Average Joint Research Articles

Comparison of Pre and Post-Operative Thoracohumeral Kinematics between Single and Multi-Tendon Rotator Cuff Tears

<h3>Research Objectives</h3> To conduct a biomechanical evaluation of patients with single and multi-tendon rotator cuff tears to elucidate the changes in thoracohumeral joint motion occurring within the first year of repair as compared to the non-injured arm. <h3>Design</h3> Longitudinal, prospective. <h3>Setting</h3> Mobility Lab at the University of Wisconsin-Milwaukee. <h3>Participants</h3> Ten patients with rotator cuff tears stratified into two groups: supraspinatus tear only n=5 (single) and a supraspinatus tear plus at least one other muscle involved n=5 (multi). Mean age for the single tear group: 63.2 (±7.9 years) and multi tear group: 61.4 (±5.9 years). Mean tear size was 1.2 (±0.2 cm) for the single group and 3.0 (±1.4 cm) for the multi. Participants were evaluated pre-operatively (pre-op) and at approximately 3 months and 6 months post-operatively (post-op). <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Peak thoracohumeral (TH) joint external rotation. <h3>Results</h3> When comparing the post-op average peak TH joint external rotation of the surgical arm to the non-injured arm within each group, both had significantly less external rotation of the surgical arm at 3 months post-op, but only the single tear group had significantly less at 6 months post-op (p = 0.00016). When comparing the average peak TH joint external rotation at each visit between groups, the multi tear group had significantly greater external rotation of the surgical arm at the pre-op (p=0.04) and 6 months post-op (p=0.01) visits. <h3>Conclusions</h3> The multi tear group had significantly higher motion pre-op and 6 months post-op than the single tear group and normalized to the non-injured arm at 6 months. These results suggest pre-op motion plays a key role in rehabilitation progress, potentially more than the number of muscle tears. <h3>Author(s) Disclosures</h3> The authors have nothing to disclose.

Multi-carrier based UAV data relaying and user tracking system

In the case of natural disaster or emergency rescue, unmanned aerial vehicle (UAV) can be dispatched to the target region and leveraged as aerial relay to track and serve users owning to flexible maneuverability and fast deployment. In this article, a multi-carrier based UAV data relaying and user tracking system is proposed in which the UAV adopts multi-carrier transmission and builds a communication connection from the reliable infrastructure to the target region in emergency. More specifically, a base station (BS) sends information to the UAV which can allocate sub-carriers to users, and then the UAV forwards information, tracks and serves users to ameliorate system performance. A downlink average achievable sum rate maximization-based joint optimization problem, including the UAV flight path, sub-carrier transmit power and user scheduling, is formulated with the information causality constraint. Since the formulated problem suffers from non-convexity, a three-step iterative algorithm is derived to approximate the optimal solution to the original problem by alternatively optimizing UAV flight path, sub-carrier transmit power and user scheduling. Simulation results show that the proposed algorithm can not only track mobile users dynamically, but also demonstrate the performance superiorities of the proposed scheme prominently.

Subject-Specific Alignment and Mass Distribution in Musculoskeletal Models of the Lumbar Spine.

Musculoskeletal modeling is a well-established method in spine biomechanics and generally employed for investigations concerning both the healthy and the pathological spine. It commonly involves inverse kinematics and optimization of muscle activity and provides detailed insight into joint loading. The aim of the present work was to develop and validate a procedure for the automatized generation of semi-subject-specific multi-rigid body models with an articulated lumbar spine. Individualization of the models was achieved with a novel approach incorporating information from annotated EOS images. The size and alignment of bony structures, as well as specific body weight distribution along the spine segments, were accurately reproduced in the 3D models. To ensure the pipeline’s robustness, models based on 145 EOS images of subjects with various weight distributions and spinopelvic parameters were generated. For validation, we performed kinematics-dependent and segment-dependent comparisons of the average joint loads obtained for our cohort with the outcome of various published in vivo and in situ studies. Overall, our results agreed well with literature data. The here described method is a promising tool for studying a variety of clinical questions, ranging from the evaluation of the effects of alignment variation on joint loading to the assessment of possible pathomechanisms involved in adjacent segment disease.

