Showing papers by "University of Exeter published in 1989"

Disclosure in the Corporate Annual Reports of Swedish Companies

Abstract: Sweden is of interest because of the rapid growth in the Stockholm stock exchange and because of the country's disproportionate number of multinational enterprises. This paper reports on the extent of disclosure in the corporate annual reports of Swedish companies. An assessment is made as to whether there is a significant association between a number of independent variables and the extent of disclosure.

Statistical Modelling in GLIM

Abstract: Part 1 Introducing GLIM 3: getting started in GLIM 3. Part 2 Statistical modelling and statistical inference: the Bernoulli distribution for binary data types of variables definition of a statistical model model criticism likelihood-based confidence intervals. Part 3 Normal regression and analysis of variance: the normal distribution and the Box-Cox transformation family link functions and transformations regression models for prediction the use of regression models for calibration fatorial designs midding data. Part 4 Binomial response data: binary responses transformations and link functions contingency table construction from binary data multidimensional contingency tables with a binary response. Part 5: multinomial and Poisson response data. Part 6 Survival data: probability plotting with censored data - the Kaplan-Meier estimator the Weibull distribution the Cox proportional hazards model and the piecewise exponential distribution the logistic and log logistic distributions time-dependent explanatory variables. Appendices: discussion GLIM directives system defined structures in GLIM datasets and macros.

The Knowledge, Beliefs and Attitudes of the Mathematics Teacher: a model

Abstract: Official pressure for reforms in the teaching of mathematics overlooks a key factor: the psychological foundations of the practice of teaching mathematics, including the teacher's knowledge, beliefs and attitudes. Research on teaching and teacher education also under‐emphasises this area, which Shulman terms the ‘missing program’ in research on teacher cognitions. The present paper addresses this lack by proposing an analytic model of the different types of knowledge, beliefs and attitudes of the mathematics teacher, and their relationship with practice. Of particular note is the importance accorded to the teacher's practical knowledge of the teaching of mathematics (both pedagogical and curricular knowledge), knowledge of classroom organisation, and knowledge of the school context. Also notable is the importance ascribed to the teacher's beliefs concerning the nature of mathematics, and concerning the processes of teaching and learning mathematics. The model has implications for teacher educatio...

Voluntary Corporate Disclosure by Swedish Companies

Abstract: Sweden is of interest because of the rapid growth in the Stockholm Stock Exchange and because of the country's disproportionate number of multi-national enterprises. This paper reports on the extent of voluntary disclosure in the corporate annual reports of unlisted and listed Swedish companies. A wide-ranging definition of voluntary disclosure is adopted because of the flexibility of approach accepted in Sweden. This should not be construed that Swedish accounting is largely unregulated, rather it reflects a problem of interpretation of what constitutes generally accepted accounting principles in Sweden. In addition, the paper assesses whether there is a significant association between a number of independent variables and the extent of disclosure.

The Kinematics and Aerodynamics of the Free Flight of some Diptera

Abstract: Summary Seven representative species of the order Diptera were filmed in free flight using high-speed cinematography. Insects were killed after filming, and morphological measurements were made in the manner of Ellington (1984£>). The detailed kinematics of selected sequences were then found using frame-byframe digitization, followed by computer reconstruction of the third dimension. Kinematics were qualitatively similar to those observed by Ellington (1984c), though in three species the wings often underwent ventral flexion near the base at the end of the downstroke. For aerodynamic analysis of hovering flight, modified forms of the equations of Ellington (1984eJ) were used. Forward flight was analysed by a novel method, which assumes that an equal but opposite circulation is built up for each halfstroke and allows linear equations to be used. The lift coefficients calculated for hovering were commonly well above those possible by quasi-steady mechanisms, but rotational coefficients were within those that could be achieved by the unsteady lift mechanisms: clap-and-fling (WeisFogh, 1973) and flex (Ellington, 1984d). The lift and rotational coefficients of the two half-strokes were often unequal. In forward flight, the equal circulation assumption often led to an incorrect estimation of the aerodynamic force vector, showing that the circulations during the two half-strokes were unequal. It is suggested that flies manoeuvre largely by altering the unsteady circulations produced at stroke reversal via alterations in the speed and timing of wing rotation. The differences in the mechanisms used by different fly species are related to their flight behaviour in the field.

