Showing papers by "University of Westminster published in 1996"

Splitting the unit delay [FIR/all pass filters design]

Abstract: A fractional delay filter is a device for bandlimited interpolation between samples. It finds applications in numerous fields of signal processing, including communications, array processing, speech processing, and music technology. We present a comprehensive review of FIR and allpass filter design techniques for bandlimited approximation of a fractional digital delay. Emphasis is on simple and efficient methods that are well suited for fast coefficient update or continuous control of the delay value. Various new approaches are proposed and several examples are provided to illustrate the performance of the methods. We also discuss the implementation complexity of the algorithms. We focus on four applications where fractional delay filters are needed: synchronization of digital modems, incommensurate sampling rate conversion, high-resolution pitch prediction, and sound synthesis of musical instruments.

The Californian ideology

Abstract: A the end of the twentieth century, the long predicted convergence of the media, computing, and telecommunications into hypermedia is finally happening. Once again, capitalism's relentless drive to diversify and intensify the creative powers of human labour is on the verge of qualitatively transforming the way in which we work, play, and live together. By integrating different technologies around common protocols, something is being created which is more than the sum of its parts. When the ability to produce and receive unlimited amounts of information in any form is combined with the reach of the global telephone networks, existing forms of work and leisure can be fundamentally transformed. New industries will be born and current stock market favourites will swept away. At such moments of profound social change, anyone who can offer a simple explanation of what is happening will be listened to with great interest. At this crucial juncture, a loose alliance of writers, hackers, capitalists, and artists from the West Coast of the United States have succeeded in defining a heterogeneous orthodoxy for the coming information age: the Californian Ideology. This new faith has emerged from a bizarre fusion of the cultural bohemianism of San Francisco with the hi-tech industries of

Perception and recognition of normal and negative faces : the role of shape from shading and pigmentation cues

Abstract: A face is surprisingly difficult to recognise when presented in photographic negative, and negation has also been shown to affect simple perceptual judgments about a face. Two possible explanations for this effect are examined. In the shape-from-shading explanation it is argued that negating an image results in an impossible pattern of shading, and that this disrupts the formation of a three-dimensional representation of the surface geometry of the face. In an alternative account for this effect it is suggested that identification errors occur as a consequence of changes to the apparent pigmentation of the face caused by negating the image. Three experiments are reported which are designed to test these explanations by using novel colour-image transformations in which the hue and luminance components of images are independently manipulated. The results of these studies suggest that although changes to the apparent pigmentation of a face might result in identification errors in some situations, the loss of...

Cross-modality priming in stem completion reflects conscious memory, but not voluntary memory.

Abstract: A comparison of incidental and intentional stem-completion tests confirmed that cross-modality priming occurs when performance conforms completely to the retrieval intentionality criterion, indi­ cating involuntary-not voluntary-retrieval in the incidental test. However, an on-line measure of awareness in the incidental test, and a process-dissociation analysis of the intentional test, indicated only within-modality, but not cross-modality, transfer of involuntary retrieval that is unaccompanied by memorial awareness, These results imply that conscious memory should not be equated with vol­ untary retrieval, and unconscious memory should not be equated with involuntary retrieval, because involuntary retrieval can be accompanied by memorial awareness, Incidental perceptual tests of memory typically re­ quire participants to complete or identify an incomplete or degraded external stimulus (e.g., a word stem or a briefly flashed word). Prior study of the intact version of a test item facilitates or "primes" current performance. This priming is characterized as perceptual because it often varies with the degree ofperceptual match between study and test items: In a visual test, for example, priming de­ creases markedly when study is auditory compared to when it is visual (for reviews, see Richardson-Klavehn & Bjork, 1988; Roediger & McDermott, 1993). Such find­ ings, among others, have led to the hypothesis that prim­ ing depends on modality-specific perceptualrepresenta­

Discourse and policy change: The significance of language for housing research

Abstract: The paper reviews a range of epistemological concerns which are pertinent to the study of housing policy. It is divided into four sections: first, a formulation of language as ‘expressive behaviour’ is put forward to show that language is not simply a medium in which ideas and intentions are communicated, rather it is best understood as dynamic and integrally linked to relations of power and dominance. The second section suggests a methodology which can be applied to a study of housing policy and demonstrates with examples how certain words often used in the language of housing are necessarily linked to a wider cultural and ideological milieu. The third section explores how power relationships are manifested through language. To support these arguments the fourth section applies the methodology to examine the content of some key housing terminology ‘expressed’ during the post‐war period in the UK and considers the implications that follow from its usage.