Variants of Jacobi polynomials in coding theory

In this paper, we introduce the notion of the complete joint Jacobi polynomial of two linear codes of length n over $${\mathbb {F}}_{q}$$ and $${\mathbb {Z}}_{k}$$ . We give the MacWilliams type identity for the complete joint Jacobi polynomials of codes. We also introduce the concepts of the average Jacobi polynomial and the average complete joint Jacobi polynomial over $${\mathbb {F}}_{q}$$ and $${\mathbb {Z}}_{k}$$ . We give a representation of the average of the complete joint Jacobi polynomials of two linear codes of length n over $${\mathbb {F}}_{q}$$ and $${\mathbb {Z}}_{k}$$ in terms of the compositions of n and its distribution in the codes. Further we present a generalization of the representation for the average of the $$(g+1)$$ -fold complete joint Jacobi polynomials of codes over $${\mathbb {F}}_{q}$$ and $${\mathbb {Z}}_{k}$$ . Finally, we give the notion of the average Jacobi intersection number of two codes.

Jumbo cup in hip joint renovation may cause the center of rotation to increase.

BACKGROUNDUtilizing the large jumbo cup in revision total hip arthroplasty is an effective approach to cure many lacunar and segmental peripheral bone defects. However, with the use of the jumbo cup, the center of the hip joint may become elevated relative to the primary acetabulum, and the diameter of the large cup is greater.AIMTo study the height and the significance of the elevation of the hip joint center.METHODSEighty-eight patients matched the criteria for this condition and were included in the study. The center height of the hip joint was measured relative to the opposite normal hip joint. The diameter of the jumbo cup was measured and checked according to operation notes, and the diameter of the jumbo cup was measured with a prosthesis label. Then, the horizontal and vertical centers of rotation were measured on the surgical side and opposite side. The average center height of the hip joint on the renovated side and the opposite side and the position of the hip cup relative to the teardrop were compared using a paired t-test.RESULTSRadiometric analysis showed that the average hip joint center was elevated by 7.6 mm. The rotational center height delta of the renovated hip was 7.6 ± 5.6 mm, and there was an obvious difference between the two groups (P = 0.00). The difference in horizontal distance was 0.5 ± 5.1 mm (-11.5 -14.0 mm), and there was no obvious difference between the two groups (P = 0.38). According to the foreign standard, the rotational center height delta of the renovated hip was 7.5 ± 6.2 mm, and there was a significant difference between the two groups (P = 0.00). There was no obvious difference between the domestic and foreign standards (P > 0.05) between the two groups.CONCLUSIONThe application of the jumbo cup elevates the rotational center of the hip joint, but it is feasible and effective to use the jumbo cup.

In-process cooling of friction stir extruded joints for increased weld performance via compressed air, water, granulated dry ice, and liquid nitrogen

Joining of aluminum alloy AA6061 to mild steel was achieved using a friction stir extrusion (FSE) method in which processed aluminum was extruded into a preformed steel dovetail groove. These joints were subject to various in-process cooling (IPC) methods via compressed air, water, granulated dry ice, and liquid nitrogen as well as varying weld pitches (WP) via the following rotational and translational (inches per minute, IPM) weld parameters: 1500RPM-3IPM, 1500RPM-2IPM, 1000RPM-3IPM, and 1000RPM-2IPM. Rockwell hardness testing and lap shear tensile testing were then used to evaluate the effectiveness of IPC by comparison to uncooled joints. These tests revealed an increase of 4.1% and 3.1% of hardness performance of the water cooled and dry ice cooled respectively compared to the uncooled weld. Additionally, the average tensile shear joint strength increased at a maximum of 4.5% for water cooled joints, 3.7% for air cooled welds, 3.5% for dry ice cooled welds, and 1.8% for liquid nitrogen cooled welds. The use of various IPC sources also revealed that the higher the WP, the stronger the extrusion joint. Thus, WP (revolution per inch, RPI) in order of descending performance are as follows: 750 RPI, 500 RPI, and 333 RPI. The novelty of this IPC and WP research comes from the investigation on the FSE joints compared to past research that has used butt and lap welds. The introduction of IPC and varying WP improved the strength and hardness of the FSE joints with the water cooling yielding the greatest measured improvement.

