Management of malignant hyperthermia susceptible parturients

The management of eleven women susceptible to malignant hyperthermia during twenty deliveries is presented. These women were managed over a six-year period following guidelines that were established in 1990. Initial problems identified were the management of labour and caesarean section, the use of sympathomimetics and potential problems for the newborn, viz placental transfer of drugs and the possibility of a stress-induced malignant hyperthermia reaction in the newborn. There was little evidence that the stress of labour produced hypermetabolic responses in either mother or neonates and the use of sympathomimetics increased throughout the six-year period with no evidence of adverse effects. A caesarean section using general anaesthesia was not required but the management of this situation is described in both the protocol and discussion sections of this paper.     

Miniaturised optical encoder for ultra precision metrology systems

We report here on a novel high resolution optical encoder, which can be employed within ultra precision metrology systems. Microsystems techniques have been used to monolithically integrate the discrete components of an encoder onto a single compound semiconductor chip, thereby radically reducing the footprint and cost of assembly. Gratings manufactured at the wafer level by standard photo-lithography, allow for the simultaneous alignment of many devices in a single process step. This development coupled with a unique photodiode configuration not only significantly increases performance but also improves the alignment tolerances in both manufacture and set-up, which substantially reduces the required set-up time. The optical encoder chip has been successfully demonstrated under test conditions on a 4 μm pitch scale: alignment tolerances have been increased with DC to AC ratios of the order of 7:1 and signal-to-noise ratios greater than 40:1.     

Validation of ISO method 11290 part 2. Enumeration of Listeria monocytogenes in foods.

The European and International Standard method for the enumeration of Listeria monocytogenes, described in EN ISO 11290 Part 2: 1998 [EN ISO 11290-2 Microbiology of Food and Animal Feedingstuffs-Horizontal Method for the Detection and Enumeration of L. monocytogenes: Part 2. Enumeration; International Organisation for Standardisation, Geneva.] was validated by order of the European Commission (Standards, Measurement and Testing Fourth Framework Programme Project SMT4-CT96-2098). The objective was to determine the precision of the method in terms of repeatability (r) and reproducibility (R) using three different food types inoculated with various levels of L. monocytogenes and a typical background flora. The results are intended for publication in the associated standards. Cheese, meat, dried egg powder and reference materials were examined by 21 laboratories in 16 countries in Europe. Each participant received eight test materials per food type: blind duplicates at four inoculum levels (0, 10(2), 10(3), 10(4) cfu/g). In addition, two reference materials containing L. monocytogenes were included in the study. All test materials were subjected to stringent homogeneity and stability testing before being used in the collaborative trial. Participants were required to use only PALCAM agar for enumeration of L. monocytogenes, as prescribed by the reference method. Statistical analyses has been performed using a newly introduced approach for food microbiology (draft standard prEN ISO 16140 [prEN ISO 16140 Microbiology of Food and Animal Feedingstuffs-Protocol for the Validation of Alternative Methods, International Organisation for Standardisation, Geneva.], the precision data being calculated using robust estimates. Overall values for repeatability (r) of EN ISO 11290-2 when used with food test materials were r = log10 0.58 (expressed as an absolute difference between log10-transformed test results) or r = 3.8 (expressed as an absolute ratio between test results on the normal scale). For the reference materials (capsules containing approximately 5000 cfu), r = log10 0.34 (expressed as an absolute difference between log10-transformed test results) or r = 2.2 (expressed as an absolute ratio between test results on the normal scale). Overall values for reproducibility (R) of EN ISO 11290-2 when used with food test materials were R = log10 0.81 (expressed as a difference between log10-transformed test results) or R = 6.5 (expressed as an absolute ratio between test results on the normal scale). For the reference materials, R = log10 0.51 (expressed as a difference between log10-transformed test results) or R = 3.2 (expressed as an absolute ratio between test results on the normal scale). Further studies have been initiated by ISO TC34/SC9 to try to enhance the isolation of L. monocytogenes from foods and improve the confirmation procedures.     

Assessment of the pore geometry of stereolithographic models by high resolution MRI

It is becoming increasingly evident that material strength and other mechanical properties depend not only on the density but also on the internal architecture of the structure in question. The internal structures of five different stereolithographic samples were examined noninvasively using high resolution magnetic resonance imaging (MRI). The image analysis techniques of segmentation applied to the acquired images allowed the quantification of the structural parameters mean pore size and pore separation. These parameters were quantified along many angular orientations with a spatial resolution of 0.12 mm, and their distributions clearly revealed the structural anisotropy of the samples.     

Efficient block size selection in H.264 video coding standard

Selecting an efficient variable block size mode in H.264 video coding standard for better compression performance is considered. The proposed scheme is based on a 3D recursive search algorithm and takes into account the motion vector cost and previous frame information. The best mode for the current macroblock is obtained by analysing the modes for a maximum of four macroblocks in the current and previous frames. An improvement in the encoding time with negligible impact on subjective and quantitative performance has been achieved.     

