The spatial distribution and temporal dynamics of brain regions activated during the perception of object and non-object patterns

Both animal and human studies suggest that the efficiency with which we are able to grasp objects is attributable to a repertoire of motor signals derived directly from vision. This is in general agreement with the long-held belief that the automatic generation of motor signals by the perception of objects is based on the actions they afford. In this study, we used magnetoencephalography (MEG) to determine the spatial distribution and temporal dynamics of brain regions activated during passive viewing of object and non-object targets that varied in the extent to which they afforded a grasping action. Synthetic Aperture Magnetometry (SAM) was used to localize task-related oscillatory power changes within specific frequency bands, and the time course of activity within given regions-of-interest was determined by calculating time-frequency plots using a Morlet wavelet transform. Both single subject and group-averaged data on the spatial distribution of brain activity are presented. We show that: (i) significant reductions in 10-25 Hz activity within extrastriate cortex, occipito-temporal cortex, sensori-motor cortex and cerebellum were evident with passive viewing of both objects and non-objects; and (ii) reductions in oscillatory activity within the posterior part of the superior parietal cortex (area Ba7) were only evident with the perception of objects. Assuming that focal reductions in low-frequency oscillations (< 30 Hz) reflect areas of heightened neural activity, we conclude that: (i) activity within a network of brain areas, including the sensori-motor cortex, is not critically dependent on stimulus type and may reflect general changes in visual attention; and (ii) the posterior part of the superior parietal cortex, area Ba7, is activated preferentially by objects and may play a role in computations related to grasping. © 2006 Elsevier Inc. All rights reserved.

Flow field analysis of some mixing and conveying screw element regions, within a closely intermeshing, co-rotating twin-screw extruder.

Grafting of antioxidants and other modifiers onto polymers by reactive extrusion, has been performed successfully by the Polymer Processing and Performance Group at Aston University. Traditionally the optimum conditions for the grafting process have been established within a Brabender internal mixer. Transfer of this batch process to a continuous processor, such as an extruder, has, typically, been empirical. To have more confidence in the success of direct transfer of the process requires knowledge of, and comparison between, residence times, mixing intensities, shear rates and flow regimes in the internal mixer and in the continuous processor.The continuous processor chosen for the current work in the closely intermeshing, co-rotating twin-screw extruder (CICo-TSE). CICo-TSEs contain screw elements that convey material with a self-wiping action and are widely used for polymer compounding and blending. Of the different mixing modules contained within the CICo-TSE, the trilobal elements, which impose intensive mixing, and the mixing discs, which impose extensive mixing, are of importance when establishing the intensity of mixing. In this thesis, the flow patterns within the various regions of the single-flighted conveying screw elements and within both the trilobal element and mixing disc zones of a Betol BTS40 CICo-TSE, have been modelled using the computational fluid dynamics package Polyflow. A major obstacle encountered when solving the flow problem within all of these sets of elements, arises from both the complex geometry and the time-dependent flow boundaries as the elements rotate about their fixed axes. Simulation of the time dependent boundaries was overcome by selecting a number of sequential 2D and 3D geometries, used to represent partial mixing cycles. The flow fields were simulated using the ideal rheological properties of polypropylene and characterised in terms of velocity vectors, shear stresses generated and a parameter known as the mixing efficiency. The majority of the large 3D simulations were performed on the Cray J90 supercomputer situated at the Rutherford-Appleton laboratories, with pre- and postprocessing operations achieved via a Silicon Graphics Indy workstation. A mechanical model was constructed consisting of various CICo-TSE elements rotating within a transparent outer barrel. A technique has been developed using coloured viscous clays whereby the flow patterns and mixing characteristics within the CICo-TSE may be visualised. In order to test and verify the simulated predictions, the patterns observed within the mechanical model were compared with the flow patterns predicted by the computational model. The flow patterns within the single-flighted conveying screw elements in particular, showed good agreement between the experimental and simulated results.

