1,276 research outputs found

    Wireless connection of bioimpedance measurement circuits based-on AD5933: A state of the art

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    This contribution describes the state of the art in bioimpedance measurements through development boards to build portable devices that perform in-situ measurements and potential technological opportunities to separate the AD5933 integrated circuit from a PC. The presented research is based on prototypes developed with the aim of achieving portability with the AD5933 integrated circuit and it includes different wireless connection methods and a varied software design for the acquisition, visualization and storage of data obtained from biological systems. As a result, this work describes twenty articles that perform wireless connectivity using different microprocessors for different applications. These references seek to explore technological trends, deficiencies, and opportunities for future development projects in telemedicine.Fil: Dell'osa, Antonio Héctor. Universidad Nacional de Tierra del Fuego. Instituto de Desarrollo Economico E Innovacion; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Apátiga Pérez, D. S.. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados. Departamento de Investigaciones Educativas.; MéxicoFil: Suárez Pérez, K. I.. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados. Departamento de Investigaciones Educativas.; MéxicoFil: Ramírez Barrios, M.. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados. Departamento de Investigaciones Educativas.; México4th Latin American Conference on Bioimpedance 2021San Luis PotosíMéxicoSocieda Mexicana de Ingeniería Biomédic

    Measuring the magnetic field of a trans-equatorial loop system using coronal seismology

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    Context. EIT waves are freely-propagating global pulses in the low corona which are strongly associated with the initial evolution of coronal mass ejections (CMEs). They are thought to be large-Amplitude, fast-mode magnetohydrodynamic waves initially driven by the rapid expansion of a CME in the low corona. Aims. An EIT wave was observed on 6 July 2012 to impact an adjacent trans-equatorial loop system which then exhibited a decaying oscillation as it returned to rest. Observations of the loop oscillations were used to estimate the magnetic field strength of the loop system by studying the decaying oscillation of the loop, measuring the propagation of ubiquitous transverse waves in the loop and extrapolating the magnetic field from observed magnetograms. Methods. Observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory (SDO/AIA) and the Coronal Multi-channel Polarimeter (CoMP) were used to study the event. An Empirical Mode Decomposition analysis was used to characterise the oscillation of the loop system in CoMP Doppler velocity and line width and in AIA intensity. Results. The loop system was shown to oscillate in the 2nd harmonic mode rather than at the fundamental frequency, with the seismological analysis returning an estimated magnetic field strength of 5.5 ± 1.5 G. This compares to the magnetic field strength estimates of 1-9 G and 3-9 G found using the measurements of transverse wave propagation and magnetic field extrapolation respectively.Fil: Long, David M.. Colegio Universitario de Londres; Reino UnidoFil: Valori, G.. Colegio Universitario de Londres; Reino UnidoFil: Pérez-Suárez, D.. Colegio Universitario de Londres; Reino UnidoFil: Morton, R. J.. University Of Northumbria; Reino UnidoFil: Vasquez, Alberto Marcos. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

    Computer modeling of radiofrequency cardiac ablation: 30 years of bioengineering research

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    [EN] This review begins with a rationale of the importance of theoretical, mathematical and computational models for radiofrequency (RF) catheter ablation (RFCA). We then describe the historical context in which each model was developed, its contribution to the knowledge of the physics of RFCA and its implications for clinical practice. Next, we review the computer modeling studies intended to improve our knowledge of the biophysics of RFCA and those intended to explore new technologies. We describe the most important technical details of the implementation of mathematical models, including governing equations, tissue properties, boundary conditions, etc. We discuss the utility of lumped element models, which despite their simplicity are widely used by clinical researchers to provide a physical explanation of how RF power is absorbed in different tissues. Computer model verification and validation are also discussed in the context of RFCA. The article ends with a section on the current limitations, i.e. aspects not yet included in state-of-the-art RFCA computer modeling and on future work aimed at covering the current gapsGrant RTI2018-094357-B-C21 funded by MCIN/AEI/10.13039/501100011033 (Spanish Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación)González-Suárez, A.; Pérez, JJ.; Irastorza, RM.; D Avila, A.; Berjano, E. (2022). Computer modeling of radiofrequency cardiac ablation: 30 years of bioengineering research. Computer Methods and Programs in Biomedicine. 214:1-16. https://doi.org/10.1016/j.cmpb.2021.10654611621

    Evolution of the magnetic field distribution of active regions

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    AIMS: Although the temporal evolution of active regions (ARs) is relatively well understood, the processes involved continue to be the subject of investigation. We study how the magnetic field of a series of ARs evolves with time to better characterise how ARs emerge and disperse. METHODS: We examined the temporal variation in the magnetic field distribution of 37 emerging ARs. A kernel density estimation plot of the field distribution was created on a log-log scale for each AR at each time step. We found that the central portion of the distribution is typically linear, and its slope was used to characterise the evolution of the magnetic field. RESULTS: The slopes were seen to evolve with time, becoming less steep as the fragmented emerging flux coalesces. The slopes reached a maximum value of ∼-1.5 just before the time of maximum flux before becoming steeper during the decay phase towards the quiet-Sun value of ∼-3. This behaviour differs significantly from a classical diffusion model, which produces a slope of -1. These results suggest that simple classical diffusion is not responsible for the observed changes in field distribution, but that other processes play a significant role in flux dispersion. CONCLUSIONS. We propose that the steep negative slope seen during the late-decay phase is due to magnetic flux reprocessing by (super)granular convective cells

    Evaluation experiment of ontology tools’ interoperability with the WebODE ontology engineering workbench

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    This paper presents the results of the interoperability experiment proposed in EON2003, using the following ontology tools: Protégé-2000 and WebODE. We will show which knowledge is preserved and which knowledge is lost in the import/export processes between tools when using RDF(S) as an intermediate language

    The “Alluvial Mesovoid Shallow Substratum”, a new subterranean habitat

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    Received: April 5, 2013; Accepted: August 23, 2013; Published: October 4, 2013In this paper we describe a new type of subterranean habitat associated with dry watercourses in the Eastern Iberian Peninsula, the “Alluvial Mesovoid Shallow Substratum” (alluvial MSS). Historical observations and data from field sampling specially designed to study MSS fauna in the streambeds of temporary watercourses support the description of this new habitat. To conduct the sampling, 16 subterranean sampling devices were placed in a region of Eastern Spain. The traps were operated for 12 months and temperature and relative humidity data were recorded to characterise the habitat. A large number of species was captured, many of which belonged to the arthropod group, with marked hygrophilous, geophilic, lucifugous and mesothermal habits. In addition, there was also a substantial number of species showing markedly ripicolous traits. The results confirm that the network of spaces which forms in alluvial deposits of temporary watercourses merits the category of habitat, and here we propose the name of “alluvial MSS”. The “alluvial MSS” may be covered or not by a layer of soil, is extremely damp, provides a buffer against above ground temperatures and is aphotic. In addition, compared to other types of MSS, it is a very unstable habitat. It is possible that the “alluvial MSS” may be found in other areas of the world with strongly seasonal climatic regimes, and could play an important role as a biogeographic corridor and as a refuge from climatic changes.The Spanish Ministry of Science and Innovation for funded this research project (CGL2010-19924) and the Ministry of Education and Science programme "Juan de la Cierva". This research Project (CGL2010-19924) was funded by the Spanish Ministry of Science and Innovation.The Ministry of Education and Science programme "Juan de la Cierva" funded the research activity of one of the authors (A. J-V.).Peer reviewe
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