546 research outputs found

    GU + GSA = L + R: educating the whole: course structure for a human-centred approach in product design engineering

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    In Glasgow, an inter-institutional approach to teaching design engineering students is fostered through the particular nature of the teaching and learning environment, the management of students, the structure of the projects, and the content and delivery of the technical and non-technical elements. These engineering students are encouraged to work in teams, to take a user-orientated approach, to develop an aesthetic as well as a technical intelligence, and to understand the role of human factors in successful product development

    Measurement of K^+ \to \pi^0 \mu^+ \nu \gamma decay using stopped kaons

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    The K^+ \to \pi^0 \mu^+ \nu \gamma (Kμ3γK_{\mu 3 \gamma}) decay has been measured with stopped positive kaons at the KEK 12 GeV proton synchrotron. A Kμ3γK_{\mu 3 \gamma} sample containing 125 events was obtained. The partial branching ratio Br(Kμ3γ,Eγ>30MeV,θμ+γ>20∘)Br(K_{\mu 3 \gamma}, E_{\gamma}>30 {\rm MeV}, \theta_{\mu^+ \gamma}>20^{\circ}) was found to be [2.4±0.5(stat)±0.6(syst)]×10−5[2.4 \pm 0.5(stat) \pm 0.6(syst)]\times 10^{-5}, which is in good agreement with theoretical predictions.Comment: 12 pages, 3 figures, to be published in Physics Letters

    Current-Induced Torques in Magnetic Metals: Beyond Spin Transfer

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    Current-induced torques on ferromagnetic nanoparticles and on domain walls in ferromagnetic nanowires are normally understood in terms of transfer of conserved spin angular momentum between spin-polarized currents and the magnetic condensate. In a series of recent articles we have discussed a microscopic picture of current-induced torques in which they are viewed as following from exchange fields produced by the misaligned spins of current carrying quasiparticles. This picture has the advantage that it can be applied to systems in which spin is not approximately conserved. More importantly, this point of view makes it clear that current-induced torques can also act on the order parameter of an antiferromagnetic metal, even though this quantity is not related to total spin. In this informal and intentionally provocative review we explain this picture and discuss its application to antiferromagnets.Comment: 5 figures, to appear in Journal of Magnetism and

    Extended Seiberg-Witten Theory and Integrable Hierarchy

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    The prepotential of the effective N=2 super-Yang-Mills theory perturbed in the ultraviolet by the descendents of the single-trace chiral operators is shown to be a particular tau-function of the quasiclassical Toda hierarchy. In the case of noncommutative U(1) theory (or U(N) theory with 2N-2 fundamental hypermultiplets at the appropriate locus of the moduli space of vacua) or a theory on a single fractional D3 brane at the ADE singularity the hierarchy is the dispersionless Toda chain. We present its explicit solutions. Our results generalize the limit shape analysis of Logan-Schepp and Vershik-Kerov, support the prior work hep-th/0302191 which established the equivalence of these N=2 theories with the topological A string on CP^1 and clarify the origin of the Eguchi-Yang matrix integral. In the higher rank case we find an appropriate variant of the quasiclassical tau-function, show how the Seiberg-Witten curve is deformed by Toda flows, and fix the contact term ambiguity.Comment: 49 page

    Quantized Thermal Transport in the Fractional Quantum Hall Effect

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    We analyze thermal transport in the fractional quantum Hall effect (FQHE), employing a Luttinger liquid model of edge states. Impurity mediated inter-channel scattering events are incorporated in a hydrodynamic description of heat and charge transport. The thermal Hall conductance, KHK_H, is shown to provide a new and universal characterization of the FQHE state, and reveals non-trivial information about the edge structure. The Lorenz ratio between thermal and electrical Hall conductances {\it violates} the free-electron Wiedemann-Franz law, and for some fractional states is predicted to be {\it negative}. We argue that thermal transport may provide a unique way to detect the presence of the elusive upstream propagating modes, predicted for fractions such as ν=2/3\nu=2/3 and ν=3/5\nu=3/5.Comment: 6 pages REVTeX, 2 postscript figures (uuencoded and compressed

    Measurement of direct photon emission in K+→π+π0γK^+ \to \pi^+ \pi^0 \gamma decay using stopped positive kaons

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    The radiative decay K+→π+π0γK^+ \to \pi^+ \pi^0 \gamma (Kπ2γK_{\pi 2 \gamma}) has been measured with stopped positive kaons. A Kπ2γK_{\pi 2 \gamma} sample containing 4k events was analyzed, and the Kπ2γK_{\pi 2 \gamma} branching ratio of the direct photon emission process was determined to be [6.1±2.5(stat)±1.9(syst)]×10−6[6.1\pm2.5({\rm stat})\pm1.9({\rm syst})]\times 10^{-6}. No interference pattern with internal bremsstrahlung was observed.Comment: 12 pages, 6 figures, 2 tables, to be published in Phys. Lett.