Investigation of chaotic mixing in laminar fluid systems by the use of computational fluid dynamics

This work presents significant development into chaotic mixing induced through periodic boundaries and twisting flows. Three-dimensional closed and throughput domains are shown to exhibit chaotic motion under both time periodic and time independent boundary motions, A property is developed originating from a signature of chaos, sensitive dependence to initial conditions, which successfully quantifies the degree of disorder withjn the mixing systems presented and enables comparisons of the disorder throughout ranges of operating parameters, This work omits physical experimental results but presents significant computational investigation into chaotic systems using commercial computational fluid dynamics techniques. Physical experiments with chaotic mixing systems are, by their very nature, difficult to extract information beyond the recognition that disorder does, does not of partially occurs. The initial aim of this work is to observe whether it is possible to accurately simulate previously published physical experimental results through using commercial CFD techniques. This is shown to be possible for simple two-dimensional systems with time periodic wall movements. From this, and subsequent macro and microscopic observations of flow regimes, a simple explanation is developed for how boundary operating parameters affect the system disorder. Consider the classic two-dimensional rectangular cavity with time periodic velocity of the upper and lower walls, causing two opposing streamline motions. The degree of disorder within the system is related to the magnitude of displacement of individual particles within these opposing streamlines. The rationale is then employed in this work to develop and investigate more complex three-dimensional mixing systems that exhibit throughputs and time independence and are therefore more realistic and a significant advance towards designing chaotic mixers for process industries. Domains inducing chaotic motion through twisting flows are also briefly considered. This work concludes by offering possible advancements to the property developed to quantify disorder and suggestions of domains and associated boundary conditions that are expected to produce chaotic mixing.

The dynamics of organizational change : an analysis of power, professions and new managerialism in the case of CoastElectric

It is widely accepted that the Thatcher years and their immediate aftermath were associated with substantive social and organizational change. The privatisation programme, 'the rolling back of the State', prosecuted by the successive Conservative Governments from 1979-1997 was a central pillar of Governmental policy. This thesis seeks to engage with privatization through the of CoastElectric, a newly privatised Regional Electricity Company. This thesis contributes to the extant understanding of the dynamics of organizational change in four major ways. Firstly, the study into CoastElectric addresses the senior management decision making within the organization: in particular, it will attempt to make sense of 'why' particular decisions were made. The theoretical backdrop to this concern will draw on the concepts of normalization, cultural capital and corporate fashion. The argument presented in this thesis is that the decision-making broadly corresponded with that which could be considered to be at the vanguard of mangerialist thought. However, a detailed analysis suggested that at different junctures in CoastElectric's history there were differences in the approach to decision making that warranted further analysis. The most notable finding was that the relative levels of new managerialist cultural capital possessed by the decision-making elite had an important bearing upon whether the decision was formulated either endogenously or exogenously, with the assistance of cultural intermediaries such as management consultants. The thesis demonstrates the importance of the broader discourse of new managerialism in terms of shaping what is considered to be a 'commonsensical, rational' strategy. The second concern of this thesis is that of the process of organizational change. The study of CoastElectric attempts to provide a rich account of the dynamics of organizational change. This is realized through, first, examining the pre-existing context of the organization; second, through analyzing the power politics of change interventions. The master concepts utilised in this endeavour are that of: dividing practices, the establishment of violent hierarchies between competing discourses; symbolic violence; critical turning points; recursiveness; creative destruction; legitimation strategies and the reconstitution of subjects in the workplace.

An investigation of the emerging system of host government participation in the international oil industry with particular reference to Libyan participation arrangements

This study has been conceived with the primary objective of identifying and evaluating the financial aspects of the transformation in country/company relations of the international oil industry from the traditional concessionary system to the system of governmental participation in the ownership and operation of oil concessions. The emphasis of the inquiry was placed on assembling a case study of the oil exploitation arrangements of Libya. Through a comprehensive review of the literature, the sociopolitical factors surrounding the international oil business were identified and examined in an attempt to see their influence on contractual arrangements and particularly to gauge the impact of any induced contractual changes on the revenue benefit accruing to the host country from its oil operations. Some comparative analyses were made in the study to examine the viability of the Libyan participation deals both as an investment proposal and as a system of conducting oil activities in the country. The analysis was carried out in the light of specific hypotheses to assess the relative impact of the participation scheme in comparison with the alternative concessionary model on the net revenue resulting to the government from oil operations and the relative effect on the level of research and development within the industry. A discounted cash flow analysis was conducted to measure inputs and outputs of the comparative models and judge their revenue benefits. Then an empirical analysis was carried out to detect any significant behavioural changes in the exploration and development effort associated with the different oil exploitation systems. Results of the investigation of revenues support the argument that the mere introduction of the participation system has not resulted in a significant revenue benefit to the host government. Though there has been a significant increase in government revenue, associated with the period following the emergence of the participation agreements, this increase was mainly due to socio-economic factors other than the participation scheme. At the same time the empirical results have shown an association of the participation scheme with a decline of the oil industry's research and development efforts.

