Showing papers by "City University London published in 1993"

The mechanics of cemented carbonate sands

Abstract: The behaviour of artificially cemented carbonate sand was investigated in triaxial tests at confining pressures of up to 9 MPa. The results show that an important effect of cementing is a reduction in specific volume resulting from the increase in fines content This influences both the stress-strain behaviour and the peak strength at strains beyond those required to fracture the cement bonding. Comparisons between the behaviour of cemented and uncemented soils should, therefore, be carried out on samples with the same gradings. For cemented samples it is possible to identify a yield curve outside the state boundary surface of the uncemented soil. A framework for the behaviour has been defined which depends on the relative magnitudes of the confining pressure and cement bond strength. The behaviour of a natural cal-carenite agreed well with this framework which is also likely to be applicable to other cemented soils. Le comportement d'un sable carbonate artificiellement cimente a ete etudie a l'aide d'essa...

Conscious visual perception without V1.

Abstract: We used the technique of PET to determine whether visual signals reach visual area V5, specialized for visual motion, when a human patient, blinded by a lesion in area V1, discriminates the direction of motion of visual stimuli and shows, through his verbal reports, that he is consciously aware of both the nature of the visual stimulus and its direction of motion. The results showed that area V5 was active without a parallel activation of area V1, implying that the visual input can reach V5 without passing first through V1 and that such an input is sufficient for both the discrimination and the conscious awareness of the visual stimulus.

Validation of ultrahigh dependability for software-based systems

Abstract: Modern society depends on computers for a number of critical tasks in which failure can have very high costs. As a consequence, high levels of dependability (reliability, safety, etc.) are required from such computers, including their software. Whenever a quantitative approach to risk is adopted, these requirements must be stated in quantitative terms, and a rigorous demonstration of their being attained is necessary. For software used in the most critical roles, such demonstrations are not usually supplied. The fact is that the dependability requirements often lie near the limit of the current state of the art, or beyond, in terms not only of the ability to satisfy them, but also, and more often, of the ability to demonstrate that they are satisfied in the individual operational products (validation). We discuss reasons why such demonstrations cannot usually be provided with the means available: reliability growth models, testing with stable reliability, structural dependability modelling, as well as more informal arguments based on good engineering practice. We state some rigorous arguments about the limits of what can be validated with each of such means. Combining evidence from these different sources would seem to raise the levels that can be validated; yet this improvement is not such as to solve the problem. It appears that engineering practice must take into account the fact that no solution exists, at present, for the validation of ultra-high dependability in systems relying on complex software.

The behaviour of granular soils at elevated stresses

Abstract: The behaviour of three diverse granular soils (Dogs Bag sand, decomposed granite, and Ham River sand) has been investigated over a wide range of stresses (50 kPa - 58 MPa) allowing a general framework to be developed for the behaviour of granular soils. Characteristic features such as a normal compression and critical state lines may be identified and the description of the mechanics of these soils is therefore similar in many respects to the critical state framework developed for clay soils. For granular soils, the principal means of volumetric compression is through particle crushing and this gives rise to some unusual features, notably that for these soils the critical state is not at the apex of the state boundary surface. Particle breakage has been quantified and unique relationships identified between the degree of breakage and the stresses applied, both for isotropic compression and at the critical state. (A) For the covering abstract see IRRD 859983.

Development of the Trilateral Flash Cycle System: Part 1: Fundamental Considerations:

Abstract: The world market for systems for power recovery from low-grade heat sources is of the order of £1 billion per annum. Many of these sources are hot liquids or gases from which conventional power systems convert less than 2.5 per cent of the available heat into useful power when the fluid is initially at a temperature of 100° C rising to 8–9 per cent at an initial temperature of 200°C. Consideration of the maximum work recoverable from such single-phase heat sources leads to the concept of an ideal trilateral cycle as the optimum means of power recovery. The trilateral flash cycle (TFC) system is one means of approaching this ideal which involves liquid heating only and two-phase expansion of vapour. Previous work related to this is reviewed and details of analytical studies are given which compare such a system with various types of simple Rankine cycle. It is shown that provided two-phase expanders can be made to attain adiabatic efficiencies of more than 75 per cent, the TFC system can produce outputs of...