Balanced mechanical forces and microtubule contribution to fibroblast contraction

Abstract: Fibroblast locomotion is thought to generate tractional forces which lead to contraction and reorganisation of collagen in tissue development and repair. A culture force monitor device (CFM) was used to measure changes in force in fibroblast populated collagen lattices, which resulted from cytoskeletal reorganisation by cytochalasin B, colchicine, vinblastine, and taxol. Microfilament disruption abolished contraction forces, microtubule disruption elicited a new peak of contraction, while taxol stabilisation of microtubules produced a gradual fall in measured force across the collagen gel. Based on these measurements, it is suggested that the cell can be viewed as an engineering structure in which residual intracellular forces, from contractile microfilaments, exert compressive loading on microtubular elements. This microtubular structure appears to act as a ''balanced space frame'' (analogous to an aeroplane chassis), maintaining cell shape and consequently storing a residual internal tension (RIT). In dermal fibroblasts this hidden RIT was up to 33% of the measurable force exerted on the collagen gel. Phenotypic differences between space frame organisation and RIT levels could explain site and pathological variations in fibroblast contraction. (C) 1996 Wiley-Liss, Inc.

From environment to sustainability: Surveys and analysis of local agenda 21 process development in UK local authorities

Abstract: Agenda 21 has come to be the most significant outcome of the Rio Summit for local government in the UK and Local Agenda 21 is emerging as the main driver for the development of local policies and programmes for sustainable development. In general, the work is being undertaken by those charged with the development of environmental policy in local authorities. Sustainability is seen as a natural extension of environmental policy work, and survey results presented confirm a gradual emergence of LA21 work from an environmental focus to a strategic approach to issues of environment, economic development, social welfare and accessibility. The level of awareness of LA21 and commitment to it in general terms appear high, but survey results suggest that the full implications of the agenda, particularly those relating to new approaches to partnership, participation and democracy, have not yet been addressed by all authorities. The author suggests that problems of corporatisation of LA21 and its relationshi...

CO2 laser activation of nociceptive and non-nociceptive thermal afferents from hairy and glabrous skin.

Abstract: In 8 healthy subjects we have recorded cerebral evoked potentials and reaction time (RT) to CO2 laser stimulation of the hairy and glabrous skin at low and high stimulus intensities, corresponding to subjective reporting of detection and pain, respectively. At each intensity we were able to identify an evoked potential; the latencies of the major vertex positive (VP) components fell into 2 distinct populations 320 +/- 30 (VP300) and 778 +/- 80 (VP800) which did not differ between stimulation sites. The frequency of the VP300 responses was greatest in the high stimulus conditions and lower in the low stimulus conditions whilst the opposite was true for the VP800 responses. BImodal distributions of RT were seen at both stimulus intensities. In a further group of of 10 subjects we recorded the latency shift of the vertex negativity following proximal and distal stimulation of hairy skin of the left upper limb and derived conduction velocities for the VP300 (13.21 +/- 2.8 m/sec) and VP800 (1.26 +/- 0.29 m/sec) responses. These results suggest that, following CO2 laser stimulation of both hairy and glabrous skin, two different fibre populations are activated. The VP300 responses appear to be related to A delta activation, while the characteristics of the VP800 responses are consistent with activation of thermoreceptors mediated by C fibres.

Moderating binge drinking: it is possible to change behaviour if you plan it in advance

Abstract: Recent theories of enactment suggest that behaviour change is increased by planning how, where, and when to execute a behavioural response. Drawing on these theories, a brief planning intervention was designed and its effectiveness compared to an information-based health promotion programme (control). All participants were given information about the safe limits per drinking occasion and the adverse consequences of binge drinking, and were asked to drink within the safe limits in order to avoid these consequences. In addition, participants in the planning group received an option menu of possible responses for refusing a drink, asked to choose one strategy and specify a time and place in which the chosen strategy would be implemented. The planning intervention group did not differ from the control group on reported likelihood of future binge drinking, nor on levels of past drinking, age and gender. At a 2-week follow-up, members of the planning intervention group reported lower drinking frequency than controls. The implications of prior planning for interventions aimed at reducing alcohol-related harm are discussed.

Digital alias-free signal processing in the GHz frequency range

Abstract: The advanced Information Technology we call Digital Alias-free Signal Processing (DASP) is discussed in this paper to draw attention to the facts that, first, this technique has already reached a considerable degree of maturity so that it can now be used as a widely applicable Digital Signal Processing (DSP) tool and, second, that it is especially competitive in the area of Microwave and Radio Frequency (RF) signal processing. Its utility arises from its applicability to digital processing of signals at frequencies considerably exceeding half of the mean sampling rate, which traditionally limit classical DSP applications.

From Agent Theory to Agent Construction: A Case Study

Abstract: There is a growing body of work that concentrates on theoretical aspects of agents and multi-agent systems, and a complementary body of work concerned with building practical systems. However, the two have typically been unrelated. This gap between the theory and practice of intelligent agents has only relatively recently begun to be addressed. In this paper we describe the construction of an agent simulation environment that is based strongly on a formal theory of agent systems, but which is intended to serve in exactly this way as a basis for practical development. The paper briefly introduces the theory, then describes the system and the simple reactive agents built with it, but most importantly shows how it reflects the theoretical framework and how it facilitates incremental agent design and implementation. Using this example as a case-study, some possibilities for a methodology for the development of agent systems are discussed.

