BIOCOMSC  Grup de Biologia Computacional i Sistemes Complexoshttp://hdl.handle.net/2117/7967220191118T01:00:24Z20191118T01:00:24ZNonlinearities due to refractoriness in SR Ca releasePeñaranda Ayllón, AngelinaÁlvarez Lacalle, EnriqueRodríguez Cantalapiedra, InmaEchebarría Domínguez, Blashttp://hdl.handle.net/2117/16941320191009T05:31:52Z20191008T15:14:15ZNonlinearities due to refractoriness in SR Ca release
Peñaranda Ayllón, Angelina; Álvarez Lacalle, Enrique; Rodríguez Cantalapiedra, Inma; Echebarría Domínguez, Blas
Calcium alternans is a proarrhytmic cardiac dysfunction related to beattobeat changes in the amplitude of intracellular calcium transient, that typically occurs at rapid pacing rates. Although oscillations in sarcoplasmic reticulum (SR) content have been related with calcium alternans, the experimental appearance of alternans without these oscillations suggests that another mechanism related with refractoriness of SR calcium release might be key, at least, under certain conditions. We investigate how RyR2 refractoriness modulates calcium handling on a beattobeat basis using a numerical rabbit cardiomyocyte model. We find that a slow recovery from inactivation of the RyR2 might be crucial. On one hand, a steep relation between sarcoplasmic reticulum (SR) load and calcium release makes regular calcium cycling unstable at high SR calcium load and/or fast pacing rates, in agreement with previous explanation when RyR2 inactivation is not important. On the other hand, we show that calcium release can also depend strongly on the number of RyR2 ready to open if an important number of RyR2s inactivate after the release. This gives rise to a steep nonlinear relation between the calcium release and the level of recovered RyR2, so that a small change in the later produces big changes in calcium release. A conclusion of this result is that RyR2 refractoriness can be the main nonlinearity behind alternans even when alternation in SRCa load is present.
20191008T15:14:15ZPeñaranda Ayllón, AngelinaÁlvarez Lacalle, EnriqueRodríguez Cantalapiedra, InmaEchebarría Domínguez, BlasCalcium alternans is a proarrhytmic cardiac dysfunction related to beattobeat changes in the amplitude of intracellular calcium transient, that typically occurs at rapid pacing rates. Although oscillations in sarcoplasmic reticulum (SR) content have been related with calcium alternans, the experimental appearance of alternans without these oscillations suggests that another mechanism related with refractoriness of SR calcium release might be key, at least, under certain conditions. We investigate how RyR2 refractoriness modulates calcium handling on a beattobeat basis using a numerical rabbit cardiomyocyte model. We find that a slow recovery from inactivation of the RyR2 might be crucial. On one hand, a steep relation between sarcoplasmic reticulum (SR) load and calcium release makes regular calcium cycling unstable at high SR calcium load and/or fast pacing rates, in agreement with previous explanation when RyR2 inactivation is not important. On the other hand, we show that calcium release can also depend strongly on the number of RyR2 ready to open if an important number of RyR2s inactivate after the release. This gives rise to a steep nonlinear relation between the calcium release and the level of recovered RyR2, so that a small change in the later produces big changes in calcium release. A conclusion of this result is that RyR2 refractoriness can be the main nonlinearity behind alternans even when alternation in SRCa load is present.Mecanismes que expliquen el manteniment de la TB en l'espècie humanaCardona Iglesias, Pere JoanPrats Soler, Clarahttp://hdl.handle.net/2117/16781520190830T05:37:17Z20190829T12:57:23ZMecanismes que expliquen el manteniment de la TB en l'espècie humana
Cardona Iglesias, Pere Joan; Prats Soler, Clara
20190829T12:57:23ZCardona Iglesias, Pere JoanPrats Soler, ClaraUnstable state decay in nonMarkovian heat baths and weak signals detectionJiménez Aquino, José InésSánchez Salas, NormaRamírez de la Piscina Millán, LaureanoRomero Bastida, M.http://hdl.handle.net/2117/13488320190626T05:54:07Z20190620T11:56:34ZUnstable state decay in nonMarkovian heat baths and weak signals detection
Jiménez Aquino, José Inés; Sánchez Salas, Norma; Ramírez de la Piscina Millán, Laureano; Romero Bastida, M.
