Bacterial chemotaxis without gradient-sensing

Models for chemotaxis are based on gradient sensing of individual organisms. The key contribution of Keller and Segel is showing that erratic movements of individuals may result in an accurate chemotaxis phenomenon as a group. In this paper we provide another option to understand chemotactic behavior when individuals do not sense the gradient of chemical concentration by any means. We show that, if individuals increase their motility to find food when they are hungry, an accurate chemotactic behavior may obtained without sensing the gradient. Such a random dispersal has been suggested by Cho and Kim and is called starvation driven diffusion. This model is surprisingly similar to the original derivation of Keller-Segel model. A comprehensive picture of traveling band and front solutions is provided with numerical simulations.Comment: 19 pages, 4 figure

The factors influencing a contract payment structure in biotech licensing deals

Department of Management EngineeringThere are many studies which try to identify and verify theoretically and empirically many factors influencing technology market???s elements including rate of technology licensing, informational asymmetry, pricing of technology and so forth. In this study, based on conventional bargaining power???s approach and signaling theory???s perspective, I identified and verified empirically a couple of determinants influencing contract payment structure of licensing. Licensor???s size and licensee???s size has a positive impact on a share of fixed upfront payment in contract payment structure. Licensed technology???s development phase has a positive impact on a share of fixed upfront payment in contract payment structure and licensing region has a negative impact on a share of fixed upfront payment in contract payment structure. There is significant moderation of technology development phase on direct effect of licensor???s size and leverage on contact payment structure. Generally, in biotechnology industry, conventional bargaining power???s approach is dominant over signaling theory???s perspective. Total asset as a proxy for size is justified empirically compared to other size measures such as total revenue.ope

Hodge ideals and spectrum of isolated hypersurface singularities

We introduce Hodge ideal spectrum for isolated hypersurface singularities to see the difference between the Hodge ideals and the microlocal $V$-filtration modulo the Jacobian ideal. Via the Tjurina subspectrum, we can compare the Hodge ideal spectrum with the Steenbrink spectrum which can be defined by the microlocal $V$-filtration. As a consequence of a formula of Mustata and Popa, these two spectra coincide in the weighted homogeneous case. We prove sufficient conditions for their coincidence and non-coincidence in some non-weighted-homogeneous cases where the defining function is semi-weighted-homogeneous or with non-degenerate Newton boundary in most cases. We also show that the convenience condition can be avoided in a formula of Zhang for the non-degenerate case, and present an example where the Hodge ideals are not weakly decreasing even modulo the Jacobian ideal.Comment: 29 page

Anti-anxiety effect of methanol extract of Pericarpium zanthoxyli using a strychnine-sensitive glycine receptor model

Purpose: To determine if the methanol extract of Pericarpium zanthoxyli exerts anti-anxiety effects and also to explore any probable anti-anxiety mechanism in vivo.Methods: The staircase test, elevated plus maze test, rota-rod treadmill test and convulsions induced by strychnine and picrotoxin on mice were tested to identify potential mechanism of anti-anxiety activity of the plant extract.Results: The plant extract (10 mg/kg, p.o.) significantly reduced rearing numbers in the staircase test while it increased the time spent in the open arms as well as the number of entries to the open arms in the elevated plus maze test, suggesting that it has significant anti-anxiety activity. Furthermore, the extract inhibited strychnine-induced convulsion. However, it had little effect on picrotoxin-induced convulsion, suggesting that its anti-anxiety activity may be linked to strychnine-sensitive glycine receptor and not GABA receptor.Conclusion: These results suggest that the Pericarpium zanthoxyli extract may be beneficial for the control of anxiety.Keywords: Anti-anxiety, Pericarpium zanthoxyli, Glycine Receptor, GABA Recepto