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  • 1
    Electronic Resource
    Electronic Resource
    An optical spin micromotor (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1779-1781 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An optical spin micromotor operated by optical tweezers, described in the present study, converts radiant energy directly to mechanical energy. This conversion is of great practical and fundamental interest. The optical spin micromotor consists of a two-bead linkage. The large bead (2.0 μm in diameter) is trapped by the optical tweezers and rotates around the laser beam axis. The small bead (0.94 μm in diameter) is partially coated with gold/palladium for generating the spin torque through the change of momentum from gradient radiation pressure of the same laser applied on the coated small bead. With a laser power of 29 mW at the sample plane, the spin speed averaged 158.8±155.5 rpm (mean±standard deviation) and the torque was estimated as 101.9±99.8 pN nm. This optical spin micromotor will be useful in (1) providing a fundamental step toward developing optical-operated mechanical devices, (2) twisting macromolecules, and (3) generating vortex and shear force in medium at nanoscale. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126165
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  • 2
    Electronic Resource
    Electronic Resource
    Distal upper extremity function following proximal humeral resection and reconstruction for tumors: Contralateral comparison (1997)
    Springer
    Annals of surgical oncology 4 (1997), S. 237-246 
    Details
    ISSN: 1534-4681
    Keywords: Sarcoma ; Oncology ; Reconstruction ; Shoulder ; Upper extremity ; Limb salvage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Most functional analyses after limb salvage operations about the shoulder have focused on proximal function with the assumption that distal function is largely unaffected. This analysis examines distal function objectively. Methods: Objective laboratory data regarding distal upper extremity strength after reconstructive procedures for tumors near the shoulder joint was collected over a 16-year period. Thirty-two patients were able to participate fully in the data collection at an average most recent follow-up duration of 〉3.5 years. Results: Statistically significant reductions on the involved side compared with the uninvolved side in grip, forearm pronation, forearm supination, elbow flexion, and elbow extension strength were documented (p〈0.05). The magnitude of reduction in strength diminishes distally, with the greatest effect in this group of patients being observed in elbow extension, followed by elbow flexion, forearm supination, and forearm pronation. Grip strength consistently showed the least amount of strength reduction compared with the uninvolved side, even within resection and reconstruction groups. Subjective patient rating of dexterity was no less than 3 of 5. Ninety percent of patients rated their dexterity 4 of 5 (52%) or 5 of 5 (38%). Conclusions: Despite the insistence of “normal” function in the distal upper extremity after limb salvage procedures, complete normality is not maintained. However, the degree of maintenance of distal function appears to be high, especially for grip strength and forearm pronation strength, and patient satisfaction is acceptable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02306616
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  • 3
    Electronic Resource
    Electronic Resource
    A theoretical model to predict distribution of the fabric tensor and apparent density in cancellous bone (1998)
    Springer
    Journal of mathematical biology 36 (1998), S. 557-568 
    Details
    ISSN: 1432-1416
    Keywords: Key words: Theoretical model ; Fabric tensor ; Apparent density ; Bone remodeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract.  The adaptation of cancellous bone to mechanical forces is well recognized. Theoretical models for predicting cancellous bone architecture have been developed and have mainly focused on the distribution of trabecular mass or the apparent density. The purpose of this study was to develop a theoretical model which can simultaneously predict the distribution of trabecular orthotropy/orientation, as represented by the fabric tensor, along with apparent density. Two sets of equations were derived under the assumption that cancellous bone is a biological self-optimizing material which tends to minimize strain energy. The first set of equations provide the relationship between the fabric tensor and stress tensor, and have been verified to be consistent with Wolff’s law of trabecular architecture, that is, the principal directions of the fabric tensor coincide with the principal stress trajectories. The second set of equations yield the apparent density from the stress tensor, which was shown to be identical to those obtained based on local optimization with strain energy density of true bone tissue as the objective function. These two sets of equations, together with elasticity field equations, provide a complete mathematical formulation for the adaptation of cancellous bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002850050114
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  • 4
    Electronic Resource
    Electronic Resource
    Relationship of deep structures of the hand and wrist to topographical landmarks (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 6 (1993), S. 300-307 
    Details
    ISSN: 0897-3806
    Keywords: carpal canal ; carpal tunnel surgery ; carpal tunnel syndrome ; flexor retinaculum ; transverse carpal ligament ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The relationship of topographical landmarks to the deep structures of the wrist and hand has not been clearly defined and would be of benefit to surgeons performing endoscopic carpal tunnel surgery. To this end, 10 fresh cadaveric wrist specimens had radiopaque markers placed adjacent to key anatomic structures within the wrist and hand. A new technique for localizing the hook of the hamate was established. We found that the thick segment of the flexor retinaculum, often defined as the transverse carpal ligament, was 2.2 cm in length. Its distal border was 1 cm distal to the distal aspect of the hook of the hamate. The proximal ligamentous portion had a mean length of 1.2 cm, whereas the distal aponeurotic portion (distal to the hook of the hamate) had a mean length of 1.0 cm. The position of the superficial palmar arch was 2.7 cm distal to the hook of the hamate or at a line bisecting three-fourths of the distance from the distal flexor wrist crease to the proximal palmar crease. The relationship of the superficial palmar arch to topographical landmarks was more consistent than it was when the standard reference of Kaplan's cardinal line was used. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ca.980060507
