1,372 research outputs found
A chemically driven fluctuating ratchet model for actomyosin interaction
With reference to the experimental observations by T. Yanagida and his
co-workers on actomyosin interaction, a Brownian motor of fluctuating ratchet
kind is designed with the aim to describe the interaction between a Myosin II
head and a neighboring actin filament. Our motor combines the dynamics of the
myosin head with a chemical external system related to the ATP cycle, whose
role is to provide the energy supply necessary to bias the motion. Analytical
expressions for the duration of the ATP cycle, for the Gibbs free energy and
for the net displacement of the myosin head are obtained. Finally, by
exploiting a method due to Sekimoto (1997, J. Phys. Soc. Jpn., 66, 1234), a
formula is worked out for the amount of energy consumed during the ATP cycle.Comment: 15 pages. 1 figur
Magnetization curve of the kagome-strip-lattice antiferromagnet
We study the magnetization curve of the Heisenberg model on the
quasi-one-dimensional kagome-strip lattice that shares the same lattice
structure in the inner part with the two-dimensional kagome lattice. Our
numerical calculations based on the density matrix renormalization group method
reveal that the system shows several magnetization plateaus between zero
magnetization and the saturated one; we find the presence of the magnetic
plateaus with the n=7 height of the saturation for n =1,2,3,4,5 and 6 in the S
=1/2 case, whereas we detect only the magnetic plateaus of n =1,3,5 and 6 in
the S =1 case. In the cases of n =2,4 and 6 for the S=1/2 system, the
Oshikawa-Yamanaka-Affleck condition suggests the occurrence of the
translational symmetry breaking (TSB). We numerically confirm this non-trivial
TSB in our results of local magnetizations. We have also found that the
macroscopic jump appears near the saturation field irrespective of the spin
amplitude as well as the two-dimensional kagome model.Comment: 6pages, 3figures, accepted for publication in Journal of Low
Temperature Physic
Characterization of Knots and Links Arising From Site-specific Recombination on Twist Knots
We develop a model characterizing all possible knots and links arising from
recombination starting with a twist knot substrate, extending previous work of
Buck and Flapan. We show that all knot or link products fall into three
well-understood families of knots and links, and prove that given a positive
integer , the number of product knots and links with minimal crossing number
equal to grows proportionally to . In the (common) case of twist knot
substrates whose products have minimal crossing number one more than the
substrate, we prove that the types of products are tightly prescribed. Finally,
we give two simple examples to illustrate how this model can help determine
previously uncharacterized experimental data.Comment: 32 pages, 7 tables, 27 figures, revised: figures re-arranged, and
minor corrections. To appear in Journal of Physics
Demonstration of unconditional one-way quantum computations for continuous variables
Quantum computing promises to exploit the laws of quantum mechanics for
processing information in ways fundamentally different from today's classical
computers, leading to unprecedented efficiency. One-way quantum computation,
sometimes referred to as the cluster model of quantum computation, is a very
promising approach to fulfil the capabilities of quantum information
processing. The cluster model is realizable through measurements on a highly
entangled cluster state with no need for controlled unitary evolutions. Here we
demonstrate unconditional one-way quantum computation experiments for
continuous variables using a linear cluster state of four entangled optical
modes. We implement an important set of quantum operations, linear
transformations, in the optical phase space through one-way computation. Though
not sufficient, these are necessary for universal quantum computation over
continuous variables, and in our scheme, in principle, any such linear
transformation can be unconditionally and deterministically applied to
arbitrary single-mode quantum states.Comment: 9 pages, 3 figure
Ferrimagnetism of the Heisenberg Models on the Quasi-One-Dimensional Kagome Strip Lattices
We study the ground-state properties of the S=1/2 Heisenberg models on the
quasi-onedimensional kagome strip lattices by the exact diagonalization and
density matrix renormalization group methods. The models with two different
strip widths share the same lattice structure in their inner part with the
spatially anisotropic two-dimensional kagome lattice. When there is no magnetic
frustration, the well-known Lieb-Mattis ferrimagnetic state is realized in both
models. When the strength of magnetic frustration is increased, on the other
hand, the Lieb-Mattis-type ferrimagnetism is collapsed. We find that there
