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Tesfamariam, Melake D., Asad M. Mirza, Daniel Chaparro, Ahmed Z. Ali, Rachel Montalvan, Ilyas Saytashev, Brittany A. Gonzalez et al. „Elastin-Dependent Aortic Heart Valve Leaflet Curvature Changes During Cyclic Flexure“. Bioengineering 6, Nr. 2 (07.05.2019): 39. http://dx.doi.org/10.3390/bioengineering6020039.
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The progression of calcific aortic valve disease (CAVD) is characterized by extracellular matrix (ECM) remodeling, leading to structural abnormalities and improper valve function. The focus of the present study was to relate aortic valve leaflet axial curvature changes as a function of elastin degradation, which has been associated with CAVD. Circumferential rectangular strips (L × W = 10 × 2.5 mm) of normal and elastin-degraded (via enzymatic digestion) porcine AV leaflets were subjected to cyclic flexure (1 Hz). A significant increase in mean curvature (p < 0.05) was found in elastin-degraded leaflet specimens in comparison to un-degraded controls at both the semi-constrained (50% of maximum flexed state during specimen bending and straightening events) and fully-constrained (maximally-flexed) states. This significance did not occur in all three flexed configurations when measurements were performed using either minimum or maximum curvature. Moreover, the mean curvature increase in the elastin-degraded leaflets was most pronounced at the instance of maximum flexure, compared to un-degraded controls. We conclude that the mean axial curvature metric can detect distinct spatial changes in aortic valve ECM arising from the loss in bulk content and/or structure of elastin, particularly when there is a high degree of tissue bending. Therefore, the instance of maximum leaflet flexure during the cardiac cycle could be targeted for mean curvature measurements and serve as a potential biomarker for elastin degradation in early CAVD remodeling.
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HIRATA, H., K. FUJISAWA, H. SASAKI, A. MORITA und M. MATSUMOTO. „Congenital Triggering of The Index Finger at The A2 Pulley“. Journal of Hand Surgery 21, Nr. 5 (Oktober 1996): 609–11. http://dx.doi.org/10.1016/s0266-7681(96)80140-9.
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A case of trigger index finger is reported. The diagnosis was made in the neonatal intensive care unit. The proximal interphalangeal joint (PIP) was locked in a flexed position. A nodular thickening of the flexor tendon was felt at the A2 pulley level. Surgery revealed thickening of both the A2 pulley and the radial slip of the flexor superficialis tendon. Division of the A2 pulley released the PIP joint locking.
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Ema, Ryoichi, Momoka Suzuki, Emi Kawaguchi, Itaru Saito und Ryota Akagi. „Effects of sex and joint action on voluntary activation“. PeerJ 6 (15.11.2018): e5968. http://dx.doi.org/10.7717/peerj.5968.
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The current study tested the hypothesis that voluntary activation during maximal voluntary contraction (MVC) conditionally depends on sex and joint action. Twenty-eight healthy adults (14 of each sex) performed knee extensor MVC and plantar flexor MVC at extended and flexed knee positions. Voluntary activation during MVC was assessed using a twitch interpolation technique. The voluntary activation during plantar flexor MVC at the extended knee position was significantly lower (P = 0.020, 95% confidence interval 1.4 to 14.6, Cohen’s d for between-subject design = 0.94) in women (88.3% ± 10.0%) than in men (96.2% ± 6.6%). In contrast, no significant sex differences were shown in the voluntary activation during knee extensor MVC (93.7% ± 5.9% (women) vs. 95.0% ± 3.9% (men)) and during plantar flexor MVC at the flexed knee position (90.4% ± 12.2% (women) vs. 96.8% ± 5.6% (men)). The voluntary activation during knee extensor MVC was significantly higher (P = 0.001, 95% confidence interval 2.1 to 8.8, Cohen’s d for within-subject design = 0.69) than that during plantar flexor MVC at the extended knee position in women, whereas the corresponding difference was not observed in men. The results revealed that the existence of sex difference in the voluntary activation during MVC depends on joint action and joint angle.
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Danley, BT, BN Hamilton, D. Tantbirojn, RE Goldstein und A. Versluis. „Cuspal Flexure and Stress in Restored Teeth Caused by Amalgam Expansion“. Operative Dentistry 43, Nr. 6 (01.11.2018): E300—E307. http://dx.doi.org/10.2341/17-329-l.
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SUMMARY Objective: Cracks in amalgam-filled teeth may be related to amalgam expansion. This study measured cuspal flexure and used finite element analysis to assess associated stress levels in amalgam-filled teeth. Methods and Materials: External surfaces of 18 extracted molars were scanned in three dimensions. Nine molars were restored with mesio-occluso-distal amalgam fillings; the other teeth were left intact as controls. All teeth were stored in saline and scanned after two, four, and eight weeks. Cuspal flexure and restoration expansion were determined by calculating the difference between scanned surfaces. Stresses in a flexed tooth were calculated using finite element analysis. Results: Cusps of amalgam-filled teeth flexed outward approximately 3 μm, and restoration surfaces expanded 4 to 8 μm during storage. Cuspal flexure was significantly higher in the amalgam group (multivariate tests, p<0.05), but storage time had no significant effect (repeated measures, p>0.05). Expansion caused stress concentrations at the cavity line angles. These stress concentrations increased stresses due to mastication 44% to 178%. Conclusions: Amalgam expansion pushed cavity walls outward, which created stress concentrations at the cavity line angles. Expansion stresses can raise stresses in amalgam-filled teeth and contribute to incidentally observed cracks.
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Hoffmann, Gilles, Brian D. Schmit, Jennifer H. Kahn und Derek G. Kamper. „Effect of sensory feedback from the proximal upper limb on voluntary isometric finger flexion and extension in hemiparetic stroke subjects“. Journal of Neurophysiology 106, Nr. 5 (November 2011): 2546–56. http://dx.doi.org/10.1152/jn.00522.2010.
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This study investigated the potential influence of proximal sensory feedback on voluntary distal motor activity in the paretic upper limb of hemiparetic stroke survivors and the potential effect of voluntary distal motor activity on proximal muscle activity. Ten stroke subjects and 10 neurologically intact control subjects performed maximum voluntary isometric flexion and extension, respectively, at the metacarpophalangeal (MCP) joints of the fingers in two static arm postures and under three conditions of electrical stimulation of the arm. The tasks were quantified in terms of maximum MCP torque [MCP flexion (MCPflex) or MCP extension (MCPext)] and activity of targeted (flexor digitorum superficialis or extensor digitorum communis) and nontargeted upper limb muscles. From a previous study on the MCP stretch reflex poststroke, we expected stroke subjects to exhibit a modulation of voluntary MCP torque production by arm posture and electrical stimulation and increased nontargeted muscle activity. Posture 1 (flexed elbow, neutral shoulder) led to greater MCPflexin stroke subjects than posture 2 (extended elbow, flexed shoulder). Electrical stimulation did not influence MCPflexor MCPextin either subject group. In stroke subjects, posture 1 led to greater nontargeted upper limb flexor activity during MCPflexand to greater elbow flexor and extensor activity during MCPext. Stroke subjects exhibited greater elbow flexor activity during MCPflexand greater elbow flexor and extensor activity during MCPextthan control subjects. The results suggest that static arm posture can modulate voluntary distal motor activity and accompanying muscle activity in the paretic upper limb poststroke.
