Anomalous behavior of the spin gap of a spin-1/2 two-leg antiferromagnetic ladder with Ising-like rung interactions

Using mainly numerical methods, we investigate the width of the spin gap of a spin-1/2 two-leg ladder described by \cH= J_\rl \sum_{j=1}^{N/2} [ \vS_{j,a} \cdot \vS_{j+1,a} + \vS_{j,b} \cdot \vS_{j+1,b} ] + J_\rr \sum_{j=1}^{N/2} [\lambda (S^x_{j,a} S^x_{j,b} + S^y_{j,a} S^y_{j,b}) + S^z_{j,a} S^z_{j,b}] , where $S^\alpha_{j,a(b)}$ denotes the $\alpha$-component of the spin-1/2 operator at the $j$-th site of the $a (b)$ chain. We mainly focus on the J_\rr \gg J_\rl > 0 and $|\lambda| \ll 1$ case. The width of the spin gap as a function of $\lambda$ anomalously increases near $\lambda = 0$; for instance, for $-0.1 < \lambda < 0.1$ when $J_{\rm l}/J_{\rm r} = 0.1$. The gap formation mechanism is thought to be different for the $\lambda 0$ cases. Since, in usual cases, the width of the gap becomes zero or small at the point where the gap formation mechanism changes, the above gap-increasing phenomenon in the present case is anomalous. We explain the origin of this anomalous phenomenon by use of the degenerate perturbation theory. We also draw the ground-state phase diagram.Comment: 4 pages, 11 figures; Proc. "The International Conference on Quantum Criticality and Novel Phases" (2012), to be published in Phys. Stat. Solidi

Visual Feedback Without Geometric Features Against Occlusion: A Walsh Basis

Date of Online Publication: 09 January 2018For a visual feedback without geometric features, this brief suggests to apply a basis made by the Walsh functions in order to reduce the off-line experimental cost. Depending on the resolution, the feedback is implementable and achieves the closed-loop stability of dynamical systems as long as the input-output linearity on matrix space exists. Remarkably, a part of the whole occlusion effects is rejected, and the remaining part is attenuated. The validity is confirmed by the experimental feedback for nonplanar sloshing

Alteration of chemokine production in bovine endometrial epithelial and stromal cells under heat stress conditions

After parturition, cows frequently develop uterine bacterial infections, resulting in the onset of endometritis. To eliminate the bacteria, bovine endometrial cells secrete chemokines, such as IL-6 and MCP1, which attract macrophages (M Phi s) to the subepithelial stroma. These attracted M Phi s are not only involved in bacterial elimination but also the orchestration of inflammation and tissue repair. These immune responses aid in the recovery from endometritis; however, the recovery from endometritis takes longer in summer than in any other season. Based on these findings, we hypothesized that heat stress (HS) affects the chemokine production in endometrial cells. To confirm this hypothesis, we compared IL-6 and MCP1 production induced by lipopolysaccharide (LPS) in bovine endometrial epithelial and stromal cells under normal (38.5 degrees C) and HS conditions (40.5 degrees C). In the endometrial epithelial cells, IL-6 production stimulated by LPS was significantly (p < .05) suppressed under HS conditions. MCP1 production in endometrial epithelial cells was not detected under both the control and HS conditions regardless of the presence of LPS. Moreover, LPS significantly (p < .05) stimulated IL-6 and MCP1 production in endometrial stromal cells. Moreover, HS significantly (p < .05) enhanced their production compared to that under the control conditions. In addition, HS did not affect the migration ability of M Phi s; however, the supernatant of the endometrial stromal cells cultured under the HS condition significantly (p < .05) attracted the M Phi s when compared to the control condition. These results suggest that HS disrupts chemokine production in two types of endometrial cells and alters the distribution of M Phi s in the endometrium during the summer

Hepatocyte growth factor and Met in drug discovery

Activation of the hepatocyte growth factor (HGF)-Met pathway evokes dynamic biological responses that support the morphogenesis, regeneration and survival of cells and tissues. A characterization of conditional Met knockout mice indicates that the HGF-Met pathway plays important roles in the regeneration, protection and homeostasis of cells such as hepatocytes, renal tubular cells and neurons. Preclinical studies in disease models have indicated that recombinant HGF protein and expression plasmid for HGF are biological drug candidates for the treatment of patients with diseases or injuries that involve impaired tissue function. The phase-I and phase-I/II clinical trials of the intrathecal administration of HGF protein for the treatment of patients with amyotrophic lateral sclerosis and spinal cord injury, respectively, are ongoing. Biological actions of HGF that promote the dynamic movement, morphogenesis and survival of cells also closely participate in invasion-metastasis and resistance to the molecular-targeted drugs in tumour cells. Different types of HGF-Met pathway inhibitors are now in clinical trials for treatment of malignant tumours. Basic research on HGF and Met has lead to drug discoveries in regenerative medicine and tumour biology. © The Authors 2015. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved