Análise dinâmica de colisão de comboios para projeto de segurança passiva

Trabalho final de mestrado para obtenção do grau Mestre em Engenharia MecânicaEste trabalho visa a modelação multicorpo da colisão de comboios com o objetivo de permitir efetuar simulações da colisão, de modo a observar os fenómenos de absorção de energia, de modo a permitir uma redução dos custos computacionais, mas também dos custos com testes reais. O modelo desenvolvido replica de forma bastante correta uma colisão, podendo servir para análise da colisão. O modelo desenvolvido tem por base um modelo real, sendo este modelo constituído por carruagens, onde uma das carruagens apresenta uma dada velocidade inicial enquanto as outras se encontram em repouso, e buffers, sendo estes últimos estruturas de absorção de energia, estas estruturas encontram-se acopladas às carruagens por molas não lineares. Uma vez que os resultados dependem da curva de rigidez das molas é relativamente simples alterar as características do modelo de modo a simular diferentes tipo de colisão a diferentes velocidades e com diferentes massas. Uma vez que se verifica que quando existe o impacto entre carruagens, não existe recuo do corpo que se encontra inicialmente em movimento, é necessário garantir que o mesmo se verifica nas simulações, esta situação apresentou um grande desafio de simulação, sendo que foram necessárias várias tentativas e modelos, de modo a conseguir replicar o melhor possível este fenómeno. Este projeto oferece uma ferramenta de análise da colisão de carruagens, sendo que a utilização do modelo desenvolvido pode ser útil no projeto e fabrico de carruagens, bem como em projetos de segurança passiva de passageiros.This paper aims the multibody modeling of railway collisions, with the purpose of allow collision simulations, in order to observe the energy absorption phenomena, in order to allow reducing the computing cost, and real test cost as well. The model was developed to replicate quite accurately a collision and can be used for collision analysis. The developed model was based on a real model, being this model was made by carriages, where one of them has an initial velocity while the others are at rest, the model also have buffers, wich are structures for energy absorption, these structures are coupled to the carriages by nonlinear springs. Since the results depend on the springs stiffness curve it is relatively simple to change the characteristics of the model in order to simulate different types of collision, at different velocities with different masses. Since it is found that when there is an impact between carriages there is no recoil of the body that was initially moving, it is necessary to ensure this is what happens in the simulations, this situation presented a big challenge, and several models and trials was made in order to replicate this phenomenon as best as possible. This project offers a different railway crash analysis tool, and the use of the developed model can be useful in the project and manufacture of rail carriages, as well as passive passenger safety projects.N/

Bowel Biofilms: Tipping Points between a Healthy and Compromised Gut?

Bacterial communities are known to impact human health and disease. Mixed species biofilms, mostly pathogenic in nature, have been observed in dental and gastric infections as well as in intestinal diseases, chronic gut wounds and colon cancer. Apart from the appendix, the presence of thick polymicrobial biofilms in the healthy gut mucosa is still debated. Polymicrobial biofilms containing potential pathogens appear to be an early-warning signal of developing disease and can be regarded as a tipping point between a healthy and a diseased state of the gut mucosa. Key biofilm-forming pathogens and associated molecules hold promise as biomarkers. Criteria to distinguish microcolonies from biofilms are crucial to provide clarity when reporting biofilm-related phenomena in health and disease in the gut.</p

Evaluation de divergence de monocot et d'eudicot en utilisant le transcriptome de canne à sucre

Corresponding author : e-mail [email protected];International audienceOver 40,000 sugarcane (Saccharum officinarum) consensus sequences assembled from 237,954 expressed sequence tags were compared with the protein and DNA sequences from other angiosperms, including the genomes of Arabidopsis and rice (Oryza sativa). Approximately two-thirds of the sugarcane transcriptome have similar sequences in Arabidopsis. These sequences may represent a core set of proteins or protein domains that are conserved among monocots and eudicots and probably encode for essential angiosperm functions. The remaining sequences represent putative monocot-specific genetic material, one-half of which were found only in sugarcane. These monocot-specific cDNAs represent either novelties or, in many cases, fast-evolving sequences that diverged substantially from their eudicot homologs. The wide comparative genome analysis presented here provides information on the evolutionary changes that underlie the divergence of monocots and eudicots. Our comparative analysis also led to the identification of several not yet annotated putative genes and possible gene loss events in Arabidopsi

The generation and utilization of a cancer-oriented representation of the human transcriptome by using expressed sequence tags.

Whereas genome sequencing defines the genetic potential of an organism, transcript sequencing defines the utilization of this potential and links the genome with most areas of biology. To exploit the information within the human genome in the fight against cancer, we have deposited some two million expressed sequence tags (ESTs) from human tumors and their corresponding normal tissues in the public databases. The data currently define approximately 23,500 genes, of which only approximately 1,250 are still represented only by ESTs. Examination of the EST coverage of known cancer-related (CR) genes reveals that &amp;lt;1% do not have corresponding ESTs, indicating that the representation of genes associated with commonly studied tumors is high. The careful recording of the origin of all ESTs we have produced has enabled detailed definition of where the genes they represent are expressed in the human body. More than 100,000 ESTs are available for seven tissues, indicating a surprising variability of gene usage that has led to the discovery of a significant number of genes with restricted expression, and that may thus be therapeutically useful. The ESTs also reveal novel nonsynonymous germline variants (although the one-pass nature of the data necessitates careful validation) and many alternatively spliced transcripts. Although widely exploited by the scientific community, vindicating our totally open source policy, the EST data generated still provide extensive information that remains to be systematically explored, and that may further facilitate progress toward both the understanding and treatment of human cancers

Resolved versus confirmed ARDS after 24&#160;h: insights from the LUNG SAFE study

Purpose: To evaluate patients with resolved versus confirmed ARDS, identify subgroups with substantial mortality risk, and to determine the utility of day 2 ARDS reclassification. Methods: Our primary objective, in this secondary LUNG SAFE analysis, was to compare outcome in patients with resolved versus confirmed ARDS after 24\ua0h. Secondary objectives included identifying factors associated with ARDS persistence and mortality, and the utility of day 2 ARDS reclassification. Results: Of 2377 patients fulfilling the ARDS definition on the first day of ARDS (day 1) and receiving invasive mechanical ventilation, 503 (24%) no longer fulfilled the ARDS definition the next day, 52% of whom initially had moderate or severe ARDS. Higher tidal volume on day 1 of ARDS was associated with confirmed ARDS [OR 1.07 (CI 1.01\u20131.13), P = 0.035]. Hospital mortality was 38% overall, ranging from 31% in resolved ARDS to 41% in confirmed ARDS, and 57% in confirmed severe ARDS at day 2. In both\ua0resolved and confirmed\ua0ARDS, age, non-respiratory SOFA score, lower PEEP and P/F ratio, higher peak pressure and respiratory rate were each\ua0associated with mortality. In confirmed ARDS, pH and the presence of immunosuppression or neoplasm were also associated\ua0with mortality. The increase in area under the receiver operating curve for ARDS reclassification on day 2 was marginal. Conclusions: ARDS, whether resolved or confirmed at day 2, has a high mortality rate. ARDS reclassification at day 2 has limited predictive value for mortality. The substantial mortality risk in severe confirmed ARDS suggests that complex interventions might best be tested in this population. Trial Registration: ClinicalTrials.gov NCT02010073. \ua9 2018, Springer-Verlag GmbH Germany, part of Springer Nature and ESICM