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Journal of Shoulder and Elbow Surgery Feb 2021The rotator cuff (RC) and the deltoid muscle are 2 synergistic units that enable the functionally demanding movements of the shoulder. A number of biomechanical studies...
BACKGROUND
The rotator cuff (RC) and the deltoid muscle are 2 synergistic units that enable the functionally demanding movements of the shoulder. A number of biomechanical studies assume similar force contribution of the force couple (RC and deltoid) over the whole range of motion, whereas others propose position-dependent force distribution. There is a lack of in vivo data regarding the deltoid's contribution to shoulder flexion and abduction strength. This study aimed to create reliable in vivo data quantifying the deltoid's contribution to shoulder flexion and abduction strength throughout the range of motion.
METHODS
Active range of motion and isometric muscle strength of shoulder abduction and flexion in 0°, 30°, 60°, 90°, and 120° of abduction/flexion as well as internal and external rotation in 0° and 90° of abduction were obtained in 12 healthy volunteers on the dominant arm before and after an ultrasound-guided isolated axillary nerve block. Needle electromyography was performed before and after the block to confirm deltoid paralysis. Radiographs of the shoulder and an ultrasonographic examination were used to exclude relevant shoulder pathologies.
RESULTS
Active range of motion showed a minimal to moderate reduction to 94% and 88% of the preintervention value for abduction and flexion. Internal and external rotation amplitude was not impaired. The abduction strength was significantly reduced to 76% at 0° (P = .002) and to 25% at 120° (P < .001) of abduction. The flexion strength was significantly reduced to 64% at 30° (P < .001) and to 30% at 120° (P < .001) of flexion. The strength reduction was linear, depending on the flexion/abduction angle. The maximal external rotation strength showed a significant decrease to 53% in 90° (P < .001) of abduction, whereas in adduction no strength loss was observed (P = .09). The internal rotation strength remained unaffected in 0° and 90° of abduction (P = .28; P = .13).
CONCLUSION
The deltoid shows a linear contribution to maximal shoulder strength depending on the abduction or flexion angle, ranging from 24% in 0° to 75% in 120° of abduction and from 11% in 0° to 70% in 120° of flexion, respectively. The overall contribution to abduction strength is higher than to flexion strength. The combination of deltoid muscle and teres minor contributes about 50% to external rotation strength in 90° of abduction. The internal rotation strength is not influenced by a deltoid paralysis. This study highlights the position-dependent contribution of the shoulder muscles to strength development and thereby provides an empirical approach to better understand human shoulder kinematics.
Topics: Biomechanical Phenomena; Deltoid Muscle; Humans; Range of Motion, Articular; Rotation; Rotator Cuff; Shoulder; Shoulder Joint
PubMed: 32540315
DOI: 10.1016/j.jse.2020.05.023 -
Journal of Orthopaedic Surgery and... Aug 2014This work aimed to assess tibial rotations, meniscal movements, and morphological changes during knee flexion and extension using kinematic magnetic resonance imaging...
OBJECTIVE
This work aimed to assess tibial rotations, meniscal movements, and morphological changes during knee flexion and extension using kinematic magnetic resonance imaging (MRI).
METHODS
Thirty volunteers with healthy knees were examined using kinematic MRI. The knees were imaged in the transverse plane with flexion and extension angles from 0° to 40° and 40° to 0°, respectively. The tibial interior and exterior rotation angles were measured, and the meniscal movement range, height change, and side movements were detected.
RESULTS
The tibia rotated internally (11.55° ± 3.20°) during knee flexion and rotated externally (11.40° ± 3.0°) during knee extension. No significant differences were observed between the internal and external tibial rotation angles (P > 0.05), between males and females (P > 0.05), or between the left and right knee joints (P > 0.05). The tibial rotation angle with a flexion angle of 0° to 24° differed significantly from that with a flexion angle of 24° to 40° (P < 0.01). With knee flexion, the medial and lateral menisci moved backward and the height of the meniscus increased. The movement range was greater in the anterior horn than in the posterior horn and greater in the lateral meniscus than in the medial meniscus (P < 0.01). During backward movements of the menisci, the distance between the anterior and posterior horns decreased, with the decrease more apparent in the lateral meniscus (P < 0.01). The side movements of the medial and lateral menisci were not obvious, and a smaller movement range was found than that of the forward and backward movements.
