The Role of miR-526b in COX-2 Mediated Human Breast Cancer Progression and Induction of Stem-Like Phenotype Via EP4 Receptor Signaling

Our laboratory previously established that aberrant expression of cyclo-oxygenase (COX)-2 promotes breast cancer progression and metastasis via multiple mechanisms, including stem-like cell (SLC) induction, owing to activation of the prostaglandin E2 receptor EP4. COX-2 expression was linked to up-regulation of miRNA-526b. We hypothesized that miR-526b is regulated by EP4 activity, and that miR-526b supports breast cancer progression and induction of SLCs. Using stably miR-526b transfected MCF-7 and SKBR-3 cells in functional assays, including tumorsphere formation in vitro and lung colony formation in vivo, we observed enhanced migration, invasion, proliferation, tumorsphere formation, and in vivo tumorigenecity compared to controls. EP4 receptor activation and inhibition resulted in respective increases or decreases in miR-526b expression in PKA and PI3K-AKT dependent manners. We conclude that miR-526b promotes breast cancer progression and SLC induction, is up-regulated by EP4, and holds promise as a biomarker for monitoring and personalizing breast cancer treatment

Bosonic molecules in rotating traps

We present a variational many-body wave function for repelling bosons in rotating traps, focusing on rotational frequencies that do not lead to restriction to the lowest Landau level. This wave function incorporates correlations beyond the Gross-Pitaevskii (GP) mean field approximation, and it describes rotating boson molecules (RBMs) made of localized bosons that form polygonal-ring-like crystalline patterns in their intrinsic frame of reference. The RBMs exhibit characteristic periodic dependencies of the ground-state angular momenta on the number of bosons in the polygonal rings. For small numbers of neutral bosons, the RBM ground-state energies are found to be always lower than those of the corresponding GP solutions, in particular in the regime of GP vortex formation.Comment: To appear in Phys. Rev. Lett. LATEX, 5 pages with 5 figures. For related papers, see http://www.prism.gatech.edu/~ph274cy

Nonuniversal transmission phase lapses through a quantum dot: An exact-diagonalization of the many-body transport problem

Systematic trends of nonuniversal behavior of electron transmission phases through a quantum dot, with no phase lapse for the transition N=1 -> N=2 and a lapse of pi for the N=2 -> N=3 transition, are predicted, in agreement with experiments, from many-body transport calculations involving exact diagonalization of the dot Hamiltonian. The results favor shape anisotropy of the dot and strong e-e repulsion with consequent electron localization, showing dependence on spin configurations and the participation of excited doorway transmission channels.Comment: Published version. REVTEX4. 4 pages with 3 color figures. For related papers, see http://www.prism.gatech.edu/~ph274cy

Phase-Controlled Force and Magnetization Oscillations in Superconducting Ballistic Nanowires

The emergence of superconductivity-induced phase-controlled forces in the (0.01-0.1) nN range, and of magnetization oscillations, in nanowire junctions, is discussed. A giant magnetic response to applied weak magnetic fields, is predicted in the ballistic Josephson junction formed by a superconducting tip and a surface, bridged by a normal metal nanowire where Andreev states form.Comment: 5 pages, 3 figure

Premelting of Thin Wires

Recent work has raised considerable interest on the nature of thin metallic wires. We have investigated the melting behavior of thin cylindrical Pb wires with the axis along a (110) direction, using molecular dynamics and a well-tested many-body potential. We find that---in analogy with cluster melting---the melting temperature $T_m (R)$ of a wire with radius $R$ is lower than that of a bulk solid, $T_m^b$, by $T_m (R) = T_m^b -c/R$. Surface melting effects, with formation of a thin skin of highly diffusive atoms at the wire surface, is observed. The diffusivity is lower where the wire surface has a flat, local (111) orientation, and higher at (110) and (100) rounded areas. The possible relevance to recent results on non-rupturing thin necks between an STM tip and a warm surface is addressed.Comment: 10 pages, 4 postscript figures are appended, RevTeX, SISSA Ref. 131/94/CM/S

Estimation of Fiber Orientations Using Neighborhood Information

Data from diffusion magnetic resonance imaging (dMRI) can be used to reconstruct fiber tracts, for example, in muscle and white matter. Estimation of fiber orientations (FOs) is a crucial step in the reconstruction process and these estimates can be corrupted by noise. In this paper, a new method called Fiber Orientation Reconstruction using Neighborhood Information (FORNI) is described and shown to reduce the effects of noise and improve FO estimation performance by incorporating spatial consistency. FORNI uses a fixed tensor basis to model the diffusion weighted signals, which has the advantage of providing an explicit relationship between the basis vectors and the FOs. FO spatial coherence is encouraged using weighted l1-norm regularization terms, which contain the interaction of directional information between neighbor voxels. Data fidelity is encouraged using a squared error between the observed and reconstructed diffusion weighted signals. After appropriate weighting of these competing objectives, the resulting objective function is minimized using a block coordinate descent algorithm, and a straightforward parallelization strategy is used to speed up processing. Experiments were performed on a digital crossing phantom, ex vivo tongue dMRI data, and in vivo brain dMRI data for both qualitative and quantitative evaluation. The results demonstrate that FORNI improves the quality of FO estimation over other state of the art algorithms.Comment: Journal paper accepted in Medical Image Analysis. 35 pages and 16 figure

Energetics, forces, and quantized conductance in jellium modeled metallic nanowires

Energetics and quantized conductance in jellium modeled nanowires are investigated using the local density functional based shell correction method, extending our previous study of uniform in shape wires [C. Yannouleas and U. Landman, J. Phys. Chem. B 101, 5780 (1997)] to wires containing a variable shaped constricted region. The energetics of the wire (sodium) as a function of the length of the volume conserving, adiabatically shaped constriction leads to formation of self selecting magic wire configurations. The variations in the energy result in oscillations in the force required to elongate the wire and are directly correlated with the stepwise variations of the conductance of the nanowire in units of 2e^2/h. The oscillatory patterns in the energetics and forces, and the correlated stepwise variation in the conductance are shown, numerically and through a semiclassical analysis, to be dominated by the quantized spectrum of the transverse states at the narrowmost part of the constriction in the wire.Comment: Latex/Revtex, 11 pages with 5 Postscript figure

Dislocation Emission around Nanoindentations on a (001) fcc Metal Surface Studied by STM and Atomistic Simulations

We present a combined study by Scanning Tunneling Microscopy and atomistic simulations of the emission of dissociated dislocation loops by nanoindentation on a (001) fcc surface. The latter consist of two stacking-fault ribbons bounded by Shockley partials and a stair-rod dislocation. These dissociated loops, which intersect the surface, are shown to originate from loops of interstitial character emitted along the directions and are usually located at hundreds of angstroms away from the indentation point. Simulations reproduce the nucleation and glide of these dislocation loops.Comment: 10 pages, 4 figure

Origin of anomalously long interatomic distances in suspended gold chains

The discovery of long bonds in gold atom chains has represented a challenge for physical interpretation. In fact, interatomic distances frequently attain 3.0-3.6 A values and, distances as large as 5.0 A may be seldom observed. Here, we studied gold chains by transmission electron microscopy and performed theoretical calculations using cluster ab initio density functional formalism. We show that the insertion of two carbon atoms is required to account for the longest bonds, while distances above 3 A may be due to a mixture of clean and one C atom contaminated bonds.Comment: 4 pages, 4 Postscript figures, to be published in Physical Review Letter