Quenched dynamics of classical isolated systems: the spherical spin model with two-body random interactions or the Neumann integrable model

We study the Hamiltonian dynamics of the spherical spin model with fully-connected two-body interactions drawn from a Gaussian probability distribution. In the statistical physics framework, the potential energy is of the so-called $p=2$ spherical disordered kind. Most importantly for our setting, the energy conserving dynamics are equivalent to the ones of the Neumann integrable system. We take initial conditions in thermal equilibrium and we subsequently evolve the configurations with Newton dynamics dictated by a different Hamiltonian. We identify three dynamical phases depending on the parameters that characterise the initial state and the final Hamiltonian. We obtain the {\it global} dynamical observables with numerical and analytic methods and we show that, in most cases, they are out of thermal equilibrium. We note, however, that for shallow quenches from the condensed phase the dynamics are close to (though not at) thermal equilibrium. Surprisingly enough, for a particular relation between parameters the global observables comply Gibbs-Boltzmann equilibrium. We next set the analysis of the system with finite number of degrees of freedom in terms of $N$ non-linearly coupled modes. We evaluate the mode temperatures and we relate them to the frequency-dependent effective temperature measured with the fluctuation-dissipation relation in the frequency domain, similarly to what was recently proposed for quantum integrable cases. Finally, we analyse the $N-1$ integrals of motion and we use them to show that the system is out of equilibrium in all phases, even for parameters that show an apparent Gibbs-Boltzmann behaviour of global observables. We elaborate on the role played by these constants of motion in the post-quench dynamics and we briefly discuss the possible description of the asymptotic dynamics in terms of a Generalised Gibbs Ensemble

Connecting the 3D DGS Calques3D with the CAS Maple

Many (2D) Dynamic Geometry Systems (DGSs) are able to export numeric coordinates and equations with numeric coefficients to Computer Algebra Systems (CASs). Moreover, different approaches and systems that link (2D) DGSs with CASs, so that symbolic coordinates and equations with symbolic coefficients can be exported from the DGS to the CAS, already exist. Although the 3D DGS Calques3D can export numeric coordinates and equations with numeric coefficients to Maple and Mathematica, it cannot export symbolic coordinates and equations with symbolic coefficients. A connection between the 3D DGS Calques3D and the CAS Maple, that can handle symbolic coordinates and equations with symbolic coefficients, is presented here. Its main interest is to provide a convenient time-saving way to explore problems and directly obtain both algebraic and numeric data when dealing with a 3D extension of "ruler and compass geometry". This link has not only educational purposes but mathematical ones, like mechanical theorem proving in geometry, geometric discovery (hypotheses completion), geometric loci finding... As far as we know, there is no comparable "symbolic" link in the 3D case, except the prototype 3D-LD (restricted to determining algebraic surfaces as geometric loci)

Assessment of real aging in selection process of replacement materials for stone monuments conservation

[EN] Reconstruction of monuments often raises the question of stones replacement. It must be aesthetically durable, which means the stone must age like the original one. This study presents an image processing chain, from capture to visualisation, to compare stones at different states of aging: recently extracted from quarry, weathered on old buildings, and cleaned on monuments recently restored. This tool includes: (1) a digital still camera calibration, (2) a chromatic adaptation transform and (3) a resizing process. To test it, a case study was conducted to assess the compatibility of three types of limestone. This graphical tool helps the selection of replacement materials by visual comparison between several possible stones in order to select them by aging properties and visual resemblance.[ES] En el ámbito de la sustitución de piedras en los monumentos, frecuentemente se plantea el problema de la selección de las piedras de reemplazo. De hecho, la reconstrucción debe ser estéticamente duradera, es decir, la piedra sustituida debe envejecer como la piedra original. Este estudio presenta una cadena de procesamiento de imágenes, desde la adquisición hasta la visualización, que permite comparar imágenes de piedras en varias etapas de su envejecimiento: recién extraída de la cantera, envejecida en edificios antiguos, y decapada con arena en monumentos recién restaurados. Esta herramienta incluye: (1) una calibración de cámara digital, (2) una transformación de adaptación cromática y (3) una etapa de redimensión. Para testear el método propuesto, un estudio de caso se llevó a cabo para evaluar la compatibilidad de tres tipos de caliza. Esta herramienta gráfica puede ayudar la selección de materiales de reemplazo con envejecimiento complejo como la piedra natural.Concha Lozano, N.; Lafon, D.; Eterradossi, O.; Gaudon, P. (2011). Assessment of real aging in selection process of replacement materials for stone monuments conservation. Virtual Archaeology Review. 2(3):27-31. https://doi.org/10.4995/var.2011.4579OJS273123BRILL, Michael H., "The relation between the color of the illuminant and the color of the illuminated object". Color Research & Application. (1995) 20: 70- 5. doi:10.1002/col.5080200112.)CHORRO E., PERALES E., de Fez D., LUQUE M. J., and MARTÍNEZ-VERDÚ F. M., "Application of the S-CIELAB color model to processed and calibrated images with a colorimetric dithering method," Optics Express 15, no. 12 (Juin 11, 2007): 7810-7817. http://dx.doi.org/10.1364/OE.15.007810FAIRCHILD M.D., "A Revision of CIECAM97s for Practical Applications ", dans Color Research & Applications, Wiley Interscience, vol. 25, no 4, August 2000, p. 260-266ICOMOS-ISCS, Illustrated glossary on stone deterioration patterns, 2008THORNBUSH. M.J. and VILES, H.A., "Photo-based decay mapping of replaced stone blocks on the boundary wall of Worcester College, Oxford". Building stone decay: from diagnosis to conservation. In, Prikryl, R. and Smith, B.J. (eds.) (2007) Geological Society Special Publication, 271: 69-75.P.THORNBUSH. M.J., "Grayscale calibration of outdoor photographic surveys of historical Stone Walls in Oxford, England," Color Research & Application 33, no. 1 (2, 2008): 61-67.STOKES M. (Hewlett-Packard), ANDERSON M. (Microsoft), CHANDRASEKAR S. (Microsoft), MOTTA R. (Hewlett-Packard) Version 1.10, November 5, 1996 "A Standard Default Color Space for the Internet: sRGB" ICC, [online] http://www.color.org/sRGB.xalter [Consulta: 22-04-2010]

