Holographic Superconductor for a Lifshitz fixed point

We consider the gravity dual of strongly coupled system at a Lifshitz-fixed point and finite temperature, which was constructed in a recent work arXiv:0909.0263. We construct an Abelian Higgs model in that background and calculate condensation and conductivity using holographic techniques. We find that condensation happens and DC conductivity blows up when temperature turns below a critical value.Comment: 14 pages, 4 figures, v4: improved version, references adde

Impact of Metronomic UFT/Cyclophosphamide Chemotherapy and Antiangiogenic Drug Assessed in a New Preclinical Model of Locally Advanced Orthotopic Hepatocellular Carcinoma

AbstractHepatocellular carcinoma (HCC) is an intrinsically chemotherapy refractory malignancy. Development of effective therapeutic regimens would be facilitated by improved preclinical HCC models. Currently, most models consist of subcutaneous human tumor transplants in immunodeficient mice; however, these do not reproduce the extensive liver disease associated with HCC or metastasize. To address this deficiency, we developed an orthotopic model. Human HCC cells were transfected with the gene encoding secretable β-subunit human choriogonadotropin (β-hCG), which was used as a surrogate marker of tumor burden. The HCC cells were implanted into the left liver lobe of severe combined immunodeficient (SCID) mice, after which the efficacy of different therapies was evaluated on established, but liver-confined human Hep3B cell line HCC. Treatments included sorafenib or metronomic chemotherapy using cyclophosphamide (CTX), UFT, an oral 5-fluorouracil prodrug, or doxorubicin either alone or in various combinations, with or without an antiangiogenic agent, DC101, an anti-vascular endothelial growth factor receptor-2 antibody. Sorafenib inhibited tumor growth in a dose-dependent manner but caused severe weight loss in SCID mice, thus necessitating use of DC101 in subsequent experiments. Although less toxicity was observed using either single or doublet metronomic chemotherapy without any added antiangiogenic agent, none, provided survival benefit. In contrast, significantly improved overall survival was observed using various combinations of metronomic chemotherapy regimens such as UFT + CTX with DC101. In conclusion, using this model of liver-confined but advanced HCC suggests that the efficacy of a targeted antiangiogenic drug or metronomic chemotherapy can be mutually enhanced by concurrent combination treatment

Defective autophagy in chondrocytes with Kashin-Beck disease but higher than osteoarthritis

SummaryObjectiveThis study was undertaken to monitor autophagy in chondrocytes with Kashin-Beck disease (KBD) and osteoarthritis (OA).MethodsThe identification and quantification of autophagy were morphologically visualized by transmission electron microscopy (TEM), together with immunohistochemical localization of Beclin1 and LC3 in cartilage, and immunoblotting of cellular Beclin1, LC3 and p62/SQSTM1 in the normal, KBD and OA groups. Sequentially, regulated-autophagy genes (ATG) were analyzed by IPA software and validated by quantitative real-time polymerase chain reaction (qRT-PCR). Cytotoxicity of cell death was measured by fluorescence detection and flow cytometry (FCM). The co-localization and measurement of autophagy and mitochondria/reactive oxygen species (ROS) were carried out.ResultsKBD chondrocytes exhibited a variety of abnormal cellular contents including nuclei, mitochondrial, glycogen deposits and microfilaments, and OA chondrocytes mainly presented swelled endocytoplasmic reticulum (ER). Beclin1 and LC3 were reduced both in KBD and OA compared with normal controls; however, the two proteins and p62 in KBD were in a higher level than OA. Simultaneously, KBD chondrocytes showed 45 genes that were different from normal controls and 92 genes different from OA, whose functions were mainly involved in cell morphology, cellular functions, cell death and survival. Autophagy was negatively correlated with apoptosis in the three kinds of chondrocytes, and the rates decreased when autophagy was induced by rapamycin. Similarly, KBD and OA chondrocytes showed lower autophagy and higher ROS production compared with the normal chondrocytes.ConclusionAutophagy was defective in KBD chondrocytes, but it was higher than in OA. The insufficient autophagy may be associated with apoptosis and mitochondrial change in the pathogenesis of KBD and OA

Theoretical study on pp --> p n pi+ reaction at medium energies

The $pp\to p n \pi^+$ reaction is a channel with the largest total cross section for pp collision in COSY/CSR energy region. In this work, we investigate individual contributions from various $N^*$ and $\Delta^{*}$ resonances with mass up to about 2 GeV for the $pp\to p n \pi^+$ reaction. We extend a resonance model, which can reproduce the observed total cross section quite well, to give theoretical predictions of various differential cross sections for the present reaction at $T_p=2.88$ GeV. It could serve as a reference for identifying new physics in the future experiments at HIRFL-CSR.Comment: talk at STORI08, Sept. 2008, Lanzhou, Chin

