Torsional Rotation Research Articles

The prototype BS-II for computer measurement of biomechanical characteristics of the human cadaverous lumbar spine

BackgroundThe new second-generation computer system BS-II (Bio-Spine-II) based on the National Instruments’ development environment has been designed and constructed for evaluating the stability of various surgical fixative methods of the cadaverous lumbar spine (L1–L5). BS-II holds the measured sample using aluminum fixtures and using four computer-controlled stepper motors; it performs a circular movement (warm up of the specimen), programmatically driven extension (back bend), right and left lateral flexion (lateral bend), left and right axial torsion (rotation), and axial compression (pressure). Four strain gauges are used to measure the stiffness of the sample. The movement of individual components (vertebrae) is contactlessly monitored by two CCD (charge couple device) cameras. The obtained data are in digital form continuously stored in the computer memory for further processing.MethodsThe functionality of the equipment was verified on the cadaverous specimen of the human spine. The stiffness of the sample was measured by strain gauges, and the results were processed using linear regression analysis. Movements of vertebrae were determined by circular discs covered with appropriate patterns. The discs have been linked with the respective vertebrae and were contactlessly monitored by two CCD (charge couple device) cameras and evaluated using digital image processing methods and 2D digital FFT (fast Fourier transformation). Direction and displacement of the individual components were determined by the band of the calculated spectrum. The new device BS-II is controlled by a modifiable computer program designed in the National Instruments’ development environment which allows statistical processing of the sample, including its warming up.ResultsThe computer system BS-II for measurement of biomechanical properties of the spine sample was designed. Functionality of the device was verified by implementation of LUMIR XLIF CAGE implant into a cadaver sample of the human spine. Comparison of the rigidity of the intact and stabilized sample is shown in the graphs of article. The achieved results contributed to certification of the implant into the surgical practice.ConclusionThe designed computer BS-II system is designed for biomechanical measurements of the lumbar part of the human spine, especially for verification of surgical fixation methods. The system is based on the knowledge and experience with a manually operated measuring device designed by Palacky University Olomouc. The computer programmatic control allows the user to change the conditions and parameters of the measurement procedure in a planned way, which allows the results to be processed in, among other things, a statistical way.If suitable models are used (3D printing), the BS-II system can be used to verify procedures for surgical stabilization of the spine in the training of future doctors.The obtained data of stiffness and image information are stored in digital form and can be used for next offline sophisticated study of biomechanical properties of specimens (accurate vertebral geometry, statistical processing, 3D printing, etc.).The usefulness of the BS-II system is demonstrated in the case of biomechanical analysis of the implantation of LUMIR XLIF CAGE implant to a human cadaver specimen of the spine.

Ocular torsion is related to perceived motion-induced position shifts.

Ocular torsion (i.e., rotations of the eye about the line of sight) can be induced by visual rotational motion. It remains unclear whether and how such visually induced torsion is related to perception. By using the flash-grab effect, an illusory position shift of a briefly flashed stationary target superimposed on a rotating pattern, we examined the relationship between torsion and perception. In two experiments, 25 observers reported the perceived location of a flash while their three-dimensional eye movements were recorded. In Experiment 1, the flash coincided with a direction reversal of a large, centrally displayed, rotating grating. The grating triggered visually induced torsion in the direction of stimulus rotation. The magnitude of torsional eye rotation correlated with the illusory perceptual position shift. To test whether torsion caused the illusion, in Experiment 2, the flash was superimposed on two peripheral gratings rotating in opposite directions. Even though torsion was eliminated, the illusory position shift persisted. Despite the lack of a causal relationship, the torsion-perception correlations indicate a close link between both systems, either through similar visual-input processing or a boost of visual rotational signal strength via oculomotor feedback.

