Rotation Of Plane Research Articles

Measurement of Brain Strains in a Goat Head Under Impact Loading

Abstract Measurements of brain deformations under dynamic loading are required to understand the biomechanics of traumatic brain injury (TBI). In this work, we have experimentally measured two-dimensional (2D) brain deformations in a sacrificed goat brain under injurious impact loading. To facilitate imaging, the goat head was dissected along the longitudinal midline. Goat head response was studied for sagittal plane rotation. Full-field, 2D deformations in the midsagittal plane of a goat brain were obtained at spatiotemporal resolutions of ∼1 mm and 0.4 ms, respectively. Results elucidate the dynamic strain evolution. The goat brain underwent large deformation. The strain pattern was heterogeneous. Peak strains in various brain regions were established within ∼20 ms, followed by negligible strain development due to the considerable viscous dissipation. The Cerebellum region experienced the highest strain, followed by cortical and subcortical regions. Strain concentration in the goat brain near the stiff membrane of the tentorium was observed. The strains in a brain simulant of a head surrogate (obtained previously) were also compared against the goat brain response. A response in the brain simulant was comparable to the goat brain in terms of strain pattern, peak strains in various substructures, and strain concentration near the membrane. However, the brain simulant was less dissipative than the goat brain. These results enhance the current understanding of the biomechanics of the brain under dynamic loading.

Optimization of in-brace corrective force in adolescents with Lenke type 5 curve using finite element model

BackgroundPelvic parameters have been taken into consideration for the evaluation of the outcomes of bracing in AIS. To discuss the stress required to correct the pelvic deformity related to Lenke5 adolescent idiopathic scoliosis (AIS) by finite element analysis, and provide a reference for the shaping of the pelvic region of the brace.MethodsAn three-dimensional (3D) corrective force on the pelvic area was defined. Computed tomography images were used to reconstruct a 3D model of Lenke5 AIS. Computer-aided engineering software Abaqus was used to implement finite element analysis. By adjusting the magnitude and position of corrective forces, coronal pelvic coronal plane rotation (PCPR) and Cobb angle (CA) of lumbar curve in the coronal plane, horizontal pelvic axial plane rotation, and apical vertebra rotation (AVR) were minimized to achieve the best effect on the spine and pelvic deformity correction. The proposed corrective conditions were divided into three groups: (1) forces applied on X-axis; (2) forces applied both in the X- and Y-axis; and (3) forces applied along the X-, Y-, and Z-axis at the same time.ResultsIn three groups, CA correction reduced by 31.5%, 42.5%, and 59.8%, and the PCPR changed to 12°, 13°, and 1° from 6.5°, respectively. The best groups of correction forces should simultaneously locate on the sagittal, transverse, and coronal planes of the pelvis.ConclusionsFor Lenke5 AIS, 3D correction forces can sufficiently reduce scoliosis and pelvic asymmetrical state. Force applied along the Z-axis is vital to correct the pelvic coronal pelvic tilt associated with Lenke5 AIS.

Effects of elevation on shoulder joint motion: comparison of dynamic and static conditions.

Although visual examination and palpation are used to assess shoulder motion in clinical practice, there is no consensus on shoulder motion under dynamic and static conditions. This study aimed to compare shoulder joint motion under dynamic and static conditions. The dominant arm of 14 healthy adult males was investigated. Electromagnetic sensors attached to the scapular, thorax, and humerus were used to measure three-dimensional shoulder joint motion under dynamic and static elevation conditions and compare scapular upward rotation and glenohumeral joint elevation in different elevation planes and angles. At 120° of elevation in the scapular and coronal planes, the scapular upward rotation angle was higher in the static condition and the glenohumeral joint elevation angle was higher in the dynamic condition (P<0.05). In scapular plane and coronal plane elevation 90°- 120°, the angular change in scapular upward rotation was higher in the static condition and the angular change in scapulohumeral joint elevation was higher in the dynamic condition (P<0.05). No differences were found in shoulder joint motion in the sagittal plane elevation between the dynamic and static conditions. No interaction effects were found between elevation condition and elevation angle in all elevation planes. Differences in shoulder joint motion should be noted when assessing shoulder joint motion in different dynamic and static conditions. Level of evidence: Level III, diagnostic cross-sectional study.

