In Vitro Characterisation of Physiological and Maximum Elastic Modulus of Ascending Thoracic Aortic Aneurysms Using Uniaxial Tensile Testing

AbstractObjectiveAscending thoracic aortic aneurysms (ATAA) are a life-threatening condition due to the risk of rupture or dissection. This risk is increased in the presence of a bicuspid aortic valve (BAV). The purpose of this study was to provide data on the elastic modulus of aortic wall of ATAA using uniaxial tensile testing in two different areas of the stress–strain relationship: physiological and maximum range of stresses. The influence of tissue location, tissue orientation and valve type on these parameters was investigated.Materials and methodsTissues freshly excised from ATAA with bicuspid or tricuspid aortic valve were obtained from greater and lesser curvature (GC and LC) and the specimens were tested uniaxially in circumferential (CIRC) and longitudinal (LONG) orientation. Maximum elastic modulus (MEM) was given by the maximum slope of the stress–strain curve before failure. Physiological modulus (PM) was derived from the Laplace law and from ranges of pressure of 80–120 mmHg. Means of each group of specimen were compared using Student's t-test to assess the influence of location, orientation and valve type on each mechanical parameter.ResultsPM was found to be significantly lower than the MEM (p < 0.001). The MEM and PM were significantly higher (p < 0.01) in the CIRC (n = 66) than in the LONG orientation (n = 42). The MEM was higher in the circumferential orientation in the BAV group (p < 0.001 in GC and p < 0.05 in LC). MEM and PM in GC specimens were higher in the longitudinal orientation than the LC specimens (p < 0.05).ConclusionThis study demonstrates the anisotropy of the aortic wall in ATAA and provides data on the mechanical behaviour in the physiological range of pressure

Lower Rate of Restenosis and Reinterventions With Covered vs Bare Metal Stents Following Innominate Artery Stenting

PURPOSE: To determine any difference between bare metal stents (BMS) and balloon-expandable covered stents in the treatment of innominate artery atheromatous lesions. MATERIALS AND METHODS: A multicenter retrospective study involving 13 university hospitals in France collected 93 patients (mean age 63.2±11.1 years; 57 men) treated over a 10-year period. All patients had systolic blood pressure asymmetry &gt;15 mm Hg and were either asymptomatic (39, 42%) or had carotid (20, 22%), vertebrobasilar (24, 26%), and/or brachial (20, 22%) symptoms. Innominate artery stenosis ranged from 50% to 70% in 4 (4%) symptomatic cases and between 70% and 90% in 52 (56%) cases; 28 (30%) lesions were preocclusive and 8 (9%) were occluded. One (1%) severely symptomatic patient had a &lt;50% stenosis. Demographic characteristics, operative indications, and procedure details were compared between the covered (36, 39%) and BMS (57, 61%) groups. Multivariate analysis was performed to determine relative risks of restenosis and reinterventions [reported with 95% confidence intervals (CI)]. RESULTS: The endovascular procedures were performed mainly via retrograde carotid access (75, 81%). Perioperative strokes occurred in 4 (4.3%) patients. During the mean 34.5±31.2-month follow-up, 30 (32%) restenoses were detected and 13 (20%) reinterventions were performed. Relative risks were 6.9 (95% CI 2.2 to 22.2, p=0.001) for restenosis and 14.6 (95% CI 1.8 to 120.8, p=0.004) for reinterventions between BMS and covered stents. The severity of the treated lesions had no influence on the results. CONCLUSION: Patients treated with BMS for innominate artery stenosis have more frequent restenoses and reinterventions than patients treated with covered stents

Growth of the digital footprint of the society of critical care medicine annual congress: 2014-2020

Objectives: Since 2014, the Society of Critical Care Medicine has encouraged “live-tweeting” through the use of specific hashtags at each annual Critical Care Congress. We describe how the digital footprint of the Society of Critical Care Medicine Congress on Twitter has evolved at a time when social media use at conferences is becoming increasingly popular. Design: We used Symplur Signals (Symplur LLC, Pasadena, CA) to track all tweets containing the Society of Critical Care Medicine Congress hashtag for each annual meeting between 2014 and 2020. We collected data on the number of tweets, tweet characteristics, and impressions (i.e., potential views) for each year and data on the characteristics of the top 100 most actively tweeting users of that Congress

North Flinders Reef (Coral Sea, Australia) Porites sp. corals as a candidate Global Boundary Stratotype Section and Point for the Anthropocene Series

