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Search Results: 1 - 10 of 9705 matches for " Marc Rodger "
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Diagnostic randomized controlled trials: the final frontier
Rodger Marc,Ramsay Tim,Fergusson Dean
Trials , 2012, DOI: 10.1186/1745-6215-13-137
Abstract: Clinicians, patients, governments, third-party payers, and the public take for granted that diagnostic tests are accurate, safe and effective. However, we may be seriously misled if we are relying on robust study design to ensure accurate, safe, and effective diagnostic tests. Properly conducted, randomized controlled trials are the gold standard for assessing the effectiveness and safety of interventions, yet are rarely conducted in the assessment of diagnostic tests. Instead, diagnostic cohort studies are commonly performed to assess the characteristics of a diagnostic test including sensitivity and specificity. While diagnostic cohort studies can inform us about the relative accuracy of an experimental diagnostic intervention compared to a reference standard, they do not inform us about whether the differences in accuracy are clinically important, or the degree of clinical importance (in other words, the impact on patient outcomes). In this commentary we provide the advantages of the diagnostic randomized controlled trial and suggest a greater awareness and uptake in their conduct. Doing so will better ensure that patients are offered diagnostic procedures that will make a clinical difference.
Stellar Populations and Galaxy Morphology at High Redshift
Andrew Bunker,Hyron Spinrad,Daniel Stern,Rodger Thompson,Leonidas Moustakas,Marc Davis,Arjun Dey
Physics , 2000,
Abstract: In this article we investigate the morphology and stellar populations of high-redshift galaxies through multi-waveband HST imaging and ground-based spatially-resolved spectroscopy. We study the redshift evolution of galaxy morphology in the Hubble Deep Field, using the deep IDT-NICMOS near-infrared HST imaging coupled with spectroscopic and photometric redshifts. Using the multi-waveband data to compare the appearance of galaxies at the same rest-frame wavelengths reveals that "morphological k-corrections" (the change in appearance when viewing high-z objects at shorter rest-frame wavelengths) are only important in a minority of cases, and that galaxies were intrinsically more peculiar at high redshift. One example of significant morphological k-corrections is spiral galaxies, which often show more pronounced barred structure in the near-infrared than in the optical. Therefore, the apparent decline in the fraction of barred spirals at faint magnitudes in the optical HDF may be due to band-shifting effects at the higher redshifts, rather than intrinsic evolution. Using such features as the age-sensitive Balmer+4000Ang break, the spatially- resolved colours of distant galaxies in optical/near-infrared imaging can also be used to study their component stellar populations. We supplement this with deep Keck/LRIS spectroscopy of two extended sources: a chain galaxy at z=2.8 (HDF4-555.1, the "Hot Dog" - the brightest U-drop Lyman-break galaxy in the HDF) and a pair of z=4.04 gravitationally lensed arcs behind the cluster Abell 2390. The absence of measurable rotation across the z=2.8 chain galaxy implies that it is unikely to be a disk viewed edge on. With the resolution enhancement from lensing, we detect stellar populations of different ages in the z=4 arcs.
Enterprise Architecture Ontology for Supply ChainMaintenance and Restoration of the Sikorsky’s UH-60 Helicopter  [PDF]
James A. Rodger, Pankaj Pankaj
Intelligent Information Management (IIM) , 2012, DOI: 10.4236/iim.2012.44024
Abstract: Ontologies have emerged as an important tool in the Enterprise architecture discipline to provide the theoretical foundations for designing and representing the enterprise as a whole or a specific area or domain, in a scientific fashion. This paper examines the domain of maintenance, repair, and overhaul (MRO) of the Sikorsky UH-60 helicopter involving multiple enterprises, and represents it through an ontology using the OWL Language and Protégé tool. The resulting ontology gives a formal and unambiguous model/representation of the MRO domain that can be used by multiple parties to arrive at a common shared conceptualization of the MRO domain. The ontology is designed to be conformant to ISO 13030 or the Product Life Cycle Support Standard (PLCS) standard, hence representing the state of being as per this standard especially at the interfaces between enterprises while incorporating existing reality to the greatest possible extent within the enterprises. As a result the ontology can be used to design Information Systems (IS) and their interfaces in all enterprises engaged in MRO to alleviate some of the issues present in the MRO area and to support business intelligence efforts.
