Instabilities in charged tori

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2021, Tutor: Alberto Fernández-NievesThis report aims to shed light on the different instability regimes of charged toroidal droplets. Firstly, we have studied the shrinkage and breakup of neutral tori through Rayleigh-Plateau instabilities. When charged, electrical stresses can overcome surface tension stresses leading to droplet expansion. At even higher voltage, tori can develop Saffman-Taylor instabilities, which result in viscous fingering. Remarkably, at high enough potential, these viscous fingering branch out, giving rise to a magnificent dendritic-growth behaviou

The backbone of the post-synaptic density originated in a unicellular ancestor of choanoflagellates and metazoans

<p>Abstract</p> <p>Background</p> <p>Comparative genomics of the early diverging metazoan lineages and of their unicellular sister-groups opens new window to reconstructing the genetic changes which preceded or accompanied the evolution of multicellular body plans. A recent analysis found that the genome of the nerve-less sponges encodes the homologues of most vertebrate post-synaptic proteins. In vertebrate excitatory synapses, these proteins assemble to form the post-synaptic density, a complex molecular platform linking membrane receptors, components of their signalling pathways, and the cytoskeleton. Newly available genomes from <it>Monosiga brevicollis </it>(a member of Choanoflagellata, the closest unicellular relatives of animals) and <it>Trichoplax adhaerens </it>(a member of Placozoa: besides sponges, the only nerve-less metazoans) offer an opportunity to refine our understanding of post-synaptic protein evolution.</p> <p>Results</p> <p>Searches for orthologous proteins and reconstruction of gene gains/losses based on the taxon phylogeny indicate that post-synaptic proteins originated in two main steps. The backbone scaffold proteins (Shank, Homer, DLG) and some of their partners were acquired in a unicellular ancestor of choanoflagellates and metazoans. A substantial additional set appeared in an exclusive ancestor of the Metazoa. The placozoan genome contains most post-synaptic genes but lacks some of them. Notably, the master-scaffold protein Shank might have been lost secondarily in the placozoan lineage.</p> <p>Conclusions</p> <p>The time of origination of most post-synaptic proteins was not concomitant with the acquisition of synapses or neural-like cells. The backbone of the scaffold emerged in a unicellular context and was probably not involved in cell-cell communication. Based on the reconstructed protein composition and potential interactions, its ancestral function could have been to link calcium signalling and cytoskeleton regulation. The complex later became integrated into the evolving synapse through the addition of novel functionalities.</p

L’art xinès dels anys 90 en el context internacional .El cas del Pop Polític i el Realisme Cínic

Treballs Finals de Grau d'Història de l'Art, Facultat de Geografia i Història, Universitat de Barcelona, Curs: 2020-2021, Tutor: Anna Mª Guasch FerrerL’art xinès dels anys 90, el cas del Pop Polític i el Realisme Cínic, neix amb la voluntat de donar una visió del transcurs de l’art contemporani xinès entre la dècada dels 80 i la dècada dels 90 posant èmfasi en els moviments del Pop Polític i el Realisme Cínic. En aquest sentit, posarem de manifest aquells esdeveniments més rellevants que es produïren en el context del desenvolupament del Pop Polític i el Realisme Cínic que actuaren com a contraposició de les pràctiques artístiques anteriors, amb una estètica particular i en molts aspectes innovadora. En recull de tot això, constatarem de quina manera va entrar en circulació aquest art dins el sistema internacional i sota quins paràmetres de valoració es va justificar, tant des del punt de vista dels propis xinesos com des del punt de vista dels occidentals, ambdós amb un llegat social, polític, cultural i artístic molt divers que obrí la porta a un seguit d’interpretacions i valoracions, en molts casos contradictòries. Partint d'aquesta base, i per entendre de quina manera l’art xinès dels 90 va traspassar les fronteres nacionals per fer-se un lloc en el marc occidental de l'art, es voldrà posar en rellevància aquelles exposicions més destacades que durant la mateixa dècada se celebraren a occident i que incorporaren per primera vegada mostres d'art xinès contemporani

Conserved expression of vertebrate microvillar gene homologs in choanocytes of freshwater sponges