The statistics of the first passage and nonlinear relaxation times are used to characterize the decay process of an unstable state for an electrically charged Brownian particle embedded in nonMarkovian heat baths under the action of an external electric field. The relaxation process is described, in the overdamped regime, by a Generalized Langevin Equation (GLE) characterized by an arbitrary friction memory kernel, and a bistable potential profile. By applying the quasideterministic approach, the statistics of the mean first passage time is calculated through the exact analytical solution of the GLE with arbitrary memory kernel in the linear regime of the bistable potential. To characterize the relaxation process including the nonlinear contributions of the bistable potential, we use the specific Ornstein–Uhlenbeck friction memory kernel to exactly calculate the nonlinear statistics of the mean first passage time as well as the nonlinear relaxation time. Both characteristic times are applied for possible detection of weak signals in the unstable state decay process.
20190620T11:56:34ZJiménez Aquino, José InésSánchez Salas, NormaRamírez de la Piscina Millán, LaureanoRomero Bastida, M.The statistics of the first passage and nonlinear relaxation times are used to characterize the decay process of an unstable state for an electrically charged Brownian particle embedded in nonMarkovian heat baths under the action of an external electric field. The relaxation process is described, in the overdamped regime, by a Generalized Langevin Equation (GLE) characterized by an arbitrary friction memory kernel, and a bistable potential profile. By applying the quasideterministic approach, the statistics of the mean first passage time is calculated through the exact analytical solution of the GLE with arbitrary memory kernel in the linear regime of the bistable potential. To characterize the relaxation process including the nonlinear contributions of the bistable potential, we use the specific Ornstein–Uhlenbeck friction memory kernel to exactly calculate the nonlinear statistics of the mean first passage time as well as the nonlinear relaxation time. Both characteristic times are applied for possible detection of weak signals in the unstable state decay process.Identification of yeast isolated from laboratory sourdoughs prepared with grape, apple, and yogurtGordún Quiles, ElenaPuig Pujol, AnnaPiñol, LolaCarbó Moliner, Rosahttp://hdl.handle.net/2117/13262620190504T03:28:05Z20190503T18:53:04ZIdentification of yeast isolated from laboratory sourdoughs prepared with grape, apple, and yogurt
Gordún Quiles, Elena; Puig Pujol, Anna; Piñol, Lola; Carbó Moliner, Rosa
Sourdough; Apple; Grap;, Yogurt; Molecular identification; Yeast
20190503T18:53:04ZGordún Quiles, ElenaPuig Pujol, AnnaPiñol, LolaCarbó Moliner, RosaSourdough; Apple; Grap;, Yogurt; Molecular identification; YeastEffects of gravity level on bubble detachment, rise, and bouncing with a free surfaceSuñol Galofre, Francesc XavierGonzález Cinca, Ricardohttp://hdl.handle.net/2117/13261820190504T03:28:01Z20190503T12:28:50ZEffects of gravity level on bubble detachment, rise, and bouncing with a free surface
Suñol Galofre, Francesc Xavier; González Cinca, Ricardo
Bubble detachment, rise, and bouncing upon impact with a free surface is studied experimentally in variable gravity
conditions. Previous investigations focused on the effects of fluid properties such as viscosity or surface tension on the
rise and bouncing dynamics. Gravity force is a crucial factor in the detachment, rise and bouncing processes. However,
the effect of different gravity levels has never been studied experimentally. In this paper we analyze the role of gravity
in the detachment, rise velocity and bouncing motion of millimetric bubbles colliding with a free surface. Single air
bubbles in ethanol are detached from a nozzle by the buoyancy force. After reaching a terminal velocity, the rising
bubble interacts with the free surface in a bouncing process prior to coalescence. The equivalent bubble diameter at
detachment decreases as the gravity level increases, in agreement with the theoretical prediction. An expression for
the terminal velocity as a function of gravity is proposed. The terminal velocity is found to increase with the gravity
level, although bubbles are smaller at higher values of gravity. The bouncing process has been modelled by a damped
oscillator, in which the free surface acts as an elastic membrane. An expression for the frequency of bouncing as a
function of gravity has been obtained, showing a good agreement with the experimental results. The motion of the
bubble during the bouncing process can be approximated by an underdamped oscillator even if viscosity is negligible.
