Cable-deck dynamic interactions at the International Guadiana Bridge: On-site measurements and finite element modelling

SUMMARY The International Guadiana Bridge is a cable-stayed bridge crossing the Guadiana River, which marks the southern border between Portugal and Spain. The bridge has a central span of 324 m and a total length of 666 m and was open to traffic in 1991. Despite the globally satisfying behaviour under the common environmental loads, which largely ensures the bridge serviceability, frequent episodes of cable vibration have been observed since completion of the construction. In this paper, the bridge modal properties and dynamic behaviour, identified from repeated campaigns of vibration data acquisitions, are compared with the response of a three-dimensional finite element model, including the description of the cable transversal motion. The model, after minor updating, furnishes a realistic reproduction of the current bridge dynamic behaviour. Then different possible justifications of the local vibrations are evaluated, briefly scanning the known sources of large amplitude cable oscillations both in the linear and the nonlinear field. In particular, the occurrence of different internal resonance conditions is deeply discussed, in order to verify whether the experimental observations could be really justified by a cable–deck dynamic interaction mechanism. Among different possibilities, a beating phenomenon between two resonant modes, amplified by the lower damping and inertial characteristics of the local mode with respect to the global one, is selected as the most critical cable excitation source. Since the cable vibrations are proved to persist for different wind conditions, the heavy traffic load on the bridge deck is investigated as one possible source of the global mode direct excitation. On this respect, the model response to random load and moving forces acting on the bridge deck is numerically evaluated evidencing how some particular features of the real bridge behaviour can be qualitatively reproduced. Copyright # 2008 John Wiley & Sons, Ltd

Holonomy and parallel transport for Abelian gerbes

In this paper we establish a one-to-one correspondence between $S^1$-gerbes with connections, on the one hand, and their holonomies, for simply connected manifolds, or their parallel transports, in the general case, on the other hand. This result is a higher-order analogue of the familiar equivalence between bundles with connections and their holonomies for connected manifolds. The holonomy of a gerbe with group $S^1$ on a simply connected manifold $M$ is a group morphism from the thin second homotopy group to $S^1$, satisfying a smoothness condition, where a homotopy between maps from $[0,1]^2$ to $M$ is thin when its derivative is of rank $\leq 2$. For the non-simply connected case, holonomy is replaced by a parallel transport functor between two monoidal Lie groupoids. The reconstruction of the gerbe and connection from its holonomy is carried out in detail for the simply connected case. Our approach to abelian gerbes with connections holds out prospects for generalizing to the non-abelian case via the theory of double Lie groupoids.Comment: Final version. Improved readibility (hopefully). LaTeX, 60 pages, 14 figures. To appear in Advances in Mathematic

A Multi-scenario prospection of urban change - the case of urban growth in the Algarve

The Algarve faces unprecedented challenges resulting from increase of urban sprawl and population density along its coastal perimeters. A growing loss of ecosystems and natural landscapes have led to major asymmetries between the interior of the Algarve and the littoral areas. The depletion of natural resources taken for granted during the sixties, are conveying to the degradation of landscape, while the formerly beautiful region of the Algarve is losing its tourist attractions, largely explored since the latter. Loss of agricultural land to urban areas, has not only been a reality in Portugal, but is a common problem in peri-urban Europe and is overshadowing sustainable development. This paper aims to analyze the land-use change tendencies for the Algarve region from the beginning of the nineties up to 2020. By using a multi-scenario perspective of weight drivers such as agriculture, coastal proximity, urban proximity, population density and road networks, an Analytical Hierarchy Process will be applied to form three growth patterns for urban propensity within the coming 10 years and expanding over a total time frame of 30 years. The novelty of this approach is shared by the usage of story-lines which generate three distinct scenarios: More Ecological, Business as Usual and Economic Reasoning (maximization of economic growth). While story-lines are naturally qualitative, this methodology proposes a quantitative validation of qualitative information, giving a much more accurate result of current trends of urban growth and environmental change in the Algarve. The projection of future land-use is managed through the CORINE Land Cover spatial databases and iterations of cellular automata with the storylines, which shall allow the projection of future urban growth. By understanding the different path-tendencies of urban growth for the region, better decision-making can be done, as to avoid unbalanced city growth, bringing forth more sustainable cities within natural landscapes

Estudo dosimétrico comparativo entre a respiração livre e inspiração forçada com radioterapia conformacional a 3D no tratamento do cancro da mama esquerda

