4,528 research outputs found

    Predictions for the unitarity triangle angles in a new parametrization

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    A new approach to the parametrization of the CKM matrix, VV, is considered in which VV is written as a linear combination of the unit matrix II and a non-diagonal matrix UU which causes intergenerational-mixing, that is V=cosθI+isinθUV=\cos\theta I+i\sin\theta U. Such a VV depends on 3 real parameters including the parameter θ\theta. It is interesting that a value of θ=π/4\theta=\pi/4 is required to fit the available data on the CKM-matrix including CP-violation. Predictions of this fit for the angles α\alpha, β\beta and γ\gamma for the unitarity triangle corresponding to V11V13+V21V23+V31V33=0V_{11}V^*_{13} + V_{21} V^*_{23} +V_{31}V^*_{33} =0, are given. For θ\theta=π/4\pi/4, we obtain α=88.46\alpha=88.46^\circ, β=45.046\beta=45.046^\circ and γ=46.5\gamma=46.5^\circ. These values are just about in agreement, within errors, with the present data. It is very interesting that the unitarity triangle is expected to be approximately a right-angled, isosceles triangle. Our prediction sin2β=1\sin 2\beta = 1 is in excellent agreement with the value 0.99±0.15±0.050.99\pm 0.15\pm 0.05 reported by the Belle collaboration at the Lepton-Photon 2001 meeting.Comment: 11 pages, latex, no figure

    Wigner distributions for finite dimensional quantum systems: An algebraic approach

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    We discuss questions pertaining to the definition of `momentum', `momentum space', `phase space', and `Wigner distributions'; for finite dimensional quantum systems. For such systems, where traditional concepts of `momenta' established for continuum situations offer little help, we propose a physically reasonable and mathematically tangible definition and use it for the purpose of setting up Wigner distributions in a purely algebraic manner. It is found that the point of view adopted here is limited to odd dimensional systems only. The mathematical reasons which force this situation are examined in detail.Comment: Latex, 13 page

    Phase-space descriptions of operators and the Wigner distribution in quantum mechanics II. The finite dimensional case

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    A complete solution to the problem of setting up Wigner distribution for N-level quantum systems is presented. The scheme makes use of some of the ideas introduced by Dirac in the course of defining functions of noncommuting observables and works uniformly for all N. Further, the construction developed here has the virtue of being essentially input-free in that it merely requires finding a square root of a certain N^2 x N^2 complex symmetric matrix, a task which, as is shown, can always be accomplished analytically. As an illustration, the case of a single qubit is considered in some detail and it is shown that one recovers the result of Feynman and Wootters for this case without recourse to any auxiliary constructs.Comment: 14 pages, typos corrected, para and references added in introduction, submitted to Jour. Phys.

    Particle alignments and shape change in 66^{66}Ge and 68^{68}Ge

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    The structure of the NZN \approx Z nuclei 66^{66}Ge and 68^{68}Ge is studied by the shell model on a spherical basis. The calculations with an extended P+QQP+QQ Hamiltonian in the configuration space (2p3/22p_{3/2}, 1f5/21f_{5/2}, 2p1/22p_{1/2}, 1g9/21g_{9/2}) succeed in reproducing experimental energy levels, moments of inertia and QQ moments in Ge isotopes. Using the reliable wave functions, this paper investigates particle alignments and nuclear shapes in 66^{66}Ge and 68^{68}Ge. It is shown that structural changes in the four sequences of the positive- and negative-parity yrast states with even JJ and odd JJ are caused by various types of particle alignments in the g9/2g_{9/2} orbit. The nuclear shape is investigated by calculating spectroscopic QQ moments of the first and second 2+2^+ states, and moreover the triaxiality is examined by the constrained Hatree-Fock method. The changes of the first band crossing and the nuclear deformation depending on the neutron number are discussed.Comment: 18 pages, 21 figures; submitted to Phys. Rev.

    Teaching Simulations Supported by Artificial Intelligence in the Real World

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    Video conferencing has enabled synchronous communication in a classroom and created multi-sensory content to stimulate learners. Artificial intelligence involves complex equations that are better taught using a constructive pedagogy where students experiment with alternative ways of solving the same problem. Multiple-choice questions have high reliability and can easily reveal student skill levels in a quick way. The Australian Computer Society accreditation exercise ensures that the content for each subject serves as a flexible template for teaching. The geographical extent of the country requires the presence of multiple subordinate campuses affiliated to a main campus. Following the concept of strands, it was also necessary to show continuity in learning and assessments between the first- and second-year subjects. Student feedback for subjects with artificial intelligence-based simulations showed that several students found it difficult to understand lectures and assignments. Hence, to measure student learning, we introduced a Kahoot quiz during the recess of each lecture that students could join through their mobile phones from different campuses. Software project management is challenging for students with vision or attention-related disorders. We taught them how to use charts to visually observe variables and narrow down possible relationships before performing in-depth analysis. One of the main purposes of education is employability. Hence, greater context to real world industry examples was introduced into lectures

    Salmonella enterica biofilm-mediated dispersal by nitric oxide donors in association with cellulose nanocrystal hydrogels

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    Protected by extracellular polymers, microbes within biofilms are significantly more resistant to disinfectants. Current research has been instrumental in identifying nitric oxide donors and hydrogels as potential disinfectant additives. Nitric oxide (NO) donors are considered a very promising molecule as biofilm dispersal agents and hydrogels have recently attracted a lot of interest due to their biocompatible properties and ability to form stable thin films. When the NO donor MAHMA NONOate was dissolved in phosphate saline buffer, it was able to reduce the biomass of well-established biofilms up to 15% for at least 24 h of contact time. Encapsulation of MAHMA NONOate and molsidomine within a hydrogel composed of cellulose nanocrystals (CNC) has shown a synergistic effect in dispersing well-established biofilms: after 2 h of exposure, moderate but significant dispersion was measured. After 6 h of exposure, the number of cells transitioning from the biofilm to the planktonic state was up to 0.6 log higher when compared with non-treated biofilms. To further explore the transport processes of NO donors within hydrogels, we measured the nitric oxide flux from gels, at 25°C for a composite of 0.1 µM MAHMA NONOate–CNC. Nitric oxide diffuses up to 500 µm from the hydrogel surface, with flux decreasing according to Fick’s law. 60% of NO was released from the hydrogel composite during the first 23 min. These data suggest that the combined treatments with nitric oxide donor and hydrogels may allow for new sustainable cleaning strategies
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