331 research outputs found
Contribution to the design of continuous -time Sigma - Delta Modulators based on time delay elements
No full textThe research carried out in this thesis is focused in the development of a new class of data converters for digital radio. There are two main architectures for communication receivers which perform a digital demodulation. One of them is based on analog demodulation to the base band and digitization of the I/Q components. Another option is to digitize the band pass signal at the output of the IF stage using a bandpass Sigma-Delta modulator. Bandpass Sigma- Delta modulators can be implemented with discrete-time circuits, using switched capacitors or continuous-time circuits. The main innovation introduced in this work is the use of passive transmission lines in the loop filter of a bandpass continuous-time Sigma-Delta modulator instead of the conventional solution with gm-C or LC resonators. As long as transmission lines are used as replacement of a LC resonator in RF technology, it seems compelling that transmission lines could improve bandpass continuous-time Sigma-Delta modulators. The analysis of a Sigma- Delta modulator using distributed resonators has led to a completely new family of Sigma- Delta modulators which possess properties inherited both from continuous-time and discretetime Sigma-Delta modulators. In this thesis we present the basic theory and the practical design trade-offs of this new family of Sigma-Delta modulators. Three demonstration chips have been implemented to validate the theoretical developments. The first two are a proof of concept of the application of transmission lines to build lowpass and bandpass modulators. The third chip summarizes all the contributions of the thesis. It consists of a transmission line Sigma-Delta modulator which combines subsampling techniques, a mismatch insensitive circuitry and a quadrature architecture to implement the IF to digital stage of a receiver
The practice of access pricing : telecommunications in the United Kingdom
No full textTelecommunications was the first network utility to be privatized in the United Kingdom. Drawing on 15 years'experience and discussion in the field, the author shows the economic principles of regulation in general and access pricing in particular that have been implemented. British Telecommunications (BT), formed as a public enterprise in 1980-81, was privatized in 1984. Since then the approaches to regulation have changed in three broad periods: the duoply, the transition to competition, and the recently introduced normalization phase. Dealing with each period, the author focuses on how the actual implementation of access charges are determined, at the same time providing background needed on regulatory intervention generally. Rather than follow the model of competition for a common infrastructure, Oftel [the Office of Telecommunications, the regulatory agency]has encouraged competition between alternative networks, which benefits customers but involves duplication of fixed costs. As a result of Oftel's approach, customers have seen their bills reduced 50 percent in real terms since privatization. It is difficult to know how much to attribute this remarkable result to technological progress (BT halved its workforce in the same period), to regulatory intervention (Oftel set string caps until 1997), or to competition (there are hundreds of players in the market). The author contends more weight should probably be given to the first two. Entrants have not achieved big market shares, if one considers the asymmetric regulation that has been in place for more than a decade. Indirectly, at least, competition benefited consumers by applying discipline to BT's behavior. Oftel's approach was interventionist until 1997, when it began trying to normalize the industry, as authority overseeing competition. The odds on complete deregulation are slight, and some controls on industry will remain. In the longer term, Oftel should especially monitor anticompetitive practices and collusive behavior among the bigger players (BT, CWC, and cellulator operators), The United Kingdom's interconnection experience demonstrates the complexity of the problem and its relationship to other topics, such as tariff rebalancing, access deficit, and universal service. Although a bit ad hoc, the recent incentive regulation, with a network cap based on proper accounting procedures and engineering models, may represent the best practice available today in the telecommunications industry, says the author.Public Sector Economics&Finance,Decentralization,Knowledge Economy,Economic Theory&Research,Payment Systems&Infrastructure,Public Sector Economics&Finance,Education for the Knowledge Economy,Knowledge Economy,Economic Theory&Research,ICT Policy and Strategies
"I had to give up so, so much": a narrative study to investigate the impact of Chronic Fatigue Syndrome (CFS) on the lives of young people.
No full textThe aim of this research was to explore the experiences of Chronic Fatigue Syndrome among a small group of adolescents, through three research questions: What are the personal experiences of young people with CFS – how does the condition affect their daily lives – including educational, social and psychological perspectives. Secondly, how does CFS impact family life – how does the condition influence not only the lives of sufferers but also those closest to them? Finally, can the knowledge base be deepened to help guide practice for those caring for the needs of adolescent CFS sufferers and their families?
The study used a narrative approach in an attempt to capture young people‘s stories, and to provide a window of insight into the personal impacts of CFS on the lives of individuals. Open-ended interviews with eight young CFS sufferers (11 to 18 year olds) were employed that explored personal experiences of CFS. In addition four email interviews were conducted with primary caregivers to explore the impacts of CFS from a carers perspective.
