Advanced composites in sailplane structures: Application and mechanical properties

Advanced Composites in sailplanes mean the use of carbon and aramid fibers in an epoxy matrix. Weight savings were in the range of 8 to 18% in comparison with glass fiber structures. The laminates will be produced by hand-layup techniques and all material tests were done with these materials. These values may be used for calculation of strength and stiffness, as well as for comparison of the materials to get a weight-optimum construction. Proposals for material-optimum construction are mentioned

Composite rotor blades for large wind energy installations

The design of large wind power systems in Germany is reviewed with attention given to elaboration of the total wind energy system, aerodynamic design of the rotor blade, and wind loading effects. Particular consideration is given to the development of composite glass fiber/plastic or carbon fiber/plastic rotor blades for such installations

Static Friction between Elastic Solids due to Random Asperities

Several workers have established that the Larkin domains for two three dimensional nonmetallic elastic solids in contact with each other at a disordered interface are enormously large. This implies that there should be negligible static friction per unit area in the macroscopic solid limit. The present work argues that the fluctuations in the heights of the random asperities at the interface that occur in the Greenwood-Williamson model can account for static friction.Comment: Contains some improvements in the treatment of the subjec

An integrated approach for treatment of acute type a aortic dissection

Background and objective: We reviewed a single-institution experience to verify the impact of surgery during different time intervals on early and late results in the treatment of patients with type A acute aortic dissection (A-AAD). Materials and Methods: From 2004 to 2021, a total of 258 patients underwent repair of A-AAD; patients were equally distributed among three periods: 2004–2010 (Era 1, n = 90), 2011–2016 (Era 2, n = 87), and 2017–2021 (Era 3, n = 81). The primary end-point was to assess whether through the years changes in indications, surgical strategies and techniques and increasing experience have influenced early and late outcomes of A-AAD repair. Results: Axillary artery cannulation was almost routinely used in Eras 2 (86%) and 3 (91%) while one femoral artery was mainly cannulated in Era 1 (91%) (p < 0.01). Retrograde cerebral perfusion was predominantly used in Era 1 (60%) while antegrade cerebral perfusion was preferred in Eras 2 (94%,) and 3 (100%); (p < 0.01). There was a significant increase of arch replacement procedures from Era 1 (11%) to Eras 2 (33%) and 3 (48%) (p < 0.01). A frozen elephant trunk was mainly performed in Era 3. Hospital mortality was 13% in Era 1, 11% in Era 2, and 4% in Era 3 (p = 0.07). Actuarial survival at 3 years is 74%, in Era 1, 78% in Era 2, and 89% in Era 3 (p = 0.05). Conclusions: With increasing experience and a more aggressive approach, including total arch replacement, repair of A-AAD can be performed with low operative mortality in many patients. Patient care and treatment by a specific team organization allows a faster diagnosis and referral for surgery allowing to further improve early and late outcomes

Distal Reoperations after Repair of Acute Type A Aortic Dissection—Incidence, Causes and Outcomes

Background and Aim of the Study: In patients with acute type A aortic dissection (A-AAD) whether initial repair should include also aortic arch replacement is still debated. We aimed to assess if extensive aortic repair prevents from reoperations patients with A-AAD. Methods: Outcomes after distal reoperation following repair of A-AAD (n = 285; 1977 to 2018) were analysed in 22 of 226 who underwent ascending aorta/hemiarch replacement (Group 1R) and 7 of 59 who had ascending aorta/arch replacement (Group 2R). Results: Distal reoperation was more common in Group 1R (n = 22) than in Group 2R (n = 0) (p &lt; 0.001) while thoracic endovascular stenting was more frequent in Group 2R (7 vs 3, p &lt; 0.001). Indications for reoperation were pseudoaneurysm at distal anastomosis (n = 4, 18%) and progression of aortic dissection (n = 18, 82%) in Group 1R. Indication for thoracic endovascular stenting was progressive aortic dissection in 3 patients of Group 1R and in 6 of Group 2R. Second reoperation was required in 2 patients from Group 1R (2%) during a mean follow-up of 5 years. Median follow-up was 4 years in Group 1R and 7 years in Group 2R (p = 0.36). Hospital mortality was 14% in Group 1R and 0% in Group 2R (p = 0.3). Actuarial survival is 68 ± 10%, and 62 ± 11% for Group 1R and 100% for Group 2R at 5 and 10 years (p = 0.076). Conclusions: Distal reoperations after A-AAD repair have an acceptable mortality. An extensive initial repair has lower rate of reoperation and better mid-term survival and should be indicated especially for young patients in experienced centers

