Mechanical loading of primate fingers on vertical rock surfaces

Mechanical loading of finger bones (phalanges) can induce angular curvature, which benefits arboreal primates by dissipating forces and economising the recruitment of muscles during climbing. The recent discovery of extremely curved phalanges in a hominin, Homo naledi, is puzzling, for it suggests life in an arboreal milieu, or, alternatively, habitual climbing on vertical rock surfaces. The importance of climbing rock walls is attested by several populations of baboons, one of which uses a 7-m vertical surface to enter and exit Dronkvlei Cave, De Hoop Nature Reserve, South Africa. This rock surface is an attractive model for estimating the probability of extreme mechanical loading on the phalanges of rock-climbing primates. Here we use three-dimensional photogrammetry to show that 82–91% of the climbable surface would generate high forces on the flexor tendon pulley system and severely load the phalanges of baboons and H. naledi. If such proportions are representative of vertical rock surfaces elsewhere, it may be sufficient to induce stress-mitigating curvature in the phalanges of primates.

Cable Pulley Test

<div>This report will investigate the interactions regarding a cable pulley system within the nose landing gear. There is the possibility of tension drops occurring within this system. A test was done to determine the tension values within the system, this test was to isolate two possibilities that could</div><div>cause the tension drop. These two possibilities were structural deflection within the nose landing gear or the tension loss occurring within the pulley cluster. With this test it was found that there are in fact tension drops when the pulley cluster was used on a rigid system without the structural deformations of the nose landing gear. There are some discrepancies where a basic cable test was done without the pulley cluster and no tension drop was found. This would lead to an investigation to occur after this test</div><div>to determine why the tension drop happens with the cable and pulley cluster interaction. Some reasons to the tension drop within the pulley cluster would be unwinding of the cable as well as deformation occurring. There is however no definite answer for the tension drop as the observation was difficult within such a confined and small space of the pulley cluster.</div>

Cable Pulley Test

<div>This report will investigate the interactions regarding a cable pulley system within the nose landing gear. There is the possibility of tension drops occurring within this system. A test was done to determine the tension values within the system, this test was to isolate two possibilities that could</div><div>cause the tension drop. These two possibilities were structural deflection within the nose landing gear or the tension loss occurring within the pulley cluster. With this test it was found that there are in fact tension drops when the pulley cluster was used on a rigid system without the structural deformations of the nose landing gear. There are some discrepancies where a basic cable test was done without the pulley cluster and no tension drop was found. This would lead to an investigation to occur after this test</div><div>to determine why the tension drop happens with the cable and pulley cluster interaction. Some reasons to the tension drop within the pulley cluster would be unwinding of the cable as well as deformation occurring. There is however no definite answer for the tension drop as the observation was difficult within such a confined and small space of the pulley cluster.</div>

Comprehending Optimality of Finger Flexor Tendon Pulley System using Computational Analysis

It is rare that existing prosthetic/orthotic designs are based on kinetostatics of a biological finger, especially its tendon- pulley system (TPS). Whether a biological TPS is optimal for use as a reference, say for design purposes, and if so in what sense, is also relatively unknown. We expect an optimal TPS to yield high range of flexion while operating with lower tendon tension, bowstringing, and pulley stresses. To gain insight into the TPS designs, we present a parametric study which is then used to determine optimal TPS configurations for the flexor mechanism. A compliant, flexure-based computational model is developed and simulated using the pseudo rigid body method, with various combinations of pulley/tendon attachment point locations, pulley heights, and widths. Results suggest that three distinct types of TPS configurations corresponding to single stiff pulley, or two stiff pulleys, or one stiff and one flexible-inextensible pulley per phalange can be optimal. For a TPS configuration similar to a biological one, the distal pulleys on the proximal and intermediate phalanges need to be like flexible-inextensible string loops that effectively model the behavior of joint and cruciate pulleys. We reckon that a biological flexor TPS may have evolved to maximize flexion range with minimum possible actuation tension, bowstringing and pulley stress. Our findings may be useful in not only developing efficient hand devices, but also in improving TPS reconstruction surgery procedures.