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Yuasa, Yasuhiro, Toshiyuki Kurihara und Tadao Isaka. „Relationship Between Toe Muscular Strength and the Ability to Change Direction in Athletes“. Journal of Human Kinetics 64, Nr. 1 (15.10.2018): 47–55. http://dx.doi.org/10.1515/hukin-2017-0183.
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Abstract This study aimed to investigate the relationship between toe muscular strength and the ability to change direction in athletes. Seventeen collegiate American-football players participated in the study (age 19.9 ± 0.9 years, competition experience 7.3 ± 1.7 years). Two types of measurements were performed to evaluate toe muscular strength: toe flexor strength with the metatarsophalangeal joint in the planter flexed position and toe-pushing force with the metatarsophalangeal joint in the dorsiflexed position. The ability to change direction was evaluated using the pro-agility and 3-cone tests and change of direction deficits, calculated by subtracting the sprint times from the pro-agility and 3-cone times. There were significant correlations between toe-pushing force and the results of the pro-agility and 3-cone tests, but no significant correlations between toe flexor strength and the pro-agility and 3-cone tests. Neither toe-pushing force nor toe flexor strength was significantly correlated with the sprint test results. Furthermore, toe-pushing force was significantly correlated with the 3-cone test deficit, but toe flexor strength was not. The ability to change direction is more strongly affected by toe muscular strength (measured as toe-pushing force) with the metatarsophalangeal joint in the dorsiflexed angle than by toe muscular strength (measured as toe flexor strength) with the metatarsophalangeal joint in the plantar flexed angle. Our results suggest that athletes can improve their ability to change direction with toe muscular strength training with the metatarsophalangeal joint in the dorsiflexed position.
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SAVAGE, R., M. G. PRITCHARD, M. THOMAS und R. G. NEWCOMBE. „Differential Splintage for Flexor Tendon Rehabilitation: An Experimental Study of its Effect on Finger Flexion Strength“. Journal of Hand Surgery 30, Nr. 2 (April 2005): 168–74. http://dx.doi.org/10.1016/j.jhsb.2004.10.014.
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We conducted laboratory tests to investigate the possibility of partly de-powering flexor digitorum profundus with a view of reducing flexion force during active flexor tendon rehabilitation. We constructed a splint and applied tapes to the proximal segments of fingers to test the hypothesis that holding three fingers more extended than the other finger would reduce the flexion strength of the more flexed finger. The splint allowed the metacarpophalangeal joint of the more flexed finger to be held in three positions of increasing flexion (15°, 30°, and 45°) compared to the remaining three fingers. We have called this ‘differential splintage’. Healthy volunteers were tested for maximum active flexion strength at the different flexion angles. ‘Differential splintage’ of up to 45° resulted in mean decreased flexion strength of 28% in the index finger and 35% to 38% in the middle, ring and little fingers. The results suggest that “differential splintage” of a finger after flexor tendon repair may be useful in reducing tension across the repair during a program of active tendon rehabilitation and we feel that it has potential to reduce the incidence of repair rupture before healing is complete.
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Jellema, T., und W. Heitler. „Peripheral control of the gain of a central synaptic connection between antagonistic motor neurones in the locust“. Journal of Experimental Biology 199, Nr. 3 (01.03.1996): 613–25. http://dx.doi.org/10.1242/jeb.199.3.613.
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The metathoracic fast extensor tibiae (FETi) motor neurone of locusts is unusual amongst insect motor neurones because it makes output connections within the central nervous system as well as in the periphery. It makes excitatory chemical synaptic connections to most if not all of the antagonist flexor tibiae motor neurones. The gain of the FETi-flexor connection is dependent on the peripheral conditions at the time of the FETi spike. This dependency has two aspects. First, sensory input resulting from the extensor muscle contraction can sum with the central excitatory postsynaptic potential (EPSP) to augment its falling phase if the tibia is restrained in the flexed position (initiating a tension-dependent reflex) or is free to extend (initiating a movement-dependent resistance reflex). This effect is thus due to simple postsynaptic summation of the central EPSP with peripheral sensory input. Second, the static tibial position at the time of the FETi spike can change the amplitude of the central EPSP, in the absence of any extensor muscle contraction. The EPSP can be up to 30 % greater in amplitude if FETi spikes with the tibia held flexed rather than extended. The primary sense organ mediating this effect is the femoral chordotonal organ. Evidence is presented suggesting that the mechanism underlying this change in gain may be specifically localised to the FETi-flexor connection, rather than being due to general position-dependent sensory feedback summing with the EPSP. The change in the amplitude of the central EPSP is probably not caused by general postsynaptic summation with tonic sensory input, since a diminution in the amplitude of the central EPSP caused by tibial extension is often accompanied by overall tonic excitation of the flexor motor neurone. Small but significant changes in the peak amplitude of the FETi spike have a positive correlation with changes in the EPSP amplitude, suggesting a likely presynaptic component to the mechanism of gain control. The change in amplitude of the EPSP can alter its effectiveness in producing flexor motor output and, thus, has functional significance. The change serves to augment the effectiveness of the FETi-flexor connection when the tibia is fully flexed, and thus to increase its adaptive advantage during the co-contraction preceding a jump or kick, and to reduce the effectiveness of the connection when the tibia is partially or fully extended, and thus to reduce its potentially maladaptive consequences during voluntary extension movements such as thrusting.
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Wu, Chengliang, Weiya Hao, Qichang Mei, Xiaofei Xiao, Xuhong Li und Wei Sun. „Strategies of elite Chinese gymnasts in coping with landing impact from backward somersault“. PeerJ 7 (25.10.2019): e7914. http://dx.doi.org/10.7717/peerj.7914.
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This study aimed to investigate how elite Chinese gymnasts manage the landing impact from a backward somersault. Six international-level male gymnasts performed backward somersault tests with a synchronous collection of kinematics (250 Hz), ground reaction forces (1,000 Hz), and surface electromyography (EMG) (2,000 Hz). A 19-segment human model was developed and lower extremity joints torques were calculated by means of a computer simulation. The angles of the lower extremity joints initially extended and then flexed. These angular velocities of extension continued to decrease and the joint torques changed from extensor to flexor within 100 ms before touchdown. The angles of the hips, knees, and ankles flexed rapidly by 12°, 36°, and 29°, respectively, and the angular velocities of flexion, flexor torque, and EMG peaked sharply during the initial impact phase of the landing. The angles of the hips, knees, and ankles flexed at approximately 90°, 100°, and 80°, respectively. The torques were reversed with the extensor torques, showing a relatively high level of muscle activation during the terminal impact phase of the landing. The results showed that the international-level gymnasts first extended their lower extremity joints, then flexed just before touchdown. They continued flexing actively and rapidly in the initial impact phase and then extended to resist the landing impact and maintain body posture during the terminal impact phase of the landing. The information gained from this study could improve our understanding of the landings of elite gymnasts and assist in injury prevention.
