The dynamics of motor learning through the formation of internal models

A medical student learning to perform a laparoscopic procedure or a recently paralyzed user of a powered wheelchair must learn to operate machinery via interfaces that translate their actions into commands for an external device. Since the user\u2019s actions are selected from a number of alternatives that would result in the same effect in the control space of the external device, learning to use such interfaces involves dealing with redundancy. Subjects need to learn an externally chosen many-to-one map that transforms their actions into device commands. Mathematically, we describe this type of learning as a deterministic dynamical process, whose state is the evolving forward and inverse internal models of the interface. The forward model predicts the outcomes of actions, while the inverse model generates actions designed to attain desired outcomes. Both the mathematical analysis of the proposed model of learning dynamics and the learning performance observed in a group of subjects demonstrate a first-order exponential convergence of the learning process toward a particular state that depends only on the initial state of the inverse and forward models and on the sequence of targets supplied to the users. Noise is not only present but necessary for the convergence of learning through the minimization of the difference between actual and predicted outcomes

EMG Based Body-Machine Interface for Adaptive and Personalized Robotic Training of Persons with Multiple Sclerosis

Multiple sclerosis is a complex neurological disease that results in motor impairment associated with muscle weakness and lack of motor coordination. Indeed, previous studies showed that, while activities in isolated arm muscles appeared generally similar to those of unimpaired subjects, shoulder muscle coordination with arm motions was affected by MS and there was a marked co-activation of the biceps and triceps in the extension movements. This inability to activate muscles independently has a significant impact in motor function therefore reducing the co-contraction could improve the overall arm function. In this pilot study, we developed a body-machine interface based on muscle activities with the goal of ‘breaking’ the abnormal triceps-biceps co-activation during planar flexion-extension movements of people with multiple sclerosis during a robot-based task. The task consisted in 2D center-out reaching movements with the assistance of a robotic manipulandum. When the subject was not exhibiting the abnormal triceps-biceps co-activation for three consecutive movements the robot was decreasing the assistance. Subjects trained for up to six 1-hour sessions in three weeks. Results showed that the assistance from the robot decreased within each session for most of the subjects, while the movement became faster and straighter. The comparison between muscle activity before and after the training with this body-machine interface demonstrated that subjects learned how to reduce the tricepsbiceps co-activation

Linking satellites to genes with machine learning to estimate phytoplankton community structure from space

Ocean color remote sensing has been used for more than 2 decades to estimate primary productivity. Approaches have also been developed to disentangle phytoplankton community structure based on spectral data from space, in particular when combined with in situ measurements of photosynthetic pigments. Here, we propose a new ocean color algorithm to derive the relative cell abundance of seven phytoplankton groups, as well as their contribution to total chlorophyll a (Chl a) at the global scale. Our algorithm is based on machine learning and has been trained using remotely sensed parameters (reflectance, backscattering, and attenuation coefficients at different wavelengths, plus temperature and Chl a) combined with an omics-based biomarker developed using Tara Oceans data representing a single-copy gene encoding a component of the photosynthetic machinery that is present across all phytoplankton, including both prokaryotes and eukaryotes. It differs from previous methods which rely on diagnostic pigments to derive phytoplankton groups. Our methodology provides robust estimates of the phytoplankton community structure in terms of relative cell abundance and contribution to total Chl a concentration. The newly generated datasets yield complementary information about different aspects of phytoplankton that are valuable for assessing the contributions of different phytoplankton groups to primary productivity and inferring community assembly processes. This makes remote sensing observations excellent tools to collect essential biodiversity variables (EBVs) and provide a foundation for developing marine biodiversity forecasts.</p

The role of antioxidants in the interplay between oxidative stress and senescence

Cellular senescence is an irreversible state of cell cycle arrest occurring in response to stressful stimuli, such as telomere attrition, DNA damage, reactive oxygen species, and oncogenic proteins. Although beneficial and protective in several physiological processes, an excessive senescent cell burden has been involved in various pathological conditions including aging, tissue dysfunction and chronic diseases. Oxidative stress (OS) can drive senescence due to a loss of balance between pro-oxidant stimuli and antioxidant defences. Therefore, the identification and characterization of antioxidant compounds capable of preventing or counteracting the senescent phenotype is of major interest. However, despite the considerable number of studies, a comprehensive overview of the main antioxidant molecules capable of counteracting OS-induced senescence is still lacking. Here, besides a brief description of the molecular mechanisms implicated in OS-mediated aging, we review and discuss the role of enzymes, mitochondria-targeting compounds, vitamins, carotenoids, organosulfur compounds, nitrogen non-protein molecules, minerals, flavonoids, and non-flavonoids as antioxidant compounds with an anti-aging potential, therefore offering insights into innovative lifespan-extending approaches

The Potential Role of Gut Microbiota in Alzheimer’s Disease: from Diagnosis to Treatment

