Distributed model reference adaptive containment control of heterogeneous multi-agent systems with unknown uncertainties and directed topologies

In this paper, the containment control problem of heterogeneous uncertain high-order linear Multi-Agent Systems (MASs) is addressed and solved via a novel fully-Distributed Model Reference Adaptive Control (DMRAC) approach, where each follower computes its adaptive control action on the basis of local measurements, information shared with neighbors (within the communication range) and the matching errors w.r.t. its own reference model, without requiring any previous knowledge of the global directed communication topology structure. The approach inherits the robustness of the direct model reference adaptive control (MRAC) scheme and allows all agents converging towards the convex hull spanned by leaders while fulfilling at the same time local additional performance requirements at single-agent level, such as prescribed settling time, overshoot, etc. The asymptotic stability of the whole closed-loop network is analytically derived by exploiting the Lyapunov theory and the Barbalat lemma, hence proving that each follower converges to the convex hull spanned by the leaders, as well as the boundedness of the adaptive gains. Extensive numerical analysis for heterogeneous MAS composed of stable, unstable and oscillating agent dynamics are presented to validate the theoretical framework and to confirm the effectiveness of the proposed approach.     

Identification of histological threshold concepts in health sciences curricula: Students' perception

Students' metacognitive skills and perceptions are considered important variables for high-quality learning. In this study, students' perceptions were used to identify histological threshold concepts (integrative, irreversible, transformative, and troublesome) in three health sciences curricula. A specific questionnaire was developed and validated to characterize students' perceptions of histological threshold concepts. A sample of 410 undergraduate students enrolled in the dentistry, medicine, and pharmacy degree programs participated in the study. Concepts assessed in the study were clustered to ten categories (factors) by exploratory and confirmatory factor analysis. Concepts linked to tissue organization and tissue functional states received the highest scores from students in all degree programs, suggesting that the process of learning histology requires the integration of both static concepts related to the constituent elements of tissues and dynamic concepts such as stem cells as a tissue renewal substrate, or the euplasic, proplasic and retroplasic states of tissues. The complexity of integrating static and dynamic concepts may pose a challenging barrier to the comprehension of histology. In addition, several differences were detected among the students in different degree programs. Dentistry students more often perceived morphostructural concepts as threshold concepts, whereas medical students highlighted concepts related to two-dimensional microscopic identification. Lastly, pharmacy students identified concepts related to tissue general activity as critical for the comprehension and learning of histology. The identification of threshold concepts through students' perceptions is potentially useful to improve the teaching and learning process in health sciences curricula.     

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Rhodesia and the Olympic Games: representations of masculinity,war and Empire, 1965–1980

White-settler-ruled Rhodesia faced isolation from international sporting competition after its unilateral declaration of independence in 1965, including from the Olympic Games. Sport reflected the qualities of white Rhodesian society, including its gendered and racialized norms. Rhodesia inherited its sporting ethic from Great Britain, and the British influence on Rhodesian sport remained indelible even as anti-British sentiment flared in the white community as Britain worked to exclude Rhodesia from international sport. This work highlights the irony that Rhodesia adhered to Imperial British social norms on the playing field while trying to assert an independent and anti-British national identity.     

The Libraries They Are A-Changin': How Libraries Reorganize

This article will report on the results of a study of library reorganizations in the literature. The authors identified five steps common to all library reorganizations, and this article describes those steps as well as two management change theories most mentioned in the literature—the eight-step process of change by John Kotter and Reframing Organizations by Lee G. Bolman and Terrence E. Deal. The article will draw conclusions formed by a comparison of these theoretical models to the practice and real-life experience of reorganizations as described by libraries in the literature.     

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