A comparison of anchor loads, planar displacement, and rotation for nylon and polyester moored systems for a 15 MW floating wind turbine in shallow water

Renewable energy is crucial for addressing energy security and climate change challenges. Offshore wind energy presents a significant opportunity to generate renewable energy. Shallow water areas, between 50 and 70 m deep, are economically feasible for wind farms using shared anchor concepts and mooring line systems. However, choosing the appropriate type of system is critical. Previous studies have demonstrated that synthetic fiber ropes are more efficient than traditional chain catenary. In this paper we present the results of a dynamic analysis of a 15 MW Turbine and the VolturnUS-S reference platform deployed in the Celtic Sea. We compare the planar displacements, rotations, and loads acting on a shared anchor using nylon and polyester ropes, the latter as retrieved from the literature. An engineering procedure is used to simulate the behavior of the nylon rope, and a diffraction analysis is employed considering the stiffness of the mooring matrix. Our results show that using nylon rope reduces the peak resolved anchor load by 44% compared to polyester, but at the cost of a relatively larger displacements and rotations, which can be mitigated with improvements in mooring design. Since nylon is 10% cheaper than polyester rope with an identical minimum breaking load (MBL), and more cost-efficient anchor concepts are being investigated, the findings of this study encourage further research on nylon applications for wind farms in shallow water using shared anchors.

Числове моделювання поступальних і обертальних коливань рдтп у стапелі під час вогневих стендових випробувань

This article dwells on results of firing bench testing of the solid-propellant rocket engine (SPRE), fastened to the thrust-measuring assembly stand. It is shown that when engine enters the steady-state mode of operation, plane (forward and rotation) vibrations of the SPRE can take place in the assembly stand due to the sudden pattern of thrust generation and displacement of the center of mass of the vibrating system from the engine axis. These vibrations distort measured values of engine thrust and pattern of its change versus time. The purpose of this work is to simulate the oscillating processes of the engine atop the assembly stand to single out in the distorted values of the measured thrust the components related to the processes in the engine and components, which are introduced into the thrust measurement by the oscillating processes in the system “assembly stand – engine”. Model of vibrating system is suggested, which consists of two rigidly connected bodies, containing elastic links, enabling forward and rotary motion and limited by the rigidity of the links. Mathematical model of the vibrating system is developed. Internal forces and moments acting in oscillatory system are defined. Method of numerical simulation of plane vibrations within the limits of the developed model is suggested. Plane vibrating motion and elastic force curve (curve based on force sensor readings) were simulated in thrust-measuring system for different cases of thrust curve and values of vibrating system parameters. Resonance condition was simulated and mutual influence of elastic parametrical link between forward and rotary vibrations was established. Impact of thrust-measuring system rigidity on peak values of force sensor readings was found out. Elastic force vibrations in thrust-measuring system with vibrating system parameters were simulated including variant of thrust change versus time, implemented during firing bench tests of one of the SPRE. It is shown that registered simulation results recreate thrust measurement results in pattern and values obtained by the force sensor during the firing bench tests, and owing to this, it was concluded that oscillating process parameters, assumed in the model, meet the actual ones. It is concluded that simulation provides objective interpretation of the thrust curve, reliable and comprehensive analysis of engine run during firing bench tests, more detailed and exact design of the assembly stand. Key words: vibrating system, plane vibrations, forward vibrations, rotary vibrations, resonance, thrust measurement.

