2,516 research outputs found

    Integral constraints on the monodromy group of the hyperkahler resolution of a symmetric product of a K3 surface

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    Let M be a 2n-dimensional Kahler manifold deformation equivalent to the Hilbert scheme of length n subschemes of a K3 surface S. Let Mon be the group of automorphisms of the cohomology ring of M, which are induced by monodromy operators. The second integral cohomology of M is endowed with the Beauville-Bogomolov bilinear form. We prove that the restriction homomorphism from Mon to the isometry group O[H^2(M)] is injective, for infinitely many n, and its kernel has order at most 2, in the remaining cases. For all n, the image of Mon in O[H^2(M)] is the subgroup generated by reflections with respect to +2 and -2 classes. As a consequence, we get counter examples to a version of the weight 2 Torelli question, when n-1 is not a prime power.Comment: Version 3: Latex, 54 pages. Expository change

    Genomic diversity of Escherichia coli isolates from backyard chickens and guinea fowl in the Gambia

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    Chickens and guinea fowl are commonly reared in Gambian homes as affordable sources of protein. Using standard microbiological techniques, we obtained 68 caecal isolates of Escherichia coli from 10 chickens and 9 guinea fowl in rural Gambia. After Illumina whole-genome sequencing, 28 sequence types were detected in the isolates (4 of them novel), of which ST155 was the most common (22/68, 32 %). These strains span four of the eight main phylogroups of E. coli, with phylogroups B1 and A being most prevalent. Nearly a third of the isolates harboured at least one antimicrobial resistance gene, while most of the ST155 isolates (14/22, 64 %) encoded resistance to ≥3 classes of clinically relevant antibiotics, as well as putative virulence factors, suggesting pathogenic potential in humans. Furthermore, hierarchical clustering revealed that several Gambian poultry strains were closely related to isolates from humans. Although the ST155 lineage is common in poultry from Africa and South America, the Gambian ST155 isolates belong to a unique cgMLST cluster comprising closely related (38-39 alleles differences) isolates from poultry and livestock from sub-Saharan Africa - suggesting that strains can be exchanged between poultry and livestock in this setting. Continued surveillance of E. coli and other potential pathogens in rural backyard poultry from sub-Saharan Africa is warranted

    Using process drama to explore the causes of dental anxiety in primary‑school children

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    Background Drama and role play can be unlisted as methods to allow children to view problems from a range of different perspectives that may differ from their own experience. Application of drama technique to assess the cause of dental fear and anxiety in a school setting is novel. Aim The aim of this study was to engage primary school children in the core investigation via participatory arts methodologies, namely, process drama to gain understanding of the causes of dental anxiety. Design Sixty-three children, aged 7–10 years from three primary schools participated in this study. A 90-min drama workshop was carried in each school. The children were encouraged to identify the causes of dental anxiety using key concepts from process drama. The sessions were audio-recorded and transcribed. Results Four key concepts emerged: (1) fear of the unknown; (2) unpleasant sensory experience; (3) society’s perception and portrayal of the dentist; and (4) learnt negative associations with the dentist. Within each four key concepts, two sub-themes were identified. Conclusions Role-playing and use of drama are a novel application and can reveal a considerable amount of information from the child’s perspective on the cause of dental fear and anxiety

    From von Neumann architecture and Atanasoff’s ABC to Neuromorphic Computation and Kasabov’s NeuCube. Part II: Applications

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    Spatio/Spector-Temporal Data (SSTD) analyzing is a challenging task, as temporal features may manifest complex interactions that may also change over time. Making use of suitable models that can capture the “hidden” interactions and interrelationship among multivariate data, is vital in SSTD investigation. This chapter describes a number of prominent applications built using the Kasabov’s NeuCube-based Spiking Neural Network (SNN) architecture for mapping, learning, visualization, classification/regression and better understanding and interpretation of SSTD

    Reflections on a 'virtual' practice development unit: changing practice through identity development

