970 resultados para Surgical technique and possible pitfalls


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Sox8 is a member of the Sox family of developmental transcription factor genes and is closely related to Sox9, a critical gene involved in mammalian sex determination and differentiation. Both genes encode proteins with the ability to bind similar DNA target sequences, and to activate transcription in in vitro assays. Expression studies indicate that the two genes have largely overlapping patterns of activity during mammalian embryonic development. A knockout of Sox8 in mice has no obvious developmental phenotype, suggesting that the two genes are able to act redundantly in a variety of developmental contexts. In particular, both genes are expressed in the developing Sertoli cell lineage of the developing testes in mice, and both proteins are able to activate transcription of the gene encoding anti-Mullerian hormone (AMH), through synergistic action with steroidogenic factor I (SF1). We have hypothesized that Sox8 may substitute for Sox9 in species where Sox9 is expressed too late to be involved in sex determination or regulation of Amh expression. However, our studies involving the red-eared slider turtle indicate that Sox8 is expressed at similar levels in males and females throughout the sex-determining period, suggesting that Sox8 is neither a transcriptional regulator for Amh, nor responsible for sex determination or gonad differentiation in that species. Similarly, Sox8 is not expressed in a sexually dimorphic pattern during gonadogenesis in the chicken. Since a functional role(s) for Sox8 is implied by its conservation during evolution, the significance of Sox8 for sexual and other aspects of development will need to be uncovered through more directed lines of experimentation. Copyright (C) 2003 S. Karger AG, Basel.

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A re-examination of fundamental concepts and a formal structuring of the waveform analysis problem is presented in Part I. eg. the nature of frequency is examined and a novel alternative to the classical methods of detection proposed and implemented which has the advantage of speed and independence from amplitude. Waveform analysis provides the link between Parts I and II. Part II is devoted to Human Factors and the Adaptive Task Technique. The Historical, Technical and Intellectual development of the technique is traced in a review which examines the evidence of its advantages relative to non-adaptive fixed task methods of training, skill assessment and man-machine optimisation. A second review examines research evidence on the effect of vibration on manual control ability. Findings are presented in terms of percentage increment or decrement in performance relative to performance without vibration in the range 0-0.6Rms'g'. Primary task performance was found to vary by as much as 90% between tasks at the same Rms'g'. Differences in task difficulty accounted for this difference. Within tasks vibration-added-difficulty accounted for the effects of vibration intensity. Secondary tasks were found to be largely insensitive to vibration except secondaries which involved fine manual adjustment of minor controls. Three experiments are reported next in which an adaptive technique was used to measure the % task difficulty added by vertical random and sinusoidal vibration to a 'Critical Compensatory Tracking task. At vibration intensities between 0 - 0.09 Rms 'g' it was found that random vibration added (24.5 x Rms'g')/7.4 x 100% to the difficulty of the control task. An equivalence relationship between Random and Sinusoidal vibration effects was established based upon added task difficulty. Waveform Analyses which were applied to the experimental data served to validate Phase Plane analysis and uncovered the development of a control and possibly a vibration isolation strategy. The submission ends with an appraisal of subjects mentioned in the thesis title.

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Background Evaluation of anterior chamber depth (ACD) can potentially identify those patients at risk of angle-closure glaucoma. We aimed to: compare van Herick’s limbal chamber depth (LCDvh) grades with LCDorb grades calculated from the Orbscan anterior chamber angle values; determine Smith’s technique ACD and compare to Orbscan ACD; and calculate a constant for Smith’s technique using Orbscan ACD. Methods Eighty participants free from eye disease underwent LCDvh grading, Smith’s technique ACD, and Orbscan anterior chamber angle and ACD measurement. Results LCDvh overestimated grades by a mean of 0.25 (coefficient of repeatability [CR] 1.59) compared to LCDorb. Smith’s technique (constant 1.40 and 1.31) overestimated ACD by a mean of 0.33 mm (CR 0.82) and 0.12 mm (CR 0.79) respectively, compared to Orbscan. Using linear regression, we determined a constant of 1.22 for Smith’s slit-length method. Conclusions Smith’s technique (constant 1.31) provided an ACD that is closer to that found with Orbscan compared to a constant of 1.40 or LCDvh. Our findings also suggest that Smith’s technique would produce values closer to that obtained with Orbscan by using a constant of 1.22.

