13,857 research outputs found
Consent and the Construction of the Volunteer: Institutional Settings of Experimental Research on Human Beings in Britain during the Cold War
This study challenges the primacy of consent in the history of human experimentation and argues that privileging the cultural frameworks adds nuance to our understanding of the construction of the volunteer in the period 1945 to 1970. Historians and bio-ethicists have argued that medical ethics codes have marked out the parameters of using people as subjects in medical scientific research and that the consent of the subjects was fundamental to their status as volunteers. However, the temporality of the creation of medical ethics codes means that they need to be understood within their historical context. That medical ethics codes arose from a specific historical context rather than a concerted and conscious determination to safeguard the well-being of subjects needs to be acknowledged. The British context of human experimentation is under-researched and there has been even less focus on the cultural frameworks within which experiments took place. This study demonstrates, through a close analysis of the Medical Research Council's Common Cold Research Unit (CCRU) and the government's military research facility, the Chemical Defence Experimental Establishment, Porton Down (Porton), that the `volunteer' in human experiments was a subjective entity whose identity was specific to the institution which recruited and made use of the subject. By examining representations of volunteers in the British press, the rhetoric of the government's collectivist agenda becomes evident and this fed into the institutional construction of the volunteer at the CCRU. In contrast, discussions between Porton scientists, staff members, and government officials demonstrate that the use of military personnel in secret chemical warfare experiments was far more complex. Conflicting interests of the military, the government and the scientific imperative affected how the military volunteer was perceived
Embodying entrepreneurship: everyday practices, processes and routines in a technology incubator
The growing interest in the processes and practices of entrepreneurship has
been dominated by a consideration of temporality. Through a thirty-six-month
ethnography of a technology incubator, this thesis contributes to extant
understanding by exploring the effect of space. The first paper explores how
class structures from the surrounding city have appropriated entrepreneurship
within the incubator. The second paper adopts a more explicitly spatial analysis
to reveal how the use of space influences a common understanding of
entrepreneurship. The final paper looks more closely at the entrepreneurs within
the incubator and how they use visual symbols to develop their identity. Taken
together, the three papers reject the notion of entrepreneurship as a primarily
economic endeavour as articulated through commonly understood language and
propose entrepreneuring as an enigmatic attractor that is accessed through the
ambiguity of the non-verbal to develop the ânewâ. The thesis therefore contributes
to the understanding of entrepreneurship and proposes a distinct role for the non-verbal in that understanding
TOWARDS AN UNDERSTANDING OF EFFORTFUL FUNDRAISING EXPERIENCES: USING INTERPRETATIVE PHENOMENOLOGICAL ANALYSIS IN FUNDRAISING RESEARCH
Physical-activity oriented community fundraising has experienced an exponential growth in popularity over the past 15 years. The aim of this study was to explore the value of effortful fundraising experiences, from the point of view of participants, and explore the impact that these experiences have on peopleâs lives. This study used an IPA approach to interview 23 individuals, recognising the role of participants as proxy (nonprofessional) fundraisers for charitable organisations, and the unique organisation donor dynamic that this creates. It also bought together relevant psychological theory related to physical activity fundraising experiences (through a narrative literature review) and used primary interview data to substantiate these. Effortful fundraising experiences are examined in detail to understand their significance to participants, and how such experiences influence their connection with a charity or cause. This was done with an idiographic focus at first, before examining convergences and divergences across the sample. This study found that effortful fundraising experiences can have a profound positive impact upon community fundraisers in both the short and the long term. Additionally, it found that these experiences can be opportunities for charitable organisations to create lasting meaningful relationships with participants, and foster mutually beneficial lifetime relationships with them. Further research is needed to test specific psychological theory in this context, including self-esteem theory, self determination theory, and the martyrdom effect (among others)
Walking with the Earth: Intercultural Perspectives on Ethics of Ecological Caring
It is commonly believed that considering nature different from us, human beings (qua rational, cultural, religious and social actors), is detrimental to our engagement for the preservation of nature. An obvious example is animal rights, a deep concern for all living beings, including non-human living creatures, which is understandable only if we approach nature, without fearing it, as something which should remain outside of our true home. âWalking with the earthâ aims at questioning any similar preconceptions in the wide sense, including allegoric-poetic contributions. We invited 14 authors from 4 continents to express all sorts of ways of saying why caring is so important, why togetherness, being-with each others, as a spiritual but also embodied ethics is important in a divided world
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Brain signal recognition using deep learning
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityBrain Computer Interface (BCI) has the potential to offer a new generation of applications independent of
muscular activity and controlled by the human brain. Brain imaging technologies are used to transfer the
cognitive tasks into control commands for a BCI system. The electroencephalography (EEG) technology
serves as the best available non-invasive solution for extracting signals from the brain. On the other hand,
speech is the primary means of communication, but for patients suffering from locked-in syndrome, there
is no easy way to communicate. Therefore, an ideal communication system for locked-in patients is a
thought-to-speech BCI system.
