On Component Reliability and System Reliability for Space Missions

This paper is to address the basics, the limitations and the relationship between component reliability and system reliability through a study of flight computing architectures and related avionics components for NASA future missions. Component reliability analysis and system reliability analysis need to be evaluated at the same time, and the limitations of each analysis and the relationship between the two analyses need to be understood

TCT-142 Clinical Characteristics and Outcomes of Patients Undergoing Transcatheter Aortic Valve Replacement With STS PROM of ≤3%

Background Transcatheter aortic valve replacement (TAVR) is the preferred treatment for most patients with aortic stenosis deemed at intermediate or higher risk for surgical aortic valve replacement (SAVR). Determination of the risk of SAVR is mainly based on the Society of Thoracic Surgeons (STS) risk calculator. However, federal regulations permit the heart team latitude to offer TAVR for patients with ≤3% predicted risk of mortality (PROM) whose perceived risk is not adequately accounted for by the STS risk model. Limited data is available on the clinical characteristics and outcomes of these patients Methods The study group involved 2,539 patients who underwent TAVR from 2013 to 2017 within 7 hospitals in 5 Western states in the Providence St. Joseph Health system. The local TAVR site staff completed surveys identifying the clinical factors driving the heart team\u27s decision to proceed with TAVR. Clinical data was also collected per the TVT registry requirements. Results We identified 332 TAVR patients with STS PROM ≤3% and 2,207 patients with STS PROM \u3e3%. The percentage of TAVR patients with an STS PROM increased over time from 5.1% in 2013 to 16.6% in 2017. The most common factors (≥1 possible) influencing the heart team\u27s decision to proceed with TAVR in the ≤3% STS PROM group were frailty (63%), hostile chest (23%), severe lung disease (14%), morbid obesity (10%), and liver disease (8%). The baseline characteristics and outcomes of both groups are listed in the Table. Conclusion The proportion of TAVR patients with STS PROM ≤3% tripled from 2013 to 2017. In comparison to those with STS PROM \u3e3%, they were younger and more often men. The most common reasons driving the decision to favor TAVR over SAVR were frailty, hostile chest, and severe lung disease. TAVR patients with STS PROM ≤3% had shorter hospital stays and were more likely to be alive at 1 year

TCT-804 Outcomes of Trans-Carotid TAVR in a high-Volume Center

Background Although the preferred route for transcatheter aortic valve replacement is through the femoral artery, alternatives remain necessary for patients with obstructive iliofemoral disease. Our valve team has developed a large experience using the carotid artery as a primary alternative vascular access approach for transcatheter aortic valve replacement (TAVR). We aim to compare short-term outcomes by access route in a single-center, high-volume, transcarotid (TC) TAVR program. Methods All patients undergoing TAVR between September 2012 and September 2018 were included in the study. Baseline demographics and outcomes were obtained from data our institution submitted in compliance with TVT (Transcatheter Valve Therapy) reporting and are supplemented by individual chart review. Results Overall, 1,153 commercial TAVR procedures were completed during the study period. Of these, 976 (85%) were transfemoral (TF), 105 (9%) were TC, and 72 (6%) were other (53 transapical, 14 transaxillary, 5 transaortic). TF patients had lower Society of Thoracic Surgeons (STS) scores (6.0% vs. 7.1% vs. 8.3%), peripheral vascular disease (24% vs. 88% vs. 72%), and cerebral vascular disease (11% vs. 17% vs. 32%) compared with TC and other patients, respectively (p \u3c 0.001). Combined in-hospital and 30-day mortality was 2.6% for the TF cohort versus 3.8% for TC (p = 0.36) and 13.9% for other (p \u3c 0.001). The stroke rate at 30 days was 3.7% for TF versus 3.8% for TC and 4.2% for other access routes (p = 0.98) (Table). Conclusion TAVR can be safely performed from the TC access route at a high-volume center with similar in-hospital and 30-day mortality and stroke rates compared with TF patients. Mortality was significantly increased, however, in patients treated with other alternative access routes

Towards an Economy of Higher Education

This paper draws a distinction between ways thinking and acting, and hence of policy and practice in higher education, in terms of different kinds of economy: economies of exchange and economies of excess. Crucial features of economies of exchange are outlined and their presence in prevailing conceptions of teaching and learning is illustrated. These are contrasted with other possible forms of practice, which in turn bring to light the nature of an economy of excess. In more philosophical terms, and to expand on the picture, economies of excess are elaborated with reference, first, to the understanding of alterity in the work of Emmanuel Levinas and, second, to the idea of Dionysian intensity that is to be found in Nietzsche. In the light of critical comment on some current directions in policy and practice, the implications of these ways of thinking for the administrator, the teacher and the student in higher education are explored