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ELLIOT, D., und J. KHAN. „Palmar Bands in Rheumatoid Arthritis and Other Chronic Conditions of the Upper Limb“. Journal of Hand Surgery 21, Nr. 3 (Juni 1996): 369–74. http://dx.doi.org/10.1016/s0266-7681(05)80206-2.
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Palmar prolapse of the flexor tendons as a result of attenuation of the A1 and A2 pulleys occurs in rheumatoid arthritis and other conditions in which the joints of the fingers are chronically flexed. The flexor tendons may be palpable and sometimes visible as longitudinal bands crossing the palm. This can lead to confusion with the palmar bands of Dupuytren's disease. These bands are illustrated in a small series of patients and a serious complication of a misdiagnosis of Dupuytren's disease is presented. The pathogenesis of these palmar bands in rheumatoid arthritis is discussed.
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Bundy, Mark, James Newill, Vince Marcopoli, Michael Ng und Charles Wells. „A Methodology for Characterizing Gun Barrel Flexure due to Vehicle Motion“. Shock and Vibration 8, Nr. 3-4 (2001): 223–28. http://dx.doi.org/10.1155/2001/746901.
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Barrel centerline curvature is known to influence the location of projectile shot impacts. Superimposed on the unique manufactured barrel centerline is the flexed barrel shape that can occur prior to firing while the vehicle is on the move. In order to understand and quantify the effects of barrel flexure on gun accuracy, it is necessary to determine what combination of fundamental mode shapes is most likely to occur. A method to accomplish this task is described in this paper. The method is demonstrated by enumerating the 10 most likely flexed barrel shapes that were found to occur in a tank-mounted gun barrel while it traversed a bump course.
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Trank, T. V., und J. L. Smith. „Adaptive control for backward quadrupedal walking VI. metatarsophalangeal joint dynamics and motor patterns of digit muscles“. Journal of Neurophysiology 75, Nr. 2 (01.02.1996): 678–79. http://dx.doi.org/10.1152/jn.1996.75.2.678.
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1. We compared the dynamics of the metatarsophalangeal (MTP) joint of the cat's hind paw and the motor patterns of two short and four long muscles of the digits for two walking forms, forward (FWD) and backward (BWD). Kinematic (angular displacements) data digitized from high-speed cine film and electromyographic (EMG) data were synchronized and assessed for bouts of treadmill walking. Kinetic data (joint forces) were calculated from kinematic and anthropometric data with the use of inverse-dynamic calculations in which the MTP joint net torque was divided into gravitational, motion-dependent, ground contact (absent for swing), and muscle torque components. Swing-phase kinetics were calculated from treadmill steps and stance-phase kinetics from overground steps in which one hind paw contacted a miniature force platform embedded in the walkway. 2. The plantar angle at the intersection of the metatarsal and phalangeal segmental lines was used to measure MTP angular displacements. During swing for both walking forms, the MTP joint flexed (F) and then extended (E); however, the F-E transition occurred at the onset of FWD swing and at the end of BWD swing. For FWD walking, the MTP joint extended at a constant velocity during most of stance as the cat's weight rotated forward over the paw. During the unweighting phase at the end of stance, the MTP joint flexed rapidly before paw lift off. For BWD walking, the MTP joint extended briefly at stance onset (similar to a yield) and then flexed at a constant velocity as the cat's weight rotated backward over the paw. At the end of stance, the MTP joint extended and then flexed slightly as the paw was unweighted before paw lift off. 3. For both forms of walking, three of the six muscles tested were recruited just before paw contact and remained active for most (75-80%) of stance for both walking forms: plantaris (PLT), flexor hallucis longus (FHL), and flexor digitorum brevis (FDB). Their recruitment contributed to the flexor muscle torque at the MTP joint during most of FWD and BWD stance and was responsible for the absorption of mechanical power at the MTP joint for FWD stance and generation of mechanical power at the MTP joint during BWD stance. Also, the FHL and PLT, along with the soleus (SOL; also recorded in this study), contributed to an extensor muscle torque (described in paper IV of this series) and the generation of mechanical power at the ankle joint during stance of FWD and BWD walking. 4. The timing of activity for three muscles recruited during FWD swing was distinct for the two walking forms. The hallmark burst of the flexor digitorum longus (FDL)--a single burst, brief in duration and high in amplitude--occurred at the end of FWD swing (as the toes flexed rapidly) but shifted to the onset of BWD stance (as the claws protruded and toes extended) during paw weighting. The extensor digitorum longus (EDL) was recruited after paw off and was active for most of FWD swing; its activity contributed to an extensor muscle torque at the MTP joint and a flexor muscle torque at the ankle joint. For BWD walking, EDL recruitment shifted to an earlier phase in the step cycle and coincided with toe extension, which occurred at the end of stance before paw lift off. This pre-lift off activity continued into the first part of swing and contributed to an extensor muscle torque at the MTP joint and a flexor muscle torque at the ankle.(ABSTRACT TRUNCATED AT 250 WORDS)
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POWELL, E. S., und I. A. TRAIL. „Forces Transmitted Along Human Flexor Tendons – The Effect of Extending the Fingers Against the Resistance Provided by Rubber Bands“. Journal of Hand Surgery (European Volume) 34, Nr. 2 (12.03.2009): 186–89. http://dx.doi.org/10.1177/1753193408096016.
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We wished to test the hypothesis that postoperative extension of repaired flexor tendons against rubber bands will reduce the stress on the repairs, and therefore the risk of rupture. During 24 routine carpal tunnel decompression operations the force in flexor tendons was measured using a load cell. The patients flexed and extended their fingers with and without a rubber band providing resistance to extension. We found no statistically significant difference between the force measured in the tendon with or without the presence of rubber bands. To conclude, we have shown that if the application of rubber band dynamic splintage after flexor tendon repair has any advantage, it is not by reducing the forces transmitted along the tendon during resisted extension or by aiding flexion.
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Chahal, Jaskarndip, Herman S. Dhotar und Dimitri J. Anastakis. „Phaeohyphomycosis Infection Leading to Flexor Tendon Rupture: A Case Report“. HAND 4, Nr. 3 (04.03.2009): 335–38. http://dx.doi.org/10.1007/s11552-009-9178-7.
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A rare previously unreported cause of flexor tendon rupture is described. A 66-year-old man presented with a fully extended left middle finger, accompanied by swelling and purulent drainage. Prior to presentation, he had received a steroid injection for left middle finger stenosing tenosynovitis and subsequently developed culture-proven phaeohyphomycosis fungal infection and secondary enterococcal bacterial infection, requiring pharmacotherapy and incision, drainage, and debridement for abscess formation. Clinical and magnetic resonance imaging findings were consistent with the diagnosis of closed flexor tendon rupture of the left middle finger. Antifungal and antibiotic therapy followed by two-stage flexor tendon reconstruction was performed. Six months postoperatively, full passive range of motion was achieved and the proximal interphalangeal and distal interphalangeal joints of the left middle finger actively flexed to 125° and 90°, respectively.
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MITSIONIS, G., K. J. FISCHER, J. A. BASTIDAS, R. GREWAL, H. J. PFAEFFLE und M. M. TOMAINO. „Feasibility of Partial A2 and A4 Pulley Excision: Residual Pulley Strength“. Journal of Hand Surgery 25, Nr. 1 (Februar 2000): 90–94. http://dx.doi.org/10.1054/jhsb.1999.0332.