Rotational spectrum of isotopic methyl mercaptan, 13CH3SH, in the laboratory and towards Sagittarius B2(N2)

Methyl mercaptan (CH3SH) is a known interstellar molecule with abundances high enough that the detection of some of its minor isotopologues is promising. The present study aims to provide accurate spectroscopic parameters for the 13CH3SH isotopologue to facilitate its identification in the interstellar medium at millimetre and submillimetre wavelengths. Through careful analysis of recent CH3SH spectra from 49–510 GHz and 1.1–1.5 THz recorded at natural isotopic composition, extensive assignments were possible not only for the ground torsional state of 13CH3SH, but also in the first and second excited states. The torsion–rotation spectrum displays complex structure due to the large-amplitude internal rotation of the 13CH3 group, similar to the main and other minor isotopic species of methyl mercaptan. The assigned transition frequencies have been fitted to within experimental error with a 52-parameter model employing the RAM36 programme. With predictions based on this fit, 13CH3SH was searched for in spectra from the Atacama Large Millimetre/sub-millimetre Array (ALMA) towards the Galactic centre source Sgr B2(N2). Several transitions were expected to be observable, but all of them turned out to be severely blended with emission from other species, which prevents us from identifying 13CH3SH in this source.

Dynamic modeling for rotating composite Timoshenko beam and analysis on its bending-torsion coupled vibration

A formulation is presented for steady-state dynamic responses of rotating bending-torsion coupled composite Timoshenko beams (CTBs) subjected to distributed and/or concentrated harmonic loadings. The separation of cross section's mass center from its shear center and the introduced coupled rigidity of composite material lead to the bending-torsion coupled vibration of the beams. Considering those two coupling factors and based on Hamilton's principle, three partial differential non-homogeneous governing equations of vibration with arbitrary boundary conditions are formulated in terms of the flexural translation, torsional rotation and angle rotation of cross section of the beams. The parameters for the damping, axial load, shear deformation, rotation speed, hub radius and so forth are incorporated into those equations of motion. Subsequently, the Green's function element method (GFEM) is developed to solve these equations in matrix form, and the analytical Green's functions of the beams are given in terms of piecewise functions. Using the superposition principle, the explicit expressions of dynamic responses of the beams under various harmonic loadings are obtained. The present solving procedure for Timoshenko beams can be degenerated to deal with for Rayleigh and Euler beams by specifying the values of shear rigidity and rotational inertia. Cantilevers with bending-torsion coupled vibration are given as examples to verify the present theory and to illustrate the use of the present formulation. The influences of rotation speed, bending-torsion couplings and damping on the natural frequencies and/or shape functions of the beams are performed. The steady-state responses of the beam subjected to external harmonic excitation are given through numerical simulations. Remarkably, the symmetric property of the Green's functions is maintained for rotating bending-torsion coupled CTBs, but there will be a slight deviation in the numerical calculations.

Effect of Building Height on Torsional Rotation of Base Isolated Structures

The effect of height variation of a base isolated building on torsional response has been studied in the paper Also response of lead rubber and friction pendulum base isolator on torsional rotation has been compared. For the study, building rests on friction pendulum system (FPS) and lead rubber bearing (LRB) has been considered. The height of the building is varied successively and subjected to bi-directional seismic excitation. The torsional response of isolated structure is studied for each increment in the storey height for both LRB and FPS isolators and compared with fixed base structure. The result indicates that, base isolated structures reduces torsional rotation. It is also found that torsional rotation for buildings of ten to fifteen stores have significant reduction compared to other models considered in present study. Beyond this, the effectiveness reduces. It is also observed that FPS base isolator has effectively reduced torsional rotation when compared to LRB.

CT-based study of vertebral and intravertebral rotation in right thoracic adolescent idiopathic scoliosis

PurposeTo define the longitudinal rotation axis around which individual vertebrae rotate, and to establish the various extra- and intravertebral rotation patterns in thoracic adolescent idiopathic scoliosis (AIS) patients, for better understanding of the 3D development of the rotational deformity.MethodsSeventy high-resolution CT scans from an existing database of thoracic AIS patients (Cobb angle: 46°–109°) were included to determine the vertebral axial rotation, rotation radius, intravertebral axial rotation, and local mechanical torsion for each spinal level, using previously validated image processing techniques.ResultsFor all levels, the longitudinal rotation axis, from which the vertebrae rotate away from the midline, was localized posterior to the spine. The axis became closer to the spine at the apex: apex, r = 11.5 ± 5.1 cm versus two levels above (radius = 15.8 ± 8.5 cm; p < 0.001) and beneath (radius = 14.2 ± 8.2 cm; p < 0.001). The vertebral axial rotation, intravertebral axial rotation, and local mechanical torsion of the vertebral bodies were largest at the apex (21.9° ± 7.4°, 8.7° ± 13.5° and 3.0° ± 2.5°) and decreased toward the neutral, junctional zones (p < 0.001).ConclusionIn AIS, the vertebrae rotate away around an axis that is localized posterior to the spine. The distance between this axis and the spine is minimal at the apex and increases gradually to the neutral zones. The vertebral axial rotation is accompanied by smaller amounts of intravertebral rotation and local mechanical torsion, which increases toward the apical region. The altered morphology and alignment are important for a better understanding of the 3D pathoanatomical development of AIS and better therapeutic planning for bracing and surgical intervention.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.

