The effect of a market factor on information flow between stocks using the minimal spanning tree

We empirically investigated the effects of market factors on the information flow created from N(N−1)/2 linkage relationships among stocks. We also examined the possibility of employing the minimal spanning tree (MST) method, which is capable of reducing the number of links to N−1. We determined that market factors carry important information value regarding information flow among stocks. Moreover, the information flow among stocks showed time-varying properties according to the changes in market status. In particular, we noted that the information flow increased dramatically during periods of market crises. Finally, we confirmed, via the MST method, that the information flow among stocks could be assessed effectively with the reduced linkage relationships among all links among stocks from the perspective of the overall market.     

Different ocular dominance map formation influenced by orientation preference columns in visual cortices

In animal experiments, the observed orientation preference and ocular dominance columns in the visual cortex of the brain show various pattern types. Here, we show that the different visual map formations in various species are due to the crossover behavior in anisotropic systems composed of orientational and scalar components such as easy-plane Heisenberg models. We predict the transition boundary between different pattern types with the anisotropy as a main bifurcation parameter, which is consistent with experimental observations.     

Submicrometer structure of surface-chemical gradients prepared by a two-step immersion method

Lateral force microscopy and microdroplet density measurements have been used to examine the microstructure of surface-chemical gradients of thiols on gold, prepared by a two-step immersion method. A single-component coverage gradient, generated by gradual immersion of a gold surface into a solution of a single thiol, yielded islands of approximately 25 nm in diameter at the end that had only been briefly immersed, whereas an increasingly continuous film was formed along the gradient. After saturation with a second thiol with a different end group, the structure generated during the initial immersion step was found to persist.     

Linear codes from simplicial complexes

In this article we introduce a method of constructing binary linear codes and computing their weights by means of Boolean functions arising from mathematical objects called simplicial complexes. Inspired by Adamaszek (Am Math Mon 122:367–370, 2015) we introduce n-variable generating functions associated with simplicial complexes and derive explicit formulae. Applying the construction (Carlet in Finite Field Appl 13:121–135, 2007; Wadayama in Des Codes Cryptogr 23:23–33, 2001) of binary linear codes to Boolean functions arising from simplicial complexes, we obtain a class of optimal linear codes and a class of minimal linear codes.     

Up-regulation of defense enzymes is responsible for low reactive oxygen species in malignant prostate cancer cells

Reactive oxygen species (ROS) are involved in a diversity of important phenomena in the process of tumor development. To investigate the alterations of oxidative stress and their related systems in tumor progression, a variety of components in the antioxidative stress defense system were examined in prostate cancer cell lines, PC3 and LNCaP. Cell surface molecules involved in metastasis were expressed highly in PC3 cells compared with LNCaP cells, and strong invasion ability was shown in PC3 cells only. ROS level in LNCaP cells was twice higher than that in PC3 cells, although nitric oxide (NO) level was similar between the two cell lines. The content of GSH increased up to about 2-fold in PC3 compared with LNCaP. Activities of glutathione reductase, thioredoxin reductase, and glutathione S-transferase except catalase are significantly higher in PC3 cells than in LNCaP cells. Furthermore, oxidative stress-inducing agents caused down-regulation of GSH and glutathione S-transferase much more significantly in LNCaP cells than in PC3 cells. These results imply that malignant tumor cells may maintain low ROS content by preserving relatively high anti-oxidative capacity, even in the presence of stressful agents.     

Market efficiency in foreign exchange markets

We investigate the relative market efficiency in financial market data, using the approximate entropy(ApEn) method for a quantification of randomness in time series. We used the global foreign exchange market indices for 17 countries during two periods from 1984 to 1998 and from 1999 to 2004 in order to study the efficiency of various foreign exchange markets around the market crisis. We found that on average, the ApEn values for European and North American foreign exchange markets are larger than those for African and Asian ones except Japan. We also found that the ApEn for Asian markets increased significantly after the Asian currency crisis. Our results suggest that the markets with a larger liquidity such as European and North American foreign exchange markets have a higher market efficiency than those with a smaller liquidity such as the African and Asian markets except Japan.     

Porcine gastric mucin (PGM) at the water/poly(dimethylsiloxane) (PDMS) interface: influence of pH and ionic strength on its conformation, adsorption, and aqueous lubrication properties

We have investigated the influence of pH and ionic strength on the conformation of porcine gastric mucin (PGM) in bulk aqueous solution, its adsorption behavior onto poly(dimethylsiloxane) (PDMS) surfaces, and its lubricating behavior upon the self-mated sliding contact of a PDMS tribopair by means of circular dichroism (CD) spectroscopy, optical waveguide lightmode spectroscopy (OWLS), and pin-on-disk tribometry, respectively. In a low-concentration regime (1 mg/mL), where the formation of a mucus-gel is generally excluded, PGM is still observed to exhibit effective aqueous lubricating properties under specific conditions of acidic pH and low ionic strength. This behavior was closely correlated with specific conformations in the bulk solution as well as specific adsorption behavior at the water/PDMS interface. The lubrication mechanism of the self-mated sliding contact of PDMS by means of surface modification with PGM is discussed in terms of isoviscous-elastic/soft-elastohydrodynamic lubrication (soft-EHL).     

Filter characteristics of a chirped volume holographic grating

We compare and analyze the filter properties of transmission-type volume holographic gratings, especially the dispersion characteristics for uniform and chirped gratings. It is theoretically and experimentally shown that the dispersion characteristics can be controlled by introducing one-dimensional chirping to the volume grating in a photorefractive crystal. The filter response including output power and dispersion comes from a combined effect of the spatial spectra of the grating structure, input beam, and output-coupling fiber mode. Filter responses can be designed by controlling these parameters for optical communication applications.     

NF-κB-dependent miR-31/155 biogenesis is essential for TNF-α-induced impairment of endothelial progenitor cell function

Endothelial progenitor cell (EPC) dysfunction impairs vascular function and remodeling in inflammation-associated diseases, including preeclampsia. However, the underlying mechanism of this inflammation-induced dysfunction remains unclear. In the present study, we found increases in TNF-α and miR-31/155 levels and reduced numbers of circulating EPCs in patients with preeclampsia. Patient-derived mononuclear cells (MNCs) cultured in autologous serum had decreased endothelial nitric oxide synthase (eNOS) expression, nitric oxide production, and differentiation into EPCs with angiogenic potential, and these effects were inhibited by a TNF-α-neutralizing antibody and miR-31/155 inhibitors. Moreover, TNF-α treatment of normal MNCs increased miR-31/155 biogenesis, decreased eNOS expression, reduced EPC differentiation, and impaired angiogenic potential. The TNF-α-induced impairment of EPC differentiation and function was rescued by NF-κB p65 knockdown or miR-31/155 inhibitors. In addition, treatment of MNCs with synthetic miR-31/155 or an eNOS inhibitor mimicked the inhibitory effects of TNF-α on eNOS expression and EPC functions. Moreover, transplantation of EPCs that had been differentiated from TNF-α-treated MNCs decreased neovascularization and blood perfusion in ischemic mouse hindlimbs compared with those of normally differentiated EPCs. These findings suggest that NF-κB activation is required for TNF-α-induced impairment of EPC mobilization, differentiation, and function via miR-31/155 biogenesis and eNOS downregulation. Our data provide a new role for NF-κB-dependent miR-31/155 in EPC dysfunction under the pathogenic conditions of inflammation-associated vascular diseases, including preeclampsia.Subject terms: Differentiation, Cell biology