Projects

Throughout our scientific career we have developed a strong interest in the applied science, particularly, physics of life. Through this genuine attraction for science we developed an interest in subjects located in the interface of Physics and Biology. The areas of physics that we are most interested in are time series analysis, complex networks and energy converters. In past years, we have worked in the non linear analysis of time series and dynamical systems. Our involvement in projects related to time series analysis and networks helped us to strengthen my interests in the area of non-linear dynamics and to enrich my knowledge with this new form to study complex systems. Our recent work has been focused on the study of scaling properties of heartbeat and excursions time series, electrical signals related earthquake activity and characteristics of complex networks. In the case of complex networks, we have studied the transcriptional regulatory networks of bacteria like the E. coli and S. cerevisiae. We are also interested in exploring the transport properties and organization of complex networks with applications to physical, biological and social systems.

Our research projects are supported partially by Consejo Nacional de Ciencia y Tecnología, México (under grant 49128-F-26020),

Instituto de Ciencia y Tecnología Distrito Federal, México, Comisión de Fomento a las Actividades Académicas (COFAA) and Secretaría de Investigación y Posgrado (SIP-EDI), Instituto Politécnico Nacional.

Projects:

    • Heartbeat dynamics

An important characteristic of heartbeat time series is the nonstationarity related with a large number of control mechanisms of the heart and external stimuli. However, when the interbeat sequences are observed locally, one can roughly define a local mean value. From a physiologic point of view, the presence of local stationary segments can be understood as the capability of the system to preserve an approximated constant value but for a limited period of time (homeostasis principle). Recently, we have focused our attention on the scaling properties of excursions, which are defined as the period of time employed by a walker to return to its average value, to evaluate the capability of the system to preserve a mean output value and to compare differences between wake and sleep periods. Our studies have revealed changes in the scaling properties and in the stability of excursions between diurnal and nocturnal periods under healthy and heart failure conditions. For recent results about correlations of excursions see our published papers:

    • Geoelectric signals and earthquake occurrences

Evaluating complex fluctuations in geoelectric time series is an important task not only for earthquake prediction but also for understanding complex processes related to earthquake preparation. Diverse studies have reported alterations, as the emergence of correlated dynamics in geoelectric potentials prior to an important earthquake (EQ). Our recent work have focused on studying nonlinear properties of electrical signals from the ground in the

south coast of Mexico where seismic activity is very important.

We recently launched the TeleSismuxWeb System, a web-oriented tool for the analysis of geolectric signals.

Currently, we are monitoring self-potential signals from two

stations located along the south mexican pacific coast:

We are planning to extend our number of stations along the

south mexican pacific coast.

    • Organization and transport in complex networks

We are interested in exploring organization and transport properties in complex networks.



    • Non linear analysis of energy converters

            • We are interested in studying the local stability of endoreversible engines operating at different power regimes for common heat transfer laws and for different heat conductances. Typical heat engine models at finite time, reach steady-state conditions for the internal temperatures while operating. In this sense, it is important to discuss the system's dynamic properties, such as response to noisy perturbation and relaxation times to reach the steady state. On the other hand, we also interested in studying data from cycle-by-cycle variations in heat release for a simulated spark-ignited engine. Our analyses are based on non linear scaling properties of heat release fluctuations obtained from a turbulent combustion model. We have applied mono and multifractal methods to characterize the fluctuations for several fuel-air ratio values, from lean mixtures to over stoichiometric situations. Our findings reveal a complex behavior for intermediate fuel-air ratio values.

            • See our recent book Quasi-Dimensional-Simulation-Spark-Ignition-Engines, Springer 2013