesis of evidence from multiple studies using meta-analysis is a natural next step but its feasibility depends heavily on the standard of reporting of joint models in the medical literature. During this review we aim to assess the current standard of reporting of joint models applied in the literature, and to determine whether current reporting standards would allow or hinder future aggregate data meta-analyses of model results. We undertook a literature review of non-methodological studies that involved joint modelling of longitudinal and time-to-event medical data. Study characteristics were extracted and an assessment of whether separate meta-analyses for longitudinal, time-to-event and association parameters were possible was made. The 65 studies identified used a wide range of joint modelling methods in a selection of software. Identified studies concerned a variety of disease areas. The majority of studies reported adequate information to conduct a meta-analysis (67.7% for longitudinal parameter aggregate data meta-analysis, 69.2% for time-to-event parameter aggregate data meta-analysis, 76.9% for association parameter aggregate data meta-analysis). In some cases model structure was difficult to ascertain from the published reports. Whilst extraction of sufficient information to permit meta-analyses was possible in a majority of cases, the standard of reporting of joint models should be maintained and improved. Recommendations for future practice include clear statement of model structure, of values of estimated parameters, of software used and of statistical methods applied.

Intraoperative performance and postoperative outcome comparison of longitudinal, torsional, and transversal phacoemulsification machines.

PubMed

Christakis, Panos G; Braga-Mele, Rosa M

2012-02-01

To compare the intraoperative performance and postoperative outcomes of 3 phacoemulsification machines that use different modes. Kensington Eye Institute, Toronto, Ontario, Canada. Comparative case series. This chart and video review comprised consecutive eligible patients who had phacoemulsification by the same surgeon using a Whitestar Signature Ellips-FX (transversal), Infiniti-Ozil-IP (torsional), or Stellaris (longitudinal) machine. The review included 98 patients. Baseline characteristics in the groups were similar; the mean nuclear sclerosis grade was 2.0 ± 0.8. There were no significant intraoperative complications. The torsional machine averaged less phacoemulsification needle time (83 ± 33 seconds) than the transversal (99 ± 40 seconds; P=.21) or longitudinal (110 ± 45 seconds; P=.02) machines; the difference was accentuated in cases with high-grade nuclear sclerosis. The torsional machine had less chatter and better followability than the transversal or longitudinal machines (P<.001). The torsional and longitudinal machines had better anterior chamber stability than the transversal machine (P<.001). Postoperatively, the torsional machine yielded less central corneal edema than the transversal (P<.001) and longitudinal (P=.04) machines, corresponding to a smaller increase in mean corneal thickness (torsional 5%, transversal 10%, longitudinal 12%; P=.04). Also, the torsional machine had better 1-day postoperative visual acuities (P<.001). All 3 phacoemulsification machines were effective with no significant intraoperative complications. The torsional machine outperformed the transversal and longitudinal machines, with a lower mean needle time, less chatter, and improved followability. This corresponded to less corneal edema 1 day postoperatively and better visual acuity. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Budget Impact Analysis to Estimate the Cost Dynamics of Treating Refractory Gastroesophageal Reflux Disease With Radiofrequency Energy: a Payer Perspective.

PubMed

Gregory, David; Scotti, Dennis J; Buck, Daniel; Triadafilopoulos, George

2016-05-01

A minimally invasive endoscopic treatment that utilizes radio-frequency energy (RFE) has received increased attention as an appropriate middle-ground approach in the treatment of refractory gastroesophageal reflux disease (GERD) and as an alternative to complicated and invasive surgical procedures. The objective of this study was to develop a longitudinal budget impact analysis from the payer perspective to estimate the direct medical costs of treatment for the refractory GERD patient population and to estimate the budgetary impact of further extending the RFE treatment option to other target populations. A retrospective analysis of claims designed to assess the longitudinal costs and budget impact on payer expenditures associated with managing and treating GERD surgically (Nissen fundoplication [NF]), endoscopically (RFE), or medically was performed. Both Medicare and commercially insured claims databases were interrogated for such population-level analyses. At current adoption rates (less than 1% of procedures), RFE demonstrated overall cost savings ranging from 7.3% to 50.5% in the 12-month time period following the index procedure (inclusive of procedure costs) when compared to medical management and fundoplication across the commercial and Medicare patient populations. Increasing the total number of RFE procedures to 2% of total cases performed generated per-member, per-month (PMPM) savings of $0.28 in the Medicare population and $0.37 in the commercially insured population. Further increases yielded higher PMPM savings. Adding to the clinical importance of RFE in filling the gap between medical and surgical management, this economic analysis demonstrates to payers that the adoption of RFE can create notable savings to their plans when compared to surgery or medical management.

Time to health-related quality of life score deterioration as a modality of longitudinal analysis for health-related quality of life studies in oncology: do we need RECIST for quality of life to achieve standardization?

PubMed

Anota, Amélie; Hamidou, Zeinab; Paget-Bailly, Sophie; Chibaudel, Benoist; Bascoul-Mollevi, Caroline; Auquier, Pascal; Westeel, Virginie; Fiteni, Frederic; Borg, Christophe; Bonnetain, Franck

2015-01-01

Longitudinal analysis of health-related quality of life (HRQoL) remains unstandardized and compromises comparison of results between trials. In oncology, despite available statistical approaches, results are poorly used to change standards of care, mainly due to lack of standardization and the ability to propose clinical meaningful results. In this context, the time to deterioration (TTD) has been proposed as a modality of longitudinal HRQoL analysis for cancer patients. As for tumor response and progression, we propose to develop RECIST criteria for HRQoL. Several definitions of TTD are investigated in this paper. We applied this approach in early breast cancer and metastatic pancreatic cancer with a 5-point minimal clinically important difference. In breast cancer, TTD was defined as compared to the baseline score or to the best previous score. In pancreatic cancer (arm 1: gemcitabine with FOLFIRI.3, arm 2: gemcitabine alone), the time until definitive deterioration (TUDD) was investigated with or without death as event. In the breast cancer study, 381 women were included. The median TTD was influenced by the choice of the reference score. In pancreatic cancer study, 98 patients were enrolled. Patients in Arm 1 presented longer TUDD than those in Arm 2 for most of HRQoL scores. Results of TUDD were slightly different according to the definition of deterioration applied. Currently, the international ARCAD group supports the idea of developing RECIST for HRQoL in pancreatic and colorectal cancer with liver metastasis, with a view to using HRQoL as a co-primary endpoint along with a tumor parameter.

Promising Long-Term Health-Related Quality of Life After High-Dose-Rate Brachytherapy Boost for Localized Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wahlgren, Thomas; Nilsson, Sten; Lennernaes, Bo

2007-11-01

Purpose: To explore the long-term general and disease-specific health-related quality of life (HRQOL) >5 years after combined radiotherapy for localized prostate cancer, including a high-dose-rate brachytherapy boost and hormonal deprivation therapy. Methods and Materials: Of 196 eligible patients with localized prostate cancer (Stage T1-T3a) consecutively treated with curative radiotherapy at our institution between June 1998 and August 2000, 182 (93%) completed the European Organization for Research and Treatment of Cancer Quality of Life questionnaires QLQ-C30 and QLQ-PR25, including specific questions on fecal incontinence >5 years after treatment in September 2005. A comparison with age-matched normative data was done, as wellmore » as a longitudinal analysis using HRQOL data from a previous study. Results: The analysis included 158 nonrecurrent patients. Comparisons made with normative data showed that physical and role functioning were significantly better statistically and social functioning was significantly worse. Diarrhea and sleep disturbances were more pronounced and pain less pronounced than in a normal male population. The longitudinal analysis of disease-specific HRQOL showed that urinary urgency and erectile problems persisted 5 years after treatment, and nocturia and hormonally dependent symptoms had declined significantly, with a statistically significant difference. Fecal incontinence was recognized by 25% of patients, of whom 80% considered it a minor problem. Conclusion: More than 5 years after combined radiotherapy, irritative urinary problems and erectile dysfunction remain concerns, although severe bowel disturbance and fecal incontinence seem to be minor problems. Longitudinally, a decline mainly in hormonally dependent symptoms was seen. Minor differences in general HRQOL compared with normative data were observed, possibly including 'response shift' effects.« less

Evaluation of visual impairment in Usher syndrome 1b and Usher syndrome 2a.

PubMed

Pennings, Ronald J E; Huygen, Patrick L M; Orten, Dana J; Wagenaar, Mariette; van Aarem, Annelies; Kremer, Hannie; Kimberling, William J; Cremers, Cor W R J; Deutman, August F

2004-04-01

To evaluate visual impairment in Usher syndrome 1b (USH1b) and Usher syndrome 2a (USH2a). We carried out a retrospective study of 19 USH1b patients and 40 USH2a patients. Cross-sectional regression analyses of the functional acuity score (FAS), functional field score (FFS) and functional vision score (FVS) related to age were performed. Statistical tests relating to regression lines and Student's t-test were used to compare between (sub)groups of patients. Parts of the available individual longitudinal data were used to obtain individual estimates of progressive deterioration and compare these to those obtained with cross-sectional analysis. Results were compared between subgroups of USH2a patients pertaining to combinations of different types of mutations. Cross-sectional analyses revealed significant deterioration of the FAS (0.7% per year), FFS (1.0% per year) and FVS (1.5% per year) with advancing age in both patient groups, without a significant difference between the USH1b and USH2a patients. Individual estimates of the deterioration rates were substantially and significantly higher than the cross-sectional estimates in some USH2a cases, including values of about 5% per year (or even higher) for the FAS (age 35-50 years), 3-4% per year for the FFS and 4-5% per year for the FVS (age > 20 years). There was no difference in functional vision score behaviour detected between subgroups of patients pertaining to different biallelic combinations of specific types of mutations. The FAS, FFS and FVS deteriorated significantly by 0.7-1.5% per year according to cross-sectional linear regression analysis in both USH1b and USH2a patients. Higher deterioration rates (3-5% per year) in any of these scores were attained, according to longitudinal data collected from individual USH2a patients. Score behaviour was similar across the patient groups and across different biallelic combinations of various types of mutations. However, more elaborate studies, preferably covering longitudinal data, are needed to obtain conclusive evidence.

Modelling, simulation and applications of longitudinal train dynamics

NASA Astrophysics Data System (ADS)

Cole, Colin; Spiryagin, Maksym; Wu, Qing; Sun, Yan Quan

2017-10-01

Significant developments in longitudinal train simulation and an overview of the approaches to train models and modelling vehicle force inputs are firstly presented. The most important modelling task, that of the wagon connection, consisting of energy absorption devices such as draft gears and buffers, draw gear stiffness, coupler slack and structural stiffness is then presented. Detailed attention is given to the modelling approaches for friction wedge damped and polymer draft gears. A significant issue in longitudinal train dynamics is the modelling and calculation of the input forces - the co-dimensional problem. The need to push traction performances higher has led to research and improvement in the accuracy of traction modelling which is discussed. A co-simulation method that combines longitudinal train simulation, locomotive traction control and locomotive vehicle dynamics is presented. The modelling of other forces, braking propulsion resistance, curve drag and grade forces are also discussed. As extensions to conventional longitudinal train dynamics, lateral forces and coupler impacts are examined in regards to interaction with wagon lateral and vertical dynamics. Various applications of longitudinal train dynamics are then presented. As an alternative to the tradition single wagon mass approach to longitudinal train dynamics, an example incorporating fully detailed wagon dynamics is presented for a crash analysis problem. Further applications of starting traction, air braking, distributed power, energy analysis and tippler operation are also presented.

Consequences of bullying in schools.

PubMed

Rigby, Ken

2003-10-01

For the most part, studies of the consequences of bullying in schools have concentrated upon health outcomes for children persistently bullied by their peers. Conclusions have been influenced by how bullying has been conceptualized and assessed, the specific health outcomes investigated, and the research method and data analysis employed. Results from cross-sectional surveys suggest that being victimized by peers is significantly related to comparatively low levels of psychological well-being and social adjustment and to high levels of psychological distress and adverse physical health symptoms. Retrospective reports and studies suggest that peer victimization may contribute to later difficulties with health and well-being. Longitudinal studies provide stronger support for the view that peer victimization is a significant causal factor in schoolchildren's lowered health and well-being and that the effects can be long-lasting. Further evidence from longitudinal studies indicates that the tendency to bully others at school significantly predicts subsequent antisocial and violent behaviour.

A Longitudinal Mode Electromagnetic Acoustic Transducer (EMAT) Based on a Permanent Magnet Chain for Pipe Inspection.

PubMed

Cong, Ming; Wu, Xinjun; Qian, Chunqiao

2016-05-21

A new electromagnetic acoustic transducer (EMAT) design, employing a special structure of the permanent magnet chain, is proposed to generate and receive longitudinal guided waves for pipe inspection based on the magnetostriction mechanism. Firstly, a quantitative analysis of the excitation forces shows the influence of the radial component can be ignored. Furthermore, as the axial component of the static magnetic field is dominant, a method of solenoid testing coils connected in series is adopted to increase the signal amplitude. Then, two EMAT configurations are developed to generate and receive the L(0,2) guided wave mode. The experimental results show the circumferential notch can be identified and located successfully. Finally, a detailed investigation of the performance of the proposed EMATs is given. Compared to the conventional EMAT configuration, the proposed configurations have the advantages of small volume, light weight, easy installation and portability, which is helpful to improve inspection efficiency.

Predictors of depression among refugees from Vietnam: a longitudinal study of new arrivals.

PubMed

Hinton, W L; Tiet, Q; Tran, C G; Chesney, M

1997-01-01

The present study examined the impact of prearrival traumatic experiences and sociodemographic characteristics on future depression among Vietnamese and Chinese refugees from Vietnam. This is a longitudinal study of newly arrived refugees from Vietnam undergoing a mandatory health screening. A stratified consecutive sample of ethnic Chinese and ethnic Vietnamese refugees was drawn. The depression subscale of the Indochinese Hopkins symptoms checklist was administered to 114 refugees within the first 6 months after arrival in the United States and 12 to 18 months later. Ethnic Vietnamese reported more prearrival trauma compared with ethnic Chinese. Age was strongly correlated with time 2 depression among ethnic Vietnamese but not among ethnic Chinese. Multivariate linear regression analysis revealed that being a veteran, older, unattached, less proficient in English, ethnic Vietnamese, and more depressed at baseline predicted higher depression at follow-up. Although prearrival trauma predicted future depression, other sociodemographic characteristics assumed more importance with time.

Risk factors for common mental disorders in women. Population-based longitudinal study.

PubMed

Patel, Vikram; Kirkwood, Betty R; Pednekar, Sulochana; Weiss, Helen; Mabey, David

2006-12-01

The determinants of common mental disorders in women have not been described in longitudinal studies from a low-income country. Population-based cohort study of 2494 women aged 18 to 50 years, in India. The Revised Clinical Interview Schedule was used for the detection of common mental disorders. There were 39 incident cases of common mental disorder in 2166 participants eligible for analysis (12-month rate 1.8%, 95% CI 1.3-2.4%). The following baseline factors were independently associated with the risk for common mental disorder: poverty (low income and having difficulty making ends meet); being married as compared with being single; use of tobacco; experiencing abnormal vaginal discharge; reporting a chronic physical illness; and having higher psychological symptom scores at baseline. Programmes to reduce the burden of common mental disorder in women should target poorer women, women with chronic physical illness and who have gynaecological symptoms, and women who use tobacco.

Effects of Computer Support, Collaboration, and Time Lag on Performance Self-Efficacy and Transfer of Training: A Longitudinal Meta-Analysis

ERIC Educational Resources Information Center

Gegenfurtner, Andreas; Veermans, Koen; Vauras, Marja

2013-01-01

This meta-analysis (29 studies, k = 33, N = 4158) examined the longitudinal development of the relationship between performance self-efficacy and transfer before and after training. A specific focus was on training programs that afforded varying degrees of computer-supported collaborative learning (CSCL). Consistent with social cognitive theory,…

The Developmental and Cultural Contexts of Objectified Body Consciousness: A Longitudinal Analysis of Two Cohorts of Women

ERIC Educational Resources Information Center

McKinley, Nita Mary

2006-01-01

Longitudinal analysis of 10-year follow-up data on objectified body consciousness, body esteem, weight-related attitudes and behaviors, and psychological well-being in 74 middle-aged and 72 young women tested hypotheses developed from age-related change and cohort differences models of body experience. Young women's body surveillance and body…

Decreasing Sports Activity with Increasing Age? Findings from a 20-Year Longitudinal and Cohort Sequence Analysis

ERIC Educational Resources Information Center

Breuer, Christoph; Wicker, Pamela

2009-01-01

According to cross-sectional studies in sport science literature, decreasing sports activity with increasing age is generally assumed. In this paper, the validity of this assumption is checked by applying more effective methods of analysis, such as longitudinal and cohort sequence analyses. With the help of 20 years' worth of data records from the…

Evolution of Online Discussion Forum Richness according to Channel Expansion Theory: A Longitudinal Panel Data Analysis

ERIC Educational Resources Information Center

Fernandez, Vicenc; Simo, Pep; Sallan, Jose M.; Enache, Mihaela

2013-01-01

The selection and use of communication media has been the center of attention for a great number of researchers in the area of organizational communication. The channel expansion theory combines elements of the main theories in this area; however, these investigations have a static cross-sectional design rather than a longitudinal analysis. With…

An Analysis of Pedagogical Moves for Facilitating the Development of In-Service Middle-School Mathematics Teachers' Recognition of Reasoning

ERIC Educational Resources Information Center

Cipriani, Phyllis J.

2017-01-01

A constructivist approach for teaching and learning mathematics was the foundation for a longitudinal study at Rutgers University in 1987 (Maher, 2011). One of the objectives of the longitudinal study was to provide an environment where students solve problems in collaborative groups (Maher, 2011). Videos from the longitudinal study are stored in…

A recurrence matrix method for the analysis of longitudinal and torsional vibrations in non-uniform multibranch beams with variable boundary conditions

NASA Technical Reports Server (NTRS)

Davis, R. B.; Stephens, M. V.