CONCLUSION
Knee flexion and extension facilitated internal and external tibial rotations, which may be related to the ligament and joint capsule structure and femoral condyle geometry.
Topics: Adult; Aged; Biomechanical Phenomena; Female; Humans; Knee Joint; Magnetic Resonance Imaging; Male; Menisci, Tibial; Middle Aged; Rotation; Tibia
PubMed: 25142267
DOI: 10.1186/s13018-014-0065-8 -
Computational Intelligence and... 2022The goal of this research was to provide a new approach for analyzing orthodontic teeth arrangement inside oral depending on the rotation matrix computation and...
The goal of this research was to provide a new approach for analyzing orthodontic teeth arrangement inside oral depending on the rotation matrix computation and resistance detection. The present method includes the following operations within a certain therapy period: first three-dimensional positions of the tooth were evaluated with a pierced laser beam and a three-dimensional system of surface-scanning. Second, the three-dimensional shape data was automatically registered at maxillary 1 molars, and methods of coordinate had been normalized. Third, a translation vector and rotation matrix had been evaluated from automatic registration of two position data of a particular tooth. Fourth, the limited spiral axes of teeth had been measured as the zero rotational dislocation locus; and impressions for a model of the dental cast had been taken at five different points: shortly before and after device was fitted, and ten days, one month, and two months after the treatment started. The results showed that existing analysis approach could more quickly classify a specific tooth's movement by spinning all over and translating along a finite helical axis. It can provide statistical visual three-dimensional data on complex tooth arrangement throughout orthodontic therapy.
Topics: Rotation; Tooth Movement Techniques
PubMed: 35634084
DOI: 10.1155/2022/4675181 -
Journal of Visualized Experiments : JoVE Mar 2017Classical techniques for investigating the Rayleigh-Taylor instability include using compressed gasses, rocketry or linear electric motors to reverse the effective...
Classical techniques for investigating the Rayleigh-Taylor instability include using compressed gasses, rocketry or linear electric motors to reverse the effective direction of gravity, and accelerate the lighter fluid toward the denser fluid. Other authors have separated a gravitationally unstable stratification with a barrier that is removed to initiate the flow. However, the parabolic initial interface in the case of a rotating stratification imposes significant technical difficulties experimentally. We wish to be able to spin-up the stratification into solid-body rotation and only then initiate the flow in order to investigate the effects of rotation upon the Rayleigh-Taylor instability. The approach we have adopted here is to use the magnetic field of a superconducting magnet to manipulate the effective weight of the two liquids to initiate the flow. We create a gravitationally stable two-layer stratification using standard flotation techniques. The upper layer is less dense than the lower layer and so the system is Rayleigh-Taylor stable. This stratification is then spun-up until both layers are in solid-body rotation and a parabolic interface is observed. These experiments use fluids with low magnetic susceptibility, |χ| ~ 10 - 10, compared to a ferrofluids. The dominant effect of the magnetic field applies a body-force to each layer changing the effective weight. The upper layer is weakly paramagnetic while the lower layer is weakly diamagnetic. When the magnetic field is applied, the lower layer is repelled from the magnet while the upper layer is attracted towards the magnet. A Rayleigh-Taylor instability is achieved with application of a high gradient magnetic field. We further observed that increasing the dynamic viscosity of the fluid in each layer, increases the length-scale of the instability.
Topics: Computer Simulation; Magnetics; Models, Theoretical; Rheology; Rotation; Viscosity
PubMed: 28287561
DOI: 10.3791/55088 -
Sensors (Basel, Switzerland) Apr 2022Among various energy harvesting technologies, triboelectricity is an epoch-making discovery that can convert energy loss caused by the mechanical vibration or friction...