Rotational spectroscopy of methyl mercaptan CH332SH at millimeter and submillimeter wavelengths

We present a new global study of the millimeter (mm) wave, submillimeter (sub-mm) wave, and terahertz (THz) spectra of the lowest three torsional states of methyl mercaptan (CH3SH). New measurements have been carried out between 50 and 510 GHz using the Kharkiv mm wave and the Cologne sub-mm wave spectrometers whereas THz spectra records were used from our previous study. The new data, involving torsion–rotation transitions with J up to 61 and Ka up to 18, were combined with previously published measurements and fit using the rho-axis-method torsion–rotation Hamiltonian. The final fit used 124 parameters to give an overall weighted root-mean-square deviation of 0.72 for the dataset consisting of 6965 microwave (MW) and 16 345 far-infrared line frequencies sampling transitions within and between the ground, first, and second excited torsional states. This investigation presents a two-fold expansion in the J quantum numbers and a significant improvement in the fit quality, especially for the MW part of the data, thus allowing us to provide more reliable predictions to support astronomical observations.

Modeling of Localized Inelastic Deformation at the Mesoscale with Account for the Local Lattice Curvature in the Framework of the Asymmetric Cosserat Theory

In the paper, inelastic strain localization in homogeneous specimens and mesovolumes of a polycrystalline material is modeled based on the asymmetric theory of an elastoplastic Cosserat continuum in a two-dimensional formulation for plane strain. It is assumed that rotational deformation in loaded materials occurs due to the development of localized plastic deformation as well as bending and torsion of the material lattice at the micro- and nanoscale levels. For this reason, the parameters of the micropolar model are considered as functions of inelastic strain for each local mesovolume of the continuum. It is shown that the observed parabolic hardening can be attributed to a large extent to the development of rotational deformation modes, bending and torsion, and appearance of couple stresses in the loaded material. The modeling results indicate that if rotational deformation is stopped in the loaded material, its accommodation capacity decreases, the local and macroscopic inelastic strains sharply increase, leading to a much more rapid formation of fracture structures. Conversely, the formation of meso- and nanoscale substructures with high lattice curvature in materials promotes the activation of rotational deformation modes, reduction of localized strains, and relaxation of stress concentrators.

Experimental and Numerical Prediction of Torsional Behavior of Steel Beam with Sinusoidal Web

This study is concerned with the torsional behavior of I-beams with sinusoidal corrugated web. A compact-type numerical and experimental program was planned to observe pure torsion. This type of beam is quite important for the building design and construction. Specifically, the torsional behavior mentioned throughout this paper is a significant aspect to investigate the overall mechanical properties. The torsion load and rotation capability of experimental and finite element models were investigated for the I-sinus-shaped steel beams. The torsion load of elastic torsion compared to plastic torsion is approximately 76.77%, 86.46%, 83.50% and 78.11% for the Ex-Simple, Ex-sinus 30°, Ex-sinus 70° and Ex-IPE160, respectively. The increased rotation of elastic torsion compared to plastic torsion is approximately 45.12%, 40%, 50.55% and 38% for Ex-Simple, Ex-sinus 30°, Ex-sinus 70° and Ex-IPE160, respectively.

New insights and innovation from a million crystal structures in the Cambridge Structural Database.

