Bajracharya, K & Vigneswaran, S 1990, 'Adsorption of cadmium and zinc in saturated soil columns: Mathematical models and experiments', Environmental Technology, vol. 11, no. 1, pp. 9-24.
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It vas found from experiments that adsorption of Cd and Zn in the dynamic system was higher than that in the static systea. Equilibrium Adsorption Model (EAM) and Two Site Adsorption Model (TSAM) have been validated with the observed concentration history curves of Cd and Zn. In most of the cases the EAM model with dynamic isotherm constants fitted the observed concentration history curves satisfactorily. In those where EAM did not fit well (using Dynamic isotherm constants), the TSAM predicted more accurately. The general conclusion is that for highly adsorbing solutes, EAM is a simple and quite satisfactory model for the prediction of concentration profiles both temporally and spatially. © 1990 Publications Division Selper Ltd.
Bajracharya, K & Vigneswaran, S 1990, 'Competitive adsorption of solutes in saturated soil columns: Mathematical model and experiments', Environmental Technology, vol. 11, no. 1, pp. 25-32.
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Results of competitive adsorption column experiments of Cadmiua (Cd) and Zinc (Zn) are discussed. A mathematical model termed as Competitive Dynamic Adsorption Model (CDAM) to predict the solute concentration in the multi‐solute system is presented. The CDAM is verified using concentration history curves of Cd and Zn obtained from saturated column experiments. © 1990 Taylor and Francis Group, LLC.
Ball, JE 1990, 'Unsteady flow model for urban drainage systems', Transactions of the Institution of Engineers, Australia. Civil engineering, vol. CE32, no. 2, pp. 66-74.
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A numerical model which uses the algorithm presented by Ball (1) and the results of an investigation into the relative importance of the terms in the full dynamic wave equation of motion presented by Ball (2) for the prediction of unsteady flow propagation within an urban drainage system is presented. Results obtained from the use of the proposed model and also from use of the EXTRAN block of SWMM (3) on sample hypothetical networks are presented. These results indicate a more stable and physically reasonable hydrograph is predicted by the proposed model than that obtained from EXTRAN. Finally, an application of the proposed model to the analysis of an existing drainage network is presented.
Bird, TS 1990, 'Analysis of mutual coupling in finite arrays of different-sized rectangular waveguides', IEEE Transactions on Antennas and Propagation, vol. 38, no. 2, pp. 166-172.
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Bird, TS 1990, 'Behaviour of multiple elliptical waveguides opening into a ground plane', IEE Proceedings H Microwaves, Antennas and Propagation, vol. 137, no. 2, pp. 121-121.
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Bird, TS & Hay, SG 1990, 'Mismatch in dielectric-loaded rectangular waveguide antenna', Electronics Letters, vol. 26, no. 1, pp. 59-61.
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Bird, TS & Sprey, MA 1990, 'Scan limitations of shaped dual-offset reflector antennas for multiple satellite access', Electronics Letters, vol. 26, no. 4, pp. 228-228.
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CAO, HT, BAWEJA, D & ROPER, H 1990, 'CORROSION CHARACTERISTICS OF STEEL IN SOLUTIONS DERIVED FROM CEMENTS AND BLENDED CEMENTS', CEMENT AND CONCRETE RESEARCH, vol. 20, no. 3, pp. 325-334.
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Potentiodynamic Anodic Polarization techniques were used to investigate the corrosion characteristics of steel in solutions. The solutions were prepared by mixing different cements at a water-binder ratio of 2.0 and extraction after 3 and 7 days. Cements used in this investigation included an OPC with low C3A content, an OPC with high C3A content, a Slag Cement and a Fly Ash Cement. Results indicate that in the absence of chloride ions, the corrosion characteristics of steel in these solutions are very similar to those of steel in lime-saturated water. Despite differences in the rest potentials found in solutions made with the range of binder materials, steel passivation could be observed in all solutions. Passivation imparted to the steel by binder solutions was found to vary in the presence of increasing levels of chloride. A threshold chloride ion concentration for depassivation was established for each binder solution tested. Solutions made from the High C3A Cement and the Slag Cement displayed the best steel passivation characteristics, white the Low C3A Cement solution rated worst. © 1990.
