Shear viscosity and nonlinear behaviour of whole blood under large amplitude oscillatory shear

We investigated experimentally the rheological behavior of whole human blood subjected to large amplitude oscillatory shear under strain control to assess its nonlinear viscoelastic response. In these rheological tests, the shear stress response presented higher harmonic contributions, revealing the nonlinear behavior of human blood that is associated with changes in its internal microstructure. For the rheological conditions investigated, intra-cycle strain-stiffening and intra-cycle shear-thinning behavior of the human blood samples were observed and quantified based on the Lissajous–Bowditch plots. The results demonstrated that the dissipative nature of whole blood is more intense than its elastic component. We also assessed the effect of adding EDTA anticoagulant on the shear viscosity of whole blood subjected to steady shear flow. We found that the use of anticoagulant in appropriate concentrations did not influence the shear viscosity and that blood samples without anticoagulant preserved their rheological characteristics approximately for up to 8 minutes before coagulation became significant

A Very Rare Case of Coronary Artery Bypass Grafting in a Progeria Child

Hutchinson-Gilford progeria syndrome is a rare genetic disorder, characterized by progressive premature aging and early death in the first or second decade of life, usually secondary to cardiovascular events (myocardial infarction and stroke). We report a case of a 14-year-old boy with progeria syndrome and cardiac arrest due to myocardial infarction, who was submitted to an immediate coronary angiography which revealed left main stem and three-vessel coronary artery disease. A prompt double bypass coronary artery grafting surgery was performed, and, despite successful coronary reperfusion, the patient remained in coma and brain death was declared on fourth day after surgery.info:eu-repo/semantics/publishedVersio

Hydro-wind optimal operation for joint bidding in day-ahead market: storage efficiency and impact of wind forecasting uncertainty

Wind power production is uncertain. The imbalance between committed and delivered energy in pool markets leads to the increase of system costs, which must be incurred by defaulting producers, thereby decreasing their revenues. To avoid this situation, wind producers can submit their bids together with hydro resources. Then the mismatches between the predicted and supplied wind power can be used by hydro producers, turbining or pumping such differences when convenient. This study formulates the problem of hydro-wind production optimization in operation contexts of pool market. The problem is solved for a simple three-reservoir cascade case to discuss optimization results. The results show a depreciation in optimal revenues from hydro power when wind forecasting is uncertain. The depreciation is caused by an asymmetry in optimal revenues from positive and negative wind power mismatches. The problem of neutralizing the effect of forecasting uncertainty is subsequently formulated and solved for the three-reservoir case. The results are discussed to conclude the impacts of uncertainty on joint bidding in pool market contexts.info:eu-repo/semantics/acceptedVersio

Surgical Ablation of Atrial Fibrillation and Left Atrial Appendage Occlusion by a Totally Videothoracoscopic Approach - New Paradigm?

Introduction: Atrial fibrillation (AF) contributes to increased morbidity and mortality. Pharmacological and percutaneous catheter therapies are unsatisfactory, with potential serious adverse effects. Cox-Maze III/IV surgery, with higher rates of success, has not been widely adopted because of the associated complexity of the procedure. Methods: We performed a retrospective analysis of the first patients submitted to surgical ablation of AF with occlusion of the left atrial appendage with a totally videothoracoscopic (VATS) approach in our institution. We describe the surgical technique and our results, including duration of surgery, hospital stay, complications and maintenance of sinus rhythm after surgery, at 6, 12 and 18 months of follow-up. Results: We studied 15 patients (ages ranging from 39 to 75 years old; 54,5% female gender). Mean time since the diagnosis of AF was 5,75 years. All had been submitted to prior catheter ablation (mean of 2 attempts). Mean diameter and volume of the left atrium was 42 mm (M-mode) and 70 ml (43 ml/m2), respectively. Mean duration of surgery was 2 hours and 22 minutes. In one patient we had to convert the surgery to median sternotomy. Mean hospital stay was 4,8 days. Mean time of follow-up was 12 months. During follow-up, 91%, 90% and 80% of the patients were in sinus rhythm at 6, 12 and 18 months, respectively. Conclusion: This surgical approach represents a real benefit for those patients with multiple attempts of catheter ablation without success. However, a larger sample of patients with a longer period of follow-up is necessary for further conclusions.info:eu-repo/semantics/publishedVersio

Quality of Life Among Adults with Repaired Tetralogy of Fallot: a Literature Review

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. Survival into adulthood is currently expected following surgical repair, leading to a growing population of adults with repaired TOF. In this literature review, we aim to summarize the current state of knowledge on the quality of life of adults with repaired TOF. A search was conducted on PubMed and results were reviewed for articles published between January of 2010 and June of 2020. Search terms included "Tetralogy of Fallot", "repaired", "adults" and "quality of life". For the subjective health status evaluation, most published studies used Short-Form-36. Most studies agree that physical complex status is poorer for adult patients with repaired TOF than for controls. Mental complex status was also lower. Patients reported similar satisfaction with their lives and levels of social participation. Most patients had a college or university degree. Higher education, male gender and having a partner were positively associated with being employed. Studies found no difference in the proportion of patients that are married or living with a partner, compared to control groups. Patients operated for TOF have a lower reproduction rate compared with the background population. A consistent finding of these studies is abnormal physical parameters compared to psychosocial issues. The diverse needs of adults with repaired TOF require a multidisciplinary care, that takes into consideration all aspects that affect their quality of life. Despite abnormal physical functional status, it is reassuring that most adult patients with TOF lead independent and productive lives.info:eu-repo/semantics/publishedVersio

