Sliding Luttinger liquid phases

We study systems of coupled spin-gapped and gapless Luttinger liquids. First, we establish the existence of a sliding Luttinger liquid phase for a system of weakly coupled parallel quantum wires, with and without disorder. It is shown that the coupling can {\it stabilize} a Luttinger liquid phase in the presence of disorder. We then extend our analysis to a system of crossed Luttinger liquids and establish the stability of a non-Fermi liquid state: the crossed sliding Luttinger liquid phase (CSLL). In this phase the system exhibits a finite-temperature, long-wavelength, isotropic electric conductivity that diverges as a power law in temperature $T$ as $T \to 0$. This two-dimensional system has many properties of a true isotropic Luttinger liquid, though at zero temperature it becomes anisotropic. An extension of this model to a three-dimensional stack exhibits a much higher in-plane conductivity than the conductivity in a perpendicular direction.Comment: Revtex, 18 pages, 8 figure

Photoinduced 3D orientational order in side chain liquid crystalline azopolymers

We apply experimental technique based on the combination of methods dealing with principal refractive indices and absorption coefficients to study the photoinduced 3D orientational order in the films of liquid crystalline (LC) azopolymers. The technique is used to identify 3D orientational configurations of trans azobenzene chromophores and to characterize the degree of ordering in terms of order parameters. We study two types of LC azopolymers which form structures with preferred in-plane and out-of-plane alignment of azochromophores, correspondingly. Using irradiation with the polarized light of two different wavelengths we find that the kinetics of photoinduced anisotropy can be dominated by either photo-reorientation or photoselection mechanisms depending on the wavelength. We formulate the phenomenological model describing the kinetics of photoinduced anisotropy in terms of the isomer concentrations and the order parameter tensor. We present the numerical results for absorption coefficients that are found to be in good agreement with the experimental data. The model is also used to interpret the effect of changing the mechanism with the wavelength of the pumping light.Comment: uses revtex4 28 pages, 10 figure

Performance and Results of the Triple Buffering Built-In in a Raspberry PI to Optimize the Distribution of Information from a Smart Sensor

“ The final publication is available at Springer via http://dx.doi.org/ 10.1007/978-3-319-07593-8_33"Currently, 3D sensors can be considered an evolution of cameras by providing the image with its depth information. These sensors have a generic function and the programmer has to process the received information in order to be adapted and used in a specific environment. In robots navigation, the 3D information can be useful for basic behaviours such as obstacles avoidance or even more complex behaviours such as maps generation . In this article an image management system provided by the xTion intelligent sensor is presented. The xTion sensor provides a VGA image and a 3D depth, which allows it to be used for several purposes. In order to distribute the data, it is acquired, processed and sent to several clients with a triple buffer system modified to serve the most recent image to the client. The system is programmed in C for Linux and built-in in a Raspberry PI. The article exposes the performance and results from monitoring the frame's delay comparing it with a simple and a double buffer system widely used in this kind of systems.Coordinated project COBAMI: Mission-based Hierarchical Control. Education and Science Department, Spanish Government. CICYT: MICINN: DPI2011-28507-C02-01/02 and project “Real time distributed control systems” of the Support Program for Research and Development 2012 UPV (PAID-06-12).Jiménez García, JL.; Poza Luján, JL.; Posadas Yagüe, JL.; Baselga Masiá, D.; Simó Ten, JE. (2014). Performance and Results of the Triple Buffering Built-In in a Raspberry PI to Optimize the Distribution of Information from a Smart Sensor. En Distributed Computing and Artificial Intelligence, 11th International Conference. Springer. 279-286. https://doi.org/10.1007/978-3-319-07593-8_33S279286Brignell, J.E.: The future of intelligent sensors: a problem of technology or ethics? Sensors and Actuators 56, 11–15 (1996)Fernandes, J., Laranjeira, J., Novais, P., Marreiros, G., Neves, J.: A Context Aware Architecture to Support People with Partial Visual Impairments. In: Omatu, S., Neves, J., Rodriguez, J.M.C., Paz Santana, J.F., Gonzalez, S.R. (eds.) Distrib. Computing & Artificial Intelligence. AISC, vol. 217, pp. 333–340. Springer, Heidelberg (2013)Chien-Hui, L., Kuan-Wei, L., Ting-Hua, C., Che-Chen, C., Charles, H.-P.: Fall Detection by a SVM-Based Cloud System with Motion Sensors. In: Yueh-Min, H., Han-Chieh, C., Der-Jiunn, D., James J (Jong Hyuk), P. (eds.) Advanced Technologies, Embedded and Multimedia for Human-centric Computing. LNEE, vol. 260, pp. 37–45. Springer, Heidelberg (2014)Grzejszczak, T., Mikulski, M., Szkodny, T., Jędrasiak, K.: Gesture Based Robot Control. In: Bolc, L., Tadeusiewicz, R., Chmielewski, L.J., Wojciechowski, K. (eds.) ICCVG 2012. LNCS, vol. 7594, pp. 407–413. Springer, Heidelberg (2012)Lee, C.S., Gyu, M.L., Woo, S.R.: Standardization and challenges of smart ubiquitous networks in ITU-T. IEEE Communications Magazine 51(10), 102–110 (2013)Dias, D.M., Mukherjee, R., Sitaram, D., Tewari, R.: Buffering and Caching in Large-Scale Video Servers. In: Prac. of COMPCON (1995)Tagami, Y., Watanabe, M., Yamaguchi, Y.: Development Environment of 3D Graphics Systems. Fujitsu Scientific & Technical Journal 49(1), 64–70 (2013)Khan, S., Bailey, D., Gupta, G.: Simulation of Triple Buffer Scheme. In: Second International Conference on Computer and Electrical Engineering (2009)ASUS: Xtion Pro Live, http://www.asus.comEdwards, C.: Not-so-humble raspberry pi gets big ideas. Engineering & Technology 8(3), 30–33 (2013)Poza-Luján, J.L., Posadas-Yagüe, J.L., Simó-Ten, J.E.: Quality of Control and Quality of Service in Mobile Robot Navigation. International Journal of Imaging and Robotics 8(1) (2014)Norman Villaroman, N., Rowe, D., Swan, B.: Teaching natural user interaction using OpenNI and the Microsoft Kinect sensor. In: Proceedings of the 2011 Conference on Information Technology Education (SIGITE 2011), pp. 227–232. ACM, New York (2011)Bradski, G., Kaehler, A.: Learning OpenCV: Computer vision with the OpenCV library. O’reilly (2008)Ollero, A.: Intelligent mobile robot navigation. STAR, vol. 16. Springer, Heidelberg (2005)Freese, M., Singh, S., Ozaki, F., Matsuhira, N.: Virtual Robot Experimentation Platform V-REP: A Versatile 3D Robot Simulator. In: Ando, N., Balakirsky, S., Hemker, T., Reggiani, M., von Stryk, O. (eds.) SIMPAR 2010. LNCS (LNAI), vol. 6472, pp. 51–62. Springer, Heidelberg (2010

