585 research outputs found

    Programmability of Chemical Reaction Networks

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    Motivated by the intriguing complexity of biochemical circuitry within individual cells we study Stochastic Chemical Reaction Networks (SCRNs), a formal model that considers a set of chemical reactions acting on a finite number of molecules in a well-stirred solution according to standard chemical kinetics equations. SCRNs have been widely used for describing naturally occurring (bio)chemical systems, and with the advent of synthetic biology they become a promising language for the design of artificial biochemical circuits. Our interest here is the computational power of SCRNs and how they relate to more conventional models of computation. We survey known connections and give new connections between SCRNs and Boolean Logic Circuits, Vector Addition Systems, Petri Nets, Gate Implementability, Primitive Recursive Functions, Register Machines, Fractran, and Turing Machines. A theme to these investigations is the thin line between decidable and undecidable questions about SCRN behavior

    Strategy-proof Sharing

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    We consider the problem of sharing a divisible good, where agents prefer more to less. First, we prove that a sharing rule satisfies strategy proofness if and only if it has the quasi-constancy property: no one changes her own share by changing her announcements. Next, by constructing a system of linear equations in a manner that is consistent with quasi-constancy, we provide a way to find every strategy-proof sharing rule. Finally, we identify a necessary and sufficient condition for the existence of non-constant, strategy-proof sharing rules, by examining the relationship between the constancy of strategy-proof sharing rules and the dimension of the solution space of the linear system.Strategy-proofness, Bossiness, Non-constancy, Quasi-constancy.

    Developing a conformance methodology for clinically-defined medical record headings:a preliminary report.

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    Background: The Professional Records Standards Body for health and social care (PRSB) was formed in 2013 to develop and assure professional standards for the content and structure of patient records across all care disciplines in the UK. Although the PRSB work is aimed at Electronic Health Record (EHR) adoption and interoperability to support continuity of care, the current technical guidance is limited and ambiguous. Objectives: This project was initiated as a proof-ofconcept to demonstrate whether, and if so, how, conformance methods can be developed based on the professional standards. Methods: An expert group was convened, comprising clinical and technical representatives. A constrained data set was defined for an outpatient letter, using the subset of outpatient headings that are also present in the ep-SOS patient summary. A mind map was produced for the main sections and sub-sections. An openEHR archetype model was produced as the basis for creating HL7 and IHE implementation artefacts. Results: Several issues about data definition and representation were identified when attempting to map the outpatient headings to the epSOS patient summary, partly due to the difference between process and static viewpoints. Mind maps have been a simple and helpful way to visualize the logical information model and expose and resolve disagreements about which headings are purely for human navigation and which, if any, have intrinsic meaning. Conclusions: Conformance testing is feasible but nontrivial. In contrast to traditional standards-development timescales, PRSB needs an agile standards development process with EHR vendor and integrator collaboration to ensure implementability and widespread adoption. This will require significant clinical and technical resources

    Towards a Coherent Theory of Physics and Mathematics

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    As an approach to a Theory of Everything a framework for developing a coherent theory of mathematics and physics together is described. The main characteristic of such a theory is discussed: the theory must be valid and and sufficiently strong, and it must maximally describe its own validity and sufficient strength. The mathematical logical definition of validity is used, and sufficient strength is seen to be a necessary and useful concept. The requirement of maximal description of its own validity and sufficient strength may be useful to reject candidate coherent theories for which the description is less than maximal. Other aspects of a coherent theory discussed include universal applicability, the relation to the anthropic principle, and possible uniqueness. It is suggested that the basic properties of the physical and mathematical universes are entwined with and emerge with a coherent theory. Support for this includes the indirect reality status of properties of very small or very large far away systems compared to moderate sized nearby systems. Discussion of the necessary physical nature of language includes physical models of language and a proof that the meaning content of expressions of any axiomatizable theory seems to be independent of the algorithmic complexity of the theory. G\"{o}del maps seem to be less useful for a coherent theory than for purely mathematical theories because all symbols and words of any language musthave representations as states of physical systems already in the domain of a coherent theory.Comment: 38 pages, earlier version extensively revised and clarified. Accepted for publication in Foundations of Physic

    The political districting problem: A survey

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    Computer scientists and social scientists consider the political districting problem from different viewpoints. This paper gives an overview of both strands of the literature on districting in which the connections and the differences between the two approaches are highlighted

    THE IMPLEMENTABILITY OF WESTERN APPROACHES IN EASTERN SOCIETIES

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    The field of foreign language teaching has been dominated mostly by Western views. While some of these views can indeed be implemented, many others, especially with regards to the role of the teacher and that of the students, stumble on cultural barriers; the approaches are also constrained by the unavailability of educational facilities in most Eastern societies. This paper is to look into these two constraints: (a) in the case of learner autonomy and the new role of the teacher, the Western concepts cannot  be conveniently implemented without changing the cultural values of the society, and (b) in the case of educational facilities, Western approaches such as  Community Language Learning, Total Physical Response, Suggestopedy, and Content-based Instruction, which are claimed to be student-centered, cannot easily be implemented in normal classrooms where educational aids  are not generally available on the national scope.Keywords: learner autonomy, Community Language Learning, Total Physical Response, Suggestopedy, Content-based Instruction.  

    Strategy-proof Sharing

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    Contracts for Systems Design: Theory

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    Aircrafts, trains, cars, plants, distributed telecommunication military or health care systems,and more, involve systems design as a critical step. Complexity has caused system design times and coststo go severely over budget so as to threaten the health of entire industrial sectors. Heuristic methods andstandard practices do not seem to scale with complexity so that novel design methods and tools based on astrong theoretical foundation are sorely needed. Model-based design as well as other methodologies suchas layered and compositional design have been used recently but a unified intellectual framework with acomplete design flow supported by formal tools is still lacking.Recently an “orthogonal” approach has been proposed that can be applied to all methodologies introducedthus far to provide a rigorous scaffolding for verification, analysis and abstraction/refinement: contractbaseddesign. Several results have been obtained in this domain but a unified treatment of the topic that canhelp in putting contract-based design in perspective is missing. This paper intends to provide such treatmentwhere contracts are precisely defined and characterized so that they can be used in design methodologiessuch as the ones mentioned above with no ambiguity. In addition, the paper provides an important linkbetween interface and contract theories to show similarities and correspondences.This paper is complemented by a companion paper where contract based design is illustrated throughuse cases

    Lecturers' views of curriculum change at English Language Teaching departments in Turkey

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    ArticleThis study seeks to understand lecturers’ views about the effectiveness of curriculum change procedures taking place in 2006 at the English language teacher education departments of Turkish universities. The study collected both quantitative and qualitative data through an open-ended questionnaire completed by 27 lecturers working at fifteen different universities and semi-structured interviews with five of the participants. The results indicated that lecturers did not have voice during the change process and were not well informed about the changes. The change process was reported to disregard some important steps of curriculum development such as needs analysis, teacher training, and evaluation. With regard to course-specific changes, the 2006 curriculum was reported to be effective in involving practical courses. Combining separate literature courses, adding a vocabulary course, and extending class hours of some courses were found to be effective changes. Conversely, removing skill-based courses, decreasing class hours of the research skills course, combining advanced reading and writing courses, and removing school experience course were reported as negative aspects of the 2006 curriculum change. Considering these findings, a number of suggestions are made to achieve effective curriculum change at English Language Teaching Departments
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