Papers by Inma Rodríguez Cantalapiedra
Earthquake Engineering & Structural Dynamics, 2014
Materiales De Construccion, Jul 15, 2010
This study demonstrates the feasibility of using a simple method to measure the resonant fundamen... more This study demonstrates the feasibility of using a simple method to measure the resonant fundamental frequency for determining the MOE (dynamic Young's modulus) of lime and cement mortars. The procedure follows the instructions stated in the UNE-EN ISO 12680-1 standard for refractory products although in this study the instructions are applied to standardized RILEM 4x4x16 cm test samples made of lime and cement mortars. The simplicity of the procedure as well as its correlation to other measured variables, suggest that it can be widely applied in studies about the evolution of the physical characteristics in lime mortars, such as mechanical strength, static Young's modulus, carbonation depth, etc. 1.-Introduction With respect to the mortars used for restoration, it is especially important to know its modulus of elasticity. Usually some of the cement mortars overstiffen the building causing changes in its structural performance.
American Journal of Physiology-heart and Circulatory Physiology, Jun 1, 2014
Despite the important role of electromechanical alternans in cardiac arrhythmogenesis, its molecu... more Despite the important role of electromechanical alternans in cardiac arrhythmogenesis, its molecular origin is not well understood. The appearance of calcium alternans has often been associated to fluctuations in the sarcoplasmic reticulum (SR) Ca loading. However, cytosolic calcium alternans observed without concurrent oscillations in the SR Ca content suggests an alternative mechanism related to a dysfunction in the dynamics of the ryanodine receptor (RyR2). We have investigated the effect of SR release refractoriness in the appearance of alternans, using a mathematical model of a single human atrial cell, based on the model by Nygren et al. (30), where we modified the dynamics of the RyR2 and of SR Ca release. The genesis of calcium alternans was studied stimulating the cell for different periods and values of the RyR2 recovery time from inactivation. At fast rates cytosolic calcium alternans were obtained without concurrent SR Ca content fluctuations. A transition from regular response to alternans was also observed, changing the recovery time from inactivation of the RyR2. This transition was found to be hysteretic, so for a given set of parameters different responses were observed. We then studied the relevance of RyR2 refractoriness for the generation of alternans, reproducing the same protocols as in recent experiments. In particular, restitution of Ca release during alternans was studied with a S1S2 protocol, obtaining a different response if the S2 stimulation was given after a long or a short release. We show that the experimental results can be explained by RyR2 refractoriness, arising from a slow RyR2 recovery from inactivation, stressing the role of the RyR2 in the genesis of alternans. electromechanical alternans; arrhythmias; calcium dynamics; ryanodine receptor; SR calcium release refractoriness THE OCCURRENCE OF CARDIAC arrhythmias has often been associated to irregularities in intracellular calcium dynamics (43). An important example is calcium alternans (6), a beat-to-beat alternation in the intracellular Ca transient of cardiac cells (14, 45) that develops when the cells are paced rapidly or pharmacologically stressed. Alternans has been shown to precede episodes of atrial fibrillation (AF) and to appear at slower pacing times in patients with persistent AF (29). Despite the important role of electromechanical alternans in cardiac arrhythmogenesis, its molecular origin is not well understood. An explanation for the emergence of calcium
Sustainability, May 12, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
El presente trabajo es la continuacion de un proyecto titulado “Estudio termico del edificio de l... more El presente trabajo es la continuacion de un proyecto titulado “Estudio termico del edificio de la EPSEB (UPC) mediante certificacion con Calener y estudio de eficiencia energetica mediante Lider.” Presentado en junio de 2010, que utilizaba estos programas para calificar energeticamente el edificio en ese ano. El objetivo del presente proyecto es realizar una auditoria energetica de la “Escola Politecnica d’Edificacio de Barcelona (EPSEB)”. Con esta auditoria se quiere averiguar el estado energetico de la escuela y comprobar la utilidad de las medidas de reduccion de consumo que se han ido tomando especialmente a partir del ano 2010. Ese ano se realizo una gran intervencion en las fachadas norte, este y oeste donde se cambiaron las ventanas, se instalaron detectores de presencia en los banos para disminuir el consumo electrico y se llevo a cabo una campana de concienciacion en sostenibilidad. Para realizar este analisis del edificio se