Who would have thought it! Influence on outcome of radiotherapy, Ki67 and stroma. Introduction to Session 5
Alan Rodger
Breast Cancer Research , 2009, DOI: 10.1186/bcr2432
Abstract: Ragaz argues from the updated results of these pivotal Canadian and Danish trails, from survival trends observed in British Columbia, Canada and from the data presented consistently from 1990 to 2005 by the Early Breast Cancer Trialists' Collaborative Group that this effect on outcome is real [4]. The reality is explained by the record reduction over this period in post-radiotherapy acute and late morbidity due to improved techniques and dosimetry.Ragaz also indicates that, due to lack of radiotherapy trials, there is no clarity on what needs to be irradiated, while the question of who needs to be irradiated can no longer be answered simplistically on the basis of the number of nodes involved. The histopathological extent of nodal involvement judged by the percentage of involved nodes, by the spread within a node and by the presence of extracapsular spread - all indicators of risk of systemic relapse - is more critical than the indicators of increased risk of local failure.The need for more trials in radiotherapy is underlined by the fact that this paradigm shift in attitude and assessment of benefit occurred when the results of the pivotal randomised trials were published in 1997 showing that postoperative radiotherapy could improve long-term overall survival and not just cause long-term morbidity.That a single measurement of Ki67 does predict long-term outcome is discussed by Dowsett and colleagues [5], but with the caveat that such a single assay may not deliver all of the required information. For prognosis alone, a single pretreatment assay suffices - but for predictive information, a second post-treatment assay in the neoadjuvant case is needed. Further assays offer even more information for drug development studies or of drug resistance mechanisms.While breast stroma has been of passing interest to pathologists since at least the 1960s, when elastosis was considered a possible marker of prognosis, the hypothesis that malignant epithelial cells alone are progn
Comparing multiple competing interventions in the absence of randomized trials using clinical risk-benefit analysis
Alejandro Lazo-Langner, Marc A Rodger, Nicholas J Barrowman, Tim Ramsay, Philip S Wells, Douglas A Coyle
BMC Medical Research Methodology , 2012, DOI: 10.1186/1471-2288-12-3
Abstract: Using a cost-effectiveness approach from a clinical perspective (i.e. risk benefit analysis) we compared thromboprophylaxis with warfarin, low molecular weight heparin, unfractionated heparin, fondaparinux or ximelagatran in patients undergoing major orthopedic surgery, with sub-analyses according to surgery type. Proportions and variances of events defining risk (major bleeding) and benefit (thrombosis averted) were obtained through a meta-analysis and used to define beta distributions. Monte Carlo simulations were conducted and used to calculate incremental risks, benefits, and risk-benefit ratios. Finally, net clinical benefit was calculated for all replications across a range of risk-benefit acceptability thresholds, with a reference range obtained by estimating the case fatality rate - ratio of thrombosis to bleeding.The analysis showed that compared to placebo ximelagatran was superior to other options but final results were influenced by type of surgery, since ximelagatran was superior in total knee replacement but not in total hip replacement.Using simulation and economic techniques we demonstrate a method that allows comparing multiple competing interventions in the absence of randomized trials with multiple arms by determining the option with the best risk-benefit profile. It can be helpful in clinical decision making since it incorporates risk, benefit, and personal risk acceptance.In daily clinical practice clinicians are frequently presented with multiple competing treatment alternatives for the same clinical situation. In general it is accepted that when comparing several therapeutic alternatives the best evidence is derived from randomized trials. However, randomized trials are usually conducted comparing only two (or seldom three) options because inclusion of more treatment groups would require prohibitively large sample sizes and substantial increases in research costs and as a consequence, studies comparing all available treatment options at the sa
The Association of Factor V Leiden and Prothrombin Gene Mutation and Placenta-Mediated Pregnancy Complications: A Systematic Review and Meta-analysis of Prospective Cohort Studies
Marc A. Rodger ,Marisol T. Betancourt,Peter Clark,Pelle G. Lindqvist,Donna Dizon-Townson,Joanne Said,Uri Seligsohn,Marc Carrier,Ophira Salomon,Ian A. Greer
PLOS Medicine , 2010, DOI: 10.1371/journal.pmed.1000292
Abstract: Background Factor V Leiden (FVL) and prothrombin gene mutation (PGM) are common inherited thrombophilias. Retrospective studies variably suggest a link between maternal FVL/PGM and placenta-mediated pregnancy complications including pregnancy loss, small for gestational age, pre-eclampsia and placental abruption. Prospective cohort studies provide a superior methodologic design but require larger sample sizes to detect important effects. We undertook a systematic review and a meta-analysis of prospective cohort studies to estimate the association of maternal FVL or PGM carrier status and placenta-mediated pregnancy complications. Methods and Findings A comprehensive search strategy was run in Medline and Embase. Inclusion criteria were: (1) prospective cohort design; (2) clearly defined outcomes including one of the following: pregnancy loss, small for gestational age, pre-eclampsia or placental abruption; (3) maternal FVL or PGM carrier status; (4) sufficient data for calculation of odds ratios (ORs). We identified 322 titles, reviewed 30 articles for inclusion and exclusion criteria, and included ten studies in the meta-analysis. The odds of pregnancy loss in women with FVL (absolute risk 4.2%) was 52% higher (OR = 1.52, 95% confidence interval [CI] 1.06–2.19) as compared with women without FVL (absolute risk 3.2%). There was no significant association between FVL and pre-eclampsia (OR = 1.23, 95% CI 0.89–1.70) or between FVL and SGA (OR = 1.0, 95% CI 0.80–1.25). PGM was not associated with pre-eclampsia (OR = 1.25, 95% CI 0.79–1.99) or SGA (OR 1.25, 95% CI 0.92–1.70). Conclusions Women with FVL appear to be at a small absolute increased risk of late pregnancy loss. Women with FVL and PGM appear not to be at increased risk of pre-eclampsia or birth of SGA infants. Please see later in the article for the Editors' Summary
