Rhenium-Based Electrocatalysts for Water Splitting.

Due to the contamination and global warming problems, it is necessary to search for alternative environmentally friendly energy sources. In this area, hydrogen is a promising alternative. Hydrogen is even more promising, when it is obtained through water electrolysis operated with renewable energy sources. Among the possible devices to perform electrolysis, proton exchange membrane (PEM) electrolyzers appear as the most promising commercial systems for hydrogen production in the coming years. However, their massification is affected by the noble metals used as electrocatalysts in their electrodes, with high commercial value: Pt at the cathode where the hydrogen evolution reaction occurs (HER) and Ru/Ir at the anode where the oxygen evolution reaction (OER) happens. Therefore, to take full advantage of the PEM technology for green H2 production and build up a mature PEM market, it is imperative to search for more abundant, cheaper, and stable catalysts, reaching the highest possible activities at the lowest overpotential with the longest stability under the harsh acidic conditions of a PEM. In the search for new electrocatalysts and considering the predictions of a Trasatti volcano plot, rhenium appears to be a promising candidate for HER in acidic media. At the same time, recent studies provide evidence of its potential as an OER catalyst. However, some of these reports have focused on chemical and photochemical water splitting and have not always considered acidic media. This review summarizes rhenium-based electrocatalysts for water splitting under acidic conditions: i.e., potential candidates as cathode materials. In the various sections, we review the mechanism concepts of electrocatalysis, evaluation methods, and the different rhenium-based materials applied for the HER in acidic media. As rhenium is less common for the OER, we included a section about its use in chemical and photochemical water oxidation and as an electrocatalyst under basic conditions. Finally, concluding remarks and perspectives are given about rhenium for water splitting.

Espacios cardioprotegidos en México: acciones para prevenir la muerte súbita cardiaca. Una postura de profesionales de la salud.

La muerte súbita cardiaca es un problema de salud pública a nivel mundial. Aunque su incidencia no es conocida, se estima que causa hasta 50% de la mortalidad de origen cardíaco y hasta 20% de la mortalidad total en los adultos. En México, estimaciones previas sugieren que causa en promedio 33 000 muertes al año; sin embargo, los datos no son precisos. La  mitad de los eventos por muerte súbita cardiaca se deben a un paro cardiaco súbito extrahospitalario que, de no ser atendido oportunamente, deriva en una muerte súbita cardiaca. Por tanto, la capacidad de responder pronta y adecuadamente a estos eventos con las maniobras y equipos necesarios mejora la sobrevida de las víctimas. Para atender este problema, en algunos estados del país se han creado espacios cardioprotegidos que permiten realizar maniobras de reanimación cardiopulmonar y desfibrilación cardiaca de acceso público oportunamente. Como objetivo, los profesionales de la salud establecen la importancia de implementar espacios cardioprotegidos y crear políticas públicas al respecto en todo el país.

Nonequilibrium thermodynamics of the asymmetric Sherrington-Kirkpatrick model.

Most natural systems operate far from equilibrium, displaying time-asymmetric, irreversible dynamics characterized by a positive entropy production while exchanging energy and matter with the environment. Although stochastic thermodynamics underpins the irreversible dynamics of small systems, the nonequilibrium thermodynamics of larger, more complex systems remains unexplored. Here, we investigate the asymmetric Sherrington-Kirkpatrick model with synchronous and asynchronous updates as a prototypical example of large-scale nonequilibrium processes. Using a path integral method, we calculate a generating functional over trajectories, obtaining exact solutions of the order parameters, path entropy, and steady-state entropy production of infinitely large networks. Entropy production peaks at critical order-disorder phase transitions, but is significantly larger for quasi-deterministic disordered dynamics. Consequently, entropy production can increase under distinct scenarios, requiring multiple thermodynamic quantities to describe the system accurately. These results contribute to developing an exact analytical theory of the nonequilibrium thermodynamics of large-scale physical and biological systems and their phase transitions.

Recurrent, nonequilibrium systems and the Markov blanket assumption.

