1,189 research outputs found
On fundamental groups related to the Hirzebruch surface F_1
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
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Assessing the UK policies for broadband adoption
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 governmentâs 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 âsuccess factorsâ in government intervention that support the diffusion of technology with a view to render favourable results if applied to other national settings
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Developmental exposures to perfluorooctanesulfonic acid (PFOS) impact embryonic nutrition, pancreatic morphology, and adiposity in the zebrafish, \u3cem\u3eDanio rerio\u3c/em\u3e
Perfluorooctanesulfonic acid (PFOS) is a persistent environmental contaminant previously found in consumer surfactants and industrial fire-fighting foams. PFOS has been widely implicated in metabolic dysfunction across the lifespan, including diabetes and obesity. However, the contributions of the embryonic environment to metabolic disease remain uncharacterized. This study seeks to identify perturbations in embryonic metabolism, pancreas development, and adiposity due to developmental and subchronic PFOS exposures and their persistence into later larval and juvenile periods. Zebrafish embryos were exposed to 16 or 32 ÎŒM PFOS developmentally (1â5 days post fertilization; dpf) or subchronically (1â15 dpf). Embryonic fatty acid and macronutrient concentrations and expression of peroxisome proliferator-activated receptor (PPAR) isoforms were quantified in embryos. Pancreatic islet morphometry was assessed at 15 and 30 dpf, and adiposity and fish behavior were assessed at 15 dpf. Concentrations of lauric (C12:0) and myristic (C14:0) saturated fatty acids were increased by PFOS at 4 dpf, and PPAR gene expression was reduced. Incidence of aberrant islet morphologies, principal islet areas, and adiposity were increased in 15 dpf larvae and 30 dpf juvenile fish. Together, these data suggest that the embryonic period is a susceptible window of metabolic programming in response to PFOS exposures, and that these early exposures alone can have persisting effects later in the lifecourse
Epileptiform Activity in Alcohol Dependent Patients and Possibilities of Its Indirect Measurement
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
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 âen paraleloâ 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
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Childhood Maltreatment, Depression, and Suicidal Ideation: Critical Importance of Parental and Peer Emotional Abuse during Developmental Sensitive Periods in Males and Females
Background: The adverse childhood experience (ACE) study found that risk for depression increased as a function of number of types of childhood maltreatment, and interpret this as a result of cumulative stress. An alternative hypothesis is that risk depends on type and timing of maltreatment. This will also present as a linear increase, since exposure to more types of abuse increases likelihood of experiencing a critical type of abuse at a critical age. Methods: 560 (223M/337F) young adults (18â25 years) were recruited from the community without regard to diagnosis and balanced to have equal exposure to 0â4 plus types of maltreatment. The Maltreatment and Abuse Chronology of Exposure Scale assessed severity of exposure to 10 types of maltreatment across each year of childhood. Major depressive disorder (MDD) and current symptoms were evaluated by SCID, interview, and self-report. Predictive analytics assessed importance of exposure at each age and evaluated whether exposure at one or two ages was a more important predictor than number, severity, or duration of maltreatment across childhood. Results: The most important predictors of lifetime history of MDD were non-verbal emotional abuse in males and peer emotional abuse (EA) in females at 14 years of age, and these were more important predictors across models than number of types of maltreatment (males: t9 = 16.39, p < 10-7; females t9 = 5.78, p < 10-4). Suicidal ideation was predicted, in part, by NVEA and peer EA at age 14, but most importantly by parental verbal abuse at age 5 in males and sexual abuse at age 18 in females. Conclusion: This study provides evidence for sensitive exposure periods when maltreatment maximally impacts risk for depression, and provides an alternative interpretation of the ACE study results. These findings fit with emerging neuroimaging evidence for regional sensitivity periods. The presence of sensitive exposure periods has important implications for prevention, preemption, and treatment of MDD
The diacylglycerol kinase α/Atypical PKC/ÎČ1 integrin pathway in SDF-1α mammary carcinoma invasiveness
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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