Full Joint Research Articles

Shoulder joint loading in the high performance flat and kick tennis serves

Objective:To quantify and compare the full body kinematics and shoulder joint kinetics during the high-performance tennis flat (FS) and kick serves (KS).Methods:A 12-camera 250 Hz, Vicon motion analysis system recorded...

Investigations into the effects of electron beam welding on thick Ti–6Al–4V titanium alloy

Electron beam welding (EBW) of titanium alloy Ti–6Al–4V is not an easy task and finding the correct welding parameters is one of the critical activities when the product is intricate in shape. The procedure adopted to weld 17.5 mm thick joint in a spherical titanium gas bottle using EBW is presented here. Available EBW machine was capable of welding full penetration joint only up to 12.5 mm in titanium. Single sided partial penetration weld yielded poor result in production welding due to repeated defects like lack of fusion, root porosities, weld bead depression, under cut, etc. A two-pass double side welding technique was developed, and a joint thickness of 21 mm was decided so that a partial penetration weld can be attempted with lesser beam power. The extra material kept at the root of the weld can be machined off after welding. Single pass was made from one side of the joint producing a partial penetration weld with a penetration of nearly 19 mm. The second pass was made from the reverse side of the joint producing a similar partial penetration weld with almost the same penetration as that of the first weld. Trial welds were carried out and considerable difficulties were encountered in developing the welding procedure for establishing a defect free weld. Fusion zone voids and root porosities were observed and techniques were developed which eliminated their occurrence. Systematic weld qualification was carried out on coupon level and mechanical property and microstructure evaluations were carried out to ensure the joint integrity. Based on the technology developed and parameters arrived, the final specimen was welded. After passing through non-destructive tests, it was subjected to hydraulic proof pressure test with strain gauges and acoustic emission sensors for validating the capability of the technology developed. It has qualified all the test requirements as per the specifications and has been used for aerospace applications.

Dissimilar autogenous full penetration welding of superalloy K418 and 42CrMo steel by a high power CW Nd:YAG laser

Experiments of autogenous laser full penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 3.5 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance were investigated. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. Results show that high quality full penetration laser-welded joint can be obtained by optimizing the welding velocity, flow rate of shielding gas and defocusing distance. The laser-welded seam have non-equilibrium solidified microstructures consisting of γ-FeCr 0.29Ni 0.16C 0.06 austenite solid solution dendrites as the dominant and very small amount of super-fine dispersed Ni 3Al γ′ phase and Laves particles as well as MC needle-like carbides distributed in the interdendritic regions. Although the microhardness of the laser-welded seam was lower than that of the base metal, the strength of the joint was equal to that of the base metal and the fracture mechanism showed fine ductility.

Joint Analyticity and Analytic Continuation of Dirichlet–Neumann Operators on Doubly Perturbed Domains

In this paper we take up the question of analyticity properties of Dirichlet–Neumann operators (DNO) which arise in boundary value and free boundary problems from a wide variety of applications (e.g., fluid and solid mechanics, electromagnetic and acoustic scattering). More specifically, we consider DNO defined on domains inspired by the simulation of ocean waves over bathymetry, i.e. domains perturbed independently at both the top and bottom. Our analysis shows that the DNO, when perturbed from an arbitrary smooth domain, is parametrically analytic (as a function of deformation height/slope) for profiles of finite smoothness. Additionally, we extend these results to joint spatial and parametric analyticity when the perturbations are real analytic. This analysis is novel not only in that it accounts for the doubly perturbed nature of the geometry, but also in that the technique of proof establishes the full joint analyticity from an arbitrary smooth profile simultaneously.

Posttraumatic temporomandibular joint ankylosis: clinical development and surgical management

To investigate the patterns of condylar fractures associated with temporomandibular joint ankylosis (TMJA) and treatment methods and results based on the different types of ankylosis. Forty-two joints of ankylosis in 31 patients with were categorized to four groups according to Sawhney's classification and undergone surgical treatment as follows: a joint release and disc reposition for Type I ankylosis, a dissection of bony block and disc reposition for Type II; a dissection of full-joint and employment of the temporal myofascial flap as interposition for Type III; a radically dissection of full joint followed by ramus distraction osteogenesis and genioplasty for Type IV. All of patients were followed up for 9 to 54 months with an average of 30 months. The range of mouth opening and temporomandibular joint (TMJ) function were assessed. Condylar fractures were retrospectively investigated on the patterns and the course of ankylosis development. Macroscopical visualization on the osseously ankylosed sites and disc displacement were analyzed in comparison with the radiological findings. Condylar sagittal and comminuted fractures were most susceptible to TMJA. Early fibrous ankylosis occurred usually at the 4th or 5th month post-traumatically with an average month opening of 18.3 mm. The articular discs were found displaced in all cases and early bony bridge formed at a limited area where there was no disc as cushion. During fellow-up, considerable improvement in mandibular movement was attained with a stable joint function and mouth opening range of over 30 mm except for two cases in which ankylosis relapsed. Condylar sagittal and comminuted fractures are most likely to cause ankylosis. Early surgical intervention could reduce the disc and avoid the later ankylosis.