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We investigated residual digital flexor pulley strengths after 75% excision of the A2 and A4 pulleys. For direct pull-off tests, A2 and A4 pulleys from cadaveric fingers were tested by pulling on a loop of flexor digitorum profundus tendon through the pulley. For functional loading tests, fingers were positioned with the metacarpophalangeal joint flexed to 90° for A2 testing, and with the proximal interphalangeal joint in 90° flexion for A4 testing (with all other joints in full extension). Excision of 75% of A2 and A4 pulleys reduced pulley strengths determined by both testing methods. For the functional loading tests, which are more clinically relevant, mean tendon forces at failure after partial excision of A2 and A4 pulleys were 224 and 131 N respectively, which is sufficient to withstand flexor tendon forces expected during activities of daily living.
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Sato, Junko, Yoshinori Ishii und Hideo Noguchi. „Comparison of the Thickness of Pulley and Flexor Tendon Between in Neutral and in Flexed Positions of Trigger Finger“. Open Orthopaedics Journal 10, Nr. 1 (25.03.2016): 36–40. http://dx.doi.org/10.2174/1874325001610010036.
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Objective: This study aims to compare the morphology of the A1 pulley and flexor tendons in idiopathic trigger finger of digits other than the thumb between in neutral position and in the position with the interphalangeal joints full flexed and with the metacarpophalangeal (MP) joint 0° extended (hook grip position). Method: A total of 48 affected digits and 48 contralateral normal digits from 48 patients who initially diagnosed with idiopathic trigger finger were studied sonographically. Sonographic analysis was focused on the A1 pulley and flexor tendons at the level of the MP joint in the transverse plane. We measured the anterior-posterior thickness of A1 pulley and the sum of the flexor digitorum superficialis and profundus tendons, and also measured the maximum radialulnar width of the flexor tendon in neutral and hook grip positions, respectively. Each measurement was compared between in neutral and in hook grip positions, and also between the affected and contralateral normal digits in each position. Results: In all the digits, the anterior-posterior thickness of flexor tendons significantly increased in hook grip position as compared with in neutral position, whereas radial-ulnar width significantly decreased. Both the A1 pulley and flexor tendons were thicker in the affected digits as compared with contralateral normal digits. Conclusion: The thickness of flexor tendons was significantly increased anteroposteriorly in hook grip position as compared with in neutral position. In trigger finger, A1 pulley and flexor tendon were thickened, and mismatch between the volume of the flexor tendon sheath and the tendons, especially in anterior-posterior direction, might be a cause of repetitive triggering.
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Miller, John P., Kerriann Catlaw und Robert Confessore. „Effect of Ankle Position on EMG Activity and Peak Torque of the Knee Extensors and Flexors during Isokinetic Testing“. Journal of Sport Rehabilitation 6, Nr. 4 (November 1997): 335–42. http://dx.doi.org/10.1123/jsr.6.4.335.
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The purpose of this study was to examine the effect of ankle position on the electromyographic (EMG) activity, peak torque, and peak knee flexion to extension torque ratio during isokinetic testing of the knee. Twelve healthy female athletes performed six maximal knee extension and flexion repetitions with their dominant legs at 60 and 180°/s with the ankle in a plantar flexed position and again in a dorsiflexed position. Root mean square EMG (rmsEMG) activity was determined by placing bipolar surface electrodes on the quadriceps and the hamstrings. Ankle position had no effect on the rmsEMG activity of the quadriceps or the hamstrings at either 60 or 180°/s. Significant differences were noted for peak flexor torque at 607s (p <.001) and 180°/s (p<.01) and for peak torque flexor/extensor ratio (p <.01), with higher values observed with ankle dorsiflexion. This suggests that ankle position affects knee flexor torque and flexor/extensor ratio but not hamstring activity during isokinetic testing of the knee.
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Jung, Jinwon, Nguyen Van Sy, Dongkyu Lee, Seonggun Joe, Jaihyuk Hwang und Byungkyu Kim. „A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems“. Applied Sciences 10, Nr. 20 (12.10.2020): 7087. http://dx.doi.org/10.3390/app10207087.
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For earth observation, the optical systems in small satellites are crucial to obtain high- resolution images. However, the alignment between a primary and a secondary mirror in an optical system can be disturbed due to the harsh environments inside vehicles or space (i.e., vibrations, shock loading during launch, dramatic temperature changes, or high vacuum pressure in space). To compensate for such undesired deformations, a focusing mechanism should be embedded into the optical system. In this paper, we propose a novel Single Motor-Driven Focusing mechanism with Flexure Hinges (SMFH), allowing the Flexure Hinge (FlexHe) to displace in the longitudinal direction. The presented FlexHe incorporates radial zig-zag-patterned slits to achieve flexibility, and preloading of the hinge structures to reduce the resulting hysteresis. To investigate an optimal configuration of FlexHe, a numerical simulation is performed by means of ANSYS 19.2. The variation of Modulation Transfer Function (MTF), corresponding to an image resolution, is evaluated by using an optics simulation program (CODE-V). The experimental setups are built by exploiting the fabricated SMFH and five LVDT (Linear Variable Differential Transformer) sensors with a high resolution of 0.031 µm. As a result, hysteresis can be reduced up to 6.52% with a pre-stretched length of 3 µm. The proposed SMFH allows not only the De-space to displace up to 23.93 µm, but also the De-center and the Tilt to achieve the desired displacements of 5.20 µm and 88.45 µrad, respectively. Conclusively, the SMFH shows promising characteristics to embed a feedback control, due to its high resolution (up to 0.1 µm) for De-space with the MTF of 37%.
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Vanguri, Sailabala, und Bethi Manasa. „Accessory head of flexor digiti minimi: a case study“. National Journal of Clinical Anatomy 04, Nr. 04 (Oktober 2015): 208–9. http://dx.doi.org/10.1055/s-0039-3401576.
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AbstractFlexor digiti minimi is a muscle of hypothenar eminence. It flexes the little finger at metacarpo phalangeal joint. During routine Anatomical dissection, an extra muscle was noticed in the flexor compartment of right forearm of a male cadaver. The identified muscle took origin from medial aspect of the Palmaris longus tendon just proximal to the wrist joint. When traced distally this muscle joined the fibers of the Flexor digiti minimi, and finally got inserted to palmar aspect of base of proximal phalanx of 5th digit. In its course, the muscle crossed median nerve and Ulnar artery. Because of this reason, this variation has the potential to cause compression of the structures mentioned above and is of interest to clinicians.
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Bakır, Kemal. „Book Review: Faydasız Bilginin Faydası / Abraham Flexner, 2017“. Yuksekogretim Dergisi 10, Nr. 2 (27.07.2020): 247–48. http://dx.doi.org/10.2399/yod.20.001.
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Le Sant, Guillaume, Antoine Nordez, François Hug, Ricardo Andrade, Thomas Lecharte, Peter J. McNair und Raphaël Gross. „Effects of stroke injury on the shear modulus of the lower leg muscle during passive dorsiflexion“. Journal of Applied Physiology 126, Nr. 1 (01.01.2019): 11–22. http://dx.doi.org/10.1152/japplphysiol.00968.2017.
