96 research outputs found
A redenção cósmica do mestiço: inversão semântica do conceito de raça na Raza cósmica de José Vasconcelos
Contribution of Social Isolation, Restraint, and Hindlimb Unloading to Changes in Hemodynamic Parameters and Motion Activity in Rats
The most accepted animal model for simulation of the physiological and morphological consequences of microgravity on the cardiovascular system is one of head-down hindlimb unloading. Experimental conditions surrounding this model include not only head-down tilting of rats, but also social and restraint stresses that have their own influences on cardiovascular system function. Here, we studied levels of spontaneous locomotor activity, blood pressure, and heart rate during 14 days under the following experimental conditions: cage control, social isolation in standard rat housing, social isolation in special cages for hindlimb unloading, horizontal attachment (restraint), and head-down hindlimb unloading. General activity and hemodynamic parameters were continuously monitored in conscious rats by telemetry. Heart rate and blood pressure were both evaluated during treadmill running to reveal cardiovascular deconditioning development as a result of unloading. The main findings of our work are that: social isolation and restraint induced persistent physical inactivity, while unloading in rats resulted in initial inactivity followed by normalization and increased locomotion after one week. Moreover, 14 days of hindlimb unloading showed significant elevation of blood pressure and slight elevation of heart rate. Hemodynamic changes in isolated and restrained rats largely reproduced the trends observed during unloading. Finally, we detected no augmentation of tachycardia during moderate exercise in rats after 14 days of unloading. Thus, we concluded that both social isolation and restraint, as an integral part of the model conditions, contribute essentially to cardiovascular reactions during head-down hindlimb unloading, compared to the little changes in the hydrostatic gradient
Human Gamma Oscillations during Slow Wave Sleep
Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS). At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30–50 Hz) and high (60–120 Hz) frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves (“IN-phase” pattern), confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave (“ANTI-phase” pattern). This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks
Présentation
Fell Claude. Présentation. In: América : Cahiers du CRICCAL, n°4-5, 1990. Le discours culturel dans les revues latino-américaines de l'entre-deux guerres, 1919-1939. pp. 7-11
La littérature éducative au Mexique après la révolution : Gabriela Mistral et José Vasconcelos
Dans un Mexique qui, au terme de dix années de guerre civile presque ininterrompue, repense les modalités de son enseignement, de ses méthodes éducatives et de sa politique culturelle, le rôle et la diffusion du livre, tant dans le contexte scolaire qu'en dehors même de l'école, sont au cœur des débats et vont susciter ce qui ressemble parfois à des polémiques. On peut s'arrêter brièvement sur trois controverses principales. La première éclate en 1919 et elle est liée au contenu, à l'élaborat..
La polémique de l'École Nationale Préparatoire (Mexico, 1922)
Fell Claude. La polémique de l'École Nationale Préparatoire (Mexico, 1922). In: América : Cahiers du CRICCAL, n°21, 1998. Polémiques et manifestes aux XIXe et XXe siècles en Amérique latine. pp. 155-161
Le département de la Culture et de l'Éducation Indigène au Mexique au lendemain de la Révolution (1920-1924)
On peut affirmer que la question indienne est présente, de façon explicite ou larvée, dans la pensée de tous les intellectuels, hommes politiques et pédagogues mexicains, au cours des premières décennies du XXe siècle. La Révolution de 1910 n'a fait que rendre le problème plus actuel encore et lorsque se termine la phrase armée de cette énorme secousse qui a ébranlé le Mexique pendant presque dix ans, nombreux sont ceux qui s'interrogent sur « l'intégration » – certains disent « la régénérati..
Présentation
Fell Claude. Présentation. In: América : Cahiers du CRICCAL, n°3, 1988. Les mythes identitaires en Amérique latine. pp. 7-8
D'un dirigisme à l'autre. L'université de Mexico entre le porfirisme et la post-revolution (1910-1925)
Créée en 1551 -elle s'appellera pendant la période coloniale "Real y pontificia Universidad de México"- l'Université de Mexico est une des plus anciennes du continent américain. Elle fut également, pendant la colonisation espagnole, un des plus brillants centres intellectuels des Indes Occidentales. Après l'Indépendance, elle s'enfoncera lentement dans l'archaïsme, le désordre et l'apathie, jusqu'en 1865, date à laquelle l'Empereur Maximilien décide de fermer l'Université et de ne laisser sub..
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