1974-01-01

An approximate method for calculating the longitudinal and torsional natural frequencies and associated modal data of a beamlike, variable cross section multibranch structure is presented. The procedure described is the numerical integration of the first order differential equations that characterize the beam element in longitudinal motion and that satisfy the appropriate boundary conditions.

Retention of Children and Their Families in the Longitudinal Outcome Study of the Comprehensive Community Mental Health Services for Children and Their Families Program: A Multilevel Analysis

ERIC Educational Resources Information Center

Gebreselassie, Tesfayi; Stephens, Robert L.; Maples, Connie J.; Johnson, Stacy F.; Tucker, Alyce L.

2014-01-01

Predictors of retention of participants in a longitudinal study and heterogeneity between communities were investigated using a multilevel logistic regression model. Data from the longitudinal outcome study of the national evaluation of the Comprehensive Community Mental Health Services for Children and Their Families program and information on…

Characteristics of At-Risk Students in NELS:88. National Education Longitudinal Study of 1988. Statistical Analysis Report. Contractor Report. NCES 92-042

ERIC Educational Resources Information Center

Kaufman, Phillip; Bradbury, Denise

1992-01-01

The National Education Longitudinal Study of 1988 (NELS:88) is a large-scale, national longitudinal study designed and sponsored by the National Center for Education Statistics (NCES), with support from other government agencies. Beginning in the spring of 1988 with a cohort of eighth graders (25,000) attending public and private schools across…

Analysis of the longitudinal space charge impedance of a round uniform beam inside parallel plates and rectangular chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L.; Li, Y.

2015-02-03

This paper analyzes the longitudinal space charge impedances of a round uniform beam inside a rectangular and parallel plate chambers using the image charge method. This analysis is valid for arbitrary wavelengths, and the calculations converge rapidly. The research shows that only a few of the image beams are needed to obtain a relative error less than 0.1%. The beam offset effect is also discussed in the analysis.

Young Adult Outcomes of Children Growing up with Chronic Illness: An analysis of the National Longitudinal Study of Adolescent Health

PubMed Central

Maslow, Gary R.; Haydon, Abigail; Ford, Carol Ann; Halpern, Carolyn Tucker

2012-01-01

Objective To examine young adult outcomes in a nationally representative US cohort of young adults who grew up with a chronic illness. Design Secondary analysis of nationally representative data from Wave III (2001) of the National Longitudinal Study of Adolescent Health. Setting United States Participants The analytic sample included 13,236 young adults 18–28 years old at Wave III. Main Exposure Self-report of a chronic physical illness (asthma, cancer, diabetes or epilepsy) in adolescence. Respondents with (1) asthma or (2) non-asthma chronic illness (cancer, diabetes, or epilepsy) were compared to subjects without these conditions. Main Outcome Measures Self-report of high school graduation, ever having a job, having a current job, living with parents, and ever receiving public assistance. Results Three percent of young adults had non-asthma chronic illness (cancer, diabetes, or epilepsy) and 16% had asthma. The majority of young adults with chronic illness graduated high school (81%) and were currently employed (60%). However, compared to healthy young adults, those with a non-asthma chronic illness were significantly less likely to graduate high school, ever have a job, or have a current job and were more likely to receive public assistance. When compared to young adults with asthma, young adults with non-asthma chronic illness again had significantly worse young adult outcomes on all measures. Conclusions Most young adults growing up with chronic illness graduate high school and are employed. However, these young adults are significantly less likely than their healthy peers to achieve these important educational and vocational milestones. PMID:21383274

Formation mechanisms of periodic longitudinal microstructure and texture patterns in friction stir welded magnesium AZ80

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiscocks, J., E-mail: j.hiscocks@queensu.ca

Many studies of friction stir welding have shown that periodicity of metal flow around the tool pin may result in the formation of periodic differences in microstructure and texture in the weld nugget area correlated with the weld pitch. The current work investigates the periodicity of magnesium weld microtexture in the nugget region and its association with material flow using optical and electron microscopy. Two welds created in AZ80 at different processing conditions are presented in detail, one illustrating periodic longitudinal texture change, and one showing for the first time that periodic variations in texture, grain size, or composition aremore » not defining features of periodic nugget flow. While nugget texture is dominated by shear deformation, it was found here to be affected to a lesser degree by compaction of material behind the welding tool, which led to reduction in intensity of the shear texture fiber. The decreased tendency for magnesium based alloys to form periodic patterns as compared to aluminum based alloys is explained with reference to the shear textures. - Highlights: •It is shown here that periodic material flow in the nugget does not necessitate longitudinal texture patterns. •Longitudinal texture patterns are shown to be present or absent in Mg AZ80 based on processing conditions. •Texture in the nugget is mainly dictated by shear deformation, but has measurable effects from other deformation modes. •Explanation of why longitudinal texture change is frequently reported in aluminum but not magnesium alloys is provided. •A new vector visualization of material flow based on EBSD data analysis is shown.« less

Low-flow traveltime, longitudinal-dispersion, and reaeration characteristics of the Souris River from Lake Darling Dam to J Clark Salyer National Wildlife Refuge, North Dakota

USGS Publications Warehouse

Wesolowski, E.A.; Nelson, R.A.

1987-01-01

As part of the Sour is River water-quality assessment, traveltime, longitudinal-dispersion, and reaeration measurements were made during September 1983 on segments of the 186-mile reach of the Sour is River from Lake Darling Dam to the J. Clark Salyer National Wildlife Refuge. The primary objective was to determine traveltime, longitudinal-dispersion, and reaeration coefficients during low flow. Streamflow in the reach ranged from 10.5 to 47.0 cubic feet per second during the measurement period.On the basis of channel and hydraulic characteristics, the 186-mile reach was subdivided into five subreaches that ranged from 18 to 55 river miles in length. Within each subreach, representative test reaches that ranged from 5.0 to 9.1 river miles in length were selected for tracer injection and sample collection. Standard fluorometric techniques were used to measure traveltime and longitudinal dispersion, and a modified tracer technique that used ethylene and propane gas was used to measure reaeration. Mean test-reach velocities ranged from 0.05 to 0.30 foot per second, longitudinal-dispersion coefficients ranged from 4.2 to 61 square feet per second, and reaeration coefficients based on propane ranged from 0.39 to 1.66 per day. Predictive reaeration coefficients obtained from 18 equations (8 semiempirical and 10 empirical) were compared with each measured reaeration coefficient by use of an error-of-estimate analysis. The predictive reaeration coefficients ranged from 0.0008 to 3.4 per day. A semiempirical equation that produced coefficients most similar to the measured coefficients had the smallest absolute error of estimate (0.35). The smallest absolute error of estimate for the empirical equations was 0.41.

Mitral annular plane systolic excursion/left ventricular length (MAPSE/L) as a simple index for assessing left ventricular longitudinal function in children.

PubMed

Terada, Tomomasa; Mori, Kazuhiro; Inoue, Miki; Yasunobu, Hayabuchi

2016-11-01

Assessment of longitudinal left ventricular (LV) function is important for early detection of cardiac dysfunction. Although mitral annular plane systolic excursion (MAPSE) obtained by M-mode echocardiography offers a simple method for assessing longitudinal LV function, normal values of MAPSE for children change according to body size. To minimize the effects of body size, MAPSE was divided by LV long-axis length (MAPSE/L). MAPSE/L was measured in 210 healthy children from birth to 15 years of age and classified into five subgroups. MAPSE/L was then compared with 10 parameters in 136 children (age, heart rate, mean blood pressure, ejection fraction of the LV (EF), peak atrial flow velocity/peak early diastolic flow velocity of mitral flow, tissue Doppler velocity during systole (s') and early diastole (e'), E/e' ratio, Tei index, and global longitudinal strain (GLS) of the LV by the speckle tracking method). MAPSE/L was significantly lower in the neonate group than in the remaining four groups. MAPSE/L then increased with age to peak at 1-5 years and gradually decreased thereafter. In all cases beyond the neonatal period, MAPSE/L was more than 0.17. Among various parameters, GLS, age, EF, Tei index and s' were significantly associated with MAPSE/L in that order. In univariate analysis, GLS was most significantly associated with MAPSE/L (r=.56). We have established normal reference values for MPSE/L in healthy children. MAPSE/L is expected to offer a simple parameter to evaluate LV longitudinal systolic function during daily routine echocardiography in children. © 2016, Wiley Periodicals, Inc.

Longitudinal changes in gray matter regions after cranial radiation and comparative analysis with whole body radiation: a DTI study.

PubMed

Watve, Apurva; Gupta, Mamta; Khushu, Subash; Rana, Poonam

2018-06-01

Radiation-induced white matter changes are well known and vastly studied. However, radiation-induced gray matter alterations are still a research question. In the present study, these changes were assessed in a longitudinal manner using Diffusion Tensor Imaging (DTI) and further compared for cranial and whole body radiation exposure. Male mice (C57BL/6) were irradiated with cranial or whole body radiation followed by DTI study at 7T animal MRI system during predose, subacute and early delayed phases of radiation sickness. Fractional anisotropy (FA) and mean diffusivity (MD) values were obtained from brain's gray matter regions. Decreased FA with increased MD was observed prominently in animals exposed to cranial radiation showing most changes at 8 months post irradiation. However, whole body radiation induced FA changes were mostly observed at 1 month post irradiation as compared to controls. The differential response after whole body and cranial irradiation observed in the study depicts that radiation exposure of 5 Gy could induce permanent alterations in gray matter regions prominently as observed in Caudoputamen region at all the time points. Thus, our study has bolstered the role of DTI to probe microstructural changes in gray matter regions of brain after radiation exposure.

Sleeping difficulty, disease and mortality in older women: a latent class analysis and distal survival analysis.

PubMed

Leigh, Lucy; Hudson, Irene L; Byles, Julie E

2015-12-01

The aim of this study is to identify patterns of sleep difficulty in older women, to investigate whether sleep difficulty is an indicator for poorer survival, and to determine whether sleep difficulty modifies the association between disease and death. Data were from the Australian Longitudinal Study on Women's Health, a 15-year longitudinal cohort study, with 10 721 women aged 70-75 years at baseline. Repeated-measures latent class analysis identified four classes of persistent sleep difficulty: troubled sleepers (N = 2429, 22.7%); early wakers (N = 3083, 28.8%); trouble falling asleep (N = 1767, 16.5%); and untroubled sleepers (N = 3442, 32.1%). Sleep difficulty was an indicator for mortality. Compared with untroubled sleepers, hazard ratios and 95% confidence intervals for troubled sleepers, early wakers, and troubled falling asleep were 1.12 (1.03, 1.23), 0.81 (0.75, 0.91) and 0.89 (0.79, 1.00), respectively. Sleep difficulty may modify the prognosis of women with chronic diseases. Hazard ratios (and 95% confidence intervals) for having three or more diseases (compared with 0 diseases) were enhanced for untroubled sleepers, early wakers and trouble falling asleep [hazard ratio = 1.86 (1.55, 2.22), 1.91 (1.56, 2.35) and 1.98 (1.47, 2.66), respectively], and reduced for troubled sleepers [hazard ratio = 1.57 (1.24, 1.98)]. Sleep difficulty in older women is more complex than the presence or absence of sleep difficulty, and should be considered when assessing the risk of death associated with disease. © 2015 European Sleep Research Society.

Comparison of clinical outcomes in decompression and fusion versus decompression only in patients with ossification of the posterior longitudinal ligament: a meta-analysis.

PubMed

Mehdi, Syed K; Alentado, Vincent J; Lee, Bryan S; Mroz, Thomas E; Benzel, Edward C; Steinmetz, Michael P

2016-06-01

OBJECTIVE Ossification of the posterior longitudinal ligament (OPLL) is a pathological calcification or ossification of the PLL, predominantly occurring in the cervical spine. Although surgery is often necessary for patients with symptomatic neurological deterioration, there remains controversy with regard to the optimal surgical treatment. In this systematic review and meta-analysis, the authors identified differences in complications and outcomes after anterior or posterior decompression and fusion versus after decompression alone for the treatment of cervical myelopathy due to OPLL. METHODS A MEDLINE, SCOPUS, and Web of Science search was performed for studies reporting complications and outcomes after decompression and fusion or after decompression alone for patients with OPLL. A meta-analysis was performed to calculate effect summary mean values, 95% CIs, Q statistics, and I(2) values. Forest plots were constructed for each analysis group. RESULTS Of the 2630 retrieved articles, 32 met the inclusion criteria. There was no statistically significant difference in the incidence of excellent and good outcomes and of fair and poor outcomes between the decompression and fusion and the decompression-only cohorts. However, the decompression and fusion cohort had a statistically significantly higher recovery rate (63.2% vs 53.9%; p < 0.0001), a higher final Japanese Orthopaedic Association score (14.0 vs 13.5; p < 0.0001), and a lower incidence of OPLL progression (< 1% vs 6.3%; p < 0.0001) compared with the decompression-only cohort. There was no statistically significant difference in the incidence of complications between the 2 cohorts. CONCLUSIONS This study represents the only comprehensive review of outcomes and complications after decompression and fusion or after decompression alone for OPLL across a heterogeneous group of surgeons and patients. Based on these results, decompression and fusion is a superior surgical technique compared with posterior decompression alone in patients with OPLL. These results indicate that surgical decompression and fusion lead to a faster recovery, improved postoperative neurological functioning, and a lower incidence of OPLL progression compared with posterior decompression only. Furthermore, decompression and fusion did not lead to a greater incidence of complications compared with posterior decompression only.

Vehicle longitudinal velocity estimation during the braking process using unknown input Kalman filter

NASA Astrophysics Data System (ADS)

Moaveni, Bijan; Khosravi Roqaye Abad, Mahdi; Nasiri, Sayyad

2015-10-01

In this paper, vehicle longitudinal velocity during the braking process is estimated by measuring the wheels speed. Here, a new algorithm based on the unknown input Kalman filter is developed to estimate the vehicle longitudinal velocity with a minimum mean square error and without using the value of braking torque in the estimation procedure. The stability and convergence of the filter are analysed and proved. Effectiveness of the method is shown by designing a real experiment and comparing the estimation result with actual longitudinal velocity computing from a three-axis accelerometer output.

Analysis of longitudinal data from animals with missing values using SPSS.

PubMed

Duricki, Denise A; Soleman, Sara; Moon, Lawrence D F

2016-06-01

Testing of therapies for disease or injury often involves the analysis of longitudinal data from animals. Modern analytical methods have advantages over conventional methods (particularly when some data are missing), yet they are not used widely by preclinical researchers. Here we provide an easy-to-use protocol for the analysis of longitudinal data from animals, and we present a click-by-click guide for performing suitable analyses using the statistical package IBM SPSS Statistics software (SPSS). We guide readers through the analysis of a real-life data set obtained when testing a therapy for brain injury (stroke) in elderly rats. If a few data points are missing, as in this example data set (for example, because of animal dropout), repeated-measures analysis of covariance may fail to detect a treatment effect. An alternative analysis method, such as the use of linear models (with various covariance structures), and analysis using restricted maximum likelihood estimation (to include all available data) can be used to better detect treatment effects. This protocol takes 2 h to carry out.

Defining SNAP by cross-sectional and longitudinal definitions of neurodegeneration.

PubMed

Wisse, L E M; Das, S R; Davatzikos, C; Dickerson, B C; Xie, S X; Yushkevich, P A; Wolk, D A

2018-01-01

Suspected non-Alzheimer's pathophysiology (SNAP) is a biomarker driven designation that represents a heterogeneous group in terms of etiology and prognosis. SNAP has only been identified by cross-sectional neurodegeneration measures, whereas longitudinal measures might better reflect "active" neurodegeneration and might be more tightly linked to prognosis. We compare neurodegeneration defined by cross-sectional 'hippocampal volume' only (SNAP/L-) versus both cross-sectional and longitudinal 'hippocampal atrophy rate' (SNAP/L+) and investigate how these definitions impact prevalence and the clinical and biomarker profile of SNAP in Mild Cognitive Impairment (MCI). 276 MCI patients from ADNI-GO/2 were designated amyloid "positive" (A+) or "negative" (A-) based on their florbetapir scan and neurodegeneration 'positive' or 'negative' based on cross-sectional hippocampal volume and longitudinal hippocampal atrophy rate. 74.1% of all SNAP participants defined by the cross-sectional definition of neurodegeneration also met the longitudinal definition of neurodegeneration, whereas 25.9% did not. SNAP/L+ displayed larger white matter hyperintensity volume, a higher conversion rate to dementia over 5 years and a steeper decline on cognitive tasks compared to SNAP/L- and the A- CN group. SNAP/L- had more abnormal values on neuroimaging markers and worse performance on cognitive tasks than the A- CN group, but did not show a difference in dementia conversion rate or longitudinal cognition. Using a longitudinal definition of neurodegeneration in addition to a cross-sectional one identifies SNAP participants with significant cognitive decline and a worse clinical prognosis for which cerebrovascular disease may be an important driver.

E6 and E7 Antibody Levels Are Potential Biomarkers of Recurrence in Patients with Advanced-Stage Human Papillomavirus-Positive Oropharyngeal Squamous Cell Carcinoma.

