493 research outputs found
Sex differences in Cognitive Abilities Test scores: a UK national picture
No full textBackground and aims. There is uncertainty about the extent or even existence of sex differences in the mean and variability of reasoning test scores ( Jensen, 1998; Lynn, 1994, ; Mackintosh, 1996). This paper analyses the Cognitive Abilities Test (CAT) scores of a large and representative sample of UK pupils to determine the extent of any sex differences.
Sample. A nationally representative UK sample of over 320,000 school pupils aged 11-12 years was assessed on the CAT (third edition) between September 2001 and August 2003. The CAT includes separate nationally standardized tests for verbal, quantitative, and non-verbal reasoning. The size and recency of the sample is unprecedented in research on this issue.
Methods. The sheer size of the sample ensures that any sex difference will achieve statistical significance. Therefore, effect sizes (d) and variance ratios (VR) are employed to evaluate the magnitude of sex differences in mean scores and in score variability, respectively.
Results. The mean verbal reasoning score for girls was 2.2 standard score points higher than the mean for boys, but only 0.3 standard points in favour of girls for non-verbal reasoning (NVR), and 0.7 points in favour of boys for quantitative reasoning (QR). However, for all three tests there were substantial sex differences in the standard deviation of scores, with greater variance among boys. Boys were over represented relative to girls at both the top and the bottom extremes for all tests, with the exception of the top 10% in verbal reasoning.
Conclusions. Given the small differences in means, explanations for sex differences in wider domains such examination attainment at age 16 need to look beyond conceptions of `ability'. Boys tend to be both the lowest and the highest performers in terms of their reasoning abilities, which warns against the danger of stereotyping boys as low achievers
Identification of a novel type of spacer element required for imprinting in fission yeast
No full textAsymmetrical segregation of differentiated sister chromatids is thought to be important for cellular differentiation in higher
eukaryotes. Similarly, in fission yeast, cellular differentiation involves the asymmetrical segregation of a chromosomal
imprint. This imprint has been shown to consist of two ribonucleotides that are incorporated into the DNA during laggingstrand
synthesis in response to a replication pause, but the underlying mechanism remains unknown. Here we present key
novel discoveries important for unravelling this process. Our data show that cis-acting sequences within the mat1 cassette
mediate pausing of replication forks at the proximity of the imprinting site, and the results suggest that this pause dictates
specific priming at the position of imprinting in a sequence-independent manner. Also, we identify a novel type of cis-acting
spacer region important for the imprinting process that affects where subsequent primers are put down after the
replication fork is released from the pause. Thus, our data suggest that the imprint is formed by ligation of a not-fullyprocessed
Okazaki fragment to the subsequent fragment. The presented work addresses how differentiated sister
chromatids are established during DNA replication through the involvement of replication barriers
Modeling of multi-strand wire ropes subjected to axial tension and torsion loads
No full textA new model characterizing the response of a multi-strand wire rope subjected to axial tension and axial torque is presented in this paper. Apart from most of previous approaches which deal with a straight wire strand, the present model fully considers the double-helix structure in multi-strand configuration. To be further, a new method to compute local deformation parameters (two curvatures and a twist defined by Love, 1944) of each wire is introduced. The proposed model well predicts the global stiffness of the rope. It is found that different friction states between adjacent wires can lead to quite a different distribution of local bending and torsion deformation of double-helix wire. The variations of stresses in double-helix wires along the rope axis are analyzed and the results show that torsion stress of a double-helix wire can be neglected when the rope is subjected to axial tension (axial torsion is restrained). The present model provides a new way to estimate the local deformation and stresses at the wire level, which sheds new insight into the understanding of the fatigue and failure behavior of the wire rope. (C) 2015 Elsevier Ltd. All rights reserved
DNA binding, single-strand annealing and strand exchange properties of Hop2-Mnd1
