Variability of channel subconductance states of the cardiac sodium channel induced by protease.

Conductance and subconductance levels of voltage-activated sodium channels recorded using patch clamp techniques from isolated cardiac myocytes were accurately determined using signal processing techniques. From the tabulated amplitude distributions of the conductance levels, we inferred the most likely underlying distribution by applying the method of the kernel density estimate. When myocytes were prepared by dissociation of the heart with a solution containing collagenase as the only digestive enzyme, the fully open conductance level of the channel was 23 pS, with two prominent sublevels at 8 and 16 pS (280 mM sodium). When cells were dissociated in an identical manner but with solution containing added protease, the most frequent open levels of the channel were 9 and 15 pS. In these latter recordings, the channel also opened to 22 pS, but did so only rarely. The main conductance levels in cells dissociated with protease were essentially the same as the subconductance states in cells dissociated without protease. We infer that the conductance sublevels normally seen are, within experimental errors, 1/3 and 2/3 of the fully open level, and that the proteolytic enzyme modifies the channel such that it tends to open predominantly to the subconductance levels.     

Development of uranium carbide targets for the on-line production of neutron-rich isotopes

A number of on-line and off-line tests have been performed at the IRIS (investigation of radioactive isotopes at synchrocyclotron) facility in order to develop uranium carbide targets with a high density (11 g/cm³) for the on-line production of neutron-rich isotopes by fission of ²³⁸U. A 1 GeV proton beam was used to bombard two kinds of targets held at temperatures in the range of 1900–2100 °C. The first one was a target-ion source assembly slightly modified to withstand 3 months of continuous heating at a temperature of about 2050 °C. The second unit was of a new kind, where ionisation takes place in the target volume itself. A comparison of the on-line isotopic yields before and after heating for 3 months is here reported. The yields and release times of Rb, Cs and In are compared with the ones obtained from a standard reference target, as measured in previous experiments.     

Automated multiple headspace extraction procedure: adsorption modeling and determination of air-to-water partition coefficients

The present work makes the first attempt to take into account adsorptions in the determination of partition coefficients by modeling the multiple headspace extraction (MHE) process. Modeling a six-step MHE procedure of a homologous series of methyl ketones revealed that their adsorption-desorption on the walls was the rate-limiting step. Moreover, a comparison between experimental and predicted MHE plots shows that only the last MHE points were affected by adsorption phenomena. Using cell materials with the lowest sorptive properties, partition coefficients were then accurately calculated from the first four MHE steps. This kinetic approach supports previous work in which adsorptions were lowered owing to the choice of sampling cell materials. It also justifies some reproducibility limitations of the MHE quantification procedure mentioned in the literature.     

Asymptotic study of transverse conductivity in superconducting multifilamentary composites

This paper deals with superconducting multifilamentary composites with periodic structure in the presence of a weak electromagnetic field. We study the magnetic induction and establish an approximation result when the period is small (in the framework of homogenization theory). Then we determine some physical constants of an “equivalent” homogeneous conductor, and thus transverse conductivity can be obtained. For various proportions of superconductor, we compute both the values of transverse conductivity proposed by different physicists and the mathematical value obtained in this paper (we use finite elements and an overrelaxation method); we compare them between themselves and with recent experimental results; we note that our results are in very good agreement with Carr's formula and with the experimental measures of Davoust.     

Boundary detection and skeletonization with a massively parallelarchitecture

A massively parallel architecture called TOSCA (tokens sending cellular automation) is presented that performs edge pixel detection and skeletonization in the image processing area. Each cell of this cellular automaton has a very reduced set of instructions and a very small amount of memory. The computation is based on token propagation, counting devices, and local processing. The skeletonization method is based on the Chamfer distance     

Amelioration de la precision du dosage de l'oxygene dans le sodium par la methode d'amalgamation

The difficulties in analyzing oxygen present in trace amounts in liquid sodium by the amalgamation method stem from the possibility of contamination of sodium during the manipulations and transfers. The precision has been improved by developing a method of working which made it possible to estimate the contamination during each analysis. The results obtained are compared to the values obtained by the classical amalgamation method and also to those quoted by Noden, obtained by vacuum distillation or by use of the vanadium-wire and the electrolytic oxygen meter.     

