Showing papers by "City University London published in 1994"
TL;DR: It is shown that the search for general software complexity measures is doomed to failure and the theory does help to define and validate measures of specific complexity attributes, and is able to view software measurement in a very wide perspective.
Abstract: Software measurement, like measurement in any other discipline, must adhere to the science of measurement if it is to gain widespread acceptance and validity. The observation of some very simple, but fundamental, principles of measurement can have an extremely beneficial effect on the subject. Measurement theory is used to highlight both weaknesses and strengths of software metrics work, including work on metrics validation. We identify a problem with the well-known Weyuker properties (E.J. Weyuker, 1988), but also show that a criticism of these properties by J.C. Cherniavsky and C.H. Smith (1991) is invalid. We show that the search for general software complexity measures is doomed to failure. However, the theory does help us to define and validate measures of specific complexity attributes. Above all, we are able to view software measurement in a very wide perspective, rationalising and relating its many diverse activities. >
544 citations
TL;DR: Three new methods of determining Littmann's factor q become available: simply reducing the axial length by a constant 1 · 82 mm; constructing a personalized schematic eye, given additional data; and ray tracing through this eye to extend calculations to peripheral retinal areas.
Abstract: Littmann's formula relating the size of a retinal feature to its measured image size on a telecentric fundus camera film is widely used. It requires only the corneal radius, ametropia, and Littmann's factor q obtained from nomograms or tables. These procedures are here computerized for practitioners' convenience. Basic optical principles are discussed, showing q to be a constant fraction of the theoretical ocular dimension k′, the distance from the eye's second principal point to the retina. If the eye's axial length is known, three new methods of determining q become available: (a) simply reducing the axial length by a constant 1 · 82 mm; (b) constructing a personalized schematic eye, given additional data; (c) ray tracing through this eye to extend calculations to peripheral retinal areas. Results of all these evaluations for 12 subjects of known ocular dimensions are presented for comparison. Method (a), the simplest, is arguably the most reliable. It shows good agreement with Littmann's supplementary procedure when the eye's axial length is known.
516 citations
TL;DR: In this article, a theoretical analysis of the self-mixing interference produced by an external optical feedback is found to be due to the variations in the threshold gain and in the spectral distribution of the laser output.
Abstract: This paper presents a theoretical analysis and a comparison with experimental results on self-mixing interference inside a single-longitudinal-mode diode laser. A theoretical model, based on the steady-state equations of the lasing condition in a Fabry-Perot type laser cavity, is described, and through it a satisfactory analysis of self-mixing interference for optical sensing applications is given. In this work, the self-mixing interference produced by an external optical feedback is found to be due to the variations in the threshold gain and in the spectral distribution of the laser output. The gain variation results in an optical intensity modulation, and the spectral variation determines both the modulation waveform and the coherence properties of the interference. The theoretical analysis of the self-mixing interference is seen to yield a simulation of the laser power modulation which is in good agreement with the experiment results reported. >
310 citations
TL;DR: This work suggests several ways to address the problem of software development and maintenance with new practices whose effectiveness is rarely, if ever, backed up by hard evidence.
Abstract: For 25 years, software researchers have proposed improving software development and maintenance with new practices whose effectiveness is rarely, if ever, backed up by hard evidence. We suggest several ways to address the problem, and we challenge the community to invest in being more scientific. >
293 citations
TL;DR: In this paper, the structure of two variations on the Temperley-Lieb algebra, both used for dealing with special kinds of boundary conditions in statistical mechanics models, is determined. But the analysis is restricted to the blob algebra.
Abstract: We determine the structure of two variations on the Temperley-Lieb algebra, both used for dealing with special kinds of boundary conditions in statistical mechanics models. The first is a new algebra, the ‘blob’ algebra. We determine both the generic and all the exceptional structures for this two parameter algebra. The second is the periodic Temperley-Lieb algebra. The generic structure and part of the exceptional structure of this algebra have already been studied. We complete the analysis using results from the study of the blob algebra.
