A computational multiscale homogenization framework accounting for inertial effects: application to acoustic metamaterials modelling

A framework, based on an extended Hill–Mandel principle accounting for inertial effects (Multiscale Virtual Work principle), is developed for application to acoustic problems in the context of metamaterials modelling. The classical restrictions in the mean values of the micro-displacement fluctuations and their gradients are then accounted for in a saddle-point formulation of that variational principle in terms of Lagrange functionals. A physical interpretation of the involved Lagrange multipliers can then be readily obtained. The framework is specifically tailored for modelling the phenomena involved in Locally Resonant Acoustic Metamaterials (LRAM). In this view, several additional hypotheses based on scale separation are used to split the fully coupled micro-macro set of equations into a quasi-static and an inertial system. These are then solved by considering a projection of the microscale equations into their natural modes, which allows for a low-cost computational treatment of the multiscale problem. On this basis, the issue of numerically capturing the local resonance phenomena in a FE context is addressed. Objectivity of the obtained results in terms of the macroscopic Finite Element (FE) discretization is checked as well as accuracy of the homogenization procedure by comparing with direct numerical simulations (DNS). The appearance of local resonance band-gaps is then modelled for a homogeneous 2D problem and its extension to multi-layered macroscopic material is presented as an initial attempt towards acoustic metamaterial design for tailored band-gap attenuatio

Consulta rápida de traumatología

Objetivos: El aumento de presión asistencial requiere medidas organizativas para descongestionar el Servicio de Urgencias Traumatológicas (SUT), atendiendo los problemas de lista de espera en consultas externas y programación quirúrgica e intentando obtener diagnósticos y tratamientos precoces. Analizamos los resultados de implementación de la CRT creada para dicho fin. Metodología: Estudio descriptivo, retrospectivo, de base poblacional, valorando la totalidad de pacientes atendidos en la CRT de la Clínica USP-Palmaplanas, de 160 camas, durante el periodo de enero a mayo 2009 estableciendo indicadores de actividad y calidad específicos. Resultados: Pacientes atendidos en el SUT durante el periodo de estudio 6864, pacientes derivados a la CRT 824(12%), motivo de consulta (patología rodilla 16%,pie 13%,columna cervical 12%,lumbar 12%,muñeca 12%, tobillo 11%, hombro 6%,otros 18%), estudio de concordancia diagnóstica 89%, tiempo de espera desde atención en SUT hasta valoración en la CRT (<48h 30 %,3-7 días 51 %,8-12 días 16 %,>12 días 3%), tiempo de espera desde valoración inicial hasta final en la CRT (mismo día 30%,<8 días 54 %,8-12 días 13%,>12 días 3%), pacientes derivados a Rehabilitación desde la CRT 40%, altas domiciliarias 30%, cirugías programadas desde CRT 21%, derivaciones a otros servicios (Neurocirugía 6%,Reumatología 3%), revaloraciones por el mismo motivo en SUT 1%. Conclusiones: La CRT ha reducido el tiempo de espera en el diagnóstico y tratamiento de los pacientes derivados desde el SUT. Es útil para mejorar la accesibilidad a consultas externas y programación quirúrgica. Agiliza la fluidez en los circuitos hospitalarios y garantiza la seguridad al paciente.Aims: The rise of pressure in emergency admissions require organisation measures to decongest the Trauma Emergency Service (TES), addressing the issues of waiting lists and outpatient surgical schedule and trying to get diagnosis and / or specific and early treatments. Methods: Descriptive, retrospective population-based study, assessing all patients seen in the RATC at Clinica USP Palmaplanas, a 160 bed hospital, during the period from January to May 2009, establishing quality indicators and specific activities. We analyse the results of implementing the RACT created for that purpose Results: Patients treated at the TES during the period of study: 6864; patients referred to the RACT: 824 (12%); reason for consultation (knee lesions 16%, foot 13%, cervical spine 12%, lumbar spine 12%, wrist 12% , ankle 11%, shoulder 6%, other 18%); study of diagnostic concordance 89%, waiting time from TES from assessment to evaluation at the RACT (<48h 30%, 3-7 days 51%, 8-12 days 16%, >12 days 3%); waiting time from initial to final assessment in the RACT (same day 30%, <8 days 54%, 8-12 days 13%, > 12 days 3%). Patients referred to rehabilitation from the RACT 40%, discharged home 30%, scheduled surgeries from RACT 21%, referrals to other services (6% Neurosurgery, 3% Rheumatology), re-evaluations for the same reason in TES 1%. Conclusions: RACT reduced the waiting time for diagnosis and treatment of patients referred from the TES. It is helpful for improving the accessibility of outpatient visits and surgical schedule, improving the flow of the hospital channels and ensuring patient safety

A computational multiscale homogenization framework accounting for inertial effects: application to acoustic metamaterials modelling

