1,144 research outputs found
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
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
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
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
Matching conditions in the quasicontinuum method: Removal of the error introduced at the interface between the coarse-grained and fully atomistic region
金沢大学大学院自然科学研究科機能開発システム金沢大学工学部The quasicontinuum method is a way of reducing the number of degrees of freedom in an atomistic simulation by removing the majority of the atoms in regions of slowly varying strain fields. Due to the different ways the energy of the atoms is calculated in the coarse-grained regions and the regions where all the atoms are present, unphysical forces called "ghost forces" arise at the interfaces. Corrections may be used to almost remove the ghost forces, but the correction forces are nonconservative, ruining energy conservation in dynamic simulations. We show that it is possible to formulate the quasicontinuum method without these problems by introducing a buffer layer between the two regions of space. The method is applicable to short-ranged potentials in the face-centered cubic, body-centered cubic, and hexagonal close-packed crystal structures
Stochastic Resonance of Ensemble Neurons for Transient Spike Trains: A Wavelet Analysis
By using the wavelet transformation (WT), we have analyzed the response of an
ensemble of (=1, 10, 100 and 500) Hodgkin-Huxley (HH) neurons to {\it
transient} -pulse spike trains () with independent Gaussian noises.
The cross-correlation between the input and output signals is expressed in
terms of the WT expansion coefficients. The signal-to-noise ratio (SNR) is
evaluated by using the {\it denoising} method within the WT, by which the noise
contribution is extracted from output signals. Although the response of a
single (N=1) neuron to sub-threshold transient signals with noises is quite
unreliable, the transmission fidelity assessed by the cross-correlation and SNR
is shown to be much improved by increasing the value of : a population of
neurons play an indispensable role in the stochastic resonance (SR) for
transient spike inputs. It is also shown that in a large-scale ensemble, the
transmission fidelity for supra-threshold transient spikes is not significantly
degraded by a weak noise which is responsible to SR for sub-threshold inputs.Comment: 20 pages, 4 figure
Lansoprazole inhibits mitochondrial superoxide production and cellular lipid peroxidation induced by indomethacin in RGM1 cells
Lansoprazole is effective in healing non-steroidal anti-inflammatory drugs induced ulcers, and antioxidant properties have been thought to play a key role in healing ulcers. We hypothesize that lansoprazole exerts a cytoprotective effect by inhibiting reactive oxygen species leakage from mitochondria and lipid peroxidation. We pretreated gastric epithelial RGM1 cells with lansoprazole and then treated them with indomethacin in vitro. We found that the lansoprazole pretreatment significantly reduced cellular injury, maintained mitochondrial transmembrane potential, and decreased lipid peroxidation. Furthermore, the signal intensity of the electron spin resonance spectrum of the indomethacin-treated mitochondria which were pretreated with lansoprazole showed considerable reduction compared to those without the lansoprazole pretreatment. These results suggest that lansoprazole reduced superoxide production in the mitochondria of indomethacin treated cells, and subsequently inhibited lipid peroxide and cellular injury in gastric epithelial cells
Bipartite Entanglement in Continuous-Variable Cluster States
We present a study of the entanglement properties of Gaussian cluster states,
proposed as a universal resource for continuous-variable quantum computing. A
central aim is to compare mathematically-idealized cluster states defined using
quadrature eigenstates, which have infinite squeezing and cannot exist in
nature, with Gaussian approximations which are experimentally accessible.
Adopting widely-used definitions, we first review the key concepts, by
analysing a process of teleportation along a continuous-variable quantum wire
in the language of matrix product states. Next we consider the bipartite
entanglement properties of the wire, providing analytic results. We proceed to
grid cluster states, which are universal for the qubit case. To extend our
analysis of the bipartite entanglement, we adopt the entropic-entanglement
width, a specialized entanglement measure introduced recently by Van den Nest M
et al., Phys. Rev. Lett. 97 150504 (2006), adapting their definition to the
continuous-variable context. Finally we add the effects of photonic loss,
extending our arguments to mixed states. Cumulatively our results point to key
differences in the properties of idealized and Gaussian cluster states. Even
modest loss rates are found to strongly limit the amount of entanglement. We
discuss the implications for the potential of continuous-variable analogues of
measurement-based quantum computation.Comment: 22 page
Osteonectin, bone proteoglycan, and phosphophoryn defects in a form of bovine osteogenesis imperfecta.
- …