Rheological behavior of human blood in uniaxial extensional flow

We present an investigation of the rheological behavior of whole human blood under uniaxial extensional flow. For that purpose, capillary breakup experiments were carried out by combining the slow retraction method, high-speed imaging techniques and an immiscible oil bath. The use of the oil bath was aimed at reducing liquid loss by evaporation and to reduce light refraction effects, thus allowing the visualization of the blood cells during the filament thinning. Extensional relaxation times were measured for whole blood samples collected from a total of thirteen healthy adult volunteers from both genders, with hematocrit levels between 38.7% and 46.3%. For this range of red blood cell concentrations, the variation of the extensional relaxation time is small, with the average extensional relaxation times measured in air and in oil being 114±30 μs and 259±47 μs, respectively. An increase of the red blood cells concentration leads to an increase of the bulk viscosity of the sample, which delays the thinning of the filament and consequently the time to breakup. In addition, blood aging was found to reduce the relaxation time while the absence of anticoagulant increases it significantly

Phytoplankton dynamics in relation to seasonal variability and upwelling and relaxation patterns at the mouth of Ria de Aveiro (West Iberian Margin) over a four-year period

From June 2004 to December 2007, samples were weekly collected at a fixed station located at the mouth of Ria de Aveiro (West Iberian Margin). We examined the seasonal and inter-annual fluctuations in composition and community structure of the phytoplankton in relation to the main environmental drivers and assessed the influence of the oceano-graphic regime, namely changes in frequency and intensity of upwelling events, over the dynamics of the phytoplankton assemblage. The samples were consistently handled and a final subset of 136 OTUs (taxa with relative abundance > 0.01%) was subsequently submitted to various multivariate analyses. The phytoplankton assemblage showed significant changes at all temporal scales but with an overriding importance of seasonality over longer-(inter-annual) or shorter-term fluctuations (upwelling-related). Sea-surface temperature, salinity and maximum upwelling index were retrieved as the main driver of seasonal change. Seasonal signal was most evident in the fluctuations of chlorophyll a concentration and in the high turnover from the winter to spring phytoplankton assemblage. The seasonal cycle of production and succession was disturbed by upwelling events known to disrupt thermal stratification and induce changes in the phytoplankton assemblage. Our results indicate that both the frequency and intensity of physical forcing were important drivers of such variability, but the outcome in terms of species composition was highly dependent on the available local pool of species and the timing of those events in relation to the seasonal cycle. We conclude that duration, frequency and intensity of upwelling events, which vary seasonally and inter-annually, are paramount for maintaining long-term phytoplankton diversity likely by allowing unstable coexistence and incorporating species turnover at different scales. Our results contribute to the understanding of the complex mechanisms of coastal phytoplankton dynamics in relation to changing physical forcing which is fundamental to improve predictability of future prospects under climate change.Portuguese Foundation for Science and Technology (FCT, Portugal) [SFRH/BPD/ 94562/2013]; FEDER funds; national funds; CESAM [UID/AMB/50017]; FCT/MEC through national funds; FEDERinfo:eu-repo/semantics/publishedVersio

Proximal tibial osteophytes and their relationship with the height of the tibial spines of the intercondylar eminence: paleopathological study

Tibial spiking (i.e., spurring of tibial spines), eburnation, and osteophytes are considered features of osteoarthritis. This investigation employed direct inspection of the medial and lateral tibial plateaus in paleopathological specimens to analyze the frequency and morphological features of osteoarthritis and to define any relationship between the size of osteophytes and that of the intercondylar tibial spines. A total of 35 tibial bone specimens were evaluated for the degree of osteoarthritis and presence of eburnation. Each plateau was also divided into four quadrants and the presence and size of bone outgrowths were recorded in each quadrant. The “medial/lateral tibial intercondylar spine index” for each specimen was calculated as follows: (medial/lateral intercondylar tibial spine height)/(anteroposterior width of the superior tibial surface). The relationships between medial and lateral tibial height indexes with the degree of osteoarthritis were then tested. Osteophytes were observed more frequently in the anterior quadrants of both tibial plateaus than in the posterior quadrants (29 vs 16 for the medial tibial plateau [p = 0.01] and 28 vs 20 for the lateral tibial plateau [p = 0.04]). Eburnation was seen more frequently in the posterior regions of both tibial plateaus than in the anterior regions (17 vs 5, p < 0.01). In specimens with no signs of osteoarthritis the lateral intercondylar tibial index was significantly lower than that in specimens with some degree of osteoarthritis (p = 0.02). The medial intercondylar tibial index of the specimens with no signs of osteoarthritis was not significantly different from that of the specimens with some degree of osteoarthritis (p = 0.45). There was a positive correlation between the lateral spine height index and the overall grading of osteoarthritis, (r = 0.6, p < 0.01). In the anteromedial and posteromedial quadrants of the lateral tibial plateau, the association between the lateral intercondylar tibial spine index and the grade of osteophytes was 0.5 (p < 0.01) and 0.7 (p < 0.01) respectively. Spiking of the lateral tibial intercondylar spine is associated with osteophyte formation and osteoarthritis. Eburnation occurs mainly in the posterior parts of the tibial plateaus while osteophytes arise mainly in the anterior parts. These findings suggest that stresses occurring in the flexed knee may contribute to many of the morphological abnormalities of osteoarthritis