Emanuel, PD, Peiper, SC, Chen, Z, Sheng, DC & Zuckerman, KS 1990, 'Specific inhibition of interleukin 3 bioactivity by a monoclonal antibody reactive with hematopoietic progenitor cells.', Proceedings of the National Academy of Sciences, vol. 87, no. 12, pp. 4449-4452.
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HIM1, originally designated HI98, a murine monoclonal IgM antibody raised against human mononuclear cells, has been reported at the Fourth International Leukocyte Typing Workshop (called antibody M0141) to be the only one of 157 antibodies tested that inhibited binding of interleukin 3 (IL-3) to KG-1 human acute myelogenous leukemia cells and normal human monocytes. We have carried out detailed studies of the selective effect of HIM1 on IL-3-mediated stimulation of hematopoietic progenitors. Preincubation of normal human bone marrow mononuclear cells, depleted of adherent cells and T cells, with HIM1 antibody resulted in a dose-dependent inhibition of IL-3-mediated stimulation of both erythroid burst-forming units (maximum inhibition 55%) and granulocyte/macrophage colony-forming units (maximum inhibition 49%). HIM1 antibody had no effect on growth of erythroid colony-forming units in culture. In addition, preincubation of the cells with HIM1 antibody had no deleterious effect on granulocyte/macrophage colony-stimulating factor-induced growth of either erythroid bursts or granulocyte/macrophage colonies. To be certain that the HIM1 antibody did not react directly with IL-3 itself, we attempted to use immunodepletion to remove IL-3 that had been added to our culture medium. Although we were able to remove IL-3 bioactivity by immunodepletion with anti-IL-3 antibody bound to Sepharose beads, beads with attached HIM1 did not remove IL-3 activity from the medium. Polymorphonuclear neutrophils bind high levels of HIM1, although they have very few or no detectable IL-3 receptors. Therefore, this antibody appears to recognize a cell surface antigen that is critical for optimal IL-3 binding and bioactivity but is not the actual IL-3 receptor.
Esselle, KP & Stuchly, SS 1990, 'Pulse-receiving characteristics of resistively loaded dipole antennas', IEEE Transactions on Antennas and Propagation, vol. 38, no. 10, pp. 1677-1683.
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Esselle, KP & Stuchly, SS 1990, 'Resistively loaded loop as a pulse-receiving antenna', IEEE Transactions on Antennas and Propagation, vol. 38, no. 7, pp. 1123-1126.
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EZE, OC & LOGANATHAN, P 1990, 'EFFECTS OF PH ON PHOSPHATE SORPTION OF SOME PALE-ADULTS OF SOUTHERN NIGERIA', SOIL SCIENCE, vol. 150, no. 3, pp. 613-621.
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The effect of pH on phosphate sorption by soil samples from two coarse-textured pedons of typic Paleudults in the perhumid tropical zone of Nigeria was studied by equilibrating air-dried soil samples adjusted to pH 3.5–6.5 for 48 h with 10 ppm P and 60 ppm P solutions at two concentrations of CaCl2 and NaCl. Phosphate sorption was generally unaffected by pH at low P additions at the two concentrations of the salts, whereas at high P additions sorption generally decreased with increase in soil pH, except in the presence of the high concentration of CaCl2 (10−2 M) where sorption decreased up to pH 5.0–5.5; beyond this pH range it increased. In both 10−2 M CaCl2 and 3 × 10−2 M NaCl systems, phosphate sorption decreased by 19–89% as a result of dithionite-citrate-bicarbonate (DCB) treatment. The effects of pH on phosphate sorption by treated samples were similar to those by untreated samples. Phosphate sorption increased with increase in depth, probably due to the increase in oxalate and dithionite-citrate-bi-carbonate extractable Fe and Al and the decrease in organic matter content down the pedons. Phosphate sorption by samples from the B horizon increased with increase in period of incubation with lime, whereas in the samples of Ap horizons no consistent trend was obtained. © 1990 Williams and Wilkins.