ABSTRACT: Introduction – Radiotherapy (RT) is a therapeutic approach for the treatment of left breast cancer. However, different breathing techniques free breathing (FB) and deep inspiration breath-hold (DIBH) can be used. Objectives – To identify which of the breathing techniques, DIBH or FB, has obtained better irradiation of the planning target volume (PTV) and a lower dose at the organs at risk (OAR). Check if the DIBH technique allows a dose reduction in the left ventricle. Methodology – Twenty female patients with pathology in the left breast were selected. In computed tomography, the contours of PTV and OAR were made. We obtained dosimetric data for each patient, with each of the two types of breathing techniques. Dosimetric data for all patients were compared for both respiratory techniques. Results – The DIBH technique reduced the mean dose (Dmean) and V20% in the left lung, only being higher in four patients. In the left ventricle, there was a decrease in Dmean and V30% in all patients. The spinal cord in either DIBH or FB did not reach the reference limit, however, there was an improvement when using DIBH. Conclusions – The DIBH technique presents lower doses in the organs at risk, improvements in PTV dose coverage, as well as conformity, homogeneity, and quality indexes when compared to the FB technique.RESUMO: Introdução – A radioterapia (RT) é uma abordagem terapêutica para tratamento do cancro da mama esquerda. Contudo, diferentes técnicas respiratórias Respiração Livre (FB) e Inspiração Forçada (DIBH) podem ser usadas. Objetivos – Identificar em qual das técnicas de respiração, DIBH ou FB, se consegue obter uma melhor irradiação do Planning Target Volume (PTV) e uma menor dose nos órgãos de risco (OR). Perceber se a técnica de DIBH permite uma diminuição de dose no ventrículo esquerdo. Metodologia – Foram selecionadas 20 doentes, do sexo feminino, com patologia na mama esquerda. Na tomografia computorizada foram feitos os contornos do PTV e dos OAR. Obtiveram-se os dados dosimétricos de cada uma das doentes, com cada um dos dois tipos de técnica respiratória, que foram comparados. Resultados – Em média, a técnica DIBH reduziu a dose média (Dmed) e V20% no pulmão esquerdo, apenas sendo superior em quatro doentes. No ventrículo esquerdo observou-se uma diminuição de Dmed e V30% em todos os doentes. A medula quer em DIBH quer em FB não atingiu o limite de referência; contudo, verificou-se uma melhoria quando usado o DIBH. Conclusões – A técnica respiratória DIBH apresenta menor dose nos órgãos de risco, melhoria na cobertura de dose no PTV, bem como nos índices de conformidade homogeneidade e qualidade comparativamente à técnica de FB.info:eu-repo/semantics/publishedVersio

Estudo de três sistemas de imobilização utilizados em radioterapia: perspetiva atual e futura

Mestrado em RadioterapiaEm oncologia e de acordo com a literatura, 50 a 60% dos doentes realizam Radioterapia. Destes, cerca de 40% são integrados em esquema de tratamentos de Radioterapia paliativa. Um aspeto fulcral para o sucesso da realização do tratamento de Radioterapia consiste no posicionamento adequado do doente, e tentar garantir que este posicionamento seja reprodutível entre as diversas sessões de tratamento. Os sistemas de imobilização tem um papel preponderante para garantirem este requisito, No entanto, verifica-se no dia-a-dia que os sistemas disponíveis comercialmente nem sempre apresentam a melhor solução que garanta um posicionamento confortável ao doente, logo poderá dificultar a sua imobilização. Para além disto é essencial contar com a colaboração do doente, devendo este ser informado e treinado para se manter imóvel durante o tratamento. É objetivo deste estudo recolher informações bibliográficas sobre a utilização de equipamentos de imobilização, tendo como critérios de análise o conforto para o doente e a reprodutibilidade do posicionamento diário, com maior enfase em tumores de cabeça e pescoço, mama e pélvicos. Com base nas informações bibliográficas, foi realizado um estudo prático com um grupo de 19 doentes consecutivos tratados em colchão de vácuo, no Centro Oncológico Drª Natália Chaves. Considera-se que os três sistemas de imobilização (sistema de fixação de máscaras, apoio de mama e imobilizadores pélvicos) atualmente utilizados poderão ser melhorados. Os dados estatísticos na reprodutibilidade do colchão de vácuo justificam a oportunidade para melhorar os sistemas de imobilização. Neste sentido com este trabalho, pretende-se apresentar uma proposta de mesa de tratamento robotizada que teoricamente, poderá aumentar o conforto do doente durante tratamento e, consequentemente a reprodutibilidade ao longo do tratamento de Radioterapia.ABSTRACT - According to the literature, 50 to 60% of all oncology patients receive radiotherapy treatment. From these patients, about 40% receive radiotherapy with palliative intention. A major factor for the success of the radiotherapy treatment is the right patient setup and the assurance that this setup will be reproducible during all treatment sessions. Immobilization devices play a major role in achieving these requirements. However, on daily practice, the devices available on the market aren’t always the best way to ensure a comfortable patient setup, which may hinder immobilization. Besides, one needs to rely on patient’s will to collaborate, making patient information and training so important to assure he remains still during treatment sessions. This study’s goal is to obtain bibliographic information about the use of immobilization devices, analyzing its comfort for the patient and daily setup reproducibility, for head and neck, breast and pelvic tumors setup. A study for vac-lok cushions was also made, including 19 consecutive patients from Centro Oncológico Dr.ª Natália Chaves whose setup was made using this device. Conclusions were that the three immobilization devices in literature (mask systems, breast board and pelvice devices) currently used can be improved. Statistic data on reproducibility using the vac-lok cushion also justifies the opportunity to improve immobilization devices. Therefore, it is presented in this study the idea for a robotic treatment couch which will, in theory, be able to increase patient’s comfort and reproducibility of setup during radiotherapy treatment

