351 research outputs found

    Input effects on the acquisition of a novel phrasal construction in five year olds

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    The present experiments demonstrate that children as young as five years old (M = 5;2) generalize beyond their input on the basis of minimal exposure to a novel argument structure construction. The novel construction that was used involved a non-English phrasal pattern: VN1N2, paired with a novel abstract meaning: N2 approaches N1. At the same time, we find that children are keenly sensitive to the input: they show knowledge of the construction after a single day of exposure but this grows stronger after three days; also, children generalize more readily to new verbs when the input contains more than one verb

    X-ray Spectra of the RIXOS source sample

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    We present results of an extensive study of the X-ray spectral properties of sources detected in the RIXOS survey, that is nearly complete down to a flux limit of 3e-14 cgs (0.5-2 keV). We show that for X-ray surveys containing sources with low count rate spectral slopes estimated using simple hardness ratios in the ROSAT band can be biased. Instead we analyse three-colour X-ray data using statistical techniques appropriate to the Poisson regime which removes the effects of this bias. We have then applied this technique to the RIXOS survey to study the spectral properties of the sample. For the AGN we find an average energy index of 1.05+-0.05 with no evidence for spectral evolution with redshift. Individual AGN are shown to have a range of properties including soft X-ray excesses and intrinsic absorption. Narrow Emission Line Galaxies also seem to fit to a power-law spectrum, which may indicate a non-thermal origin for their X-ray emission. We infer that most of the clusters in the sample have a bremsstrahlung temperature >3 keV, although some show evidence for a cooling flow. The stars deviate strongly from a power-law model but fit to a thermal model. Finally, we have analysed the whole RIXOS sample containing 1762 sources. We find that the mean spectral slope of the sources hardens at lower fluxes in agreement with results from other samples. However, a study of the individual sources demonstrates that the hardening of the mean is caused by the appearance of a population of very hard sources at the lowest fluxes. This has implications for the nature of the soft X-ray background.Comment: 31,LaTeX file, 2 PS files with Table 2 and 22 PS figures. MNRAS in pres

    Acquiring and processing verb argument structure : distributional learning in a miniature language

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    Adult knowledge of a language involves correctly balancing lexically-based and more language-general patterns. For example, verb argument structures may sometimes readily generalize to new verbs, yet with particular verbs may resist generalization. From the perspective of acquisition, this creates significant learnability problems, with some researchers claiming a crucial role for verb semantics in the determination of when generalization may and may not occur. Similarly, there has been debate regarding how verb-specific and more generalized constraints interact in sentence processing and on the role of semantics in this process. The current work explores these issues using artificial language learning. In three experiments using languages without semantic cues to verb distribution, we demonstrate that learners can acquire both verb-specific and verb-general patterns, based on distributional information in the linguistic input regarding each of the verbs as well as across the language as a whole. As with natural languages, these factors are shown to affect production, judgments and real-time processing. We demonstrate that learners apply a rational procedure in determining their usage of these different input statistics and conclude by suggesting that a Bayesian perspective on statistical learning may be an appropriate framework for capturing our findings

    A conserved arginine with non-conserved function is a key determinant of agonist selectivity in α7 nicotinic ACh receptors

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    The α7 and α4ÎČ2* (“*” denotes possibly assembly with another subunit) nicotinic acetylcholine receptors (nAChRs) are the most abundant nAChRs in the mammalian brain. These receptors are the most targeted nAChRs in drug discovery programmes for brain disorders. However, the development of subtype-specific agonists remains challenging due to the high degree of sequence homology and conservation of function in nAChRs. We have developed C(10) variants of cytisine, a partial agonist of α4ÎČ2 nAChR that has been used for smoking cessation. The C(10) methyl analogue used in this study displays negligible affinity for α7 nAChR, while retaining high affinity for α4ÎČ2 nAChR.Fil: Minguez Viñas, Teresa. Oxford Brookes University; Reino UnidoFil: Nielsen, Beatriz Elizabeth. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto de Investigaciones BioquĂ­micas de BahĂ­a Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂ­micas de BahĂ­a Blanca; Argentina. Universidad Nacional del Sur. Departamento de BiologĂ­a, BioquĂ­mica y Farmacia; ArgentinaFil: Shoemark, Deborah K.. University Of Bristol; Reino UnidoFil: Gotti, Cecilia. UniversitĂ  degli Studi di Milano; ItaliaFil: Sessions, Richard B.. University Of Bristol; Reino UnidoFil: Mulholland, Adrian J.. University Of Bristol; Reino UnidoFil: Bouzat, Cecilia Beatriz. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto de Investigaciones BioquĂ­micas de BahĂ­a Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂ­micas de BahĂ­a Blanca; Argentina. Universidad Nacional del Sur. Departamento de BiologĂ­a, BioquĂ­mica y Farmacia; ArgentinaFil: Wonnacott, Susan. University of Bath; Reino UnidoFil: Gallagher, Timothy. University Of Bristol; Reino UnidoFil: Bermudez, Isabel. University of Oxford; Reino UnidoFil: Oliveira, Ana Sofia. University Of Bristol; Reino Unid