Five themes arose from a generic qualitative analysis of data - adolescent CFS is experienced as: (1) having to adapt to debilitating physical symptoms; (2) living with changes in family relationships and loved one‟s life experiences; (3) living with isolation and a disruption to a full and satisfying teenage life; and (4) feeling misunderstood and judged. Also a fifth and universal overarching theme, that CFS in adolescents is experienced as having to put life on hold. This is a major life adjustment, not only for the individual sufferers but for their family members also, who have to adapt to a new way of life accommodating for the limitations of one member.
The implications for clinical practice and further research are discussed
Biocultural perspectives on birth defects in medieval urban and rural English populations.
No full textThe biocultural and epidemiological approaches have been used as investigative methods by which to assess the prevalence of birth defects of the axial skeleton among five English Medieval population samples (Raunds Fumells, Northamptonshire; the hospital/almshouse of St James and St Mary Magdalene, Chichester, West Sussex; St Helen-on-the-Walls, York; Wharram Percy, East Yorkshire, and the Augustinian Friary cemetery, Hull, Humberside).The author hypothesises that Medieval urban populations produced offspring with higher frequencies of skeletal defects because they were subject to the adverse health-mediating effects of higher population density. These include poor quality, frequently overcrowded living conditions, poor sanitation, increased rates of disease threat and transmission, poorer quality food and drink due to pollution and adulteration, and greater levels of industrial-related air and water pollution. The author proposes that this response was a consequence of the impaired interaction between a population-wide compromised nutritional status and a co-existing weakened immune response. It is proposed that rural populations will express significantly lower frequencies of the same skeletal defects, as they are not subject to the same adverse environmental effects of population density and urban living conditions. The results support this hypothesis among the four populations derived from burial grounds associated with residential areas, whilst the Hull population expresses a rural pattern of defect prevalence, raising questions of possibly limited, exclusive access to burial at that site, available to non-urban dwellers. The author suggests that similar reproductive effects may be found today in populations undergoing demographic transition, for example, those experiencing the process of urbanisation in the developing world, or those migrating to the developed West. The author also shows how the results, when viewed alongside the medical literature, may indicate the presence of soft-tissue anomalies which are invisible to those working with dry bone. Keywords: urban, rural, medieval, birth defects, congenital, urbanisation, population density, biocultural, epidemiology, spine, cleft palate, skeleton, archaeology, palaeopathology
Neonatologie/Pädiatrie – Leitlinie Parenterale Ernährung, Kapitel 13
No full textThere are special challenges in implementing parenteral nutrition (PN) in paediatric patients, which arises from the wide range of patients, ranging from extremely premature infants up to teenagers weighing up to and over 100 kg, and their varying substrate requirements. Age and maturity-related changes of the metabolism and fluid and nutrient requirements must be taken into consideration along with the clinical situation during which PN is applied. The indication, the procedure as well as the intake of fluid and substrates are very different to that known in PN-practice in adult patients, e.g. the fluid, nutrient and energy needs of premature infants and newborns per kg body weight are markedly higher than of older paediatric and adult patients. Premature infants <35 weeks of pregnancy and most sick term infants usually require full or partial PN. In neonates the actual amount of PN administered must be calculated (not estimated). Enteral nutrition should be gradually introduced and should replace PN as quickly as possible in order to minimise any side-effects from exposure to PN. Inadequate substrate intake in early infancy can cause long-term detrimental effects in terms of metabolic programming of the risk of illness in later life. If energy and nutrient demands in children and adolescents cannot be met through enteral nutrition, partial or total PN should be considered within 7 days or less depending on the nutritional state and clinical conditions.Eine besondere Herausforderung bei der Durchführung parenteraler Ernährung (PE) bei pädiatrischen Patienten ergibt sich aus der großen Spannbreite zwischen den Patienten, die von extrem unreifen Frühgeborenen bis hin zu Jugendlichen mit einem Körpergewicht von mehr als 100 kg reicht, und ihrem unterschiedlichen Substratbedarf. Dabei sind alters- und reifeabhängige Veränderungen des Stoffwechsels sowie des Flüssigkeits- und Nährstoffbedarfs zu berücksichtigen sowie auch die klinische Situation, in der eine PE eingesetzt wird. Das Vorgehen unterscheidet sich deshalb ganz erheblich von der PE-Praxis bei erwachsenen Patienten, z.B. ist der Flüssigkeits-, Nährstoff- und Energiebedarf von Früh- und Neugeborenen pro kg Körpergewicht höher als bei älteren pädiatrischen und bei erwachsenen Patienten. In der Regel benötigen alle Frühgeborenen <35. SSW und alle kranken Reifgeborenen während der Phase des allmählichen Aufbaus der enteralen Nahrungszufuhr eine vollständige oder partielle PE. Die Zufuhrmengen der PE bei Neonaten müssen berechnet (nicht geschätzt) werden. Der Anteil der PE sollte zur Minimierung von Nebenwirkungen sobald wie möglich durch Einführung einer enteralen Ernährung vermindert (teilparenterale Ernährung) und schließlich komplett durch enterale Ernährung abgelöst werden. Eine unangemessene Substratzufuhr im frühen Säuglingsalter kann langfristig nachteilige Auswirkungen im Sinne einer metabolischen Programmierung des Krankheitsrisikos im späteren Lebensalter haben. Wenn bei älteren Kindern und Jugendlichen dagegen der Energie- und Nährstoffbedarf eines Patienten im Vorschul- oder Schulalter durch eine enterale Nährstoffzufuhr nicht gedeckt werden kann, ist abhängig von Ernährungszustand und klinischen Umständen spätestens innerhalb von 7 Tagen eine partielle oder totale PE zu erwägen
Protein and energy nutrition of marine gadoids, Atlantic cod (Gadus morhua L.) and haddock (Melanogrammus aeglefinus L.)
