Attraction of Spiral Waves by Localized Inhomogeneities with Small-World Connections in Excitable Media

Trapping and un-trapping of spiral tips in a two-dimensional homogeneous excitable medium with local small-world connections is studied by numerical simulation. In a homogeneous medium which can be simulated with a lattice of regular neighborhood connections, the spiral wave is in the meandering regime. When changing the topology of a small region from regular connections to small-world connections, the tip of a spiral waves is attracted by the small-world region, where the average path length declines with the introduction of long distant connections. The "trapped" phenomenon also occurs in regular lattices where the diffusion coefficient of the small region is increased. The above results can be explained by the eikonal equation and the relation between core radius and diffusion coefficient.Comment: 5 pages, 4 figure

The SNARE protein FolVam7 mediates intracellular trafficking to regulate conidiogenesis and pathogenicity in Fusarium oxysporum f. sp. lycopersici.

Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are conserved in fungi, plants and animals. The Vam7 gene encodes a v-SNARE protein that involved in vesicle trafficking in fungi. Here, we identified and characterized the function of FolVam7, a homologue of the yeast SNARE protein Vam7p in Fusarium oxysporum f. sp. lycopersici (Fol), a fungal pathogen of tomato. FolVam7 contains SNARE and PX (Phox homology) domains that are indispensable for normal localization and function of FolVam7. Targeted gene deletion showed that FolVam7-mediated vesicle trafficking is important for vegetative growth, asexual development, conidial morphology and plant infection. Further cytological examinations revealed that FolVam7 is localized to vesicles and vacuole membranes in the hyphae stage. Moreover, the ΔFolvam7 mutant is insensitive to salt and osmotic stresses and hypersensitive to cell wall stressors. Taken together, our results suggested that FolVam7-mediated vesicle trafficking promotes vegetative growth, conidiogenesis and pathogenicity of Fol

International Standards For Exporting Firms: Evidence From China

The existing literature provides mixed evidence of the impact of ISO 9000 international standards on country level export growth.  Since it is costly to adopt the international standards, it is important to understand how these standards increase exports at the firm level.  This paper examines the effect of ISO 9000 standards on firm-level export growth in China, which of all countries has the highest number of firms adopting ISO 9000 standards.  With the assortative matching methodology, we first examine the factors related to the choice of applying for the certification. After controlling for this endogeneity issue, our results show that obtaining ISO 9000 standards significantly increases firm exports.  Furthermore, we find low-tech firms and non-state-owned enterprises are more likely to benefit from adopting the standards.  Overall, our study provides important guidelines for firms applying for the international quality standards

International standards for exporting firms: Evidence from China

The existing literature provides mixed evidence of the impact of ISO 9000 international standards on country level export growth. Since it is costly to adopt the international standards, it is important to understand how these standards increase exports at the firm level. This paper examines the effect of ISO 9000 standards on firm-level export growth in China, which of all countries has the highest number of firms adopting ISO 9000 standards. With the assortative matching methodology, we first examine the factors related to the choice of applying for the certification. After controlling for this endogeneity issue, our results show that obtaining ISO 9000 standards significantly increases firm exports. Furthermore, we find low-tech firms and non-state-owned enterprises are more likely to benefit from adopting the standards. Overall, our study provides important guidelines for firms applying for the international quality standards