Static and dynamic properties of frictional phenomena in a one-dimensional system with randomness

Static and dynamic frictional phenomena at the interface with random impurities are investigated in a two-chain model with incommensurate structure. Static frictional force is caused by the impurity pinning and/or by the pinning due to the regular potential, which is responsible for the breaking of analyticity transition for impurity-free cases. It is confirmed that the static frictional force is always finite in the presence of impurities, in contrast to the impurity-free system. The nature of impurity pinning is discussed in connection with that in density waves. The kinetic frictional force of a steady sliding state is also investigated numerically. The relationship between the sliding velocity dependence of the kinetic frictional force and the strength of impurity potential is discussed.Comment: RevTex, 14 pages, 6 PostScript figures, to appear in Phys. Rev.

Role of CC chemokine CCL6/C10 as a monocyte chemoattractant in a murine acute peritonitis.

The aim of this study was to determine the role of CC chemokine CCL6/C10 in acute inflammation. Intraperitoneal injection of thioglycollate increased peritoneal CCL6, which peaked at 4 h and remained elevated at 48 h. Neutralization of CCL6 significantly inhibited the macrophage infiltration (34-48% reduction), but not other cell types, without decreasing the other CC chemokines known to attract monocytes/macrophages. CCL6 was expressed in peripheral eosinophils and elicited macrophages, but not in elicited neutrophils. Peritoneal CCL6 level was not decreased in granulocyte-depleted mice where eosinophil influx was significantly impaired. Thus, CCL6 appears to contribute to the macrophage infiltration that is independent of other CC chemokines. Eosinophils pre-store CCL6, but do not release CCL6 in the peritoneum in this model of inflammation

Superconductivity of the One-Dimensional d-p Model with p-p transfer

Using the numerical diagonalization method, we investigate the one-dimensional $d$-$p$ model, simulating a Cu-O linear chain with strong Coulomb repulsions. Paying attention to the effect of the transfer energy $t_{pp}$ between the nearest neighbor oxygen-sites, we calculate the critical exponent of correlation functions $K_{\rho}$ based on the Luttinger liquid relations and the ground state energy $E_0(\phi)$ as a function of an external flux $\phi$. We find that the transfer $t_{pp}$ increases the charge susceptibility and the exponent $K_{\rho}$ in cooperation with the repulsion $U_{d}$ at Cu-site. We also show that anomalous flux quantization occurs for $K_{\rho}>1$. The superconducting region is presented on a phase diagram of $U_{d}$ vs. $t_{pp}$ plane.Comment: 4 pages, RevTex + 5 PS figures include

Angle-resolved photoemission in high Tc cuprates from theoretical viewpoints

The angle-resolved photoemission (ARPES) technique has been developed rapidly over the last decay, accompanied by the improvement of energy and momentum resolutions. This technique has been established as the most powerful tool to investigate the high Tc cuprate superconductors. We review recent ARPES data on the cuprates from a theoretical point of view, with emphasis on the systematic evolution of the spectral weight near the momentum (pi,0) from insulator to overdoped systems. The effects of charge stripes on the ARPES spectra are also reviewed. Some recent experimental and theoretical efforts to understand the superconducting state and the pseudogap phenomenon are discussed.Comment: Review, 25 pages, with 22 GIF figures. To appear in Supercond. Sci. Technol. Vol. 13 April 2000. A version including PS figures can be found at http://www.maekawa-lab.imr.tohoku.ac.jp/TOHYAMA/tohyama.ps.g

Absence of CC chemokine receptor 8 enhances innate immunity during septic peritonitis

