Simulating underwater molecular propagation signal

Molecular Communication (MC) is a relatively new interdisciplinary research paradigm that is related to the field of: communications, nanotechnology, biotechnology, fluid dynamics, and chemical engineering. In MC, molecules are utilized to convey information which can be observed in nature (e.g., quorum sensing between bacteria at the micro-scales and pheromone-based communication at the macro-scales in both air and water environments).A new approach for Molecular Communication via Diffusion (MCvD), voxel-based simulations, is proposed and analyzed. Optimum voxel length relation with environment parameters is studied.Un nuevo método para la Comunicación Molecular via Difusión (MCvD), simulaciones basada en voxel, es propuesta y analizada. La longitud óptima para los voxel y su relación con los parámetros del entorno es estudiada.A new approach for Molecular Communication via Diffusion (MCvD), voxel-based simulations, is proposed and analyzed. Optimum voxel length relation with environment parameters is studied

Beyond the Light-Cone Propagation of Relativistic Wavefunctions: Numerical Results

It is known that relativistic wavefunctions formally propagate beyond the light cone when the propagator is limited to the positive energy sector. By construction, this is the case for solutions of the Salpeter (or relativistic Schrödinger) equation or for Klein–Gordon and Dirac wavefunctions defined in the Foldy–Wouthuysen representation. In this work, we quantitatively investigate the degree of non-causality for free propagation for different types of wavepackets that all initially have a compact spatial support. In the studied examples, we find that non-causality appears as a small transient effect that can in most cases be neglected. We display several numerical results and discuss the fundamental and practical consequences of our findings concerning this peculiar dynamical feature

Speed-up and slow-down of a quantum particle

[EN] We study non-relativistic propagation of Gaussian wave packets in one-dimensional Eckart potential, a barrier, or a well. In the picture used, the transmitted wave packet results from interference between the copies of the freely propagating state with different spatial shifts (delays), x′, induced by the scattering potential. The Uncertainty Principle precludes relating the particle’s final position to the delay experienced in the potential, except in the classical limit. Beyond this limit, even defining an effective range of the delay is shown to be an impracticable task, owing to the oscillatory nature of the corresponding amplitude distribution. Our examples include the classically allowed case, semiclassical tunnelling, delays induced in the presence of a virtual state, and scattering by a low barrier. The properties of the amplitude distribution of the delays, and its pole representation are studied in detail.Financial support through the grants PGC2018-101355-B-100 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”, PID2019-107609GB-I00 by MCIN, and the Basque Government Grant No IT986-16, is acknowledged by MP and DS

Klein paradox for bosons, wave packets and negative tunnelling times

We analyse a little known aspect of the Klein paradox. A Klein-Gordon boson appears to be able to cross a supercritical rectangular barrier without being reflected, while spending there a negative amount of time. The transmission mechanism is demonstrably acausal, yet an attempt to construct the corresponding causal solution of the Klein-Gordon equation fails. We relate the causal solution to a divergent multiple-reflections series, and show that the problem is remedied for a smooth barrier, where pair production at the energy equal to a half of the barrier's height is enhanced yet remains finite.Financial support of MCIU, through the Grant PGC2018-101355-B-100(MCIU/AEI/FEDER,UE) (XGdC, MP, DS), of Spanish MINECO, project FIS2016-80681-P (MP), and of the Basque Government Grant no. IT986-16 (MP, DS) is gratefully acknowledged

Delays in relativistic and non-relativistic scattering studied by means of quantum measurement theory

190 p.Al medir el tiempo que toma un paquete de ondas en cruzar una región potencial a través del efecto túnel el resultado es aparentemente superluminal. La razón de esta medida paradójica se debe a que el paquete se remodela en la barrera, de forma que no ha sido transmitido a través de una única trayectoria.Existen definiciones alternativas del tiempo de recorrido, como la demora espacial de Eisenbud-Wigner-Smith o el reloj de Larmor. Éstas son realmente instrucciones de cómo medir y, en el caso cuántico,obtienen resultados contradictorios. El uso de dispersión relativista no solo no resuelve estas contradicciones, si no que aparecen otros resultados extraños, como un tiempo de recorrido negativo

