Topology, Random Matrix Theory and the spectrum of the Wilson Dirac operator

We study the spectrum of the hermitian Wilson Dirac operator in the epsilon-regime of QCD in the quenched approximation and compare it to predictions from Wilson Random Matrix Theory. Using the distributions of single eigenvalues in the microscopic limit and for specific topological charge sectors, we examine the possibility of extracting estimates of the low energy constants which parametrise the lattice artefacts in Wilson chiral perturbation theory. The topological charge of the field configurations is obtained from a field theoretical definition as well as from the flow of eigenvalues of the hermitian Wilson Dirac operator, and we determine the extent to which the two are correlated.Comment: 7 pages, 5 figures, proceedings of the XXIX International Symposium on Lattice Field Theory - Lattice 2011, July 10-16, 2011, Squaw Valley, Lake Tahoe, Californi

Spin chain simulations with a meron cluster algorithm

We apply a meron cluster algorithm to the XY spin chain, which describes a quantum rotor. This is a multi-cluster simulation supplemented by an improved estimator, which deals with objects of half-integer topological charge. This method is powerful enough to provide precise results for the model with a theta-term - it is therefore one of the rare examples, where a system with a complex action can be solved numerically. In particular we measure the correlation length, as well as the topological and magnetic susceptibility. We discuss the algorithmic efficiency in view of the critical slowing down. Due to the excellent performance that we observe, it is strongly motivated to work on new applications of meron cluster algorithms in higher dimensions.Comment: 18 pages, 9 figures, published versio

An easily prepared graphene oxide-ionic liquid hybrid nanomaterial for micro-solid phase extraction and preconcentration of Hg in water samples

A preconcentration method based on the use of graphene oxide (GO) functionalized with an ionic liquid (IL) was developed for trace Hg determination in water samples. The IL-GO hybrid nanomaterial was prepared by a simple procedure to functionalize GO with the IL 1-butyl-3-dodecylimidazolium bromide ([C4C12im]Br) and its performance as a sorption material for Hg was evaluated. A microcolumn filled with the IL-GO nanomaterial was used for preconcentration and determination of Hg followed by electrothermal atomic absorption spectrometry (ETAAS) detection. Mercury was retained at pH 5.0 and 20% (v/v) HNO3 was used for the elution of Hg from the microcolumn. The effects of different variables, including the sample volume, extraction time, sample flow rate, type and concentration of eluent and eluent flow rate were carefully studied. High retention efficiency (100%) was achieved with the proposed IL-GO sorption nanomaterial without the need for additional chelating reagents or derivatization reagents, which is an important advantage compared with traditional preconcentration methods. A sensitivity enhancement factor of 100 and a low detection limit of 14 ng L-1 were obtained under optimal experimental conditions. The proposed method can be considered as a simple, cost-effective and efficient alternative for Hg determination in water samples like river, rain, mineral and tap water.Fil: Cruz Sotolongo, Annaly. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Martinis, Estefanía Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo; Argentin

Le regroupement en flexion: un traitement antalgique non pharmacologique pour le prématuré : revue de la littérature

Depuis 1980, la douleur du nouveau-né prématuré n’est plus remise en question. Cependant, celui-ci subit de nombreux soins invasifs lors de son hospitalisation en néonatologie. La prise de sang représente notamment le quart des procédures administrées au prématuré. Dans un souci de confort et de sécurité de leur patient, les infirmières en néonatologie tentent de soulager le nouveau-né prématuré à l’aide d’interventions non pharmacologiques en combinaison avec les traitements médicamenteux

Hadron masses in QCD with one quark flavour

One-flavour QCD - a gauge theory with SU(3) colour gauge group and a fermion in the fundamental representation - is studied by Monte Carlo simulations. The mass spectrum of hadronic bound states is investigated in a volume with extensions of L ~ 4.4r_0 (~2.2fm) at two different lattice spacings: a ~ 0.37r_0 (~0.19fm) and a ~ 0.27r_0 (~0.13fm). The lattice action is Symanzik tree-level-improved Wilson action for the gauge field and (unimproved) Wilson action for the fermion.Comment: 21 pages, 4 figures; further references adde

Slackline: création d'un programme d'entraînement progressif de l'équilibre

La slackline commence à faire son apparition dans le milieu thérapeutique. Cette discipline exige des capacités précises qui allient concentration et équilibre. C’est ce dernier terme que nous cherchons à développer ici. Les études sont encore très restreintes et aucun programme d’entraînement n’a été validé.Slacklinen, das als eigenständiger Sport angesehen werden kann, wird immer öfter als Therapie eingesetzt. Diese Disziplin benötigt präzise Fähigkeiten wie Konzentration und Gleichgewicht. In dieser Arbeit werden wir den Aspekt des Gleichgewichts bearbeiten. Es gibt nur wenige Studien zum Thema Gleichgewicht, Slackline und Therapie und kein Trainingsprogramm wurde validiert

Intra-regional classification of grape seeds produced in Mendoza province (Argentina) by multi-elemental analysis and chemometrics tools