(Non equilibrium) Thermodynamics of Integrable models: The Generalized Gibbs Ensemble description of the classical Neumann Model

We study a classical integrable (Neumann) model describing the motion of a particle on the sphere, subject to harmonic forces. We tackle the problem in the infinite dimensional limit by introducing a soft version in which the spherical constraint is imposed only on average over initial conditions. We show that the Generalized Gibbs Ensemble captures the long-time averages of the soft model. We reveal the full dynamic phase diagram with extended, quasi-condensed, coordinate-, and coordinate and momentum-condensed phases. The scaling properties of the fluctuations allow us to establish in which cases the strict and soft spherical constraints are equivalent, confirming the validity of the GGE hypothesis for the Neumann model on a large portion of the dynamic phase diagram.Comment: 5 pages, 3 figure

Characterization of Tungsten Inert Gas (TIG) Welding Fume Generated by Apprentice Welders.

Tungsten inert gas welding (TIG) represents one of the most widely used metal joining processes in industry. Its propensity to generate a greater portion of welding fume particles at the nanoscale poses a potential occupational health hazard for workers. However, current literature lacks comprehensive characterization of TIG welding fume particles. Even less is known about welding fumes generated by welding apprentices with little experience in welding. We characterized TIG welding fume generated by apprentice welders (N = 20) in a ventilated exposure cabin. Exposure assessment was conducted for each apprentice welder at the breathing zone (BZ) inside of the welding helmet and at a near-field (NF) location, 60cm away from the welding task. We characterized particulate matter (PM4), particle number concentration and particle size, particle morphology, chemical composition, reactive oxygen species (ROS) production potential, and gaseous components. The mean particle number concentration at the BZ was 1.69E+06 particles cm(-3), with a mean geometric mean diameter of 45nm. On average across all subjects, 92% of the particle counts at the BZ were below 100nm. We observed elevated concentrations of tungsten, which was most likely due to electrode consumption. Mean ROS production potential of TIG welding fumes at the BZ exceeded average concentrations previously found in traffic-polluted air. Furthermore, ROS production potential was significantly higher for apprentices that burned their metal during their welding task. We recommend that future exposure assessments take into consideration welding performance as a potential exposure modifier for apprentice welders or welders with minimal training

Sensitive photonic system to measure oxidative potential of airborne nanoparticles and ROS levels in exhaled air

A photonic system has been developed that enables sensitive quantitative determination of reactive oxygen species (ROS) - mainly hydrogen peroxide (H2O2) - in aerosol samples such as airborne nanoparticles and exhaled air from patients. The detection principle relies on the amplification of the absorbance under multiple scattering conditions due to optical path lengthening [1] and [2]. In this study, the presence of cellulose membrane that acts as random medium into the glass optical cell considerably improved the sensitivity of the detection based on colorimetric FOX assay (FeII/orange xylenol). Despite the loss of assay volume (cellulose occupies 75% of cell volume) the limit of detection is enhanced by one order of magnitude reaching the value of 9 nM (H2O2 equivalents). Spectral analysis is performed automatically with a periodicity of 5 to 15 s, giving rise to real-time ROS measurements. Moreover, the elution of air sample into the collection chamber via a micro-diffuser (impinger) enables quantitative determination of ROS contained in or generated from airborne samples. As proof-of-concept the photonic ROS detection system was used in the determination of both ROS generated from traffic pollution and ROS contained in the exhaled breath as lung inflammation biomarkers