Pouvoir d'établissement de quatre graminées fourragères tropicales (Pennisetum purpureum Schum., Panicum maximum Jacq., Brachiaria decumbens Stapf., et Digitaria decumbens Stent.) installées en arrière-saison

Les auteurs exposent les résultats qu'ils ont obtenus, en installant, en fin de saison des pluies, quatre graminées fourragères (Pennisetum purpureum Schum., Panicum maximum Jacq., Brachiaria decumbens Stapf. et Digitaria decumbens Stent.), sur un terrain pauvre situé dans la région de Botucatu, Etat de São Paulo, au Brésil. Les "prises" des boutures ont été excellentes, sauf pour Digitaria qui a eu à souffrir d'une invasion de cochenilles et les productions en fourrage, au cours de la saison des pluies suivante, ont été très satisfaisantes. Cette technique mise en pratique derrière une culture vivrière saisonnière avec ce que cela comporte d'avantages pour les plantes bouturées devrait donner des résultats d'un intérêt économiqu

Actividades de experimentación con materiales de bajo coste para la enseñanza de física: resistores y capacitores de grafito

La necesidad de acercar la ciencia a la realidad cotidiana del alumnado obliga a buscar nuevos recursos que tradicionalmente no eran tratados en la enseñanza formal: la química presente en la cocina y desarrollada a través de los trucos que han funcionado en los tratamientos culinarios. En el presente artículo encontramos una reflexión acerca de la urgencia alfabetizar científicamente y de introducir saberes considerados femeninos en las aulas, una estrategia de búsqueda de recursos: la interpretación científica y las aplicaciones didácticas de distintos trucos de cocina relacionados con frutas, hortalizas y verduras, y por último, algunas sugerencias para llevar a cabo distintas actividades en el aula de secundaria.Palabras clave: Química cotidiana; trucos de cocina; coeducación.Learning chemistry through the culinary treatment of fruit and vegetablesThe need of bringing science near the daily life of students makes us search for new non-traditional ways of teaching: chemistry in cookin and developed through those tricks used in culinary treatments. In this article we can find a reflection on the urgency of teaching science and introducing “women knowledge” in the classroom. We also try to find new ways of teaching through the scientific interpretation and didactic application of different cooking tricks related to fruit and vegetables. Finally we make some suggestionsto be carried out in secondary school classrooms.Key words: Daily life chemistry; cooking tricks; coeducation

In vitro development of primordial follicles after long-term culture of goat ovarian tissue

This study aims to investigate the effects of follicle stimulating hormone (FSH) and fibroblast growth factor-2 (FGF-2) on the survival and growth of caprine preantral follicles. Ovarian tissues were cultured for 1, 7, 14, 21 or 28 days in medium supplemented with FSH (FSH-2d or FSH-7d, i.e., with replacement of the culture medium every 2 or 7 days, respectively) or FSH + FGF-2 (replacement of the medium every 2 days). Non-cultured (control) and cultured ovarian fragments were processed for histological and ultrastructural analysis. After 28 days of culture, the media supplemented with FSH-2d was the most effective in maintaining the percentage of normal follicles and in promoting follicular growth. Furthermore, both treatments with FSH increased the percentage of the primary follicles. However, ultrastructural studies did not confirm follicular integrity from 14 days of culture onward. In conclusion, culturing tissue for up to 7 days in medium containing FSH alone or combined with FGF-2 maintains caprine preantral follicle integrity and promotes their growth in vitro

Antioxidant and antimicrobial films based on brewers spent grain arabinoxylans, nanocellulose and feruloylated compounds for active packaging

In this study, brewers spent grain (BSG) arabinoxylans-based nanocomposite films were prepared by solvent casting of arabinoxylans (AX) suspensions containing different amounts of nanofibrillated cellulose (NFC, 5, 10, 25, 50 and 75% mass fraction). The obtained nanocomposite films were homogeneous and presented thermal stability up to 230 °C and good mechanical properties (Young's modulus up to 7.5 GPa). Additionally, the films with 50% NFC were loaded with ferulic acid or feruloylated arabinoxylo-oligosaccharides enriched fraction from BSG (75 mg per g of film). This combination enhanced the UV–Vis barrier properties and imparted additional functionalities to the films, namely (i) antioxidant activity up to 90% (DPPH scavenging activity), (ii) antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, and (iii) antifungal activity towards the polymorphic fungus Candida albicans. Therefore, these fully biobased nanocomposite films show potential for application as active food packaging systems.publishe

Towards the critical behavior for the light nuclei by NIMROD detector

The critical behavior for the light nuclei with A$\sim 36$ has been investigated experimentally by the NIMROD multi-detectors. The wide variety of observables indicate the critical point has been reached in the disassembly of hot nuclei at an excitation energy of 5.6$\pm$0.5 MeV/u.Comment: 4 pages, 2 figures; Proceeding of 18th Nuclear Physics Division Conference of the Euro. Phys. Society (NPDC18) "Phase transitions in strongly interacting matter", Prague, 23.8.-29.8. 2004. To be published in Nuclear Physics

Produtividade e valor nutritivo de pasto de capim-elefante manejado sob princípios agroecológicos.

Objetivou-se avaliar o valor nutritivo do capim-elefante, quanto aos teores de PB e FDN e a digestibilidade in vitro da MS (DIVMS), submetido a algumas práticas agroecológicas. Foram usados dois piquetes (0,15 ha cada), onde foi estabelecido o capim-elefante, em 2001, com espaçamento entrelinhas de três metros. Nas entrelinhas, estabeleceram-se aveia (Avena strigosa Schreb.) e azevém (Lolium multiflorum Lam.) no período hibernal e, no estival, permitiu-se o desenvolvimento de espécies de crescimento espontâneo. A adubação foi feita com fertilizantes orgânicos (150 kg de N /ha). No período experimental (24/04/2004 a 05/05/2005), foram conduzidos sete pastejos. Os animais experimentais foram vacas da raça Holandesa que receberam, como complementação alimentar, 3,5 kg/dia de concentrado. Avaliaram-se a massa de forragem inicial, composição botânica do pasto e os componentes estruturais. Para as análises de valor nutritivo do pasto, foram feitas amostragens simulando o pastejo. O delineamento experimental foi de blocos ao acaso com duas repetições (piquetes) e sete tratamentos (pastejos). Os melhores resultados do valor nutritivo foram obtidos no período hibernal. Foram encontradas correlações negativas da PB e DIVMS e positivas da FDN com a biomassa de lâminas foliares do capim-elefante. O capim-elefante, manejado sob princípios agroecológicos, apresentou alto valor nutritivo e produtividade, tanto no verão quanto no inverno, possibilitando que a produção animal seja mais sustentável no decorrer do ano

Bayesian joint estimation of non-Gaussianity and the power spectrum

We propose a rigorous, non-perturbative, Bayesian framework which enables one jointly to test Gaussianity and estimate the power spectrum of CMB anisotropies. It makes use of the Hilbert space of an harmonic oscillator to set up an exact likelihood function, dependent on the power spectrum and on a set of parameters $\alpha_i$, which are zero for Gaussian processes. The latter can be expressed as series of cumulants; indeed they perturbatively reduce to cumulants. However they have the advantage that their variation is essentially unconstrained. Any truncation(i.e.: finite set of $\alpha_i$) therefore still produces a proper distribution - something which cannot be said of the only other such tool on offer, the Edgeworth expansion. We apply our method to Very Small Array (VSA) simulations based on signal Gaussianity, showing that our algorithm is indeed not biased.Comment: 11pages, 4 figures, submitted to MNRA