Gardner, JF, Srinivasan, K & Waldron, KJ 1990, 'A Solution for the Force Distribution Problem in Redundantly Actuated Closed Kinematic Chains', Journal of Dynamic Systems, Measurement, and Control, vol. 112, no. 3, pp. 523-526.
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Proper control of robotic systems which incorporate closed kinematic chains is important in many applications. Among these are the multi-robot work cell and legged vehicles. In these no unique solution exists for the force distribution corresponding to a specified trajectory. A framework within which additional constraint equations may be written is presented here, and the force distribution solved in closed form for a walking machine application. These constraints are related to system performance goals of interest, such as improved traction and/or load sharing among the legs. The proposed technique is shown to be computationally simpler than other alternative solutions to the same problem.
Gardner, JF, Srinivasan, K & Waldron, KJ 1990, 'Closed loop trajectory control of walking machines', Robotica, vol. 8, no. 1, pp. 13-22.
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SUMMARYThe global trajectory control of walking machines is addressed here with particular attention paid to the consequences of actuator redundancy for control and to the inclusion of actuator dynamics in trajectory controller design. Redundancy of actuation, typical of walking machines, results in the trajectory control problem being formulated perforce in a global coordinate frame, instead of the joint space, as in nonredundant manipulators. This lack of one-to-one correspondence between the degrees of freedom of motion in the global coordinate frame and the actuators results in coupling between the different trajectory control loops. A mechanism for reducing this coupling effect is proposed here, along with a procedure to take into account approximately the effect of actuator dynamics in designing the trajectory controllers. The proposed methods are evaluated by simulation for an example problem in legged locomotion and are shown to be effective.
Hiroshige, M, Miyanaga, Y & Tochinai, K 1990, 'An Adaptive Signal Processing System for Voiced Speech with Automatic Spectrum Selector', Systems and Computers in Japan, vol. 21, no. 4, pp. 85-96.
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AbstractIn this paper, adaptive spectrum analysis algorithms for voiced speech are discussed. A new adaptive signal processing system which uses a modified MIS algorithm and has a spectrum selector using a neural network is proposed. Based on the properties of voiced speech, we first test an identification algorithm which estimates AR parameters from the first moment of the observed signal and investigate its sensitivity to noise. In order to compare the modified MIS for voiced speech analysis with the above first moment analysis, the frequency domain properties of weighting factor A which is used in the modified MIS are presented.This paper shows that we should select only the accurate spectra from among the results given by the modified MIS. The selection of spectra is automatically performed using a neural network. Using above methods, we construct a new analysis system for voiced speech. Experiments on real speech show that the proposed system is effective for speech analysis.
Huang, MZ & Waldron, KJ 1990, 'Relationship between payload and speed in legged locomotion systems', IEEE Transactions on Robotics and Automation, vol. 6, no. 5, pp. 570-577.
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Huynh, BP, Coulman, CE & Turner, TR 1990, 'Some turbulence characteristics of convectively mixed layers over rugged and homogeneous terrain', Boundary-Layer Meteorology, vol. 51, no. 3, pp. 229-254.
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Indraratna, B 1990, 'Development and applications of a synthetic material to simulate soft sedimentary rocks', Géotechnique, vol. 40, no. 2, pp. 189-200.
