12,867 research outputs found

    Reduction of noise in gyro outputs

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    Technique is described to reduce extraneous gyro output signals by using relatively inexpensive shrouds which do not increase power comsumption. Shrouds reduce noise by minimizing mass of gas spinning with rotor, reducing Reynolds number near rotor, and inducing laminar flow

    Disk tracing for B[e] supergiants in the Magellanic Clouds

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    B[e] supergiants are evolved massive stars with a complex circumstellar environment. A number of important emission features probe the structure and the kinematics of the circumstellar material. In our survey of Magellanic Cloud B[e] supergiants we focus on the [OI] and [CaII] emission lines, which we identified in four more objects.Comment: 2 pages; 1 figure; submitted to the proceedings of the Physics of Evolved Stars - A conference dedicated to the memory of Olivier Chesneau, Nice, France, June 8-12, 201

    Off-shell Top Quarks with One Jet at the LHC: A comprehensive analysis at NLO QCD

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    We present a comprehensive study of the production of top quark pairs in association with one hard jet in the di-lepton decay channel at the LHC. Our predictions, accurate at NLO in QCD, focus on the LHC Run II with a center-of-mass energy of 13 TeV. All resonant and non-resonant contributions at the perturbative order O(αs4α4){\cal O}(\alpha_s^4 \alpha^4) are taken into account, including irreducible backgrounds to ttˉjt\bar{t}j production, interferences and off-shell effects of the top quark and the WW gauge boson. We extensively investigate the dependence of our results upon variation of renormalisation and factorisation scales and parton distribution functions in the quest for an accurate estimate of the theoretical uncertainties. Additionally, we explore a few possibilities for a dynamical scale choice with the goal of stabilizing the perturbative convergence of the differential cross sections far away from the ttˉt\bar{t} threshold. Results presented here are particularly relevant for searches of new physics as well as for precise measurements of the top-quark fiducial cross sections and top-quark properties at the LHC.Comment: 51 pages, 36 figures, 6 tables, version to appear in JHE

    Mapping vesicle shapes into the phase diagram: A comparison of experiment and theory

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    Phase-contrast microscopy is used to monitor the shapes of micron-scale fluid-phase phospholipid-bilayer vesicles in aqueous solution. At fixed temperature, each vesicle undergoes thermal shape fluctuations. We are able experimentally to characterize the thermal shape ensemble by digitizing the vesicle outline in real time and storing the time-sequence of images. Analysis of this ensemble using the area-difference-elasticity (ADE) model of vesicle shapes allows us to associate (map) each time-sequence to a point in the zero-temperature (shape) phase diagram. Changing the laboratory temperature modifies the control parameters (area, volume, etc.) of each vesicle, so it sweeps out a trajectory across the theoretical phase diagram. It is a nontrivial test of the ADE model to check that these trajectories remain confined to regions of the phase diagram where the corresponding shapes are locally stable. In particular, we study the thermal trajectories of three prolate vesicles which, upon heating, experienced a mechanical instability leading to budding. We verify that the position of the observed instability and the geometry of the budded shape are in reasonable accord with the theoretical predictions. The inability of previous experiments to detect the ``hidden'' control parameters (relaxed area difference and spontaneous curvature) make this the first direct quantitative confrontation between vesicle-shape theory and experiment.Comment: submitted to PRE, LaTeX, 26 pages, 11 ps-fi

    Rigid invariance as derived from BRS invariance: The abelian Higgs model

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    Consequences of a symmetry, e.g.\ relations amongst Green functions, are renormalization scheme independently expressed in terms of a rigid Ward identity. The corresponding local version yields information on the respective current. In the case of spontaneous breakdown one has to define the theory via the BRS invariance and thus to construct rigid and current Ward identity non-trivially in accordance with it. We performed this construction to all orders of perturbation theory in the abelian Higgs model as a prelude to the standard model. A technical tool of interest in itself is the use of a doublet of external scalar ``background'' fields. The Callan-Symanzik equation has an interesting form and follows easily once the rigid invariance is established.Comment: 33 pages, Plain Te

    Gyro noise study program Final report

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    Reducing noise induced by turbulent windage torques within gimbal of fluid rotor gyroscop

    Generalized Massive Gravity and Galilean Conformal Algebra in two dimensions

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    Galilean conformal algebra (GCA) in two dimensions arises as contraction of two copies of the centrally extended Virasoro algebra (t→t,x→ϵxt\rightarrow t, x\rightarrow\epsilon x with ϵ→0\epsilon\rightarrow 0). The central charges of GCA can be expressed in term of Virasoro central charges. For finite and non-zero GCA central charges, the Virasoro central charges must behave as asymmetric form O(1)±O(1ϵ)O(1)\pm O(\frac{1}{\epsilon}). We propose that, the bulk description for 2d GCA with asymmetric central charges is given by general massive gravity (GMG) in three dimensions. It can be seen that, if the gravitational Chern-Simons coupling 1μ\frac{1}{\mu} behaves as of order O(1ϵ\frac{1}{\epsilon}) or (μ→ϵμ\mu\rightarrow\epsilon\mu), the central charges of GMG have the above ϵ\epsilon dependence. So, in non-relativistic scaling limit μ→ϵμ\mu\rightarrow\epsilon\mu, we calculated GCA parameters and finite entropy in term of gravity parameters mass and angular momentum of GMG.Comment: 9 page
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