Markov blankets - statistical independences between system and environment - have become popular to describe the boundaries of living systems under Bayesian views of cognition. The intuition behind Markov blankets originates from considering acyclic, atemporal networks. In contrast, living systems display recurrent, nonequilibrium interactions that generate pervasive couplings between system and environment, making Markov blankets highly unusual and restricted to particular cases.

[Preliminary results of the HEARTS Initiative in Mexico: facilitators and barriers in information systemsResultados preliminares da Iniciativa HEARTS no México: facilitadores e barreiras dos sistemas de informação]. / Resultados preliminares de la Iniciativa HEARTS en México: facilitadores y barreras de los sistemas de información.

Objective: To compare the differences in treatment coverage of patients with systemic arterial hypertension and the proportion of patients with controlled AHT, between December 2020 and December 2021 in health facilities that implemented the HEARTS Initiative, and to explore the facilitators and barriers related to information systems in Mexico. Methods: Descriptive ecological observational study. The results at health facilities that have begun implementing the HEARTS Initiative (n=29) in Chiapas and Sonora were compared, with respect to the variables of treatment coverage and control of AHT, across four periods (semesters) in 2020 and 2021. Results: There were more women than men in treatment and with controlled AHT in the different age groups. Some barriers were identified in information systems (e.g., multiplicity of systems, lack of interoperability, limited internet connectivity in health facilities), as well as facilitators (e.g., free access to information, availability of data from previous years, generation of estimates and projections). Conclusions: Sixteen (55%) of the implementing facilities improved the proportion of patients with controlled AHT in the period covered by the study. It is important to monitor indicators at the process level, and this should be accompanied by a redistribution of functions in health teams. It is also important to ensure a supply of medicines to enhance the effectiveness of the strategy. It is suggested to strengthen implementation with the key drivers for the control of arterial hypertension.

Objetivo: Comparar a diferença de cobertura e proporção de pacientes com hipertensão arterial sistêmica controlada entre dezembro de 2020 e dezembro de 2021 em estabelecimentos de saúde que implementam a Iniciativa HEARTS, e explorar os facilitadores e as barreiras relacionados aos sistemas de informação no México. Métodos: Estudo observacional ecológico descritivo. Os resultados dos estabelecimentos de saúde que iniciaram a implementação da Iniciativa HEARTS (n=29) em Chiapas e Sonora foram comparados em relação às variáveis de cobertura de atenção e controle da hipertensão, em 4 períodos (semestres) de 2020 a 2021. Resultados: Há um maior número de mulheres em tratamento e controladas em relação aos homens nas diferentes faixas etárias. Foram identificadas algumas barreiras (por exemplo, multiplicidade de sistemas, falta de interoperabilidade e conexão limitada à internet nos estabelecimentos de saúde) e facilitadores (por exemplo, livre acesso à informação, disponibilidade de dados de anos anteriores e geração de estimativas e projeções) nos sistemas de informação. Conclusões: Cinquenta e cinco por cento dos estabelecimentos em implementação (16 estabelecimentos) melhoraram a proporção de pacientes controlados no período analisado. É importante monitorar os indicadores no nível de processos ­tal monitoramento deve ser acompanhado por uma redistribuição das funções das equipes de saúde. Deve-se também assegurar o fornecimento de medicamentos para aumentar a eficácia da estratégia. Sugere-se fortalecer a implementação com os principais impulsionadores para o controle da hipertensão.

Resultados preliminares de la Iniciativa HEARTS en México: facilitadores y barreras de los sistemas de información