This research aims to investigate methods for the recognition of imagined speech from EEG signals
using deep learning techniques. In order to design an optimal imagined speech recognition BCI, variety
of issues have been solved. These include 1) proposing new feature extraction and classification
framework for recognition of imagined speech from EEG signals, 2) grammatical class recognition of
imagined words from EEG signals, 3) discriminating different cognitive tasks associated with speech in
the brain such as overt speech, covert speech, and visual imagery. In this work machine learning, deep
learning methods were used to analyze EEG signals.
For recognition of imagined speech from EEG signals, a new EEG database was collected while the
participants mentally spoke (imagined speech) the presented words. Along with imagined speech, EEG
data was recorded for visual imagery (imagining a scene or an image) and overt speech (verbal speech).
Spectro-temporal and spatio-temporal domain features were investigated for the classification of imagined
words from EEG signals. Further, a deep learning framework using the convolutional network
and attention mechanism was implemented for learning features in the spatial, temporal, and spectral
domains. The method achieved a recognition rate of 76.6% for three binary word pairs. These experiments
show that deep learning algorithms are ideal for imagined speech recognition from EEG signals
due to their ability to interpret features from non-linear and non-stationary signals. Grammatical classes
of imagined words from EEG signals were also recognized using a multi-channel convolution network
framework. This method was extended to a multi-level recognition system for multi-class classification
of imagined words which achieved an accuracy of 52.9% for 10 words, which is much better in
comparison to previous work.
In order to investigate the difference between imagined speech with verbal speech and visual imagery
from EEG signals, we used multivariate pattern analysis (MVPA). MVPA provided the time segments
when the neural oscillation for the different cognitive tasks was linearly separable. Further, frequencies
that result in most discrimination between the different cognitive tasks were also explored. A framework
was proposed to discriminate two cognitive tasks based on the spatio-temporal patterns in EEG signals.
The proposed method used the K-means clustering algorithm to find the best electrode combination and
convolutional-attention network for feature extraction and classification. The proposed method achieved
a high recognition rate of 82.9% and 77.7%.
The results in this research suggest that a communication based BCI system can be designed using
deep learning methods. Further, this work add knowledge to the existing work in the field of communication
based BCI system
THE DREAM OF A ZERO WASTE SOCIETY: EXPLORING THE PRACTICES AND BEHAVIOURS OF WASTE GENERATION IN GREATER MEXICO CITY
This research aims to re-conceptualise consumption and waste generation through a broader set of theoretical questions and analytical methodologies to establish a more holistic theoretical framework for comprehending the global South's "waste crisis." This thesis is primarily based on the following question: "why do we dispose of things?". By
focusing on practices and behaviours of consumption and disposal by citizens of GMC, this thesis seeks to unpack the networks, symbols, skills, and meanings of these practices.