Simulating underwater molecular propagation signal

Molecular Communication (MC) is a relatively new interdisciplinary research paradigm that is related to the field of: communications, nanotechnology, biotechnology, fluid dynamics, and chemical engineering. In MC, molecules are utilized to convey information which can be observed in nature (e.g., quorum sensing between bacteria at the micro-scales and pheromone-based communication at the macro-scales in both air and water environments).A new approach for Molecular Communication via Diffusion (MCvD), voxel-based simulations, is proposed and analyzed. Optimum voxel length relation with environment parameters is studied.Un nuevo método para la Comunicación Molecular via Difusión (MCvD), simulaciones basada en voxel, es propuesta y analizada. La longitud óptima para los voxel y su relación con los parámetros del entorno es estudiada.A new approach for Molecular Communication via Diffusion (MCvD), voxel-based simulations, is proposed and analyzed. Optimum voxel length relation with environment parameters is studied

Simulating underwater molecular propagation signal

Molecular Communication (MC) is a relatively new interdisciplinary research paradigm that is related to the field of: communications, nanotechnology, biotechnology, fluid dynamics, and chemical engineering. In MC, molecules are utilized to convey information which can be observed in nature (e.g., quorum sensing between bacteria at the micro-scales and pheromone-based communication at the macro-scales in both air and water environments).A new approach for Molecular Communication via Diffusion (MCvD), voxel-based simulations, is proposed and analyzed. Optimum voxel length relation with environment parameters is studied.Un nuevo método para la Comunicación Molecular via Difusión (MCvD), simulaciones basada en voxel, es propuesta y analizada. La longitud óptima para los voxel y su relación con los parámetros del entorno es estudiada.A new approach for Molecular Communication via Diffusion (MCvD), voxel-based simulations, is proposed and analyzed. Optimum voxel length relation with environment parameters is studied

Cardiomyocyte calcium dynamics

Contraction of the cardiac muscles starts with an action potential acting as a signal, which depolarizes myocytes, making them to contract. Ca 2+ is key in both processes, signaling and contraction; in this work we are going to focus in the role its concentration plays in contraction of cardiomyocytes, and therefore beating of the heart. A cardiac cell can be modelled as an array of Calcium Release Units (CaRUs), each of which present five different compartments and calcium concentration; the response of this concentrations to the external action potential determines the cardiac contraction.2016/201

Quantum Measurements and Delays in Scattering by Zero-Range Potentials

Eisenbud–Wigner–Smith delay and the Larmor time give different estimates for the duration of a quantum scattering event. The difference is most pronounced in the case where the de Broglie wavelength is large compared to the size of the scatterer. We use the methods of quantum measurement theory to analyse both approaches and to decide which one of them, if any, describes the duration a particle spends in the region that contains the scattering potential. The cases of transmission, reflection, and three-dimensional elastic scattering are discussed in some detail.We are grateful for grant PID2021-126273NB-I00, funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”. We acknowledge financial support from the Basque Government, grant No. IT1470-22. MP acknowledges support from the Spanish Agencia Estatal de Investigación, grant No. PID2022-141283NB-100

Cardiomyocyte calcium dynamics

Contraction of the cardiac muscles starts with an action potential acting as a signal, which depolarizes myocytes, making them to contract. Ca 2+ is key in both processes, signaling and contraction; in this work we are going to focus in the role its concentration plays in contraction of cardiomyocytes, and therefore beating of the heart. A cardiac cell can be modelled as an array of Calcium Release Units (CaRUs), each of which present five different compartments and calcium concentration; the response of this concentrations to the external action potential determines the cardiac contraction.2016/201