Evaluating 35 Methods to Generate Structural Connectomes Using Pairwise Classification

There is no consensus on how to construct structural brain networks from diffusion MRI. How variations in pre-processing steps affect network reliability and its ability to distinguish subjects remains opaque. In this work, we address this issue by comparing 35 structural connectome-building pipelines. We vary diffusion reconstruction models, tractography algorithms and parcellations. Next, we classify structural connectome pairs as either belonging to the same individual or not. Connectome weights and eight topological derivative measures form our feature set. For experiments, we use three test-retest datasets from the Consortium for Reliability and Reproducibility (CoRR) comprised of a total of 105 individuals. We also compare pairwise classification results to a commonly used parametric test-retest measure, Intraclass Correlation Coefficient (ICC).Comment: Accepted for MICCAI 2017, 8 pages, 3 figure

Affective variability in depression:Revisiting the inertia-instability paradox

How can depression be associated with both instability and inertia of affect? Koval et al. (2013, Emotion, 13, 1132) showed that this paradox can be solved by accounting for the statistical overlap between measures of affect dynamics. Nevertheless, these measures are still often studied in isolation. The present study is a replication of the Koval et al. study. We used experience sampling data (three times a day, 1 month) of 462 participants from the general population and a subsample thereof (N = 100) selected to reflect a uniform range of depressive symptoms. Dynamics measures were calculated for momentary negative affect scores. When adjusting for the overlap among affect dynamics measures, depression was associated with 'dispersion' (SD) but not 'instability' (RMSSD) or 'inertia' (AR) of negative affect. The association between dispersion and depression became non-significant when mean levels of negative affect were adjusted for. These findings substantiate the evidence that the presumed association between depression and instability is largely accounted for by the SD, while the association between dispersion and depression may largely reflect mean levels of affect. Depression may thus not be related to higher instability per se, which would be in line with theories on the adaptive function of moment-to-moment fluctuations in affect

Why does the ethnic and socio-economic composition of schools influence math achievement? The role of sense of futility and futility culture

Although a number of studies in many countries have investigated the impact of the ethnic and socio-economic composition of schools on academic performance, few studies have analyzed in detail how and why compositional features matter. This article presents an examination of whether pupils’ sense of futility and schools’ futility culture account for the impact of ethnic and socio-economic status (SES) composition of schools on the academic achievement of their pupils. Multilevel analyses of data based on a survey of 2,845 pupils (aged 10–12 years) in 68 Flemish primary schools revealed that higher proportions of immigrant and working-class pupils in a school is associated with lower levels of math achievement in both immigrant and native Belgian pupils. However, by analyzing at a deeper level, by taking control variables into account, our study found that the ethnic composition of the school no longer had a significant effect on pupils’ achievement, while the SES composition still did. Most importantly, our results indicated that the remaining impact of SES composition can be explained by pupils’ sense of futility and schools’ futility culture. The implications of these findings for educational policy are discussed

Resource use data by patient report or hospital records: Do they agree?

Background: Economic evaluations alongside clinical trials are becoming increasingly common. Cost data are often collected through the use of postal questionnaires; however, the accuracy of this method is uncertain. We compared postal questionnaires with hospital records for collecting data on physiotherapy service use. Methods: As part of a randomised trial of orthopaedic medicine compared with orthopaedic surgery we collected physiotherapy use data on a group of patients from retrospective postal questionnaires and from hospital records. Results: 315 patients were referred for physiotherapy. Hospital data on attendances was available for 30% (n = 96), compared with 48% (n = 150) of patients completing questionnaire data (95% Cl for difference = 10% to 24%); 19% (n = 59) had data available from both sources. The two methods produced an intraclass correlation coefficient of 0.54 (95% Cl 0.31 to 0.70). However, the two methods produced significantly different estimates of resource use with patient self report recalling a mean of 1.3 extra visits (95% Cl 0.4 to 2.2) compared with hospital records. Conclusions: Using questionnaires in this study produced data on a greater number of patients compared with examination of hospital records. However, the two data sources did differ in the quantity of physiotherapy used and this should be taken into account in any analysi

CVM studies on the atomic ordering in complex perovskite alloys

The atomic ordering in complex perovskite alloys is investigated by the cluster variation method (CVM). For the 1/3\{111\}-type ordered structure, the order-disorder phase transition is the first order, and the order parameter of the 1:2 complex perovskite reaches its maximum near x=0.25. For the 1/2\{111\}-type ordered structure, the ordering transition is the second order. Phase diagrams for both ordered structures are obtained. The order-disorder line obeys the linear law.Comment: 10 pages, 6 figure

Does inter-vertebral range of motion increase after spinal manipulation? A prospective cohort study.