A quantitative approach to predict tunnel overbreak based on the Q-system

Overbreak can be a significant challenge in tunnelling and is usually assessed on a project-by-project basis. This paper attempts to quantify tunnel overbreak in jointed rock masses by producing a predictive model that practitioners can utilize at the preliminary design stage. Discontinuum numerical analysis of a circular-shaped tunnel is performed using the combined finite difference – discrete element method to generate a database of rock masses prone to overbreak. The Q-system, rock mass quality index, is used to classify the rock masses that are expected to overbreak in various tunnelling environments. The results are scrutinized to identify trends between overbreak and: i) Q, ii) average joint spacing and, iii) in-situ stress conditions. It is observed that overbreak increases when Q < 4 and is uniform when Q ≤ 4. A predictive model is generated through multiple regression analysis and can be used to identify and highlight the maximum likely overbreak or scenarios where overbreak is expected to occur.

Effect of water pressure and temperature on spherical float of level sensing auto drain valve

A float detects the level of a liquid in a tank or a container. It floats on top of the liquid surface and acts as a mechanical switch when the water moves up or down in the auto drain valve tank. The auto drain valve removes the water in the compressed air circuit The spherical float used in the auto drain valve is prone to the realization of a dent and the float joint fails due to the high pressure of air in the compressed air circuit. In this paper, the spherical float was analysed numerically to select the suitable stainless steel materials out of SS 302, SS 305, SS 312, SS 316 to withstand the high-pressure force and temperature of the air in the drain valve. The applied pressure was varied from 0.7 to 2.0 MPa and the temperature from 2 °C to 80 °C based on the drain valve application. The structural analysis results obtained were the total deformation, the equivalent stress, and the pressure at the joints of the float. Equations were obtained to get the relationships between applied pressure and temperature with equivalent stress and total deformation. The results indicate that both equivalent stress and total deformation varies linearly with pressure. With respect to temperature, equivalent stress varies linearly and total deformation varies in polynomial relation. The minimum and maximum values of total deformation obtained were 0 to 0.0132 mm, equivalent stress were 37.11 to 75.40 MPa and the average joint pressure was 12.43 to 76.56 MPa. The results show that SS 314 grade could be chosen for fabrication of spherical float in drain valve application.

The Proximal Placement of the Knee Joint in the 1-Stage Treatment of Infected Knee Revisions With Large Anterior Soft Tissue Defects

Introduction: No good mechanisms are available for reconstruction of large anterior soft tissue defects associated with infected total knees [periprosthetic joint infections of the knee (PJI-K)]. Patellectomy is usually required due to involvement with adjacent large anterior soft tissue defects left after radical debridement, free flaps are required for closure. This type of flap necessitates the use of a drop lock brace in ambulation. Our question is whether the proximal placement of the knee joint with longer tibial segments can reduce the number of free flaps and reduce the need for a drop lock brace by reattaching the quadriceps directly to the hinged tibial component. Methods: We retrospectively analyzed 35 cases with a minimum 2-year follow-up. Of 1-stage total knee revisions for PJI-K with the proximal placement of the knee joint for large anterior soft tissue defects left after debridement. Results: The average knee joint displacement was 85 mm. Eleven recurred with infection and 4 required amputation. Eighteen had enough extensor power to walk with a cane or walker as opposed to requiring a drop lock brace. Fifteen patients did not need any free or local flaps, rather these patients only required adjacent soft tissue transfer during surgery. Discussion: This novel proximal placement of the knee joint in patients with PJI-K who have large anterior soft tissue defects lessens the need for free flaps. The proximal placement also allows for reconstruction of what is left of the quadriceps mechanism into the tibial component and usually provides enough extensor power to lock the hinge joint.

Hybrid Comptonization and Electron–Positron Pair Production in the Black-hole X-Ray Binary MAXI J1820+070

Abstract We study X-ray and soft gamma-ray spectra from the hard state of the accreting black-hole binary MAXI J1820+070. We perform an analysis of two joint spectra from NuSTAR and INTEGRAL, covering the range of 3–650 keV, and of an average joint spectrum over the rise of the hard state, covering the 3–2200 keV range. The spectra are well modeled by Comptonization of soft seed photons. However, the distributions of the scattering electrons are not purely thermal; we find they have substantial high-energy tails, well modeled as power laws. The photon tail in the average spectrum is detected well beyond the threshold for electron–positron pair production, 511 keV. This allows us to calculate the rate of the electron–positron pair production and put a lower limit on the size of the source from pair equilibrium. At the fitted Thomson optical depth of the Comptonizing plasma, the limit is about 4 gravitational radii. If we adopt the sizes estimated by us from the reflection spectroscopy of &gt;20 gravitational radii, the fractional pair abundance becomes much less than unity. The low pair abundance is confirmed by the lack of both an annihilation feature and of a pair absorption cutoff above 511 keV in the average spectrum.

