1,282 research outputs found

    Projective quantum spaces

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    Associated to the standard SUq(n)SU_{q}(n) R-matrices, we introduce quantum spheres Sq2n1S_{q}^{2n-1}, projective quantum spaces CPqn1CP_{q}^{n-1}, and quantum Grassmann manifolds Gk(Cqn)G_{k}(C_{q}^{n}). These algebras are shown to be homogeneous quantum spaces of standard quantum groups and are also quantum principle bundles in the sense of T Brzezinski and S. Majid (Comm. Math. Phys. 157,591 (1993)).Comment: 8 page

    Development and validation of the brief esophageal dysphagia questionnaire

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    BackgroundEsophageal dysphagia is common in gastroenterology practice and has multiple etiologies. A complication for some patients with dysphagia is food impaction. A valid and reliable questionnaire to rapidly evaluate esophageal dysphagia and impaction symptoms can aid the gastroenterologist in gathering information to inform treatment approach and further evaluation, including endoscopy.Methods1638 patients participated over two study phases. 744 participants completed the Brief Esophageal Dysphagia Questionnaire (BEDQ) for phase 1; 869 completed the BEDQ, Visceral Sensitivity Index, Gastroesophageal Reflux Disease Questionnaire, and Hospital Anxiety and Depression Scale for phase 2. Demographic and clinical data were obtained via the electronic medical record. The BEDQ was evaluated for internal consistency, split‐half reliability, ceiling and floor effects, and construct validity.Key ResultsThe BEDQ demonstrated excellent internal consistency, reliability, and construct validity. The symptom frequency and severity scales scored above the standard acceptable cutoffs for reliability while the impaction subscale yielded poor internal consistency and split‐half reliability; thus the impaction items were deemed qualifiers only and removed from the total score. No significant ceiling or floor effects were found with the exception of 1 item, and inter‐item correlations fell within accepted ranges. Construct validity was supported by moderate yet significant correlations with other measures. The predictive ability of the BEDQ was small but significant.Conclusions & InferencesThe BEDQ represents a rapid, reliable, and valid assessment tool for esophageal dysphagia with food impaction for clinical practice that differentiates between patients with major motor dysfunction and mechanical obstruction.Validated, rapid clinical assessment tools for esophageal dysphagia are lacking. The brief esophageal dysphagia questionnaire aims to gauge the severity and frequency of dysphagia with additional items to gauge food impaction. The BEDQ is a reliable and valid tool to assess esophageal dysphagia.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135130/1/nmo12889.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135130/2/nmo12889_am.pd

    Gut-directed hypnotherapy significantly augments clinical remission in quiescent ulcerative colitis

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    Psychotherapy is not routinely recommended for in ulcerative colitis (UC). Gut-directed hypnotherapy (HYP) has been linked to improved function in the gastrointestinal tract and may operate through immune-mediated pathways in chronic diseases

    Ferromagnetic coupling and magnetic anisotropy in molecular Ni(II) squares

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    We investigated the magnetic properties of two isostructural Ni(II) metal complexes [Ni4Lb8] and [Ni4Lc8]. In each molecule the four Ni(II) centers form almost perfect regular squares. Magnetic coupling and anisotropy of single crystals were examined by magnetization measurements and in particular by high-field torque magnetometry at low temperatures. The data were analyzed in terms of an effective spin Hamiltonian appropriate for Ni(II) centers. For both compounds, we found a weak intramolecular ferromagnetic coupling of the four Ni(II) spins and sizable single-ion anisotropies of the easy-axis type. The coupling strengths are roughly identical for both compounds, whereas the zero-field-splitting parameters are significantly different. Possible reasons for this observation are discussed.Comment: 7 pages, 7 figure

    Predicting a Gapless Spin-1 Neutral Collective Mode branch for Graphite

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    Using the standard tight binding model of 2d graphite with short range electron repulsion, we find a gapless spin-1, neutral collective mode branch {\em below the particle-hole continuum} with energy vanishing linearly with momenta at the Γ\Gamma and KK points in the BZ. This spin-1 mode has a wide energy dispersion, 0 to 2eV\sim 2 eV and is not Landau damped. The `Dirac cone spectrum' of electrons at the chemical potential of graphite generates our collective mode; so we call this `spin-1 zero sound' of the `Dirac sea'. Epithermal neutron scattering experiments, where graphite single crystals are often used as analyzers (an opportunity for `self-analysis'!), and spin polarized electron energy loss spectroscopy (SPEELS) can be used to confirm and study our collective mode.Comment: 4 pages of LaTex file, 3 eps figure file

