Logic gates operated by bipolar photoelectrochemical water splitting

International audienceA new approach for the design of logic gates that do not involve chemical inputs is presented here. This concept is based on the polarization of a light-sensitive interface. AND and OR logic gates, working with cheap reactants, which locally triggered water splitting half reactions, were designed and operated

Saint-Bertrand-de-Comminges – Coupéré, « Macellum »

Date de l'opération : 1989 (SD) ; 1985 - 1988 (FP) Inventeur(s) : Fabre Gabriel Après les premières interventions qui avaient permis de préciser la nature exacte de cet édifice considéré jusqu’alors comme une basilique, transformée en marché et qui est en fait un macellum construit dans la première moitié du Ier s. après J.-C. (Gallia Informations, 1989 : 101 et 102, fig. 28), il est apparu nécessaire d’assurer la liaison avec les états antérieurs scellés par un pavement mosaïqué couvrant l’e..

Nitrogen and euphotic/mixing zone ratio explain cyanobacterial occurrence in small subtropical man-made lakes (Uruguay)

Las floraciones de cianobacterias potencialmente tóxicas son un problema global causado por el incremento de la eutrofización. Las causas del desarrollo de cianobacterias han sido ampliamente estudiadas en sistemas templados. Estos estudios son escasos en latitudes intermedias, sin embargo, son importantes para evaluar los efectos potenciales del cambio climático. Nuestro objetivo fue explicar las diferencias en la comunidad fitoplanctonica y la presencia de cianobacterias de siete lagos artificiales y eutróficos del sudeste uruguayo, en función de sus variables ambientales. Estudiamos la disponibilidad de recursos, mezcla, depredación y morfometría. Evaluamos experimentalmente la importancia relativa de nitrógeno y fósforo en el crecimiento de las comunidades naturales con cianobacterias. La composición específica del fitoplancton fue diferente en cada lago. Los factores determinantes de la estructura comunitaria fueron la disponibilidad de nitrógeno disuelto y la relación zona eufótica/mezcla. Algunos lagos estuvieron dominados por cianobacterias (Microcystis aeruginosa y Cylindrospermopsis raciborskii) a pesar de las bajas temperaturas (11-12ºC). Encontramos aumento del crecimiento especies de gran tamaño (>10μm), incluyendo cianobacterias fijadoras de nitrógeno, frente al enriquecimiento con nitrato. Sin embargo, los organismos más pequeños (10 μm), including nitrogen fixing cyanobacteria, increased their growth rates with increasing nitrate concentration. In contrast, smaller species (<10 μm) responded to increased phosphate concentration. We observed that there was no correspondence between massive growth of cyanobacteria and lower diversity systems.Fil: Fabre, Amelia. Universidad de la República. Facultad de Ciencias; UruguayFil: Carballo, Carmela. Universidad de la República. Facultad de Ciencias; UruguayFil: Hernandez, Esnedy. Universidad de Antioquia; ColombiaFil: Piriz, Pablo. Universidad de la República. Facultad de Ciencias; UruguayFil: Bergamino, Leandro. Universidad de la República. Facultad de Ciencias; UruguayFil: Mello, Luciana. Universidad de la República. Facultad de Ciencias; UruguayFil: Gonzalez, Silvana. Universidad de la República. Facultad de Ciencias; UruguayFil: Perez, German. Instituto de Investigaciones Biológicas "Clemente Estable"; UruguayFil: León, José Gabriel. Departamento General de Irrigación; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Aubriot, Luis. Universidad de la República. Facultad de Ciencias; UruguayFil: Bonilla, Sylvia. Universidad de la República. Facultad de Ciencias; UruguayFil: Kruk, Carla. Universidad de la República. Facultad de Ciencias; Urugua

Concerns about the widespread use of rodent models for human risk assessments of endocrine disruptors.