A framework, based on an extended Hill–Mandel principle accounting for inertial effects (Multiscale Virtual Work principle), is developed for application to acoustic problems in the context of metamaterials modelling. The classical restrictions in the mean values of the micro-displacement fluctuations and their gradients are then accounted for in a saddle-point formulation of that variational principle in terms of Lagrange functionals. A physical interpretation of the involved Lagrange multipliers can then be readily obtained. The framework is specifically tailored for modelling the phenomena involved in Locally Resonant Acoustic Metamaterials (LRAM). In this view, several additional hypotheses based on scale separation are used to split the fully coupled micro-macro set of equations into a quasi-static and an inertial system. These are then solved by considering a projection of the microscale equations into their natural modes, which allows for a low-cost computational treatment of the multiscale problem. On this basis, the issue of numerically capturing the local resonance phenomena in a FE context is addressed. Objectivity of the obtained results in terms of the macroscopic Finite Element (FE) discretization is checked as well as accuracy of the homogenization procedure by comparing with direct numerical simulations (DNS). The appearance of local resonance band-gaps is then modelled for a homogeneous 2D problem and its extension to multi-layered macroscopic material is presented as an initial attempt towards acoustic metamaterial design for tailored band-gap attenuation.Peer ReviewedPostprint (author's final draft

Experimental and numerical assessment of local resonance phenomena in 3D-printed acoustic metamaterials

The so called Locally Resonant Acoustic Metamaterials (LRAM) are a new kind of artificially engineered materials capable of attenuating acoustic waves. As the name suggests, this phenomenon occurs in the vicinity of internal frequencies of the material structure, and can give rise to acoustic bandgaps. One possible way to achieve this is by considering periodic arrangements of a certain topology (unit cell), smaller in size than the characteristic wavelength. In this context, a computational model based on a homogenization framework has been developed from which one can obtain the aforementioned resonance frequencies for a given LRAM unit cell design in the sub-wavelength regime, which is suitable for low-frequency applications. Aiming at validating both the proposed numerical model and the local resonance phenomena responsible for the attenuation capabilities of such materials, a 3D-printed prototype consisting of a plate with a well selected LRAM unit cell design has been built and its acoustic response to normal incident waves in the range between 500 and 2000 Hz has been tested in an impedance tube. The results demonstrate the attenuating capabilities of the proposed design in the targeted frequency range for normal incident sound pressure waves and also establish the proposed formulation as the fundamental base for the computational design of 3D-printed LRAM-based structures.Peer ReviewedPostprint (author's final draft

Computational design of locally resonant acoustic metamaterials

The so-called Locally Resonant Acoustic Metamaterials (LRAM) are considered for the design of specifically engineered devices capable of stopping waves from propagating in certain frequency regions (bandgaps), this making them applicable for acoustic insulation purposes. This fact has inspired the design of a new kind of lightweight acoustic insulation panels with the ability to attenuate noise sources in the low frequency range (below 5000 Hz) without requiring thick pieces of very dense materials. A design procedure based on different computational mechanics tools, namely, (1) a multiscale homogenization framework, (2) model order reduction strategies and (3) topological optimization procedures, is proposed. It aims at attenuating sound waves through the panel for a target set of resonance frequencies as well as maximizing the associated bandgaps. The resulting design’s performance is later studied by introducing viscoelastic properties in the coating phase, in order to both analyse their effects on the overall design and account for more realistic behaviour. The study displays the emerging field of Computational Material Design (CMD) as a computational mechanics area with enormous potential for the design of metamaterial-based industrial acoustic parts.Peer ReviewedPostprint (author's final draft

Acute effects of small changes in bicycle saddle height on gross efficiency and lower limb kinematics

P. 784-791El objetivo del presente estudio fue evaluar los efectos agudos de pequeños cambios en la altura del sillín de bicicleta sobre la eficiencia bruta y cinemática de las extremidades inferiores. Ciclistas bien entrenados (n = 14) realizaron una prueba de pedaleo sub-máximo (~ 70-75% del VO2max) a cadencia constante (90 rpm). Consistió en tres series aleatorias de 6 minutos con la altura de sillín preferida, 2% más alta y 2% más baja. La eficiencia bruta (GE) fue significativamente menor y el consumo de oxígeno (VO2) fue significativamente mayor levantando el sillín (GE = 19.9 ± 1.5%; VO2 = 43.8 ml.kg-1.min-1) que al bajarlo (GE = 20.4 ± 1.3%; VO2 = 42.8 ml.kg-1.min-1). Adicionalmente, un cambio de 0.8% en GE (20.6 ± 1.6 a 19.8 ± 1.6%, p < 0.05) se observó al comparar las posiciones donde se obtuvieron los mejores y peores GE. También se observó un efecto significativo en la cinemática de las extremidades inferiores (p <0.05) al efectuar pequeños cambios en la altura del sillín. Las diferencias entre las posiciones de silla de montar más bajas y más altas, en las articulaciones de cadera, rodilla y tobillo fueron un aumento de la extensión (~ 4, 7 y 8º, respectivamente), una disminución de la flexión (~3, 4 y 4º respectivamente) y, en consecuencia, un aumento del rango de movimiento (~1, 3 y 4º respectivamente). Los resultados del presente estudio indican que pequeños cambios en la altura del sillín afectaron a GE y a la cinemática de las extremidades inferiores. Los cambios observados en la cinemática de las extremidades inferiores podrían justificar, en parte, los cambios de GES

