Atrial Flutter in Infants

ObjectivesWe sought to characterize the clinical nature of atrial flutter (AFL) in a large cohort of infants.BackgroundThere are no large studies describing the natural history of AFL in infants. Previous studies vary in the therapy used and expected prognosis.MethodsWe reviewed the records of all children younger than 1 year of age who were diagnosed with AFL at our hospital during the past 25 years, excluding those with previous cardiac surgery.ResultsWe identified 50 infants with AFL. Most, 36 (72%), presented within the first 48 h of life. Congestive heart failure was evident in 10 infants, with 6 presenting at 1 day of age, and 4 presenting beyond 1 month of age. The remainder were asymptomatic. A large atrial septal defect was the only structural heart disease. Spontaneous conversion to sinus rhythm occurred in 13 (26%) infants. Sinus rhythm was restored in 20 of 23 (87%) attempts at direct current cardioversion and 7 of 22 (32%) attempts at transesophegeal pacing; 7 required antiarrhythmic therapy. An additional arrhythmia, all supraventricular, appeared in 11 (22%) infants. The recurrence of AFL developed in 6 infants; 5 of 6 of these incidents occurred within 24 h of the first episode. All patients with recurrence had an additional arrhythmia.ConclusionsInfants with AFL usually present within the first 2 days of life. No association was found with structural heart disease. Direct current cardioversion appears to be most effective at establishing sinus rhythm. Chronic AFL has the potential to cause cardiovascular compromise. Atrial flutter in the absence of other arrhythmias has a low risk of recurrence. Once in sinus rhythm, infants with AFL have an excellent prognosis and may not require chronic antiarrhythmic therapy

Fractal-polarization correction in time domain dielectric spectroscopy

Electrode polarization appears self-similar in time and occurs even when the geometrical electrode structure is not fractal. Problems associated with electrode polarization in time domain dielectric spectroscopy of conductive liquids persist to much higher frequencies than generally appreciated. An explicit consideration of the fractal nature of such polarization, irrespective of the fractal (geometrical) structure of the electrode, leads to a concise correction for such polarization effects. This correction is illustrated for an aqueous electrolyte

Impurity generation during intense lower hybrid heating experiments on the Alcator C tokamak

and disposal, in whole or in part by or for the United States govern-ment is permitted. By acceptance of this article, the publisher and/or recipient ac-knowledges the U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright covering this paper. Experiments are underway on the Alcator C Tokamak with over 1 MW of RF power injected into the plasma at a frequency of 4.6 GHz to study both heating and current drive effects. During these studies, impurity genera-tion from limiter structures has been observed. The RF induced impurity influx is a strongly nonlinear function of net injected power. For Prf < 500 kW, only small effects are seen. As Prf approaches 1 MW, however, sharp increases in impurity influxes and Zeff are observed. Three different lim-iter materials have been used during these studies: molybdenum, graphite, and silicon-carbide coated graphite. In each case, the materials of the limiter structure are seen to dominate the increased impurity influx. In a typical case, with Prf = 1.0 MW e = 1.3 x 1014 cm- 3, and the SiC coated limiters, Zeff is seen to increase from 1.5 before the RF pulse to about 4 during the heating. At the same time, central Te increases from 2000 eV to 3000 eV and central Ti from 1200 eV to 1800 eV. Similar effects are seen in both H2 and D2 working gas discharges. The contribution to impurity genera-tion of nonthermal electrons, which are produced by the RF, is under investi-gation. Changes in edge plasma temperature and density, as well as the possibility that the particle transport is affected by the RF, are also being examined. Results of the experiments with the three different limiter materials are compared, and contributions of impurity radiation to the overall power balance are estimated

Lessons We Learned Designing and Building the Chandra Telescope

2014 marks the crystal (15th) anniversary of the launch of the Chandra Xray Observatory. This paper offers some of the major lessons learned by some of the key members of the Chandra Telescope team. We offer some of the lessons gleaned from our experiences developing, designing, building and testing the telescope and its subsystems, with 15 years of hindsight. Among the topics to be discussed are the early developmental tests, known as VETAI and VETAII, requirements derivation, the impact of late requirements and reflection on the conservatism in the design process

Templating hydrogels

Templating processes for creating polymerized hydrogels are reviewed. The use of contact photonic crystals and of non-contact colloidal crystalline arrays as templates are described and applications to chemical sensing and device fabrication are illustrated. Emulsion templating is illustrated in the formation of microporous membranes, and templating on reverse emulsions and double emulsions is described. Templating in solutions of macromolecules and micelles is discussed and then various applications of hydrogel templating on surfactant liquid crystalline mesophases are illustrated, including a nanoscale analogue of colloidal crystalline array templating, except that the bead array in this case is a cubic array of nonionic micelles. The use of particles as templates in making core-shell and hollow microgel beads is described, as is the use of membrane pores as another illustration of confinement templating

Non-invasive measurement of cholesterol in human blood by impedance technique: an investigation by 2D finite element field modelling

This paper concerns detection of solid particles suspended in conductive media by impedance technique. The technique is based on changes in impedance measured between two electrodes placed across a given volume of conducting medium. It presents a methodology for modelling and investigation of the feasibility of such a technique for particle detection by 2D finite element (FE) field modelling. This is based on modelling and computation of electric field distribution between the above electrodes. It establishes the modelling approach, the complexity involved and justifies the need for modelling in 3D to incorporate some of the effects that cannot be taken into account in 2D models. It reports on the modelling investigation for a specific case of detecting, by impedance technique cholesterol particles suspended in human blood and points to a possible instrument for non-invasive measurement of blood cholesterol level