Percorrer por autor "Faria, P."
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- Bidirectional flow of action potentials in axons drives activity dynamics in neuronal culturesPublication . Mateus, J. C.; Lopes, C. D. F.; Aroso, M.; Costa, A. R.; Gerós, A.; Meneses, J.; Faria, P.; Neto, E.; Lamghari, M.; Sousa, M. M.; Aguiar, PObjective. Recent technological advances are revealing the complex physiology of the axon and challenging long-standing assumptions. Namely, while most action potential (AP) initiation occurs at the axon initial segment in central nervous system neurons, initiation in distal parts of the axon has been reported to occur in both physiological and pathological conditions. The functional role of these ectopic APs, if exists, is still not clear, nor its impact on network activity dynamics. Approach. Using an electrophysiology platform specifically designed for assessing axonal conduction we show here for the first time regular and effective bidirectional axonal conduction in hippocampal and dorsal root ganglia cultures. We investigate and characterize this bidirectional propagation both in physiological conditions and after distal axotomy. Main results. A significant fraction of APs are not coming from the canonical synapse-dendrite-soma signal flow, but instead from signals originating at the distal axon. Importantly, antidromic APs may carry information and can have a functional impact on the neuron, as they consistently depolarize the soma. Thus, plasticity or gene transduction mechanisms triggered by soma depolarization can also be affected by these antidromic APs. Conduction velocity is asymmetrical, with antidromic conduction being slower than orthodromic. Significance. Altogether these findings have important implications for the study of neuronal function in vitro, reshaping our understanding on how information flows in neuronal cultures.
- Heatsinks to Cool Batteries for Unmanned Aerial VehiclesPublication . Galvão, J.; Faria, P.; Mateus, A.; Pereira, T.; Fernandes, S.This study aims to develop several different models of heatsinks, designed to cool a vertical take-off and landing unmanned aerial vehicle (UAV) battery, through topology optimization, aimed at being manufactured through selective laser melting (SLM) technology. A battery’s temperature must be properly managed for a safe and efficient operation. The methodology developed was with the support of software to carry out several simulations which, starting from several scenarios and restrictions imposed by the small space available to accommodate these small batteries in this type of aircraft. The conception resulted in several battery thermal management systems (BTMS) models, with different applications and efficiency degrees. A relevant aspect is the topology optimization being coupled to computational thermal analysis to reduce the mass of the heatsink whilst ensuring a maximum battery temperature threshold. Together with the use of topology optimization, the SLM process was selected to manufacture the heat sinks, under conditions of geometric freedom, using several high thermal conductivity metal alloys, such as, aluminium and copper to obtain the designed models.
- Optimizing regions for characterization of thermal images in medical applicationsPublication . Duarte, A.; Carrão, L.; Espanha, M.; Viana, T.; Freitas, D.; Bártolo, P.; Faria, P.; Almeida, H.Biomedical techniques and applications are being developed and placed at the service of clinicians. An example is medical thermography which is being used more often in the detection of certain diseases and also in pain distribution. Current thermography processing software has some limitations mainly because it is developed for general applications and doesn't allow the identification of a Region Of Interest (ROI) with a specific anatomic shape. In this research, a computational application was developed in order to aid in the characterization of thermal images. The limitations of existing software applications was overcome by designing an application that allows choosing any ROI, independently of its geometric shape, making the analysis, processing and comparison of different thermal images, easier to be used by the medical community.