Among various energy harvesting technologies, triboelectricity is an epoch-making discovery that can convert energy loss caused by the mechanical vibration or friction of parts into energy gain. As human convenience has emerged as an important future value, wireless devices have attracted widespread attention; thus, it is essential to extend the duration and lifespan of batteries through energy harvesting or the application of self-powered equipment. Here, we report a transistor, in which the gate rotates and rubs against the dielectric and utilizes the triboelectricity generated rather than the switching voltage of the transistor. The device is a triboelectric transistor with a simple structure and is manufactured using a simple process. Compared to that at the stationary state, the output current of the triboelectric transistor increased by 207.66 times at the maximum rotation velocity. The approach reported in this paper could be an innovative method to enable a transistor to harness its own power while converting energy loss in any rotating object into harvested energy.
Topics: Electric Power Supplies; Humans; Nanotechnology; Rotation
PubMed: 35590998
DOI: 10.3390/s22093309 -
Dento Maxillo Facial Radiology May 2019To evaluate the influence of rotation degree and field of view (FOV) size on the amount of artefacts produced in cone beam CT (CBCT) images.
OBJECTIVE
To evaluate the influence of rotation degree and field of view (FOV) size on the amount of artefacts produced in cone beam CT (CBCT) images.
METHODS
A cylindrical wax utility phantom, with a metallic sample in its interior, was scanned with two FOV sizes (100 x 100 and 40 x 40 mm) and in full (360°) and partial (~180°) rotations. After the acquisitions, images were objectively assessed in the ImageJ software, obtaining the standard deviation in areas around the metal sample. The influence of artefacts produced by the several FOVs and rotation degrees was compared by two-way analysis of variance (α = 0.05).
RESULTS
The images obtained with a large FOV presented a higher amount of noise compared to a restricted FOV, both for partial ( = 0.0037) and full ( = 0.0023) rotation degrees. For images obtained with a restricted FOV, full rotation resulted in images with less noise ( = 0.0259). For images obtained with large FOV, there was no statistically significant difference ( = 0.1494) in noise for both rotation protocols.
CONCLUSIONS
As there were no significant differences in the amount of artefacts in rotation protocols for large FOVs, the partial rotation can be indicated due to its lower exposure to radiation. For acquiring images with restricted FOVs, the full rotation is recommended.
Topics: Artifacts; Cone-Beam Computed Tomography; Phantoms, Imaging; Rotation
PubMed: 30563362
DOI: 10.1259/dmfr.20180340 -
Proceedings of the National Academy of... Jun 2020Arguably the most foundational principle in perception research is that our experience of the world goes beyond the retinal image; we perceive the distal environment...
Arguably the most foundational principle in perception research is that our experience of the world goes beyond the retinal image; we perceive the distal environment itself, not the proximal stimulation it causes. Shape may be the paradigm case of such "unconscious inference": When a coin is rotated in depth, we infer the circular object it truly is, discarding the perspectival ellipse projected on our eyes. But is this really the fate of such perspectival shapes? Or does a tilted coin retain an elliptical appearance even when we know it's circular? This question has generated heated debate from Locke and Hume to the present; but whereas extant arguments rely primarily on introspection, this problem is also open to empirical test. If tilted coins bear a representational similarity to elliptical objects, then a circular coin should, when rotated, impair search for a distal ellipse. Here, nine experiments demonstrate that this is so, suggesting that perspectival shapes persist in the mind far longer than traditionally assumed. Subjects saw search arrays of three-dimensional "coins," and simply had to locate a distally elliptical coin. Surprisingly, rotated circular coins slowed search for elliptical targets, even when subjects clearly knew the rotated coins were circular. This pattern arose with static and dynamic cues, couldn't be explained by strategic responding or unfamiliarity, generalized across shape classes, and occurred even with sustained viewing. Finally, these effects extended beyond artificial displays to real-world objects viewed in naturalistic, full-cue conditions. We conclude that objects have a remarkably persistent dual character: their objective shape "out there," and their perspectival shape "from here."
Topics: Cues; Depth Perception; Form Perception; Humans; Philosophy; Rotation
PubMed: 32532920
DOI: 10.1073/pnas.2000715117 -
Journal of the Optical Society of... May 2013We present an efficient and accurate algorithm for principal component analysis (PCA) of a large set of two-dimensional images and, for each image, the set of its...
