The Experts below are selected from a list of 35847 Experts worldwide ranked by ideXlab platform

Nico Rozendaal - One of the best experts on this subject based on the ideXlab platform.

  • the effects of freesurfer Version workstation type and macintosh Operating System Version on anatomical volume and cortical thickness measurements
    PLOS ONE, 2012
    Co-Authors: Ed H B M Gronenschild, Petra Habets, Heidi I L Jacobs, Ron Mengelers, Nico Rozendaal
    Abstract:

    FreeSurfer is a popular software package to measure cortical thickness and volume of neuroanatomical structures. However, little if any is known about measurement reliability across various data processing conditions. Using a set of 30 anatomical T1-weighted 3T MRI scans, we investigated the effects of data processing variables such as FreeSurfer Version (v4.3.1, v4.5.0, and v5.0.0), workstation (Macintosh and Hewlett-Packard), and Macintosh Operating System Version (OSX 10.5 and OSX 10.6). Significant differences were revealed between FreeSurfer Version v5.0.0 and the two earlier Versions. These differences were on average 8.8±6.6% (range 1.3–64.0%) (volume) and 2.8±1.3% (1.1–7.7%) (cortical thickness). About a factor two smaller differences were detected between Macintosh and Hewlett-Packard workstations and between OSX 10.5 and OSX 10.6. The observed differences are similar in magnitude as effect sizes reported in accuracy evaluations and neurodegenerative studies. The main conclusion is that in the context of an ongoing study, users are discouraged to update to a new major release of either FreeSurfer or Operating System or to switch to a different type of workstation without repeating the analysis; results thus give a quantitative support to successive recommendations stated by FreeSurfer developers over the years. Moreover, in view of the large and significant cross-Version differences, it is concluded that formal assessment of the accuracy of FreeSurfer is desirable.

Steven F Bellenot - One of the best experts on this subject based on the ideXlab platform.

  • twos time warp Operating System Version 2 5 1
    1994
    Co-Authors: Steven F Bellenot
    Abstract:

    The Time Warp Operating System (TWOS) is a special-purpose Operating System designed to support parallel discrete-event simulation. TWOS is a complete implementation of the Time Warp mechanism, a distributed protocol for virtual time synchronization based on process rollback and message annihilation. Version 2.5.1 supports simulations and other computations using both virtual time and dynamic load balancing; it does not support general time-sharing or multi-process jobs using conventional message synchronization and communication. The program utilizes the underlying Operating System's resources. TWOS runs a single simulation at a time, executing it concurrently on as many processors of a distributed System as are allocated. The simulation needs only to be decomposed into objects (logical processes) that interact through time-stamped messages. TWOS provides transparent synchronization. The user does not have to add any more special logic to aid in synchronization, nor give any synchronization advice, nor even understand much about how the Time Warp mechanism works. The Time Warp Simulator (TWSIM) subdirectory contains a sequential simulation engine that is interface compatible with TWOS. This means that an application designer and programmer who wish to use TWOS can prototype code on TWSIM on a single processor and/or workstation before having to deal with the complexity of working on a distributed System. TWSIM also provides statistics about the application which may be helpful for determining the correctness of an application and for achieving good performance on TWOS. Version 2.5.1 has an updated interface that is not compatible with 2.0. The program's user manual assists the simulation programmer in the design, coding, and implementation of discrete-event simulations running on TWOS. The manual also includes a practical user's guide to the TWOS application benchmark, Colliding Pucks. TWOS supports simulations written in the C programming language. It is designed to run on the Sun3/Sun4 series computers and the BBN "Butterfly" GP-1000 computer. The standard distribution medium for this package is a .25 inch tape cartridge in TAR format. TWOS was developed in 1989 and updated in 1991. This program is a copyrighted work with all copyright vested in NASA. Sun3 and Sun4 are trademarks of Sun MicroSystems, Inc.

  • time warp Operating System Version 2 5 1
    NASA Tech Briefs, 1993
    Co-Authors: Steven F Bellenot, John S Gieselman, Lawrence R Hawley, Judy Peterson, Matthew T Presley, Peter Reiher, Paul L Springer, John R Tupman, John J Wedel, Frederick Wieland
    Abstract:

    Time Warp Operating System, TWOS, is special purpose computer program designed to support parallel simulation of discrete events. Complete implementation of Time Warp software mechanism, which implements distributed protocol for virtual synchronization based on rollback of processes and annihilation of messages. Supports simulations and other computations in which both virtual time and dynamic load balancing used. Program utilizes underlying resources of Operating System. Written in C programming language.

Ed H B M Gronenschild - One of the best experts on this subject based on the ideXlab platform.

