36 research outputs found

    Performance Measurement Systems Must Be Engineered

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    The aim of this paper, which puts special emphasis on IT-related aspects, is threefold. ·First, it defines requirements a modern Performance Measurements System (PMS) should meet. The list of requirements generated can be used both to assess a current PMS, and to identify ways to improve an existing PMS. ·Second, it reports the findings of an empirical study, which seeks to identify the shortcomings of existing PMSs. ·Third, a life cycle for PMSs is suggested

    Seeking the Goal in the Process, the Process for the Goal: Organizational Learning in a Public Sector Change Project

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    This paper describes how a combination of process modelling and goal modelling techniques has been used to facilitate organizational learning. The case study comes from the public sector in the UK. The modelling techniques have helped users to rationalise about the existing processes and then to design how they would like the process to work. The paper describes how the users have been able to confront the complex issues involved. The experience suggests that the combination of the modelling techniques is important to the learning experience of the users involved

    Symmetry-resolved entanglement detection using partial transpose moments

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    We propose an ordered set of experimentally accessible conditions for detecting entanglement in mixed states. The kk-th condition involves comparing moments of the partially transposed density operator up to order kk. Remarkably, the union of all moment inequalities reproduces the Peres-Horodecki criterion for detecting entanglement. Our empirical studies highlight that the first four conditions already detect mixed state entanglement reliably in a variety of quantum architectures. Exploiting symmetries can help to further improve their detection capabilities. We also show how to estimate moment inequalities based on local random measurements of single state copies (classical shadows) and derive statistically sound confidence intervals as a function of the number of performed measurements. Our analysis includes the experimentally relevant situation of drifting sources, i.e. non-identical, but independent, state copies.Comment: 11+11 pages, 6 figure

    T cell stimulator cells, an efficient and versatile cellular system to assess the role of costimulatory ligands in the activation of human T cells.

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    It is well established that full activation of T cells requires the interaction of the TCR complex with the peptide-MHC complex (Signal 1) and additional signals (Signal 2). These second signals are generated by the interaction of costimulatory ligands expressed on antigen presenting cells with activating receptors on T cells. In addition, T cell responses are negatively regulated by inhibitory costimulatory pathways. Since professional antigen presenting cells (APC) harbour a plethora of stimulating and inhibitory surface molecules, the contribution of individual costimulatory molecules is difficult to assess on these cells. We have developed a system of stimulator cells that can give signal 1 to human T cells via a membrane bound anti-CD3 antibody fragment. By expressing human costimulatory ligands on these cells, their role in T cell activation processes can readily be analyzed. We demonstrate that T cell stimulator cells are excellent tools to study various aspects of human T cell costimulation, including the effects of immunomodulatory drugs or how costimulatory signals contribute to the in vitro expansion of T cells. T cell stimulator cells are especially suited for the functional evaluation of ligands that are implicated in costimulatory processes. In this study we have evaluated the role of the CD2 family member CD150 (SLAM) and the TNF family member TL1A (TNFSF15) in the activation of human T cells. Whereas our results do not point to a significant role of CD150 in T cell activation we found TL1A to potently costimulate human T cells. Taken together our results demonstrate that T cell stimulator cells are excellent tools to study various aspects of costimulatory processes

    “Breaking up is hard to do”: the formation and resolution of sister chromatid intertwines

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    The absolute necessity to resolve every intertwine between the two strands of the DNA double helix provides a massive challenge to the cellular processes that duplicate and segregate chromosomes. Although the overwhelming majority of intertwines between the parental DNA strands are resolved during DNA replication, there are numerous chromosomal contexts where some intertwining is maintained into mitosis. These mitotic sister chromatid intertwines (SCIs) can be found as; short regions of unreplicated DNA, fully replicated and intertwined sister chromatids—commonly referred to as DNA catenation—and as sister chromatid linkages generated by homologous recombination-associated processes. Several overlapping mechanisms, including intra-chromosomal compaction, topoisomerase action and Holliday junction resolvases, ensure that all SCIs are removed before they can prevent normal chromosome segregation. Here, I discuss why some DNA intertwines persist into mitosis and review our current knowledge of the SCI resolution mechanisms that are employed in both prokaryotes and eukaryotes, including how deregulating SCI formation during DNA replication or disrupting the resolution processes may contribute to aneuploidy in cancer

    PICH promotes sister chromatid disjunction and co-operates with topoisomerase II in mitosis

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    PICH is a SNF2 family DNA translocase that binds to ultra-fine DNA bridges (UFBs) in mitosis. Numerous roles for PICH have been proposed from protein depletion experiments, but a consensus has failed to emerge. Here, we report that deletion of PICH in avian cells causes chromosome structural abnormalities, and hypersensitivity to an inhibitor of Topoisomerase II (Topo II), ICRF-193. ICRF-193-treated PICH-/- cells undergo sister chromatid non-disjunction in anaphase, and frequently abort cytokinesis. PICH co-localises with Topo IIα on UFBs and at the ribosomal DNA locus, and the timely resolution of both structures depends on the ATPase activity of PICH. Purified PICH protein strongly stimulates the catalytic activity of Topo II in vitro. Consistent with this, a human PICH-/- cell line exhibits chromosome instability and chromosome condensation and decatenation defects similar to those of ICRF-193-treated cells. We propose that PICH and Topo II cooperate to prevent chromosome missegregation events in mitosis

    Goal-Based Business Process Models: Creation and Evaluation

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    The paper gives an overview of an approach to modelling and evaluating business processes at conceptual level. We show which steps would be needed to create an object-oriented business process model, and how business process models can be evaluated against nonfunctional goals. Overall, we get some kind of guarantee that business process models are useful. They facilitate not only the communication between team members, they can be seen as an essential prerequisite for information system developers. Nevertheless, although models are useful we have to accept that an evaluation of a business process can only be partial if it is carried out at model level. Contents 1 Introduction................................................................................................................................. 2 2 Definitions................................................................................................................................... 3 3 The significance of goals and mode..
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