Dynamic ground stress‐path evolution due to the railway traffic: A parametric study

No presente artigo apresenta‐se um estudo numérico sobre a evolução do estado de tensão geomecânico induzido pela passagem de tráfego ferroviário. O modelo numérico proposto é baseado na formulação 2,5D apoiada no MEF‐PML, permitindo a consideração da interação do sistema composto pelo comboio, via‐férrea e maciço de fundação. Para o caso de estudo proposto, as alterações do estado de tensão são sistematizadas sob a forma de trajetórias de tensão. Perante os resultados alcançados é possível reconhecer a grande influência da velocidade de circulação do comboio e da presença de irregularidades na via no comportamento da via‐férrea. Tirando partido dos conhecimentos adquiridos com a realização dos estudos paramétricos referidos, verifica‐se a adequabilidade de um ensaio laboratorial –ensaio torsional com cilindro vazado– na simulação das complexas trajetórias de tensão induzidas no solo de fundação pela passagem do tráfego ferroviário. Os resultados obtidos permitem perspetivar a simulação em laboratório dessa ação, através de um carregamento cíclico, com o objetivo de estudar a acumulação de dano nas amostras.In this paper, a numerical study of the geomechanical stress state evolution induced by the railway traffic is presented. The numerical model is based on a 2.5D formulation with the ability to account for the dynamic train‐track interaction. For the case study, the stress state evolution is systematized in the form of stress paths. The results obtained allow to recognize the great influence of the train speed and the presence of irregularities in the track for the behavior of the railway track. Based on the knowledge acquired during the implementation of previous parametric studies, the adequacy of the hollow cylinder torsional test to simulate the complex stress paths induced in the ground of the traffic railway is evaluated. The results obtained allow to put in perspective the simulation of these loads in laboratory, with the aim of studying the damage accumulation in the specimens.Peer Reviewe

Knowledge and attitude towards the gradual reduction of salt in bread – an online survey

Aim: Assess knowledge and attitude towards the gradual reduction of salt in bread and the potential impact on eating habits of children (6-18 years) and their families, as part as a Health Impact Assessment pilot study.N/

The evaluation of student-centredness of teaching and learning: a new mixed-methods approach.

OBJECTIVE: The aim of the study was to develop and consider the usefulness of a new mixed-methods approach to evaluate the student-centredness of teaching and learning on undergraduate medical courses. An essential paradigm for the evaluation was the coherence between how teachers conceptualise their practice (espoused theories) and their actual practice (theories-in-use). METHODS: The context was a module within an integrated basic sciences course in an undergraduate medical degree programme. The programme had an explicit intention of providing a student-centred curriculum. A content analysis framework based on Weimer's dimensions of student-centred teaching was used to analyze data collected from individual interviews with seven teachers to identify espoused theories and 34h of classroom observations and one student focus group to identify theories-in-use. The interviewees were identified by purposeful sampling. The findings from the three methods were triangulated to evaluate the student-centredness of teaching and learning on the course. RESULTS: Different, but complementary, perspectives of the student-centredness of teaching and learning were identified by each method. The triangulation of the findings revealed coherence between the teachers' espoused theories and theories-in-use. CONCLUSIONS: A mixed-methods approach that combined classroom observations with interviews from a purposeful sample of teachers and students offered a useful evaluation of the extent of student-centredness of teaching and learning of this basic science course. Our case study suggests that this new approach is applicable to other courses in medical education

Evaluation of influenza vaccination services and users’ perception about its utility: a study in a community pharmacy in Lisbon, Portugal

Poster presented at the 25th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID). Copenhagen, Denmark, 25–28 April 201

Vascular liver anatomy and main variants: what the radiologist must know

Advances in surgical techniques are extremely demanding regarding the accuracy and level of detail expected for display of the vascular anatomy of the liver. Precise knowledge of the arterial, portal and hepatic vein territories are mandatory whenever a liver intervention is planned. Sectional anatomy can now be routinely performed on multidetector computed tomography (MDCT) with volumetric data and isotropic voxel display, by means of sub-millimetric slice thickness acquisition. The relevant vascular information can thus be gathered, reviewed and post-processed with unprecedented clarity, obviating the need for digital subtraction angiography. The scope of the present paper is to review the normal vascular liver anatomy, its most relevant variants including additional sources of vascular inflow. Apart from providing the surgeon with a detailed vascular and parenchymal roadmap knowledge of imaging findings may avoid potential confusion with pathologic processes

Integrated system for macroalgae production and conversion into biogas

Recently research on energy from macroalgae is being reconsidered driven by the following factors: fuel price increase, CO2 mitigation policies and interest on renewable energy sources after the Kyoto protocol, and need for energy crops not competing with land for food production. However, the commercial expansion of this energy source is limited by its economic feasibility. In this presentation we analyse the development of integrated systems that promote synergies between macroalgae/biogas production and activities such as aquaculture and urban wastewater treatment. The recycling of nutrients and CO2 by macroalgae can be an opportunity to reduce the biomass-biogas production cost. Other advantage is the proximity between biomass production, conversion into energy and its consumption, thus avoiding energy losses and pollution in transportation. Experimental work is underway and includes batch tests to evaluate biodegradability of Ulva spp. and Gracilaria sp. and co-digestion of these macroalgae with sewage sludge from Beirolas wastewater treatment plant (WWTP). Furthermore, continuous co-digestion experiments are planned to be carried out in a 30 L experimental reactor to be placed in the same WWTP. The objectives are to reproduce sludge digestion in Beirolas WWTP and evaluate algae/sludge co-digestion performance. Preliminary results indicate methane yields in accordance with similar batch experiments, whereby our CH4 yields per volatile solids added range between 0.14-0.20 m3 CH4 kg-1 VSadded against 0.16-0.27 m3 CH4 kg-1 VSadded [1,2] depending on the algae species and pretreatment. Overall, Ulva sp. shows a better performance over Gracilaria sp. as also confirmed in other experiments [1]

