An Architecture for Integrating Concurrency Control into Environment Frameworks

Research in layered and componentized systems shows the benefit of dividing the responsibility of services into separate components. It is still an unresolved issue, however, how a system can be created from a set of existing (independently developed) components. This issue of integration is of immense concern to software architects since a proper solution would reduce duplicate implementation efforts and promote component reuse. In this paper we take a step towards this goal within the domain of software development environments (SDEs) by showing how to integrate an external concurrency control component, called Pern, with environment frameworks. We discuss two experiments where we integrated Pern with Oz, a multi-site, decentralized process centered environment, and Process WEAVER, a commercial process server. We introduce an architecture for retrofitting an external concurrency control component into an environment

The Cord Approach to Extensible Concurrency Control

Database management systems (DBMSs) have been increasingly used for advanced application domains, such as software development environments, workflow management systems, computer-aided design and manufacturing, and managed healthcare. In these domains, the standard correctness model of serializability is often too restrictive. The authors introduce the notion of a concurrency control language (CCL) that allows a database application designer to specify concurrency control policies to tailor the behavior of a transaction manager. A well-crafted set of policies defines an extended transaction model. The necessary semantic information required by the CCL run-time engine is extracted from a task manager, a (logical) module by definition included in all advanced applications. This module stores task models that encode the semantic information about the transactions submitted to the DBMS. They have designed a rule-based CCL, called CORD, and have implemented a run-time engine that can be hooked to a conventional transaction manager to implement the sophisticated concurrency control required by advanced database applications. They present an architecture for systems based on CORD and describe how they integrated the CORD engine with the Exodus Storage Manager to implement altruistic locking

Incremental Process Support for Code Reengineering

Reengineering a large code base can be a monumental task, and the situation becomes even worse if the code is concomitantly being modified. For the past two years, we have been using the Marvel process centered environment (PCE) for all of our software development and are currently using it to develop the Oz PCE (Marvel's successor). Towards this effort, we are reengineering Oz's code base to isolate the process engine, transaction manager, and object management system as separate components that can be mixed and matched in arbitrary systems. In this paper, we show how a PCE can guide and assist teams of users in carrying out code reengineering while allowing them to continue their normal code development. The key features to this approach are its incremental nature and the ability of the PCE to automate most of the tasks necessary to maintain the consistency of the code base

Modification of graft survival by transfusion of the donor : a study in rats

There is wide acceptance that in humans blood transfusions given to the recipient before grafting produce a strikingly beneficial effect on the post-transplant course of cadaveric or living related kidneys (Opelz eta! .. 1981b: Salvatierra eta!.. 1983). Recently it has been reported by several authors that blood transfusions to the donor prior to nephrectomy positively influence graft survival (Jeekel eta!.. 1980: 1981: Frisk eta! .. 1981: 1983: Harder eta!.. 1984). However, retrospective studies by Berget a!. (1982), Bock eta!. (1984) and Opelz (1985a) could not confirm these reports. Many questions were raised by these retrospective observations and this made it necessary to experimentally investigate them in rigidly controlled studies. This thesis is the reflection of these experiments. Moreover. it contains an extensive introduction in the development of transplantation with special emphasis on the approaches to immune modulation in human kidney transplantatio

Small bowel transplantation: An overview

Small bowel transplantation (SBT) would, in theory, be the treatment of choice for patients suffering from the short bowel syndrome. Although SBT has been done with a considerable degree of success in some centers [36,145], it is by no means an established or widely applicable therapy for those with short bowel syndrome. The small bowel is unique among vascularized organ grafts because it not only elicits a vigorous rejection reaction but is also capable of inducing graft-versus-host disease (GVHD). Rejection of the graft does not only lead to loss of function but also to bacterial translocation. The risk of fatal sepsis is aggravated by the immunosuppression given to prevent rejection. Here, the history of SBT is described, and recent developments in experimental and clinical SBT, as well as future prospects for this theoretically optimal treatment modality for patients dependent on total parenteral nutrition (TPN) for life, are outlined

Minimal important change in physical function in trauma patients:a study using the short musculoskeletal function assessment

PURPOSE: The Short Musculoskeletal Function Assessment (SMFA) questionnaire can be used to evaluate physical functioning in patients with traumatic injuries. It is not known what change in score reflects a meaningful change to patients. The aim was to determine minimal important change (MIC) values of the subscales (0-100) of the Dutch SMFA-NL in a sample of patients with a broad range of injuries. METHODS: Patients between 18 and 65 years of age completed the SMFA-NL and the Global Rating of Effect (GRE) questions at 6-week and 12-month post-injury. Anchor-based MIC values were calculated using univariable logistic regression analyses. RESULTS: A total of 225 patients were included (response rate 67%). The MIC value of the Upper Extremity Dysfunction (UED) subscale was 8 points, with a misclassification rate of 43%. The Lower Extremity Dysfunction subscale MIC value was 14 points, with a misclassification rate of 29%. The MIC value of the Problems with Daily Activities subscale was 25 points, with a misclassification rate of 33%. The MIC value of the Mental and Emotional Problems (MEP) subscale was 7 points, with a misclassification rate 37%. CONCLUSION: MIC values of the SMFA-NL were determined. The MIC values aid interpreting whether a change in physical functioning can be considered clinically important. Due to the considerable rates of misclassification, the MIC values of the UED and MEP subscales should be used with caution

Resumption of pituitary and ovarian activity post-partum: endocrine and ultrasonic observations in bromocriptine-treated women

The resumption of pituitary and ovarian activity was investigated by hormonal measurements and ultrasound scanning in 45 healthy post-partum women who were treated with bromocriptine. Bromocriptine, 50 mg (Parlodel LAR) was administered within 24 h post-partum. Plasma luteinizing hormone, follicle stimulating hormone, oestradiol, progesterone and prolactin concentrations were measured repeatedly and correlated with ultrasound measurements. Forty-one of the 45 women completed the study. A prompt fall in prolactin levels to normal (non-pregnant) values was observed within 24 h post-partum. Hereafter, a rapid return of the normal menstrual cycle was observed. Endocrine evidence of ovulation was obtained in 19/41 women within 1 month post-partum. Ultrasound measurements started at day 10 and were repeated regularly in 40 women. Ultrasound evidence of ovulation was found in 25/40 women. Ultrasound findings appeared not to correspond with the hormonal measurements. It is concluded that the resumption of pituitary and ovarian secretory functions post-partum is not always paralleled by a concomitant recovery of normal follicular growth and ovulation. Application of a progesterone threshold to judge resumption of ovulation post-partum should be reconsidere