296 research outputs found

    Simplicity of the automorphism groups of some Hrushovski constructions

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    We show that the automorphism groups of certain countable structures obtained using the Hrushovski amalgamation method are simple groups. The structures we consider are the 'uncollapsed' structures of infinite Morley rank obtained by the ab initio construction and the (unstable) omega-categorical pseudoplanes. The simplicity of the automorphism groups of these follows from results which generalize work of Lascar and of Tent and Ziegler.Comment: 35 page

    SIMPLICITY OF THE AUTOMORPHISM GROUPS OF SOME HRUSHOVSKI CONSTRUCTIONS

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    Abstract. we show that the automorphism groups of certain countable structures obtained using the Hrushovski amalgamation method are simple groups. The structures we consider are the 'uncollapsed' structures of infinite Morley rank obtained by the ab initio construction and the (unstable) ā„µ 0 -categorical pseudoplanes. The simplicity of the automorphism groups of these follows from results which generalize work of Lascar and of Tent and Ziegler

    Prediction of Pathological Complete Response to Neoadjuvant Chemotherapy for Primary Breast Cancer Comparing Interim Ultrasound, Shear Wave Elastography and MRI

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    Abstract Backgroundā€‚Prediction of pathological complete response (pCR) of primary breast cancer to neoadjuvant chemotherapy (NACT) may influence planned surgical approaches in the breast and axilla. The aim of this project is to assess the value of interim shear wave elastography (SWE), ultrasound (US) and magnetic resonance imaging (MRI) after 3 cycles in predicting pCR. Methodsā€‚64 patients receiving NACT had baseline and interim US, SWE and MRI examinations. The mean lesion stiffness at SWE, US and MRI diameter was measured at both time points. We compared four parameters with pCR status: a) Interim mean stiffness ā‰¤ or &gt;ā€Š50 kPa; b) Percentage stiffness reduction; c) Percentage US diameter reduction and d) Interim MRI response using RECIST criteria. The Chi square test was used to assess significance. Resultsā€‚Interim stiffness of ā‰¤ or &gt;ā€Š50 kPa gave the best prediction of pCR with pCR seen in 10 of 14 (71ā€Š%) cancers with an interim stiffness of ā‰¤ā€Š50 kPa, compared to 7 of 50Ā (14ā€Š%) of cancers with an interim stiffness of &gt;ā€Š50 kPa, (pā€Š&lt;ā€Š0.0001) (sensitivity 59ā€Š%, specificity 91ā€Š%, PPV 71ā€Š%, NPV 86ā€Š% and diagnostic accuracy 83ā€Š%). Percentage reduction in stiffness was the next best parameter (sensitivity 59ā€Š%, specificity 85ā€Š%, pā€Š&lt;ā€Š0.0004) followed by reduction in MRI diameter of &gt;ā€Š30ā€Š% (sensitivity 50ā€Š% and specificity 79ā€Š%, pā€Š=ā€Š0.03) and % reduction in US diameter (sensitivity 47ā€Š%, specificity 81ā€Š%, pā€Š=ā€Š0.03). Similar results were obtained from ROC analysis. Conclusionā€‚SWE stiffness of breast cancers after 3 cycles of NACT and changes in stiffness from baseline are strongly associated with pCR after 6 cycles.</jats:p

    The development of sentence-interpretation strategies in monolingual German-learning children with and without specific language impairment

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    Previous research on sentence comprehension conducted with German-learning children has concentrated on the role of case marking and word order in typically developing children. This paper compares, the performance of German-learning children with language impairment (age 4-6 years) and without language impairment (aged 2-6, 8-9 years) in two experiments that systematically vary the cues animacy, case marking; word-order, and subject-verb agreement. The two experiments differ with regard to the choice of case marking: in the first it is distinct but in the second it is neutralized. The theoretical framework is the competition model developed by Bates and Mac Whinney and their collaborators, a variant of the parallel distributed processing models. It is hypothesized that children of either population first appreciate the cue animacy that can be processed locally, that is, "on the spot," before they turn to more distributed cues leading ultimately up to subject-verb agreement, which presupposes the comparison of various constituents before an interpretation can be established. Thus agreement is more "costly" in processing than animacy or the (more) local cue initial NP. In experiment I with unambiguous case markers it is shown that the typically developing children proceed from animacy to the nominative (predominantly in coalition with the initial NP) to agreement, while in the second experiment with ambiguous case markers these children turn from animacy to the initial NP and then to agreement. The impaired children also progress from local to distributed cues. Yet, in contrast to the control group, they do not acknowledge the nominative in coalition with the initial NP in the first experiment but only in support of agreement. However, although they do not seem to appreciate distinct case markers to any large extent in the first experiment, they are irritated if such distinctions are lacking: in experiment II all impaired children turn to. animacy (some in coalition with the initial NP and/or particular word orders). In the discussion, the relationship between short-term memory and processing as well as the relationship between production and comprehension of case markers and agreement are addressed. Further research is needed to explore in more detail "cue costs" in sentence comprehension

    Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors.

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    Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (Ī±-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a āˆ¼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination.This work was supported by the Medical Research Council (R.T.K, R.J.M.F and H.O.B.G. G0701476; K.V. and R.T.K 1233560), Wellcome Trust (R.T.K. and K.A.E. 091543/Z/10/Z), Marie Curie training programme Axregen EC FP7 ITN (I.L. and R.T.K 214003), and core support grant from the Wellcome Trust and MRC to the Wellcome Trust ā€“ Medical Research Council Cambridge Stem Cell Institute.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/ncomms951
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