On the Rate of Attenuation of Signals Conducted along Overhead Wires

A simple expression is presented for the attenuation of signals along an overhead conductor with a ground return. The formula appears to be sufficiently accurate to provide useful estimates of the line attenuation up to frequencies for which the conductor height is of the order of a quarter wavelength.     

Manipulation of the phosphatidylethanolamine pool in the human red cell membrane affects its Mg2+-ATPase activity

The qualitative fungal composition of Turin's atmospheric environment was surveyed, carrying out a twelve-month study and collecting with a single stage volumetric sieve sampler on Dermasel agar supplemented with 0.4 g l-1 cycloheximide and 0.05 g l-1 chloramphenicol. We isolated 165 species and 2 varieties of mesophilic fungi from 58 genera and 26 thermotolerant species from 12 genera. Penicillium, Aspergillus, Acremonium, Chrysosporium, Scopulariopsis, Malbranchea, Paecilomyces, Phialophora and Cladosporium were in sequence the genera most rich in mesophilic species; Aspergillus, Penicillium, Chrysosporium and Scopulariopsis the most rich in thermotolerant species. Many of the species isolated are rarely or never recorded in the atmospheric environment. Cycloheximide can thus be said to select among airborne fungi, giving a characteristic picture.     

Immobilization of active hydrogenases by encapsulation in polymeric porous gels

Hydrogenases encapsulated in porous polymeric silica gels retain significant levels of hydrogen production activity when compared to hydrogenases in solution using reduced methyl viologen as an electron donor. Encapsulated hydrogenases remain active after storage at room temperature for longer than four weeks and are less sensitive to proteolytic digestion. Nanoscopic confinement of active hydrogenases in solids paves the way for their potential use in hydrogen producing catalytic materials applications.     

Optimal Interconnect ATPG Under a Ground-Bounce Constraint

In order to prevent ground bounce, Automatic Test Pattern Generation (ATPG) algorithms for wire interconnects have recently been extended with the capability to restrict the maximal Hamming distance between any two consecutive test patterns to a user-defined integer, referred to as the Simultaneously-Switching Outputs Limit (SSOL). The conventional approach to meet this SSOL constraint is to insert additional test patterns between consecutive test patterns if their Hamming distance is too large; this approach often leads to substantially more test patterns than strictly necessary. This paper presents an algorithm that generates, for a user-defined number of interconnect wires, a minimal set of test patterns that respects a user-defined SSOL constraint. Experimental results show that, in comparison to the conventional approach, our algorithm leads to a significant reduction of up to 60% in the test pattern count and corresponding test application time.This revised version was published online in March 2005 with corrections to the cover date.     

Heat conduction in spin-polarized gaseous3He at low temperature

A dilute gas of³He exhibits an interesting dependence of its transport properties on the nuclear spin polarization, resulting from the indistinguishability of the fermions during binary collisions. This article reports experimental results on the heat conductivity of gaseous³He in the 1.2–4.2 K range, the gas being polarized by laser optical pumping. The heat conductivity is found to change with the nuclear polarization. Compared to preliminary data already reported, the present work has been carried out with more care to control all the heat fluxes reaching the measurement cell, and the temperature range has been extended. The results are compared to recently improved calculations. The temperature dependence of the effect is now found to be in satisfactory agreement with theory.     

Evaluating parallel architectures for two real-time applicationswith 100 kHz repetition rate [hadron collider data]

In the context of research and development activities for future hadron colliders, competitive implementations of real-time algorithms for feature extraction have been made on various forms of commercial pipelined and parallel architectures. The algorithms used for benchmarking serve for decision making and are of relative complexity; they are required to run with a repetition rate of 100 kHz on data sets of kilobyte size. Results are reported and discussed in detail. Among the commercially available architectures, pipelined image processing systems can compete with custom-designed architectures. General-purpose processors with systolic mesh connectivity can also be used. Massively parallel systems of the SIMD type (many processors executing the same program on different data) are less suitable in the presently marketed form     

Implementation of radiation boundary conditions in the finiteelement analysis of electromagnetic wave propagation

