Quadratic optimal functional quantization of stochastic processes and numerical applications

In this paper, we present an overview of the recent developments of functional quantization of stochastic processes, with an emphasis on the quadratic case. Functional quantization is a way to approximate a process, viewed as a Hilbert-valued random variable, using a nearest neighbour projection on a finite codebook. A special emphasis is made on the computational aspects and the numerical applications, in particular the pricing of some path-dependent European options.Comment: 41 page

Cross-sectional measures and modelled estimates of blood alcohol levels in UK nightlife and their relationships with drinking behaviours and observed signs of inebriation

<p>Abstract</p> <p>Background</p> <p>Management of nightlife in UK cities focuses on creating safe places for individuals to drink. Little is known about intoxication levels as measuring total alcohol consumption on nights out is complicated by early evening interviews missing subsequent consumption and later interviews risking individuals being too drunk to recall consumption or participate at all. Here we assess mixed survey and modelling techniques as a methodological approach to examining these issues.</p> <p>Methods</p> <p>Interviews with a cross sectional sample of nightlife patrons (n = 214) recruited at different locations in three cities established alcohol consumption patterns up to the point of interview, self-assessed drunkenness and intended drinking patterns throughout the remaining night out. Researchers observed individuals' behaviours to independently assess drunkenness. Breath alcohol tests and general linear modelling were used to model blood alcohol levels at participants' expected time of leaving nightlife settings.</p> <p>Results</p> <p>At interview 49.53% of individuals regarded themselves as drunk and 79.43% intended to consume more alcohol before returning home, with around one in ten individuals (15.38% males; 4.35% females) intending to consume >40 units (equal to 400 mls of pure alcohol). Self-assessed drunkenness, researcher observed measures of sobriety and blood alcohol levels all correlated well. Modelled estimates for blood alcohol at time of going home suggested that 71.68% of males would be over 0.15%BAC (gms alcohol/100 mls blood). Higher blood alcohol levels were related to drinking later into the night.</p> <p>Conclusions</p> <p>UK nightlife has used substantive health and judicial resources with the aim of creating safer and later drinking environments. Survey and modelling techniques together can help characterise the condition of drinkers when using and leaving these settings. Here such methods identified patrons as routinely getting drunk, with risks of drunkenness increasing over later nights. Without preventing drunkenness and sales to intoxicated individuals, extended drinking hours can simply act as havens for drunks. A public health approach to nightlife is needed to better understand and take into account the chronic effects of drunkenness, the damages arising after drunk individuals leave city centres and the costs of people avoiding drunken city centres at night.</p

