428 research outputs found

    State-related electroencephalographic deviances in attention deficit hyperactivity disorder

    Get PDF
    The dynamic security region (DSR) of bulk power system has been accepted more and more in recent years for providing plenty of security information and good prospect in online application. This paper compares three linear approximations for the dynamic security region of network-reduction power systems. The three linear approximations are the Q-linear approximation based on the quadratic approximation of stability region, the L-linear approximation based on the linear approximation of stability region and the L0-linear approximation based on the invariant assumption of the normal vector for the boundary of the stability region corresponding to different control variable. The three linear approximations are all obtained with a same critical point lying just on the boundary of dynamic security region. The critical point is searched with numerical simulation. The accuracy of the three linear approximations is compared, using the linear approximation obtained with the curve fitting approach or the actual boundary of DSR searched as the benchmark. Simulation results in IEEE 3-machine 9-bus system and 10-machine 39-bus New England system show that all the three linear approximations display fairly accurate estimation. Furthermore, from the computational viewpoint, the L-linear and the L0-linear method are two alternative choices to approximate the dynamic security region.link_to_subscribed_fulltex

    Verticale temperatuurgradiënten in geconditioneerde kassen: Effecten op groei, ontwikkeling en onderliggende processen bij tomaat

    Get PDF
    In de jaren 2003 tot 2007 is het aantal bedrijven waarop (semi)gesloten geteeld wordt geleidelijk toegenomen. Op alle bedrijven bleken echter vragen te bestaan over de reacties van het gewas op het nieuwe klimaat. Daarom is in 2008 door Wageningen UR Glastuinbouw een onderzoek gestart naar de groei van tomaat in geconditioneerde kassen, waarin veel aandacht wordt besteed aan de fysiologische processen in de plant. Het onderzoek wordt gefinancierd vanuit het programma Kas als Energiebron door Productschap Tuinbouw en het ministerie van EL&I en wordt begeleid door een aantal tomatentelers en een adviseur. Het onderzoek dat in dit rapport wordt beschreven had als centrale vraag hoe een verticale temperatuurgradiënt de processen in de plant beïnvloedt

    Molecular evolution of HoxA13 and the multiple origins of limbless morphologies in amphibians and reptiles

    Get PDF
    Developmental processes and their results, morphological characters, are inherited through transmission of genes regulating development. While there is ample evidence that cis-regulatory elements tend to be modular, with sequence segments dedicated to different roles, the situation for proteins is less clear, being particularly complex for transcription factors with multiple functions. Some motifs mediating protein-protein interactions may be exclusive to particular developmental roles, but it is also possible that motifs are mostly shared among different processes. Here we focus on HoxA13, a protein essential for limb development. We asked whether the HoxA13 amino acid sequence evolved similarly in three limbless clades: Gymnophiona, Amphisbaenia and Serpentes. We explored variation in ω (dN/dS) using a maximum-likelihood framework and HoxA13sequences from 47 species. Comparisons of evolutionary models provided low ω global values and no evidence that HoxA13 experienced relaxed selection in limbless clades. Branch-site models failed to detect evidence for positive selection acting on any site along branches of Amphisbaena and Gymnophiona, while three sites were identified in Serpentes. Examination of alignments did not reveal consistent sequence differences between limbed and limbless species. We conclude that HoxA13 has no modules exclusive to limb development, which may be explained by its involvement in multiple developmental processes

    Essential and checkpoint functions of budding yeast ATM and ATR during meiotic prophase are facilitated by differential phosphorylation of a meiotic adaptor protein, Hop1

    Get PDF
    A hallmark of the conserved ATM/ATR signalling is its ability to mediate a wide range of functions utilizing only a limited number of adaptors and effector kinases. During meiosis, Tel1 and Mec1, the budding yeast ATM and ATR, respectively, rely on a meiotic adaptor protein Hop1, a 53BP1/Rad9 functional analog, and its associated kinase Mek1, a CHK2/Rad53-paralog, to mediate multiple functions: control of the formation and repair of programmed meiotic DNA double strand breaks, enforcement of inter-homolog bias, regulation of meiotic progression, and implementation of checkpoint responses. Here, we present evidence that the multi-functionality of the Tel1/Mec1-to-Hop1/Mek1 signalling depends on stepwise activation of Mek1 that is mediated by Tel1/Mec1 phosphorylation of two specific residues within Hop1: phosphorylation at the threonine 318 (T318) ensures the transient basal level Mek1 activation required for viable spore formation during unperturbed meiosis. Phosphorylation at the serine 298 (S298) promotes stable Hop1-Mek1 interaction on chromosomes following the initial phospho-T318 mediated Mek1 recruitment. In the absence of Dmc1, the phospho-S298 also promotes Mek1 hyper-activation necessary for implementing meiotic checkpoint arrest. Taking these observations together, we propose that the Hop1 phospho-T318 and phospho-S298 constitute key components of the Tel1/Mec1- based meiotic recombination surveillance (MRS) network and facilitate effective coupling of meiotic recombination and progression during both unperturbed and challenged meiosis

