1,069 research outputs found

    Sea surface salinity variability from a simplified mixed layer model of the global ocean

    No full text
    International audienceA bi-dimensional mixed layer model (MLM) of the global ocean is used to investigate the sea surface salinity (SSS) balance and variability at daily to seasonal scales. Thus a simulation over an average year is performed with daily climatological forcing fields. The forcing dataset combines air-sea fluxes from a meteorological model, geostrophic currents from satellite altimeters and in situ data for river run-offs, deep temperature and salinity. The model is based on the "slab mixed layer" formulation, which allows many simplifications in the vertical mixing representation, but requires an accurate estimate for the Mixed Layer Depth. Therefore, the model MLD is obtained from an original inversion technique, by adjusting the simulated temperature to input sea surface temperature (SST) data. The geographical distribution and seasonal variability of this "effective" MLD is validated against an in situ thermocline depth. This comparison proves the model results are consistent with observations, except at high latitudes and in some parts of the equatorial band. The salinity balance can then be analysed in all the remaining areas. The annual tendency and amplitude of each of the six processes included in the model are described, whilst providing some physical explanations. A map of the dominant process shows that freshwater flux controls SSS in most tropical areas, Ekman transport in Trades regions, geostrophic advection in equatorial jets, western boundary currents and the major part of subtropical gyres, while diapycnal mixing leads over the remaining subtropical areas and at higher latitudes. At a global scale, SSS variations are primarily caused by horizontal advection (46%), then vertical entrainment (24%), freshwater flux (22%) and lateral diffusion (8%). Finally, the simulated SSS variability is compared to an in situ climatology, in terms of distribution and seasonal variability. The overall agreement is satisfying, which confirms that the salinity balance is reliable. The simulation exhibits stronger gradients and higher variability, due to its fine resolution and high frequency forcing. Moreover, the SSS variability at daily scale can be investigated from the model, revealing patterns considerably different from the seasonal cycle. Within the perspective of the future satellite missions dedicated to SSS retrieval (SMOS and Aquarius/SAC-D), the MLM could be useful for determining calibration areas, as well as providing a first-guess estimate to inversion algorithms

    Acute stress enhances heterodimerization and binding of corticosteroid receptors at glucocorticoid target genes in the hippocampus

    Get PDF
    A stressful event results in secretion of glucocorticoid hormones, which bind to mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) in the hippocampus to regulate cognitive and affective responses to the challenge. MRs are already highly occupied by low glucocorticoid levels under baseline conditions, whereas GRs only become substantially occupied by stress- or circadian-driven glucocorticoid levels. Currently, however, the binding of MRs and GRs to glucocorticoid-responsive elements (GREs) within hippocampal glucocorticoid target genes under such physiological conditions in vivo is unknown. We found that forced swim (FS) stress evoked increased hippocampal RNA expression levels of the glucocorticoid-responsive genes FK506-binding protein 5 (Fkbp5), Period 1 (Per1), and serum- and glucocorticoid-inducible kinase 1 (Sgk1). Chromatin immunoprecipitation (ChIP) analysis showed that this stressor caused substantial gene-dependent increases in GR binding and surprisingly, also MR binding to GREs within these genes. Different acute challenges, including novelty, restraint, and FS stress, produced distinct glucocorticoid responses but resulted in largely similar MR and GR binding to GREs. Sequential and tandem ChIP analyses showed that, after FS stress, MRs and GRs bind concomitantly to the same GRE sites within Fkbp5 and Per1 but not Sgk1. Thus, after stress, MRs and GRs seem to bind to GREs as homo- and/or heterodimers in a gene-dependent manner. MR binding to GREs at baseline seems to be restricted, whereas after stress, GR binding may facilitate cobinding of MR. This study reveals that the interaction of MRs and GRs with GREs within the genome constitutes an additional level of complexity in hippocampal glucocorticoid action beyond expectancies based on ligand–receptor interactions

    Computing procedures for a learning machine

    Get PDF

    Π€Π΅Π½ΠΎΠΌΠ΅Π½ ΠΌΠ΅ΠΌΠ° Π² Ρ†ΠΈΡ„Ρ€ΠΎΠ²ΠΎΠΌ общСствС ΠΊΠ°ΠΊ ΠΏΡ€Π΅Π΄ΠΌΠ΅Ρ‚ осмыслСния: ΡΠΎΡ†ΠΈΠ°Π»ΡŒΠ½ΠΎ-философский Π°Π½Π°Π»ΠΈΠ·

