6,271 research outputs found
Topological kink states at a tilt boundary in gated multi-layer graphene
The search for new realization of topologically protected edge states is an
active area of research. We show that a tilt boundary in gated multi-layer
graphene supports topologically protected gapless kink states, associated with
quantum valley Hall insulator (QVH). We investigate such kink states from two
perspectives: the microscopic perspective of a tight-binding model and an
ab-initio calculation on bilayer, and the perspective of symmetry protected
topological (SPT) states for general multi-layer. We show that a AB-BA bilayer
tilt boundary supports gapless kink states that are undeterred by strain
concentrated at the boundary. Further, we establish the kink states as concrete
examples of edge states of {\it time-reversal symmetric} -type
SPT, protected by no valley mixing, electron number conservation, and time
reversal symmetries. This allows us to discuss possible phase transitions
upon symmetry changes from the SPT perspective. Recent experimental
observations of a network of such tilt boundaries suggest that transport
through these novel topological kink states might explain the long standing
puzzle of sub-gap conductance. Further, recent observation of gap closing and
re-opening in gated bi-layer might be the first example of a transition between
two distinct SPT's: QVH and LAF.Comment: Improved a discussion of the structural aspects of the tilt boundary.
Included a discussion of boundary condition dependence. Added new section on
connection to experiment
Histamine increases neuronal excitability and sensitivity of the lateral vestibular nucleus and promotes motor behaviors via HCN channel coupled to H2 receptor
published_or_final_versio
Structural phase transition in IrTe: A combined study of optical spectroscopy and band structure calculations
IrPtTe is an interesting system showing competing phenomenon
between structural instability and superconductivity. Due to the large atomic
numbers of Ir and Te, the spin-orbital coupling is expected to be strong in the
system which may lead to nonconventional superconductivity. We grew single
crystal samples of this system and investigated their electronic properties. In
particular, we performed optical spectroscopic measurements, in combination
with density function calculations, on the undoped compound IrTe in an
effort to elucidate the origin of the structural phase transition at 280 K. The
measurement revealed a dramatic reconstruction of band structure and a
significant reduction of conducting carriers below the phase transition. We
elaborate that the transition is not driven by the density wave type
instability but caused by the crystal field effect which further
splits/separates the energy levels of Te (p, p) and Te p bands.Comment: 16 pages, 5 figure
A school-based comprehensive lifestyle intervention among Chinese kids against Obesity (CLICK-Obesity) in Nanjing City, China: The baseline data
Background: urgent development of effective interventions to prevent rapidly rising childhood obesity in China is needed. Methods: Between May 2010 and December 2013, a cluster randomized controlled trial was conducted among 4 graders in eight urban primary schools randomly assigned to intervention or control groups in Nanjing, China. A multi-component intervention program was implemented within the treatment group, while students in the control group followed their usual health education curriculum without additional intervention. Results: At baseline, 638 and 544 students were enrolled in the intervention and control group, respectively. The prevalence of excess body weight was 26.8%, with 27.4% in the intervention group and 26.1% in the control group (p=0.61). The mean (SD) BMI and WC was 18.7 (3.0) and 63.0 (9.2) for participants in intervention schools, and 18.5 (2.9) and 63.6 (8.7) for students in control group, separately (p=0.24 and 0.41, respectively). Compared to those who were not aware of what lifestyle/behavior factors were unhealthy, students who were aware of the unhealthy lifestyle/ behavior factors consumed fewer fried snacks (0.46±0.76 serves/week vs 0.65±0.91 serves/week;
Natural killer cells attenuate cytomegalovirus-induced hearing loss in mice
<div><p>Congenital cytomegalovirus (CMV) infection is the most common non-hereditary cause of sensorineural hearing loss (SNHL) yet the mechanisms of hearing loss remain obscure. Natural Killer (NK) cells play a critical role in regulating murine CMV infection via NK cell recognition of the Ly49H cell surface receptor of the viral-encoded m157 ligand expressed at the infected cell surface. This Ly49H NK receptor/m157 ligand interaction has been found to mediate host resistance to CMV in the spleen, and lung, but is much less effective in the liver, so it is not known if this interaction is important in the context of SNHL. Using a murine model for CMV-induced labyrinthitis, we have demonstrated that the Ly49H/m157 interaction mediates host resistance in the temporal bone. BALB/c mice, which lack functional Ly49H, inoculated with mCMV at post-natal day 3 developed profound hearing loss and significant outer hair cell loss by 28 days of life. In contrast, C57BL/6 mice, competent for the Ly49H/m157 interaction, had minimal hearing loss and attenuated outer hair cell loss with the same mCMV dose. Administration of Ly49H blocking antibody or inoculation with a mCMV viral strain deleted for the m157 gene rendered the previously resistant C57BL/6 mouse strain susceptible to hearing loss to a similar extent as the BALB/c mouse strain indicating a direct role of the Ly49H/m157 interaction in mCMV-dependent hearing loss. Additionally, NK cell recruitment to sites of infection was evident in the temporal bone of inoculated susceptible mouse strains. These results demonstrate participation of NK cells in protection from CMV-induced labyrinthitis and SNHL in mice.</p></div