An effective clearance of microbes is crucial in host defense during infection. In the present study, we demonstrate that CC chemokine receptor 8 (CCR8) skews innate immune response during septic peritonitis induced by cecal ligation and puncture (CLP). CCR8 was expressed in resident peritoneal macrophages and elicited leukocytes during CLP in the wildâ type CCR8+/+ mice. CCR8â /â mice were resistant to CLPâ induced lethality relative to CCR8+/+ mice, and this resistance was associated with an augmented bacterial clearance in CCR8â /â mice. In vitro, peritoneal macrophages from CCR8â /â mice, but not neutrophils, exhibited enhanced bactericidal activities relative to those from CCR8+/+ mice. Upon stimulation with the bacterial component LPS, elevated levels of superoxide generation, lysosomal enzyme release, and nitric oxide generation, effector molecules for bacterial killing were detected in CCR8â /â macrophages relative to CCR8+/+ macrophages. In addition, CCR8â /â macrophages produced significantly higher levels than CCR8+/+ macrophages of several cytokines and chemokines known to augment bactericidal activities of leukocytes that include TNFâ α, ILâ 12, macrophageâ derived chemokine (MDC/CCL22), macrophage inflammatory protein (MIP)â 2, and KC. Altogether, these results indicate that CCR8 may have a negative impact on host defense during septic peritonitis, providing a new paradigm for the role of CCR8 in innate immunity.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154456/1/fsb2fj041728fje.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154456/2/fsb2fj041728fje-sup-0001.pd

Measurement of the cosmic-ray antiproton spectrum at solar minimum with a long-duration balloon flight over Antarctica

The energy spectrum of cosmic-ray antiprotons from 0.17 to 3.5 GeV has been measured using 7886 antiprotons detected by BESS-Polar II during a long-duration flight over Antarctica near solar minimum in December 2007 and January 2008. This shows good consistency with secondary antiproton calculations. Cosmologically primary antiprotons have been investigated by comparing measured and calculated antiproton spectra. BESS-Polar II data show no evidence of primary antiprotons from evaporation of primordial black holes.Comment: 4 pages, 4 figures, submitted to Physical Review Letter

d-Wave Superconductivity Induced by Chern-Simons Term in High-TcT_c Cuprates

We show that a Chern-Simons term for a gauge field describing a fluctuation of spins is induced by integrating out hole fields in the presence of spin-orbit coupling which originates from a buckling of the CuO$_2$ plane. Through the Chern-Simons term, holes behave like skyrmion excitations in a spin system and become a superconducting state with $d_{x^2-y^2}$ symmetry after the antiferromagnetic long-range order is destroyed.Comment: 4 pages, 1 figure, the condition of taking continuum limit included, references added, typos corrected, to be published in Journal of Physical Society of Japa

Sliding motion of a two-dimensional Wigner crystal in a strong magnetic field

We study the sliding state of a two-dimensional Wigner crystal in a strong magnetic field and a random impurity potential. Using a high-velocity perturbation theory, we compute the nonlinear conductivity, various correlation functions, and the interference effects arising in combined AC + DC electric effects, including the Shapiro anomaly and the linear response to an AC field. Disorder is found to induce mainly transverse distortions in the sliding state of the lattice. The Hall resistivity retains its classical value. We find that, within the large velocity perturbation theory, free carriers which affect the longitudinal phonon modes of the Wigner crystal do not change the form of the nonlinear conductivity. We compare the present sliding Wigner crystal in a strong magnetic field to the conventional sliding charge-density wave systems. Our result for the nonlinear conductivity agrees well with the $I-V$ characteristics measured in some experiments at low temperatures or large depinning fields, for the insulating phases near filling factor $\nu$ = 1/5. We summarize the available experimental data, and point out the differences among them.Comment: appeared in RPB vol. 50, 4600 (1994); LaTex file; 3 figures available from [email protected]

Direct observation of the washboard noise of a driven vortex lattice in a high-temperature superconductor, Bi2Sr2CaCu2Oy

We studied the conduction noise spectrum in the vortex state of a high-temperature superconductor, Bi2Sr2CaCu2Oy, subject to a uniform driving force. Two characteristic features, a broadband noise (BBN) and a narrow-band noise (NBN), were observed in the vortex-solid phase. The origin of the large BBN was determined to be plastic motion of the vortices, whereas the NBN was found to originate from the washboard modulation of the translational velocity of the driven vortices. We believe this to be the first observation ofComment: 4 pages, 4 figures, to appear in Phys. Rev. Let