Gut microbiota is emerging as a key regulator of many disease conditions and its dysregulation is implicated in the pathogenesis of several gastrointestinal and extraintestinal disorders. More recently, gut microbiome alterations have been linked to neurodegeneration through the increasingly defined gut microbiota brain axis, opening the possibility for new microbiota-based therapeutic options. Although several studies have been conducted to unravel the possible relationship between Alzheimer’s Disease (AD) pathogenesis and progression, the diagnostic and therapeutic potential of approaches aiming at restoring gut microbiota eubiosis remain to be fully addressed. In this narrative review, we briefly summarize the role of gut microbiota homeostasis in brain health and disease, and we present evidence for its dysregulation in AD patients. Based on these observations, we then discuss how dysbiosis might be exploited as a new diagnostic tool in early and advanced disease stages, and we examine the potential of prebiotics, probiotics, fecal microbiota transplantation, and diets as complementary therapeutic interventions on disease pathogenesis and progression, thus offering new insights into the diagnosis and treatment of this devastating and progressive disease

Blood-Based Biomarkers for Alzheimer’s Disease Diagnosis and Progression: An Overview

Alzheimer’s Disease (AD) is a progressive neurodegenerative disease characterized by amyloid-β (Aβ) plaque deposition and neurofibrillary tangle accumulation in the brain. Although several studies have been conducted to unravel the complex and interconnected pathophysiology of AD, clinical trial failure rates have been high, and no disease-modifying therapies are presently available. Fluid biomarker discovery for AD is a rapidly expanding field of research aimed at anticipating disease diagnosis and following disease progression over time. Currently, Aβ1–42, phosphorylated tau, and total tau levels in the cerebrospinal fluid are the best-studied fluid biomarkers for AD, but the need for novel, cheap, less-invasive, easily detectable, and more-accessible markers has recently led to the search for new blood-based molecules. However, despite considerable research activity, a comprehensive and up-to-date overview of the main blood-based biomarker candidates is still lacking. In this narrative review, we discuss the role of proteins, lipids, metabolites, oxidative-stress-related molecules, and cytokines as possible disease biomarkers. Furthermore, we highlight the potential of the emerging miRNAs and long non-coding RNAs (lncRNAs) as diagnostic tools, and we briefly present the role of vitamins and gut-microbiome-related molecules as novel candidates for AD detection and monitoring, thus offering new insights into the diagnosis and progression of this devastating disease

Síntesis, caracterización y evaluación catalítica de fotocatalizadores obtenidos por inmovilización del ácido tungstofosfórico en zeolitas Y

En las últimas décadas la degradación de sustancias tóxicas en aguas residuales se ha convertido en un importante reto, ya que, debido al incremento de su producción y a su carácter biorecalcitrante, hace que los microorganismos comúnmente utilizados en los sistemas biológicos para su depuración no puedan degradarlos. Uno de los tipos de contaminantes más extendidos son los colorantes de tipo azódicos presentes en aguas residuales de la industria textil, los cuales pueden en muchos casos unirse a cuerpos acuosos subterráneos o superficiales. Los colorantes empleados en la industria textil, tienen gran persistencia en el ambiente, y los métodos de eliminación clásicos no son enteramente útiles debido a que oxidaciones o reducciones parciales pueden generar productos secundarios altamente tóxicos. Una gran proporción de los colorantes no son directamente tóxicos para los organismos vivos; sin embargo, la fuerte coloración que imparten a los medios de descarga puede llegar a suprimir los procesos fotobiosintéticos en los cursos de agua, por lo que su presencia debe ser controlada. Ante esta problemática, la fotocatálisis heterogénea surge como una tecnología promisoria para la remoción de sustancias biorecalcitrantes. Los heteropoliácidos con estructura de Keggin poseen propiedades que son de gran utilidad y valor para la catálisis heterogénea. Muchos de éstos poseen características fotocatalíticas similares a los fotocatalizadores semiconductores; ésto es, pueden ser fotoexitados, tomar electrones del sustrato a degradar, reoxidarse por un aceptor electrónico y volver al estado inicial, para poder ser fotoexitado nuevamente. El ácido tungstofosfórico (TPA) es un heteropolicompuesto que posee acidez Brönsted superior a la de los ácidos sólidos convencionales, es un conocido catalizador ácido y de oxidación, en el cual las propiedades redox y ácido-base pueden adecuarse con el agregado o modificación de los heteroátomos, y es el más utilizado. La principal desventaja que presentan los heteropoliácidos es su baja estabilidad térmica, lo que resulta en una mayor degradación de la estructura principal acompañada de un deterioro de la selectividad y disminución de la actividad catalítica; presentan además elevada solubilidad en agua y solventes orgánicos oxigenados, lo que dificulta su posterior recuperación y reutilización; otra desventaja es su baja superficie específica de área. Para solucionar estas desventajas, disminuir la solubilidad en agua y solventes orgánicos oxigenados, aumentar la superficie específica y permitir la reutilización de estos catalizadores, muchos investigadores los depositan sobre sólidos tales como: SiO₂, Al₂O₃, TiO₂, MCM-41 o zeolitas, entre otros, logrando además un incremento en la estabilidad térmica del material soportado. Las zeolitas ofrecen gran área superficial, estructura porosa única, gran estabilidad térmica, mecánica y química, y han sido poco utilizadas para este fin. Por lo anteriormente mencionado, se ha encarado un estudio sistemático del efecto de la impregnación de TPA sobre la matriz zeolítica NH₄Y; y la evaluación catalítica de material resultante, en la fotodegradación del colorante azódico naranja de metilo (MO).Centro de Investigación y Desarrollo en Ciencias Aplicada

