Holographic RG flows with nematic IR phases

We construct zero-temperature geometries that interpolate between a Lifshitz fixed point in the UV and an IR phase that breaks spatial rotations but preserves translations. We work with a simple holographic model describing two massive gauge fields coupled to gravity and a neutral scalar. Our construction can be used to describe RG flows in non-relativistic, strongly coupled quantum systems with nematic order in the IR. In particular, when the dynamical critical exponent of the UV fixed point is z=2 and the IR scaling exponents are chosen appropriately, our model realizes holographically the scaling properties of the bosonic modes of the quadratic band crossing model.Comment: 19 pages, 2 figures. References added. Expanded discussion on nematic orde

Episodic memory reconsolidation and strengthening

Episodic memories are not always accurate, subject to false recollection due to the process of memory reconsolidation (Loftus, 2005). Memory reactivation places memory to a labile state and can lead to two phenomena: memory updating/reconsolidation with possibility of having inaccurate memories (Hupbach et al. 2007) and memory strengthening. By replicating Hupbach et al. (2007, 2008) study, Study 1 aimed to investigate the impact of music upon memory reconsolidation whereas Study 2 explored whether exposure to original learning context is sufficient to trigger reconsolidation. Study 1 found out that reconsolidation process may not be as reliable as suggested in existing reconsolidation studies. Study 2 discovered dissociation between updating of list memory and resistance to the memory-weakening effect of interference, suggesting reactivation-induced reconsolidation can maintain or even strengthen memories. Study 3 tested directly the capacity of memory reactivation to facilitate memory strengthening. An idea of implementing 6 hours interval in between Day 2 sessions was suggested, aimed to determine whether or not the learning effect is mediated by reconsolidation processes. The common effects of retrieval-relearning, relearning-retrieval, relearning-relearning, retrieval-6 hours-relearning, relearning-6 hours-retrieval to strengthen episodic memory may reflect different underlying processes, one or more of which might be related to memory reconsolidation

A key variant in the cis-regulatory element of flowering gene Ghd8 associated with cold tolerance in rice.

Variations in the gene promoter play critical roles in the evolution of important adaptive traits in crops, but direct links of the regulatory mutation to the adaptive change are not well understood. Here, we examine the nucleotide variations in the promoter region of a transcription factor (Ghd8) that control grain number, plant height and heading date in rice. We find that a dominant promoter type of subspecies japonica displayed a high activity for Ghd8 expression in comparison with the one in indica. Transgenic analyses revealed that higher expression levels of Ghd8 delayed heading date and enhanced cold tolerance in rice. Furthermore, a single-nucleotide polymorphism (T1279G) at the position -1279 bp that locates on the potential GA-responsive motif in the Ghd8 promoter affected the expression of this gene. The 1279 T variant has elevated expression of Ghd8, thus conferring increased cold tolerance of rice seedlings. Nucleotide diversity analysis revealed that the approximately 25-kb genomic region surrounding Ghd8 in the subspecies japonica was under significant selection pressure. Our findings demonstrate that the join effects of the regulatory and coding variants largely contribute to the divergence of japonica and indica and increase the adaptability of japonica to the cold environment

Vitamin B2 blocks development of Alzheimer’s disease in APP/PS1 transgenic mice via anti-oxidative mechanism

Purpose: To study the effect of vitamin B2 (VB2) on the development of Alzheimer’s disease (AD).Methods: Memory and learning abilities were assessed in amyloid precursor protein/presenilin-1 (APP/PSI) transgenic mice aged 3 months, and C57BL/6 mice, using Morris water maze test. Brain tissue levels of key antioxidant enzymes, malondialdehyde (MDA), and reactive oxygen species (ROS) were assayed using ELISA kits. Western blot assay was used to monitor the expressions of Nrf2 and Keap1 proteins.Results: Treatment with VB 2 significantly improved cognitive function of APP/PS1 mice with respect to number of crossings, duration of stay in target quadrant (TQ), and escape latency time (p < 0.01). Moreover, VB2 also significantly reduced the levels of MDA and ROS. It also brought about significant increases in brain activities of CAT, SOD, and GSH-Px in APP/PS1 mice, relative to the control group (p < 0.01). Moreover, VB2 up-regulated Nrf2 expression but down-regulated the expression of Keap1 in brain tissue of transgenic mice.Conclusion: These results indicate that VB2 protects the brain from ROS-induced AD damage, most likely due to its potential anti-oxidant property and activation of the Nrf2 pathway.Keywords: Alzheimer’s disease, Cognitive function, Vitamin B2, Reactive oxygen species, Superoxide oxide dismutase, Anti-oxidatio

Experimental and Theoretical Studies on Formability of 22MnB5 at Elevated Temperatures by Gleeble Simulator

AbstractThis paper, which includes an experimental analysis and theoretical predictions, presents a method to investigate the formability of high strength steel sheet 22MnB5 at elevated temperatures. In this method, two designs for tensile test specimens with laser engraving grids are developed and used to obtain the strain paths of a uniaxial tensile state and the plane strain occurring at elevated temperatures using a Gleeble simulator. On the other hand, a modified Cockcroft criterion that takes strain path into consideration is employed to predict the entire forming limit diagram. A forming limit diagram could be established as a result of using the modified Cockcroft criterion together with the limit strains obtained from the tensile tests based on two novel specimen designs. In this paper, forming limit diagrams at three strain rates and forming limit diagrams at temperatures ranging from 650 oC to 850 oC were established