976 research outputs found
In situ measured cross section geometry of old timber structures and its influence on structural safety
Old timber structures may show significant variation in the cross section geometry along the same element, as a result of both construction methods and deterioration. As consequence, the definition of the geometric parameters in situ may be both time consuming and costly. This
work presents the results of inspections carried out in different timber structures. Based on the obtained results, different simplified geometric models are proposed in order to efficiently
model the geometry variations found. Probabilistic modelling techniques are also used to define safety parameters of existing timber structures, when subjected to dead and live loads, namely self-weight and wind actions. The parameters of the models have been defined as
probabilistic variables, and safety of a selected case study was assessed using the Monte Carlo simulation technique. Assuming a target reliability index, a model was defined for both the
residual cross section and the time dependent deterioration evolution. As a consequence, it was possible to compute probabilities of failure and reliability indices, as well as, time evolution deterioration curves for this structure. The results obtained provide a proposal for definition of the cross section geometric parameters of existing timber structures with different levels of decay, using a simplified probabilistic geometry model and considering a remaining capacity factor for the decayed areas. This model can be used for assessing the safety of the structure at present and for predicting future performance
Reliability analysis of a timber truss system subjected to decay
Assessing the safety of existing timber structures is of paramount importance for taking reliable decisions on repair actions and their extent. The results obtained through semi-probabilistic methods are unrealistic, as the partial safety factors present in codes are calibrated considering the uncertainty present in new structures. In order to overcome these limitations, and also to include the effects of decay in the safety analysis, probabilistic methods, based on Monte-Carlo simulation are applied here to assess the safety of existing timber structures. In particular, the impact of decay on structural safety is analyzed and discussed, using a simple structural model, similar to that used for current semi-probabilistic analysis
Palliative splenic irradiation for symptomatic splenomegaly in non-Hodgkin lymphoma
INTRODUCTION AND AIMS:
Splenic marginal zone lymphoma, an uncommon subtype of non-Hodgkin lymphoma (NHL), is usually present with symptomatic splenomegaly. Although splenectomy has long been considered the first-line therapy in symptomatic or cytopenic patients, it can lead to significant morbidity and mortality. Splenic irradiation is an option for patients who have a poor response to systemic therapy and/or are not surgical candidates. In this paper, we present a case report of a patient who received splenic radiotherapy for symptomatic splenomegaly.
METHODS:
An 85-year-old Caucasian man with a 4 year history of low-grade NHL presented with progressive pancytopenia, significant weight loss and symptomatic splenomegaly (abdominal discomfort, sense of fullness and limitation of mobility due to spleen size). The patient refused splenectomy and, in December 2017, was referred to palliative splenic radiotherapy. He was initially treated with five fractions of one Grey (Gy) in order to evaluate clinical and haematology response. After that, 1.5 Gy daily, 5 days a week for 3 weeks. 3D conformal radiotherapy, multiple fields and mixed energy (6 and 15 Mv) were used.
RESULTS:
Radiotherapy allowed significant splenic reduction to almost half the size, resolving abdominal discomfort and improving quality of life. There was no decline of haemoglobin, leukocytes and platelet counts; in fact, there was a marginal increase.
