Bilateral radial ray hypoplasia with multiple epiphyseal dysplasia

Flexion reflexes, elicited by surface stimulation, can be used to produce a simple form of stepping in spinal cord injured (SCI) humans. A drawback of this approach is a decreasing magnitude of flexion reflex to repeated presentations of the stimuli (habituation). Pilot data indicated that high intensity stimulation could produce dishabituation of the reflex. The aim of this study was to examine and quantify the inter- and intra-subject variability of the short and long term conditioning effect of high intensity stimulation on the magnitude of flexion reflexes in a larger number of SCI subjects. Dishabituation was observed in all subjects, however the amount of dishabituation observed was small and highly variable. However the use of high intensity conditioning stimulation may offer a means of coping with habituation in a small number of subjects.     

A model for the transverse strain response of unidirectional ceramic matrix composites during tensile testing

A comprehensive micromechanical model relating the longitudinal stress and transverse strain of unidirectional fibre toughened ceramic matrix composites (CMCs) is presented. The model uses different cylindrical unit-cells to describe the composite throughout a tensile test and considers all relevant damage mechanisms. The proposed model takes into account the Poisson contraction of fibre and matrix, the relief of thermal residual stresses upon damage development, and the build-up of compressive radial stresses at the interface due to mismatch between fibre and matrix after debonding and sliding. Thus the modelled transverse strain response depends on a wide range of microstructural and micromechanical parameters. The approach is checked by comparing the experimentally observed and simulated response of a unidirectional SiC/CAS composite of which all constituent properties were determined experimentally. The agreement between experiment and theory is excellent.     

THE EFFECT OF CORRELATED ARRIVALS ON QUEUES

Using Markov renewal arrival processes, a study of the effect of serial correlations in the arrival process on the mean queueing performance has been done. We show that positive serial correlations may have major impact on the mean queue lengths (and consequently on other performance measures).     

Fully refocused multi-shot spatiotemporally encoded MRI: robust imaging in the presence of metallic implants

Object

An approach has been recently introduced for acquiring arbitrary 2D NMR spectra or images in a single scan, based on the use of frequency-swept RF pulses for the sequential excitation and acquisition of the spins response. This spatiotemporal-encoding (SPEN) approach enables a unique, voxel-by-voxel refocusing of all frequency shifts in the sample, for all instants throughout the data acquisition. The present study investigates the use of this full-refocusing aspect of SPEN-based imaging in the multi-shot MRI of objects, subject to sizable field inhomogeneities that complicate conventional imaging approaches.

Materials and methods

2D MRI experiments were performed at 7 T on phantoms and on mice in vivo, focusing on imaging in proximity to metallic objects. Fully refocused SPEN-based spin echo imaging sequences were implemented, using both Cartesian and back-projection trajectories, and compared with k-space encoded spin echo imaging schemes collected on identical samples under equal bandwidths and acquisition timing conditions.

Results

In all cases assayed, the fully refocused spatiotemporally encoded experiments evidenced a ca. 50?% reduction in signal dephasing in the proximity of the metal, as compared to analogous results stemming from the k-space encoded spin echo counterparts.

Conclusion

The results in this study suggest that SPEN-based acquisition schemes carry the potential to overcome strong field inhomogeneities, of the kind that currently preclude high-field, high-resolution tissue characterizations in the neighborhood of metallic implants.     

Effects of dietary inclusion of xylooligo‐ saccharides,arabinoxylooligosaccha‐ rides and soluble arabinoxylan on the microbial composition of caecal contents of chickens

BACKGROUND: Arabinoxylan (AX)‐derived preparations have raised particular interest by the suggestion that they exert prebiotic properties. Therefore an in vivo experiment was conducted to study the effects of xylooligosaccharides (XOS), arabinoxylooligosaccharides (AXOS) and soluble AX (S‐AX) on several groups of gut bacteria of chickens. Chickens were fed a control diet or the same diet supplemented with 2.5 g kg^?1 of XOS (average degree of polymerisation (avDP) of 3, average degree of arabinose substitution (avDS) of 0.09), wheat bran‐derived AXOS (avDP 9, avDS 0.34) or wheat endosperm alkali‐solubilised AX (S‐AX, avDP > 6000, avDS 0.5). RESULTS: All treatment groups showed an increase in the number of caecal bifidobacteria after 2 weeks of feeding (P < 0.05), while the treatments did not impact numbers of Enterobacteriaceae and aerobic lactobacilli in the caeca relative to the control. XOS led to a tremendous increase in caecal bifidobacteria counts (10⁸ g^?1 for the XOS treatment versus 10³ g^?1 for the control treatment) after only 1 week of supplementation, while AXOS and S‐AX led to similar strong increases in bifidobacteria counts after 2 weeks of supplementation. Addition of S‐AX to the diet, but not of AXOS or XOS, led to a significantly decreased (P < 0.05) body weight gain after 2 weeks of feeding relative to animals on the control diet, consistent with its known viscosity‐related antinutritive effects in chickens. CONCLUSION: Similar to XOS, AXOS selectively stimulate the presence of bifidobacteria in the caeca of chickens, establishing their bifidogenic effect as a first indicator for prebiotic potential. Copyright © 2008 Society of Chemical Industry     

Some physiological characteristics to estimate species potential as a mine reclamation ground cover

In finding what physiological characteristics can be used to predict ground cover success on mine reclamation sites, 14 herb and grass species were tested. Establishment and early growth was tested on three different soils, ie vermiculate and quartz sand mixture, quarry overburden and coal mine overburden in a greenhouse. The results indicate that plant height and cover, transpiration rate and foliar pigments may be used to select plant adaptability to mined soil. White clover (Trifolium repens L.) showed the greatest potential as ground cover for mined soils. Species most widely used in reclamation tended to be perennials of moderate rate.