    Egyptian Public Intellectuals and their “Wests”

    Get PDF
    Gradually, the term “occidentalism” is gaining ground. Since the end of the Cold War and the consequent loss of a West that could be defined in terms of (and against) its Communist nemesis in the East, the process of imaging the West is steadily acquiring students. This article reviews how popular writers in Egypt imagine the West, showing that while their views on the West are shaped differently by particular ideologies, they converge in condemning the policies emerging from the West

    A Page and Its Politics: Situating Kullinā Khālid Saʿīd in Egypt’s Ideological Landscape at the Time of Revolution

    Get PDF
    In discussions concerning the importance of social media in the 25January revolution, a central role is given to the "Kullinā Khālid Saʿīd" [We’re all Khaled Said] Facebook page. Using an advanced data collection and extraction application called Netvizz, a research team consisting of Arabists and Media studies specialists has collected and analysed all of the posts and comments exchanged through the page. This data set allows for a systematic analysis of the page. This article offers an outline of the ideological nature of "Kullinā Khālid Saʿīd", with particular emphasis on the "revolutionary" period between 1 January - 11 February 2011. It argues that the page shows no evidence of political bias in the sense of explicit favoring of a political group. Rather, the page constituted a community of users who abstained from using politically factional language. Reflecting the mood and concerns of the revolution’s grassroots masses, it clearly illustrates the disinclination to engage with formal politics

    An interlaboratory study of TEX86 and BIT analysis of sediments, extracts and standard mixtures.

    Get PDF
    Two commonly used proxies based on the distribution of glycerol dialkyl glycerol tetraethers (GDGTs) are the TEX86 (TetraEther indeX of 86 carbon atoms) paleothermometer for sea surface temperature reconstructions and the BIT (Branched Isoprenoid Tetraether) index for reconstructing soil organic matter input to the ocean. An initial round-robin study of two sediment extracts, in which 15 laboratories participated, showed relatively consistent TEX86 values (reproducibility ±3-4°C when translated to temperature) but a large spread in BIT measurements (reproducibility ±0.41 on a scale of 0-1). Here we report results of a second round-robin study with 35 laboratories in which three sediments, one sediment extract, and two mixtures of pure, isolated GDGTs were analyzed. The results for TEX86 and BIT index showed improvement compared to the previous round-robin study. The reproducibility, indicating interlaboratory variation, of TEX86 values ranged from 1.3 to 3.0°C when translated to temperature. These results are similar to those of other temperature proxies used in paleoceanography. Comparison of the results obtained from one of the three sediments showed that TEX86 and BIT indices are not significantly affected by interlaboratory differences in sediment extraction techniques. BIT values of the sediments and extracts were at the extremes of the index with values close to 0 or 1, and showed good reproducibility (ranging from 0.013 to 0.042). However, the measured BIT values for the two GDGT mixtures, with known molar ratios of crenarchaeol and branched GDGTs, had intermediate BIT values and showed poor reproducibility and a large overestimation of the "true" (i.e., molar-based) BIT index. The latter is likely due to, among other factors, the higher mass spectrometric response of branched GDGTs compared to crenarchaeol, which also varies among mass spectrometers. Correction for this different mass spectrometric response showed a considerable improvement in the reproducibility of BIT index measurements among laboratories, as well as a substantially improved estimation of molar-based BIT values. This suggests that standard mixtures should be used in order to obtain consistent, and molar-based, BIT values

    Mesoproterozoic surface oxygenation accompanied major sedimentary manganese deposition at 1.4 and 1.1 Ga

    Get PDF
    This research was funded by the Australian Science and Industry Endowment Fund (SIEF) as part of The Distal Footprints of Giant Ore Systems: UNCOVER Australia Project (RP04-063)—Capricorn Distal Footprints. EAS also thanks the donors of The American Chemical Society Petroleum Research Fund for partial support of this research (61017-ND2).Peer reviewedPublisher PD
    corecore