Background: Spinal manipulation for nonspecific neck pain is thought to work in part by improving inter-vertebral range of motion (IV-RoM), but it is difficult to measure this or determine whether it is related to clinical outcomes. Objectives: This study undertook to determine whether cervical spine flexion and extension IV-RoM increases after a course of spinal manipulation, to explore relationships between any IV-RoM increases and clinical outcomes and to compare palpation with objective measurement in the detection of hypo-mobile segments. Method: Thirty patients with nonspecific neck pain and 30 healthy controls matched for age and gender received quantitative fluoroscopy (QF) screenings to measure flexion and extension IV-RoM (C1-C6) at baseline and 4-week follow-up between September 2012-13. Patients received up to 12 neck manipulations and completed NRS, NDI and Euroqol 5D-5L at baseline, plus PGIC and satisfaction questionnaires at follow-up. IV-RoM accuracy, repeatability and hypo-mobility cut-offs were determined. Minimal detectable changes (MDC) over 4 weeks were calculated from controls. Patients and control IV-RoMs were compared at baseline as well as changes in patients over 4 weeks. Correlations between outcomes and the number of manipulations received and the agreement (Kappa) between palpated and QF-detected of hypo-mobile segments were calculated. Results: QF had high accuracy (worst RMS error 0.5o) and repeatability (highest SEM 1.1o, lowest ICC 0.90) for IV-RoM measurement. Hypo-mobility cut offs ranged from 0.8o to 3.5o. No outcome was significantly correlated with increased IV-RoM above MDC and there was no significant difference between the number of hypo-mobile segments in patients and controls at baseline or significant increases in IV-RoMs in patients. However, there was a modest and significant correlation between the number of manipulations received and the number of levels and directions whose IV-RoM increased beyond MDC (Rho=0.39, p=0.043). There was also no agreement between palpation and QF in identifying hypo-mobile segments (Kappa 0.04-0.06). Conclusions: This study found no differences in cervical sagittal IV-RoM between patients with non-specific neck pain and matched controls. There was a modest dose-response relationship between the number of manipulations given and number of levels increasing IV-RoM - providing evidence that neck manipulation has a mechanical effect at segmental levels. However, patient-reported outcomes were not related to this

Initial elevation bias in subjective reports

Peer reviewedPostprin

Reliability of capturing foot parameters using digital scanning and the neutral suspension casting technique

<p>Abstract</p> <p>Background</p> <p>A clinical study was conducted to determine the intra and inter-rater reliability of digital scanning and the neutral suspension casting technique to measure six foot parameters. The neutral suspension casting technique is a commonly utilised method for obtaining a negative impression of the foot prior to orthotic fabrication. Digital scanning offers an alternative to the traditional plaster of Paris techniques.</p> <p>Methods</p> <p>Twenty one healthy participants volunteered to take part in the study. Six casts and six digital scans were obtained from each participant by two raters of differing clinical experience. The foot parameters chosen for investigation were cast length (mm), forefoot width (mm), rearfoot width (mm), medial arch height (mm), lateral arch height (mm) and forefoot to rearfoot alignment (degrees). Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) were calculated to determine the intra and inter-rater reliability. Measurement error was assessed through the calculation of the standard error of the measurement (SEM) and smallest real difference (SRD).</p> <p>Results</p> <p>ICC values for all foot parameters using digital scanning ranged between 0.81-0.99 for both intra and inter-rater reliability. For neutral suspension casting technique inter-rater reliability values ranged from 0.57-0.99 and intra-rater reliability values ranging from 0.36-0.99 for rater 1 and 0.49-0.99 for rater 2.</p> <p>Conclusions</p> <p>The findings of this study indicate that digital scanning is a reliable technique, irrespective of clinical experience, with reduced measurement variability in all foot parameters investigated when compared to neutral suspension casting.</p

Development of Ferroelectric Order in Relaxor (1-x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3

The microstructure and phase transition in relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 (PMN) and its solid solution with PbTiO3 (PT), PMN-xPT, remain to be one of the most puzzling issues of solid state science. In the present work we have investigated the evolution of the phase symmetry in PMN-xPT ceramics as a function of temperature (20 K < T < 500 K) and composition (0 <= x <= 0.15) by means of high-resolution synchrotron x-ray diffraction. Structural analysis based on the experimental data reveals that the substitution of Ti^4+ for the complex B-site (Mg1/3Nb2/3)^4+ ions results in the development of a clean rhombohedral phase at a PT-concentration as low as 5%. The results provide some new insight into the development of the ferroelectric order in PMN-PT, which has been discussed in light of the kinetics of polar nanoregions and the physical models of the relaxor ferroelectrics to illustrate the structural evolution from a relaxor to a ferroelectric state.Comment: Revised version with updated references; 9 pages, 4 figures embedde