The Cambridge Structural Database (CSD) is the world's largest and most comprehensive collection of organic, organometallic, and metal-organic crystal structure information. Analyses using the data have wide impact across the chemical sciences in allowing understanding of structural preferences. In this short review, we illustrate the more common methods by which CSD data influence molecular design. We show how more data could lead to more refined insights into the future using a simple example of trifluoromethylphenyl fragments, highlighting how with sufficient data one can build a reasonable model of geometric change in a chemical fragment with torsional rotation, and show some recent examples where the CSD has been used in conjunction with other methods to provide design ideas and more computationally tractable workflows for derivation of useful insights into structural design.

Assessment of lower limb rotational profile and its correlation with the tibial tuberosity-trochlea groove distance: A radiological study.

The purpose of our study was to determine whether there is a correlation between the lower limb rotational profile and tibial tuberosity-trochlea groove (TT-TG) distance. The computed tomography cross-sectional imaging on 50 patients' lower limbs (100 limbs) was investigated at our institution. The TT-TG distance was measured along with rotational measurements including femoral version (FV), tibial torsion and knee joint rotation angle (KJRA). Patients were divided into two groups. Group 1 had a TT-TG ≥ 20 mm which was considered pathological and group 2 with a non-pathological TT-TG (≤19 mm). Rotational angles were compared between groups. Statistical analysis was performed using the t-test and Mann-Whitney U analysis. Our results demonstrated a statistically significant difference in the mean KJRA (p = 0.026) between the pathological (mean = 10.6, standard deviation (SD) = 7.79°) and the non-pathological TT-TG groups (mean = 6.99, SD = 5.06°). A higher mean value for FV and tibial torsion was also demonstrated in patients with a pathological TT-TG (18.2 vs. 13.7, 32.8 vs. 30.9, p > 0.05, respectively). In conclusion, there was a statistically significant higher mean value for the KJRA in patients with a pathological TT-TG. Hence, a lateralized tibial tubercle as demonstrated by an increase in the TT-TG distance may be associated with a coexisting lower limb rotational malalignment.

An analysis of influence of material damping on dynamic response of surface foundation under rotational motion

ABSTRACT Material damping arises due to the soil present beneath the foundation and controls the behaviour of the foundation under dynamic excitation. In the present study, an attempt has been taken to observe the effect of soil material damping on the dynamic response of foundation under rocking and torsional motion. A recent trend in present methods of dynamic analysis of foundation in the frequency domain is to find out the dynamic impedance functions, i.e. spring coefficient and damping coefficient. For foundation under rotational motion, i.e. rocking and torsion, the material damping is introduced using the Kelvin model and the results thus obtained are compared with those obtained by Hysteretic model and Voigt model. Parameter sensitivity analysis is carried out to determine the most influencing parameter. The study suggests that foundation under rocking motion is non-linearly influenced by the Poisson’s ratio of soil.

Design and analysis of microcantilever beams based on arrow shape

In this work, we present the design and analysis of microcantilever beams based on arrow shape. Effect of rectangular step length and width as well as free end width of beam have been investigated on various characteristics of proposed microcantilever beams. The proposed microcantilever beams were fabricated from silicon dioxide material using wet bulk micromachining in 25 wt.% TMAH at 75 °C. Vibration analysis of the microcantilever beams was carried out using a laser vibrometer. A FEM software, ANSYS, was used primarily for numerical analysis of resonance frequency, and to examine the effect of rectangular step length as well as free end width of microcantilever beam on its resonance frequency. Furthermore, ANSYS was employed to determine the maximum deflection, torsional end rotation and quality factor of proposed microcantilever beams. Additionally, effects of bottom gap and rectangular step length on quality factor of proposed microcantilever beams at lower and higher bottom gaps have also been investigated. The fundamental transverse bending mode frequency for a proposed microcantilever beam comprising rectangular step length of 50 μm and free end width 0 μm is approximately 48% higher than that of the conventional rectangular profile microcantilever beam of width 40 μm. Furthermore, maximum deflection and torsional end rotation obtained for a proposed microcantilever beam having rectangular step length 190 μm and beam free end width 40 μm are found as 680% and 800%, respectively, higher than that of the rectangular beam of length 200 μm and thickness 40 μm.

