675 research outputs found

    An environment for object-oriented real-time system design

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    A concise object-oriented method for the development of real-time systems has been composed. Hardware components are modelled by (software) base objects; base objects are controlled by a hierarchy of coordinator objects, expressed in an organizational diagram. The behaviour of objects is specified by state transition diagrams. This approach considerably promotes requirements analysis and communication with the customer. A CASE tool has been constructed with diagram editors for graphical specifications of real-time systems. The tool can generate executable code for PLCs from these graphical specifications; reuse of previous results is supported by the repository function of the tool. Experiences attained in practice with method and tool show that time spent in system testing and installation is reduced considerabl

    Identification and mapping of the novel apple scab resistance gene Vd3

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    Apple scab, caused by the fungal pathogen Venturia inaequalis, is one of the most devastating diseases for the apple growing in temperate zones with humid springs and summers. Breeding programs around the world have been able to identify several sources of resistance, the Vf from Malus floribunda 821 being the most frequently used. The appearance of two new races of V. inaequalis (races 6 and 7) in several European countries that are able to overcome the resistance of the Vf gene put in evidence the necessity of the combination of different resistance genes in the same genotype (pyramiding). Here, we report the identification and mapping of a new apple scab resistance gene (Vd3) from the resistant selection “1980-015-25” of the apple breeding program at Plant Research International, The Netherlands. This selection contains also the Vf gene and the novel V25 gene for apple scab resistance. We mapped Vd3 on linkage group 1, 1 cM to the south of Vf in repulsion phase to it. Based on pedigree analysis and resistance tests, it could be deduced that 1980-015-25 had inherited Vd3 from the founder “D3.” This gene provides resistance to the highly virulent EU-NL-24 strain of race 7 of V. inaequalis capable of overcoming the resistance from Vf and Vg

    Computational methods reveal novel functionalities of PIWI-interacting RNAs in human papillomavirus-induced head and neck squamous cell carcinoma.

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    Human papillomavirus (HPV) infection is the fastest growing cause of head and neck squamous cell carcinoma (HNSCC) today, but its role in malignant transformation remains unclear. This study aimed to conduct a comprehensive investigation of PIWI-interacting RNA (piRNA) alterations and functionalities in HPV-induced HNSCC. Using 77 RNA-sequencing datasets from TCGA, we examined differential expression of piRNAs between HPV16(+) HNSCC and HPV(-) Normal samples, identifying a panel of 30 HPV-dysregulated piRNAs. We then computationally investigated the potential mechanistic significances of these transcripts in HPV-induced HNSCC, identifying our panel of piRNAs to associate with the protein PIWIL4 as well as the RTL family of retrotransposon-like genes, possibly through direct binding interactions. We also recognized several HPV-dysregulated transcripts for their correlations with well-documented mutations and copy number variations in HNSCC as well as HNSCC clinical variables, demonstrating the potential ability of our piRNAs to play important roles in large-scale modulation of HNSCC in addition to their direct, smaller-scale interactions in this malignancy. The differential expression of key piRNAs, including NONHSAT077364, NONHSAT102574, and NONHSAT128479, was verified in vitro by evaluating endogenous expression in HPV(+) cancer vs. HPV(-) normal cell lines. Overall, our novel study provides a rigorous investigation of piRNA dysregulation in HPV-related HNSCC, and lends critical insight into the idea that these small regulatory transcripts may play crucial and previously unidentified roles in tumor pathogenesis and progression

    Evagination of Cells Controls Bio-Silica Formation and Maturation during Spicule Formation in Sponges

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    The enzymatic-silicatein mediated formation of the skeletal elements, the spicules of siliceous sponges starts intracellularly and is completed extracellularly. With Suberites domuncula we show that the axial growth of the spicules proceeds in three phases: (I) formation of an axial canal; (II) evagination of a cell process into the axial canal, and (III) assembly of the axial filament composed of silicatein. During these phases the core part of the spicule is synthesized. Silicatein and its substrate silicate are stored in silicasomes, found both inside and outside of the cellular extension within the axial canal, as well as all around the spicule. The membranes of the silicasomes are interspersed by pores of ≈2 nm that are likely associated with aquaporin channels which are implicated in the hardening of the initial bio-silica products formed by silicatein. We can summarize the sequence of events that govern spicule formation as follows: differential genetic readout (of silicatein) → fractal association of the silicateins → evagination of cells by hydro-mechanical forces into the axial canal → and finally processive bio-silica polycondensation around the axial canal. We termed this process, occurring sequentially or in parallel, bio-inorganic self-organization

