Human whole-brain functional connectivity networks have been shown to exhibit both local/quasilocal (e.g., a set of functional sub-circuits induced by node or edge attributes) and non-local (e.g., higher-order functional coordination patterns) properties. Nonetheless, the non-local properties of topological strata induced by local/quasilocal functional sub-circuits have yet to be addressed. To that end, we proposed a homological formalism that enables the quantification of higher-order characteristics of human brain functional sub-circuits. Our results indicate that each homological order uniquely unravels diverse, complementary properties of human brain functional sub-circuits. Noticeably, the H1 homological distance between rest and motor task was observed at both the whole-brain and sub-circuit consolidated levels, which suggested the self-similarity property of human brain functional connectivity unraveled by a homological kernel. Furthermore, at the whole-brain level, the rest–task differentiation was found to be most prominent between rest and different tasks at different homological orders: (i) Emotion task (H0), (ii) Motor task (H1), and (iii) Working memory task (H2). At the functional sub-circuit level, the rest–task functional dichotomy of the default mode network is found to be mostly prominent at the first and second homological scaffolds. Also at such scale, we found that the limbic network plays a significant role in homological reconfiguration across both the task and subject domains, which paves the way for subsequent investigations on the complex neuro-physiological role of such network. From a wider perspective, our formalism can be applied, beyond brain connectomics, to study the non-localized coordination patterns of localized structures stretching across complex network fibers.
The best way to stop the introduction of non-indigenous species (NISs) is by preventing their transport. In the case of ship hulls, this may be accomplished by managing entrainment onto the hull. This study was designed to examine the role of hull husbandry, i.e., cleaning and grooming, in fouling community structure and to determine the effect of husbandry on the recolonization of surfaces after a transplant was performed. A series of panels were placed at two locations along the east coast of Florida (Port Canaveral and Sebastian Inlet) that are typified by distinct fouling communities. Panels were subjected to one of three treatments: groomed weekly, cleaned every two months, or freely fouling. After four months, all panels were cleaned and transplanted between sites; no further husbandry was performed. Fouling community composition and coverage was characterized at monthly intervals both before and after transplantation. Hull husbandry was found to affect coverage and composition, with groomed panels carrying a lower cover of macrofouling in general. The effect of the original location on subsequent fouling composition and recolonization by specific organisms was confirmed for encrusting bryozoans, barnacles, sponges, and tunicates. Hull husbandry also affected subsequent fouling with specific preferences shown for surfaces that had been groomed, cleaned and undisturbed.
ABSTRACT In Fall 2020, political science instructors at the Massachusetts Institute of Technology (MIT) and the Naval Postgraduate School (NPS) partnered to conduct a virtual-learning wargame centered on Taiwan. This article presents its design and execution along with the results from pre- and post-game surveys and interviews with the participants that were conducted to measure the achievement of its learning objectives. The game conduct and empirical results demonstrate two main findings. First, wargames are effective tools of active learning that aid in classroom instruction and grab the attention of students—even over Zoom—in a way that traditional methods of instruction do not. Second, wargames can bridge gaps between different fields. The MIT–NPS wargame tackled the civil–military divide by bringing together military officers at NPS and academics from MIT. These results show that wargaming holds promise as a bridge-building tool of instruction that can engage students, scholars, and practitioners in achieving positive learning outcomes.
Randall C. O’Reilly, Charan Ranganath, Jacob L. Russin
A hallmark of human intelligence is the ability to adapt to new situations by applying learned rules to new content (systematicity) and thereby enabling an open-ended number of inferences and actions (generativity). Here, we propose that the human brain accomplishes these feats through pathways in the parietal cortex that encode the abstract structure of space, events, and tasks and pathways in the temporal cortex that encode information about specific people, places, and things (content). Recent neural network models show how the separation of structure and content might emerge through a combination of architectural biases and learning, and these networks show dramatic improvements over previous models in the ability to capture systematic, generative behavior. We close by considering how the hippocampal formation may form integrative memories that enable rapid learning of new structure and content representations.
