Asteroseismology of delta Scuti stars in open clusters: Praesepe

The present paper provides a general overview of the asteroseismic potential of delta Scuti stars in clusters, in particular focusing on convection diagnostics. We give a summarise of the last results obtained by the authors for the Praesepe cluster of which five delta Scuti stars are analysed. In that work, linear analysis is confronted with observations, using refined descriptions for the effects of rotation on the determination of the global stellar parameters and on the adiabatic oscillation frequency computations. A single, complete, and coherent solution for all the selected stars is found, which lead the authors to find important restrictions to the convection description for a certain range of effective temperatures. Furthermore, the method used allowed to give an estimate of the global parameters of the selected stars and constrain the cluster.Comment: 6 pages, 1 figure. Accepted for publication in Communications in Asteroseismolog

Performance Of The High Speed Rail In Spain In The Context Of The New Regulation Framework. Evidence From The Madrid-Seville Hsr Corridor

The ambitious planned development of the high-speed rail (HSR) network in Spain requires the implementation of new sector regulations to fully achieve its objectives, namely to make the sector more competitive and to promote a more balanced and efficient transport system. For this purpose, the Spanish administration recently launched the new Rail Sector Act (39/2003), on a national regulatory framework. The planned liberalisation process foresees the end of the monopoly of the Spanish state operator RENFE, opening up passenger transport to new rail operators by 2010. On a European level, this new regulatory framework comes in line with EU’s concerns both on transport service performance and on infrastructure development. On the one hand, European regulations have focused in measures to guarantee quality of service, equal access and effective competition market rules. On the other, the relevance of the development of HSR projects in the Iberian peninsula is proved with their inclusion among the priority projects of the trans-European networks (TEN).Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

In-silico modeling to compare radiofrequency-induced thermal lesions created on myocardium and thigh muscle

[EN] Beating heart (BH) and thigh muscle (TM) are two pre-clinical models aimed at studying the lesion sizes created by radiofrequency (RF) catheters in cardiac ablation. Previous experimental results have shown that thermal lesions created in the TM are slightly bigger than in the BH. Our objective was to use in-silico modeling to elucidate some of the causes of this difference. In-silico RF ablation models were created using the Arrhenius function to estimate lesion size under different energy settings (25 W/20 s, 50 W/6 s and 90 W/4 s) and parallel, 45 degrees and perpendicular catheter positions. The models consisted of homogeneous tissue: myocardium in the BH model and striated muscle in the TM model. The computer results showed that the lesion sizes were generally bigger in the TM model and the differences depended on the energy setting, with hardly any differences at 90 W/4 s but with differences of 1 mm in depth and 1.5 m in width at 25 W/20 s. The higher electrical conductivity of striated muscle (0.446 S/m) than that of the myocardium (0.281 S/m) is possibly one of the causes of the higher percentage of RF energy delivered to the tissue in the TM model, with differences between models of 2-5% at 90 W/4 s, similar to 9% at 50 W/6 s and similar to 10% at 25 W/20 s. Proximity to the air-blood interface (just 2 cm from the tissue surface) artificially created in the TM model to emulate the cardiac cavity had little effect on lesion size. In conclusion, the TM-based experimental model creates fairly similar-sized lesions to the BH model, especially in high-power short-duration ablations (50 W/6 s and 90 W/4 s). Our computer results suggest that the higher electrical conductivity of striated muscle could be one of the causes of the slightly larger lesions in the TM model.This research was funded by the Spanish Ministerio de Ciencia, Innovacion y Universidades/Agencia Estatal de Investigacion MCIN/AEI/10.13039/501100011033 (Grant number: RTI2018-094357-B-C21)Pérez, JJ.; Berjano, E.; González-Suárez, A. (2022). In-silico modeling to compare radiofrequency-induced thermal lesions created on myocardium and thigh muscle. Bioengineering. 9(7):1-13. https://doi.org/10.3390/bioengineering9070329S1139

How far the zone of heat-induced transient block extends beyond the lesion during RF catheter cardiac ablation

