2,190 research outputs found

    MAVL/StickWRLD: analyzing structural constraints using interpositional dependencies in biomolecular sequence alignments

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    The increasing availability of structurally aligned protein families has made it possible to use statistical methods to discover regions of interpositional dependencies of residue identity. Such dependencies amongst residues often have structural or functional implications, and their discovery can supply valuable constraints that assist in the refinement of measured, or predicted molecular structure assignments. Multiple Alignment Variation Linker (MAVL) and StickWRLD [W. Ray (2004) Nucleic Acids Res., 32, W59–W63] were developed to analyze and visualize nucleic acid and protein alignments, to discover and illuminate position/location relationships to the user. The original system analyzed users' data from a web-form submission and presented the user with a static VRML diagram describing their data. We are pleased to report that MAVL/StickWRLD has been completely redesigned and rewritten. MAVL/StickWRLD now functions as a platform-independent Java applet, with real-time dynamic controls that enable much more intuitive exploration and interaction with the data. The system has also been upgraded to enable visualization of a range of aggregate residue properties, and an extensive database of pre-computed StickWRLD diagrams based on PFAM families is now available directly from the interface. The Java StickWRLD applet is available via the WWW at

    A Cross-cultural Qualitative Examination of Social-networking Sites and Academic Performance

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    AbstractSocial-networking site (SNS) use, specifically Facebook®, has remained a controversial subject for many educators and media. Recent studies discuss the negative and positive impacts of SNSs on students’ academic performance. This qualitative study examines the impact of SNSs on students’ academic performance via open-ended survey responses in the United States (US) and Europe. Responses were examined using the Qualitative Content Analysis (QCA). Findings from this study indicate the differences in perceptions between students in the US and Europe. Overall, common themes indicated that the majority of students claimed they feel SNSs do not impact their grades. Many European students (32.0%) indicated that they use SNSs for their school work, whereas 31.7% of US students mentioned being a responsible student

    Supernovae Ia Constraints on a Time-Variable Cosmological "Constant"

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    The energy density of a scalar field ϕ\phi with potential V(ϕ)ϕαV(\phi) \propto \phi^{-\alpha}, α>0\alpha > 0, behaves like a time-variable cosmological constant that could contribute significantly to the present energy density. Predictions of this spatially-flat model are compared to recent Type Ia supernovae apparent magnitude versus redshift data. A large region of model parameter space is consistent with current observations. (These constraints are based on the exact scalar field model equations of motion, not on the widely used time-independent equation of state fluid approximation equations of motion.) We examine the consequences of also incorporating constraints from recent measurements of the Hubble parameter and the age of the universe in the constant and time-variable cosmological constant models. We also study the effect of using a non-informative prior for the density parameter.Comment: Accepted for publication in Ap

    Radiological staging in neuroblastoma : computed tomography or magnetic resonance imaging?

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    Purpose: To compare the effectiveness of computed tomography (CT) and magnetic resonance imaging (MRI) in the staging of neuroblastomas according to the International Neuroblastoma Risk Group Staging System (INRGSS). Material and methods: In this single-centre retrospective study we identified a total of 20 patients under the age of 18 years, who were admitted to our hospital with neuroblastoma between January 2005 and May 2018, and who had both CT and MRI examination. The INRGSS stages of tumours were evaluated by CT scan and MRI. Then, stages of tumours were described according to the INRGSS for CT and MRI, separately. The Spearman rank correlation test was used for statistical analysis. The p-value < 0.05 was considered as statistically significant. Results: The median age was 11 months, and the age range was one month to nine years. In our results; both MRI and CT were significant in the determination of radiological staging of NBL, p < 0.001 and p = 0.002, respectively. MRI was superior to CT in radiological staging. MRI was also superior for the detection of intraspinal extension, involvement of multiple body compartments, metastatic disease, and bone marrow infiltration. CT was more useful to consider the relationship between tumours and vascular structures. Conclusions: MRI and CT have high diagnostic accuracy rates in the staging of pre-treatment neuroblastomas. MRI is important in pre-treatment evaluation of neuroblastomas because of the higher detection of metastases as well as the lack of ionising radiation

    Scaling Cosmologies from Duality Twisted Compactifications

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    Oscillating moduli fields can support a cosmological scaling solution in the presence of a perfect fluid when the scalar field potential satisfies appropriate conditions. We examine when such conditions arise in higher-dimensional, non-linear sigma-models that are reduced to four dimensions under a generalized Scherk-Schwarz compactification. We show explicitly that scaling behaviour is possible when the higher-dimensional action exhibits a global SL(n,R) or O(2,2) symmetry. These underlying symmetries can be exploited to generate non-trivial scaling solutions when the moduli fields have non-canonical kinetic energy. We also consider the compactification of eleven-dimensional vacuum Einstein gravity on an elliptic twisted torus.Comment: 21 pages, 3 figure

    The Operator Product Expansion of the Lowest Higher Spin Current at Finite N

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    For the N=2 Kazama-Suzuki(KS) model on CP^3, the lowest higher spin current with spins (2, 5/2, 5/2,3) is obtained from the generalized GKO coset construction. By computing the operator product expansion of this current and itself, the next higher spin current with spins (3, 7/2, 7/2, 4) is also derived. This is a realization of the N=2 W_{N+1} algebra with N=3 in the supersymmetric WZW model. By incorporating the self-coupling constant of lowest higher spin current which is known for the general (N,k), we present the complete nonlinear operator product expansion of the lowest higher spin current with spins (2, 5/2, 5/2, 3) in the N=2 KS model on CP^N space. This should coincide with the asymptotic symmetry of the higher spin AdS_3 supergravity at the quantum level. The large (N,k) 't Hooft limit and the corresponding classical nonlinear algebra are also discussed.Comment: 62 pages; the footnotes added, some redundant appendices removed, the presentations in the whole paper improved and to appear in JHE

    Highly stable defective TiO2-x with tuned exposed facets induced by fluorine: Impact of surface and bulk properties on selective UV/visible alcohol photo-oxidation

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    Titanium dioxide samples were prepared in the presence of different amounts of fluorine via hydrothermal method. It has been found that the presence of fluoride influenced the physico-chemical properties of TiO2 in various ways as polymorphic form stability, surface hydroxylation, generation of hydroxyl radicals under irradiation and formation of Ti3+ centers and oxygen vacancies. The generation rate of [rad]OH radicals was investigated by the photoluminescence technique in the presence of terephthalic acid. X-ray diffractometry indicated that fluorine stabilized the anatase TiO2. X-Ray photoelectron spectroscopy (XPS) revealed the presence of fluorine on the surface and the shift of the valence band edge towards less negative potentials, electron paramagnetic resonance (EPR) confirmed the formation of Ti3+ in the bulk of the photocatalysts, UV–vis spectra showed the extension of the TiO2 photo-response in the visible light region. 2-Propanol degradation and 4-methoxybenzyl alcohol partial oxidation were studied as probe reactions by using the home prepared powders as photocatalysts. Surprisingly, the photocatalytic activity resulted to be mainly affected by [rad]OH radicals formation ability under irradiation, rather than by the presence of {0 0 1} facets, although it cannot be excluded that the latter could influence the ability to form radicals under irradiation
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