Showing papers by "Royal Holloway, University of London published in 2000"

An Introduction to Support Vector Machines and Other Kernel-based Learning Methods

Abstract: From the publisher: This is the first comprehensive introduction to Support Vector Machines (SVMs), a new generation learning system based on recent advances in statistical learning theory. SVMs deliver state-of-the-art performance in real-world applications such as text categorisation, hand-written character recognition, image classification, biosequences analysis, etc., and are now established as one of the standard tools for machine learning and data mining. Students will find the book both stimulating and accessible, while practitioners will be guided smoothly through the material required for a good grasp of the theory and its applications. The concepts are introduced gradually in accessible and self-contained stages, while the presentation is rigorous and thorough. Pointers to relevant literature and web sites containing software ensure that it forms an ideal starting point for further study. Equally, the book and its associated web site will guide practitioners to updated literature, new applications, and on-line software.

Text Classification using String Kernels

Abstract: We introduce a novel kernel for comparing two text documents. The kernel is an inner product in the feature space consisting of all subsequences of length k. A subsequence is any ordered sequence of k characters occurring in the text though not necessarily contiguously. The subsequences are weighted by an exponentially decaying factor of their full length in the text, hence emphasising those occurrences which are close to contiguous. A direct computation of this feature vector would involve a prohibitive amount of computation even for modest values of k, since the dimension of the feature space grows exponentially with k. The paper describes how despite this fact the inner product can be efficiently evaluated by a dynamic programming technique. A preliminary experimental comparison of the performance of the kernel compared with a standard word feature space kernel [6] is made showing encouraging results.

Feature Selection for SVMs

Abstract: We introduce a method of feature selection for Support Vector Machines. The method is based upon finding those features which minimize bounds on the leave-one-out error. This search can be efficiently performed via gradient descent. The resulting algorithms are shown to be superior to some standard feature selection algorithms on both toy data and real-life problems of face recognition, pedestrian detection and analyzing DNA microarray data.

Temporary Jobs: Stepping Stones or Dead Ends?

Abstract: In Britain about 7% of male employees and 10% of female employees are in temporary jobs. In contrast to much of continental Europe, this proportion has been relatively stable over the 1990s. Using data from the British Household Panel Survey, we find that temporary workers report lower levels of job satisfaction, receive less work-related training, and are less well-paid than their counterparts in permanent employment. However, there is evidence that fixed-term contracts are a stepping stone to permanent work. Women (but not men) who start in fixed-term employment and move to permanent jobs fully catch up to those who start in permanent jobs.

Phenols in the plant and in man. The potential for possible nutritional enhancement of the diet by modifying the phenols content or profile

Abstract: There is growing recognition that many phenolic secondary metabolites present in foodstuffs may possibly exert beneficial effects on human health. This may to some degree be mediated via antioxidant actions, but a range of more specific pharmacological effects have also been proposed. Given this background, there may be favourable consequences for the general health of Western populations as a result of optimising the phenolic content of the diet. This paper reviews what is known of the function of phenolics both in the plant and in man. It also describes current understanding of the biosynthesis of phenolics in plants, with emphasis on where potential controlling steps may exist. Finally, advances in identification and isolation of the genes coding for phenolic biosynthetic enzymes or regulatory proteins are also summarised. Taken together, this information provides a basis for attempts to modify and optimise the phenolic content of food crops, using either conventional plant breeding along with manipulation of agronomic practices, or else the more targeted approaches of modern molecular biology. © 2000 Society of Chemical Industry

Predicting PTSD symptoms in victims of violent crime: The role of shame, anger, and childhood abuse

Abstract: To examine the role of cognitive-affective appraisals and childhood abuse as predictors of crime-related posttraumatic stress disorder (PTSD) symptoms, 157 victims of violent crime were interviewed within 1 month postcrime and 6 months later. Measures within 1 month postcrime included previous physical and sexual abuse in childhood and responses to the current crime, including shame and anger with self and others. When all variables were considered together, shame and anger with others were the only independent predictors of PTSD symptoms at 1 month, and shame was the only independent predictor of PTSD symptoms at 6 months when 1-month symptoms were controlled. The results suggest that both shame and anger play an important role in the phenomenology of crime-related PTSD and that shame makes a contribution to the subsequent course of symptoms. The findings are also consistent with previous evidence for the role of shame as a mediator between childhood abuse and adult psychopathology.

