Two-Form Gravity and the Generation of Space-Time

In the framework of the two-form gravity, which is classically equivalent to the Einstein gravity, the one-loop effective potential for the conformal factor of metric is calculated in the finite volume and in the finite temperature by choosing a temporal gauge condition. There appears a quartically divergent term which cannot be removed by the renormalization of the cosmological term and we find there is only one non-trivial minimum in the effective potential. If the cut-off scale has a physical meaning, \eg the Planck scale coming from string theory, this minimum might explain why the space-time is generated, \ie why the classical metric has a non-trivial value.Comment: Latex file, 18p

Is the Condensation of Strings the Origin of Einstein Gravity ?

A mechanism of generating the metric is proposed, where the Kalb-Ramond symmetry existing in the topological BF theory is broken through the condensation of the string fields which are so introduced as to couple with the anti-symmetric tensor fields $B$, invariantly under the Kalb-Ramond symmetry. In the chiral decomposition of the local Lorentz group, the non-Abelian $B$ fields need to be generalized to the string fields. The mechanism of the condensation is discussed, viewing the confinement problem and the polymer physics.Comment: Latex file, 12p

Identification of a strong binding site for kinesin on the microtubule using mutant analysis of tubulin

The kinesin-binding site on the microtubule has not been identified because of the technical difficulties involved in the mutant analyses of tubulin. Exploiting the budding yeast expression system, we succeeded in replacing the negatively charged residues in the α-helix 12 of β-tubulin with alanine and analyzed their effect on kinesin–microtubule interaction in vitro. The microtubule gliding assay showed that the affinity of the microtubules for kinesin was significantly reduced in E410A, D417A, and E421A, but not in E412A mutant. The unbinding force measurement revealed that in the former three mutants, the kinesin–microtubule interaction in the adenosine 5′-[β,γ-imido]triphosphate state (AMP-PNP state) became less stable when a load was imposed towards the microtubule minus end. In parallel with this decreased stability, the stall force of kinesin was reduced. Our results implicate residues E410, D417, and E421 as crucial for the kinesin–microtubule interaction in the strong binding state, thereby governing the size of kinesin stall force