Corals are unique in the suite of proposed Anthropocene Global Boundary Stratotype Section and Point (GSSP) archives, as living organisms that produce aragonite exoskeletons preserved in the geological record that contain highly accurate and precise (<±1 year) internal chronologies. The GSSP candidate site North Flinders Reef in the Coral Sea (Australia) is an offshore oceanic reef, and therefore less vulnerable to local human influences than those closer to the coast. Here, we present geochemical records from two Porites sp. corals sampled at an annual to pluri-annual (i.e. 3–5 years) resolution that shows clear global and regional human impacts. Atmospheric nuclear bomb testing by-products (14C,239+240Pu) show a clear increase in the Flinders Reef corals coincident with well-dated nuclear testing operations. By contrast, the radionuclides 241Am and 137Cs are present at low or undetectable levels, as are spheroidal carbonaceous fly-ash particles. Coral δ13C shows centennial variability likely influenced by growth effects in the 18th century and with a progression to lower values starting in 1880 and accelerating post-1970. The latter may be related to the Suess Effect resulting from 13C-depleted fossil fuel burning. Coral δ15N decreased between 1710 and 1954 with a reversal post-1954. Coral temperature proxies indicate prominent centennial variability with equally warm conditions in the 18th and end of 20th century. However, the exact mechanisms responsible for the mid-20th century changes in these parameters need to be scrutinised in further detail. Plain Language summary: This work proposes a candidate natural archive for the official marker of the Anthropocene that geologists will use to mark this important interval in time. Our candidate is a live coral from North Flinders Reef in the Coral Sea (Australia), located 150 km east of the Great Barrier Reef, a location that is remote from direct local human influences. Corals are a unique archive of tropical ocean change because they incorporate the geochemical signature from seawater into their limestone skeleton during their long life-spans. Here we investigated a number of geochemical markers in yearly growth layers of the corals to define several markers for the Anthropocene based on changes in temperature, water chemistry, chemicals from pollution and fertilisers, radioactive products from nuclear bomb testing, and by-products from burning fossil fuels. We have detected clear human influences in several of these markers

A two way process – Social capacity as a driver and outcome of equitable marine spatial planning

Although stakeholder engagement is one of the founding principles of marine spatial planning (MSP), meaningful representation of people and their connections to marine resources within marine governance is still lacking. A broad understanding of how concepts surrounding social capital and capacity is translated into MSP practice is missing. With this article, we describe detailed case studies in the United Kingdom, Brazil and South Africa to build a better understanding of the ways in which MSP and other ocean governance initiatives operationalise the concepts of social capital and capacity. Drawing on insights from the cases, we call for a rethinking of capacitation as a two-way process. In particular, trust-building, social learning and efforts to build social capacity should be elaborated without imposing a hierarchy between people ‘who know’ and people ‘who don’t’. Innovative approaches to relationship building, knowledge development, and collaboration highlighted in the case studies highlight ways to build social capacity both among stakeholders and planners, as is necessary for more equitable and sustainable MSP development and implementation

Tibio-femoral joint constraints for bone pose estimation during movement using multi-body optimization

The financial support of the Universita'Italo-Francese (Call Vinci) and of the Department of Human Movement and Sport Sciences of the University of Rome ''Foro Italico'' is gratefully acknowledged. The authors wish to acknowledge Dr. Sophie Lacoste for her technical support and John McCamley for his contribution to the refinement of the manuscriptWhen using skin markers and stereophotogrammetry for movement analysis, bone pose estimation may be performed using multi-body optimization with the intent of reducing the effect of soft tissue artefacts. When the joint of interest is the knee, improvement of this approach requires defining subject-specific relevant kinematic constraints. The aim of this work was to provide these constraints in the form of plausible values for the distances between origin and insertion of the main ligaments (ligament lengths), during loaded healthy knee flexion, taking into account the indeterminacies associated with landmark identification during anatomical calibration. Ligament attachment sites were identified through virtual palpation on digital bone templates. Attachments sites were estimated for six knee specimens by matching the femur and tibia templates to low-dose stereoradiography images. Movement data were obtained using stereophotogrammetry and pin markers. Relevant ligament lengths for the anterior and posterior cruciate, lateral collateral, and deep and superficial bundles of the medial collateral ligaments (ACL, PCL, LCL, MCLdeep, MCLsup) were calculated. The effect of landmark identification variability was evaluated performing a Monte Carlo simulation on the coordinates of the origin-insertion centroids. The ACL and LCL lengths were found to decrease, and the MCLdeep length to increase significantly during flexion, while variations in PCL and MCLsup length was concealed by the experimental indeterminacy. An analytical model is given that provides subject-specific plausible ligament length variations as functions of the knee flexion angle and that can be incorporated in a multi-body optimization procedure