18,075 research outputs found
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 -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 -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
- …