Megalawyering in the global order: The cultural, social and economic transformation of global legal practice

Abstract: (1996). Megalawyering in the global order: The cultural, social and economic transformation of global legal practice. International Journal of the Legal Profession: Vol. 3, The Solicitors' in Transition, pp. 169-214.

A low third order intermodulation amplifier with harmonic feedback circuitry

Abstract: This paper describes a novel technique for reducing the third-order intermodulation product levels in a nonlinear amplifier. This technique is based on feeding the second harmonic signal produced at the output of the amplifier back to its input. Mathematical analysis and computer simulation are presented. The results of the related experiment which gave a measurement of 16 dB reduction in the level of the third order intermodulation is reported.

Flexibility in building use: the technical feasibility of converting redundant offices into flats

Abstract: The potential for converting empty offices into housing depends upon demands for converted space, the ability to finance conversions and attitudes of owners of empty buildings, together with flexibility in planning and ability to overcome technical constraints. This article explains the reasons for the large stock of redundant office buildings in the UK and questions whether some of these can be converted to provide much needed affordable housing. Technical constraints on their own are rarely insurmountable but the cost of making necessary changes may often be higher than other options of demolition and new building. Case studies of converted buildings show that it is necessary for project managers to deal with a range of issues from planning, location and finance to the accurate assessment of technical criteria in order for successful outcomes. It has often been difficult to find sites where all the necessary variables coincide in a positive manner and for this reason, the conversion of offices into flat...

The Translator Investigated

Abstract: Studies conducted within the framework of the newly-established field of translation process analysis have drawn heavily on introspection as a methodology for investigating the mental processes involved in translation. The data emerging from such studies differ widely, however, in their focus, their scope and their applicability to specific purposes. This paper surveys the process studies carried out to date and, in the light of the limitations on introspective data, explores what studies of this kind have to offer translation theorists, teachers or trainers of translators, as well as translators themselves. It suggests in particular that more - and more differentiated - work with professional translators is now needed to inform the vocational postgraduate courses for translators that the profession is increasingly demanding.

Reconceptualizing Anarchy:: Structural Realism Meets World History

Abstract: How can the understandings of world historians about the critical changes in the international system be brought into harmony with the way IR theorists think about system change? One of the main ob...

Secretory immunoglobulin A and cardiovascular responses to acute psychological challenge.

Abstract: Cardiovascular activity and secretory immunoglobulin A (sIgA) in saliva were recorded at rest, during a 30-min computer game task, and during subsequent recovery. Blood pressure (BP) rose and remained elevated during the task and returned to resting levels during recovery. This pressor response was produced by increased total peripheral resistance rather than increased cardiac output. SIgA secretion rate also increased during the task, although the effect proved significant only toward the end of the task. As such, the data provide preliminary indication that sIgA is sensitive to acute psychological challenge in the laboratory. Although correlational analyses revealed that sIgA reactions were stable, they were not significantly correlated with pressor reactions. The influence of task uncertainty was explored by comparing individuals who had previously played the computer game with those who had not. Task-induced increases in BP and sIgA were a feature of individuals new to the computer game. In contrast to these novice players, experienced players showed minimal increases in BP and no increases in sIgA.

Mycelium-bound lipase from a locally isolated strain of Aspergillus flavus link: pattern and factors involved in its production

Abstract: Aspergillus flavus produces a lipase (EC 3.1.1.3) which is partly bound to the mycelium during growth. The production of the mycelium-bound lipase is concomitant with growth, and declines when growth ceases. Maximum productivity of the enzyme is obtained when the culture is incubated at 30°C, an initial culture pH of 6·5 and with 2% (w/v) each of corn oil and yeast extract as carbon and organic nitrogen source. Yeast extract affects not only the production of lipase but also the secretion of proteases into the culture medium. Production of the latter enzymes, which inactivate the free lipase, is enhanced by adding yeast extract (1–2%, w/v) to the culture medium. However, at 5% (w/v) yeast extract concentration, proteolytic activity is not detected and consequently, the activity of free lipase may easily be measured. Free lipase activity can easily be detected when 0·001 mol dm−3 EDTA is added to the culture medium. The presence of the chelating agent enhances the production and maintains the stability of the extracted mycelium-bound lipase.