Effects of personalized movement models in virtual reality on pain expectancy and motor behavior in patients with chronic back pain: a feasibility study

Cognitive-behavioral therapy (CBT) of chronic pain focuses on behavioral, cognitive, affective and social factors that play a role in the transition from acute to chronic pain, which often is initially caused by a specific event but then takes on “a life of its own”. CBT models assume that fear of pain and subsequent avoidance behavior contribute to pain chronicity and the maintenance of chronic pain. In chronic back pain (CBP), avoidance is often addressed by teaching patients to reduce pain behaviors (such as guarding and bracing that may become dysfunctional over time) and increase healthy behaviors (such as physical exercise and meaningful social activities). The current study explored if personalized virtual movement models (doppelganger avatars), who maximize model-observer similarity in virtual reality (VR), can influence fear of pain, motor avoidance and movement-related pain and function. In a randomized controlled trial, participants with CBP observed and imitated an avatar (AVA, N = 17) or a videotaped model (VID, N = 16) over three sessions, where moving a beverage crate, bending sideward (BS), and rotation in the horizontal plane (RH) were shown. Self-reported pain expectancy, as well as engagement, functional capacity and pain during movements, were analyzed along with range of motion (ROM). The AVA group reported higher engagement with no significant group differences observed in ROM. Pain expectancy increased in AVA but not VID over the sessions. Pain and limitations did not significantly differ. However, we observed a significant moderation effect of group, with prior pain expectancy predicting pain and avoidance in the VID but not in the AVA group. This can be interpreted as an effect of personalized movement models decoupling pain behavior from movement-related fear and pain expectancy. Thus, personalized virtual movement models may provide an additional tool for exposure and exercise treatments in cognitive-behavioral treatment approaches to CBP.

Axial rotation analysis in total ankle arthroplasty using weight-bearing computer tomography and three-dimensional modeling

BackgroundPost-operative alignment is the most critical indicator for a successful total ankle arthroplasty (TAA). Total ankle malrotation is associated with an increased risk for polyethylene wear and medial gutter pain. Currently, there is no consensus on the correct way to measure the alignment of the tibial and talar component rotations in the axial plane. In the current study, the post-operative analysis system was assessed using weight-bearing computer tomography and a three-dimensional (3D) model. The purpose of the study was to assess the inter-observer and intra-observer agreement of this system. Material and methodFour angles were measured by two raters independently in two separate readings: posterior tibial component rotation angle (PTIRA), posterior talar component rotation angle (PTARA), tibia talar component axial angle (TTAM), and tibial component to the second metatarsal angle (TMRA). Agreement analysis was quantified according to the interclass coefficient. ResultsSixty TAAs across 60 patients were evaluated. A good inter-observer agreement and intra-observer agreement when measuring the PTIRA, PTARA, and TTAM angles was observed along with an excellent inter-observer agreement and intra-observer agreement when measuring the TMRA angle. ConclusionIn conclusion, the current 3D model-based measurement system demonstrates good to excellent inter and intra-agreement. According to these results, 3D modelling can be reliably used to measure and assess the axial rotation of TAA components. Level of evidenceLevel 3 retrospective study

Probing axions through tomography of anisotropic cosmic birefringence

Cosmic birefringence is the in-vacuo rotation of the linear polarization plane experienced by photons of the Cosmic Microwave Background (CMB) radiation when theoretically well-motivated parity-violating extensions of Maxwell electromagnetism are considered. If the angle parametrizing such a rotation is dependent on the photon's direction, then this phenomenon is called Anisotropic Cosmic Birefringence (ACB). In this paper, we perform for the first time a tomographic treatment of the ACB, by considering photons emitted both at the recombination and reionization epoch. This allows one to extract additional and complementary information about the physical source of cosmic birefringence with respect to the isotropic case. We focus here on the case of an axion-like field χ, whose coupling with the electromagnetic sector induces such a phenomenon, by using an analytical and numerical approach (which involves a modification of the CLASS code). We find that the anisotropic component of cosmic birefringence exhibits a peculiar behavior: an increase of the axion mass implies an enhancement of the anisotropic amplitude, allowing to probe a wider range of masses with respect to the purely isotropic case. Moreover, we show that at large angular scales, the interplay between the reionization and recombination contributions to ACB is sensitive to the axion mass, so that at sufficiently low multipoles, for sufficiently light masses, the reionization contribution overtakes the recombination one, making the tomographic approach to cosmic birefringence a promising tool for investigating the properties of this axion-like field.

