Showing papers by "Lancaster University published in 1984"

Computer simulation in management science

Abstract: From the Publisher: Mike Pidd updates this new edition to focus more attention on system dynamics as a result of increasing interest in this area. Other revisions include an increase in the number of exercises at the end of each chapter, an expansion of the area of the book covering visual interactive modeling systems, strengthening of statistical aspects of the text, and a general overhaul of the original material to bring the references and general tone up to date.

Formulae and Program to Determine Total Carotenoids and Chlorophylls A and B of Leaf Extracts in Different Solvents

Abstract: Various equations for the determination of total chlorophyll and individual amounts of chlorophylls a and b in extracts from plant tissues exist (see Holden 1976) and some of them (e.g. Arnon 1949) have been widely used. Additional modifications to the equations have also been developed so as to permit an estimate of total carotenoids to be made from the spectrum of the same mixture in di-ethyl ether (Ziegler, Egle 1965; Gaudillere 1974).

Learning and developing from managerial work experiences

Abstract: DURING the last decade there has been an increasing interest in the waymanagers learn from normal work experiences. This has emerged fromscepticism about whether formal management training ever gets used at all(Davies, 1973; Mant, 1969), and questions about whether, even if it is used,it produces the kind of behaviour which might lead to effective management,and hence business, performance (Hays and Abernathy, 1980; Livingston,1971; Revans, 1981). Furthermore the potency of natural learning has beenemphasized at a theoretical level by Kolb e

Sex and Organizational Analysis

Abstract: The focus of the paper is on the process of organizational desexualization which has taken place over a long historical period and upon the resistance which this process has engendered amongst organizational subordinates. The eradication of the high level of sexual activity which took place in pre-industrial organizations was sought by those in positions of authority and the paper considers the variety of mechanisms which were developed to attain this expulsion. These mechanisms are well entrenched in contemporary organizations, yet have met with considerable resistance from lower-order organizational members. The paper considers certain forms of resistance in this light in an attempt to suggest a dialectical approach to sexuality. It is concluded that the issue of sex is one which organizational analysis has avoided for too long.

Interaction between two decomposer basidiomycetes and a collembolan under Sitka spruce: Distribution, abundance and selective grazing

Abstract: The fungi Mycena galopus (Pers. ex Fr.) Kummer and Marasmius androsaceus (L. ex Fr.) Fr. produced over 99% of the fruit bodies on a site under Picea sitchensis Carr. In the laboratory M. androsaceus colonized litter from both the L and F 1 horizons more than twice as fast as M. galopus , but in the field its distribution was restricted to the L horizon whereas M. galopus occurred in the F 1 horizon. The collembolan Onychiurus latus Gisin, the most abundant mycophagous arthropod at the field site which consistently had basidiomycete hyphae in its gut, was found throughout the autumn in the litter horizons in densities up to 600 m −2 . This collembolan showed a marked preference for the mycelium of M. androsaceus rather than that of M. galopus in both laboratory and field tests. These results suggest that selective grazing by O. latus may be an important factor in determining the vertical distribution of these two fungi in the field.

Interaction between two decomposer basidiomycetes and a collembolan under Sitka spruce: Grazing and its potential effects on fungal distribution and litter decomposition

Abstract: The hypothesis that selective grazing by Onychiurus latus Gisin altered the outcome of competition between two basidiomycetes, Mycena galopus (Pers. ex Fr.) Kummer and Marasmius androsaceus (L. ex Fr.) Fr. on Sitka spruce litter was tested. Without grazing M. androsaceus had the higher colonizing ability of litter in the laboratory whereas with grazing the position was reversed. Field exclusion experiments also suggested that higher densities of O. latus resulted in a reduction in the activity of M. androsaceus and an increase in that of M. galopus and vice versa. It is suggested that selective grazing may be an important factor determining the field distribution of these fungi, since M. androsaceus , the preferred food source, was restricted to the L litter horizon where the density of O. latus was not high enough to alter the outcome of competition whereas M. galopus predominated in the F 1 horizon. The rate of decomposition of Sitka spruce litter in the laboratory caused by M. androsaceus (17% dry weight loss over 6 months at 11°C) increased by 4–14% in the presence of grazing by O. latus whereas that of M. galopus (11.5%) decreased by 12–16%.

The E.O.Q. for Linear Increasing Demand: A Simple Optimal Solution

Abstract: The E.O.Q. is derived for constant, continuous demand. For linear increasing demand, Donaldson's analytical solution considers demand bounded by a time horizon H. Although this is mathematically convenient for obtaining a solution, it complicates the calculation of the optimal replenishment policy. Extending the time horizon so that it no longer influences the replenishment times simplifies the calculation of the optimal policy, which is then equivalent to the E.O.Q. calculation for constant demand.