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This study proposes an integrated analytical framework for effective management of project risks using combined multiple criteria decision-making technique and decision tree analysis. First, a conceptual risk management model was developed through thorough literature review. The model was then applied through action research on a petroleum oil refinery construction project in the Central part of India in order to demonstrate its effectiveness. Oil refinery construction projects are risky because of technical complexity, resource unavailability, involvement of many stakeholders and strict environmental requirements. Although project risk management has been researched extensively, practical and easily adoptable framework is missing. In the proposed framework, risks are identified using cause and effect diagram, analysed using the analytic hierarchy process and responses are developed using the risk map. Additionally, decision tree analysis allows modelling various options for risk response development and optimises selection of risk mitigating strategy. The proposed risk management framework could be easily adopted and applied in any project and integrated with other project management knowledge areas.

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This submission for a PhD by previously published work is based upon six publications in peer reviewed journals, reflecting a 9-year research programme. My research has shown, in a coherent and original way, the difficulty in treating people with dementia with safe and effective medication whilst providing research-founded guidance to develop mechanisms to optimise medication choice and minimise iatrogenic events. A wide range of methods, including systematic reviews, meta-analysis, randomised controlled trials (RCTs), quantitative research and mixed methods were used to generate the data, which supported the exploration of three themes. The first theme, to understand the incidence and causes of medication errors in dementia services, identified that people with dementia may be more susceptible to medication-related iatrogenic disease partly due to inherent disease-related characteristics. One particular area of concern is the use of anti-psychotics to treat the Behavioural and Psychological Symptoms of Dementia (BPSD). The second and third themes, respectively, investigated a novel pharmacological and health services intervention to limit anti-psychotic usage. The second phase found that whilst the glutamate receptor blocker memantine showed some promise, further research was clearly required. The third phase found that anti-psychotic usage in dementia may be higher than official figures suggest and that medication review linking primary and secondary care can limit such usage. My work has been widely cited, reflecting a substantial contribution to the field, in terms of our understanding of the causes of, and possible solutions to limit, medication-related adverse events in people with dementia. More importantly, this work has already informed clinical practice, patients, carers and policy makers by its demonstrable impact on health policy. In particular my research has identified key lines of enquiry for future work and for the development of my own personal research programme to reduce the risk associated with medication in this vulnerable population.

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Cannabidiol (CBD), a once-considered inert cannabis constituent, is one of two primary constituents of cannabis, alongside delta-9-tetrahydrocannabinol (?9-THC/THC). In the last 30 years, CBD has become implicated with a range of pharmaceutical mechanisms of great therapeutic interest and utility. This review details the literature speculating CBD’s attenuation of psychotic symptoms, particularly in light of a marked elevation in mean THC concentrations, and a concomitant decline in CBD concentrations in the prevalent U.K street market cannabis derivatives since c. 2000. CBD is purported to exhibit pharmacology akin to established atypical antipsychotics, whilst THC has been implicated with the precipitation of psychosis, and the induction of associated symptoms. The aim of the review was to clarify the conjecture surrounding CBD’s antipsychotic efficacy, before going on to detail prominent theories about its associated pharmacodynamics. Were CBD’s antipsychotic efficacy established, then there is potential for major latent anthropological repercussions to manifest, such as significant elevations in psychosis manifestations in the U.K. The review found a largely affirmative body of evidence asserting CBD’s antipsychotic efficacy. CBD exhibited capacity to attenuate natural and artificially induced psychoses in both animal and human cohorts, the latter of which included individuals considered resistant to conventional treatment. CBD also shows promising potential for use as an antipsychotic drug for Parkinson’s disease (PD) patients with psychosis, owing to its low rate of extra-pyramidal side-effect induction. A range of potential pharmacological mechanisms behind CBD’s neuroleptic pharmacology are outlined, with particular emphasis on its prevention of the hydrolysis and reuptake of the endogenous cannabinoid, anandamide. However, given the nebular aetiological basis for psychoses, explicit conclusions on how CBD attenuates psychotic symptoms remains to be determined.