242 citations
TL;DR: A high proportion of these autistic subjects were reported to have current difficulties with personal pronouns in their everyday life, and some alternative interpretations of the results are discussed.
Abstract: The nature of autistic individuals' abnormalities in the use of personal pronouns has been a topic of considerable speculation but little systematic investigation. We tested groups of CA- and verbal MA-matched autistic and nonautistic mentally retarded children and young adults on a series of tasks that involved the comprehension and use of the personal pronouns "I," "you," and "me." All subjects were able to comprehend these pronouns within the test situations, and there were few instances of pronoun reversal. However, autistic subjects were significantly less likely to employ the pronoun "me" in a visual perspective-taking task (when instead they tended to say: 'I can see the . . .'), and lower ability subjects were more likely to use their own proper names rather than personal pronouns in certain photograph-naming tasks. There were also circumstances in which autistic subjects were less likely than controls to employ the pronoun "you" to refer to the experimenter. A high proportion of these autistic subjects were reported to have current difficulties with personal pronouns in their everyday life, and we discuss some alternative interpretations of the results.
216 citations
TL;DR: In this article, the use of a previously presented general criterion of failure for high cycle multiaxial fatigue, τa/tA,B+σn.max/2σT= 1, is extended to cases where the shear and normal stress on the critical plane are non-proportional and also to give life predictions in the range of 104 to 106 cycles.
Abstract: — The use of a previously presented general criterion of failure for high cycle multiaxial fatigue, τa/tA,B+σn.max/2σT= 1, is extended to cases where the shear and normal stress on the critical plane are non-proportional and also to give life predictions in the range of 104 to 106 cycles. The criterion takes account of whether case A cracks, growing along the surface, or case B cracks, growing in from the surface, occur.
191 citations
06 Oct 1994
TL;DR: The research described in this paper describes aspects of target recognition, thresholding, and location, and the results of a series of simulation experiments are used to analyze the performance of subpixel target location techniques such as: centroiding; Gaussian shape fitting; and ellipse fitting, under varying conditions.
Abstract: Signalizing points of interest on the object to be measured is a reliable and common method of achieving optimum target location accuracy for many high precision measurement tasks. In photogrammetric metrology, images of the targets originate from photographs and CCD cameras. Regardless of whether the photographs are scanned or the digital images are captured directly, the overall accuracy of the technique is partly dependent on the precise and accurate location of the target images. However, it is often not clear which technique to choose for a particular task, or what are the significant sources of error. The research described in this paper describes aspects of target recognition, thresholding, and location. The results of a series of simulation experiments are used to analyze the performance of subpixel target location techniques such as: centroiding; Gaussian shape fitting; and ellipse fitting, under varying conditions.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
173 citations
TL;DR: In a directed-forgetting paradigm, each word in a study list was followed by a cue designating that word as eitherlearn orforget, and there were more remember responses after the short cue delay; cue delay influenced know responses, regardless of word designation.
Abstract: In a directed-forgetting paradigm, each word in a study list was followed by a cue designating that word as eitherlearn orforget. This cue appeared after either a short or a long delay. It was assumed that a long delay would increase maintenance rehearsal of all the words, and that only the words followed by a learn cue would be rehearsed elaboratively. Moreover, because the interval between the words was constant, a short cue delay should allow more time for elaborative rehearsal. In a subsequent test, subjects maderemember orknow responses to indicate whether recognition of each word was accompanied by conscious recollection or by feelings of familiarity in the absence of conscious recollection. The hypothesis was that remembering depends on elaborative rehearsal, and knowing depends on maintenance rehearsal. In accord with this hypothesis, the learn-versus-forget designation influenced remember but not know responses, and there were more remember responses after the short cue delay; cue delay influenced know responses, regardless of word designation.
