Comportamento dinâmico de pontes pedonais de madeira

Na Parte 2 do Eurocódigo 5 é proposto, para tipologias correntes, um processo simplificado de verificação do estado-limite de vibração para pontes de madeira sujeitas à acção de grupos de peões, o qual utiliza estimativas do valor máximo da aceleração no tabuleiro. Neste trabalho procede-se à comparação entre os valores determinados por esse método e os obtidos por análise dinâmica de modelos numéricos de Elementos Finitos, sob a acção de grupos de peões de dimensão e frequência de passada variáveis. Descrevem-se ainda os modelos probabilísticos utilizados na geração do carregamento dinâmico correspondente a estes grupos

Questioning the proverb ‘more haste, less speed’: classic versus metabarcoding approaches for the diet study of a remote island endemic gecko

Dietary studies can reveal valuable information on how species exploit their habitats and are of particular importance for insular endemics conservation as these species present higher risk of extinction. Reptiles are often neglected in island systems, principally the ones inhabiting remote areas, therefore little is known on their ecological networks. The Selvagens gecko Tarentola (boettgeri) bischoffi, endemic to the remote and integral reserve of Selvagens Archipelago, is classified as Vulnerable by the Portuguese Red Data Book. Little is known about this gecko’s ecology and dietary habits, but it is assumed to be exclusively insectivorous. The diet of the continental Tarentola species was already studied using classical methods. Only two studies have used next-generation sequencing (NGS) techniques for this genus thus far, and very few NGS studies have been employed for reptiles in general. Considering the lack of information on its diet and the conservation interest of the Selvagens gecko, we used morphological and DNA metabarcoding approaches to characterize its diet. The traditional method of morphological identification of prey remains in faecal pellets collected over a longer period was compared with metabarcoding of samples collected during rapid surveys. Molecular results revealed that this species is a generalist, feeding on invertebrate, plant and vertebrate items, whereas the morphological approaches were unable to detect the latter two. These results opened up new questions on the ecological role of the Selvagens gecko that deserves to be further explored, such as the possible predation on seabirds, plant services or trophic competition with the sympatric Madeira lizard Teira dugesii. Metabarcoding identified a greater diversity of dietary items at higher taxonomic resolution, but morphological identification enabled calculation of relative abundances and biomasses of ingested arthropods, and detected a dietary shift on invertebrate preys between seasons. Results of this study highlight the global applicability of rapid metabarcoding surveys for understudied taxa on remote islands that are difficult to access. We recommend using the metabarcoding approach, even if ‘speedy’ sampling only is possible, but we must highlight that disregarding long-term ecological data may lead to ‘hasty’ conclusion.info:eu-repo/semantics/publishedVersio

Thermal leptogenesis in a model with mass varying neutrinos

In this paper we consider the possibility of neutrino mass varying during the evolution of the Universe and study its implications on leptogenesis. Specifically, we take the minimal seesaw model of neutrino masses and introduce a coupling between the right-handed neutrinos and the dark energy scalar field, the Quintessence. In our model, the right-handed neutrino masses change as the Quintessence scalar evolves. We then examine in detail the parameter space of this model allowed by the observed baryon number asymmetry. Our results show that it is possible to lower the reheating temperature in this scenario in comparison with the case that the neutrino masses are unchanged, which helps solve the gravitino problem. Furthermore, a degenerate neutrino mass patten with $m_i$ larger than the upper limit given in the minimal leptogenesis scenario is permitted.Comment: 18 pages, 7 figures, version to appear in PR

Reliability of Fatigue Strength Curves for Riveted Connections Using Normal and Weibull Distribution Functions

In North America and Europe, there is a significant number of centenary metallic bridges that require maintenance and strengthening operations. These structures need to be adapted to increasing traffic intensities, and their structural integrity should be constantly evaluated. Fatigue damages were not considered in the original design of old metallic bridges, and riveted connections are one of the most frequent sources of fatigue damages on these structures. This paper intends to be a contribution for the reliable assessment of the fatigue behavior of riveted connections by proposing S-N curves for these structural details. Experimental fatigue data is analyzed from multiple bridges across Europe, and different statistical methods were implemented. A normal distribution function was implemented following the ISO 12107 standard, and the results were compared with the implementation of the two-parameter Weibull distribution function. Different estimation methodologies were implemented to determine the parameters of the Weibull distribution. S-N curves obtained by the statistical analysis were then compared with design recommendations from North American and European standards. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Erratum DOI: 10.1061/AJRUA6.0001081 The following correction should be made to the original paper: in all places where it is written “probability of failure,” the text should read “probability of survival,” including in Tables 2 and 3.Steel & Composite Structure