Knowledge Management of Software Productivity and Development Time  [PDF]
James A. Rodger, Pankaj Pankaj, Ata Nahouraii
Journal of Software Engineering and Applications (JSEA) , 2011, DOI: 10.4236/jsea.2011.411072
Abstract: In this paper, we identify a set of factors that may be used to forecast software productivity and software development time. Software productivity was measured in function points per person hours, and software development time was measured in number of elapsed days. Using field data on over 130 field software projects from various industries, we empirically test the impact of team size, integrated computer aided software engineering (ICASE) tools, software development type, software development platform, and programming language type on the software development productivity and development time. Our results indicate that team size, software development type, software development platform, and programming language type significantly impact software development productivity. However, only team size significantly impacts software development time. Our results indicate that effective management of software development teams, and using different management strategies for different software development type environments may improve software development productivity.
P2P Business Applications: Future and Directions  [PDF]
Pankaj Pankaj, Micki Hyde, James A. Rodger
Communications and Network (CN) , 2012, DOI: 10.4236/cn.2012.43029
Abstract: Since the launch of Napster in June 1999, peer-to-peer technology (P2P) has become synonymous with file sharing applications that are the bane of the recording industry due to copyright infringements and consequent revenue losses. P2P promised a revolution in business computing which has not arrived. It has become synonymous with illegal file sharing and copyright violations. Meanwhile the information systems industry has undergone a paradigm change, and we are supposedly living in a world of cloud computing and mobile devices. It is pertinent to examine if P2P, as a revolutionary technology, is still relevant and important today and will be in future. One has to examine this question in the context of the fact that P2P technologies have matured but have however had limited adoption outside file sharing in the consumer space. This paper provides a detailed analysis of P2P computing and offers some propositions to answer the question of the relevancy of P2P. It is proposed that P2P is still a relevant technology but may be reshaped in the coming years in a different form as compared to what exists today.
A Petri Net Pareto ISO 31000 Workflow Process Decision Making Approach for Supply Chain Risk Trigger Inventory Decisions in Government Organizations  [PDF]
James A. Rodger, Pankaj Pankaj, Ata Nahouraii
Intelligent Information Management (IIM) , 2014, DOI: 10.4236/iim.2014.63017
Abstract:

The Petri Net Pareto method proposed in this study has the advantages of acting directly on computing results by assessment of workflow process information. Our study contributes to the literature because it has investigated an ISO 31000 workflow process approach to group decision making for reducing backorders in the supply chain, from an integrated perspective utilizing Pareto charts and Petri nets. The contribution to the literature is also enhanced by the L-Project illustrative example that presents an evaluation hierarchy of supply chain risk. The proposed method is appropriate for use in situations in which assessment information may be qualitative or precise quantitative information is either unavailable or too costly to compute.

Exploring the Benefits of an Agile Information System  [PDF]
Pankaj Chaudhary, Micki Hyde, James A. Rodger
Intelligent Information Management (IIM) , 2017, DOI: 10.4236/iim.2017.95007
Abstract: Information Systems (IS) agility is a current topic of interest in the IS industry. The study follows up on work on the definition of the construct of IS agility and attributes for sensing, diagnosis, and selection and execution in an agile IS. IS agility is defined as the ability of an IS to sense a change in real time; diagnose it in real time; and select and execute a response in real time. Architecting an agile IS is a complex and resource-intensive task, and hence examination of its benefits is highly desired and appropriate. This paper examines the benefits of an Agile Information System. Benefits of an agile IS were derived from related academic literature and then refined using practitioner literature and qualitative data. The benefits considered were the first order or direct benefits. These benefits were then empirically validated through a survey of IT practitioners. The results of the survey were analyzed and a rank order of the benefits was arrived at. An exploratory factor analysis was also done to find the common dimensions underlying the benefits. It is suggested that organizations can use the empirically validated benefits from this study to justify and jump-start their capital and labor expenditure to build agility into their Information System.
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