Utilização de georadar na caracterização da evolução do dano estrutural de uma parede: ensaio à escala real

Ao longo do tempo o património edificado deteriora-se devido a causas naturais ou antrópicas. A acção sísmica é um factor que pode provocar danos estruturais nas paredes das construções tradicionais, por vezes até imperceptíveis à vista desarmada. A Geofísica aplicada proporciona técnicas de elevada resolução que permitem detectar alvos de pequenas dimensões, como por exemplo fendas na estrutura interna de paredes. O georadar, técnica não invasiva, utiliza impulsos electromagnéticos de frequências variando de dezenas de MHz a GHz que permitem uma elevada resolução dos meios a investigar. A utilização destas técnicas na caracterização interna de paredes exige a utilização de gamas de frequências elevadas (> 1GHz) de forma que pequenas fissuras sejam detectadas. A evolução do dano de uma estrutura tradicional de alvenaria sujeita a diferentes solicitações, como as acções sísmicas, pode ser monitorizada por medidas de georadar. Por outro lado, poderá ainda ser viável a utilização de medidas de georadar na avaliação da eficácia de soluções de reparação de fissuras por injecção de caldas. Na região de Aveiro as paredes estruturais eram tradicionalmente realizadas em adobe. Para avaliar a viabilidade da aplicação do georadar na caracterização interna destas estruturas, no Departamento de Engenharia Civil da Universidade de Aveiro foi construída uma parede em adobe, com blocos de adobe recuperados das construções existentes, e segundo as técnicas e métodos tradicionais. Esta parede foi inicialmente sujeita a uma solicitação cíclica de amplitude crescente que lhe produziu danos estruturais significativos. Estes danos foram posteriormente reparados com recurso à injecção de uma calda à base de cal hidráulica. Após reparação dos danos, a parede foi reforçada com uma malha polimérica embebida no reboco e esta foi sujeita a um ensaio cíclico de amplitude crescente até ao seu colapso. Foram recolhidos dados de georadar (1.6 GHz) sobre a parede, antes e durante o ensaio da parede reforçada, que permitiram caracterizar os danos iniciais, a eficiência da injecção da calda na colmatação das fissuras e a evolução dos danos estruturais provocados ao longo do ensaio. Os resultados são discutidos e permitem justificar plenamente a utilização do georadar na caracterização interna de estruturas de paredes. Demonstra-se que o georadar é uma ferramenta não intrusiva de elevada resolução a utilizar na avaliação do dano em construções existentes

An integrated investigation of the Rio tailings, Panasqueira mine, Centre Portugal

The risks associated with mine tailings have different nature and, thus, only a multiple approach can investigate and monitor comprehensively the characteristics and evolution of mine tailings impacts on the environment. Deposition at the Rio tailings (Panasqueira Mine) lasted about ninety years. Over one million cubic metres, of complex very fine to fine material, are deposited on a mountain side overlaying the Zezere river, increasing the risk of contamination of one of the most important hydrographic basins in central Portugal. Herein, a multidisciplinary study including geophysics, geochemistry and borehole information, organized in a GIS, is used to characterize the Rio tailings. The geophysical survey comprised ERT (Electrical Resistivity Tomography) and GPR (Ground Penetrating Radar) on the mud impoundment, as well as, on the slope of the tailings. The geochemical survey consisted on collecting water and tailings samples, iron coatings, arsenopyrite stockpile material and ferruginous crust. Samples collected in boreholes, drilled specifically for this project, were also analyzed. The GIS provided imaging of the geophysical, geochemical and particle size spatial distribution, so that comparisons between the different data sets are easily done. Resistivity and GPR allowed bedrock positioning. GPR was able to give layering results within the tailings. Finally, comparison and correlation between geophysical and geochemical results are carried out and evaluated on the GIS platform

Cognitive Load And Self-determination Theories Applied To E-learning: Impact On Students' Participation And Academic Performance