Evaluating policy feedback rules using the joint density function of a stochastic model

The practise of evaluating feedback rules in stochastic models using marginal distributions implies the loss of considerable information. It is possible to use the full joint density function. This is illustrated by analysing three rules in a large stochastic model.

Primary Osteoarthritis in the Ankle Joint Is Associated With Finger Metacarpophalangeal Osteoarthritis and the H63D Mutation in the HFE Gene

Osteoarthritis (OA) can occur in the ankle joint. It also occurs in an appreciable proportion of subjects with hereditary hemochromatosis (HH). Might these conditions have common genetic characteristics? The aim of this study was to test the hypothesis that HFE gene mutations are associated with primary osteoarthritis in the ankle joint. Consecutive referred patients who had primary or secondary (posttraumatic) OA of the ankle joint were assessed by a single rheumatologist and had a full physical and joint examination. Plain x-rays of the ankle joint, other clinically involved osteoarthritic joints, iron studies, HFE genotyping, and Hb electrophoresis were performed. The significance of differences was evaluated by 2-tailed Fisher exact test. Fourteen patients met the inclusion criteria for primary ankle OA and 6 met the criteria for secondary ankle OA. One of the 14 had had a previous subtalar joint fusion and was excluded. Among the remaining 13, 7 had OA in the index and/or middle finger metacarpophalangeal joints (MCP2,3 OA) with radiologic features similar to those found in hemochromatotic arthropathy (HA). Furthermore, 11 of the 13 had at least one HFE mutation, one subject in this group was homozygous for H63D, one was compound heterozygous for C282Y and S65C, and one was compound heterozygous for H63D and S65C. Eight were heterozygous for H63D. The 13 subjects were compared with the 6 secondary ankle OA subjects and with a previously studied population cohort (n = 3011) from the town of Busselton in whom HFE genotyping had been performed. A statistically significant increase in the frequency of HFE gene mutations was observed in the group with primary OA of the ankle joint compared with that with secondary ankle joint OA (P = 0.0095) and compared with the Busselton cohort (P = 0.0008). Furthermore, a statistically significant association between finger MCP joint OA and primary ankle joint OA was observed (P = 0.0436). Iron studies were normal in the 13 primary and 6 secondary ankle OA subjects. None of the subjects with ankle OA had clinical signs of hemochromatosis or abnormal liver function tests. A strong and statistically significant association was observed between HFE gene mutations and primary OA in the ankle joint. The frequent presence of MCP2,3 OA in these patients suggests the existence of a type 2 polyarticular OA phenotype that closely resembles the arthropathy of HH and which appears to be clinically differentiable from type 1 OA or nodal generalized OA (NGOA). HFE gene mutations may be a marker for the type 2 polyarticular OA phenotype and a clue to OA pathogenesis.

Pilot study of fitness training and exercise testing in polyarticular childhood arthritis

To 1) assess the safety and feasibility of laboratory-based exercise testing in juvenile idiopathic arthritis (JIA), 2) test the safety and feasibility of a 3-month exercise program in JIA, 3) assess pain during exercise in JIA, 4) compare ratings of perceived effort (RPE) with heart rate (HR) achieved, and 5) estimate the training effect on metabolic efficiency of gait as measured by submaximal exercise testing. Nine children with JIA were enrolled in a 12-week circuit training program involving pool, stationary bicycle, treadmill, and Fitball. They underwent formal exercise testing before and after the program, underwent a full joint assessment, were administered the Childhood Health Assessment Questionnaire and Juvenile Arthritis Functional Status Index, and were assessed for overall quality of life and health-related quality of life. A visual analog scale was used to assess pain during testing and training, and the Borg scale was used to measure RPE. Children with JIA were able to participate in exercise testing without any significant problems. Children with severe hip disease dropped out of the exercise program due to pain during the exercise sessions and worsened arthritis symptoms. Target HR was achieved and correlated with RPE in the bicycle and treadmill sessions. Submaximal exercise testing showed an improvement with a small to moderate effect size. This study suggests that it is safe, feasible, and acceptable for children with arthritis, in the absence of severe hip involvement, to participate in formal exercise testing and structured fitness programs.

