27 resultados para Positive definite kernels and functions
em Aston University Research Archive
Resumo:
This study was concerned with the structure, functions and development, especially the performance, of some rural small firms associated with the Council for Small Industries in Rural Areas (C?SIRA) of England. Forty firms were used as the main basis of analysis. For some aspects of the investigation, however, data from another 54 firms, obtained indirectly through nine CoSIRA Organisers, were also used. For performance-analysis, the 40 firms were firstly ranked according to their growth and profitability rates which were calculated from their financial data. Then each of the variables hypothesised to be related to performance was tested to ascertain its relationship with performance, using the Spearman's Rank Correlation technique. The analysis indicated that each of the four factors .. the principal, the firm itself, its management, and the environment - had a bearing upon the performance of the firm. Within the first factor, the owner-manager's background and attitudes were found to be most important; in the second, the firm's size, age and scope of activities were also found to be correlated with performance; with respect to the third, it was revealed that firms which practised some forms of systems in planning, control and costing performed better than those which did not and, finally with respect to the fourth factor, it was found that some of the services provided by CoSIRA, especially credit finance, were facilitative to the firm's performance. Another significant facet of the firms highlighted by the study was their multifarious roles. These, meeting economic, psychological, sociological and political needs, were considered to be most useful to man and his society. Finally, the study has added light to the structural characteristics of the sampled firms, including various aspects of their development, orientation and organisation, as well as their various structural strengths and weakness. ' .
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There is a proliferation of categorization schemes in the scientific literature that have mostly been developed from psychologists’ understanding of the nature of linguistic interactions. This has a led to problems in defining question types used by interviewers. Based on the principle that the overarching purpose of an interview is to elicit information and that questions can function both as actions in their own right and as vehicles for other actions, a Conversational Analysis approach was used to analyse a small number of police interviews. The analysis produced a different categorization of question types and, in particular, the conversational turns fell into two functional types: (i) Topic Initiation Questions and (ii) Topic Facilitation Questions. We argue that forensic interviewing requires a switch of focus from the ‘words’ used by interviewers in question types to the ‘function’ of conversational turns within interviews.
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The assessment of the reliability of systems which learn from data is a key issue to investigate thoroughly before the actual application of information processing techniques to real-world problems. Over the recent years Gaussian processes and Bayesian neural networks have come to the fore and in this thesis their generalisation capabilities are analysed from theoretical and empirical perspectives. Upper and lower bounds on the learning curve of Gaussian processes are investigated in order to estimate the amount of data required to guarantee a certain level of generalisation performance. In this thesis we analyse the effects on the bounds and the learning curve induced by the smoothness of stochastic processes described by four different covariance functions. We also explain the early, linearly-decreasing behaviour of the curves and we investigate the asymptotic behaviour of the upper bounds. The effect of the noise and the characteristic lengthscale of the stochastic process on the tightness of the bounds are also discussed. The analysis is supported by several numerical simulations. The generalisation error of a Gaussian process is affected by the dimension of the input vector and may be decreased by input-variable reduction techniques. In conventional approaches to Gaussian process regression, the positive definite matrix estimating the distance between input points is often taken diagonal. In this thesis we show that a general distance matrix is able to estimate the effective dimensionality of the regression problem as well as to discover the linear transformation from the manifest variables to the hidden-feature space, with a significant reduction of the input dimension. Numerical simulations confirm the significant superiority of the general distance matrix with respect to the diagonal one.In the thesis we also present an empirical investigation of the generalisation errors of neural networks trained by two Bayesian algorithms, the Markov Chain Monte Carlo method and the evidence framework; the neural networks have been trained on the task of labelling segmented outdoor images.
Resumo:
This work reports the developnent of a mathenatical model and distributed, multi variable computer-control for a pilot plant double-effect climbing-film evaporator. A distributed-parameter model of the plant has been developed and the time-domain model transformed into the Laplace domain. The model has been further transformed into an integral domain conforming to an algebraic ring of polynomials, to eliminate the transcendental terms which arise in the Laplace domain due to the distributed nature of the plant model. This has made possible the application of linear control theories to a set of linear-partial differential equations. The models obtained have well tracked the experimental results of the plant. A distributed-computer network has been interfaced with the plant to implement digital controllers in a hierarchical structure. A modern rnultivariable Wiener-Hopf controller has been applled to the plant model. The application has revealed a limitation condition that the plant matrix should be positive-definite along the infinite frequency axis. A new multi variable control theory has emerged fram this study, which avoids the above limitation. The controller has the structure of the modern Wiener-Hopf controller, but with a unique feature enabling a designer to specify the closed-loop poles in advance and to shape the sensitivity matrix as required. In this way, the method treats directly the interaction problems found in the chemical processes with good tracking and regulation performances. Though the ability of the analytical design methods to determine once and for all whether a given set of specifications can be met is one of its chief advantages over the conventional trial-and-error design procedures. However, one disadvantage that offsets to some degree the enormous advantages is the relatively complicated algebra that must be employed in working out all but the simplest problem. Mathematical algorithms and computer software have been developed to treat some of the mathematical operations defined over the integral domain, such as matrix fraction description, spectral factorization, the Bezout identity, and the general manipulation of polynomial matrices. Hence, the design problems of Wiener-Hopf type of controllers and other similar algebraic design methods can be easily solved.