    Law of Genome Evolution Direction : Coding Information Quantity Grows

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    The problem of the directionality of genome evolution is studied. Based on the analysis of C-value paradox and the evolution of genome size we propose that the function-coding information quantity of a genome always grows in the course of evolution through sequence duplication, expansion of code, and gene transfer from outside. The function-coding information quantity of a genome consists of two parts, p-coding information quantity which encodes functional protein and n-coding information quantity which encodes other functional elements except amino acid sequence. The evidences on the evolutionary law about the function-coding information quantity are listed. The needs of function is the motive force for the expansion of coding information quantity and the information quantity expansion is the way to make functional innovation and extension for a species. So, the increase of coding information quantity of a genome is a measure of the acquired new function and it determines the directionality of genome evolution.Comment: 16 page

    Identifiability of flow distributions from link measurements with applications to computer networks

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    We study the problem of identifiability of distributions of flows on a graph from aggregate measurements collected on its edges. This is a canonical example of a statistical inverse problem motivated by recent developments in computer networks. In this paper (i) we introduce a number of models for multi-modal data that capture their spatio-temporal correlation, (ii) provide sufficient conditions for the identifiability of nth order cumulants and also for a special class of heavy tailed distributions. Further, we investigate conditions on network routing for the flows that prove sufficient for identifiability of their distributions (up to mean). Finally, we extend our results to directed acyclic graphs and discuss some open problems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58107/2/ip7_5_004.pd

    The Wicked Machinery of Government: Malta and the Problems of Continuity under the New Model Administration

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    This is a study focused on the early years of British rule in Malta (1800-1813). It explores the application to the island of the “new model” of colonial government, one based on direct rule from London mediated by the continuation of existing laws and institutions. Systemic deficiencies are identified. These tended to undermine the effectiveness of direct British rule. This study also reveals, in the context of legal and constitutional continuity, unresolved tensions between modernity and tradition. The political stability of the island was damaged and the possibility of continued British possession was threatened

    Neutral forces acting on intragenomic variability shape the Escherichia coli regulatory network topology

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    Cis-regulatory networks (CRNs) play a central role in cellular decision making. Like every other biological system, CRNs undergo evolution, which shapes their properties by a combination of adaptive and nonadaptive evolutionary forces. Teasing apart these forces is an important step toward functional analyses of the different components of CRNs, designing regulatory perturbation experiments, and constructing synthetic networks. Although tests of neutrality and selection based on molecular sequence data exist, no such tests are currently available based on CRNs. In this work, we present a unique genotype model of CRNs that is grounded in a genomic context and demonstrate its use in identifying portions of the CRN with properties explainable by neutral evolutionary forces at the system, subsystem, and operon levels.We leverage our model against experimentally derived data from Escherichia coli. The results of this analysis show statistically significant and substantial neutral trends in properties previously identified as adaptive in originラdegree distribution, clustering coefficient, and motifsラ within the E. coli CRN. Our model captures the tightly coupled genomeヨ interactome of an organism and enables analyses of how evolutionary events acting at the genome level, such as mutation, and at the population level, such as genetic drift, give rise to neutral patterns that we can quantify in CRNs

    Francisella tularensis RipA Protein Topology and Identification of Functional Domains

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    Francisella tularensis is a Gram-negative coccobacillus and is the etiological agent of the disease tularemia. Expression of the cytoplasmic membrane protein RipA is required for Francisella replication within macrophages and other cell types; however, the function of this protein remains unknown. RipA is conserved among all sequenced Francisella species, and RipA-like proteins are present in a number of individual strains of a wide variety of species scattered throughout the prokaryotic kingdom. Cross-linking studies revealed that RipA forms homoligomers. Using a panel of RipA-green fluorescent protein and RipA-PhoA fusion constructs, we determined that RipA has a unique topology within the cytoplasmic membrane, with the N and C termini in the cytoplasm and periplasm, respectively. RipA has two significant cytoplasmic domains, one composed roughly of amino acids 1 to 50 and the second flanked by the second and third transmembrane domains and comprising amino acids 104 to 152. RipA functional domains were identified by measuring the effects of deletion mutations, amino acid substitution mutations, and spontaneously arising intragenic suppressor mutations on intracellular replication, induction of interleukin-1β (IL-1β) secretion by infected macrophages, and oligomer formation. Results from these experiments demonstrated that each of the cytoplasmic domains and specific amino acids within these domains are required for RipA function
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