3,051 research outputs found
Topological magnons in one-dimensional ferromagnetic Su-Schrieffer-Heeger model with anisotropic interaction
Topological magnons in a one-dimensional (1D) ferromagnetic (FM)
Su-Schrieffer-Heeger (SSH) model with anisotropic exchange interactions are
investigated. Apart from the inter-cellular isotropic Heisenberg interaction,
the intercellular anisotropic exchange interactions, i.e. Dzyaloshinskii-Moriya
interaction (DMI) and pseudo-dipolar interaction (PDI), also can induce the
emergence of the non-trivial phase with two degenerate in-gap edge states
separately localized at the two ends of the 1D chain, while the intracellular
interactions instead unfavors the topological phase. The interplay among them
has synergistic effects on the topological phase transition, very different
from that in the two-dimensional (2D) ferromagnet. These results demonstrate
that the 1D magnons possess rich topological phase diagrams distinctly
different from the electronic version of the SSH model and even the 2D magnons.
Due to the lower dimensional structural characteristics of this 1D topological
magnonic system, the magnonic crystals can be constructed from bottom to top,
which has important potential applications in the design of novel magnonic
devices.Comment: 22 pages, 11 figure
Cactus pear: a natural product in cancer chemoprevention
BACKGROUND: Cancer chemoprevention is a new approach in cancer prevention, in which chemical agents are used to prevent cancer in normal and/or high-risk populations. Although chemoprevention has shown promise in some epithelial cancers, currently available preventive agents are limited and the agents are costly, generally with side effects. Natural products, such as grape seed, green tea, and certain herbs have demonstrated anti-cancer effects. To find a natural product that can be used in chemoprevention of cancer, we tested Arizona cactus fruit solution, the aqueous extracts of cactus pear, for its anti-cancer effects in cultured cells and in an animal model. METHOD: Aqueous extracts of cactus pear were used to treat immortalized ovarian and cervical epithelial cells, as well as ovarian, cervical, and bladder cancer cells. Aqueous extracts of cactus pear were used at six concentrations (0, 0.5, 1, 5, 10 or 25%) to treat cells for 1, 3, or 5 days. Growth inhibition, apoptosis induction, and cell cycle changes were analyzed in the cultured cells; the suppression of tumor growth in nude mice was evaluated and compared with the effect of a synthetic retinoid N-(4-hydroxyphernyl) retinamide (4-HPR), which is currently used as a chemoprevention agent. Immunohistochemistry staining of tissue samples from animal tumors was performed to examine the gene expression. RESULTS: Cells exposed to cactus pear extracts had a significant increase in apoptosis and growth inhibition in both immortalized epithelial cells and cancer cells in a dose- and time-dependent manner. It also affected cell cycle of cancer cells by increasing G1 and decreasing G2 and S phases. Both 4-HPR and cactus pear extracts significantly suppressed tumor growth in nude mice, increased annexin IV expression, and decreased VEGF expression. CONCLUSION: Arizona cactus pear extracts effectively inhibited cell growth in several different immortalized and cancer cell cultures, suppressed tumor growth in nude mice, and modulated expression of tumor-related genes. These effects were comparable with those caused by a synthetic retinoid currently used in chemoprevention trials. The mechanism of the anti-cancer effects of cactus pear extracts needs to be further studied
Antiviral Therapy and Outcomes of Patients with Pneumonia Caused by Influenza A Pandemic (H1N1) Virus
There is limited data on the clinical outcome of patients with pandemic H1N1 (pH1N1) pneumonia who received oseltamivir treatment, especially when the treatment was administered more than 48 hours after symptom onset.During the pandemic in 2009, a cohort of pH1N1 influenza pneumonia was built in China, and their clinical information was collected systematically, and analyzed with Cox models.<200, oseltamivir administration reduced the mortality risk by 92.1%, 88% and 83.5%, respectively. Higher doses of oseltamivir (>3.8 mg/kg/d) did not improve clinical outcome (mortality, higher dose 2.5% vs standard dose 2.8%, p>0.05).<200
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