2,754 research outputs found

    Level structures on the Weierstrass family of cubics

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    Let W -> A^2 be the universal Weierstrass family of cubic curves over C. For each N >= 2, we construct surfaces parametrizing the three standard kinds of level N structures on the smooth fibers of W. We then complete these surfaces to finite covers of A^2. Since W -> A^2 is the versal deformation space of a cusp singularity, these surfaces convey information about the level structure on any family of curves of genus g degenerating to a cuspidal curve. Our goal in this note is to determine for which values of N these surfaces are smooth over (0,0). From a topological perspective, the results determine the homeomorphism type of certain branched covers of S^3 with monodromy in SL_2(Z/N).Comment: LaTeX, 12 pages; added section giving a topological interpretation of the result

    Density dependent strong coupling constant of QCD derived from compact star data

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    The present work is an endeavour to connect the properties of tiny nearly massless objects with those of some of the most massive ones, the compact stars. Since 1996 there is major influx of X-ray and γ\gamma ray data from binary stars, one or both of which are compact objects that are difficult to explain as neutron stars since they contain a mass M in too small a radius R . The suggestion has been put forward that these are strange quark stars (SS) explainable in a simple model with chiral symmetry restoration (CSR) for the quarks and the M, R and other properties like QPOs (quasi periodic oscillations) in their X-ray power spectrum. It would be nice if this astrophysical data could shed some light on fundamental properties of quarks obeying QCD. One can relate the strong coupling constant of QCD, αs\alpha_s to the quark mass through the Dyson-Schwinger gap equation using the real time formalism of Dolan and Jackiw. This enables us to obtain the density dependence of αs\alpha_s from the simple CSR referred to above. This way fundamental physics, difficult to extract from other models like for example lattice QCD, can be constrained from present-day compact star data and may be put back to modelling the dense quark phase of early universe.Comment: 7 pages, 4 figure

    Examining the Impact of Treatment Fidelity on Client Outcomes in a Statewide Implementation of Parent-Child Interaction Therapy

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    Clinician treatment fidelity, consisting of treatment adherence and clinician competence, is commonly assessed during the implementation of evidence-based treatments to ensure that clinicians are delivering care according to an intended service model. Although resources are often expended in fidelity measurement, associations between fidelity and client outcomes has not been well established in the psychotherapy literature. The relationship between clinician fidelity and treatment outcomes was investigated in a longitudinal sample of clinicians (n = 17) and parent-child dyads (n = 32) following a statewide implementation of Parent-Child Interaction Therapy. Observer-rated measures of adherence and coaching competence collected from early treatment sessions were used to predict intake levels and growth trajectories of parent-reported behavior problems and positive parenting skills. Hierarchical linear modeling results indicated that higher levels of coaching competence were associated with greater behavior problem frequency at intake. Neither early session adherence nor early session competence, as they were measured in the current study, predicted changes in treatment outcomes over time. These results suggest that additional variables should be modeled alongside early treatment fidelity to predict treatment outcome change. Possible explanations for these findings, limitations of the current study, and directions for future research are discussed

    Mechanisms for Outsourcing Computation via a Decentralized Market

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    As the number of personal computing and IoT devices grows rapidly, so does the amount of computational power that is available at the edge. Since many of these devices are often idle, there is a vast amount of computational power that is currently untapped, and which could be used for outsourcing computation. Existing solutions for harnessing this power, such as volunteer computing (e.g., BOINC), are centralized platforms in which a single organization or company can control participation and pricing. By contrast, an open market of computational resources, where resource owners and resource users trade directly with each other, could lead to greater participation and more competitive pricing. To provide an open market, we introduce MODiCuM, a decentralized system for outsourcing computation. MODiCuM deters participants from misbehaving-which is a key problem in decentralized systems-by resolving disputes via dedicated mediators and by imposing enforceable fines. However, unlike other decentralized outsourcing solutions, MODiCuM minimizes computational overhead since it does not require global trust in mediation results. We provide analytical results proving that MODiCuM can deter misbehavior, and we evaluate the overhead of MODiCuM using experimental results based on an implementation of our platform

    Holomorphic selection rules, the origin of the mu term, and thermal inflation

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    When an abelian gauge theory with integer charges is spontaneously broken by the expectation value of a charge Q field, there remains a Z_Q discrete symmetry. In a supersymmetric theory, holomorphy adds additional constraints on the operators that can appear in the effective superpotential. As a result, operators with the same mass dimension but opposite sign charges can have very different coupling strengths. In the present work we characterize the operator hierarchies in the effective theory due to holomorphy, and show that there exist simple relationships between the size of an operator and its mass dimension and charge. Using such holomorphy-induced operator hierarchies, we construct a simple model with a naturally small supersymmetric mu term. This model also provides a concrete realization of late-time thermal inflation, which has the ability to solve the gravitino and moduli problems of weak-scale supersymmetry.Comment: 18 pages, 1 figur

    The combustion mitigation of methane as a non-CO2 greenhouse gas

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    These research results have received funding from the EU H2020 Programme (No. 689772) and from MCTI/RNP-Brazil under the HPC4E Project, grant agreement no 689772
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