Therefore, viscosity is not the main responsible for damping, which is probably due to energy transfer from the bubble
to the fluid in the form of vortex and surface waves generation.
20190503T12:28:50ZSuñol Galofre, Francesc XavierGonzález Cinca, RicardoBubble detachment, rise, and bouncing upon impact with a free surface is studied experimentally in variable gravity
conditions. Previous investigations focused on the effects of fluid properties such as viscosity or surface tension on the
rise and bouncing dynamics. Gravity force is a crucial factor in the detachment, rise and bouncing processes. However,
the effect of different gravity levels has never been studied experimentally. In this paper we analyze the role of gravity
in the detachment, rise velocity and bouncing motion of millimetric bubbles colliding with a free surface. Single air
bubbles in ethanol are detached from a nozzle by the buoyancy force. After reaching a terminal velocity, the rising
bubble interacts with the free surface in a bouncing process prior to coalescence. The equivalent bubble diameter at
detachment decreases as the gravity level increases, in agreement with the theoretical prediction. An expression for
the terminal velocity as a function of gravity is proposed. The terminal velocity is found to increase with the gravity
level, although bubbles are smaller at higher values of gravity. The bouncing process has been modelled by a damped
oscillator, in which the free surface acts as an elastic membrane. An expression for the frequency of bouncing as a
function of gravity has been obtained, showing a good agreement with the experimental results. The motion of the
bubble during the bouncing process can be approximated by an underdamped oscillator even if viscosity is negligible.
Therefore, viscosity is not the main responsible for damping, which is probably due to energy transfer from the bubble
to the fluid in the form of vortex and surface waves generation.ESA/ELGRA GravityRelated Research Summer SchoolGonzález Cinca, RicardoCallens, NatachaCarvil, Philhttp://hdl.handle.net/2117/13261620190504T03:29:16Z20190503T12:19:07ZESA/ELGRA GravityRelated Research Summer School
González Cinca, Ricardo; Callens, Natacha; Carvil, Phil
The European Low Gravity Research Association
(ELGRA) and the European Space Agency (ESA) Education
Office co
organi
se at the ESA Academy’s Training and Learning
Centre in ESA
ESEC,
Belgium,
a Summer S
chool on gravity

related research since 2016. This Summer School explains the
fundamentals of performing research at different gravity levels
and
offers an overview of current research activity
under
microgravity and hypergravity conditi
ons in life and physical
sciences. Over four and a half
intensive
days
, 22
Bachelors or
Masters students from ESA member and associate states
attend
stimulating lectures
, and work within small groups to devise
project
ideas for prospective experiments. Gra
vity
related
research is introduced to these future scientists and engineers by
experienced professionals from across the
European space
and
research
sector. These
professional trainers are ELGRA and ESA
experts, freely sharing their experience and know
ho
w with the
students, including their day
to
day work and research experience
in biology, human physiology, and physics.
Many different
scientific topics are addressed during
the school
including:
solidification
, fluid
dynamics
, heat
and mass transfer, spaceflight
analogues,
animal models,
cell
biology,
growth of plants, a
rtificial
gravity
for
astronaut countermeasure
s and s
pace
adaptation.
Each year the programme incorporates new elements to enhance
the experience for the students based on their feedback.
20190503T12:19:07ZGonzález Cinca, RicardoCallens, NatachaCarvil, PhilThe European Low Gravity Research Association
(ELGRA) and the European Space Agency (ESA) Education
Office co
organi
se at the ESA Academy’s Training and Learning
Centre in ESA
ESEC,
Belgium,
a Summer S
chool on gravity

related research since 2016. This Summer School explains the
fundamentals of performing research at different gravity levels
and
offers an overview of current research activity
under
microgravity and hypergravity conditi
ons in life and physical
sciences. Over four and a half
intensive
days
, 22
Bachelors or
Masters students from ESA member and associate states
attend
stimulating lectures
, and work within small groups to devise
project
ideas for prospective experiments. Gra
vity
related
research is introduced to these future scientists and engineers by
experienced professionals from across the
European space
and
research
sector. These
professional trainers are ELGRA and ESA
experts, freely sharing their experience and know
ho
w with the
students, including their day
to
day work and research experience
in biology, human physiology, and physics.