PubMed

Spector, Matthew E; Sacco, Assuntina G; Bellile, Emily; Taylor, Jeremy M G; Jones, Tamara; Sun, Kan; Brown, William C; Birkeland, Andrew C; Bradford, Carol R; Wolf, Gregory T; Prince, Mark E; Moyer, Jeffrey S; Malloy, Kelly; Swiecicki, Paul; Eisbruch, Avraham; McHugh, Jonathan B; Chepeha, Douglas B; Rozek, Laura; Worden, Francis P

2017-06-01

Purpose: There is a paucity of biomarkers to predict failure in human papillomavirus-positive (HPV + ) oropharyngeal squamous cell carcinoma (OPSCC) following curative therapy. E6/E7 viral oncoproteins are constitutively expressed in HPV + tumors and highly immunogenic, resulting in readily detected serum antibodies. The purpose of this study is to determine whether serum E6 and E7 antibody levels can potentially serve as a biomarker of recurrence in patients with HPV+OPSCC. Experimental Design: We evaluated E6/E7 antibody levels in patients with previously untreated, advanced stage (III, IVa-b), HPV+OPSCC receiving definitive chemoradiation under a uniform protocol from 2003 to 2010. Baseline and longitudinal serum samples were obtained from our archived repository. E6/E7 serum levels were measured using a glutathione- S -transferase capture ELISA and quantified by approximating the area under the dilution curve, and were analyzed using ANOVA and linear mixed model for longitudinal analysis. Results: We compared 22 HPV+OPSCC patients who developed recurrence with 30 patients who remained disease-free. There were no differences in T classification, N classification, disease subsite, or smoking status between the groups. In a longitudinal analysis, recurrent patients had significantly higher E6 and E7 serum antibody levels than the nonrecurrent patients over the follow-up period ( P = 0.02 and P = 0.002, respectively). Patients who recurred had a lower clearance of E7 antibody than patients who remained disease-free ( P = 0.0016). Conclusions: Patients with HPV+OPSCC whose disease recurs have a lower clearance of E6 and E7 antibodies than patients who do not have recurrence. The ratio of E7 antibody at disease recurrence compared with baseline is potentially a clinically significant measurement of disease status in HPV+OPSCC. Clin Cancer Res; 23(11); 2723-9. ©2016 AACR . ©2016 American Association for Cancer Research.

Charts relating the compressive buckling stress of longitudinally supported plates to the effective deflectional and rotational stiffness of the supports

NASA Technical Reports Server (NTRS)

Anderson, Roger A; Semonian, Joseph W

1954-01-01

A stability analysis is made of a long flat rectangular plate subjected to a uniform longitudinal compressive stress and supported along its longitudinal edges and along one or more longitudinal lines by elastic line supports. The elastic supports possess deflectional and rotational stiffness. Such configuration is an idealization of the compression cover skin and internal structure of a wing and tail surfaces. The results of the analysis are presented in the form of charts in which the buckling-stress coefficient is plotted against the buckle length of the plate for a wide range of support stiffnesses. The charts make possible the determination of the compressive buckling stress of plates supported by members whose stiffness may or may not be defined by elementary beam bending and twisting theory but yet whose effective restraint is amenable to evaluation. The deflectional and rotational stiffness provided by longitudinal stiffeners and full-depth webs is discussed and numerical examples are given to illustrate the application of the charts to the design of wing structures.

Model selection for marginal regression analysis of longitudinal data with missing observations and covariate measurement error.

PubMed

Shen, Chung-Wei; Chen, Yi-Hau

2015-10-01

Missing observations and covariate measurement error commonly arise in longitudinal data. However, existing methods for model selection in marginal regression analysis of longitudinal data fail to address the potential bias resulting from these issues. To tackle this problem, we propose a new model selection criterion, the Generalized Longitudinal Information Criterion, which is based on an approximately unbiased estimator for the expected quadratic error of a considered marginal model accounting for both data missingness and covariate measurement error. The simulation results reveal that the proposed method performs quite well in the presence of missing data and covariate measurement error. On the contrary, the naive procedures without taking care of such complexity in data may perform quite poorly. The proposed method is applied to data from the Taiwan Longitudinal Study on Aging to assess the relationship of depression with health and social status in the elderly, accommodating measurement error in the covariate as well as missing observations. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Closed-form analysis of fiber-matrix interface stresses under thermo-mechanical loadings

NASA Technical Reports Server (NTRS)

Naik, Rajiv A.; Crews, John H., Jr.

1992-01-01

Closed form techniques for calculating fiber matrix (FM) interface stresses, using repeating square and diamond regular arrays, were presented for a unidirectional composite under thermo-mechanical loadings. An Airy's stress function micromechanics approach from the literature, developed for calculating overall composite moduli, was extended in the present study to compute FM interface stresses for a unidirectional graphite/epoxy (AS4/3501-6) composite under thermal, longitudinal, transverse, transverse shear, and longitudinal shear loadings. Comparison with finite element results indicate excellent agreement of the FM interface stresses for the square array. Under thermal and longitudinal loading, the square array has the same FM peak stresses as the diamond array. The square array predicted higher stress concentrations under transverse normal and longitudinal shear loadings than the diamond array. Under transverse shear loading, the square array had a higher stress concentration while the diamond array had a higher radial stress concentration. Stress concentration factors under transverse shear and longitudinal shear loadings were very sensitive to fiber volume fraction. The present analysis provides a simple way to calculate accurate FM interface stresses for both the square and diamond array configurations.

Pulmonary function disparities exist and persist in Hispanic patients with cystic fibrosis: A longitudinal analysis.

PubMed

McGarry, Meghan E; Neuhaus, John M; Nielson, Dennis W; Burchard, Esteban; Ly, Ngoc P

2017-12-01

Hispanic patients with cystic fibrosis (CF) have decreased life expectancy compared to non-Hispanic white patients. Pulmonary function is a main predictor of life expectancy in CF. Ethnic differences in pulmonary function in CF have been understudied. The objective was to compare longitudinal pulmonary function between Hispanic and non-Hispanic white patients with CF. This cohort study of 15 018 6-25 years old patients in the CF Foundation Patient Registry from 2008 to 2013 compared FEV 1 percent predicted and longitudinal change in FEV 1 percent predicted in Hispanic to non-Hispanic white patients. We used linear mixed effects models with patient-specific slopes and intercepts, adjusting for 14 demographic and clinical variables. We did sub-analyses by CFTR class, F508del copies, and PERT use. Hispanic patients had lower FEV 1 percent predicted (79.9%) compared with non-Hispanic white patients (85.6%); (-5.8%, 95%CI -6.7% to -4.8%, P < 0.001), however, there was no difference in FEV 1 decline over time. Patients on PERT had a larger difference between Hispanic and non-Hispanic white patients in FEV 1 percent predicted than patients not on PERT (-6.0% vs -4.1%, P = 0.02). The ethnic difference in FEV 1 percent predicted was not statistically significant between CFTR classes (Class I-III: -6.1%, Class IV-V: -5.9%, Unclassified: -5.7%, P > 0.05) or between F508del copies (None: -7.6%, Heterozygotes: -5.6%, Homozygotes: -5.3%, P > 0.05). Disparities in pulmonary function exist in Hispanic patients with CF early in life and then persist without improving or worsening over time. It is valuable to investigate the factors contributing to pulmonary function in Hispanic patients with CF. © 2017 Wiley Periodicals, Inc.

Beyond the double banana: improved recognition of temporal lobe seizures in long-term EEG.

PubMed

Rosenzweig, Ivana; Fogarasi, András; Johnsen, Birger; Alving, Jørgen; Fabricius, Martin Ejler; Scherg, Michael; Neufeld, Miri Y; Pressler, Ronit; Kjaer, Troels W; van Emde Boas, Walter; Beniczky, Sándor

2014-02-01

To investigate whether extending the 10-20 array with 6 electrodes in the inferior temporal chain and constructing computed montages increases the diagnostic value of ictal EEG activity originating in the temporal lobe. In addition, the accuracy of computer-assisted spectral source analysis was investigated. Forty EEG samples were reviewed by 7 EEG experts in various montages (longitudinal and transversal bipolar, common average, source derivation, source montage, current source density, and reference-free montages) using 2 electrode arrays (10-20 and the extended one). Spectral source analysis used source montage to calculate density spectral array, defining the earliest oscillatory onset. From this, phase maps were calculated for localization. The reference standard was the decision of the multidisciplinary epilepsy surgery team on the seizure onset zone. Clinical performance was compared with the double banana (longitudinal bipolar montage, 10-20 array). Adding the inferior temporal electrode chain, computed montages (reference free, common average, and source derivation), and voltage maps significantly increased the sensitivity. Phase maps had the highest sensitivity and identified ictal activity at earlier time-point than visual inspection. There was no significant difference concerning specificity. The findings advocate for the use of these digital EEG technology-derived analysis methods in clinical practice.

Integral Airframe Structures (IAS): Validated Feasibility Study of Integrally Stiffened Metallic Fuselage Panels for Reducing Manufacturing Costs

NASA Technical Reports Server (NTRS)

Munroe, J.; Wilkins, K.; Gruber, M.; Domack, Marcia S. (Technical Monitor)

2000-01-01

The Integral Airframe Structures (IAS) program investigated the feasibility of using "integrally stiffened" construction for commercial transport fuselage structure. The objective of the program was to demonstrate structural performance and weight equal to current "built-up" structure with lower manufacturing cost. Testing evaluated mechanical properties, structural details, joint performance, repair, static compression, and two-bay crack residual strength panels. Alloys evaluated included 7050-T7451 plate, 7050-T74511 extrusion, 6013-T6511x extrusion, and 7475-T7351 plate. Structural performance was evaluated with a large 7475-T7351 pressure test that included the arrest of a two-bay longitudinal crack, and a measure of residual strength for a two-bay crack centered on a broken frame. Analysis predictions for the two-bay longitudinal crack panel correlated well with the test results. Analysis activity conducted by the IAS team strongly indicates that current analysis tools predict integral structural behavior as accurately as built-up structure. The cost study results indicated that, compared to built-up fabrication methods, high-speed machining structure from aluminum plate would yield a recurring cost savings of 61%. Part count dropped from 78 individual parts on a baseline panel to just 7 parts for machined IAS structure.

Enabling Analysis of Big, Thick, Long, and Wide Data: Data Management for the Analysis of a Large Longitudinal and Cross-National Narrative Data Set.

PubMed

Winskell, Kate; Singleton, Robyn; Sabben, Gaelle

2018-03-01

Distinctive longitudinal narrative data, collected during a critical 18-year period in the history of the HIV epidemic, offer a unique opportunity to examine how young Africans are making sense of evolving developments in HIV prevention and treatment. More than 200,000 young people from across sub-Saharan Africa took part in HIV-themed scriptwriting contests held at eight discrete time points between 1997 and 2014, creating more than 75,000 narratives. This article describes the data reduction and management strategies developed for our cross-national and longitudinal study of these qualitative data. The study aims to inform HIV communication practice by identifying cultural meanings and contextual factors that inform sexual behaviors and social practices, and also to help increase understanding of processes of sociocultural change. We describe our sampling strategies and our triangulating methodologies, combining in-depth narrative analysis, thematic qualitative analysis, and quantitative analysis, which are designed to enable systematic comparison without sacrificing ethnographic richness.

Analysis of longitudinal data from animals where some data are missing in SPSS

PubMed Central

Duricki, DA; Soleman, S; Moon, LDF

2017-01-01

Testing of therapies for disease or injury often involves analysis of longitudinal data from animals. Modern analytical methods have advantages over conventional methods (particularly where some data are missing) yet are not used widely by pre-clinical researchers. We provide here an easy to use protocol for analysing longitudinal data from animals and present a click-by-click guide for performing suitable analyses using the statistical package SPSS. We guide readers through analysis of a real-life data set obtained when testing a therapy for brain injury (stroke) in elderly rats. We show that repeated measures analysis of covariance failed to detect a treatment effect when a few data points were missing (due to animal drop-out) whereas analysis using an alternative method detected a beneficial effect of treatment; specifically, we demonstrate the superiority of linear models (with various covariance structures) analysed using Restricted Maximum Likelihood estimation (to include all available data). This protocol takes two hours to follow. PMID:27196723

Jointly modeling longitudinal proportional data and survival times with an application to the quality of life data in a breast cancer trial.

PubMed

Song, Hui; Peng, Yingwei; Tu, Dongsheng

2017-04-01

Motivated by the joint analysis of longitudinal quality of life data and recurrence free survival times from a cancer clinical trial, we present in this paper two approaches to jointly model the longitudinal proportional measurements, which are confined in a finite interval, and survival data. Both approaches assume a proportional hazards model for the survival times. For the longitudinal component, the first approach applies the classical linear mixed model to logit transformed responses, while the second approach directly models the responses using a simplex distribution. A semiparametric method based on a penalized joint likelihood generated by the Laplace approximation is derived to fit the joint model defined by the second approach. The proposed procedures are evaluated in a simulation study and applied to the analysis of breast cancer data motivated this research.

Weight loss is associated with improvements in cognitive function among overweight and obese people: A systematic review and meta-analysis.

PubMed

Veronese, Nicola; Facchini, Silvia; Stubbs, Brendon; Luchini, Claudio; Solmi, Marco; Manzato, Enzo; Sergi, Giuseppe; Maggi, Stefania; Cosco, Theodore; Fontana, Luigi

2017-01-01

Whilst obesity is associated with a higher risk of cognitive impairment, the influence of weight loss on cognitive function in obese/overweight people is equivocal. We conducted a meta-analysis of randomized controlled trials (RCTs) and longitudinal studies evaluating the influence of voluntary weight loss on cognitive function in obese/overweight individuals. Articles were acquired from a systematic search of major databases from inception till 01/2016. A random effect meta-analysis of weight loss interventions (diet, physical activity, bariatric surgery) on different cognitive domains (memory, attention, executive functions, language and motor speed) was conducted. Twenty studies (13 longitudinal studies=551 participants; 7 RCTs=328 treated vs. 140 controls) were included. Weight loss was associated with a significant improvement in attention and memory in both longitudinal studies and RCTs, whereas executive function and language improved in longitudinal and RCT studies, respectively. In conclusion, intentional weight loss in obese/overweight people is associated with improvements in performance across various cognitive domains. Future adequately powered RCTs are required to confirm/refute these findings. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Impact of Motherhood on the Career Pattern of Working Women: Differences in the Life Histories and Career Status of Employed Mothers and Working Women without Children.

ERIC Educational Resources Information Center

Owings, Jeffrey A.; And Others

A study compared employed mothers with working women who do not have children along dimensions reflective of their life histories and labor market experiences. It utilized data from two nationwide longitudinal surveys--the National Longitudinal Survey of Young Women aged 14 to 24 and the National Longitudinal Study of the High School Class of…

Exploring the Relationship between Access Technology and Standardized Test Scores for Youths with Visual Impairments: Secondary Analysis of the National Longitudinal Transition Study 2

ERIC Educational Resources Information Center

Freeland, Amy L.; Emerson, Robert Wall; Curtis, Amy B.; Fogarty, Kieran

2010-01-01

This article presents the findings of a secondary analysis of the National Longitudinal Transition Study 2 that explored the predictive association between training in access technology and performance on the Woodcock-Johnson Tests of Academic Achievement: III. The results indicated that the use of access technology had a limited predictive…

Definition and application of longitudinal stability derivatives for elastic airplanes

NASA Technical Reports Server (NTRS)

Kemp, W. B., Jr.

1972-01-01

A set of longitudinal stability derivatives for elastic airplanes is defined from fundamental principles allowing perturbations in forward speed. Application of these derivatives to longitudinal stability analysis by use of approximate expressions for static stability and control parameters as well as the dynamic equations of motion is illustrated. One commonly used alternative formulation for elastic airplanes is shown to yield significant inaccuracies because of inappropriate interpretation of inertial effects.

Quantile regression in the presence of monotone missingness with sensitivity analysis

PubMed Central

Liu, Minzhao; Daniels, Michael J.; Perri, Michael G.

2016-01-01

In this paper, we develop methods for longitudinal quantile regression when there is monotone missingness. In particular, we propose pattern mixture models with a constraint that provides a straightforward interpretation of the marginal quantile regression parameters. Our approach allows sensitivity analysis which is an essential component in inference for incomplete data. To facilitate computation of the likelihood, we propose a novel way to obtain analytic forms for the required integrals. We conduct simulations to examine the robustness of our approach to modeling assumptions and compare its performance to competing approaches. The model is applied to data from a recent clinical trial on weight management. PMID:26041008

Analytical investigation of the dynamics of tethered constellations in earth orbit

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.; Gullahorn, Gordon E.; Estes, Robert D.

1988-01-01

This Quarterly Report on Tethering in Earth Orbit deals with three topics: (1) Investigation of the propagation of longitudinal and transverse waves along the upper tether. Specifically, the upper tether is modeled as three massive platforms connected by two perfectly elastic continua (tether segments). The tether attachment point to the station is assumed to vibrate both longitudinally and transversely at a given frequency. Longitudinal and transverse waves propagate along the tethers affecting the acceleration levels at the elevator and at the upper platform. The displacement and acceleration frequency-response functions at the elevator and at the upper platform are computed for both longitudinal and transverse waves. An analysis to optimize the damping time of the longitudinal dampers is also carried out in order to select optimal parameters. The analytical evaluation of the performance of tuned vs. detuned longitudinal dampers is also part of this analysis. (2) The use of the Shuttle primary Reaction Control System (RCS) thrusters for blowing away a recoiling broken tether is discussed. A microcomputer system was set up to support this operation. (3) Most of the effort in the tether plasma physics study was devoted to software development. A particle simulation code has been integrated into the Macintosh II computer system and will be utilized for studying the physics of hollow cathodes.

Early Impairment of Cardiac Function and Asynchronization of Systemic Amyloidosis with Preserved Ejection Fraction Using Two-Dimensional Speckle Tracking Echocardiography.

PubMed

Huang, He; Jing, Xian-chao; Hu, Zhang-xue; Chen, Xi; Liu, Xiao-qin

2015-12-01

To observe the ventricular global and regional function of the patients with systemic amyloidosis using two-dimensional speckle tracking echocardiography. The study enrolled 31 consecutive biopsy-proved patients with systemic amyloidosis who underwent echocardiographic examination and EF ≥ 55% and 37 age- and gender-matched healthy controls. We compared systolic strain and strain rate, diastolic strain rate, time to peak strain, peak delay time in longitudinal, radial, circumferential directions in 16 left ventricular segments. The global peak systolic longitudinal and radial strain of left ventricle, peak systolic longitudinal strain and strain rate, diastolic strain rate of right ventricular free wall were also compared. (1) Global peak systolic longitudinal strain (GPSLS), peak systolic longitudinal strain (PSLS) and strain rate (PSLSR), peak early diastolic longitudinal strain rate (PELSR) in 16 segments were decreased in case (P < 0.05). (2) Peak systolic radial strain and strain rate of inferoseptum and inferolateral at the level of papillary muscle were lower (P < 0.05), and peak early diastolic radial strain rate (PERSR) was reduced (P < 0.05). (3) Peak early diastolic circumferential strain rate was lower (P < 0.05). (4) Time to peak systolic longitudinal, radial, circumferential strain was longer, and peak delay time at the same level retarded (P < 0.05). (5) Into right ventricular wall, PSLS and PSLSR at mid-segment, and PSLSR, PELSR, peak atrial systolic longitudinal strain rate (PALSR) at basal were reduced (P < 0.05). (6) Inverse correlation between interventricular septum (IVS) thickness and GPSLS and GPSRS was found (P < 0.05). Systolic and diastolic dysfunction existed in systemic amyloidosis with preserved EF. Mechanical contraction disorder may be one reason for systolic dysfunction. GPLSR and GPRSR were negatively related to IVS thickness. © 2015, Wiley Periodicals, Inc.