153 citations
TL;DR: A model of carbohydrate metabolism has been implemented as a causal probabilistic network, allowing explicit representation of the uncertainties involved in the prediction of 24-h blood glucose profiles in insulin-dependent diabetic subjects, and in several cases seemed more appropriate than the doses actually administered to the patients.
151 citations
TL;DR: It is argued that the two encoding activities produced approximately equivalent involuntary influences of memory, but that items encoded semantically were associated with involuntary conscious memory to a greater extent than were items encoded graphemically.
Abstract: Priming in an indirect test of stem completion should reflect involuntary memory, but can be accompanied by conscious awareness of the past (involuntary conscious memory) or unaccompanied by such awareness (involuntary unconscious memory). We adapted the method of opposition developed by Jacoby, Woloshyn, and Kelley (1989) to obtain a measure of stem-completion priming that should reflect only involuntary unconscious memory. Subjects completed stems with the first word coming to mind, but wrote down a different word if the word that came to mind first had been previously encountered. Facilitatory priming was expected only when involuntary unconscious influences outweighed inhibitory effects of involuntary conscious memory, or of intentional retrieval. We observed a facilitation effect for items processed graphemically at encoding, in conjunction with an inhibition effect for items processed semantically at encoding. In contrast, a standard indirect test showed similar levels of priming following ...
TL;DR: The results are consistent with the belief that worrying is primarily an anxiety-related phenomenon with any problem-solving deficits occurring at the level of solution implementation rather than solution generation.
TL;DR: The results suggest that chromatic signals are processed independently to generate perceived object colour or to construct spatially structured objects, and that these functions involve different neural substrates.
Abstract: A new method that allows controlled masking of luminance contrast has been developed to study the use of chromatic signals in human vision. The method also makes it possible to examine the different uses of chromatic signals (e.g. the generation of perceived colour, or the construction and representation of object structure and form). By using this technique, we studied the threshold detection of chromatic signals in normal trichromats. The results show that chromatic signals are virtually unaffected by ongoing, randomly varying, luminance contrast changes. These findings suggest that chromatic signals are either processed independently or can be separated completely from any confounding luminance contrast components in the stimulus. Thresholds for detection of colour changes only, and for extraction of stimulus structure from chromatic signals in normal trichromats, in subjects with single cone receptor deficiency (i.e. dichromats) and in three subjects with abnormal colour vision caused by bilateral damage to ventromedial, extra-striate visual cortex (i.e. subjects with cerebral achromatopsia) have also been measured. No significant difference in thresholds for the two conditions was observed either in normal trichromats or in dichromats. Subjects with cerebral achromatopsia, however, reveal markedly different thresholds. The results suggest that chromatic signals are processed independently to generate perceived object colour or to construct spatially structured objects, and that these functions involve different neural substrates. The results help to explain, at least in part, why cerebral achromatopsia is a heterogeneous disorder, and why there can be significant differences in the effective use of chromatic signals in subjects described as cerebral achromatopsics.
TL;DR: Low birth weight is associated with socioeconomic disadvantage in childhood and adolescence and studies of the association of indicators of early development and adult disease need to take into account experiences right through from birth to adulthood.
Abstract: Objective: To investigate the relation between birth weight and socioeconomic disadvantage during childhood and adolescence in a birth cohort study. Design: Longitudinal analysis of birth weight in relation to social class, household amenities and overcrowding, and financial difficulties as reported by parents at interview when participants were aged 7, 11, and 16 years; and receipt of unemployment or supplementary benefits as reported by participants at age 23. Subjects: Male participants in the 1958 birth cohort (national child development study) born to parents resident in Great Britain during the week of 3-9 March 1958. Data on birth weight and financial difficulties between birth and 23 years were available for 4321; data on housing conditions and social class at ages 7, 11, and 16 years were available for 3370. Main outcome measures: Socioeconomic disadvantage at later ages in men weighing 6 lb (2721g) or under at birth compared with those weighing over 6 lb and between fifths of the distribution of birth weight. Results: Cohort members who weighed 6 lb or under at birth were more likely to experience socioeconomic disadvantage subsequently. Those in lower fifths of the distribution were more likely to experience socioeconomic disadvantage. Conclusion—Low birth weight is associated with socioeconomic disadvantage in childhood and adolescence. Studies of the association of indicators of early development and adult disease need to take into account experiences right through from birth to adulthood if they are to elucidate the combination of risks attributable to developmental problems and socioeconomic disadvantage.
