Domain walls in supersymmetric QCD: from weak to strong coupling

We consider domain walls that appear in supersymmetric QCD with Nf < Nc massive flavours. In particular, for 2 Nf < Nc we explicitly construct the domain walls that interpolate between vacua labeled by i and (i+ N_f). We show that these solutions are Bogomol'nyi-Prasad-Sommerfield (BPS) saturated for any value of the mass of the matter fields. This fact allows us to evaluate the large mass limit of these domain walls. We comment on the relevance of these solutions for supersymmetric gluodynamics.Comment: 4 pages, 4 figures, LaTex, uses psfig.st

Efeito do pré-resfriamento de frutos de cupuaçu na aceitação sensorial do néctar.

A região Amazônica possui as melhores condições edafoclimáticas para o desenvolvimento do cupuaçuzeiro. No entanto, temperatura e umidade relativa do ar elevadas, condições de cultivo, colheita e armazenamento inadequados, além das características intrínsecas do fruto acabam desencadeando e acelerando o processo de deterioração pós-colheita. Após a coleta, o fruto apresenta alta perecibilidade, devendo ser consumido em dois ou três dias quando não processado. Diante disso, objetivou-se com este trabalho avaliar o efeito do pré-resfriamento dos frutos na aceitação sensorial de néctar de cupuaçu. Foram realizados dois experimentos. No primeiro, os frutos foram armazenados a temperatura ambiente por 6 dias e no segundo os frutos foram armazenados sob refrigeração a 10°C por 15 dias. Para cada experimento, foram avaliados frutos não submetidos a pré-resfriamento e frutos submetidos a um pré-resfriamento por imersão em água gelada a 10°C por 133 minutos. Os frutos foram despolpados a cada 3 dias de armazenamento, analisados quanto aos teores de sólidos solúveis, acidez titulável e açúcares, e utilizados para fabricação do néctar, que foi submetido a análise de aceitação sensorial. Em frutos armazenados a temperatura ambiente, o pré-resfriamento melhorou a aceitação sensorial do néctar de cupuaçu ao final do tempo de armazenamento. Em frutos armazenados sob refrigeração, o pré-resfriamento não teve efeito sobre a aceitação sensorial do néctar de cupuaçu

Low-lying magnetic excitations of doubly-closed-shell nuclei and nucleon-nucleon effective interactions

We have studied the low lying magnetic spectra of 12C, 16O, 40Ca, 48Ca and 208Pb nuclei within the Random Phase Approximation (RPA) theory, finding that the description of low-lying magnetic states of doubly-closed-shell nuclei imposes severe constraints on the spin and tensor terms of the nucleon-nucleon effective interaction. We have first made an investigation by using four phenomenological effective interactions and we have obtained good agreement with the experimental magnetic spectra, and, to a lesser extent, with the electron scattering responses. Then we have made self-consistent RPA calculations to test the validity of the finite-range D1 Gogny interaction. For all the nuclei under study we have found that this interaction inverts the energies of all the magnetic states forming isospin doublets.Comment: 19 pages, 13 figures, 7 tables, accepted for publication in Phys. Rev.

One-loop effects in a self-dual planar noncommutative theory

We study the UV properties, and derive the explicit form of the one-loop effective action, for a noncommutative complex scalar field theory in 2+1 dimensions with a Grosse-Wulkenhaar term, at the self-dual point. We also consider quantum effects around non-trivial minima of the classical action which appear when the potential allows for the spontaneous breaking of the U(1) symmetry. For those solutions, we show that the one-loop correction to the vacuum energy is a function of a special combination of the amplitude of the classical solution and the coupling constant.Comment: Version to appear in JHE

Fracture of disordered solids in compression as a critical phenomenon: I. Statistical mechanics formalism

This is the first of a series of three articles that treats fracture localization as a critical phenomenon. This first article establishes a statistical mechanics based on ensemble averages when fluctuations through time play no role in defining the ensemble. Ensembles are obtained by dividing a huge rock sample into many mesoscopic volumes. Because rocks are a disordered collection of grains in cohesive contact, we expect that once shear strain is applied and cracks begin to arrive in the system, the mesoscopic volumes will have a wide distribution of different crack states. These mesoscopic volumes are the members of our ensembles. We determine the probability of observing a mesoscopic volume to be in a given crack state by maximizing Shannon's measure of the emergent crack disorder subject to constraints coming from the energy-balance of brittle fracture. The laws of thermodynamics, the partition function, and the quantification of temperature are obtained for such cracking systems.Comment: 11 pages, 2 figure