[Origin of motion in the human ureter: mechanics, energetics and kinetics of the myosin molecular motors].

PubMed

Vargiu, Romina; Perinu, Anna; De Lisa, Antonello; Tintrup, Frank; Manca, Francesco; Mancinelli, Rino

2012-01-01

Ureteral peristalsis is the result of coordinated mechanical motor performance of longitudinal and circular smooth muscle layer of the ureter wall. The main aim of this study was to characterize in smooth muscle of proximal segments of human ureter, the mechanical properties at level of muscle tissue and at level of myosin molecular motors. Ureteral samples were collected from 15 patients, who underwent nephrectomy for renal cancer. Smooth muscle strips longitudinally and circularly oriented from proximal segments of human ureter were used for the in vitro experiments. Mechanical indices including the maximum unloaded shortening velocity (Vmax), and the maximum isometric tension (P0) normalized per cross-sectional area, were determined in vitro determined in electrically evoked contractions of longitudinal and circular smooth muscle strips. Myosin cross-bridge (CB) number per mm2 (Ψ) the elementary force per single CB (Ψ) and kinetic parameters were calculated in muscle strips, using Huxley's equations adapted to nonsarcomeric muscles. Longitudinal smooth muscle strips exhibited a significantly (p<0.05) faster Vmax (63%) and a higher P0 (40%), if compared to circular strips. Moreover, longitudinal muscle strips showed a significantly higher unitary force (Ψ) per CB. However, no significant differences were observed in CB number, the attachment (f1) and the detachment (g2) rate constants between longitudinal and circular muscle strips. The main result obtained in the present work documents that the mechanical, energetic and unitary forces per CB of longitudinal layer of proximal ureter are better compared to the circular one; these preliminary findings suggested, unlike intestinal smooth muscle, a major role of longitudinal smooth muscle layer in the ureter peristalsis.

A Longitudinal Study on Resting State Functional Connectivity in Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease.

PubMed

Hafkemeijer, Anne; Möller, Christiane; Dopper, Elise G P; Jiskoot, Lize C; van den Berg-Huysmans, Annette A; van Swieten, John C; van der Flier, Wiesje M; Vrenken, Hugo; Pijnenburg, Yolande A L; Barkhof, Frederik; Scheltens, Philip; van der Grond, Jeroen; Rombouts, Serge A R B

2017-01-01

Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) are the most common types of early-onset dementia. We applied longitudinal resting state functional magnetic resonance imaging (fMRI) to delineate functional brain connections relevant for disease progression and diagnostic accuracy. We used two-center resting state fMRI data of 20 AD patients (65.1±8.0 years), 12 bvFTD patients (64.7±5.4 years), and 22 control subjects (63.8±5.0 years) at baseline and 1.8-year follow-up. We used whole-network and voxel-based network-to-region analyses to study group differences in functional connectivity at baseline and follow-up, and longitudinal changes in connectivity within and between groups. At baseline, connectivity between paracingulate gyrus and executive control network, between cuneal cortex and medial visual network, and between paracingulate gyrus and salience network was higher in AD compared with controls. These differences were also present after 1.8 years. At follow-up, connectivity between angular gyrus and right frontoparietal network, and between paracingulate gyrus and default mode network was lower in bvFTD compared with controls, and lower compared with AD between anterior cingulate gyrus and executive control network, and between lateral occipital cortex and medial visual network. Over time, connectivity decreased in AD between precuneus and right frontoparietal network and in bvFTD between inferior frontal gyrus and left frontoparietal network. Longitudinal changes in connectivity between supramarginal gyrus and right frontoparietal network differ between both patient groups and controls. We found disease-specific brain regions with longitudinal connectivity changes. This suggests the potential of longitudinal resting state fMRI to delineate regions relevant for disease progression and for diagnostic accuracy, although no group differences in longitudinal changes in the direct comparison of AD and bvFTD were found.

Applying the Longitudinal Model from Item Response Theory to Assess Health-Related Quality of Life in the PRODIGE 4/ACCORD 11 Randomized Trial.

PubMed

Barbieri, Antoine; Anota, Amélie; Conroy, Thierry; Gourgou-Bourgade, Sophie; Juzyna, Beata; Bonnetain, Franck; Lavergne, Christian; Bascoul-Mollevi, Caroline

2016-07-01

A new longitudinal statistical approach was compared to the classical methods currently used to analyze health-related quality-of-life (HRQoL) data. The comparison was made using data in patients with metastatic pancreatic cancer. Three hundred forty-two patients from the PRODIGE4/ACCORD 11 study were randomly assigned to FOLFIRINOX versus gemcitabine regimens. HRQoL was evaluated using the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30. The classical analysis uses a linear mixed model (LMM), considering an HRQoL score as a good representation of the true value of the HRQoL, following EORTC recommendations. In contrast, built on the item response theory (IRT), our approach considered HRQoL as a latent variable directly estimated from the raw data. For polytomous items, we extended the partial credit model to a longitudinal analysis (longitudinal partial credit model [LPCM]), thereby modeling the latent trait as a function of time and other covariates. Both models gave the same conclusions on 11 of 15 HRQoL dimensions. HRQoL evolution was similar between the 2 treatment arms, except for the symptoms of pain. Indeed, regarding the LPCM, pain perception was significantly less important in the FOLFIRINOX arm than in the gemcitabine arm. For most of the scales, HRQoL changes over time, and no difference was found between treatments in terms of HRQoL. The use of LMM to study the HRQoL score does not seem appropriate. It is an easy-to-use model, but the basic statistical assumptions do not check. Our IRT model may be more complex but shows the same qualities and gives similar results. It has the additional advantage of being more precise and suitable because of its direct use of raw data. © The Author(s) 2015.

Semiparametric Estimation of the Impacts of Longitudinal Interventions on Adolescent Obesity using Targeted Maximum-Likelihood: Accessible Estimation with the ltmle Package

PubMed Central

Decker, Anna L.; Hubbard, Alan; Crespi, Catherine M.; Seto, Edmund Y.W.; Wang, May C.

2015-01-01

While child and adolescent obesity is a serious public health concern, few studies have utilized parameters based on the causal inference literature to examine the potential impacts of early intervention. The purpose of this analysis was to estimate the causal effects of early interventions to improve physical activity and diet during adolescence on body mass index (BMI), a measure of adiposity, using improved techniques. The most widespread statistical method in studies of child and adolescent obesity is multi-variable regression, with the parameter of interest being the coefficient on the variable of interest. This approach does not appropriately adjust for time-dependent confounding, and the modeling assumptions may not always be met. An alternative parameter to estimate is one motivated by the causal inference literature, which can be interpreted as the mean change in the outcome under interventions to set the exposure of interest. The underlying data-generating distribution, upon which the estimator is based, can be estimated via a parametric or semi-parametric approach. Using data from the National Heart, Lung, and Blood Institute Growth and Health Study, a 10-year prospective cohort study of adolescent girls, we estimated the longitudinal impact of physical activity and diet interventions on 10-year BMI z-scores via a parameter motivated by the causal inference literature, using both parametric and semi-parametric estimation approaches. The parameters of interest were estimated with a recently released R package, ltmle, for estimating means based upon general longitudinal treatment regimes. We found that early, sustained intervention on total calories had a greater impact than a physical activity intervention or non-sustained interventions. Multivariable linear regression yielded inflated effect estimates compared to estimates based on targeted maximum-likelihood estimation and data-adaptive super learning. Our analysis demonstrates that sophisticated, optimal semiparametric estimation of longitudinal treatment-specific means via ltmle provides an incredibly powerful, yet easy-to-use tool, removing impediments for putting theory into practice. PMID:26046009

Control methods for aiding a pilot during STOL engine failure transients

NASA Technical Reports Server (NTRS)

Nelson, E. R.; Debra, D. B.

1976-01-01

Candidate autopilot control laws that control the engine failure transient sink rates by demonstrating the engineering application of modern state variable control theory were defined. The results of approximate modal analysis were compared to those derived from full state analyses provided from computer design solutions. The aircraft was described, and a state variable model of its longitudinal dynamic motion due to engine and control variations was defined. The classical fast and slow modes were assumed to be sufficiently different to define reduced order approximations of the aircraft motion amendable to hand analysis control definition methods. The original state equations of motion were also applied to a large scale state variable control design program, in particular OPTSYS. The resulting control laws were compared with respect to their relative responses, ease of application, and meeting the desired performance objectives.

An overview of longitudinal data analysis methods for neurological research.

PubMed

Locascio, Joseph J; Atri, Alireza

2011-01-01

The purpose of this article is to provide a concise, broad and readily accessible overview of longitudinal data analysis methods, aimed to be a practical guide for clinical investigators in neurology. In general, we advise that older, traditional methods, including (1) simple regression of the dependent variable on a time measure, (2) analyzing a single summary subject level number that indexes changes for each subject and (3) a general linear model approach with a fixed-subject effect, should be reserved for quick, simple or preliminary analyses. We advocate the general use of mixed-random and fixed-effect regression models for analyses of most longitudinal clinical studies. Under restrictive situations or to provide validation, we recommend: (1) repeated-measure analysis of covariance (ANCOVA), (2) ANCOVA for two time points, (3) generalized estimating equations and (4) latent growth curve/structural equation models.

Variable selection for marginal longitudinal generalized linear models.

PubMed

Cantoni, Eva; Flemming, Joanna Mills; Ronchetti, Elvezio

2005-06-01

Variable selection is an essential part of any statistical analysis and yet has been somewhat neglected in the context of longitudinal data analysis. In this article, we propose a generalized version of Mallows's C(p) (GC(p)) suitable for use with both parametric and nonparametric models. GC(p) provides an estimate of a measure of model's adequacy for prediction. We examine its performance with popular marginal longitudinal models (fitted using GEE) and contrast results with what is typically done in practice: variable selection based on Wald-type or score-type tests. An application to real data further demonstrates the merits of our approach while at the same time emphasizing some important robust features inherent to GC(p).

Elastic stability of biaxially loaded longitudinally stiffened composite structures.

NASA Technical Reports Server (NTRS)

Viswanathan, A. V.; Tamekuni, M.; Tripp, L. L.

1973-01-01

A linear analysis method is presented for the elastic stability of structures of uniform cross section, that may be idealized as an assemblage of laminated plate-strips, flat and curved, and beams. Each plate-strip and beam covers the entire length of the structure and is simply supported on the edges normal to the longitudinal axis. Arbitrary boundary conditions may be specified on any external longitudinal side of plate-strips. The structure or selected plate-strips may be loaded in any desired combination of inplane biaxial loads. The analysis simultaneously considers all modes of instability and is applicable for the buckling of laminated composite structures. Some numerical results are presented to indicate possible applications.

Intimate Partner Violence and Neighborhood Income: A Longitudinal Analysis

PubMed Central

Bonomi, Amy E.; Trabert, Britton; Anderson, Melissa L.; Kernic, Mary A.; Holt, Victoria L.

2017-01-01

This investigation used a longitudinal design to examine the relationship between neighborhood-level income, individual-level predictors, and police-reported intimate partner violence in 5,994 urban couples followed over 2 years. At the baseline abuse incident, intimate partner violence rates were highest in the poorest neighborhoods (13.8 per 1,000 women in the lowest income quartile, followed by 12.1, 8.2, and 5.0 in the respective higher income quartiles). However, in the longitudinal analysis, weapon use at the baseline abuse event was a much stronger predictor of repeat abuse (incident rate ratios ranging from 1.72 for physical abuse to 1.83 for non-physical abuse) than neighborhood income. PMID:24476760

Higher education affects accelerated cortical thinning in Alzheimer's disease: a 5-year preliminary longitudinal study.

PubMed

Cho, Hanna; Jeon, Seun; Kim, Changsoo; Ye, Byoung Seok; Kim, Geon Ha; Noh, Young; Kim, Hee Jin; Yoon, Cindy W; Kim, Yeo Jin; Kim, Jung-Hyun; Park, Sang Eon; Kim, Sung Tae; Lee, Jong-Min; Kang, Sue J; Suh, Mee Kyung; Chin, Juhee; Na, Duk L; Kang, Dae Ryong; Seo, Sang Won

2015-01-01

Epidemiological studies have reported that higher education (HE) is associated with a reduced risk of incident Alzheimer's disease (AD). However, after the clinical onset of AD, patients with HE levels show more rapid cognitive decline than patients with lower education (LE) levels. Although education level and cognition have been linked, there have been few longitudinal studies investigating the relationship between education level and cortical decline in patients with AD. The aim of this study was to compare the topography of cortical atrophy longitudinally between AD patients with HE (HE-AD) and AD patients with LE (LE-AD). We prospectively recruited 36 patients with early-stage AD and 14 normal controls. The patients were classified into two groups according to educational level, 23 HE-AD (>9 years) and 13 LE-AD (≤9 years). As AD progressed over the 5-year longitudinal follow-ups, the HE-AD showed a significant group-by-time interaction in the right dorsolateral frontal and precuneus, and the left parahippocampal regions compared to the LE-AD. Our study reveals that the preliminary longitudinal effect of HE accelerates cortical atrophy in AD patients over time, which underlines the importance of education level for predicting prognosis.

First stable isotope analysis of Asiatic wild ass tail hair from the Mongolian Gobi

PubMed Central

Horacek, Micha; Sturm, Martina Burnik; Kaczensky, Petra

2015-01-01

Stable isotope analysis has become a powerful tool to study feeding ecology, water use or movement pattern in contemporary, historic and ancient species. Certain hair and teeth grow continuously, and when sampled longitudinally can provide temporally explicit information on dietary regime and movement pattern. In an initial trial, we analysed a tail sample of an Asiatic wild ass (Equus hemionus) from the Mongolian Gobi. We found seasonal variations in H, C and N isotope patterns, likely being the result of temporal variations in available feeds, water supply and possibly physiological status. Thus stable isotope analysis shows promise to study the comparative ecology of the three autochthonous equid species in the Mongolian Gobi. PMID:26339116

A Longitudinal Study of Growth and Development and the Incidence of Physical Defects at Ages 9 and 10. A Progress Report to the Bernard van Leer Foundation on the Growth and Development Study of the Mt. Druitt Longitudinal Study.

ERIC Educational Resources Information Center

Clark, Anne; O'Brien, Peter

A longitudinal comparative study was made of the physical growth and development of Australian fourth-grade students from low, medium, and high socioeconomic groups. Specific questions addressed were (1) Do children differing in socioeconomic status differ in anthropometric characteristics and incidence of physical defects? (2) What is the…

The importance of the orientation of the electrode plates in recording the external anal sphincter EMG by non-invasive anal plug electrodes.

PubMed

Binnie, N R; Kawimbe, B M; Papachrysostomou, M; Clare, N; Smith, A N

1991-02-01

Two non-invasive anal plug electrodes of similar size have been compared, one with the electrode plates orientated circularly in the anal canal and the other with the plates in the long axis of the anal canal. There was a significant increase in the amplitude in the EMG signals recorded at rest and during squeeze from the external anal sphincter with a longitudinally placed electrode in 117 patients. Inappropriate contraction of the external anal sphincter when straining at stool was more readily detected using the longitudinal electrode in 52 patients investigated for intractable constipation. The longitudinal electrode detected the amplitude of the response to the elicitation of a pudeno-anal reflex more readily than the circular electrode. When in 12 of the 117 the pudeno-anal reflex EMG signal was either absent or not detected with the circumferential plug electrode, the longitudinal electrode detected the presence of a low amplitude response in 11 of these. When the non-invasive longitudinal electrode was compared to invasive fine wire stainless steel electrodes, a correlation was found for external anal sphincter resting EMG (r = 0.99, p less than 0.01), voluntary squeeze EMG (r = 0.99, p less than 0.001) and strain EMG (r = 0.91, p less than 0.01). The longitudinal anal plug electrode thus facilitates surface acquisition of EMG activity.

An Analysis of the Effects of Wing Aspect Ratio and Tail Location on Static Longitudinal Stability Below the Mach Number of Lift Divergence

NASA Technical Reports Server (NTRS)

Axelson, John A.; Crown, J. Conrad

1948-01-01

An analysis is presented of the influence of wing aspect ratio and tail location on the effects of compressibility upon static longitudinal stability. The investigation showed that the use of reduced wing aspect ratios or short tail lengths leads to serious reductions in high-speed stability and the possibility of high-speed instability.

Intrinsic to extrinsic phonon lifetime transition in a GaAs-AlAs superlattice.

PubMed

Hofmann, F; Garg, J; Maznev, A A; Jandl, A; Bulsara, M; Fitzgerald, E A; Chen, G; Nelson, K A

2013-07-24

We have measured the lifetimes of two zone-center longitudinal acoustic phonon modes, at 320 and 640 GHz, in a 14 nm GaAs/2 nm AlAs superlattice structure. By comparing measurements at 296 and 79 K we separate the intrinsic contribution to phonon lifetime determined by phonon-phonon scattering from the extrinsic contribution due to defects and interface roughness. At 296 K, the 320 GHz phonon lifetime has approximately equal contributions from intrinsic and extrinsic scattering, whilst at 640 GHz it is dominated by extrinsic effects. These measurements are compared with intrinsic and extrinsic scattering rates in the superlattice obtained from first-principles lattice dynamics calculations. The calculated room-temperature intrinsic lifetime of longitudinal phonons at 320 GHz is in agreement with the experimentally measured value of 0.9 ns. The model correctly predicts the transition from predominantly intrinsic to predominantly extrinsic scattering; however the predicted transition occurs at higher frequencies. Our analysis indicates that the 'interfacial atomic disorder' model is not entirely adequate and that the observed frequency dependence of the extrinsic scattering rate is likely to be determined by a finite correlation length of interface roughness.

