Improvements to an electromagnetic near-field sensor forsimultaneous electric and magnetic field measurement

A sensor for simultaneous electric and magnetic field measurement has been described by M. Kanda (see ibid., vol.EMC-26, no.3, p.102-10, 1984). It relies upon measuring the voltage across precisely matched loads at opposite sides of a loop antenna. A modification to the theory is presented to account for unmatched loading of the loop. Measured results of wave impedance over a 10-400-MHz range demonstrate the accuracy of the modified theory as well as highlighting a novel calibration technique     

Optical and electronic design of a calibrated multichannel electronic interferometer for quantitative flow visualization

Calibrated multichannel electronic interferometry is an electro-optic technique for performing phase shifting of transient phenomena. The design of an improved system for calibrated multichannel electronic interferometry is discussed. This includes a computational method for alignment of three phase-shifted interferograms and determination of the pixel correspondence. During calibration the phase, modulation, and bias of the optical system are determined. These data are stored electronically and used to compensate for errors associated with the path differences in the interferometer, the separation of the phase-shifted interferograms, and the measurement of the phase shift.     

低水平电离辐射致癌效应剂量响应关系的评论性再评估

数十年来，为了辐射防护目的，通常假定辐射诱发癌的总危险是随着剂量呈线性无阈函数增加。现有的资料并不排除有阈存在，然而，剂量响应关系的变化是依赖于所论及的癌症类型，剂量，剂量率，以及辐射的LET，受照个体的年龄、性别和生理状态，以及其他因素，其中包括在低剂量条件下的适应性响应和旁观者效应的潜在影响。所以，根据不断发展的科学知识，下列机构定期对低水平辐射的剂量响应关系进行再评估，这些机构是：美国国家辐射防护与测量委员会(NCRP)，国际放射防护委员会(ICRP)，联合国原子辐射效应科学委员会(UNSCEAR)，美国国家科学院(USNAS)以及其他机构。近来这些评论普遍发现的重要证据认为，作为癌症前体的损伤(例如突变和染色体畸变)，以及某些类型癌症，其发生率在低剂量范围内将随着剂量线性增加。在此基础上，可以得出以下结论：对于低水平辐射的致癌效应，尽管不排除有其他剂量响应关系，但没有什么模式比线性无阈模式更能被接受。     

OPTICAL FLUOR-CROWN GLASSES*

The effect of variations in composition on optical properties was studied. The index of refraction is lowered by the substitution of fluorine and alumina for silica; the reciprocal dispersion, however, is increased by fluorine and lowered by alumina so that fluorine and alumina can be balanced against each other to give almost any desired optical properties within the field investigated, that is, in the range of 1.46 to 1.50 for index of refraction and 63 to 70 for the reciprocal dispersion.     

Estimating teat canal cross-sectional area to determine the effects of teat-end and mouthpiece chamber vacuum on teat congestion

The primary objective of this experiment was to assess the effect of mouthpiece chamber vacuum on teat-end congestion. The secondary objective was to assess the interactive effects of mouthpiece chamber vacuum with teat-end vacuum and pulsation setting on teat-end congestion. The influence of system vacuum, pulsation settings, mouthpiece chamber vacuum, and teat-end vacuum on teat-end congestion were tested in a 2 × 2 factorial design. The low-risk conditions for teat-end congestion (TEL) were 40 kPa system vacuum (Vs) and 400-ms pulsation b-phase. The high-risk conditions for teat-end congestion (TEH) were 49 kPa Vs and 700-ms b-phase. The low-risk condition for teat-barrel congestion (TBL) was created by venting the liner mouthpiece chamber to atmosphere. In the high-risk condition for teat-barrel congestion (TBH) the mouthpiece chamber was connected to short milk tube vacuum. Eight cows (32 quarters) were used in the experiment conducted during 0400 h milkings. All cows received all treatments over the entire experimental period. Teatcups were removed after 150 s for all treatments to standardize the exposure period. Calculated teat canal cross-sectional area (CA) was used to assess congestion of teat tissue. The main effect of the teat-end treatment was a reduction in CA of 9.9% between TEL and TEH conditions, for both levels of teat-barrel congestion risk. The main effect of the teat-barrel treatment was remarkably similar, with a decrease of 9.7% in CA between TBL and TBH conditions for both levels of teat-end congestion risk. No interaction between treatments was detected, hence the main effects are additive. The most aggressive of the 4 treatment combinations (TEH plus TBH) had a CA estimate 20% smaller than for the most gentle treatment combination (TEL plus TBL). The conditions designed to impair circulation in the teat barrel also had a deleterious effect on circulation at the teat end. This experiment highlights the importance of elevated mouthpiece chamber vacuum on teat-end congestion and resultant decreases in CA.     