CONCLUSION:
Palliative splenic irradiation was well tolerated confirming that it is a safe treatment option for palliation of symptomatic splenomegaly. Thereby, splenic irradiation should be strongly considered in the management of symptomatic splenomegaly, for selected patients who are refractory to or unsuitable for other options or when the patient refuses other treatments.info:eu-repo/semantics/publishedVersio
Total synthesis of the potent immunosuppressant (-)-Pironetin
A convergent and efficient total synthesis of (-)-pironetin, a compound that shows plant growth regulatory activity, and is immunosuppressive as well as having remarkable antitumoral activity, is described. The synthesis required 19 steps from N-propionyl oxazolidinone (S)-9 and produced the desired product in 11% overall yield.6628
Massive mortality of invasive bivalves as a potential resource subsidy for the adjacent terrestrial food web
Large-scale mortality of invasive bivalves
was observed in the River Danube basin in the autumn
of 2011 due to a particularly low water discharge. The
aim of this study was to quantify and compare the
biomass of invasive and native bivalve die-offs
amongst eight different sites and to assess the potential
role of invasive bivalve die-offs as a resource subsidy
for the adjacent terrestrial food web. Invasive bivalve
die-offs dominated half of the study sites and their
highest density and biomass were recorded at the
warm water effluent. The density and biomass values
recorded in this study are amongst the highest values
recorded for aquatic ecosystems and show that a
habitat affected by heated water can sustain an extremely high biomass of invasive bivalves. These
mortalities highlight invasive bivalves as a major
resource subsidy, possibly contributing remarkable
amounts of nutrients and energy to the adjacent
terrestrial ecosystem. Given the widespread occurrence
of these invasive bivalves and the predicted
increase in the frequency and intensity of extreme
climatic events, the ecological impacts generated by
their massive mortalities should be taken into account
in other geographical areas as well.The authors are grateful to David Strayer for valuable comments on a previous version of the manuscript. Special thanks to the Danube-Ipoly National Park for the help in field work. Ronaldo Sousa was supported by the project "ECOIAS" funded by the Portuguese Foundation for the Science and the Technology and COMPETE funds (contract: PTDC/AAC-AMB/116685/2010)
Experimental infection of one-day-old chicks with Salmonella Serotypes Previously isolated from poultry facilities, wild birds, and swine
Prevalence of prognostic factors for cancer of the uterine cervix after radical hysterectomy
The impact of chronic stress on the rat brain lipidome
Chronic stress is a major risk factor for several human disorders that affect modern societies. The brain is a key target of chronic stress. In fact, there is growing evidence indicating that exposure to stress affects learning and memory, decision making and emotional responses, and may even predispose for pathological processes, such as Alzheimer's disease and depression. Lipids are a major constituent of the brain and specifically signaling lipids have been shown to regulate brain function. Here, we used a mass spectrometry-based lipidomic approach to evaluate the impact of a chronic unpredictable stress (CUS) paradigm on the rat brain in a region-specific manner. We found that the prefrontal cortex (PFC) was the area with the highest degree of changes induced by chronic stress. Although the hippocampus presented relevant lipidomic changes, the amygdala and, to a greater extent, the cerebellum presented few lipid changes upon chronic stress exposure. The sphingolipid and phospholipid metabolism were profoundly affected, showing an increase in ceramide (Cer) and a decrease in sphingomyelin (SM) and dihydrosphingomyelin (dhSM) levels, and a decrease in phosphatidylethanolamine (PE) and ether phosphatidylcholine (PCe) and increase in lysophosphatidylethanolamine (LPE) levels, respectively. Furthermore, the fatty-acyl profile of phospholipids and diacylglycerol revealed that chronic stressed rats had higher 38 carbon(38C)-lipid levels in the hippocampus and reduced 36C-lipid levels in the PFC. Finally, lysophosphatidylcholine (LPC) levels in the PFC were found to be correlated with blood corticosterone (CORT) levels. In summary, lipidomic profiling of the effect of chronic stress allowed the identification of dysregulated lipid pathways, revealing putative targets for pharmacological intervention that may potentially be used to modulate stress-induced deficits.Funding by Fundação para a Ciência e Tecnologia (PTDC/SAU-NMC/118971/2010) and by the North Region Operational Program (ON.2-O Novo Norte), under Quadro de Referência Estratégico Nacional (QREN) and through Fundo Europeu de Desenvolvimento Regional (FEDER). GDP is funded by NIH grants R01 NS056049 and P50 AG008702 (to Scott Small)
Brain serotonin depletion enhances the sodium appetite induced by sodium depletion or beta-adrenergic stimulation
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