Fringe cracks and plumose structures in layered rocks: stepping senses and their implications for palaeostress interpretation

Many joint surfaces show en échelon arrays of microfractures (fringe cracks, F-joints, twist hackles) along fringe zones in continuity with plumose structures. In layered rocks, joints with two fringe zones showing opposite stepping senses at the top and bottom (type A) are more frequent than those showing a single stepping sense (type P). Consistent with such an arrangement, their curved advancing fronts show continuous, 180°-radial patterns of steps showing a ‘spiral-staircase’ geometry. In double plumose structures diverging from an initiation point, different combinations of symmetry elements allow us to define four basic stepping types: (type PA) single stepping sense on the full joint surface; (type AA) opposite stepping senses at both fringes; (type PP) opposite stepping senses at both sides of the starting point; (type AP) four alternate quadrants with opposite stepping. Most of these types have been observed in limestone beds of the Mequinenza area (Ebro Basin, Spain) and Glamorgan coast (South Wales). According to our observations, the varied stepping arrangements are independent of changes in orientation within the parent joint, the latter showing more persistent strikes than fringe cracks. All these features suggest that fringe crack arrays in continuity with plumose structures are related to local stress redistribution at the advancing front and, as a general rule, do not record remote stresses. After careful observation and discrimination, only those en échelon cracks consistently stepped and showing no geometric continuity with plume barbs should be included in palaeostress analysis.

Optimal source localization in the presence of interfering sources

Source localization in shallow-water ocean environments is hindered by the presence of loud interfering sound sources. To remediate these nuisance sources, one needs to back out the true signal from the received mixed acoustic field by estimating a most likely interference scheme. In this work the focus is on resolving problems introduced by an unknown number of interfering signal sources. A statistical model for the sensed acoustic field is estimated using Gibbs sampling in which one obtains through iteration an approximation to the full joint posterior probability description of the model and data. From this joint probability description, the impact of canceling undesirable field components is readily seen on the estimated uncertainty that characterizes the localization process. [Work supported by ONR.]

Treatment of Distal Radius Fractures With a Low-Profile Dorsal Plating System: An Outcomes Assessment

To evaluate objective functional and radiographic outcomes after internal fixation of acute, displaced, and unstable fractures of the distal aspect of the radius in adults by using a low-profile dorsal plating system. Our hypothesis was that the low-profile dorsal plating system would allow for a reduction of extensor tendon irritation and pain and provide stable osseous fixation. Sixty consecutive unstable fractures in 59 patients were treated by open reduction internal fixation using a low-profile dorsal plating system. There were 29 type A, 14 type B, and 8 type C fractures (AO classification system). Fifty patients with 51 fractures returned for outcomes assessment by physical examination, plain radiographs, and completion of a validated musculoskeletal function assessment questionnaire. The minimum follow-up period was 1 year; the mean follow-up period was 24 months. Clinical evaluation was performed and plain radiographs were assessed for maintenance of immediate postoperative reduction and implant position. Objective functional assessment was obtained through the Disabilities of the Arm, Shoulder, and Hand questionnaire. Outcomes analysis showed no cases of extensor tendon irritation or rupture. Hardware removal was performed in 1 patient but no extensor tendon irritation or rupture was evidenced. The mean Disabilities of the Arm, Shoulder, and Hand score was 11.9; implant-related discomfort was minimal. All patients had an excellent (31 patients) or good (19 patients) result according to the scoring system of Gartland and Werley. The mean active range of motion was greater than 80% of that of the contralateral wrist in flexion/extension, pronation/supination, and ulnar/radial deviation. Extensor tendon function was unimpaired in all patients. Grip and pinch strength averaged 90% and 94% of the contralateral sides, respectively. Radiographic evaluation showed no change in fracture reduction or implant position. The treatment of distal radius fractures with a low-profile stainless steel dorsal plating system is a safe and effective method that provides stable internal fixation and allows for full extensor tendon glide and full metacarpophalangeal joint motion. Objective outcome testing showed uniformly good to excellent recovery of wrist and hand function in all patients. Therapeutic, Level IV.