Patient-specific instrumentation combined with a new tool for gap balancing is useful in total knee replacement: a 3-year follow-up of a retrospective study

ObjectiveThe purpose of this study was to determine whether the gap-balancing technique with patient-specific instrumentation (PSI) and a new balancing device in total knee arthroplasty (TKA) can improve knee function to a greater extent than can the measured resection technique.Materials and methodsData from 150 patients who underwent TKA from August 2014 to June 2016 were studied retrospectively. The gap-balancing technique assisted by PSI and the new balancing device was used in 80 patients (82 knees), and the measured resection technique was used in 70 patients (70 knees). The surgical, imaging, and knee function data were compared.ResultsThe gap-balancing technique assisted by PSI and the new balancing device was found to be feasible in all operated knees and reliable. In total, 150 patients (152 knees) of ages ranging from 52 to 78 years (mean 67 years) underwent TKA during the study period. The follow-up period ranged from 35 to 52 months (mean 45 months). Only one patient, who was included in the gap-balancing group, underwent a revision surgery at 2 years postoperatively due to infection. There were no differences in the incidence of anterior knee pain between the two groups. The mean flexion angle, KSS scores, and VAS scores did not significantly differ between the measured resection group and gap-balancing group at 12 weeks or 36 weeks postoperatively. The average joint line displacement was 1.3 ± 1.1 mm (range 0–3) proximally in the GB (gap-balancing) group and 1.2 ± 1.4 mm in the MR (measured-resection) group. No outliers >5 mm in either group were recorded. The mean leg axis deviation from the neutral mechanical axis was 1.8°±1.5° varus (range 0°–3°varus) versus the neutral mechanical axis in the GB group and 1.4°±1.2°(range 0°–3°)in the MR group. No outliers with >3° deviation in either group were recorded.ConclusionsThe gap-balancing technique performed with the new balancing device and PSI can yield accurate femoral component alignment as well as outcomes similar to those of measured resection at 3 years. The new balancing device can be taken into consideration by surgeons who prefer performing the gap-balancing technique with PSI.

Changing Stride Frequency Alters Average Joint Power and Power Distributions during Ground Contact and Leg Swing in Running.

Runners naturally adopt a stride frequency closely corresponding with the stride frequency that minimizes energy consumption. Although the concept of self-optimization is well recognized, we lack mechanistic insight into the association between stride frequency and energy consumption. Altering stride frequency affects lower extremity joint power; however, these alterations are different between joints, possibly with counteracting effects on the energy consumption during ground contact and swing. Here, we investigated the effects of changing stride frequency from a joint-level perspective. Seventeen experienced runners performed six running trials at five different stride frequencies (preferred stride frequency (PSF) twice, PSF ± 8%, PSF ± 15%) at 12 km·h-1. During each trial, we measured metabolic energy consumption and muscle activation, and collected kinematic and kinetic data, which allowed us to calculate average positive joint power using inverse dynamics. With decreasing stride frequency, average positive ankle and knee power during ground contact increased (P < 0.01), whereas average positive hip power during leg swing decreased (P < 0.01). Average soleus muscle activation during ground contact also decreased with increasing stride frequency (P < 0.01). In addition, the relative contribution of positive ankle power to the total positive joint power during ground contact decreased (P = 0.01) with decreasing stride frequency, whereas the relative contribution of the hip during the full stride increased (P < 0.01) with increasing stride frequency. Our results provide evidence for the hypothesis that the optimal stride frequency represents a trade-off between minimizing the energy consumption during ground contact, associated with higher stride frequencies, without excessively increasing the cost of leg swing or reducing the time available to produce the necessary forces.

Subcutaneous tanezumab for osteoarthritis: Is the early improvement in pain and function meaningful and sustained?

