On the Nature of Vigilance.

OBJECTIVE: I explore the origins, theoretical underpinnings, applications, and importance of vigilance in a world ever more dominated by semiautomated, automated, and autonomous machines. BACKGROUND: The empirical genesis of vigilance is taken as a case study in the etiology of the application of the behavioral sciences to the human culture of technology. The subsequent taxonomic ordering and theoretical clarification of its causal antecedents are set in the overall context of contemporary human-machine systems research. METHOD: The methods exercised in this work are historical analysis and informational synthesis in combination with projected theoretical implications and impact. RESULTS: The profile of evolution of the concept of vigilance is clarified and cast in the light of critical events, such as the promulgation of the vigilance taxonomy, its linkage to attentional resource theory, and the recognition that the attendant performance decrement is as indicative of iatrogenic sources as it is a shortfall or limitation of the observer's processing capacity. CONCLUSION: Vigilance is alive and growing in importance. Understanding sustained attention will become ever more critical in the humanization of automation-dominated systems. APPLICATION: The application of vigilance is widespread and potentially ubiquitous for semiautomated, automated, and autonomous system interaction.

Theoretical foundation for designing multilayer Halbach array magnets for benchtop NMR and MRI.

Multilayer Halbach array magnets support portable NMR and MRI, but optimizing their design to maximize performance and minimize the use of expensive magnet materials is challenging. This is partly because our theoretical understanding of such arrays is incomplete and computationally intensive. Here we provide a theoretical description of the magnetic field distribution and we demonstrate that inhomogeneity is greatest along the z axis in multilayer Halbach array magnets. This allows the configuration of the multilayer Halbach array magnets to be optimized in a way that takes into account homogeneity, magnet volume, and magnetic flux density. At the same time, our description simplifies the design of multilayer array magnets, while accommodating the possibility of different outer radii, lengths for each layer array, or the presence of separation between the rings. We validated the theoretical description in simulations of a three-layer Halbach array magnet, then with a prototype three-layer 1-T Halbach array magnet. After adjusting the position of magnet blocks in the neighboring rings, we achieved homogeneity of 220 ppm for a standard 5 mm NMR tube while the inner diameter of the magnet is 20 mm. Our work provides a theoretical foundation for designing multilayer Halbach array magnets to maximize homogeneity and minimize the use of magnet materials.

Thinking on large-scale terrestrial ecosystem management and its theoretical fundament and practice.

Ecosystem management at large scales is one of the core solutions to solve current global challenges of environmental and resources problem, mitigate climate change, govern ecosystems and environments regionally and achieve sustainable development. It is also a hotspot in the research and practice of conservation of global natural resources and ecosystems. Based on recalling and synthesizing of several large international actions on ecosystem management in the past two decades, this article rethought the concept of ecosystem management and its application from the perspective of discipline development of ecosystem management, theoretical fundaments and practices. The content included three parts: firstly, we reviewed the development of the scientific concept and practice of ecosystem management, discussed the connotations of the concept and redefined it, and summarized the practice of ecosystem management and its contribution to the development of the discipline. Secondly, we clarified the scientific and technological mission and basic tasks of ecosystem management, organized the discipline system of ecosystem management and its main research fields, summarized fundamental theories and the knowledge system of the science of ecosystem management, and clarified critical steps of ecosystem management actions, basic elements of management plans and management approaches. Finally, we proposed new trends of scientific research and the discipline development of ecosystem management, discussed the important spatial scales and its objects system of the scientific research on ecosystem management, proposed the cutting-edge scientific questions of global ecosystem management, integrative ecology thought and macro ecosystem approach. This review aimed at providing references for the scientific research and discipline deve-lopment of ecosystem management in China.

From 2SFCA to i2SFCA: integration, derivation and validation.

Uneven distributions of population and service providers lead to geographic disparity in access for residents and varying workload for staff in facilities. The former can be captured by spatial accessibility in the traditional two-step floating catchment area (2SFCA) method; and the latter can be measured by potential crowdedness in the newly developed inverted 2SFCA (or i2SFCA) method. Residents-based accessibility and facility crowdedness are two sides of the same coin in examining the geographic variability of resource allocation. This short research note derives the formulations of both methods to solidify their theoretical foundation, and uses a case study to validate both. By doing so, the 2SFCA and i2SFCA are fully integrated into one conceptual framework, derived with extensions to the Huff model, and validated by empirical data.