221 research outputs found

    The Study of the Properties of Uranium Dioxide Pellets Depending on the Parameters of Pressing and Sintering

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    The paper presents dilatometric research of uranium dioxide pellets, fabricated by compaction at different pressure values. Temperature observed at sintering start is determined and it is pointed out that this temperature doesn’t depend on compaction pressure. Keywords: uranium dioxide, compaction, sintering, dilatometry, shrink curves, geometric density, pycnometric density

    Ultrabright GeV photon source via controlled electromagnetic cascades in laser-dipole waves

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    One aim of upcoming high-intensity laser facilities is to provide new high-flux gamma-ray sources. Electromagnetic cascades may serve for this, but are known to limit both field strengths and particle energies, restricting efficient production of photons to sub-GeV energies. Here we show how to create a directed GeV photon source, enabled by a controlled interplay between the cascade and anomalous radiative trapping. Using advanced 3D QED particle-in-cell (PIC) simulations and analytic estimates, we show that the concept is feasible for planned peak powers of 10 PW level. A higher peak power of 40 PW can provide 10910^9 photons with GeV energies in a well-collimated 3 fs beam, achieving peak brilliance 9×1024{9 \times 10^{24}} ph s1^{-1}mrad2^{-2}mm2^{-2}/0.1%{\%}BW. Such a source would be a powerful tool for studying fundamental electromagnetic and nuclear processes

    Live Birth of a Healthy Child in a Couple with Identical mtDNA Carrying a Pathogenic c.471_477delTTTAAAAinsG Variant in the MOCS2 Gene.

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    Molybdenum cofactor deficiency type B (MOCODB; #252160) is an autosomal recessive metabolic disorder that has only been described in 37 affected patients. In this report, we describe the presence of an in-frame homozygous variant (c.471_477delTTTAAAAinsG) in the MOCS2 gene in an affected child, diagnosed with Ohtahara syndrome according to the clinical manifestations. The analysis of the three-dimensional structure of the protein and the amino acid substitutions suggested the pathogenicity of this mutation. To prevent transmitting this mutation to the next generation, we used preimplantation genetic testing for the monogenic disorders (PGT-M) protocol to select MOCS2 gene mutant-free embryos for transfer in an in vitro fertilization (IVF) program. As a result, a healthy child was born. Interestingly, both parents of the proband shared an identical mitochondrial (mt) DNA control region, assuming their close relationship and thus suggesting that both copies of the nuclear rare variant c.471_477delTTTAAAAinsG may have been transmitted from the same female ancestor. Our estimation of the a priori probability of meeting individuals with the same mtDNA haplotype confirms the assumption of a possible distant maternal relationship among the proband's direct relatives

    Effect of hydrophobization of airfield coatings on the consumption of deicing reagents2

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    The issue of reducing costs for the maintenance of airfield coatings is particularly important nowadays due to the increase in the intensity of domestic air transportation. A significant part of the costs of the operational maintenance of airfields is spent on the purchase of deicing reagents (DIR) used to protect airfield pavements from icing. There is a possibility to reduce the required amount DIR by using of hydrophobizing impregnations (HPI) for cement concrete airfield pavements. The assumption about possibility to reduce costs for DIR by using HPI was proven by laboratory tests on specimens of cement concrete slabs. In the course of laboratory tests the process of airfield pavement icing and de-icing was modeled. According to the results of experimental studies it was determined that the consumption of DIR for cement concrete slabs specimens treated with HPI was reduced by 35% compared to similar specimens without HPI treatment. For the economic evaluation of cost reduction for the purchase of DIRs, the costs of applied DIRs used at civil airfields of the Russian Federation were analyzed, taking into account their location in different climatic zones. The assessment has revealed that the cost savings for the purchase of DIRs can be up to 29.1 %

    Studies to elucidate the effect and antiapoptotic mechanism of 2-ethyl-3-hydroxy-6- methylpyridine-n-acetyltaurinate in a rat model of retinal ischemia-reperfusion

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    To study the retinoprotective effect and antiapoptotic mechanism of 2-Ethyl-3-hydroxy-6-methyl-pyridine-Nacetyltaurinate (EHMP-NAT) in a rat model of retinal ischemia-reperfusio

    The Retrograde IFT Machinery of C. elegans Cilia: Two IFT Dynein Complexes?

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    We analyzed the relatively poorly understood IFT-dynein (class DYNC2)-driven retrograde IFT pathway in C. elegans cilia, which yielded results that are surprising in the context of current models of IFT. Assays of C. elegans dynein gene expression and intraflagellar transport (IFT) suggest that conventional IFT-dynein contains essential heavy (CHE-3), light-intermediate (XBX-1), plus three light polypeptide chains that participate in IFT, but no “essential” intermediate chain. IFT assays of XBX-1::YFP suggest that IFT-dynein is transported as cargo to the distal tip of the cilium by kinesin-2 motors, but independent of the IFT-particle/BBSome complexes. Finally, we were surprised to find that the subset of cilia present on the OLQ (outer labial quadrant) neurons assemble independently of conventional “CHE-3” IFT-dynein, implying that there is a second IFT-dynein acting in these cilia. We have found a novel gene encoding a dynein heavy chain, DHC-3, and two light chains, in OLQ neurons, which could constitute an IFT-dynein complex in OLQ neuronal cilia. Our results underscore several surprising features of retrograde IFT that require clarification

    Extended particle-in-cell schemes for physics in ultrastrong laser fields: Review and developments.

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    We review common extensions of particle-in-cell (PIC) schemes which account for strong field phenomena in laser-plasma interactions. After describing the physical processes of interest and their numerical implementation, we provide solutions for several associated methodological and algorithmic problems. We propose a modified event generator that precisely models the entire spectrum of incoherent particle emission without any low-energy cutoff, and which imposes close to the weakest possible demands on the numerical time step. Based on this, we also develop an adaptive event generator that subdivides the time step for locally resolving QED events, allowing for efficient simulation of cascades. Further, we present a unified technical interface for including the processes of interest in different PIC implementations. Two PIC codes which support this interface, PICADOR and ELMIS, are also briefly reviewed
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