This moves the conceptualisation of waste generation away from being conceived as an irremediable consequence of population growth or as primary responsibility on the
consumers' shoulders. Therefore, this thesis proposes that consumers are embedded in a "throwaway environment" that pushes them toward unsustainable practices. However, this does not mean that the consumers have a "throwaway culture"; consumers might be "carriers" of practices, but they are still active participants.
By unravelling the multiple layers of framing that aggregate into the consumption and disposal of citizens in GMC, we shall see how GMC society's historical, social, and political framework serves as dispositions that guide an individual to act. This study focuses on modifying the narrative of considering consumers as careless, lazy, or
consumption-driven. It also sheds light on how ignoring these behaviours and practices will only bring temporary and reactionary solutions when dealing with waste.
This dissertation also offers an analytical framework that explores how consumers' elements interrelate and are synergetic. By re-conceptualising consumption and waste
generation, I propose not focusing on the insidious moral narrative of whether consumption and disposal are acceptable and to what degree. Instead, we should concentrate on a policy strategy that will help reduce the flow of materials. As a result, we might be able to curve a waste crisis by accepting shared responsibility (mostly borne by governments and businesses
Internationalisation dynamics in contemporary South American life sciences: the case of zebrafish
We tend to assume that science is inherently international. Geographical boundaries
are not a matter of concern in science, and when they do â e.g. due to the rise of
nationalist or populist movements â they are thought to constitute a threat to the
essence of the scientific enterprise; namely, the global mobility of ideas, knowledge
and researchers. Quite recently, we also started to consider that research could
become âmore internationalâ under the assumption that in doing so it becomes better,
i.e. more collaborative, innovative, dynamic, and of greater quality. Such a positive
conceptualisation of internationalisation, however, rests on interpretations coming
almost exclusively from the Global North that systematically ignore power dynamics
in scientific practice and that regard scientific internationalisation as an unproblematic
transformative process and as a desired outcome.
In Science and Technology Studies (STS), social research on model
organisms is perhaps the clearest example of the influence of the dominant vision of
internationalisation. This body of literature tends to describe model organism science
and their research communities as uniform and harmonious international ecosystems
governed by a strong collaborative ethos of sharing specimens, knowledge and
resources. But beyond these unproblematic descriptions, how does
internationalisation actually transform research on life? To what extent do the power
dynamics of internationalisation intervene in contemporary practices of knowledge
production and diffusion in this field of research?
This thesis revisits the dynamics and practices of scientific internationalisation
in contemporary science from the perspective of South American life sciences. It takes
the zebrafish (Danio rerio), a small tropic freshwater fish, originally from the Ganges
region in India and quite popular in pet shops, as a case study of how complex
dynamics of internationalisation intervene in science. While zebrafish research has
experienced a remarkable growth in recent years at the global scale, in South America
its growth has been unprecedented, allowing average laboratories, which often
operate with small budgets and with less well-developed science infrastructures, to
conduct world-class research.
My approach is based on a consideration of internationalisation as a
conceptual model of change. I consider internationalisation to be a process essentially
marked by tensions in the spatial, cognitive and evaluative dimensions of scientific
practice. These tensions, I claim, are not just a key feature of internationalisation, but
also aspects of a conceptual opposition that is geared towards explaining how change
comes about in science. By studying the dynamics of internationalisation, I seek to
understand various transformations of zebrafish research: from its construction as a
research artefact to its diffusion across geographical boundaries. My focus on South
America, on the other hand, helps me to understand the complexity of such dynamics
beyond the lenses of the dominant discourse of internationalisation that prevails in
the STS literature on model organisms. I use mixed-methods (i.e. semi-structured
interviews, document analysis, bibliometrics and social network analysis) to observe
and interpret transformations of internationalisation at different scales and levels.