Using virtual reality to prepare patients for radiotherapy: a systematic review of interventional studies with educational sessions

Purpose: To understand the impact of radiotherapy educational sessions with virtual reality on oncologic adult patients' psychological and cognitive outcomes related to the treatment experience. Methods: This review was performed according to the Preferred Reporting Items for Systematic Reviews guidelines. A systematic electronic search in three databases, MEDLINE, Scopus, and Web of Science, was conducted in December 2021 to find interventional studies with adult patients undergoing external radiotherapy who received an educational session with virtual reality before or during the treatment. The studies that provided qualitative or quantitative information about the impact of educational sessions on patients' psychological and cognitive dimensions related to RT experience were retained for analysis. Results: Of the 25 records found, eight articles about seven studies were analysed that involved 376 patients with different oncological pathologies. Most studies evaluated knowledge and treatment-related anxiety, mainly through self-reported questionnaires. The analysis showed a significant improvement in patients' knowledge and comprehension of radiotherapy treatment. Anxiety levels also decreased with virtual reality educational sessions and throughout the treatment in almost all the studies, although with less homogeneous results. Conclusion: Virtual reality methods in standard educational sessions can enhance cancer patients' preparation for radiation therapy by increasing their understanding of treatment and reducing anxiety.info:eu-repo/semantics/publishedVersio

1985-2000

Caetano, M., Carrao, H., & Painho, M. (2005). Alterações da ocupação do espaço do solo em Portugal Continental: 1985-2000. Lisboa: Instituto do Ambiente.Projecto realizado para o Instituto do Ambiente, no âmbito do protocolo celebrado entre esta entidade e o Instituto Superior de Estatística e Gestão de Informação da Universidade Nova de Lisboa (ISEGI-UNL).publishersversionpublishe

Impact of SGRT on patient positioning: a systematic review

Introdução – Surface guided radiotherapy (SGRT) é uma técnica que utiliza tecnologia na deteção a 3D da superfície do doente e que auxilia o radioterapeuta no reposicionamento diário e na monitorização de movimentos intra e interfração do doente. É uma técnica não invasiva e sem recurso a radiação ionizante. Objetivos – Pretende-se estudar se a técnica SGRT poderá substituir o uso de marcações cutâneas e o uso de protocolos de imagens de verificação/Image-guided radiation therapy (IGRT), sem comprometer a reprodutibilidade do tratamento. Método – Efetuou-se uma revisão sistemática nas bases de dados Scopus e MEDLINE, onde foram analisados artigos publicados nos últimos cinco anos. Após a conjugação dos termos de pesquisa e de acordo com os critérios de inclusão e exclusão identificaram-se dez artigos, que foram incluídos na revisão. Resultados/Discussão – A técnica SGRT reduziu os desvios no posicionamento, comparativamente ao posicionamento com base em marcações cutâneas. Por outro lado, permite uma redução de dose resultante da verificação da IGRT devido à menor frequência da sua utilização, quando conjugado com SGRT. Conclusão – A SGRT mostrou-se viável ao garantir um posicionamento preciso quando comparada com o reposicionamento convencional baseado na conjugação de marcações cutâneas e lasers. Foi ainda possível verificar uma redução significativa dos erros intrafração e interfração. No entanto, ela não foi considerada suficientemente viável para substituir a IGRT na sua totalidade. A IGRT ainda tem um papel importante na confirmação do posicionamento anatómico e na monitorização do PTV e órgãos adjacentes.ABSTRACT - Introduction – Surface-guided radiotherapy (SGRT) is a technique that uses technology in the 3D detection of the patient’s surface, which helps the radiation therapists in the daily repositioning and monitoring of intra and interfraction movements of the patient. It is a non-invasive technique and does not use ionising radiation. Objectives – It is intended to study if the SGRT technique could replace the use of skin markers and the use of verification/Image-guided radiation therapy (IGRT) imaging protocols, without compromising the reproducibility of the treatment. Methods – A systematic review was performed in the Scopus and MEDLINE databases, where articles published in the last five years were analysed. After combining the search terms and according to the inclusion and exclusion criteria, ten articles were included in this review. Results/Discussion – The SGRT technique reduced positioning deviations compared to positioning based on skin markers. On the other hand, it allows a dose reduction resulting from IGRT verification, due to the lower frequency of its use, when combined with SGRT. Conclusion – SGRT proved to be feasible in ensuring accurate positioning when compared to conventional repositioning based on the conjugation of skin markers and lasers. A significant reduction in intrafraction and interfraction errors was also observed. However, it was not considered sufficiently feasible to replace IGRT to its full extent. IGRT still has an important role in confirming anatomical positioning and in monitoring PTV and adjacent organs.info:eu-repo/semantics/publishedVersio