Improvements of the T-Ω method for 3-D eddy currentanalysis

An improved T-Ω method that can analyze magnetic fields produced not only by eddy currents but also by magnetizing currents is proposed. The method is applied to the analysis of 3-D eddy-current models with holes. The usefulness of the method is investigated by comparing calculated results with measured results and with results obtained by the A-Φ method. The T-Ω method has the advantage that the CPU time can be considerably reduced when most of the analyzed region is current-free and the eddy current flows two-dimensionally. The method is especially effective when the shape of the winding is simple and the distribution of magnetizing current is known beforehand. It is not effective when most of the analyzed region is current-carrying     

Optical bistability and set-reset operation of a Fabry-Perotsemiconductor laser amplifier with two detuned light injections

Optical bistability in a Fabry-Perot semiconductor laser amplifier when two optical inputs detuned from the resonant wavelength of a semiconductor laser amplifier are injected is discussed. A split branch is found in the optical output versus input characteristics in addition to conventional optical bistability behavior. It is shown analytically and experimentally that set and reset can be achieved in the optical output of the semiconductor laser amplifier for each wavelength by applying two detuned optical pulses and using the split branch     

A 64-Mb DRAM with meshed power line

A 64-Mb dynamic RAM (DRAM) has been developed with a meshed power line (MPL) and a quasi-distributed sense-amplifier driver (qDSAD) scheme. It realizes high speed, t_RAS=50 ns (typical) at V_cc=3.3 V, and 16-b input/output (I/O). This MPL+qDSAD scheme can reduce sensing delay caused by the metal layer resistance. Furthermore, to suppress crosstalk noise, a V_SS shield peripheral layout scheme has been introduced, which also widens power line widths. This 64-Mb DRAM was fabricated with 0.4-μm CMOS technology using KrF excimer laser lithography. A newly developed memory cell structure, the tunnel-shaped stacked-capacitor cell (TSSC), was adapted to this 64-Mb DRAM     

A 10 bit 20 MS/s 3 V supply CMOS A/D converter

A 10 bit CMOS A/D converter with 3 V power supply has been developed for being integrated into system VLSI's. In this A/D converter, redundant binary encoders named “twin encoders” enhance tolerance to substrate noise, together with employing differential amplifiers in comparators. The bias circuit using a replica of the amplifier is developed for biasing differential comparators with 3 V power supply. Subranging architecture along with a multilevel tree decoding structure improves dynamic performance of the ADC at 3 V power supply. The A/D converter is fabricated in double-polysilicon, double-metal, 0.8 μm CMOS technology. The experimental results show that the ADC operates at 20 MS/s and the twin encoders suppress the influence of substrate noise effectively. This ADC has a single power supply of 3 V, and dissipates 135 mW at 20 MS/s operation     

Surgical treatment of ventricular tachycardia after surgical repair of tetralogy of Fallot. Relation between intraoperative mapping and histological findings

BACKGROUND: The mechanism of ventricular tachycardia (VT) after correction of tetralogy of Fallot (TF) is poorly understood. The purpose of this study was to examine the histopathology of the arrhythmogenic area detected by intraoperative mapping. METHODS AND RESULTS: The patients were three men who underwent radical surgery for TF at age 3, 3, or 5 years, respectively. VT developed at 8, 9, or 11 years, respectively, after surgery, and shock developed during VT in every case. The ECG revealed monomorphic VT in two cases and polymorphic VT in one case. Induction of VT resulted in a wide left-axis deviation-pattern QRS with cycle lengths varying between 260 and 330 milliseconds. The VT origin was identified at the right ventricular outflow tract (RVOT). A radical operation was performed with the patient under cardiopulmonary bypass. On epicardial mapping, delayed activation of the RVOT was recorded during sinus rhythm, and clockwise circus movement of the macroreentry current during VT on the right ventricular free wall was documented in each case. The VTs were treated successfully by surgical resection and cryoablation of the myocardium. In every patient, histology of the myocardial specimens showed degeneration, adiposis, fibrosis, inflammatory cell infiltration, and scattered myocyte islets. These lesions corresponded anatomically to the area of myocardium in which delayed activation was evident during epicardial mapping. CONCLUSIONS: The results of this study indicate that patients with VT after radical correction of the TF have abnormal histopathological findings at the site of the prior right ventriculotomy scar. These lesions were noted within the region of delayed activation found during epicardial mapping and were found to be a part of the reentrant circuit.     

