The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Joseph L Demer - One of the best experts on this subject based on the ideXlab platform.
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the effect of axial length on extraocular muscle leverage
American Journal of Ophthalmology, 2020Co-Authors: Robert A Clark, Joseph L DemerAbstract:Purpose Magnetic resonance imaging was used to determine the effect of axial length (AL) on globe Rotational Axis and horizontal extraocular muscle leverage during horizontal duction. Design Prospective observational case series. Methods At a single academic center, 36 orthophoric adults with a wide range of ALs underwent high-resolution axial orbital magnetic resonance imaging in target-controlled adduction and abduction. ALs were measured in planes containing maximum globe cross-sections. Area centroids were calculated to determine globe centers. Rotational axes in orbital coordinates were calculated from displacements of lens centers and globe–optic nerve attachments. Lever arms were calculated as distances between published extraocular muscle insertions and Rotational axes. Results ALs averaged 26.3 ± 0.3 mm (standard error [range 21.5-33.4 mm]). Rotational axes from adduction to abduction averaged 1.1 ± 0.2 mm medial and 1.1 ± 0.2 mm anterior to the globe's geometric center in adduction. Linear regression demonstrated no significant correlation between AL and Rotational Axis horizontal (R2 = 0.06) or anteroposterior (R2 = 0.07) position. Medial rectus (MR) lever arms averaged 12.0 ± 0.2 mm and lateral rectus (LR) lever arms averaged 12.8 ± 0.2 mm. Both MR (R2 = 0.24, P Conclusions Regardless of AL, the globe rotates about a point nasal and anterior to its geometric center, giving the LR more leverage than the MR. This eccentricity may diminish the effect of tendon repositioning in moderate to highly myopic patients, with reductions in per-mill imeter dose/response predicted with longer AL.
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the globe s eccentric Rotational Axis why medial rectus surgery is more potent than lateral rectus surgery
Ophthalmology, 2018Co-Authors: Robert A Clark, Joseph L DemerAbstract:Purpose Tables typically recommend greater lateral rectus (LR) than medial rectus (MR) surgical doses for horizontal strabismus of any given magnitude, a difference unexplained by mechanical models that assume globe rotation about its center. We tested this assumption during horizontal ductions. Design Prospective observational study. Participants Eighteen adult subjects with normal binocular vision. Methods Surface coil magnetic resonance imaging at 390 or 430 μm resolution was obtained using 2-mm–thick contiguous axial planes while subjects fixated targets in central, right, and left gaze. Angular displacements of lines connecting the corneal apex through the minor lens Axis to the retina were measured to approximate clinical ductions. Globe centers were calculated from their area centroids. Apparent lens and globe-optic nerve (ON) junction rotations around the globe center were then compared with clinical ductions. Main Outcome Measures Apparent angular rotations of lenses and globe-ON junctions during horizontal ductions. Results Globe-ON junctions appeared to rotate significantly less around globe centers than did lenses for abduction (20.6°±4.7° vs. 27.4°±7.4°, ± standard deviation (SD), P 0.001) and adduction (25.3°±6.7° vs. 31.9°±8.3°, P 0.001). Both rotations differed significantly from clinical adduction (27.9°±8.3°, P 0.007), but only in abduction was globe-ON junction rotation significantly less than clinical abduction (28.6°±9.4°, P 0.001). The true geometric globe Rotational center was 2.2±0.5 mm medial and 0.8±1.0 mm posterior to the geometric globe center and was displaced farther medially and posteriorly during adduction. This eccentricity imbues each millimeter of MR recession with approximately 30% more trigonometric Rotational effect than equivalent LR recession. Conclusions The medial and posterior eccentricities of the normal ocular Rotational Axis profoundly influence horizontal rectus action. The proximity of the globe's Rotational Axis to the MR shortens its lever arm relative to the LR, explaining why mechanical effects of smaller MR recessions are equivalent to larger LR recessions.
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Effect of adaptation to telescopic spectacles on the initial human horizontal vestibuloocular reflex.
Journal of neurophysiology, 2000Co-Authors: Benjamin T. Crane, Joseph L DemerAbstract:Gain of the vestibuloocular reflex (VOR) not only varies with target distance and Rotational Axis, but can be chronically modified in response to prolonged wearing of head-mounted magnifiers. This ...