Use of sutureless and rapid deployment prostheses in challenging reoperations

Sutureless and rapid-deployment bioprostheses have been introduced as alternatives to traditional prosthetic valves to reduce cardiopulmonary and aortic cross-clamp times during aortic valve replacement. These devices have also been employed in extremely demanding surgical settings, as underlined in the present review. Searches on the PubMed and Medline databases aimed to identify, from the English-language literature, the reported cases where both sutureless and rapid-deployment prostheses were employed in challenging surgical situations, usually complex reoperations sometimes even performed as bailout procedures. We have identified 25 patients for whom a sutureless or rapid-deployment prosthesis was used in complex redo procedures: 17 patients with a failing stentless bioprosthesis, 6 patients with a failing homograft, and 2 patients with the failure of a valve-sparing procedure. All patients survived reoperation and were reported to be alive 3 months to 4 years postoperatively. Sutureless and rapid-deployment bioprostheses have proved effective in replacing degenerated stentless bioprostheses and homografts in challenging redo procedures. In these settings, they should be considered as a valid alternative not only to traditional prostheses but also in selected cases to transcatheter valve-in-valve solutions

Diagnosis and treatment of idiopathic premature ventricular contractions: A stepwise approach based on the site of origin

Premature ventricular contractions in the absence of structural heart disease are among the most common arrhythmias in clinical practice, with well-defined sites of origin in the right and left ventricle. In this review, starting from the electrocardiographic localization of premature ventricular contractions, we investigated the mechanisms, prevalence in the general population, diagnostic work-up, prognosis and treatment of premature ventricular contractions, according to current scientific evidence

Under-reporting bicycle accidents to police in the COST TU1101 international survey: Cross-country comparisons and associated factors