Prevalência de acidentes de trânsito auto-referidos em Rio Branco, Acre

OBJETIVO: Estimar a prevalência de acidentes de trânsito auto-referidos e identificar fatores associados. MÉTODOS: Estudo transversal de base populacional realizado de setembro de 2007 a agosto de 2008, nas zonas urbana e rural de Rio Branco, AC. Foram analisados dados referentes aos adultos (18 a 96 anos, n = 1.516) do inquérito Saúde e Nutrição de Adultos e Crianças de Rio Branco, obtidos em entrevistas domiciliares. As relações entre acidente de trânsito auto-referido e variáveis socioeconômicas e comportamentais foram analisadas por meio de razões de prevalência e intervalos de 95% de confiança; foi efetuada análise de regressão múltipla de Poisson. RESULTADOS: A prevalência de acidente de trânsito auto-referido foi de 36%. Na análise de Poisson, os indivíduos do sexo masculino (RP=1,45 e IC95%: 1,12;1,87), que relatavam consumo de bebida alcoólica (RP=1,25 e IC95%: 0,97;1,62), com renda acima de cinco salários mínimos (RP=1,88 e IC95%: 1,25;2,83), idade entre 18 e 25 anos (RP=1,45 e IC95%: 1,02;2,05) apresentaram maior probabilidade de referir envolvimento em acidente de trânsito. As variáveis idade e escolaridade mostraram associação inversa com o desfecho, enquanto renda apresentou associação positiva, todas elas com tendência significativa. CONCLUSÕES: A prevalência dos acidentes de trânsito auto-referidos aponta risco mais elevado para homens, com renda mais elevada, menor escolaridade e que ingerem bebida alcoólica, os quais devem ser alvo das campanhas preventivas.OBJETIVO: Estimar la prevalencia de accidentes de tránsito auto-referidos e identificar factores asociados. MÉTODOS: Estudio transversal de base poblacional realizado de septiembre de 2007 a agosto de 2008, en las zonas urbana y rural de Rio Branco, Norte de Brasil. Se analizaron datos referentes a los adultos (18 a 96 años, n=1.516) de la Pesquisa Salud y Nutrición de Adultos y Niños de Rio Branco, obtenidos en entrevistas domiciliares. Las relaciones entre accidente de tránsito auto-referido y variables socioeconómicas y conductuales fueron analizadas por medio de tasas de prevalencia e intervalos de 95% de confianza. El análisis multivariado fue efectuado por medio de la regresión de Poisson. RESULTADOS: La prevalencia de accidente de tránsito auto-referido fue de 36%. En el análisis multivariado, los individuos del sexo masculino (RP 1,45 e IC95%: 1,12;1,87), que relataban consumo de bebida alcohólica (RP 1,25 e IC95%: 0,97;1,62), con renta superior a cinco salarios mínimos (RP 1,88 e IC95%: 1,25;2,83), edad entre 18 y 25 años (RP 1,45 e IC95%: 1,02;2,05) presentaron mayor probabilidad de referir envolvimiento en accidente de tránsito. Las variables edad y escolaridad mostraron asociación inversa con el resultado, mientras que renta presentó asociación positiva, todas ellas con tendencia significativa. CONCLUSIONES: La prevalencia de los accidentes de tránsito auto-referidos, señalan riesgo más elevado para hombres, con renta más elevada, menor escolaridad y que ingieren bebida alcohólica, siendo ellos el blanco de las campañas preventivas.OBJECTIVE: To estimate the prevalence of self-reported traffic accidents and identify associated factors. METHODS: Cross-sectional, population-based study carried out from September 2007 to August 2008, in the urban and rural zones of Rio Branco (Northern Brazil). Data referring to adults (aged 18 to 96 years, n = 1,516) of the inquiry Health and Nutrition of Adults and Children of Rio Branco, obtained in home interviews, were analyzed. The relations between self-reported traffic accident and socioeconomic and behavior variables were analyzed by means of prevalence ratios and 95% confidence intervals; Poisson regression analysis was performed. RESULTS: The prevalence of self-reported traffic accident was 36%. In the Poisson analysis, male individuals (PR= 1.45 and 95% CI: 1.12;1.87) who reported alcohol consumption (PR= 1.25 and 95%CI: 0.97;1.62), with income above five minimum wages (PR= 1.88 and 95%CI: 1.25;2.83), aged between 18 and 25 years (PR= 1.45 and 95%CI: 1.02;2.05), presented higher probability of reporting involvement in traffic accidents. The variables age and level of schooling had inverse association with the outcome, while income had a positive association, all of them with significant tendency. CONCLUSIONS: The prevalence of self-reported traffic accidents shows higher risk for men with higher income, lower level of schooling and who ingest alcoholic beverages. They should be the target of prevention campaigns

Astrocytes: biology and pathology

Astrocytes are specialized glial cells that outnumber neurons by over fivefold. They contiguously tile the entire central nervous system (CNS) and exert many essential complex functions in the healthy CNS. Astrocytes respond to all forms of CNS insults through a process referred to as reactive astrogliosis, which has become a pathological hallmark of CNS structural lesions. Substantial progress has been made recently in determining functions and mechanisms of reactive astrogliosis and in identifying roles of astrocytes in CNS disorders and pathologies. A vast molecular arsenal at the disposal of reactive astrocytes is being defined. Transgenic mouse models are dissecting specific aspects of reactive astrocytosis and glial scar formation in vivo. Astrocyte involvement in specific clinicopathological entities is being defined. It is now clear that reactive astrogliosis is not a simple all-or-none phenomenon but is a finely gradated continuum of changes that occur in context-dependent manners regulated by specific signaling events. These changes range from reversible alterations in gene expression and cell hypertrophy with preservation of cellular domains and tissue structure, to long-lasting scar formation with rearrangement of tissue structure. Increasing evidence points towards the potential of reactive astrogliosis to play either primary or contributing roles in CNS disorders via loss of normal astrocyte functions or gain of abnormal effects. This article reviews (1) astrocyte functions in healthy CNS, (2) mechanisms and functions of reactive astrogliosis and glial scar formation, and (3) ways in which reactive astrocytes may cause or contribute to specific CNS disorders and lesions