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Contractures are common complications of a stroke. The spatial location of the increased stiffness among plantar flexors and its variability among survivors remain unknown. This study assessed the mechanical properties of the lower leg muscles in stroke survivors during passive dorsiflexions. Stiffness was estimated through the measurement of the shear modulus. Two experiments were independently conducted, in which participants lay supine: with the knee extended ( experiment 1, n = 13 stroke survivors and n = 13 controls), or with the knee flexed at 90° ( experiment 2, n = 14 stroke survivors and n = 14 controls). The shear modulus of plantar flexors [gastrocnemius medialis (three locations), gastrocnemius lateralis (three locations), soleus (two locations), flexor digitorum longus, flexor hallucis longus), peroneus longus] and dorsiflexors (tibialis anterior and extensor digitorum longus) was measured using ultrasound shear wave elastography during passive dorsiflexions (2°/s). At the same ankle angle, stroke survivors displayed higher shear modulus than controls for gastrocnemius medialis and gastrocnemius lateralis (knee extended) and soleus (knee flexed). Very low shear modulus was found for the other muscles. The adjustment for muscle slack angle suggested that the increased shear modulus was arising from consequences of contractures. The stiffness distribution between muscles was consistent across participants with the highest shear modulus reported for the most distal regions of gastrocnemius medialis (knee extended) and soleus (knee flexed). These results provide a better appreciation of stiffness locations among plantar flexors of stroke survivors and can provide evidence for the implementation of clinical trials to evaluate targeted interventions applied on these specific muscle regions.NEW & NOTEWORTHY The shear modulus of 13 muscle regions was assessed in stroke patients using elastography. When compared with controls, shear modulus was increased in the gastrocnemius muscle (GM) when the knee was extended and in the soleus (SOL) when the knee was flexed. The distal regions of GM and SOL were the most affected. These changes were consistent in all the stroke patients, suggesting that the regions are a potential source of the increase in joint stiffness.
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Schweizer, Andreas, und Robert Hudek. „Kinetics of Crimp and Slope Grip in Rock Climbing“. Journal of Applied Biomechanics 27, Nr. 2 (Mai 2011): 116–21. http://dx.doi.org/10.1123/jab.27.2.116.
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The aim was to investigate differences of the kinetics of the crimp and the slope grip used in rock climbing. Nine cadaver fingers were prepared and fixated with the proximal phalanx in a frame. The superficial (FDS) and deep (FDP) flexor tendons were loaded selectively and together with 40 N in the crimp grip (PIP joint flexed 90°/DIP joint hyperextended) and the slope grip position (<25° flexed/50° flexed respectively). Five different grip sizes were tested and the flexion force which was generated to the grip was measured. In the crimp grip the FDP generated more flexion force in small sized holds whereas the FDS generated more force in the larger holds. During the slope grip the FDP was more effective than the FDS. While both tendons were loaded, the flexion force was always greater during crimp grip compared with the slope grip. The FDP seems to be most important for very small holds using the crimp grip but also during slope grip holds whereas the FDS is more important for larger flat holds.
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Lewis, Martin G. C., Mark A. King, Maurice R. Yeadon und Filipe Conceição. „Are Joint Torque Models Limited by an Assumption of Monoarticularity?“ Journal of Applied Biomechanics 28, Nr. 5 (November 2012): 520–29. http://dx.doi.org/10.1123/jab.28.5.520.
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This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Isovelocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex MJ dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary.
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Old, Oliver, Vaikunthan Rajaratnam und Gina Allen. „Traumatic correction of Linburg–Comstock anomaly: a case report“. Annals of The Royal College of Surgeons of England 92, Nr. 4 (Mai 2010): e1-e3. http://dx.doi.org/10.1308/147870810x12659688852031.
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Linburg–Comstock anomaly describes an anatomical variant of flexor tendons of the hand. Flexor pollicis longus (FPL) sends a connecting tendon to flexor digitorum profundus (FDP), causing simultaneous flexion at the distal interphalangeal joint (DIPJ) of the index finger when the interphalangeal joint (IPJ) of the thumb is flexed. Epidemiological studies have revealed a unilateral prevalence as high as 31% of individuals; however, the condition rarely causes symptoms. The anomaly can present with a restrictive flexor tenosynovitis, requiring explorative surgery to confirm the diagnosis and disconnection of the anomalous tendon slip to relieve symptoms. We describe the case of a rock climber who suffered a forced extension injury to the DIPJ of the right index finger, resulting in traumatic rupture of his anomalous FPL–FDP connecting tendon. This is the first reported case of rupture of a Linburg–Comstock anomaly. Through rupture of this anomalous tendon, the patient can be viewed as having corrected his aberrant tendon to conform with the more prevalent anatomical configuration and function. We identified the rupture using dynamic ultrasound of the wrist; to our knowledge, this technique has not been described previously in the literature. We recommend the use of this imaging modality to confirm diagnosis, thus avoiding explorative surgery.
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Schatzki, S. C. „Simon Flexner.“ American Journal of Roentgenology 169, Nr. 5 (November 1997): 1395–96. http://dx.doi.org/10.2214/ajr.169.5.9353466.
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Nachman, Ralph L., und Peter M. Marzuk. „Flexner Redux“. Perspectives in Biology and Medicine 54, Nr. 1 (2011): 55–60. http://dx.doi.org/10.1353/pbm.2011.0006.
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Buford, J. A., und J. L. Smith. „Adaptive control for backward quadrupedal walking. II. Hindlimb muscle synergies“. Journal of Neurophysiology 64, Nr. 3 (01.09.1990): 756–66. http://dx.doi.org/10.1152/jn.1990.64.3.756.
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1. To compare the basic hindlimb synergies for backward (BWD) and forward (FWD) walking, electromyograms (EMG) were recorded from selected flexor and extensor muscles of the hip, knee, and ankle joints from four cats trained to perform both forms of walking at a moderate walking speed (0.6 m/s). For each muscle, EMG measurements included burst duration, burst latencies referenced to the time of paw contact or paw off, and integrated burst amplitudes. To relate patterns of muscle activity to various phases of the step cycle, EMG records were synchronized with kinematic data obtained by digitizing high-speed cine film. 2. Hindlimb EMG data indicate that BWD walking in the cat was characterized by reciprocal flexor and extensor synergies similar to those for FWD walking, with flexors active during swing and extensors active during stance. Although the underlying synergies were similar, temporal parameters (burst latencies and durations) and amplitude levels for specific muscles were different for BWD and FWD walking. 3. For both directions, iliopsoas (IP) and semitendinosus (ST) were active as the hip and knee joints flexed at the onset of swing. For BWD walking, IP activity decreased early, and ST activity continued as the hip extended and the knee flexed. For FWD walking, in contrast, ST activity ceased early, and IP activity continued as the hip flexed and the knee extended. For both directions, tibialis anterior (TA) was active throughout swing as the ankle flexed and then extended. A second ST burst occurred at the end of swing for FWD walking as hip flexion and knee extension slowed for paw contact. 4. For both directions, knee extensor (vastus lateralis, VL) activity began at paw contact. Ankle extensor (lateral gastrocnemius, LG) activity began during midswing for BWD walking but just before paw contact for FWD walking. At the ankle joint, flexion during the E2 phase (yield) of stance was minimal or absent for BWD walking, and ankle extension during BWD stance was accompanied by a ramp increase in LG-EMG activity. At the knee joint, the yield was also small (or absent) for BWD walking, and increased VL-EMG amplitudes were associated with the increased range of knee extension for BWD stance. 5. Although the uniarticular hip extensor (anterior biceps femoris, ABF) was active during stance for both directions, the hip flexed during BWD stance and extended during FWD stance.(ABSTRACT TRUNCATED AT 400 WORDS)
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Liverneaux, Philippe A. „The minimally invasive approach for distal radius fractures and malunions“. Journal of Hand Surgery (European Volume) 43, Nr. 2 (12.12.2017): 121–30. http://dx.doi.org/10.1177/1753193417745259.