Optical and structural properties of solution deposited nickel manganite thin films

Nickel manganite thin films of interest for microbolometer applications have been prepared using chemical solution and spin spray deposition and studied using transmission electron microscopy to quantify the material crystallinity and spectroscopic ellipsometry to extract the complex dielectric function (ε = ε₁ + iε₂) and film microstructure. A parameterization for ε over a spectral range from 0.04 to 5.15 eV has been developed to model well-crystallized nickel manganite, and the visible-range critical point features, infrared vibrations, and optical absorption onset have been identified. A multiple sample analysis structural model and procedure has been developed for spin spray deposited films exhibiting complicated void evolutions with thickness. Variations in ε and crystallite grain size have been observed as a function of film processing and indicate that the optical properties and microstructural information gained from spectroscopic ellipsometry is useful in process monitoring for this material system.     

Novel nonsense mutation in the hypoxanthine guanine phosphoribosyltransferase gene and nonrandom X-inactivation causing Lesch-Nyhan syndrome in a female patient

BACKGROUND: Patient views are important in the evaluation of the quality of health care. The use of surveys needs to be evaluated to determine their cost-effectiveness and benefits. OBJECTIVES: To determine the costs of conducting patient opinion surveys in general practice and to find out how effective patient surveys are in stimulating changes which are beneficial for patient care. METHOD: Postal questionnaire to all 102 medical audit advisory groups (MAAGs) and 98 family health services authorities (FHSAs) in England and Wales, followed by postal questionnaire to 302 general practices reported to have conducted surveys, sampled by the type or questionnaire used. Numbers of MAAGs and FHSAs reporting surveys in general practice; types of questionnaire used; estimated costs; changes made; and benefits identified were measured. RESULTS: Eighty-five (83%) MAAGs and 75 (77%) FHSAs responded. One hundred and fifty-four (96%) of MAAGs or FHSAs reported survey activity. Types of questionnaire used were 1) designed by the practice, 2) designed by the MAAG or FHSA, possibly in collaboration with a practice, or 3) standard 'off-the-shelf'. One hundred and thirty-three (44%) practices responded. Total costs to a practice of conducting a survey ranged from nothing to over 2200 Pounds. Questionnaires designed by the practice are likely to be more costly than other designs. Some practices had surveys provided free of charge by MAAG or FHSA. Sixty-one per cent of practices said changes had been implemented and a further 22% of practices said changes were planned. The most common change was to appointment systems. Benefits were identified for patients, staff, the practice, the MAAG or FHSA and the NHS. Surveys also brought benefits in relationships and understanding. Only 8.2% of practices felt the costs of surveys outweighed the benefits. CONCLUSIONS: Many practices are surveying patients' opinions. Surveys can be costly but MAAGs and FHSAs can provide expertise and resources. Surveys using any of the types of questionnaire are likely to lead to changes and identifiable benefits. Benefits of surveys are perceived by the majority of practices to outweigh the costs.     

Unusual Polarization Ordering in Lanthanum Modified Lead Zirconate Titanate (Pb0.97La0.03)(Zr0.90Ti0.10)0.9925O3

Lanthanum incorporation in lead zirconate titanate (PLZT) increases the stability range of the antiferroelectric phase in the Zr‐rich side of the phase diagram. The paper presents the analysis, which has been carried out on (Pb_0.97La_0.03)(Zr_0.90Ti_0.10)_0.9925O₃ ceramic system since it exhibits interesting results with ferroelectric (FE) and antiferroelectric (AFE) phases, and coexistence of both properties in some temperature range. Transmission electron microscopy evidences a complex domain structure, where nanodomains appear within larger ones. The data are consistent with the possibility to have in this material a ferroelastic phase of novel type in which the coexistence mechanism between FE and AFE properties is associated with the oscillation in space of the polarization. The possibility for a determining role of a rigid unit mode in structural instabilities, dependence on composition and doping, and pretransitional effects in the perovskite family is underlined by the obtained results for the studied system.