BackgroundTo evaluate if early improvements in pain and function with subcutaneous tanezumab are meaningful and sustained over 24 weeks.MethodsPatients with moderate‐to‐severe osteoarthritis (hip or knee) in Europe and Japan were randomized to placebo, tanezumab 2.5 mg or tanezumab 5 mg (baseline, Week 8 and Week 16). Outcomes included: average daily index joint pain score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscales, rescue medication use, WOMAC responders (within‐patient ≥30% reduction in WOMAC Pain or Physical Function), Outcome Measures in Rheumatology‐Osteoarthritis Research Society International (OMERACT‐OARSI) responders (within‐patient) and Patient‐reported Treatment Impact Assessment‐Modified questionnaire.ResultsPatients received placebo (n = 282), tanezumab 2.5 mg (n = 283) or tanezumab 5 mg (n = 284). Changes from baseline in average daily index joint pain (within the first week) and WOMAC subscales (Week 2 through Week 24) were greater for each tanezumab group versus placebo (least squares [LS] mean, unadjusted p ≤ .05). Rescue medication use (days/week) was lower for each tanezumab group versus placebo from Week 2 through Week 12 (LS mean, unadjusted p ≤ .05) but not at Week 16 or 24. A higher proportion of each tanezumab group than placebo achieved ≥30% reduction from baseline in WOMAC Pain or Physical Function, or OMERACT‐OARSI response (Week 2 through Week 24, unadjusted p ≤ .05), or were satisfied with treatment at Week 24 (unadjusted p ≤ .05).ConclusionsSubcutaneous tanezumab, compared with placebo, reduced pain within the first week, and pain and function were improved throughout 24 weeks. The proportions of responders and patients satisfied were higher with tanezumab than placebo.ClinicalTrials.gov:NCT02709486.SignificanceThis exploratory analysis of data from a placebo‐controlled, Phase 3 study of patients with moderate‐to‐severe osteoarthritis of the hip or knee for whom standard analgesics were not effective or could not be taken, found that onset of efficacy of subcutaneous tanezumab was within the first week, and efficacy was maintained through the 24‐week treatment period. Tanezumab was effective in those patients with the most radiologically severe osteoarthritis.

Eruption type probability and eruption source parameters at Cotopaxi and Guagua Pichincha volcanoes (Ecuador) with uncertainty quantification

Future occurrence of explosive eruptive activity at Cotopaxi and Guagua Pichincha volcanoes, Ecuador, is assessed probabilistically, utilizing expert elicitation. Eight eruption types were considered for each volcano. Type event probabilities were evaluated for the next eruption at each volcano and for at least one of each type within the next 100 years. For each type, we elicited relevant eruption source parameters (duration, average plume height, and total tephra mass). We investigated the robustness of these elicited evaluations by deriving probability uncertainties using three expert scoring methods. For Cotopaxi, we considered both rhyolitic and andesitic magmas. Elicitation findings indicate that the most probable next eruption type is an andesitic hydrovolcanic/ash-emission (~ 26–44% median probability), which has also the highest median probability of recurring over the next 100 years. However, for the next eruption at Cotopaxi, the average joint probabilities for sub-Plinian or Plinian type eruption is of order 30–40%—a significant chance of a violent explosive event. It is inferred that any Cotopaxi rhyolitic eruption could involve a longer duration and greater erupted mass than an andesitic event, likely producing a prolonged emergency. For Guagua Pichincha, future eruption types are expected to be andesitic/dacitic, and a vulcanian event is judged most probable for the next eruption (median probability ~40–55%); this type is expected to be most frequent over the next 100 years, too. However, there is a substantial probability (possibly >40% in average) that the next eruption could be sub-Plinian or Plinian, with all that implies for hazard levels.

Mechanical Effect of Performance Pressure Boots on Cadaveric Equine Hindlimb Fetlock Biomechanics.