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This article reviews the author’s currently used minimal invasive approach for volar plating of distal radius fractures. A single longitudinal incision of 1.5 cm is drawn on the lateral aspect of the flexor carpi radialis tendon in order to insert a plate under the pronator quadratus. With the wrist flexed, the plate is applied on the anterior cortex of the radius to reduce the fracture. This approach offers the advantage of preserving ligamentotaxis, which facilitates the reduction, and the small scar improves the cosmetics. It is mainly indicated for extra-articular and simple intra-articular fractures of the distal radius. Relative contraindications are comminuted articular fractures in elderly osteoporotic patients. Functional and radiological results are comparable with those obtained with an extended flexor carpi radialis approach. My colleagues and I have used it for more than 2000 cases since 2012. This technique requires practise. Attempted conversion to a larger incision is possible in case of difficulty, but this is seldom necessary.
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Reddy, V. Manikanta, Vallishri V und Lakshmi Devi C. K. „STUDY ON TENDINOUS CONNECTIONS BETWEEN FLEXOR HALLUCIS LONGUS AND FLEXOR DIGITORUM LONGUS“. International Journal of Anatomy and Research 7, Nr. 2.2 (05.05.2019): 6531–35. http://dx.doi.org/10.16965/ijar.2019.161.
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Willemen, M. A., J. L. Lanovaz, H. C. Schamhardt und Hilary Clayton. „Effects of a Heel Wedge in Horses with Superficial Digital Flexor Tendinitis“. Veterinary and Comparative Orthopaedics and Traumatology 13, Nr. 01 (2000): 01–08. http://dx.doi.org/10.1055/s-0038-1632622.
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SummaryThe objective was to determine whether the use of heel wedges is an appropriate treatment for superficial digital flexor (SDF) tendinitis. The subjects were six warmblood horses in which SDF tendinitis was induced in one forelimb using a collagenase model. The stride characteristics were compared under four conditions: flat shoes; 6° heel wedge following a one hour adaptation; 6° heel wedge following five days adaptation; and one hour after reapplication of flat shoes. Videographic and force data were collected for both forelimbs during the stance phase of the trot, and were combined with morphometric measurements using an inverse dynamics method to calculate net joint moments and joint powers at each of the joints of the forelimbs. Repeated measures ANOVA was used to compare the stride variables across conditions in the lame limb and in the compensating forelimb. Significant kinematic changes in response to the use of heel wedges were confined to the coffin joint which was more flexed due to the more upright orientation of the hoof segment. The onset of breakover was delayed with the hoof wedges. In the compensating limb only, the use of heel wedges was associated with a shift of the net joint moment to the dorsal side of the coffin joint during the first one third of stance. Both forelimbs had significantly smaller peak palmar moments at the coffin joint with heel wedges in the second half of stance, which appeared to be a mechanical consequence of the more flexed position of the coffin joint. Tension was increased in the extensor branches of the suspensory ligament and common digital extensor tendon on the dorsal side, and reduced in the deep digital flexor tendon and its distal accessory ligament on the palmar side. Less energy was absorbed across the coffin joint in both limbs with heel wedges. The study did not reveal changes associated with the use of heel wedges that could be interpreted as a reduction of the effects of lameness due to SDF tendinitis.The objective was to determine whether the application of 60 heel wedges was appropriate for treating horses with superficial digital flexor (SDF) tendinitis. The significant effects of the heel wedges affected the coffin joint and included a more flexed position due to the more upright orientation of the hoof segment, a reduction in the peak palmar moment and less energy absorption across the joint. Since these changes were confined to the coffin joint, they were not interpreted as being beneficial in treating lameness due to SDF tendinitis.
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Chen, Darren B., und David C. Yee. „FLEXOR DIGITORUM PROFUNDUS TENDON AVULSION THROUGH A RECURRENT ENCHONDROMA — A CASE REPORT“. Hand Surgery 06, Nr. 01 (Juli 2001): 125–26. http://dx.doi.org/10.1142/s0218810401000485.
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Flexor digitorum profundus (FDP) tendon avulsion from the distal phalanx is a well recognised injury, which usually follows a hyperextension force to a flexed distal interphalangeal (DIP) joint. It is commonly seen in contact sport athletes, with a predilection for the ring finger.2,4 Avulsion of the FDP tendon from pathological bone is an infrequent occurrence. It has, however, been reported to occur in association with an enchondroma of the distal phalanx.2,3 To our knowledge, an FDP tendon avulsion through a recurrent enchondroma has not been reported. We present the case findings of such an event.
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Tosteson, C. D. „1991 Flexner Award“. Academic Medicine 67, Nr. 2 (Februar 1992): 98. http://dx.doi.org/10.1097/00001888-199202000-00008.
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King, Jon A. „Commentary: Flexner Revisited“. Annals of Emergency Medicine 35, Nr. 6 (Juni 2000): 0624–25. http://dx.doi.org/10.1067/mem.2000.106831a.
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Bronstein, Arthur. „Stuart Berg Flexner“. Dictionaries: Journal of the Dictionary Society of North America 12, Nr. 1 (1990): 161–63. http://dx.doi.org/10.1353/dic.1990.0014.
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Kennelly, Peter J., Judith S. Bond, Bettie Sue Masters, Edward A. Dennis, Charles Brenner und Daniel M. Raben. „Desperately Seeking Flexner“. Academic Medicine 88, Nr. 10 (Oktober 2013): 1405–6. http://dx.doi.org/10.1097/acm.0b013e3182a225be.
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BÄSSLER, ULRICH. „Functional Principles of Pattern Generation for Walking Movements of Stick Insect Forelegs: The Role of the Femoral Chordotonal Organ Afferences“. Journal of Experimental Biology 136, Nr. 1 (01.05.1988): 125–47. http://dx.doi.org/10.1242/jeb.136.1.125.