The Costs of Ignoring High-Order Correlations in Populations of Model Neurons

Investigators debate the extent to which neural populations use pairwise and higher-order statistical dependencies among neural responses to represent information about a visual stimulus. To study this issue, three statistical decoders were used to extract the information in the responses of model neurons about the binocular disparities present in simulated pairs of left-eye and right-eye images: (1) the full joint probability decoder considered all possible statistical relations among neural responses as potentially important; (2) the dependence tree decoder also considered all possible relations as potentially important, but it approximated high-order statistical correlations using a computationally tractable procedure; and (3) the independent response decoder, which assumed that neural responses are statistically independent, meaning that all correlations should be zero and thus can be ignored. Simulation results indicate that high-order correlations among model neuron responses contain significant information about binocular disparities and that the amount of this high-order information increases rapidly as a function of neural population size. Furthermore, the results highlight the potential importance of the dependence tree decoder to neuroscientists as a powerful but still practical way of approximating high-order correlations among neural responses.

The Costs of Ignoring High-Order Correlations in Populations of Model Neurons

Investigators debate the extent to which neural populations use pair-wise and higher-order statistical dependencies among neural responses to represent information about a visual stimulus. To study this issue, three statistical decoders were used to extract the information in the responses of model neurons about the binocular disparities present in simulated pairs of left-eye and right-eye images: (1) the full joint probability decoder considered all possible statistical relations among neural responses as potentially important; (2) the dependence tree decoder also considered all possible relations as potentially important, but it approximated high-order statistical correlations using a computationally tractable procedure; and (3) the independent response decoder, which assumed that neural responses are statistically independent, meaning that all correlations should be zero and thus can be ignored. Simulation results indicate that high-order correlations among model neuron responses contain significant information about binocular disparities and that the amount of this high-order information increases rapidly as a function of neural population size. Furthermore, the results highlight the potential importance of the dependence tree decoder to neuroscientists as a powerful but still practical way of approximating high-order correlations among neural responses.

Three-Dimensional T1 Mapping for dGEMRIC at 3.0 T Using the Look Locker Method

The objective of this study was to implement a three-dimensional (3-D) T1 mapping sequence (3DLL) at 3.0 T for dGEMRIC based on the Look Locker scheme. Because all current reports on dGEMRIC are at 1.5 T and mostly using 2-D IR fast spin echo (FSE), data were acquired at 1.5 T and 3.0 T with both 3DLL and 2-D IR-FSE sequence. Phantoms with different concentrations of Gd(DTPA) were used and seven subjects (three asymptomatic, four symptomatic) were scanned using the dGEMRIC technique. The T1 measurements obtained on the phantom with 3DLL show very good agreement with those acquired with 2-D IR-FSE. Using a two-tailed paired t test, the T1 (Gd) measurements in two sections obtained in all subjects with both sequences were found to be statistically indistinguishable at either field strength (P = 0.07 at 1.5 T and P = 0.07 at 3.0 T). The preliminary data presented here suggest that the 3DLL sequence provides accurate T1 values with sufficient in-plane resolution and allows full joint coverage in less than 10 minutes.

355. A Platform for Gene Delivery to Embryonic Stem Cells Using HSV

Embryonic development is a complex process involving integrated pathways directing the ordered proliferation, migration, and differentiation of stem cells into a developing embryo. Murine embryonic stem (mES) lines are immortal and homogeneous, and provide a relevant model of embryogenesis via embryoid body formation. An efficient gene delivery system for mES cells will facilitate investigations into the molecular events of embryonic differentiation. Here we describe the engineering and characterization of a replication-defective Herpes simplex virus-1 (HSV-1) vector, JD|[beta]||[beta]|, as a platform gene delivery vehicle. In this vector, the immediate early (IE, |[alpha]|) genes ICP4 and ICP22, and one full genomic joint element have been deleted. IE genes ICP27 and ICP0, whose low-level expression is necessary for transgene expression, have been converted into early (E, |[beta]|) genes in order to constrain their expression to ICP4-complementing cells, effectively eliminating their expression in normal cells. JD|[beta]||[beta]| does not express toxic viral genes in non-complementing cells including mES cells. JD|[beta]||[beta]| contains a green fluorescent protein (GFP) transgene under the control of the HCMV IE promoter and transduces mES cells with high efficiency. Transduction with JD|[beta]||[beta]|, even at elevated MOI, does not alter subsequent embryoid body formation nor the expression of endogenous germ layer markers during embryoid body formation, as determined by quantitative-PCR analysis. JD|[beta]||[beta]| will be further engineered to express developmentally relevant genes individually or in combination. This vector may be a useful tool for the experimental stem cell and regenerative medicine fields due to the attributes of non-toxicity, large transgene capacity, robust transgene expression, and non-integrating genome.

LOCKING OF THE METACARPOPHALANGEAL JOINT OF THE THUMB BY A LOOSE BODY: A CASE REPORT

We report a case with locking of the metacarpophalangeal (MP) joint of the thumb in a 15-year-old high school baseball catcher, which was caused by an intra-articular loose body arising from osteochondritis dissecans. The loose body was removed arthroscopically, enabling early return to full MP joint function.