[RESUMEN]. Objetivo. Comparar la diferencia en la cobertura y proporción de pacientes controlados con hipertensión arterial sistémica entre diciembre de 2020 y diciembre de 2021 en los establecimientos de salud con implementación de la Iniciativa HEARTS, y explorar los facilitadores y las barreras relacionados con los sistemas de información en México. Métodos. Estudio observacional ecológico descriptivo. Se compararon los resultados de los establecimientos de salud que han iniciado la implementación de la Iniciativa HEARTS (n=29) en Chiapas y Sonora, respecto a las variables de cobertura de atención y control de la hipertensión, en 4 periodos (semestres) del 2020 al 2021. Resultados. Existe mayor número de mujeres en tratamiento y en control respecto de los hombres en los diferentes grupos de edad. Se identificaron algunas barreras (p. ej.multiplicidad de sistemas, falta de interoperabilidad, conectividad limitada a internet en los establecimientos de salud) y facilitadores (p. ej.acceso libre a la información, disponibilidad de datos desde años previos, generación de estimaciones y proyecciones) en los sistemas de información. Conclusiones. El 55% de los establecimientos bajo implementación (16 establecimientos) mejoraron la proporción de pacientes controlados en el periodo analizado. Es importante monitorear indicadores a nivel de procesos, lo cual debe ir acompañado de una redistribución de las funciones de los equipos de salud y asegurar el abastecimiento de medicamentos para potenciar la efectividad de la estrategia. Se sugiere fortalecer la implementación con los impulsores clave para el control de la hipertensión.

[ABSTRACT]. Objective. To compare the differences in treatment coverage of patients with systemic arterial hypertension and the proportion of patients with controlled AHT, between December 2020 and December 2021 in health facilities that implemented the HEARTS Initiative, and to explore the facilitators and barriers related to information systems in Mexico. Methods. Descriptive ecological observational study. The results at health facilities that have begun implementing the HEARTS Initiative (n=29) in Chiapas and Sonora were compared, with respect to the variables of treatment coverage and control of AHT, across four periods (semesters) in 2020 and 2021. Results. There were more women than men in treatment and with controlled AHT in the different age groups. Some barriers were identified in information systems (e.g., multiplicity of systems, lack of interoperability, limited internet connectivity in health facilities), as well as facilitators (e.g., free access to information, availability of data from previous years, generation of estimates and projections). Conclusions. Sixteen (55%) of the implementing facilities improved the proportion of patients with controlled AHT in the period covered by the study. It is important to monitor indicators at the process level, and this should be accompanied by a redistribution of functions in health teams. It is also important to ensure a supply of medicines to enhance the effectiveness of the strategy. It is suggested to strengthen implementation with the key drivers for the control of arterial hypertension.

[RESUMO]. Objetivo. Comparar a diferença de cobertura e proporção de pacientes com hipertensão arterial sistêmica controlada entre dezembro de 2020 e dezembro de 2021 em estabelecimentos de saúde que implementam a Iniciativa HEARTS, e explorar os facilitadores e as barreiras relacionados aos sistemas de informação no México. Métodos. Estudo observacional ecológico descritivo. Os resultados dos estabelecimentos de saúde que iniciaram a implementação da Iniciativa HEARTS (n=29) em Chiapas e Sonora foram comparados em relação às variáveis de cobertura de atenção e controle da hipertensão, em 4 períodos (semestres) de 2020 a 2021. Resultados. Há um maior número de mulheres em tratamento e controladas em relação aos homens nas diferentes faixas etárias. Foram identificadas algumas barreiras (por exemplo, multiplicidade de sistemas, falta de interoperabilidade e conexão limitada à internet nos estabelecimentos de saúde) e facilitadores (por exemplo, livre acesso à informação, disponibilidade de dados de anos anteriores e geração de estimativas e projeções) nos sistemas de informação. Conclusões. Cinquenta e cinco por cento dos estabelecimentos em implementação (16 estabelecimentos) melhoraram a proporção de pacientes controlados no período analisado. É importante monitorar os indicadores no nível de processos –tal monitoramento deve ser acompanhado por uma redistribuição das funções das equipes de saúde. Deve-se também assegurar o fornecimento de medicamentos para aumentar a eficácia da estratégia. Sugere-se fortalecer a implementação com os principais impulsionadores para o controle da hipertensão.

A proprietary GMP human platelet lysate for the expansion of dermal fibroblasts for clinical applications.