Many different
scientific topics are addressed during
the school
including:
solidification
, fluid
dynamics
, heat
and mass transfer, spaceflight
analogues,
animal models,
cell
biology,
growth of plants, a
rtificial
gravity
for
astronaut countermeasure
s and s
pace
adaptation.
Each year the programme incorporates new elements to enhance
the experience for the students based on their feedback.CD5L Drives M2 Polarization of Human Macrophages in Liver CancerSanjurjo, LucíaAran, G.Téllez, ÉricaSilvaMartins, B.López Codina, DanielPrats Soler, ClaraArmengol, C.Sarrias, Maria Rosahttp://hdl.handle.net/2117/13252120190503T03:19:29Z20190502T12:10:26ZCD5L Drives M2 Polarization of Human Macrophages in Liver Cancer
Sanjurjo, Lucía; Aran, G.; Téllez, Érica; SilvaMartins, B.; López Codina, Daniel; Prats Soler, Clara; Armengol, C.; Sarrias, Maria Rosa
20190502T12:10:26ZSanjurjo, LucíaAran, G.Téllez, ÉricaSilvaMartins, B.López Codina, DanielPrats Soler, ClaraArmengol, C.Sarrias, Maria RosaStochastic coupled map model of subcellular calcium cycling in cardiac cellsRomero Castañeda, LuisÁlvarez Lacalle, EnriqueShiferaw, Yohanneshttp://hdl.handle.net/2117/13249620190503T03:19:26Z20190502T09:47:25ZStochastic coupled map model of subcellular calcium cycling in cardiac cells
Romero Castañeda, Luis; Álvarez Lacalle, Enrique; Shiferaw, Yohannes
In this study, we analyze a nonlinear map model of intracellular calcium (Ca) and voltage in cardiac cells. In this model, Ca
release from the sarcoplasmic reticulum (SR) occurs at spatially distributed dyadic junctions that are diffusively coupled. At these
junctions, release occurs with a probability that depends on key variables such as the SR load and the diastolic interval. Using
this model, we explore how nonlinearity and stochasticity determine the spatial distribution of Ca release events within a cardiac
cell. In particular, we identify a novel synchronization transition, which occurs at rapid pacing rates, in which the global Ca
transient transitions from a period 2 response to a period 1 response. In the global period 2 response dyadic junctions fire in
unison, on average, on alternate beats, while in the period 1 regime, Ca release at individual dyads is highly irregular. A close
examination of the spatial distribution of Ca reveals that in the period 1 regime, the system coarsens into spatially outofphase
regions with a length scale much smaller than the system size, but larger than the spacing between dyads.We have also explored
in detail the coupling to membrane voltage. We study first the case of positive coupling, where a large Ca transient promotes a
long action potential duration (APD). Here, the coupling to voltage synchronizes Ca release so that the system exhibits a robust
period 2 response that is independent of initial conditions. On the other hand, in the case of negative coupling, where a large
Ca transient tends to shorten the APD, we find a multitude of metastable states which consist of complex spatially discordant
alternans patterns. Using an analogy to equilibrium statistical mechanics, we show that the spatial patterns observed can be
explained by a mapping to the Potts model, with an additional term that accounts for a global coupling of spin states. Using this
analogy, we argue that Ca cycling in cardiac cells exhibits complex spatiotemporal patterns that emerge via first or second order
phase transitions. These results show that voltage and Ca can interact in order to induce complex subcellular responses, which
can potentially lead to heart rhythm disorders.
