73 research outputs found

    Nonlinear Polariton Fluids in a Flatband Reveal Discrete Gap Solitons

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    Phase frustration in periodic lattices is responsible for the formation of dispersionless flat bands. The absence of any kinetic energy scale makes flat band physics critically sensitive to perturbations and interactions. We report here on the experimental investigation of the nonlinear dynamics of cavity polaritons in the gapped flat band of a one-dimensional Lieb lattice. We observe the formation of gap solitons with quantized size and very abrupt edges, signature of the frozen propagation of switching fronts. This type of gap solitons belongs to the class of truncated Bloch waves, and had only been observed in closed systems up to now. Here the driven-dissipative character of the system gives rise to a complex multistability of the nonlinear domains generated in the flat band. These results open up interesting perspective regarding more complex 2D lattices and the generation of correlated photon phases.Comment: 6 pages, 4 figures + supplemental material (6 pages, 6 figures

    From publishers to self-publishing: disruptive effects in the book industry

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    This paper explores the structure of the book publishing industry post digitalisation, analysing the choices of the publishers and authors. The introduction of successful e-book readers has belatedly given digitalisation the characteristics of a disruptive technology by making self-publishing a serious option for authors. This has been supported by the entry of new types of intermediaries and the strengthening of others. These changes have reduced the general requirements for an author to get a book self-published. As a result, a larger share of the surplus from the book industry is likely to go to authors, explaining the significant increase in the supply of books. The potential oversupply of books has created a new problem by increasing competition and making consumer searches more difficult. We argue that digitalisation has shifted the potential for market failure from an inadequate supply of books to asymmetric information about quality. It remains to be seen whether the market will provide appropriate intermediaries to solve the asymmetric information problem

    ‘Medusa head ataxia’: the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 3: Anti-Yo/CDR2, anti-Nb/AP3B2, PCA-2, anti-Tr/DNER, other antibodies, diagnostic pitfalls, summary and outlook

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    Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as ‘Medusa head antibodies’ due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook

    ‘Medusa head ataxia’: the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 3: Anti-Yo/CDR2, anti-Nb/AP3B2, PCA-2, anti-Tr/DNER, other antibodies, diagnostic pitfalls, summary and outlook

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    Comparison of clinical practice guidelines from a knowledge modelling perspective: a case study with the management of hypertension.

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    Hypertension, as a cardiovascular risk factor, is a public health issue for which many clinical practice guidelines (CPGs) are published. In order to build the knowledge base of a clinical decision support system for the management of hypertension, we analysed three contemporary (2013) CPGs written in French on hypertension in a knowledge modelling perspective. We developed a semi-automated method using natural language processing called term extraction. Relevant candidate terms have been mapped to medical concepts to produce the conceptual coverage of each CPG. Only 53% of the 88 identified concepts were shared by the three guidelines. While sharing concepts does not warrantee that CPGs contents are similar, this also emphasizes guideline specificities. Such specificities could enrich the knowledge base of decision support systems by broadening their scope

    Clinical practice guidelines consistency for patients with multimorbidity: a case-study in the management of type 2 diabetes and hypertension.

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    Decision support for the guideline-based management of patients with multimorbidity is a challenge since it relies on the combination of single-disease clinical practice guidelines (CPGs). The aim of this work is to present a framework to check, at the modelling level, whether two CPGs overlap and are potentially inconsistent, thus requiring further reconciliation. The method relies on an ontological comparison of the patient profiles covered by CPGs and the recommended actions attached. It was applied to check the consistency of CPGs for the management of arterial hypertension and for the management of type 2 diabetes. Results showed that the two CPGs had only one common patient profile, although more profiles were impacted through profile subsumption. In this specific case, recommended actions were not found inconsistent since antihypertensive and anti-diabetic drugs could be combined in an additive way

    An Ontology-Based Clinical Decision Support System for the Management of Patients with Multiple Chronic Disorders.

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    Decision support systems, as means of disseminating clinical practice guidelines, are powerful software that may lead to an improvement of medical practices. However, they are not always efficient and may suffer from limitations among which are lack of flexibility and weaknesses in the integration of several clinical practice guidelines (CPGs) for the management of patients with multiple chronic disorders. We propose a framework based on an ontological modeling of CPG contents as rules. The ontology provides the required flexibility to adapt patient data and enable the provision of appropriate recommendations expressed at various levels of abstraction. To solve decisional conflicts that occur when combining multiple sources of recommendations, we proposed a method based on the subsumption graph of the patient profiles corresponding to the rules. A prototype CDSS implementing this approach has been developed. Results are given on a clinical case to illustrate the assets of ontological reasoning in increasing the number of issued recommendations and thereby the reliability of decision support

    Using an ontological modeling to evaluate the consistency of clinical practice guidelines: application to the comparison of three guidelines on the management of adult hypertension.

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    Every year, numerous clinical practice guidelines (CPGs) are published on a same topic. They may be conflicting, thus infringing clinicians' confidence in adhering to them. In order to build a clinical decision support system to assist GPs in the management of hypertension, we have considered three recent CPGs written in French. We developed a methodological framework to evaluate how consistent the three CPGs were. After a manual extraction of recommendation rules, all patient profiles covered by the CPGs have been identified. Then, ontological modeling and reasoning were used to build a subsumption graph of all profiles. This graph allows the retrieval of recommendations that could be conflicting. Results show that if rules are different in the three CPGs according to a document-based approach, many profiles are related through subsumption, and no critical inconsistencies were discovered when implementing an ontological modeling

    Design of a Fine-Grained Knowledge Model for the Formalization of Clinical Practice Guidelines: Comparison with GEM.

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    Published as textual documents, clinical practice guidelines (CPGs) didn't demonstrate to impact physician practices when disseminated in their original format. However, when computerized and embedded in clinical decision support systems, they appeared to be more effective. In order to ease the translation from textual to computerized CPGs, we have elaborated a fine-grained knowledge model of CPGs (FGKM) to be used when authoring CPGs. The work has been conducted on VIDALRecos® CPGs. The building of the model has followed a bottom-up iterative process starting with 15 different CPGs. The first version of the FGKM has been assessed on two new complex CPGs, and was enriched by comparison with the Guideline Elements Model (GEM). The final version of the FGKM has been tested on the 2014 Hypertension CPGs. We compared the rules automatically derived from FGKM instances to those manually extracted from textual CPGs for decision support. Results showed that difficulties such as text normalization have to be solved. The FGKM is intended to be used upstream of the process of CPGs authoring in order to ease the implementation and the update of both textual and computerized CPGs
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