The particle size characteristics of fluvial suspended sediment: an overview

Abstract: The particle size characteristics of suspended sediment are of fundamental importance in understanding its role in a variety of environmental processes. Existing knowledge concerning the spatial and temporal variability of the grain size composition of suspended sediment is, however, relatively limited. At the global scale, major contrasts may exist between individual rivers in the calibre of their suspended load and this may be related to a number of controls including climate, catchment geology and basin scale. Any attempt to understand the precise relationship between the grain size characteristics of suspended sediment and those of its source material must also take account of the selectivity of erosion and delivery processes. A local case study undertaken by the authors in the 1500 km2 basin of the River Exe in Devon, UK is used to illustrate the considerable spatial variability that may occur within a relatively small area and the complexity of the associated controls.

From Tourist to Tourism Entrepreneur, from Consumption to Production: Evidence from Cornwall, England

Abstract: There has been little research on the social and cultural aspects of tourism entrepreneurship. In this paper the social routes to tourism entrepreneurship are investigated, with emphasis on two major channels - those of the ex-employer and the ex-employee. Data are reported from a case study of Cornwall where 411 firms were interviewed as part of a stratified sample, representing different local economic environments and different sectors of tourism. An analysis of previous occupational experience and of access to capital only provides a partial explanation of entrepreneurship in Cornish tourism. Further analysis of business motivations and of migration patterns reveals an important dimension of noneconomic decisionmaking. This raises questions as to whether tourism entrepreneurship can be seen as a form of consumption rather than production and to its relationship with the entrepreneurial middle class as a whole. -Authors

A Disproof of a Conjecture of Erdős in Ramsey Theory

Abstract: Contre-exemples a la conjecture de Erdos et discussion des proprietes des graphes extremaux

The genetic architecture of interspecific variation in mimulus.

Abstract: The genetic architecture of various floral and morphological differences between Mimulus cupriphilus and Mimulus guttatus is investigated. M. cupriphilus is believed to have speciated from M. guttatus in the recent past. The two parent species, the F(1) and F(2), and two backcrosses were grown and scored for 23 different characters. The analysis of means revealed significant epistasis for a number of the floral characters, particularly those involving the length of parts. Dominance was generally toward M. guttatus, except for the characters related to flowering time. Analysis of the genetic correlations between characters revealed that there were at least four different polygenic genetic systems, governing flowering time, size of flower, number of spots on the corolla, and general size. An analysis of minimum gene number suggested that there were at least 3-7 genes controlling floral size, and a different three controlling floral spot number. Two other characters, corolla lobe shape and stem color, were produced by independent major gene differences. Annuality was also shown to be heritable. The two species appear to utilize the same gene for copper tolerance. The results are discussed in the light of current theories of speciation.

Inertial and aerodynamic torques on the wings of diptera in flight

Abstract: Summary 1. The magnitude and distribution of the torques caused by inertial and aerodynamic forces on the wings of Diptera in flight are calculated. 2. The bending torque at stroke reversal due to the inertia of the virtual mass of air bound to the wing is only slightly less than the torque due to the inertia of the wing mass itself. The maximum inertial torque due to both wing mass and virtual mass is usually slightly greater than the maximum aerodynamic torque encountered by the wings. 3. Bending torques decrease rapidly away from the wing base. 4. Pitching torques are much smaller than bending torques at the wing base, but do not decrease much until near the tip. 5. The pattern of loading affects the wing design. Wings are thicker nearer the base to resist bending, but thin and light near the tip to minimize inertial energy expenditure. Their open, corrugated structure resists bending, while allowing them to be twisted as a result of the weak pitching moments.