20190502T09:47:25ZRomero Castañeda, LuisÁlvarez Lacalle, EnriqueShiferaw, YohannesIn this study, we analyze a nonlinear map model of intracellular calcium (Ca) and voltage in cardiac cells. In this model, Ca
release from the sarcoplasmic reticulum (SR) occurs at spatially distributed dyadic junctions that are diffusively coupled. At these
junctions, release occurs with a probability that depends on key variables such as the SR load and the diastolic interval. Using
this model, we explore how nonlinearity and stochasticity determine the spatial distribution of Ca release events within a cardiac
cell. In particular, we identify a novel synchronization transition, which occurs at rapid pacing rates, in which the global Ca
transient transitions from a period 2 response to a period 1 response. In the global period 2 response dyadic junctions fire in
unison, on average, on alternate beats, while in the period 1 regime, Ca release at individual dyads is highly irregular. A close
examination of the spatial distribution of Ca reveals that in the period 1 regime, the system coarsens into spatially outofphase
regions with a length scale much smaller than the system size, but larger than the spacing between dyads.We have also explored
in detail the coupling to membrane voltage. We study first the case of positive coupling, where a large Ca transient promotes a
long action potential duration (APD). Here, the coupling to voltage synchronizes Ca release so that the system exhibits a robust
period 2 response that is independent of initial conditions. On the other hand, in the case of negative coupling, where a large
Ca transient tends to shorten the APD, we find a multitude of metastable states which consist of complex spatially discordant
alternans patterns. Using an analogy to equilibrium statistical mechanics, we show that the spatial patterns observed can be
explained by a mapping to the Potts model, with an additional term that accounts for a global coupling of spin states. Using this
analogy, we argue that Ca cycling in cardiac cells exhibits complex spatiotemporal patterns that emerge via first or second order
phase transitions. These results show that voltage and Ca can interact in order to induce complex subcellular responses, which
can potentially lead to heart rhythm disorders.A General Equilibrium Model to Study Intracellular Calcium Homeostasis. New Insights on Ventricular FunctionÁlvarez Lacalle, EnriqueConesa, DavidEchebarría Domínguez, BlasShiferaw, YohannesPeñaranda Ayllón, AngelinaRodríguez Cantalapiedra, Inmahttp://hdl.handle.net/2117/13243020190501T03:49:03Z20190430T14:00:46ZA General Equilibrium Model to Study Intracellular Calcium Homeostasis. New Insights on Ventricular Function
Álvarez Lacalle, Enrique; Conesa, David; Echebarría Domínguez, Blas; Shiferaw, Yohannes; Peñaranda Ayllón, Angelina; Rodríguez Cantalapiedra, Inma
20190430T14:00:46ZÁlvarez Lacalle, EnriqueConesa, DavidEchebarría Domínguez, BlasShiferaw, YohannesPeñaranda Ayllón, AngelinaRodríguez Cantalapiedra, InmaStability of oscillating hexagons in rotating convectionEchebarría Domínguez, BlasRiecke, Hermannhttp://hdl.handle.net/2117/13127420190405T03:01:07Z20190404T11:53:12ZStability of oscillating hexagons in rotating convection
Echebarría Domínguez, Blas; Riecke, Hermann
Breaking the chiral symmetry, rotation induces a secondary Hopf bifurcation in weakly nonlinear hexagon patterns which gives rise to oscillating hexagons. We study the stability of the oscillating hexagons using three coupled Ginzburg–Landau equations. Close to the bifurcation point, we derive reduced equations for the amplitude of the oscillation, coupled to the phase of the underlying hexagons. Within these equations, we identify two types of longwave instabilities and study the ensuing dynamics using numerical simulations of the three coupled Ginzburg–Landau equations.
20190404T11:53:12ZEchebarría Domínguez, BlasRiecke, HermannBreaking the chiral symmetry, rotation induces a secondary Hopf bifurcation in weakly nonlinear hexagon patterns which gives rise to oscillating hexagons. We study the stability of the oscillating hexagons using three coupled Ginzburg–Landau equations. Close to the bifurcation point, we derive reduced equations for the amplitude of the oscillation, coupled to the phase of the underlying hexagons. Within these equations, we identify two types of longwave instabilities and study the ensuing dynamics using numerical simulations of the three coupled Ginzburg–Landau equations.