No full text Primary goals of this thesis were to: 1) examine the in vivo digestion of macronutrients from conventional or alternative feed ingredients used in practical diets of juvenile gadoids (Atlantic cod and haddock), 2) document growth potential of fish at the juvenile grower phase given varying levels of dietary protein and energy and 3) assess the potential of in vitro pH-Stat methods for rapid screening protein quality of feed ingredients, specifically for gadoids. All primary research questions were linked to and built upon one another with the goal of gaining a better understanding of protein and energy utilization of juvenile grower phase gadoids. Studies showed that cod and haddock have a high capacity to utilize a wide range of dietary feed ingredients, such as fish meals, zooplankton meal, soybean products (meal, concentrate and isolate) and wheat gluten meal. New dietary formulations for gadoids may also utilize pulse meals, corn gluten meal, canola protein concentrate and crab meal. Digestibility data in this thesis is currently the only research that examined both in vivo and in vitro macronutrient digestibility of a large number and wide range of individual ingredients, specifically for gadoids. This is essential to gain new knowledge on protein and energy utilization as well as for least-cost ration formulations and effective substitution of ingredients into new formulations. Data has demonstrated a dietary digestible protein/digestible energy (DP/DE)ratio of 30 g DP/MJ DE is required for gadoids during the juvenile phase (in vitro closed-system pH-Stat assay for rapid screening protein quality of test ingredients that is ‘species-specific’ to gadoids. It is demonstrated that in vitro results generally reflected results obtained through conventional in vivo protein digestibility methods. Studies resulted in the first generation of a ‘gadoid-specific’ proteolytic enzyme extraction method and in vitro closed-system pH-Stat assay which may be useful to investigate protein digestion, absorption and metabolism of gadoids and further development of their feeds. </p
Realising the geo/graphic landscape of the everyday: a practice led investigation into an interdisciplinary geo/graphic design process
No full textThis research proposes that the ‘geo/graphic’ design process—an original synthesis of cultural geographic and graphic design theory and practice—offers much to geographers and graphic designers in relation to the understanding and representation of place, and the potential of print based graphic design to create interactive, multi-linear spaces of exploration for the reader.
The understanding and representation of place is a central issue within cultural geography, with place itself a complex notion defined in contemporary geographic terms as ongoing and relational. This problematises both understanding and representation, as places, in a sense, are never ‘fixed’. Addressing this, and the contention that much of place evades representation, many geographers have begun to use methods that site the researcher, and their understanding, in more embodied, experiential ways within place, and are drawing on ‘creative’ methods such as film-making or sound recording. Yet, the predominant representation of place within geography remains the academic text, with few attempts to explore the communicative possibilities of type and image in this context. So, the pages of academic journals remain conventional, though research methods develop in multi-sensory ways. This research bridges the apparent divide between methods of exploring and representing place, and in doing so positions the graphic designer as researcher and develops a process that engages with the understanding and representation of place in a holistic way. Foregrounding graphic design practice, it highlights design interventions that re-situate the page as an experiential place.