The implications of function on the origin and homologies of the dipterous wing

Abstract: The origin of Diptera, and the homologies of the dipteran wing, are re-examined in the light of recent studies on the flight biomechanics and functional wing morphology of Diptera and ofPanorpa. Significant Diptera apomorphies are identified, relevant fossils discussed, and a hypothetical wing ground-plan figured. The arculus, the modified clavus and the anteroposterior asymmetry of the fly wing seem to be adaptations to a mode of flight in which instantaneous wing pitch and camber are controlled automatically, rather than by muscular action; probably in association with the development of asynchronous power musculature. Tillyard's Cu2 (=CUP) is believed to be a secondary pseudo-vein, his 1A to be the true CuP and 2A to be 1A. The late Permian fossil Permotipula Patricia is almost certainly a member of the Diptera stem-group, possibly even of the crown-group. The Mesozoic Laurentipteridae and the Permian Permotanyderidae are other possible, but not certain, stem-group members.

The Creation of New Knowledge by Information Retrieval and Classification.

Abstract: Knowledge can be created by drawing inferences from what is already known. Often some of the requisite information is lacking and has to be gathered by whatever research techniques are appropriate, e.g. experiments, surveys etc. Even if the information has all been published already, unless it is retrieved no inferences will be drawn from it and consequently there will exist some knowledge that is implicit in the literature and yet is not known by anyone. This ‘undiscovered public knowledge’, as it is termed by Swanson, may exist in the following forms: (i) a hidden refutation or qualification of a hypothesis; (ii) an undrawn conclusion from two or more premises; (iii) the cumulative evidence of weak, independent tests; (iv) solutions to analogous problems; (v) hidden correlations between factors. Methods of classification may also play a direct role in the creation of original knowledge. Novel solutions to problems may be discovered by generating different combinations of the basic features of the solutions, as is done in morphological analysis. Alternatively a natural classification may identify gaps in existing knowledge. This paper reviews previous work on producing knowledge by information retrieval or classification and describes techniques by which hidden knowledge may be retrieved, e.g. serendipity in browsing, use of appropriate search strategies and, possibly in the future, methods based on Farradane's relational indexing or artificial intelligence.

The Effects of Group Composition on Group Interactive Processes and Pupil Understanding

Abstract: Previous research has demonstrated the cognitive and affective benefits to be accrued from co‐operative group work. However this body of research has largely been limited to consideration of group products rather than group processes and as such has failed to provide explanations of how, or why, improved outcomes occur. This study focused on group processes in order to throw light on the relationship between group composition, interactive processes and pupil understanding on a cooperative decision‐making task. More specifically it reports on the nature and type of talk in homogeneous, heterogeneous and mixed attaining groups, and their relationships to pupil retention and understanding.

The Export of Slaves from Colchis

Abstract: Polybius in a familiar passage, lists goods moving past Byzantium between the Mediterranean. world and the Black Sea region; among these goods, slaves are accorded a prominent place:…as regards necessities it is an unidsputed fact that the most plentiful supplies and best qualities of of cattle and slaves reach us from the countries lying round the Pontus, while among luxuries the same countries furnish us with an abundance of honey, wax and preserved fish; from the surplus of our countries they take olive-oil and every kind of wine. As for grain, there is give and-take – with them sometimes supplying us when we require it and sometimes importing it from us

Verb guidance and other lexical effects in parsing

Abstract: The process of sentence parsing is clearly influenced by the detailed information recovered from the lexicon for each successive word that appears in the sentence. This information may be used to guide or direct the assembly of new syntactic structures during the initial phases of parsing. Alternatively, it may be used to check or monitor the internal consistency of syntactic frameworks constructed on some other basis. This paper first describes a range of different models in each of these two categories and then reviews the empirical evidence bearing on the alternative models. Overall, it is concluded that current findings are most compatible with structure-checking models. The data are discussed in terms of a model based on a symbol-processing formalism (unification grammar) and the outline of a parser based on a connectionist processing system.

