Stagnation Detection with Randomized Local Search.

Recently a mechanism called stagnation detection was proposed that automatically adjusts the mutation rate of evolutionary algorithms when they encounter local optima. The so-called SD-(1+1) EA introduced by Rajabi and Witt (2022) adds stagnation detection to the classical (1+1) EA with standard bit mutation. This algorithm flips each bit independently with some mutation rate, and stagnation detection raises the rate when the algorithm is likely to have encountered a local optimum. In this article, we investigate stagnation detection in the context of the k-bit flip operator of randomized local search that flips k bits chosen uniformly at random and let stagnation detection adjust the parameter k. We obtain improved runtime results compared with the SD-(1+1) EA amounting to a speedup of at least (1-o(1))2πm, where m is the so-called gap size, that is, the distance to the next improvement. Moreover, we propose additional schemes that prevent infinite optimization times even if the algorithm misses a working choice of k due to unlucky events. Finally, we present an example where standard bit mutation still outperforms the k-bit flip operator with stagnation detection.

Superficial temporal artery aneurysm misdiagnosed in a patient with long-term migraine headache treatment: a case report.

BACKGROUND: Superficial temporal artery aneurysm is a rare vascular abnormality without specific clinical symptoms. In this case report, we present the case of a patient with superficial temporal artery aneurysm who was diagnosed with migraine headache at first. CASE PRESENTATION: A 60-year-old Iranian man with a previous history of headaches, who did not respond properly to the treatments following the initial diagnosis of migraine, presented with a painless lump in the left temporal region, and he was diagnosed with superficial temporal artery aneurysm via Doppler ultrasound. Finally, surgical removal of the left superficial temporal artery aneurysm was performed. CONCLUSIONS: This case shows the importance of vascular causes in the approach to headache etiologies, especially when the headache is prolonged without proper responses to treatment. Computed tomography angiography and magnetic resonance angiography are appropriate diagnostic methods for aneurysm detection that should be considered in future studies.

From the rhombic transposition flap toward Z-plasty: An optimized design using the finite element method.

In this paper, an optimized design for rhombic transposition flaps is created using a reliable finite element model that assures convergence for stress and deformation results. Defining a general configuration for rhombic flaps, the surgical process of wound closure is simulated for a wide variety of patterns. To address the intrinsic uncertainties associated with modelling skin's mechanical properties, four different sets of material parameters are considered, to investigate statistical measures. The results suggest that implementing the rhombic flap technique in a way similar to Z-plasty leads to an optimized surgical technique. The proposed flap, which can be employed for 60° to 90° rhombic defects, can reduce the maximum von Mises stress by 53% (on average) with respect to the Dufourmentel flap, and, in the case of a 60° defect, 43% with respect to the Limberg flap. To avoid any depressed area such as dog-ear formation, the maximum compressive principal stress is examined to assure that it remains within the limits of the stresses in the existing surgical techniques. The deformed configuration is also taken into consideration. Ease of implementation, in terms of both construction and orientation with respect to the relaxed skin tension lines, is another design feature offered by the proposed flap.