Design and validation of a questionnaire about the perceptions of dual career student-athletes (ESTPORT)

Abstract The purpose of this paper was to design and validate a questionnaire about the perceptions of elite studentathletes at university relating to their dual career. In the initial creation of the instrument, constructs were defined and three dimensions were established: academic life, sporting life and sports tutor. After a process of ‘back translation’, experts (n = 8) agreed the construct to ensure content validity, the dimensions and the questionnaire questions. Statistical analysis of the items showed adequate comprehension to confirm content validity of participants (n = 30). In construct validity (n = 73), the results showed correct psychometric quality, internal consistency, reliability and adequacy of the structural model. The instrument had evidence of external validity, since the results were congruent with the main findings of the research. This questionnaire was found to be a valid and reliable assessment instrument, consisting of 84 questions (in Spanish and English language), that enables the perception of elite student-athletes to be known about their dual career whilst at university

Diseño y validación del cuestionario de percepción de los estudiantes universitarios-deportistas de alto nivel sobre la carrera dual (ESTPORT).

El objetivo de la presente investigación fue diseñar y validar un instrumento de evaluación para conocer la percepción de los estudiantes universitarios-deportistas de alto nivel sobre la carrera dual. En la creación inicial del instrumento se definió el constructo y se establecieron tres dimensiones: carrera académica, carrera deportiva y tutor deportivo. En la validez de contenido, tras un proceso de traducción inversa, los expertos (n = 8) valoraron positivamente el constructo, las dimensiones y las preguntas cuestionario. Los resultados estadísticos de los ítems mostraron la adecuada validez de comprensión de los participantes (n = 30). En la validez de constructo (n = 73), las propiedades psicométricas mostraron la adecuada calidad psicométrica, consistencia interna, fiabilidad y bondad de ajuste. El instrumento también contó con evidencias externas de validez, dado que los resultados fueron en la línea de lo que demuestra la literatura. Por ello, este trabajo ofrece un cuestionario válido y fiable de 84 preguntas (en español y en inglés) que permite medir la percepción de los estudiantes universitarios-deportistas de alto nivel sobre la carrera dual.Actividad Física y Deport

Dynamics of brain networks in aesthetic appreciation

Neuroimage experiments have been essential for identifying active brain networks. During cognitive tasks as in, e.g., aesthetic appreciation, such networks include regions that belong to the default mode network (DMN). Theoretically, DMN activity should be interrupted during cognitive tasks demanding attention, as is the case for aesthetic appreciation. Analyzing the functional connectivity dynamics along three temporal windows and two conditions, beautiful and not beautiful stimuli, here we report experimental support for the hypothesis that aesthetic appreciation relies on the activation of two different networks, an initial aesthetic network and a delayed aesthetic network, engaged within distinct time frames. Activation of the DMN might correspond mainly to the delayed aesthetic network. We discuss adaptive and evolutionary explanations for the relationships existing between the DMN and aesthetic networks and offer unique inputs to debates on the mind/brain interaction

Diseño y validación del cuestionario de percepción de los estudiantes universitarios-deportistas de alto nivel sobre la carrera dual (ESTPORT)

The purpose of this paper was to design and validate a questionnaire about the perceptions of elite studentathletes at university relating to their dual career. In the initial creation of the instrument, constructs were defined and three dimensions were established: academic life, sporting life and sports tutor. After a process of ‘back translation’, experts (n = 8) agreed the construct to ensure content validity, the dimensions and the questionnaire questions. Statistical analysis of the items showed adequate comprehension to confirm content validity of participants (n = 30). In construct validity (n = 73), the results showed correct psychometric quality, internal consistency, reliability and adequacy of the structural model. The instrument had evidence of external validity, since the results were congruent with the main findings of the research. This questionnaire was found to be a valid and reliable assessment instrument, consisting of 84 questions (in Spanish and English language), that enables the perception of elite student-athletes to be known about their dual career whilst at universityEl objetivo de la presente investigación fue diseñar y validar un instrumento de evaluación para conocer la percepción de los estudiantes universitarios-deportistas de alto nivel sobre la carrera dual. En la creación inicial del instrumento se definió el constructo y se establecieron tres dimensiones: carrera académica, carrera deportiva y tutor deportivo. En la validez de contenido, tras un proceso de traducción inversa, los expertos (n = 8) valoraron positivamente el constructo, las dimensiones y las preguntas cuestionario. Los resultados estadísticos de los ítems mostraron la adecuada validez de comprensión de los participantes (n = 30). En la validez de constructo (n = 73), las propiedades psicométricas mostraron la adecuada calidad psicométrica, consistencia interna, fiabilidad y bondad de ajuste. El instrumento también contó con evidencias externas de validez, dado que los resultados fueron en la línea de lo que demuestra la literatura. Por ello, este trabajo ofrece un cuestionario válido y fiable de 84 preguntas (en español y en inglés) que permite medir la percepción de los estudiantes universitarios-deportistas de alto nivel sobre la carrera dualActividad Física y Deport