    A Matrix Integral Solution to [P,Q]=P and Matrix Laplace Transforms

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    In this paper we solve the following problems: (i) find two differential operators P and Q satisfying [P,Q]=P, where P flows according to the KP hierarchy \partial P/\partial t_n = [(P^{n/p})_+,P], with p := \ord P\ge 2; (ii) find a matrix integral representation for the associated \t au-function. First we construct an infinite dimensional space {\cal W}=\Span_\BC \{\psi_0(z),\psi_1(z),... \} of functions of z\in\BC invariant under the action of two operators, multiplication by z^p and A_c:= z \partial/\partial z - z + c. This requirement is satisfied, for arbitrary p, if \psi_0 is a certain function generalizing the classical H\"ankel function (for p=2); our representation of the generalized H\"ankel function as a double Laplace transform of a simple function, which was unknown even for the p=2 case, enables us to represent the \tau-function associated with the KP time evolution of the space \cal W as a ``double matrix Laplace transform'' in two different ways. One representation involves an integration over the space of matrices whose spectrum belongs to a wedge-shaped contour \gamma := \gamma^+ + \gamma^- \subset\BC defined by \gamma^\pm=\BR_+\E^{\pm\pi\I/p}. The new integrals above relate to the matrix Laplace transforms, in contrast with the matrix Fourier transforms, which generalize the Kontsevich integrals and solve the operator equation [P,Q]=1.Comment: 27 pages, LaTeX, 1 figure in PostScrip

    Evidence of in Vivo Existence of Borrelia Biofilm in Borrelial Lymphocytomas

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    Lyme borreliosis, caused by the spirochete Borrelia burgdorferi sensu lato, has grown into a major public health problem. We recently identified a novel morphological form of B. burgdorferi, called biofilm, a structure that is well known to be highly resistant to antibiotics. However, there is no evidence of the existence of Borrelia biofilm in vivo; therefore, the main goal of this study was to determine the presence of Borrelia biofilm in infected human skin tissues. Archived skin biopsy tissues from borrelial lymphocytomas (BL) were reexamined for the presence of B. burgdorferi sensu lato using Borrelia-specific immunohistochemical staining (IHC), fluorescent in situ hybridization, combined fluorescent in situ hybridization (FISH)—IHC, polymerase chain reaction (PCR), and fluorescent and atomic force microscopy methods. Our morphological and histological analyses showed that significant amounts of Borrelia-positive spirochetes and aggregates exist in the BL tissues. Analyzing structures positive for Borrelia showed that aggregates, but not spirochetes, expressed biofilm markers such as protective layers of different mucopolysaccharides, especially alginate. Atomic force microscopy revealed additional hallmark biofilm features of the Borrelia/alginate-positive aggregates such as inside channels and surface protrusions. In summary, this is the first study that demonstrates the presence of Borrelia biofilm in human infected skin tissues

    On the derivative of the associated Legendre function of the first kind of integer order with respect to its degree

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    In our recent works [R. Szmytkowski, J. Phys. A 39 (2006) 15147; corrigendum: 40 (2007) 7819; addendum: 40 (2007) 14887], we have investigated the derivative of the Legendre function of the first kind, Pν(z)P_{\nu}(z), with respect to its degree ν\nu. In the present work, we extend these studies and construct several representations of the derivative of the associated Legendre function of the first kind, Pν±m(z)P_{\nu}^{\pm m}(z), with respect to the degree ν\nu, for m∈Nm\in\mathbb{N}. At first, we establish several contour-integral representations of ∂Pν±m(z)/∂ν\partial P_{\nu}^{\pm m}(z)/\partial\nu. They are then used to derive Rodrigues-type formulas for [∂Pν±m(z)/∂ν]ν=n[\partial P_{\nu}^{\pm m}(z)/\partial\nu]_{\nu=n} with n∈Nn\in\mathbb{N}. Next, some closed-form expressions for [∂Pν±m(z)/∂ν]ν=n[\partial P_{\nu}^{\pm m}(z)/\partial\nu]_{\nu=n} are obtained. These results are applied to find several representations, both explicit and of the Rodrigues type, for the associated Legendre function of the second kind of integer degree and order, Qn±m(z)Q_{n}^{\pm m}(z); the explicit representations are suitable for use for numerical purposes in various regions of the complex zz-plane. Finally, the derivatives [∂2Pνm(z)/∂ν2]ν=n[\partial^{2}P_{\nu}^{m}(z)/\partial\nu^{2}]_{\nu=n}, [∂Qνm(z)/∂ν]ν=n[\partial Q_{\nu}^{m}(z)/\partial\nu]_{\nu=n} and [∂Qνm(z)/∂ν]ν=−n−1[\partial Q_{\nu}^{m}(z)/\partial\nu]_{\nu=-n-1}, all with m>nm>n, are evaluated in terms of [∂Pν−m(±z)/∂ν]ν=n[\partial P_{\nu}^{-m}(\pm z)/\partial\nu]_{\nu=n}.Comment: LateX, 40 pages, 1 figure, extensive referencin
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