926 resultados para Valve spring steel
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Abstract The aim of this study was to investigate changes in running mechanics and spring-mass behaviour with fatigue induced by 5-hour hilly running (5HHR). Running mechanics were measured pre- and post-5HHR at 10, 12 and 14 km · h(-1) on an instrumented treadmill in eight ultramarathon runners, and sampled at 1000 Hz for 10 consecutive steps. Contact (t(c) ) and aerial (t(a) ) times were determined from ground reaction force (GRF) signals and used to compute step frequency (f). Maximal GRF, loading rate, downward displacement of the centre of mass (Δz), and leg length change (ΔL) during the support phase were determined and used to compute both vertical (K(vert) ) and leg (K(leg) ) stiffness. A significant decrease in t(c) was observed at 12 and 14 km · h(-1) resulting in an increase of f at all speeds. Duty factor and F(max) significantly decreased at 10 km · h(-1). A significant increase in K(vert) and K(leg) was observed at all running speeds with significant decreases in Δz and ΔL. Despite the shorter duration, the changes in running mechanics appeared to be in the same direction (increased f and K(vert) , decrease in Δz and F(max) ) but of lower amplitude compared with those obtained after an ultra-trail or an ultramarathon.
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Donateur : Vassal, Gabrielle Maud (1880-1959)
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Capital intensive industries in specialized niches of production have constituted solid ground for family firms in Spain , as evidenced by the experience of the iron and steel wire industries between 1870 and 2000. The embeddedness of these firms in their local and regional environments have allowed the creation of networks that, together with favourable institutional conditions, significantly explain the dominance of family entrepreneurship in iron and steel wire manufacturing in Spain, until the end of the 20 th century. Dominance of family firms at the regional level has not been not an obstacle for innovation in wire manufacturing in Spain, which has taken place even when institutional conditions blocked innovation and traditional networking. Therefore, economic theories about the difficulties dynastic family firms may have to perform appropriately in science-based industries must be questioned
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The purpose of the newsletter is to communicate with parents and professionals about newborn hearing screening in Iowa. We will share information about: Hearing screenings Intervention Resources available for parents and professionals “Best practices” by hospitals, AEAs (Area Education Agencies), or private practive audiology offices System goals Family stories Highlights from the EHDI Advisory Committee Updates on Iowa’s EHDI program It is important to point out that we are a diverse team of individuals working together to ensure that all newborns and toddlers with hearing loss are identified as early as possible and provided with timely and appropriate audiological, educational and medical intervention. Each newsletter will introduce you to various team members of the EHDI system in Iowa.
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The purpose of the newsletter is to communicate with parents and professionals about newborn hearing screening in Iowa. We will share information about: Hearing screenings Intervention Resources available for parents and professionals “Best practices” by hospitals, AEAs (Area Education Agencies), or private practive audiology offices System goals Family stories Highlights from the EHDI Advisory Committee Updates on Iowa’s EHDI program It is important to point out that we are a diverse team of individuals working together to ensure that all newborns and toddlers with hearing loss are identified as early as possible and provided with timely and appropriate audiological, educational and medical intervention. Each newsletter will introduce you to various team members of the EHDI system in Iowa.
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The purpose of the newsletter is to communicate with parents and professionals about newborn hearing screening in Iowa. We will share information about: Hearing screenings Intervention Resources available for parents and professionals “Best practices” by hospitals, AEAs (Area Education Agencies), or private practive audiology offices System goals Family stories Highlights from the EHDI Advisory Committee Updates on Iowa’s EHDI program It is important to point out that we are a diverse team of individuals working together to ensure that all newborns and toddlers with hearing loss are identified as early as possible and provided with timely and appropriate audiological, educational and medical intervention. Each newsletter will introduce you to various team members of the EHDI system in Iowa.
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The purpose of the newsletter is to communicate with parents and professionals about newborn hearing screening in Iowa. We will share information about: Hearing screenings Intervention Resources available for parents and professionals “Best practices” by hospitals, AEAs (Area Education Agencies), or private practive audiology offices System goals Family stories Highlights from the EHDI Advisory Committee Updates on Iowa’s EHDI program It is important to point out that we are a diverse team of individuals working together to ensure that all newborns and toddlers with hearing loss are identified as early as possible and provided with timely and appropriate audiological, educational and medical intervention. Each newsletter will introduce you to various team members of the EHDI system in Iowa.