Characterization of Rock Mechanical Properties Using Lab Tests and Numerical Interpretation Model of Well Logs

The tight gas reservoir in the fifth member of the Xujiahe formation contains heterogeneous interlayers of sandstone and shale that are low in both porosity and permeability. Elastic characteristics of sandstone and shale are analyzed in this study based on petrophysics tests. The tests indicate that sandstone and mudstone samples have different stress-strain relationships. The rock tends to exhibit elastic-plastic deformation. The compressive strength correlates with confinement pressure and elastic modulus. The results based on thin-bed log interpretation match dynamic Young’s modulus and Poisson’s ratio predicted by theory. The compressive strength is calculated from density, elastic impedance, and clay contents. The tensile strength is calibrated using compressive strength. Shear strength is calculated with an empirical formula. Finally, log interpretation of rock mechanical properties is performed on the fifth member of the Xujiahe formation. Natural fractures in downhole cores and rock microscopic failure in the samples in the cross section demonstrate that tensile fractures were primarily observed in sandstone, and shear fractures can be observed in both mudstone and sandstone. Based on different elasticity and plasticity of different rocks, as well as the characteristics of natural fractures, a fracture propagation model was built

Fabrication and superconductivity of NaxTaS2 crystals

In this paper we report the growth and superconductivity of $Na_xTaS_2$ crystals. The structural data deduced from X-ray diffraction pattern shows that the sample has the same structure as $2H-TaS_2$. A series of crystals with different superconducting transition temperatures ($T_c$) ranging from 2.5 K to 4.4 K were obtained. It is found that the $T_c$ rises with the increase of $Na$ content determined by Energy-Dispersive x-ray microanalysis(EDX) of Scanning Electron Microscope (SEM) on these crystals. Compared with the resistivity curve of un-intercalated sample $2H-TaS_2$ ($T_c$ = 0.8 K, $T_{CDW} \approx$ 70 K), no signal of charge density wave (CDW) was observed in samples $Na_{0.1}TaS_2$ and $Na_{0.05}TaS_2$. However, in some samples with lower $T_c$, the CDW appears again at about 65 K. Comparison between the anisotropic resistivity indicates that the anisotropy becomes smaller in samples with more $Na$ intercalation (albeit a weak semiconducting behavior along c-axis) and thus higher $T_c$. It is thus concluded that there is a competition between the superconductivity and the CDW. With the increase of sodium content, the rise of $T_c$ in $Na_xTaS_2$ is caused mainly by the suppression to the CDW in $2H-TaS_2$, and the conventional rigid band model for layered dichalcogenide may be inadequate to explain the changes induced by the slight intercalation of sodium in $2H-TaS_2$.Comment: 8 pages, 13 figures, To appear in Physical Review

Lattice Boltzmann for Binary Fluids with Suspended Colloids

A new description of the binary fluid problem via the lattice Boltzmann method is presented which highlights the use of the moments in constructing two equilibrium distribution functions. This offers a number of benefits, including better isotropy, and a more natural route to the inclusion of multiple relaxation times for the binary fluid problem. In addition, the implementation of solid colloidal particles suspended in the binary mixture is addressed, which extends the solid-fluid boundary conditions for mass and momentum to include a single conserved compositional order parameter. A number of simple benchmark problems involving a single particle at or near a fluid-fluid interface are undertaken and show good agreement with available theoretical or numerical results.Comment: 10 pages, 4 figures, ICMMES 200

Contacts between the endoplasmic reticulum and other membranes in neurons

The cytoplasm of eukaryotic cells is compartmentalized by intracellular membranes that define subcellular organelles. One of these organelles, the endoplasmic reticulum, forms a continuous network of tubules and cisternae that extends throughout all cell compartments, including neuronal dendrites and axons. This network communicates with most other organelles by vesicular transport, and also by contacts that do not lead to fusion but allow cross-talk between adjacent bilayers. Though these membrane contacts have previously been observed in neurons, their distribution and abundance has not been systematically analyzed. Here, we have carried out such analysis. Our studies reveal new aspects of the internal structure of neurons and provide a critical complement to information about interorganelle communication emerging from functional and biochemical studies