2,009 research outputs found

    Inclusive Production of Four Charm Hadrons in e^+ e^- Annihilation at B Factories

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    Measurements by the Belle Collaboration of the exclusive production of two charmonia in e^+ e^- annihilation differ substantially from theoretical predictions. Till now, no conclusive explanation for this remarkable discrepancy has been provided. Even the origin of the discrepancy is not identified, yet. We suggest that the measurement of four-charm events in Belle data must provide a strong constraint in identifying the origin of this large discrepancy. Our prediction of the cross section for e^+e^- -> c c-bar c c-bar, in lowest order in strong coupling constant, at sqrt{s}=10.6 GeV is about 0.1 pb. If measured four-charm cross section is compatible with the prediction based on perturbative QCD, it is very likely that factorization of hadronization process from perturbative part may be significantly violated or there exists a new production mechanism. If the cross section for the four-charm event is also larger than the prediction like that for the exclusive J/psi+eta_c production, perturbative QCD expansion itself will be proved to be unreliable and loses predictive power.Comment: 4 pages, 3 figures, version published in Phys. Rev. D as a Rapid Communicatio

    Transnational reflections on transnational research projects on men, boys and gender relations

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    This article reflects on the research project, ‘Engaging South African and Finnish youth towards new traditions of non-violence, equality and social well-being’, funded by the Finnish and South African national research councils, in the context of wider debates on research, projects and transnational processes. The project is located within a broader analysis of research projects and projectization (the reduction of research to separate projects), and the increasing tendencies for research to be framed within and as projects, with their own specific temporal and organizational characteristics. This approach is developed further in terms of different understandings of research across borders: international, comparative, multinational and transnational. Special attention is given to differences between research projects that are in the Europe and the EU, and projects that are between the global North and the global South. The theoretical, political and practical challenges of the North-South research project are discussed

    In Nightingale's footsteps: A qualitative analysis of the impact of leadership development within the clinical learning environment

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    Aim To identify and describe the impact areas of a newly developed leadership development programme focussed on positioning leaders to improve the student experience of the clinical learning environment. Background There is a need to consider extending traditional ways of developing leaders within the clinical learning in order to accommodate an increased number of students and ensure their learning experience is fulfilling and developmental. The Florence Nightingale Foundation implemented a bespoke leadership development programme within the clinical learning environment. Identifying the areas of impact will help to inform organisational decision making regarding the benefits of encouraging and supporting emerging leaders to undertake this type of programme. Method For this qualitative descriptive study, eight health care professionals who took part in a bespoke leadership development programme were interviewed individually and then collectively. The Florence Nightingale Foundation fellowship/scholarship programme is examined to determine impact. Results Two key themes were described in relation to impact of the programme. These were ‘Personal Development’ and ‘Professional Impact’. The two key themes comprised several subthemes. The notion of time and space to think was subsumed within each theme. Conclusion Data highlights that the Florence Nightingale Foundation programme had a distinct impact on participants by transforming thinking and increasing self-confidence to enable changes to make improvements both within their organisations and at national level. Implications for Nursing Management Health care managers must continue to invest in building leadership capacity and capability through programmes that can help position individuals to realize their potential to positively influence health outcomes and wider society

    Progressive Star Bursts and High Velocities in the Infrared Luminous, Colliding Galaxy Arp 118

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    In this paper we demonstrate for the first time the connection between the spatial and temporal progression of star formation and the changing locations of the very dense regions in the gas of a massive disk galaxy (NGC 1144) in the aftermath of its collision with a massive elliptical (NGC 1143). These two galaxies form the combined object Arp 118, a collisional ring galaxy system. The results of 3D, time-dependent, numerical simulations of the behavior of the gas, stars, and dark matter of a disk galaxy and the stars and dark matter in an elliptical during a collision are compared with multiwavelength observations of Arp 118. The collision that took place approximately 22 Myr ago generated a strong, non-linear density wave in the stars and gas in the disk of NGC 1144, causing the gas to became clumped on a large scale. This wave produced a series of superstarclusters along arcs and rings that emanate from the central point of impact in the disk. The locations of these star forming regions match those of the regions of increased gas density predicted the time sequence of models. The models also predict the large velocity gradients observed across the disk of NGC 1144. These are due to the rapid radial outflow of gas coupled to large azimuthal velocities in the expanding ring, caused by the impact of the massive intruder.Comment: 12 pages in document, and 8 figures (figures are separate from the document's file); Submitted to Astrophysical Journal Letter

    Subtropical Real Root Finding

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    We describe a new incomplete but terminating method for real root finding for large multivariate polynomials. We take an abstract view of the polynomial as the set of exponent vectors associated with sign information on the coefficients. Then we employ linear programming to heuristically find roots. There is a specialized variant for roots with exclusively positive coordinates, which is of considerable interest for applications in chemistry and systems biology. An implementation of our method combining the computer algebra system Reduce with the linear programming solver Gurobi has been successfully applied to input data originating from established mathematical models used in these areas. We have solved several hundred problems with up to more than 800000 monomials in up to 10 variables with degrees up to 12. Our method has failed due to its incompleteness in less than 8 percent of the cases

    A note on the polarization of the laser field in Mott Scattering

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    In the first Born approximation and using an elliptically polarized laser field, the Mott scattering of an electron by a Coulomb potential is investigated using the Dirac-Volkov states to describe the incident and scattered electrons. The results obtained are compared with the results of S.M. Li \textit{et al} \cite{1} for the case of a linearly polarized laser field and with the results of Y. Attaourti \textit{et al} \cite{2} for the case of a circular polarization.Comment: 9 pages, Latex, 2 figure

    A new two-dimensional lattice model that is "consistent around a cube"

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    For two-dimensional lattice equations one definition of integrability is that the model can be naturally and consistently extended to three dimensions, i.e., that it is "consistent around a cube" (CAC). As a consequence of CAC one can construct a Lax pair for the model. Recently Adler, Bobenko and Suris conducted a search based on this principle and certain additional assumptions. One of those assumptions was the "tetrahedron property", which is satisfied by most known equations. We present here one lattice equation that satisfies the consistency condition but does not have the tetrahedron property. Its Lax pair is also presented and some basic properties discussed.Comment: 8 pages in LaTe

    The upper triangular solutions to the three-state constant quantum Yang-Baxter equation

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    In this article we present all nonsingular upper triangular solutions to the constant quantum Yang-Baxter equation Rj1j2k1k2Rk1j3l1k3Rk2k3l2l3=Rj2j3k2k3Rj1k3k1l3Rk1k2l1l2R_{j_1j_2}^{k_1k_2}R_{k_1j_3}^{l_1k_3}R_{k_2k_3}^{l_2l_3}= R_{j_2j_3}^{k_2k_3}R_{j_1k_3}^{k_1l_3}R_{k_1k_2}^{l_1l_2} in the three state case, i.e. all indices ranging from 1 to 3. The upper triangular ansatz implies 729 equations for 45 variables. Fortunately many of the equations turned out to be simple allowing us to start breaking the problem into smaller ones. In the end we had a total of 552 solutions, but many of them were either inherited from two-state solutions or subcases of others. The final list contains 35 nontrivial solutions, most of them new.Comment: 24 Pages in LaTe
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