Recent years have witnessed the introduction of ex vivo expanded dermal fibroblasts for several cell therapy and tissue-engineering applications, including the treatment of facial scars and burns, representing a promising cell type for regenerative medicine. We tested different in-house produced human platelet lysate (HPL) solutions against fetal bovine serum as supplements for in vitro fibroblast expansion by comparing cell yield, molecular marker expression, extracellular matrix (ECM) generation, genomic stability and global gene expression. Our in-house produced HPL supported fibroblast growth at levels similar to those for FBS and commercial HPL products and was superior to AB human serum. Cells grown in HPL maintained a fibroblast phenotype (VIM+, CD44+, CD13+, CD90+), ECM generation capacity (FN+, COL1+) and a normal karyotype, although gene expression profiling revealed changes related to cell metabolism, adhesion and cellular senescence. The HPL manufacturing process was validated within a GMP compliant system and the solution was stable at -80ºC and -20ºC for 2 years. Dermal fibroblasts expanded in vitro with HPL maintain a normal karyotype and expression of fibroblast markers, with only minor changes in their global gene expression profile. Our in-house produced GMP-HPL is an efficient, safe and economical cell culture supplement that can help increase the healthcare activity of blood transfusion centers through the re-use of transfusional plasma and platelets approaching their expiration date. Currently, our HPL solution is approved by the Spanish Agency of Medicines and Medical Devices and is being used in the manufacture of cell therapy products.Abbreviations: AB plasma: plasma group AB; ABHS: AB Human Serum; ABHS+GF: AB Human Serum supplemented with growth factors; ANOVA: Analysis of variance; ATMPs: Advanced Therapies for Medicinal Products; CPE: cytopathic effect; DEGs: Differentially expressed genes; DMEM: Dulbecco's modified Eagle's Medium; ECM: Extracellular matrix; ELISA: enzyme-linked immunosorbent assay; FBS: Fetal bovine serum; FDR: False discovery rate; FGF: Fibroblast growth factor; GMP: Good manufacturing practice; HPL: Human platelet lysate; HPL-CM: commercial human platelet lysate; MSCs: mesenchymal stem cells; NEAA: non-essential amino acids; P/S: penicillin/streptomycin; PBS: phosphate buffered saline; PC: leukodepleted platelet concentrate; PCR: polymerase chain reaction; PDGF: Platelet-derived growth factor; PDGFRA: Platelet-derived growth factor receptor alpha; qPCR: quantitative polymerase chain reaction; RNA: Ribonucleic acid; RT: Room temperature; TAC: Transcriptome analysis console; TGF-ß: Transforming growth factor beta.

How particular is the physics of the free energy principle?

The free energy principle (FEP) states that any dynamical system can be interpreted as performing Bayesian inference upon its surrounding environment. Although, in theory, the FEP applies to a wide variety of systems, there has been almost no direct exploration or demonstration of the principle in concrete systems. In this work, we examine in depth the assumptions required to derive the FEP in the simplest possible set of systems - weakly-coupled non-equilibrium linear stochastic systems. Specifically, we explore (i) how general the requirements imposed on the statistical structure of a system are and (ii) how informative the FEP is about the behaviour of such systems. We discover that two requirements of the FEP - the Markov blanket condition (i.e. a statistical boundary precluding direct coupling between internal and external states) and stringent restrictions on its solenoidal flows (i.e. tendencies driving a system out of equilibrium) - are only valid for a very narrow space of parameters. Suitable systems require an absence of perception-action asymmetries that is highly unusual for living systems interacting with an environment. More importantly, we observe that a mathematically central step in the argument, connecting the behaviour of a system to variational inference, relies on an implicit equivalence between the dynamics of the average states of a system with the average of the dynamics of those states. This equivalence does not hold in general even for linear stochastic systems, since it requires an effective decoupling from the system's history of interactions. These observations are critical for evaluating the generality and applicability of the FEP and indicate the existence of significant problems of the theory in its current form. These issues make the FEP, as it stands, not straightforwardly applicable to the simple linear systems studied here and suggest that more development is needed before the theory could be applied to the kind of complex systems that describe living and cognitive processes.

