93,666 research outputs found

    Efficient Energy Transport in Photosynthesis: Roles of Coherence and Entanglement

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    Recently it has been discovered---contrary to expectations of physicists as well as biologists---that the energy transport during photosynthesis, from the chlorophyll pigment that captures the photon to the reaction centre where glucose is synthesised from carbon dioxide and water, is highly coherent even at ambient temperature and in the cellular environment. This process and the key molecular ingredients that it depends on are described. By looking at the process from the computer science view-point, we can study what has been optimised and how. A spatial search algorithmic model based on robust features of wave dynamics is presented.Comment: 6 pages, 3 figures, to appear in the proceedings of the Symposium "75 Years of Quantum Entanglement: Foundations and Information Theoretic Applications", January 2011, Kolkata, Indi

    Surface-renewal models for heat-transfer between walls and fluidized beds

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    Two surface-renewed film penetration models describe transient heat-transfer between a wall and a fluidized bed. Methods are presented for estimation of mean residence times of particles at the transporting surface, their age densities and the average transport coefficients

    Autonomic computing architecture for SCADA cyber security

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    Cognitive computing relates to intelligent computing platforms that are based on the disciplines of artificial intelligence, machine learning, and other innovative technologies. These technologies can be used to design systems that mimic the human brain to learn about their environment and can autonomously predict an impending anomalous situation. IBM first used the term ‘Autonomic Computing’ in 2001 to combat the looming complexity crisis (Ganek and Corbi, 2003). The concept has been inspired by the human biological autonomic system. An autonomic system is self-healing, self-regulating, self-optimising and self-protecting (Ganek and Corbi, 2003). Therefore, the system should be able to protect itself against both malicious attacks and unintended mistakes by the operator

    Narrating the past: virtual environments and narrative

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    This paper explores how traditional narrative language used in film and theatre can be adapted to create interactivity and a greater sense of presence in the virtual heritage environment. It focuses on the fundamental principles of narrative required to create immersion and presence and investigates methods of embedding intangible social histories into these environments. These issues are explored in a case study of Greens Mill in the 1830’s, interweaving the story of the reform bill riots in Nottingham with the life of George Green, mathematician and proprietor of the Mill

    Eta-nucleon and eta-prime-nucleon coupling constants in QCD and the role of gluons

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    Coupling constants of η\eta and η\eta^{\prime} mesons with nucleons have been calculated using the method of QCD sum rules. Starting from vacuum-to-meson correlation function of interpolating fields of two nucleons, its matrix element with respect to nucleon spinors has been considered. Coupling constants at the physical points have been estimated from extrapolation of results obtained at two other points. Anomalous glue has been found to give substantial contribution to the coupling constants and also accounts for a significant OZI-rule violation.Comment: 6 pages, 3 figures and 2 table

    Zariski Closures and Subgroup Separability

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    The main result of this article is a refinement of the well-known subgroup separability results of Hall and Scott for free and surface groups. We show that for any finitely generated subgroup, there is a finite dimensional representation of the free or surface group that separates the subgroup in the induced Zariski topology. As a corollary, we establish a polynomial upper bound on the size of the quotients used to separate a finitely generated subgroup in a free or surface group.Comment: Final version. To appear in Selecta Mat

    Towards Understanding the Origin of Genetic Languages

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    Molecular biology is a nanotechnology that works--it has worked for billions of years and in an amazing variety of circumstances. At its core is a system for acquiring, processing and communicating information that is universal, from viruses and bacteria to human beings. Advances in genetics and experience in designing computers have taken us to a stage where we can understand the optimisation principles at the root of this system, from the availability of basic building blocks to the execution of tasks. The languages of DNA and proteins are argued to be the optimal solutions to the information processing tasks they carry out. The analysis also suggests simpler predecessors to these languages, and provides fascinating clues about their origin. Obviously, a comprehensive unraveling of the puzzle of life would have a lot to say about what we may design or convert ourselves into.Comment: (v1) 33 pages, contributed chapter to "Quantum Aspects of Life", edited by D. Abbott, P. Davies and A. Pati, (v2) published version with some editin
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