Hemisphericity: A critical review

Abstract: Hemisphericity refers to the idea that people may rely on a preferred mode of cognitive processing, which is linked to activity on the part of the left or right cerebral hemispheres. Four methods have been used in hemisphericity research: lateral eye-movements, electrophysiological measures, questionnaires and cognitive tests. It is demonstrated that none has been properly validated with respect to the purposes for which they are employed in studies of hemisphericity. It is argued that the idea of hemisphericity lacks adequate foundation and that, because of the assumptions implicit in the idea of hemisphericity, it will never be possible to provide such a foundation. The idea is a misleading one which should be abandoned.

4 Transepithelial Potentials in Fish Gills

Abstract: Publisher Summary This chapter describes the different aspects of transepithelial potentials in fish gills. The knowledge of the transepithelial potential is essential in the interpretation of the movements of ions across an epithelium. The transepithelial potential observed in the gills of a teleost is generated by a diffusion potential, arising from the difference in composition between the blood plasma and the external medium and a metabolically maintained component, arising from the active transport of ions. In euryhaline fishes, the potentials approximate to the Nernst potentials for sodium, depolarizing as the external concentration falls and even reversing in hypoosmotic solutions. The substitution of sodium by the larger, less permeant organic ion, choline, also depolarizes the gills, whereas the substitution of organic anions for chloride hyperpolarizes them, but to a smaller extent. Calcium ions modulate the permeability of the gill in both seawater and fresh water, but whereas seawater always contains about 20 mEq l − l , fresh water usually contains somewhere between 0.1 and 1.0 mEq l −1 and some waters have calcium concentrations that lie even outside this range. Bicarbonate ions in the external medium stimulate chloride efflux in the toadfish, Opsanus tau, but have no significant effect on the transepithelial potential.

Torfajökull: A volcano dominated by magma mixing

Abstract: All postglacial (less than 10 000-yr-old) rhyolite eruptions from Iceland9s largest silicic center show evidence of admixture with basaltic magmas The degrees of mixing vary from rare inclusions within host rhyolites to completely homogeneous blends with hybrid compositions The model presented here explains the dominance of mixed-magma eruptions in recent activity and addresses the likely influence that magma mixing may have in future eruptive events

A firm specific analysis of economies of density in the u.s. railroad industry

Abstract: AN UNDERSTANDING of the nature of costs of production is important in every regulated industry, both for policy makers and firms. Policy makers may be interested in whether there are economies of scale in production, and in whether there are technological aspects of an industry that will pose difficult problems if an industry is regulated. Regulators and firms may be interested in costs for ratemaking purposes, and in decisions about the effects of introducing new services or discontinuing existing services. Historically most cost studies in regulated industries have used data drawn from a cross section of firms, or from a combination of cross section and time

Soft evaluation of Boolean search queries in information retrieval systems

Abstract: La logique booleenne est le support le plus courant a la formulation des questions lors d'une recherche automatisee. Ses performances sont evaluees, sur des donnees mathematiques et logiques, en particulier dans le domaine de la recherche bibliographique ou les resultats sont loin d'etre parfaits

The psychopharmacology of lithium

Abstract: This review covers the literature on the behavioural effects of lithium since 1974. Behavioural and cognitive actions of lithium are outlined in the context of a discussion of various methodological issues which arise with lithium research. A suggestion that lithium may produce behavioural effects by impairing the central processing of sensory information, particularly of stimuli of around difference threshold level, is examined in the light of a number of objections which have been raised to such a model.

Geochemical Evolution of the Menengai Caldera Volcano, Kenya

Abstract: The Menengai volcano is composed almost entirely of strongly peralkaline, Si-oversaturated trachytes. No mafic or intermediate products have yet been identified. The volcano has had a complex geochemical evolution, resulting from the interplay of magma mixing, crystal fractionation and liquid state differentiation. The controlling mechanism at any time was related to the growth stage of the complex, the presence of volatile gradients in the chamber, and the distribution of magma densities in the chamber. Prior to a major ash flow eruption, the magma reservoir was growing by the addition and mixing of two or more trachytic melts, only slightly different in composition. A volatile-rich cap eventually separated from the lava-forming zone and became compositionalIy zoned by liquid state processes. In late pfecaldera times, trachyte magma was able to penetrate into the cap zone, resulting in the eruption of mixed magma. The first Menengai ash flow tuff was erupted from a compositionally zoned magma chamber which showed strong roofward enrichment in Fe, Mn, Cs, Hf, Nb, Ni, Pb, Rb, Ta, Th, U, Y, Zn, Zr, and the REE (including Eu) and probably also Na, Cl, and F, and roofward depletion in Al, Mg, Ca, K, Ti, P, Ba, and Sc. Observed enrichment factors of up to 5 make this one of the most strongly zoned ash flow units yet recorded. Zonation was achieved by liquid state differentiation, probably involving volatile transfer and thermodiffusion, and minor crystal fractionation. After a period of rehomogenization of the magma remaining in the upper parts of the chamber, the second Menengai ash flow tuff was erupted, with formation of the present caldera. This unit is also compositionalIy zoned, although with lower observed enrichment factors than the first sheet. Caldera collapse was followed by convective overturn within the magma chamber and the rise to the roof zone of a Ba-rich magma from a level not tapped by the as flow. Enrichment of volatiles in this zone resulted in the establishment of a stable density interface between an upper, tuff-producing zone and the lower, lava-forming zone. In the latter, 25% crystallization of syenite took place against the side walls. Crystallization in the tuff-forming zone was more extensive (75%) and produced a series of chemically evolved tuffs. At some critical stage, liquid state processes became dominant in both zones and compositional variations comparable to those in the ash flow sheets were established. Some mixing of the upper and lower zone magmas may have occurred relatively recently. The Menengai volcano provides evidence of the development by liquid state mechanisms of extensive compositional zonations through thicknesses in excess of 102 m in times of 102–103 years. It also gives unique information on the senses and amounts of elemental enrichments and depletions during liquid state differentiation of trachytic magma.

