-
Brazilian Journal of Physical Therapy 2020A better understanding about the relationship between trunk and hip muscles strength and core stability may improve evaluation and interventions proposed to improve core...
BACKGROUND
A better understanding about the relationship between trunk and hip muscles strength and core stability may improve evaluation and interventions proposed to improve core stability.
OBJECTIVES
To investigate if trunk and hip muscles strength predict pelvic posterior rotation during the bridge test with unilateral knee extension.
METHODS
This is a cross-sectional study. Sixty-one healthy individuals of both sexes (age, 28±6.4 years, weight, 66.5±10.9kg, height, 167±9.5cm) performed the bridge test with unilateral knee extension. The pelvic posterior rotation during the bridge test was obtained with two-dimensional video analysis. Isometric strength of the trunk extensors and rotators, and hip abductors, external and internal rotators and extensors were measured with a hand-held dynamometer. Multiple linear regression analysis was performed to identify if the strength variables could explain the pelvic posterior rotation during the test.
RESULTS
Muscle strength predicted pelvic posterior rotation during the bridge test (r=0.54; p=0.003). Strength of the trunk rotators (p=0.045) and hip internal rotators (p=0.015) predicted reduced magnitude of pelvic posterior rotation during the bridge test, and strength of the hip extensors (p=0.003) predicted increased magnitude of pelvic posterior rotation.
CONCLUSIONS
Trunk rotators and hip internal rotators and extensors strength predict 29% of the performance during the bridge test with unilateral knee extension. The strength of these muscles should be evaluated in individuals with increased pelvic posterior rotation during the bridge test with unilateral knee extension.
Topics: Cross-Sectional Studies; Female; Hip; Humans; Male; Muscle Strength; Muscle, Skeletal; Rotation; Young Adult
PubMed: 30954371
DOI: 10.1016/j.bjpt.2019.03.001 -
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 -
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 -
Genes To Cells : Devoted To Molecular &... Mar 2019Bacterial cells, including Escherichia coli and Bacillus subtilis, continuously elongate and divide. Although the cell width is maintained during cell cycle, the...
Bacterial cells, including Escherichia coli and Bacillus subtilis, continuously elongate and divide. Although the cell width is maintained during cell cycle, the molecular mechanisms involved in its regulation remain unknown. MreB has been implicated to play a role in maintaining cell width. Several point mutations in mreB that affect cell width have been identified. The MreB protein forms clusters or polymers in the cell and moves along annular tracks perpendicular to the long axis. This rotation is coupled with peptidoglycan synthesis. Here, we focused on two MreB mutants, MreB and MreB . Cells producing MreB and MreB were thinner and thicker than WT cells, and MreB and MreB rotated faster and slower than WT MreB, respectively. We observed that the rotation rate correlated with the cell wall synthesis rate. Thus, we conclude that the velocity of MreB rotation also affects cell width, that is, the faster the MreB rotates, the thinner the cell width is.
Topics: Cell Wall; Escherichia coli; Escherichia coli Proteins; Mutation; Rotation
PubMed: 30597729
DOI: 10.1111/gtc.12667 -
Vision Research Jun 1995The recording of three-dimensional eye position has become the accepted standard in oculomotor research. In this paper we review the mathematics underlying the...
The recording of three-dimensional eye position has become the accepted standard in oculomotor research. In this paper we review the mathematics underlying the representation of three-dimensional eye movements. Rotation matrices, rotation vectors and quaternions are presented, and their relations described. The connection between search coils and rotation matrices is explained, as well as the connection between eye position and eye velocity. While examples of applications of the formulas to vestibulo-ocular research are given, the methods and mathematical analyses are also useful for studying other motor systems.
Topics: Eye Movements; Humans; Mathematics; Rotation; Time Factors
PubMed: 7660581
DOI: 10.1016/0042-6989(94)00257-m -
TheScientificWorldJournal 2014Depending on the rotational structure of Fresnel reflector, the rotation angle of the mirror was deduced under the eccentric condition. By analyzing the influence of the...
Depending on the rotational structure of Fresnel reflector, the rotation angle of the mirror was deduced under the eccentric condition. By analyzing the influence of the sun tracking rotation angle error caused by main factors, the change rule and extent of the influence were revealed. It is concluded that the tracking errors caused by the difference between the rotation axis and true north meridian, at noon, were maximum under certain conditions and reduced at morning and afternoon gradually. The tracking error caused by other deviations such as rotating eccentric, latitude, and solar altitude was positive at morning, negative at afternoon, and zero at a certain moment of noon.
