Experimental Study of Interfacial Stress Distribution of Bonded-in BFRP Rod Glulam Joints Using Fibre Optic Sensors (FOS)

In this study, fibre optic sensors (FOS) were used to investigate the interfacial stress-strain behaviour of bonded-in basalt fibre reinforced polymer (BFRP) rods loaded into glulam members. Pull-out tests were conducted to examine the effect of bonded length and load-to-grain direction on the distribution of stress at the BFRP rod/adhesive zone. It was observed that the stress concentration at the loaded end of the BFRP rod of the samples was significantly the highest while the unloaded end showed the lowest. Increasing the bonded length at the same loading configuration resulted in a decrease in stress concentration at the loaded end. The stress concentration at the loaded end of the perpendicular to the grain samples was relatively higher than that of the corresponding parallel to the grain samples.

Modified stiffened panel analysis methods for laser beam and friction stir welded aircraft panels

The introduction of advanced welding methods as an alternative joining process to riveting in the manufacture of primary aircraft structure has the potential to realize reductions in both manufacturing costs and structural weight. Current design and analysis methods for aircraft panels have been developed and validated for riveted fabrication. For welded panels, considering the buckling collapse design philosophy of aircraft stiffened panels, strength prediction methods considering welding process effects for both local-buckling and post-buckling behaviours must be developed and validated. This article reports on the work undertaken to develop analysis methods for the crippling failure of stiffened panels fabricated using laser beam and friction stir welding. The work assesses modifications to conventional analysis methods and finite-element analysis methods for strength prediction. The analysis work is validated experimentally with welded single stiffener crippling specimens. The experimental programme has demonstrated the potential static strength of laser beam and friction stir welded sheet-stiffener joints for post-buckling panel applications. The work undertaken has demonstrated that the crippling behaviour of welded stiffened panels may be analysed considering standard-buckling behaviour. However, stiffened panel buckling analysis procedures must be altered to account for the weld joint geometry and process altered material properties. © IMechE 2006.

Is perception of upper body orientation based on the inertia tensor? Normogravity versus microgravity conditions

During lateral leg raising, a synergistic inclination of the supporting leg and trunk in the opposite direction to the leg movement is performed in order to preserve equilibrium. As first hypothesized by Pagano and Turvey (J Exp Psychol Hum Percept Perform, 1995, 21:1070-1087), the perception of limb orientation could be based on the orientation of the limb's inertia tensor. The purpose of this study was thus to explore whether the final upper body orientation (trunk inclination relative to vertical) depends on changes in the trunk inertia tensor. We imposed a loading condition, with total mass of 4 kg added to the subject's trunk in either a symmetrical or asymmetrical configuration. This changed the orientation of the trunk inertia tensor while keeping the total trunk mass constant. In order to separate any effects of the inertia tensor from the effects of gravitational torque, the experiment was carried out in normo- and microgravity. The results indicated that in normogravity the same final upper body orientation was maintained irrespective of the loading condition. In microgravity, regardless of loading conditions the same (but different from the normogravity) orientation of the upper body was achieved through different joint organizations: two joints (the hip and ankle joints of the supporting leg) in the asymmetrical loading condition, and one (hip) in the symmetrical loading condition. In order to determine whether the different orientations of the inertia tensor were perceived during the movement, the interjoint coordination was quantified by performing a principal components analysis (PCA) on the supporting and moving hips and on the supporting ankle joints. It was expected that different loading conditions would modify the principal component of the PCA. In normogravity, asymmetrical loading decreased the coupling between joints, while in microgravity a strong coupling was preserved whatever the loading condition. It was concluded that the trunk inertia tensor did not play a role during the lateral leg raising task because in spite of the absence of gravitational torque the final upper body orientation and the interjoint coupling were not influenced.

Hand arthritis in systemic lupus erythematosus: an ultrasound pictorial essay.

A small minority of systemic lupus erythematosus (SLE) patients may develop a deforming arthritis, typically with a non-erosive (Jaccoud's) pattern, although erosive features indistinguishable from rheumatoid arthritis may also occur. High-resolution ultrasonography (HRUS) allows detailed 'real time' imaging of joint and tendon morphostructural changes involving the hand in patients with several rheumatic diseases. The main aim of this pictorial essay is to provide the first descriptive HRUS and power Doppler (PD) findings of joint and tendon involvement of the hand and wrist in patients with SLE arthritis. Seventeen patients with SLE and hand involvement were examined. HRUS of the wrist, 2nd and 3rd MCP joints, 3rd PIP joint and 2nd, 3rd and 4th finger flexor tendons were studied in the dominant hand for each patient. Sixteen (94%) patients had joint effusion or synovial hypertrophy in the wrist. Twelve (71%) patients had joint effusion or synovial hypertrophy in 2nd or 3rd MCPJs. Eight (47%) patients had erosion at 2nd or 3rd MCPJs. In three cases erosions were not present radiologically. Eleven (65%) patients had evidence of tenosynovitis. In SLE, HRUS with PD detects a high prevalence of inflammatory pathology in the tendons and synovium of the hand and wrist, and a high prevalence of MCP joint erosions. HRUS offers a sensitive, real-time and readily repeatable assessment of soft-tissue, inflammatory and bony changes in SLE hands.

Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera.

Ulva, one of the first Linnaean genera, was later circumscribed to consist of green seaweeds with distromatic blades, and Enteromorpha Link was established for tubular forms. Although several lines of evidence suggest that these generic constructs are artificial, Ulva and Enteromorpha have been maintained as separate genera. Our aims were to determine phylogenetic relationships among taxa currently attributed to Ulva, Enteromorpha, Umbraulva Bae et I.K. Lee and the monotypic genus Chloropelta C.E. Tanner, and to make any nomenclatural changes justified by our findings. Analyses of nuclear ribosomal internal transcribed spacer DNA (ITS nrDNA) (29 ingroup taxa including the type species of Ulva and Enteromorpha), the chloroplast-encoded rbcL gene (for a subset of taxa) and a combined data set were carried out. All trees had a strongly supported clade consisting of all Ulva, Enteromorpha and Chloropelta species, but Ulva and Enteromorpha were not monophyletic. The recent removal of Umbraulva olivascens (P.J.L. Dangeard) Bae et I.K. Lee from Ulva is supported, although the relationship of the segregate genus Umbraulva to Ulvaria requires further investigation. These results, combined with earlier molecular and culture data, provide strong evidence that Ulva, Enteromorpha and Chloropelta are not distinct evolutionary entities and should not be recognized as separate genera. A comparison of traits for surveyed species revealed few synapomorphies. Because Ulva is the oldest name, Enteromorpha and Chloropelta are here reduced to synonymy with Ulva, and new combinations are made where necessary.

Reinforced Stone Columns in Weak Deposits – A Laboratory Model Study

This paper investigates the performance of stone columns in a weak deposit such as peat. It evaluates the effects of reinforcing stone columns by jacketing with a tubular wire mesh and bridging reinforcement with a metal rod and a concrete plug. A series of plate loading tests was conducted on isolated stone columns installed in a soil bed consisting of a peat layer sandwiched between two layers of sand. The load–displacement characteristics of footings supported by stone columns were investigated by applying load to a circular plate supported on: (a) untreated soil; (b) soil treated with stone columns; and (c) soil treated with stone columns reinforced with the above reinforcing techniques. The work has shown that the settlement characteristics of the soil can be improved by installing stone columns and that a significant enhancement in the load–settlement response is achieved when the columns are reinforced by the various methods.

The Characterization of Friction Stir Welding Process Effects on Stiffened Panel Buckling Performance

The introduction of advanced welding methods as an alternative joining process to riveting in the manufacture of primary aircraft structure has the potential to realize reductions in both manufacturing costs and structural weight. However, welding processes can introduce undesirable residual stresses and distortions in the final fabricated components, as well as localized loss of mechanical properties at the weld joints. The aim of this research is to determine and characterize the key process effects of advanced welding assembly methods on stiffened panel static strength performance. This in-depth understanding of the relationships between welding process effects and buckling and collapse strength is required to achieve manufacturing cost reductions without introducing structural analysis uncertainties and hence conservative over designed welded panels. This current work is focused at the sub-component level and examines the static strength of friction stir welded multi stiffener panels. The undertaken experimental and computational studies have demonstrated that local skin buckling is predominantly influenced by the magnitude of welding induced residual stresses and associated geometric distortions, whereas panel collapse behavior is sensitive to the lateral width of the physically joined skin and stiffener flange material, the strength of material in the Heat Affected Zone as well as the magnitude of the welding induced residual stresses. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


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Reducing Drifts in the Inertial Measurements of Wrist and Elbow Positions

In this paper, we present an inertial-sensor-based monitoring system for measuring the movement of human upper limbs. Two wearable inertial sensors are placed near the wrist and elbow joints, respectively. The measurement drift in segment orientation is dramatically reduced after a Kalman filter is applied to estimate inclinations using accelerations and turning rates from gyroscopes. Using premeasured lengths of the upper and lower arms, we compute the position of the wrist and elbow joints via a proposed kinematic model. Experimental results demonstrate that this new motion capture system, in comparison to an optical motion tracker, possesses an RMS position error of less than 0.009 m, with a drift of less than 0.005 ms-1 in five daily activities. In addition, the RMS angle error is less than 3??. This indicates that the proposed approach has performed well in terms of accuracy and reliability.