No full text<p><b>Copyright information:</b></p><p>Taken from "Stimulation of fission yeast and mouse Hop2-Mnd1 of the Dmc1 and Rad51 recombinases"</p><p></p><p>Nucleic Acids Research 2007;35(8):2719-2733.</p><p>Published online 10 Apr 2007</p><p>PMCID:PMC1885673.</p><p>© 2007 The Author(s)</p> () DNA binding of spH2M1. DNA-binding reactions contained ssDNA (), 5′-tailed duplex DNA (), dsDNA () and 3′-tailed duplex DNA () and the indicated concentrations of spH2M1. () Time course of single-strand annealing by spH2M1. Lane a, purified 400 bp duplex DNA. Reactions contained denatured 400 bp duplex DNA and no protein (lanes b–f) or spH2M1 (1.2 μM, lanes g–k). The reactions were stopped at the indicated times. () spH2M1 promote single-strand annealing in the presence of a single-strand binding protein. Lane a, purified 400 bp duplex DNA; lane b, spH2M1 alone (1.2 μM); lanes c–g, SSB alone; lanes h–l, spH2M1 (1.2 μM) with the indicated concentrations of SSB. () spH2M1 promotes strand exchange. spH2M1 was mixed with 1.5 μM 63-mer ssDNA. DNA strand exchange was initiated by addition of homologous 3 μM of 63-bp dsDNA, in which the strand that would be displaced during DNA strand exchange was P-labeled.Lane a, duplex DNA; lane b, denatured duplex DNA; lanes c–l, DNA strand exchange as a function of spH2M1 concentration. () Effect of cofactors on spH2M1 strand exchange. Reactions were carried out in buffer containing an ATP regeneration system using 3 μM spH2M1 (lane b); in buffer without ATP (lane c); in standard buffer in which ATP was replaced with ATPγS (lane d); AMP-PNP (lane e); standard buffer lacking Mg (lane f); reactions with heterologous ssDNA (lane g); in buffer without ATP regeneration (lane h); lane a, without protein
MRE11 facilitates the removal of human topoisomerase II complexes from genomic DNA
No full textTopoisomerase II creates a double-strand break intermediate with topoisomerase covalently coupled to the DNA via a 5'-phosphotyrosyl bond. These intermediate complexes can become cytotoxic protein-DNA adducts and DSB repair at these lesions requires removal of topoisomerase II. To analyse removal of topoisomerase II from genomic DNA we adapted the trapped in agarose DNA immunostaining assay. Recombinant MRE11 from 2 sources removed topoisomerase IIalpha from genomic DNA in vitro, as did MRE11 immunoprecipitates isolated from A-TLD or K562 cells. Basal topoisomerase II complex levels were very high in A-TLD cells lacking full-length wild type MRE11, suggesting that MRE11 facilitates the processing of topoisomerase complexes that arise as part of normal cellular metabolism. In K562 cells inhibition of MRE11, PARP or replication increased topoisomerase IIalpha and beta complex levels formed in the absence of an anti-topoisomerase II dru
A self-conscious Kurt Vonnegut: an analysis of Cat's Cradle, Slaughterhouse-Five and Breakfast of Champions
No full textThe works of Kurt Vonnegut stand as seminal in the American literary canon. Looking at three of his most influential novels, namely Cat's Cradle, Slaughterhouse-Five and Breakfast of Champions, this study aims to better understand the mechanisms which inform his fiction. Working chronologically through the novels, the study examines historical context, narrative technique, theoretical underpinnings and the social critique of each novel. Guided by an idea of the postmodern novel the study examines how these elements interact, concluding that by way of what may be considered "simple" yet self-conscious metafiction and prose as well as variations in narrative technique, Vonnegut is able to more accurately convey his opinions on the American situation as well as demonstrate his stance on the role of fiction and the writer in contemporary society. The study also considers closely the role of the reader and the author/reader/text relationship
Longitudinal oscillation of intensity fronts in a strand at the edge of an active region
No full textThe edge of a solar active region (AR) is considered as a possible source region of the slow solar wind. Winebarger et al. (2001) observed outflows from an AR with velocities between 5 and 20 km/s. Recently, Sakao et al. (2007) reported the outflow of X-ray-emitting plasma from the edge of an AR. This outflow was inferred from the observation of outward traveling intensity enhancements. However, in Robbrecht et al. (2001), propagation of slow magnetoacoustic waves along the strand was considered as the possible cause for the longitudinal extension of the strand. Whether this phenomenon relates to a slow-mode wave or the outflow of plasma or a heating process of different parts of the strand is still an open question. Here we try to identify the nature of such a traveling event through studying the longitudinal motions of certain intensity level fronts in the strand. We find that the intensity front is oscillating like a sinusoidal signal along the strand with a period of 11 minutes. This result suggests that the oscillation might be partly related with the 5-minute p-mode oscillation in the photosphere. Moreover, we find that such oscillation of intensity-level fronts can be described by a model in which the strand has periodic extension. Yet, the relation between the extending strand and slow solar wind needs to be further studied.Astronomy & AstrophysicsCPCI-S(ISTP)