Simple SummaryPressure boots are performance enhancing equipment used by showjumping horses. Showjumping is scored by knocked down obstacle rails and time. Similar to weighted boots, pressure boots are intended to improve the hindlimb retraction of jumping horses to reduce the likelihood of knocking down rails on course. Manufacturers describe pressure boots as using acupressure to improve a horse’s awareness of their own limbs. However, this mechanism has not been verified within the scientific literature. The size and shape of features on the interior boot surface suggest a mechanical mechanism may affect anatomical structures within the lower limb. This research aims to characterize the mechanical effect of pressure boots by measuring forces and joint angles of cadaveric limbs with and without a pressure boot applied. Cadaveric limbs with a pressure boot applied required greater compressive loads to flex the fetlock joint than limbs without a pressure boot applied. This difference in compressive loads increased with increasing fetlock flexion angle. Differences in limb compressive loads contributed to greater tensile loads of palmar tendons and ligaments, specifically the suspensory apparatus. Greater tensile loading of tendons and ligaments may increase the likelihood of musculoskeletal injury and warrant concern for animal welfare of equine showjumping athletes.Pressure boots are applied to hind limbs of showjumping horses with the intent to enhance jumping form. Manufacturers claim acupressure points enhance proprioception of hind limbs. With this increased awareness, horses are expected to retract their hind limbs to clear jump rails. This research aimed to investigate a more direct, mechanical effect of pressure boots on hind limb biomechanics. Cadaveric hind limbs (n = 6) were mechanically loaded in axial compression (3 cycles at 0.25 Hz, displacement control ~3300 N) with (2 trials) and without (2 trials) a pressure boot applied. During mechanical loading, fetlock angle was measured using bone fixed pins with retroreflective markers (30 Hz). Changes in limb load and fetlock angle between unloaded and loaded states, as well as average fetlock joint stiffness, were compared between trials with and without the pressure boot via ANOVA. Differences in measured loads between trials with and without the boot were observed in both unloaded (Δ = 6 N, p = 0.05) and loaded states (Δ = 25 N, p = 0.002). Trials with the boot had greater average fetlock stiffness (Δ = 3 N/degree, p = 0.001). Differences in loads with and without boots may increase with greater fetlock angles when cantering and jumping. These mechanical effects of pressure boots may contribute to greater tensile loading of palmar tendons and ligaments, and likelihood of musculoskeletal injury that can be related to animal welfare issues.

The influence of reinforcement strengthening on seismic response and index correlation for high arch dams by endurance time analysis method

This study aims to explore the correlation between the seismic response indices of high arch dam with and without cantilever reinforcement strengthening. The nonlinear dynamic responses of the 289-m-high Baihetan dam located in southwestern China, to three-component endurance time acceleration histories are investigated. The dynamic responses, including damage distribution, displacement, and joint opening, are statistically analyzed. Furthermore, the proposed seismic response indices, including the global and local damage volume ratios, the average joint opening, and the displacement of the crown cantilever are studied. By comparing the seismic response indices with and without reinforcement, the effects of cantilever reinforcement on the changing trend and range of the seismic response indices are discussed. Subsequently, the correlation curves of the seismic response indices are demonstrated, and the correlation calculated with reinforcement between the seismic response indices is identified. To provide a better correlation analysis, the correlation of each seismic response index is classified. Numerical results show that the changing trend of correlation of the damage indices v. the upstream displacement is different from that of the damage indices v. the downstream displacement. When the peak ground acceleration is approximately 0.5 g, cantilever reinforcement has a significant effect on limiting damage development in the middle-upper part of the downstream face. However, cantilever reinforcement has a limited effect on the correlation between each seismic response index under different peak ground accelerations.

Anthropometrics, flexibility and training history as determinants for bicycle configuration

Intrinsic factors such as leg length, arm length, flexibility and training history are factors that may be relevant to the optimisation of the individual bicycle configuration process. Bike fitting methods do not always take all these variables into account, and as yet there have been limited studies examining how these variables can affect the cyclist's position on the bicycle. The main aims of this study were to establish how individual anthropometrics, training history and flexibility may influence cyclists' freely chosen bicycle configuration, and to determine the full-body static flexion angles chosen by cyclists on the bicycle.Fifty well-trained male cyclists were recruited for the study. A multivariate linear regression analysis was performed to predict the four main configurations of a bicycle (saddle height, saddle setback, handlebar reach and handlebar drop) based on individual anthropometrics, flexibility and training history. Average joint kinematic ranges for the knee (36°±7°) and elbow (19°±8°) joint supported previous recommendations. Hip (77°±5°) and shoulder (112°±7°) joint angles should be determined as true clinical joints.Trochanteric leg length (p < 0.01), Knee Extension Angle test (p < 0.01) and mSchober test (p = 0.04) were significant predictors for determining saddle height. Hamstring flexibility can be used to predict handlebar drop (p = 0.01).A cyclist who wishes to adopt a more aerodynamic position with an increased handlebar drop should aim to improve their hamstring flexibility.

