Effect of the photoperiod on the glutamate level in the suprachiasmatic nucleus of pregnant and non-pregnant rabbits

[EN] Microdialysis sampling was used to measure the glutamate level (GLU) contained in the suprachiasmatic nucleus (SCN) in 10 pregnant and 10 non-pregnant, subjected to either a 16:8 h light-dark cycle or a 12 h advanced photoperiod. Results revealed that GLU levels were significantly greater in samples taken for 2 h (15 min intervals), ¿60, ¿45 and ¿30 min before parturition (P<0.009, P<0.04, P<0.02), and +45 and +60 min after birth (P<0.009, P<0.05) respectively, in pregnant rabbits subjects to a 16:8 LD photoperiod (with light from 6:00-22:00 h). Parturition in these animals occurred at day 31 of gestation. Pregnant rabbits exposed to 12 h advanced photoperiod showed lower GLU levels in the SCN, and a longer gestation period and parturition process. In non-pregnant rabbits the GLU levels in the SCN were also significantly higher (P<0.009, in all samples) in comparison with rabbits subjected to the 12 h shifted photoperiod. It is possible that the photoperiod may have influenced GLU levels, and consequently, the length of gestation, the number of young and the time of birth. However, further studies involving new biotechnologies and a greater number of animals are needed to confirm these results.Reyes-Guerrero, G.; Vázquez-García, M.; Calderón-Guzmán, D.; Donatti-Albarrán, O.; Guevara-Guzmán, R. (2008). Effect of the photoperiod on the glutamate level in the suprachiasmatic nucleus of pregnant and non-pregnant rabbits. World Rabbit Science. 16(3). doi:10.4995/wrs.2008.62316

The end-to-end testbed of the Optical Metrology System on-board LISA Pathfinder

LISA Pathfinder is a technology demonstration mission for the Laser Interferometer Space Antenna (LISA). The main experiment on-board LISA Pathfinder is the so-called LISA Technology Package (LTP) which has the aim to measure the differential acceleration between two free-falling test masses with an accuracy of 3x10^(-14) ms^(-2)/sqrt[Hz] between 1 mHz and 30 mHz. This measurement is performed interferometrically by the Optical Metrology System (OMS) on-board LISA Pathfinder. In this paper we present the development of an experimental end-to-end testbed of the entire OMS. It includes the interferometer and its sub-units, the interferometer back-end which is a phasemeter and the processing of the phasemeter output data. Furthermore, 3-axes piezo actuated mirrors are used instead of the free-falling test masses for the characterisation of the dynamic behaviour of the system and some parts of the Drag-free and Attitude Control System (DFACS) which controls the test masses and the satellite. The end-to-end testbed includes all parts of the LTP that can reasonably be tested on earth without free-falling test masses. At its present status it consists mainly of breadboard components. Some of those have already been replaced by Engineering Models of the LTP experiment. In the next steps, further Engineering Models and Flight Models will also be inserted in this testbed and tested against well characterised breadboard components. The presented testbed is an important reference for the unit tests and can also be used for validation of the on-board experiment during the mission

Carbon and oxygen in HII regions of the Magellanic Clouds: abundance discrepancy and chemical evolution

We present C and O abundances in the Magellanic Clouds derived from deep spectra of HII regions. The data have been taken with the Ultraviolet-Visual Echelle Spectrograph at the 8.2-m VLT. The sample comprises 5 HII regions in the Large Magellanic Cloud (LMC) and 4 in the Small Magellanic Cloud (SMC). We measure pure recombination lines (RLs) of CII and OII in all the objects, permitting to derive the abundance discrepancy factors (ADFs) for O^2+, as well as their O/H, C/H and C/O ratios. We compare the ADFs with those of other HII regions in different galaxies. The results suggest a possible metallicity dependence of the ADF for the low-metallicity objects, but more uncertain for high-metallicity objects. We compare nebular and B-type stellar abundances and we find that the stellar abundances agree better with the nebular ones derived from collisionally excited lines (CELs). Comparing these results with other galaxies we observe that stellar abundances seem to agree better with the nebular ones derived from CELs in low-metallicity environments and from RLs in high-metallicity environments. The C/H, O/H and C/O ratios show almost flat radial gradients, in contrast with the spiral galaxies where such gradients are negative. We explore the chemical evolution analysing C/O vs. O/H and comparing with the results of HII regions in other galaxies. The LMC seems to show a similar chemical evolution to the external zones of small spiral galaxies and the SMC behaves as a typical star-forming dwarf galaxy.Comment: Accepted for publication in MNRAS, 17 pages, 11 figures, 8 table

