1,198 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

    General Opinion Formation Games with Social Group Membership (Short Paper)

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    Modeling how agents form their opinions is of paramount importance for designing marketing and electoral campaigns. In this work, we present a new framework for opinion formation which generalizes the well-known Friedkin-Johnsen model by incorporating three important features: (i) social group membership, that limits the amount of influence that people not belonging to the same group may lead on a given agent; (ii) both attraction among friends, and repulsion among enemies; (iii) different strengths of influence lead from different people on a given agent, even if the social relationships among them are the same. We show that, despite its generality, our model always admits a pure Nash equilibrium which, under opportune mild conditions, is even unique. Next, we analyze the performances of these equilibria with respect to a social objective function defined as a convex combination, parametrized by a value λ ∈ [0, 1], of the costs yielded by the untruthfulness of the declared opinions and the total cost of social pressure. We prove bounds on both the price of anarchy and the price of stability which show that, for not-too-extreme values of λ, performance at equilibrium are very close to optimal ones. For instance, in several interesting scenarios, the prices of anarchy and stability are both equal to (Equation presented) which never exceeds 2 for λ ∈ [1/5, 1/2]

    On Augmented Stochastic Submodular Optimization: Adaptivity, Multi-Rounds, Budgeted, and Robustness

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    In this work we consider the problem of Stochastic Submodular Maximization, in which we would like to maximize the value of a monotone and submodular objective function, subject to the fact that the values of this function depend on the realization of stochastic events. This problem has applications in several areas, and in particular it well models basic problems such as influence maximization and stochastic probing. In this work, we advocate the necessity to extend the study of this problem in order to include several different features such as a budget constraint on the number of observations, the chance of adaptively choosing what we observe or the presence of multiple rounds. We here speculate on the possible directions that this line of research can take. In particular, we will discuss about interesting open problems mainly in the settings of robust optimization and online learning

    Pengaruh Penggunaan Antibiotik Eritromisin Dengan Terapi Calcium-channel Blocker Terhadap Gagal Ginjal Akut

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    Calsium-Channel Blocker (CCB) seperti amlodipin, felodipin, nifedipin, diltiazem, dan verapamil dimetabolisme oleh enzim CYP3A4. Kadar CCB dalam darah dapat meningkat ke level yang berbahaya jika enzim tersebut dihambat. Eritromisin (antibiotik makrolida) merupakan inhibitor CYP3A4, penggunaan bersamaan CCB dan makrolida diasosiasikan dengan peningkatan risiko rawat inap akibat gagal ginjal akut. Tujuan penelitian ini untuk mengetahui pengaruh yang ditimbulkan oleh penggunaan CCB dan eritromisin terhadap fungsi ginjal pada pasien rawat inap poliklinik penyakit dalam RS Dr. Moewardi. Penelitian dilakukan secara deskriptif dengan pendekatan pengambilan data secara retrospektif. Data diperoleh dari hasil observasi catatan rekam medik pasien selama menjalani perawatan di rumah sakit (rawat inap). Hasil dari 4 pasien diketahui masing-masing pasien mengalami peningkatan kadar kreatinin dan ureum dengan rata-rata kenaikan kreatinin 34,8% dan ureum 36,6%. Hal ini kemungkinan disebabkan adanya interaksi makrolida dan CCB yang mengakibatkan kenaikan kadar CCB dalam darah sehingga menyebabkan hipotensi. Keadaan hipotensi dapat menyebabkan hipoperfusi ginjal yang berpotensi terjadinya gagal ginjal akut, dimana ditandai dengan meningkatnya kadar ureum dan kreatinin

    A Structured Framework and Resources to Use to Get Your Medical Education Work Published.

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    IntroductionMedical educators often have great ideas for medical education scholarship but have difficulty converting their educational abstract or project into a published manuscript.MethodsDuring this workshop, participants addressed common challenges in developing an educational manuscript. In small-group case scenarios, participants discovered the importance of the "So what?" in making the case for their project. Incorporating conceptual frameworks, participants chose appropriate outcome metrics, discussed how to frame the discussion section, and ensured appropriate journal fit. After each small-group exercise, large-group discussions allowed the small groups to report back so that facilitators could highlight and reinforce key learning points. At the conclusion of the workshop, participants left with a checklist for creating an educational manuscript and an additional resources document to assist them in avoiding common pitfalls when turning their educational abstract/project into a publishable manuscript.ResultsThis workshop was presented in 2016 and 2017. Presenter evaluations were completed by 33 participants; 11 completed conference evaluations. The mean overall rating on presenter evaluations was 4.55 out of 5, while the conference evaluations mean was 3.73 out of 4. Comments provided on both evaluation tools highlighted the perceived effectiveness of the delivery and content. More than 50% of respondents stated that they planned to incorporate the use of conceptual frameworks in future work.DiscussionThis workshop helped participants address common challenges by providing opportunities for hands-on practice as well as tips and resources for use when submitting a medical education manuscript for publication

