Object-oriented protocol hierarchies for distributed workflow systems

Distributed software systems such as groupware and workflow systems will play a key role in the near future. While numerous models which promise highly sophisticated functionality are proposed in the literature their implementation is still a difficult and very expensive task. Therefore existing systems fall far behind their promises. Entities of the workflow level are often autonomous. Consequently, they are related to each other in more than a fixed client/server configuration: they often perform their activities in collaboration. Workflow models also contain a lot of information about the system\u27s dynamics. If one uses objects as an implementation mode

Object migration in non-monolithic distributed applications

Object migration is usually applied to optimize distributed monolithic systems. In this paper, the authors investigate whether object migration can also be utilized in cooperative systems which consist of autonomous components. We show that object migration policies will not always optimize system performance. Rather they can reduce it drastically if different components apply these policies concurrently. Conventional run-time support for linguistic primitives which are usually used to express migration policies is adapted to cooperative systems. We show that two novel approaches, place-policy and reduction of attachment-transitiveness, can counter the degradation caused by conflicting policies. In order to restrict attachment-transitiveness we introduce dynamic relationships called \emph{alliances} between objects which explicitly define cooperation contexts. The effects of these modifications are evaluated by simulation

Multi-object cooperation in distributed object bases

It is an emerging trend to build large information systems in a component-based fashion where the components follow the concept of object. Applications are constructed by organizing pre-built objects such that they cooperate with each other to perform some task. However, considerable programming effort is required to express multi-object constraints in terms of the traditional message-passing mechanism. This observation lead many authors to suggest communication abstractions in object models. One promising approach is to separate multi-object constraints from the objects and collect them into a separate construct. We call this construct an alliance. Unlike other approaches we allow alliances to involve large sets of long-lived objects which may dynamically vary during the - also potentially long - life-time of the alliance. Alliances are not only visible at the specification level but are also computational entities which enforce multi-object constraints at run-time. They do so in an unreliable world, i.e., we do not assume that objects will always meet their obligations in a cooperation. Since objects may often be distributed across a network, we demonstrate that alliances are an ideal place to deal with aspects of distribution in an application-specific manner. We illustrate our thesis by one of the key questions of distributed object management: where shall objects be located and when shall they migrate to which node? We show that alliances allow for customized distribution policies which are neither "hardwired" into the objects nor necessitate a centralized distribution control

Ausgewählte Kapitel der Implementierung objektorientierter Datenbanksysteme

Objektorientierte Datenbanksysteme bieten gegenüber klassischen Datenbanksysten, wie bspw. den Relationalen Systemen oder den Netzwerk-Systemen, eine erweiterte Funktionalität, die in vielen Anwendungsbereichen benötigt wird. Beispiele für Anwendungen objektorientierter Datenbanksysteme sind technische Informationssysteme Entwurfsdatenbanken oder Multi-Media-Datenbanken. Die erweiterte Funktionalität objektorientierter Datenbanksysteme erfordert neue Implementierungskonzepte. Das Ziel dieses Seminars, das im Sommersemester 1994 am Institut für Programmstrukturen und Daten organisation der Universität Karlsruhe gehalten wurde, ist die Untersuchung ausgewählter Kapitel bei der Implementierung objektorientierter Daten- banksysteme. Das Seminar ist in vier Teile gegliedert. Im ersten Teil wird - quasi aus Benutzersicht - in die Konzepte objektorientierter Datenmodelle eingeführt Aus Implementierungssicht stellen diese Konzepte die Spezifikation für ein zu implementierendes objektorientiertes Datenbanksystem dar. Der zweite Teil beschäftigt sich mit derSpeicherung von Objekten auf dem Hintergrundspeicher sowie mit dem Umgang mit persistenten Objekten zur Laufzeit. In Teil drei werden zwei spezielle Synchronisations-Verfahren vorgestellt, die im Hinblick auf objektorientierte Datenbanksysteme entworfen wurden. In Teil vier sind zwei Themen zusammengefaßt, die einen Überblick geben über Evolution in objektorientierten Datenbanksystemen und über aktive objectorientierte Datenbanksystem

Associations of frailty with health care costs – results of the ESTHER cohort study

Background: The concept of frailty is rapidly gaining attention as an independent syndrome with high prevalence in older adults. Thereby, frailty is often related to certain adverse outcomes like mortality or disability. Another adverse outcome discussed is increased health care utilization. However, only few studies examined the impact of frailty on health care utilization and corresponding costs. The aim of this study was therefore to investigate comprehensively the relationship between frailty, health care utilization and costs. Methods: Cross sectional data from 2598 older participants (57–84 years) recruited in the Saarland, Germany, between 2008 and 2010 was used. Participants passed geriatric assessments that included Fried’s five frailty criteria: weakness, slowness, exhaustion, unintentional weight loss, and physical inactivity. Health care utilization was recorded in the sectors of inpatient treatment, outpatient treatment, pharmaceuticals, and nursing care. Results: Prevalence of frailty (≥3 symptoms) was 8.0 %. Mean total 3-month costs of frail participants were €3659 (4 or 5 symptoms) and €1616 (3 symptoms) as compared to €642 of nonfrail participants (no symptom). Controlling for comorbidity and general socio-demographic characteristics in multiple regression models, the difference in total costs between frail and non-frail participants still amounted to €1917; p < .05 (4 or 5 symptoms) and €680; p < .05 (3 symptoms). Among the 5 symptoms of frailty, weight loss and exhaustion were significantly associated with total costs after controlling for comorbidity. Conclusions: The study provides evidence that frailty is associated with increased health care costs. The analyses furthermore indicate that frailty is an important factor for health care costs independent from pure age and comorbidity. Costs were rather attributable to frailty (and comorbidity) than to age. This stresses that the overlapping concepts of multimorbidity and frailty are both necessary to explain health care use and corresponding costs among older adults