realizaron ensayos donde se mide la cantidad de flujo que se pierde por las noches a traves de las ventanas de cada fachada y en diferentes plantas. De estos ensayos se obtienen las transmitancias de los vidrios y se puede comprobar que dependiendo de la orientacion de la fachada el flujo varia. Tambien se observa que hay una disminucion de perdida de energia del 35% por una ventana con la persiana bajada y otra con la persiana subida. La segunda parte del proyecto analiza los consumos de la escuela desde el ano 2010, de la instalacion electrica, de gas y de agua. Este analisis se realiza mediante las facturas que el departamento de mantenimiento aporta y mediante el programa SIRENA. Tras este analisis se comprueba que de 2010 a 2012 hay una reduccion del consumo de todas las instalaciones. Electrica en general 12%, iluminacion 43%, gas 30% y agua 20%. Por otro lado se comparan los datos de disminucion que se preveian en el trabajo anterior comprobando hasta que punto la prevision de LIDER ha sido acertada, y se adjunta la calificacion energetica de la escuela antes del cambio de ventanas, tras esta intervencion y por ultimo la calificacion que obtendria si se cambiaran las calderas actuales por unas mas eficientes. Aportaria una reduccion en las emisiones de CO2 notable. Finalmente se aportan varias propuestas de ahorro y mejora que permitirian que la escuela fuera mas eficiente energeticamente.
Computing in Cardiology (CinC), 2012, Sep 14, 2017
Among the different potassium channels present in cardiac myocytes, the small conductance Ca2+ ac... more Among the different potassium channels present in cardiac myocytes, the small conductance Ca2+ activated potassium channels (SK channels) are particular because they are affected by changes in intracellular calcium. The functional role of these channels in cardiac electrophysiology is still under intense debate. While they do not seem to play an important role in healthy heartstheir associated current, I KCa, is smaller than other potassium currents-, there is increasing evidence that they may become relevant under pathological conditions. In fact, both pro-and anti-arrhythmic effects have been assigned to these channels, depending on the clinical situation. In this work, we have incorporated the current through SK channels, I KCa , into an electrophysiological ionic model of human atria myocyte. This allows us to evaluate changes in the action potential under different parameters affecting the kinetics of these channels. We observe a large dependence of the action potential duration with the conductance and gate dynamics of the channel. The dependence of SK channels with changes in intracellular calcium dynamics helps decreasing the proarrhythmic effect of spontaneous calcium release events.
In the absence of a better solution, ventricular fibrillation is treated by applying one or sever... more In the absence of a better solution, ventricular fibrillation is treated by applying one or several large electrical shocks to the patient. The question of how to lower the energy required for a successful shock is still a current issue in both fundamental research and clinical practice. In the study presented here we will compare defibrillation applied through a four electrode device with the standard procedure using two electrodes. The method is tested through intensive numerical simulations. Here we have used a one dimensional geometry. At the level of the cardiac tissue, the bidomain and the modified Beeler-Reuter models were used. Three different shock waveforms are tested: monophasic and two types of biphasic shocks. The results are compared with those obtained with standard two electrode device. A significant reduction in defibrillation thresholds is achieved for all the three tested waveforms when we use a four electrode device.
Ecology and the Environment, Jun 28, 2006
Data from SABLES98 experimental campaign have been used in order to study the influence of stabil... more Data from SABLES98 experimental campaign have been used in order to study the influence of stability (from weak to strong stratification) on the flux-profile relationships for momentum and heat: φ m and φ h. Standard instrumentatio n, 14 thermocouples and 3 sonic anemometers at three levels (5.8, 13.5 and 32 m) were available from 10 to 28 September 1998 and calculations are done in order to extract structure functions and intermittency. The results show increasing values of φ m and φ h with increasing stability parameter and then values remain constant. As a consequence of these constant, but different values of φ m and φ h for strong stability, when linear similarity functions (Businger et al., 1971) are used to calculate surface fluxes of momentum and heat an important underestimation of the turbulent mixing is produced. The differences in structure and higher order moments between stable and neutral turbulence is studied in terms of turbulent intermittent mixing and velocity PDF's.