Resultados preliminares de la Iniciativa HEARTS en México: facilitadores y barreras de los sistemas de información / Preliminary results of the HEARTS Initiative in Mexico: facilitators and barriers in information systems / Resultados preliminares da Iniciativa HEARTS no México: facilitadores e barreiras dos sistemas de informação

RESUMEN Objetivo. Comparar la diferencia en la cobertura y proporción de pacientes controlados con hipertensión arterial sistémica entre diciembre de 2020 y diciembre de 2021 en los establecimientos de salud con implementación de la Iniciativa HEARTS, y explorar los facilitadores y las barreras relacionados con los sistemas de información en México. Métodos. Estudio observacional ecológico descriptivo. Se compararon los resultados de los establecimientos de salud que han iniciado la implementación de la Iniciativa HEARTS (n=29) en Chiapas y Sonora, respecto a las variables de cobertura de atención y control de la hipertensión, en 4 periodos (semestres) del 2020 al 2021. Resultados. Existe mayor número de mujeres en tratamiento y en control respecto de los hombres en los diferentes grupos de edad. Se identificaron algunas barreras (p. ej.multiplicidad de sistemas, falta de interoperabilidad, conectividad limitada a internet en los establecimientos de salud) y facilitadores (p. ej.acceso libre a la información, disponibilidad de datos desde años previos, generación de estimaciones y proyecciones) en los sistemas de información. Conclusiones. El 55% de los establecimientos bajo implementación (16 establecimientos) mejoraron la proporción de pacientes controlados en el periodo analizado. Es importante monitorear indicadores a nivel de procesos, lo cual debe ir acompañado de una redistribución de las funciones de los equipos de salud y asegurar el abastecimiento de medicamentos para potenciar la efectividad de la estrategia. Se sugiere fortalecer la implementación con los impulsores clave para el control de la hipertensión.

ABSTRACT Objective. To compare the differences in treatment coverage of patients with systemic arterial hypertension and the proportion of patients with controlled AHT, between December 2020 and December 2021 in health facilities that implemented the HEARTS Initiative, and to explore the facilitators and barriers related to information systems in Mexico. Methods. Descriptive ecological observational study. The results at health facilities that have begun implementing the HEARTS Initiative (n=29) in Chiapas and Sonora were compared, with respect to the variables of treatment coverage and control of AHT, across four periods (semesters) in 2020 and 2021. Results. There were more women than men in treatment and with controlled AHT in the different age groups. Some barriers were identified in information systems (e.g., multiplicity of systems, lack of interoperability, limited internet connectivity in health facilities), as well as facilitators (e.g., free access to information, availability of data from previous years, generation of estimates and projections). Conclusions. Sixteen (55%) of the implementing facilities improved the proportion of patients with controlled AHT in the period covered by the study. It is important to monitor indicators at the process level, and this should be accompanied by a redistribution of functions in health teams. It is also important to ensure a supply of medicines to enhance the effectiveness of the strategy. It is suggested to strengthen implementation with the key drivers for the control of arterial hypertension.

RESUMO Objetivo. Comparar a diferença de cobertura e proporção de pacientes com hipertensão arterial sistêmica controlada entre dezembro de 2020 e dezembro de 2021 em estabelecimentos de saúde que implementam a Iniciativa HEARTS, e explorar os facilitadores e as barreiras relacionados aos sistemas de informação no México. Métodos. Estudo observacional ecológico descritivo. Os resultados dos estabelecimentos de saúde que iniciaram a implementação da Iniciativa HEARTS (n=29) em Chiapas e Sonora foram comparados em relação às variáveis de cobertura de atenção e controle da hipertensão, em 4 períodos (semestres) de 2020 a 2021. Resultados. Há um maior número de mulheres em tratamento e controladas em relação aos homens nas diferentes faixas etárias. Foram identificadas algumas barreiras (por exemplo, multiplicidade de sistemas, falta de interoperabilidade e conexão limitada à internet nos estabelecimentos de saúde) e facilitadores (por exemplo, livre acesso à informação, disponibilidade de dados de anos anteriores e geração de estimativas e projeções) nos sistemas de informação. Conclusões. Cinquenta e cinco por cento dos estabelecimentos em implementação (16 estabelecimentos) melhoraram a proporção de pacientes controlados no período analisado. É importante monitorar os indicadores no nível de processos -tal monitoramento deve ser acompanhado por uma redistribuição das funções das equipes de saúde. Deve-se também assegurar o fornecimento de medicamentos para aumentar a eficácia da estratégia. Sugere-se fortalecer a implementação com os principais impulsionadores para o controle da hipertensão.