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DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

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In the last decade, researchers in the social sciences have increasingly adopted neuroscientific techniques, with the consequent rise of research inspired by neuroscience in disciplines such as economics, marketing, decision sciences, and leadership. In 2007, we introduced the term organizational cognitive neuroscience (OCN), in an attempt to clearly demarcate research carried out in these many areas, and provide an overarching paradigm for research utilizing cognitive neuroscientific methods, theories, and concepts, within the organizational and business research fields. Here we will revisit and further refine the OCN paradigm, and define an approach where we feel the marriage of organizational theory and neuroscience will return even greater dividends in the future and that is within the field of clinical practice.

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There are several initiatives such as: US Ignite, Software Defined Networking (SDN), OpenFlow, Global Environment for Network Innovation (GENI), WiMAX and Internet 2 dealing with the future of the internet. The goal of the paper is to understand the goals, intricacies, and nuances of some of these techniques and show some of the possibilities of next-generation high-speed networking and their applications into education and culture heritage.

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We describe the fate of mangrove leaf tannins in aquatic ecosystems and their possible influence on dissolved organic nitrogen (DON) cycling. Tannins were extracted and purified from senescent yellow leaves of the red mangrove (Rhizophora mangle) and used for a series of model experiments to investigate their physical and chemical reactivity in natural environments. Physical processes investigated included aggregation, adsorption to organic matter-rich sediments, and co-aggregation with DON in natural waters. Chemical reactions included structural change, which was determined by excitation–emission matrix fluorescence spectra, and the release of proteins from tannin–protein complexes under solar-simulated light exposure. A large portion of tannins can be physically eliminated from aquatic environments by precipitation in saline water and also by binding to sediments. A portion of DON in natural water can coprecipitate with tannins, indicating that mangrove swamps can influence DON cycling in estuarine environments. The chemical reactivity of tannins in natural waters was also very high, with a half-life of less than 1 d. Proteins were released gradually from tannin–protein complexes incubated under light conditions but not under dark conditions, indicating a potentially buffering role of tannin– protein complexes on DON recycling in mangrove estuaries. Although tannins are not detected at a significant level in natural waters, they play an important ecological role by preserving nitrogen and buffering its cycling in estuarine ecosystems through the prevention of rapid DON export/loss from mangrove fringe areas and/or from rapid microbial mineralization.

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This paper examines the history of U.S. interventions in Latin America and attempts to explain their frequency by highlighting two factors – besides security and economic interests – that have made American interventions in Latin America so common. First, immense differences in size and influence between the United States and the States of Latin America have made interventions appear to be a low risk solution to crises that threaten American interests in the region. Second, when U.S government concerns and aspirations for Latin America converge with the general fears and aspirations of American foreign policy, interventions become much more likely. Such a convergence pushes Latin American issues high up the U.S. foreign policy agenda because of the region’s proximity to the United States and the perception that costs of intervening are low. The leads proponents of intervention to begin asking questions like “if we cannot stop communism/revolutions/drug-trafficking in Latin America, where can we stop it?” This article traces how these factors influenced the decision to intervene in Latin America during the era of Dollar Diplomacy and during the Cold War. It concludes with three possible scenarios that could lead to a reemergence of an American interventionist policy in Latin America. It makes the argument that even though the United Sates has not intervened in Latin America during the twenty-two years, it is far from clear that American interventions in Latin America will be consigned to the past.