Analysis of Longitudinal Studies With Repeated Outcome Measures: Adjusting for Time-Dependent Confounding Using Conventional Methods.

PubMed

Keogh, Ruth H; Daniel, Rhian M; VanderWeele, Tyler J; Vansteelandt, Stijn

2018-05-01

Estimation of causal effects of time-varying exposures using longitudinal data is a common problem in epidemiology. When there are time-varying confounders, which may include past outcomes, affected by prior exposure, standard regression methods can lead to bias. Methods such as inverse probability weighted estimation of marginal structural models have been developed to address this problem. However, in this paper we show how standard regression methods can be used, even in the presence of time-dependent confounding, to estimate the total effect of an exposure on a subsequent outcome by controlling appropriately for prior exposures, outcomes, and time-varying covariates. We refer to the resulting estimation approach as sequential conditional mean models (SCMMs), which can be fitted using generalized estimating equations. We outline this approach and describe how including propensity score adjustment is advantageous. We compare the causal effects being estimated using SCMMs and marginal structural models, and we compare the two approaches using simulations. SCMMs enable more precise inferences, with greater robustness against model misspecification via propensity score adjustment, and easily accommodate continuous exposures and interactions. A new test for direct effects of past exposures on a subsequent outcome is described.

Reassessing the educational environment among undergraduate students in a chiropractic training institution: A study over time

PubMed Central

Palmgren, Per J.; Sundberg, Tobias; Laksov, Klara Bolander

2015-01-01

Objective The aim of the study was twofold: (1) to compare the perceived educational environment at 2 points in time and (2) to longitudinally examine potential changes in perceptions of the educational environment over time. Methods The validated Dundee Ready Educational Environment Measure (DREEM), a 50-item, self-administered Likert-type inventory, was used in this prospective study. Employing convenience sampling, undergraduate chiropractic students were investigated at 2 points in time: 2009 (n = 124) and 2012 (n = 127). An analysis of 2 matching samples was performed on 27% (n = 34) of the respondents in 2009. Results A total of 251 students (79%) completed the inventory, 83% (n = 124) in 2009 and 75% (n = 127) in 2012. The overall DREEM scores in both years were excellent: 156 (78%) and 153 (77%), respectively. The students' perceptions of teachers differed significantly between the 2 cohort years, decreasing from 77% to 73%. Three items received deprived scores: limited support for stressed students, authoritarian teachers, and an overemphasis on factual learning; the latter significantly decreased in 2012. In the longitudinal sample these items also displayed scores below the expected mean. Conclusion Students viewed the educational environment as excellent both in 2009 and 2012. The perceptions of teachers declined with time; however, this could be attributed to teachers' new roles. Certain aspects of the educational environment factored prominently during the comparative points in time, as well as longitudinally, and these ought to be further investigated and addressed to provide an enhanced educational environment. PMID:26023892

Disruption of brain anatomical networks in schizophrenia: A longitudinal, diffusion tensor imaging based study.

PubMed

Sun, Yu; Chen, Yu; Lee, Renick; Bezerianos, Anastasios; Collinson, Simon L; Sim, Kang

2016-03-01

Despite convergent neuroimaging evidence indicating a wide range of brain abnormalities in schizophrenia, our understanding of alterations in the topological architecture of brain anatomical networks and how they are modulated over time, is still rudimentary. Here, we employed graph theoretical analysis of longitudinal diffusion tensor imaging data (DTI) over a 5-year period to investigate brain network topology in schizophrenia and its relationship with clinical manifestations of the illness. Using deterministic tractography, weighted brain anatomical networks were constructed from 31 patients experiencing schizophrenia and 28 age- and gender-matched healthy control subjects. Although the overall small-world characteristics were observed at both baseline and follow-up, a scan-point independent significant deficit of global integration was found in patients compared to controls, suggesting dysfunctional integration of the brain and supporting the notion of schizophrenia as a disconnection syndrome. Specifically, several brain regions (e.g., the inferior frontal gyrus and the bilateral insula) that are crucial for cognitive and emotional integration were aberrant. Furthermore, a significant group-by-longitudinal scan interaction was revealed in the characteristic path length and global efficiency, attributing to a progressive aberration of global integration in patients compared to healthy controls. Moreover, the progressive disruptions of the brain anatomical network topology were associated with the clinical symptoms of the patients. Together, our findings provide insights into the substrates of anatomical dysconnectivity patterns for schizophrenia and highlight the potential for connectome-based metrics as neural markers of illness progression and clinical change with treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Anterior Versus Posterior Approach for Multilevel Degenerative Cervical Disease: A Retrospective Propensity Score-Matched Study of the MarketScan Database.

PubMed

Cole, Tyler; Veeravagu, Anand; Zhang, Michael; Azad, Tej D; Desai, Atman; Ratliff, John K

2015-07-01

Retrospective 2:1 propensity score-matched analysis on a national longitudinal database between 2006 and 2010. To compare rates of adverse events, revisions procedure rates, and payment differences in anterior cervical fusion procedures compared with posterior laminectomy and fusion procedures with at least 3 levels of instrumentation. The comparative benefits of anterior versus posterior approach to multilevel degenerative cervical disease remain controversial. Recent systematic reviews have reached conflicting conclusions. We demonstrate the comparative economic and clinical outcomes of anterior and posterior approaches for multilevel cervical degenerative disk disease. We identified 13,662 patients in a national billing claims database who underwent anterior or posterior cervical fusion procedures with 3 or more levels of instrumentation. Cohorts were balanced using 2:1 propensity score matching and outcomes were compared using bivariate analysis. With the exception of dysphagia (6.4% in anterior and 1.4% in posterior), overall 30-day complication rates were lower in the anterior approach group. The rate of any complication excluding dysphagia with anterior approaches was 12.3%, significantly lower (P < 0.0001) than that of posterior approaches, 17.8%. Anterior approaches resulted in lower hospital ($18,346 vs. $23,638) and total payments ($28,963 vs. $33,526). Patients receiving an anterior surgical approach demonstrated significantly lower rate of 30-day readmission (5.1% vs. 9.9%, P < 0.0001), were less likely to require revision surgery (12.8% vs. 18.1%, P < 0.0001), and had a shorter length of stay by 1.5 nights (P < 0.0001). Anterior approaches in the surgical management of multilevel degenerative cervical disease provide clinical advantages over posterior approaches, including lower overall complication rates, revision procedure rates, and decreased length of stay. Anterior approach procedures are also associated with decreased overall payments. These findings must be interpreted in light of limitations inherent to retrospective longitudinal studies including absence of subjective and radiographical outcomes. 3.

Aeroelastic Sizing for High-Speed Research (HSR) Longitudinal Control Alternatives Project (LCAP)

NASA Technical Reports Server (NTRS)

Walsh, Joanne L.; Dunn, H. J.; Stroud, W. Jefferson; Barthelemy, J.-F.; Weston, Robert P.; Martin, Carl J.; Bennett, Robert M.

2005-01-01

The Longitudinal Control Alternatives Project (LCAP) compared three high-speed civil transport configurations to determine potential advantages of the three associated longitudinal control concepts. The three aircraft configurations included a conventional configuration with a layout having a horizontal aft tail, a configuration with a forward canard in addition to a horizontal aft tail, and a configuration with only a forward canard. The three configurations were aeroelastically sized and were compared on the basis of operational empty weight (OEW) and longitudinal control characteristics. The sized structure consisted of composite honeycomb sandwich panels on both the wing and the fuselage. Design variables were the core depth of the sandwich and the thicknesses of the composite material which made up the face sheets of the sandwich. Each configuration was sized for minimum structural weight under linear and nonlinear aeroelastic loads subject to strain, buckling, ply-mixture, and subsonic and supersonic flutter constraints. This report describes the methods that were used and the results that were generated for the aeroelastic sizing of the three configurations.

Exploring high-resolution magic angle spinning (HR-MAS) NMR spectroscopy for metabonomic analysis of apples.

PubMed

Vermathen, Martina; Marzorati, Mattia; Vermathen, Peter

2012-01-01

Classical liquid-state high-resolution (HR) NMR spectroscopy has proved a powerful tool in the metabonomic analysis of liquid food samples like fruit juices. In this paper the application of (1)H high-resolution magic angle spinning (HR-MAS) NMR spectroscopy to apple tissue is presented probing its potential for metabonomic studies. The (1)H HR-MAS NMR spectra are discussed in terms of the chemical composition of apple tissue and compared to liquid-state NMR spectra of apple juice. Differences indicate that specific metabolic changes are induced by juice preparation. The feasibility of HR-MAS NMR-based multivariate analysis is demonstrated by a study distinguishing three different apple cultivars by principal component analysis (PCA). Preliminary results are shown from subsequent studies comparing three different cultivation methods by means of PCA and partial least squares discriminant analysis (PLS-DA) of the HR-MAS NMR data. The compounds responsible for discriminating organically grown apples are discussed. Finally, an outlook of our ongoing work is given including a longitudinal study on apples.

New multi-scale approach to improve explanation of patterns of contemporary morphodynamics in the badland landscapes of Central Italy: the important Quaternary context

NASA Astrophysics Data System (ADS)

Vergari, Francesca; Troiani, Francesco; Della Seta, Marta; Faulkner, Hazel; Schwanghart, Wolfgang; Ciccacci, Sirio; Del Monte, Maurizio; Fredi, Paola

2016-04-01

Spatial patterns and magnitudes of short-term erosional processes are often the result of longer-term landscape-wide morphodynamics. Their combined analysis, however, is challenged by different spatial scales, data availability and resolution. Integrating both analyses has thus rarely been done though urgently needed to better understand and manage present day erosional dynamics and land degradation. In this study we aim at overcoming these shortcomings by exploring a multi-scale approach, based on a nested experimental design that integrates the traditional monitoring of erosion processes at local and short time scale, with the longer-term (over the last 103-105 yr) and basin-to-morphostructure scale analysis of landscape morphodynamics. We investigated the geomorphological behaviour of a Mediterranean active badland site located in the Upper Orcia Valley (Southern Tuscany, Italy). This choice is justified by the availability of decadal erosion monitoring datasets at a range of scales, and the rapidity of development of erosion processes. Based on the analysis of drainage network and its longitudinal and planform pattern, we tested the hypothesis that this rejuvenating, actively erosional landscape presents hotspots of denudation processes on hillslope and in channel network that are largely associated with (a) knickpoints on stream longitudinal profiles, (b) sites of strong connectivity, and (c) sites of strong divide competition with adjacent, aggressive and non-aggressive systems. To illustrate and explore this nested approach, we extracted the channel network and analysed stream longitudinal profiles using the MATLAB-based TopoToolbox program, starting from the 27x27 m Aster GDEM. The stream network morphometric analyses involved computing and mapping χ-values, a transformation that normalizes the longitudinal distance by upslope area and which serves as a proxy of the dynamic state of river basins based on the current geometry of the river network. Finally, we projected on the longitudinal profiles of the Orcia River and some of its main tributaries a full range of geomorphic features which are relevant for the interpretation of the landscape morphoevolution, connectivity and erosion/deposition dynamics: i) competitive divides; ii) sites with different degree of connectivity within the drainage system; iii) sites experiencing different erosion rates; iv) sites with in-channel depositional features and landslide deposits; v) remnants of relict geomorphic surfaces. The plano-altimetric distribution of such features, compared with the drainage network evolutionary stage, allowed to better understand the morphodynamics of badland areas and to define future scenarios in the perspective of a better management of hazardous processes.

Ozil IP torsional mode versus combined torsional/longitudinal microcoaxial phacoemulsification.

PubMed

Helvacioglu, Firat; Tunc, Zeki; Yeter, Celal; Oguzhan, Hasan; Sencan, Sadik

2012-01-01

To compare the safety and efficacy of microcoaxial phacoemulsification surgeries performed with the Ozil Intelligent Phaco (IP) torsional mode and combined torsional/longitudinal ultrasound (US) mode using the Infiniti Vision System (Alcon Laboratories). In this prospective randomized comparative study, 60 eyes were assigned to 2.2-mm microcoaxial phacoemulsification using the Ozil IP torsional mode (group 1) or combined torsional/longitudinal US mode (group 2). The primary outcome measures were US time (UST), cumulative dissipated energy (CDE), longitudinal and torsional ultrasound amplitudes, mean operation time, mean volume of balanced salt solution (BSS) used, and surgical complications. Both groups included 30 eyes. Mean UST, CDE, and longitudinal and torsional ultrasound amplitudes in group 1 were 1 minute 15±34.33 seconds, 8.74±5.64, 0.43±0.74, and 25.56±8.56, respectively, and these parameters in group 2 were 1 minute 40±51.44 seconds, 9.28±5.99, 3.64±1.55, and 3.71±1.34, respectively. UST and longitudinal amplitudes were found to be significantly low in group 1 (p<0.001, p<0.001), whereas torsional amplitude was found to be significantly high in this group (p=0.001). Mean volumes of BSS used in groups 1 and 2 were 63.30±18.00 cc and 84.50±28.65 cc, respectively (p=0.001). The Ozil IP torsional mode may provide more effective lens removal than the combined torsional/longitudinal US mode with a lower UST and volume of BSS used.

LONGITUDINAL TRAJECTORIES OF ARTERIAL STIFFNESS AND THE ROLE OF BLOOD PRESSURE: THE BALTIMORE LONGITUDINAL STUDY OF AGING

PubMed Central

AlGhatrif, Majd; Strait, James B.; Morrell, Chris; Canepa, Marco; Wright, Jeanette; Elango, Palchamy; Scuteri, Angelo; Najjar, Samer S.; Ferrucci, Luigi; Lakatta, Edward G.

2013-01-01

Carotid-femoral pulse wave velocity (PWV), a marker of arterial stiffness, is an established independent cardiovascular (CV) risk factor. Little information is available on the pattern and determinants of the longitudinal change in PWV with aging. Such information is crucial to elucidating mechanisms underlying arterial stiffness and the design of interventions to retard it. Between 1988 and 2013, we collected 2 to 9 serial measures of PWV in 354 men and 423 women of the Baltimore Longitudinal Study of Aging, who were 21 to 94 years of age and free of clinically significant CV disease. Rates of PWV increase accelerated with advancing age in men more than women, leading to gender differences in PWV after the age of 50. In both sexes, not only systolic blood pressure (SBP) ≥140mmHg, but also SBP of 120–139mmHg was associated with steeper rates of PWV increase compared to SBP<120mmHg. Furthermore, there was a dose-dependent effect SBP in men with marked acceleration in PWV rate of increase with age at SBP ≥140mmHg compared to SBP of 120–139mmHg. Except for waist circumference in women, no other traditional CV risk factors predicted longitudinal PWV increase. In conclusion, the steeper longitudinal increase of PWV in men than women led to gender difference that expanded with advancing age. Age and systolic blood pressure are the main longitudinal determinants of pulse wave velocity and the effect of systolic blood pressure on PWV trajectories exists even in the pre-hypertensive range. PMID:24001897

Oscillatory mode transition for supersonic open cavity flows

NASA Astrophysics Data System (ADS)

Kumar, Mayank; Vaidyanathan, Aravind

2018-02-01

The transition in the primary oscillatory mode in an open cavity has been experimentally investigated and the associated characteristics in a Mach 1.71 flow has been analyzed. The length-to-depth (L/D) ratios of the rectangular cavities are varied from 1.67 to 3.33. Unsteady pressure measurement and flow visualization are employed to understand the transitional flow physics. Flow visualization revealed the change in oscillation pattern from longitudinal mode to transverse mode and is also characterized by the presence of two bow shocks at the trailing edge instead of one. The transition is found to occur between L/D 1.67 and 2, marked by a change in the feedback mechanism, resulting in a shift from the vortex circulation driven transverse feedback mode to the oscillating shear layer driven longitudinal feedback mode. Cavities oscillating in the transition mode exhibit multiple tones of comparable strength. Correlation analysis indicated the shift in the feedback mechanism. Wavelet analysis revealed the temporal behaviour of tones during transition. Tone switching is observed in deeper cavities and is attributed to the occurrence of two bow shocks as evident from the temporo-spectral characteristics of transition that affects the shear layer modal shape.

Social relationships and risk of dementia: A systematic review and meta-analysis of longitudinal cohort studies.

PubMed

Kuiper, Jisca S; Zuidersma, Marij; Oude Voshaar, Richard C; Zuidema, Sytse U; van den Heuvel, Edwin R; Stolk, Ronald P; Smidt, Nynke

2015-07-01

It is unclear to what extent poor social relationships are related to the development of dementia. A comprehensive systematic literature search identified 19 longitudinal cohort studies investigating the association between various social relationship factors and incident dementia in the general population. Relative risks (RRs) with 95% confidence intervals (CIs) were pooled using random-effects meta-analysis. Low social participation (RR: 1.41 (95% CI: 1.13-1.75)), less frequent social contact (RR: 1.57 (95% CI: 1.32-1.85)), and more loneliness (RR: 1.58 (95% CI: 1.19-2.09)) were statistically significant associated with incident dementia. The results of the association between social network size and dementia were inconsistent. No statistically significant association was found for low satisfaction with social network and the onset of dementia (RR: 1.25 (95% CI: 0.96-1.62). We conclude that social relationship factors that represent a lack of social interaction are associated with incident dementia. The strength of the associations between poor social interaction and incident dementia is comparable with other well-established risk factors for dementia, including low education attainment, physical inactivity, and late-life depression. Copyright © 2015 Elsevier B.V. All rights reserved.

