Three-dimensional multifractal analysis of trabecular bone under clinical computed tomography

Purpose: An adequate understanding of bone structural properties is critical for predicting fragility conditions caused by diseases such as osteoporosis, and in gauging the success of fracture prevention treatments. In this work we aim to develop multiresolution image analysis techniques to extrapolate high-resolution images predictive power to images taken in clinical conditions. Methods: We performed multifractal analysis (MFA) on a set of 17 ex vivo human vertebrae clinical CT scans. The vertebræ failure loads (FFailure) were experimentally measured. We combined bone mineral density (BMD) with different multifractal dimensions, and BMD with multiresolution statistics (e.g., skewness, kurtosis) of MFA curves, to obtain linear models to predict FFailure. Furthermore we obtained short- and long-term precisions from simulated in vivo scans, using a clinical CT scanner. Ground-truth data - high-resolution images - were obtained with a High-Resolution Peripheral Quantitative Computed Tomography (HRpQCT) scanner. Results: At the same level of detail, BMD combined with traditional multifractal descriptors (Lipschitz-Hölder exponents), and BMD with monofractal features showed similar prediction powers in predicting FFailure (87%, adj. R2). However, at different levels of details, the prediction power of BMD with multifractal features raises to 92% (adj. R2) of FFailure. Our main finding is that a simpler but slightly less accurate model, combining BMD and the skewness of the resulting multifractal curves, predicts 90% (adj. R2) of FFailure. Conclusions: Compared to monofractal and standard bone measures, multifractal analysis captured key insights in the conditions leading to FFailure. Instead of raw multifractal descriptors, the statistics of multifractal curves can be used in several other contexts, facilitating further research.Fil: Baravalle, Rodrigo Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; ArgentinaFil: Thomsen, Felix Sebastian Leo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur; ArgentinaFil: Delrieux, Claudio Augusto. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lu, Yongtao. Dalian University of Technology; ChinaFil: Gómez, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; ArgentinaFil: Stošić, Borko. Universidade Federal Rural Pernambuco; BrasilFil: Stošić, Tatijana. Universidade Federal Rural Pernambuco; Brasi

Fracture toughness of cemented carbides obtained by electrical resistance sintering

The unique combination of hardness, toughness and wear resistance exhibited by WC-Co cemented carbides (hardmetals) has made them a preeminent material choice for extremely demanding applications, such as metal cutting/forming tools or mining bits, in which improved and consistent performance together with high reliability are required. The high fracture toughness values exhibited by hardmetals are mainly due to ductile ligament bridging and crack deflection (intrinsic to carbides). In this work two WC-Co grades obtained by using the electric resistance sintering technique are studied. The relationships between the process parameters (cobalt volume fraction, sintering current and time, die materials, etc.), the microstructural characteristics (porosity, cobalt volume fraction, carbide grain size, binder thickness and carbide contiguity) and mechanical properties (Vickers hardness and fracture toughness) are established and discussed. Also the presence of microstructural anisotropy and residual stresses is studied. The sintering process at 7 kA, 600 ms and 100 MPa, in an alumina die, followed by a treatment of residual stress relief (800 °C, 2 h in high vacuum), allows to obtain WC-Co pellets with the best balance between an homogeneous microstructure and mechanical behaviour.EU for funding this research with in the framework of the EU 7th Framework FoF.NMP.2013-10 608729 EFFIPRO Projec

Bayesian parameter estimation for targeted anisotropic gravitational-wave background

Extended sources of the stochastic gravitational backgrounds have been conventionally searched on the spherical harmonics bases. The analysis during the previous observing runs by the ground-based gravitational-wave detectors, such as LIGO and Virgo, have yielded the constraints on the angular power spectrum Cℓ, yet it lacks the capability of estimating other parameters such as a spectral index. In this paper, we introduce an alternative Bayesian formalism to search for such stochastic signals with a particular distribution of anisotropies on the sky. This approach provides a Bayesian posterior of model parameters and also enables selection tests among different signal models. While the conventional analysis fixes the highest angular scale a priori, here we show a more systematic and quantitative way to determine the cutoff scale based on a Bayes factor, which depends on the amplitude and the angular scale of observed signals. Also, we analyze the third observing runs of LIGO and Virgo for the population of millisecond pulsars and obtain the 95% constraints of the signal amplitude, ϵ<2.7×10-8PGC2018-094773-B-C32, CEX2020-001007-