Non-linear soil behaviour on high speed rail lines

This paper gives new insights into non-linear subgrade behaviour on high speed railway track dynamics. First, a novel semi-analytical model is developed which allows for soil stiffness and damping to dynamically change as a function of strain. The model uses analytical expressions for the railroad track, coupled to a thin-layer element formulation for the ground. Material non-linearity is accounted for using a ‘linear equivalent’ approach which iteratively updates the soil material properties. It is validated using published datasets and in-situ field data. Four case studies are used to investigate non-linear behaviour, each with contrasting subgrade characteristics. Considering an 18 tonne axle load, the critical velocity is significantly lower than the linear case, and rail deflections are up to 30% higher. Furthermore, at speeds close-to, but below the non-linear critical velocity, dynamic amplification is highly sensitive to small increases in train speed. These findings are dependent upon soil material properties, and are important for railway track-earthwork designers because often 70% of the linear critical velocity is used as a design limit. This work shows that designs close to this limit may be still at risk of high dynamic effects, particularly if line speed is increased in the future

Perception of medical errors among health professionals and students

Objective: To know the perceptions of health professionals and students about medical errors. Methods: It is a qualitative study conducted with 92 subjects of both genders in the Campus 1 from the Federal University of Paraíba, in João Pessoa. For data collection, we have used a semi-structured questionnaire consisted of two parts containing the test of Free Association of Words with the inductive term "medical error". The collected data were analyzed with the help of the software Alceste, which showed additional six classes. Results: The subjects perceive medical error from the recognition of "impunity" and associate it to "incompetence", "inattention", "disinterest" and "unpreparedness" by doctors to exercise their profession. Conclusion: Both students and professionals point as causes of medical errors: the bad professional training coupled with lack of infrastructure of services offered, as well as arrogance of doct

Anaerobic digestion of OMW : intermittent feeding strategy and LCFA oxidation profile

ManuscriptAn intermittent feeding strategy was applied to the anaerobic treatment of raw olive mill wastewater (OMW). Two reactors were operated under influent concentrations of 5 to 50 g COD L-1. Two and one batch (feed-less) periods were applied to reactor R1 and R2, respectively, operating in continuous thenceforth. It was demonstrated that the intermittent feeding of OMW improved the mineralization of accumulated Long Chain Fatty Acids (LCFA) inside the reactor. Nevertheless, LCFA accumulated again when the organic loading rate was increased from 2 to 3 and 5 kg COD m-3 d-1. The profiles of LCFA, obtained with OMW digestion, were different from previous studies with synthetic effluents. At the beginning of reactors operation, oleate was the main LCFA compound (~50%) followed by palmitate. Afterwards, a shift in the LCFA pattern accumulation was noticed for both reactors. At periods with higher OMW concentrations (30-50 g COD L-1, 3-5 kg COD m-3 d-1) palmitate was the main LCFA accumulated with 69% at R1 and 54% at R2. For real oily wastewaters, a periodically batch period could be a practical solution to maintain low values of LCFA inside the reactor. The addition of a nitrogen source was essential to enhance the methane yield

Start-up and feeding strategy of an anaerobic sequencing batch reactor for olive mill wastewater treatment

Olive mill wastewater (OMW) is the effluent generated by olive oil industries, mainly produced in the Mediterranean areas. The production of olive oil generates huge amounts of wastewater. Anaerobic wastewater treatment processes appears as a promising technology for the treatment and energetic potential recovery of these high strength wastewaters since a renewable energy source (biogas) is generated. However, due to the high organic contents and presence of lipidic and phenolic compounds the treatment of OMW is sometimes toxic to the anaerobic microorganisms. Aiming at define the best strategy for the anaerobic sequencing batch reactor start-up, two reactors were operated with an hydraulic retention time of 10 days, fed with OMW at 5gCOD/L. In batch assays it was previously observed that when using an adapted microbial consortium to lipids, OMW was more efficiently converted to biogas and the overall methane production was higher. On the other hand an intermittent feeding start-up was proven to promote the degradation of long chain fatty acids to methane. Therefore, two reactors, R1 and R2 were inoculated with a biomass acclimated to oleate (BAO) and a biomass non-acclimated (BNA), respectively. The inoculum type effect on start-up efficiency and the benefits of an intermittent feeding were studied. In both reactors, the COD removal efficiency reached more than 80% after 50 days of operation. The reactor with BAO was more stable during the operation period than in the reactor with BNA. The inoculums effect was determinant in the initial phase of feeding, but, as expected, its effect was diluted after 30 days. The intermittent feeding was tested in R1. Promoting the degradation of the accumulated substrate was beneficial to increase the specific methanogenic activity of the sludge inside the reactor