Nonhermitian adiabatic perturbation theory of topological quantization of the average velocity of a magnetic skyrmion under thermal fluctuations

We study the two-dimensional motion of a magnetic skyrmion driven by a ratchetlike polarized electric current that is periodic in both space and time. Some general cases are considered, in each of which,in the low temperature and adiabatic limit, regardless of the details of the driving current, the time and statistical average velocity along any direction is topologically quantized as a Chern number, multiplied by a basic unit. We make two approaches, one based on identifying the drift direction, and the other based on the nonhermitian adiabatic perturbation theory developed for the Fokker-Planck operator. Both approach applies in the case of periodicity along the direction of the driving current and homogeneity in the transverse direction, for which the analytical result is confirmed by our numerical simulation on the constituent spins,and a convenient experiment is proposed.Comment: 32 pages, preprint forma

Accelerating Unruh-DeWitt detectors coupled with a spinor field

The behavior of accelerating Unruh-DeWitt detectors coupled with a spinor field in (3+1)-dimensional spacetime is investigated. For a single point-like detector with Gaussian switching function, the transition probability increases with the acceleration and thus the antiUnruh effect effect cannot occur. Due to the spinor structure of the Dirac field, UV divergences are encountered in the calculation of the entanglement between the detectors. After introducing some UV cutoff $\Lambda$, the logarithmic negativity of detectors is shown to behave nonmonotonically with respect to the acceleration. Besides, the logarithmic negativity increases with the cutoff $\Lambda$ and decreases with the distance between the detectors. The mutual information between the two detectors is also discussed.Comment: 30 page

Robust Preparation of GHZ and W States of Three Distant Atoms

Schemes to generate Greenberger-Horne-Zeilinger(GHZ) and W states of three distant atoms are proposed in this paper. The schemes use the effects of quantum statistics of indistinguishable photons emitted by the atoms inside optical cavities. The advantages of the schemes are their robustness against detection inefficiency and asynchronous emission of the photons. Moreover, in Lamb-Dicke limit, the schemes do not require simultaneous click of the detectors, this makes the schemes more realizable in experiments.Comment: 5 pages, 1 fiure. Phys. Rev. A 75, 044301 (2007

Knockdown of Rab5a expression decreases cancer cell motility and invasion through integrin-mediated signaling pathway

<p>Abstract</p> <p>Background</p> <p>Rab GTPases function as modulators in intracellular transport. Rab5a, a member of the Rab subfamily of small GTPases, is an important regulator of vesicle traffic from the plasma membrane to early endosomes. Recent findings have reported that Rab5a gene was involved in the progression of cancer. In the present study, we investigated the effect of Rab5a on cervical cancer invasion and metastasis and the molecular mechanism underlying the involvement of Rab5a.</p> <p>Methods</p> <p>Rab5a expression was assessed by immunohistochemical analysis on a cervical cancer tissue microarray. RNA interference (RNAi) was performed to knock down the endogenous expression of Rab5a gene in HeLa and SiHa cells. Cell motility was evaluated using invasion assay and wound migration assay <it>in vitro</it>. The expression levels of integrin-associated molecules were detected by Western blot and immunofluorescence.</p> <p>Results</p> <p>We found that Rab5a was expressed at a high level in cervical cancer tissues. Silencing of Rab5a expression significantly decreased cancer cell motility and invasiveness. The down-regulation of integrin-associated focal adhesion signaling molecules was further detected in Rab5a knockdown cells. Meanwhile, active GTP-bound Rac1, Cdc42, and RhoA were also down-regulated, accompanied with the reduction in the number and size of filopodia and lamellipodia.</p> <p>Conclusions</p> <p>Taken together, these data suggest that Rab5a functions in regulating the invasion phenotype, and we propose that this regulation may be via integrin-mediated signaling pathway in cervical cancer cells.</p

A new sesquiterpene lactone and a new aromatic glycoside from Illicium difengpi

AbstractA new sesquiterpene lactone (1) and a new aromatic glycoside (2), together with three known compounds (3–5) were isolated from the stem bark of Illicium difengpi K. I. B et K. I. M. Their structures were determined by spectroscopic methods, including 1D and 2D NMR, HRESIMS, and chemical methods. The absolute configuration of the secondary alcohol in 1 was confirmed by Mosher's method. Compound 2 exhibited significant anti-inflammatory activity with IC50 value of 6.72μmol/L

Anderson Localization and Mobility Edge in Curved Spacetime

We construct a quasiperiodic lattice model in a curved spacetime to explore the crossover concerning both condensed matter and curved spacetime physics. We study the related Anderson localization and find that the model has a clear boundary of localized-extended phase separation, which leads to the mobility edge, i.e., the coexistence of nonergodic localized, critical and extended phases. A novel self-consistent segmentation method is developed to calculate the analytical expression of the critical position of phase separation, and the rich phase diagram is determined by calculating the fractal dimension and scaling index in multifractal analysis.Comment: 17 pages, 4+12 figure