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  • 5
    Electronic Resource
    Electronic Resource
    Quantitative analysis of the intrinsic muscles of the hand (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 4 (1991), S. 265-284 
    Details
    ISSN: 0897-3806
    Keywords: biomechanics ; anatomy ; fingers ; forces ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: As part of a study involving three-dimensional modeling of the hand, the intrinsic muscles of the hand were evaluated quantitatively to estimate the range of muscular forces crossing the fingers. The Brand method of dissection allowed determination of muscle volume, fiber length, and physiologic cross section to estimate the maximal force. The intrinsic muscles were grouped by components on the basis of their origins in the trilaminar scheme of Cunningham as (1) dorsal abductors from the central ray, exemplified by the bipennate dorsal interossei; (2) the intermediate layer consisting of inter-phalangeal joint extensors, exemplified by the unipennate palmar interossei with insertions into the extensor expansion; and (3) a superficial layer of adductors arising from the third metacarpal ridge, referred to as contrahentes.The fiber lengths of either component of the dorsal interossei averaged 1.3 cm. The intermediate layer of muscle, numbered as flexores breves (FB), included the palmar interossei FB4,7,9; the superficial components of the dorsal interossei FB3,5,6,8; and the accessory adductor pollicis FB2. Fiber lengths averaged 1.7 cm. The superficial heads of the flexor pollicis brevis and abductor digiti quinti are possibly the border representations of the intermediate layer as FB1 and FB10. The thenar muscles made up 37%, dorsal interossei 24%, palmar interossei (flexores breves) of the fingers 16%, lumbricals 7%, and hypothenar muscles 16% of the total intrinsic muscle mass.The ratio of muscle mass to fiber length, the physiologic cross-sectional area, is useful in estimating available force.This quantitative analysis of the intrinsic musculature may find application in the understanding of hand function and biomechanics.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ca.980040405
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  • 6
    Electronic Resource
    Electronic Resource
    A method for determination of the anisotropic properties of biomembranes (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 125-132 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A methodology was developed for potential determination of the anisotropic properties of biomembranes. This method is based on the theoretical discretization of a continuous membrane used for finite element analysis and the simultaneous measurement of the displacement of nodes on the surface of a membrane. From the given loads and measured nodal displacements, one can assemble the resulting stiffness matrix and approximate the material properties associated with the membrane. Mathematical estimations and computer simulations were performed to determine the perturbation of load and displacement errors on the resulting material properties. The results indicated that the material properties are particularly sensitive to displacement errors. The displacement measurements may require an accuracy of 20 μm for a 4 × 4 cm2 specimen. Significant inaccuracies occur close to the points of load application. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Ligamentous structures of the metacarpophalangeal joint: A quantitative anatomic study (1983)
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 1 (1983), S. 361-368 
    Details
    ISSN: 0736-0266
    Keywords: Index finger ; Ligamentous structures ; Metacarpophalangeal joint ; Quantitative anatomic study ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ligamentous structure of the metacarpophalangeal (MCP) joint of the index finger in human cadavers was studied by gross examination and quantitative measurement. Anatomically, the collateral ligament is separable into two layers, with the precise origin arising from the metacarpal head and inserting on the proximal phalanx. Quantitatively, the change in length of the collateral ligament was studied with biplanar radiographic techniques. The distance between the origin and insertion of the collateral ligament changed in different portions of the ligament when the joint was moved from a position of hyperextension to that of flexion. When the MCP joint was flexed from 0° to 80°, the dorsal portions of both the radial and ulnar collateral ligaments were lengthened (3-4 mm). The middle portions of both ligaments were slightly elongated (0.4-1.0 mm), and the volar portions of the ligaments were shortened (1-2 mm). When the MCP joint extended into hyperextension, the dorsal portions of the ligaments shortened 2-3 mm, the middle thirds of the ligaments shortened slightly, and the volar thirds of the ligaments lengthened. The results of this study suggest that the dorsal and volar portions of the collateral ligament provide MCP joint constraint at the flexed and extended positions, respectively.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jor.1100010404
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  • 8
    Electronic Resource
    Electronic Resource
    Transverse stability of the carpus. An analytical study (1989)
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 7 (1989), S. 738-743 
    Details
    ISSN: 0736-0266
    Keywords: Carpus ; Flexor retinaculum ; Wrist stability ; Intercarpal force distribution ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The stabilizing structures of the transverse carpal arch were studied utilizing an analytical model based on a rigid body spring model theory. This method was used to calculate the relative motion between carpal bones, the distribution of compressive forces in the intercarpal joints, and the tensions in the ligaments under simulated dorsopalmar compression. The contribution of each ligament against the effect of compression was determined by removing ligaments from the model. A multivariate analysis of variance disclosed that sectioning the flexor retinaculum alone does not significantly modify the distribution of forces in ligaments and joints (p = 0.33), and decreases dorsopalmar carpal stiffness by only 7.8%. In contrast, isolated removal of the palmar hamate-capitate ligament causes a pronounced weakening of the carpal structure, from an average fo 232 to 131 N/mm (p 〈 0.01). If the flexor retinaculum is removed in addition to releasing one palmar intercarpal ligament, a gross instability of the carpal arch is created.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jor.1100070516
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