Transcatheter or surgical aortic-valve replacement in intermediate-risk patients

BACKGROUND: Previous trials have shown that among high-risk patients with aortic stenosis, survival rates are similar with transcatheter aortic-valve replacement (TAVR) and surgical aorticvalve replacement. We evaluated the two procedures in a randomized trial involving intermediate-risk patients. METHODS: We randomly assigned 2032 intermediate-risk patients with severe aortic stenosis, at 57 centers, to undergo either TAVR or surgical replacement. The primary end point was death from any cause or disabling stroke at 2 years. The primary hypothesis was that TAVR would not be inferior to surgical replacement. Before randomization, patients were entered into one of two cohorts on the basis of clinical and imaging findings; 76.3% of the patients were included in the transfemoral-access cohort and 23.7% in the transthoracic-access cohort. RESULTS: The rate of death from any cause or disabling stroke was similar in the TAVR group and the surgery group (P=0.001 for noninferiority). At 2 years, the Kaplan–Meier event rates were 19.3% in the TAVR group and 21.1% in the surgery group (hazard ratio in the TAVR group, 0.89; 95% confidence interval [CI], 0.73 to 1.09; P=0.25). In the transfemoralaccess cohort, TAVR resulted in a lower rate of death or disabling stroke than surgery (hazard ratio, 0.79; 95% CI, 0.62 to 1.00; P=0.05), whereas in the transthoracic-access cohort, outcomes were similar in the two groups. TAVR resulted in larger aortic-valve areas than did surgery and also resulted in lower rates of acute kidney injury, severe bleeding, and new-onset atrial fibrillation; surgery resulted in fewer major vascular complications and less paravalvular aortic regurgitation. CONCLUSIONS: In intermediate-risk patients, TAVR was similar to surgical aortic-valve replacement with respect to the primary end point of death or disabling stroke. (Funded by Edwards Lifesciences; PARTNER 2 ClinicalTrials.gov number, NCT01314313

A land-to-ocean perspective on the magnitude, source and implication of DIC flux from major Arctic rivers to the Arctic Ocean

Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 26 (2012): GB4018, doi:10.1029/2011GB004192.A series of seasonally distributed measurements from the six largest Arctic rivers (the Ob', Yenisey, Lena, Kolyma, Yukon and Mackenzie) was used to examine the magnitude and significance of Arctic riverine DIC flux to larger scale C dynamics within the Arctic system. DIC concentration showed considerable, and synchronous, seasonal variation across these six large Arctic rivers, which have an estimated combined annual DIC flux of 30 Tg C yr−1. By examining the relationship between DIC flux and landscape variables known to regulate riverine DIC, we extrapolate to a DIC flux of 57 ± 9.9 Tg C yr−1for the full pan-arctic basin, and show that DIC export increases with runoff, the extent of carbonate rocks and glacial coverage, but decreases with permafrost extent. This pan-arctic riverine DIC estimate represents 13–15% of the total global DIC flux. The annual flux of selected ions (HCO3−, Na+, Ca2+, Mg2+, Sr2+, and Cl−) from the six largest Arctic rivers confirms that chemical weathering is dominated by inputs from carbonate rocks in the North American watersheds, but points to a more important role for silicate rocks in Siberian watersheds. In the coastal ocean, river water-induced decreases in aragonite saturation (i.e., an ocean acidification effect) appears to be much more pronounced in Siberia than in the North American Arctic, and stronger in the winter and spring than in the late summer. Accounting for seasonal variation in the flux of DIC and other major ions gives a much clearer understanding of the importance of riverine DIC within the broader pan-arctic C cycle.Funding for this work was provided through NSF-OPP-0229302 and NSF-OPP-0732985. Additional support to SET was provided by an NSERC Postdoctoral Fellowship.2013-06-1

Locomotor changes in length and EMG activity of feline medial gastrocnemius muscle following paralysis of two synergists

The mechanism of the compensatory increase in electromyographic activity (EMG) of a cat ankle extensor during walking shortly after paralysis of its synergists is not fully understood. It is possible that due to greater ankle flexion in stance in this situation, muscle spindles are stretched to a greater extent and, thus, contribute to the EMG enhancement. However, also changes in force feedback and central drive may play a role. The aim of the present study was to investigate the short-term (1- to 2-week post-op) effects of lateral gastrocnemius (LG) and soleus (SO) denervation on muscle fascicle and muscle–tendon unit (MTU) length changes, as well as EMG activity of the intact medial gastrocnemius (MG) muscle in stance during overground walking on level (0%), downslope (−50%, presumably enhancing stretch of ankle extensors in stance) and upslope (+50%, enhancing load on ankle extensors) surfaces. Fascicle length was measured directly using sonomicrometry, and MTU length was calculated from joint kinematics. For each slope condition, LG-SO denervation resulted in an increase in MTU stretch and peak stretch velocity of the intact MG in early stance. MG muscle fascicle stretch and peak stretch velocity were also higher than before denervation in downslope walking. Denervation significantly decreased the magnitude of MG fascicle shortening and peak shortening velocity during early stance in level and upslope walking. MG EMG magnitude in the swing and stance phases was substantially greater after denervation, with a relatively greater increase during stance of level and upslope walking. These results suggest that the fascicle length patterns of MG muscle are significantly altered when two of its synergists are in a state of paralysis. Further, the compensatory increase in MG EMG is likely mediated by enhanced MG length feedback during downslope walking, enhanced feedback from load-sensitive receptors during upslope walking and enhanced central drive in all walking conditions

Sustainable Urban Systems: Co-design and Framing for Transformation

Rapid urbanisation generates risks and opportunities for sustainable development. Urban policy and decision makers are challenged by the complexity of cities as social–ecological–technical systems. Consequently there is an increasing need for collaborative knowledge development that supports a whole-of-system view, and transformational change at multiple scales. Such holistic urban approaches are rare in practice. A co-design process involving researchers, practitioners and other stakeholders, has progressed such an approach in the Australian context, aiming to also contribute to international knowledge development and sharing. This process has generated three outputs: (1) a shared framework to support more systematic knowledge development and use, (2) identification of barriers that create a gap between stated urban goals and actual practice, and (3) identification of strategic focal areas to address this gap. Developing integrated strategies at broader urban scales is seen as the most pressing need. The knowledge framework adopts a systems perspective that incorporates the many urban trade-offs and synergies revealed by a systems view. Broader implications are drawn for policy and decision makers, for researchers and for a shared forward agenda