Yukihiko Nosé - One of the best experts on this subject based on the ideXlab platform.
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the next generation baylor c gyro pump antithrombogenic free impeller design for long term centrifugal vad
Artificial Organs, 1994Co-Authors: M Yasuhisa D Ohara, Yukihiko NoséAbstract:Abstract: The new generation centrifugal blood pump, the C2 Gyro Pump “Free Impeller Model” specifically designed for long-term ventricular assistance and a bridge to transplantation, has been developed. In the free impeller design, the impeller was completely freed from mechanical tethers by eliminating the shaft. This unique design allowed the incorporation of a center-penetrating hole in the impeller, called the center conduit, which accelerates the secondary blood flow from the bottom to the top of the impeller. During in vitro performance tests, two characteristic impeller motions, called floating mode and wandering Rotational Axis, were observed. In the floating mode, the impeller seemed to be floating without touching the pump casing and resulted in the idea of no bearing contact. Also, the Rotational Axis of the impeller exhibited a small circular motion and illustrated the idea of no stationary area in the blood path. These three characteristics are expected to be advantageous for antithrombogenesity and low hemolysis which are essential for a long-term centrifugal VAD.
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The Next Generation Baylor C‐Gyro Pump: Antithrombogenic “Free Impeller” Design for Long‐Term Centrifugal VAD
Artificial organs, 1994Co-Authors: Yasuhisa Ohara, Yukihiko NoséAbstract:Abstract: The new generation centrifugal blood pump, the C2 Gyro Pump “Free Impeller Model” specifically designed for long-term ventricular assistance and a bridge to transplantation, has been developed. In the free impeller design, the impeller was completely freed from mechanical tethers by eliminating the shaft. This unique design allowed the incorporation of a center-penetrating hole in the impeller, called the center conduit, which accelerates the secondary blood flow from the bottom to the top of the impeller. During in vitro performance tests, two characteristic impeller motions, called floating mode and wandering Rotational Axis, were observed. In the floating mode, the impeller seemed to be floating without touching the pump casing and resulted in the idea of no bearing contact. Also, the Rotational Axis of the impeller exhibited a small circular motion and illustrated the idea of no stationary area in the blood path. These three characteristics are expected to be advantageous for antithrombogenesity and low hemolysis which are essential for a long-term centrifugal VAD.
Makoto Kaneko - One of the best experts on this subject based on the ideXlab platform.
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IROS - The mechanism of the linear load-sensitive continuously variable transmission with the spherical driving unit
2011 IEEE RSJ International Conference on Intelligent Robots and Systems, 2011Co-Authors: Kenjiro Tadakuma, Kazuki Terada, Riichiro Tadakuma, Mitsuru Higashimori, Aiguo Ming, Makoto Shimojo, Makoto KanekoAbstract:This paper describes linear load-sensitive continuously variable transmission with the spherical driving unit. This CVT mechanism consists of spherical drive, drive Axis, motor housing, fixed bracket and linear sliding plate. It changes the reduction ratio continuously by inclination angle of active Rotational Axis. Additionally, this linear mechanism has a load-sensitive function by changing inclination of active Rotational Axis in response to the load. We have developed a linear load-sensitive continuously variable transmission and confirmed the effectiveness of the proposed mechanism.
Yuefa Fang - One of the best experts on this subject based on the ideXlab platform.
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motion characteristics and Rotational Axis analysis of three dof parallel robot mechanisms
Systems Man and Cybernetics, 1995Co-Authors: Z Huang, Yuefa FangAbstract:This paper presents a simple method based on the screw theory for determination of the possible motion characteristics and the position of Rotational axes when the linear displacements are constrained for multi-degree of freedom (2-5 DOF) parallel mechanisms. The theory is significant for understanding novel constrained multi-DOF mechanisms, their kinematics and robot path planning. The paper also reports the analysis results for several three DOF platform and pyramid parallel mechanisms.
Benjamin T. Crane - One of the best experts on this subject based on the ideXlab platform.
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Effect of adaptation to telescopic spectacles on the initial human horizontal vestibuloocular reflex.
Journal of neurophysiology, 2000Co-Authors: Benjamin T. Crane, Joseph L DemerAbstract:Gain of the vestibuloocular reflex (VOR) not only varies with target distance and Rotational Axis, but can be chronically modified in response to prolonged wearing of head-mounted magnifiers. This ...