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Due to the fact that a model material can be made homogeneous, the influence of different variables on behavioural mechanisms can be investigated independently. Consequently, large experimental scatter attributed to inherent variables (generally unknown) of a natural material can be avoided. This Paper presents the development of an artificial material which can effectively simulate the behaviour of an array of weak, sedimentary rocks. This synthetic soft rock was constituted with gypsum cement, fine sand and water, and characterized with homogeneous and isotropic properties with insignificant variability from one batch to another. It can be easily manufactured in the laboratory and can be cast either in large or small volumes to occupy any predetermined shape of given physical dimensions. An experimental application to study the behaviour of reinforced composites (simulated bolted rock) is also described in this Paper. Puis qu'une matière-modèle peut être rendue homogène, il est possible d'étudier de façon indépendante l'influence exercée par de diverses variables sur les mécanismes de comportement. On peut par conséquent éviter la dispersion considérable expérimentale attribuée aux variabilités inhérentes, généralement inconnues, à une matière naturelle. L'article décrit le développement d'une matière artificielle qui peut simuler effectivement le comportement d'un groupe de roches tendres Sédimentaires. Cette rocbe tendre synthétique comprenait du ciment de gypse, du sable fin et de l'eau et possédait des propriétés homogènes et isotropes qui ne variaient que très peu d'un lot à l'autre. Cette matière peut se produire très facilement dans le laboratoire et être coulée dans de petits ou grands volumes pour prendre n'importe quelle forme prédeterminée de dimensions données. L'article présente aussi une application expérimentale pour étudier le comportement des matières composites renforcées (simulation de rocbes boulonnées).
Indraratna, B & Kaiser, PK 1990, 'Analytical model for the design of grouted rock bolts', International Journal for Numerical and Analytical Methods in Geomechanics, vol. 14, no. 4, pp. 227-251.
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AbstractAn analytical model which represents the behaviour of a reinforced rock mass near a circular underground opening in a homogeneous, uniform stress field has been developed. The theory adopts the concepts of elastoplasticity and considers a proper interaction mechanism between the ground and the grouted (or friction) bolts. It highlights the influence of the bolt pattern on the extent of the yield zone and tunnel deformation. A dimensionless parameter is introduced as a design tool which relates the tunnel convergence to the bolt spacing for a given bolt length. This publication contains the derivation of the analytical model and an illustration of the effect of bolts on the stress and displacement field near an opening. Its application to tunnel design is discussed briefly. The verification of the theory by laboratory simulation and field measurements will be presented, in detail, in a future publication.
Indraratna, B & Kaiser, PK 1990, 'Design for grouted rock bolts based on the convergence control method', International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, vol. 27, no. 4, pp. 269-281.
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A design approach for the application of fully grouted bolts as a passive support system in underground openings is introduced in this paper. The analytical solution was developed based on elasto-plastic concepts and was verified by laboratory simulations with physical models. The application of the theory to one case history and a comparison with an empirical design method (RMR) are presented. Computational examples and general design guides are provided to facilitate the use of the proposed method in practice. © 1990.
Jing Song Chang & Vigneswaran, S 1990, 'Ionic strength in deep bed filtration', Water Research, vol. 24, no. 11, pp. 1425-1430.
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The removal efficiency of particles in deep bed filtration depends on both transport and attachment mechanisms of particles. The particle attachment mechanisms depend mainly on chemical characteristics of aqueous phase, suspended particles and filter media. In this study, two different suspensions were used to study the effect of ionic strength on the particle removal efficiency. The ionic strength of suspension was varied by adding a known amount of sodium chloride. The removal efficiencies were related to ionic strength and zeta potential. The clean filter bed efficiency and removal efficiency during the ripening period for various strengths were quantitatively related to the two model coefficients appearing in the O'Melia-Ali model. These model coefficients represent the filter medium-particle and particle-particle attachments. This type of quantification of the effect of ionic strength in terms of filter efficiency is very useful in filter design and operation control.
Kumar, V & Waldron, KJ 1990, 'Force Distribution in Walking Vehicles', Journal of Mechanical Design, vol. 112, no. 1, pp. 90-99.
