Resilience as a Strategic Imperative in the Age of Uncertainty

The article examines resilience as a new approach to supporting economic growth under the global uncertainty and sudden shocks. We describe resilience as a method for dynamic stabilization of complex systems, as a new imperative for growth policy, and as a new standard of risk management.

Design of a new gas-dynamic stabilization system for a metal-cutting plasma torch

The analysis of the influence of various design solutions of the gas-dynamic stabilization system in plasma torches for cutting metals on the efficiency of equalizing the velocities of gas flows along the cross-section of the gas path is carried out. It is noted that the efficiency evaluation method developed by the authors should be based on the calculation of the uniformity of the gas flow velocity distribution over the cross-section of the gas-air path of the plasma torch. A vortex stabilization system using two swirlers is proposed. The effect of improving the reliability and quality of plasma cutting is shown. The results of the efficiency studies for the proposed system of gas-vortex stabilization in metal-cutting plasma torches are presented. The calculating results of equalization coefficients for the velocity distribution in different parts of the gas-dynamic stabilization system in the plasma torch are presented. Based on the results of the calculations, a constructive optimization of the gas-air path in the plasma torch was performed. The experimentally obtained advantages of the new upgraded plasma torch in terms of the gas-vortex stabilization efficiency are demonstrated. The effects of improved cutting quality and reduced nozzle wear in the new plasma torch are shown. This is due to the higher degree of the plasma arc stabilization in the new plasma torch, which leads to a decrease in its oscillations, and, consequently, to an increase in the efficiency of the cutting process.

Correlation of bone density to screw loosening in dynamic stabilization: an analysis of 176 patients

Although osteoporosis has negative impacts on lumbar fusion, its effects on screw loosening in dynamic stabilization remain elusive. We aimed to correlate bone mineral density (BMD) with screw loosening in Dynesys dynamic stabilization (DDS). Consecutive patients who underwent 2- or 3-level DDS for spondylosis, recurrent disc herniations, or low-grade spondylolisthesis at L3-5 were retrospectively reviewed. BMD was assessed by the Hounsfield Unit (HU) in vertebral bodies (VB) and pedicles with and without cortical bone (CB) on pre-operative computed tomography (CT). Screw loosening was assessed by radiographs and confirmed by CT. HU values were compared between the loosened and intact screws. 176 patients and 918 screws were analyzed with 78 loosened screws found in 36 patients (mean follow-up: 43.4 months). The HU values of VB were similar in loosened and intact screws (p = 0.14). The HU values of pedicles were insignificantly less in loosened than intact screws (including CB: 286.70 ± 118.97 vs. 297.31 ± 110.99, p = 0.45; excluding CB: 238.48 ± 114.90 vs. 240.51 ± 108.91, p = 0.88). All patients had clinical improvements. In conclusion, the HU values, as a surrogate for BMD, were unrelated to screw loosening in DDS. Therefore, patients with compromised BMD might be potential candidates for dynamic stabilization rather than fusion.

Percutaneous Full Endoscopic Posterior Decompression for Revision of Lumbar Spinal Dynamic Stabilization

Objective: The objective of this article was to analysis the efficacy of percutaneous full endoscopic posterior decompression for revision of lumbar spinal dynamic stabilization.Methods: Twenty consecutive patients with failed lumbar spinal dynamic stabilization presenting with leg pain that had supporting imaging diagnosis of lateral stenosis and /or residual / recurrent disc herniation, or whose pain complaint was supported by relief from diagnostic and therapeutic injections, were offered percutaneous transforaminal endoscopic discectomy and foraminoplasty over a repeat open procedure. Each patient sought consultation following a transient successful, partially successful or unsuccessful open lumbar spinal dynamic stabilization surgery for disc herniation or spinal stenosis. Endoscopic foraminoplasty was also performed to either decompress the bony foramen for foraminal stenosis, or foraminoplasty to allow for endoscopic visual examination of the affected traversing and exiting nerve roots in the axilla. The average follow up time was, average 37.9 months, minimum 24 months. Outcome data at each visit included Macnab, VAS and ODI.Results: The average leg Visual Analog Scale improved from 8.9 ± 2.6 to 1.08± 0.7 (p < 0.005). Fifteen patients had excellent outcomes, four had good outcomes, one had fair outcomes, and no had poor outcomes, according to the Macnab criteria (Table 2). Nineteen of 20 patients had excellent or good outcomes, for an overall success rate of 95%. No patients required reoperation. There were no incidental durotomies, infections, vascular or visceral injuries. They were also relieved to be able to avoid "open" decompression.Conclusion: The transforaminal endoscopic approach is effective for failed lumbar spinal dynamic stabilization surgery due to residual/recurrent nucleus pulposus and lateral stenosis. Failed initial index surgery may involve failure to recognize patho-anatomy in the axilla of the foramen housing the traversing and the exiting nerve. The transforaminal endoscopic approach effectively decompresses the foramen and does not further destabilize the spine needing stabilization. It also avoids going through the previous surgical site.

The Discovery of Floating Boats on the Oscillating Levitated Liquid Layer

When air bubbles are injected into a still bath with liquid, it’s known that they will rise to the top surface because of their small mass. However, oscillations, which can provide a dynamical stabilizing effect, can make air bubbles sink when created below a certain depth that changes along with the forcing amplitude. Three experiments are needed to show the defy-gravity behavior caused by vibration on liquid. Using silicon oil, a syringe, a needle, and a vertically oscillating shaker with amplitude, an air layer formed by sinking bubbles, which defy the well-known Archimedes’ principle, is being trapped under the levitating liquid layer acts as a spring-mass. With the further experiment using two light foam boats, it was observed that an upside-down buoyant force was acting on the liquid provided by vibration, supporting the boats to flow on both interfaces of the liquid layer. A symmetric Archimedes’ principle is discovered to be reflected on the lower interface created by the dynamic stabilization as well. This discovery about the effect vibration can have on liquid, and alternately the forces acting on the object floating on this liquid brings lots of future development to light and is new progress in the area of fluid mechanics.