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It is well known that the addition of noise to the input data of a neural network during training can, in some circumstances, lead to significant improvements in generalization performance. Previous work has shown that such training with noise is equivalent to a form of regularization in which an extra term is added to the error function. However, the regularization term, which involves second derivatives of the error function, is not bounded below, and so can lead to difficulties if used directly in a learning algorithm based on error minimization. In this paper we show that, for the purposes of network training, the regularization term can be reduced to a positive definite form which involves only first derivatives of the network mapping. For a sum-of-squares error function, the regularization term belongs to the class of generalized Tikhonov regularizers. Direct minimization of the regularized error function provides a practical alternative to training with noise.
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This monograph proposes a general model for the analysis of polysemy. The underspecified content of polysemic items produces interpretations in relation with characterised contextual indicators. This ternary set of schematic representations applies to the meaning organisation of French indefinite qui que ce soit ('any'). Universal positive readings, existential and opposition readings are generated by modalised predicate, a modalised proposition and syntactically adjoined functions. "Affective" contexts yield a negative polarity interpretation, the interpretation is generated through concessive reasoning, which explains how scalar values can be evoked by an item representing arbitrary selection. Such contextual reasoning and characterised contextual indicators are the two modes for the calculation of the contextual interpretation of polysemous items.
Resumo:
This article extends the debate regarding the relationship between strategic planning and performance. It addresses criticism of previous empirical studies that have largely investigated direct and bi-variate relationships, producing equivocal results. The current study investigates the mediating effects of four types of flexibility on the strategic planning and performance relationship. Flexibility is defined as the extent to which new and alternative decisions are generated and considered in strategic planning, allowing for positive organizational change and adaptation to environmental turbulence. Through investigating simultaneous equations in a structural equation model, we find that two types of flexibility mediate the relationship between strategic planning and financial performance, while the other two types mediate the relationship between strategic planning and non-financial performance. The results are new empirical insights that have not been previously reported.
Resumo:
As part of a study into antimycobacterial compounds a set of phenolic N1-benzylidene-pyridinecarboxamidrazones was prepared and evaluated. This report describes the unexpected discovery of a potent compound with a pronounced selectivity for Gram-positive bacteria over Gram-negative micro-organisms. In addition, this compound is active against various drug-resistant Gram-positive bacteria. © 2005 Elsevier Ltd. All rights reserved.
Resumo:
This paper considers the role of opportunism in three contractual theories of the firm: rent-seeking theory, property rights theory, and agency theory. In each case I examine whether it is possible to have a functioning contractual theory of the firm without recourse to opportunism. Without opportunism firms may still exist as a result of issues arising from (incomplete) contracting. Far from posing a problem for the theory of the firm, questioning the role of opportunism and the ubiquity of the hold-up problem helps us understand more about the purpose and functions of contracts which go beyond mere incentive alignment.
Resumo:
This study examined whether the effectiveness of human resource management (HRM) practices is contingent on organizational climate and competitive strategy. The concepts of internal and external fit suggest that the positive relationship between HRM and subsequent productivity will be stronger for firms with a positive organizational climate and for firms using differentiation strategies. Resource allocation theories of motivation, on the other hand, predict that the relationship between HRM and productivity will be stronger for firms with a poor climate because employees working in these firms should have the greatest amount of spare capacity. The results supported the resource allocation argument. © 2005 Southern Management Association. All rights reserved.
Resumo:
This thesis explores, in a team context, using the Michigan Model, the relationship between social support, stress and well-being outcomes. The studies reported were carried out in Post Office Ltd. Study one examines differences in social support source and type for employees working in teams and quasi teams. Analysis was carried out at the individual level. The results supported previous work on well-being in teams: individuals working in teams report significantly higher levels of well-being, job satisfaction and organisational commitment than those individuals in quasi teams. Members of teams reported greater satisfaction with support from their manager and colleagues, and all types of support compared to members of quasi teams. Manager support and specific types of support mediated the relationship between team working and well-being outcomes. In terms of stressors, satisfaction with manager support and emotional challenge predicted greater influence which was positively related to the well-being outcomes. Study two conducted at the team level builds on relationships established in study one. Stage one explored teamness, the extent to which, along a continuum the team was well-defined. Stage two explored teamness agreement, the extent to which the team agreed on their teamness. The extent to which the Branch Office were a well-defined team had a positive effect on team functioning; participation, innovation and commitment to task excellence. Team functioning was associated with higher levels of satisfaction with manager and team support and all types of support. Working in a well-defined team was associated with job satisfaction, mediated by positive team functioning and social support. Teamness agreement predicted team well-being, clarity of objectives, work demands and satisfaction with reality check. Working in a team was not associated with performance. This thesis advances understanding in the area of team working and processes within teams, advancing understanding of the specifics of social support from different so urces and types of support. The studies reveal the key role of team functional characteri stics in creating the vehicle through which supportive interactions take place. which contribute to positive outcomes associated with working in a well-defined team.