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A rampwise stretch of the femoral chordotonal organ is known often to elicit a response in the active decerebrate stick insect that is termed an ‘active reaction’, and which can be considered to represent part of the step cycle. During the first part of the response, the flexor motor neurones are excited and the excitatory extensor motor neurones are inhibited, forming a positive feedback loop. When the chordotonal organ reaches a position corresponding to a flexed femur-tibia joint, the flexor motor neurones are inhibited and the extensor motor neurones are excited. In this study, extracellular and intracellular recordings showed that, during an active reaction, the excitation of the retractor unguis motor neurones usually paralleled that of the flexor motor neurones, whereas the protractor coxae motor neurones were less strongly coupled to this system. The first part of the active reaction occurred only at low stimulus velocities. At high stimulus velocities negative feedback was present. The first part therefore represents some kind of velocity-control-system for active flexions. Electrical stimulation of the nerve containing the axons of trochanteral campaniform sensilla and of the hairfield trHP decreased the likelihood that concurrent chordotonal organ stimulation would elicit an active reaction. Furthermore, most of the active reactions that occurred under these stimulus conditions involved only the flexor tibiae muscle. The results indicate that: the walking pattern generator is composed of subunits that are only loosely coupled centrally; it probably does not include a central pattern generator; and generation of an active reaction is a two-step process.
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Smith, W. H. F., und P. Wessel. „Gridding with continuous curvature splines in tension“. GEOPHYSICS 55, Nr. 3 (März 1990): 293–305. http://dx.doi.org/10.1190/1.1442837.
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A gridding method commonly called minimum curvature is widely used in the earth sciences. The method interpolates the data to be gridded with a surface having continuous second derivatives and minimal total squared curvature. The minimum‐curvature surface has an analogy in elastic plate flexure and approximates the shape adopted by a thin plate flexed to pass through the data points. Minimum‐curvature surfaces may have large oscillations and extraneous inflection points which make them unsuitable for gridding in many of the applications where they are commonly used. These extraneous inflection points can be eliminated by adding tension to the elastic‐plate flexure equation. It is straightforward to generalize minimum‐curvature gridding algorithms to include a tension parameter; the same system of equations must be solved in either case and only the relative weights of the coefficients change. Therefore, solutions under tension require no more computational effort than minimum‐curvature solutions, and any algorithm which can solve the minimum‐curvature equations can solve the more general system. We give common geologic examples where minimum‐curvature gridding produces erroneous results but gridding with tension yields a good solution. We also outline how to improve the convergence of an iterative method of solution for the gridding equations.
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Trank, T. V., C. Chen und J. L. Smith. „Forms of forward quadrupedal locomotion. I. A comparison of posture, hindlimb kinematics, and motor patterns for normal and crouched walking“. Journal of Neurophysiology 76, Nr. 4 (01.10.1996): 2316–26. http://dx.doi.org/10.1152/jn.1996.76.4.2316.
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1. Posture, hindlimb kinematics, and activity patterns of selected hindlimb muscles were compared for normal and crouched treadmill walking (0.5-0.6 m/s) for eight cats. To elicit crouched walking in which the trunk and head were lowered, cats were encouraged to walk under a light-weight Plexiglas ceiling suspended 17-20 cm above the treadmill belt. Kinematic data were obtained from high-speed cine film, and electromyograms (EMGs)-synchronized with the kinematic records-were taken from 11 hindlimb muscles. 2. The postures for the two forms of walking were distinctly different. During crouched walking, each cat lowered its entire body keeping its trunk horizontal to the treadmill belt. Also the head was lowered, with the top of the head in line with the dorsal surface of the trunk. Hip height, used as a measure for hindlimb crouch, was reduced by 30%, from an average height of 23 cm to an average height of 16 cm above the belt during the entire step cycle. 3. Average cycle periods (766 +/- 30 ms, mean +/- SD) and percentage of time devoted to swing (30%) and stance (70%) were similar for normal and crouched walking. The profiles of the hindlimb kinematics were also similar for the hip, knee, ankle, and metatarsophalangeal (MTP) joints during the step cycle, but the timing of some of the motion reversal, as well as the ranges of motion during various phases, were different at some joints for the two forms of walking. 4. During the swing phase, the transition between the flexion and extension (F-E1 reversal) occurred later in the normalized swing phase at the hip, knee, and ankle joints, and the range of flexion was increased at each joint. With greater flexion at these joints, the anatomic axis of the hindlimb (measured from hip joint to toe) was decreased and the hind paw advanced in the narrow space between the abdomen and treadmill belt. At contact, the position of the paw was less anterior to the perpendicular reference line (hip joint marker to belt) and all joints were more flexed for crouched than normal walking. 5. Throughout the stance phase, the knee and ankle joints remained significantly more flexed by 41-45 deg during crouched than normal walking. Although the hip and MTP joints started in a more flexed position at paw contact, both joints extended more during stance for crouched than normal walking, and at the time of peak extension (just before paw lift-off), the degree of extension at the hip and MTP joints was similar for both forms of walking. 6. Muscle patterns for crouched and normal walking were similar with some exceptions. The burst durations for three primary flexor muscles, the semitendinosus (knee flexor), extensor digitorum longus (EDL, ankle flexor), and flexor digitorum longus (digit flexor) were longer for crouched than normal walking, and this was consistent with the increased range and duration of flexion during the swing phase of crouched walking. Also, two muscles that normally showed mainly swing-related activity during normal walking, the EDL and the extensor digitorum brevis, had distinct stance-related bursts that occurred after midstance during crouched walking. 7. Crouched walking requires a postural change that typically occurs when cats stalk prey and when cats walk up and down sleep slopes. Postural set during walking appears to be determined by brain stem and diencephalic centers, and the postural orientation of the cat may require adjustments in the motor program provided by spinal centers for the cat to walk. The role of posture and locomotion and the adjustments in hindlimb kinematics and EMG activity patterns have been studied for forward and backward walking in the cat and now for crouched walking on the treadmill. These data will assist us in understanding the role of posture, especially crouched posture, during other walking behaviors.
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SCHWEIZER, A. „Lumbrical Tears in Rock Climbers“. Journal of Hand Surgery 28, Nr. 2 (April 2003): 187–89. http://dx.doi.org/10.1016/s0266-7681(02)00250-4.
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Performance rock climbing places high demands on the hand and may lead to specific injuries. In a “one-finger-pocket” hold, the interphalangeal joints remain in 20–40° flexion. To increase the maximum force of the holding finger by the quadriga effect, the interphalangeal joints of the adjacent fingers become almost maximally flexed. Holding a “one-finger-pocket” with the ring or small finger leads to a shift of the deep flexor tendons which increases the distance between the two adjacent origins of either the third or the fourth lumbrical. This may cause disruption and tear of that muscle. An organized haematoma in the third lumbrical was visible by ultrasonography in one of the three cases described.
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Mickovski, Slobodan B., und A. Roland Ennos. „The effect of unidirectional stem flexing on shoot and root morphology and architecture in young Pinus sylvestris trees“. Canadian Journal of Forest Research 33, Nr. 11 (01.11.2003): 2202–9. http://dx.doi.org/10.1139/x03-139.
