Occult intraspinal abnormalities and congenital scoliosis

Background: Congenital scoliosis occurs because of either the failure of formation or the failure of segmentation or both. Evaluation of the incidence and the types of occult intraspinal abnormalities in congenital scoliosis is the subject of this study. Methods: During a period of 29 years, 103 patients with congenital scoliosis were studied. MRI was used in 46 patients, myelography or CT myelography was used in 64 patients and both MRI and myelography or CT myelography were used in 7 patients for intraspinal abnormalities. Results: In the MRI group, among the 46 patients, 19 patients (41.3) had intraspinal abnormalities consisting syringomyelia in 9 (19.5) diastematomyelia in 8 (17.4), tethered cord syndrome in 6 (13), low conus in 5 (10.8) and diplomyelia in 3 (6.5) of the patients. In the myelography group, among the 64 patients, 17 (26.5) had intraspinal abnormalities and diastematomyelia was the most common one found in 14 (21.8) patients. Conclusions: Intraspinal abnormalities are frequent in congenital scoliosis. Syringomyelia may be associated with congenital scoliosis. In congenital scoliosis, rib fusion may be an indicator of intraspinal abnormalities in MRI. A significant difference between clinical findings and intraspinal anomalies (P<0.05) was noted. Moreover, we believe that total spinal MRI with coronal, sagittal and axial views is a valuable tool in determining the intraspinal abnormalities in congenital scoliosis. This method is highly recommended for detection and neurosurgical intervention before corrective surgeries

A Profit Guided Coordination Heuristic for Travelling Thief Problems

The travelling thief problem (TTP) is a combination of two interdependent NP-hard components: travelling salesman problem (TSP) and knapsack problem (KP). Existing approaches for TTP typically solve the TSP and KP components in an interleaved fashion, where the solution to one component is held fixed while the other component is changed. This indicates poor coordination between solving the two components and may lead to poor quality TTP solutions. For solving the TSP component, the 2-OPT segment reversing heuristic is often used for modifying the tour. We propose an extended and modified form of the reversing heuristic in order to concurrently consider both the TSP and KP components. Items deemed as less profitable and picked in cities earlier in the reversed segment are replaced by items that tend to be equally or more profitable and not picked in the later cities. Comparative evaluations on a broad range of benchmark TTP instances indicate that the proposed approach outperforms existing state-of-the-art TTP solvers

A profit guided coordination heuristic for travelling thief problems

The travelling thief problem (TTP) is a combination of two interdependent NP-hard components: travelling salesman problem (TSP) and knapsack problem (KP). Existing approaches for TTP typically solve the TSP and KP components in an interleaved fashion, where the solution to one component is held fixed while the other component is changed. This indicates poor coordination between solving the two components and may lead to poor quality TTP solutions. For solving the TSP component, the 2-OPT segment reversing heuristic is often used for modifying the tour. We propose an extended and modified form of the reversing heuristic in order to concurrently consider both the TSP and KP components. Items deemed as less profitable and picked in cities earlier in the reversed segment are replaced by items that tend to be equally or more profitable and not picked in the later cities. Comparative evaluations on a broad range of benchmark TTP instances indicate that the proposed approach outperforms existing state-of-the-art TTP solvers

Sustainable seawater desalination: Current status, environmental implications and future expectations

International audienceDesalination is the process of making the saltwater of the Earth's oceans drinkable and could be a solution to droughts, especially in warmer and drier regions. However, the concerns of high cost and ecosystem degradation have always restricted the growth of the desalination industry and necessitated further studies and corrective actions. As desalination is becoming essential for our planet, the development of sustainable and energy-efficient technologies to produce clean water is a key research topic. Considering the worth of seawater desalination to fulfill the needs of the Earth habitants, this article explores how this process can be made less problematic to use as a real solution, not just a temporary opportunity. Desalination methods will play a key role, so all the major options and their environmental footprints are discussed, considering the energy requirements in particular of each process. A brief but up-to-date summary of the current status and future trends of desalination technologies is provided. Available equipment and procedures that are being developed to make desalination a sustainable process are explored. Finally, based on a detailed review, we highlight the future trends and issues to make informed decisions pertaining to the future research and development projects of this sector