PSpice Modeling of a Sandwich Piezoelectric Ceramic Ultrasonic Transducer in Longitudinal Vibration

PubMed Central

Wei, Xiaoyuan; Yang, Yuan; Yao, Wenqing; Zhang, Lei

2017-01-01

Sandwiched piezoelectric transducers are widely used, especially in high power applications. For more convenient analysis and design, a PSpice lossy model of sandwiched piezoelectric ultrasonic transducers in longitudinal vibration is proposed by means of the one-dimensional wave and transmission line theories. With the proposed model, the resonance and antiresonance frequencies are obtained, and it is shown that the simulations and measurements have good consistency. For the purpose of further verification the accuracy and application of the PSpice model, a pitch-catch setup and an experimental platform are built. They include two sandwiched piezoelectric ultrasonic transducers and two aluminum cylinders whose lengths are 20 mm and 100 mm respectively. Based on this pitch-catch setup, the impedance and transient analysis are performed. Compared with the measured results, it is shown that the simulated results have good consistency. In addition, the conclusion can be drawn that the optimal excitation frequency for the pitch-catch setup is not necessarily the resonance frequency of ultrasonic transducers, because the resonance frequency is obtained under no load. The proposed PSpice model of the sandwiched piezoelectric transducer is more conveniently applied to combine with other circuits such as driving circuits, filters, amplifiers, and so on. PMID:28973996

Adaptive quantification and longitudinal analysis of pulmonary emphysema with a hidden Markov measure field model.

PubMed

Hame, Yrjo; Angelini, Elsa D; Hoffman, Eric A; Barr, R Graham; Laine, Andrew F

2014-07-01

The extent of pulmonary emphysema is commonly estimated from CT scans by computing the proportional area of voxels below a predefined attenuation threshold. However, the reliability of this approach is limited by several factors that affect the CT intensity distributions in the lung. This work presents a novel method for emphysema quantification, based on parametric modeling of intensity distributions and a hidden Markov measure field model to segment emphysematous regions. The framework adapts to the characteristics of an image to ensure a robust quantification of emphysema under varying CT imaging protocols, and differences in parenchymal intensity distributions due to factors such as inspiration level. Compared to standard approaches, the presented model involves a larger number of parameters, most of which can be estimated from data, to handle the variability encountered in lung CT scans. The method was applied on a longitudinal data set with 87 subjects and a total of 365 scans acquired with varying imaging protocols. The resulting emphysema estimates had very high intra-subject correlation values. By reducing sensitivity to changes in imaging protocol, the method provides a more robust estimate than standard approaches. The generated emphysema delineations promise advantages for regional analysis of emphysema extent and progression.

Longitudinally Jointed Edge-wise Compression Honeycomb Composite Sandwich Coupon Testing and FE Analysis: Three Methods of Strain Measurement, and Comparison

NASA Technical Reports Server (NTRS)

Farrokh, Babak; AbdulRahim, Nur Aida; Segal, Ken; Fan, Terry; Jones, Justin; Hodges, Ken; Mashni, Noah; Garg, Naman; Sang, Alex; Gifford, Dawn;

Gene expression correlates of postinfective fatigue syndrome after infectious mononucleosis.

PubMed

Cameron, Barbara; Galbraith, Sally; Zhang, Yun; Davenport, Tracey; Vollmer-Conna, Ute; Wakefield, Denis; Hickie, Ian; Dunsmuir, William; Whistler, Toni; Vernon, Suzanne; Reeves, William C; Lloyd, Andrew R

2007-07-01

Infectious mononucleosis (IM) commonly triggers a protracted postinfective fatigue syndrome (PIFS) of unknown pathogenesis. Seven subjects with PIFS with 6 or more months of disabling symptoms and 8 matched control subjects who had recovered promptly from documented IM were studied. The expression of 30,000 genes was examined in the peripheral blood by microarray analysis in 65 longitudinally collected samples. Gene expression patterns associated with PIFS were sought by correlation with symptom factor scores. Differential expression of 733 genes was identified when samples collected early during the illness and at the late (recovered) time point were compared. Of these genes, 234 were found to be significantly correlated with the reported severity of the fatigue symptom factor, and 180 were found to be correlated with the musculoskeletal pain symptom factor. Validation by analysis of the longitudinal expression pattern revealed 35 genes for which changes in expression were consistent with the illness course. These genes included several that are involved in signal transduction pathways, metal ion binding, and ion channel activity. Gene expression correlates of the cardinal symptoms of PIFS after IM have been identified. Further studies of these gene products may help to elucidate the pathogenesis of PIFS.

Profiles of rural longitudinal integrated clerkship students: a descriptive study of six consecutive student cohorts *.

PubMed

Brooks, Kathleen D; Eley, Diann S; Zink, Therese

2014-02-01

Medical schools worldwide are challenged to address the rural primary care workforce shortage by creating community-engaged curricula to nurture student interest in rural practice. To examine the personal characteristics of six consecutive rural longitudinal integrated clerkship student cohorts to understand whom the programs attract and select and thus inform the development of such programs. A cross-sectional cohort design was used. Six cohorts (2007-2012) completed a survey on demographics and factors that influenced their choice of rural primary care. The Temperament and Character Inventory was used to measure personality. Analysis was mainly descriptive. Where appropriate univariate analysis compared variables between groups. Sample size was 205 with the majority female (61%), between 25 and 29 years (64%), single (60%) and lived longest in rural communities with populations less than 20,000 (60%). Rural lifestyle, background and desire to work in underserved areas were noted to impact rural medicine interest. Professional satisfaction, personal and professional goals and family needs had the highest impact on career decisions, and financial concerns lowest. The stability of students' personal characteristics across cohorts and the workforce outcomes of this program suggest the recruitment process successfully nurtures students who will fit well into future rural practice.

PSpice Modeling of a Sandwich Piezoelectric Ceramic Ultrasonic Transducer in Longitudinal Vibration.

PubMed

Wei, Xiaoyuan; Yang, Yuan; Yao, Wenqing; Zhang, Lei

2017-09-30

Sandwiched piezoelectric transducers are widely used, especially in high power applications. For more convenient analysis and design, a PSpice lossy model of sandwiched piezoelectric ultrasonic transducers in longitudinal vibration is proposed by means of the one-dimensional wave and transmission line theories. With the proposed model, the resonance and antiresonance frequencies are obtained, and it is shown that the simulations and measurements have good consistency. For the purpose of further verification the accuracy and application of the PSpice model, a pitch-catch setup and an experimental platform are built. They include two sandwiched piezoelectric ultrasonic transducers and two aluminum cylinders whose lengths are 20 mm and 100 mm respectively. Based on this pitch-catch setup, the impedance and transient analysis are performed. Compared with the measured results, it is shown that the simulated results have good consistency. In addition, the conclusion can be drawn that the optimal excitation frequency for the pitch-catch setup is not necessarily the resonance frequency of ultrasonic transducers, because the resonance frequency is obtained under no load. The proposed PSpice model of the sandwiched piezoelectric transducer is more conveniently applied to combine with other circuits such as driving circuits, filters, amplifiers, and so on.

Automated segmentation of mouse OCT volumes (ASiMOV): Validation & clinical study of a light damage model.

PubMed

Antony, Bhavna Josephine; Kim, Byung-Jin; Lang, Andrew; Carass, Aaron; Prince, Jerry L; Zack, Donald J

2017-01-01

The use of spectral-domain optical coherence tomography (SD-OCT) is becoming commonplace for the in vivo longitudinal study of murine models of ophthalmic disease. Longitudinal studies, however, generate large quantities of data, the manual analysis of which is very challenging due to the time-consuming nature of generating delineations. Thus, it is of importance that automated algorithms be developed to facilitate accurate and timely analysis of these large datasets. Furthermore, as the models target a variety of diseases, the associated structural changes can also be extremely disparate. For instance, in the light damage (LD) model, which is frequently used to study photoreceptor degeneration, the outer retina appears dramatically different from the normal retina. To address these concerns, we have developed a flexible graph-based algorithm for the automated segmentation of mouse OCT volumes (ASiMOV). This approach incorporates a machine-learning component that can be easily trained for different disease models. To validate ASiMOV, the automated results were compared to manual delineations obtained from three raters on healthy and BALB/cJ mice post LD. It was also used to study a longitudinal LD model, where five control and five LD mice were imaged at four timepoints post LD. The total retinal thickness and the outer retina (comprising the outer nuclear layer, and inner and outer segments of the photoreceptors) were unchanged the day after the LD, but subsequently thinned significantly (p < 0.01). The retinal nerve fiber-ganglion cell complex and the inner plexiform layers, however, remained unchanged for the duration of the study.

Automated segmentation of mouse OCT volumes (ASiMOV): Validation & clinical study of a light damage model

PubMed Central

Lang, Andrew; Carass, Aaron; Prince, Jerry L.; Zack, Donald J.

2017-01-01

The use of spectral-domain optical coherence tomography (SD-OCT) is becoming commonplace for the in vivo longitudinal study of murine models of ophthalmic disease. Longitudinal studies, however, generate large quantities of data, the manual analysis of which is very challenging due to the time-consuming nature of generating delineations. Thus, it is of importance that automated algorithms be developed to facilitate accurate and timely analysis of these large datasets. Furthermore, as the models target a variety of diseases, the associated structural changes can also be extremely disparate. For instance, in the light damage (LD) model, which is frequently used to study photoreceptor degeneration, the outer retina appears dramatically different from the normal retina. To address these concerns, we have developed a flexible graph-based algorithm for the automated segmentation of mouse OCT volumes (ASiMOV). This approach incorporates a machine-learning component that can be easily trained for different disease models. To validate ASiMOV, the automated results were compared to manual delineations obtained from three raters on healthy and BALB/cJ mice post LD. It was also used to study a longitudinal LD model, where five control and five LD mice were imaged at four timepoints post LD. The total retinal thickness and the outer retina (comprising the outer nuclear layer, and inner and outer segments of the photoreceptors) were unchanged the day after the LD, but subsequently thinned significantly (p < 0.01). The retinal nerve fiber-ganglion cell complex and the inner plexiform layers, however, remained unchanged for the duration of the study. PMID:28817571

A longitudinal analysis of the influence of the neighborhood built environment on walking for transportation: the RESIDE study.

PubMed

Knuiman, Matthew W; Christian, Hayley E; Divitini, Mark L; Foster, Sarah A; Bull, Fiona C; Badland, Hannah M; Giles-Corti, Billie

2014-09-01

The purpose of the present analysis was to use longitudinal data collected over 7 years (from 4 surveys) in the Residential Environments (RESIDE) Study (Perth, Australia, 2003-2012) to more carefully examine the relationship of neighborhood walkability and destination accessibility with walking for transportation that has been seen in many cross-sectional studies. We compared effect estimates from 3 types of logistic regression models: 2 that utilize all available data (a population marginal model and a subject-level mixed model) and a third subject-level conditional model that exclusively uses within-person longitudinal evidence. The results support the evidence that neighborhood walkability (especially land-use mix and street connectivity), local access to public transit stops, and variety in the types of local destinations are important determinants of walking for transportation. The similarity of subject-level effect estimates from logistic mixed models and those from conditional logistic models indicates that there is little or no bias from uncontrolled time-constant residential preference (self-selection) factors; however, confounding by uncontrolled time-varying factors, such as health status, remains a possibility. These findings provide policy makers and urban planners with further evidence that certain features of the built environment may be important in the design of neighborhoods to increase walking for transportation and meet the health needs of residents. © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Evaluation of HIV and highly active antiretroviral therapy on the natural history of human papillomavirus infection and cervical cytopathologic findings in HIV-positive and high-risk HIV-negative women.

PubMed

Blitz, Sandra; Baxter, Joanna; Raboud, Janet; Walmsley, Sharon; Rachlis, Anita; Smaill, Fiona; Ferenczy, Alex; Coutlée, François; Hankins, Catherine; Money, Deborah

2013-08-01

The Canadian Women's HIV Study (CWHS) enrolled human immunodeficiency virus (HIV)-positive and high-risk HIV-negative women in a longitudinal cohort. This analysis considered the effects of HIV and highly active antiretroviral therapy (HAART) on HPV persistence and cervical squamous intraepithelial lesions (SILs). Longitudinal cytopathologic and HPV DNA results were analyzed using multistate models. States of cervical SIL were defined as absent, present, and treatment; HPV states were defined as negative or positive. Demographic variables and markers of sexual activity were considered predictors. Results were calculated on the basis of transition probabilities and reported as hazard ratios (HRs). The CWHS followed 750 HIV-positive and 323 HIV-negative women during 1993-2002. A total of 467 and 456 women were included in the longitudinal cervical cytopathologic and HPV DNA analyses, respectively. HIV-positive women had increased prevalence (46.6% vs 28.7%; P < .0001), increased acquisition (HR, 2.3; P = .03), and decreased clearance (HR, 0.4; P < .001) of oncogenic HPV as compared to HIV-negative women. Oncogenic HPV infection predicted progression of cervical dysplasia from normal to abnormal SIL (HR, 2.8; P = .002). Among HIV-positive participants, HAART increased the likelihood of regression (from present to absent) of cervical SIL (HR, 3.3; P = .02) and increased the clearance of oncogenic HPV types other than HPV-16 or HPV-18 (HR, 2.2; P = .01). This analysis demonstrated beneficial effects of HAART on cervical SIL in HIV-positive women.

Rasch analysis and impact factor methods both yield valid and comparable measures of health status in interstitial lung disease.

PubMed

Patel, Amit S; Siegert, Richard J; Bajwah, Sabrina; Brignall, Kate; Gosker, Harry R; Moxham, John; Maher, Toby M; Renzoni, Elisabetta A; Wells, Athol U; Higginson, Irene J; Birring, Surinder S

2015-09-01

Rasch analysis has largely replaced impact factor methodology for developing health status measures. The aim of this study was to develop a health status questionnaire for patients with interstitial lung disease (ILD) using impact factor methodology and to compare its validity with that of another version developed using Rasch analysis. A preliminary 71-item questionnaire was developed and evaluated in 173 patients with ILD. Items were reduced by the impact factor method (King's Brief ILD questionnaire, KBILD-I) and Rasch analysis (KBILD-R). Both questionnaires were validated by assessing their relationship with forced vital capacity (FVC) and St Georges Respiratory Questionnaire (SGRQ) and by evaluating internal reliability, repeatability, and longitudinal responsiveness. The KBILD-R and KBILD-I comprised 15 items each. The content of eight items differed between the KBILD-R and KBILD-I. Internal and test-retest reliability was good for total scores of both questionnaires. There was a good relationship with SGRQ and moderate relationship with FVC for both questionnaires. Effect sizes were comparable. Both questionnaires discriminated patients with differing disease severity. Despite considerable differences in the content of retained items, both KBILD-R and KBILD-I questionnaires demonstrated acceptable measurement properties and performed comparably in a clinical setting. Copyright © 2015 Elsevier Inc. All rights reserved.

Tea Consumption and Mortality Among Oldest-Old Chinese

PubMed Central

Ruan, Rongping; Feng, Lei; Li, Jialiang; Ng, Tze-Pin; Zeng, Yi

2013-01-01

Objectives To investigate the association between tea consumption and mortality among oldest-old Chinese. Design Population-based longitudinal data from The Chinese Longitudinal Healthy Longevity Survey (CLHLS) was analyzed using Cox semi-parametric proportional hazard model. Setting 631 randomly selected counties and cities of China’s 22 provinces. Participants 9,093 old adults aged 80 and above who provided complete data at baseline survey (year 1998). Measurements Self-reported current frequency of tea drinking and past frequency around age 60 were ascertained at baseline survey, and follow-up survey was conducted respectively in years 2000, 2002 and 2005. Results Among oldest-old Chinese, tea consumption was associated with reduced risk of mortality after adjusting for demographic characteristics, socioeconomic status, health practices, and health status. Compared with non-tea drinkers, the adjusted hazard ratio (HR) was 0.90 (95% CI 0.84–0.96) for daily tea drinkers (at the baseline survey, 1998) and 1.00 (95% CI 1.01–1.07) for occasional tea drinkers respectively (P for linear trend=0.003). Similar results were found when tea drinking status around age 60 was used in analysis. Further analysis showed that compared to consistently infrequent tea drinkers, subjects who reported frequent tea drinking at both age 60 and at baseline survey had a 10% reduction in mortality (HR=0.90, 95%CI 0.84–0.97). Conclusion Tea consumption is associated reduced risk of mortality among oldest-old Chinese. PMID:24117374

Association between Breastfeeding and Childhood Obesity: Analysis of a Linked Longitudinal Study of Rural Appalachian Fifth-Grade Children.

PubMed

Umer, Amna; Hamilton, Candice; Britton, Cris M; Mullett, Martha D; John, Collin; Neal, William; Lilly, Christa L

2015-08-01

Although breastfeeding is associated with improving numerous health outcomes for the child, its role in reducing childhood obesity is contested. Despite this controversy, both the CDC and the US Department of Health and Human Services promote breastfeeding as one of the strategies for reducing childhood obesity. Rural Appalachia has one of the highest rates of childhood obesity and low rates of breastfeeding, compared to rest of the nation. The aim of this study was to examine the association between breastfeeding and childhood obesity at 11 years in the rural Appalachian state of West Virginia (WV). The study used linked data from two cross-sectional data sets to examine this relationship longitudinally in fifth-grade WV children. The main outcome variable was BMI adjusted percent (BMI%) and the main exposure was defined as occurrence of breastfeeding. Mean BMI% of children who were not breastfed was significantly higher, compared to children who were breastfed. The result of the multiple regression analysis showed that breastfeeding significantly predicted BMI% of children after controlling for maternal education, health insurance, family history of hypercholesterolemia and diabetes, child's asthma status, and birth weight of the infant. Our results are consistent with other studies that have shown a significant, but small, inverse association between breastfeeding and childhood obesity. Findings from this study suggest the need to improve breastfeeding rates in the rural Appalachian state of WV as one of the potential strategies to prevent obesity during childhood and adolescence.

Intimate Partner Violence and Welfare Participation: A Longitudinal Causal Analysis

ERIC Educational Resources Information Center

Cheng, Tyrone C.