A Novel SALL4/OCT4 Transcriptional Feedback Network for Pluripotency of Embryonic Stem Cells
Background: SALL4 is a member of the SALL gene family that encodes a group of putative developmental transcription factors. Murine Sall4 plays a critical role in maintaining embryonic stem cell (ES cell) pluripotency and self-renewal. We have shown that Sall4 activates Oct4 and is a master regulator in murine ES cells. Other SALL gene members, especially Sall1 and Sall3 are expressed in both murine and human ES cells, and deletions of these two genes in mice lead to perinatal death due to developmental defects. To date, little is known about the molecular mechanisms controlling the regulation of expressions of SALL4 or other SALL gene family members. Methodology/Principal Findings: This report describes a novel SALL4/OCT4 regulator feedback loop in ES cells in balancing the proper expression dosage of SALL4 and OCT4 for the maintenance of ESC stem cell properties. While we have observed that a positive feedback relationship is present between SALL4 and OCT4, the strong self-repression of SALL4 seems to be the “break” for this loop. In addition, we have shown that SALL4 can repress the promoters of other SALL family members, such as SALL1 and SALL3, which competes with the activation of these two genes by OCT4. Conclusions/Significance: Our findings, when taken together, indicate that SALL4 is a master regulator that controls its own expression and the expression of OCT4. SALL4 and OCT4 work antagonistically to balance the expressions of other SALL gene family members. This novel SALL4/OCT4 transcription regulation feedback loop should provide more insight into the mechanism of governing the “stemness” of ES cells
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Optimum design of reinforced concrete retaining walls with the flower pollination algorithm
The flower pollination algorithm (FPA) is anefficient metaheuristicoptimizationalgorithm mimickingthe pollinationprocessof flowering species. In this study, FPA is applied, for first time, to the optimum design of reinforced concrete (RC) cantilever retaining walls. It is foundthat FPA offers important savings with respect to conventional design approachesand that it outperformsgenetic algorithm (GA)andthe particle swarm optimization (PSO) algorithm in this designproblem.Furthermore, parameter tuning reveals that the best FPA performance is achieved for switch probability values ranging between 0.4 and 0.7, a population size of 20 individualsand aLévy flightstep sizescale factor of 0.5. Finally, parametric optimum designs show that theoptimumcost of RC retaining walls increases rapidly with the wallheight and smoothly with the magnitude of surcharge loadin
Set optimization - a rather short introduction
Recent developments in set optimization are surveyed and extended including
various set relations as well as fundamental constructions of a convex analysis
for set- and vector-valued functions, and duality for set optimization
problems. Extensive sections with bibliographical comments summarize the state
of the art. Applications to vector optimization and financial risk measures are
discussed along with algorithmic approaches to set optimization problems
Increased Glutathione Synthesis Following Nrf2 Activation by Vanadyl Sulfate in Human Chang Liver Cells
Jeju ground water, containing vanadium compounds, was shown to increase glutathione (GSH) levels as determined by a colorimetric assay and confocal microscopy. To investigate whether the effects of Jeju ground water on GSH were specifically mediated by vanadium compounds, human Chang liver cells were incubated for 10 passages in media containing deionized distilled water (DDW), Jeju ground water (S1 and S3), and vanadyl sulfate (VOSO4). Vanadyl sulfate scavenged superoxide anion, hydroxyl radical and intracellular reactive oxygen species. Vanadyl sulfate effectively increased cellular GSH level and up-regulated mRNA and protein expression of a catalytic subunit of glutamate cysteine ligase (GCLC), which is involved in GSH synthesis. The induction of GCLC expression by vanadyl sulfate was found to be mediated by transcription factor erythroid transcription factor NF-E2 (Nrf2), which critically regulates GCLC by binding to the antioxidant response elements (AREs). Vanadyl sulfate treatment increased the nuclear translocation of Nrf2 and the accumulation of phosphorylated Nrf2. Extracellular regulated kinase (ERK) contributed to ARE-driven GCLC expression via Nrf2 activation. Vanadyl sulfate induced the expression of the active phospho form of ERK. Taken together, these results suggest that the increase in GSH level by Jeju ground water is, at least in part, due to the effects of vanadyl sulfate via the Nrf2-mediated induction of GCLC
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