TL;DR: Fear of animals in the fear-relevant category was significantly associated with scores on the obsessive washing sub-scale of the Maudsley Obsessive-Compulsive Inventory, but was not associated with obsessive behaviour in general.
TL;DR: This paper investigated the effects of varying the correspondence between presentation and test modes on states of conscious awareness in recognition memory and found that auditory and visual study modes differentially affected recollective experience and feelings of familiarity assessed by “remember” and “know” responses accompanying recognition.
Abstract: Two experiments investigated the effects of varying the correspondence between presentation and test modes on states of conscious awareness in recognition memory. Experiment 1 used visual test items and showed that auditory and visual study modes differentially affected recollective experience and feelings of familiarity assessed by “remember” and “know” responses accompanying recognition: “know” responses were slightly enhanced following visual presentation, but this was largely offset by a similarly small increase in “remember” responses. Experiment 2 employed conditions designed to maximise any effect on “know” responses of the correspondence between presentation and test modes by using a highly perceptual orienting task at study. Under these conditions, there was a large mode correspondence effect on “know” responses. The results support the idea that “know” responses are particularly sensitive to perceptual factors.
TL;DR: Results show a relationship between knowledge and attitude but no relationship between either of these and the nursing practice scale, and suggest that nursing practice and knowledge are weakly related.
Abstract: Issues concerning sex and sexuality are relevant to nursing practice. The objective of this study was to determine the relationship between knowledge of and attitude towards sexuality, and nursing practice. Nursing practice in this case was defined as the discussion of sexuality with the patient, with particular reference to taking a sexual history on admission to the ward. A multi-choice questionnaire with sections establishing demographic details and nursing practice, and including the Sex, Knowledge and Attitude Test (SKAT), was administered to 357 registered general nurses (RGNs). Results show a relationship between knowledge and attitude but no relationship between either of these and the nursing practice scale. However, a slight but significant correlation between receiving teaching about sexual history taking and questioning patients about sexuality on admission suggests that nursing practice and knowledge are weakly related. There is evidence that factors other than those within the scope of this study influence all three independent variables, and these are discussed. The implications of the study suggest the need for an improvement in nurse education regarding sexuality at all stages of training.
TL;DR: Until appropriate procedural and statistical comparisons are made, it is concluded that it is premature to assume that EC represents a form of conditioning that is theoretically distinct from other types of classical conditioning.
TL;DR: This article found that political disaffection including lack of interest and intention not to vote, is strongly associated with a growing cynicism about politics rooted in poor educational performance and a working class family background.
Abstract: The antecedents of political disaffection and political activism have been extensively studied in adult populations, producing two models of political protest, the ‘dissatisfaction model’, suggesting that protest action is rooted in political disaffection, and the ‘resource model’ which bases interest in politics in a sense of political self-efficacy. There has been a dearth of research extending this theorizing to young people of prevoting age. The present study presents the results of regression analysis applied to longitudinal data collected in a U.K. Programme of research and economic and political socialization, the ESRC 16-19 Initiative. The analysis relates ‘lack of interest in politics’, ‘intention not to vote’ and ‘political activity’, to attitudes, personality characteristics, experience and circumstances measured earlier. It is concluded that political disaffection including lack of interest and intention not to vote, is strongly associated with a growing cynicism about politics rooted in poor educational performance and a working class family background. The connections with activism are negative but much weaker, suggesting the potential for protest activity across a wider spectrum of youth. This lends support to Marsh's (1990) view that given the right circumstances, protest action under both the ‘resource model’, and the ‘dissatisfaction model’, can apply.