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This paper addresses the problem of the appropriate distribution of forces between the legs of a legged locomotion system for walking on uneven terrain. The legs of the walking machine and the terrain form closed kinematic chains. The system is statically indeterminate and an optimal solution is desired for force control of the legs. In addition, as unisense force limitations are imposed on the wrenches acting at the feet, it is important to be able to determine for any given configuration whether or not a set of valid contact forces can be found which will ensure the stability of the vehicle. Fast and efficient algorithms to solve these problems have been developed. The trade-off between computational simplicity and optimality makes it necessary to resort to suboptimal algorithms. In particular, schemes based on the Moore-Penrose Generalized Inverse, or the pseudo inverse, and linear programming were investigated. An active compliance control scheme with varying leg compliances is shown to be a suitable paradigm for control. A variation of the linear programming technique, that is well-suited to the problem of predicting instability in the vehicle, is also presented.
Mahinthakumar, G & Vigneswaran, S 1990, 'Solute transport through saturated soils: a study of the physical non-equilibrium model', Water, Air, and Soil Pollution, vol. 51, no. 1-2, pp. 161-180.
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Miyanaga, Y, Ohtsuki, N & Tochinai, K 1990, 'Adaptive ARMA lattice modeling for speech processing', Journal of the Acoustical Society of Japan (E), vol. 11, no. 3, pp. 173-182.
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Miyanaga, Y, Tochinai, K, Nagai, N & Nagata, K 1990, 'Adaptive identification of a modified ARMA lattice model', IEEE Transactions on Circuits and Systems, vol. 37, no. 9, pp. 1140-1144.
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NANUA, P, WALDRON, KJ & MURTHY, V 1990, 'DIRECT KINEMATIC SOLUTION OF A STEWART PLATFORM', IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION, vol. 6, no. 4, pp. 438-444.
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Pugh, DR, Ribble, EA, Vohnout, VJ, Bihari, TE, Walliser, TM, Patterson, MR & Waldron, KJ 1990, 'Technical Description of the Adaptive Suspension Vehicle', The International Journal of Robotics Research, vol. 9, no. 2, pp. 24-42.
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This paper contains descriptions and specifications of the major mechanical systems of the Adaptive Suspension Vehi cle. It also contains an overview of the computer software and hardware architectures. Experimental response curves for the principal servo systems are presented.
REUBEN, AJ & SHANNON, AG 1990, 'Some Problems in the Mathematical Modelling of Erythrocyte Sedimentation', Mathematical Medicine and Biology, vol. 7, no. 3, pp. 145-156.
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The rate at which red blood cells fall in vitro is used as a common clinical test, amongst others, for a number of pathological conditions. The use of this test is cast into doubt when one finds flaws in the underlying models and confusion over fundamental issues such as the aggregation of the red blood cells. Both of these deficiencies are evident in an otherwise innovative publication by Huang et al. (1971). In examining the mathematics of this relatively unknown study, it is found that the Huang model resembles certain moving-boundary problems. The consequences of this observation are discussed. © 1990 Oxford University Press.
REUBEN, AJ & SHANNON, AG 1990, 'SOME PROBLEMS IN THE MATHEMATICAL-MODELING OF ERYTHROCYTE SEDIMENTATION', IMA JOURNAL OF MATHEMATICS APPLIED IN MEDICINE AND BIOLOGY, vol. 7, no. 3, pp. 145-156.
SHANNON, AG, COLAGIURI, S & MILLER, JJ 1990, 'COMPARISON OF GLYCEMIC CONTROL WITH HUMAN AND PORCINE INSULINS - A META-ANALYSIS', MEDICAL JOURNAL OF AUSTRALIA, vol. 152, no. 1, pp. 49-49.
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Stewart, MG 1990, 'Human error in steel beam design', Civil Engineering Systems, vol. 7, no. 2, pp. 94-101.