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Modified oligonucleotides containing sulphur group have been useful tools for studies of carcinogenesis, protein or nucleic acid structures and functions, protein-nucleic acid interactions, and for antisense modulation of gene expression. One successful example has been the synthesis and study of oligodeoxynucleotides containing 6-thio-2'-deoxyguanine. 6-Thio-2-deoxyguanosine was first discovered as metabolic compound of 6- mercaptopurine (6-MP). Later, it was applied as drug to cure leukaemia. During the research of its toxicity, a method was developed to use the sulphur group as a versatile position for post-synthetic modification. The advantage of application of post-synthetic modification lies in its convenience. Synthesis of oligomers with normal sequences has become routine work in most laboratories. However, design and synthesis of a proper phosphoramidite monomer for a new modified nucleoside are always difficult tasks even for a skilful chemist. Thus an alternative method (post-synthetic method) has been invented to overcome the difficulties. This was achieved by incorporation of versatile nucleotides into oligomers which contain a leaving group, that is sufficiently stable to withstand the conditions of synthesis but can be substituted by nucleophiles after synthesis, to produce, a series of oligomers each containing a different modified base. In the current project, a phosphoramidite monomer with 6-thioguanine has been successfully synthesised and incorporated into RNA. A deprotection procedure, which is specific for RNA was designed for oligomers containing 6-thioguanosine. The results were validated by various methods (UV, HPLC, enzymatic digestion). Pioneer work in utilization of the versatile sulphur group for post-synthetic modification was also tested. Post-synthetic modification was also carried out on DNA with 6- deoxythioguanosine. Electrophilic reagents with various functional groups (alphatic, aromatic, fluorescent) and bi-functional groups have been attached with the oligomers.
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Despite the increasing popularity of research on intercultural preparation and its effectiveness, research on training for inpatriates has not been developed with the same level of rigour as research on training for expatriates. Furthermore, research on intercultural training hardly ever includes the aspect of preparing for the corporate culture of a company. For expatriates coming from headquarters’ national culture and equipped with a good knowledge of headquarters’ corporate culture, it might be sufficient to address only the national culture of the location abroad. But can the same be said for inpatriates coming from a foreign subsidiary? Therefore the qualitative research of my thesis was aimed at finding out if intercultural training programmes that address only the national culture of the host country are sufficient to prepare inpatriates for working at headquarters. A case study using a German multinational company has been conducted in order to find out what kind of problems and irritations inpatriates at the company’s headquarters perceive at work. In order to determine whether the findings are related to the national or the corporate culture, Hall’s and Hofstede’s approaches to culture were used. The interview analysis produced the following conclusion: Although the researched company promotes standardised worldwide corporate guidelines, there are many differences between headquarters and subsidiaries regarding the interpretation and realisation of these guidelines. These differences cause irritation, confusion and problems for the inpatriates. Therefore an effective intercultural preparation for inpatriates should be tailor-made and take into account the aspect of corporate culture, as well as the specific roles and functions of inpatriates.
Resumo:
The 21-day experimental gingivitis model, an established noninvasive model of inflammation in response to increasing bacterial accumulation in humans, is designed to enable the study of both the induction and resolution of inflammation. Here, we have analyzed gingival crevicular fluid, an oral fluid comprising a serum transudate and tissue exudates, by LC-MS/MS using Fourier transform ion cyclotron resonance mass spectrometry and iTRAQ isobaric mass tags, to establish meta-proteomic profiles of inflammation-induced changes in proteins in healthy young volunteers. Across the course of experimentally induced gingivitis, we identified 16 bacterial and 186 human proteins. Although abundances of the bacterial proteins identified did not vary temporally, Fusobacterium outer membrane proteins were detected. Fusobacterium species have previously been associated with periodontal health or disease. The human proteins identified spanned a wide range of compartments (both extracellular and intracellular) and functions, including serum proteins, proteins displaying antibacterial properties, and proteins with functions associated with cellular transcription, DNA binding, the cytoskeleton, cell adhesion, and cilia. PolySNAP3 clustering software was used in a multilayered analytical approach. Clusters of proteins that associated with changes to the clinical parameters included neuronal and synapse associated proteins.
Resumo:
Iyer and Velu (2006) have convincingly argued that contemporary analyses of fertility behaviour fail to explain why a woman (or a couple) will choose to postpone childbirth, and in particular to consider the role of uncertainty in this regard. They have addressed this lacuna in the literature by using a real options approach to model fertility decisions by relating uncertainty experienced by individuals to the likelihood of childbirth. However, they did not present empirical evidence. Since the theory implies the existence of two offsetting effects of uncertainty on fertility decisions, a positive insurance effect and a negative option value effect, it is not easy to reject the theory on the basis of empirical analysis, when one of these effects offsets the other. We construct such a test for East (and also West) Germany during that country's reunification, which takes advantage of the fact that because of the country's strong welfare system, the insurance effect should be dominated by the option value effect, thereby suggesting that the net relationship should be negative. The results provide rather strong support for the real options link, especially for Eastern Germany.