1,414 research outputs found

    Use of radiobiological modeling in treatment plan evaluation and optimization of prostate cancer radiotherapy

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    There are many tools available that are used to evaluate a radiotherapy treatment plan, such as isodose distribution charts, dose volume histograms (DVH), maximum, minimum and mean doses of the dose distributions as well as DVH point dose constraints. All the already mentioned evaluation tools are dosimetric only without taking into account the radiobiological characteristics of tumors or OARs. It has been demonstrated that although competing treatment plans might have similar mean, maximum or minimum doses they may have significantly different clinical outcomes (Mavroidis et al. 2001). For performing a more complete treatment plan evaluation and comparison the complication-free tumor control probability (P+) and the biologically effective uniform dose (D ) have been proposed (Källman et al. 1992a, Mavroidis et al. 2000). The D concept denotes that any two dose distributions within a target or OAR are equivalent if they produce the same probability for tumor control or normal tissue complication, respectively (Mavroidis et al. 2001)..

    Model checking quantum protocols

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    This thesis describes model checking techniques for protocols arising in quantum information theory and quantum cryptography. We discuss the theory and implementation of a practical model checker, QMC, for quantum protocols. In our framework, we assume that the quantum operations performed in a protocol are restricted to those within the stabilizer formalism; while this particular set of operations is not universal for quantum computation, it allows us to develop models of several useful protocols as well as of systems involving both classical and quantum information processing. We detail the syntax, semantics and type system of QMC’s modelling language, the logic QCTL which is used for verification, and the verification algorithms that have been implemented in the tool. We demonstrate our techniques with applications to a number of case studies

    Ballistic Spin Injection from Fe into ZnSe and GaAs with a (001), (111), and (110) orientation

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    We present first-principles calculations of ballistic spin injection in Fe/GaAs and Fe/ZnSe junctions with orientation (001), (111), and (110). We find that the symmetry mismatch of the Fe minority-spin states with the semiconductor conduction states can lead to extremely high spin polarization of the current through the (001) interface for hot and thermal injection processes. Such a symmetry mismatch does not exist for the (111) and (110) interfaces, where smaller spin injection efficiencies are found. The presence of interface states is found to lower the current spin polarization, both with and without a Schottky barrier. Finally, a higher bias can also affect the spin injection efficiency.Comment: 12 pages, 18 figure

    Energy efficiency parametric design tool in the framework of holistic ship design optimization

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    Recent International Maritime Organization (IMO) decisions with respect to measures to reduce the emissions from maritime greenhouse gases (GHGs) suggest that the collaboration of all major stakeholders of shipbuilding and ship operations is required to address this complex techno-economical and highly political problem efficiently. This calls eventually for the development of proper design, operational knowledge, and assessment tools for the energy-efficient design and operation of ships, as suggested by the Second IMO GHG Study (2009). This type of coordination of the efforts of many maritime stakeholders, with often conflicting professional interests but ultimately commonly aiming at optimal ship design and operation solutions, has been addressed within a methodology developed in the EU-funded Logistics-Based (LOGBASED) Design Project (2004–2007). Based on the knowledge base developed within this project, a new parametric design software tool (PDT) has been developed by the National Technical University of Athens, Ship Design Laboratory (NTUA-SDL), for implementing an energy efficiency design and management procedure. The PDT is an integral part of an earlier developed holistic ship design optimization approach by NTUA-SDL that addresses the multi-objective ship design optimization problem. It provides Pareto-optimum solutions and a complete mapping of the design space in a comprehensive way for the final assessment and decision by all the involved stakeholders. The application of the tool to the design of a large oil tanker and alternatively to container ships is elaborated in the presented paper

    Model checking quantum protocols

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    This thesis describes model checking techniques for protocols arising in quantum information theory and quantum cryptography. We discuss the theory and implementation of a practical model checker, QMC, for quantum protocols. In our framework, we assume that the quantum operations performed in a protocol are restricted to those within the stabilizer formalism; while this particular set of operations is not universal for quantum computation, it allows us to develop models of several useful protocols as well as of systems involving both classical and quantum information processing. We detail the syntax, semantics and type system of QMC’s modelling language, the logic QCTL which is used for verification, and the verification algorithms that have been implemented in the tool. We demonstrate our techniques with applications to a number of case studies.EThOS - Electronic Theses Online ServiceUniversity of Warwick. Dept. of Computer ScienceEngineering and Physical Sciences Research Council (Great Britain) (EPSRC) (GR/S34090/01, EP/E006833/2, GR/S86037/01)Sixth Framework Programme (European Commission) (SFP)Fundação para a Ciência ea Tecnologia (FCT) (POCI/MAT/55796/2004)Conselho de Reitores das Universidades Portuguesas (CRUP)GBUnited Kingdo

    SEASONAL VARIATION OF CHEMICAL COMPOSITION AND DRY MATTER DIGESTIBILITY OF RANGELANDS IN NW GREECE

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    This study was carried out to determine the chemical composition and in vitro dry matter digestibility of grazable material, during the growing season of plants, in three different altitudinal zones, in native rangelands, northwestern Greece. Samples were collected during the period from May to October of the years 2004 and 2005. Sample collection was accomplished by cutting aboveground biomass at a height similar to that grazed by small ruminants. The results showed that herbage production was significantly affected (P<0.001) by sampling year, growing season and altitudinal zone respectively, as well as (P<0.01) by the “month x year” and (P<0.05) “altitude x month” interactions. CP, ash, EE and CF content and IVDMD affected significantly (P<0.01) by both harvest month and altitudinal zone, while there was no significant affection by the sampling year and the interaction between altitude, month and year (except EE which affected (P<0.01) by the “month x year” interaction). Herbage production strongly related (P<0.01) to the altitude (r= +0.247), harvest month (r= -0.479) and CP content (r= -0.274). IVDMD related positively (P<0.01) to CP (r= +0.729), ash (r= +0.369) and EE (r= +0.351) content and negatively to harvest month (r= -0.779) and to CF content (r= -0.663). It was recommended that additional protein sources should be supplied in order to cover the needs of the grazing animals. It is necessary the transhumance of herds from lower to higher altitude for better utilization of rangelands
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