Dominance by birthright: entry of prior radio producers and competitive ramifications in the U.S. television receiver industry

Abstract: The U.S. television receiver industry evolved to be an oligopoly dominated by firms that produced radios prior to TVs. Data on the experience of all U.S. radio manufacturers and on the length of survival and rate of innovation of all U.S. TV entrants are collected to analyze how radio experience influenced entry, firm performance, and the evolution of market structure in the TV industry. Consistent with a model of the evolution of an oligopolistic industry, more experienced radio firms were more likely to enter TV manufacturing, had higher innovation rates, and in turn had greater market shares and longer survival, suggesting that firm capabilities and the evolution of the TV industry's market structure were critically shaped by firms' experience prior to entry. Copyright © 2000 John Wiley & Sons, Ltd.

Elevation of the provitamin A content of transgenic tomato plants.

Abstract: Tomato products are the principal dietary sources of lycopene and major source of beta-carotene, both of which have been shown to benefit human health. To enhance the carotenoid content and profile of tomato fruit, we have produced transgenic lines containing a bacterial carotenoid gene (crtI) encoding the enzyme phytoene desaturase, which converts phytoene into lycopene. Expression of this gene in transgenic tomatoes did not elevate total carotenoid levels. However, the beta-carotene content increased about threefold, up to 45% of the total carotenoid content. Endogenous carotenoid genes were concurrently upregulated, except for phytoene synthase, which was repressed. The alteration in carotenoid content of these plants did not affect growth and development. Levels of noncarotenoid isoprenoids were unchanged in the transformants. The phenotype has been found to be stable and reproducible over at least four generations.

Application of high-performance liquid chromatography with photodiode array detection to the metabolic profiling of plant isoprenoids

Abstract: The application of high-performance liquid chromatography (HPLC) using a C30 reverse-phase stationary matrix has enabled the simultaneous separation of carotenes, xanthophylls, ubiquinones, tocopherols and plastoquinones in a single chromatogram Continuous photodiode array (PDA) detection ensured identification and quantification of compounds upon elution Applications of the method to the characterization of transgenic and mutant tomato varieties with altered isoprenoid content, biochemical screening of Arabidopsis thaliana, and elucidation of the modes of action of bleaching herbicides are described to illustrate the versatility of the procedure

Distribution of Knowledge, Group Network Structure, and Group Performance

Abstract: This study investigates the effect of knowledge distribution and group structure on performance in MBA game teams. We found that group performance was contingent on the distribution of knowledge within the group and networks of social relationships among group members. Studying 39 teams of MBA students in two management simulation games, we found that, in general, groups that had broadly distributed knowledge, i.e., groups made up of members who had general knowledge, outperformed groups that had knowledge concentrated in different members, i.e., groups made up of members who had specialized or both specialized and general knowledge. However, the advantage that the former enjoyed over the latter disappeared when groups of specialists or mixed groups had decentralized network structures.

New Paradigm or Old Myopia? Unsettling the Communicative Turn in Planning Theory:

Abstract: During the last decade or so, many planning theorists have taken a so-called communicative turn, to the point where somiie have declared the emergence of a dominant new paradigm supported by increasing consensus among theorists. We wish to raise a number of broad questions about the communicative paradigm and claims for its theoretical dominance. We point to alternative analytical positions that focus on issues of power, of the state, and of political economy, in ways that are often underplayed in the communicative literature and that demonstrate a healthy diversity in the field. We offer six critical propositions about communicative planning theory as a contribution to the ongoing debates, in theory and practice, about the conitested nature of planning, its practices and effects.

