Image of pseudocapture caused by micro-dislodgment of the electrode in a VDD pacemaker

The new AV sequential pacemakers have improved the suitability for the election of the best pacing mode for each patient. The complexity of the systems may mask some dysfunctions. In the presented case, a failure to capture due to micro-dislodgment, may have been missed in a simple pacemaker control, because of the combination of several factors: the presence of normal AV conduction at that moment, the concordance between the pacemaker stimulus and the conducted QRS complex and the similar morphology of the conducted and paced QRS complex.     

The production of monoenergetic fast neutrons of known flux: An improved method to identify the associated particle

The performance of a deuterium gas target to produce neutrons from the D(d, n)³He reaction is reported. The associated particle method is used. The associated particle is unequivocally identified with a telescope employing microchannel-plate electron multipliers and a silicon surface barrier detector, providing both time-of-flight (TOF) and energy (E) information. The system was set up at the 7 MV Van de Graaff CN accelerator of the laboratori Nazionali di Legnaro (Padova), and has been tested with deuteron energies from 2.5 to 6.5 MeV. About 300 tagged neutrons per s sr nA atm are produced. The TOF-E identification method to discriminate the associated particle will be used in the future in measurements at higher deuteron energies and with the reaction T(d, n)⁴He.     

Limits of pulmonary resection

Foreign body aspiration in children may present with a variety of symptoms. We report here an unusual case of laryngeal foreign body in an infant masquerading as laryngeal web in its clinical presentation as well as radiological findings. The diagnosis was only made at endoscopy, thus emphasising the limited sensitivity of radiographic studies in identifying this condition.     

LASER-DRILLING APPLICATION TO A CERAMIC-COATED ALLOY

The capability of laser drilling applied to various materials is first outlined. The article then focuses on the study of material removal by the laser beam which influences the quality of the hole since “recast”, i.e. resolidified material, often exhibits microcracking, modifies the shape and more generally the properties of the hole due to a sort of coating of the hole inner wall.

A fluid-mechanics approach to describe the removal phenomena is proposed and validated using experimental data. This approach is coupled with results from a thermal model developed in a recently published paper (1). Solidification and cracking phenomena were also investigated using a SEM (Scanning Electron Microscope) to observe accurately the most significant microstructural features, such as the interdendritic spacings.     

Description and experimental results of a semi-indirect ceramic evaporative cooler

Evaporative cooling is used in industrial and air conditioning processes to reduce temperature in different fluids. Direct evaporation systems can lead to environmental problems such as Legionnaire's disease, and indirect systems reduce system efficiency.This work presents the manufacture, test bed set up and trials carried out on a ceramic evaporative cooling system which acts as a semi-indirect cooler. Depending on air characteristics, it may act as a sensible or enthalpic exchanger. The water cooled in a cooling tower, using the return air coming from the conditioned room (22 °C and 50% comfort conditions) goes through the ceramic pipes, exchanging sensible and latent heat with a current of outdoor air.The use of this recovery system is mainly in climates with a high temperature and humidity such as tropical environments where the system yields a decrease in supply air humidity, using the cooling power of return air.The tests presented show the system behaviour for various supply air conditions.     

Nutritional status of marginated children of the Madrid's autonomous community, Spain

The nutritional status of 101 institutionalized students aged 6 to 13 was assessed from the dietary and biochemical points of view. The children were pupils of a Youth Care Boarding School. The dietary survey revealed an adequate nutrient intake which met the Recommended Dietary Allowances (RDA) in most cases as well as a high protein intake (250% of RDA). A slight deficiency in energy, zinc, magnesium and vitamins B2 and C was found in some cases in the eldest group. Blood parameters (erythrocyte counts, hematocrit, hemoglobin, mean corpuscular values, serum proteins, albumin, globulins, albumin/globulin ratio, urea and cholesterol) showed slightly lower values, mainly on hemoglobin, than those obtained from other similar groups. Nevertheless, urine parameters (nitrogen, urea, uric acid and creatinine) were higher, may be due to the high protein intake, energy deficiency and non-dietary factors such as lack of affection, socioeconomic problems, etc. All of these factors cause a rise in the students' catabolism. Correlations between dietary and biochemical data seem to corroborate that there is a shortage of energy, zinc, riboflavin, magnesium and vitamin C intakes in some cases, which limits the build up of several blood elements.     

Age-related changes in adenosine in rat coronary resistance vessels

The purpose of the present investigation was to determine if the efficacy of amoxicillin-clavulanate against penicillin-resistant Streptococcus pneumoniae could be improved by increasing the pediatric amoxicillin unit dose (90 versus 45 mg/kg of body weight/day) while maintaining the clavulanate unit dose at 6.4 mg/kg/day. A rat pneumonia model was used. In that model approximately 6 log10 CFU of one of four strains of S. pneumoniae (amoxicillin MICs, 2 microg/ml [one strain], 4 microg/ml [two strains], and 8 microg/ml [one strain]) were instilled into the bronchi of rats. Amoxicillin-clavulanate was given by computer-controlled intravenous infusion to approximate the concentrations achieved in the plasma of children following the administration of oral doses of 45/6.4 mg/kg/day or 90/6.4 mg/kg/g/day divided every 12 h or saline as a control for a total of 3 days. Infusions continued for 3 days, and 2 h after the cessation of infusion, bacterial numbers in the lungs were significantly reduced by the 90/6.4-mg/kg/day equivalent dosage for strains for which amoxicillin MICs were 2 or 4 microg/ml. The 45/6.4-mg/kg/day equivalent dosage was fully effective only against the strain for which the amoxicillin MIC was 2 microg/ml and had marginal efficacy against one of the two strains for which amoxicillin MICs were 4 microg/ml. The bacterial load for the strain for which the amoxicillin MIC was 8 microg/ml was not reduced with either dosage. These data demonstrate that regimens which achieved concentrations in plasma above the MIC for at least 34% of a 24-h dosing period resulted in significant reductions in the number of viable bacteria, indicating that the efficacy of amoxicillin-clavulanate can be extended to include efficacy against less susceptible strains of S. pneumoniae by increasing the amoxicillin dose.     

Influence of carbon black dispersion on the thermal diffusivity of an SBR vulcanizate

There are few investigations of the influence of filler dispersion on the thermal diffusivity of carbon black rubber compounds. In this article, experimental results of a cured styrene–butadiene rubber (SBR) compound are presented in the range of temperatures between 210 and 350 K at four levels of dispersion obtained in a laboratory mill. The results of thermal diffusivity measurements are discussed in the frame of competitive mechanisms appearing during mixing and involving the breakdown of agglomerates into aggregates and particles in the rubber matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1379–1385, 1999