Psoriatic Dactylitis: Current Perspectives and New Insights in Ultrasonography and Magnetic Resonance Imaging

Dactylitis, one of the most typical features of psoriatic arthritis (PsA), is the diffuse swelling of the digits and is determined by the involvement of different anatomic structures, including: the subcutaneous fibrous tissue “accessory pulley” system; flexor tendons, with their related structures; the articular synovium; the small enthesis of the hands. Dactylitis is currently considered both a marker of disease activity and severe prognosis and its importance in PsA is emphasized by the inclusion in the classification criteria of PsA. This review focuses on the role of imaging in the management of PsA patients with dactylitis in clinical practice and in a research setting. Furthermore, imaging could be a valuable tool to assist in unravelling some of the underlying mechanisms of the onset and chronicization of dactylitis in PsA patients.

Using a simple rope-pulley system that mechanically couples the arms, legs, and treadmill reduces the metabolic cost of walking

Background Emphasizing the active use of the arms and coordinating them with the stepping motion of the legs may promote walking recovery in patients with impaired lower limb function. Yet, most approaches use seated devices to allow coupled arm and leg movements. To provide an option during treadmill walking, we designed a rope-pulley system that physically links the arms and legs. This arm-leg pulley system was grounded to the floor and made of commercially available slotted square tubing, solid strut channels, and low-friction pulleys that allowed us to use a rope to connect the subject’s wrist to the ipsilateral foot. This set-up was based on our idea that during walking the arm could generate an assistive force during arm swing retraction and, therefore, aid in leg swing. Methods To test this idea, we compared the mechanical, muscular, and metabolic effects between normal walking and walking with the arm-leg pulley system. We measured rope and ground reaction forces, electromyographic signals of key arm and leg muscles, and rates of metabolic energy consumption while healthy, young subjects walked at 1.25 m/s on a dual-belt instrumented treadmill (n = 8). Results With our arm-leg pulley system, we found that an assistive force could be generated, reaching peak values of 7% body weight on average. Contrary to our expectation, the force mainly coincided with the propulsive phase of walking and not leg swing. Our findings suggest that subjects actively used their arms to harness the energy from the moving treadmill belt, which helped to propel the whole body via the arm-leg rope linkage. This effectively decreased the muscular and mechanical demands placed on the legs, reducing the propulsive impulse by 43% (p < 0.001), which led to a 17% net reduction in the metabolic power required for walking (p = 0.001). Conclusions These findings provide the biomechanical and energetic basis for how we might reimagine the use of the arms in gait rehabilitation, opening the opportunity to explore if such a method could help patients regain their walking ability. Trial registration: Study registered on 09/29/2018 in ClinicalTrials.gov (ID—NCT03689647).

The System Modification of Transmission on The RCWS Prototype UGV Robot (Unmanned Ground Vehicle)

An automotive transmission system is a system that has the function for conversion torsion and the rapidity (rotation) from the torsion machine and it has a different rapidity to keep on to the last activator. This conversion changes the high rotation speed becomes lower, but it has more energy conversely. The highest torsion in certain machines generally occurs in a half from the limit from the machine rotation which allowed, while the vehicle needs the highest torsion start from it could be moved. The purpose of this study is to modify the accuracy and the exact transmission, so that the activator transmission which uses a pulley system (part of the automobile chassis) and belt will have a gentle rotation by activator use motor stepper with more energy in it. This machine works by having a battery to supply electricity to the motor stepper, then it is controlled by azimuth and elevation moving control so that transmission of weapon bipod will move with elevation-100 s/d 600 degrees. Azimuth moving control will be pressed so it will move the motor stepper and make the weapon move to 360 degrees. The result of the rotation of the motor will move gently and the comparison between use motor DC gearbox which not really soft at the rotation itself.

Soft tissue abnormalities in Wassel Type VI radial polydactyly: a detailed anatomical study

Wassel VI radial polydactyly is associated with metacarpal adduction and radial deviation of the metacarpophalangeal joint of the ulnar duplicate. The soft tissue abnormalities responsible for these deformities were characterized using preoperative multi-planar three-dimensional ultrasound and intraoperative observation in four patients. In all patients, the abductor pollicis brevis and superficial head of the flexor pollicis brevis inserted into the radial first metacarpal, whereas the adductor pollicis and deep head of the flexor pollicis brevis inserted into the ulnar thumb. Aberrant location of the flexor pollicis longus and absence of the A1 pulley system was associated with severe radial deviation. An additional superficial thenar muscle along the ulnar metacarpal was associated with minimal metacarpal adduction. Uneven forces on the ulnar duplicate could be associated with these characteristic deformities and joint instability. Knowledge of these abnormalities allows better planning of surgery and further insight into this rare radial polydactyly configuration. Level of evidence: II