Adolescent smoking: attitudes, norms and parental influence.

Abstract: The self-reported smoking habits and intentions of over 10,000 adolescents, aged 11 to 16 years, were related to a variety of attitudinal and normative variables. Current or previous smoking experience was a more important predictor of future intention to smoke than attitude or subjective norm (others' perceived tolerance of subjects' smoking). Parental opposition to smoking was a more important direct predictor of subjects' smoking intention than parental smoking behaviour.

Adaptive speciation in Mimulus: an ecological comparison of M. cupriphilus with its presumed progenitor, M. guttatus

Abstract: summary The ecology of a recently evolved species, Mimulus cupriphilus, was compared with its presumed progenitor, M. guttatus. Both species live sympatrically as annuals on two small copper mines in Calaveras county, California, USA. There are almost no other species present in the areas where Mimulus dominates. The production of seed by the two species was compared. The relationship between capsule number and plant height differs, with M. cupriphilus having the steeper slope, so that at any particular height it produces more capsules. Mean seed number per capsule, and the relationship between seed number and size of plant, also varies between the two species. M. cupriphilus is normally sell-fertilizing, and thus has a higher probability that a capsule will he fertilized than M. guttatus, which relies more on fertilization by insects. The various parameters can be combined to produce a predicted relationship between size of plant and seed production. When plants are small, M. cupriphilus will produce more seeds, but at heights greater than about V cm M. guttatus will be fitter. The overall resource allocation pattern also reveals that M. cupriphilus devotes a greater proportion of its dry weight to seed and capsule production. These results show that in the habitat where the two species co-exist, arid deserted copper mines, the derived species is better adapted.

Gambling in children and adolescents

Abstract: The topic of adolescent gambling is attracting growing interest, but there has still been little controlled or systematic research into the area, and much of what has been written would best be described as “armchair theorizing.” The literature concerning pre-adult gambling behavior falls into three general categories: (a) direct and indirect studies concerning adolescent gambling; (b) studies of the economic socialization of children, and (c) consideration of gambling as play and games as precursors to gambling. This paper presents an overview of the literature examining each of these three categories. Special emphasis is placed upon the playing of fruit machines, as it is this activity which is currently regarded as the biggest problem concerning young gamblers, particularly in the U.K. Recommendations for future research are discussed, particularly for work using a functional/behavioral analysis model to determine the variables which influence how adolescents “learn” to gamble.

Heteronuclear Cluster Chemistry of Copper, Silver, and Gold

Abstract: Publisher Summary This chapter reviews the synthesis, structures, chemical properties, and dynamic behavior of copper, silver, and gold—containing heteronuclear cluster compounds. A cluster compound is considered to be a species, which contains three or more framework atoms with sufficient interactions among them to define either a metal core made up of one or more trigonal planar M 3 units or a three-dimensional skeletal geometry based on a wide variety of polyhedra. The chapter is restricted Group IB metal cluster compounds in which the skeletal atoms consist predominantly of transition metals. In the vast majority of the Group IB metal heteronuclear clusters reported so far, one two-electron donor ligand is attached to each coinage metal and PR 3 is the most common ligand of this type. A number of species with coinage metals that do not carry any ligands or with ligands that are not simple two-electron donors bonded to the Group IB metals are also known and these clusters are also described in this chapter.

Children's concepts of illness: Towards an alternative to the “Stage” approach

Abstract: Research concerned with the development of children's beliefs about health and illness has practical implications for educating children about their illness, treatment and hospital admission. Previous research has suggested that beliefs about health and illness develop through a series of systematic stages, and that children are unable to understand explanations in advance of their own cognitive level. Alternative theories which give greater emphasis to the role of experience are considered, and some implications for clinical practice drawn.