    Atypical birdsong and artificial languages provide insights into how communication systems are shaped by learning, use and transmission

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    In this article, I argue that a comparative approach focusing on the cognitive capacities and behavioral mechanisms that underlie vocal learning in songbirds and humans can provide valuable insights into the evolutionary origins of language. The experimental approaches I discuss use abnormal song and atypical linguistic input to study the processes of individual learning, social interaction, and cultural transmission. Atypical input places increased learning and communicative pressure on learners, so exploring how they respond to this type of input provides a particularly clear picture of the biases and constraints at work during learning and use. Furthermore, simulating the cultural transmission of these unnatural communication systems in the laboratory informs us about how learning and social biases influence the structure of communication systems in the long run. Findings based on these methods suggest fundamental similarities in the basic social–cognitive mechanisms underlying vocal learning in birds and humans, and continuing research promises insights into the uniquely human mechanisms and into how human cognition and social behavior interact, and ultimately impact on the evolution of language

    “It ain’t (just) what you do, it’s (also) the way that you do it”: The role of Procedural Justice in the Implementation of Anti-social Behaviour Interventions with Young People

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    This paper provides an analysis of the introduction and implementation of hybrid powers to regulate anti-social behaviour, during a period of regulatory ‘hyperactivity’ in the UK. It explores the role of procedural justice by drawing on findings from a study conducted in England which investigated the implementation practices and experiences of young people and parents. These are considered against seven characteristics of procedural justice: voice; voluntariness; respectful treatment; parsimony; accuracy of information; fairness; and neutrality. The paper analyses the manner in which principles of voluntary cooperation can be corrupted by threats of punitive sanctions. It questions the extent to which the use of such hybrid orders fosters perceptions of legitimacy and supports the capacity of young people to avoid criminalisation

    Language learning, language use and the evolution of linguistic variation

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    Linguistic universals arise from the interaction between the processes of language learning and language use. A test case for the relationship between these factors is linguistic variation, which tends to be conditioned on linguistic or sociolinguistic criteria. How can we explain the scarcity of unpredictable variation in natural language, and to what extent is this property of language a straightforward reflection of biases in statistical learning? We review three strands of experimental work exploring these questions, and introduce a Bayesian model of the learning and transmission of linguistic variation along with a closely matched artificial language learning experiment with adult participants. Our results show that while the biases of language learners can potentially play a role in shaping linguistic systems, the relationship between biases of learners and the structure of languages is not straightforward. Weak biases can have strong effects on language structure as they accumulate over repeated transmission. But the opposite can also be true: strong biases can have weak or no effects. Furthermore, the use of language during interaction can reshape linguistic systems. Combining data and insights from studies of learning, transmission and use is therefore essential if we are to understand how biases in statistical learning interact with language transmission and language use to shape the structural properties of language

    Unlocking nicotinic selectivity via direct C‒H functionalization of (−)-cytisine

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    Differentiating nicotinic acetylcholine receptors (nAChR) to target the high-affinity nicotine α4ÎČ2 subtype is a major challenge in developing effective addiction therapies. Although cytisine 1 and varenicline 2 (current smoking-cessation agents) are partial agonists of α4ÎČ2, these drugs display full agonism at the α7 nAChR subtype. Site-specific modification of (−)-cytisine via Ir-catalyzed C‒H activation provides access to C(10) variants 6–10, 13, 14, 17, 20, and 22, and docking studies reveal that C(10) substitution targets the complementary region of the receptor binding site, mediating subtype differentiation. C(10)-modified cytisine ligands retain affinity for α4ÎČ2 nAChR and are partial agonists, show enhanced selectivity for α4ÎČ2 versus both α3ÎČ4 and α7 subtypes, and critically, display negligible activity at α7. Molecular dynamics simulations link the C(10) moiety to receptor subtype differentiation; key residues beyond the immediate binding site are identified, and molecular-level conformational behavior responsible for these crucial differences is characterized
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