This is an Accepted Manuscript of an article published by Taylor & Francis in International Journal of Hyperthermia on 02-01-2023, available online: http://www.tandfonline.com/ https://doi.org/10.1080/02656736.2022.2163310[EN] Purpose While radiofrequency catheter ablation (RFCA) creates a lesion consisting of the tissue points subjected to lethal heating, the sublethal heating (SH) undergone by the surrounding tissue can cause transient electrophysiological block. The size of the zone of heat-induced transient block (HiTB) has not been quantified to date. Our objective was to use computer modeling to provide an initial estimate. Methods and materials We used previous experimental data together with the Arrhenius damage index (omega) to fix the omega values that delineate this zone: a lower limit of 0.1-0.4 and upper limit of 1.0 (lesion boundary). An RFCA computer model was used with different power-duration settings, catheter positions and electrode insertion depths, together with dispersion of the tissue's electrical and thermal characteristics. Results The HiTB zone extends in depth to a minimum and maximum distance of 0.5 mm and 2 mm beyond the lesion limit, respectively, while its maximum width varies with the energy delivered, extending to a minimum of 0.6 mm and a maximum of 2.5 mm beyond the lesion, reaching 3.5 mm when high energy settings are used (25 W-20s, 500 J). The dispersion of the tissue's thermal and electrical characteristics affects the size of the HiTB zone by +/- 0.3 mm in depth and +/- 0.5 mm in maximum width. Conclusions Our results suggest that the size of the zone of heat-induced transient block during RFCA could extend beyond the lesion limit by a maximum of 2 mm in depth and approximately 2.5 mm in width.This work was supported by Spanish Ministerio de Ciencia, Innovacion y Universidades/Agencia Estatal de Investigacion IMCIN/AEI/10.13039/ 501100011033 (Grant RTI2018-094357-B-C21).Pérez, JJ.; Berjano, E.; González Suárez, A. (2023). How far the zone of heat-induced transient block extends beyond the lesion during RF catheter cardiac ablation. International Journal of Hyperthermia. 40(1):1-10. https://doi.org/10.1080/02656736.2022.216331011040

A comprehensive asteroseismic modelling of the high-amplitude delta Scuti star RV Arietis

We present a comprehensive asteroseismic study of the double-mode high-amplitude delta Scuti star HD 187642 (RV Arietis). The modelling includes some of the most recent techniques: 1) effects of rotation on both equilibrium models and adiabatic oscillation spectrum, 2) non-adiabatic study of radial and non-radial modes, 3) relationship between the fundamental radial mode and the first overtone in the framework of Petersen diagrams. The analysis reveals that two of the observed frequencies are very probably identified as the fundamental and first overtone radial modes. Analysis of the colour index variations, together with theoretical non-adiabatic calculations, points to models in the range of [7065,7245] K in effective temperature and of [1190, 1270] Myr in stellar age. These values were found to be compatible with those obtained using the three other asteroseismic techniques.Comment: accepted for publication in A&

Thermal impact of replacing constant voltage by low-frequency sine wave voltage in RF ablation computer modeling

