Bacterial chemotaxis without gradient-sensing

Models for chemotaxis are based on gradient sensing of individual organisms. The key contribution of Keller and Segel is showing that erratic movements of individuals may result in an accurate chemotaxis phenomenon as a group. In this paper we provide another option to understand chemotactic behavior when individuals do not sense the gradient of chemical concentration by any means. We show that, if individuals increase their motility to find food when they are hungry, an accurate chemotactic behavior may obtained without sensing the gradient. Such a random dispersal has been suggested by Cho and Kim and is called starvation driven diffusion. This model is surprisingly similar to the original derivation of Keller-Segel model. A comprehensive picture of traveling band and front solutions is provided with numerical simulations.Comment: 19 pages, 4 figure

Assembling Creative Cities in Seoul and Yokohama: Rebranding East Asian Urbanism

By investigating institutional and cultural practices as well as the consequences of the creative industry-led development policy in Yokohama, Japan and Seoul, South Korea, this dissertation critically reexamines the key rationales of creative economy-driven urban development and considers social costs and tensions between the state, capital and citizens that are embedded within creative city policy discourses and practices. This dissertation intervenes in the conventional understandings, which consider the influx of neoliberalism as the key to explain the rapid global circulation of creative city policy, typically based on cities in the West. By considering the policy transfer as endless processes of “translation” from the viewpoint of Actor-Network Theory, rather than a linear replication process, it shows that specific institutional and cultural practices—such as the historical legacy of the East Asian developmental state and its relation to capital and civic society—are necessary not only for properly locating the meaning of neoliberalism but also for evaluating the complexity of neoliberal political projects in East Asia. By conceptualizing creative city policy as new urban governmental techniques , it argues that the creative cities of Japan and Korea are test sites not only for neoliberal creative economy but also for new forms of governing and being governed with significant implications for fostering certain types of subjectivities such as creative citizen and creative labor . Under this framework, ultimately this dissertation contributes to re-orient the current debates on the global creative city policy from a question of “How can we develop effective creative city policy?” implemented by urban planners, capitals and state officials to that of “How can we invent and share creative city politics?” raised by creative workers, activists and citizens

Double Greibach operator grammars

AbstractEvery context-free grammar can be transformed into one in double Greibach operator form, that satisfies both double Greibach form and operator form. Examination of the expressive power of various well-known subclasses of context-free grammars in double Greibach and/or operator form yields an extended hierarchy of language classes. Basic decision properties such as equivalence can be stated in stronger forms via new classes of languages in this hierarchy

On momentum conservation and thermionic emission cooling

The question of whether relaxing momentum conservation can increase the performance of thermionic cooling device is examined. Both homojunctions and heterojunctions are considered. It is shown that for many cases, a non-conserved lateral momentum model overestimates the current. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, non-conservation of lateral momentum may increase the current. These results may be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of conducting channels. These results also show that within thermionic emission framework, the possibilities of increasing thermionic cooling by relaxing momentum conservation are limited. More generally, however, when the connection to the source is weak or in the presence of scattering, the situation may be different. Issues that deserve further study are identified.Comment: 36 pages, 1 table, 9 figure

On the Best Bandstructure for Thermoelectric Performance

The conventional understanding that a bandstructure that produces a Dirac delta function transport distribution (or transmission in the Landauer framework) maximizes the thermoelectric figure of merit, ZT, is revisited. Thermoelectric (TE) performance is evaluated using a simple tight binding (TB) model for electron dispersion and three different scattering models: 1) a constant scattering time, 2) a constant mean-free-path, and 3) a scattering rate proportional to the density-of-states. We found that a Dirac delta-function transmission never produces the maximum ZT. The best bandstructure for maximizing ZT depends on the scattering physics. These results demonstrate that the selection of bandstructure to maximize TE performance is more complex than previously thought and that a high density-of-states near the band edge does not necessarily improve TE performance

Sport clusters and community resilience in the United States

How to enhance community resilience to natural disasters is a major question for researchers and policymakers. Although researchers agree that sport generates community benefits, few scholarly efforts in sport management have been invested in understanding the sport–resilience association. This paper attempted to address whether and how sport clusters—the clustering of sport industries—are associated with community resilience across locations. To achieve this, geographically weighted regression and visualization techniques were applied to macro-level data regarding community resilience and the clustering of 13 separate sport industries across 3,108 counties in the contiguous United States. The results indicate that, overall, the clustering of eight sport industries was significantly associated with community resilience and demonstrates the existence of spatially heterogeneous associations in magnitudes and signs of community resilience in sport clusters. The findings of this paper have the potential to help community sport scholars and policymakers implement location-specific resilience policies through sport industry development

Restructuring TCAD System: Teaching Traditional TCAD New Tricks

Traditional TCAD simulation has succeeded in predicting and optimizing the device performance; however, it still faces a massive challenge - a high computational cost. There have been many attempts to replace TCAD with deep learning, but it has not yet been completely replaced. This paper presents a novel algorithm restructuring the traditional TCAD system. The proposed algorithm predicts three-dimensional (3-D) TCAD simulation in real-time while capturing a variance, enables deep learning and TCAD to complement each other, and fully resolves convergence errors.Comment: In Proceedings of 2021 IEEE International Electron Devices Meeting (IEDM

Bouncing back: unpacking the influence of sport media on consumer resilience

This study aims to empirically investigate how sport media consumption influences the relationships among the spatially explicit risks of COVID-19, resilience, and positive and negative affect, considering social class. To achieve this, we employed an integrated approach using spatial and aspatial analyses. The findings indicated that the negative effects of the spatially explicit risks of COVID-19 on resilience are mitigated by sport media consumption. In turn, an increased level of resilience enhances positive affect and reduces negative affect. Moreover, consumers in the upper class showed a more pronounced resilience process through sport media consumption than those in the lower class. This study contributes to the knowledge regarding the sport−resilience association by identifying the moderating effect of sport media consumption within social classes and addressing the spatially explicit risks of COVID-19. The present findings provide a basis for sport-based resilience strategies in times of adversity

Quaternary structures of Vac8 differentially regulate the Cvt and PMN pathways.

Armadillo (ARM) repeat proteins constitute a large protein family with diverse and fundamental functions in all organisms, and armadillo repeat domains share high structural similarity. However, exactly how these structurally similar proteins can mediate diverse functions remains a long-standing question. Vac8 (vacuole related 8) is a multifunctional protein that plays pivotal roles in various autophagic pathways, including piecemeal microautophagy of the nucleus (PMN) and cytoplasm-to-vacuole targeting (Cvt) pathways in the budding yeast Saccharomyces cerevisiae. Vac8 comprises an H1 helix at the N terminus, followed by 12 armadillo repeats. Herein, we report the crystal structure of Vac8 bound to Atg13, a key component of autophagic machinery. The 70-angstrom extended loop of Atg13 binds to the ARM domain of Vac8 in an antiparallel manner. Structural, biochemical, and in vivo experiments demonstrated that the H1 helix of Vac8 intramolecularly associates with the first ARM and regulates its self-association, which is crucial for Cvt and PMN pathways. The structure of H1 helix-deleted Vac8 complexed with Atg13 reveals that Vac8[Delta 19-33]-Atg13 forms a heterotetramer and adopts an extended superhelical structure exclusively employed in the Cvt pathway. Most importantly, comparison of Vac8-Nvj1 and Vac8-Atg13 provides a molecular understanding of how a single ARM domain protein adopts different quaternary structures depending on its associated proteins to differentially regulate 2 closely related but distinct cellular pathways