Higher education and ethnicity: A case study with Aymara students.

We aim to understand the strategies that Aymara students have developed to overcome the vulnerability in access and permanence in higher education. For Aymara students, references external to the institution act as protection factors of the support network that decisively determine their adaptation to the educational environment. Methodologically, this study accounts for a case study in northern Chile regions, using biographical interviews to build the narrative regarding the university experience of the students. Main highlights establish that though ethnic-racial and socioeconomic dimensions intersect in the significance of student's vulnerability important sources of identity reinforce their resilience, subjectivities, and empowerment processes. We conclude that the learning experience is not developed exclusively in the educational institution, but it is the socioaffective space linked to the peers, the family and the community which have a decisive role, which in the case of the Aymara students, acquires an intercultural nature.

The Hemodynamic Mass Action of a Central Pattern Generator.

The hemodynamic response is a neurovascular and metabolic process in which there is rapid delivery of blood flow to a neuronal tissue in response to neuronal activation. The functional magnetic resonance imaging (fMRI) and the functional near-infrared spectroscopy (fNIRS), for instance, are based on the physiological principles of such hemodynamic responses. Both techniques allow the mapping of active neuronal regions in which the neurovascular and metabolic events are occurring. However, although both techniques have revolutionized the neurosciences, they are mostly employed for neuroimaging of the human brain but not for the spinal cord during functional tasks. Moreover, little is known about other techniques measuring the hemodynamic response in the spinal cord. The purpose of the present study was to show for the first time that a simple optical system termed direct current photoplethysmography (DC-PPG) can be employed to detect hemodynamic responses of the spinal cord and the brainstem during the functional activation of the spinal central pattern generator (CPG). In particular, we positioned two DC-PPG systems directly on the brainstem and spinal cord during fictive scratching in the cat. The optical DC-PPG systems allowed the trial-by-trial recording of massive hemodynamic signals. We found that the "strength" of the flexor-plus-extensor motoneuron activities during motor episodes of fictive scratching was significantly correlated to the "strengths" of the brainstem and spinal DC-PPG signals. Because the DC-PPG was robustly detected in real-time, we claim that such a functional signal reflects the hemodynamic mass action of the brainstem and spinal cord associated with the CPG motor action. Our findings shed light on an unexplored hemodynamic observable of the spinal CPGs, providing a proof of concept that the DC-PPG can be used for the assessment of the integrity of the human CPGs.

Resetting the Respiratory Rhythm with a Spinal Central Pattern Generator.

There is evidence that a variety of central and afferent stimuli, including swallowing, can produce phase resetting in the respiratory rhythmicity. Also, there are reports about the intrinsic linkage between locomotion and respiration. However, little is known about the interaction between the central pattern generators (CPGs) for scratching and respiration. The present study aims to examine whether the activation of scratching CPG produces phase resetting of the respiratory rhythm. We employed decerebrate cats to apply brief tactile stimuli to the pinna during the inspiratory-expiratory transition. We observed that those stimuli to the pinna not eliciting fictive scratching did not reset the respiratory rhythm. However, when the pinna stimuli elicited fictive scratching, then the respiratory rhythm exhibited a significant phase resetting. We also found interneurons in the medulla oblongata exhibiting phase resetting related to scratching-CPG episodes. This second finding suggests that this type of resetting involves brainstem components of the respiratory CPG. These results shed new light on the resetting action from a spinal CPG on the respiratory rhythm.

Características de la oclusión en niños con dentición primaria en la ciudad de México / Occlusion characteristics in children with primary dentition from Mexico city

El fenómeno más dinámico que se observa en la boca es el de la oclusión dental. Las características de la oclusión durante la dentición primaria se consideran precursoras de las de la oclusión en la dentición permanente; de ahí la importancia de su comprensión y entendimiento. Objetivo: el propósito de este trabajo fue conocer las características de la oclusión dental durante la dentición primaria en un grupo de niños mexicanos de un nivel socio-económico medio bajo. Muestra: se revisaron 42 niños y 58 niñas, entre 3 y 5 años de edad, con dentición temporal completa. Material y métodos: se realizó un estudio observacional, prolectivo, transversal y descriptivo. Las características de la oclusión se observaron en modelos de estudio y los datos se analizaron estadísticamente por medio del programa SPSS y la prueba de Chi cuadrado con un nivel de confianza del 95 por ciento. Resultados: la forma de arco más frecuente fue la ovoide en 71 por ciento de los niñosy 74 por ciento en las niñas en el maxilar, en la mandíbula 81 por ciento para las niñas y 64 por ciento para los niños. Los espacio primates invertidos se observaron e 7 por ciento de los niños y 22 por ciento de las niñas. La sobremordida vertical aumentada se presentó en 57 por ciento de los niños y 55 por ciento de las niñas, la sobremordida horizontal ideal con 52 por ciento para los niños y 59 por ciento para las niñas. La relación canina Clase I representó el 88 por ciento en niños y 85 por ciento en niñas. El plano terminal mesial en 79 por ciento de los niños y 81 por ciento de las niñas, el plano terminal recto se observó en 12 por ciento de los niños y 16 por ciento en las niñas. Conclusiones: las características consideradas como ideales pueden tener variaciones debido a las características raciales de los individuaos sin que esto represente una alteración en la oclusión o desarrollo de la misma