Topics: Altitude; Rotation; Solar Energy; Sunlight
PubMed: 24895664
DOI: 10.1155/2014/834392 -
Knee Surgery, Sports Traumatology,... Apr 2017The purpose of this study was to identify biomechanical factors, in both reconstructed and healthy knees, that correlate with patient satisfaction after ACL...
The combination of tibial anterior translation and axial rotation into a single biomechanical factor improves the prediction of patient satisfaction over each factor alone in patients with ACL reconstructed knees.
PURPOSE
The purpose of this study was to identify biomechanical factors, in both reconstructed and healthy knees, that correlate with patient satisfaction after ACL reconstruction.
METHODS
Seventeen patients who had undergone unilateral ACL reconstruction were reviewed 9 years post-op. Patients completed subjective questionnaires and underwent manual knee laxity testing (Lachman-Trillat, KT-1000, and pivot shift) and automated laxity testing. During automated testing, both legs were rotated into external rotation and then internal rotation until peak rotational torque reached 5.65 Nm. Load-deformation curves were generated from torque and rotation data. Features of the curves were extracted for analysis. Total leg rotation and anterior laxity during KT-1000 testing were combined into a single factor (Joint Play Envelope or JPE). Patients were divided into groups based on patient satisfaction scores (Group 1: Higher Satisfaction, Group 2: Lower Satisfaction, Group 3: Unsatisfied). Load-deformation curve features and manual laxity testing results were compared between groups 1 and 2 to determine which biomechanical factors could distinguish between the groups. Diagnostic screening values were calculated for KT-1000 testing, the pivot shift test, total leg rotation and JPE.
RESULTS
During manual testing, no significant differences in biomechanical factors were found when comparing reconstructed knees in group 1 and group 2. When comparing the reconstructed and healthy knees within group 2, the reconstructed knees had a significantly higher displacement during the KT-1000 manual maximum test (p < 0.002). When considering the reconstructed knees alone, neither the result of the pivot shift test nor KT-1000 testing could distinguish between group 1 and group 2. During automated testing, there were no significant differences between the groups when comparing the reconstructed lower limbs. The healthy lower limbs in group 2 had more maximum external rotation (p < 0.02) and decreased stiffness at maximum external rotation (p < 0.02) when compared to the healthy lower limbs in group 1. Total leg rotation was unable to distinguish between group 1 and group 2. JPE could distinguish between group 1 and group 2 when considering the reconstructed limb alone (p < 0.02). All four diagnostic screening values for JPE were equal or higher than in the other criteria. JPE also showed the most significant correlation with patient satisfaction.
CONCLUSIONS
Joint Play Envelope is an objective measure that demonstrated improved predictive value as compared to other tests when used as a measure of satisfaction in patients with ACL reconstructed knees.
Topics: Anterior Cruciate Ligament Reconstruction; Female; Follow-Up Studies; Humans; Joint Instability; Knee Joint; Male; Patient Satisfaction; Retrospective Studies; Rotation
PubMed: 28299388
DOI: 10.1007/s00167-017-4497-7 -
Nihon Hoshasen Gijutsu Gakkai Zasshi 2022It is necessary to perform gantry quality assurance (QA) in high precision radiotherapy. However, the O-ring type linear accelerator (Halcyon) does not have a light...
PURPOSE
It is necessary to perform gantry quality assurance (QA) in high precision radiotherapy. However, the O-ring type linear accelerator (Halcyon) does not have a light field and laser as a reference of isocenter point. The aim of this study is to investigate the usefulness of a three-dimensional diode array detector for gantry angle QA, and an O-ring type linear accelerator.
METHOD
The gantry angle and rotational center were verified using the ArcCHECK 3D diode array on the general linear accelerator (TrueBeam) as a reference and Halcyon. The gantry angles were measured at 0, 90, 180, and 270°. The accuracy of the gantry rotational center was evaluated using rotational irradiation in the clockwise and counterclockwise directions between 181° and 179°.
RESULTS
The QA system with ArcCHECK was able to apply on the TrueBeam and Halcyon. As a result of the accuracy of the gantry angle, the maximum error of value calculated from ArcCHECK was 0.1° compared with the nominal gantry angle of Halcyon. As a result of the accuracy of the gantry rotation isocenter of Halcyon, the distance between the isocenter and the gantry rotation center was 0.45 mm and 0.41 mm in the clockwise and counterclockwise directions, respectively.
CONCLUSION
The QA system with ArcCHECK was useful for the gantry angle and the rotation center accuracy on the Halcyon.