Gramsci and peasant subalternity in India

Abstract: Such key Gramscian concepts as hegemony and passive revolution, hitherto discussed mainly in relation to Western industrial societies, also have a direct relevance to the study of peasant societies. Critically applied, Gramsci's ideas give fresh emphasis to the central importance and dialectical nature of elite‐subaltern relations in rural India in the nineteenth and twentieth centuries. His stress upon the negative and derivative aspects of peasant culture and ideology needs, however, to be qualified by an awareness of the strengths and relative autonomy of subaltern politics within the overall structure of elite domination.

Essay Planning and Essay Writing

Abstract: Undergraduate students are commonly advised to make plans of their essays before they begin writing, yet there is little empirical evidence on the nature, role or efficacy of essay planning. This paper examines findings from a recent study of coursework essay‐writing as an aspect of student learning in the social sciences. A total of 16 Psychology and 17 History students took part in the investigation, which mainly took the form of two sets of semi‐structured interviews. From an analysis of the interview transcripts, five planning strategies were identified. However, it was apparent that to gain a full understanding of the nature of planning, it was necessary to examine these strategies in the light of the main findings of the study—a qualitative analysis of differences in the students’ conceptions of what an essay was and what essay‐writing involved. In sum, what seemed important was less how a student planned than what planning was directed towards.

Technical analysis of IIASA energy scenarios

Abstract: Despite the appearance of analytical rigour, IIASA's widely acclaimed global energy projections are highly unstable and based on informal guesswork. This results from inadequate peer review and quality control, raising questions about political bias in scientific analysis.

New methods for nuclear cooling into the microkelvin regime

Abstract: We describe the philosophy and practice of a new method of nuclear cooling in which the copper refrigerant is immersed directly in the3He sample to be cooled using a guard cell configuration. The method has been used to cool liquid3He to ∼120 µK. We also describe a variant of the method intended for cooling metallic samples, by which a platinum NMR thermometer has been cooled to ∼13 µK. Finally, in an appendix we suggest a very simple nuclear cooling method utilizing the copper flakes used in the manufacture of paint, which will cool liquid3He to around 1 mK with a minimum of cryogenic effort.

Effects of rust and post‐infection drought on photosynthesis, growth and water relations in groundsel

Abstract: Exchanges of CO2 and water vapour were examined in groundsel, Senecio vulgaris, grown and infected with rust, Puccinia lagenophorae, under laboratory conditions. The effects of drought were examined by withholding water from plants from 2 days until approximately 10 days after infection, after which further daily water losses were restored. Net photosynthesis was inhibited and dark respiration was stimulated in rust-infected leaves but, in young healthy leaves on the same plant, gross and net photosynthesis were stimulated and photorespiration was inhibited. The growth of plants was stunted 15 days after infection because the growth of leaf area was inhibited and, thereby, the photosynthetic capacity of the plant was reduced. Drought inhibited the growth of leaf area in both healthy and infected plants and, when combined with rust, had additive deleterious effects on net photosynthesis per plant and on growth. After sporulation, rusted plants transpired more rapidly than did healthy controls and leaf water potential fell to reach - 0.95 and-1.92 MPa in well-watered and drought-stressed plants respectively, compared with -0.18 and - 1.2 MPa in healthy controls, 20 days after infection. Rust impaired the normal increase in Water-Use Efficiency in response to drought.

Beyond Floating Point

Abstract: Un systeme numerique est propose pour l'arithmetique d'ordinateur basee sur des fonctions exponentielles iterees L'avantage principal est d'extirper le sous-passement et le depassement de capacite, mais il y a quelques autres avantages et ceux-ci sont decrits et discutes