81 research outputs found
Why doesn’t the telephone ring? : Reform of educational standards in Russia
The article engages with the ongoing debate about the global/local dynamics in the process of neoliberal educational reform by exploring public perception of the neoliberal idea of 'educational standardisation' in post-Soviet Russia. Using a variety of discursive and textual analysis techniques, the article analyses the presentation of the concept in the official government discourse, benchmarking it against nationally-grounded pedagogical concerns and aspirations. It contrasts the interpretative schemes underlying neoliberal, official and local interpretations of educational standards and exposes points of tension surrounding the concept at the linguistic, metaphorical and conceptual levels. It show how despite sharing the terminology the public and the official discourses are not ‘talking about the same thing,’ generating widespread confusion at grassroots level and obscuring the direction of reform. I further deconstruct logic for popular resistance to the concept of educational standard by uncovering cultural metaphors underlying negative interpretations of ‘standardisation’. I conclude by problematising the mediating role of the Russian government in translating new educational values into the Russian culture code, highlighting the importance of educational policy as a socially interpreted phenomenon and calling for a further conceptualisation of the cultural variable in contemporary theory of educational change.Peer reviewe
Studying synthesis confinement effects on the internal structure of nanogels in computer simulations
We study the effects of droplet finite size on the structure of nanogel
particles synthesized by random crosslinking of molecular polymers diluted in
nanoemulsions. For this, we use a bead-spring computer model of polymer-like
structures that mimics the confined random crosslinking process corresponding
to irradiation- or electrochemically-induced crosslinking methods. Our results
indicate that random crosslinking under strong confinement can lead to unusual
nanogel internal structures, with a central region less dense than the external
one, whereas under moderate confinement the resulting structure has a denser
central region. We analyze the topology of the polymer networks forming nanogel
particles with both types of architectures, their overall structural
parameters, their response to the quality of the solvent and compare the cases
of non-ionic and ionic systems
Geologists of Russian origin in Latin America
Se describe la vida y trayectoria de geólogos que más allá de su nacionalidad (rusa, ucraniana, tártara, alemana, etc.), nacieron en territorios que pertenecieron al Imperio Ruso, la Unión Soviética o la Federación Rusa, y de sus descendientes graduados en geología, todos los cuales vivieron y trabajaron en países de Latinoamérica (en los cuales las lenguas que prevalecen son el español y el portugués). También se incluyen geólogos de la URSS que trabajaron temporariamente en algunos países de Latinoamérica y que con sus publicaciones contribuyeron a la Geología.We describe here the life and career of geologists who beyond their nationality(Russian, Ukrainian, Tatar, German, etc.), were born on the territory of the Russian Empire, the SovietUnion or the Russian Federation and their descendants that became geologists, all of whom lived andworked in Latin-American countries (where Spanish and Portuguese languages prevail). We includealso geologists from USSR who worked temporary in some countries of Latin America and leftcontributions to geology in form of publications.Fil: Tchoumatchenco, Platon. Bulgarian Academy Of Sciences; BulgariaFil: Riccardi, Alberto Carlos. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Durand Delga, Michel. Centre National de la Recherche Scientifique; FranciaFil: Alonso, Ricardo. Universidad Nacional de Salta; ArgentinaFil: Wiasemsky, Michel. Centre National de la Recherche Scientifique; FranciaFil: Boltovskoy, Demetrio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Charrier González, Reynaldo. Sociedad Geologica de Chile; ChileFil: Minina, Elena. State Geological Museum “V.I.Vernadsky”; Rusi
Suspensions of magnetic nanogels at zero field: equilibrium structural properties
Magnetic nanogels represent a cutting edge of magnetic soft matter research
due to their numerous potential applications. Here, using Langevin dynamics
simulations, we analyse the influence of magnetic nanogel concentration and
embedded magnetic particle interactions on the self-assembly of magnetic
nanogels at zero field. For this, we calculated radial distribution functions
and structure factors for nanogels and magnetic particles within them. We found
that, in comparison to suspensions of free magnetic nanoparticles, where the
self-assembly is already observed if the interparticle interaction strength
exceeds the thermal fluctuations by approximately a factor of three,
self-assembly of magnetic nanogels only takes place by increasing such ratio
above six. This magnetic nanogel self-assembly is realised by means of
favourable close contacts between magnetic nanoparticles from different
nanogels. It turns out that for high values of interparticle interactions,
corresponding to the formation of internal rings in isolated nanogels, in their
suspensions larger magnetic particle clusters with lower elastic penalty can be
formed by involving different nanogels. Finally, we show that when the
self-assembly of these nanogels takes place, it has a drastic effect on the
structural properties even if the volume fraction of magnetic nanoparticles is
low.Comment: International Conference on Magnetic Fluids - ICMF 201