International audienceFetal testis is a major target of endocrine disruptors (EDs). During the last 20 years, we have developed an organotypic culture system that maintains the function of the different fetal testis cell types and have used this approach as a toxicological test to evaluate the effects of various compounds on gametogenesis and steroidogenesis in rat, mouse and human testes. We named this test rat, mouse and human fetal testis assay. With this approach, we compared the effects of six potential EDs ((mono-(2-ethylhexyl) phthalate (MEHP), cadmium, depleted uranium, diethylstilboestrol (DES), bisphenol A (BPA) and metformin) and one signalling molecule (retinoic acid (RA)) on the function of rat, mouse and human fetal testis at a comparable developmental stage. We found that the response is similar in humans and rodents for only one third of our analyses. For instance, RA and MEHP have similar negative effects on gametogenesis in the three species. For another third of our analyses, the threshold efficient concentrations that disturb gametogenesis and/or steroidogenesis differ as a function of the species. For instance, BPA and metformin have similar negative effects on steroidogenesis in human and rodents, but at different threshold doses. For the last third of our analyses, the qualitative response is species specific. For instance, MEHP and DES affect steroidogenesis in rodents, but not in human fetal testis. These species differences raise concerns about the extrapolation of data obtained in rodents to human health risk assessment and highlight the need of rigorous comparisons of the effects in human and rodent models, when assessing ED risk

A new chapter in the bisphenol A story: bisphenol S and bisphenol F are not safe alternatives to this compound

Bisphenol A (BPA) is a widely studied typical endocrine-disrupting chemical, and one of the major new issues is the safe replacement of this commonly used compound. Bisphenol S (BPS) and bisphenol F (BPF) are already or are planned to be used as BPA alternatives. With the use of a culture system that we developed (fetal testis assay [FeTA]), we previously showed that 10 nmol/L BPA reduces basal testosterone secretion of human fetal testis explants and that the susceptibility to BPA is at least 100-fold lower in rat and mouse fetal testes. Here, we show that addition of LH in the FeTA system considerably enhances BPA minimum effective concentration in mouse and human but not in rat fetal testes. Then, using the FeTA system without LH (the experimental conditions in which mouse and human fetal testes are most sensitive to BPA), we found that, as for BPA, 10 nmol/L BPS or BPF is sufficient to decrease basal testosterone secretion by human fetal testes with often nonmonotonic dose-response curves. In fetal mouse testes, the dose-response curves were mostly monotonic and the minimum effective concentrations were 1,000 nmol/L for BPA and BPF and 100 nmol/L for BPS. Finally, 10,000 nmol/L BPA, BPS, or BPF reduced Insl3 expression in cultured mouse fetal testes. This is the first report describing BPS and BPF adverse effects on a physiologic function in humans and rodents

Picosecond Synchronization of Photon Pairs through a Fiber Link between Fermilab and Argonne National Laboratories

We demonstrate a three-node quantum network for C-band photon pairs using 2 pairs of 59 km of deployed fiber between Fermi and Argonne National Laboratories. The C-band pairs are directed to nodes using a standard telecommunication switch and synchronized to picosecond-scale timing resolution using a coexisting O- or L-band optical clock distribution system. We measure a reduction of coincidence-to-accidental ratio (CAR) of the C-band pairs from 51 $\pm$ 2 to 5.3 $\pm$ 0.4 due to Raman scattering of the O-band clock pulses. Despite this reduction, the CAR is nevertheless suitable for quantum networks

