Showing papers by "University of Manchester published in 1986"

Comparison of the effects of BRL 34915 and verapamil on electrical and mechanical activity in rat portal vein

Abstract: The effects of the novel anti-hypertensive agent BRL 34915, (+/-) 6-cyano-3,4-dihydro-2,2-dimethyl-trans-4-(2-oxo-1-pyrrolidyl)-2H-b enzo[b]pyran-3-ol, have been compared with those of verapamil on rat isolated portal vein. BRL 34915 produced a concentration-dependent reduction in mechanical responses to noradrenaline but had relatively little inhibitory effect on K+-induced contractions. Verapamil reduced the magnitude of both noradrenaline and K+-induced mechanical responses. BRL 34915 delayed the appearance of the reduced noradrenaline contractions, a property not shared by verapamil. BRL 34915 abolished spontaneous electrical and mechanical discharges and hyperpolarized the portal vein cells close to their calculated potassium equilibrium potential. Verapamil inhibited spontaneous electrical and mechanical discharges, effects associated with a small depolarization. BRL 34915 produced a significant increase in the 86Rb efflux rate coefficient whilst verapamil was without effect on this parameter. The inhibitory effects of BRL 34915 were rapid in onset and readily reversible by washing, whilst those of verapamil were slower in onset and only slowly reversible. It is concluded that the inhibitory effects of BRL 34915 in rat portal vein are produced by the opening of potassium channels in the smooth muscle cells. This inhibits spike activity and in sufficient concentration holds the membrane potential at or close to the potassium equilibrium potential, thereby reducing the effects of excitatory agents.

Experimental studies on multijet production in e+e- annihilation at PETRA energies

Abstract: Hadronic jet production bye+e−-annihilation has been studied in the energy range of 14.0–46.7 GeV. The data have been analysed in terms of a cluster algorithm and other topological quantities. The results are compared with 2nd order QCD calculations which incorporate models for the fragmentation of quarks and gluons into hadrons. At the higher energies we observe more spherical and 4-jet like events than predicted by these calculations. We cannot achieve a simultaneous description of the observed 3- and 4-jet production by adjusting the strong coupling constant αs or the fragmentation parameters of the 2nd order QCD models. The observed excess of spherical events can partially be explained by the production of multi-parton events expected from higher order QCD contributions. Consequences of the presented results for the value of αs, determined in previous analyses, are discussed. QCD parton shower models, including soft gluon interference, are able to describe the observed number of spherical events.

Nonlinear dynamical systems

Abstract: State-space models describing function analysis piecewise-linear systems stability control system performance discrete-time systems solutions to exercises.

The effects of BRL 34915 and nicorandil on electrical and mechanical activity and on 86Rb efflux in rat blood vessels.

Abstract: The effects of the antihypertensive agent BRL 34915 on a variety of responses of the aorta and portal vein of the rat have been compared with those of nicorandil. On portal vein, BRL 34915 (0.01-50 X 10(-6) M) and nicorandil (0.1-500 X 10(-6) M) abolished spontaneous mechanical activity and reduced mechanical responses to noradrenaline (0.1-100 X 10(-6) M) and K+ (5-20 X 10(-3) M) but had little inhibitory effect on responses to K+ (40-80 X 10(-3) M). The onset of the reduced responses to noradrenaline was delayed by both agents. On portal vein, BRL 34915 (0.1-50 X 10(-6) M) and nicorandil (0.5-500 X 10(-6) M) abolished spontaneous electrical and mechanical activity, hyperpolarized the smooth muscle cells to a value close to their calculated potassium equilibrium potential and increased the 86Rb efflux rate coefficient. On aorta, BRL 34915 (0.2-0.8 X 10(-6) M) and nicorandil (8-32 X 10(-6) M) reduced mechanical responses to noradrenaline (0.001-1 X 10(-6) M) and K+ (5-20 X 10(-3) M) but had little inhibitory effect on responses to K+ (40-80 X 10(-3) M). On aorta, BRL 34915 (0.2-0.8 X 10(-6) M) increased the 86Rb efflux rate coefficient whereas nicorandil (8-32 X 10(-6) M) was without effect. It is concluded that the inhibitory actions of BRL 34915 on both aorta and portal vein result from the opening of membrane potassium channels. The resulting membrane shunt inhibits the effects of excitatory agents.(ABSTRACT TRUNCATED AT 250 WORDS)