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Stents have a long history in traditional valve surgery as both, porcine biological valves as well as pericardial valves are mounted on stents prior to implantation. Recently stent-mounted biological devices have been compressed up to the point, where they can be passed through a catheter. Various routes can be distinguished for implantation: open access, the trans-vascular route in antegrade or retrograde fashion, as well as direct trans-apical or trans-atrial access. Direct access has the potentialforvideo-endoscopic valve replacement. In theory, as well as in the experimental setting, valved stents have been implanted in tricuspid and caval position respectively, as well as in pulmonary, mitral and aortic locations. The largest clinical experience has been achieved in pulmonary position whereas current efforts target the aortic position.
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BACKGROUND: Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry. METHODS AND RESULTS: The Global Valve-in-Valve Registry included 202 patients with degenerated bioprosthetic valves (aged 77.7±10.4 years; 52.5% men) from 38 cardiac centers. Bioprosthesis mode of failure was stenosis (n=85; 42%), regurgitation (n=68; 34%), or combined stenosis and regurgitation (n=49; 24%). Implanted devices included CoreValve (n=124) and Edwards SAPIEN (n=78). Procedural success was achieved in 93.1% of cases. Adverse procedural outcomes included initial device malposition in 15.3% of cases and ostial coronary obstruction in 3.5%. After the procedure, valve maximum/mean gradients were 28.4±14.1/15.9±8.6 mm Hg, and 95% of patients had ≤+1 degree of aortic regurgitation. At 30-day follow-up, all-cause mortality was 8.4%, and 84.1% of patients were at New York Heart Association functional class I/II. One-year follow-up was obtained in 87 patients, with 85.8% survival of treated patients. CONCLUSIONS: The valve-in-valve procedure is clinically effective in the vast majority of patients with degenerated bioprosthetic valves. Safety and efficacy concerns include device malposition, ostial coronary obstruction, and high gradients after the procedure.
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OBJECTIVES: The study aimed to evaluate the feasibility of off-pump transapical mitral valve-in-ring implantation and to test the performance of a custom-made self-expandable stent valve, in comparison with the standard SAPIEN valve. METHODS: Acute experiments were performed in five pigs. Animals (mean weight 58.4 ± 7.3 kg) underwent mitral valve annuloplasties under cardiopulmonary bypass using 26-mm rings (SJM?). Then, a 30-mm custom-made self-expandable stent valve or a 23-mm balloon-expandable transcatheter heart valve (Edwards SAPIEN XT?) was deployed within the annuloplasty rings through a transatrial access and under direct vision. Subsequently, the stent valves were inserted transapically under fluoroscopic guidance and off pump. RESULTS: The procedural success of transatrial and transapical mitral valve-in-ring procedures was 100% (10 of 10). Mean transatrial and transapical procedure time was 2.0 ± 1.1 and 22.0 ± 5.7 min, respectively. Haemodynamic status during transapical implantation remained stable, and differences in data collected before and after the stent-valve deployment were not statistically significant. Mean mitral annulus diameter and mean mitral orifice area in the group of self-expandable stent valves were 2.60 ± 0.02 cm and 4.16 ± 0.48 cm(2), respectively, whereas in the SAPIEN group they were 1.95 ± 0.18 cm and 2.26 ± 0.20 cm(2), respectively. Trace or mild regurgitation was detected only in the self-expandable stent-valve group. Mean gradients were 4.1 ± 4.5 mmHg across the self-expandable stent valves and 1.0 ± 0 mmHg across the SAPIEN valves. Postmortem examination confirmed adequate positioning of the self-expandable valves and the SAPIEN valves within the annuloplasty ring. CONCLUSIONS: Off-pump transapical mitral valve-in-ring implantation is safe and feasible. Transapical access may represent the ideal option for valve-in-ring procedures in cases of recurrent mitral regurgitation after mitral valve repair, in high-risk patients. Owing to the supra-annular profile of the valve components, our custom-made nitinol stent valve provides nearer to normal functional area than the SAPIEN valve.
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Program newsletter used to communicate with parents and professionals about newborn hearing screening in Iowa, including best practice and family stories.
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Program newsletter used to communicate with parents and professionals about newborn hearing screening in Iowa, including best practice and family stories.
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Program newsletter used to communicate with parents and professionals about newborn hearing screening in Iowa, including best practice and family stories.
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Program newsletter used to communicate with parents and professionals about newborn hearing screening in Iowa, including best practice and family stories.