A unifying framework for mean-field theories of asymmetric kinetic Ising systems.

Kinetic Ising models are powerful tools for studying the non-equilibrium dynamics of complex systems. As their behavior is not tractable for large networks, many mean-field methods have been proposed for their analysis, each based on unique assumptions about the system's temporal evolution. This disparity of approaches makes it challenging to systematically advance mean-field methods beyond previous contributions. Here, we propose a unifying framework for mean-field theories of asymmetric kinetic Ising systems from an information geometry perspective. The framework is built on Plefka expansions of a system around a simplified model obtained by an orthogonal projection to a sub-manifold of tractable probability distributions. This view not only unifies previous methods but also allows us to develop novel methods that, in contrast with traditional approaches, preserve the system's correlations. We show that these new methods can outperform previous ones in predicting and assessing network properties near maximally fluctuating regimes.

Critical integration in neural and cognitive systems: Beyond power-law scaling as the hallmark of soft assembly.

Inspired by models of self-organized criticality, a family of measures quantifies long-range correlations in neural and behavioral activity in the form of self-similar (e.g., power-law scaled) patterns across a range of scales. Long-range correlations are often taken as evidence that a system is near a critical transition, suggesting interaction-dominant, softly assembled relations between its parts. Psychologists and neuroscientists frequently use power-law scaling as evidence of critical regimes and soft assembly in neural and cognitive activity. Critics, however, argue that this methodology operates at most at the level of an analogy between cognitive and other natural phenomena. This is because power-laws do not provide information about a particular system's organization or what makes it specifically cognitive. We respond to this criticism using recent work in Integrated Information Theory. We propose a more principled understanding of criticality as a system's susceptibility to changes in its own integration, a property cognitive agents are expected to manifest. We contrast critical integration with power-law measures and find the former more informative about the underlying processes.

Integrated information in the thermodynamic limit.

The capacity to integrate information is a prominent feature of biological, neural, and cognitive processes. Integrated Information Theory (IIT) provides mathematical tools for quantifying the level of integration in a system, but its computational cost generally precludes applications beyond relatively small models. In consequence, it is not yet well understood how integration scales up with the size of a system or with different temporal scales of activity, nor how a system maintains integration as it interacts with its environment. After revising some assumptions of the theory, we show for the first time how modified measures of information integration scale when a neural network becomes very large. Using kinetic Ising models and mean-field approximations, we show that information integration diverges in the thermodynamic limit at certain critical points. Moreover, by comparing different divergent tendencies of blocks that make up a system at these critical points, we can use information integration to delimit the boundary between an integrated unit and its environment. Finally, we present a model that adaptively maintains its integration despite changes in its environment by generating a critical surface where its integrity is preserved. We argue that the exploration of integrated information for these limit cases helps in addressing a variety of poorly understood questions about the organization of biological, neural, and cognitive systems.

Exploring Criticality as a Generic Adaptive Mechanism.

The activity of many biological and cognitive systems is not poised deep within a specific regime of activity. Instead, they operate near points of critical behavior located at the boundary between different phases. Certain authors link some of the properties of criticality with the ability of living systems to generate autonomous or intrinsically generated behavior. However, these claims remain highly speculative. In this paper, we intend to explore the connection between criticality and autonomous behavior through conceptual models that show how embodied agents may adapt themselves toward critical points. We propose to exploit maximum entropy models and their formal descriptions of indicators of criticality to present a learning model that drives generic agents toward critical points. Specifically, we derive such a learning model in an embodied Boltzmann machine by implementing a gradient ascent rule that maximizes the heat capacity of the controller in order to make the network maximally sensitive to external perturbations. We test and corroborate the model by implementing an embodied agent in the Mountain Car benchmark test, which is controlled by a Boltzmann machine that adjusts its weights according to the model. We find that the neural controller reaches an apparent point of criticality, which coincides with a transition point of the behavior of the agent between two regimes of behavior, maximizing the synergistic information between its sensors and the combination of hidden and motor neurons. Finally, we discuss the potential of our learning model to answer questions about the connection between criticality and the capabilities of living systems to autonomously generate intrinsic constraints on their behavior. We suggest that these "critical agents" are able to acquire flexible behavioral patterns that are useful for the development of successful strategies in different contexts.

