1,589 research outputs found

    A DAI approach to modeling the transportation domain

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    A central problem in the study of autonomous cooperating systems is that of how to establish mechanisms for controlling the interactions between different parts (which are called agents) of the system. One way to integrate such mechanisms into a multi-agent system is to exploit the technique of cooperation or negotiation protocols. In a protocol we distinguish to essential layers: the communication layer specifying the possible flow of messages between different agents, and the decision layer, which controls the selection of a message (speech-act) that the agent sends in a specific situation. In this report we first give a short introduction of our agent model InteRRap which provides the basis for the modeling of the different scenarios considered in the AKA-Mod project at the DFKI. The techniques we will discuss in the following are located in the plan based component and in the cooperation component of this model. The domain of application is the MARS scenario (Modeling a Multi-Agent Scenario for Shipping Companies) which implements a group of shipping companies whose goal it is to deliver a set of dynamically given orders, satisfying a set of given time and/or cost constraints. The complexity of the orders may exceed the capacities of a single company. Therefore, cooperation between companies is required in order to achieve the goal in a satisfactory way. This domain is of considerable interest for studies with economical background as well as for research projects. We give a short summary of results from economical studies that are concerned with the real-world situation in Germany in the transportation domain. They show the need for the development of new techniques from the field of computer science to tackle the problems therein. Then, an overview on related research is presented. Two approaches are discussed in more detail: the first one being based on OR-techniques and a second one being based on the concept of partial intelligent agents attempting to integrate techniques from OR and DAI. Both approaches are concerned with the situation in a single company. However, our purpose to handle the case of distributed shipping companies requires additional mechanisms, e.g. to cope with the problems of task allocation and task decomposition in multi-agent systems. Mechanisms for distributed task decomposition and task allocation processes in multi-agent systems belong to the core of our studies. Therefore, we will first discuss techniques for these problems in a general setting and then describe their implementations in the MARS system. In this description, particular emphasis is placed on the cooperation within a shipping company. Here, one company agent has to allocate a set of orders its truck agents. The truck agents support the company agents by giving cost estimations based on their route planning facility. Thus, this procedure provides the basis for the decisions of the company agents and is discussed in very detail. Finally, we present results from a series of benchmark tests. The test sets have also been run with OR-implementations and thus, give us the opportunity to compare our implementation against these approaches

    Rising longevity, increasing the retirement age, and the consequences for knowledge-based long-run growth

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    We assess the long-run growth effects of rising longevity and increasing the retirement age when growth is driven by purposeful research and development. In contrast to economies in which growth depends on learning-by-doing spillovers, raising the retirement age fosters economic growth. How economic growth changes in response to rising life expectancy depends on the retirement response. Employing numerical analysis we find that the requirement for experiencing a growth stimulus from rising longevity is fulfilled for the United States, nearly met for the average OECD economy, but missed by the EU and by Japan

    Effects of Progesterone and Its Antagonist Mifepristone on Progesterone Receptor A Expression in Human Umbilical Vein Endothelial Cells

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    Effects of female steroid hormones on endothelial cells are gaining increased importance due to several studies on the effects of hormonal treatment on cardiovascular risk. Recent data argue for an improvement of endothelium-derived relaxation and impaired vascular contraction by estradiol, whereas progesterone and testosterone might entail contrary effects. So far, gestagenic influence on endothelial cell physiology is poorly understood. Human umbilical vein endothelial cells (HUVECs) exposed to the female sex hormones estradiol and progesterone show expression of estrogen receptor-beta (ER beta) and progesterone receptor A (PR-A), and are negative for ER alpha and PR-B. The aim of this study was to analyze the expression and stimulation of PR-A and -B in HUVECs after stimulation with progesterone and PR antagonists that are commercially available. PR-B expression or upregulation was abrogated after application of progesterone or antagonists to HUVECs. Expression of PR-A could be significantly upregulated with progesterone and mifepristone. Unexpectedly, stimulation with the progesterone antagonist RU486 (mifepristone) was accomplished by an upregulation of PR-A expression in our study. We conclude that gestagenic effects on HUVECs independent of modulators are mediated via the PR-A. Copyright (C) 2009 S. Karger AG, Base

    Clinical Workflows - The Killer Application for Process-oriented Information Systems?