My analysis suggests first, that internationalisation played an important role in
the construction of the zebrafish as a model organism and that, in the infrastructures
and practices of resource exchange that sustain the scientific value of the organism
internationally, dynamics of asymmetry and empowerment problematise the
collaborative ethos of this community. Second, I found that collaborative networks â
measured through co-authorships â also played an important role in the diffusion of
zebrafish as a model organism in South America. However, I did not find a clear
indication of international dependency in the diffusion of zebrafish, explained by a
geographical concentration of scientific expertise in the zebrafish collaboration
network. Rather than exposing peripheral researchers to novel ideas, networks of
international collaboration seem to be more related to access to privileged material
infrastructures resulting from the social organisation of scientific labour worldwide.
Lastly, by examining practices of biological data curation and researchersâ
international mobility trajectories, I describe how dynamics of internationalisation
shape the notion of research excellence in model organism science. In this case, I
found mobility trajectories to play a key role in boosting researchersâ contributions to
the communityâs database, especially among researchers from peripheral
communities like South America. Overall, while these findings show the value of
considering internationalisation as a conceptual model of change in science, more
research is needed on the intervention of complex dynamics of internationalisation in
other cases and fields of research
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Effect of Prior Plastic Strain on the High Temperature Creep Deformation and Damage Response of Type 316H Stainless Steel
Creep damage in ductile alloys is associated with creep deformation, crack growth and starts with the nucleation and growth of cavities. Under sustained high temperature and stress conditions, growing cavities can start to coalesce leading to microcracking and ultimate failure of a component. This mechanism can limit the lifetime of power plant components operating at high temperature. Many engineering components enter service in a cold-worked or prestrained condition as a result of manufacturing processes such as bending, forging, welding etc. Such pre-conditioning alters the creep resistance of the material significantly. Its effect on the creep deformation properties of a structure during service, and creep damage response can be advantageous for some materials but disadvantageous for others. Hence it is crucial to understand the effects of prior plastic strain when assessing the lifetime and safety of power plant components, for example in the context of nuclear power generation. The research set out in this thesis aims to examine the effect of prior plastic strain on subsequent creep deformation behaviour and development of damage in AISI Type 316H austenitic stainless steel, a material widely used in the fleet of Advanced Gas Cooled reactors operated by EDF Energy in the UK.
A novel cylindrical hourglass-shaped test specimen was designed for the research where a constant applied load provided a variation in uniaxial stress and associated creep strain rate along the hourglass gauge length. A further innovation in this PhD work involved exploiting the potential of 3D digital image correlation (3D-DIC) for measuring spatially resolved creep deformation along the hourglass gauge section over long duration creep tests at a high temperature of 550âŠC. The scope of testing included load-controlled creep tests carried out on 5 samples where 0, 4, 8, 12 and 16% of prior tensile plastic strain was introduced at room temperature. The prestraining was carried out on cylindrical samples before the hourglass shape was machined, ensuring a uniform level of prior plastic strain was present along the gauge section prior to creep experiments. It was found that prior plastic strain increased the creep resistance of the as-received material. Increasing plastic strain decreased the creep strain rate and creep ductility. On the other hand, it resulted in an increase in time to failure.