Oscillatory dynamics in the perception of pain investigated using magnetoencephalography

This thesis investigates changes in the oscillatory dynamics in key areas of the pain matrix during different modalities of pain. Gamma oscillations were seen in the primary somatosensory cortex in response to somatic electrical stimulation at painful and non-painful intensities. The strength of the gamma oscillations was found to relate to the intensity of the stimulus. Gamma oscillations were not seen during distal oesophageal electrical stimulation or the cold pressor test. Gamma oscillations were not seen in all participants during somatic electrical stimulation, however clear evoked responses from SI were seen in everyone. During a train of electrical pulses to the median nerve and the digit, a decrease in the frequency of the gamma oscillations was seen across the duration of the train. During a train of electrical stimuli to the median nerve and the digit, gamma oscillations were seen at ~20-100ms following stimulus onset and at frequencies between 30-100Hz. This gamma response was found to have a strong evoked component. Following a single electrical pulse to the digit, gamma oscillations were seen at 100-250ms and between 60-95Hz and were not temporally coincident with the main components of the evoked response. These results suggest that gamma oscillations may have an important role in encoding different aspects of sensory stimuli within their characteristics such as strength and frequency. These findings help to elucidate how somatic stimuli are processed within the cortex which in turn may be used to understand abnormal cases of somatosensory processing.

The dynamics and control of a remotely piloted plan-symmetric helicopter

Prior to the development of a production standard control system for ML Aviation's plan-symmetric remotely piloted helicopter system, SPRITE, optimum solutions to technical requirements had yet to be found for some aspects of the work. This thesis describes an industrial project where solutions to real problems have been provided within strict timescale constraints. Use has been made of published material wherever appropriate, new solutions have been contributed where none existed previously. A lack of clearly defined user requirements from potential Remotely Piloted Air Vehicle (RPAV) system users is identified, A simulation package is defined to enable the RPAV designer to progress with air vehicle and control system design, development and evaluation studies and to assist the user to investigate his applications. The theoretical basis of this simulation package is developed including Co-axial Contra-rotating Twin Rotor (CCTR), six degrees of freedom motion, fuselage aerodynamics and sensor and control system models. A compatible system of equations is derived for modelling a miniature plan-symmetric helicopter. Rigorous searches revealed a lack of CCTR models, based on closed form expressions to obviate integration along the rotor blade, for stabilisation and navigation studies through simulation. An economic CCTR simulation model is developed and validated by comparison with published work and practical tests. Confusion in published work between attitude and Euler angles is clarified. The implementation of package is discussed. dynamic adjustment of assessment. the theory into a high integrity software Use is made of a novel technique basing the integration time step size on error Simulation output for control system stability verification, cross coupling of motion between control channels and air vehicle response to demands and horizontal wind gusts studies are presented. Contra-Rotating Twin Rotor Flight Control System Remotely Piloted Plan-Symmetric Helicopter Simulation Six Degrees of Freedom Motion ( i i)

T-cell epitope prediction and immune complex simulation using molecular dynamics:state of the art and persisting challenges

Atomistic Molecular Dynamics provides powerful and flexible tools for the prediction and analysis of molecular and macromolecular systems. Specifically, it provides a means by which we can measure theoretically that which cannot be measured experimentally: the dynamic time-evolution of complex systems comprising atoms and molecules. It is particularly suitable for the simulation and analysis of the otherwise inaccessible details of MHC-peptide interaction and, on a larger scale, the simulation of the immune synapse. Progress has been relatively tentative yet the emergence of truly high-performance computing and the development of coarse-grained simulation now offers us the hope of accurately predicting thermodynamic parameters and of simulating not merely a handful of proteins but larger, longer simulations comprising thousands of protein molecules and the cellular scale structures they form. We exemplify this within the context of immunoinformatics.