Topics: Particle Accelerators; Radiotherapy, Intensity-Modulated; Rotation
PubMed: 35314535
DOI: 10.6009/jjrt.780303 -
Orthopaedics & Traumatology, Surgery &... Apr 2017Restoration of native head-shaft angle (HSA) is critical for treatment of proximal humerus fracture. However, HSA has not been properly investigated according to the...
INTRODUCTION
Restoration of native head-shaft angle (HSA) is critical for treatment of proximal humerus fracture. However, HSA has not been properly investigated according to the humeral rotation. This study was designed to analyze the relationship between the humeral rotation and the HSA at 1° increments, and clarify its serial changing pattern according to the humeral rotation.
HYPOTHESIS
The angulation of HSA would be undervalued when the humerus is being rotated externally and it would be overvalued when it is being rotated internally.
MATERIALS AND METHODS
Eight dried cadaveric normal humeri were CT scanned. They were analyzed using computer-aided design with a standardized neutral position. HSA was the angle between the humeral shaft axis (SA) and the humeral head axis (HA). SA and HA were the best-fit lines through center of all the best-fitting circles in every cross section along the humeral shaft and within the humeral head, respectively. Each 3D model was rotated 30° internally and 45° externally relatives to the SA at 1° increments with the camera was fixed at antero-posterior view of neutral position. Angulation of HSA in every rotational degree was documented as ratio relatives to the angulation of HSA in neutral position.
RESULTS
The average HSA at neutral position was 133±1.93°. HSA was underestimated by 8±1.9% and it was overestimated by 20±5.1% at the maximum external rotation (ER) and internal rotation (IR), respectively. HSA was underestimated by 1% in every 5.8° of ER and overestimated by 1% in every 1.5° of IR. Rotational misalignments within 10° of IR and 18° of ER could be tolerated (P>.05).
CONCLUSIONS
HSA was underestimated at ER and was overestimated at IR. This information could be useful for surgeons in restoring the native HSA for treatment of proximal humerus fracture.
TYPE OF STUDY
Basic research study.
Topics: Biomechanical Phenomena; Cadaver; Diaphyses; Humans; Humeral Head; Rotation; Shoulder Joint; Tomography, X-Ray Computed
PubMed: 28082108
DOI: 10.1016/j.otsr.2016.11.015 -
Journal of Shoulder and Elbow Surgery Jun 2010Rotator cuff tears are common shoulder problems whose propagation is difficult to predict because of the structural and mechanical inhomogeneity of the supraspinatus... (Review)
Review
BACKGROUND
Rotator cuff tears are common shoulder problems whose propagation is difficult to predict because of the structural and mechanical inhomogeneity of the supraspinatus tendon. We have previously shown that the supraspinatus and infraspinatus tendons interact mechanically when the supraspinatus tendon is intact or exhibits a full-thickness tear, so that an increase in supraspinatus tendon strain is paralleled by an increase in infraspinatus tendon strain. Such interaction is critical and suggests that an increase in infraspinatus tendon strain that accompanies an increase in supraspinatus tendon strain may shield the supraspinatus tendon from further injury, but increase the risk of injury to the infraspinatus tendon. In this study, the mechanical interactions between the supraspinatus and infraspinatus tendons were evaluated for the commonly occurring supraspinatus tendon partial-thickness tears through a range of rotation angles.
METHODS
For each joint rotation and supraspinatus tendon tear size evaluated, the supraspinatus tendon was loaded, and images corresponding to 5 N, 30 N, 60 N, and 90 N of supraspinatus tendon load were isolated for the speckle painted supraspinatus and infraspinatus tendons. A region of interest outlining the insertion site was isolated and displacements between the 5 N loaded image and each of the others were measured, from which normalized average principal strains were quantified in both tendons.
RESULTS
The observed effect on infraspinatus tendon strain paralleled that observed on strain in the supraspinatus tendon. Introducing a supraspinatus tendon partial-thickness tear and increasing load caused an increase in normalized average maximum and a decrease in normalized average minimum principal strain in the infraspinatus tendon. Increasing rotation angle from internal to external rotation caused a general decrease in normalized average maximum and increase in normalized average minimum principal strain in both tendons.
CONCLUSION
The supraspinatus and infraspinatus tendons mechanically interact for the intact and partially torn supraspinatus tendons for neutral and rotated glenohumeral joint.
Topics: Biomechanical Phenomena; Humans; Range of Motion, Articular; Rotation; Rotator Cuff; Rotator Cuff Injuries; Rupture; Shoulder Injuries; Shoulder Joint; Sprains and Strains; Tendon Injuries; Trauma Severity Indices
PubMed: 20080051
DOI: 10.1016/j.jse.2009.10.003