MODIFIED TEST STATISTICS BY INTER-VOXEL VARIANCE SHRINKAGE WITH AN APPLICATION TO fMRI

Functional Magnetic Resonance Imaging (fMRI) is a non-invasive technique which is commonly used to quantify changes in blood oxygenation and flow coupled to neuronal activation. One of the primary goals of fMRI studies is to identify localized brain regions where neuronal activation levels vary between groups. Single voxel t-tests have been commonly used to determine whether activation related to the protocol differs across groups. Due to the generally limited number of subjects within each study, accurate estimation of variance at each voxel is difficult. Thus, combining information across voxels in the statistical analysis of fMRI data is desirable in order to improve efficiency. Here we construct a hierarchical model and apply an Empirical Bayes framework on the analysis of group fMRI data, employing techniques used in high throughput genomic studies. The key idea is to shrink residual variances by combining information across voxels, and subsequently to construct an improved test statistic in lieu of the classical t-statistic. This hierarchical model results in a shrinkage of voxel-wise residual sample variances towards a common value. The shrunken estimator for voxelspecific variance components on the group analyses outperforms the classical residual error estimator in terms of mean squared error. Moreover, the shrunken test-statistic decreases false positive rate when testing differences in brain contrast maps across a wide range of simulation studies. This methodology was also applied to experimental data regarding a cognitive activation task.

Stability test of modified repair options for San Pedro Breakwater, Los Angeles, California : coastal model investigation /

"July 1986."

Impact test of compact vehicle with modified side structure, 25 mph, 60 degree impact, Torino-to-Volare, test no. 3. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Impact test of compact vehicle with modified side structure, 35 mph, 90 degree impact, Torino-to-Volare, test no. 4. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Impact test of compact vehicle with modified side structure, 35 mph, 60 degree impact, Torino-to-Volare, test no. 5. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Impact test of compact vehicle with modified side structure, 35 mph, 60 degree impact, Impala-to-Volare, test no. 10. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Impact test of compact vehicle with modified side structure, 35 mph, 90 degree impact, Impala-to-Volare, test no. 11. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Impact test of compact vehicle with modified side structure, 35 mph, 60 degree impact, Torino-to-Volare, test no. 6. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Impact test of compact vehicle with modified side structure, 35 mph, 60 degree impact, Torino-to-Volare, test no. 7. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Impact test of compact vehicle with modified side structure, 35 mph, 90 degree impact, Torino-to-Volare, test no. 8. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

An evaluation of the modified motorcycle operator skill test exercises. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Operator, organizational, DS and GS maintenance manual for test set, guided missile system, AN/TSM-84 and electrical equipment shelter, S-250/G (modified) : (Lance guided missile system).

Includes index.

Strain and excursion of the sciatic, tibial, and plantar nerves during a modified straight leg raising test

A modified straight leg raising (SLR) in which ankle dorsiflexion is performed before hip flexion has been suggested to diagnose distal neuropathies such as tarsal tunnel syndrome. This study evaluates the clinical hypothesis that strain in the nerves around the ankle and foot caused by ankle dorsiflexion can be further increased with hip flexion. Linear displacement transducers were inserted into the sciatic, tibial, and plantar nerves and plantar fascia of eight embalmed cadavers to measure strain during the modified SLR. Nerve excursion was measured with a digital calliper. Ankle dorsiflexion resulted in a significant strain and distal. excursion of the tibial nerve. With the ankle in dorsiflexion, the proximal excursion and tension increase in the sciatic nerve associated with hip flexion were transmitted distally along the nerve from the hip to beyond the ankle. As hip flexion had an impact on the nerves around the ankle and foot but not on the plantar fascia, the modified SLR may be a useful test to differentially diagnose plantar heel pain. Although the modified SLR caused the greatest increase in nerve strain nearest the moving joint, mechanical forces acting on peripheral nerves are transmitted well beyond the moving joint. (c) 2006 Orthopaedic Research Society.

Heavy truck suspension optimization based on modified skyhook damping control

This paper presents a multi-objective optimization strategy for heavy truck suspension systems based on modified skyhook damping (MSD) control, which improves ride comfort and road-friendliness simultaneously. A four-axle heavy truck-road coupling system model was established using functional virtual prototype technology; the model was then validated through a ride comfort test. As the mechanical properties and time lag of dampers were taken into account, MSD control of active and semi-active dampers was implemented using Matlab/Simulink. Through co-simulations with Adams and Matlab, the effects of passive, semi-active MSD control, and active MSD control were analyzed and compared; thus, control parameters which afforded the best integrated performance were chosen. Simulation results indicated that MSD control improves a truck’s ride comfort and roadfriendliness, while the semi-active MSD control damper obtains road-friendliness comparable to the active MSD control damper.

Innovation implementation effectiveness : a multiorganizational test of Klein Conn and Sorra’s model.

In an empirical test and extension of Klein Conn and Sorra’s model of innovation implementation effectiveness, we apply structural equation modelling to identify the generalizability of their data-modified model in comparison with their theorised model. We examined the implementation of various types of innovations in a sample of 135 organizations. We found that the data supported the original model rather than the data-modified model, such that implementation climate mediated polices and practices and implementation effectiveness, while implementation effectiveness partially mediated the relationship between implementation climate and innovation effectiveness. Furthermore, we extend their model to suggest that non-financial resources availability plays a critical role in implementation policies and practices.