Vertical effects of distalization protocol with Clear aligners in Class II patients: a prospective study.

The aim of the present prospective study was to detect the effects on vertical dentoskeletal dimension produced by molar distalization with Clear Aligners in a group of subjects with Class II malocclusion. The Clear Aligners Group (CAG) comprised 20 patients (13 females, seven males) with a mean age of 17.2±3.2 years. The same standardized protocol of sequential distalization was applied in all subjects. For each patient lateral cephalograms have been analyzed before treatment (T1) and at the end of the therapy (T2). At the end of treatment, clear aligners were effective in the correction of Class II dental relationship with the correction of the overjet (-1.3 mm). The treated group showed statistically significant reduction in FMA angle (-1.3°) associated with a counterclockwise rotation of the occlusal plane (POccl^PF -3.1°; SN^POccl -4.2°) and a slight intrusion of maxillary first molars to palatal plane (-0.9 mm). Finally, statistically significant differences were detected in anterior facial height (N-Me) and in the ArGo^GoMe angle (-1.2 mm and -3.4°, respectively). Upper molar distalization with clear aligners represents a valid alternative to non-extraction treatment of Class II malocclusion, reducing the extrusion of maxillary first molars and improving the control of the occlusal plane and of the vertical dimension.

Planar polarization rotation reflective surface for X-band RCS reduction in microstrip patch antenna

In this study, a rectangular microstrip patch antenna (MSPA) with a low X-band radar cross section (RCS) is proposed. The existing RCS reduction involves many layers, which raises design complexity. The research challenge is to lower the X-band RCS of a patch antenna using single-layer while keeping the good radiation performance. A polarization rotation reflective surface (PRRS) made up of unit cells arranged in the same plane encircles the proposed MSPA. This MSPA's radiation pattern and scattering capabilities are investigated and the effective RCS reduction in the X-band frequency from 8 to 12 GHz is achieved by arranging the unit cells of the newly developed PRRS. The proposed MSPA, which has an impedance bandwidth (BW) of 8.98 GHz to 10.99 GHz and a low X-band RCS, eliminates the requirement for multiple layers in the antenna. In addition, the antenna has the length and width of 23 mm and 41 mm with 14 unit cells and radiating elements of antenna is 9 mm x 6 mm and the substrate have the thickness of h = 2 mm.

Effects of load increase on lower extremity kinetic and kinematic variables in the back squat exercise.

Squats are one of the most widely used weight training methods worldwide, and the single most ubiquitous with regard to multi-joint resistance training. The objective of the present study was to investigate kinematic and kinetic changes in the lower extremities as a result of load increases during a back squat exercise, and to propose an association between back squats and lower extremity injuries. Eight individuals with experience of back squat training were recruited. The subjects performed back squats with loads of 25%, 50%, 100%, and 125% of their body weight. During the performance, the center of pressure (COP) sway; vertical center of mass (COM) velocity; joint moment; joint range of motion (ROM) of flexion/extension and adduction/abduction; and rotation of the ankle, knee, and hip joints were measured. The participants' lower extremity joint ROM, vertical COM velocity, and COP variability did not change significantly with changes in weight loading. However, the moments applied to the lower extremity joints differed according to changes in barbell weight. The moments of plantar flexion (f= 54.362, p< 0.001), dorsiflexion (f= 8.475, p< 0.001), knee flexion (f= 12.013, p< 0.001), knee extension (f= 8.581, p< 0.001), hip flexion (f= 5.111, p< 0.001), and hip extension (f= 11.053, p< 0.001) increased in the sagittal plane (flexion/extension). There was also a significant increase in ankle eversion (f= 5.612, p= 0.004), hip abduction (f= 3.242, p= 0.037), and adduction (f= 5.846, p= 0.003) in the frontal plane (adduction/abduction). Among the moment variables in the transverse plane (rotation), there were significant differences in ankle internal rotation (f= 7.043, p= 0.001) and hip external rotation (f= 11.070, p< 0.001). As the barbell load increased, posture and performance were maintained, but rotational moments of the joints differed. It is expected that the joint directions that showed significant differences in this study are likely to be vulnerable to the risk of injury when an excessive load is applied to the body. Examples include the hip adduction moment, hip external rotation moment, and ankle internal rotation moment, and apply regardless of the increase in the rotational moments of joints from load increases.

