2,048 research outputs found

    Quantum and Classical in Adiabatic Computation

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    Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialised state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose groundstate encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimisation algorithms and quantum adiabatic optimisation. This new perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealing - though inconclusive - results

    Non-Abelian Vortices of Higher Winding Numbers

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    We make a detailed study of the moduli space of winding number two (k=2) axially symmetric vortices (or equivalently, of co-axial composite of two fundamental vortices), occurring in U(2) gauge theory with two flavors in the Higgs phase, recently discussed by Hashimoto-Tong (hep-th/0506022) and Auzzi-Shifman-Yung (hep-th/0511150). We find that it is a weighted projective space WCP^2_(2,1,1)=CP^2/Z_2. This manifold contains an A_1-type (Z_2) orbifold singularity even though the full moduli space including the relative position moduli is smooth. The SU(2) transformation properties of such vortices are studied. Our results are then generalized to U(N) gauge theory with N flavors, where the internal moduli space of k=2 axially symmetric vortices is found to be a weighted Grassmannian manifold. It contains singularities along a submanifold.Comment: 32 pages, 1 figure, the final version published in PR

    The regulation of exosome function in the CNS: implications for neurodegeneration

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    Exosomes are nanovesicles that have been shown to regulate neuronal development and regeneration, and modulate synaptic function

    Adequacy of hospitals in Rome to an unconventional event (CBRNe). TTX simulation and HTA

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    Background Rome hosts thousands of sensible targets. Healthcare reaction has been guaranteed by 6 advanced Emergency Departments (EDs) and 7 basic ones. Everyday Rome hosts 6 millions of people/die, ± 2 million in particular occasions. About National Stockpile Antidotes (SNA), Rome hosts 3 warehouses. In case of events, stockpiles are activated with a long-time call; then stockpiles are charged in delivering trucks. Methods Study analyzes PEIMAF (State of emergency plans for massive influx of injures) of advanced EDs in Rome and their adequacy in a possible CBRNe attack. Hypothesis of C/N attack on Saint Peter's Square during Angelus on Wednesday (at 12.00 AM) or E attack in Trastevere on Saturday (at 9.00 PM). Analysis of activation of SNA and travel times between SNA warehouse and EDs. Comparison with French EDs during Paris attacks. Results EDs are chronically undermanned in ordinary conditions already, and would have issues in hosting a very large number of critical patients all at once. Some hospitals do not inform their workers about PEIMAF or they do not consider CBRNe emergencies in their PEIMAF, and even if it has been considered, hardly any simulation/exercitation is ever performed. Moreover, news of the CBRNe attack may not reach immediately the healthcare personal already at work in EDs; this is extremely problematic since they could be at major risk of contamination in case of CBRNe attacks. Furthermore, without a standardize protocol active in the whole city, no cross-hospital organization can be performed. Conclusions All data point towards the weakness and fragmentation of actual organizative system. Time of activation and charging are crucials for first aid efficacy and efficiency; a smart call system can reduce the activation time of SNA. A better organization of SNA in major Rome hospitals can reduce delivering time and help save more lives
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