2,924 research outputs found

    COMPUTER SIMULATION AND COMPUTABILITY OF BIOLOGICAL SYSTEMS

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    The ability to simulate a biological organism by employing a computer is related to the ability of the computer to calculate the behavior of such a dynamical system, or the "computability" of the system.* However, the two questions of computability and simulation are not equivalent. Since the question of computability can be given a precise answer in terms of recursive functions, automata theory and dynamical systems, it will be appropriate to consider it first. The more elusive question of adequate simulation of biological systems by a computer will be then addressed and a possible connection between the two answers given will be considered. A conjecture is formulated that suggests the possibility of employing an algebraic-topological, "quantum" computer (Baianu, 1971b) for analogous and symbolic simulations of biological systems that may include chaotic processes that are not, in genral, either recursively or digitally computable. Depending on the biological network being modelled, such as the Human Genome/Cell Interactome or a trillion-cell Cognitive Neural Network system, the appropriate logical structure for such simulations might be either the Quantum MV-Logic (QMV) discussed in recent publications (Chiara, 2004, and references cited therein)or Lukasiewicz Logic Algebras that were shown to be isomorphic to MV-logic algebras (Georgescu et al, 2001)

    Novel Techniques and Their Applications to Health Foods, Agricultural and Medical Biotechnology: Functional Genomics and Basic Epigenetic Controls in Plant and Animal Cells

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    Selected applications of novel techniques for analyzing Health Food formulations, as well as for advanced investigations in Agricultural and Medical Biotechnology aimed at defining the multiple connections between functional genomics and epigenomic, fundamental control mechanisms in both animal and plant cells are being reviewed with the aim of unraveling future developments and policy changes that are likely to open new niches for Biotechnology and prevent the shrinking or closing of existing markets. Amongst the selected novel techniques with applications in both Agricultural and Medical Biotechnology are: immobilized bacterial cells and enzymes, microencapsulation and liposome production, genetic manipulation of microorganisms, development of novel vaccines from plants, epigenomics of mammalian cells and organisms, and biocomputational tools for molecular modeling related to disease and Bioinformatics. Both fundamental and applied aspects of the emerging new techniques are being discussed in relation to their anticipated, marked impact on future markets and present policy changes that are needed for success in either Agricultural or Medical Biotechnology. The novel techniques are illustrated with figures presenting the most important features of representative and powerful tools which are currently being developed for both immediate and long term applications in Agriculture, Health Food formulation and production, pharmaceuticals and Medicine. The research aspects are naturally emphasized in our review as they are key to further developments in Biotechnology; however, the course adopted for the implementation of biotechnological applications, and the policies associated with biotechnological applications are clearly the determining factors for future Biotechnology successes, be they pharmaceutical, medical or agricultural

    Metallic wafer bonding for the fabrication of long-wavelength vertical-cavity surface-emitting lasers

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    [[abstract]]A novel metallic bonding method using AuGeNiCr as the bonding medium was developed for the fabrication of long-wavelength vertical-cavity surface-emitting lasers (VCSELs). The metallic bonding process can be performed at a low temperature of 320 °C within 1 h and it does not require chemical-mechanical polishing or etching treatments on the bonding surfaces. As determined by atomic force microscopy, the process can tolerate a surface roughness of ∼10 nm on the surface of bonding samples. Cross-sectional transmission electron microscopy shows that the bonding interface is smooth and damage-free. Using this bonding technique, a 1.55 μm GaInAsP/InP VCSEL structure with Al-oxide/Si distributed Bragg reflectors was demonstrated on a Si substrate. No degradation was found on the bonded VCSEL structure after annealing at 420 °C. The reflectivity and resonance measured from the bonded VCSEL cavity confirmed the high optical quality provided by this bonding process for device fabrication.[[fileno]]2030161010042[[department]]電機工程學

    Understanding the beliefs and intentions in search and purchase functions in an e-commerce web site

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    10.1109/TEM.2008.922641IEEE Transactions on Engineering Management561106-114IEEM

    Outer Regions of the Milky Way

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    With the start of the Gaia era, the time has come to address the major challenge of deriving the star formation history and evolution of the disk of our MilkyWay. Here we review our present knowledge of the outer regions of the Milky Way disk population. Its stellar content, its structure and its dynamical and chemical evolution are summarized, focussing on our lack of understanding both from an observational and a theoretical viewpoint. We describe the unprecedented data that Gaia and the upcoming ground-based spectroscopic surveys will provide in the next decade. More in detail, we quantify the expect accuracy in position, velocity and astrophysical parameters of some of the key tracers of the stellar populations in the outer Galactic disk. Some insights on the future capability of these surveys to answer crucial and fundamental issues are discussed, such as the mechanisms driving the spiral arms and the warp formation. Our Galaxy, theMilkyWay, is our cosmological laboratory for understanding the process of formation and evolution of disk galaxies. What we learn in the next decades will be naturally transferred to the extragalactic domain.Comment: 22 pages, 10 figures, Invited review, Book chapter in "Outskirts of Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and Space Science Library, Springer, in pres

    Pharmacological treatments in pregnant women with psoriasis in the U.S.A.

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110872/1/bjd13306.pd

    Origin of Life

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    The evolution of life has been a big enigma despite rapid advancements in the fields of biochemistry, astrobiology, and astrophysics in recent years. The answer to this puzzle has been as mind-boggling as the riddle relating to evolution of Universe itself. Despite the fact that panspermia has gained considerable support as a viable explanation for origin of life on the Earth and elsewhere in the Universe, the issue remains far from a tangible solution. This paper examines the various prevailing hypotheses regarding origin of life like abiogenesis, RNA World, Iron-sulphur World, and panspermia; and concludes that delivery of life-bearing organic molecules by the comets in the early epoch of the Earth alone possibly was not responsible for kick-starting the process of evolution of life on our planet.Comment: 32 pages, 8 figures,invited review article, minor additio

    A threshold phenomenon for embeddings of H0mH^m_0 into Orlicz spaces

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    We consider a sequence of positive smooth critical points of the Adams-Moser-Trudinger embedding of H0mH^m_0 into Orlicz spaces. We study its concentration-compactness behavior and show that if the sequence is not precompact, then the liminf of the H0mH^m_0-norms of the functions is greater than or equal to a positive geometric constant.Comment: 14 Page

    Nonlinear r-Modes in Neutron Stars: Instability of an unstable mode

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    We study the dynamical evolution of a large amplitude r-mode by numerical simulations. R-modes in neutron stars are unstable growing modes, driven by gravitational radiation reaction. In these simulations, r-modes of amplitude unity or above are destroyed by a catastrophic decay: A large amplitude r-mode gradually leaks energy into other fluid modes, which in turn act nonlinearly with the r-mode, leading to the onset of the rapid decay. As a result the r-mode suddenly breaks down into a differentially rotating configuration. The catastrophic decay does not appear to be related to shock waves at the star's surface. The limit it imposes on the r-mode amplitude is significantly smaller than that suggested by previous fully nonlinear numerical simulations.Comment: Published in Phys. Rev. D Rapid Comm. 66, 041303(R) (2002
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