Degradación de diclorvos sobre zeolitas ZSM-11 impregnadas con TiO₂

La degradación fotocatalítica mediada por materiales semiconductores es una alternativa exitosa y conveniente para el tratamiento de aguas residuales que contienen contaminantes orgánicos. El TiO₂, en su fase anatasa, es uno de los catalizadores que exhibe amplias aplicaciones en la degradación de diversos contaminantes, ya que es altamente fotocatalítico. El inconveniente que presenta, es que la recuperación luego de ser utilizado como catalizador en diversos procesos se hace dificultosa, debido a que es un polvo muy fino. Con el fin de resolver este problema, muchos investigadores han examinado algunos métodos para la fijación de TiO₂ en otros materiales de apoyo. Entre los diferentes soportes, las zeolitas son consideradas aptas para tal fin debido a sus características especiales, tales como alta superficie específica lo que permite una gran adsorción de los sustratos a ser degradados, presencia de cajas y canales que permiten confinar las moléculas de los sustratos, incrementando la actividad fotocatalítica, transparencia a la radiación de longitud de onda mayor a 240 nm permitiendo a la luz incidente alcanzar y excitar al huésped fotoactivo, entre otras. Los insecticidas organofosforados se utilizan ampliamente provocando una importante amenaza para los ecosistemas y la salud pública. El Diclorvos (DDVP) es un insecticida organofosforado, empleado para la protección de cultivos, principalmente en invernaderos, y para el control de parásitos e insectos en los hogares. Debido a su solubilidad en agua, los residuos de insecticidas en las prácticas agrícolas pueden infiltrarse a través del suelo en las aguas superficiales y finalmente causar daño en los organismos acuáticos. Por lo tanto, se hace necesario quitar los residuos de este compuesto tóxico en el agua mediante la elaboración de un método de purificación eficiente y económico. En el presente trabajo de investigación se degradará el diclorvos mediante fotocatálisis heterogénea utilizando como catalizadores zeolitas del tipo ZSM-11 impregnadas con TiO₂. Se prepararán catalizadores con distintos porcentajes de carga de dióxido de titanio sobre la matriz zeolítica y se caracterizarán por dos técnicas: Difracción de rayos X (DRX) y Espectroscopia Infrarroja (IR). Los catalizadores preparados fueron comparados con la zeolita sin carga de TiO₂ y con el TiO₂ Degussa P25, el cuál es generalmente utilizado como referencia.Centro de Investigación y Desarrollo en Ciencias Aplicada

Upper Body-Based Power Wheelchair Control Interface for Individuals with Tetraplegia

Many power wheelchair control interfaces are not sufficient for individuals with severely limited upper limb mobility. The majority of controllers that do not rely on coordinated arm and hand movements provide users a limited vocabulary of commands and often do not take advantage of the user's residual motion. We developed a body-machine interface (BMI) that leverages the flexibility and customizability of redundant control by using high dimensional changes in shoulder kinematics to generate proportional control commands for a power wheelchair. In this study, three individuals with cervical spinal cord injuries were able to control a power wheelchair safely and accurately using only small shoulder movements. With the BMI, participants were able to achieve their desired trajectories and, after five sessions driving, were able to achieve smoothness that was similar to the smoothness with their current joystick. All participants were twice as slow using the BMI however improved with practice. Importantly, users were able to generalize training controlling a computer to driving a power wheelchair, and employed similar strategies when controlling both devices. Overall, this work suggests that the BMI can be an effective wheelchair control interface for individuals with high-level spinal cord injuries who have limited arm and hand control

Greener Method to Obtain a Key Intermediate of Vitamin E over Cu-ZSM-5

The catalytic oxidation of 2,3,5-trimethylphenol was performed over transition metals modified ZSM-5 zeolites employing hydrogen peroxide as oxidant under mild reaction conditions. Catalysts samples were characterized by several techniques (XRD, FTIR, BET, AA) and cristallinity and orthorhombic symmetry were confirmed for all of them. Best catalytic results were obtained for Cu-ZSM-5 sample, so further activity studies were done over this material. 2,3,5-trimethyl-1,4-benzoquinone was obtained as the main product of the selective oxidation. Reaction parameters (nature of the solvent, hydrogen peroxide concentration, reaction time, catalyst mass, substrate initial concentration and reaction temperature) were evaluated to reach the optimum reaction conditions. According to the obtained results, an apparent activation energy of 52.33 kJ/mol was calculated.Fil: Saux, Clara. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; ArgentinaFil: Renzini, Maria Soledad. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; ArgentinaFil: Gómez, Silvina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; ArgentinaFil: Pierella, Liliana Beatriz. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; Argentin