WSPH and ISPH Calculations of a Counter-Rotating Vortex Dipole

Viscosity and vorticity are magnitudes playing an important role in many engineering physical phenomena such as: boundary layer separation, transition flows, shear flows, etc., demonstrating the importance of the vortical viscous flows commonly used among the SPH community. The simulation presented here, describes the physics of a pair of counter-rotating vortices in which the strain field felt by each vortex is due to the other one. Different from the evolution of a single isolated vortex, in this case each vortex is subjected to an external stationary strain field generated by the other, making the streamlines deform elliptically. To avoid the boundary influence, a large computational domain has been used ensuring insignificant effect of the boundary conditions on the solution. The performance of the most commonly used viscous models in simulating laminar flows, Takeda’s (TVT), Morris’ (MVT) and Monaghan-Cleary’s (MCGVT) has been discussed comparing their results. These viscous models have been used under two different compressibility hypotheses. Two cases have been numerically analyzed in this presentation. In the first case, a 2D system of two counter-rotating Lamb O seen vortices is considered. At first, the system goes through a rapid relaxation process in which both vortices equilibrate each other. This quasi-steady state is obtained after the relaxation phase is advected at a constant speed and slowly evolves owing to viscous diffusion. The results of the different Lamb-O seen numerical solutions have been validated with good agreement by comparison with the numerical results of a finite element code (ADFC) solution. A second case, somewhat more complex than the previous one, is a 3D Batchelor vortex dipole obtained by adding an axial flow to the system of the first case. The Batchelor vortex model considered here is a classical option normally used to model the structure of trailing vortices in the far-wake of an aircraft

Prevalence of metabolic syndrome in workers of the mother-child center Miguel Grau, Chaclacayo, Peru

Introducción: Las enfermedades crónicas en el Perú están incrementando de manera preocupante, y el síndrome metabólico (SM) sigue la misma tendencia. Ante esta problemática le corresponde al equipo de salud cumplir un rol en educación y prevención. Objetivos: Determinar la prevalencia de síndrome metabólico en trabajadores de un centro materno infantil y examinar su relación con variables sociodemográficas e índice de masa corporal (IMC). Diseño: Estudio descriptivo, corte transversal. Lugar: Centro Materno Infantil (CMI) Miguel Grau, de la DISA IV Lima Este, Chaclacayo, Lima, Perú. Participantes: Trabajadores del centro de salud. Intervenciones: A 108 trabajadores que dieron su consentimiento informado se les encuestó para recoger los datos sociodemográficos. Además se les midió peso, talla, perímetro de cintura, presión arterial y, en una muestra, de 5 mL de sangre venosa en ayunas, se determinó glicemia y perfil lipídico. Se realizó análisis estadístico descriptivo y pruebas U de Mann Whitney, Kruskal Wallis y chi2; se consideró para todas las pruebas un nivel de significancia de 0,05 Principales medidas de resultados: Síndrome metabólico, perfil lipídico, categorías del IMC, glicemia, número de factores de riesgo. Resultados: El 35,2% de los trabajadores presentó síndrome metabólico. Se observó asociación del SM con la edad y categorías del IMC. No se encontró asociación con el sexo, tampoco con el grupo ocupacional. Conclusiones: La tercera parte de los trabajadores del CMI Miguel Grau presentó SM, valor superior al de la población peruana.Introduction: Chronic diseases in Peru are increasing at alarming rate and the metabolic syndrome (MS) follows the same trend. Faced with this problem the health team must play a role in education and prevention. Objectives: To determine the prevalence of metabolic syndrome in workers of a primary health care center and to examine its relationship with sociodemographic variables and body mass index (BMI). Design: Cross-sectional study. Location: Maternal Child Center (WCC) Miguel Grau, DISA IV Lima Este, Peru. Participants: Health workers. Interventions: All 108 workers who gave informed consent were surveyed for demographic data, and weight, height, waist circumference and blood pressure were obtained. In a 5 mL serum sample fasting blood glucose and lipid profile were determined. Descriptive statistics and U-Mann Whitney, Kruskal Wallis and chi2 tests were done; P value of 0.05 was used to determine significance. Main outcome measures: Metabolic syndrome, lipid profile, BMI categories, glycemia, number of risk factors. Results: 35.2% of workers had metabolic syndrome. SM was associated with age and BMI. No association was found with gender or occupational group. Conclusions: One-third of workers at the WCC Miguel Grau had MS, higher rate than in the Peruvian population