Disaccharide analysis of human skin glycosaminoglycans in sun-exposed and sun-protected skin of aged people

The negative conduction effect of quinidine on each of the successive phases of the ventricular depolarization was investigated using an original noninvasive method: the spatial velocity electrocardiogram of the QRS complex (SVECG-QRS). We performed a randomized placebo-controlled trial in 10 healthy subjects with a single oral dose of quinidine (330 mg) or placebo. Electrocardiographic acquisition and processing (220 recordings for the complete trial) were performed using the Lyon vectorcardiographic program. For each SVECG-QRS curve, the position of seven specific points from A (onset of QRS) to G (end of QRS) were determined precisely. The six successive time intervals between these points (AB-FG) and five velocity values (B-F) were then calculated. The QRS complex was longer under quinidine than placebo (102.4 +/- 1.6 vs. 100.3 +/- 1.5 ms). The difference was at the periphery of statistical significance (p = 0.05), and this lack of statistical difference may be mainly due to the low serum levels of quinidine obtained at the peak of the concentration (1.46 +/- 0.4 mg/1). All six QRS time intervals were longer under quinidine, but only the BC interval was significantly different (9.3 +/- 1.1 vs. 18.8 +/- 1.1 ms; p < 0.05) suggesting a more pronounced negative conduction effect at the onset of ventricular depolarization. No significant modifications were observed for the velocity values. We conclude that (1) the negative conduction effect of quinidine is heterogeneous, but a further study with a higher dose of quinidine (concentration-dependent effect) is required to confirm this hypothesis and (2) the spatial velocity electrocardiogram of the QRS complex allows a detailed analysis of the ventricular conduction phases. The results of the measurement were found to be reproducible. This noninvasive tool could be used in clinical practice to assess effects of antiarrhythmic drugs on successive ventricular depolarization phases.     

Swelling of hydrophilic polymers. III

The total volume change included gel and surrounded water with the swelling of five types of speherical cross-linked dextran (Sephadex) that are either nonionic (G) or possess one of four different ionic groups in the same molecular skeleton: CM: sodium carboxymethyl, SP: sodium sulphopropyl, DEAE: diethylaminoethyl chloride, and QAE: diethyl-(2-hydroxypropyl) aminoethyl chloride. All have been studied by dilatometry. The total volume decreased with the swelling of all Sephadexes. The maximum changes of total volume with the swelling in water were all negatives of CM, G, SP, (DEAE, QAE), which decrease in that order. These values did not depend on the concentration of sodium chloride and were closely related to the maximum heats of swelling. Total volume changes occurred by the dissociation of the ionic group of dextran derivatives that subtracted the total volume change due to hydration of Sephadex skeleton from the total volume change: ?21.6 ± 3.1 μL mmol^?1 for CM, ?2.8 ± 8.0 μL mmol^?1 for SP, +13.2 ± 4.4 μL mmol^?1 for DEAE, and +15.4 ± 4.6 μL mmol^?1 for QAE. These values are assumed to be reflected in the quantities of ions-water interaction of Sephadexes. © 1994 John Wiley & Sons, Inc.     

Marmaray project: Tunnels and stations in BC contract

Istanbul is one of the most famous historical cities in the world. However, the project alignment selected as the best of a range of alignments cannot avoid passing beneath the historical and cultural heritages of Istanbul as well as under ancient and densely inhabited areas of the city. This paper will explain some of the challenges related to the bored tunnels.

Historical buildings are vulnerable. Yet many existing residential and office buildings are old and constructed on minimal foundations. As a consequence, it is vital that any drawdown of groundwater and any ground settlements have to be minimized.

In addition, the connection between the immersed and bored tunnels will be made directly and totally underground, without the usual intermediate shafts and beneath the deep waters of the Bosphorus Strait. This operation needs the utmost control of the tunnel excavation face to ensure its stability and to minimize water ingress. Based on such considerations, tunnel excavation by tunnel boring machine (TBM) using a slurry shield and having the ability to operate under high pore pressures was recommended as the method of excavation for the main running tunnels.

The paper will explain how the design team from Avrasyaconsult – the Employer’s Representative – arrived at the final minimum, specific and functional requirements of the bored tunneling works which are to be carried out using the ‘FIDIC EPC/Turnkey Project’ conditions.     

Efficient directional cloning of recombinant adenovirus vectors using DNA-protein complex

We describe an efficient cloning system utilizing adenoviral DNA-protein complexes which allows the directional cloning of genes into adenoviral expression vectors in a single step. DNA-protein complexes derived from a recombinant adenovirus (AVC2.null) were isolated by sequential use of CsCl step gradients followed by isopycnic centrifugation in a mixture of CsCl and guanidine HCl. AVC2.null is an adenoviral expression vector containing unique restriction sites between the human CMV-IE promoter and the SV40 intron/polyadenylation site. Transgenes were prepared for cloning into this vector by introduction of compatible restriction sites by PCR. A vector expressing rat granulocyte-macrophage colony-stimulating factor (GM-CSF) was constructed using DNA-protein complex as well as by traditional recombination techniques. The efficacy of our adenoviral cloning system utilizing DNA-protein complex was two logs higher than that seen using homologous recombination. All viruses generated by directional ligation of the insert into the vector DNA-protein complexes contained the desired transgene in the correct orientation. This technique greatly simplifies and accelerates the generation of recombinant adenoviral vectors.