Semi-parametric probability-weighted moments estimation revisited

PEst-OE/MAT/UI0006/2011 PEst-OE/MAT/UI0297/2011In this paper, for heavy-tailed models and through the use of probability weighted moments based on the largest observations, we deal essentially with the semi-parametric estimation of the Value-at-Risk at a level p, the size of the loss occurred with a small probability p, as well as the dual problem of estimation of the probability of exceedance of a high level x. These estimation procedures depend crucially on the estimation of the extreme value index, the primary parameter in Statistics of Extremes, also done on the basis of the same weighted moments. Under regular variation conditions on the right-tail of the underlying distribution function F, we prove the consistency and asymptotic normality of the estimators under consideration in this paper, through the usual link of their asymptotic behaviour to the one of the extreme value index estimator they are based on. The performance of these estimators, for finite samples, is illustrated through Monte-Carlo simulations. An adaptive choice of thresholds is put forward. Applications to a real data set in the field of insurance as well as to simulated data are also provided.authorsversionpublishe

Community interactions promote Legionella pneumophila survival in drinking water biofilms

Legionella pneumophila is a waterborne pathogen that can cause Pontiac Fever or Legionnaires’ disease, a type of pneumonia that can be fatal. Although L. pneumophila is not able to replicate in low nutrient environments, such as drinking water, it is known that heterotrophic biofilms have a crucial role in the survival of this pathogen in drinking water distribution systems. The aim of this work is to study the community interactions that influence the survival of L. pneumophila in biofilms. For that, mono and dual-species biofilms of L. pneumophila and the predominant biofilm isolates Variovorax paradoxus, Mycobacterium chelonae, Acidovorax spp., Sphingomonas spp., were formed on PVC surfaces and sessile cells quantified for total cells, viable and cultivable L. pneumophila and cultivable non-Legionellae. Results demonstrated that Acidovorax spp. and Sphingomonas spp. appear to have an antagonistic effect on L. pneumophila cultivability but not in the viability, leading to the formation of viable but noncultivable (VBNC) cells, while M. chelonae increased the cultivability of this pathogen. M. chelonae is one of the microorganisms commonly found in drinking water and this work demonstrates that this strain is able to promote L. pneumophila survival in these systems. It is also demonstrated that other species might stimulate this pathogen to enter a VBNC state and consequently be underestimated in the drinking water quality control, as drinking water safety assessment still relies on standard culture techniques. It is essential for future work to study other biofilm community members to understand their ecological interactions with L. pneumophila

Resistance of legionella pneumophila and helicobacter pylori to chlorination in drinking water biofilms

The disintegration of concrete structures made of ordinary Portland cement (OPC) is a worrying topic of increasing significance. The development of new binders with longer durability is therefore needed. Alkali-activated binders have emerged as an alternative to OPC binders, which seems to have superior durability and environmental impact. This paper reviews current knowledge about alkali-activated binders. The subjects of Part 1 in this paper are historical background, terminology and hydration products. The proper terminology to designate these new binders will be discussed. The influence of the prime materials and the type of alkaline activator on the reaction mechanisms and on the nature of the reaction products will be described

Outbreak of Clostridium difficile PCR ribotype 027-the recent experience of a regional hospital

Background: Clostridium difficile infection (CDI) is the leading cause of healthcare-associated diarrhea, and several outbreaks with increased severity and mortality have been reported. In this study we report a C. difficile PCR ribotype 027 outbreak in Portugal, aiming to contribute to a better knowledge of the epidemiology of this agent in Europe. Methods: Outbreak report with retrospective study of medical records and active surveillance data of all inpatients with the diagnosis of CDI, from 1st January to 31th December 2012, in a Portuguese hospital. C. difficile isolates were characterized regarding ribotype, toxin genes and moxifloxin resistance. Outbreak control measures were taken, concerning communication, education, reinforcement of infection control measures, optimization of diagnosis and treatment of CDI, and antibiotic stewardship. Results: Fifty-three inpatients met the case definition of C. difficile-associated infection: 55% males, median age was 78.0 years (interquartile range: 71.0-86.0), 75% had co-morbidities, only 15% had a nonfatal condition, 68% had at least one criteria of severe disease at diagnosis, 89% received prior antibiotherapy, 79% of episodes were nosocomial. CDI rate peak was 13.89/10,000 bed days. Crude mortality rate at 6 months was 64.2% while CDI attributable cause was 11.3%. Worse outcome was related to older age (P = 0.022), severity criteria at diagnosis (leukocytosis (P = 0.008) and renal failure), and presence of fatal underlying condition (P = 0.025). PCR ribotype 027 was identified in 16 of 22 studied samples. Conclusions: This is the first report of a 027-CDI outbreak in Portugal. We emphasize the relevance of the measures taken to control the outbreak and highlight the importance of implementing a close and active surveillance of CDI

Influence of physico-chemical parameters on the survival of Helicobacter pylori in drinking water biofilms