Emergency clerkships expose students to a stressful environment that require multiple tasks, which may have a direct impact on cognitive load and motivation for learning. To address this challenge, Cognitive Load Theory and Self Determination Theory provided the conceptual frameworks to the development of a Moodle-based online Emergency Medicine course, inspired by real clinical cases. Methods Three consecutive classes (2013-2015) of sixth-year medical students (n = 304) participated in the course, during a curricular and essentially practical emergency rotation. "Virtual Rounds" provided weekly virtual patients in narrative format and meaningful schemata to chief complaints, in order to simulate real rounds at Emergency Unit. Additional activities such as Extreme Decisions, Emergency Quiz and Electrocardiographic challenge offered different views of emergency care. Authors assessed student's participation and its correlation with their academic performance. A survey evaluated students' opinions. Students graduating in 2015 answered an online questionnaire to investigate cognitive load and motivation. Results Each student produced 1965 pageviews and spent 72 hours logged on. Although Clinical Emergency rotation has two months long, students accessed the online course during an average of 5.3 months. Virtual Rounds was the most accessed activity, and there was positive correlations between the number of hours logged on the platform and final grades on Emergency Medicine. Over 90% of students felt an improvement in their clinical reasoning and considered themselves better prepared for rendering Emergency care. Considering a Likert scale from 1 (minimum load) to 7 (maximum load), the scores for total cognitive load were 4.79 +/- 2.2 for Virtual Rounds and 5.56 +/- 1.96 for real medical rounds(p<0,01). Conclusions A real-world inspired online course, based on cognitive and motivational conceptual frameworks, seems to be a strong tool to engage students in learning. It may support them to manage the cognitive challenges involved in clinical care and increase theirmotivation for learning.1

Association of cystic fibrosis genetic modifiers with congenital bilateral absence of the vas deferens

Objective: To investigate whether genetic modifiers of cystic fibrosis (CF) lung disease also predispose to congenital bilateral absence of the vas deferens (CBAVD) in association with cystic fibrosis transmembrane conductance regulator (CFTR) mutations. We tested the hypothesis that polymorphisms of transforming growth factor (TGF)-beta 1 (rs 1982073, rs 1800471) and endothelin receptor type A (EDNRA) (rs 5335, rs 1801708) are associated with the CBAVD phenotype. Design: Genotyping of subjects with clinical CBAVD. Setting: Outpatient and hospital-based clinical evaluation. Patient(s): DNA samples from 80 subjects with CBAVD and 51 healthy male controls from various regions of Europe. This is one of the largest genetic studies of this disease to date. Intervention(s): None. Main Outcome Measure(s): Genotype analysis. Result(s): For single nucleotide polymorphism (SNP) rs 5335, we found increased frequency of the CC genotype among subjects with CBAVD. The difference was significant among Turkish patients versus controls (45.2% vs. 19.4%), and between all cases versus controls (36% vs. 15.7%). No associations between CBAVD penetrance and polymorphisms rs 1982073, rs 1800471, or rs 1801708 were observed. Conclusion(s): Our findings indicate that endothelin receptor type A polymorphism rs 5335 may be associated with CBAVD penetrance. To our knowledge, this is the first study to investigate genetic modifiers relevant to CBAVD. (Fertil Steril (R) 2010; 94: 2122-7. (C) 2010 by American Society for Reproductive Medicine.

Alternative Splicing at a NAGNAG Acceptor Site as a Novel Phenotype Modifier

Approximately 30% of alleles causing genetic disorders generate premature termination codons (PTCs), which are usually associated with severe phenotypes. However, bypassing the deleterious stop codon can lead to a mild disease outcome. Splicing at NAGNAG tandem splice sites has been reported to result in insertion or deletion (indel) of three nucleotides. We identified such a mechanism as the origin of the mild to asymptomatic phenotype observed in cystic fibrosis patients homozygous for the E831X mutation (2623G>T) in the CFTR gene. Analyses performed on nasal epithelial cell mRNA detected three distinct isoforms, a considerably more complex situation than expected for a single nucleotide substitution. Structure-function studies and in silico analyses provided the first experimental evidence of an indel of a stop codon by alternative splicing at a NAGNAG acceptor site. In addition to contributing to proteome plasticity, alternative splicing at a NAGNAG tandem site can thus remove a disease-causing UAG stop codon. This molecular study reveals a naturally occurring mechanism where the effect of either modifier genes or epigenetic factors could be suspected. This finding is of importance for genetic counseling as well as for deciding appropriate therapeutic strategies