Kinematic dynamo action in a sphere: Effects of periodic time-dependent flows on solutions with axial dipole symmetry

Choosing a simple class of flows, with characteristics that may be present in the Earth's core, we study the ability to generate a magnetic field when the flow is permitted to oscillate periodically in time. The flow characteristics are parameterised by D, representing a differential rotation, M, a meridional circulation, and C, a component characterising convective rolls. Dynamo action is sensitive to these flow parameters and fails spectacularly for much of the parameter space where magnetic flux is concentrated into small regions. Oscillations of the flow are introduced by varying the flow parameters in time, defining a closed orbit in the space (D,M). Time-dependence appears to smooth out flux concentrations, often enhancing dynamo action. Dynamo action can be impaired, however, when flux concentrations of opposite signs occur close together as smoothing destroys the flux by cancellation. It is possible to produce geomagnetic-type reversals by making the orbit stray into a region where the steady flows generate oscillatory fields. In this case, however, dynamo action was not found to be enhanced by the time-dependence. A novel approach is taken to solving the time-dependent eigenvalue problem, where by combining Floquet theory with a matrix-free Krylov-subspace method we avoid large memory requirements for storing the matrix required by the standard approach.Comment: 22 pages, 12 figures. Geophys. Astrophys. Fluid Dynam., as accepted (2004

The splice variant Ehm2/1 in breast cancer MCF-7 cells interacted with β--catenin and increased its localization to plasma membrane

Ehm2, which belongs to the FERM superfamily, is a metastasis-associated protein. However, its function in cancer metastasis and the associated molecular mechanism is not definitely clear. Alternative splicing is an important biological step during mRNA processing and has been reported to be related with many diseases including cancers. Ehm2 has two transcript variants. Transcript variant 1(Ehm2/1) encodes isoform 1 of 518 amino acids, while transcript variant 2(Ehm2/2) encodes isoform 2 of 913 amino acids. In this study, we found that Ehm2/1 was the main transcript variant in the MCF-7 breast cancer cell line. Forced expression of Ehm2/1 upregulated the total protein amount but had no effect on the mRNA levels of β-catenin. The increased β-catenin was found to be dominantly located at the cell membrane. Meanwhile, knockdown of Ehm2/1 in MCF-7 cells decreased the total protein amount but not the mRNA levels of β-catenin. Further results showed that Ehm2/1 interacted with β-catenin and colocalized with it at the cell membrane. E-cadherin, a partner of β-catenin in cadherin-catenin complexes, was also upregulated by the overexpression of Ehm2/1 and also colocalized with it at the cell membrane. Meanwhile, overexpression of Ehm2/1 inhibited the migration ability of MCF-7 cells. These results suggested that Ehm2/1 may render β-catenin at the cell membrane by interacting with β-catenin and E-cadherin

Collective Dipole Oscillation of a Spin-Orbit Coupled Bose-Einstein Condensate

We present an experimental study of the collective dipole oscillation of a spin-orbit coupled Bose-Einstein condensate in a harmonic trap. Dynamics of the center-of-mass dipole oscillation is studied in a broad parameter region, as a function of spin-orbit coupling parameters as well as oscillation amplitude. Anharmonic properties beyond effective-mass approximation are revealed, such as amplitude-dependent frequency and finite oscillation frequency at place with divergent effective mass. These anharmonic behaviors agree quantitatively with variational wave-function calculations. Moreover, we experimentally demonstrate a unique feature of spin-orbit coupled system predicted by a sum-rule approach, stating that spin polarization susceptibility--a static physical quantity--can be measured via dynamics of dipole oscillation. The divergence of polarization susceptibility is observed at the quantum phase transition that separates magnetic nonzero-momentum condensate from nonmagnetic zero-momentum phase. The good agreement between the experimental and theoretical results provides a bench mark for recently developed theoretical approaches.Comment: 5 pages, 4 figures, 0 tabl

The association between S100A13 and HMGA1 in the modulation of thyroid cancer proliferation and invasion

Additional file 5: Figure S3. Lentivirus-mediated S100A13 knockdown was utilized to detect the effect on migration capability with scratch-wound assays in TPC1 cell

Thermally driven spin injection from a ferromagnet into a non-magnetic metal

Creating, manipulating and detecting spin polarized carriers are the key elements of spin based electronics. Most practical devices use a perpendicular geometry in which the spin currents, describing the transport of spin angular momentum, are accompanied by charge currents. In recent years, new sources of pure spin currents, i.e., without charge currents, have been demonstrated and applied. In this paper, we demonstrate a conceptually new source of pure spin current driven by the flow of heat across a ferromagnetic/non-magnetic metal (FM/NM) interface. This spin current is generated because the Seebeck coefficient, which describes the generation of a voltage as a result of a temperature gradient, is spin dependent in a ferromagnet. For a detailed study of this new source of spins, it is measured in a non-local lateral geometry. We developed a 3D model that describes the heat, charge and spin transport in this geometry which allows us to quantify this process. We obtain a spin Seebeck coefficient for Permalloy of -3.8 microvolt/Kelvin demonstrating that thermally driven spin injection is a feasible alternative for electrical spin injection in, for example, spin transfer torque experiments

uSPIO-based Nanocarrier for Pretargeted, PET-MR Image-Guided Delivery

Ultrasmall superparamagnetic iron-oxide nanoparticles (uSPIO) are an attractive platform for development of smart contrast agents for MR imaging. A hydrophilic ligand with high affinity towards the surface of uSPIO core renders hydrophobic uSPIO water-soluble, biocompatible, and highly stable in physiological conditions. A small overall hydrodynamic diameter ensures optimal pharmacokinetics, tumor delivery profile and of particular interest, the enhanced T1 MR contrast. In this study, for the first time, we synthesized a ligand with facile approach that fulfills the as-proposed properties and provides multiple reactive groups for further modifications. Structural and molecular size analysis on the resultant uSPIO-ligand construct confirmed size uniformity and small hydrodynamic diameter of the construct. Its r1 relaxivity has been tested on a 7 Tesla MR Instrument and is comparable to clinically available T1 gadolinium-based contrast agent GBCA (1 mM-1s-1 vs 3 mM-1s-1), respectively. In vivo injection resulted in significant decrease in tumor T1 (15%) within 1 hour of injection and complete signal recovery after 4 hours. Good relaxation and delivery properties and the presence of multiple surface reactive groups can facilitate application of the developed uSPIO, as a universal MRI-compatible nanocarrier platform. HER2(+) metastatic breast cancer (mBC) is one of the most aggressive and lethal cancer type among female. Targeted therapeutic approaches such as trastuzumab and antibody-drug conjugates (ADC) lack long-term efficacy against HER2(+) mBC or can cause severe systematic toxicity due to off-target effects. A Pretargeting delivery platform can minimize toxicity and increases therapeutic localization by separating the single delivery step into a pretargeting step of biomarker followed by the therapeutic delivery step. We have successfully developed a click-chemistry based pretargeting platform for HER2(+) BC with PET-MR image guidance. Trastuzumab and newly developed uSPIO carrier are selected as pretargeting and delivery component, respectively. Confocal imaging confirmed an enhanced internalization associated with pretargeting strategy. An enhanced tumor accumulation as well as the tumor to organ accumulation ratio at up to 24hr post uSPIO injection was observed in pretargeted mice. 40% local T1 decrease in pretargeted tumors was observed within 4hr, and an overall of 15% T1 drop retained for 24hr post uSPIO injection. The prolonged tumor retention and increased tumor to organ accumulation ratio establish a solid foundation for pretargeted delivery approach for in vivo applications