A single-photon detector in the far-infrared range

Abstract: The far-infrared region (wavelengths in the range 10 microm-1 mm) is one of the richest areas of spectroscopic research, encompassing the rotational spectra of molecules and vibrational spectra of solids, liquids and gases. But studies in this spectral region are hampered by the absence of sensitive detectors--despite recent efforts to improve superconducting bolometers, attainable sensitivities are currently far below the level of single-photon detection. This is in marked contrast to the visible and near-infrared regions (wavelengths shorter than about 1.5 microm), in which single-photon counting is possible using photomultiplier tubes. Here we report the detection of single far-infrared photons in the wavelength range 175-210 microm (6.0-7.1 meV), using a single-electron transistor consisting of a semiconductor quantum dot in high magnetic field. We detect, with a time resolution of a millisecond, an incident flux of 0.1 photons per second on an effective detector area of 0.1 mm2--a sensitivity that exceeds previously reported values by a factor of more than 10(4). The sensitivity is a consequence of the unconventional detection mechanism, in which one absorbed photon leads to a current of 10(6)-10(12) electrons through the quantum dot. By contrast, mechanisms of conventional detectors or photon assisted tunnelling in single-electron transistors produce only a few electrons per incident photon.

Cognitive psychology: A student's handbook (4th ed.).

Abstract: Search torrent: cognitive psychology a student's handbook 6th edition torrent (13MB ) cognitive psychology In and Out of the Laboratory 4th Galotti.pdf · More. Cognitive Psychology A Student's Handbook 6th Edition Michael Eysenck Mark Keane. £16.20 Cognitive Psychology 4th Edition/Eysenck & Keane. £1.00. Prentice Hall, 4th edition, 01/02/2015. ISBN-10: 0321919068. ISBN-13: 9780321919069. Cognitive Psychology: A Student's Handbook 7th Edition by Michael.

Fear, helplessness, and horror in posttraumatic stress disorder : Investigating DSM-IV criterion A2 in victims of violent crime

Abstract: A DSM-IV diagnosis of posttraumatic stress disorder (PTSD) required for the first time that individuals must report experiencing intense fear, helplessness, or horror at the time of the trauma. In a longitudinal study of 138 victims of violent crime, we investigated whether reports of intense trauma-related emotions characterized individuals who, after 6 months, met criteria for PTSD according to the DSM-III-R. We found that intense levels of all 3 emotions strongly predicted later PTSD. However, a small number of those who later met DSM-III-R or ICD criteria for PTSD did not report intense emotions at the time of the trauma. They did, however, report high levels of either anger with others or shame.

The evolution of syntactic communication

Abstract: Animal communication is typically non-syntactic, which means that signals refer to whole situations. Human language is syntactic, and signals consist of discrete components that have their own meanings. Syntax is a prerequisite for taking advantage of combinatorics, that is, "making infinite use of finite means. The vast expressive power of human language would be impossible without syntax, and the transition from non-syntactic to syntactic communication was an essential step in the evolution of human language. We aim to understand the evolutionary dynamics of this transition and to analyse how natural selection can guide it. Here we present a model for the population dynamics of language evolution, define the basic reproductive ratio of words and calculate the maximum size of a lexicon. Syntax allows larger repertoires and the possibility to formulate messages that have not been learned beforehand. Nevertheless, according to our model natural selection can only favour the emergence of syntax if the number of required signals exceeds a threshold value. This result might explain why only humans evolved syntactic communication and hence complex language.

Characterization of Bacillus Species Used for Oral Bacteriotherapy and Bacterioprophylaxis of Gastrointestinal Disorders

Abstract: Bacillus subtilis spores are being used for oral bacteriotherapy and bacterioprophylaxis of gastrointestinal disorders in both humans and animals. Since B. subtilis is an aerobic saprophyte, how spores may benefit the gut microbiota is an intriguing question, since other probiotics such as Lactobacillus spp. which colonize the gut are anerobes. As a first step in understanding the potential effects of ingesting spores, we have characterized five commercial products. An extensive biochemical, physiological, and phylogenetic analysis has revealed that four of these products are mislabeled. Moreover, four of these products showed high levels of antibiotic resistance.