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Mechanical stresses experienced by a tree during lateral loading may cause alterations in both shoot and root growth (thigmomorphogenesis). Many of the previous studies on this subject have concentrated on shoot responses to lateral loads, while root system responses to stresses caused by external loading have been investigated only in more recent years, and even then only rarely in trees. This study presents the effect of unidirectional stem flexure of young Scots pine (Pinus sylvestris L.) on their root system morphology and architecture. Apart from the changes to the parts of the tree aboveground, unidirectional periodical flexing induced an increase in total root cross-sectional area and larger biomass allocation to the roots parallel to the plane of flexing, which in turn resulted in a larger number of major lateral roots with larger cross-sectional area in the plane of flexing. Since there were no significant differences in root to shoot ratio or the mechanical properties of wood between flexed and unflexed trees in this study, the increase in the lateral resistance in flexed trees was associated with the greater proportion of total root biomass allocated to the proximal major lateral roots, which was an adaptive mechanism for improvement of the trees' anchorage.
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Goh, C. H., B. H. Lee und Amitabha Lahiri. „BIPHASIC MOTION OF THE MEDIAN NERVE IN THE NORMAL ASIAN POPULATION“. Hand Surgery 20, Nr. 01 (Januar 2015): 73–80. http://dx.doi.org/10.1142/s0218810415500100.
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Background: The biomechanical interaction between the median nerve and the flexor tendons is an important consideration in Carpal tunnel syndrome (CTS). We aim to quantify the displacement and compressive deformation pattern of the median nerve in various stages of finger flexion in the normal population at the inlet of the carpal tunnel. Methods: Transverse ultrasounds images were taken at the carpal tunnel inlet during full-extension, mid-flexion and full flexion. The displacement, distance, Feret's diameter, and perimeter of the median nerve were calculated and compared between each position. Results: Biphasic median nerve motion was observed, with a displacement of 2.84 ± 3.49 mm in the ulnar direction from full-extension to mid-flexion (Phase I) and a further 0.93 ± 3.04 mm from mid-flexion to full flexion (Phase II). Of 49 hands, 37 (75.5%) exhibited ulnar displacement in Phase I while 12 (24.5%) exhibited radial displacement. Feret's diameter (5.95 ± 1.08 mm) and perimeter (13.28 ± 2.09) of the median nerve were greatest in the mid-flexed position. Conclusion: In a healthy Asian population, the median nerve has a biphasic motion during finger flexion, with maximal deformation in the mid-flexed position.
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Friedlander, K., R. Ko, R. Aper, G. Breur und H. Towle. „Surgical treatment of simple syndactylism with secondary deep digital flexor tendon contracture in a Basset Hound“. Veterinary and Comparative Orthopaedics and Traumatology 20, Nr. 03 (2007): 219–23. http://dx.doi.org/10.1160/vcot-06-11-0086.
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SummaryA five-month-old, female Basset Hound was presented for lameness associated with a fused 3rd and 4th digital pad on the left hind limb (simple incomplete syndactyly), and secondary contracture of the deep digital flexure tendon of the 3rd and 4th digit. An onychectomy of the third phalanx of the third and fourth digits was performed. Following the operation, the dog gained good use of the affected limb for one month until intermittent non-weight bearing lameness developed. A second surgery was performed six months later, partially removing the second phalanx of digits three and four. Follow-up reports indicate that the dog is doing well and is without lameness. This is the first report of deep digital flexor tendon contracture and surgical treatment of this complication in canine simple syndactylism.
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DiPiro, Joseph. „The 21stCentury Abraham Flexner“. American Journal of Pharmaceutical Education 72, Nr. 4 (September 2008): 79. http://dx.doi.org/10.5688/aj720479.
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Steinberger, Lane. „Looking for Abraham Flexner“. CFA Institute Magazine 21, Nr. 6 (November 2010): 18–19. http://dx.doi.org/10.2469/cfm.v21.n6.4.
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Bonner, T. N. „Searching for Abraham Flexner“. Academic Medicine 73, Nr. 2 (Februar 1998): 160–6. http://dx.doi.org/10.1097/00001888-199802000-00014.
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Oriol-Bosch, A. „De Flexner a Bolonia“. Revista de la Fundación Educación Médica 13, Nr. 4 (2010): 193. http://dx.doi.org/10.33588/fem.134.573.
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Netting, F. Ellen. „Abraham’s Daughter: Eleanor Flexner“. Affilia 25, Nr. 2 (29.04.2010): 185–90. http://dx.doi.org/10.1177/0886109910364347.
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Carraccio, Carol L., und Robert Englander. „From Flexner to Competencies“. Academic Medicine 88, Nr. 8 (August 2013): 1067–73. http://dx.doi.org/10.1097/acm.0b013e318299396f.
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Musalem, Lindsay L., Tatjana Stankovic, Drazen Glisic, Gillian E. Cook und Tyson A. C. Beach. „Biomechanical and Electromyographic Comparisons of Isometric Trunk Flexor Endurance Test Postures: Prone Plank Versus V-Sit“. Journal of Applied Biomechanics 31, Nr. 6 (Dezember 2015): 469–75. http://dx.doi.org/10.1123/jab.2014-0197.
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The objective of this study was to investigate why holding times on 2 different tests of isometric trunk flexor endurance capacity (prone plank and v-sit) are weakly correlated. Body position and ground reaction force data from 10 men and 10 women were used to conduct static biomechanical analyses of both test postures, and bilateral activations of the rectus abdominis, internal and external obliques, latissimus dorsi, and lumbar and thoracic erector spinae were measured in a second sample of 15 men and 15 women while holding the test postures. No between-posture differences in net low back flexor moments were found (P = .111), but the lumbar spine was 28° more flexed in the v-sit than in the plank (P < .001). No between-posture differences were detected in the rectus abdominis (P = .397), external obliques (P = .204), internal obliques (P = .226), or lumbar erector spinae (P = .116) activation levels, but those of the thoracic erector spinae (P = .0253) and latissimus dorsi (P < .001) were greater in the plank than in the v-sit. Altogether, the findings suggest that differences between plank and v-sit holding times are most likely related to between-test differences in lumbar spine postures and shoulder demands.
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Schnyer, Ariela, Mirialys Gallardo, Suzanne Cox und Gary Gillis. „Indirect evidence for elastic energy playing a role in limb recovery during toad hopping“. Biology Letters 10, Nr. 7 (Juli 2014): 20140418. http://dx.doi.org/10.1098/rsbl.2014.0418.
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Elastic energy is critical for amplifying muscle power during the propulsive phase of anuran jumping. In this study, we use toads ( Bufo marinus ) to address whether elastic recoil is also involved after take-off to help flex the limbs before landing. The potential for such spring-like behaviour stems from the unusually flexed configuration of a toad's hindlimbs in a relaxed state. Manual extension of the knee beyond approximately 90° leads to the rapid development of passive tension in the limb as underlying elastic tissues become stretched. We hypothesized that during take-off, the knee regularly extends beyond this, allowing passive recoil to help drive limb flexion in mid-air. To test this, we used high-speed video and electromyography to record hindlimb kinematics and electrical activity in a hindlimb extensor (semimembranosus) and flexor (iliofibularis). We predicted that hops in which the knees extended further during take-off would require less knee flexor recruitment during recovery. Knees extended beyond 90° in over 80% of hops, and longer hops involved greater degrees of knee extension during take-off and more intense semimembranosus activity. However, knee flexion velocities during recovery were maintained despite a significant decrease in iliofibularis intensity in longer hops, results consistent with elastic recoil playing a role.