Activation of WNT and BMP signaling in adult human articular cartilage following mechanical injury

Acute full thickness joint surface defects can undergo repair, which involves tissue patterning and endochondral bone formation. Molecular signals regulating this process may contribute to the repair outcome, chronic evolution and, eventually, the onset of osteoarthritis. We tested the hypothesis that mechanical injury modulates morphogenetic pathways in adult human articular cartilage explants. Adjacent articular cartilage explants were obtained from preserved areas of the femoral condyles of patients undergoing arthroplasty for osteoarthritis, or from a normal joint of a patient undergoing lower limb amputation. Paired explants were individually maintained in explant culture. From each pair, one explant was mechanically injured and the other left uninjured as a control. Cultures were terminated at different time points for histochemistry, immunohistochemistry and gene expression analysis by reverse transcription real time PCR. Bone morphogenetic protein 2 (BMP-2) mRNA was upregulated in the injured explants. We detected phosphorylation of SMAD-1 and SMAD-5, consistent with activation of the bone morphogenetic protein (BMP) pathway. FRZB-1 mRNA was downregulated in the injured explants, suggesting de-repression of WNT signaling. Accordingly, expression of the canonical WNT target genes Axin-2 and c-JUN was upregulated in the injured explants. Activation of the canonical WNT signaling pathway by LiCl treatment induced upregulation of COL2A1 and Aggrecan mRNA, suggesting an anabolic effect. Phosphorylation of SMAD-1/-5 and downregulation of FRZB were confirmed in vivo in a mouse model of joint surface injury. Taken together, these data show modulation of the BMP and WNT pathways following mechanical injury in vitro and in vivo, which may play a role in the reparative response of the joint surface. These pathways may, therefore, represent potential targets in protocols of biological joint surface defect repair.

Optimal Sequential Exploration: A Binary Learning Model

In this paper, we develop a practical and flexible framework for evaluating sequential exploration strategies in the case where the exploration prospects are dependent. Our interest in this problem was motivated by an oil exploration problem, and our approach begins with marginal assessments for each prospect (e.g., what is the probability that the well is wet?) and pairwise assessments of the dependence between prospects (e.g., what is the probability that both wells i and j are wet?). We then use information-theoretic methods to construct a full joint distribution for all outcomes from these marginal and pairwise assessments. This joint distribution is straightforward to calculate, has many nice properties, and appears to provide an accurate approximation for distributions likely to be encountered in practice. Given this joint probability distribution, we determine an optimal drilling strategy using an efficient dynamic programming model. We illustrate these techniques with an oil exploration example and study how dependence and risk aversion affect the optimal drilling strategies. The information-theory-based techniques for constructing joint distributions and dynamic programming model for determining optimal exploration strategies could be used together or separately in many other applications.

Coupled mechanical–electromagnetic–thermal–hydraulic effects inNb3Sn cable-in-conduit conductors for ITER

The crucial multi-physics problem of how to extrapolate from the performance of an isolatedNb3Sn strand measured in the laboratory to the performance of a superconducting coil usingmulti-strand twisted cables is addressed here. We consider the particular case of the pathgoing from the LMI strand to the international thermonuclear experimental reactor (ITER)toroidal field model coil (TFMC), through its associated Full Size Joint Sample, theTFMC-FSJS. Mechanical, electromagnetic and thermal–hydraulic conditions are simulatedusing the ANSYS, ENSIC and Mithrandir/M&M codes, respectively. At least in this case,the DC performance of the short sample turns out to be relatively close to (consideringerror bars) but not fully representative of that of the coil, showing higher (less compressive)effective thermal strain but also higher sensitivity to the electromechanical load.

Asymptotic Bayesian structure learning using graph supports for Gaussian graphical models

The theory of Gaussian graphical models is a powerful tool for independence analysis between continuous variables. In this framework, various methods have been conceived to infer independence relations from data samples. However, most of them result in stepwise, deterministic, descent algorithms that are inadequate for solving this issue. More recent developments have focused on stochastic procedures, yet they all base their research on strong a priori knowledge and are unable to perform model selection among the set of all possible models. Moreover, convergence of the corresponding algorithms is slow, precluding applications on a large scale. In this paper, we propose a novel Bayesian strategy to deal with structure learning. Relating graphs to their supports, we convert the problem of model selection into that of parameter estimation. Use of non-informative priors and asymptotic results yield a posterior probability for independence graph supports in closed form. Gibbs sampling is then applied to approximate the full joint posterior density. We finally give three examples of structure learning, one from synthetic data, and the two others from real data.