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Veitch, D & Glendinning, P 1990, 'Explicit renormalisation in piecewise linear bimodal maps', Physica D: Nonlinear Phenomena, vol. 44, no. 1-2, pp. 149-167.
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Vigneswaran, S, Jing Song Chang & Janssens, JG 1990, 'Experimental investigation of size distribution of suspended particles in granular bed filtration', Water Research, vol. 24, no. 7, pp. 927-930.
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Laboratory-scale experimental studies were conducted to show the effect of size distribution of particles in granular bed filtration. The results showed that the investigation of granular bed filtration based merely on the mean size is inadequate as particles of different size have different removal efficiencies. This study also showed that there is an improvement in fine particles removal efficiency when they are present with particles in polydispersed suspension. © 1990.
Voinov, AA & Akhremenkov, AA 1990, 'Simulation modeling system for aquatic bodies', Ecological Modelling, vol. 52, no. 3-4, pp. 181-205.
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Watterson, PA 1990, 'Magnetic field penetration into thin discs', Archiv für Elektrotechnik, vol. 73, no. 5, pp. 353-363.
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Zhou, JL & Banks, CJ 1990, 'Fractionation of humic acid components by ion exchange chromatography', Environmental Technology, vol. 11, no. 12, pp. 1147-1152.
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Boyce, RR, Bone, DJ, Houwing, AFP & Finlayson, KD 1970, 'Measurement of heavy particle and electron densities in supersonic nonequilibrium corner expansions of ionized argon and neon', AIP Conference Proceedings, American Institute of Physics, pp. 414-419.
Esselle, KP & Stuchly, SS 1970, 'A new broadband antenna for transient electromagnetic field measurements', International Symposium on Antennas and Propagation Society, Merging Technologies for the 90's, International Symposium on Antennas and Propagation Society, Merging Technologies for the 90's, IEEE, pp. 1584-1587.
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A novel broadband antenna based on the resistively loaded V dipole is presented. For a given sensitivity and termination impedance, this antenna provides a broader bandwidth compared with the Wu-King dipole. A 30-cm monopole configuration with a 500-Ω commercially available probe as the termination is estimated to have a bandwidth of 20-10 GHz and sensitivity of 10.5 × 10-3 V/(Vm-1).This antenna can be used to measure electromagnetic pulses and transients with subnanosecond rise times. It can also be used as the receiving antenna in time-domain scattering edges.
Esselle, KP & Stuchly, SS 1970, 'An electrically-large antenna for transient electromagnetic field measurements', Conference on Precision Electromagnetic Measurements, Conference on Precision Electromagnetic Measurements, IEEE, pp. 192-193.
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An electrically large antenna for the measurement of broadband electromagnetic pulses and transients is described. Numerical results obtained from theoretical analyses in both the time and frequency domains are presented. They indicate that the antenna can be used to measure electromagnetic pulses and transients with subnanosecond rise times (bandwidth up to 10 GHz) and has much better frequency- and time-domain receiving characteristics than an equally sensitive Wu-King monopole.
Horwitz, R, Courtenay, TD & Braun, RM 1970, 'The Development Of Novel Modem Structures To Enhance The Throughput Of Dial Up Telephone Lines', IEEE South African Symposium on Communications and Signal Processing, IEEE South African Symposium on Communications and Signal Processing, IEEE, pp. 95-99.
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© 1990 IEEE. A popular approach to designing high-speed modems for use on voice-grade telephone channels is to use a high order modulation scheme combined with a digital architecture. This paper describes the development of a modem structure which uses the DSP56001 signal processor to implement 49 quadrature partial response signalling (49 QPRS). The choice of 49 QPRS is justified by its high spectral efficiency and reasonable error rate performance. This system is being developed for two applications, which are described in the paper.