    Get PDF
    Π“Π»ΠΎΠ±Π°Π»ΡŒΠ½Π°Ρ трансформация Ρ†ΠΈΡ„Ρ€ΠΎΠ²ΠΎΠ³ΠΎ общСства сопровоТдаСтся Π½Π΅ Ρ‚ΠΎΠ»ΡŒΠΊΠΎ ΠΏΡ€ΠΎΠ½ΠΈΠΊΠ½ΠΎΠ²Π΅Π½ΠΈΠ΅ΠΌ ΠΈΠ½Ρ‚Π΅Ρ€Π½Π΅Ρ‚-ΠΊΠΎΠΌΠΌΡƒΠ½ΠΈΠΊΠ°Ρ†ΠΈΠΈ Π²ΠΎ всС сфСры ΠΆΠΈΠ·Π½Π΅Π΄Π΅ΡΡ‚Π΅Π»ΡŒΠ½ΠΎΡΡ‚ΠΈ общСства, Π½ΠΎ ΠΈ Π³Π»ΡƒΠ±ΠΎΠΊΠΈΠΌ пСрСосмыслСниСм ΠΊΠΎΠΌΠΌΡƒΠ½ΠΈΠΊΠ°Ρ‚ΠΈΠ²Π½ΠΎΠΉ ΠΏΡ€ΠΈΡ€ΠΎΠ΄Ρ‹ ΡΠΎΡ†ΠΈΠ°Π»ΡŒΠ½ΠΎΠΉ Ρ€Π΅Π°Π»ΡŒΠ½ΠΎΡΡ‚ΠΈ. ΠšΠΎΠΌΠΌΡƒΠ½ΠΈΠΊΠ°Ρ†ΠΈΠΈ сСгодня - это ΠΎΠ±Ρ‰ΠΈΠΉ ΠΌΠΈΡ€ Π·Π½Π°Ρ‡ΠΈΠΌΡ‹Ρ… ΠΎΠ±ΡŠΠ΅ΠΊΡ‚ΠΎΠ² ΠΈ событий, наши чувства ΠΈ мысли, наши способы выраТСния этих ΡΠΎΡ†ΠΈΠ°Π»ΡŒΠ½ΠΎ выстраиваСмых Ρ€Π΅Π°Π»ΡŒΠ½ΠΎΡΡ‚Π΅ΠΉ Ρ„ΠΎΡ€ΠΌΠΈΡ€ΡƒΡŽΡ‚ ΠΊΠΎΠΌΠΌΡƒΠ½ΠΈΠΊΠ°Ρ‚ΠΈΠ²Π½ΠΎΠ΅ пространство.The global transformation of the digital society is accompanied not only by the penetration of Internet communication into all spheres of society, but also by a deep rethinking of the communicative nature of social reality. Communication today is a common world of significant objects and events, our feelings and thoughts, our ways of expressing these socially constructed realities form a communicative space

    Detection of the maximum resistance to the herbicides diuron and glyphosate, and evaluation of its phenotypic cost, in freshwater phytoplankton

    Get PDF
    One of the most important anthropogenic impacts on freshwater aquatic ecosystems close to intensive agriculture areas is the cumulative increase in herbicide concentrations. The threat is especially relevant for phytoplankton organisms because they have the same physiological targets as the plants for which herbicides have been designed. This led us to explore the evolutionary response of three phytoplanktonic species to increasing concentrations of two herbicides and its consequences in terms of growth and photosynthesis performance. Specifically, we used an experimental ratchet protocol to investigate the differential evolution and the limit of resistance of a cyanobacterium (Microcystis aeruginosa) and two chlorophyceans (Chlamydomonas reinhardtii and Dictyosphaerium chlorelloides) to two herbicides in worldwide use: glyphosate and diuron. Initially, the growth rate of M. aeruginosa and D. chlorelloides was completely inhibited when they were exposed to a dose of 0.23 ppm diuron or 40 ppm glyphosate, whereas a higher concentration of both herbicides (0.46 ppm diuron or 90 ppm glyphosate) was necessary to abolish C. reinhardtii growth. However, after running a ratchet protocol, the resistance of the three species to both herbicides increased by an adaptation process. M. aeruginosa and D. chlorelloides were able to grow at 1.84 ppm diuron and 80 ppm glyphosate and C. reinhardtii proliferated at twice these concentrations. Herbicide-resistant strains showed lower growth rates than their wild-type coun- terparts in the absence of herbicides, as well as changes on morphology and differences on photosynthetic pigment content. Besides, herbicide-resistant cells generally showed a lower photosynthetic performance than wild-type strains in the three species. These results indicate that the introduction of both herbicides in freshwater ecosystems could produce a diminution of primary production due to the selection of herbicide-resistant mutants, that would exhibit ...This work was financially supported by the project CGL2017-87314- P (Ministerio de Economía, Industria y Competitividad, Spain). The acquisition of the FlowCAM by the University of MÑlaga was co-financed by the 2008-2011 FEDER program for scientific-technique infrastructure (Proposal number: UNMA08-1E005). Funding for open access charge: Universidad de MÑlaga/CBUA

    Аналіз Π½Π°ΠΏΡ€ΡƒΠΆΠ΅Π½ΠΎ-Π΄Π΅Ρ„ΠΎΡ€ΠΌΠΎΠ²Π°Π½ΠΎΠ³ΠΎ стану стійки дискової Π±ΠΎΡ€ΠΎΠ½ΠΈ

    Get PDF
    • …
    corecore