The feasibility of the application of chemometric techniques associated with multi-element analysis for the classification of grape seeds according to their provenance vineyard soil was investigated. Grape seed samples from different localities of Mendoza province (Argentina) were evaluated. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the determination of twenty-nine elements (Ag, As, Ce, Co, Cs, Cu, Eu, Fe, Ga, Gd, La, Lu, Mn, Mo, Nb, Nd, Ni, Pr, Rb, Sm, Te, Ti, Tl, Tm, U, V, Y, Zn and Zr). Once the analytical data were collected, supervised pattern recognition techniques such as linear discriminant analysis (LDA), partial least square discriminant analysis (PLS-DA), k-nearest neighbors (k-NN), support vector machine (SVM) and Random Forest (RF) were applied to construct classification/discrimination rules. The results indicated that nonlinear methods, RF and SVM, perform best with up to 98% and 93% accuracy rate, respectively, and therefore are excellent tools for classification of grapes.Fil: Canizo, Brenda Vanina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Escudero, Leticia Belén. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Pérez, María Belén. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Pellerano, Roberto Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Química Básica y Aplicada del Nordeste Argentino. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Química Básica y Aplicada del Nordeste Argentino; ArgentinaFil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Química Básica y Aplicada del Nordeste Argentino. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Química Básica y Aplicada del Nordeste Argentino; Argentin

Spectral properties of the Wilson Dirac operator in the ϵ\epsilon-regime

We investigate the spectral properties of the Wilson Dirac operator in quenched QCD in the microscopic regime. We distinguish the topological sectors using the index as determined by the Wilson flow method. Consequently, the distributions of the low-lying eigenvalues of the Wilson Dirac operator can be compared in each of the topological sectors to predictions from random matrix theory applied to the $\epsilon$-regime of chiral perturbation theory. We find rather good agreement for volumes as small as $(1.5 \, \text{fm})^4$ and lattice spacings as coarse as $0.1\, \text{fm}$, and demonstrate that it is indeed possible to extract low-energy constants for Wilson fermions from the spectral properties of the Wilson Dirac operator.Comment: Changed normalizations for some of the results, cosmetic updates to several plots. Conclusions not affected. Version accepted for publication by JHEP. 22 pages, 12 figure

Development of analytic methods of separation-preconcentration with magnetic ionic liquids for the ultra-sensitive determination of trace elements

En el presente proyecto de investigación se propone el desarrollo de métodos analíticos modernos de alta sensibilidad, para la determinación y análisis de especiación de elementos traza. Para ello, se innovará en al diseño de nuevas técnicas de microextracción líquido-líquido (LLME) y de preconcentración, basadas en el uso de solventes de última generación denominados "Líquidos Iónicos Magnéticos" (MILs). Las técnicas de microextracción basadas en MILs serán fundamentales para obtener métodos analíticos de alta sensibilidad y selectividad al asociarse a detectores espectrométricos atómicos (AAS, AFS e ICP-MS). El proyecto contribuirá también con métodos que a la vez posean alto grado de sustentabilidad ambiental y se rijan por el concepto de la Química Verde ("Green Chemistry"), debido a la posibilidad que ofrecen los MILs de ser separados, recuperados y transportados por la aplicación de un campo magnético, abriendo nuevas posibilidades más allá del contexto analítico y vinculadas a tecnologías de separación inéditas. Se plantea la resolución de problemas usuales de las técnicas LLME, como son su escasa automatización y la necesidad de disponer de tediosas rutinas para la separación de fases, tales como la centrifugación, la cual insume tiempo considerable y reduce la Finalmente, los métodos analíticos desarrollados serán herramientas fundamentales para la obtención de datos concretos acerca de la calidad de recursos naturales (aguas de diverso origen) y alimentos (ajo, vinos, uvas y mosto) de importancia estratégica para el desarrollo social y productivo de la provincia de Mendoza.In this research project, it is proposed the development of modern high sensitivity analytical methods for the determination and analysis of speciation of trace elements. To do this, it will innovate in the design of new liquid-liquid microextraction (LLME) and pre-concentration techniques, based on the use of state-of-the-art solvents called "Magnetic Ionic Liquids" (MILs). The techniques of microextracción based on MILs will be fundamental to obtain analytical methods of high sensitivity and selectivity when associated with atomic spectrometric detectors (AAS, AFS and ICP-MS). The project will also contribute with methods that also have a high degree of environmental sustainability and are governed by the concept of Green Chemistry, due to the possibility offered by the MILs of being separated, recovered and transported by the application of a magnetic field, opening new possibilities beyond the analytical context and linked to unprecedented separation technologies. It is proposed to solve the usual problems of LLME techniques, such as its low automation and the need to have tedious routines for phase separation, such as centrifugation, which takes considerable time and reduces the analytical frequency.Finally, the analytical methods developed will be fundamental tools for obtaining specific data about the quality of natural resources (waters of different origin) and food (garlic, wines, grapes and must) of strategic importance for the social and productive development of the province of Mendoza