3,006 research outputs found

    The Birman-Schwinger principle in von Neumann algebras of finite type

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    We introduce a relative index for a pair of dissipative operators in a von Neumann algebra of finite type and prove an analog of the Birman-Schwinger principle in this setting. As an application of this result, revisiting the Birman-Krein formula in the abstract scattering theory, we represent the de la Harpe-Skandalis determinant of the characteristic function of dissipative operators in the algebra in terms of the relative index

    Hierarchy of Hamilton equations on Banach Lie-Poisson spaces related to restricted Grassmannian

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    Using the Magri method one defines an involutive family of Hamiltonians on Banach Lie-Poisson space iR+UL_res^1 (which contains the restricted Grassmannian as a symplectic leaf) and on its complexification C+L_res^1. The hierarchy of Hamilton equations given by these Hamiltonians is investigated. The operator equations of Ricatti-type are included in this hierarchy. For a few particular cases one gives the explicit solutions.Comment: 31 pages (some minor corrections and clarifications

    Elastic stiffening in PVA-Borax studied with experimental medium amplitude oscillatory shear

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    In this thesis, we seek to understand the mechanisms of strain-stiffening and shear-thickening often observed in transient or associative polymer hydrogels; specifically, Poly(vinyl) alcohol (PVA) crosslinked with Sodium tetraborate (Borax), or PVA-Borax. We use medium amplitude oscillatory shear (MAOS) as a tool to measure asymptotically nonlinear viscoelastic material functions across a range of compositions of PVA-Borax with storage moduli ranging from G01003000G_0 \approx 100-3000~Pa. The material functions can be related to model parameters to gain physical insight into the structure of the material system. We demonstrate that with a "good" structure-rheology model \cite{AshwinModel}, a single nonlinear parameter scales the asymptotically nonlinear material functions, and we argue that finite-extensibility is the sub-dominant cause of nonlinearity (<5<5\%) compared to stretch-induced crosslinking. Furthermore, we validate the model by using first-harmonic MAOS measures to predict third-harmonic MAOS via a single nonlinear model parameter. Finally, we define a universal nonlinear parameter to compare the strength of nonlinearities across a range of strain-stiffening materials

    Validation of the Spanish Short Self-Regulation Questionnaire (SSSRQ) through Rasch Analysis

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    The Supplementary Material for this article can be found online at: http://journal.frontiersin.org/article/10.3389/fpsyg.2017.00276/full#supplementary-materialBackground: The aim of the study was to psychometrically characterize the Spanish Short Self-Regulation Questionnaire (SSSRQ) through Rasch analysis.Materials and Methods: 831 Spaniard university students (262 men), between 17 and 39 years of age and ranging from the first to the 5th year of studies, completed the SSSRQ questionnaire. Confirmatory factor analysis (CFA) was carried out in order to establish structural adequacy. Afterward, by means of the Rasch model, a study of each sub scale was conducted to test for dimensionality, fit of the sample questions, functionality of the response categories, reliability and estimation of Differential Item Functioning by gender and course.Results: The four sub-scales comply with the unidimensionality criteria, the questions are in line with the model, the response categories operate properly and the reliability of the sample is acceptable. Nonetheless, the test could benefit from the inclusion of additional items of both high and low difficulty in order to increase construct validity, discrimination and reliability for the respondents. Several items with differences in gender and course were also identified.Discussion: The results evidence the need and adequacy of this complementary psychometric analysis strategy, in relation to the CFA to enhance the instrument.This research was funded by Fundación Universitaria Konrad Lorenz (Colombia), by a R&D Project Grant, ref. EDU2011-24805 (2012-2015) of the Ministry of Science and Innovation (Spain), and with Federal Funds (European Union)

    Clinicopathological, therapeutic and prognostic features of the triple-negative tumors in moroccan breast cancer patients (experience of Hassan II university hospital in Fez)

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    <p>Abstract</p> <p>Introduction</p> <p>Triple-negative breast cancer (TNBC) is defined as a group of breast carcinomas that are negative for expression of hormone receptors (ER, PR) and Her2, we can distinguish between two groups: basal-like (ER-, PR-, Her2-, cytokeratin (CK) 5/6+ and/or Her1+) and unclassified subtype (ER-, PR-, Her2-, Her1- and CK5/6-).</p> <p>The aim of this study is to determine the clinicopathological, histological, therapeutic and prognostic features associated with this type of breast cancer.</p> <p>Methods</p> <p>This is a retrospective study of 366 female breast cancer patients, diagnosed between January 2007 and June 2010 at the Department of Pathology. Epidemiological, clinical, histological, therapeutic and evolutive data were analyzed. OS and DFS rates were estimated by Kaplan-Meier analysis and a log-rank test to estimate outcome.</p> <p>Results</p> <p>A total of 64 women were identified as having TNBC (17.5% of all female breast cancer patients), 12.6% were basal-like, 4.9% were unclassified subtype, with a median age of 45 years. The median histological tumor diameter was 4.3 cm. TNBC were most often associated with a high grade, 49.2% grade III (53% for unclassified subtype, 47.6% for basal-like). Vascular invasion was found in 26.6% of cases (22% for unclassified subtype and 28.3% for basal-like). For the lymph node involvement: 51% had positive lymph nodes, and 22.4% had distant metastases. Neoadjuvant chemotherapy was administered to 18% patients with 26% of complete pathologic response; therefore adjuvant chemotherapy was given to 82%. 98% received anthracycline based regimen and only 30% received taxanes.</p> <p>The Kaplan-Meier curves based showed the lowest survival probability at 3-years (49% of OS, and 39% of DFS).</p> <p>Conclusion</p> <p>TNBC is associated with young age, high grade tumors, advanced stage at diagnosis, difference chemo response compared to other subtypes, and shortest survival. Critical to optimal future management is accurate identification of truly triple negative disease, and adequately powered prospective TNBC trials to establish treatment efficacy and define predictive biomarkers.</p

    Stratifying triple-negative breast cancer: which definition(s) to use?

