526 research outputs found

    The Significance of Routines for the Analysis and Design of Information Systems: A Preliminary Study

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    In this paper we argue that traditional information systems design and development is implicitly informed by a certain deliberative theory about the nature of purposeful activity. However, we examine other theories of activity that lead us to challenge this dominant model. This work-in-progress report reinterprets a number of existing case studies from the literature and provides a preliminary account of a new case study in order to demonstrate that successful operational systems in time-constrained environments often do not exhibit those characteristics that are the hallmarks of the deliberative approach. These systems are better discussed in terms of routines and situated action. Finally, we make some preliminary observations about the significance of this for Information Systems

    Magnetic resonance study of the pineal region: normal pineal gland, simple cysts

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    A magnetic resonance imaging (MRI) study of the normal pineal gland and pineal simple cysts was performed in 762 cases. A fine section technique (maximum 3 millimeters) enabled most of the times the identifying of a normal pineal in addition to demonstrating that a pineal without any cyst shows an isointense signal in Tl and T2 which, in turn, is enhanced following gadolinium. The measure of the normal pineal was of about 6.1 millimeters in its diameter length. Pineal simple cysts were observed in a 2.6% frequency in relation to the whole series (762 cases); however reaches 6.1% when only the visualized pineals were considered (329 cases). Also, it was found out that simple cysts were not correlated to age or gender. Simple cysts characteristics are: dimension less or equal to 20 millimeters; absence of expansive effect; similar signal to that of the cerebrospinal fluid; absence of cyst growth.Realiza-se um estudo por ressonância magnética da pineal normal e dos cistos simples da pineal e estabelece-se um protocolo para estudo da região pineal analisando-se 762 exames. A utilização da técnica com cortes finos (3 milímetros no máximo) identifica a pineal normal na maioria das vezes (84,4%) e demonstra que a pineal normal, sem cistos, apresenta sinal isointenso em Tl e T2 com realce após a injeção de gadolínio, medindo em média 6,1 milímetros no seu maior diâmetro. Os cistos simples da pineal aparecem com frequência de 2,6% em relação a toda a série (762 casos) elevando-se essa frequência para 6,1% se forem consideradas somente as pineais visiblizadas (329 casos). Os cistos simples não se correlacionam nem com a idade nem com o sexo e os cistos sintomáticos são raros. Os critérios para diagnóstico diferencial dos cistos simples versus tumores da região da pineal são: dimensões menores ou iguais a 20 milímetros; espessura da parede abaixo de 2 milímetros; ausência de efeito expansivo; sinal igual ao líquido cefalorraquidiano e ausência de crescimento dos cistos.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Diagnóstico por ImagemUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Serviço de NeurorradiologiaUniversidade Paris-Sul Centro Hospitalar Universitário de BicêtreUNIFESP, EPM, Depto. de Diagnóstico por ImagemUNIFESP, EPM, Serviço de NeurorradiologiaSciEL

    Developing a Methodology for Designing Routine Information Systems Based on the Situational Theory of Action

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    Information systems are part of purposeful socio-technical systems and consequently theories of action may help in understanding them. Current systems analysis and design methodologies seem to have been influenced only by one particular theory of action, which asserts that action results from deliberation upon an abstract representation of the world. Many disciplines have discussed an alternative ‘situational’ theory of action. There is no design methodology that fully supports designing systems reflecting the situational theory of action. The aim of this paper is to describe the motivation for, and progress to date of research-in-progress developing a design methodology based on concepts from the situational theory of action. This methodology for designing situational information systems is being iteratively refined using a combination of case studies and action research. This project is significant because many information systems fail in pressured routine environments where we would argue that the situational theory of action provides a better description of purposeful activity

    Ariel - Volume 6 Number 4

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    Editors Mark Dembert J.D. Kanofsky Frank Chervenak John Lammie Curt Cummings Entertainment Robert Breckenridge Joe Conti Gary Kaskey Photographer Larry Glazerman Overseas Editor Mike Sinason Humorist Jim McCann Staff Ken Jaffe Bob Sklaroff Halley Faust Jim Burk

    Caval-Aortic Access to Allow Transcatheter Aortic Valve Replacement in Otherwise Ineligible Patients Initial Human Experience

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    ObjectivesThis study describes the first use of caval-aortic access and closure to enable transcatheter aortic valve replacement (TAVR) in patients who lacked other access options. Caval-aortic access refers to percutaneous entry into the abdominal aorta from the femoral vein through the adjoining inferior vena cava.BackgroundTAVR is attractive in high-risk or inoperable patients with severe aortic stenosis. Available transcatheter valves require large introducer sheaths, which are a risk for major vascular complications or preclude TAVR altogether. Caval-aortic access has been successful in animals.MethodsWe performed a single-center retrospective review of procedural and 30-day outcomes of prohibitive-risk patients who underwent TAVR via caval-aortic access.ResultsBetween July 2013 and January 2014, 19 patients underwent TAVR via caval-aortic access; 79% were women. Caval-aortic access and tract closure were successful in all 19 patients; TAVR was successful in 17 patients. Six patients experienced modified VARC-2 major vascular complications, 2 (11%) of whom required intervention. Most (79%) required blood transfusion. There were no deaths attributable to caval-aortic access. Throughout the 111 (range 39 to 229) days of follow up, there were no post-discharge complications related to tract creation or closure. All patients had persistent aorto-caval flow immediately post-procedure. Of the 16 patients who underwent repeat imaging after the first week, 15 (94%) had complete closure of the residual aorto-caval tract.ConclusionsPercutaneous transcaval venous access to the aorta allows TAVR in otherwise ineligible patients, and may offer a new access strategy for other applications requiring large transcatheter implants
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