Identification of generic drilling task phases and height effect: Coupling of kinematic and kinetic data

BackgroundThe prevention of work-related musculoskeletal disorders (MSDs) is an important issue for the health of operators, especially when the workload is heavy, such as in drilling activities. Research questionThis study aimed to propose an objective identification and description of the different phases that comprise a drilling task as well as a biomechanical and ergonomic evaluation of the subjects' overall posture during its effective part. MethodsFourteen healthy subjects performed three successive drillings at two different heights, 130 (H130) and 170 cm (H170) from the ground, of a 3 mm thick steel plate. Kinematic and kinetic data were simultaneously acquired using a Qualisys motion capture system and a force platform. The speed profiles of each body segments and the evolution of the force exerted were analysed to identify the different phases. Then, the average joint angles of the whole body were calculated during the drilling phase for the two heights considered and compared. Finally, the measured postures were qualified through the Rapid Upper Limb Assessment (RULA) score in order to assess the risk of developing MSDs for each condition. ResultsThe drilling task could be divided into five phases whatever the condition: transport, aiming, repositioning, drilling, and return. The increase in height has doubled the duration of the drilling phase while reducing the force exerted by about 30 %. Similarly, height variation significantly influenced the subjects' posture, mainly in the head, trunk and upper limbs, and the RULA scores obtained for conditions H130 and H170 were 6 and 7 respectively. SignificanceThe results indicate, on the one hand, the relevance of coupling kinematic and kinetic data in order to analyse the drilling task and, on the other hand, that operators are exposed to considerable risk of developing MSDs, even at intermediate heights, which increase as the height increases.

Joining process of dissimilar materials using three-dimensional electrodeposited Ni-Cu film

ABSTRACT We have developed a process of joining metals and plastics using three-dimensional electrodeposited films of a Ni–Cu alloy. In the present study, the effect of the shape of electrodeposited films, which was changed by using different concentrations of Ni amidosulfate in the Ni–Cu alloy plating solution and by plating at current densities, on the joint strength between stainless steel and polyamide 6 was investigated. The results show that when the concentration ratio of Ni amidosulfate to that of Cu sulfate was 150:15 (g/L) and the plating current density was 10 mA/cm2, a dendritic structure of the electrodeposited film was formed. When the concentration of Ni amidosulfate was 300–450 g/L, dendritic electrodeposited films with thick trunks were formed. When a stainless steel plate with an electrodeposited film and a polyamide 6 plate were joined by heating and compression, voids were formed directly above the dendritic electrodeposited film inside the polyamide 6 plate. A lap joint specimen with the stainless steel plate and polyamide 6 plate joined using the electrodeposited film made of 450 g/L Ni amidosulfate showed an average joint strength of 17 MPa.

Some factors affecting granitic pluton topography: Pluton topography in the southern Lachlan Foldbelt

Where neotectonics are inactive, granite batholith topography is determined largely by the dissolution rates of the minerals of the component plutons. In southern New South Wales, Australia, plutons in the Kosciusko, Corryong, Berridale, and Murrumbidgee Batholiths allow an assessment of the extent to which faults, joints, grainsize and foliation may control a pluton's topography. Changes in mean elevation of zoned plutons closely follow the changes in mineralogy; more felsic zones invariably occur at higher elevations than more mafic zones. Faults clearly dictate major landscape features, such as linear valleys. Neither grainsize nor foliation show any appreciable effect on these landscapes. Joint spacing in these plutons has a positive correlation with the rock's grainsize, with an intrinsic value varying linearly as the grain size varies. Not all joints at the intrinsic spacing may be evident. In perennially wet valleys most joints become weathered and so visible, leading to joints mostly spaced at that intrinsic value. In quickly drying crests and ridges more incipient joints remain closed, leading to larger boulders and a wider average joint spacing. Thus the evident joint spacing in granites is determined by grainsize and landscape position.