A Life-Cycle Consistent Empirical Model of Family Labour Supply Using Cross-Section Data

Abstract: This paper estimates a utility maximising model of the joint determination of male and female labour supplies using a sample of married couples from the U.K. Family Expenditure Survey. The emphasis is on the estimation of within period preferences that are consistent with intertemporal two-stage budgeting under uncertainty. However, the approach we adopt provides an alternative method of estimating certain aspects of life-cycle behaviour to the fixed effects λ-constant approach of Heckman and MaCurdy (1980), MaCurdy (1981) and Browning, Deaton and Irish (1985). Moreover, it relaxes some of the underlying restrictions that are implicit in these λ-constant models under uncertainty.

Book Review: Principles of CMOS VLSI Design: A Systems Perspective

Abstract: An Introduction to Microprocessors: THORN EMI HOME ELECTRONICS (Macmillan, 1985,86 pp., £5.95 paperback) This text is 'a concise presentation of the functioning of a microprocessor and of the systems that can be constructed by interfacing'. The book builds upon earlier books in the Macmillan series which deal with an introduction to digital techniques and related topics. It is supported by video tapes relating to microprocessor systems. The text deals with the MOSTEK 6502 microprocessor and covers basic ideas, programming and interfacing. The treatment is intended for the enthusiast rather than the undergraduate student. Attention is directed explicitly to the chosen microprocessor and its associated chips. The novice would have considerable difficulty with this text. Without background material provided by earlier texts in the series the material would be difficult to follow. For the enthusiast wishing to know how best to exploit the 6502 the text would be useful. M. G. HARTLEY, Department of Electrical Engineering and Electronics, U MIST

Hormonal control of metabolism in trauma and sepsis.

Abstract: The metabolic changes occurring after injury and in sepsis are still, more than 60 years after their relatively complete description, a cause of significant morbidity and mortality. Although many of their deleterious aspects can be overcome by active nutritional support, this is primarily an empirical means of treatment. The hormonal environment which produces these changes has not been fully elucidated, at least in part because so much of the work in this area has been plagued by the study of small heterogeneous groups of patients at different stages in their response, by a failure to measure the hormones most likely to be relevant, and by an almost universal failure to attempt to relate the endocrine to the metabolic changes observed. This picture is now changing for the better as more interest is centred on the responses to trauma, and the authors are at last in a position to formulate testable hypotheses about the endocrine control of metabolism in trauma and sepsis.

A dispersion model of hepatic elimination: 1. Formulation of the model and bolus considerations

Abstract: A dispersion model of hepatic elimination, based on the residence time distribution of blood elements within the liver, is presented. The general rate equations appropriate for describing the hepatic output concentration of a tracer solute are derived. Particular consideration is given to events following a bolus input dose of a tracer. The model is shown to be compatible with the known hepatic architecture and hepatic physiology. The model has been fitted to hepatic outflow data for red blood cells, albumin, and other noneliminated solutes. The experimental data suggest a high degree of dispersion of blood elements within the liver. The model has also been used to evaluate the effects of changes in enzyme activity, hepatic cell permeability, blood flow, and protein binding on the outflow concentration vs. time profiles of solutes.

The transformation of business finance into financial economics: The roles of academic expansion and changes in U.S. capital markets

Abstract: Financial economics combines a high degree of theoretical abstraction and formality with considerable empirical uncertainty and strong connections to financial institutions and employers. This unusual combination is the product of academic expansion in the leading U.S. post graduate business schools and their attempt to acquire intellectual legitimacy by encouraging scientific research, on the one hand, and of changes in the organization of U.S. financial markets, especially of investment analysis and management, on the other hand. This paper discusses the dominant characteristics of financial economics as an intellectual field and how these contextual factors shaped its emergence.