Inertia in infrastructure development : some analytical aspects, and reasons for inefficient infrastructure choices
No full textThis paper uses some simple conceptual models to draw out various implications of infrastructure investments with long lifetimes for the ability of societies to reduce their future greenhouse gas emissions. A broad range of such investments, related both to energy supply and demand systems, may commit societies to high and persistent levels of greenhouse gas emissions over time, that are difficult and costly to change once the investments have been sunk. There are, the author argues, several strong reasons to expect the greenhouse gas emissions embedded in such investments to be excessive. One is that infrastructure investment decisions tend to be made on the basis of (current and expected future) emissions prices that do not fully reflect the social costs of greenhouse gas emissions resulting from the investments. A second, related, set of reasons are excessive discounting of future project costs and benefits including future climate damages, and a too-short planning horizon for infrastructure investors. These issues are illustrated for two alternative cases of climate damages, namely with the possibility of a"climate catastrophe,"and with a sustained increase in the marginal global damage cost of greenhouse gas emissions.Climate Change Economics,Energy Production and Transportation,Climate Change Mitigation and Green House Gases,Transport Economics Policy&Planning,Environment and Energy Efficiency
L. T. Meade\u27s Avaricious Anomaly: Â Madame Sara, British Imperialism, and Greedy Wolves in The Sorceress of the Strand
No full textL. T. Meade\u27s Avaricious Anomaly: Madame Sara, British Imperialism, and Greedy Wolves in The Sorceress of the Strand. Laurie Langlois Denning, Department of English, BYU Master of Arts. Critics interested in the prolific late Victorian author L.T. Meade have primarily focused on her work as an author of girls\u27 stories and novels for young people, which enjoyed fantastic commercial success in her lifetime but fell into obscurity after her death. Recent scholarship on her detective fiction shows Meade\u27s significant contributions to the genre as well as her engagement with social and political discourse. Scholars have noted ways that Meade\u27s popular series, The Sorceress of the Strand, contributes to the New Woman debate and expresses anxiety over the British imperial project. This project examines Meade\u27s villain in the series as a social anomaly that functions to interrogate the greed at the heart of imperialism. Examining the series\u27 conclusion and the unusual nature of its ending sheds new light on Meade\u27s contribution to debate over empire at the fin de siécle. Meade\u27s fascinating villain, Madame Sara, is doggedly pursued by two detective figures--one is considered the top forensic specialist in the British police force and the other is the head of a business fraud agency--but the detectives are never able to bring Madam Sara to justice. Instead, it is a wolf that finally defeats the brilliant criminal mastermind. Why a wolf? Madam Sara\u27s unusual demise serves as a deus ex machina that invites the reader to consider the Dante symbolism embedded in the text. Other critics see Meade\u27s ending as reinforcing the empire; however, given the Dante imagery that has Madam Sara symbolizing a greedy imperial force, Meade\u27s series indicts imperial greed and warns British citizens about failure to apprehend the evil in empire
An antibody raised against a pathogenic serpin variant induces mutant-like behaviour in the wild-type protein.
No full textA monoclonal antibody (mAb) that binds to a transient intermediate may act as a catalyst for the corresponding reaction; here we show this principle can extend on a macro-molecular scale to the induction of mutant-like oligomerisation in a wild-type protein. Using the common, pathogenic Glu342Lys (Z) variant of α1-antitrypsin as antigen - whose native state is susceptible to the formation of a proto-oligomeric intermediate - we have produced a mAb (5E3) that increases the rate of oligomerisation of the wild-type (M) variant. Employing ELISA, gel shift, thermal stability and FRET time-course experiments, we show that mAb5E3 does not bind to the native state of α1-antitrypsin, but recognises a cryptic epitope in the vicinity of the post-helix A loop and strand 4C that is revealed upon transition to the polymerisation intermediate, and which persists in the ensuing oligomer. This epitope is not shared by loop-inserted monomeric conformations. We show the increased amenity to polymerisation by either the pathogenic Glu342Lys mutation or the binding of mAb5E3 occurs without affecting energetic barrier to polymerisation. As mAb5E3 also does not alter the relative stability of the monomer to intermediate, it acts in a manner similar to the Glu342Lys mutation, by facilitating the conformational interchange between these two states
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