The torsional fundamental band and high-J rotational spectra of the ground, first and second excited torsional states of acetone

We present a new global study of the millimeter, submillimeter and far-infrared (FIR) spectra involving the three lowest torsional states of acetone ((CH3)2CO). New microwave measurements have been carried out between 34 and 940 GHz using spectrometers in IRA NASU (Ukraine), and PhLAM Lille (France). The FIR spectrum of acetone has been recorded on the AILES beamline of the SOLEIL synchrotron facility. The new data involving torsion–rotation transitions with J up to 90 and Ka up to 52 were combined with previously published measurements and analyzed using a model developed recently to study the high resolution spectra of molecules with two equivalent methyl rotors and C2v symmetry at equilibrium (PAM_C2v_2tops program). The final fit included 117 parameters to give an overall weighted root-mean-square deviation of 0.85 for the dataset consisting of 29,584 microwave and 1116 FIR line frequencies belonging, respectively, to the three lowest torsional states (ν12,ν17) = (0,0), (1,0), (0,1) and to the observed fundamental band associated with the methyl-top torsion mode (ν12,ν17) = (0,1) ← (0,0). The high values of rotational quantum numbers involved in this study provide an opportunity to test the performance of the PAM_C2v_2tops program approach for the case of highly excited rotational states.

Transformation Properties under the Operations of the Molecular Symmetry Groups G36 and G36(EM) of Ethane H3CCH3

In the present work, we report a detailed description of the symmetry properties of the eight-atomic molecule ethane, with the aim of facilitating the variational calculations of rotation-vibration spectra of ethane and related molecules. Ethane consists of two methyl groups CH 3 where the internal rotation (torsion) of one CH 3 group relative to the other is of large amplitude and involves tunnelling between multiple minima of the potential energy function. The molecular symmetry group of ethane is the 36-element group G 36 , but the construction of symmetrised basis functions is most conveniently done in terms of the 72-element extended molecular symmetry group G 36 (EM). This group can subsequently be used in the construction of block-diagonal matrix representations of the ro-vibrational Hamiltonian for ethane. The derived transformation matrices associated with G 36 (EM) have been implemented in the variational nuclear motion program TROVE (Theoretical ROVibrational Energies). TROVE variational calculations are used as a practical example of a G 36 (EM) symmetry adaptation for large systems with a non-rigid, torsional degree of freedom. We present the derivation of irreducible transformation matrices for all 36 (72) operations of G 36 (M) (G 36 (EM)) and also describe algorithms for a numerical construction of these matrices based on a set of four (five) generators. The methodology presented is illustrated on the construction of the symmetry-adapted representations both of the potential energy function of ethane and of the rotation, torsion and vibration basis set functions.

Torsion of Rectangular Connection Elements

Traditionally, the torsional design of rectangular members has been based on elastic calculations. For member design, this approach is justified because beams subjected to torsion are usually controlled by torsional rotation serviceability limits. However, designs that are based on a first yield criterion underestimate the strength of connection elements. To evaluate the true torsional behavior of connection elements, various factors affecting the torsional strength of short rectangular members are investigated, showing that the torsional strength of connection elements can be predicted with rational analysis models using an ultimate strength approach. A method is proposed for calculating the strength of rectangular connection elements subjected to any possible combination of loads, including torsion. The design method results in a significant increase in torsional strength compared to traditional analysis methods. The method can be used to analyze extended single-plate connections subjected loads in any direction, including axial forces and combined vertical and horizontal shear forces. Three design examples show the proper application of the design method.

8주간의 스트레칭과 코어 운동 프로그램이 청소년의 자세교정에 미치는 효과에 관한 비교분석

This study aims to provide exercise program for correct body alignment of the youth in the growth period, to identify the factors that can be improved through correct posture and to improve the quality of the youth in growth period. For this purpose, this study conducted a group exercise for 60 minutes 2 times a week and a personal home training program one time a week on the experimental group 1(7 persons) applied with stretching exercise and experimental group 2(10 persons) applied with core props exercise program for 8 weeks. By examining and analyzing changes in 3 dimensional posture measurement variables before and after application of program, that is, arrangement status of the spine, imbalance of body central axis, rotation of spine and torso torsion using formetric 4D, this study obtained the results as follows. First, significant difference between group was found in Scoliosis and Kyphosis among Vertebra factors(p<0.5). Second, significant difference between group was found in pelvic rotation and pelvic torsion among pelvic factors(p<0.5). No significant difference was found in the factors of torso twist, rotation of pelvis and imbalance of central axis.