TL;DR: Byng et al. as discussed by the authors replicated and extended an earlier study in which a therapy program was carried out with two agrammatic aphasic patients with sentence processing impairments suggested to be at the level of mapping thematic roles and grammatical relations.
Abstract: This study was designed to replicate and extend an earlier study in which a therapy programme was carried out with two agrammatic aphasic patients with sentence processing impairments suggested to be at the level of mapping thematic roles and grammatical relations (Byng 1988). In the current study one of the therapy procedures implemented in the previous study was repeated with three different people with long-term ‘agrammatism’. The outcome of the therapy resulted in some gains in sentence production and verb retrieval, but these gains varied across the three patients. Whilst some change had taken place for each person, the pattern of results showed that the quality and extent of the change was different in each case. The potential source for these differences is explored and the implications of the study for the necessary development of theories about therapy are discussed.
TL;DR: In this article, the notion of generic timbre has been defined as the attribution of spectromorphological identity, and transformational and typological discourse have been defined, leading to the concept of generic generative timbre.
Abstract: Timbre is defined as the attribution of spectromorphological identity. Electroacoustic music experience, particularly acousmatic music, questions the viability of a notion of timbre. Of primary significance is the traditional linking of timbre to the source and cause of a sound: the concept of source-cause texture is introduced to define this link. The ambiguous relationship between pitch and timbre indicates that timbre cannot be defined as that part of the sound which is not pitch. Problems in establishing the existence of sonic identities within the musical context, and of maintaining the coherence of identities are discussed, opening up questions relating to musical discourse. Two types of discourse — transformational and typological — are defined, leading to the notion of generic timbre. In a spectromorphological music where defining identities becomes problematic it becomes impossible to disentangle timbre from discourse: here the notion of timbre has a limited viability.
Journal Article•
TL;DR: The authors discusses five indicators of competitiveness: real exchange rates based on consumer price indices, export unit values of manufacturing goods, relative price of traded to nontraded goods, normalized unit labor costs in manufacturing, and the ratio of normalized unit labour costs to value-added deflators in manufacturing.
Abstract: This paper discusses five indicators of competitiveness: real exchange rates based on consumer price indices, export unit values of manufacturing goods, the relative price of traded to nontraded goods, normalized unit labor costs in manufacturing, and the ratio of normalized unit labor costs to value-added deflators in manufacturing. It discusses how each of these measures is associated with changes in a country`s balance of trade in goods and nonfactor services and examines the relationship among these indicators. It then examines the empirical performance of three of the indicators in terms of their ability to explain trade flows.
TL;DR: This article describes how the practicality of the Smartie framework was verified by testing it with corporate partners and hopes it will enable the identification of standards whose use is most likely to lead to improvements in some aspect of software development processes and products.
Abstract: The authors report on the results of the Smartie project (Standards and Methods Assessment Using Rigorous Techniques in Industrial Environments), a collaborative effort to propose a widely applicable procedure for the objective assessment of standards used in software development. We hope that, for a given environment and application area, Smartie will enable the identification of standards whose use is most likely to lead to improvements in some aspect of software development processes and products. In this article, we describe how we verified the practicality of the Smartie framework by testing it with corporate partners. >
TL;DR: It is found that the physiological model could only be parameterized for data from 24 (80%) of the 30 patients in the study, and comparison of observed and predicted blood glucose data from these 24 patients over a period of 5-6 days following parameter estimation revealed a mean (+/- SD) root mean square deviation between measured and simulated blood glucose values.
TL;DR: The paper discusses similarities between reliability and security with the intention of working toward measures of "operational security" similar to those that the authors have for reliability of systems, which raises several issues which invite empirical investigation.