A qualitative, naturalistic and reflective methodological approach is taken, drawing on social science methods and design practice. Ethnographic methods inspire a series of print based design test projects, each conveying a particular version of the London borough of Hackney—the testing ground for the research. Analysis of the design test projects, establishes key elements of the research and practice, thus articulating the specifics of the ‘geo/graphic’ design process
The secret ring:: knowing asthma in Teeside's children
No full textAsthma in children in Teesside in the north east of England is the subject of my research. Asthma is the most commonly diagnosed chronic health problem of childhood in the United Kingdom and its prevalence has increased markedly in recent decades. Previous research has identified it as being a particular health concern of people in Teesside. ‘What is asthma?' is my central research question, and I seek its answer in how people talk about asthma. My data is derived from semi-structured interviews with children with asthma and their families, observation of their consultations with health professionals in asthma clinics, and unstructured interviews within, and participant observation of, their local community. Asthma is presented as different modes of 'unhealth' - illness, disease, sickness and diagnosis, the last being a sub-category of, or the same as, sickness. Relationships are created between these different modes of asthma and other unhealths. Research focuses upon the contributions of biology, culture and history to asthma in Teesside's children. I show how relationships between the self and the other, the individual and the population, and the local and wider worlds contribute to how asthma is known in them. Throughout, a contrast is drawn between asthma as a thing and asthma as a word. Central to my argument is that the contribution of things and words to asthma is variable, and uncertainty over their respective contributions gives asthma its potency. The dissertation is, however, also about researching asthma. Reflexivity guides my research and I discuss how my dual background in medicine and anthropology has influenced my approach to researching asthma and to writing about it. Disciplines, I argue, discipline the practice and presentation of research: what asthma was when I practised medicine is not what I have researched here as an anthropologist
The impact of illness and the impact of school closure on social contact patterns.
No full textBACKGROUND: Mathematical models, based on data describing normal patterns of social mixing, are used to understand epidemics in order to predict patterns of disease spread and plan interventions and responses. However, individuals who are ill show behavioural changes that affect their social mixing patterns and predictive models should take into account these changes if they are to be effective. OBJECTIVES: To describe and quantify the changes in (1) social contact behaviour experienced by individuals when they are ill with pandemic H1N1 influenza (swine flu) and (2) mixing patterns of school children that take place as a result of swine flu-related school closures. METHODS: For the first part of the study, a self-completed questionnaire-based study was carried out in the autumn/winter of 2009-10. The study population was individuals who had been diagnosed with swine flu and who received a swine flu antiviral prescription from an antiviral distribution centre (ADC). It consisted of an initial survey to be filled in when participants were symptomatic with swine flu and a follow-up survey to be filled in when they had recovered. Each part of the questionnaire had two sections: patient details and a contact diary. The second part of the study was adapted to quantify the difference in mixing patterns of pupils between the school term and the half-term holiday as school closures did not occur during the study period. Eight schools participated and questionnaire packs were distributed to them, containing two surveys: one to be filled in during the school term and one during the spring half-term holiday. RESULTS: For the patient study, approximately 3800 surveys were distributed by 31 ADCs. Overall, 317 responses to the initial survey were received and 179 participants returned the follow-up survey. For all types of a contact, except contacts made at home, there were highly significant differences in contact behaviour (Wilcoxon signed-rank test, p < 0.001). Individuals made substantially fewer contacts when they were ill than when they were well. Analysis showed that returning to work was the most significant predictor of increased numbers of contacts. Also, the greater the change in the number of symptoms reported, the greater the change in the number of contacts. For the school study, approximately 1100 questionnaire packs were distributed and 134 responses were received, with 119 paired contact diaries. Pupils reported on average 18.51 contacts each day during term time and 9.24 during the half-term holiday - a reduction of over 50% and a highly significant change (Wilcoxon signed-rank test, p < 0.0001). CONCLUSIONS: The evidence from this study suggests that ill individuals make substantial changes to their social contact patterns. These changes are strongly linked to absence from work and the severity of the reported illness. Epidemiological modellers should therefore consider the implications of illness-related behavioural changes on model predictions. Future studies to measure the extent of behavioural change in a broader cross-section of infected cases could be valuable, along with more detailed studies of the social contact patterns of school children, focusing on differences between school terms and school holidays
First measurement of the vertical bar t vertical bar-dependence of coherent J/psi photonuclear production
No full textThe first measurement of the cross section for coherent J/Psi photoproduction as a function of vertical bar t vertical bar, the square of the momentum transferred between the incoming and outgoing target nucleus, is presented. The data were measured with the ALICE detector in ultra-peripheral Pb-Pbcollisions at a centre-of-mass energy per nucleon pair root s(NN) = 5.02 TeV with the J/Psi produced in the central rapidity region vertical bar y vertical bar < 0.8, which corresponds to the small Bjorken-xrange (0.3 - 1.4) x 10(-3). The measured vertical bar t vertical bar-dependence is not described by computations based only on the Pb nuclear form factor, while the photonuclear cross section is better reproduced by models including shadowing according to the leading-twist approximation, or gluon-saturation effects from the impact-parameter dependent Balitsky-Kovchegov equation. These new results are therefore a valid tool to constrain the relevant model parameters and to investigate the transverse gluonic structure at very low Bjorken- x. (C) 2021 The Author(s). Published by Elsevier B.V
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