University of Abou Bekr Belkaïd

European colonial policies and objectives pursued in the Maghrebi region, together with the impact of shared foundations and commonalities uniting the region's populations, prompted leading figures of the national movements to adopt the idea of strengthening the common Maghrebi struggle and activating it on the ground. They regarded this approach as the most effective means of liberation from the colonial grip and of restoring usurped national sovereignty in all its pillars and components. Given that Algeria was among the earliest victims of French colonial domination, it constituted an early arena of resistance to colonialism and a platform for the articulation of unifying ideas that viewed the Maghreb as a single entity confronting the same danger and sharing the same destiny. This was manifested in the positions and contributions of prominent figures within the national movement and the liberation revolution, who enriched and reinforced the trajectory of the Maghrebi unitary struggle.

This paper presents an improved fixed-time control strategy for path tracking of autonomous gun-launched coaxial-rotor micro aerial vehicles (MAVs) operating under unknown aerodynamic forces. The proposed algorithm combines a filtered fixed-time hierarchical backstepping (FTHB) method with a fixed-time disturbance observer (FDO). Using a coordinate transformation, the complex dynamics of the MAV are decoupled into fully actuated and underactuated subsystems. The novelty of this work lies in two key contributions: (1) the design of a fixed-time hierarchical backstepping controller for the nominal system, ensuring fixed-time stability, with fixed-time filters employed to estimate virtual control inputs and thereby reduce the complexity of the backstepping design, and (2) the integration of fixed-time observers to estimate unknown disturbances in fixed time, effectively addressing the challenges posed by aerodynamic uncertainties affecting the entire system. The effectiveness of this control strategy is rigorously demonstrated through fixed-time stability analyses. A comprehensive comparative assessment, covering both qualitative and quantitative evaluations, is carried out through extensive simulations comparing the proposed controller with a fixed-time controller, a finite-time controller, and a disturbance observer-based controller. This evaluation clearly underscores the robustness and superior performance of the proposed control strategy.

Collagen supplementation has garnered attention as a promising intervention to support healthy aging and longevity. The synthesis of collagen, the body’s primary structural protein, decreases by approximately 1% per year after age 25, contributing to an aging phenotype characterized by skin wrinkling, joint degeneration, and impaired tissue integrity. This mini-review critically evaluates the potential benefits of collagen supplementation, exploring its multifaceted mechanisms of action that extend beyond simply providing amino acids. Specifically, exogenous collagen peptides stimulate dermal fibroblasts, increasing the synthesis of elastin and fibrillin, key collagen types. Additionally, recent findings in model organisms highlight specific collagen genes as vital mediators of longevity, suggesting a regulatory role in cellular senescence and oxidative stress pathways prevalent in aging. This review aims to provide a comprehensive overview of the effects of collagen supplementation in the areas of skin, musculoskeletal, and metabolic health by synthesizing contemporary clinical evidence and mechanistic information. Furthermore, addressing safety concerns and research limitations, it questions whether collagen peptides, beyond their superficial benefits, can be proven as a legitimate component of longevity medicine to influence fundamental biological aging processes.