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"Diffusion"
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Adventure diffusion : from meandering molecules to the spreading of plants, humans, and ideas
This easy-to read book looks at the many ways in which diffusion bears on processes that involve dispersion, starting from the Brownian motion of molecules, covering the invasion of exotic plants, migration of populations, epidemics, and extending to the spreading of languages and ideas. Recently, there has been a growing interest in understanding migrations, diffusion and spreading outside the \"hard\" natural sciences of physics and chemistry, for example the spreading of plants introduced as a result of globalization. Another fascinating story is that of human migration in the distant past, i.e. the immigration of our ancestors who brought agriculture from the Near East, or the fast spread of the Palaeo-Indians into the Americas after the end of the Ice Age. Likewise, the spread of languages in the past, and even more so the current spread and retreat of languages will be described here in terms of diffusion. By understanding these principles, there is hope that some of the less common languages that are threatened by globalization can be saved. Another important implication discussed by the author concerns the outbreak of epidemics; these may be mitigated if we understand their spreading mechanism. Last but not least the spreading of ideas and innovations, a process which changes the world sometimes faster than we wish, can also be usefully described in this picture.
Book
The characteristics of knowledge diffusion of library and information science – from the perspective of citation
PurposeThis paper aims to explore the characteristics of knowledge diffusion of library and information science to reveal its development trend and influence on other disciplines.Design/methodology/approachBased on the ESI discipline classification, this paper measures the knowledge diffusion from the library and information science to other disciplines over the last 24 years using indicators in four dimensions: breadth, intensity, speed and theme of knowledge diffusion.FindingsThe results show that the knowledge diffusion breadth of library and information science is wide, spreading to 21 ESI disciplines; the knowledge spread mainly concentrates in four soft or applied disciplines, and yet partially inter-disciplinary, and the knowledge diffusion intensity to each ESI discipline is parabolic whose highest point is mostly in 2004–2005; the speed of spreading to the 21 ESI disciplines is faster and faster, and the articles at the highest speed of knowledge diffusion are basically published after 2005; the knowledge diffusion themes are becoming increasingly diverse, deepening and specialization over time.Originality/valueThis paper modifies the relevant indicators of knowledge diffusion and constructs a measurement framework of knowledge diffusion from four aspects: breadth, intensity, speed and theme. The research method can also be used to explore the characteristics of knowledge absorption of a discipline from other ones.
Journal Article
Anatomical accuracy of brain connections derived from diffusion MRI tractography is inherently limited
Significance Diffusion-weighted MRI (DWI) tractography is widely used to map structural connections of the human brain in vivo and has been adopted by large-scale initiatives such as the human connectome project. Our results indicate that, even with high-quality data, DWI tractography alone is unlikely to provide an anatomically accurate map of the brain connectome. It is crucial to complement tractography results with a combination of histological or neurophysiological methods to map structural connectivity accurately. Our findings, however, do not diminish the importance of diffusion MRI as a noninvasive tool that offers important quantitative measures related to brain tissue microstructure and white matter architecture.
Tractography based on diffusion-weighted MRI (DWI) is widely used for mapping the structural connections of the human brain. Its accuracy is known to be limited by technical factors affecting in vivo data acquisition, such as noise, artifacts, and data undersampling resulting from scan time constraints. It generally is assumed that improvements in data quality and implementation of sophisticated tractography methods will lead to increasingly accurate maps of human anatomical connections. However, assessing the anatomical accuracy of DWI tractography is difficult because of the lack of independent knowledge of the true anatomical connections in humans. Here we investigate the future prospects of DWI-based connectional imaging by applying advanced tractography methods to an ex vivo DWI dataset of the macaque brain. The results of different tractography methods were compared with maps of known axonal projections from previous tracer studies in the macaque. Despite the exceptional quality of the DWI data, none of the methods demonstrated high anatomical accuracy. The methods that showed the highest sensitivity showed the lowest specificity, and vice versa. Additionally, anatomical accuracy was highly dependent upon parameters of the tractography algorithm, with different optimal values for mapping different pathways. These results suggest that there is an inherent limitation in determining long-range anatomical projections based on voxel-averaged estimates of local fiber orientation obtained from DWI data that is unlikely to be overcome by improvements in data acquisition and analysis alone.