Trihalomethanes in Lisbon Indoor Swimming Pools: Occurrence and Determining Factors

Inclui artigo publicado em: Proceedings of the 4th International Conference of Swimming Pool & SPA(ICOEH), 2011, Porto: 40-50The presence of water disinfection by-products (DBPs) in swimming pools constitutes today a public health concern, particularly because swimming is an activity used by a high percentage of the population, namely elderly and young children. Moreover, several adverse short-term and long-term health effects have been associated with these compounds (Lakind et al., 2010; Zwiener et al., 2007). Water disinfection methods are used in all swimming pools, namely in public pools, to ensure an adequate and effective protection of users against microbiological pathogens. Chlorination is the most common disinfection method used worldwide, because it is low cost, easy to use, efficient against a broad spectrum of microorganisms, and enables the maintenance of a residual protection. The use of chlorine based treatment techniques has one strong drawback, which is the generation of several DBPs, potentially harmful products, that can be absorbed by ingestion, inhalation and absorption through the skin (Nieuwenhuijsen et al., 2009; Caro and Gallego, 2007). DBPs comprise several compounds that are formed through the reaction of chlorine with organic matter present in water. Amongst DBPs, the most relevant and better characterized are trihalomethanes (THMs): chloroform (CF), bromoform (BF), bromodichloromethane (BDCM), and chlorodibromomethane (DBCM). These compounds have been associated with health effects such as respiratory, ocular and cutaneous symptoms and also with some long-term health effects such as bladder cancer and adverse reproductive outcomes (Lee et al., 2009; Zwiener et al., 2007). Accurate exposure assessments to THMs in indoor pool environment is particularly difficult because their formation depends on many factors such as water and air temperature (Tw and Tair), humidity (Hu), pH, free residual chlorine (FrCl), total organic content and number of pool users (Lee et al., 2009). In Portugal a specific legislation to assess the quality of swimming pool waters is inexistent. The guideline value used in this study for total THMs (TTHMs) was the one established in the Portuguese Law 306/2007, for drinking water quality - 100 μg/L. Some other water parameters determined in swimming pools such as Tw turbidity (Turb), pH, FrCl, total residual chlorine, conductivity (Cond), permanganate index (COD) and isocyanuric acid were assessed by Portuguese Law 5/97, regarding technical and safety conditions of closed environments with water diversions. WHO guidelines for safe recreational water environments (2006) were also used to assess some water and air parameters in pools. Standard 62.1 (2006) from American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASRHAE) was also used to assess pool air parameters. The main goal of this investigation project was to study the occurrence, distribution and determinants of THMs in indoor swimming pools. This will enable an evaluation of swimming pool users’ exposure to THMs. In order to achieve this goal, the characterization of water quality of 30 Lisbon indoor swimming pools, using chorine based treatment techniques, was made during a six month period. Because of laboratory working restrictions, CF concentration in pool air was studied only in 6 swimming pools, at the same period. Several parameters such as TTHMs concentration, CF, BDCM, DBCM, BF concentration in water, FrCl, combined residual chlorine (CrCl), pH, Tw and Tair, Hu, COD, Cond, Turb and chloride (Cl) were determined in each pool, once a month. THMs water sampling was made in duplicates in two pool water spots, physicochemical parameters were determined in one of the THMs water sampling spots and THMs air sampling was made in two pool spots, considered to be representative of the swimming pool air. All sampling procedures were performed by specialized sampling technicians from Lisbon Health Centres Group (ACES). Statistical analysis was performed using the SPSS 17.0 software. Descriptive analysis was applied to all variables in order to determine mean, median, standard deviation, minimum and maximum. Student’s t-test and Mann-Whitney tests were used to compare numerical variables and Spearman’s rank correlation coefficient were used to examine correlation between all environmental parameters. TTHMs water level ranged from 10 to 160 μg/L, while CF water level typically ranged from 5 to 150 μg/L, with occasional higher levels detected. Regarding other THMs levels in pool water, BDCM ranged from 0.5 to 15 μg/L, DBCM from 0.4 to 10 μg/L and BF was obtained in concentrations less than 2 μg/L. Moreover, in some pools, DBCM and BF were not detected. From these results, it can be concluded that there was a large variation in TTHMs and CF water levels between the pools and that CF was the THM obtained in higher concentrations. These results are in agreement with studies presented by other authors (Lee et al., 2009; Chu and Nieuwenhuijsen, 2002). In air, CF level ranged from 40 to 200 μg/m3, with occasional higher levels detected. Tw presented less variation (27 to 31 ºC) than Tair (21 to 33 ºC), although sporadic higher values were found. FrCl and Cond presented higher values than the guidelines from DR 5/97 only in a small number of pools. Turb and COD values were within the guidelines from DR 5/97. pH varied from 7 to 8.5, with only a small number of pools having values higher than 7.8. As referred in WHO guidelines, pH should be maintained between 7.2 and 7.8 for chlorine disinfectants to ensure efficient disinfection. Using the statistical tests mentioned before, it was possible to obtain some interesting results. There was a clear positive linear correlation between CF water concentration (CFW) and TTHMs water concentration (R>0.98, p0.78, p0.45, p<0.05). These results are in agreement with Lee et al. (2009) which obtained positive linear correlations between CFW and COD and with Chu and Nieuwenhuijsen (2002) which also obtained correlations between TTHMs water concentration and Tw. In conclusion, there appears to be good water and air quality in the studied Lisbon swimming pools. Regarding THMs levels in water, some pools presented high TTHMs and CF concentrations. Moreover, CF air concentrations were also high in some swimming pools. These results clearly demonstrate that THMs monitoring is particularly important and that, in a near future, this should be extended to other DBPs. Furthermore, for a correct and conscious use of swimming pools, appropriate and targeted information about safe practices should be provided to pool users.Bolsa de Investigação Científica Doutor Ricardo Jorge - Zelinda Silv