Abstract The process of water entry is a complex and attractive field of research, since from more than a century ago there are wide applications in industry, nature science, bionics, and naval technology. The objective of this work is to investigate the cavity dynamics during water entry of a spinning sphere by numerical simulations. The algorithm of these simulations uses the Boundary Data Immersion Method (BDIM) to model the solid/fluid interactions, and the interface between the liquid and the gas is tracked by the volume-of-fluid (VOF) method. The uniform Cartesian-grid is used, and the effect of surface wettability is considered. The governing meta-equations for the full domain ensure the stable and accurate prediction on the pressure value on the solid boundary. Numerical results are validated with experiments, and good agreement between numerical and experimental results has been obtained for the transient cavity formation and the motion of the sphere. To further investigate the influence of the spin rate on the splash and cavity evolution and hydrodynamic characteristics, five different spin rates with a constant impact velocity are considered. Results reveal that the spin rate has significant influence on the cavity and splash asymmetry as well as the moment of pinch-off, while the depth of pinch-off is almost constant. The vortex structures show that both effects of rotation and shear play a role on the evolution of splash and cavity. The hydrodynamic forces fluctuate dramatically both at the moment of impact and the pinch off of the cavity. They gradually tend to be constant as the sphere descent with an open cavity.
AbstractIn practice, managers often face a trade‐off of choosing between committed and contingent pricing under cost uncertainty because contingent pricing may increase the firm's profit but may decrease consumer surplus and market share. This article compares the two pricing strategies under cost uncertainty in terms of the firm's profit, consumer surplus, and market share. We find conditions under which committed pricing would lead to higher consumer surplus and market share than contingent pricing and conditions under vice versa. The results highlight the properties of consumers' valuation distribution in the trade‐offs of choosing between committed and contingent pricing, specifically the properties of the so‐called Mills' ratio which is defined as the reciprocal of hazard rate. According to the curvature of Mills' ratio, we define three types of distributions. We then categorize some commonly used continuous distributions into the three types which lead to different preferences in the trade‐offs. Finally, we fit two sets of household income data from China and the United States into income distributions as the proxies of consumers' valuation distributions in an economy to illustrate those trade‐offs embedded in the two pricing strategies.
Angela Minichiello, David Armijo, Sarbajit Mukherjee
et al.
A robust and intuitive understanding of fluid mechanics—the applied science of fluid motion—is foundational within many engineering disciplines, including aerospace, chemical, civil, mechanical, naval, and ocean engineering. In‐depth knowledge of fluid mechanics is critical to safe and economical design of engineering applications employed globally everyday, such as automobiles, aircraft, and sea craft, and to meeting global 21st century engineering challenges, such as developing renewable energy sources, providing access to clean water, managing the environmental nitrogen cycle, and improving urban infrastructure. Despite the fundamental nature of fluid mechanics within the broader undergraduate engineering curriculum, students often characterize courses in fluid mechanics as mathematically onerous, conceptually difficult, and aesthetically uninteresting; anecdotally, undergraduates may choose to opt‐out of fluids engineering‐related careers based on their early experiences in fluids courses. Therefore, the continued development of new frameworks for engineering instruction in fluid mechanics is needed. Toward that end, this paper introduces mobile instructional particle image velocimetry (mI‐PIV), a low‐cost, open‐source, mobile application‐based educational tool under development for smartphones and tablets running Android. The mobile application provides learners with both technological capability and guided instruction that enables them to visualize and experiment with authentic flow fields in real time. The mI‐PIV tool is designed to generate interest in and intuition about fluid flow and to improve understanding of mathematical concepts as they relate to fluid mechanics by providing opportunities for fluids‐related active engagement and discovery in both formal and informal learning contexts.
M. Cummings, C. Mastracchio, Kristopher M. Thornburg
et al.
This work was supported by Aurora Flight Sciences under the ONR Science of Autonomy program as well as the Office of Naval Research (ONR) under Code 34 and MURI [grant number N00014-08-C-070].
Contents: Preface Cnut's geld and the size of Danish ships The naval service of the Cinque ports The development of broadside gunnery, 1450a "1650 The new Atlantic: naval warfare in the 16th century The military revolution at sea Queen Elizabeth and the myth of sea-power in English history The victualling of the British Navy during the Seven Years War Medicine, administration and society in the 18th-century Royal Navy Mobilizing seapower in the 18th century The naval chaplain in the 18th century Medicine and science in the British Navy of the 18th century Weather, geography and naval power in the age of sail Form and function in European navies, 1660a "1815 Navies and the Enlightenment Commissioned officers' careers in the Royal Navy, 1690a "1815 Mutiny or subversion? Spithead and the Nore Training or education: a naval dilemma over three centuries Index.