Electrical and mechanical effects of BRL34915 in guinea‐pig isolated trachealis

Abstract: BRL34915 (0.1-10 microM) suppressed the spontaneous tone of guinea-pig isolated trachealis in a concentration-dependent manner. BRL34915 was not antagonized by propranolol (1 microM). In trachea where spontaneous tone was suppressed by indomethacin (2.8 microM) but subsequently restored to the same level with acetylcholine or histamine, the relaxant potency of BRL34915 was reduced. In Krebs solution containing K+ (120 mM), isolated trachealis muscle developed near-maximal tension. The relaxant effects of BRL34915 were virtually abolished in this medium. Concentration-effect curves for KCl, acetylcholine and histamine were constructed in tissues treated with indomethacin (2.8 microM). BRL34915 (10 microM) depressed the foot of the concentration-effect curve for KCl and caused minor rightward shifts in the concentration-effect curves of acetylcholine and histamine. Four K+-channel inhibitors were tested. Apamin (0.1 microM) did not modify the action of BRL34915. Tetraethylammonium (8 mM) had little effect but procaine (5 mM) and 4-aminopyridine (5 mM) each significantly inhibited the relaxant action of BRL34915. Intracellular electrophysiological recording showed that BRL34915 (0.1 microM) caused very minor relaxation and little, if any, electrical change. Higher concentrations (1-10 microM) evoked relaxation, suppression of spontaneous electrical slow waves and marked hyperpolarization of the trachealis cells. In the presence of TEA (8 mM) or procaine (5 mM) the hyperpolarization induced by BRL34915 was significantly reduced. In trachealis skinned of its plasma membranes, tension development induced by Ca2+ (20 microM) was unaffected either by BRL34915 (10 microM) or by nicorandil (1 mM). In studies of the efflux of 86Rb+ from muscle-rich strips of trachea, BRL34915 (1 and 10 microM) increased the efflux rate constant. It is concluded that BRL34915 evokes relaxation of the trachealis by a mechanism that involves neither beta-adrenoceptor activation nor direct reduction of the sensitivity of the intracellular contractile machinery to cytosolic free Ca2+. The action of BRL34915 may depend on the opening of K+ channels in the plasma membrane which are permeable to 86Rb+. The opening of these channels, or the effects of their opening, may be reduced by K+-channel inhibitors such as 4-aminopyridine, procaine and TEA but not by apamin.

Generation of pair coherent states and squeezing via the competition of four-wave mixing and amplified spontaneous emission

Abstract: Strong competition between four-wave mixing and amplified spontaneous emission in resonant two-photon excitations is shown to generate radiation fields with strong squeezing and antibunching. The generated fields are in a new type of coherent state which is an eigenstate of the operator corresponding to the simultaneous annihilation of photons in two modes.

Autoantibodies against alanyl-tRNA synthetase and tRNAAla coexist and are associated with myositis.

Abstract: The sera of six patients with autoimmune disease, predominantly myositis with pulmonary fibrosis, contain antibodies of the PL-12 specificity. These autoantibodies react with both protein and RNA components of human cells. The protein has a subunit molecular mass of 110 kD, and the RNA comprises a group of bands in the tRNA size class. Aminoacylation experiments identify the antigens as alanyl-tRNA synthetase and its corresponding tRNAs, tRNAAla. Anti-tRNA antibody can be absorbed out without depleting antisynthetase activity, showing that the antigens are recognized independently by separable antibodies that coexist in these sera. The concurrence of separate antibodies to the two components suggests that the autoimmune response may be mounted against the charging enzyme-tRNA complex. However, the antisynthetase antibody fails to coprecipitate tRNA with the enzyme, suggesting that the antibody reacts with its target only when it is not complexed with tRNA.

Global Shift: Industrial Change in a Turbulent World

Abstract: This brief article attempts to highlight why Peter Dicken's Global shift has become a clear 'classic' in human geography. I will also speculate, for speculation is all that is possible in this sort of article, on the why questions: why has it sold many tens of thousands of copies, especially via course adoptions?; why is it now an 'obligatory passage point' in the subdiscipline of economic geography?; and why is it utilized so heavily in disciplines and fields of study as diverse as business, sociology, public policy, political science, development studies, textile products marketing, journalism, etc.?

Catalogue of the mammals of ethiopia

Abstract: SUMMARY The present work completes the systematic treatment of Ethiopian mammals, commenced in 1973, by considering a diverse assemblage of species which presents the mammalogist with two quite distinct problems. Most of the larger forms are relatively free from taxonomic complexities, at least at the specific level, but rapidly declining in numbers as a result of drought, widespread destruction of natural habitat and inadequately controlled hunting. It appears that conservable stocks of pure-bred African Wild ass, Equus africanus (Fitzinger, 1857), now exist only in the Danakil region of Ethiopia, where the population is estimated to number no more than 2–3,000 head, while the herds of E. grevyi Oustalet, 1882 have been severely depleted during the past decade, both in this country and in neighbouring Kenya. The African Elephant, Loxodonta africana (Blumenbach, 1797), now occupies only remnants of its former range in Ethiopia and the position of the small Somali-arid race, L. a. orleansi Lydekker, 1907, ...

