An in situ study of abyssal turbidity-current sediment plumes generated by a deep seabed polymetallic nodule mining preprototype collector vehicle.

An in situ study to investigate the dynamics of sediment plumes near the release from a deep seabed polymetallic nodule mining preprototype collector vehicle was conducted in the Clarion Clipperton Zone in the Pacific Ocean 4500-m deep. The experiments reveal that the excess density of the released sediment-laden water leads to a low-lying, laterally spreading turbidity current. At the time of measurement, 2 to 8% of the sediment mass were detected 2 m or higher above the seabed and were not observed to settle over several hours, with the remaining 92 to 98% below 2 m and some fraction of that locally deposited. Our results suggest that turbidity current dynamics sets the fraction of sediment remaining suspended and the scale of the subsequent ambient sediment plume. The implications of this process, which is characteristically overlooked in previous modeling efforts, are substantial for plume modeling that will lie at the heart of environmental impact statements for regulatory consideration.

Late correction of tetralogy of Fallot in children.

AIM OF STUDY: To report our experience of late correction after infancy in patients with tetralogy of Fallot (ToF). METHODS: Observational single-centre retrospective analysis of the surgical techniques and perioperative development of patients from developing countries undergoing total surgical correction of ToF after infancy, between 1 November 2011 and 30 November 2016. Variables are presented as numbers with percentages or as mean ± standard deviation. Due to the setting of the humanitarian programme, clinical and echocardiographic follow-up procedures could be conducted for only one month postoperatively. RESULTS: Twenty-five children (mean age: 70.8 ± 42 months, range 23-163; 44% female) underwent total surgical correction of ToF. Two patients (0.8%) initially received a Blalock-Taussig shunt and underwent subsequent correction 24 and 108 months later, respectively. Preoperative mean right ventricular/pulmonary artery (RV/PA) gradient was 84 ± 32 mm Hg, with a Nakata index of 164 ± 71 mm2/m2. Major aortopulmonary collateral arteries (MAPCAs) were observed in eight children (32%), six (26%) of whom underwent transcatheter closure before surgery. 24 children (96%) underwent a valve-sparing pulmonary valve repair and one patient received a transannular patch (TAP). There were no cases which saw major adverse cardiac and cerebrovascular events (MACCE). Mean duration of mechanical ventilation was 28 ± 19.6 hours (range 7-76). Pre-discharge echocardiography demonstrated a mean RV/PA gradient of 25 ± 5.7 mm Hg, with left ventricular ejection fraction >60% in all cases. Overall length of hospital stay was 11.7 ± 4.5 days. There were no in-hospital mortality cases. CONCLUSIONS: Late surgical correction of ToF can be safely performed and produce highly satisfying early postoperative results comparable to those of classical “timely” correction. A valve-sparing technique can be applied in the majority of children.

The role of the organization structure in the diffusion of innovations.

Diffusion and adoption of innovations is a topic of increasing interest in economics, market research, and sociology. In this paper we investigate, through an agent based model, the dynamics of adoption of innovative proposals in different kinds of structures. We show that community structure plays an important role on the innovation diffusion, so that proposals are more likely to be accepted in homogeneous organizations. In addition, we show that the learning process of innovative technologies enhances their diffusion, thus resulting in an important ingredient when heterogeneous networks are considered. We also show that social pressure blocks the adoption process whatever the structure of the organization. These results may help to understand how different factors influence the diffusion and acceptance of innovative proposals in different communities and organizations.