Huang, X & Chen, H 1970, 'Born migration and its fast implementation in the wavenumber‐time domain', SEG Technical Program Expanded Abstracts 1990, SEG Technical Program Expanded Abstracts 1990, Society of Exploration Geophysicists, pp. 1136-1139.
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© 1990 Society of Exploration Geophysicists. All rights reserved. A new method for wave equation migration is presented in this paper. This migration method, named Born Migration, is formulated by solving the boundary-value problem of the wave equation in an integral closed-form and applying the Born approximation for the Green's function in the inhomogeneous media. The major features of Born migration are: 1. it has no limitation in dip angle; 2. it can accommodate gentle vertical and lateral velocity variations; and 3. it can be implemented by using fast Fourier transformation. It is believed that this technique is especially suitable for migration in 3D seismic survey application.
Lister, R 1970, 'Toward context dependent classification of infra-red spectra by energy minimization', 1990 IJCNN International Joint Conference on Neural Networks, 1990 IJCNN International Joint Conference on Neural Networks, IEEE, pp. 1-6.
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An architecture for reimplementing an existing expert system is described. The original application, called GOLD, identifies minerals in rock samples, using infrared spectral data, and was developed in the Prospector formalism. The development of GOLD's knowledge base became cumbersome when it was necessary to describe how the spectrum of one mineral is affected by the presence of another mineral in the same sample. This is due to Prospector's one-way flow of information in the inference net, from data to goals. Any form of unidirectional knowledge representation would suffer the same problem. A bidirectional energy minimization network is a more suitable form of knowledge representation. This is illustrated on a simplified version of the spectral interpretation problem.
Poulton, GT, Bird, TS, Hay, SG & Choi, YK 1970, 'Rigorous design of an antenna for AUSSAT-B', International Symposium on Antennas and Propagation Society, Merging Technologies for the 90's, International Symposium on Antennas and Propagation Society, Merging Technologies for the 90's, IEEE, pp. 1900-1903.
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The prototype antenna designed, constructed, and tested for the AUSSAT-B western Australia regional beam has operated within specifications in all regards. More importantly, the overall design approach of using highly accurate software tools to obtain a successful first-time design has been vindicated. The antenna, comprising an array of horns illuminating an offset paraboloidal reflector, has a beamforming network (BFN) to provide correct power distribution and phasing to the feed elements. The antenna geometry is defined, showing the specified racetrack projected aperture. The other main constraint imposed on the antenna design was a volumetric limit on the feed and beamforming network. The far-field pattern obtained at 12.5 GHz is shown, with the beam pattern computed from measured BFN excitations superimposed. It is shown that the correspondence between theory and experiment is excellent.
Stewart, BW & Catchpoole, D 1970, 'Structural analysis of replicating DNA following exposure to cytotoxic drugs: implications for current models of DNA synthesis in mammalian cells.', Anticancer Drug Des, United States, pp. 141-147.
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The polynucleotide length of single-stranded regions in double-stranded DNA may be determined by caffeine gradient elution from benzoylated DEAE-cellulose. On the basis of this principle, analysis has been made of sheared, deproteinized DNA isolated from synchronized lymphoblastoid cells. Two classes of single-stranded regions were detected. A minor fraction of replicating DNA contained single-stranded regions of 200 nucleotides, whilst the major structural discontinuity involved single-stranded regions of 1-4 kilobases. Newly incorporated [3H]thymidine was principally associated with the latter. Using a 'pulse-chase' protocol, the effect of certain cytotoxic drugs (and related compounds) on the proportion of replicating DNA exhibiting single-stranded character was assessed. The effects were variable. The proportion was increased by hydroxyurea and 3-aminobenzamide, but decreased by inhibitors of DNA polymerase and, to a greater extent, by inhibitors of topoisomerase. Caffeine gradient elution associated drug-induced changes with the radiolabelling of long single-stranded regions. The results are consistent with models of DNA replication involving DNA polymerization remote from replicating forks.