Assessing filter robustness at drinking water treatment plants

This investigation explores the use of five‐parameter logistic curve fitting in quantifying turbidity robustness and risk scoring in clarification and filtrations stages of several surface water treatment works in the Anglian Water region of the United Kingdom. The approach taken reviews different scoring systems and addresses issues of weighting, averages and variability in robustness performance using turbidity robustness indices (TRIs). It also proposes an area‐based risk scoring profile to assess performance [relative area profile for T₉₀ (RAP₉₀)]. The metrics produced are considered to be a logical and rational way to help prioritise where resources for water treatment operation should be deployed.     

The Applications of Satellite Based Remote Sensing Techniques in the Hydrological Assessment of Mine Water Supply and Management Systems

Mineral resources are often discovered in remote or mountainous areas where long-term hydrological records are either absent or limited. Satellite-based remote sensing techniques can provide indirect observations of phenomena of interest, such as rainfall depth, snow cover, evapotranspiration, and changes in groundwater levels. Quality and applicability of the data are limited by the spatial, spectral, and temporal resolution of images. Other limitations may arise from the algorithms used to interpret the data. Examples are provided on how new remote sensing has been used at sites owned by Barrick Gold Corporation. It should be stressed that, for the foreseeable future, remote sensing data can supplement, not replace, more traditional sources of information.     

Similarity between class A and class B G-protein-coupled receptors exemplified through calcitonin gene-related peptide receptor modelling and mutagenesis studies

Modelling class B G-protein-coupled receptors (GPCRs) using class A GPCR structural templates is difficult due to lack of homology. The plant GPCR, GCR1, has homology to both class A and class B GPCRs. We have used this to generate a class A–class B alignment, and by incorporating maximum lagged correlation of entropy and hydrophobicity into a consensus score, we have been able to align receptor transmembrane regions. We have applied this analysis to generate active and inactive homology models of the class B calcitonin gene-related peptide (CGRP) receptor, and have supported it with site-directed mutagenesis data using 122 CGRP receptor residues and 144 published mutagenesis results on other class B GPCRs. The variation of sequence variability with structure, the analysis of polarity violations, the alignment of group-conserved residues and the mutagenesis results at 27 key positions were particularly informative in distinguishing between the proposed and plausible alternative alignments. Furthermore, we have been able to associate the key molecular features of the class B GPCR signalling machinery with their class A counterparts for the first time. These include the [K/R]KLH motif in intracellular loop 1, [I/L]xxxL and KxxK at the intracellular end of TM5 and TM6, the NPXXY/VAVLY motif on TM7 and small group-conserved residues in TM1, TM2, TM3 and TM7. The equivalent of the class A DRY motif is proposed to involve Arg^2.39, His^2.43 and Glu^3.46, which makes a polar lock with T^6.37. These alignments and models provide useful tools for understanding class B GPCR function.     

The influence of the bolus injection rate of propofol on its cardiovascular effects and peak blood concentrations in sheep

The influence of the bolus injection rate of propofol on its cardiovascular effects has not been extensively studied. We therefore examined the influence of the injection rate of i.v. bolus doses of propofol on its acute cardiovascular effects and peak blood concentrations in seven chronically instrumented sheep. Each received i.v. propofol (200 mg) over 2 min (slow injection) and 0.5 min (rapid injection) on separate occasions in random order. The rapid injection was associated with more profound decreases in mean arterial blood pressure than slow injection (35.7% vs 23.7% maximal reductions from baseline, respectively; P = 0.02). There were no significant differences between the injection rates for peak reductions in myocardial contractility, increases in heart rate, or degree of respiratory depression. Concurrently, the rapid injections were associated with significantly higher arterial (26.9 vs 11.9 mg/L) propofol concentrations in a manner consistent with indicator dilution principles. There were no differences in the peak coronary sinus concentrations between the injection rates. We conclude that the rapid injection of propofol in the context of the induction of anesthesia produced significantly higher peak arterial propofol concentrations and suggest that it is these higher concentrations that produced relatively greater reductions in arterial blood pressure from rapid injections. Implications: Propofol is injected into a vein to initiate anesthesia. It can cause a rapid decrease in blood pressure, which may be dangerous to the patient. We examined the effect of rapid and slow injection rates of propofol in sheep and found that rapid injection caused a greater decrease in blood pressure. This was because rapid injection caused higher concentrations of propofol in the blood immediately after the injection. We believe that if the same processes occur in humans, there may be little advantage in injecting propofol rapidly.