Modelling manufacturing planning and control systems:the application of object-oriented principles and discrete-event simulation

Manufacturing planning and control systems are fundamental to the successful operations of a manufacturing organisation. 10 order to improve their business performance, significant investment is made by companies into planning and control systems; however, not all companies realise the benefits sought Many companies continue to suffer from high levels of inventory, shortages, obsolete parts, poor resource utilisation and poor delivery performance. This thesis argues that the fit between the planning and control system and the manufacturing organisation is a crucial element of success. The design of appropriate control systems is, therefore, important. The different approaches to the design of manufacturing planning and control systems are investigated. It is concluded that there is no provision within these design methodologies to properly assess the impact of a proposed design on the manufacturing facility. Consequently, an understanding of how a new (or modified) planning and control system will perform in the context of the complete manufacturing system is unlikely to be gained until after the system has been implemented and is running. There are many modelling techniques available, however discrete-event simulation is unique in its ability to model the complex dynamics inherent in manufacturing systems, of which the planning and control system is an integral component. The existing application of simulation to manufacturing control system issues is limited: although operational issues are addressed, application to the more fundamental design of control systems is rarely, if at all, considered. The lack of a suitable simulation-based modelling tool does not help matters. The requirements of a simulation tool capable of modelling a host of different planning and control systems is presented. It is argued that only through the application of object-oriented principles can these extensive requirements be achieved. This thesis reports on the development of an extensible class library called WBS/Control, which is based on object-oriented principles and discrete-event simulation. The functionality, both current and future, offered by WBS/Control means that different planning and control systems can be modelled: not only the more standard implementations but also hybrid systems and new designs. The flexibility implicit in the development of WBS/Control supports its application to design and operational issues. WBS/Control wholly integrates with an existing manufacturing simulator to provide a more complete modelling environment.

Mapping the yeast host cell response to recombinant membrane protein production:relieving the biological bottlenecks

Understanding the structures and functions of membrane proteins is an active area of research within bioscience. Membrane proteins are key players in essential cellular processes such as the uptake of nutrients, the export of waste products, and the way in which cells communicate with their environment. It is therefore not surprising that membrane proteins are targeted by over half of all prescription drugs. Since most membrane proteins are not abundant in their native membranes, it is necessary to produce them in recombinant host cells to enable further structural and functional studies. Unfortunately, achieving the required yields of functional recombinant membrane proteins is still a bottleneck in contemporary bioscience. This has highlighted the need for defined and rational optimization strategies based upon experimental observation rather than relying on trial and error. We have published a transcriptome and subsequent genetic analysis that has identified genes implicated in high-yielding yeast cells. These results have highlighted a role for alterations to a cell's protein synthetic capacity in the production of high yields of recombinant membrane protein: paradoxically, reduced protein synthesis favors higher yields. These results highlight a potential bottleneck at the protein folding or translocation stage of protein production.

A molecular dynamics model of the atomic structure of dysprosium alumino-phosphate glass

Molecular dynamics (MD) has been used to identify the relative distribution of dysprosium in the phosphate glass DyAl0.30P3.05O9.62. The MD model has been compared directly with experimental data obtained from neutron diffraction to enable a detailed comparison beyond the total structure factor level. The MD simulation gives Dy ... Dy correlations at 3.80(5) and 6.40(5) angstrom with relative coordination numbers of 0.8(1) and 7.3(5), thus providing evidence of minority rare-earth clustering within these glasses. The nearest neighbour Dy-O peak occurs at 2.30 angstrom with each Dy atom having on average 5.8 nearest neighbour oxygen atoms. The MD simulation is consistent with the phosphate network model based on interlinked PO4 tetrahedra where the addition of network modifiers Dy3+ depolymerizes the phosphate network through the breakage of P-(O)-P bonds whilst leaving the tetrahedral units intact. The role of aluminium within the network has been taken into explicit account, and A1 is found to be predominantly (78 tetrahedrally coordinated. In fact all four A1 bonds are found to be to P (via an oxygen atom) with negligible amounts of Al-O-Dy bonds present. This provides an important insight into the role of Al additives in improving the mechanical properties of these glasses.