Abstract: Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of "the ability of the system to resist attack." That is, it should be operational, reflecting the degree to which the system can be expected to remain free of security breaches under particular conditions of operation (including attack). Instead, current security levels at best merely reflect the extensiveness of safeguards introduced during the design and development of a system. Whilst we might expect a system developed to a higher level than another to exhibit "more secure behavior" in operation, this cannot be guaranteed; more particularly, we cannot infer what the actual security behavior will be from knowledge of such a level. In the paper we discuss similarities between reliability and security with the intention of working toward measures of "operational security" similar to those that we have for reliability of systems. Very informally, these measures could involve expressions such as the rate of occurrence of security breaches, or the probability that a specified "mission" can be accomplished without a security breach. This new approach is based on the analogy between system failure and security breach, but it raises several issues which invite empirical investigation. We briefly describe a pilot experiment that we have conducted to judge the feasibility of collecting data to examine these issues. >
TL;DR: It is demonstrated that two approaches may be adopted in time series analysis of blood glucose data: an intuitive approach, manipulating symbolic representations of the data, and formal time series methods which decompose the series into clinically related components.
TL;DR: Psychophysical experiments carried out on a subject clinically blind in half of his visual field caused by striate cortex damage reveal the existence of two distinct channels mediating residual vision, one responds to spatial structure and the other to light flux changes.
Abstract: Residual vision in subjects with damage of the primary visual cortex (striate cortex) has been demonstrated in many previous studies and is taken to reflect the properties of known subcortical and extrastriate visual pathways. In this report we describe psychophysical experiments carried out on a subject clinically blind in half of his visual field (i.e. homonymous hemianopia) caused by striate cortex damage. They reveal the existence of two distinct channels mediating such vision. One channel responds to spatial structure and the other to light flux changes. The spatially tuned channel has a peak response at about 1.2 cycles per degree and shows rapid loss of sensitivity at both high and low spatial frequencies. This channel does not respond to diffuse illumination. The light flux channel, however, responds only to sudden increments in light flux levels on the retina and shows extensive spatial summation. Both channels require transient inputs, with a peak sensitivity at about 10 cycles per second and show virtually complete attenuation at temporal frequencies below 2 cycles per second. The spatiotemporal characteristics of these two channels account for much of the reported limits of visual performance attributed to subcortical or extrastriate pathways in some patients, and especially for their relatively good sensitivity for the detection of abrupt, transient stimuli or fast-moving targets. A new method is also applied to the measurement of the amount of light scatter in the eye. The measurements show that light scatter into the sighted hemifield could not account for the results obtained with the stimuli used to characterized the residual vision of this subject.
TL;DR: Using some of the data collected by Joe Daniels while in hospital, it is demonstrated how AIDA might be applied either in a clinical setting to provide therapeutic advice or in an educational setting to interactively teach diabetic patients about their diabetes and educate them to adjust their own insulin injections and diet.
TL;DR: In this article, a numerical analysis of the three-dimensional flow field generated by pitched and skewed air jets issuing into an otherwise undisturbed turbulent boundary layer is presented, and it is demonstrated that each such jet produces a single strong longitudinal vortex.
Abstract: Numerical calculations of the three-dimensional flowfield generated by pitched and skewed air jets issuing into an otherwise undisturbed turbulent boundary layer are presented. It is demonstrated that each such jet produces a single strong longitudinal vortex. The strength of the vortex, as inferred from its effect on the development of skin friction, is shown to be influenced by pitch and skew angles, exit velocity, and downstream distance in ways which accord with published experimental results. The calculated beneficial effect that the longitudinal vortices have on the development of skin friction in an adverse pressure gradient demonstrates the mechanism by which vortex generators delay boundary-layer separation. It follows that the numerical model could be used to optimize arrays of air-jet vortex generators. Furthermore, the facility to quantify the interaction between the vortex and the boundary layer should also be valuable in the application of vane vortex generators, and possible even more generally. 18 refs.