Determination of Cumulative Distribution Function of the Crest Value of the Lightning Current Circulating Through Line Surge Arresters

For the selection and design of line surge arresters (LSA), it is essential to know the characteristics of the lightning current circulating through LSA. When lightning strikes a transmission line, only a part of the lightning current circulates through LSA. This part mostly depends on the point of impact, and the characteristic of the lightning strike current. The determination of the cumulative distribution function of the lightning current circulating through arresters is presented in first part of the paper. It can be applied on transmission lines where LSAs will be installed to protect the line against the effect of atmospheric discharges. Second part of paper presents the calculation results of the cumulative distribution function of the lightning current circulating through arresters for particular 110 kV transmission line located in an area with high lightning activity

A quasi-Monte Carlo integration method applied to the computation of the Pollaczek integral

Nos remerciements à IEEE pour l'autorisation de mise à disposition du papier complet. © IEEE Copyright Notice : Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.International audienceThis paper presents an effective numeric method to compute Pollaczek integral. This integral is widely used in transmission-line theory when computing the mutual impedance between an overhead conductor and another overhead or underground conductor and the earth-return impedance of an underground cable. At first, we present mutual expressions proposed by Pollaczek and underline the numerical complexities that often lead to the adoption of alternative simplified methods. Then a brief review of the so called "quasi-Monte Carlo" integration method along with its advantages is given. Such an approach is then applied to compute numerically Pollaczek expressions. Comparison between our numerical procedure and an algorithm that has already been published proves both the procedure accuracy, one of its main advantages along with its ease of implementation, and its relatively low time consumption, independent of the input parameters. Finally, as an application example, quasi-Monte Carlo method is used to assess the adequacy, for several study cases, of the simplified formula by Lucca, which is a widely used approximate expression of interest

BMC Biology BMC Biology The toxoplasma-host cell junction is anchored to the cell cortex to sustain parasite invasive force

International audienceBackgroundThe public health threats imposed by toxoplasmosis worldwide and by malaria in sub-Saharan countries are directly associated with the capacity of their closely related causative agents Toxoplasma and Plasmodium, respectively to colonize and expand inside host cells. Therefore, deciphering how these two Apicomplexan protozoan parasites access their hosting cells has been highlighted as a high priority research with the relevant perspective of designing anti-invasive molecules to prevent diseases. Central to the mechanistic base of invasion for both genera is mechanical force, which is thought to be applied by the parasite at the interface between the two cells following assembly of a unique cell junction but this model lacks direct evidence and has been challenged by recent genetic and cell biology studies. In this work, using parasites expressing the fluorescent core component of this junction, we analyse characteristic features of the kinematics of penetration of more than 1000 invasion events.ResultsThe majority of invasion events occur with a typical forward rotational progression of the parasite through a static junction into a vacuole formed from the invaginating host cell plasma membrane, in which the parasite subsequently replicates. However, if parasites encounter resistance and if the junction is not strongly anchored to the host cell cortex, as when parasites do not secrete the toxofilin protein and therefore are unable to locally remodel the cortical actin cytoskeleton, the junction is capped backwards and travels retrogradely with the host cell membrane along the parasite surface as it is enclosed within a functional vacuole. Kinetic measurements of the invasive trajectories strongly support a similar parasite driven force in both static and capped junctions, both of which lead to successful invasion. However about 20% of toxofilin mutants fail to enter and eventually disengage from the host cell membrane while the secreted RON2 molecules are capped at the posterior pole before being cleaved and released in the medium. By contrast in cells characterized by low cortex tension and high cortical actin dynamics, junction capping and entry failure are drastically reduced.ConclusionThis kinematic analysis of pre-invasive and invasive T. gondii tachyzoite behaviors newly highlights that to invade cells, parasites need to engage their motor with the junction molecular complex where force is efficiently applied only upon proper anchorage to the host cell membrane and cortex

Heteroleptic actinocenes: a thorium(iv)-cyclobutadienyl-cyclooctatetraenyl-di-potassium-cyclooctatetraenyl complex.

From Europe PMC via Jisc Publications RouterHistory: ppub 2020-06-01, epub 2020-06-10Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; Grant(s): EP/M027015/1, EP/P001386/1Despite the vast array of η n -carbocyclic C5-8 complexes reported for actinides, cyclobutadienyl (C4) remain exceedingly rare, being restricted to six uranium examples. Here, overcoming the inherent challenges of installing highly reducing C4-ligands onto actinides when using polar starting materials such as halides, we report that reaction of [Th(η8-C8H8)2] with [K2{C4(SiMe3)4}] gives [{Th(η4-C4[SiMe3]4)(μ-η8-C8H8)(μ-η2-C8H8)(K[C6H5Me]2)}2{K(C6H5Me)}{K}] (1), a new type of heteroleptic actinocene. Quantum chemical calculations suggest that the thorium ion engages in π- and δ-bonding to the η4-cyclobutadienyl and η8-cyclooctatetraenyl ligands, respectively. Furthermore, the coordination sphere of this bent thorocene analogue is supplemented by an η2-cyclooctatetraenyl interaction, which calculations suggest is composed of σ- and π-symmetry donations from in-plane in- and out-of-phase C[double bond, length as m-dash]C 2p-orbital combinations to vacant thorium 6d orbitals. The characterisation data are consistent with this being a metal-alkene-type interaction that is integral to the bent structure and stability of this complex

Synthesis, bonding properties and ether activation reactivity of cyclobutadienyl-ligated hybrid uranocenes

A series of hybrid uranocenes consisting of uranium(iv) sandwiched between cyclobutadienyl (Cb) and cyclo-octatetraenyl (COT) ligands has been synthesized, structurally characterized and studied computationally. The dimetallic species [(η4-Cb′′′′)(η8-COT)U(μ:η2:η8-COT)U(THF)(η4-Cb′′′′)] (1) forms concomitantly with, and can be separated from, monometallic [(η4-Cb′′′′)U(THF)(η8-COT)] (2) (Cb′′′′ = 1,2,3,4-tetrakis(trimethylsilyl)cyclobutadienyl, COT = cyclo-octatetraenyl). In toluene solution at room temperature,1dissociates into2and the unsolvated uranocene [(η4-Cb′′′′)U(η8-COT)] (3). By applying a high vacuum, both1and2can be converted directly into3. Using bulky silyl substituents on the COT ligand allowed isolation of base-free [(η4-Cb′′′′)U{η8-1,4-(iPr3Si)2C8H6}] (4), with compounds3and4being new members of the bis(annulene) family of actinocenes and the first to contain a cyclobutadienyl ligand. Computational studies show that the bonding in the hybrid uranocenes3and4has non-negligible covalency. New insight into actinocene bonding is provided by the complementary interactions of the different ligands with uranium, whereby the 6d orbitals interact most strongly with the cyclobutadienyl ligand and the 5f orbitals do so with the COT ligands. The redox-neutral activation of diethyl ether by [(η4-Cb′′′′)U(η8-C8H8)] is also described and represents a uranium-cyclobutadienyl cooperative process, potentially forming the basis of further small-molecule activation chemistry

Fasc. 60 : Mariage : formalités de célébration

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Fasc. 30 (art. 266 à 285-1) : Conséquences du divorce sur les prestations sociales et pensions de réversion

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Cours de droit des personnes et de la famille

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