Institutional work at field-configuring events:shaping industry change within sustainable transitions

Adopting an institutional approach from organization studies, this paper explores the role of key actors on “purposeful governance for sustainability” (Smith, Voss et al. 2010: 444) through the case of smart metering in the UK. Institutions are enduring patterns in social life, reflected in identities, routines, rules, shared meanings and social relations, which enable, and constrain, the beliefs and behaviours of individual and collective actors within a field (Thornton and Ocasio 2008). Large-scale external initiatives designed to drive regime-level change prompt ‘institutional entrepreneurs’ to perform ‘institutional work’ – “purposive action aimed at creating, maintaining and disrupting institutions” (Lawrence and Suddaby, 2006). Organization scholars are giving increasing attention to ‘field-configuring events’ (FCEs) which provide social spaces for diverse organizational actors to come together to collectively shape socio-technical pathways (Lampel and Meyer 2008). Our starting point for this exploratory study is that FCEs can offer important insights to the dynamics, politics and governance of sustainability transitions. Methodologically, FCEs allow us to observe and “link field evolution at the macro-level with individual action at the micro-level” (Lampel and Meyer, 2008: 1025). We examine the work of actors during a series of smart metering industry forums over a three-year period (industry presentations [n= 77] and panel discussions [n= 16]). The findings reveal new insights about how institutional change unfolds, alongside technological transitions, in ways that are partial and aligned with the interests of powerful incumbents whose voices are frequently heard at FCEs. The paper offers three contributions. First, the study responds to calls for more research examining FCEs and the role they play in transforming institutional fields. Second, the emergent findings extend research on institutional work by advancing our understanding of a specific site of institutional work, namely a face-to-face inter-organizational arena. Finally, in line with the research agenda for innovation studies and sustainability transitions elaborated by Smith et al (2010), the paper illustrates how actors in a social system respond to, translate, and enact interventions designed to promote industrial transformation, ultimately shaping the sustainability transition pathway.

Creating lift versus building the base:current trends in marketing dynamics

Markets are dynamic by nature, and marketing efforts can be directed to stimulate, reduce, or to utilize these dynamics. The field of marketing dynamics aims at modeling the effects of marketing actions and policies on short-term performance (“lift”) and on long-term performance (“base”). One of the core questions within this field is: “How do marketing efforts affect outcome metrics such as revenues, profits, or shareholder value over time?” Developments in statistical modeling and new data sources allow marketing scientists to provide increasingly comprehensive answers to this question. We present an outlook on developments in modeling marketing dynamics and specify research directions.

Agent-based simulation of lock-in dynamics in a duopoly

Lock-in is observed in real world markets of experience goods; experience goods are goods whose characteristics are difficult to determine in advance, but ascertained upon consumption. We create an agent-based simulation of consumers choosing between two experience goods available in a virtual market. We model consumers in a grid representing the spatial network of the consumers. Utilising simple assumptions, including identical distributions of product experience and consumers having a degree of follower tendency, we explore the dynamics of the model through simulations. We conduct simulations to create a lock-in before testing several hypotheses upon how to break an existing lock-in; these include the effect of advertising and free give-away. Our experiments show that the key to successfully breaking a lock-in required the creation of regions in a consumer population. Regions arise due to the degree of local conformity between agents within the regions, which spread throughout the population when a mildly superior competitor was available. These regions may be likened to a niche in a market, which gains in popularity to transition into the mainstream.

The structure and dynamics of 2-dimensional fluids in swelling clays

The interlayer pores of swelling 2:1 clays provide an ideal 2-dimensional environment in which to study confined fluids. In this paper we discuss our understanding of the structure and dynamics of interlayer fluid species in expanded clays, based primarily on the outcome of recent molecular modelling and neutron scattering studies. Counterion solvation is compared with that measured in bulk solutions, and at a local level the cation-oxygen coordination is found to be remarkably similar in these two environments. However, for the monovalent ions the contribution to the first coordination shell from the clay surfaces increases with counterion radius. This gives rise to inner-sphere (surface) complexes in the case of potassium and caesium. In this context, the location of the negative clay surface charge (i.e. arising from octahedral or tetrahedral substitution) is also found to be of major importance. Divalent cations, such as calcium, eagerly solvate to form outer-sphere complexes. These complexes are able to pin adjacent clay layers together, and thereby prevent colloidal swelling. Confined water molecules form hydrogen bonds to each other and to the clays' surfaces. In this way their local environment relaxes to close to the bulk water structure within two molecular layers of the clay surface. Finally, we discuss the way in which the simple organic molecules methane, methanol and ethylene glycol behave in the interlayer region of hydrated clays. Quasi-elastic neutron scattering of isotopically labelled interlayer CH 3OD and (CH2OD)2 in deuterated clay allows us to measure the diffusion of the CH3- and CH2-groups in both clay and liquid environments. We find that in both the one-layer methanol solvates and the two-layer glycol solvates the diffusion of the most mobile organic molecules is close to that in the bulk solution.