Risk factors with contact lens related suppurative keratitis.

Abstract: Risk factors in contact lens related suppurative keratitis were investigated. Over 12 months, sixty contact lens wearers presented with presumed microbial keratitis and 147 presented with presumed sterile keratitis. The control group consisted of contact lens wearers without lens related disorders (n = 507). The relative risk of microbial keratitis for extended wear soft contact lens users were 36.8 times (12.6-107.6) that of rigid gas permeable (RGP) contact lens users; while the relative risk of sterile keratitis among extended wear soft lens users was 4.6 times (2.2-9.9) that of RGP lens users. For daily wear soft contact lens users, the relative risk of microbial keratitis was 4.2 times (1.1-16.0) that of RGP lens wearers; for sterile keratitis the relative risk was 2.3 times (1.3-4.3) greater than RGP contact lens users. A multivariable logistic regression analysis was used to examine associated risk factors for daily and extended wear soft lens users. The type of disinfection system and its frequency of use were associated with both microbial keratitis and sterile keratitis in daily wear users. Duration of overnight wear and gender were associated with microbial keratitis, while a patient's age and socioeconomic class were associated with sterile keratitis. Different relative risks and risk factors for microbial keratitis and sterile keratitis support the use of a clinical definition to differentiate the diseases.

Lessons learned in building a corporate metrics program

Abstract: The achievements of the Contel Technology Center's software-metrics project, which brought metrics use from concept to standard operating procedure throughout the corporation, are reviewed. Metrics and process maturity pilot projects, metrics tools, metric databases, and metric data analysis are discussed. The lessons learned from the project, which could help metrics programs in other large, diverse organizations, are also discussed. >

Recognition memory and awareness: An experiential approach

Abstract: This article reviews recent studies that have adopted an experiential approach to recognition memory and awareness. This approach measures two subjective states of awareness in recognition memory, remembering (or conscious recollection) and knowing (or familiarity). There is now evidence of quite a few experimental dissociations between these two states of awareness. These dissociations impose additional constraints on theories about relations between awareness and memory systems or processes.

Effects of lorazepam upon recollective experience in recognition memory

Abstract: The effects of lorazepam (2 mg) and placebo upon recognition memory with and without conscious recollection were assessed in a cross-over study with normal volunteers. When recognising a word from study lists presented before and 1, 3 and 5 h after drug administration, subjects were required to indicate whether they could consciously recollect the word's prior occurrence or recognised it on the basis of “knowing”; in the absence of conscious recollection. Lorazepam only impaired word recognition which was accompanied by conscious recollection, and further, the level of this impairment correlated significantly with each of three different indices of subjects' arousal at the time of presentation of each list. Recognition in the absence of conscious recollection was not impaired but somewhat heightened by lorazepam, and these effects did not significantly relate to any index of arousal. These findings are interpreted as providing further support for the notion that recognition entails two distinct components, one based on contextual and associative information and related to conscious recollection, the other possibly based on a “traceless” perceptual or semantic memory system and related to feelings of knowing in the absence of conscious recollection. Implications are drawn for a contextual-encoding/retrieval account of lorazepam-induced amnesia.

The measurement of gender role behaviour in pre-school children: a research note.

Abstract: The development and construction of a new psychometric scale, the Pre-School Activities Inventory (PSAI) for the assessment of gender role behaviour in young children, is reported. The test specification, piloting and item analysis are described. Data are also given on reliability and on the various validation procedures used, as well as on age standardization and norming.

Investigation of limbal touch sensitivity using a Cochet-Bonnet aesthesiometer.

