7,999 research outputs found

    Λb\Lambda_b Decays into Λ\Lambda-Vector

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    A complete study of the angular distributions of the processes, ΛbΛV(1)\Lambda_b \to {\Lambda} V(1^-), with Λpπ\Lambda \to p {\pi}^- and V(J/Ψ)+V (J/{\Psi}) \to {\ell}^+ {\ell}^- or V(ρ0,ω)π+π,V ({\rho}^0,\omega) \to {\pi}^+ {\pi}^-, is performed. Emphasis is put on the initial Λb\Lambda_b polarization produced in the proton-proton collisions. The polarization density-matrices as well as angular distributions are derived and help to construct T-odd observables which allow us to perform tests of both Time-Reversal and CP violation.Comment: 10 pages, 2 figure

    Angular Analysis of Lambda_b Decays into Lambda v(1-) Applications to Time-Odd Observables and CP violation in Lambda_b Decays (I)

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    A complete study of teh angualr distributions of the process Lambda_b to Lambda V(1-) with lambda to p pi- and V(J/Psi) to l+l- or V(rho0,omega, phi) to pi+ pi-, K+K- is performed. Emphasis is put on the initial Lambda-b polarization produced in the proton-proton collisions and, without any dynamical assumption, polarized density-matrices of the vector-mesons V are derived and help to construct T-odd observables which allow us to perform tests of both Time-Reversal and CP violation.Comment: 12 pages, 2 figure

    Improvement of Surface Accuracy and Shop Floor Feed Rate Smoothing Through Open CNC Monitoring System and Cutting Simulation

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    AbstractIn the milling process of complex workpiece shapes the feed rate normally becomes instable due to the high degree of surface curvature that requires high acceleration and deceleration of the interpolated axes. This condition impacts on process time and on the surface accuracy regarding the manufactured part form and texture. The challenge to simulate the real machine and control behavior requires accurate models with a set of experiments to tune and dimension the model to the respective machine tool. The aim is to improve the HSC milling process of complex surfaces before removing any material. In this paper experiments show that the surface form accuracy and texture can be optimized through an automatic feed rate smoothing of the finishing operation directly on the machine tool. The axis positions and spindle speeds monitored through the open CNC are used as input for a geometric cutting simulation, thus enabling to predict and optimize the surface quality

    Construction of Special Solutions for Nonintegrable Systems

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    The Painleve test is very useful to construct not only the Laurent series solutions of systems of nonlinear ordinary differential equations but also the elliptic and trigonometric ones. The standard methods for constructing the elliptic solutions consist of two independent steps: transformation of a nonlinear polynomial differential equation into a nonlinear algebraic system and a search for solutions of the obtained system. It has been demonstrated by the example of the generalized Henon-Heiles system that the use of the Laurent series solutions of the initial differential equation assists to solve the obtained algebraic system. This procedure has been automatized and generalized on some type of multivalued solutions. To find solutions of the initial differential equation in the form of the Laurent or Puiseux series we use the Painleve test. This test can also assist to solve the inverse problem: to find the form of a polynomial potential, which corresponds to the required type of solutions. We consider the five-dimensional gravitational model with a scalar field to demonstrate this.Comment: LaTeX, 14 pages, the paper has been published in the Journal of Nonlinear Mathematical Physics (http://www.sm.luth.se/math/JNMP/

    Cyclic Mobility Effects on Soil-Pile Interaction in Dense Sand

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    A methodology to evaluate the effects of earthquake-induced cyclic mobility in dense sand on the soil-pile interaction parameters is presented. The soil behavior under cyclic loading is defined based on the interpretation of consolidated-undrained cyclic triaxial tests on samples reconstituted to the in situ relative density and shear wave velocity. The stress distribution around the pile is determined analytically, and the softened zone is modelled by an annulus of softer soil. The application of this methodology for the design of three submerged-floating tunnels in the Messina straits, Italy, indicated that even in dense sand the foundation stiffness reduction can be considerable during an earthquake. Comparisons with different approaches available from the literature are discussed

    A reduction of the resonant three-wave interaction to the generic sixth Painleve' equation

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    Among the reductions of the resonant three-wave interaction system to six-dimensional differential systems, one of them has been specifically mentioned as being linked to the generic sixth Painleve' equation P6. We derive this link explicitly, and we establish the connection to a three-degree of freedom Hamiltonian previously considered for P6.Comment: 13 pages, 0 figure, J. Phys. A Special issue "One hundred years of Painleve' VI

    Symmetry reductions of a particular set of equations of associativity in twodimensional topological field theory

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    The WDVV equations of associativity arising in twodimensional topological field theory can be represented, in the simplest nontrivial case, by a single third order equation of the Monge-Ampe`re type. By investigating its Lie point symmetries, we reduce it to various nonlinear ordinary differential equations, and we obtain several new explicit solutions.Comment: 10 pages, Latex, to appear in J. Phys. A: Math. Gen. 200

    Control of mucocutaneous leishmaniasis, a neglected disease: results of a control programme in Satipo Province, Peru.

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    Mucocutaneous leishmaniasis (MCL) is an important health problem in many rural areas of Latin America, but there are few data on the results of programmatic approaches to control the disease. We report the results of a control programme in San Martin de Pangoa District, which reports one of the highest prevalences of MCL in Peru. For 2 years (2001--2002), the technicians at the health post were trained in patient case management, received medical support and were supplied with antimonials. An evaluation after 2 years showed the following main achievements: better diagnosis of patients, who were confirmed by microscopy in 34% (82/240) of the cases in 2001 and 60% of the cases (153/254) in 2002; improved follow-up during treatment: 237 of 263 (90%) patients who initiated an antimonial therapy ended the full treatment course; improved follow-up after treatment: 143 of 237 (60%) patients who ended their full treatment were correctly monitored during the required period of 6 (cutaneous cases) or 12 (mucosal cases) months after the end of treatment. These achievements were largely due to the human and logistical resources made available, the constant availability of medications and the close collaboration between the Ministry of Health, a national research institute and an international non-governmental organization. At the end of this period, the health authorities decided to register a generic brand of sodium stibogluconate, which is now in use. This should allow the treatment of a significant number of additional patients, while saving money to invest in other facets of the case management

    Hyper-complex four-manifolds from the Tzitz\'eica equation

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    It is shown how solutions to the Tzitz\'eica equation can be used to construct a family of (pseudo) hyper-complex metrics in four dimensions.Comment: To be published in J.Math.Phy

    Psi-series solutions of the cubic H\'{e}non-Heiles system and their convergence

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    The cubic H\'enon-Heiles system contains parameters, for most values of which, the system is not integrable. In such parameter regimes, the general solution is expressible in formal expansions about arbitrary movable branch points, the so-called psi-series expansions. In this paper, the convergence of known, as well as new, psi-series solutions on real time intervals is proved, thereby establishing that the formal solutions are actual solutions
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