861 research outputs found

    Quantum Search Algorithms on Hierarchical Networks

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    The "abstract search algorithm" is a well known quantum method to find a marked vertex in a graph. It has been applied with success to searching algorithms for the hypercube and the two-dimensional grid. In this work we provide an example for which that method fails to provide the best algorithm in terms of time complexity. We analyze search algorithms in degree-3 hierarchical networks using quantum walks driven by non-groverian coins. Our conclusions are based on numerical simulations, but the hierarchical structures of the graphs seems to allow analytical results.Comment: IEEE Information Theory Workshop 201

    Review of some classical gravitational superenergy tensors using computational techniques

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    We use computational algorithms recently developed by us to study completely four index divergence free quadratic in Riemann tensor polynomials in GR. Some results are new and some other reproduce and/or correct known ones. The algorithms are part of a Mathematica package called Tools of Tensor Calculus (TTC)[web address: http://baldufa.upc.es/ttc

    Amplitude Damping for single-qubit System with single-qubit mixed-state Environment

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    We study a generalized amplitude damping channel when environment is initially in the single-qubit mixed state. Representing the affine transformation of the generalized amplitude damping by a three-dimensional volume, we plot explicitly the volume occupied by the channels simulatable by a single-qubit mixed-state environment. As expected, this volume is embedded in the total volume by the channels which is simulated by two-qubit enviroment. The volume ratio is approximately 0.08 which is much smaller than 3/8, the volume ratio for generalized depolarizing channels.Comment: 13 pages, 2 figures incluided V2: homepage address is included in reference V3: version to appear in J. Phys. A: Mathematical and Theoretica

    Capital social y democracia: explorando normas, valores y redes sociales en el Perú

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    Propone estudiar el funcionamiento de la sociedad civil peruana desde la perspectiva del capital social, concepto cuyo uso se ha conocido durante la última década tanto en el campo académico como en el de los organismos multilaterales. Contiene cuatro capítulos. En el primero, se examina críticamente la compleja trayectoria que ha seguido el concepto de capital social desde que comenzó a ser empleado en las Ciencias Sociales. El segundo capítulo, analiza las características y limitaciones más importantes de un tipo de organizaciones voluntarias que encuentran en los valores religiosos de la caridad cristiana su principal fuente de inspiración. El tercero estudia las estrategias colectivas y el tipo de liderazgo que desarrollan las organizaciones vecinales en su búsqueda por conseguir una vivienda digna. El cuarto capítulo intenta identificar los principales obstáculos que enfrentan las Comunidades Locales de Administración de Salud para conseguir que la población participe y esté adecuadamente representada en la gestión de este tipo de establecimientos. Finalmente, se formulan algunas reflexiones a la luz de los capítulos anteriores

    Malaria Immunity in Man and Mosquito: Insights Into Unsolved Mysteries of a Deadly Infectious Disease

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    Malaria is a mosquito-borne disease caused by parasites of the obligate intracellular Apicomplexa family, the most deadly of which, Plasmodium falciparum, prevails in Africa. Malaria imposes a huge health burden on the world’s most vulnerable populations, claiming the lives of nearly a million children and pregnant women each year in Africa alone. Although there is keen interest in eradicating malaria, we do not yet have the necessary tools to meet this challenge, including an effective malaria vaccine and adequate vector control strategies. Here we review what is known about the mechanisms at play in immune resistance to malaria in both the human and mosquito hosts at each step in the parasite’s complex life cycle with a view towards developing the tools that will contribute to the prevention of disease and death and ultimately the goal of malaria eradication. In so doing we hope to inspire immunologists to participate in defeating this devastating disease

    Effects of age-related cognitive deficits on EEG phase coherence

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    Body and brain undergo several changes with aging. One of these changes is the loss of neuroplasticity, which leads to the decrease of cognitive abilities. Hence the necessity of stopping or reversing these changes is of utmost importance to contemporary society. In the present work, electroencephalogram (EEG) markers of cognitive decline are sought whilst the subjects perform the Wisconsin Card Sorting Test (WCST). Considering the expected age-related cognitive deficits, WCST was applied to young and elder participants. The results suggest that coherence on theta and alpha EEG rhythms decrease with aging and increase with performance. Additionally, theta phase coherence seems more sensitive to performance, while alpha synchronization appears as a potential ageing markerFCT-Foundation for Science and Technology and Compete Program with the project reference FCOMP-01-0124-FED ER-021145 (PTDC/SAU-ENB/118383/2010

    Impact of Acute Malaria on Pre-Existing Antibodies to Viral and Vaccine Antigens in Mice and Humans

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    Vaccine-induced immunity depends on long-lived plasma cells (LLPCs) that maintain antibody levels. A recent mouse study showed that Plasmodium chaubaudi infection reduced pre-existing influenza-specific antibodies--raising concerns that malaria may compromise pre-existing vaccine responses. We extended these findings to P. yoelii infection, observing decreases in antibodies to model antigens in inbred mice and to influenza in outbred mice, associated with LLPC depletion and increased susceptibility to influenza rechallenge. We investigated the implications of these findings in Malian children by measuring vaccine-specific IgG (tetanus, measles, hepatitis B) before and after the malaria-free 6-month dry season, 10 days after the first malaria episode of the malaria season, and after the subsequent dry season. On average, vaccine-specific IgG did not decrease following acute malaria. However, in some children malaria was associated with an accelerated decline in vaccine-specific IgG, underscoring the need to further investigate the impact of malaria on pre-existing vaccine-specific antibodies

    Quantum search on graphene lattices

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    We present a continuous-time quantum search algorithm on a graphene lattice. This provides the sought- after implementation of an efficient continuous-time quantum search on a two-dimensional lattice. The search uses the linearity of the dispersion relation near the Dirac point and can find a marked site on a graphene lattice faster than the corresponding classical search. The algorithm can also be used for state transfer and communication
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