Extending the 4-Variable Approach to Cyber-Physical Systems: A Practical Experience

Abstract. Cyber-physical systems are a new research discipline that involves many areas. The key concept behind this discipline has to do with a strong interaction between the physical world and a computing system, which should be transparent to an external observer. Thus, it cannot be determined whether the system&apos;s behavior is due to the influence of the environment or the actions of the computing system. In this paper, a requirement analysis approach for these systems is presented. It is called 3D Approach and it is based on the well-known 4-Variable Model. The 3D Approach came out as the result of systematizing practical experiences taken from the design of a biodigester

Efectos aerodinámicos de hélices pusher sobre un flap en el ala

Se presenta la continuación de un estudio experimental de los efectos producidos por el campo de flujo generado por una hélice en configuración pusher sobre un ala dotada de un flap simple. El objetivo del trabajo es analizar las características del flujo de aire sobre el sistema y así poder determinar la efectividad del comando de flap. Se realizaron ensayos en túnel de viento a distintas posiciones de la hélice respecto del flap, deflexiones de flap y velocidades de revolución de hélice adquiriendo las presiones en frecuencia sobre el extradós e intradós. A partir de estas mediciones se obtuvieron los efectos sobre el sistema en estudio pudiendo caracterizar la influencia de las variables sobre el campo fluidodinámico de las presiones.Facultad de Ingenierí

Efectos aerodinámicos de hélices pusher sobre un flap en el ala

Se presenta la continuación de un estudio experimental de los efectos producidos por el campo de flujo generado por una hélice en configuración pusher sobre un ala dotada de un flap simple. El objetivo del trabajo es analizar las características del flujo de aire sobre el sistema y así poder determinar la efectividad del comando de flap. Se realizaron ensayos en túnel de viento a distintas posiciones de la hélice respecto del flap, deflexiones de flap y velocidades de revolución de hélice adquiriendo las presiones en frecuencia sobre el extradós e intradós. A partir de estas mediciones se obtuvieron los efectos sobre el sistema en estudio pudiendo caracterizar la influencia de las variables sobre el campo fluidodinámico de las presiones.Facultad de Ingenierí

Efectos aerodinámicos de hélices pusher sobre un flap en el ala

Se presenta la continuación de un estudio experimental de los efectos producidos por el campo de flujo generado por una hélice en configuración pusher sobre un ala dotada de un flap simple. El objetivo del trabajo es analizar las características del flujo de aire sobre el sistema y así poder determinar la efectividad del comando de flap. Se realizaron ensayos en túnel de viento a distintas posiciones de la hélice respecto del flap, deflexiones de flap y velocidades de revolución de hélice adquiriendo las presiones en frecuencia sobre el extradós e intradós. A partir de estas mediciones se obtuvieron los efectos sobre el sistema en estudio pudiendo caracterizar la influencia de las variables sobre el campo fluidodinámico de las presiones.Facultad de Ingenierí

Influencia del bienestar psicológico en la vulnerabilidad a conductas adictivas en adolescentes escolarizados de 15 a 18 años. Estudio piloto.

Numerosas investigaciones (Casullo, 2002; Castro Solano, 2002; Rodrigo y otros, 2004; Observatorio Argentino de Drogas, 2009), han demostrado la relación inversa entre el nivel de bienestar psicológico (BP) y conductas de riesgo en adolescentes. La hipótesis de este estudio es que la identificación de indicadores de bajo nivel de BP puede contribuir a la detección de adolescentes en riesgo adictivo