User-level integration of data and operation resources by means of a self-descriptive data model

This thesis describes the design of a system to integrate data access and various forms of data analysis and editing tools. -sets of operations-, under a single interactive user interface. The projected system is called YANUS (Yet ANother Unifying System). One of the major goals of this study is to create an environment for the user where he/she1 has optimal freedom to combine operations and apply these directly to his data, and where he is being supported to do so correctly. i.e. in conformance with the meaning of the data and of the operations. Direct application means that the user does not need to copy or transform the data. Another major goal is the encapsulation of existing external systems. Certain operations may, without the user's knowledge, be executed in these existing systems. Also, data to which operations are applied may be stored in existing databases. Thus. the user should be able to analyze data from existing databases with existing tools with minimal effort. He does not need to know about the different interfaces of different systems and about possible data translations. Finally, the environment must be extensible. with respect to the data and operations which may be accessed by the user. and with respect to the databases and software packages to be used to provide data and operations in the integrated system. The main hypothesis supported in this thesis is. that a powerful self-descriptive object-oriented data model can play a central role in achieving these goal

Symptoms and functional status of patients with disseminated cancer visiting outpatient departments

Considerable research has focused on pain and other symptoms in terminal cancer patients referred to hospices and palliative care services. These patients differ from Dutch cancer patients in the palliative stage of their disease because the latter are cared for by general practitioners at home and medical specialists in outpatient departments. To clarify the experience of these Dutch patients, a study was started to investigate the prevalence and severity of pain and other symptoms as well as the functional status of consecutive patients visiting oncology outpatient departments for follow-up. After randomization, one group (I) of patients was interviewed at home by a general practitioner using structured questionnaires. The other group (II) received the questionnaires by mail, and scored the symptoms independently. The results of the symptom assessment show that patients in groups I and II suffered 2.4 (SD = 1.7) and 2.8 (SD = 2.0) symptoms, respectively. Between 30% and 40% of all patients reported constipation, nausea, loss of appetite, coughing, and dyspnea. These percentages were 50% lower when only moderate, severe, or extremely distressing symptoms were included. Sixty percent of all patients had pain, and 20% indicated a daytime pain score of 5 or greater on a scale of 0 to 10. Functional status was measured by the COOPWONCA charts; the mean score for the charts "physical fitness" and "daily activities" was 1.5 points lower for cancer patients than a random sample from the community of the same age and gender. The findings of this study should motivate doctors to put more energy in symptom assessment and interventions in palliative care. Record 29 of 32 - SilverPlatter MEDLINE(R)

DUCAT (Dutch inventory of invasive Coronary Atherosclerosis Treatments)

Het DUCAT (Dutch inventory of invasive Coronary Atherosclerosis Treatments) project had tot doel te bepalen hoe passend behandelbeslissingen (beleidsbeslissingen) zijn bij patiënten met vernauwing van een of meer kransslagaders rond het hart (coronairlijden). DUCAT bestond uit drie delen: a) bepaling van de passendheid van behandelindicaties door een panel van deskundigen, uitgaande van drie behandelvormen: coronaire-omleidingsoperatie (CABG), 'dotteren' (PTCA), en medicamenteuze of andere niet-invasieve therapie (conservatieve behandeling); b) toetsing van de beleidsbeslissingen in tien hartcentra in Nederland aan de paneloordelen; c) het volgen van de lotgevallen van patiënten met passende en niet-passende beleidsbeslissingen. Dat laatste is beperkt gebleven tot een periode van een jaar. Hoe kan men vaststellen of een indicatie voor een ingreep passend is of niet? Ideaal zou zijn als de wetenschappelijke literatuur geen twijfel toelaat over wat de beste benadering is, maar dat is niet zo. De literatuur biedt voor vele toepassingen van CABG en vooral PTCA onvoldoende zekerheid. Er moet daarom ook een beroep worden gedaan op de ervaring van deskundigen die de indicaties in de praktijk stellen. Een aanpak - maar zeker niet de enige - om die ervaring te laten meetellen is ontwikkeld door het Amerikaanse instituut RAND in samenwerking met de Universiteit van California in Los Angeles (UCLA). De RAND/UCLA methode houdt in dat vele modelpatiënten, en bijpassende indicaties voor behandeling, worden onderscheiden op basis van combinaties van klinische kenmerken. Deskundige leden van een panel geven, op grond van de literatuur en aanvullende medische inzichten, voor elk van die modelpatiënten aan of een behandelindicatie passend, onzeker of niet-passend is. DUCAT is het eerste onderzoek in Nederland waarin deze methode is toegepast. DUCAT kende een theorie- en een praktijkdeel. In het theoriedeel kwamen twee vragen aan de orde. Hoe passend waren volgens het DUCAT-panel de vele indicaties voor behandeling bij coronairlijden en welke klinische en niet-klinische factoren hadden invloed op de oordelen van het panel? Het panel koos bij bijna de helft van de modelpatiënten voor invasieve behandeling en bij ruim een op de vijf voor conservatieve therapie, terwijl het in de rest van de gevallen geen voorkeur had voor de ene of andere benadering. Het panel vond CABG-indicaties vaker passend dan PTCA-indicaties. Het baseerde zich daarbij vooral op medische overwegingen, zoals het actuele klinische beeld en vooral de ernst van de anatomische afwijkingen. Anatomische kenmerken wogen in de oordeelsvorming zwaarder dan andere karakteristieken, zoals medicatie en de uitslag van een inspanningsproef. DUCAT richtte zich op patiënten die in het hartcentrum werden besproken op initiatief van een verwijzend cardioloog waarbij de bespreking leidde tot een beleidsbeslissing. Onze primaire belangstelling ging uit naar 3647 mensen met anatomisch gedefinieerd significant coronairlijden. De desbetreffende DUCAT-populatie bestond in doorsnee uit niet al te jonge mannen en vrouwen van wie velen zich presenteerden met een uitgebreide geschiedenis of actuele uiting van risicofactoren, ziekteverschijnselen, vatafwijkingen en behandelingen, dus met ernstige pathologie. Dat gold niet over de hele linie. Opvallend was het grote aantal mensen met eenvatslijden. Bij verreweg de meeste patiënten met significant coronairlijden opteerden de interventieartsen voor invasieve behandeling (CABG of PTCA); bij 13 procent viel de keus op conservatieve therapie. CABG kr