Abstract: Following the observation of complex sensory receptors concentrated within the palisade zone of the human conjunctiva, this study sought to measure limbal touch sensitivity using a Cochet-Bonnet aesthesiometer. Touch sensitivity was found to be significantly higher in the palisade zone compared with the adjacent conjunctiva. A comparison between temporal and inferior limbus showed a greater median sensitivity for the temporal zone. There was a significant reduction in touch sensitivity with age, but not with iris colour or contact lens wear. These data, showing a higher touch sensitivity for the palisade zone, provide indirect evidence for a role of complex nerve endings in mechanoreception.

Five-compartment model of insulin kinetics and its use to investigate action of chloroquine in NIDDM

Abstract: We have constructed a five-compartment model of insulin kinetics. The model structure was chosen to reflect insulin distribution in systemic plasma, hepatic plasma, and interstitial fluid and insulin binding to the liver and peripheral receptors, and it included receptor-mediated and non-receptor-mediated insulin degradation. Model parameters were estimated from plasma insulin concentrations measured during hyperinsulinemic euglycemic clamp studies. In the fasting condition, the model-derived mean residence time of endogenously secreted insulin was 71 min, of which 62 min were spent bound to the liver receptor, 6 min bound to the peripheral receptor, 2 min circulating in hepatic or systemic plasma, and 1 min in the interstitial fluid. More than 80% of total insulin was bound to the liver receptor, indicating that the liver is by far the largest insulin reservoir. The model was employed to assess the effect of chloroquine on insulin kinetics in patients with non-insulin-dependent diabetes mellitus (NIDDM). Chloroquine significantly altered parameter vector. However, the mean residence times of insulin in the system and in the periphery were not affected, indicating that the beneficial effect of chloroquine in patients with NIDDM under conditions of euglycemia could not be attributed to changes in insulin kinetics.

Anxiety, knowledge and satisfaction in women receiving false positive results on routine prenatal screening: a randomized controlled trial

Abstract: The majority of women receiving an abnormal result on routine prenatal screening subsequently give birth to unaffected children. Previous studies have documented high levels of anxiety in women receiving such false positive results. In an attempt to reduce this anxiety, two methods of preparing women for undergoing such testing were compared: provision of detailed written information about maternal-serum alpha-fetoprotein testing; and anxiety management training. Eligible women were randomly allocated to one of five groups. Eighty-five women subsequently received false positive results on routine alpha-fetoprotein testing. There was some evidence that completing the study questionnaires had an anxiety-reducing effect. In contrast with the results of previous studies, there was no evidence that receipt of an abnormal alpha-fetoprotein result resulted in raised anxiety. Neither of the interventions, alone or in combination, had an effect upon anxiety following an abnormal alpha-fetoprotein result. Receipt of detailed written information however, led to women having, more knowledge and being more satisfied with the amount of information that they had. One in three of the class groups reported that the classes had influenced the way they had dealt with worries. Although the interventions did not reduce anxiety in this study, there are other reasons for considering their incorporation into routine clinical practice.

`Selling scandal': business and the media

Abstract: Etude de la place des medias dans les societes capitalistes. Analyse du poids et de l'ascendant du monde des affaires dans la communication de base : notions de propriete et de controle de l'information

The meaning of bad news in HIV disease: Counselling about dreaded issues revisited

Abstract: HIV disease is a slow, progressive immunological disorder. As there is neither a cure nor a vaccine, morbidity and mortality arising from HIV infection will continue to challenge health care providers, including those who counsel these patients. Psychological preparation for ‘bad news’ and support for those whose health is deteriorating is an important task in HIV counselling. This paper describes what may be considered bad news for people living with HIV, how to prepare them for unwelcome changes in their medical condition and how to give bad news, should the need arise.

Economic burden of treated benign prostatic hyperplasia in the United Kingdom.