Biophysical Journal, 2012
Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an arrhythmogenic disease charact... more Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an arrhythmogenic disease characterized by stress-triggered syncope and sudden death. Most of the CPVT mutations are concentrated in RyR ''hotspots'': the C terminus, the central and the N terminal domains. Although the phenotypic manifestations are common, it is likely that the intrinsic mechanism of RyR dysfunction varies with the location of the mutation within the RyR. Previously, we characterized RyR dysfunction in a CPVT mutation located at the C terminal domain, identifying an increased cytosolic Ca 2þ sensitivity as the causative of a gain-of-funcion defect. Recently, we have identified a mutation in a family with CPVT syndrome, which is located in the N terminal portion: RyR2 R420Q. To analyze the function of the mutated RyR channel, we have created an expression plasmids of RyR2 R420Q and RyR2 WT. Heterologous expression in HEK cells showed decreased caffeine sensitivity, suggesting loss-offunction defect. In order to be able to further characterize this mutation in a cardiac context, we expressed both RyR2 R420Q and RyR2 WT in cultured neonatal rat cardiac myocytes and analyzed the amplitude and frequency of spontaneous [Ca 2þ ] i transients and Ca 2þ sparks by confocal microscopy. We found that the spontaneous [Ca 2þ ] i transients were more frequent but of lower amplitude in RyR2 R420Q expressing cells. Further experiments are being conducted to fully understand the underlying mechanism.
This study demonstrates the feasibility of using a simple method to measure the resonant fundamen... more This study demonstrates the feasibility of using a simple method to measure the resonant fundamental frequency for determining the MOE (dynamic Young's modulus) of lime and cement mortars. The procedure follows the instructions stated in the UNE-EN ISO 12680-1 standard for refractory products although in this study the instructions are applied to standardized RILEM 4x4x16 cm test samples made of lime and cement mortars. The simplicity of the procedure as well as its correlation to other measured variables, suggest that it can be widely applied in studies about the evolution of the physical characteristics in lime mortars, such as mechanical strength, static Young's modulus, carbonation depth, etc. 1.-Introduction With respect to the mortars used for restoration, it is especially important to know its modulus of elasticity. Usually some of the cement mortars overstiffen the building causing changes in its structural performance.
Edicions UPC eBooks, 2006
... Disseny de la coberta: Edicions UPC Fotografia de coberta: Anna Manyes Castellà Dibuixos del ... more ... Disseny de la coberta: Edicions UPC Fotografia de coberta: Anna Manyes Castellà Dibuixos del capítol "Marc teòric": Galdric Ruiz Martorell © els autors, 2006 © Edicions UPC, 2006 Edicions de la Universitat Politècnica de Catalunya, SL Jordi Girona Salgado 31, 08034 ...
Physical Review E, Jul 13, 2010
Phase-2 re-entry is thought to underlie many causes of idiopathic ventricular arrhythmias as, for... more Phase-2 re-entry is thought to underlie many causes of idiopathic ventricular arrhythmias as, for instance, those occurring in Brugada syndrome. In this paper, we study under which circumstances a region of depolarized tissue can re-excite adjacent regions that exhibit shorter action potential duration ͑APD͒, eventually inducing reentry. For this purpose, we use a simplified ionic model that reproduces well the ventricular action potential. With the help of this model, we analyze the conditions that lead to very short action potentials ͑APs͒, as well as possible mechanisms for re-excitation in a cable. We then study the induction of re-entrant waves ͑spiral waves͒ in simulations of AP propagation in the heart ventricles. We show that re-excitation takes place via a slow pulse produced by calcium current that propagates into the region of short APs until it encounters excitable tissue. We calculate analytically the speed of the slow pulse, and also give an estimate of the minimal tissue size necessary for allowing reexcitation to take place.
Journal of Theoretical Biology, Aug 1, 2009
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Este trabajo presenta las características reológicas de pastas de cal, especificando la influenci... more Este trabajo presenta las características reológicas de pastas de cal, especificando la influencia de su origen en la obtención de valores de trabajabilidad. El estudio se realiza sobre pastas de cal hidratada, de diferentes edades de maduración y sobre pastas procedentes de cal en polvo.
Lecture notes in civil engineering, 2023
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Papers by Inma Rodríguez Cantalapiedra