Comparative analysis of synovial fluid and plasma proteomes in juvenile arthritis - Proteomic patterns of joint inflammation in early stage disease

Synovial fluid is a potential source of novel biomarkers for many arthritic disorders involving joint inflammation, including juvenile idiopathic arthritis. We first compared the distinctive protein ‘fingerprints’ of local inflammation in synovial fluid with systemic profiles within matched plasma samples. The synovial fluid proteome at the time of joint inflammation was then evaluated across clinical subgroups to identify early disease associated proteins. We measured the synovial fluid and plasma proteomes using the two-dimensional fluorescence difference gel electrophoresis approach. Image analysis software was used to highlight the expression levels of joint and subgroup associated proteins across the study cohort (n = 32). A defined subset of 30 proteins had statistically significant differences (p < 0.05) between sample types such that synovial fluid could be differentiated from plasma. Furthermore distinctive synovial proteome expression patterns segregate patient subgroups. Protein expression patterns localized in the chronically inflamed joint therefore have the potential to identify patients more likely to suffer disease which will spread from a single joint to multiple joints. The proteins identified could act as criteria to prevent disease extension by more aggressive therapeutic intervention directed at an earlier stage than is currently possible.

Resolution of a taxonomic conundrum: an ultrastructural and molecular description of the life cycle of Pleistophora mulleri (Pfeiffer 1895; Georgevitch 1929)

The classification of a microsporidian parasite observed in the abdominal muscles of amphipod hosts has been repeatedly revised but still remains inconclusive. This parasite has variable spore numbers within a sporophorous vesicle and has been assigned to the genera Glugea, Pleistophora, Stempellia, and Thelohania. We used electron microscopy and molecular evidence to resolve the previous taxonomic confusion and confirm its identification as Pleistophora mulleri. The life cycle of P. mulleri is described from the freshwater amphipod host Gammarus duebeni celticus. Infection appeared as white tubular masses within the abdominal muscle of the host. Light and transmission electron microscope examination revealed the presence of an active microsporidian infection that was diffuse within the muscle block with no evidence of xenoma formation. Paucinucleate merogonial plasmodia were surrounded by an amorphous coat immediately external to the plasmalemma. The amorphous coat developed into a merontogenetic sporophorous vesicle that was present throughout sporulation. Sporogony was polysporous resulting in uninucleate spores, with a bipartite polaroplast, an anisofilar polar filament and a large posterior vacuole. SSU rDNA analysis supported the ultrastructural evidence clearly placing this parasite within the genus Pleistophora. This paper indicates that Pleistophora species are not restricted to vertebrate hosts.

Secretory products of the haptoral reservoirs and peduncular glands in two species of Bravohollisia (Monogenea : Ancyrocephalidae)

Light and electron microscopy were used to characterize the structure of secretory cells and their products involved in attachment of two monogenean parasites of fish, in order to understand their role in the attachment process. In Bravohollisia rosetta and Bravohollisia gussevi, peduncular gland cells with two nuclei, granular endoplasmic reticulum, and Golgi bodies produce dual electron-dense (DED) secretory bodies with a homogenous electron-dense rind and a less electron-dense fibrillar core (oval and concave in B. rosetta and oval in B. gussevi). The DED secretory bodies are altered as they migrate from the gland cell to the haptoral reservoir, the superficial anchor grooves, and into the gill tissues. The contents of the DED secretory bodies are exocytosed into the reservoirs, fibrillar cores persisting in the matrix, some of which condense, forming highly electron-dense spherical bodies. Small, oval, electron-dense bodies occur in the grooves, while no inclusions are visible in the homogenous exudate within the gill tissues. The single tubular extension of the reservoir enters a bifurcate channel within the anchor via a concealed, crevice-like opening on one side of the anchor. The channel directs secretions into the left and the right grooves via concealed apertures. The secretions, introduced into the tissues by the anchors, probably assist in attachment. The secretions are manifested externally as net-like structures and observed in some cases to be still attached to the point of exudation, on anchors detached from the gill tissues. This suggests that despite having the anchors detached, the worms can still remain anchored to the gill tissues via these net-like structures. Based on this, it is postulated that the net-like secretions probably function as a safety line to anchor the worm during the onset of locomotion and in doing so reduce the risk of tearing host tissues.

