1,772 research outputs found

    PyMembrane: A flexible framework for efficient simulations of elastic and liquid membranes

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    PyMembrane is a software package for simulating liquid and elastic membranes using a discretisation of the continuum description based on unstructured triangulated two-dimensional meshes embedded in three-dimensional space. The package is written in C++, with a flexible and intuitive Python interface, allowing for a quick setup, execution and analysis of complex simulations. PyMembrane follows modern software engineering principles and features a modular design that allows for straightforward implementation of custom extensions while ensuring consistency and enabling inexpensive maintenance. A hallmark feature of this design is the use of a standardized C++ interface which streamlines adding new functionalities. Furthermore, PyMembrane uses data structures optimised for unstructured meshes, ensuring efficient mesh operations and force calculations. By providing several templates for typical simulations supplemented by extensive documentation, the users can seamlessly set up and run research-level simulations and extend the package to integrate additional features, underscoring PyMembrane's commitment to user-centric design.Comment: 7 Figure

    Хромосомы и видообразование у туко-туко (Ctenomys, Hystricognathi, Rodentia)

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    Tuco-tucos, South American rodents of the genus Ctenomys represent an interesting model of speciation. Their strict territorial and solitary life under the earth, vast but highly fragmented habitats, low migration activity were the causes of their very fast radiation. About 60 species of this genus have been described. They are found in a variety of habitats, from the mountains of the Andes to the coastal dunes of the Atlantic, from humid steppes of Pampas to dry deserts of Chaco. Tuco-tucos have a very high level of chromosomal polymorphism and polytypism based on Robertsonian and whole-arm reciprocal translocations and inversions, and can therefore be used to test different versions of chromosomal speciation hypothesis. The classic version of this hypothesis emphasizes the sterility of the hybrids, due to incorrect or incomplete chromosome synapsis in heterozygotes for rearrangements, germ cells death, chromosome nondisjunction and the generation of unbalanced gametes. The modern version of chromosomal speciation hypothesis suggests that the reduction of gene flow across chromosomal hybrid zones is due to the suppression of recombination in hybrids around the break points of rearrangements distinguishing the parental species. Field studies have not revealed strong negative effects of chromosomal heterozygosity on the fitness of the carriers. These results cast doubt on the validity of the classic version of the hypothesis. Analysis of chromosome behavior in the meiotic prophase in the chromosomal heterozygotes revealed significant changes in the frequency and distribution of recombination: crossingover suppression around the breakpoint and chiasma distalization. These changes can modulate the flow of genes between chromosomal races and amplify the divergence which has arisen due to spatial isolation. These data confirm the recombinational model of chromosomal speciation.Fil: Torgasheva, Anna A.. Novosibirsk State University; Rusia. Institute of Cytology and Genetics; RusiaFil: Savchenko, Ekaterina. Institute of Cytology and Genetics; RusiaFil: Gomez Fernandez, Maria Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Mirol, Patricia Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Borodin, Pavel M.. Novosibirsk State University; Rusia. Institute of Cytology and Genetics; Rusi

    A survey of freshwater gastropods in the Microrregião Serrana of the State of Rio de Janeiro, Brazil

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    In 1984 we received samples of freshwater gastropods from many localities of the State of Rio de Janeiro, sent by Fundação Nacional de Saúde for identification. In the past three years, aiming to elaborate a chart of planorbids of the State of Rio de Janeiro additional collecting was done by the authors in the area corresponding to the Microrregião Serrana of the state: Petrópolis, Teresópolis and São José do Vale do Rio Preto. The survey was extended to the neighbour towns, Guapimirim and Magé, in order to improve the knowledge of that poorly studied area

    A Plasmodium promiscuous T cell epitope delivered within the Ad5 hexon protein enhances the protective efficacy of a protein based malaria vaccine

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    A malaria vaccine is a public health priority. In order to produce an effective vaccine, a multistage approach targeting both the blood and the liver stage infection is desirable. The vaccine candidates also need to induce balanced immune responses including antibodies, CD4+ and CD8+ T cells. Protein-based subunit vaccines like RTS,S are able to induce strong antibody response but poor cellular reactivity. Adenoviral vectors have been effective inducing protective CD8+ T cell responses in several models including malaria; nonetheless this vaccine platform exhibits a limited induction of humoral immune responses. Two approaches have been used to improve the humoral immunogenicity of recombinant adenovirus vectors, the use of heterologous prime-boost regimens with recombinant proteins or the genetic modification of the hypervariable regions (HVR) of the capsid protein hexon to express B cell epitopes of interest. In this study, we describe the development of capsid modified Ad5 vectors that express a promiscuous Plasmodium yoelii T helper epitope denominated PyT53 within the hexon HVR2 region. Several regimens were tested in mice to determine the relevance of the hexon modification in enhancing protective immune responses induced by the previously described protein-based multi-stage experimental vaccine PyCMP. A heterologous prime-boost immunization regime that combines a hexon modified vector with transgenic expression of PyCMP followed by protein immunizations resulted in the induction of robust antibody and cellular immune responses in comparison to a similar regimen that includes a vector with unmodified hexon. These differences in immunogenicity translated into a better protective efficacy against both the hepatic and red blood cell stages of P. yoelii. To our knowledge, this is the first time that a hexon modification is used to deliver a promiscuous T cell epitope. Our data support the use of such modification to enhance the immunogenicity and protective efficacy of adenoviral based malaria vaccines

    Determining the Impact of Government Intervention on Firm Decisions for Sustainable Production

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    We use a game theoretic approach to assess how the government can influence firms’ corporate social responsibility (CSR) investment and production decisions to enhance social welfare, considering the negative externalities of unsustainable production and positive externalities from CSR investments. Using a Stackelberg duopoly as a base model and lump-sum tax as the government’s decision variable, we find that when the government chooses not to intervene, it results in greater environmental damage as firms will underinvest in CSR and overproduce in quantity to achieve profit maximization. As such, the model extends to the assumption that the government acts as a benevolent dictator to model how firms will act under a regulated environment to achieve the optimal outcome. Ultimately, we show that firms have to be placed under a regulated environment to prevent them from exploiting resources and damaging the environment, thereby negatively affecting societal welfare

    A Game Theoretic Study on CSR and Government Intervention for Sustainable Production

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    We use a game theoretic approach to assess how the government can influence firms’ CSR investment and production decisions to enhance social welfare, considering the negative externalities brought by unsustainable production and positive externalities brought by CSR investments. Using a Stackelberg duopoly as a base model and lump-sum tax as the government’s decision variable, we find that when the government chooses not to intervene, it results in greater environmental damage as firms will underinvest in CSR and overproduce in quantity to achieve profit maximization. As such, the model extends to the assumption that the government acts as a benevolent dictator to model how firms will act under a regulated environment to achieve the Pareto optimal outcome. Ultimately, we show that firms have to be placed under a regulated environment to prevent them from exploiting resources and damaging the environment, thereby negatively affecting societal welfare
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