SUPPORTING DYNAMIC REUSE IN BUSINESS CASE DEVELOPMENT

Business case development (BCD) is a complex activity, which can potentially be improved by supporting the reuse of investment criteria and valuation methods. The goal of this research was to improve the usefulness and usability of business case frameworks (BCFs), while limiting the effort required to develop and maintain static databases of reusable components. Therefore, an approach was proposed for the dynamic reuse of business case components and contrasted with static reuse of business case components. In the dynamic approach, the reusable, domain-specific criteria and methods do not need to be pre-defined by experts in templates and taxonomies, but can be reused from earlier business cases. To test whether support for dynamic reuse improves BCFs, a usability experiment was set up. Three types of support for the reuse of criteria were compared: (1) recommendations, based on collaborative filtering and representative for the dynamic approach, (2) templates, representative for the static approach, and (3) no support. The task represented a simplified BCD activity and was completed by 208 people. The main results show that although the recommendations are as effective as the templates, they are the preferred type of support

Supporting fine-grained generative model-driven evolution

In the standard generative Model-driven Architecture (MDA), adapting the models of an existing system requires re-generation and restarting of that system. This is due to a strong separation between the modeling environment and the runtime environment. Certain current approaches remove this separation, allowing a system to be changed smoothly when the model changes. These approaches are, however, based on interpretation of modeling information rather than on generation, as in MDA. This paper describes an architecture that supports fine-grained evolution combined with generative model-driven development. Fine-grained changes are applied in a generative model-driven way to a system that has itself been developed in this way. To achieve this, model changes must be propagated correctly toward impacted elements. The impact of a model change flows along three dimensions: implementation, data (instances), and modeled dependencies. These three dimensions are explicitly represented in an integrated modeling-runtime environment to enable traceability. This implies a fundamental rethinking of MDA

Rate-dependency of action potential duration and refractoriness in isolated myocytes from the rabbit AV node and atrium

During atrial fibrillation, ventricular rate is determined by atrioventricular nodal (AVN) conduction, which in part is dependent upon the refractoriness of single AVN cells. The aims of this study were to investigate the rate-dependency of the action potential duration (APD) and effective refractory period (ERP) in single myocytes isolated from the AV node and atrium of rabbit hearts, using whole cell patch clamping, and to determine the contribution of the 4-aminopyridine (4-AP)-sensitive current, ITO1to these relationships in the two cell types. AVN cells had a more positive maximum diastolic potential (-60±1 v-71±2 mV), lower Vmax(8±2 v 144±17 V/s) and higher input resistance [420±46 v 65±7 MOHgr (mean±s.eP<0.05n=9–33)], respectively, than atrial myocytes. Stepwise increases in rate from 75 beats/min caused activation failure and Wenckebach periodicity in AVN cells (at around 400 beats/min), but 1:1 activation in atrial cells (at up to 600 beats/min). Rate reduction from 300 to 75 beats/min shortened the ERP in both cell types (from 155±7 to 135±11 ms in AVN cells [P<0.05, n=6] and from 130±8 to 106±7 ms in atrial cells [P<0.05, n=10]). Rate increase from 300 to 480 and 600 beats/min shortened ERP in atrial cells, by 12±4% (n=8) and 26±7% (n=7), respectively (P<0.05). By contrast, AVN ERP did not shorten at rates >300 beats/min. In atrial cells, rate reduction to 75 beats/min caused marked shortening of APD50(from 51±6 to 29±6 ms, P<0.05). 4-AP (1 mm) significantly prolonged atrial APD50at 75 beats/min (P<0.05, n=7), but not at 300 or 400 beats/min. In AVN cells, in contrast, there was less effect of rate change on APD, and 4-AP did not alter APD50at any rate. 4-AP also did not affect APD90or ERP in either cell type. In conclusion, a lack of ERP-shortening at high rates in rabbit single AVN cells may contribute to ventricular rate control. ITO1contributed to the APD50rate relation in atrial, but not AVN cells and did not contribute to the ERP rate relation in either cell type