Apoptosis is not conserved in plants as revealed by critical examination of a model for plant apoptosis-like cell death
Background: Animals and plants diverged over one billion years ago and evolved unique mechanisms for many cellular processes, including cell death. One of the most well-studied cell death programmes in animals, apoptosis, involves gradual cell dismantling and engulfment of cellular fragments, apoptotic bodies, through phagocytosis. However, rigid cell walls prevent plant cell fragmentation and thus apoptosis is not applicable for executing cell death in plants. Furthermore, plants are devoid of the key components of apoptotic machinery, including phagocytosis as well as caspases and Bcl-2 family proteins. Nevertheless, the concept of plant "apoptosis-like programmed cell death" (AL-PCD) is widespread. This is largely due to superficial morphological resemblances between plant cell death and apoptosis, and in particular between protoplast shrinkage in plant cells killed by various stimuli and animal cell volume decrease preceding fragmentation into apoptotic bodies.Results: Here, we provide a comprehensive spatio-temporal analysis of cytological and biochemical events occurring in plant cells subjected to heat shock at 40-55 degrees C and 85 degrees C, the experimental conditions typically used to trigger AL-PCD and necrotic cell death, respectively. We show that cell death under both conditions was not accompanied by membrane blebbing or formation of apoptotic bodies, as would be expected during apoptosis. Instead, we observed instant and irreversible permeabilization of the plasma membrane and ATP depletion. These processes did not depend on mitochondrial functionality or the presence of Ca2+ and could not be prevented by an inhibitor of ferroptosis. We further reveal that the lack of protoplast shrinkage at 85 degrees C, the only striking morphological difference between cell deaths induced by 40-55 degrees C or 85 degrees C heat shock, is a consequence of the fixative effect of the high temperature on intracellular contents.Conclusions: We conclude that heat shock-induced cell death is an energy-independent process best matching definition of necrosis. Although the initial steps of this necrotic cell death could be genetically regulated, classifying it as apoptosis or AL-PCD is a terminological misnomer. Our work supports the viewpoint that apoptosis is not conserved across animal and plant kingdoms and demonstrates the importance of focusing on plant-specific aspects of cell death pathways
Structure factor of model bidisperse ferrofluids with relatively weak interparticle interactions
In the present manuscript we develop a theoretical approach to describe the pair correlation function of bidisperse magnetic dipolar hard- and soft-spheres. We choose bidisperse system as the first step to allow for polydispersity when studying thermodynamics of magnetic fluids. Using diagram technique we calculate the virial expansion of the pair correlation function up to the first order in density and fourth order in the dipolar strength. Even though, the radial distribution functions are extremely sensitive to the steric potential, we show that the behaviour of the isotropic centre-centre structure factor is almost indifferent to the type of the short-range repulsion. We extensively compare our theoretical results to the data of molecular dynamics simulations, which helps us to understand the range of validity of the virial expansion both on density and magnetic dipolar strength. We also investigate the influence of the granulometric composition on the height, width, and position of the structure factor first peak in order to clarify whether it is possible to extract structural information from experimentally measured small angle neutron scattering intensities. © 2013 AIP Publishing LLC
Compressibility of ferrofluids: Towards a better understanding of structural properties
Abscisic acid signaling activates distinct VND transcription factors to promote xylem differentiation in Arabidopsis
Plants display remarkable abilities to adjust growth and development to environmental conditions, such as the amount of available water. This developmental plasticity is apparent not only in root and shoot growth rates, but also in tissue patterning and cell morphology.(1,2) We have previously shown that in response to limited water availability, Arabidopsis thaliana root displays changes in xylem morphology, mediated by the non-cell-autonomous action of abscisic acid, ABA.(2) Here, we show, through analyses of ABA response reporters and tissue-specific suppression of ABA signaling, that xylem cells themselves act as primary signaling centers governing both xylemcell fate and xylem differentiation rate, revealing the cell-autonomous control of multiple aspects of xylem development by ABA. ABA rapidly activates the expression of genes encoding VASCULAR-RELATED NAC DOMAIN (VND) transcription factors. Molecular and genetic analyses revealed that the two ABA-mediated xylem developmental changes are regulated by distinct members of this transcription factor family, with VND2 and VND3 promoting differentiation rate of metaxylem cells, while VND7 promotes the conversion of metaxylem toward protoxylem morphology. This phenomenon shows how different aspects of developmental plasticity can be interlinked, yet genetically separable. Moreover, similarities in phenotypic and molecular responses to ABA in diverse species indicate evolutionary conservation of the ABA-xylem development regulatory network among eudicots. Hence, this study gives molecular insights into how environmental stress modifies plant vascular anatomy and has potential relevance for water use optimization and adaptation to drought conditions
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