[EN] Background and objectives: A constant voltage (DC voltage) is usually used in radiofrequency ablation (RFA) computer models to mimic the radiofrequency voltage. However, in some cases a low frequency sine wave voltage (AC voltage) may be used instead. Our objective was to assess the thermal impact of replacing DC voltage by low-frequency AC voltage in RFA computer modeling. Methods: A 2D model was used consisting of an ablation electrode placed perpendicular to the tissue fragment. The Finite Element method was used to solve a coupled electric-thermal problem. Quasi-static electrical approximation was implemented in two ways (both with equivalent electrical power): (1) by a constant voltage of 25 V in the ablation electrode (DC voltage), and (2) applying a sine waveform with peak amplitude of 25 root 2 V (AC voltage). The frequency of the sine signal (f(AC)) varied from 0.5 Hz to 50 Hz. Results: Sine wave thermal oscillations (at twice the f(AC) frequency) were observed in the case of AC voltage, in addition to the temperature obtained by DC voltage. The amplitude of the oscillations: (1) increased with temperature, remaining more or less constant after 30 s; (2) was of up to +/- 3 degrees C for very low f(AC) values (0.5 Hz); and (3) was reduced at higher f(AC) values and with distance from the electrode (almost negligible for distances > 5 mm). The evolution of maximum lesion depth and width were almost identical with both DC and AC. Conclusions: Although reducing f(AC) reduces the computation time, thermal oscillations appear at points near the electrode, which suggests that a minimum value of f(AC) should be used. Replacing DC voltage by low-frequency AC voltage does not appear to have an impact on the lesion depth. (C) 2020 Elsevier B.V. All rights reserved.This work was supported by the Spanish Ministerio de Ciencia, Innovacion y Universidades under "Programa Estatal de I+D+i Orientada a los Retos de la Sociedad", Grant no. "RTI2018-094357-B-C21".Pérez, JJ.; González Suárez, A.; Nadal, E.; Berjano, E. (2020). Thermal impact of replacing constant voltage by low-frequency sine wave voltage in RF ablation computer modeling. Computer Methods and Programs in Biomedicine. 195:1-7. https://doi.org/10.1016/j.cmpb.2020.105673S17195Doss, J. D. (1982). Calculation of electric fields in conductive media. Medical Physics, 9(4), 566-573. doi:10.1118/1.595107Tungjitkusolmun, S., Haemmerich, D., Hong Cao, Jang-Zern Tsai, Young Bin Choy, Vorperian, V. R., & Webster, J. G. (2002). Modeling bipolar phase-shifted multielectrode catheter ablation. IEEE Transactions on Biomedical Engineering, 49(1), 10-17. doi:10.1109/10.972835Yan, S., Wu, X., & Wang, W. (2016). A simulation study to compare the phase-shift angle radiofrequency ablation mode with bipolar and unipolar modes in creating linear lesions for atrial fibrillation ablation. International Journal of Hyperthermia, 32(3), 231-238. doi:10.3109/02656736.2016.1145746Pérez, J. J., González-Suárez, A., & Berjano, E. (2017). Numerical analysis of thermal impact of intramyocardial capillary blood flow during radiofrequency cardiac ablation. International Journal of Hyperthermia, 34(3), 243-249. doi:10.1080/02656736.2017.1336258Keangin, P., Wessapan, T., & Rattanadecho, P. (2011). Analysis of heat transfer in deformed liver cancer modeling treated using a microwave coaxial antenna. Applied Thermal Engineering, 31(16), 3243-3254. doi:10.1016/j.applthermaleng.2011.06.005Nakayama, A., & Kuwahara, F. (2008). A general bioheat transfer model based on the theory of porous media. International Journal of Heat and Mass Transfer, 51(11-12), 3190-3199. doi:10.1016/j.ijheatmasstransfer.2007.05.030Bhowmik, A., Singh, R., Repaka, R., & Mishra, S. C. (2013). Conventional and newly developed bioheat transport models in vascularized tissues: A review. Journal of Thermal Biology, 38(3), 107-125. doi:10.1016/j.jtherbio.2012.12.003Andreozzi, A., Brunese, L., Iasiello, M., Tucci, C., & Vanoli, G. P. (2018). Modeling Heat Transfer in Tumors: A Review of Thermal Therapies. Annals of Biomedical Engineering, 47(3), 676-693. doi:10.1007/s10439-018-02177-xIasiello M., Andreozzi A., Bianco N., Vafai K. The porous media theory applied to radiofrequency catheter ablation. Int. J. Numer. Methods Heat Fluid Flow, Vol. 30 No. 5, pp. 2669–2681. 10.1108/HFF-11-2018-0707.González‐Suárez, A., Herranz, D., Berjano, E., Rubio‐Guivernau, J. L., & Margallo‐Balbás, E. (2017). Relation between denaturation time measured by optical coherence reflectometry and thermal lesion depth during radiofrequency cardiac ablation: Feasibility numerical study. Lasers in Surgery and Medicine, 50(3), 222-229. doi:10.1002/lsm.22771Irastorza, R. M., Gonzalez-Suarez, A., Pérez, J. J., & Berjano, E. (2020). Differences in applied electrical power between full thorax models and limited-domain models for RF cardiac ablation. International Journal of Hyperthermia, 37(1), 677-687. doi:10.1080/02656736.2020.1777330Seiler, J., Roberts-Thomson, K. C., Raymond, J.-M., Vest, J., Delacretaz, E., & Stevenson, W. G. (2008). Steam pops during irrigated radiofrequency ablation: Feasibility of impedance monitoring for prevention. Heart Rhythm, 5(10), 1411-1416. doi:10.1016/j.hrthm.2008.07.011González-Suárez, A., Berjano, E., Guerra, J. M., & Gerardo-Giorda, L. (2016). Computational Modeling of Open-Irrigated Electrodes for Radiofrequency Cardiac Ablation Including Blood Motion-Saline Flow Interaction. PLOS ONE, 11(3), e0150356. doi:10.1371/journal.pone.0150356Bourier, F., Duchateau, J., Vlachos, K., Lam, A., Martin, C. A., Takigawa, M., … Jais, P. (2018). High‐power short‐duration versus standard radiofrequency ablation: Insights on lesion metrics. Journal of Cardiovascular Electrophysiology, 29(11), 1570-1575. doi:10.1111/jce.13724Labonte, S. (1994). Numerical model for radio-frequency ablation of the endocardium and its experimental validation. IEEE Transactions on Biomedical Engineering, 41(2), 108-115. doi:10.1109/10.284921Babuska, I., & Oden, J. T. (2004). Verification and validation in computational engineering and science: basic concepts. Computer Methods in Applied Mechanics and Engineering, 193(36-38), 4057-4066. doi:10.1016/j.cma.2004.03.00

Paralelización de un algoritmo de cálculo de la rspuesta impulsional de un canal IR difuso en interiores

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