Plantar flexion force induced by amplitude-modulated tendon vibration and associated soleus V/F-waves as an evidence of a centrally-mediated mechanism contributing to extra torque generation in humans

Background: High-frequency trains of electrical stimulation applied over the human muscles can generate forces higher than would be expected by direct activation of motor axons, as evidenced by an unexpected relation between the stimuli and the evoked contractions, originating what has been called “extra forces”. This phenomenon has been thought to reflect nonlinear input/output neural properties such as plateau potential activation in motoneurons. However, more recent evidence has indicated that extra forces generated during electrical stimulation are mediated primarily, if not exclusively, by an intrinsic muscle property, and not from a central mechanism as previously thought. Given the inherent differences between electrical and vibratory stimuli, this study aimed to investigate: (a) whether the generation of vibration-induced muscle forces results in an unexpected relation between the stimuli and the evoked contractions (i.e. extra forces generation) and (b) whether these extra forces are accompanied by signs of a centrally-mediated mechanism or whether intrinsic muscle properties are the redominant mechanisms. Methods: Six subjects had their Achilles tendon stimulated by 100 Hz vibratory stimuli that linearly increased in amplitude (with a peak-to-peak displacement varying from 0 to 5 mm) for 10 seconds and then linearly decreased to zero for the next 10 seconds. As a measure of motoneuron excitability taken at different times during the vibratory stimulation, short-latency compound muscle action potentials (V/F-waves) were recorded in the soleus muscle in response to supramaximal nerve stimulation. Results: Plantar flexion torque and soleus V/F-wave amplitudes were increased in the second half of the stimulation in comparison with the first half. Conclusion: The present findings provide evidence that vibratory stimuli may trigger a centrally-mediated mechanism that contributes to the generation of extra torques. The vibration-induced increased motoneuron excitability (leading to increased torque generation) presumably activates spinal motoneurons following the size principle, which is a desirable feature for stimulation paradigms involved in rehabilitation programs and exercise training.

Mapping the lignin distribution in pretreated sugarcane bagasse by confocal and fluorescence lifetime imaging microscopy

Abstract Background Delignification pretreatments of biomass and methods to assess their efficacy are crucial for biomass-to-biofuels research and technology. Here, we applied confocal and fluorescence lifetime imaging microscopy (FLIM) using one- and two-photon excitation to map the lignin distribution within bagasse fibers pretreated with acid and alkali. The evaluated spectra and decay times are correlated with previously calculated lignin fractions. We have also investigated the influence of the pretreatment on the lignin distribution in the cell wall by analyzing the changes in the fluorescence characteristics using two-photon excitation. Eucalyptus fibers were also analyzed for comparison. Results Fluorescence spectra and variations of the decay time correlate well with the delignification yield and the lignin distribution. The decay dependences are considered two-exponential, one with a rapid (τ1) and the other with a slow (τ2) decay time. The fastest decay is associated to concentrated lignin in the bagasse and has a low sensitivity to the treatment. The fluorescence decay time became longer with the increase of the alkali concentration used in the treatment, which corresponds to lignin emission in a less concentrated environment. In addition, the two-photon fluorescence spectrum is very sensitive to lignin content and accumulation in the cell wall, broadening with the acid pretreatment and narrowing with the alkali one. Heterogeneity of the pretreated cell wall was observed. Conclusions Our results reveal lignin domains with different concentration levels. The acid pretreatment caused a disorder in the arrangement of lignin and its accumulation in the external border of the cell wall. The alkali pretreatment efficiently removed lignin from the middle of the bagasse fibers, but was less effective in its removal from their surfaces. Our results evidenced a strong correlation between the decay times of the lignin fluorescence and its distribution within the cell wall. A new variety of lignin fluorescence states were accessed by two-photon excitation, which allowed an even broader, but complementary, optical characterization of lignocellulosic materials. These results suggest that the lignin arrangement in untreated bagasse fiber is based on a well-organized nanoenvironment that favors a very low level of interaction between the molecules.

Insurrectos cubanos deportados hacia Canarias y Fernando Poo (1869): un ejemplo de deportación política

[ES] Aproximación a la deportación política: causas, circunstancias que la rodean y caracterización del fenómeno, para ello nos centramos en un proceso concreto: la deportación de insurrectos cubanos en 1869 con dirección a Fernando Póo y que afecta directamente a las Islas Canarias, lugar utilizado tradicionalmente como destierro. En este sentido, intentamos acercarnos a las controversias y reacciones que genera el fenómeno de la deportación, en la población, en general así como en los grupos de poder político de las islas, en particular.

Sobre Fernando Estévez y algunas esculturas del Niño Jesús. Nuevas atribuciones

[ES] La conmemoración del ccxxv aniversario del nacimiento de Fernando Estévez (1788-1854) en 2013 propició una aproximación diferente a la trayectoria de dicho artista. Este artículo recuerda las actividades organizadas entonces en La Orotava, especialmente una exposición de esculturas y documentos que tuvo varias sedes o lugares de exhibición durante el mes de marzo. Partiendo de obras contempladas entonces, se estudian otras representaciones del Niño Jesús que conservan templos del norte de Tenerife y pueden atribuírsele por cuestiones de estilo. [EN] The commemoration of 225th birth anniversary of Fernando Estévez (1788-1854) in 2013 allowed a new approach to his artistic caree. This paper recalls the activities organised in La Orotava back then, especially an exhibition of sculptures and documents in several spaces during the month of March. Based on the sculptures seen there, we can attribute to him other representations of the Infant Jesus that are preserved in churches in northern Tenerife.

Tradurre la letteratura per l'infanzia: El árbol de los sueños di Fernando Alonso.

Quest'elaborato si concentra nella traduzione dallo spagnolo all'italiano di due capitoli di un libro per bambini: El árbol de los sueños di Fernando Alonso. L'elaborato è preceduto da un'introduzione nella quale spiego la struttura generale dello stesso e le ragioni per cui ho deciso di dedicarmi a questo libro ed è seguito da una conclusione che ne ricapitola il contenuto. Poi, si compone di quattro capitoli: nel primo presento l'autore, importante scrittore di letteratura per bambini in Spagna, e le sue opere in generale. Nel secondo propongo un'analisi generale del testo di partenza, la trama e i personaggi. Il terzo capitolo presenta la mia proposta di traduzione del terzo e del sesto capitolo del libro, con alcune illustrazioni incluse. L'ultimo è un commento alla traduzione, nel quale spiego le difficoltà incontrate, le soluzioni e le strategie adottate.

El politico D. Fernando El Catholico de Lorenzo Gracián : que publica Vincencio Juan de Lastanosa

Signatur Na 50, Schop 603/56 Nr. 2