exists a non-Lieb-Mattis ferrimagnetic state between the Lieb-Mattis
ferrimagnetic state and the nonmagnetic ground state. The local magnetization
clearly shows an incommensurate modulation with long-distance periodicity in
the non-Lieb-Mattis ferrimagnetic state. The intermediate non-Lieb-Mattis
ferrimagnetic state occurs irrespective of strip width, which suggests that the
intermediate phase of the two-dimensional kagome lattice is also the
non-Lieb-Mattis-type ferrimagnetism.Comment: 9pages, 11figures, accepted for publication in J. Phys. Soc. Jp
Upper Cervical Spine Trauma: WFNS Spine Committee Recommendations
Craniovertebral junction (CVJ) trauma is a challenging clinical condition. Being a highly mobile functional unit at the junction of the skull and the vertebral column, traumatic events in this area may produce devastating neurological complications and death. Additionally, many of the CVJ traumatic injuries can be left undiagnosed or even raise difficult treatment dilemmas. We present a literature review in the format of recommendations on the diagnosis and management of different scenarios for upper cervical trauma and produce recommendations, which can be applicable to various areas of the globe.info:eu-repo/semantics/publishedVersio
Li+D Reaction in Pd and Au for 30<E_d<75 keV(I. Nuclear Physics)
Thick target yields of α particles emitted in the ^Li (d, α) ^He reactions in PdLi_x and AuLi_x were measured as a function of the bombarding energy between 30 and 75 keV. It was found that the reaction rate in Pd at lower energies is enhanced strongly over the one predicted by the cross section for the reaction with bare nuclei, but no enhancement is observed in Au. A screening energy is introduced to reproduce the excitation function of the thick target yield for each metal. The deduced value for Pd amounts to 1500±310 eV, whereas it is only 60±150 eV for Au. The enhancement in the Pd case cannot be explained by electron screening alone but suggests the existence of an additional and important mechanism of screening in metal
Synchronization of uncoupled oscillators by common gamma impulses: from phase locking to noise-induced synchronization
Nonlinear oscillators can mutually synchronize when they are driven by common
external impulses. Two important scenarios are (i) synchronization resulting
from phase locking of each oscillator to regular periodic impulses and (ii)
noise-induced synchronization caused by Poisson random impulses, but their
difference has not been fully quantified. Here we analyze a pair of uncoupled
oscillators subject to common random impulses with gamma-distributed intervals,
which can be smoothly interpolated between regular periodic and random Poisson
impulses. Their dynamics are charac- terized by phase distributions, frequency
detuning, Lyapunov exponents, and information-theoretic measures, which clearly
reveal the differences between the two synchronization scenarios.Comment: 18 page
Ethyl pyruvate improves pulmonary function in mice with bleomycin-induced lung injury as monitored with hyperpolarized 129Xe MR imaging
Purpose: High Mobility Group Box1 (HMGB1), which is one of the damage-associated molecular pattern molecules relating to various inflammatory diseases, has gained interest as a therapeutic target because of its involvement in wound healing processes. In the present study, we investigated HMGB1 as a potential therapeutic target in a model of lung fibrosis using a preclinical hyperpolarized 129Xe (HPXe) MRI system.
Methods: Lung injury was induced by intra-peritoneal injection of bleomycin (BLM) in 19 mice. Three weeks post-injection (when fibrosis was confirmed histologically), administration of ethyl pyruvate (EP) and alogliptin (ALG), which are down- and up-regulators of HMGB1, respectively, was commenced in six and seven of the 19 mice, respectively, and continued for a further 3 weeks. A separate sham-instilled group was formed of five mice, which were administered with saline for 6 weeks. Over the second 3-week period, the effects of disease progression and pharmacological therapy in the four groups of mice were monitored by HPXe MRI metrics of fractional ventilation and gas-exchange function.
Results: Gas-exchange function in BLM mice was significantly reduced after 3 weeks of BLM challenge compared to sham-instilled mice (P < 0.05). Ethyl pyruvate was found to improve HPXe MRI metrics of both ventilation and gas exchange, and repair tissue damage (assessed histologically), to a similar level as sham-instilled mice (P < 0.05), whilst ALG treatment caused no significant improvement of pulmonary function.
Conclusion: This study demonstrates the down-regulator of HMGB1, EP, as a potential therapeutic agent for pulmonary fibrosis, as assessed by a non-invasive HPXe MRI protocol
- …