Analyzing Semantic Properties of OCL Operations by Uncovering Interoperational Relationships

The OCL (Object Constraint Language) as part of the UML (Unified Modeling Language) is a rich language with different collection kinds (sets, multi-sets, sequences) and a large variety of operations defined thereon. Without negating the strong correlation between both fields we can say that these operations have their origin partly in logic (like the operations forAll and exists) and partly in computer science, in particular database systems (like the operation select). Some of these operations may be expressed in terms of other operations. This paper presents a systematic study of relationships which hold between OCL features like the mentioned operations. Apart from presenting the relationships between operations in a conceptual way, the relationships are described by a formal metamodel allowing systematic and computer supported access to the operation relationships by querying an underlying formal description

Large-x Parton Distributions

Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about "large-x" parton distributions, as well as recent measurements which have improved the parton uncertainties. Finally, we provide a status report of the data used in the global analysis, and note some of the open issues where future experiments, including those planned for Jefferson Labs, might contribute.Comment: LaTeX, 9 pages, 7 figures. Invited talk presented at the ``Workshop on Nucleon Structure in the High x-Bjorken Region (HiX2000),'' Temple University, Philadelphia, Pennsylvania, March 30-April 1, 200

OCL-based Runtime Monitoring of JVM hosted Applications

In this paper we present an approach that enables users to monitor and verify the behavior of an application running on a virtual machine at the model level. Concrete implementations of object-oriented software usually contain a lot of technical classes. Thus, the central parts of an application, e.g., the business rules, may be hidden among peripheral functionality like user-interface classes or classes managing persistency. Our approach makes use of modern virtual machines and allows the devloper to profile an application in order to achieve an abstract monitoring and verification of central application components. We represent virtual machine bytecode in form of a so-called platform-aligned model (PAM) comprising OCL invariants and pre- and postconditions. In contrast to related work, our approach uses the original source or bytecode of the monitored application as it stands and does not require any changes. We show a prototype implementation as an extension of the UML and OCL tool USE. Also, we investigate the impact of our approach to the execution time of a monitored system

Optimierte Suche von Modellinstanzen UML/OCL-Beschreibungen in USE

National audienceKonzeptuelle Modelle sind ein wichtiges Element modellgetriebener Softwareentwicklung, sowohl in der Beschreibung von Systemen als auch in der Metamodellierung domänenspezifischer Sprachen. Zu ihrer Beschreibung haben sich UML und OCL (und angelehnte Sprachen) als ein de facto Standard durchgesetzt. Validierung und Verifikation der Modelle sind hierbei wichtige Instrumente zur Sicherstellung der Modellqualität. Die Sprache ASSL (A Snapshot Sequence Language) bietet die Möglichkeit durch imperative Programmierung auf Modellebene und Backtracking konforme Instanzen systematisch zu erzeugen. Der White-Box-Ansatz ASSL ergänzt Black-Box-Ansätze, welche die Modellinstanziierung durch Abbildung auf (bspw.) ein Problem der relationalen Logik lösen. Dieser Beitrag beschreibt, wie die durch ASSL-Programme aufgespannten Suchräume durch Ausnutzung der Modellabdeckung der OCL-Constraints und der Modellstruktur erheblich verkleinert werden können und gibt einen Ausblick darauf, wie bestehende Black-Box-Ansätze in ASSL integriert werden können, um innerhalb eines imperativen Rahmens Teilinstanziierungen deklarativ beschreiben zu können

