Antiferromagnetic and structural transitions in the superoxide KO2 from first principles: A 2p-electron system with spin-orbital-lattice coupling

KO2 exhibits concomitant antiferromagnetic (AFM) and structural transitions, both of which originate from the open-shell 2p electrons of O$_{2}^{-}$ molecules. The structural transition is accompanied by the coherent tilting of O$_{2}^{-}$ molecular axes. The interplay among the spin-orbital-lattice degrees of freedom in KO2 is investigated by employing the first-principles electronic structure theory and the kinetic-exchange interaction scheme. We have shown that the insulating nature of the high symmetry phase of KO2 at high temperature (T) arises from the combined effect of the spin-orbit coupling and the strong Coulomb correlation of O 2p electrons. In contrast, for the low symmetry phase of KO2 at low T with the tilted O$_{2}^{-}$ molecular axes, the band gap and the orbital ordering are driven by the combined effects of the crystal-field and the strong Coulomb correlation. We have verified that the emergence of the O 2p ferro-orbital ordering is essential to achieve the observed AFM structure for KO2

Correlated Electronic Structures and the Phase Diagram of Hydrocarbon-based Superconductors

We have investigated correlated electronic structures and the phase diagram of electron-doped hydrocarbon molecular solids, based on the dynamical mean-field theory. We have found that the ground state of hydrocarbon-based superconductors such as electron-doped picene and coronene is a multi-band Fermi liquid, while that of non-superconducting electron-doped pentacene is a single-band Fermi liquid in the proximity of the metal-insulator transition. The size of the molecular orbital energy level splitting plays a key role in producing the superconductivity of electron-doped hydrocarbon solids. The multi-band nature of hydrocarbon solids would boost the superconductivity through the enhanced density of states at the Fermi level.X11910sciescopu

Observation of a kink during the formation of the Kondo resonance band in a heavy-fermion system

We have shown that the kink behavior in the spectral function of a heavy fermion can appear during the formation of the Kondo resonance (KR) band and the hybridization gap. We have investigated the heavy fermion compound CeCoGe2, using a combined approach of the density functional theory and the dynamical mean field theory. Low temperature T spectral functions show dispersive KR states, similarly to the recent experimental observation. During the evolution from the non-f conduction band state at high T to the dispersive KR band state at low T, which have topologically different band shapes, we have found the existence of kinks in the non-f spectral function near the Fermi level E-F. The observation of kink is clearly in correspondence with the multiple temperature scales of the formation of the KR band.X1186sciescopu

Automated Image Classification for Post-Earthquake Reconnaissance Images

In the aftermath of earthquake events, many reconnaissanceteams are dispatched to collect as much data as possible, movingquickly to capture the damages and failures on our built environments before they are recovered. Unfortunately, only a tiny portionof these images are shared, curated, and utilized. There is a pressing need for a viable visual data organizing or categorizing tool witha minimal manual effort. In this study, we aim to build a system toautomate classifying and analyzing a large volume of post-disastervisual data. Our system called Automated Reconnaissance ImageOrganizer (ARIO) is a web-based tool to automatically categorizing reconnaissance images using a deep convolutional neural net-work and generate a summary report combined with useful metadata. Automated classifiers trained using our ground-truth visualdatabase classify images into various categories that are useful toreadily analyze and document reconnaissance images from post-disaster buildings in the field

Temperature-dependent Fermi surface evolution in heavy fermion CeIrIn5

In Cerium-based heavy electron materials, the 4f electron's magnetic moments bind to the itinerant quasiparticles to form composite heavy quasiparticles at low temperature. The volume of the Fermi surfacein the Brillouin zone incorporates the moments to produce a "large FS" due to the Luttinger theorem. When the 4f electrons are localized free moments, a "small FS" is induced since it contains only broad bands of conduction spd electrons. We have addressed theoretically the evolution of the heavy fermion FS as a function of temperature, using a first principles dynamical mean-field theory (DMFT) approach combined with density functional theory (DFT+DMFT). We focus on the archetypical heavy electrons in CeIrIn5, which is believed to be near a quantum critical point. Upon cooling, both the quantum oscillation frequencies and cyclotron masses show logarithmic scaling behavior (~ ln(T_0/T)) with different characteristic temperatures T_0 = 130 and 50 K, respectively. The resistivity coherence peak observed at T ~ 50 K is the result of the competition between the binding of incoherent 4f electrons to the spd conduction electrons at Fermi level and the formation of coherent 4f electrons.Comment: 5 pages main article,3 figures for the main article, 2 page Supplementary information, 2 figures for the Supplementary information. Supplementary movie 1 and 2 are provided on the webpage(http://www-ph.postech.ac.kr/~win/supple.html

Implications of MicroRNAs in the Vascular Homeostasis and Remodeling

Vascular remodeling or arterial remodeling is a process of adaptive alteration of vascular wall architecture and leads to the endothelial cell (EC) dysfunction and synthetic or contractile phenotypic change of VSMCs, and the infiltration of monocytes and Macrophages that promotes vascular diseases including atherosclerosis. Recent findings have demonstrated that microRNAs (miRNAs) are involved in regulating gene expression at posttranscriptional level and disease pathogenesis. A change of miRNA expression profiles plays key roles in the gene expressions and the regulation of cellular functions. In this chapter, we summarize the vascular remodeling-related miRNAs and their functions in vascular biology