Adaptation to criticality through organizational invariance in embodied agents.

Many biological and cognitive systems do not operate deep within one or other regime of activity. Instead, they are poised at critical points located at phase transitions in their parameter space. The pervasiveness of criticality suggests that there may be general principles inducing this behaviour, yet there is no well-founded theory for understanding how criticality is generated at a wide span of levels and contexts. In order to explore how criticality might emerge from general adaptive mechanisms, we propose a simple learning rule that maintains an internal organizational structure from a specific family of systems at criticality. We implement the mechanism in artificial embodied agents controlled by a neural network maintaining a correlation structure randomly sampled from an Ising model at critical temperature. Agents are evaluated in two classical reinforcement learning scenarios: the Mountain Car and the Acrobot double pendulum. In both cases the neural controller appears to reach a point of criticality, which coincides with a transition point between two regimes of the agent's behaviour. These results suggest that adaptation to criticality could be used as a general adaptive mechanism in some circumstances, providing an alternative explanation for the pervasive presence of criticality in biological and cognitive systems.

Dilational rheology of oil/water interfaces covered by amphiphilic polysaccharides derived from dextran.

This work studied the adsorption at dodecane/water interface of amphiphilic polysaccharides derived from dextran (a nonionic bacterial polysaccharide) by random attachment of phenoxy groups along the chains (between 10 and 20 attached phenoxy groups per 100 glucose repeat units). The long-time kinetics of interfacial tension decrease was satisfactorily described assuming diffusion-limited adsorption of hydrophobic units (over 4h). Dilational rheology of dodecane/water interface was studied for the first time with that kind of amphiphilic polysaccharides and evidenced a significant elastic component. For all dextran derivatives, experimental results were conveniently described using Lucassen-van den Tempel model which assumed diffusion-limited of surface active species. The characteristic frequency increased with the number of attached phenoxy groups and its order of magnitude (10-3-10-2rad.s-1) was consistent with estimations based on the previous model. Experimental results were compared to those obtained with commercial stabilizers like Pluronics (L64, P105, F68 and F127) and Tween 80.

Extended Neural Metastability in an Embodied Model of Sensorimotor Coupling.

The hypothesis that brain organization is based on mechanisms of metastable synchronization in neural assemblies has been popularized during the last decades of neuroscientific research. Nevertheless, the role of body and environment for understanding the functioning of metastable assemblies is frequently dismissed. The main goal of this paper is to investigate the contribution of sensorimotor coupling to neural and behavioral metastability using a minimal computational model of plastic neural ensembles embedded in a robotic agent in a behavioral preference task. Our hypothesis is that, under some conditions, the metastability of the system is not restricted to the brain but extends to the system composed by the interaction of brain, body and environment. We test this idea, comparing an agent in continuous interaction with its environment in a task demanding behavioral flexibility with an equivalent model from the point of view of "internalist neuroscience." A statistical characterization of our model and tools from information theory allow us to show how (1) the bidirectional coupling between agent and environment brings the system closer to a regime of criticality and triggers the emergence of additional metastable states which are not found in the brain in isolation but extended to the whole system of sensorimotor interaction, (2) the synaptic plasticity of the agent is fundamental to sustain open structures in the neural controller of the agent flexibly engaging and disengaging different behavioral patterns that sustain sensorimotor metastable states, and (3) these extended metastable states emerge when the agent generates an asymmetrical circular loop of causal interaction with its environment, in which the agent responds to variability of the environment at fast timescales while acting over the environment at slow timescales, suggesting the constitution of the agent as an autonomous entity actively modulating its sensorimotor coupling with the world. We conclude with a reflection about how our results contribute in a more general way to current progress in neuroscientific research.