Radiation boundary conditions are formulated which permit the simulation of two-dimensional electromagnetic wave phenomena with the finite-element method using conventional elements over a bounded domain. Implementation of such boundary conditions preserves the symmetry of the global stiffness matrix with all the advantages that this implies, including economy of storage and solution. A number of wire-antenna systems have been modeled with this technique in a finite-element computer program called FEAST. The results demonstrate good agreement with published reference data     

Simple cell for the measurement of the radio frequency electrical properties of earth materials

The design of a simple cell for determining the radio frequency electrical properties of earth materials is described. Basically, the cell consists of a coaxial sample holder fitted with electric and magnetic field probes. When excited as a section of transmission line the induced probe voltages are related in a straightforward manner to the electrical properties of the sample. The device is intended for use with a vector voltmeter which permits the direct and simultaneous measurement of the relative amplitudes and phases of these probe voltages. The cell permits the accurate and rapid determination of the conductivity and dielectric constant of earth materials over the frequency range 1 MHz-1 GHz, without the tedious and time consuming procedures associated with the bridge and slotted line techniques commonly used in this frequency range.     

Prediction of the measured temperature after the last finishing stand using artificial neural networks

In this report the development of an artificial neural network, capable of predicting the temperature after the last finishing stand of a hot strip mill for a certain class of steels, is described. Three neural networks with different numbers of hidden nodes (3, 5 and 7) were trained. The relative standard deviation in finish temperature as predicted by the best performing neural network model (7 hidden nodes) was just over 25% smaller than that of the linear Hoogovens model. This improved accuracy can be explained by the incorrect assumption in the Hoogovens model of linear dependence of the finishing temperature on some input parameters. With the trained neural network, the influence of the various input parameters on the finishing temperature could be examined. The dependencies predicted by the neural network can be approximated by a linear fit and are a factor 2 lower for all input parameters. It is conceivable that operation of the mill using an artificial neural network for the prediction of the finishing temperature would have resulted in smaller operational fluctuations.     

Urinary thiodiacetic acid. A selective biomarker for the cytochrome P450-catalyzed oxidation of 1,2-dibromoethane in the rat

1,2-Dibromoethane (1,2-DBE) is a carcinogenic compound that is metabolized both by cytochrome P450 (P450) and glutathione S-transferase (GST) enzymes, and that has been used by us as a model compound to study interindividual variability in biotransformation reactions. In this study, the excretion of thiodiacetic acid (TDA) and S-(2-hydroxyethyl)-N-acetyl-l-cysteine (2-HEMA) were measured in the urine of rats dosed with 1,2-DBE, and experiments were performed to investigate to what extent P450 and GST enzymes contribute to the formation of TDA. To this end, CYP2E1, the main P450 isoenzyme catalyzing the oxidation of 1,2-DBE, was inhibited using disulfiram and diallylsulfide. Significant inhibition of CYP2E1, as confirmed by inhibition of the hydroxylation of chlorzoxazone, as well as inhibition of the formation of TDA from 1,2-DBE, was observed upon pretreatment of rats with these inhibitors, indicating that the P450-catalyzed oxidation of 1,2-DBE plays the major role in the TDA formation. No significant excretion of TDA was observed after administration of intermediate products of the GST pathway [i.e. S-(2-hydroxyethyl)glutathione and 2-HEMA], indicating that the GST-catalyzed metabolism of 1,2-DBE does not contribute to a significant extent to the formation of TDA. The results of this study show that TDA is specifically formed by P450 metabolites of 1,2-DBE, whereas the conjugation of 1,2-DBE to glutathione by GST enzymes does not contribute to the formation of TDA. TDA, excreted in urine, may thus be used as a biomarker of exposure to 1,2-DBE selectively reflecting the P450-catalyzed oxidation. In addition to 2-HEMA and S-[2-(N7-guanyl)ethyl]-N-acetyl-l-cysteine, TDA may be a valuable tool for biomonitoring and mechanistic studies into the metabolism and toxicity of 1,2-DBE.