    Navigating to the Moon Along Low-Energy Transfers

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    This paper presents a navigation strategy to fly to the Moon along a Weak Stability Boundary transfer trajectory. A particular strategy is devised to ensure capture into an uncontrolled relatively stable orbit at the Moon. Both uncertainty in the orbit determination process and in the control of the thrust vector are included in the navigation analysis. The orbit determination process is based on the definition of an optimal filtering technique that is able to meet accuracy requirements at an acceptable computational cost. Three sequential filtering techniques are analysed: an extended Kalman filter, an Unscented Kalman filter and a Kalman filter based on high order expansions. The analysis shows that only the unscented Kalman filter meets the accuracy requirements at an acceptable computational cost. This paper demonstrates lunar weak capture for all trajectories within a capture corridor defined by all the trajectories in the neighbourhood of the nominal one, in state space. A minimum f'v strategy is presented to extend the lifetime of the spacecraft around the Moon. The orbit determination and navigation strategies are applied to the case of the European Student Moon Orbiter

    Optical properties of in-vitro biomineralised silica

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    This is the final version of the article. Available from the publisher via the DOI in this record.Silicon is the second most common element on the Earth's crust and its oxide (SiO(2)) the most abundant mineral. Silica and silicates are widely used in medicine and industry as well as in micro- and nano-optics and electronics. However, the fabrication of glass fibres and components requires high temperature and non-physiological conditions, in contrast to biosilica structures in animals and plants. Here, we show for the first time the use of recombinant silicatein-α, the most abundant subunit of sponge proteins catalyzing biosilicification reactions, to direct the formation of optical waveguides in-vitro through soft microlithography. The artificial biosilica fibres mimic the natural sponge spicules, exhibiting refractive index values suitable for confinement of light within waveguides, with optical losses in the range of 5-10 cm(-1), suitable for application in lab-on-chips systems. This method extends biosilicification to the controlled fabrication of optical components by physiological processing conditions, hardly addressed by conventional technologies.This work is financially supported by the BIO-LITHO European project (6th Framework Program, NMP). W.E.G. Muller is holder of an ERC Advanced Research Grant

    Sponge spicules as blueprints for the biofabrication of inorganic–organic composites and biomaterials

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    While most forms of multicellular life have developed a calcium-based skeleton, a few specialized organisms complement their body plan with silica. However, of all recent animals, only sponges (phylum Porifera) are able to polymerize silica enzymatically mediated in order to generate massive siliceous skeletal elements (spicules) during a unique reaction, at ambient temperature and pressure. During this biomineralization process (i.e., biosilicification) hydrated, amorphous silica is deposited within highly specialized sponge cells, ultimately resulting in structures that range in size from micrometers to meters. Spicules lend structural stability to the sponge body, deter predators, and transmit light similar to optic fibers. This peculiar phenomenon has been comprehensively studied in recent years and in several approaches, the molecular background was explored to create tools that might be employed for novel bioinspired biotechnological and biomedical applications. Thus, it was discovered that spiculogenesis is mediated by the enzyme silicatein and starts intracellularly. The resulting silica nanoparticles fuse and subsequently form concentric lamellar layers around a central protein filament, consisting of silicatein and the scaffold protein silintaphin-1. Once the growing spicule is extruded into the extracellular space, it obtains final size and shape. Again, this process is mediated by silicatein and silintaphin-1, in combination with other molecules such as galectin and collagen. The molecular toolbox generated so far allows the fabrication of novel micro- and nanostructured composites, contributing to the economical and sustainable synthesis of biomaterials with unique characteristics. In this context, first bioinspired approaches implement recombinant silicatein and silintaphin-1 for applications in the field of biomedicine (biosilica-mediated regeneration of tooth and bone defects) or micro-optics (in vitro synthesis of light waveguides) with promising results

    Bioactive secondary metabolites from the endophytic fungus Chaetomium sp. isolated from Salvia officinalis growing in Morocco

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    This study reports the chemical investigation and cytotoxic activity of the secondary metabolites produced by the endophytic fungus Chaetomium sp. isolated from Salvia officinalis growing in Morocco. This plant was collected from the Beni-Mellal Mountain in Morocco and belongs to the Lamiaceae family and is named in Morocco “Salmia”. The endophytic fungus Chaetomium sp. was isolated from the tissues of the stem of this plant. The fungal strain was identified by PCR. The crude organic extract of the fungal strain was proven to be active when tested for cytotoxicity against L5178Y mouse lymphoma cells. Chemical investigation of the secondary metabolites showed that cochliodinol is the main component beside isocochliodinol. The structures of the isolated compounds were determined on the basis of NMR analysis (1H, 13C, COSY and HMBC) as well as by mass spectrometry using ESI (Electron Spray Ionisation) as source
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