Quantification of self-polishing in vivo from explanted metal-on-metal total hip replacements

One of the claimed advantages of metal-on-metal total hip replacements is that they ‘self-polish’ in the body, however this assertion has not been supported by quantitative data. Two pairs of components, each consisting of a femoral head and acetabular cup, were obtained at revision surgery. They were subject to topographical analysis using a non-contacting profilometer. In the ‘worn’ regions a reduction in surface roughness was seen alongside a change in skewness values from positive to negative, while elastohydrodynamic theory suggested an improvement towards mild mixed lubrication during gait. Therefore self-polishing of metal-on-metal total hip replacements can occur in vivo.     

Organohalogenated contaminants in eggs of rockhopper penguins (Eudyptes chrysocome) and imperial shags (Phalacrocorax atriceps) from the Falkland Islands

In this study, we evaluated the use of seabird eggs of two common bird species from the Falkland Islands as bioindicators of contamination with organohalogenated contaminants (OHCs). We compared contamination levels and profiles of different OHCs between eggs of the rockhopper penguin (Eudyptes chrysocome) and the imperial shag (Phalacrocorax atriceps). In addition, laying order effects on OHC concentrations and profiles were also investigated in both species. For polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) as well as polybrominated diphenyl ethers (PBDEs), concentrations were significantly lower in eggs of rockhopper penguins (27.6 ± 0.70 ng/g lw, 56.5 ± 1.33 ng/g lw and 0.98 ± 0.04 ng/g lw, respectively) compared to the imperial shags (140 ± 5.54 ng/g lw, 316 ± 11.53 ng/g lw, 1.92 ± 0.15 ng/g lw, respectively). On the other hand, 2′MeO-BDE 68 and 6MeO-BDE 47, two brominated compounds of reported natural origin, were significantly higher in the penguin eggs (0.55 ± 0.05 ng/g lw and 7.01 ± 0.64 ng/g lw, respectively) compared to the shag eggs (0.17 ± 0.03 ng/g lw and 0.50 ± 0.06 ng/g lw, respectively). In addition, PCB, OCP and PBDE contamination profiles differed markedly between the two species. Various factors, such as diet, feeding behaviour, migratory behaviour and species-specific metabolism, may be responsible for the observed results. For both rockhopper penguins and imperial shags, PCB, OCP and PBDE concentrations and profiles did not significantly change in relation to the laying order. This suggests that, for both species, any egg of a clutch is useful as a biomonitoring tool for OHCs. Although our results showed that OHCs have also reached the Falkland Islands, concentrations were relatively low compared to other studies. However, future monitoring may be warranted to assess temporal trends of different OHCs.     

Characterization of polyphenol oxidase from Uapaca kirkiana fruit

Polyphenol oxidase (PPO), the enzyme responsible for the postharvest spoilage of fruits, was extracted and purified from Uapaca kirkiana peel and pulp by ammonium sulfate precipitation and dialysis. Further purification of peel PPO was carried out by gel filtration chromatography. Optimum pH values were 7 and 8 for peel and pulp PPO, respectively. The optimum temperatures for peel and pulp PPO were 45 and 35 °C, respectively. Inhibition studies of the PPO enzyme were performed using citric acid, sodium azide, sodium metabisulfite and thiourea. The most effective inhibitors were sodium azide and citric acid for both peel and pulp PPO. V_max and K_m values were 13.63 units min^?1 and 4.923 mmol L^?1, respectively, for peel PPO and 14.03 units min^?1 and 5.43 mmol L^?1, respectively, for pulp PPO. Three isoenzymes of Uapaca kirkiana PPO were detected by polyacrylamide gel electrophoresis. One of the isoenzymes could be identified as having a molecular weight of 26 625 Da. Copyright © 2005 Society of Chemical Industry     

An actuator disk method with tip‐loss correction based on local effective upstream velocities

This work aims at assessing the performance of a tip‐loss correction for advanced actuator disk (AD) methods coupled to large eddy simulation and making this correction possible in a wind farm configuration. The classical Glauert tip‐loss factor, commonly used in the blade element momentum method, is added here to correct the tip and the root induced velocities at the rotor. However, it requires a reference upstream velocity, which is problematic to define in complex flows, such as in wind farms. A methodology is proposed here to infer an effective upstream velocity local to each disk element, based on the one‐dimensional momentum theory and using only the local data at the rotor. This estimation is verified through a set of simulations, leading to good results in spite of the crude assumptions of the one‐dimensional momentum theory. This AD supplemented with the tip‐loss correction is compared with a high fidelity vortex particle‐mesh method, through the simulations in uniform wind of a constant circulation wind turbine and of a more realistic machine, the NREL‐5MW rotor. The results show that the AD behavior is clearly improved by the addition of a tip‐loss factor and the potential errors on the effective upstream velocity estimation have a moderate impact on the tip‐loss correction.