  • the effects of freesurfer Version workstation type and macintosh Operating System Version on anatomical volume and cortical thickness measurements
    PLOS ONE, 2012
    Co-Authors: Ed H B M Gronenschild, Petra Habets, Heidi I L Jacobs, Ron Mengelers, Nico Rozendaal
    Abstract:

    FreeSurfer is a popular software package to measure cortical thickness and volume of neuroanatomical structures. However, little if any is known about measurement reliability across various data processing conditions. Using a set of 30 anatomical T1-weighted 3T MRI scans, we investigated the effects of data processing variables such as FreeSurfer Version (v4.3.1, v4.5.0, and v5.0.0), workstation (Macintosh and Hewlett-Packard), and Macintosh Operating System Version (OSX 10.5 and OSX 10.6). Significant differences were revealed between FreeSurfer Version v5.0.0 and the two earlier Versions. These differences were on average 8.8±6.6% (range 1.3–64.0%) (volume) and 2.8±1.3% (1.1–7.7%) (cortical thickness). About a factor two smaller differences were detected between Macintosh and Hewlett-Packard workstations and between OSX 10.5 and OSX 10.6. The observed differences are similar in magnitude as effect sizes reported in accuracy evaluations and neurodegenerative studies. The main conclusion is that in the context of an ongoing study, users are discouraged to update to a new major release of either FreeSurfer or Operating System or to switch to a different type of workstation without repeating the analysis; results thus give a quantitative support to successive recommendations stated by FreeSurfer developers over the years. Moreover, in view of the large and significant cross-Version differences, it is concluded that formal assessment of the accuracy of FreeSurfer is desirable.

Petra Habets - One of the best experts on this subject based on the ideXlab platform.

  • the effects of freesurfer Version workstation type and macintosh Operating System Version on anatomical volume and cortical thickness measurements
    PLOS ONE, 2012
    Co-Authors: Ed H B M Gronenschild, Petra Habets, Heidi I L Jacobs, Ron Mengelers, Nico Rozendaal
    Abstract:

    FreeSurfer is a popular software package to measure cortical thickness and volume of neuroanatomical structures. However, little if any is known about measurement reliability across various data processing conditions. Using a set of 30 anatomical T1-weighted 3T MRI scans, we investigated the effects of data processing variables such as FreeSurfer Version (v4.3.1, v4.5.0, and v5.0.0), workstation (Macintosh and Hewlett-Packard), and Macintosh Operating System Version (OSX 10.5 and OSX 10.6). Significant differences were revealed between FreeSurfer Version v5.0.0 and the two earlier Versions. These differences were on average 8.8±6.6% (range 1.3–64.0%) (volume) and 2.8±1.3% (1.1–7.7%) (cortical thickness). About a factor two smaller differences were detected between Macintosh and Hewlett-Packard workstations and between OSX 10.5 and OSX 10.6. The observed differences are similar in magnitude as effect sizes reported in accuracy evaluations and neurodegenerative studies. The main conclusion is that in the context of an ongoing study, users are discouraged to update to a new major release of either FreeSurfer or Operating System or to switch to a different type of workstation without repeating the analysis; results thus give a quantitative support to successive recommendations stated by FreeSurfer developers over the years. Moreover, in view of the large and significant cross-Version differences, it is concluded that formal assessment of the accuracy of FreeSurfer is desirable.

Heidi I L Jacobs - One of the best experts on this subject based on the ideXlab platform.

  • the effects of freesurfer Version workstation type and macintosh Operating System Version on anatomical volume and cortical thickness measurements
    PLOS ONE, 2012
    Co-Authors: Ed H B M Gronenschild, Petra Habets, Heidi I L Jacobs, Ron Mengelers, Nico Rozendaal
    Abstract:

    FreeSurfer is a popular software package to measure cortical thickness and volume of neuroanatomical structures. However, little if any is known about measurement reliability across various data processing conditions. Using a set of 30 anatomical T1-weighted 3T MRI scans, we investigated the effects of data processing variables such as FreeSurfer Version (v4.3.1, v4.5.0, and v5.0.0), workstation (Macintosh and Hewlett-Packard), and Macintosh Operating System Version (OSX 10.5 and OSX 10.6). Significant differences were revealed between FreeSurfer Version v5.0.0 and the two earlier Versions. These differences were on average 8.8±6.6% (range 1.3–64.0%) (volume) and 2.8±1.3% (1.1–7.7%) (cortical thickness). About a factor two smaller differences were detected between Macintosh and Hewlett-Packard workstations and between OSX 10.5 and OSX 10.6. The observed differences are similar in magnitude as effect sizes reported in accuracy evaluations and neurodegenerative studies. The main conclusion is that in the context of an ongoing study, users are discouraged to update to a new major release of either FreeSurfer or Operating System or to switch to a different type of workstation without repeating the analysis; results thus give a quantitative support to successive recommendations stated by FreeSurfer developers over the years. Moreover, in view of the large and significant cross-Version differences, it is concluded that formal assessment of the accuracy of FreeSurfer is desirable.