“Koehlers teardrop is not a reliable landmark for assessing the centre of rotation after Total hip arthroplasty” – a retrospective radiological study

PurposeVarious anatomical landmarks have become established in radiography for the assessment of cup positioning after total hip arthroplasty (THA). The most important one is Koehler's teardrop figure (KTF). However, there is a lack of data on the validity of this landmark, which is widely used clinically for assessing the centre of rotation of the hip.MethodA retrospective measurement of the lateral and cranial distance of the KTF to the centre of hip rotation was performed on the basis of 250 X-ray images of patients who had undergone THA. In addition, the dependence of these distances on pelvic tilt was determined in 16 patients by means of virtual X-ray projections based on pelvic CTs.ResultsIt was shown that the distance of the KTF from the centre of hip rotation in the horizontal plane is gender-dependent (men: 42.8 ± 6.0 mm vs. women: 37.4 ± 4.7 mm; p < 0.001) and age-dependent (Pearson correlation – 0.114; p < 0.05). Furthermore, the vertical and horizontal distances are subject to variation depending on height (Pearson correlation 0.14; p < 0.05 and 0.40; p < 0.001, respectively) and weight (Pearson correlation 0.158; p < 0.05). The distance between the KTF and the centre of hip rotation varies slightly depending on pelvic tilt.ConclusionThe KTF is not a sufficiently valid landmark for assessing the centre of rotation after THA. It is influenced by many different disturbance variables. However, it is largely robust against changes in pelvic tilt, so that it can be used as a reference point when comparing different intraindividual radiographs to assess the change in the centre of rotation due to implantation or to detect cup migration.

Plasma local diagnostics by polarimetric method

We study the polarization plane rotation of weak probe signal in the field of strong electromagnetic waves in the presence of an external magnetic field of plasma, the polarization plane stimulated rotation angle of the probe signal in the intense laser field and in plasma is calculated. The estimates of the residual gas local density in a cesium plasma based on the effects of Faraday, Cotton–Mouton and stimulated rotation of the probe signal in the intense laser field have been found. It is shown, that the rotation angle in the cesium plasma medium has a complex structure.

Orthogonal time chirp space modulation based upon fractional Fourier transform

Linear chirps play a significant role in communications because of their ability to spread spectrum and provide secure and robust communication. Orthogonal time frequency space (OTFS) modulation is suitable for high-mobility transmissions over a stationary delay-Doppler channel. The advantages of linear chirps and OTFS modulation are combined in this study. Specifically, orthogonal time chirp space modulation based on fractional Fourier transform (OTCS-FrFT) is proposed, which is obtained by replacing the two-dimensional (2D) sinusoidal carriers of OTFS modulation with 2D linear chirps. As the Fourier transform is the kernel of OTFS modulation, FrFT underlies the proposed OTCS-FrFT system for its complete and orthogonal linear chirp bases and its fast computation algorithms. The information symbols are originally placed on the delay-fractional Doppler plane, which is a rotation of the delay-Doppler plane, where the rotation angle is a free parameter that enables the OTCS-FrFT to adapt to different time-varying Doppler scenarios. It is proven that the OTCS-FrFT is robust to time-varying channels with linear delay/Doppler spreading functions. For other time-varying channels, simulations are performed to validate the superior performance of the OCTS-FrFT over other FrFT-based OTFS modulation methods, where the bit error rate is reduced by approximately 1 dB for both high-speed and high-acceleration terminals.

