Potential shaping and the method of controlled Lagrangians

We extend the method of controlled Lagrangians to include potential shaping for complete state-space stabilization of mechanical systems. The method of controlled Lagrangians deals with mechanical systems with symmetry and provides symmetry-preserving kinetic shaping and feedback-controlled dissipation for state-space stabilization in all but the symmetry variables. Potential shaping complements the kinetic shaping by breaking symmetry and stabilizing the remaining state variables. The approach also extends the method of controlled Lagrangians to include a class of mechanical systems without symmetry such as the inverted pendulum on a cart that travels along an incline

Choosing embryos: Ethical complexity and relational autonomy in staff accounts of PGD

Copyright @ 2008 the authors. This article is available in accordance with the Creative Commons Deed, Attribution 2.5, see http://creativecommons.org/licenses/by-nc-nd/2.5/deed.en_CA.The technique of preimplantation genetic diagnosis (PGD) is commonly explained as a way of checking the genes of embryos produced by IVF for serious genetic diseases. However, complex accounts of this technique emerged during ethics discussion groups held for PGD staff. These form part of a study exploring the social processes, meanings and institutions that frame and produce ‘ethical problems’ for practitioners, scientists and others working in the specialty of PGD in the UK. Two ‘grey areas’ raised by staff are discussed in terms of how far staff are, or in the future may be, able to support autonomous choices of women/couples: accepting ‘carrier’ embryos within the goal of creating a ‘healthy’ child; and sex selection of embryos for social reasons. These grey areas challenged the staff’s resolve to offer individual informed choice, in the face of their awareness of possible collective social effects that might ensue from individual choices. We therefore argue that these new forms of choice pose a challenge to conventional models of individual autonomy used in UK genetic and reproductive counselling, and that ‘relational autonomy’ may be a more suitable ethical model to describe the ethical principles being drawn on by staff working in this area.The Wellcome Trust Biomedical Ethics Programme, who funded the project ‘Facilitating choice, framing choice: the experience of staff workingin pre-implantation genetic diagnosis’ (no: 074935)

Social welfare, genetic welfare? Boundary-work in the IVF/PGD clinic

Copyright @ 2006 Elsevier Ltd. All rights reserved.Through the lens of the ‘welfare of the child’ assessment, this paper explores how staff working in the area of in vitro fertilisation and preimplantation genetic diagnosis (IVF/PGD) balance reflexive relations of legitimacy and accountability between the public and private spheres, and between medicine, the citizen and the state. The wider research of which this analysis is a part uses multiple methods to study two National Health Service Assisted Conception Units in England. Research methods used included observation clinics and interviews with staff from a range of disciplines. We illustrate how the staff reveal tensions between their views that the welfare of the child assessment can be seen as intrusive and discriminatory, and on the other hand that medical intervention in reproduction should be socially and professionally accountable. These tensions can be understood sociologically in terms of a gradual movement from socially based solutions to fertility problems and disabilities, towards a biomedical, and arguably genetically oriented world view of such problems. Rather than being viewed as discrete, these two orientations should be seen as indicating an emergent direction of travel along a continuum, with elements of both being present in the accounts. We argue that consideration of the welfare of the child involves staff in ethical boundary-work across the two orientations and between the accountabilities and responsibilities of healthcare professionals, individuals and the state.The Wellcome Trust Biomedical Ethics Programme, who funded the project ‘Facilitating choice, framing choice: the experience of staff working in preimplantation genetic diagnosis’ (no. 074935)

A ‘healthy baby’: The double imperative of preimplantation genetic diagnosis

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 The Authors.This article reports from a study exploring the social processes, meanings and institutions that frame and produce ‘ethical problems’ and clinical dilemmas for practitioners, scientists and others working in the specialty of preimplantation genetic diagnosis (PGD). A major topic in the data was that, in contrast to IVF, the aim of PGD is to transfer to the woman’s womb only those embryos likely to be unaffected by serious genetic disorders; that is, to produce ‘healthy babies’. Staff described the complex processes through which embryos in each treatment cycle must meet a double imperative: they must be judged viable by embryologists and ‘unaffected’ by geneticists. In this article, we focus on some of the ethical, social and occupational issues for staff ensuing from PGD’s double imperative.The Wellcome Trus

Measuring students\u27 perceptions of plagiarism: Modification and Rasch validation of a plagiarism attitude scale