Biomarkers of Neurodegeneration in Autoimmune-Mediated Encephalitis

Progranulin (PGRN), Total-Tau (t-tau), and Neurofilament light chain (NfL) are well known biomarkers of neurodegeneration. The objective of the present study was to investigate whether these parameters represent also biomarkers in autoimmune-mediated Encephalitis (AE) and may give us insights into the pathomechanisms of AE. We retrospectively examined the concentration of PGRN in the cerebrospinal fluid (CSF) and serum of 38 patients suffering from AE in acute phase and/or under treatment. This AE cohort comprises patients with autoantibodies against: NMDAR (n = 18 patients), Caspr2 (n = 8), Lgi-1 (n = 10), GABAB(R) (n = 1), and AMPAR (n = 1). Additionally, the concentrations of NfL (n = 25) and t-tau (n = 13) in CSF were measured when possible. Follow up data including MRI were available in 13 patients. Several age-matched cohorts with neurological diseases besides neuroinflammation or neurodegeneration served as control groups. We observed that PGRN was significantly elevated in the CSF of patients with NMDAR-AE in the acute phase, but normalized at follow up under treatment (p &lt; 0.01). In the CSF of other patients with AE PGRN was in the range of the CSF levels of control groups. T-tau was highly elevated in the CSF of patients with temporal FLAIR-signal in the MRI and in patients developing a hippocampal sclerosis. NfL was exceptionally high initially in Patients with AE with a paraneoplastic or parainfectious cause and also normalized under treatment. The normalizations of all biomarkers were mirrored in an improvement on the modified Rankin scale. The data suggest that the concentration of PGRN in CSF might be a biomarker for acute NMDAR-AE. Pathological high t-tau levels may indicate a risk for hippocampal sclerosis. The biomarker properties of NfL remain unclear since the levels decrease under treatment, but it could not predict severity of disease in this small cohort. According to our results, we recommend to measure in clinical practice PGRN and t-tau in the CSF of patients with AE

Effects of 3 Weeks of Oral Low-Dose Cobalt on Hemoglobin Mass and Aerobic Performance

Introduction: Cobalt ions (Co2+) stabilize HIFa and increase endogenous erythropoietin (EPO) production creating the possibility that Co2+ supplements (CoSupp) may be used as performance enhancing substances. The aim of this study was to determine the effects of a small oral dosage of CoSupp on hemoglobin mass (Hbmass) and performance with the objective of providing the basis for establishing upper threshold limits of urine [Co2+] to detect CoSupp misuse in sport. Methods: Twenty-four male subjects participated in a double-blind placebo-controlled study. Sixteen received an oral dose of 5mg of ionized Co2+ per day for 3 weeks, and eight served as controls. Blood and urine samples were taken before the study, during the study and up to 3 weeks after CoSupp. Hbmass was determined by the CO-rebreathing method at regular time intervals, and VO2max was determined before and after the CoSupp administration period. Results: In the Co2+ group, Hbmass increased by 2.0 +/- 2.1% (p < 0.001) while all the other analyzed hematological parameters did not show signi fi cant interactions of time and treatment. Hemoglobin concentration ([Hb]) and hematocrit (Hct) tended to increase (p = 0.16, p = 0.1) and also [EPO] showed a similar trend (baseline: 9.5 +/- 3.0, after 2 weeks: 12.4 +/- 5.2 mU/ml). While mean VO2max did not change, there was a trend for a positive relationship between changes in Hbmass and changes in VO2max immediately after CoSupp (r = 0.40, p = 0.11). Urine [Co2+] increased from 0.4 +/- 0.3 to 471.4 +/- 384.1 ng/ml (p < 0.01) and remained signi fi cantly elevated until 2 weeks after cessation. Conclusion: An oral Co2+ dosage of 5 mg/day for 3 weeks effectively increases Hbmass with a tendency to increase hemoglobin concentration ([Hb]) and hematocrit (Hct). Because urine Co2+ concentration remains increased for 2 weeks after cessation, upper limit threshold values for monitoring CoSupp can be established

Cytoskeletal Rearrangements in Synovial Fibroblasts as a Novel Pathophysiological Determinant of Modeled Rheumatoid Arthritis

Rheumatoid arthritis is a chronic inflammatory disease with a high prevalence and substantial socioeconomic burden. Despite intense research efforts, its aetiology and pathogenesis remain poorly understood. To identify novel genes and/or cellular pathways involved in the pathogenesis of the disease, we utilized a well-recognized tumour necrosis factor-driven animal model of this disease and performed high-throughput expression profiling with subtractive cDNA libraries and oligonucleotide microarray hybridizations, coupled with independent statistical analysis. This twin approach was validated by a number of different methods in other animal models of arthritis as well as in human patient samples, thus creating a unique list of disease modifiers of potential therapeutic value. Importantly, and through the integration of genetic linkage analysis and Gene Ontology–assisted functional discovery, we identified the gelsolin-driven synovial fibroblast cytoskeletal rearrangements as a novel pathophysiological determinant of the disease