Cervical Proprioception Assessed through Targeted Head Repositioning: Validation of a Clinical Test Based on Optoelectronic Measures

Neck proprioception is commonly assessed with head repositioning tests. In such a test, an operator rotates the head of a blindfolded individual to a target position. After returning to the rest position, the participant actively repositions the head to the target. Joint Position Error (JPE) is the angular difference between the target angle (however oriented in a 3D space) and the actively reached positions (the smaller the difference, the better the proprioception). This study aimed to validate a head-to-target (HTT) repositioning test using an optoelectronic system for also measuring the components of the JPE in the horizontal, frontal, and sagittal planes. The head movements requested by the operator consisted of 30° left-right rotations and 25° flexion-extension. The operators or subjects could not obtain these movements without modest rotations in other planes. Two operators were involved. Twenty-six healthy participants (13 women) were recruited (mean (SD): 33.4 (6.3) years). The subjects' JPE in the requested (intended) plane of motion (JPEint-component) was a few degrees only and smaller for flexion-extensions than for left-right rotations (right rotation: 5.39° (5.29°); left rotation: 5.03° (4.51°), extension: 1.79° (3.94°); flexion: 0.54° (4.35°)). Participants' average error in unintended planes was around 1° or less. Inter-operator consistency and agreement were high. The smallest detectable change, at p < 0.05, for JPEint-component ranged between 4.5° and 6.98°. This method of optoelectronic measurement in HTT repositioning tests provides results with good metric properties, fostering application to clinical studies.

Phases of Rotating Black Objects in d = 5 Einstein–Gauss–Bonnet Theory

We considered several different classes of asymptotically flat, rotating black objects in d=5 Einstein–Gauss–Bonnet (EGB) theory. These are black holes with two equal-magnitude angular momenta, in which case extremal configurations are studied as well. Numerical evidence is also given for the existence of EGB generalizations of the Myers–Perry black holes with a single plane of rotation and of the Emparan–Reall balanced black rings. All solutions approach asymptotically the Minkowski background and present no singularities outside or on the horizon. The numerical results suggest that, for any mass of the solutions and any topology of the horizon, the rotating configurations exist up to a maximal value of the GB coupling constant, while the solutions with a spherical horizon topology still satisfy the Einstein gravity bound on angular momentum.

Induced leg length inequality affects pelvis orientation during upright standing immediately following a sit-to-stand transfer: a pre-post measurement study

BackgroundLeg length inequality (LLI) greater than 20 mm has been associated with low back pain (LBP) and its correction is clinically recommended. Much less is known about the biomechanical effects that LLI below 15 mm has on pelvis orientation.MethodsTwenty-two adult participants (8 female) aged between 18 and 30 years without LBP were enrolled in the study and completed a series of sit-to-stand trials with no heel-lift (0 mm baseline) and heel-lifts of varying heights (5, 9 and 12 mm) placed in their right shoe. Three-dimensional kinematic data were obtained from the lower extremities, pelvis and thorax. Additional kinematic data were obtained from the left and right sides of the pelvis. The global orientation of the whole pelvis and relative orientation between the left and right sides of the pelvis were obtained in upright standing immediately upon completion of the sit-to-stand movement. Repeated measures ANOVAs were used to detect differences in sample means across the different levels of heel-lift (0, 5, 9, and 12 mm). The tests for within-subject effects determined overall significant differences between the means at the different levels of heel-lift induced LLI. Partial Eta-Squared was used to express the size for the main effect of heel-lift height. For each level of heel-lift, the estimated marginal mean and 95% confidence interval (95%CI) values of pelvis angles were illustrated graphically.ResultsLeft frontal plane rotation of the pelvis increased (p = 0.001), that is, the left side of the pelvis was lower than the right side of the pelvis, and anterior tilt of the pelvis decreased (p = 0.020) with a heel-lift height (applied on the right) as low as 5 mm. A significant main effect of heel-lift was only observed for the norm of rotations about all three axes for relative-pelvis orientation (p = 0.034). Post-hoc analyses did not reveal any statistically significant differences between the heel-lifts and the 0 mm baseline (p≥0.072).ConclusionThese findings suggest that correcting leg length inequality below the recommended threshold of 20 mm may influence pelvic orientation. Future work can investigate the effects of the altered orientations on spine loading and the clinical effects of corrections to minor leg length inequality.