The route of transmission for Helicobacter pylori is not well-known, but one of the suggested possibilities is via drinking water and associated biofilms. As such, the aim of this work is to study the influence of several physico-chemical parameters, including temperature, shear-stress and carbon concentration, on the prevalence and survival of H. pylori in drinking water biofilms. The biofilm studies were carried out using a two-stage chemostat system. The outflow culture of the first vessel fed three secondary chemostats in parallel and under different conditions of shear stress and carbon concentration. After 10 days the chemostats reached steady conditions, and the second stage chemostats were spiked with an inoculum of H. pylori NCTC 11637 (of approximately 106 cells ml-1) and PVC coupons were then immersed to allow biofilm formation. The coupons were removed at different times (up to 32 days) and biofilms detached with sterile glass beads. Planktonic and sessile cells were quantified by standard cultivation techniques (R2A and HPSPA) and SYTO9 staining. Remarkably, H. pylori lost cultivability under all conditions in less than 1 h which compares with 24-75 h that the pathogen usually takes to lose cultivability in pure culture at these temperatures. This suggests that H. pylori is negatively affected by the presence of heterotrophic microbial consortium; alternatively, overgrowth of other species might hinder colony development of H. pylori. Current studies are tracking the uncultivable H. pylori in the biofilms using peptide nucleic acid probes in a high performance fluorescence in situ hybridisation assay

Anatomic Variotions of the Paranasal Sinuses

Devido à grande proximidade dos seios perinasais (SPN) com a órbita, sistema nervoso central e outras estruturas, o cirurgião deve estar bem familiarizado com a anatomia nasossinusal. Foi efectuado um estudo retrospectivo de 150 TC-SPN realizadas no nosso centro, durante 2015. 75 exames preencheram os critérios de inclusão. Foi realizada análise de variáveis demográficas e anatómicas. A idade média foi 48 anos. Observámos agenésia em 6% dos seios frontais e hipoplasia em 15%, defeito da lâmina papirácea (LP) em 11%, deiscência da artéria etmoidal anterior em 29%, célula Onodi em 16%, exposição do nervo óptico em 28% e exposição da artéria carótida interna em 19%, entre outras variáveis avaliadas. A altura média da lamela lateral foi maior no sexo masculino. O sexo feminino correlacionou-se com hipoplasia do seio maxilar e LP medializada. Uma avaliação cuidada da TC-SPN é essencial para alcançar melhores resultados cirúrgicos e menor taxa de complicações.info:eu-repo/semantics/publishedVersio

Adenoid Cystic Carcinoma of the nasal cavity and paranasal sinuses - Restrospective review of 20 years

Objectivo: Analisar as características clinico-patológicas, tratamento e prognóstico do carcinoma adenóide quístico (CAQ) das fossas nasais e seios perinasais. Material e Métodos: Estudo retrospetivo de doentes com diagnóstico de CAQ de fossas nasais e seios perinasais do Instituto Português de Oncologia de Lisboa desde 1997 até 2016. Resultados: Foram obtidos 30 doentes, sendo 60% do sexo feminino. A idade média foi de 65 anos. O sintoma mais frequente foi obstrução nasal e o sinal mais comum foi tumefacção do palato duro. 63% dos doentes apresentavam tumor localmente avançado. O seio maxilar foi o mais atingido (87%). A invasão óssea foi a mais frequentemente identificada. Todos os doentes realizaram cirurgia com radioterapia adjuvante. Os doentes que apresentaram recorrência (50%) foram maioritariamente tratados com radioterapia. Conclusão: O CAQ das fossas nasais e seios perinasais apresenta habitualmente mau prognóstico. O tratamento cirúrgico é limitado pela recorrência local comum e tardia.info:eu-repo/semantics/publishedVersio

Antioxidant activity of sugar molasses, including protective effect against DNA oxidative damage

Extracts were obtained from molasses, a byproduct of the sugar industry, via a number of chromatographic steps. Their antioxidant capacity was studied, including the inhibitory effect upon DNA oxidative damage;the phenolic compound profile there of was ascertained as well. Two extracts exhibited significant antioxidant features, expressed by their capacity to decolorize ABTS radical cation and to scavenge hydroxyl free radicals (via deoxyribose assay). Those 2 extracts also brought about protection against induced DNA oxidative damage (via decreasing DNA scission, as assessed by electrophoresis).The phenolic compounds syringic acid,p-hydroxybenzoic acid, vanillic acid, p-hydroxybenzaldehyde, and ferulic acid were positively identified and quantified

A systematic approach to the interrogation and sharing of standardised biofilm signatures

Publicado em "6th International Conference on Practical Applications of Computational Biology & Bioinformatics", ISBN 978-3-642-28838-8The study of microorganism consortia, also known as biofilms, is associated to a number of applications in biotechnology, ecotechnology and clinical domains. A public repository on existing biofilm studies would aid in the design of new studies as well as promote collaborative and incremental work. However, bioinformatics approaches are hampered by the limited access to existing data. Scientific publications summarise the studies whilst results are kept in researchers’ private ad hoc files. Since the collection and ability to compare existing data is imperative to move forward in biofilm analysis, the present work has addressed the development of a systematic computer-amenable approach to biofilm data organisation and standardisation. A set of in-house studies involving pathogens and employing different state-of-the-art devices and methods of analysis was used to validate the approach. The approach is now supporting the activities of BiofOmics, a public repository on biofilm signatures (http://biofomics.org).The authors thank, among others, Rosario Oliveira, Maria Joao Vieira, Idalina Machado, Nuno Cerca, Mariana Henriques, Pilar Teixeira, Douglas Monteiro, Melissa Negri, Susana Lopes, Carina Almeida and Helder Lopes, for submitting their data. The financial support from IBB-CEB, Fundacao para a Ciencia e Tecnologia (FCT) and European Community fund FEDER (Program COMPETE), project PTDC/SAU-ESA/646091/2006/FCOMP-01-0124-FEDER-007480, are also gratefully acknowledged