    Improved Approximation Factor for Adaptive Influence Maximization via Simple Greedy Strategies

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    In the adaptive influence maximization problem, we are given a social network and a budget k, and we iteratively select k nodes, called seeds, in order to maximize the expected number of nodes that are reached by an influence cascade that they generate according to a stochastic model for influence diffusion. The decision on the next seed to select is based on the observed cascade of previously selected seeds. We focus on the myopic feedback model, in which we can only observe which neighbors of previously selected seeds have been influenced and on the independent cascade model, where each edge is associated with an independent probability of diffusing influence. While adaptive policies are strictly stronger than non-adaptive ones, in which all the seeds are selected beforehand, the latter are much easier to design and implement and they provide good approximation factors if the adaptivity gap, the ratio between the adaptive and the non-adaptive optima, is small. Previous works showed that the adaptivity gap is at most 4, and that simple adaptive or non-adaptive greedy algorithms guarantee an approximation of 1/4 (1-1/e) ? 0.158 for the adaptive optimum. This is the best approximation factor known so far for the adaptive influence maximization problem with myopic feedback. In this paper, we directly analyze the approximation factor of the non-adaptive greedy algorithm, without passing through the adaptivity gap, and show an improved bound of 1/2 (1-1/e) ? 0.316. Therefore, the adaptivity gap is at most 2e/e-1 ? 3.164. To prove these bounds, we introduce a new approach to relate the greedy non-adaptive algorithm to the adaptive optimum. The new approach does not rely on multi-linear extensions or random walks on optimal decision trees, which are commonly used techniques in the field. We believe that it is of independent interest and may be used to analyze other adaptive optimization problems. Finally, we also analyze the adaptive greedy algorithm, and show that guarantees an improved approximation factor of 1-1/(?{e)}? 0.393

    Early childhood educator training: The value of educating educators on movement, play and physical literacy development - A three country case study.

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    A child's early movement and active play experiences influence their attitudes towards physical activity throughout their childhood and into adulthood (Blair, 1992). Yet, it has been suggested that early childhood educators (ECEs) may not recognize the importance of, or give enough attention to, movement skills and physical development opportunities for young children (Clark, 2014; Whitehead, 2010). The education, or lack thereof, that ECEs receive could be an important factor. International comparisons of overall ECE preparation and training have demonstrated that some countries' ECEs are more highly educated than others (Howells and Sääkslahti, 2019). Using a case study approach, this paper conducts an analysis and comparison of three countries to examine the value and role of physical activity/movement education for ECEs to enable them to support physical literacy development in early childhood educational settings. In addition, lessons learned from creating such educational opportunities in the context of their various locations (Manitoba in Canada, Kent in England, and Escambia County, FL in U.S.A.) are discussed. A purposeful sample was used as these countries have relatively low levels of educational requirements for ECEs, yet children start attending early years’ education from the earliest life points (Howells & Sääkslahti, 2019)

    Influence of Y2O3 addition on the mechanical and oxidation behaviour of carbon fibre reinforced ZrB2/SiC composites

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    The influence of Y2O3 addition on the microstructure, thermo-mechanical properties and oxidation resistance of carbon fibre reinforced ZrB2/SiC composites was investigated. Y2O3 reacted with oxide impurities present on the surface of ZrB2 and SiC grains and formed a liquid phase, effectively lowering the sintering temperature and allowing to reach full density at 1900 °C. The presence of a carbon source (fibres) led to additional reactions which resulted in the formation of new secondary phases such as yttrium boro-carbides. Mechanical properties were significantly enhanced compared to the un-doped composite. Further tests at high temperatures resulted in strength increase up to 700 MPa at 1500 °C which was attributed to stress relaxation. Oxidation tests carried out at 1500 °C and 1650 °C in air showed that the presence of the Y-based secondary phases enhanced the growth of ZrO2 grains, but offered limited protection to oxygen due to the lower availability of surficial SiO2 formed from SiC

    Reactive melt infiltration of carbon fibre reinforced ZrB2/B composites with Zr2Cu

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    The microstructure and mechanical properties of carbon fibre reinforced ZrB2 composites produced by slurry infiltration and consolidated by reactive melt infiltration were investigated. Fibres were preliminary infiltrated with ZrB2/B slurries with varying ZrB2/B ratios. Then the composites were infiltrated with Zr2Cu melt at 1200 °C under vacuum. Boron was chosen as the reactant phase, while raw ZrB2 was added as a filler to prevent excessive swelling. With increase of boron content the infiltration becomes more difficult due to the reaction of alloy and boron. The boron is completely converted to nano ZrB2 grains. Some ZrC is produced from the side reaction between Zr2Cu and the carbon fibre, resulting in reduction of fibre diameter. The flexural strength increased from 360 to 560 MPa with the increase of boron content, while KIc amounted to 10 MPa⋅m0.5 but was affected by large scatter. The mechanical behaviour was mostly dominated by matrix properties
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