Chung-Ang University

About: Chung-Ang University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Population & Thin film. The organization has 13381 authors who have published 26978 publications receiving 416735 citations. The organization is also known as: CAU & Chung.

Generalized surface quasi-geostrophic equations with singular velocities

Abstract: This paper establishes several existence and uniqueness results for two families of active scalar equations with velocity fields determined by the scalars through very singular integrals. The first family is a generalized surface quasi-geostrophic (SQG) equation with the velocity field $u$ related to the scalar $\theta$ by $u= abla^\perp\Lambda^{\beta-2}\theta$, where $1 1$. We obtain the local existence and uniqueness of classical solutions, the global existence of weak solutions and the local existence of patch type solutions. The second family is a dissipative active scalar equation with $u= abla^\perp (\log(I-\Delta))^\mu\theta$ for $\mu>0$, which is at least logarithmically more singular than the velocity in the first family. We prove that this family with any fractional dissipation possesses a unique local smooth solution for any given smooth data. This result for the second family constitutes a first step towards resolving the global regularity issue recently proposed by K. Ohkitani \cite{Oh}.

Gravity-mediated (or composite) dark matter

Abstract: Dark matter could have an electroweak origin, yet it could communicate with the visible sector exclusively through gravitational interactions. In a setup addressing the hierarchy problem, we propose a new dark-matter scenario where gravitational mediators, arising from the compactification of extra dimensions, are responsible for dark-matter interactions and its relic abundance in the Universe. We write an explicit example of this mechanism in warped extra dimensions and work out its constraints. We also develop a dual picture of the model, based on a four-dimensional scenario with partial compositeness. We show that gravity-mediated dark matter is equivalent to a mechanism of generating viable dark matter scenarios in a strongly coupled, near-conformal theory, such as in composite Higgs models.

Differential modulation of E. coli mRNA abundance by inhibitory proteins that alter the composition of the degradosome.

Abstract: In Escherichia coli the initial step in the processing or decay of many messenger and structural RNAs is mediated by the endonuclease RNase E, which forms the core of a large RNA-catalysis machine termed the degradosome. Previous experiments have identified a protein that globally modulates RNA abundance by binding to RNase E and regulating its endonucleolytic activity. Here we report the discovery of RraB, which interacts with a different site on RNase E and interferes with cleavage of a different set of transcripts. We show that expression of RraA or RraB in vivo is accompanied by dramatic, distinct, and inhibitor-specific changes in degradosome composition--and that these are in turn associated with alterations in RNA decay and global transcript abundance profiles that are dissimilar to the profile observed during simple RNase E deficiency. Our results reveal the existence of endonuclease binding proteins that modulate the remodelling of degradosome composition in bacteria and argue that such degradosome remodelling is a mechanism for the differential regulation of RNA cleavages in E. coli.

Calcineurin B-Like Protein-Interacting Protein Kinase CIPK21 Regulates Osmotic and Salt Stress Responses in Arabidopsis

Abstract: The role of calcium-mediated signaling has been extensively studied in plant responses to abiotic stress signals. Calcineurin B-like proteins (CBLs) and CBL-interacting protein kinases (CIPKs) constitute a complex signaling network acting in diverse plant stress responses. Osmotic stress imposed by soil salinity and drought is a major abiotic stress that impedes plant growth and development and involves calcium-signaling processes. In this study, we report the functional analysis of CIPK21, an Arabidopsis (Arabidopsis thaliana) CBL-interacting protein kinase, ubiquitously expressed in plant tissues and up-regulated under multiple abiotic stress conditions. The growth of a loss-of-function mutant of CIPK21, cipk21, was hypersensitive to high salt and osmotic stress conditions. The calcium sensors CBL2 and CBL3 were found to physically interact with CIPK21 and target this kinase to the tonoplast. Moreover, preferential localization of CIPK21 to the tonoplast was detected under salt stress condition when coexpressed with CBL2 or CBL3. These findings suggest that CIPK21 mediates responses to salt stress condition in Arabidopsis, at least in part, by regulating ion and water homeostasis across the vacuolar membranes.