Para a noção de transformação curricular

Neste artigo é evidenciada a relação entre currículo e conhecimento, abordando-se o conhecimento escolar na sua seleção, organização e transformação, a partir de uma revisão do conceito de transposição didática e da proposição dos conceitos de transformação curricular e transformação didática. Qualquer debate sobre o currículo exige a dilucidação do conhecimento e uma reflexão sobre os seus diversos significados, sobretudo quando a educação se torna num projeto amplo de questionamento da realidade social. Para além de várias questões colocadas acerca do conhecimento escolar e do modo como a sua organização pode ser realizada, procura-se centrar o debate numa reflexão sobre as fronteiras entre conhecimentos e esclarecer que, sobre essa temática, jamais poderão existir respostas fechadas.This article highlights the link between curriculum and knowledge, the approach of school knowledge’s selection, organization and transformation is based on a revision of the concept of didactic transposition and on the proposal of the concepts of curriculum and didactic transformation. Debates on curriculum demand an explanation and a reflection on the multiple meanings of knowledge mainly when education aims to be a broad project to contest social reality. It aims to focus the discussion on a reflection regarding the borders between knowledges and to show that in this subject there are never closed answers.Dans cet article est mis en évidence le rapport entre le curriculum et la connaissance, en abordant la connaissance scolaire dans sa sélection, son organisation et sa transformation à partir d’une révision du concept de transposition didactique et de la proposition des concepts de transformation du curriculum et de transformation didactique. Toute discussion sur le curriculum exige la dilucidation de la connaissance et une réflexion sur ses plusieurs signifiés, surtout quand l’éducation devient un projet plus large de mise en question de la réalité sociale. Au delà des plusieurs questions posées autour de la connaissance scolaire et de la manière comme son organisation peut être réalisée, on cherche á fixer le débat dans une réflexion sur les frontières entre connaissances et éclaircir que, sur cette thématique jamais ne pourront exister des réponses absolues.En este trabajo se pone en evidencia la relación entre el currículum y el conocimiento, abordándose el conocimiento escolar en su selección, organización y transformación desde una revisión del concepto de transposición didáctica y de la proposición de los conceptos de transformación curricular y transformación didáctica. Cualquier discusión sobre el currículum requiere la aclaración del conocimiento y una reflexión sobre sus diversos significados, especialmente cuando la educación se convierte en un proyecto más amplio de cuestionamiento de la realidad social. Además de varias preguntas sobre el conocimiento escolar y el modo en el que su organización puede tener lugar, se intenta centrar el debate en una reflexión sobre las fronteras entre conocimientos y aclarar que en esta temática jamás podrán existir respuestas cerradas.(undefined

The SuperCam Instrument Suite on the Mars 2020 Rover: Science Objectives and Mast-Unit Description

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds

Effects of environmental Bisphenol A exposures on germ cell development and Leydig cell function in the human fetal testis

<div><p>Background</p><p>Using an organotypic culture system termed human Fetal Testis Assay (hFeTA) we previously showed that 0.01 μM BPA decreases basal, but not LH-stimulated, testosterone secreted by the first trimester human fetal testis. The present study was conducted to determine the potential for a long-term antiandrogenic effect of BPA using a xenograft model, and also to study the effect of BPA on germ cell development using both the hFETA and xenograft models.</p><p>Methods</p><p>Using the hFeTA system, first trimester testes were cultured for 3 days with 0.01 to 10 μM BPA. For xenografts, adult castrate male nude mice were injected with hCG and grafted with first trimester testes. Host mice received 10 μM BPA (~ 500 μg/kg/day) in their drinking water for 5 weeks. Plasma levels of total and unconjugated BPA were 0.10 μM and 0.038 μM respectively. Mice grafted with second trimester testes received 0.5 and 50 μg/kg/day BPA by oral gavage for 5 weeks.</p><p>Results</p><p>With first trimester human testes, using the hFeTA model, 10 μM BPA increased germ cell apoptosis. In xenografts, germ cell density was also reduced by BPA exposure. Importantly, BPA exposure significantly decreased the percentage of germ cells expressing the pluripotency marker AP-2γ, whilst the percentage of those expressing the pre-spermatogonial marker MAGE-A4 significantly increased. BPA exposure did not affect hCG-stimulated androgen production in first and second trimester xenografts as evaluated by both plasma testosterone level and seminal vesicle weight in host mice.</p><p>Conclusions</p><p>Exposure to BPA at environmentally relevant concentrations impairs germ cell development in first trimester human fetal testis, whilst gonadotrophin-stimulated testosterone production was unaffected in both first and second trimester testis. Studies using first trimester human fetal testis demonstrate the complementarity of the FeTA and xenograft models for determining the respective short-term and long term effects of environmental exposures.</p></div