After creep failure at the maximum stress location, small-angle neutron scattering (SANS) was utilised to investigate changes in creep cavitational damage as a function of applied stress, level of creep strain and prior plastic strain at room temperature. Two sets of experiments were performed using the D11 instrument at the ILL reactor source (France) and the SANS2D instrument at the ISIS spallation source (UK). Very similar scattering results were obtained from the two instruments. Furthermore, SANS data from the instruments were analysed using two independent analysis routes; a maximum entropy method (MAXE) and a Monte Carlo algorithm (McSAS). Since SANS is an indirect method for measuring creep cavitation, the microstructure of the specimens was also investigated using qualitative scanning electron microscopy (SEM) in order to interpret and verify the SANS cavitation observations. The SANS investigations revealed a strong correlation between the volume fraction and number density of creep cavities with applied stress and creep strain. Furthermore, an increasing number density of small creep cavities as a function of prior plastic strain was observed and verified by qualitative SEM studies. This is new evidence that prior plastic strain, induced at room temperature, introduces specific cavitational damage in Type 316H stainless steel. The macroscopic damage calculation based on the stress modified ductility exhaustion model revealed that the majority of damage for the series of prestrained specimens is caused by plastic hole growth as a consequence of inducing prior plastic strain rather than due to creep related diffusion processes
Smart-antenna techniques for energy-efficient wireless sensor networks used in bridge structural health monitoring
Abstract: It is well known that wireless sensor networks differ from other computing platforms in that 1- they typically require a minimal amount of computing power at the nodes; 2- it is often desirable for sensor nodes to have drastically low power consumption. The main benefit of the this work is a substantial network life before batteries need to be replaced or, alternatively, the capacity to function off of modest environmental energy sources (energy harvesting). In the context of Structural Health Monitoring (SHM), battery replacement is particularly problematic since nodes can be in difficult to access locations. Furthermore, any intervention on a bridge may disrupt normal bridge operation, e.g. traffic may need to be halted. In this regard, switchbeam smart antennas in combination with wireless sensor networks (WSNs) have shown great potential in reducing implementation and maintenance costs of SHM systems. The main goal of implementing switch-beam smart antennas in our application is to reduce power consumption, by focusing the radiated energy only where it is needed. SHM systems capture the dynamic vibration information of a bridge structure in real-time in order to assess the health of the structure and to predict failures. Current SHM systems are based on piezoelectric patch sensors. In addition, the collection of data from the plurality of sensors distributed over the span of the bridge is typically performed through an expensive and bulky set of shielded wires which routes the information to a data sink at one end of the structure. The installation, maintenance and operational costs of such systems are extremely high due to high power consumption and the need for periodic maintenance. Wireless sensor networks represent an attractive alternative, in terms of cost, ease of maintenance, and power consumption. However, network lifetime in terms of node battery life must be very long (ideally 5â10 years) given the cost and hassle of manual intervention. In this context, the focus of this project is to reduce the global power consumption of the SHM system by implementing switched-beam smart antennas jointly with an optimized MAC layer. In the first part of the thesis, a sensor network platform for bridge SHM incorporating switched-beam antennas is modelled and simulated. where the main consideration is the joint optimization of beamforming parameters, MAC layer, and energy consumption. The simulation model, built within the Omnet++ network simulation framework, incorporates the energy consumption profiles of actual selected components (microcontroller, radio interface chip). The energy consumption and packet delivery ratio (PDR) of the network with switched-beam antennas is compared with an equivalent network based on omnidirectional antennas. In the second part of the thesis, this system model is leveraged to examine two distinct but interrelated aspects: Gallium Arsenide (GaAs) based solar energy harvesting and switched-beam antenna strategies. The main consideration here is the joint optimization of solar energy harvesting and switchedbeam directional antennas, where an equivalent network based on omnidirectional antennas acts as a baseline reference for comparison purposes.Il est bien connu que les rĂ©seaux de capteurs sans fils diffĂšrent des autres plateformes informatiques