Abstract: Recent epidemiological studies suggest that much urological disease is untreated. However, the overall economic burden of urological diseases has never been systematically studied. This report estimates the economic burden of treated benign prostatic hyperplasia (BPH) in the United Kingdom by considering the direct costs falling on the health service, the indirect costs in lost production, and the intangible costs in reduced quality of life. Depending on the assumptions made, the economic burden in 1990 is estimated to have been between 62 million pounds and 91 million pounds annually, excluding the intangible costs. The maximum cost to the National Health Service (NHS) represents approximately 0.4% of total NHS expenditure. This finding is therefore consistent with the results of recent epidemiological studies, which suggest that the main burden of BPH is borne by sufferers in terms of reduction in quality of life and is not reflected in consumption of health care resources. However, this balance may change as a result of the new General Practitioner contract and new treatment options.

Maternal-fetal attachment during pregnancy following in vitro fertilization

Abstract: The aim of the study was to examine the degree of anxiety experienced by pregnant women who had conceived by in vitro fertilization (IVF), as well as their attitudes towards the pregnancy and the strength of their attachment to the fetus Fifteen women who had conceived by IVF were compared with 20 women who had conceived without assistance Each woman was administered the State-Trait Anxiety Inventory, the Childbearing Attitudes Questionnaire and the Maternal-Fetal Attachment Scale While the two groups of expectant mothers did not differ on these measures, a clear relationship was found for all of the women combined between general attitudes towards childbearing and attachment to the fetus, showing that women who are less positive about pregnancy, childbirth and childcare show weaker attachment to their unborn child

Monetary Regimes in Transition

Abstract: List of figures List of tables List of contributors 1. Introduction Michael D. Bordo and Forrest Capie Part I. Commodity Money Standards in Transition: 2. The scramble for gold: monetary regime transformation in the 1870s Giulio M. Gallarotti 3. The Latin Monetary Union and the emergence of the international gold standard Angela Redish 4. Greenback resumption and silver risk: the economics and politics of monetary regime change in the United States, 1862-1900 Charles W. Calomiris Part II. Successful and Unsuccessful Adherence to the Gold Standard: 5. Spain during the classical gold standard years, 1880-1914 Pablo Martin-Acena 6. Canada and the gold standard, 1871-1914: a durable monetary regime Trevor J. O. Dick and John E. Floyd 7. Australia's payments adjustment and capital flows under the international gold standard, 1870-1913 David Pope Part III. Wartime Upheaval and Postwar Stabilization: 8. British and French finance during the Napoleonic Wars Michael D. Bordo and Eugene N. White 9. Interpreting a change in monetary policy regimes: a reappraisal of the first Hungarian hyperinflation and stabilization, 1921-1928 Pierre L. Siklos 10. Halting inflation in Italy and France after the Second World War Alessandra Casella and Barry Eichengreen 11. The rise and fall of credit controls: the case of Sweden, 1939-1989 Lars Jonung Part IV. Perspectives on Monetary Regimes: 12. An assessment of monetary regimes Anna J. Schwartz Index.

Bridging the requirements gap: policies, goals and domains

Abstract: A model for requirements engineering is described which uses a taxonomy of goal-types to guide further analysis. Goals are classified according to the desired system state described in requirements statements. Heuristics then prompt further description of functions according to each goal class. Other analyses encourage expansion of goal statements into specification of objects agents, activity and information processes. These link functional decomposition of requirements to object oriented modelling. Implications of the model and supporting tools are briefly reviewed. >

Requirements engineering by example: an empirical study

Abstract: Domain abstraction reuse during requirements engineering is evaluated as a paradigm during use of a research tool. Iterative fact acquisition and abstraction retrieval, supported by example-based explanation of abstractions, are implemented in a prototype known as AIR (adviser for intelligent reuse). Observation of the use of AIRs by inexperienced software engineers reveal the effectiveness of this paradigm despite several problems. These problems are examined so as to identify improvements for future versions of intelligent requirements engineering environments. >