Journal Article
Three ancient colonies : Caribbean themes and variations
Mintz seeks to conjoin his knowledge of the history of Jamaica, Haiti, and Puerto Rico. 50 years later, the eminent scholar of the Caribbean returns to those experiences to meditate on the societies and on the island people who befriended him.
Book
Species mass transfer governs the selectivity of gas diffusion electrodes toward H2O2 electrosynthesis
The meticulous design of advanced electrocatalysts and their integration into gas diffusion electrode (GDE) architectures is emerging as a prominent research paradigm in the H
2
O
2
electrosynthesis community. However, it remains perplexing that electrocatalysts and assembled GDE frequently exhibit substantial discrepancies in H
2
O
2
selectivity during bulk electrolysis. Here, we elucidate the pivotal role of mass transfer behavior of key species (including reactants and products) beyond the intrinsic properties of the electrocatalyst in dictating electrode-scale H
2
O
2
selectivity. This tendency becomes more pronounced in high reaction rate (current density) regimes where transport limitations are intensified. By utilizing diffusion-related parameters (DRP) of GDEs (i.e., wettability and catalyst layer thickness) as probe factors, we employ both short- and long-term electrolysis in conjunction with in-situ electrochemical reflection-absorption imaging and theoretical calculations to thoroughly investigate the impact of DRP and DRP-controlled local microenvironments on O
2
and H
2
O
2
mass transfer. The mechanistic origins of diffusion-dependent conversion selectivity at the electrode scale are unveiled accordingly. The fundamental insights gained from this study underscore the necessity of architectural innovations for mainstream hydrophobic GDEs that can synchronously optimize mass transfer of reactants and products, paving the way for next-generation GDEs in gas-consuming electroreduction scenarios.
Electrocatalysts and assembled gas diffusion electrodes frequently exhibit discrepancies in selectivity during H
2
O
2
electrosynthesis. Here, the authors report the pivotal role of key species transport beyond the intrinsic properties of electrocatalysts in dictating electrode-scale H
2
O
2
selectivity.
Journal Article
The world made meme : public conversations and participatory media
Internet memes - digital snippets that can make a joke, make a point, or make a connection - are now a lingua franca of online life. They are collectively created, circulated, and transformed by countless users across vast networks. Most of us have seen the cat playing the piano, Kanye interrupting, Kanye interrupting the cat playing the piano. In 'The World Made Meme', Ryan Milner argues that memes, and the memetic process, are shaping public conversation. It's hard to imagine a major pop cultural or political moment that doesn't generate a constellation of memetic texts.
Book
Highly efficient electrosynthesis of hydrogen peroxide on a superhydrophobic three-phase interface by natural air diffusion
Hydrogen peroxide (H
2
O
2
) synthesis by electrochemical oxygen reduction reaction has attracted great attention as a green substitute for anthraquinone process. However, low oxygen utilization efficiency (<1%) and high energy consumption remain obstacles. Herein we propose a superhydrophobic natural air diffusion electrode (NADE) to greatly improve the oxygen diffusion coefficient at the cathode about 5.7 times as compared to the normal gas diffusion electrode (GDE) system. NADE allows the oxygen to be naturally diffused to the reaction interface, eliminating the need to pump oxygen/air to overcome the resistance of the gas diffusion layer, resulting in fast H
2
O
2
production (101.67 mg h
-1
cm
-2
) with a high oxygen utilization efficiency (44.5%–64.9%). Long-term operation stability of NADE and its high current efficiency under high current density indicate great potential to replace normal GDE for H
2
O
2
electrosynthesis and environmental remediation on an industrial scale.
H
2
O
2
electrosynthesis has garnered great attention as a green alternative to the anthraquinone process. Here the authors propose a cost-effective cathode to greatly improve the O
2
diffusion coefficient, resulting in a high H
2
O
2
production without the need for aeration.
Journal Article
Asymptotic Spreading for General Heterogeneous Fisher-KPP Type Equations
In this monograph, we review the theory and establish new and general results regarding spreading properties for heterogeneous
reaction-diffusion equations:
The characterizations of these sets involve two new notions of generalized principal eigenvalues
for linear parabolic operators in unbounded domains. In particular, it allows us to show that
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