International audienceBackground: The microvillus is a versatile organelle that serves important functions in disparate animal cell types. However, from a molecular perspective, the microvillus has been well studied in only a few, predominantly vertebrate, contexts. Little is known about how differences in microvillar structure contribute to differences in function, and how these differences evolved. We sequenced the transcriptome of the freshwater sponge, Ephydatia muelleri, and examined the expression of vertebrate microvillar gene homologs in choanocytes—the only microvilli-bearing cell type present in sponges. Sponges offer a distant phylogenetic comparison with vertebrates, and choanocytes are central to discussions about early animal evolution due to their similarity with choanoflagellates, the single-celled sister line-age of modern animals. Results: We found that, from a genomic perspective, sponges have conserved homologs of most vertebrate microvillar genes, most of which are expressed in choanocytes, and many of which exhibit choanocyte-specific or choanocyte-enriched expression. Possible exceptions include the cadherins that form intermicrovillar links in the enterocyte brush border and hair cell stereocilia of vertebrates and cnidarians. No obvious orthologs of these proteins were detected in sponges, but at least four candidate cadherins were identified as choanocyte-enriched and might serve this function. In contrast to the evidence for conserved microvillar structure in sponges and vertebrates, we found that choanoflagellates and ctenophores lack homologs of many fundamental microvillar genes, suggesting that microvillar structure may diverge significantly in these lineages, warranting further study. Conclusions: The available evidence suggests that microvilli evolved early in the prehistory of modern animals and have been repurposed to serve myriad functions in different cellular contexts. Detailed understanding of the sequence by which different microvilli-bearing cell/tissue types diversified will require further study of microvillar composition and development in disparate cell types and lineages. Of particular interest are the microvilli of choano-flagellates, ctenophores, and sponges, which collectively bracket the earliest events in animal evolution

Zinc oxide doped with copper and nitrogen exhibits photocatalytic antibacterial activity under light from common fluorescent tubes

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Diagnóstico de un sistema de producción ganadero y evaluación de las respuestas a las recomendaciones de la extensión rural

This research is aimed at evaluating a cattle production system through a joint diagnosis as a way of encouraging a closer link between rural extension and the farmers living on a farm located to the west of Camagüey city, Cuba. To this end, an opinion interchange with the farm producers about their decision on land management and the impact of such decisions was conducted. Besides, the farm bioeconomic and environmental results were analyzed, and interviews to producers were applied not only to evaluate the changes in physical and bioeconomic indexes, but also to assess their relationship to a credit-and-service cooperative collective venture. The integration of the rural extension to the farm with better results as to production and income levels was achieved.El objetivo del trabajo fue evaluar un sistema ganadero diagnosticado en forma participativa y propiciar un estrecho vínculo entre acciones de extensión rural y las familias campesinas de una finca ubicada en la zona oeste de la ciudad de Camagüey, Cuba. En la primera etapa se dialogó con los productores sobre sus decisiones y sus efectos; también se evaluaron los resultados bioeconómicos y ambientales de la finca. Se realizaron encuestas para evaluar los cambios en los índices físicos y bioeconómicos en tiempo y cómo los productores se relacionaban con la cooperativa de crédito y servicios. Con la investigación se logró integrar la extensión rural y la finca, vinculación que posibilitó niveles satisfactorios de producción e ingresos

Evolutionary origin of synapses and neurons – Bridging the gap

The evolutionary origin of synapses and neurons is an enigmatic subject that inspires much debate. Non-bilaterian metazoans, both with and without neurons and their closest relatives already contain many components of the molecular toolkits for synapse functions. The origin of these components and their assembly into ancient synaptic signaling machineries are particularly important in light of recent findings on the phylogeny of non-bilaterian metazoans. The evolution of synapses and neurons are often discussed only from a metazoan perspective leaving a considerable gap in our understanding. By taking an integrative approach we highlight the need to consider different, but extremely relevant phyla and to include the closest unicellular relatives of metazoans, the ichthyosporeans, filastereans and choanoflagellates, to fully understand the evolutionary origin of synapses and neurons. This approach allows for a detailed understanding of when and how the first pre- and postsynaptic signaling machineries evolved

Evolutionary origin of synapses and neurons - Bridging the gap

The evolutionary origin of synapses and neurons is an enigmatic subject that inspires much debate. Non-bilaterian metazoans, both with and without neurons and their closest relatives already contain many components of the molecular toolkits for synapse functions. The origin of these components and their assembly into ancient synaptic signaling machineries are particularly important in light of recent findings on the phylogeny of non-bilaterian metazoans. The evolution of synapses and neurons are often discussed only from a metazoan perspective leaving a considerable gap in our understanding. By taking an integrative approach we highlight the need to consider different, but extremely relevant phyla and to include the closest unicellular relatives of metazoans, the ichthyosporeans, filastereans and choanoflagellates, to fully understand the evolutionary origin of synapses and neurons. This approach allows for a detailed understanding of when and how the first pre- and postsynaptic signaling machineries evolved