Abstract runtime monitoring with USE

Adsorption and photodecomposition of formic acid on rutile TiO2 (110) have been investigated with infrared reflection–absorption spectroscopy (IRRAS) employing p- and s-polarized light along the [001] and [ 11⎯⎯0 ] crystal directions. The single crystal surfaces were prepared either by sputtering and annealing in ultrahigh vacuum (UHV) to obtain a reduced surface (r-TiO2), or by sputtering without annealing to create a rough, highly defective surface (sp-TiO2). Results are compared with corresponding measurements on rutile nanocrystals performed in synthetic air. IRRAS spectra obtained on r-TiO2 and rutile nanocrystals are very similar, and show that in both cases formic acid dissociates and is predominately adsorbed as a bridging bidentate formate species, and that the formate adsorption structure on the nanocrystals is dominated by interactions with majority (110) surfaces. In contrast, the IRRAS spectra on sp-TiO2 are different, with only minor spectral features associated with (110) surfaces and lost azimuthal symmetry, both of which imply changed adsorption geometry due to bonding to low-coordinated Ti atoms with lower valences. The UV-induced rate of formate photodecomposition is about 30 times higher on rutile nanocrystals in synthetic air compared with sp-TiO2 under UHV conditions, and even larger than on r-TiO2. These differences are explained by the lack of oxygen and limited hydroxyl coverage under UHV conditions. The difference in reactivity between the r-TiO2 and sp-TiO2 surfaces is attributed to a high concentration of strongly bonded bridging bidentate formate species on the (110) surface, which lowers its reactivity. The results point to a pressure gap where the availability of molecular oxygen and the hydroxyl concentration limit the photoreactivity in UHV leading to an almost 20-fold decrease of the formate degradation rate in UHV. In contrast, the structure represented by the single crystal (110) surface is shown to capture the essential structural properties, which dictates the formic acid adsorption and adsorption structure of rutile nanocrystals

Evaluation of renal Kt/V as a marker of renal function in predialysis patients

Evaluation of renal Kt/V as a marker of renal function in predialysis patients.BackgroundThe use of renal Kt/V (r-Kt/V) as an indicator for the need of dialysis initiation has been recommended in the NKF-DOQI guidelines. In analogy to clinical practice in peritoneal dialysis, a fall of r-Kt/V below a threshold of 2.0 per week may indicate inadequate renal toxin elimination. However, there are no studies linking r-Kt/V with other parameters of glomerular filtration rate (GFR) in predialysis patients, and the validity of r-Kt/V as parameter for timing of dialysis initiation is unknown.MethodsRenal function was assessed repeatedly in 125 patients (N = 465 measurements). In predialysis patients (r-Kt/V <2.5 per week) r-Kt/V was compared with creatinine [CCr], urea [CUr], averaged creatinine/urea clearance [CCr/Ur], Cockcroft-Gault formula [CCG], and MDRD prediction equation 6 (MDRD6-GFR). The diagnostic performance of r-Kt/V as a parameter for timing the initiation of dialysis was evaluated.ResultsRenal Kt/V <2.5 was prevalent in 24.9% of cases (N = 116, mean 1.92 ± 0.34). In this group mean CCr was 13.8 ± 4.9, mean CUr 6.7 ± 1.3, and CCr/Ur 10.2 ± 2.9mL/min/1.73m2. There was no correlation of r-Kt/V with serum creatinine and MDRD6-GFR, but a significantly positive correlation with CCr/Ur (r2 = 0.3382, P < 0.001). Sensitivity of r-Kt/V to detect CCr/Ur < 10.5mL/min/1.73m2, defined as the threshold for dialysis initiation, was 73.6% with a specificity of 91.9%.ConclusionsThese results suggest that r-Kt/V is a parameter of acceptable specificity but poor sensitivity for the timing of dialysis initiation. Additional measures of renal function, such as the average of measured creatinine and urea clearance, also should be taken into consideration when deciding on the timing of dialysis initiation prior to the development of clinical signs of uremia and malnutrition

New Bounds for the Integer Carath\'{e}odory Rank

Given a pointed rational $n$-dimensional cone $C$, we obtain new parametric and asymptotic upper bounds for the integer Carath\'{e}odory rank $\operatorname{CR}(C)$, defined as the smallest integer $k$ such that any integer vector in $C$ can be expressed as a non-negative integer combination of at most $k$ elements from the Hilbert basis of $C$. Firstly, we significantly improve previously known bounds on the integer Carath\'{e}odory rank in an asymptotic setting, where we only consider "most" integer vectors in $C$. Secondly, we show that the equality $\operatorname{CR}(C)=n$, referred to as the integer Carath\'{e}odory property, holds in arbitrary dimension for cones that possess polyhedral representations with bimodular matrices. Furthermore, we obtain a new upper bound on $\operatorname{CR}(C)$ for simplicial cones represented by $k$-modular matrices with $k \le n$. Similar results are established for cones represented by generating sets

