44 research outputs found

    Quantitative characterization of viscoelastic behavior in tissue-mimicking phantoms and ex vivo animal tissues.

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    Viscoelasticity of soft tissue is often related to pathology, and therefore, has become an important diagnostic indicator in the clinical assessment of suspect tissue. Surgeons, particularly within head and neck subsites, typically use palpation techniques for intra-operative tumor detection. This detection method, however, is highly subjective and often fails to detect small or deep abnormalities. Vibroacoustography (VA) and similar methods have previously been used to distinguish tissue with high-contrast, but a firm understanding of the main contrast mechanism has yet to be verified. The contributions of tissue mechanical properties in VA images have been difficult to verify given the limited literature on viscoelastic properties of various normal and diseased tissue. This paper aims to investigate viscoelasticity theory and present a detailed description of viscoelastic experimental results obtained in tissue-mimicking phantoms (TMPs) and ex vivo tissues to verify the main contrast mechanism in VA and similar imaging modalities. A spherical-tip micro-indentation technique was employed with the Hertzian model to acquire absolute, quantitative, point measurements of the elastic modulus (E), long term shear modulus (η), and time constant (τ) in homogeneous TMPs and ex vivo tissue in rat liver and porcine liver and gallbladder. Viscoelastic differences observed between porcine liver and gallbladder tissue suggest that imaging modalities which utilize the mechanical properties of tissue as a primary contrast mechanism can potentially be used to quantitatively differentiate between proximate organs in a clinical setting. These results may facilitate more accurate tissue modeling and add information not currently available to the field of systems characterization and biomedical research

    Efficient Compliance Checking Using BPMN-Q and Temporal Logic

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    Abstract. Compliance rules describe regulations, policies and quality constraints business processes must adhere to. Given the large number of rules and their frequency of change, manual compliance checking can be-come a time-consuming task. Automated compliance checking of process activities and their ordering is an alternative whenever business pro-cesses and compliance rules are described in a formal way. This paper introduces an approach for automated compliance checking. Compliance rules are translated into temporal logic formulae that serve as input to model checkers which in turn verify whether a process model satisfies the requested compliance rule. To address the problem of state-space explo-sion we employ a set of reduction rules. The approach is prototypically realized and evaluated.

    Design and Verification of Instantiable Compliance Rule Graphs in Process-Aware Information Systems

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    Abstract. For enterprises it has become crucial to check compliance of their business processes with certain rules such as medical guidelines or financial regulations. When automating compliance checks on pro-cess models, existing approaches have mainly addressed process-specific compliance rules so far, i.e., rules that correspond to a particular pro-cess model. However, in practice, we will rather find process-independent compliance rules that are nevertheless to be checked over process models. Thus, in this paper, we present an approach that enables the instantiation and verification of process-independent compliance rules over process models using domain models. For this, we provide an intuitive visualiza-tion of compliance rules and compliance rule instances at user level and show how rules and instances can be formalized and verified at system level. The overall approach is validated by a pattern-based comparison to existing approaches and by means of a prototypical implementation.

    Towards Compliance of Cross-Organizational Processes and their Changes

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    Businesses require the ability to rapidly implement new processes and to quickly adapt existing ones to environmental changes including the optimization of their interactions with partners and customers. However, changes of either intra- or cross-organizational processes must not be done in an uncontrolled manner. In particular, processes are increasingly subject to compliance rules that usually stem from security constraints, corporate guidelines, standards, and laws. These compliance rules have to be considered when modeling business processes and changing existing ones. While change and compliance have been extensively discussed for intra-organizational business processes, albeit only in an isolated manner, their combination in the context of cross-organizational processes remains an open issue. In this paper, we discuss requirements and challenges to be tackled in order to ensure that changes of cross-organizational business processes preserve compliance with imposed regulations, standards and laws
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