1,189 research outputs found

    On fundamental groups related to the Hirzebruch surface F_1

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    Given a projective surface and a generic projection to the plane, the braid monodromy factorization (and thus, the braid monodromy type) of the complement of its branch curve is one of the most important topological invariants, stable on deformations. From this factorization, one can compute the fundamental group of the complement of the branch curve, either in C^2 or in CP^2. In this article, we show that these groups, for the Hirzebruch surface F_{1,(a,b)}, are almost-solvable. That is - they are an extension of a solvable group, which strengthen the conjecture on degeneratable surfaces.Comment: accepted for publication at "Sci. in China, ser. Math"; 22 pages, 11 figure

    Assessing the UK policies for broadband adoption

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    Broadband technology has been introduced to the business community and the public as a rapid way of exploiting the Internet. The benefits of its use (fast reliable connections, and always on) have been widely realised and broadband diffusion is one of the items at the top of the agenda for technology related polices of governments worldwide. In this paper an examination of the impact of the UK government’s polices upon broadband adoption is undertaken. Based on institutional theory a consideration of the manipulation of supply push and demand pull forces in the diffusion of broadband is offered. Using primary and secondary data sources, an analysis of the specific institutional actions related to IT diffusion as pursued by the UK government in the case of broadband is provided. Bringing the time dimension into consideration it is revealed that the UK government has shifted its attention from supply push-only strategies to more interventional ones where the demand pull forces are also mobilised. It is believed that this research will assist in the extraction of the “success factors” in government intervention that support the diffusion of technology with a view to render favourable results if applied to other national settings

    Epileptiform Activity in Alcohol Dependent Patients and Possibilities of Its Indirect Measurement

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    Background: Alcohol dependence during withdrawal and also in abstinent period in many cases is related to reduced inhibitory functions and kindling that may appear in the form of psychosensory symptoms similar to temporal lobe epilepsy frequently in conditions of normal EEG and without seizures. Because temporal lobe epileptic activity tend to spread between hemispheres, it is possible to suppose that measures reflecting interhemispheric information transfer such as electrodermal activity (EDA) might be related to the psychosensory symptoms. Methods and Findings: We have performed measurement of bilateral EDA, psychosensory symptoms (LSCL-33) and alcohol craving (ACQ) in 34 alcohol dependent patients and 32 healthy controls. The results in alcohol dependent patients show that during rest conditions the psychosensory symptoms (LSCL-33) are related to EDA transinformation (PTI) between left and right EDA records (Spearman r = 0.44, p,0.01). Conclusions: The result may present potentially useful clinical finding suggesting a possibility to indirectly assess epileptiform changes in alcohol dependent patients

    BĂșsqueda por similaridad aplicada en la recuperaciĂłn de factores que inciden en el cĂĄlculo del Ă­ndice de riesgo para la salud de la vivienda urbana

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    El proyecto RNA-AC es el resultado de un convenio de cooperaciĂłn entre la UTN-CĂłrdoba y el Instituto de Investigaciones Geo-HistĂłricas de la Provincia del Chaco (IIGHI-CONICET). Este Ășltimo trabaja en un modelo conceptual mediante el cual busca determinar en quĂ© forma influyen ciertos factores en el riesgo para la salud humana en contextos urbanos. No se conocen expresiones matemĂĄticas que formalicen las relaciones entre los factores citados y el riesgo final, y los investigadores de la UTN-CĂłrdoba abordaron el problema computacionalmente. Primero, se planteĂł un modelo de redes neuronales capaz de captar los datos de los factores incidentes, para luego afinar esta red para que pueda identificar las relaciones entre dichos factores y el Ă­ndice final de riesgo. Segundo, para lograr una perspectiva mĂĄs amplia y disponer de tĂ©cnicas alternativas para identificar relaciones, se planteĂł otro modelo computacional mediante bĂșsqueda por similaridad, como parte del subproyecto RNA-EH. AquĂ­ exponemos el trabajo realizado en ese subproyecto, basado en los mismos datos y referencias usados en el proyecto marco RNA-AC, pero desarrollado “en paralelo” y sin cruce de resultados hasta su culminaciĂłn. Se espera con esto, poder comprobar cada modelo computacional desarrollado y efectuar comparaciones de rendimiento, ventajas, desventajas y potencialidades.Sociedad Argentina de InformĂĄtica e InvestigaciĂłn Operativ

    The diacylglycerol kinase α/Atypical PKC/ÎČ1 integrin pathway in SDF-1α mammary carcinoma invasiveness

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    Diacylglycerol kinase α (DGKα), by phosphorylating diacylglycerol into phosphatidic acid, provides a key signal driving cell migration and matrix invasion. We previously demonstrated that in epithelial cells activation of DGKα activity promotes cytoskeletal remodeling and matrix invasion by recruiting atypical PKC at ruffling sites and by promoting RCP-mediated recycling of α5ÎČ1 integrin to the tip of pseudopods. In here we investigate the signaling pathway by which DGKα mediates SDF-1α-induced matrix invasion of MDA-MB-231 invasive breast carcinoma cells. Indeed we showed that, following SDF-1α stimulation, DGKα is activated and localized at cell protrusion, thus promoting their elongation and mediating SDF-1α induced MMP-9 metalloproteinase secretion and matrix invasion. Phosphatidic acid generated by DGKα promotes localization at cell protrusions of atypical PKCs which play an essential role downstream of DGKα by promoting Rac-mediated protrusion elongation and localized recruitment of ÎČ1 integrin and MMP-9. We finally demonstrate that activation of DGKα, atypical PKCs signaling and ÎČ1 integrin are all essential for MDA-MB-231 invasiveness. These data indicates the existence of a SDF-1α induced DGKα - atypical PKC - ÎČ1 integrin signaling pathway, which is essential for matrix invasion of carcinoma cells
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