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    Triple-negative breast cancers (TNBC) have increased rates of pathologic complete response following neoadjuvant chemotherapy, yet have poorer prognosis compared with non-TNBC. Known as the triple-negative paradox, this highlights the need to dissect the biologic and clinical heterogeneity within TNBC. In the present issue, Keam and colleagues suggest two subgroups of TNBC exist based on the proliferation-related marker Ki-67, each with differential response and prognosis following neoadjuvant chemotherapy. To place results into context, we review several definitions available under the TNBC umbrella that may stratify TNBC into clinically relevant subgroups

    Neurocognitive function in HIV infected patients on antiretroviral therapy

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    OBJECTIVE To describe factors associated with neurocognitive (NC) function in HIV-positive patients on stable combination antiretroviral therapy. DESIGN We undertook a cross-sectional analysis assessing NC data obtained at baseline in patients entering the Protease-Inhibitor-Monotherapy-Versus-Ongoing-Triple therapy (PIVOT) trial. MAIN OUTCOME MEASURE NC testing comprised of 5 domains. Raw results were z-transformed using standard and demographically adjusted normative datasets (ND). Global z-scores (NPZ-5) were derived from averaging the 5 domains and percentage of subjects with test scores >1 standard deviation (SD) below population means in at least two domains (abnormal Frascati score) calculated. Patient characteristics associated with NC results were assessed using multivariable linear regression. RESULTS Of the 587 patients in PIVOT, 557 had full NC results and were included. 77% were male, 68% Caucasian and 28% of Black ethnicity. Mean (SD) baseline and nadir CD4+ lymphocyte counts were 553(217) and 177(117) cells/µL, respectively, and HIV RNA was <50 copies/mL in all. Median (IQR) NPZ-5 score was -0.5 (-1.2/-0) overall, and -0.3 (-0.7/0.1) and -1.4 (-2/-0.8) in subjects of Caucasian and Black ethnicity, respectively. Abnormal Frascati scores using the standard-ND were observed in 51%, 38%, and 81%, respectively, of subjects overall, Caucasian and Black ethnicity (p<0.001), but in 62% and 69% of Caucasian and Black subjects using demographically adjusted-ND (p = 0.20). In the multivariate analysis, only Black ethnicity was associated with poorer NPZ-5 scores (P<0.001). CONCLUSIONS In this large group of HIV-infected subjects with viral load suppression, ethnicity but not HIV-disease factors is closely associated with NC results. The prevalence of abnormal results is highly dependent on control datasets utilised. TRIAL REGISTRY ClinicalTrials.gov, NCT01230580

    WILEARN

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    El presente proyecto fue desarrollado al identificar la necesidad de los estudiantes universitarios con respecto a contar con un servicio que pueda brindarle herramientas que le ayuden a mejorar sus resultados académicos, además de desarrollar competencias que puedan ser de ayuda para potenciar su empleabilidad, sobre todo para alumnos que se encuentran en búsqueda de prácticas y oportunidades laborales. Teniendo esto en cuenta, se ha desarrollado esta idea de negocio que se enfoca en reunir estas herramientas en una app que permita a estudiantes universitarios acceder a estas. La propuesta tiene el nombre de wiLearn, que representa la idea de un aprendizaje en conjunto.  wiLearn de enfoca en un mercado compuesto por estudiantes universitarios de 18 a años, pertenecientes al NSE A y B que buscan mejorar su rendimiento académico y complementar sus conocimientos para aumentar su nivel de empleabilidad. Para validar este proyecto, se han realizado diversos experimentos que comprueben la viabilidad de la idea de negocio. Además, se ha analizado financieramente para determinar la rentabilidad, los requerimientos para el desarrollo de esta idea de negocio y, sobre todo, dar a conocer esta nueva alternativa de refuerzo académico y profesional.This project was created by the need for college students' concerns, which focuses on services that can help them improve their academic results and develop skills that can enhance their employability, internships, and most importantly, job opportunities. Thus, by keeping in mind the students' concerns, a new business idea has been developed to strategically bring these tools together in an application (App) to facilitate students' access to assist them with their needs.  Furthermore, the name of this proposal App is wiLearn, which represents teamwork learning. wiLearn focuses on a market made for 18-year-old college students from NSE A and B who seek to improve their academic performance and improve their knowledge to increase their employability level. Lastly, in order to validate this project, various experiments have been implemented to verify the business idea's viability. Additionally, a deeply financial analysis was developed to determine the cost-effectiveness and the requirements for developing this business idea. Therefore, it will allow how to publicize this new alternative of academic and professional reinforcement.Trabajo de investigació
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