2013-01-01

This longitudinal study examined the temporal-ordered causal relationship between intimate partner violence (IPV), five mental disorders (depression, generalized anxiety disorder, social phobia, panic attack, posttraumatic stress disorder [PTSD]), alcohol abuse/dependence, drug abuse/ dependence, treatment seeking (from physician, counselor, and…

High Risk for Schizophrenia from Conception to Young Adulthood.

ERIC Educational Resources Information Center

King, Suzanne

1990-01-01

Summarizes and critiques Asarnow's 1988 review of 24 longitudinal studies identifying environmental factors and individual vulnerability important to development of schizophrenia. Found Asarnow's analysis well conducted but summary should have addressed longitudinal research design. Concludes that identifiable behavior and family interaction…

Multivariate Longitudinal Analysis with Bivariate Correlation Test

PubMed Central

Adjakossa, Eric Houngla; Sadissou, Ibrahim; Hounkonnou, Mahouton Norbert; Nuel, Gregory

2016-01-01

In the context of multivariate multilevel data analysis, this paper focuses on the multivariate linear mixed-effects model, including all the correlations between the random effects when the dimensional residual terms are assumed uncorrelated. Using the EM algorithm, we suggest more general expressions of the model’s parameters estimators. These estimators can be used in the framework of the multivariate longitudinal data analysis as well as in the more general context of the analysis of multivariate multilevel data. By using a likelihood ratio test, we test the significance of the correlations between the random effects of two dependent variables of the model, in order to investigate whether or not it is useful to model these dependent variables jointly. Simulation studies are done to assess both the parameter recovery performance of the EM estimators and the power of the test. Using two empirical data sets which are of longitudinal multivariate type and multivariate multilevel type, respectively, the usefulness of the test is illustrated. PMID:27537692

Multivariate Longitudinal Analysis with Bivariate Correlation Test.

PubMed

Adjakossa, Eric Houngla; Sadissou, Ibrahim; Hounkonnou, Mahouton Norbert; Nuel, Gregory

2016-01-01

In the context of multivariate multilevel data analysis, this paper focuses on the multivariate linear mixed-effects model, including all the correlations between the random effects when the dimensional residual terms are assumed uncorrelated. Using the EM algorithm, we suggest more general expressions of the model's parameters estimators. These estimators can be used in the framework of the multivariate longitudinal data analysis as well as in the more general context of the analysis of multivariate multilevel data. By using a likelihood ratio test, we test the significance of the correlations between the random effects of two dependent variables of the model, in order to investigate whether or not it is useful to model these dependent variables jointly. Simulation studies are done to assess both the parameter recovery performance of the EM estimators and the power of the test. Using two empirical data sets which are of longitudinal multivariate type and multivariate multilevel type, respectively, the usefulness of the test is illustrated.

A Longitudinal Study of Individual and Organisational Learning

ERIC Educational Resources Information Center

Campbell, Timothy T.; Armstrong, Steven J.

2013-01-01

Purpose: The purpose of this paper is to empirically examine organisational learning (OL) and individual managerial learning and provide a comparative evaluation of the ability of each to generate organisational benefits. Design/methodology/approach: A theoretical model of organisational learning is developed which was then longitudinally tested…

Effect of Sm-Rich Phase on Corrosion Behavior of Hot-Extruded AZ31-1.5Sm Magnesium Alloy

NASA Astrophysics Data System (ADS)

Li, Xiao; Hu, Zhi; Yan, Hong; Wu, Xiaoquan; Xie, Hecong; Dong, Zhou

2018-05-01

The effects of Sm on the corrosion and microstructure behavior of hot-extruded AZ31 magnesium alloy were investigated by SEM, TEM, weight loss analysis, and electrochemical measurements. The results indicated that granular Al2Sm phase 4 μm in size in the hot-extruded AZ31 magnesium alloy modified with 1.5 wt.% Sm leads to significant grain refinement. The corrosion rate decreased from 15.98 × 10-4 to 11.19 × 10-4 g cm-2 h-1 in the transverse section and from 8.57 × 10-4 to 6.20 × 10-4 g cm-2 h-1 in the longitudinal section. Compared to the unmodified alloy, the corrosion potential of the Sm-modified alloy in the transverse and longitudinal sections increased by 98 and 62 mV, respectively, and the R ct value (charge transfer resistance) in the transverse and longitudinal sections of the modified alloy increased from 1764 and 1756 to 2928 and 2408 Ω cm2, respectively. The results showed that the corrosion resistance of hot-extruded AZ31 magnesium alloy was significantly improved by Sm addition due to the grain refinement, the decreased dislocation density, and the suppression of micro-galvanic corrosion caused by Al-Sm-(Mn) intermetallic compounds.

Thermal Conductivity Measurement of Anisotropic Biological Tissue In Vitro

NASA Astrophysics Data System (ADS)

Yue, Kai; Cheng, Liang; Yang, Lina; Jin, Bitao; Zhang, Xinxin

2017-06-01

The accurate determination of the thermal conductivity of biological tissues has implications on the success of cryosurgical/hyperthermia treatments. In light of the evident anisotropy in some biological tissues, a new modified stepwise transient method was proposed to simultaneously measure the transverse and longitudinal thermal conductivities of anisotropic biological tissues. The physical and mathematical models were established, and the analytical solution was derived. Sensitivity analysis and experimental simulation were performed to determine the feasibility and measurement accuracy of simultaneously measuring the transverse and longitudinal thermal conductivities. The experimental system was set up, and its measurement accuracy was verified by measuring the thermal conductivity of a reference standard material. The thermal conductivities of the pork tenderloin and bovine muscles were measured using the traditional 1D and proposed methods, respectively, at different temperatures. Results indicate that the thermal conductivities of the bovine muscle are lower than those of the pork tenderloin muscle, whereas the bovine muscle was determined to exhibit stronger anisotropy than the pork tenderloin muscle. Moreover, the longitudinal thermal conductivity is larger than the transverse thermal conductivity for the two tissues and all thermal conductivities increase with the increase in temperature. Compared with the traditional 1D method, results obtained by the proposed method are slightly higher although the relative deviation is below 5 %.

Accelerated telomere shortening: Tracking the lasting impact of early institutional care at the cellular level.

PubMed

Humphreys, Kathryn L; Esteves, Kyle; Zeanah, Charles H; Fox, Nathan A; Nelson, Charles A; Drury, Stacy S

2016-12-30

Studies examining the association between early adversity and longitudinal changes in telomere length within the same individual are rare, yet are likely to provide novel insight into the subsequent lasting effects of negative early experiences. We sought to examine the association between institutional care history and telomere shortening longitudinally across middle childhood and into adolescence. Buccal DNA was collected 2-4 times, between the ages of 6 and 15 years, in 79 children enrolled in the Bucharest Early Intervention Project (BEIP), a longitudinal study exploring the impact of early institutional rearing on child health and development. Children with a history of early institutional care (n=50) demonstrated significantly greater telomere shortening across middle childhood and adolescence compared to never institutionalized children (n=29). Among children with a history of institutional care, randomization to high quality foster care was not associated with differential telomere attrition across development. Cross-sectional analysis of children randomized to the care as usual group indicated shorter telomere length was associated with greater percent of the child's life spent in institutional care up to age 8. These results suggest that early adverse care from severe psychosocial deprivation may be embedded at the molecular genetic level through accelerated telomere shortening. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Accelerated telomere shortening: Tracking the lasting impact of early institutional care at the cellular level

PubMed Central

Humphreys, Kathryn L.; Esteves, Kyle; Zeanah, Charles H; Fox, Nathan A; Nelson, Charles A.; Drury, Stacy S.

2016-01-01

Studies examining the association between early adversity and longitudinal changes in telomere length within the same individual are rare, yet are likely to provide novel insight into the subsequent lasting effects of negative early experiences. We sought to examine the association between institutional care history and telomere shortening longitudinally across middle childhood and into adolescence. Buccal DNA was collected 2 to 4 times, between the ages of 6 and 15 years, in 79 children enrolled in the Bucharest Early Intervention Project (BEIP), a longitudinal study exploring the impact of early institutional rearing on child health and development. Children with a history of early institutional care (n=50) demonstrated significantly greater telomere shortening across middle childhood and adolescence compared to never institutionalized children (n=29). Among children with a history of institutional care, randomization to high quality foster care was not associated with differential telomere attrition across development. Cross-sectional analysis of children randomized to the care as usual group indicated shorter telomere length was associated with greater percent of the child’s life spent in institutional care up to age 8. These results suggest that early adverse care from severe psychosocial deprivation may be embedded at the molecular genetic level through accelerated telomere shortening. PMID:27677058

The longitudinal equations of motion of a tilt prop/rotor aircraft including the effects of wing and prop/rotor blade flexibility

NASA Technical Reports Server (NTRS)

Curtiss, H. C., Jr.

1976-01-01

The equations of motion for the longitudinal dynamics of a tilting prop/rotor aircraft are developed. The analysis represents an extension of the equations of motion. The effects of the longitudinal degrees of freedom of the body (pitch, heave and horizontal velocity) are included. The results of body freedom can be added to the equations of motion for the flexible wing propeller combination.

Proton Pump Inhibitor Initiation and Withdrawal affects Gut Microbiota and Readmission Risk in Cirrhosis.

PubMed

Bajaj, Jasmohan S; Acharya, Chathur; Fagan, Andrew; White, Melanie B; Gavis, Edith; Heuman, Douglas M; Hylemon, Phillip B; Fuchs, Michael; Puri, Puneet; Schubert, Mitchell L; Sanyal, Arun J; Sterling, Richard K; Stravitz, R Todd; Siddiqui, Mohammad S; Luketic, Velimir; Lee, Hannah; Sikaroodi, Masoumeh; Gillevet, Patrick M

2018-06-06

Cirrhosis is associated with gut microbial dysbiosis, high readmissions and proton pump inhibitor (PPI) overuse, which could be inter-linked. Our aim was to determine the effect of PPI use, initiation and withdrawl on gut microbiota and readmissions in cirrhosis. Four cohorts were enrolled. Readmissions study: Cirrhotic inpatients were followed throughout the hospitalization and 30/90-days post-discharge. PPI initiation, withdrawal/continuation patterns were analyzed between those with/without readmissions. Cross-sectional microbiota study: Cirrhotic outpatients and controls underwent stool microbiota analysis. Beneficial autochthonous and oral-origin taxa analysis vis-à-vis PPI use was performed. Longitudinal studies: Two cohorts of decompensated cirrhotic outpatients were enrolled. Patients on chronic unindicated PPI use were withdrawn for 14 days. Patients not on PPI were started on omeprazole for 14 days. Microbial analysis for oral-origin taxa was performed pre/post-intervention. Readmissions study: 343 inpatients (151 on admission PPI) were enrolled. 21 were withdrawn and 45 were initiated on PPI resulting in a PPI use increase of 21%. PPIs were associated with higher 30 (p = 0.002) and 90-day readmissions (p = 0.008) independent of comorbidities, medications, MELD and age. Cross-sectional microbiota: 137 cirrhotics (59 on PPI) and 45 controls (17 on PPI) were included. PPI users regardless of cirrhosis had higher oral-origin microbiota while cirrhotics on PPI had lower autochthonous taxa compared to the rest. Longitudinal studies: Fifteen decompensated cirrhotics tolerated omeprazole initiation with an increase in oral-origin microbial taxa compared to baseline. PPIs were withdrawn from an additional 15 outpatients, which resulted in a significant reduction of oral-origin taxa compared to baseline. PPIs modulate readmission risk and microbiota composition in cirrhosis, which responds to withdrawal. The systematic withdrawal and judicious use of PPIs is needed from a clinical and microbiological perspective in decompensated cirrhosis.

Social learning in a longitudinal integrated clinical placement.

PubMed

Roberts, Chris; Daly, Michele; Held, Fabian; Lyle, David

2017-10-01

Recent research has demonstrated that longitudinal integrated placements (LICs) are an alternative mode of clinical education to traditional placements. Extended student engagement in community settings provide the advantages of educational continuity as well as increased service provision in underserved areas. Developing and maintaining LICs require a differing approach to student learning than that for traditional placements. There has been little theoretically informed empirical research that has offered explanations of which are the important factors that promote student learning in LICs and the relationships between those factors. We explored the relationship between student learning, student perceptions of preparedness for practice and student engagement, in the context of a rural LIC. We used a sequential qualitative design employing thematic, comparative and relational analysis of data from student interviews (n = 18) to understand possible processes and mechanisms of student learning in the LIC. Through the theoretical lens of social learning systems, we identified two major themes; connectivity and preparedness for practice. Connectivity described engagement and relationship building by students, across formal and informal learning experiences, interprofessional interactions, social interactions with colleagues, interaction with patients outside of the clinical setting, and the extent of integration in the wider community. Preparedness for practice, reflected students' perceptions of having sufficient depth in clinical skills, personal and professional development, cultural awareness and understanding of the health system, to work in that system. A comparative analysis compared the nature and variation of learning across students. In a relational analysis, there was a positive association between connectivity and preparedness for practice. Connectivity is a powerful enabler of students' agentic engagement, collaboration, and learning within an LIC. It is related to student perceptions of preparedness for practice. These findings provide insight for institutions wishing to develop similar programmes, by encouraging health professional educators to consider all of the potential elements of the placements, which most promote connectivity.

An Overview of Longitudinal Data Analysis Methods for Neurological Research

PubMed Central

Locascio, Joseph J.; Atri, Alireza

2011-01-01

The purpose of this article is to provide a concise, broad and readily accessible overview of longitudinal data analysis methods, aimed to be a practical guide for clinical investigators in neurology. In general, we advise that older, traditional methods, including (1) simple regression of the dependent variable on a time measure, (2) analyzing a single summary subject level number that indexes changes for each subject and (3) a general linear model approach with a fixed-subject effect, should be reserved for quick, simple or preliminary analyses. We advocate the general use of mixed-random and fixed-effect regression models for analyses of most longitudinal clinical studies. Under restrictive situations or to provide validation, we recommend: (1) repeated-measure analysis of covariance (ANCOVA), (2) ANCOVA for two time points, (3) generalized estimating equations and (4) latent growth curve/structural equation models. PMID:22203825

Age, Gender, and Race-Based Coronary Artery Calcium Score Percentiles in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

PubMed

Pereira, Alexandre C; Gomez, Luz M; Bittencourt, Marcio Sommer; Staniak, Henrique Lane; Sharovsky, Rodolfo; Foppa, Murilo; Blaha, Michael J; Bensenor, Isabela M; Lotufo, Paulo A

2016-06-01

Coronary artery calcium (CAC) has been demonstrated to independently predict the risk of cardiovascular events and all-cause mortality, especially among White populations. Although the population distribution of CAC has been determined for several White populations, the distribution in ethnically admixed groups has not been well established. The CAC distribution, stratified for age, gender and race, is similar to the previously described distribution in the MESA study. The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) is a prospective cohort study designed to investigate subclinical cardiovascular disease in 6 different centers of Brazil. Similar to previous studies, individuals with self-reported coronary or cerebrovascular disease and those treated for diabetes mellitus were excluded from analysis. Percentiles of CAC distribution were estimated with nonparametric techniques. The analysis included 3616 individuals (54% female; mean age, 50 years). As expected, CAC prevalence and burden were steadily higher with increasing age, as well as increased in men and in White individuals. Our results revealed that for a given CAC score, the ELSA-derived CAC percentile would be lower in men compared with the Multi-Ethnic Study of Atherosclerosis (MESA) and would be higher in women compared with MESA. In our sample of the Brazilian population, we observed significant differences in CAC by sex, age, and race. Adjusted for age and sex, low-risk individuals from the Brazilian population present with significantly lower CAC prevalence and burden compared with other low-risk individuals from other worldwide populations. Using US-derived percentiles in Brazilian individuals may lead to overestimating relative CAC burden in men and underestimating relative CAC burden in women. © 2016 Wiley Periodicals, Inc.

Prostate cancer in Germany among migrants from the Former Soviet Union

PubMed Central

Winkler, Volker; Holleczek, Bernd; Stegmaier, Christa; Becher, Heiko

2012-01-01

Background In Germany, prostate cancer is the leading cause of cancer and the third leading cause of death from cancer in males. We investigate prostate cancer in Gernmany among migrants from the Former Soviet Union (FSU) and compare them to indigenous German population with regard to prostate cancer incidence, mortality and longitudinal effects. Methods Data were obtained from two migrant cohorts residing in the federal states of North Rhine Westphalia (n=34,393) and Saarland (n=18,619). Vital status was ascertained through local population registries. Causes of death were obtained from the federal statistical office or from local health authorities. Cancer incidence of the Saarland cohort was derived from the Saarland Cancer Registry using record linkage. Results From 1990 to 2005 we observed 3360 deaths of which 28 were due to prostate cancer. In the Saarland cohort 35 men were diagnosed with prostate cancer during the respective period. Migrants had lower prostate cancer incidence (SIR 0.74 (95% CI: 0.52–1.03)) and mortality (SMR 0.57 (95% CI: 0.38–0.83)) compared to the German population. Multivariate analysis showed a strong age effect on incidence meaning young migrants (below age 60) were diagnosed significantly more often with prostate cancer compared to Germans of the same age. However, mortality did not show any effects. Discussion Lower prostate cancer mortality and incidence among migrants may reflect an ongoing situation in the FSU. Additionally, longitudinal analysis did not reveal convergence of migrant prostate cancer to German rates as expected from lifestyle driven cancer sites. Therefore, our results support the hypothesis of a genetic effect on prostate cancer risk. PMID:22229025

Longitudinal effect of eteplirsen versus historical control on ambulation in Duchenne muscular dystrophy

PubMed Central

Goemans, Nathalie; Lowes, Linda P.; Alfano, Lindsay N.; Berry, Katherine; Shao, James; Kaye, Edward M.; Mercuri, Eugenio; Hamid, Hoda Abdel; Byrne, Barry J.; Connolly, Anne M.; Dracker, Robert A.; Matthew Frank, L.; Heydemann, Peter T.; O'Brien, Kevin C.; Sparks, Susan E.; Specht, Linda A.; Rodino‐Klapac, Louise; Sahenk, Zarife; Al‐Zaidy, Samiah; Cripe, Linda H.; Lewis, Sarah; M, Pane; E, Mazzone; S, Messina; GL, Vita; Bertini, D Amico A; Casimiro, Berardinelli A; Y, Torrente; F, Magri; GP, Comi; G, Baranello; T, Mongini; A, Pini; R, Battini; E, Pegoraro; C, Bruno; L, Politano; S, Previtali

2016-01-01

Objective To continue evaluation of the long‐term efficacy and safety of eteplirsen, a phosphorodiamidate morpholino oligomer designed to skip DMD exon 51 in patients with Duchenne muscular dystrophy (DMD). Three‐year progression of eteplirsen‐treated patients was compared to matched historical controls (HC). Methods Ambulatory DMD patients who were ≥7 years old and amenable to exon 51 skipping were randomized to eteplirsen (30/50mg/kg) or placebo for 24 weeks. Thereafter, all received eteplirsen on an open‐label basis. The primary functional assessment in this study was the 6‐Minute Walk Test (6MWT). Respiratory muscle function was assessed by pulmonary function testing (PFT). Longitudinal natural history data were used for comparative analysis of 6MWT performance at baseline and months 12, 24, and 36. Patients were matched to the eteplirsen group based on age, corticosteroid use, and genotype. Results At 36 months, eteplirsen‐treated patients (n = 12) demonstrated a statistically significant advantage of 151m (p < 0.01) on 6MWT and experienced a lower incidence of loss of ambulation in comparison to matched HC (n = 13) amenable to exon 51 skipping. PFT results remained relatively stable in eteplirsen‐treated patients. Eteplirsen was well tolerated. Analysis of HC confirmed the previously observed change in disease trajectory at age 7 years, and more severe progression was observed in patients with mutations amenable to exon skipping than in those not amenable. The subset of patients amenable to exon 51 skipping showed a more severe disease course than those amenable to any exon skipping. Interpretation Over 3 years of follow‐up, eteplirsen‐treated patients showed a slower rate of decline in ambulation assessed by 6MWT compared to untreated matched HC. Ann Neurol 2016;79:257–271 PMID:26573217

Longitudinal and bulk viscosities of Lennard-Jones fluids

NASA Astrophysics Data System (ADS)

Tankeshwar, K.; Pathak, K. N.; Ranganathan, S.