Plagiarism is a significant area of concern in higher education, given university students\u27 high self-reported rates of plagiarism. However, research remains inconsistent in prevalence estimates and suggested precursors of plagiarism. This may be a function of the unclear psychometric properties of the measurement tools adopted. To investigate this, we modified an existing plagiarism scale (to broaden its scope), established its psychometric properties using traditional (EFA, Cronbach\u27s alpha) and modern (Rasch analysis) survey evaluation approaches, and examined results of well-functioning items. Results indicated that traditional and modern psychometric approaches differed in their recommendations. Further, responses indicated that although most respondents acknowledged the seriousness of plagiarism, these attitudes were neither unanimous nor consistent across the range of issues assessed. This study thus provides rigorous psychometric testing of a plagiarism attitude scale and baseline data from which to begin a discussion of contextual, personal, and external factors that influence students\u27 plagiarism attitudes

STRUCTURAL PROCESSING OF VISUAL INFORMATION

One lesson that has been learned from previous approaches to scene analysis is that local methods are insufficient for extracting reliable information about the contents of a scene. Two different procedures that have been tried in order to remedy this deficiency are the use of knowledge via a priori information and internal models and multilevel analysis based on hierarchies of representations such as cone systems. It does not seem appropriate to drive the very first levels of analysis by a priori knowledge. It is doubtful that it will be possible to use knowledge in a way general and versatile enough to direct low level processing, and there is a need for some powerful data driven mechanisms that might at a later stage invoke internal models. It would seem more appropriate to obtain some crude global information through glancing or planning at low resolution levels that can drive a more scrutinous analysis at high resolution levels. While hierarchal systems are therefore good, the way they are currently being constructed is not necessarily good. In this context the issue of low level representation becomes more and more important, and not enough attention has been paid to this issue. Even Marr's provocative ideas about his primal sketch do not go to a sufficient level of analysis, and it is felt that more of the workload should be thrown onto the first processing levels. In this paper is posited a comprehensive hierarchal data structure that requires no decisions and therefore no parameters for its construction. The technique does not require preselected windows, but rather uses context-dependent criteria. The data structure is versatile, easily computed, and invertible in the sense that the original image is completely recoverable

Case Control Study on Dialysis Arthropathy: The Influence of Two Different Dialysis Membranes: Data from the EDTA Registry

In a retrospective case control study the prevalence of signs and symptoms of dialysis osteoarthropathy was analysed. Cases and controls had received over 9 years of maintenance haemodialysis uninterrupted by peritoneal dialysis or transplantation. The cases comprised 55 patients treated predominantly with polyacrylonitrile (AN69) dialysers. They were compared to a matched group dialysed exclusively with cellulosic membranes. Over 60% of all patients, cases and controls, showed one or more signs of disabling osteoarthropathy, with joint pains occurring more frequently in the older age groups. Twenty-seven of the 55 cases who had received less than 2 years of cellulosic membrane dialysis followed by 7-12 years of AN69 dialysis tended to have a lower prevalence of joint pains, carpal-tunnel syndrome and bone cysts. However, no statistically significant differences were obtained compared to the matched control group dialysed exclusively on cellulosic membranes (mostly cuprophane). The remaining 28 cases, who had been treated for more than 2 years with cellulosic membranes preceding the longer treatment period with polyacrylonitrile dialysers, showed a prevalence similar to that of their cellulosic controls. This study thus shows little, if any, influence of the two types of membranes on the prevalence of signs and symptoms of β2-microglobulin amyloidosi

DNESYS--An Expert System for Automatic Extraction of Drainage Networks from Digital Elevation

The determination of drainage networks and drainage basins is one of the more tedious yet important uses of topographic maps, and geographic information systems are now used extensively as a manual aid to facilitate that task. However, the wide availability of digital elevation maps has stimulated attempts to automate the process even further. In this paper, the problems that arose in earlier programs to map drainage systems are analyzed in detail. An expert system called the Drainage Network Extraction System (DNESYS) is described which uses both local operators and global reasoning to extract drainage networks and ridge lines. A stream representation called a parameterized directed graph (PDG) is constructed to model a drainage system. The construction of a model begins with an initial pixel labeling procedure. Then a network tracing and property measurement procedure converts the 2-D low-level labeling information into a symbolic database for high -level processing. By applying Dempster- Shafer evidence theory, evidence collection and uncertain reasoning are performed against the DNESYS knowledge-base that contains the drainage system model and the organized expert knowledge. By discarding erroneous information and supplying missing information, DNESYS produces a complete PDG which can be converted into the final drainage system