Ă©tant donnĂ© 1- quâils requiĂšrent typiquement une puissance de calcul minimale aux
noeuds du rĂ©seau ; 2- quâil est souvent dĂ©sirable que les noeuds capteurs aient une consommation
dâĂ©nergie dramatiquement faible. La principale retombĂ©e de ce travail rĂ©side en la durĂ©e
de vie allongĂ©e du rĂ©seau avant que les piles ne doivent ĂȘtre remplacĂ©es ou, alternativement,
la capacitĂ© de fonctionner indĂ©finiment Ă partir de modestes sources dâĂ©nergie ambiente (glĂąnage
dâĂ©nergie). Dans le contexte du contrĂŽle de la santĂ© structurale (CSS), le remplacement de
piles est particuliÚrement problématique puisque les noeuds peuvent se trouver en des endroits
difficiles dâaccĂšs. De plus, toute intervention sur un pont implique une perturbation de lâopĂ©ration
normale de la structure, par exemple un arrĂȘt du traffic. Dans ce contexte, les antennes
intelligentes à commutation de faisceau en combinaison avec les réseaux de capteurs sans fils
ont dĂ©montrĂ© un grand potentiel pour rĂ©duire les coĂ»ts de rĂ©alisation et dâentretien de systĂšmes
de CSS. Lâobjectif principal de lâintĂ©gration dâantennes Ă commutation de faisceau dans notre
application réside dans la réduction de la consommation énergétique, réalisée en concentrant
lâĂ©nergie radiĂ©e uniquement lĂ oĂč elle est nĂ©cessaire. Les systĂšmes de CSS capturent lâinformation
dynamique de vibration dâune structure de pont en temps rĂ©el de maniĂšre Ă Ă©valuer la santĂ©
de la structure et prédire les failles. Les systÚmes courants de CSS sont basés sur des senseurs
piézoélectriques planaires. De plus, la collecte de données à partir de la pluralité de senseurs
distribuĂ©s sur lâĂ©tendue du pont est typiquement effectuĂ©e par le biais dâun ensemble coĂ»teux
et encombrant de cĂąbles blindĂ©s qui vĂ©hiculent lâinformation jusquâĂ un point de collecte Ă une
extremitĂ© de la structure. Lâinstallation, lâentretien, et les coĂ»ts opĂ©rationnels de tels systĂšmes
sont extrĂȘmement Ă©levĂ©s Ă©tant donnĂ© la consommation de puissance Ă©levĂ©e et le besoin dâentretien
régulier. Les réseaux de capteurs sans fils représentent une alternative attrayante, en termes
de coĂ»t, facilitĂ© dâentretien et consommation Ă©nergĂ©tique. Toutefois, la vie de rĂ©seau en termes
de la durĂ©e de vie des piles doit ĂȘtre trĂšs longue (idĂ©alement de 5 Ă 10 ans) Ă©tant donnĂ© le coĂ»t
et les problĂšmes liĂ©s Ă lâintervention manuelle. Dans ce contexte, ce projet se concentre sur la
rĂ©duction de la consommation de puissance globale dâun systĂšme de CSS en y intĂ©grant des
antennes intelligentes Ă commutation de faisceau conjointement avec une couche dâaccĂšs au
médium (couche MAC) optimisée. Dans la premiÚre partie de la thÚse, une plateforme de réseau
de capteurs sans fils pour le CSS dâun pont incorporant des antennes Ă commutation de faisceaux
est modĂ©lisĂ© et simulĂ©, avec pour considĂ©ration principale lâoptimisation des paramĂštres
de sĂ©lection de faisceau, de la couche MAC et de la consommation dâĂ©nergie. Le modĂšle de
simulation, construit dans le logiciel de simulation de réseaux Omnet++, incorpore les profils
de consommation dâĂ©nergie de composants rĂ©els sĂ©lectionnĂ©s (microcontrĂŽleur, puce dâinterface
radio). La consommation dâĂ©nergie et le taux de livraison de paquets du rĂ©seau avec antennes
à commutation de faisceau est comparé avec un réseau équivalent basé sur des antennes omnidirectionnelles.
Dans la deuxiĂšme partie de la thĂšse, le modĂšle systĂšme proposĂ© est mis Ă
contribution pour examiner deux aspects distrincts mais interreliĂ©s : le glĂąnage dâĂ©nergie Ă partir
de cellules solaire Ă base dâarsĂ©niure de Gallium (GaAs) et les stratĂ©gies liĂ©es aux antennes
Ă commutation de faisceau. La considĂ©ration principale ici est lâoptimisation conjointe du glĂąnage dâĂ©nergie et des antennes Ă commutation de faisceau, en ayant pour base de comparaison
un rĂ©seau Ă©quivalent Ă base dâantennes omnidirectionnelles
- âŠ