We present an efficient and accurate algorithm for principal component analysis (PCA) of a large set of two-dimensional images and, for each image, the set of its uniform rotations in the plane and its reflection. The algorithm starts by expanding each image, originally given on a Cartesian grid, in the Fourier-Bessel basis for the disk. Because the images are essentially band limited in the Fourier domain, we use a sampling criterion to truncate the Fourier-Bessel expansion such that the maximum amount of information is preserved without the effect of aliasing. The constructed covariance matrix is invariant to rotation and reflection and has a special block diagonal structure. PCA is efficiently done for each block separately. This Fourier-Bessel-based PCA detects more meaningful eigenimages and has improved denoising capability compared to traditional PCA for a finite number of noisy images.
Topics: Algorithms; Escherichia coli; Fourier Analysis; Image Processing, Computer-Assisted; Principal Component Analysis; Ribosomes; Rotation
PubMed: 23695317
DOI: 10.1364/JOSAA.30.000871 -
Scientific Reports Nov 2022Mechanical precision corn seed-metering planter has a compact structure, missed and repeated seeding advantages during high-speed operation. In this regard, the current...
Mechanical precision corn seed-metering planter has a compact structure, missed and repeated seeding advantages during high-speed operation. In this regard, the current research study focuses on the development of a corn seed planter that features an inclined seed-metering device. The spatial layout of the seed-metering device is optimized to change the seed-filling mode to meet the needs of high-speed operation. Firstly, the mechanical characteristics and seeds in the metering device chamber were analyzed, and then the seed-filling stress model was established. Secondly, a mechanical model for corn seed particles was developed for virtual simulation tests and numerical analysis using the discrete element method (DEM) and EDEM software. Moreover, a quadratic rotating orthogonal center combination test was implemented by setting the inclination angle of seed-metering device θ(A), machine ground speed v(B), and rotation speed of metering disc n(C) as the influence factors, with the missed seeding rate M and the seed-filling stress S as the evaluation indices. The results indicated that the most significant factors affecting the missed seeding rate, seed-filling stress, S, were the rotation speed of the metering disc (n) > machine ground speed (v) > inclination angle of the metering disc (θ) and inclination angle of the metering device (θ) > rotation speed of the metering disc (n) > machine ground speed (v), respectively. However, the field verification test shows that the optimized corn seed-metering planter achieved mean values of M = 4.33, Q(qualified seeding rate) = 92.83%, and R(repeated seeding rate) = 2.84%, with average relative errors of 1.17% compared to the simulation tests and the accuracy and effectiveness of the DEM simulation model was verified. Therefore, the developed corn seed-metering device meets the industry standards and operation requirements for precise corn sowing, and technical support can be given for future studies of similar precision seeding equipment.
Topics: Zea mays; Seeds; Computer Simulation; Rotation; Software
PubMed: 36371456
DOI: 10.1038/s41598-022-23993-1 -
Studies in History and Philosophy of... Aug 2021Rotation is a challenging riddle for the relationalist. In early versions of the absolute-relational debate for example, Newton's rotating bucket poured cold water on...
Rotation is a challenging riddle for the relationalist. In early versions of the absolute-relational debate for example, Newton's rotating bucket poured cold water on the relationalist position. While the parameters of the debate have changed, a more recent analysis in 1999 by Belot proclaimed rotation to be "the downfall of relationalism." In this paper, we provide a relational response to the riddle of rotation. We present a theory that, contrary to orthodoxy, can account for all rotational effects without introducing, as the absolutist does, a fixed standard of rotation. Instead, our theory posits a universal SO(3) charge that plays the role of global angular momentum and couples to inter-particle relations via terms commonly seen in standard gauge theories such as electromagnetism and the Standard Model of particle physics. Our theory makes use of an enriched form of relationalism: it adds an SO(3) structure to the traditional relational description. Our construction is made possible by the modern tools of gauge theory, which reveal a simple relational law describing rotational effects. In this way, we can save all the phenomena of Newtonian mechanics using conserved charges and relationalism. In a second paper, we will further explore the ontological and explanatory implications of the theory developed here.
Topics: Electromagnetic Phenomena; Physics; Rotation
PubMed: 34171550
DOI: 10.1016/j.shpsa.2021.05.006