Methodologische Grenzziehungen und methodenintegrative Ansätze: Mixed Methods in der Arbeits- und Industriesoziologie sowie der Arbeitsmarktforschung

Methodologische Grenzziehungen in der Arbeitsforschung werden am Beispiel der eher qualitativ orientierten Arbeits- und Industriesoziologie und der primär quantitativ ausgerichteten Arbeitsmarktforschung nachgezeichnet: Während die Anfänge der Arbeitsforschung (z.B. Marienthal-Studie) aus pragmatischen Erwägungen heraus teilweise methodenplural angelegt waren, etablierten sich in der Nachkriegszeit infolge der zunehmenden disziplinären Ausdifferenzierung und der methodologischen Weiterentwicklungen unterschiedliche Forschungs-Communities. Die deutsche Arbeits- und Industriesoziologie fokussiert auf die Erforschung neuer Arbeitsformen, den Wandel der Arbeit und dessen Verarbeitung durch die Subjekte. Sie zeichnet sich überwiegend durch einen verstehenden Zugang aus, in dem Fallstudien eine zentrale Rolle spielen. Die Arbeitsmarktforschung orientiert sich an der Untersuchung von Beschäftigungsverhältnissen, Arbeitsmarktbedingungen und ihren Folgen für Beschäftigte und Betriebe. Sie ist durch eine immer breitere und methodisch ausgefeiltere Nutzung von quantitativen Massendaten gekennzeichnet. Schon seit einer Weile sind in beiden Communities Öffnungsprozesse zu beobachten, welche die komplementären Erkenntnisinteressen in den Vordergrund stellen und die Verwendung methodenintegrativer Designs fördern. Mittlerweile finden sich eine Reihe von Studien, in denen qualitative und quantitative Methoden kombiniert wurden, die methodologische Reflexion methodenintegrativer Forschung steht jedoch noch in den Anfängen. Am Beispiel eigener Projekte aus der Arbeits- und Industriesoziologie sowie der Arbeitsmarktforschung wird daher reflektiert, wie die bisherigen Erfahrungen mit methodenintegrativer Forschung aussehen, und welche Perspektiven sich in diesem Feld abzeichnen

Wirkmächtige Diskurse - betriebliche Auseinandersetzungen um Digitalisierung

Auseinandersetzungen um die Digitalisierung der Arbeitswelt werden auch über Diskurse ausgetragen. Wie Wettbewerbsaspekte, Regulierungsfragen, Chancen und Risiken von Digitalisierung in betrieblichen Konflikten um den digitalen Wandel in Stellung gebracht werden, hat Einfluss auf den Ausgang von Auseinandersetzungen und Aushandlungen. Vor diesem Hintergrund untersucht der Beitrag anhand von drei zentralen betrieblichen Handlungsfeldern der Digitalisierung (neue Arbeitsformen, Automatisierung, Überwachung), welche Diskurse in diesen Auseinandersetzungen wie aufgegriffen und wirkmächtig werden. Dabei zeigt sich, dass es der Arbeitgeberseite gelingt, Diskursstrategien zu verfolgen, die sie gegenüber Betriebsräten und Gewerkschaften in die Offensive bringt.Conflicts about the digitalisation of the world of work are also carried out via discourses. How competition aspects, regulatory issues, opportunities and risks of digitalisation are positioned in company conflicts over digital change influences the outcome of disputes and negotiations. Against this background, the article examines which discourses are taken up and how they become effective in these disputes on the basis of three central fields of action of digitalisation (new forms of work, automation, surveillance). It is shown that the employers’ side succeeds in pursuing discourse strategies that put them on the offensive against works councils and trade unions