The quiet Athenian

Abstract: Like its modern counterparts, Athenian democracy strove to be an assembly of all its citizens. But as is the case with modern democratic states, it often fell far short of this goal. This enlightening work focuses on a previously unexplored strata of Athenian society: the apolitical citizens. The author begins with a review of the traditional drives to honor and fame which gave impetus to ancient Athenian political life and then goes on to analyze the diverse motives of those who chose to abstain from participating in the democratic process. Dr. Carter's discussion takes full account of the demographic factors involved and sheds light on the economic, geographic, and cultural background of these apolitical Athenians.

The IEEE Reliability Test System - Extensions to and Evaluation of the Generating System

Abstract: This paper outlines some of the restrictions which currently exist in the generation data of the IEEE Reliability Test System (RTS) The paper extends the RTS by including more factors and system conditions which may be included in the reliability evaluation of generating systems These extensions create a wider set of consistent data The paper also includes generation reliability indices for the base and extended RTS These indices have been evaluated without any approximations in the evaluation process and therefore provide a set of exact indices against which the results from alternative and approximate methods can be compared

Modern nmr techniques for structure elucidation

Abstract: The rapid growth during the last decade of multiple pulse methods in one (1D) and two-dimensional (2D) NMR has produced over 100 new techniques of potential use in high-resolution NMR. This review sets out to identify and to illustrate those new methods which are most useful in the determination of molecular structure. Ten basic techniques are considered, including 2D homo- and hetero-nuclear chemical shift correlation by direct and by relayed coherence transfer, and 1D polarization transfer. Numerous variations on the basic techniques, for example multiple quantum filtration, are also discussed. Particular attention is paid to the problems of sensitivity and of the optimum choice of experimental techniques for different classes of structural problem.

Management selection in Britain: A survey and critique

Abstract: The results of a survey of the techniques used for managerial selection from 108 organizations in Great Britain are presented. The results reveal that, whilst the usage by large organizations of assessment centre type exercises and biodata is increasing, most organizations still select managers on the basis of interviews and references. It is argued that psychological research and theory should have a bigger impact on selection practice. The limitations of current research and theory are discussed under the headings of criterion measures, validity and utility, and predictors.

Comparison of the structure of human intervertebral discs in the cervical, thoracic and lumbar regions of the spine

Abstract: Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4–5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3–4, T7–8 and L2–3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65°) than in the thoracic and lumbar discs (about 70°). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.

The Type Theoretic Interpretation of Constructive Set Theory: Inductive Definitions

Abstract: Publisher Summary Constructive set theory is a possible framework for the formalization of constructive mathematics. The chapter describes the formal system CZF+DC and its type theoretic interpretation. An inductive definition usually involves the characterization of a collection of objects as the smallest collection satisfying certain closure conditions. Such a characterization can be made explicit in one of at least two ways. The first way is to define the collection as the intersection of all collections that satisfies the closure conditions. Such an explicit definition is thoroughly impredicative in that the collection is defined using quantification over all collections. The second way is to build up the collection from below as the union of a hierarchy of stages. These stages of the inductive definition are indexed using some suitable notion of “ordinal.” The paradigm for a direct understanding of an inductive definition is that for the collection of natural numbers, which is characterized as the smallest collection containing zero and closed under the successor function.

Interactions and arrangements in the process of informing

Abstract: Based on year long participant observation study, this paper attempts to explain how managers are informed or inform themselves. In contrast to the hierarchical systems model of organisations and behaviour typically adopted by information designers, a model of the social order is presented. Adopting a symbolic interactionist perspective, the way managers are informed is defined as a process of informing in which managers construct and maintain arrangements to inform each other and themselves. These arrangements to inform employ the media of interactions, observations, personal record keeping and attending meetings. In addition to describing the process of informing, supported with qualitative data from the research setting, a number of implications of this perspective for information design are considered.