Stratification and Monitoring of Juvenile Idiopathic Arthritis Patients by Synovial Proteome Analysis

Juvenile idiopathic arthritis (JIA) comprises a poorly understood group of chronic, childhood onset, autoimmune diseases with variable clinical outcomes. We investigated whether profiling of the synovial fluid (SF) proteome by a fluorescent dye based, two-dimensional gel (DIGE) approach could distinguish patients in whom inflammation extends to affect a large number of joints, early in the disease process. SF samples from 22 JIA patients were analyzed: 10 with oligoarticular arthritis, 5 extended oligoarticular and 7 polyarticular disease. SF samples were labeled with Cy dyes and separated by two-dimensional electrophoresis. Multivariate analyses were used to isolate a panel of proteins which distinguish patient subgroups. Proteins were identified using MALDI-TOF mass spectrometry with expression further verified by Western immunoblotting and immunohistochemistry. Hierarchical clustering based on the expression levels of a set of 40 proteins segregated the extended oligoarticular from the oligoarticular patients (p <0.05). Expression patterns of the isolated protein panel have also been observed over time, as disease spreads to multiple joints. The data indicates that synovial fluid proteome profiles could be used to stratify patients based on risk of disease extension. These protein profiles may also assist in monitoring therapeutic responses over time and help predict joint damage. © 2009 American Chemical Society.

DNA methylation profiling in cell models of diabetic nephropathy

We have previously identified differentially expressed genes in cell models of diabetic nephropathy and renal biopsies. Here we have performed quantitative DNA methylation profiling in cell models of diabetic nephropathy. Over 3,000 CpG units in the promoter regions of 192 candidate genes were assessed in unstimulated human mesangial cells (HMCs) and proximal tubular epithelial cells (PTCs) compared to HMCs or PTCs exposed to appropriate stimuli. A total of 301 CpG units across 38 genes (similar to 20%) were identified as differentially methylated in unstimulated HMCs versus PTCs. Analysis of amplicon methylation values in unstimulated versus stimulated cell models failed to demonstrate a >20% difference between amplicons. In conclusion, our results demonstrate that specific DNA methylation signatures are present in HMCs and PTCs, and standard protocols for exposure of renal cells to stimuli that alter gene expression may be insufficient to replicate possible alterations in DNA methylation profiles in diabetic nephropathy.

Time domain wave separation using multiple microphones

Methods of measuring the acoustic behavior of tubular systems can be broadly characterized as steady state measurements, where the measured signals are analyzed in terms of infinite duration sinusoids, and reflectometry measurements which exploit causality to separate the forward and backward going waves in a duct. This paper sets out a multiple microphone reflectometry technique which performs wave separation by using time domain convolution to track the forward and backward going waves in a cylindrical source tube. The current work uses two calibration runs (one for forward going waves and one for backward going waves) to measure the time domain transfer functions for each pair of microphones. These time domain transfer functions encode the time delay, frequency dependent losses and microphone gain ratios for travel between microphones. This approach is applied to the measurement of wave separation, bore profile and input impedance. The work differs from existing frequency domain methods in that it combines the information of multiple microphones within a time domain algorithm, and differs from existing time domain methods in its inclusion of the effect of losses and gain ratios in intermicrophone transfer functions.

Retinal vascular endothelial cell endocytosis increases in early diabetes.

BACKGROUND: Several physiological studies in recent years have convincingly demonstrated increased clearance of intravascular protein tracers by several different tissues, including the retina, during early diabetes and galactosemia in the rat. This change has been described as a consequence of increased permeation, although vascular leakage has not been demonstrated, and the fate of such tracers remains unelucidated. EXPERIMENTAL DESIGN: A pilot study in this laboratory showed no evidence of vascular leakage but suggested increased endocytosis of horseradish peroxidase (HRP) by retinal vascular endothelial cells (RVECs) in early diabetes. We therefore quantified RVEC endocytosis in normal, streptozotocin (STZ)-treated nondiabetic and STZ-diabetic rats using the design-based stereology method of "vertical sections." A duration of diabetes (6 weeks) was chosen to approximate the time period in which other workers have demonstrated increased protein permeation of the retina. RESULTS: After a 20-minute exposure to the tracer, HRP reaction product was observed in small vesicular and tubular endosomes and larger multivesicular bodies of the RVECs. Stereological analysis revealed a 6.5-fold increase in the volume of HRP-containing organelles in the RVECs of diabetic rats compared with STZ-treated nondiabetics or normal controls. None of the animals in this study showed HRP reaction product outside the retinal vascular endothelium. CONCLUSIONS: A highly significant increase in RVEC endocytosis occurs in early diabetes. Increased RVEC endocytosis may contribute to the observed clearance of intravascular protein tracers by the retina during early diabetes.