1996-12-01

Expressions for the longitudinal and bulk viscosities have been derived using Green Kubo formulae involving the time integral of the longitudinal and bulk stress autocorrelation functions. The time evolution of stress autocorrelation functions are determined using the Mori formalism and a memory function which is obtained from the Mori equation of motion. The memory function is of hyperbolic secant form and involves two parameters which are related to the microscopic sum rules of the respective autocorrelation function. We have derived expressions for the zeroth-, second-and fourth- order sum rules of the longitudinal and bulk stress autocorrelation functions. These involve static correlation functions up to four particles. The final expressions for these have been put in a form suitable for numerical calculations using low- order decoupling approximations. The numerical results have been obtained for the sum rules of longitudinal and bulk stress autocorrelation functions. These have been used to calculate the longitudinal and bulk viscosities and time evolution of the longitudinal stress autocorrelation function of the Lennard-Jones fluids over wide ranges of densities and temperatures. We have compared our results with the available computer simulation data and found reasonable agreement.

Early Clinical Features of Dengue Virus Infection in Nicaraguan Children: A Longitudinal Analysis

PubMed Central

Biswas, Hope H.; Ortega, Oscar; Gordon, Aubree; Standish, Katherine; Balmaseda, Angel; Kuan, Guillermina; Harris, Eva

2012-01-01

Background Tens of millions of dengue cases and approximately 500,000 life-threatening complications occur annually. New tools are needed to distinguish dengue from other febrile illnesses. In addition, the natural history of pediatric dengue early in illness in a community-based setting has not been well-defined. Methods Data from the multi-year, ongoing Pediatric Dengue Cohort Study of approximately 3,800 children aged 2–14 years in Managua, Nicaragua, were used to examine the frequency of clinical signs and symptoms by day of illness and to generate models for the association of signs and symptoms during the early phase of illness and over the entire course of illness with testing dengue-positive. Odds ratios (ORs) and 95% confidence intervals were calculated using generalized estimating equations (GEE) for repeated measures, adjusting for age and gender. Results One-fourth of children who tested dengue-positive did not meet the WHO case definition for suspected dengue. The frequency of signs and symptoms varied by day of illness, dengue status, and disease severity. Multivariable GEE models showed increased odds of testing dengue-positive associated with fever, headache, retro-orbital pain, myalgia, arthralgia, rash, petechiae, positive tourniquet test, vomiting, leukopenia, platelets ≤150,000 cells/mL, poor capillary refill, cold extremities and hypotension. Estimated ORs tended to be higher for signs and symptoms over the course of illness compared to the early phase of illness. Conclusions Day-by-day analysis of clinical signs and symptoms together with longitudinal statistical analysis showed significant associations with testing dengue-positive and important differences during the early phase of illness compared to the entire course of illness. These findings stress the importance of considering day of illness when developing prediction algorithms for real-time clinical management. PMID:22413033

Noninvasive PK11195-PET Image Analysis Techniques Can Detect Abnormal Cerebral Microglial Activation in Parkinson's Disease.

PubMed

Kang, Yeona; Mozley, P David; Verma, Ajay; Schlyer, David; Henchcliffe, Claire; Gauthier, Susan A; Chiao, Ping C; He, Bin; Nikolopoulou, Anastasia; Logan, Jean; Sullivan, Jenna M; Pryor, Kane O; Hesterman, Jacob; Kothari, Paresh J; Vallabhajosula, Shankar

2018-05-04

Neuroinflammation has been implicated in the pathophysiology of Parkinson's disease (PD), which might be influenced by successful neuroprotective drugs. The uptake of [ 11 C](R)-PK11195 (PK) is often considered to be a proxy for neuroinflammation, and can be quantified using the Logan graphical method with an image-derived blood input function, or the Logan reference tissue model using automated reference region extraction. The purposes of this study were (1) to assess whether these noninvasive image analysis methods can discriminate between patients with PD and healthy volunteers (HVs), and (2) to establish the effect size that would be required to distinguish true drug-induced changes from system variance in longitudinal trials. The sample consisted of 20 participants with PD and 19 HVs. Two independent teams analyzed the data to compare the volume of distribution calculated using image-derived input functions (IDIFs), and binding potentials calculated using the Logan reference region model. With all methods, the higher signal-to-background in patients resulted in lower variability and better repeatability than in controls. We were able to use noninvasive techniques showing significantly increased uptake of PK in multiple brain regions of participants with PD compared to HVs. Although not necessarily reflecting absolute values, these noninvasive image analysis methods can discriminate between PD patients and HVs. We see a difference of 24% in the substantia nigra between PD and HV with a repeatability coefficient of 13%, showing that it will be possible to estimate responses in longitudinal, within subject trials of novel neuroprotective drugs. © 2018 The Authors. Journal of Neuroimaging published by Wiley Periodicals, Inc. on behalf of American Society of Neuroimaging.

Longitudinal volumetric and 2D assessment of cerebellar atrophy in a large cohort of children with phosphomannomutase deficiency (PMM2-CDG).

PubMed

de Diego, Víctor; Martínez-Monseny, Antonio F; Muchart, Jordi; Cuadras, Daniel; Montero, Raquel; Artuch, Rafael; Pérez-Cerdá, Celia; Pérez, Belén; Pérez-Dueñas, Belén; Poretti, Andrea; Serrano, Mercedes

2017-09-01

We aim to delineate the progression of cerebellar atrophy (the primary neuroimaging finding) in children with phosphomannomutase-deficiency (PMM2-CDG) by analyzing longitudinal MRI studies and performing cerebellar volumetric analysis and a 2D cerebellar measurement. Statistical analysis was used to compare MRI measurements [midsagittal vermis relative diameter (MVRD) and volume] of children with PMM2-CDG and sex- and age-matched controls, and to determine the rate of progression of cerebellar atrophy at different ages. Fifty MRI studies of 33 PMM2-CDG patients were used for 2D evaluation, and 19 MRI studies were available for volumetric analysis. Results from a linear regression model showed that patients have a significantly lower MVRD and cerebellar volume compared to controls (p < 0.001 and p < 0.001 respectively). There was a significant negative correlation between age and MVRD for patients (p = 0.014). The rate of cerebellar atrophy measured by the loss of MVRD and cerebellar volume per year was higher at early ages (r = -0.578, p = 0.012 and r = -0.323, p = 0.48 respectively), particularly in patients under 11 years (p = 0.004). There was a significant positive correlation between MVRD and cerebellar volume in PMM2-CDG patients (r = 0.669, p = 0.001). Our study quantifies a progression of cerebellar atrophy in PMM2-CDG patients, particularly during the first decade of life, and suggests a simple and reliable measure, the MVRD, to monitor cerebellar atrophy. Quantitative measurement of MVRD and cerebellar volume are essential for correlation with phenotype and outcome, natural follow-up, and monitoring in view of potential therapies in children with PMM2-CDG.

Comparison of a single-channel EEG sleep study to polysomnography

PubMed Central

Lucey, Brendan P.; McLeland, Jennifer S.; Toedebusch, Cristina D.; Boyd, Jill; Morris, John C.; Landsness, Eric C.; Yamada, Kelvin; Holtzman, David M.

2016-01-01

Summary An accurate home sleep study to assess electroencephalography (EEG)-based sleep stages and EEG power would be advantageous for both clinical and research purposes, such as for longitudinal studies measuring changes in sleep stages over time. The purpose of this study was to compare sleep scoring of a single-channel EEG recorded simultaneously on the forehead against attended polysomnography. Participants were recruited from both a clinical sleep center and a longitudinal research study investigating cognitively-normal aging and Alzheimer's disease. Analysis for overall epoch-by-epoch agreement found strong and substantial agreement between the single-channel EEG compared to polysomnography (kappa=0.67). Slow wave activity in the frontal regions was also similar when comparing the single-channel EEG device to polysomnography. As expected, stage N1 showed poor agreement (sensitivity 0.2) due to lack of occipital electrodes. Other sleep parameters such as sleep latency and REM onset latency had decreased agreement. Participants with disrupted sleep consolidation, such as from obstructive sleep apnea, also had poor agreement. We suspect that disagreement in sleep parameters between the single-channel EEG and polysomnography is partially due to altered waveform morphology and/or poorer signal quality in the single-channel derivation. Our results show that single-channel EEG provides comparable results to polysomnography in assessing REM, combined stages N2 and N3 sleep, and several other parameters including frontal slow wave activity. The data establish that single-channel EEG can be a useful research tool. PMID:27252090

A Longitudinal Study on Learner Career Advancement in MOOCs

ERIC Educational Resources Information Center

Wang, Yuan; Paquette, Luc; Baker, Ryan

2014-01-01

In this paper, we present progress towards a longitudinal study of the post-course career advancement of MOOC learners. We present initial results and analysis plans for how to link this to in-course behaviour, towards better understanding the goals of all MOOC learners.

Sex Stratification, Technology and Organizational Change: A Longitudinal Case Study of AT&T.

ERIC Educational Resources Information Center

Hacker, Sally L.

1979-01-01

Recent technological displacement in AT&T affected workers differentially by sex. This longitudinal analysis of changes in AT&T's organizational structure addresses the tendency of organizational research to ignore the variable of sex in the study of change. (Author/RLV)

Dynamic longitudinal investigation of individual nerve endings in the skin of anesthetized mice using in vivo two-photon microscopy

NASA Astrophysics Data System (ADS)

Yuryev, Mikhail; Khiroug, Leonard

2012-04-01

Visualization of individual cutaneous nerve endings has previously relied on laborious procedures of tissue excision, fixation, sectioning and staining for light or electron microscopy. We present a method for non-invasive, longitudinal two-photon microscopy of single nerve endings within the skin of anesthetized transgenic mice. Besides excellent signal-to-background ratio and nanometer-scale spatial resolution, this method offers time-lapse ``movies'' of pathophysiological changes in nerve fine structure over minutes, hours, days or weeks. Structure of keratinocytes and dermal matrix is visualized simultaneously with nerve endings, providing clear landmarks for longitudinal analysis. We further demonstrate feasibility of dissecting individual nerve fibers with infra-red laser and monitoring their degradation and regeneration. In summary, our excision-free optical biopsy technique is ideal for longitudinal microscopic analysis of animal skin and skin innervations in vivo and can be applied widely in preclinical models of chronic pain, allergies, skin cancers and a variety of dermatological disorders.

Entrance and Exit CSR Impedance for Non-Ultrarelativistic Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Rui; Tsai, Cheng Ying

2017-05-01

For a high-brightness electron beam being transported through beamlines involving bending systems, the coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) interaction could often cause microbunching instability. The semi-analytical Vlasov solver for microbunching gain* depends on the impedances for the relevant collective effects. The existing results for CSR impedances are usually obtained for the ultrarelativistic limit. To extend the microbunching analysis to cases of low energies, such as the case of an ERL merger, or to density modulations at extremely small wavelength, it is necessary to extend the impedance analysis to the non-ultrarelativistic regime. In this study, we presentmore » the impedance analysis for the transient CSR interaction in the non-ultrarelativistic regime, for transients including both entrance to and exit from a magnetic dipole. These impedance results will be compared to their ultra-relativistic counterparts**, and the corresponding wakefield obtained from the impedance for low-energy beams will be compared with the existing results of transient CSR wakefield for general beam energies***.« less

Practical Formulations of the Latent Growth Item Response Model

ERIC Educational Resources Information Center

McGuire, Leah Walker

2010-01-01

Growth modeling using longitudinal data seems to be a promising direction for improving the methodology associated with the accountability movement. Longitudinal modeling requires that the measurements of ability are comparable over time and on the same scale. One way to create the vertical scale is through concurrent estimation with…

Longitudinal Examination of Adaptive Behavior in Autism Spectrum Disorders: Influence of Executive Function

ERIC Educational Resources Information Center

Pugliese, Cara E.; Anthony, Laura Gutermuth; Strang, John F.; Dudley, Katerina; Wallace, Gregory L.; Naiman, Daniel Q.; Kenworthy, Lauren

2016-01-01

This study characterizes longitudinal change in adaptive behavior in 64 children and adolescents with autism spectrum disorder (ASD) without intellectual disability evaluated on multiple occasions, and examines whether prior estimate of executive function (EF) problems predicts future adaptive behavior scores. Compared to standardized estimates…

Trends in Financial Satisfaction: Does Poverty Make a Difference?

ERIC Educational Resources Information Center

Hsieh, Chang-Ming

2002-01-01

Gerontological studies on financial satisfaction have been limited by the dearth of longitudinal research and the lack of research that includes the concept of poverty. In order to bridge these gaps, this longitudinal study examines and compares the intracohort and intercohort effects on financial satisfaction trends by poverty status among…

Rethinking the longitudinal stream temperature paradigm: region-wide comparison of thermal infrared imagery reveals unexpected complexity of river temperatures

EPA Science Inventory

We used an extensive dataset of remotely sensed summertime river temperature to compare longitudinal profiles (temperature versus distance) for 54 rivers in the Pacific Northwest. We evaluated (1) how often profiles fit theoretical expectations of asymptotic downstream warming, a...

Comparing Children with ASD and Their Peers' Growth in Print Knowledge.

PubMed

Dynia, Jaclyn M; Brock, Matthew E; Logan, Jessica A R; Justice, Laura M; Kaderavek, Joan N

2016-07-01

Many children with autism spectrum disorder (ASD) struggle with reading. An increased focus on emergent literacy skills-particularly print knowledge-might improve later reading outcomes. We analyzed longitudinal measures of print knowledge (i.e., alphabet knowledge and print-concept knowledge) for 35 preschoolers with ASD relative to a sample of 35 typically developing peers. Through multilevel growth curve analysis, we found that relative to their peers, children with ASD had comparable alphabet knowledge, lower print-concept knowledge, and acquired both skills at a similar rate. These findings suggest that children with ASD are unlikely to acquire print-concept knowledge commensurate to their peers without an increased emphasis on high-quality instruction that targets this skill.

A multicohort, longitudinal study of cerebellar development in attention deficit hyperactivity disorder.

PubMed

Shaw, Philip; Ishii-Takahashi, Ayaka; Park, Min Tae; Devenyi, Gabriel A; Zibman, Chava; Kasparek, Steven; Sudre, Gustavo; Mangalmurti, Aman; Hoogman, Martine; Tiemeier, Henning; von Polier, Georg; Shook, Devon; Muetzel, Ryan; Chakravarty, M Mallar; Konrad, Kerstin; Durston, Sarah; White, Tonya

2018-04-25

The cerebellum supports many cognitive functions disrupted in attention deficit hyperactivity disorder (ADHD). Prior neuroanatomic studies have been often limited by small sample sizes, inconsistent findings, and a reliance on cross-sectional data, limiting inferences about cerebellar development. Here, we conduct a multicohort study using longitudinal data, to characterize cerebellar development. Growth trajectories of the cerebellar vermis, hemispheres and white matter were estimated using piecewise linear regression from 1,656 youth; of whom 63% had longitudinal data, totaling 2,914 scans. Four cohorts participated, all contained childhood data (age 4-12 years); two had adolescent data (12-25 years). Growth parameters were combined using random-effects meta-analysis. Diagnostic differences in growth were confined to the corpus medullare (cerebellar white matter). Here, the ADHD group showed slower growth in early childhood compared to the typically developing group (left corpus medullare z = 2.49, p = .01; right z = 2.03, p = .04). This reversed in late childhood, with faster growth in ADHD in the left corpus medullare (z = 2.06, p = .04). Findings held when gender, intelligence, comorbidity, and psychostimulant medication were considered. Across four independent cohorts, containing predominately longitudinal data, we found diagnostic differences in the growth of cerebellar white matter. In ADHD, slower white matter growth in early childhood was followed by faster growth in late childhood. The findings are consistent with the concept of ADHD as a disorder of the brain's structural connections, formed partly by developing cortico-cerebellar white matter tracts. © 2018 Association for Child and Adolescent Mental Health.