Review Oligosaccharide Synthesis Using Glycosidases

Abstract: A wide range of strategies may be considered for the synthesis of oligosaccharides in vitro using enzymes, all of which present significant challenges to the enzyme technologist. Many simple oligosaccharides may be produced by the hydrolysis of readily-available polysaccharides using specific enzymes. However, to produce the complex branched hetero-oligosaccharides of the types which occur N-linked to glycoproteins is more taxing. Materials of this type may be synthesised using the natural synthetic enzymes which employ sugar nucleotides as substrates. These enzymes are highly specific but they are costly to use due to their instability and to the cost of their substrates. It has been demonstrated that glycosidases are capable of synthesising hetero-oligosaccharides when provided with underivatised sugars in conditions of low water activity but that the specificity of synthetic reactions is apparently not high and that yields of material are low. Approaches to these problems are discussed, including the use of immobilised enzymes in packed-bed reactors to allow the ‘ping’ stage of the synthetic reaction to be separated in time from the ‘pong’ stage, and the application of aqueous two-phase systems which may be ‘tailored’ to separate the enzyme and the substrates from the final product. The ability to synthesise a range of oligosaccharides is dependent on the availability of appropriate glycosidases with differing specificities. There is a clear importance of ‘biodiversity’ in providing knowledge of sources of these.

Formalising the contract net as a goal-directed system

Abstract: In response to the problems that have arisen regarding the terminology and concepts of agent-oriented systems, previous work has described a formal framework for understanding agency and autonomy. In this paper we outline the framework and refine it by adding further levels of detail to develop a formal model of the Contract Net Protocol. The model serves to make precise both the operations of nodes in the contract net, and the state of the net at various points during the protocol. In particular, the nature of the dependencies between the nodes in the net is explicated. Finally, we generalise the relationships that can be found in the contract net which are brought out by the formalisation, and introduce more general concepts such as cooperation and engagement.

Information and telecommunication technologies as a strategic tool for tourism enhancement at destination regions

Abstract: Developments in information and telecommunication technologies (ITs) have great implications for business practices and strategies. As tourism is an information intensive industry, it receives a wide range of effects which gradually re-engineer business processes and originate a paradigm-shift in best management practices. Computerised networks change the formulation and distribution methods of global tourism products, and consequently create both opportunities and threats for principals and destinations. The Global Distribution Systems (GDSs) are the most influential ITs applications as they facilitate the distribution and delivery of seamless tourism products. Although peripheral regions and small & medium-sized tourism enterprises (SMTEs) dominate the global tourism industry, they are often disregarded by GDSs, due to their strategic weaknesses and technological incapabilities. Hence, the Destination Integrated Computer Information Reservation Management System concept is proposed as a platform for diagonal economic, social, cultural and environmental integration at the destination level. This paper draws upon an extensive field research throughout the distribution channel of tourism, and aims to investigate DICIRMSs as strategic tools for the long term prosperity of SMTEs and destinations.

φ20, A Temperate Bacteriophage Isolated from Bacillus anthracis Exists as a Plasmidial Prophage

Abstract: This study describes the isolation of temperate B. anthracis phages, from 4 out of 20 B. anthracis strains screened, by use of the inducing agents mitomycin C and UV light. Phage φ20 isolated from B. anthracis Sterne 34F2 (pXO1+ pXO2−) was shown to have double-stranded DNA of size 48756 bp and a restriction site map showing nine sites for enzymes BamHI, BglII, and SstI is included. The φ20 genome was found to exist as a plasmidial prophage and the phage itself to have a polyhedral head of diameter 65 nm and tail 217 nm long and 15 nm wide.

The window of vulnerability and its effect on relative parasitoid abundance

Abstract: Summary. 1. The length of time that a gall-forming midge, Rhopalomyia califomica, was vulnerable to attack by four parasitoid species was measured in the field at two locations. 2. The midge had a restricted window of vulnerability to each of the parasitoid species, but similar windows of vulnerability were found at the two sites. 3. A stage-structured model was used to illustrate that the length of the vulnerable window should have no effect on the fraction parasitized by a single parasitoid species if that species is the only parasitoid attacking the host in a coupled host-parasitoid interaction. However, the length of the window of vulnerability can have a positive effect on the fraction parasitized by a species in competition with other parasitoid species. 4. The length of the window of vulnerability can help explain the relative field abundance of four of the common parasitoid species of R.californica.

Analysis of algorithms for nonuniform-time discrete Fourier transform

Abstract: In order to perform spectral analysis of nonuniformly sampled time domain signals, algorithms for the Nonuniform-Time Discrete Fourier Transform (NUT-DFT) are developed and evaluated The NUT-DFT takes nonuniform time domain data and produces a uniform sampled spectrum. The proposed algorithms for NUT-DFT are based on approximating the continuous-time Fourier transform by different numerical integration algorithms. Special attention is paid to the ability of the transform to capture signals with frequency components above half the average sampling rate. The performance of the algorithms is studied experimentally by analysing both nonuniformly and uniformly sampled data.