Topological insulators and metal-insulator transition in the pyrochlore iridates

The possible existence of topological insulators in cubic pyrochlore iridates A$_{2}$Ir$_{2}$O$_{7}$ (A = Y or rare-earth elements) is investigated by taking into account the strong spin-orbit coupling and trigonal crystal field effect. It is found that the trigonal crystal field effect, which is always present in real systems, may destabilize the topological insulator proposed for the ideal cubic crystal field, leading to a metallic ground state. Thus the trigonal crystal field is an important control parameter for the metal-insulator changeover. We propose that this could be one of the reasons why distinct low temperature ground states may arise for the pyrochlore iridates with different A-site ions. On the other hand, examining the electron-lattice coupling, we find that softening of the $\textbf{q}$=0 modes corresponding to trigonal or tetragonal distortions of the Ir pyrochlore lattice leads to the resurrection of the strong topological insulator. Thus, in principle, a finite temperature transition to a low-temperature topological insulator can occur via structural changes. We also suggest that the application of the external pressure along [111] or its equivalent directions would be the most efficient way of generating strong topological insulators in pyrochlore iridates.Comment: 10 pages, 11 figures, 2 table

On SS-Noetherian modules and SS-strong Mori modules

In this paper, we study some properties of $S$-Noetherian modules and $S$-strong Mori modules. Among other things, we prove the Hilbert basis theorem for $S$-Noetherian modules and $S$-strong Mori modules.Comment: 15 page

The Effect of Appearance Information on Favorableness Perception - The Role of Contingencies of Self-Worth and Self-Relevance

As online social networks evolve, people have more chances to encounter others’ profiles. According to Mussweiler et al. (2006), people tend to associate themselves with others’ profile information when encountering it. A situation in that an individual comes across others’ profiles becomes a social comparison (Festinger, 1954), and the information becomes a reference point for the comparison. As a receiver of the information, this study focuses on comparison process happened and investigates the mechanism of how people evaluate others’ appearance information in online social networks

Emerging roles of desumoylating enzymes

AbstractPosttranslational modification by small ubiquitin-like modifier (SUMO) controls diverse cellular processes including transcriptional regulation, nuclear transport, cell-cycle progression, DNA repair, and signal transduction pathway. Sumoylation is a highly dynamic process that is reversed by a family of Sentrin/SUMO-specific proteases (SENPs). Thus, desumoylation process must be important for regulation of the fate and function of SUMO-conjugated proteins as well as SUMOylation process. SENPs catalyze the removal of SUMO from SUMO-conjugated target proteins as well as the cleavage of SUMO from its precursor proteins. Since the first report of yeast desumoylating enzymes, many studies have revealed the structural and cellular biological properties of SENP family. This review focuses on the specificity of the SENPs' catalytic activities with regard to SUMO isoforms and their emerging roles as cellular regulators

11B^{11}B NMR and Relaxation in MgB2MgB_2 Superconductor

$^{11}B$ NMR and nuclear spin-lattice relaxation rate (NSLR) are reported at 7.2 Tesla and 1.4 Tesla in powder samples of the intermetallic compound $MgB_2$ with superconducting transition temperature in zero field $T_c$ = 39.2 K. From the first order quadrupole perturbed NMR specrum a quadrupole coupling frequency of 835 $\pm$ 5 kHz is obtained. The Knight shift is very small and it decreases to zero in the superconducting phase. The NSLR follows a linear law with $T_1T$ = 165 $\pm$ 10 (sec K) . The results in the normal phase indicate a negligible $s$-character of the wave function of the conduction electrons at the Fermi level. Below $T_c$ the NSLR is strongly field dependent indicating the presence of an important contribution related to the density and the thermal motion of flux lines. No coherence peak is observed at the lower field investigated (1.4 T)

Unmet Healthcare Needs of Children in Vulnerable Families in South Korea: Finding from the Community Child Center Child Panel Survey

Presented in this paper is a study that examined the status of unmet healthcare needs of children in vulnerable families and identified factors affecting such unmet needs. The Community Child Center (CCC) Child Panel Survey data in Korea were used. A multiple stepwise logistic regression analysis was performed to examine factors influencing unmet healthcare needs of children. Influencing factors comprised predisposing, enabling, and need factors based on the Andersen Behavioral Model of Health Services Utilization. A total of 340 sixth-graders from vulnerable families participated, and 96 (28.2%) children had unmet healthcare needs. Factors included absence of an after-school caregiver (OR = 1.95, 95% CI [1.16, 3.27]), perceived physical symptoms (OR = 1.33, 95% CI [1.02, 1.73]), parental indifference (OR = 1.33, 95% CI [1.002, 1.77]), duration of daily stay at CCCs (OR = 1.32, 95% CI [1.01, 1.71]), and satisfaction with CCC teachers (OR = 0.65, 95% CI [0.49, 0.85]). The relationship with parents and CCC teachers had the strongest influence on unmet healthcare needs of children. In order to reduce the unmet healthcare needs of children in vulnerable families, existing support structures should be expanded to offer financial and administrative support for children’s parents and CCC teachers

On SS-nn-absorbing ideals

Let $R$ be a commutative ring with identity, $S$ a multiplicative subset of $R$ and $I$ an ideal of $R$ disjoint from $S$. In this paper, we introduce the notion of an $S$-$n$-absorbing ideal which is a generalization of both the $S$-prime ideals and $n$-absorbing ideals. Moreover, we investigate the basic properties, quotient extension, existence and amalgamation of $S$-$n$-absorbing ideals.Comment: 18page