Ultrafast trans → cis Photoisomerization Dynamics of Alkyl-Substituted Stilbenes in a Supramolecular Capsule.

Ultrafast spectroscopy reveals the effects of confinement on the excited-state photoisomerization dynamics for a series of alkyl-substituted trans-stilbenes encapsulated in the hydrophobic cavity of an aqueous supramolecular organic host-guest complex. Compared with the solvated compounds, encapsulated trans-stilbenes have broader excited-state absorption spectra, excited-state lifetimes that are 3-4 times longer, and photoisomerization quantum yields that are 1.7-6.5 times lower in the restricted environment. The organic capsule disrupts the equilibrium structure and restricts torsional rotation around the central C═C double bond in the excited state, which is an important motion for the relaxation of trans-stilbene from S1 to S0. The location and identity of alkyl substituents play a significant role in determining the excited-state dynamics and photoisomerization quantum yields by tuning the relative crowding inside the capsule. The results are discussed in terms of distortions of the ground- and excited-state potential energy surfaces, including the topology of the S1-S0 conical intersection.

Gaze stabilization in mantis shrimp in response to angled stimuli

Gaze stabilization is a fundamental aspect of vision and almost all animals shift their eyes to compensate for any self-movement relative to the external environment. When it comes to mantis shrimp, however, the situation becomes complicated due to the complexity of their visual system and their range of eye movements. The stalked eyes of mantis shrimp can independently move left and right, and up and down, whilst simultaneously rotating about the axis of the eye stalks. Despite the large range of rotational freedom, mantis shrimp nevertheless show a stereotypical gaze stabilization response to horizontal motion of a wide-field, high-contrast stimulus. This response is often accompanied by pitch (up-down) and torsion (about the eye stalk) rotations which, surprisingly, have no effect on the performance of yaw (side-to-side) gaze stabilization. This unusual feature of mantis shrimp vision suggests that their neural circuitry for detecting motion is radially symmetric and immune to the confounding effects of torsional self-motion. In this work, we reinforce this finding, demonstrating that the yaw gaze stabilization response of the mantis shrimp is robust to the ambiguous motion cues arising from the motion of striped visual gratings in which the angle of a grating is offset from its direction of travel.

Biomechanical analysis of a novel plating for intra-articular distal humerus fractures: combined anteromedial and anterolateral plating

PurposeThe traditional strategy for fixing intra-articular distal humerus fractures is double plating placed in an orthogonal or parallel configuration, based on posterior approach. With a combined medial and lateral approach, a novel configuration of plating (combined anteromedial and anterolateral plating) has been used. In this study, we investigated the biomechanical properties of the novel plating by comparing it with orthogonal plating.MethodsBased on the 3D morphology of a healthy subject’s humerus, the models of simple intra-articular distal humerus fractures were simulated. Two configurations of plating were applied to fix the models: the novel plating (with one plate anteromedially and the other anterolaterally on distal humerus), and orthogonal plating. Stresses, displacement, and stiffness were simulated and calculated under the conditions of axial compression, rotation torsion, bending torsion, and valgus torsion by using finite element analysis.ResultsIn all the conditions, the maximal von Mises stresses of the novel plating are similar to those of orthogonal plating, and the patterns of stress distribution are similar between these two configurations. However, the impact of high stresses was weaker on the novel plating. The maximal displacement of the novel plating is smaller than that of orthogonal plating. The stiffness of the novel plating is superior to that of orthogonal plating, with the improvements of 19.4%, 122.7%, 25.0%, and 54.2% in axial compression, rotation torsion, bending torsion, and valgus torsion, respectively.ConclusionsThe novel plating is stronger than orthogonal plating without increasing stress magnitude when fixing simple intra-articular distal humerus fractures, which makes it a feasible alternative. Further biomechanical and clinical studies are needed for a decisive conclusion.