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    There is an increasing interest in changing information systems to support business processes in a more direct way. Workflow technology is a very interesting candidate to achieve this goal. Hence the important question arises, how far do we get using this technology. Is its functionality powerful enough to support a wide range of applications or is it only suitable for rather simple ones? And, if the latter is the case, are the missing functions of the “just to do” type or are more fundamental issues addressed? The paper uses the clinical domain to motivate and to elaborate the functionality needed to adequately support an advanced application environment. It shows that workflow technology is still lacking important features to serve this domain. The paper surveys the state of the art and it presents solutions for some issues based on the concepts elaborated in the ADEPT project

    Representation of Medical Guidelines Using a Classification-Based System

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    Medical guidelines play an increasing role in selecting diag-nostic and therapeutic steps under the aspects of effectiveness, invasiveness, and costs. To work directly on patient data already available in electronic form, they should be integrated into a medical Information System. In order to develop a "medical guideline module" (MGM) managing and applying guidelines to patients, a "knowledge level" representation of guidelines is necessary which reflects the structure of medical knowledge and matches medical processes. Furthermore, a direct transformation to the "symbol level" is needed. We use a nested, frame-like structure on the knowledge level and show that a classification-based knowledge representation system (CBKRS) is principally well suited for the symbol level. To facilitate the usage and to be independent of a particular CBKRS, we introduce an intermediate level called "intelligent object system" (IOS). It is developed by augmenting a simple data model for describing complex objects with prototypes and implications as a means to classify objects and to draw inferences based on this Classification. Finally, the transformation of guidelines to prototypes and implications is described

    Optically driven ultra-stable nanomechanical rotor

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    Nanomechanical devices have attracted the interest of a growing interdisciplinary research community, since they can be used as highly sensitive transducers for various physical quantities. Exquisite control over these systems facilitates experiments on the foundations of physics. Here, we demonstrate that an optically trapped silicon nanorod, set into rotation at MHz frequencies, can be locked to an external clock, transducing the properties of the time standard to the rod's motion with the remarkable frequency stability fr/Δfrf_{\rm r}/\Delta f_{\rm r} of 7.7×10117.7 \times 10^{11}. While the dynamics of this periodically driven rotor generally can be chaotic, we derive and verify that stable limit cycles exist over a surprisingly wide parameter range. This robustness should enable, in principle, measurements of external torques with sensitivities better than 0.25zNm, even at room temperature. We show that in a dilute gas, real-time phase measurements on the locked nanorod transduce pressure values with a sensitivity of 0.3%.Comment: 5 pages, 4 figure

    Probing Macroscopic Quantum Superpositions with Nanorotors

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    Whether quantum physics is universally valid is an open question with far-reaching implications. Intense research is therefore invested into testing the quantum superposition principle with ever heavier and more complex objects. Here we propose a radically new, experimentally viable route towards studies at the quantum-to-classical borderline by probing the orientational quantum revivals of a nanoscale rigid rotor. The proposed interference experiment testifies a macroscopic superposition of all possible orientations. It requires no diffraction grating, uses only a single levitated particle, and works with moderate motional temperatures under realistic environmental conditions. The first exploitation of quantum rotations of a massive object opens the door to new tests of quantum physics with submicron particles and to quantum gyroscopic torque sensors, holding the potential to improve state-of-the art devices by many orders of magnitude.Comment: 15 pages, 4 figure

    Evaluation of a Novel Anti-Mucin 1 (MUC1) Antibody (PankoMab) as a Potential Diagnostic Tool in Human Ductal Breast Cancer; Comparison with Two Established Antibodies

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    Aim: PankoMab is a novel antibody that recognizes a tumor-specific epitope of Mucin 1 (MUC1). The aim of this study was the evaluation of PankoMab as a potential diagnostic tool and its comparison with two established antibodies against MUC1 in human ductal breast cancer. Materials and Methods: Breast carcinomas were obtained from 82 patients. MUC1 expression and hormone receptor status were determined by immunohistochemistry of paraffin-embedded material. Results: PankoMab revealed strong correlation to hormone receptor expression. DF3 showed no correlation with grading, lymph node involvement and/or estrogen receptor (ER) expression. In the subgroup of lymph node-positive and ER-negative tumors, we saw a significantly reduced DF3 staining in G3 tumors compared to G2 tumors. VU-4-H5 showed increased staining intensity in correlation with increased grading. In addition, we also identified a significantly higher expression of the VU-4-H5 epitope in lymph node-positive carcinomas compared to carcinomas without lymph node involvement. Conclusion: PankoMab revealed strong correlation to hormone receptor expression in ductal carcinoma of the breast. VU-4-H5 showed increased staining intensity in correlation with increased grading and lymph node involvement. PankoMab and VU-4-H5 staining could be a useful combination in ductal breast cancer prognosis by immunohistochemistry
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