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    Aims. This paper draws together the personal thoughts and critical reflections of key people involved in the establishment of a ‘virtual’ practice development unit of clinical nurse specialists in the south of England. Background. This practice development unit is ‘virtual’ in that it is not constrained by physical or specialty boundaries. It became the first group of Trust-wide clinical nurse specialists to be accredited in the UK as a practice development unit in 2004. Design and methods. The local university was asked to facilitate the accreditation process via 11 two-hour audio-recorded learning sessions. Critical reflections from practice development unit members, leaders and university staff were written 12 months after successful accreditation, and the framework of their content analysed. Findings and discussion. Practice development was seen as a way for the clinical nurse specialists to realize their potential for improving patient care by transforming care practice in a collaborative, interprofessional and evolutionary manner. The practice development unit provided a means for these nurses to analyse their role and function within the Trust. Roberts’ identity development model for nursing serves as a useful theoretical underpinning for the reflections contained in this paper. Conclusions. These narratives provide another example of nurses making the effort to shape and contribute to patient care through organizational redesign. This group of nurses began to realize that the structure of the practice development unit process provided them with the means to analyse their role and function within the organization and, as they reflected on this structure, their behaviour began to change. Relevance to clinical practice. Evidence from these reflections supports the view that practice development unit participants have secured a positive and professional identity and are, therefore, better able to improve the patient experience

    Semileptonic Branching Fraction of Charged and Neutral B Mesons

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    An examination of leptons in Υ(4S){\Upsilon (4S)} events tagged by reconstructed BB decays yields semileptonic branching fractions of b=(10.1±1.8±1.4)%b_-=(10.1 \pm 1.8\pm 1.4)\% for charged and b0=(10.9±0.7±1.1)%b_0=(10.9 \pm 0.7\pm 1.1)\% for neutral BB mesons. This is the first measurement for charged BB. Assuming equality of the charged and neutral semileptonic widths, the ratio b/b0=0.93±0.18±0.12b_-/b_0=0.93 \pm 0.18 \pm 0.12 is equivalent to the ratio of lifetimes. A postscript version is available through World-Wide-Web in http://w4.lns.cornell.edu/public/CLNS/1994Comment: 9 pages (in REVTEX format) Preprint CLNS94-1286, CLEO 94-1

    Observation of the Isospin-Violating Decay Ds+Ds+π0D_s^{*+}\to D_s^+\pi^0

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    Using data collected with the CLEO~II detector, we have observed the isospin-violating decay Ds+Ds+π0D_s^{*+}\to D_s^+\pi^0. The decay rate for this mode, relative to the dominant radiative decay, is found to be Γ(Ds+Ds+π0)/Γ(Ds+Ds+γ)=0.0620.018+0.020±0.022\Gamma(D_s^{*+}\to D_s^+\pi^0)/\Gamma(D_s^{*+}\to D_s^+\gamma)= 0.062^{+0.020}_{-0.018}\pm0.022.Comment: 8 page uuencoded postscript file, also available through http://w4.lns.cornell.edu/public/CLN

    Measurements of the Ratios B(Ds+η+ν)/B(Ds+ϕ+ν){\cal B}(D_s^+\to \eta\ell^+\nu)/{\cal B}(D_s^+\to \phi\ell^+\nu) and B(Ds+η+ν)/B(Ds+ϕ+ν){\cal B}(D_s^+\to \eta'\ell^+\nu)/{\cal B}(D_s^+\to \phi\ell^+\nu)

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    Using the CLEO~II detector we measure B(Ds+ηe+ν)/B(Ds+ϕe+ν)=1.24±0.12±0.15{\cal B}(D_s^+\to \eta e^+\nu)/{\cal B}(D_s^+\to \phi e^+\nu) =1.24\pm0.12\pm0.15, B(Ds+ηe+ν)/B(Ds+ϕe+ν)=0.43±0.11±0.07{\cal B}(D_s^+\to \eta' e^+\nu)/{\cal B}(D_s^+\to \phi e^+\nu) =0.43\pm0.11\pm0.07 and B(Ds+ηe+ν)/B(Ds+ηe+ν)=0.35±0.09±0.07{\cal B}(D_s^+\to \eta' e^+\nu)/{\cal B}(D_s^+\to \eta e^+\nu) =0.35\pm0.09\pm0.07. We find the vector to pseudoscalar ratio, B(Ds+ϕe+ν)/B(Ds+(η+η)e+ν)=0.60±0.06±0.06{\cal B}(D_s^+\to \phi e^+\nu)/{\cal B}(D_s^+\to (\eta+\eta') e^+\nu) =0.60\pm0.06\pm0.06, which is similar to the ratio found in non strange DD decays.Comment: 11 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN
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