Einstein-Vlasov system with equal-angular momenta in AdS5

We investigate solutions of the five-dimensional rotating Einstein-Vlasov system with an $R\ifmmode\times\else\texttimes\fi{}SU(2)\ifmmode\times\else\texttimes\fi{}U(1)$ isometry group. In a five-dimensional spacetime, there are two independent planes of rotation; thus, considering $U(1)$ symmetry on each rotation plane, we may impose an $R\ifmmode\times\else\texttimes\fi{}U(1)\ifmmode\times\else\texttimes\fi{}U(1)$ isometry to a stationary spacetime. Furthermore, when the values of the two angular momenta are equal to each other, the spatial symmetry gets enhanced to $R\ifmmode\times\else\texttimes\fi{}SU(2)\ifmmode\times\else\texttimes\fi{}U(1)$ symmetry, and the spacetime has a cohomogeneity-1 structure. Imposing the same symmetry to the distribution function of the particles of which the Vlasov system consists, the distribution function can be dependent on three mutually independent and commutative conserved charges for particle motion [energy, total angular momentum on $SU(2)$ and $U(1)$ angular momentum]. We consider the distribution function which exponentially depends on the $U(1)$ angular momentum and reduces to the thermal equilibrium state in spherical symmetry. Then, in this paper, we numerically construct solutions of the asymptotically anti--de Sitter Einstein-Vlasov system.

Broadband Spintronic Terahertz Source with Peak Electric Fields Exceeding 1.5 MV/cm

Spintronic terahertz emitters (STEs) are desirable broadband terahertz sources, but their limited signal strength has hindered practical application. By optimizing the photonic and thermal environment, the authors present an STE that could overcome this obstacle. Benchmarking against the state-of-the-art terahertz emitters based on optical rectification, this STE delivers strong terahertz pulses with comparable peak electric field and fluence, and offers additional features such as broadband radiation, easy alignment, and rotation of the terahertz polarization plane without power loss. This work will open up a promising pathway to nonlinear terahertz spectroscopy with spintronic sources.

Accurate determination of hip implant wear, cup anteversion and inclination through AI automated 2D-3D registration.

The precise and accurate measurement of implant wear, acetabular cup anteversion and inclination from routine anterior-posterior radiographs still poses a challenge. Current approaches suffer from time-consuming procedures accompanied by low and observer-dependent accuracy and precision. We present and validate a novel, automated method for determining total hip arthroplasty parameters by comparing its accuracy and precision with methods in contemporary scientific literature. The algorithm uses CAD-model-basedtwo dimensional-three dimensional (2D-3D)-registration supported by convolutional neural networks. Two in-vitro experimental set-ups were designed to validate the proposed 2D-3D-method. The set-ups provided 84 predefined wear values and 24 configurations of anteversion and inclination in 114 radiographs. Accuracy and precision were evaluated by systematically comparing the predefined ground truth and the automatically calculated values from in-vitro X-rays. In addition, an algorithm was developed and validated against physician's measurements on clinical X-rays to determine the inclination of the interteardrop (ITL) and biischial line (BL) to account for the individual patient's pelvic rotation in the frontal plane. Using X-rays from experimental set-ups, the determined mean error was 0.014 mm (standard deviation: 0.020 mm; root-mean-square-error: 0.024 mm) for wear in pelvic position, -0.01° (0.24°; 0.23°) for radiographic cup anteversion, and 0.11° (0.38°; 0.39°) for radiographic cup inclination. The inclination of ITL and BL was automatically determined in all clinical X-rays with excellent interclass correlation coefficients of 0.95 and 0.91, respectively. The presented algorithm allows the accurate and precise evaluation of total hip arthroplasty parameters without additional equipment. The method might help to investigate different implant designs, biomaterials, and surgical techniques with greater objectivity.