Browsing by Author "Matzavinos, Anastasios"

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    A stochastic parabolic model of MEMS driven by fractional Brownian motion
    (2023) Drosinou, Ourania; Nikolopoulos, Christos V.; Matzavinos, Anastasios; Kavallaris, Nikos I.
    In this paper, we study a stochastic parabolic problem that emerges in the modeling and control of an electrically actuated MEMS (micro-electro-mechanical system) device. The dynamics under consideration are driven by an one dimensional fractional Brownian motion with Hurst index H > 1/2. We derive conditions under which the resulting SPDE has a global in time solution, and we provide analytic estimates for certain statistics of interest, such as quenching times and the corresponding quenching probabilities. Our results demonstrate the non-trivial impact of the fractional noise on the dynamics of the system. Given the significance of MEMS devices in biomedical applications, such as drug delivery and diagnostics, our results provide valuable insights into the reliability of these devices in the presence of positively correlated noise.
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    Modeling cell migratory persistence through temporal correlations and angular noise
    (2025) Montenegro Rojas, Ignacio; Andaur Lobos, Martín; Soler, Karol; Castelli Lacunza, Diego; Bertocchi, Cristina; Matzavinos, Anastasios; Ravasio, Andrea
    The persistence of cell migration is a fundamental property of motile behavior, enabling cells to maintain directionality while adapting to fluctuations and external cues. This feature underlies essential processes such as development, immune responses, and cancer invasion. Classical mathematical models have offered key insights into directed migration, yet they often neglect temporal correlations arising from cellular mechanisms that stabilize polarity and protrusion dynamics, processes not well captured by simple white noise. Here, we introduce an agent-based model based on stochastic differential equations (SDEs) that integrates fractional Brownian motion (fBm) to explicitly incorporate translational autocorrelation in cell trajectories. We simulate migration as a function of angular reorientation (D r ) and the strength of correlated noise (H). In this framework, temporal correlation stabilizes trajectory features inherited from initial conditions, whereas angular reorientation introduces variability that enables transitions between erratic and directed motion. Our simulations show that, unlike models driven by white noise, positive correlation markedly enhances persistence even under strong angular reorientation. Moreover, the combination of D r and H gives rise to emergent behaviors, particularly in the presence of taxis, where persistence and responsiveness are jointly tuned. These results identify correlated noise as a proxy for intrinsic cellular memory and provide a versatile computational framework to interpret the diversity and complexity of migratory behaviors.
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    The mitochondrial Ca2+ uniporter channel synergizes with fluid shear stress to induce mitochondrial Ca2+ oscillations
    (2022) Patel, Akshar; Simkulet, Matthew; Maity, Soumya; Venkatesan, Manigandan; Matzavinos, Anastasios; Madesh, Muniswamy; Alevriadou, B. Rita
    The mitochondrial calcium (Ca2+) uniporter (MCU) channel is responsible for mitochondrial Ca2+ influx. Its expression was found to be upregulated in endothelial cells (ECs) under cardiovascular disease conditions. Since the role of MCU in regulating cytosolic Ca2+ homeostasis in ECs exposed to shear stress (SS) is unknown, we studied mitochondrial Ca2+ dynamics (that is known to decode cytosolic Ca2+ signaling) in sheared ECs. To understand cause-and-effect, we ectopically expressed MCU in ECs. A higher percentage of MCU-transduced ECs exhibited mitochondrial Ca2+ transients/oscillations, and at higher frequency, under SS compared to sheared control ECs. Transients/oscillations correlated with mitochondrial reactive oxygen species (mROS) flashes and mitochondrial membrane potential (Delta Psi(m)) flickers, and depended on activation of the mechanosensitive Piezo1 channel and the endothelial nitric oxide synthase (eNOS). A positive feedback loop composed of mitochondrial Ca2+ uptake/mROS flashes/Delta Psi(m) flickers and endoplasmic reticulum Ca2+ release, in association with Piezo1 and eNOS, provided insights into the mechanism by which SS, under conditions of high MCU activity, may shape vascular EC energetics and function.