Caracterización energética de la unión de 1,3,6- naftalén trisulfonato al factor de crecimiento para fibroblastos ácido humano: implicaciones para su uso como agente anti-angiogénico

The equilibrium interaction of anti-cancer agent 1,3,6-naphatalene trisulfonate with human acidic fi broblast growthfactor has been studied by calorimetry. The affi nity decreases with increasing ionic strength. At pH 7.0 and 0.15 MNaCl concentration, a binding constant of the protein with the ligand was estimated in the 102 – 103 M-1 range, anaffi nity two orders of magnitude lower than that of aFGF with heparin. The interaction is enthalpically driven, andthe entropy change is unfavorable. A small heat capacity change with an unusual positive value of 90 cal K-1mol-1 wasdetermined from the temperature dependence of the enthalpies. Changes in accessible apolar and polar surface areasin the interaction were calculated from the thermodynamic data obtained and parametric equations in the literature.The results were compared with those measured from NMR data. The study includes structural bioenergetic considerationsabout the possible use of 1,3,6-naphatalene trisulfonate as an anti-angiogenic agent itself, or as a lead for thedevelopment of anti-angiogenic drugs.Se ha estudiado, mediante calorimetría isotérmica de reacción, la interacción del agente anticancerígeno 1,3,6-naftaléntrisulfonato con el factor de crecimiento para fi broblastos ácido humano. La afi nidad decrece con el aumento de lafuerza iónica. A pH 7,0 y NaCl 0,15 M, la constante de unión de la proteína con el ligando se encuentra en el rango102 – 103 M-1, una afi nidad dos órdenes de magnitud menor que la del FGFa por heparina. El cambio de entalpíafavorece la interacción, siendo el cambio de entropía desfavorable. De la dependencia del cambio de entalpía con latemperatura se calculó un pequeño cambio en la capacidad calorífi ca del proceso, con un valor excepcionalmentepositivo de 90 cal K-1mol-1. A partir de los datos termodinámicos medidos y de ecuaciones paramétricas establecidasen la literatura, se calcularon cambios en la superfi cie accesible al disolvente, tanto polar como apolar, que acompañana la interacción. Los resultados se compararon con los medidos mediante resonancia magnética nuclear. Elestudio incluye consideraciones de bioenergética estructural sobre el posible uso de 1,3,6-naftalén trisulfonato comoagente antiangiogénico o como molécula líder para el desarrollo de fármacos anti-angiogénicos

Hermenêutica da pergunta pedagógica: Aprendizagem mediada pela prática da liberdade a partir da perspectiva de Freire

