1,297 research outputs found
Mechanochemical enzymes and protein machines as hydrodynamic force dipoles: The active dimer model
Mechanochemically active enzymes change their shapes within every turnover cycle. Therefore, they induce circulating flows in the solvent around them and behave as oscillating hydrodynamic force dipoles. Because of non-equilibrium fluctuating flows collectively generated by the enzymes, mixing in the solution and diffusion of passive particles within it are expected to get enhanced. Here, we investigate the intensity and statistical properties of such force dipoles in the minimal active dimer model of a mechanochemical enzyme. In the framework of this model, novel estimates for hydrodynamic collective effects in solution and in lipid bilayers under rapid rotational diffusion are derived, and available experimental and computational data is examined
Developing Cloud Chambers with High School Students
The result and outcome of the \textit{cloud chamber project}, which aims to
develop a cloud chamber useful for science education is reported in detail. A
project includes both three high school students and a teacher as a part of
Super Science High School (SSH) program in our school. We develop a
dry-ice-free cloud chamber using salt and ice (or snow). Technical details of
the chamber are described. We also argue how the project have affected
student's cognition, motivation, academic skills and behavior. The research
project has taken steps of professional researchers, i.e., in planning
research, applying fund, writing a paper and giving a talk in conferences. From
interviews with students, we have learnt that such style of scientific activity
is very effective in promoting student's motivation for learning science.Comment: 9 pages, accepted to the proceedings of APPC12 - the 12th Asia
Pacific Physics Conferenc
Relation between the separable and one-boson-exchange potential for the covariant Bethe-Salpeter equation
We investigate the relation between the rank I separable potential for the
covariant Bethe-Salpeter equation and the one-boson-exchange potential. After
several trials of the parameter choices, it turns out that it is not always
possible to reproduce the phase-shifts calculated from a single term of the
one-boson-exchange potential especially of the -exchange term,
separately by the rank I separable potential. Instead, it is shown that the
separable potential is useful to parameterize the total nucleon-nucleon
interaction.Comment: 10 pages, 8 figures, to appear in J.Phys.
Exotic hadrons in s-wave chiral dynamics
We study s-wave scattering of a hadron and a Nambu-Goldstone boson induced by
the model-independent low energy interaction in the flavor SU(3) symmetric
limit. Establishing the general structure of the low energy interaction based
on group theoretical arguments, we find that the interaction in the exotic
channels are in most cases repulsive, and that for possible attractive channels
the interaction strengths are weak and uniquely given independent of channel.
Solving the scattering problem with this interaction, we show that the
attraction in the exotic channels is not strong enough to generate a bound
state from the physically known target hadrons. We also find that there are no
attractive interaction in the exotic channels in large Nc limit.Comment: RevTeX4, 4 pages, 1 figure, 2 tables, typos correcte
Exotic mesons with hidden charm and bottom near thresholds
We study heavy hadron spectroscopy near heavy meson thresholds. We employ
heavy pseudoscalar meson P and heavy vector meson P* as effective degrees of
freedom and consider meson exchange potentials between them. All possible
composite states which can be constructed from the P and P* mesons are studied
up to the total angular momentum J <= 2. We consider, as exotic states,
isosinglet states with exotic J^{PC} quantum numbers and isotriplet states. We
solve numerically the Schr\"odinger equation with channel-couplings for each
state. We found B(*)barB(*) molecule states for I^G(J^{PC}) = 1^+(1^{+-})
correspond to the masses of twin resonances Zb(10610) and Zb(10650). We predict
several possible B(*)barB(*) bound and/or resonant states in other channels. On
the other hand, there are no B(*)barB(*) bound and/or resonant states whose
quantum numbers are exotic.Comment: 10 pages, 1 figure, to appear in the proceedings of The 5th
International Workshop on Charm Physics (Charm 2012
Study of exotic hadrons in S-wave scatterings induced by chiral interaction in the flavor symmetric limit
We study s-wave bound states of a hadron and a light pseudoscalar meson
induced by the Weinberg-Tomozawa (WT) interaction in the flavor SU(3) symmetric
limit. The WT interaction is a driving force to generate quasibound states
dynamically in the chiral unitary approaches. The strength and sign of the WT
interaction are determined only by the group theoretical structure of the
target hadrons, and we present a general expression of the strengths for the
flavor SU(3) case. We show that, for the channels which are more exotic than
the target, the interaction is repulsive in most cases, and the strength of the
attractive interaction is universal for any possible target states. We
demonstrate that the attractive coupling is not strong enough to generate an
exotic state from the physically known masses of target hadrons. In addition,
we also find a nontrivial Nc dependence of the coupling strengths. We show that
the channels which are attractive at Nc=3 changes into repulsive ones for large
Nc, and, therefore, no attractive interaction exists in exotic channels in the
large-Nc limit.Comment: RevTeX4, 16 pages, 5 figure, 6 tables, This manuscript is a full
paper of Phys. Rev. Lett. 97, 192002 (hep-ph/0609014), typos corrected, final
versio
Feedback-free optical cavity with self-resonating mechanism
We demonstrated the operation of a high finesse optical cavity without
utilizing an active feedback system to stabilize the resonance. The effective
finesse, which is a finesse including the overall system performance, of the
cavity was measured to be , and the laser power stored in
the cavity was kW, which is approximately 187,000 times greater
than the incident power to the cavity. The stored power was stabilized with a
fluctuation of , and we confirmed continuous cavity operation for more
than two hours. This result has the potential to trigger an innovative
evolution for applications that use optical resonant cavities such as compact
photon sources with laser-Compton scattering or cavity enhanced absorption
spectroscopy.Comment: 5 pages, 7 figure
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