Rift deflection, migration, and propagation: Linkage of the Ethiopian and Eastern rifts, Africa

Abstract: The Main Ethiopian and Eastern (Gregory) rifts, sectors of the East African rift system, overlap in a 300-km-wide system of extensional basins that is more than three times the breadth of either rift away from the zone of overlap. The oldest volcanic rocks (Eocene) and possibly the oldest rift basins (Oligocene) of the East African rift system occur in this zone of overlap. The objectives of field, remote sensing, and geochronology (K-Ar and 40 Ar/ 39 Ar) studies in southwestern Ethiopia were to establish a chronology of rifting and volcanism in the zone of overlap, and to correlate stratigraphic sequences with those in the Kenya rift to the south and in the Main Ethiopian rift to the north. Field observations and cross sections show that basins are bounded by steeply dipping faults, stratal dips are <30°, and that extension accommodated by the intrusion of dikes is volumetrically insignificant. Thus, the style of faulting is similar to that elsewhere in East Africa south of the Afar rift. Initial volcanism between ca. 45 and 33 Ma preceded faulting and uplift, except for reactivation of some Mesozoic rift structures near the Sudan-Ethiopia border and in northern Kenya. Extensional basins began to form in late Oligocene time in the Eastern rift, and in early Miocene time in the Main Ethiopian rift. Small degrees of extension and associated volcanism in the broadly rifted zone may have been triggered by extension in the Red Sea, as well as by lithospheric heating above a mantle plume. The anomalous breadth of the zone is a consequence of rift propagation and migration, rather than basin-and-range‐style extension; both the Main Ethiopian rift and Eastern rifts have propagated along north-south lines, and the Eastern rift has migrated ~200 km eastward since late Oligocene time. The distribution of seismicity and Quaternary volcanism suggest that the Eastern and Main Ethiopian rifts are currently linked across a 200-km-wide zone between the Omo and Segen basins.

Massive idiosyncratic exon skipping corrects the nonsense mutation in dystrophic mouse muscle and produces functional revertant fibers by clonal expansion.

Abstract: Conventionally, nonsense mutations within a gene preclude synthesis of a full-length functional protein. Obviation of such a blockage is seen in the mdx mouse, where despite a nonsense mutation in exon 23 of the dystrophin gene, occasional so-called revertant muscle fibers are seen to contain near-normal levels of its protein product. Here, we show that reversion of dystrophin expression in mdx mice muscle involves unprecedented massive loss of up to 30 exons. We detected several alternatively processed transcripts that could account for some of the revertant dystrophins and could not detect genomic deletion from the region commonly skipped in revertant dystrophin. This, together with exon skipping in two noncontiguous regions, favors aberrant splicing as the mechanism for the restoration of dystrophin, but is hard to reconcile with the clonal idiosyncrasy of revertant dystrophins. Revertant dystrophins retain functional domains and mediate plasmalemmal assembly of the dystrophin-associated glycoprotein complex. Physiological function of revertant fibers is demonstrated by the clonal growth of revertant clusters with age, suggesting that revertant dystrophin could be used as a guide to the construction of dystrophin expression vectors for individual gene therapy. The dystrophin gene in the mdx mouse provides a favored system for study of exon skipping associated with nonsense mutations.

Attentional suppression of activity in the human visual cortex.

Abstract: We have used fMRI to examine the nature of the changes that occur in the human visual cortex when an observer attends to a particular location in the visual image. Previous studies have shown that the magnitude of the response to a visual stimulus is increased when the observer attends to the stimulus. We show that, in addition, attention to a particular location results in a widespread suppression of activity levels at all other locations. This suggests that a key mechanism of attentional modulation may be that spontaneous (baseline) levels of neural activity are adjusted in a position-dependent manner across the entire visual field.

Governmentality and rights and responsibilities in urban policy

Abstract: We deploy aspects of Foucault's concept of governmentality to discuss the argument that the recent shift towards a ‘rights and responsibilities' agenda in urban policy is part of broader transformations in the rationalities and techniques of government. Following Rose, we characterise the emergent forms of urban policy as part of ‘advanced liberalism’ or strategies which seek to activate citizens, individually and collectively, to take greater responsibility for their own government. Such strategies are, as Rose notes, seeking to govern through the instrumentalisation of the self-governing properties of the subjects of government themselves in a whole variety of locales. We develop the argument in three parts. The first part justifies the use of a Foucauldian framework in seeking to understand the new political and policy agenda on ‘rights and responsibilities’. In a second part, we investigate the changing nature of governmental rationalities and techniques of governmentality primarily through the contex...