618 research outputs found

    Dynamic behavior of stochastic gene expression models in the presence of bursting

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    This paper considers the behavior of discrete and continuous mathematical models for gene expression in the presence of transcriptional/translational bursting. We treat this problem in generality with respect to the distribution of the burst size as well as the frequency of bursting, and our results are applicable to both inducible and repressible expression patterns in prokaryotes and eukaryotes. We have given numerous examples of the applicability of our results, especially in the experimentally observed situation that burst size is geometrically or exponentially distributed.Comment: 22 page

    Postęp w technologii wytwarzania materiałów stykowych na bazie srebra ze szczególnym uwzględnieniem kmpozytów Ag-Re i Ag-SnO2Bi2O3

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    The paper outlines technologies currently used for the production of the Ag-Re10 and Ag-SnO2Bi2O3 contact materials in a form of wires and solid and bimetallic rivets. Their characteristic parameters, including physical and mechanical properties and microstructure, are given. It has been found that the level of these parameters, particularly electrical properties (resistance to electric arc erosion), is unsatisfactory considering the present requirements, which applies mainly to the new Ag-Re10 [wt%] alloy, so far not fully technologically mastered. Therefore, under this work a new method for the production of this type of materials has been designed and the related research works were undertaken. The new-generation contact materials in a form of nanostructured composites will be characterised by similar chemical compositions as those specified above but with increased functional properties, including enhanced resistance to arc erosion. In this paper preliminary results of the examination of structure and properties of semi-products obtained by new technology based on powder metallurgy techniques are presented. Conditions for pressure consolidation and plastic consolidation applied for material processing into wires and rivets (solid and bimetallic) have been determined.W referacie przedstawiono stosowany aktualnie zarys technologii wytwarzania materiałów stykowych Ag-Re10 i Ag-SnO2Bi2O3 w postaci drutów oraz nitów litych i bimetalowych i jednocześnie podano ich charakterystyczne parametry obejmujące właściwości fizyko-mechaniczne i mikrostrukture. Stwierdzono, że poziom uzyskiwanych właściwości-szczególnie elektrycznych (odporność na erozje łuku elektrycznego) jest niezadawalający w świetle aktualnych wymagań, co dotyczy głównie nowego jeszcze nie w pełni opanowanego technologicznie materiału Ag-Re10%wag. Zaprojektowano wiec nowy sposób wytwarzania tego typu materiałów i podjęto prace badawczo rozwojowe w tym zakresie. Ich celem jest opracowanie sposobu wytwarzania nowej generacji materiałów stykowych w postaci kompozytów o podobnym składzie chemicznym jednakże charakteryzujących się nanostruktura i znacznie wyższymi parametrami – głównie odpornością na działanie łuku elektrycznego. Przedstawiono wstępne wyniki badań obejmujące syntezę mechaniczna oraz określono warunki konsolidacji odkształceniowej i plastycznej w procesie ich przeróbki na druty i nity lite i bimetalowe, bazując na procesach z obszaru metalurgii proszków

    Immunohistochemical evidence of the co-localisation of cocaine and amphetamine regulatory peptide with neuronal isoform of nitric oxide synthase, vasoactive intestinal peptide and galanin within the circular muscle layer of the human caecum

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    The enteric nervous system consists of about one hundred million of neurons. In big mammals (including humans) intestinal enteric neuronal cells are grouped into three types of intramural ganglia located within myenteric, as well as outer and inner submucosal plexuses, which are connected by numerous nerve fibres. Both nerve fibres and cell bodies located in the gastrointestinal tract utilise a broad spectrum of active substances. One of them is cocaine- and amphetamine-regulated transcript peptide (CART). The goal of the current study was to determinate the distribution and degree of co-localisation of CART with substances taking part in intestinal motor activity by double labelling immunofluorescence technique. During the study CART-, neuronal isoform of nitric oxide synthase (nNOS)-, vasoactive intestinal peptide (VIP)- and/or galanin (GAL) — like immunoreactive (LI) nerve fibres in the circular muscle layer of the human caecum were observed in all patients studied. The degree of co-localisation of particular substances with CART depended on their type. The majority of CART-LI fibres contained simultaneously nNOS, slightly lower degree of co-localisation was observed in the case of the VIP, while simultaneously CART- and GAL-positive nerve fibres were observed less often

    Exploring the Synergies of Single‐Molecule Fluorescence and 2D Materials Coupled by DNA

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    The world of 2D materials is steadily growing, with numerous researchers attempting to discover, elucidate, and exploit their properties. Approaches relying on the detection of single fluorescent molecules offer a set of advantages, for instance, high sensitivity and specificity, that allow the drawing of conclusions with unprecedented precision. Herein, it is argued how the study of 2D materials benefits from fluorescence-based single-molecule modalities, and vice versa. A special focus is placed on DNA, serving as a versatile adaptor when anchoring single dye molecules to 2D materials. The existing literature on the fruitful combination of the two fields is reviewed, and an outlook on the additional synergies that can be created between them provided
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