Presentación atípica de la enfermedad de Alexander infantil sin macrocefalia / An atypical presentation of Infantile Alexander disease lacking macrocephaly

Resumen: Introducción: La enfermedad de Alexander consiste en una forma de leucodistrofia poco frecuente que afecta principalmente a los astrocitos; tiene un patrón de herencia autosómica recesiva y es causada por mutaciones en el gen GFAP, localizado en el cromosoma 17q21. Puede presentarse a cualquier edad y la forma infantil se caracteriza por macrocefalia, crisis convulsivas, retraso motor y cognitivo grave y espasticidad o ataxia progresivas. Caso clínico: Paciente de sexo femenino de 8 meses evaluada por retraso psicomotor y crisis convulsivas motoras focales no provocadas. En la exploración física, con perímetro cefálico normal, respuesta motora incrementada ante estímulos táctiles y al ruido, signos piramidales y ausencia de visceromegalias. Se observó hipodensidad generalizada de la sustancia blanca en la resonancia magnética y punción lumbar con hiperproteinorraquia. Se descartó enfermedad de Krabbe mediante ensayo enzimático y secuenciación del gen GALC. En la reevaluación del caso, las alteraciones en la neuroimagen hicieron sospechar de enfermedad de Alexander, y la secuenciación del gen GFAP reportó una mutación en el exón 4 c.716G > A, lo que ocasionó un cambio de arginina por histidina en la posición 239 de la proteína (p.Arg239His). Conclusiones: Los signos radiológicos en la resonancia fueron determinantes para el diagnóstico, que posteriormente se confirmó con estudio molecular. Es importante considerar que ciertas mutaciones no se asocian con macrocefalia, lo cual puede ocasionar retraso en el diagnóstico.

Abstract: Background: Alexander disease is a rare form of leukodystrophy that involves mainly astrocytes; it is inherited in an autosomal recessive manner and occurs by mutations in the GFAP gene, located on chromosome 17q21. It can occur at any age and its infantile form is characterized by macrocephaly, seizures, severe motor and cognitive delay, and progressive spasticity or ataxia. Case report: An 8-month-old female was evaluated with a history of neurodevelopmental delay and unprovoked focal motor seizures. Physical examination showed normal head circumference, increased motor responses to tactile and noise stimuli, pyramidal signs and no visceromegalies. Widespread hypodense white matter was found on magnetic resonance and lumbar puncture showed hyperproteinorrachia. Krabbe disease was ruled out by enzymatic assay and gene sequencing of GALC. In the reassessment of the case, abnormalities in neuroimaging lead to suspicion of Alexander disease, and GFAP gene sequencing reported a pathogenic mutation in exon 4 c.716G > A, which caused a change of arginine to histidine at position 239 of the protein (p.Arg239His). Conclusions: The radiographic signs observed in the resonance were decisive for the diagnosis, later confirmed by molecular study. It is important to consider that certain mutations are not associated with macrocephaly, which may cause delay in diagnosis.

[An atypical presentation of Infantile Alexander disease lacking macrocephaly]. / Presentación atípica de la enfermedad de Alexander infantil sin macrocefalia.

BACKGROUND: Alexander disease is a rare form of leukodystrophy that involves mainly astrocytes; it is inherited in an autosomal recessive manner and occurs by mutations in the GFAP gene, located on chromosome 17q21. It can occur at any age and its infantile form is characterized by macrocephaly, seizures, severe motor and cognitive delay, and progressive spasticity or ataxia. CASE REPORT: An 8-month-old female was evaluated with a history of neurodevelopmental delay and unprovoked focal motor seizures. Physical examination showed normal head circumference, increased motor responses to tactile and noise stimuli, pyramidal signs and no visceromegalies. Widespread hypodense white matter was found on magnetic resonance and lumbar puncture showed hyperproteinorrachia. Krabbe disease was ruled out by enzymatic assay and gene sequencing of GALC. In the reassessment of the case, abnormalities in neuroimaging lead to suspicion of Alexander disease, and GFAP gene sequencing reported a pathogenic mutation in exon 4 c.716G>A, which caused a change of arginine to histidine at position 239 of the protein (p.Arg239His). CONCLUSIONS: The radiographic signs observed in the resonance were decisive for the diagnosis, later confirmed by molecular study. It is important to consider that certain mutations are not associated with macrocephaly, which may cause delay in diagnosis.