Efficient solution of 3D electromagnetic eddy-current problems within the finite volume framework of OpenFOAM

Eddy-current problems occur in a wide range of industrial and metallurgical applications where conducting material is processed inductively. Motivated by realising coupled multi-physics simulations, we present a new method for the solution of such problems in the finite volume framework of foam-extend, an extended version of the very popular OpenFOAM software. The numerical procedure involves a semi-coupled multi-mesh approach to solve Maxwell's equations for non-magnetic materials by means of the Coulomb gauged magnetic vector potential and the electric scalar potential. The concept is further extended on the basis of the impressed and reduced magnetic vector potential and its usage in accordance with Biot-Savart's law to achieve a very efficient overall modelling even for complex three-dimensional geometries. Moreover, we present a special discretisation scheme to account for possible discontinuities in the electrical conductivity. To complement our numerical method, an extensive validation is completing the paper, which provides insight into the behaviour and the potential of our approach.Comment: 47 pages, improved figures, updated references, fixed typos, reverse phase shift, consistent use of inner produc

Aislamiento de cryptococcus neoformans var. Grubii en un felino doméstico. Reporte de caso

Se halló evidencia clínica, citológica y serológica de una infección natural con Criptococcus en un felino criollo proveniente de La Mesa, Cundinamarca (Colombia). C. neoformans var. grubii fue aislado del cultivo de secreciones nasales del paciente. Para el tratamiento específico se utilizó fluconazol, que mostró buenos resultados a partir del primer mes de haber iniciado su administración

Synchronizing the helicity of Rayleigh-B\'enard convection by a tide-like electromagnetic forcing

We present results on the synchronization of the helicity in a liquid-metal Rayleigh-B\'enard (RB) experiment under the influence of a tide-like electromagnetic forcing with azimuthal wavenumber m=2. We show that for a critical forcing strength the typical Large Scale Circulation (LSC) in the cylindrical vessel of aspect ratio unity is entrained by the period of the tide-like forcing, leading to synchronized helicity oscillations with opposite signs in two half-spaces. The obtained experimental results are consistent with and supported by numerical simulations. A similar entrainment mechanism for the helicity in the solar tachocline may be responsible for the astonishing synchronization of the solar dynamo by the 11.07-year triple synodic alignment cycle of the tidally dominant planets Venus, Earth and Jupiter

Effect of training on agility at high altitude in Border Collie dogs on some electrocardiographic variables: preliminary analysis

El objetivo del estudio fue conocer el efecto en reposo de algunas variables electrocardiográficas en perros Border Collie practicantes de la disciplina deportiva Agility en gran altitud (2600 msnm). Se evaluaron 15 perros (grupo atletas), pertenecientes a diferentes equipos de «agility» de la ciudad de Bogotá D.C., Colombia y 16 perros Border Collie no practicantes de actividades deportivas (grupo no atletas) de la misma ciudad. Las variables electrocardiográficas analizadas, en electrocardiografía de 5 min fueron: análisis de poder espectral con los componentes de alta y baja frecuencia y balance LF/ HF (simpático/vagal). Dentro del método de dominio de tiempo se determinó el promedio de RR (NN) y SDNN. En 100 latidos consecutivos se midió la duración de QRS y QT, corregido por la fórmula de Van de Water (QTcV) y hallada su variabilidad por desviación estándar (SDQT). Se realizó observación de la dispersión de QT de cada uno de los individuos usando un gráfico de Poincaré. Los perros del grupo de atletas evidenciaron valores de HF más altos y de LF y LF/HF más bajos que el grupo de perros no atletas (p<0.05). Así mismo, los valores de RR y SDNN, longitud de QRS e intervalo QT fueron mayores en los perros atletas (p<0.05). No se encontraron diferencias entre los grupos en QTcV y SDQT. Los resultados obtenidos evidencian diferencias claras en varios componentes de la variabilidad de frecuencia cardíaca (VFC) entre perros Border Collie atletas y no atletas, con actividad diferenciada del sistema nervioso autónomo. El ejercicio y la altitud serían responsables de los hallazgos en QT y QRS.The aim of this study was to investigate the effect of the practice of the sport discipline of Agility at high altitude (2600 meters above sea level) on some electrocardiographic variables in Border Collie dogs at rest. Fifteen dogs (athlete group), belonging to different «Agility» teams from the city of Bogota D.C., Colombia and 16 Border Collie dogs, not trained in regular or athletic activities (non-athlete group) from the same city were evaluated. The electrocardiographic variables analyzed (5-min electrocardiography) were: spectral power density with high and low frequency components and LF/HF (sympathetic/vagal) balance. Within the time domain method, the mean RR (NN) and SDNN were determined. The duration of QRS and QT was corrected (QTc) and its variability by standard deviation (SDQT) was measured in 100 consecutive beats. Observation of the QT dispersion of each individual was performed by Poincaré plot. The athlete group showed higher values of HF and of LF, and LF/HF lower than the non-athlete group (p<0.05). The values of RR and SDNN, QRS length and QT interval were also higher in athlete dogs (p<0.05). No differences were found between the groups in QTcV and SDQT. The results showed differences in several components of the heart rate variability (HRV) between Border Collie athletes and non-athletes, with differentiated activity of the autonomic nervous system. Exercise and altitude would be responsible for QT and QRS findings