Police crash reports are often the main source for official data in many countries. However, with the exception of fatal crashes, crashes are often underreported in a biased manner. Consequently, the countermeasures adopted according to them may be inefficient. In the case of bicycle crashes, this bias is most acute and it probably varies across countries, with some of them being more prone to reporting accidents to police than others. Assessing if this bias occurs and the size of it can be of great importance for evaluating the risks associated with bicycling. This study utilized data collected in the COST TU1101 action “Towards safer bicycling through optimization of bicycle helmets and usage”. The data came from an online survey that included questions related to bicyclists' attitudes, behaviour, cycling habits, accidents, and patterns of use of helmets. The survey was filled by 8655 bicyclists from 30 different countries. After applying various exclusion factors, 7015 questionnaires filled by adult cyclists from 17 countries, each with at least 100 valid responses, remained in our sample. The results showed that across all countries, an average of only 10% of all crashes were reported to the police, with a wide range among countries: from a minimum of 0.0% (Israel) and 2.6% (Croatia) to a maximum of a 35.0% (Germany). Some factors associated with the reporting levels were type of crash, type of vehicle involved, and injury severity. No relation was found between the likelihood of reporting and the cyclist's gender, age, educational level, marital status, being a parent, use of helmet, and type of bicycle. The significant under-reporting – including injury crashes that do not lead to hospitalization – justifies the use of self-report survey data for assessment of bicycling crash patterns as they relate to (1) crash risk issues such as location, infrastructure, cyclists' characteristics, and use of helmet and (2) strategic approaches to bicycle crash prevention and injury reduction.Fil: Shinar, D.. Ben Gurion University of the Negev; IsraelFil: Valero Mora, Pedro. Universidad de Valencia; EspañaFil: van Strijp Houtenbos, M.. Institute For Road Safety Research; Países BajosFil: Haworth, N.. Queensland University of Technology; AustraliaFil: Schramm, A.. Queensland University of Technology; AustraliaFil: de Bruyne, G.. Universiteit Antwerp; BélgicaFil: Cavallo, V.. No especifíca;Fil: Chliaoutakis, J.. No especifíca;Fil: Pereira Dias, Joao. Instituto Superior Tecnico; PortugalFil: Ferraro, Ottavia Eleonora. Universita Degli Studi Di Pavia; ItaliaFil: Fyhri, Aslak. No especifíca;Fil: Sajatovic, Anika Hursa. No especifíca;Fil: Kuklane, Kalev. Lund University; SueciaFil: Ledesma, Ruben Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Psicología Básica, Aplicada y Tecnología. Universidad Nacional de Mar del Plata. Facultad de Psicología. Instituto de Psicología Básica, Aplicada y Tecnología.; ArgentinaFil: Calvé Mascarell, Oscar. Ben Gurion University of the Negev; IsraelFil: Morandi, A.. Universita Degli Studi Di Pavia; ItaliaFil: Muser, Markus. No especifíca;Fil: Otte, Diettmar. No especifíca;Fil: Papadakaki, M.. No especifíca;Fil: Sanmartín, J.. Universidad de Valencia; EspañaFil: Dulf, D.. No especifíca;Fil: Saplioglu, M.. No especifíca;Fil: Tzamalouka, Georgia. No especifíca

Partitioning of bronchopulmonary carcinoids in two different prognostic categories by Ki-67 score

Introduction: Histological distinction between typical and atypical bronchopulmonary car- cinoids is based on mitotic activity and necrosis. Regardless of these two parameters, outcome after surgery is often unpredictable. In this study the prognostic value of different clinico-pathological factors was retrospectively analyzed in a large series of patients with bronchopulmonary carcinoid. Materials and Methods: The long-term post-surgical out- come of 106 radically treated patients affected by bronchopulmonary carcinoid from two Italian centers was correlated with tumor characteristics assessed by combining conven- tional histology with a panel of immunohistochemical markers of neuroendocrine differen- tiation (chromogranin-A, NSE) and proliferation activity (Ki-67 score). Results: Carcinoids were assessed as typical (TC = 75; 70.8%) and atypical (AC = 31; 29.2%). Mean follow-up was 8.3 years (range: 0-20; median: 8.0). All cases expressed neuroendocrine markers. At univariate analysis, tumor recurrence [14/75 TC (18.7%), 15/31 AC (48.4%)] correlated with carcinoid histotype (P = 0.003), tumor size (P = 0.012), mitotic index (P = 0.044), Ki-67 score (P &lt; 0.0001), and synchronous node metastasis (P = 0.037). Of these, Cox multivari- ate analysis confirmed only Ki-67 score as independent predictor of disease recurrence (P = 0.009). The best cut-off for Ki-67 score (calculated by ROC curves) discriminating recurrent vs non-recurrent disease was 4% (sensitivity 79.3%; specificity 83.8%; area under the curve 0.85). By stratifying patients according to this cut-off, a significantly dif- ferent disease-free survival was found (log-rank test P &lt; 0.0001). Conclusion: Ki-67 score accurately separates bronchopulmonary carcinoids in two well-distinct histo-prognostic categories. Ki-67 score predicts the patients outcome better than mitotic count, histotype, and tumor stage and it is therefore helpful in establishing the appropriate follow-up. © 2011 Grimaldi, Muser, Beltrami, Machin, Morelli, Pizzolitto, Talmassons, Marciello, Colao, Monaco, Monaco and Faggiano