Analysis and Identification of Trihalomethanes in Lisbon Indoor Swimming Pools: Distribution, Determinants and Human Exposure

Water disinfection methods are used in swimming pools to ensure an effective protection of users against microbiological pathogens, being chlorination the most common disinfection method used worldwide. The use of chlorine based treatment techniques has one strong drawback, which is the generation of disinfection by-products (DBPs), potentially harmful products that have been associated with respiratory and ocular symptoms, bladder cancer and adverse reproductive effects. Amongst DBPs, the most better characterized are trihalomethanes (THMs): chloroform (CF), bromoform (BF), bromodichloromethane (BDCM), and chlorodibromomethane (DBCM). In Portugal a specific legislation to assess the quality of swimming pools is inexistent. The guideline value used to evaluate total THMs in water (TTHMsW) is the one established in the Law 306/2007 - 100 μg/L. Some other water/air parameters were assessed by Law 5/97, WHO guidelines for safe recreational water environments (2006) and Standard 62.1 (2006) from American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASRHAE). The main goal of this investigation was to study the occurrence, distribution and determinants of THMs in indoor swimming pools. This will also enable an evaluation of the exposure of users to THMs. In order to achieve this goals, the characterization of water quality in 30 Lisbon indoor swimming pools, using chorine based treatment techniques, was made during a six month period. Several parameters such as TTHMs, CF, BDCM, DBCM, BF levels in water, free residual chlorine (FrCl), pH, TW, Tair, Hu, chemical oxygen demand (COD), and other, were determined in each pool, once a month. Statistical analysis was performed using the SPSS 17.0 software. Descriptive analysis was applied to all variables. Student’s t-test, Mann-Whitney tests and Spearman’s rank correlation coefficient were also used. Large variation in TTHMs and CF water levels between the pools was obtained, being CF the THM obtained in higher concentrations, with sporadic higher values than the allowed. In air, CF level (CFair) also presented occasional higher levels. There was a clear positive linear correlation between CFW and TTHMsW (R>0.95, p 0.5; p0.2; p0.2; p0.5, p0.6; p0.5; p0.2; p0.2; p<0.01). In conclusion, reasonable water and air quality was obtained in the studied Lisbon swimming pools, although some pools presented high TTHMsW, CFW and CFair. These results clearly demonstrate that THMs monitoring is particularly important and that, in a near future, this should be extended to other DBPs. Furthermore, for conscious use of swimming pools, appropriate and targeted information about safe practices should be provided to pool users.Bolsa de Investigação Científica Doutor Ricardo Jorge - Zelinda Silv