Rates and patterns of contemporary floodplain sedimentation: A case study of the river Culm, Devon, UK

Abstract: A variety of methids have been used to document contemporary rates of overbank sedimentation along an 11 km reach of the floodplain of the River Culm in Devon, UK. These have included measurements of the conveyance loss of suspended sediment between upstream and downstream measuring stations, the use of sediment traps, and the application of caesium-137 measurements to estimate the rate of accumulation of fine sediment over the past 30 years. The resultant data point to sedimentation rates typically of the order of 1500 g m−2 year−1 or 1.5 mm year−1. Values in excess of 15000 g m−2 year−1 or 15 mm year−1 have been documented in closed depressions and in backwater embayments close to the channel, whereas minimal deposition and even scour may occur along those areas that function as secondary channels during floodplain inundation.

Nuclear attitudes before and after chernobyl : change and judgment

Abstract: This study examines the attitudes of residents of a small town in Dorset, England, toward nuclear and oil developments. The sample consisted of 135 respondents to a follow-up questionnaire sent in June 1986 to a group of 356 residents who had responded to a previous questionnaire immediately before the Chernobyl accident in April 1986. There were shifts in the direction of greater opposition to the existing local nuclear plant, and the building of more nuclear power stations elsewhere in the country; comparable shifts were not found in attitudes toward non-nuclear industrial developments. Post-Chernobyl attitudes were closely related to evaluations of statements offering alternative interpretations of the accident, in a manner predictable from research on social judgment.

Nonlinear Tollmien-Schlichting/vortex interaction in boundary layers

Abstract: The nonlinear reaction between two oblique 3-D Tollmein-Schlichting (TS) waves and their induced streamwise-vortex flow is considered theoretically for an imcompressible boundary layer. The same theory applies to the destabilization of an incident vortex motion by subharmonic TS waves, followed by interaction. The scales and flow structure involved are addressed for high Reynolds numbers. The nonlionear interaction is powerful, starting at quite low amplitudes with a triple-deck structure for the TS waves but a large-scale structure for the induced vortex, after which strong nonlinear amplification occurs. This includes nonparallel-flow effects. The nonlinear interaction is governed by a partial differential system for the vortex flow coupled with an ordinary-differential one for the TS pressure. The solution properties found sometimes produce a breakup within a finite distance and sometimes further downstream, depending on the input amplitudes upstream and on the wave angles, and that then leads to the second stages of interaction associated with higher amplitudes, the main second stages giving either long-scale phenomena significantly affected by nonparallelism or shorter quasi-parallel ones governed by the full nonlinear triple-deck response.

Modelling of reference values for size at birth.

Abstract: Data from the Swedish Medical Birth Registration, 1977-1981 were used to apply methods of constructing reference standards for size at birth. Using clinical information a 'healthy' sub-population was extracted. The conditional distributions of birthweight (BW) and birthlength (BL) for each week of Gestational age, and the conditional distribution of birthweight given birthlength were modelled using truncated Normal distributions, after making use of Box-Cox power transformations. Spline functions were then used in conjunction with a multiplicative method to obtain appropriate percentage point curves. Examples of this analysis are given.

Intelligent tutoring systems survey

Abstract: Simple computer assisted instruction (CAI) systems suffer from the fact that in general they do not know the subject matter they are teaching. Intelligent tutoring systems (ITS) use artificial intelligence (AI) formalisms to represent knowledge in order to improve on CAI systems. We survey a number of systems developed, and the emerging architecture for ITS development.

Health locus of control and health beliefs in relation to adolescent smoking.

Abstract: Summary Results from a survey of 10,579 schoolchildren aged 11–16 years indicated various relationships between age, smoking behaviour, health locus of control beliefs, expressed concern with different consequences of illness and beliefs in the efficacy of different strategies for staying healthy. In particular, smokers, compared with non-smokers, showed less belief in the importance of ‘powerful others’ or ‘personal control’ but more belief in the importance of ‘chance’ as an influence on health outcomes. With regard to consequences of illness, smokers cared more than non-smokers about not being allowed to see friends, but less about getting behind in school or being a nuisance to others; they were also less convinced of the benefits of preventive health behaviours such as eating good food and taking exercise. Implications for health education approaches are discussed.