An Oscillatory Contractile Pole-Force Component Dominates the Traction Forces Exerted by Migrating Amoeboid Cells

We used principal component analysis to dissect the mechanics of chemotaxis of amoeboid cells into a reduced set of dominant components of cellular traction forces and shape changes. The dominant traction force component in wild-type cells accounted for ~40% of the mechanical work performed by these cells, and consisted of the cell attaching at front and back contracting the substrate towards its centroid (pole-force). The time evolution of this pole-force component was responsible for the periodic variations of cell length and strain energy that the cells underwent during migration. We identified four additional canonical components, reproducible from cell to cell, overall accounting for an additional ~20% of mechanical work, and associated with events such as lateral protrusion of pseudopodia. We analyzed mutant strains with contractility defects to quantify the role that non-muscle Myosin II (MyoII) plays in amoeboid motility. In MyoII essential light chain null cells the polar-force component remained dominant. On the other hand, MyoII heavy chain null cells exhibited a different dominant traction force component, with a marked increase in lateral contractile forces, suggesting that cortical contractility and/or enhanced lateral adhesions are important for motility in this cell line. By compressing the mechanics of chemotaxing cells into a reduced set of temporally-resolved degrees of freedom, the present study may contribute to refined models of cell migration that incorporate cell-substrate interactions

A multigrid-Lanczos algorithm for the numerical solutions of nonlinear eigenvalue problems

We study numerical methods for solving nonlinear elliptic eigenvalue problems which contain folds and bifurcation points. First we present some convergence theory for the MINRES, a variant of the Lanczos method. A multigrid-Lanczos method is then proposed for tracking solution branches of associated discrete problems and detecting singular points along solution branches. The proposed algorithm has the advantage of being robust and can be easily implemented. It can be regarded as a generalization and an improvement of the continuation-Lanczos algorithm. Our numerical results show the efficiency of this algorithm

Domain decomposition algorithms for fourth-order nonlinear elliptic eigenvalue problems

We study domain decomposition methods for fourth-order plate problems. The well-known von Karman equations are used as our model problem. By exploiting the symmetry of the domain, the solution of the original problem can be obtained by solving those associated reduced problems, which are defined on subdomains with appropriate boundary conditions. We show how nonoverlapping and overlapping domain decomposition methods can be used to solve the reduced problems. For the linearized von Karman equation, we present preconditioners using both Fourier analysis and probing techniques for the interface systems, which are similar to those derived by Chan et al. Finally, we compare the efficiency of various domain decomposition preconditioners for solving the von Karman equations. (C) 2003 Elsevier B.V. All rights reserved

A spectral-Galerkin continuation method using Chebyshev polynomials for the numerical solutions of the Gross-Pitaevskii equation

We study an efficient spectral-Galerkin continuation method (SGCM) and two-grid centered difference approximations for the numerical solutions of the Gross-Pitaevskii equation (GPE), where the second kind Chebyshev polynomials are used as the basis functions for the trial function space. Some basic formulae for the SGCM are derived so that the eigenvalues of the associated linear eigenvalue problems can be easily computed. The SGCM is implemented to investigate the ground and first excited-state solutions of the GPE. Both the parabolic and quadruple-well trapping potentials are considered. We also study Bose-Einstein condensates (BEC) in optical lattices, where the periodic potential described by the sine or cosine functions is imposed on the GPE. Of particular interest here is the investigation of symmetry-breaking solutions. Sample numerical results are reported. (C) 2010 Elsevier B.V. All rights reserved