El ser humano se aproxima al mundo mediante la dialéctica de pregunta y respuesta para construir socialmente la realidad mediante la práctica de la libertad. En este contexto, el estudio se realizó con el objetivo de exponer el análisis hermenéutico de la pregunta pedagógica como instrumento pedagógico para el aprendizaje mediado por la práctica de la libertad desde la perspectiva de Freire. Desde el campo de la investigación filosófica se desarrollaron tres etapas (construcción del horizonte de comprensión, destructiva y constructiva) para proyectar la tradición educativa de Vigotsky y Ausubel hacia la hermenéutica de la pregunta y confrontar el aporte de la pedagogía de la pregunta de Freire. Los resultados obtenidos recuperan la pregunta inicial, mediadora y esencial situándolas en relación con la estructura y horizonte de la pregunta. El acto de preguntar se rehabilita como práctica de la libertad al mediar el aprendizaje desde el pensamiento crítico y creativo.The man approaches the world through the dialectic of question and answer to socially construct reality by practicing freedom. In this context, the study was conducted with the aim of exposing the hermeneutical analysis of the pedagogical question as an educational tool for learning through practice of freedom from the perspective of Freire. From the field of philosophical inquiry three stages (construction horizon of understanding, destructive and constructive) were developed to project the educational tradition of Vygotsky and Ausubel hermeneutics to question and confront the contribution of pedagogy Freire's question. The results obtained recover the initial question, mediator and essential placing them in relation to the structure and horizon of the question. The act of asking is rehabilitated as a practice of freedom to mediate learning from the critical and creative thinkingO ser humano aproxima-se ao mundo mediante a dialética de pergunta e resposta para construir socialmente a realidade mediante a prática da liberdade. Neste contexto, o estudo realizou-se com o objetivo de expor a análise hermenêutica da pergunta pedagógica como instrumento pedagógico para a aprendizagem mediada pela prática de liberdade a partir da perspectiva de Freire. Do campo da investigação filosófica desenvolveram-se três etapas (construção do horizonte de compreensão, destrutiva e construtiva) para projetar a tradição educativa de Vigotsky e Ausubel para a hermenêutica da pergunta e confrontar a contribuição da pedagogia da pergunta de Freire. Os resultados obtidos recuperam a pergunta inicial, mediadora e essencial situando-as em relação com a estrutura e horizonte da pergunta. O ato de perguntar reabilita-se como prática da liberdade ao mediar a aprendizagem a partir do pensamento crítico e criativ

High resolution spectroscopy of the high velocity hot post-AGB star LS III +52 24 (IRAS 22023+5249)

The first high-resolution (R~50,000) optical spectrum of the B-type star, LS III +52 24, identified as the optical counterpart of the hot post-AGB candidate IRAS 22023+5249 (I22023) is presented. We report the detailed identifications of the observed absorption and emission features in the full wavelength range (4290-9015 A) as well as the atmospheric parameters and photospheric abundances (under the Local Thermodinamic Equilibrium approximation) for the first time. The nebular parameters (Te, Ne) are also derived. We estimate Teff=24,000 K, log g=3.0, xi=7 kms-1 and the derived abundances indicate a slightly metal-deficient evolved star with C/O<1. The observed P-Cygni profiles of hydrogen and helium clearly indicate on-going post-AGB mass loss. The presence of [N II] and [S II] lines and the non-detection of [O III] indicate that photoionisation has just started. The observed spectral features, large heliocentric radial velocity, atmospheric parameters, and chemical composition indicate that I22023 is an evolved post-AGB star belonging to the old disk population. The derived nebular parameters (Te=7000 K, Ne=1.2x104 cm-3) also suggest that I22023 may be evolving into a compact, young low-excitation Planetary Nebula. Our optical spectroscopic analysis together with the recent Spitzer detection of double-dust chemistry (the simultaneous presence of carbonaceous molecules and amorphous silicates) in I22023 and other B-type post-AGB candidates may point to a binary system with a dusty disk as the stellar origin common to the hot post-AGB stars with O-rich central stars.Comment: Accepted for publication in MNRAS (22 pages, 4 figures, and 8 tables). arXiv admin note: substantial text overlap with arXiv:0707.059

Una especie nueva de avispa gallícola para México: Andricus sphaericus Pujade-Villar n. sp. (Hymenoptera: Cynipidae: Cynipini)

Se describe una nueva especie de cinípido gallícola de México, Andricus sphaericus Pujade-Villar n. sp., solo conocida por su forma sexual. Induce agallas en las hojas de Quercus rugosa Née. Representa la segunda colecta de una generación sexual del género Andricus para México. Se proporcionan datos referidos a la diagnosis, distribución y biología de esta nueva especie