Validación del monitor de medición de la grasa corporal por impedancia bioeléctrica OMRON BF 300

ObjetivosValorar la precisión del monitor de grasa corporal por impedancia bioeléctrica OMRON BF 300 y validar su medición del porcentaje de grasa corporal (%GC) frente a la ecuación de Siri. Diseño. Estudio descriptivo, transversal.EmplazamientoAtención primaria. Centros de Salud Coronel de Palma y San Fernando, Móstoles.ParticipantesEn la valoración de la precisión del monitor participaron 88 personas y 91 en la validación.Mediciones y resultados principalesLas determinaciones de %GC se realizaron por triplicado, anotándose la media. La precisión se evaluó mediante el coeficiente de correlación intraclase (CCI) y el coeficiente de variación (CV). La validez, mediante el error técnico, el CCI y el método de Bland-Altman. En la ecuación de Siri la densidad corporal se calculó con la ecuación de Durnin-Womersley. Precisión: el CCI fue de 0,999 y el CV de 0,4 ± 0,03. Validación: la diferencia de %GC monitor (26,6 ± 9,1%) – ecuación de Siri (27,8 ± 8,2%) fue de –1,27% (p < 0,01; IC del 95%, –1,97 a –0,57), el error técnico del monitor del 2,2% y el CCI de 0,956 (IC del 95%, 0,9335–0,9710), situándose un 80,2% de las diferencias monitor – ecuación por debajo del 5%, con un intervalo de concordancia por el método de Bland-Altman de +5,45 a –7,99%.ConclusionesEl monitor OMRON BF 300 satisface los criterios de precisión (CCI > 0,95 y CV bajo) y validación (error técnico excelente, CCI > 0,75 y diferencias clínicamente aceptables) y supone una alternativa válida a los pliegues cutáneos en la valoración nutricional del paciente.ObjectivesTo assess the accuracy of the OMRON BF 300 body fat monitor using bioelectric impedance and to validate its measurement of body fat percentage (BF%) against the Siri equation.DesignCross-sectional descriptive study.SettingPrimary care. Coronel de Palma and San Fernando Health Centres, Móstoles.Participants88 people took part in the assessment of the accuracy of the monitor, and 91 in the validation.Measurements and main resultsThe BF% were recorded in triplicate, with the mean being the figure noted. Precision was evaluated through the intra-class correlation coefficient (ICC) and the coefficient of variation (CV); validity, through technical error, the ICC and the Bland-Altman method. In the Siri equation, body density was calculated through the Durnin-Womersley equation. Precision: ICC was 0.999 and CV 0.4 ± 0.03. Validation: the difference between the BF% monitor (26.6 ± 9.1%) and the Siri equation (27.8 ± 8.2%) was –1.27% (p < 0.01; 95% CI –1.97 to –0.57); the technical error of the monitor was 2.2% and of the ICC 0.956 (95% CI, 0.9335–0.9710). Thus, 80.2% of the monitor-equation differences were below 5%, with a concordance interval under the Bland-Altman method of +5.45 to –7.99%.ConclusionsThe OMRON BF 300 monitor satisfies the precision criteria (ICC > 0.95 and low CV) and validation (excellent technical error, ICC > 0.75 and clinically acceptable differences) and is a valid alternative to cutaneous folds as a method of assessing nutrition of the patient

Supersymmetry, quark confinement and the harmonic oscillator

We study some quantum systems described by noncanonical commutation relations formally expressed as [q,p]=ihbar(I + chi H), where H is the associated (harmonic oscillator-like) Hamiltonian of the system, and chi is a Hermitian (constant) operator, i.e. [H,chi]=0 . In passing, we also consider a simple (chi=0 canonical) model, in the framework of a relativistic Klein-Gordon-like wave equation.Comment: To be published in Journal of Physics A: Mathematical and Theoretical (2007

Skyrmions and edge spin excitations in quantum Hall droplets

We present an analysis of spin-textures in Quantum Hall droplets, for filling factors $\nu \simeq 1$. Analytical wavefunctions with well defined quantum numbers are given for the low-lying states of the system which result to be either bulk skyrmions or edge spin excitations. We compute dispersion relations and study how skyrmions become ground states of the Quantum Hall droplet at $\nu \gtrsim 1$. A Hartree-Fock approximation is recovered and discussed for those spin textures.Comment: RevTeX, four postscript figures appende