The C. Elegans ROR receptor tyrosine kinase, CAM-1, non-autonomously inhibits the Wnt pathway

Inhibitors of Wnt signaling promote normal development and prevent cancer by restraining when and where the Wnt pathway is activated. ROR proteins, a class of Wnt-binding receptor tyrosine kinases, inhibit Wnt signaling by an unknown mechanism. To clarify how RORs inhibit the Wnt pathway, we examined the relationship between Wnts and the sole C. elegans ROR homolog, cam-1, during C. elegans vulval development, a Wnt-regulated process. We found that loss and overexpression of cam-1 causes reciprocal defects in Wnt-mediated cell-fate specification. Our molecular and genetic analyses revealed that the CAM-1 extracellular domain (ECD) is sufficient to non-autonomously antagonize multiple Wnts, suggesting that the CAM-1/ROR ECD sequesters Wnts. A sequestration model is supported by our findings that the CAM-1 ECD binds to several Wnts in vitro. These results demonstrate how ROR proteins help to refine the spatial pattern of Wnt activity in a complex multicellular environment

Generarized Cubic Model for BaTiO3_3-like Ferroelectric Substance

We propose an order-disorder type microscopic model for BaTiO$_3$-like Ferroelectric Substance. Our model has three phase transitions and four phases. The symmetry and directions of the polarizations of the ordered phases agree with the experimental results of BaTiO$_3$. The intermediate phases in our model are known as an incompletely ordered phase, which appears in a generalized clock model.Comment: 6 pages, 4figure

Non-equilibrium spin accumulation in ferromagnetic single-electron transistors

We study transport in ferromagnetic single-electron transistors. The non- equilibrium spin accumulation on the island caused by a finite current through the system is described by a generalized theory of the Coulomb blockade. It enhances the tunnel magnetoresistance and has a drastic effect on the time- dependent transport properties. A transient decay of the spin accumulation may reverse the electric current on time scales of the order of the spin-flip relaxation time. This can be used as an experimental signature of the non- equilibrium spin accumulation.Comment: 9 postscript figures, to appear in The European Physical Journal

Magneto-optical properties of multilayer graphenes

The magneto-optical absorption properties of graphene multilayers are theoretically studied. It is shown that the spectrum can be decomposed into sub-components effectively identical to the monolayer or bilayer graphene, allowing us to understand the spectrum systematically as a function of the layer number. Odd-layered graphenes always exhibit absorption peaks which shifts in proportion to sqrt(B), with B being the magnetic field, due to the existence of an effective monolayer-like subband. We propose a possibility of observing the monolayer-like spectrum even in a mixture of multilayer graphene films with various layers numbers.Comment: 9 pages, 7 figure

Decoupling of the ϵ\epsilon-scalar mass in softly broken supersymmetry

It has been shown recently that the introduction of an unphysical $\epsilon$-scalar mass $\tilde{m}$ is necessary for the proper renormalization of softly broken supersymmetric theories by dimensional reduction (\drbar). In these theories, both the two-loop $\beta$-functions of the scalar masses and their one-loop finite corrections depend on $\tilde{m}^2$. We find, however, that the dependence on $\tilde{m}^2$ can be completely removed by slightly modifying the \drbar renormalization scheme. We also show that previous \drbar calculations of one-loop corrections in supersymmetry which ignored the $\tilde{m}^2$ contribution correspond to using this modified scheme.Comment: 7 pages, LTH-336, NUB-3094-94TH, KEK-TH-40

Three-dimensional Mapping of CDM Substructure at Submillimeter Wavelengths

The cold dark matter (CDM) structure formation model predicts that about 5-10 percent of a typical galactic halo of mass \sim 10^{12} \ms is in substructures with masses \lesssim 10^8 \ms. To directly detect such substructures, we propose to observe dust continuum emission from a strongly lensed QSO-host galaxy using a large submillimeter interferometer array with a high angular resolution of $\sim 0.01$arcsec such as the planned Atacama Large Submillimeter Array (ALMA). To assess their observational feasibility, we numerically simulate millilensing of an extended circular source by a CDM substructure modeled as a tidally truncated singular isothermal sphere (SIS) embedded in a typical QSO-galaxy lens system, B1422+231, modeled as a singular isothermal ellipsoid (SIE) with an external constant shear and a constant convergence. Assuming an angular resolution of 0.01arcsec, we find that the angular positions of \sim 10^8 \ms substructures at several kpc from the center of the macrolens halo can be directly measured if the size of the dust continuum emission region and the gradient of the surface brightness at the position of the perturber are sufficiently large. From the astrometric shift on a scale of a few times $10~$mas of an image perturbed by a subhalo with respect to an unperturbed macrolensed image, we can break the degeneracy between subhalo mass and distance provided that macrolensing parameters are determined from positions and fluxes of multiple images.Comment: 7 pages, 7 EPS files. An assessment of our assumption of constancy in shear and convergence has been included. Version accepted for publication in Ap

The ASCA X-ray spectrum of the powerful radio galaxy 3C109

We report the results from an ASCA X-ray observation of the powerful Broad Line Radio Galaxy, 3C109. The ASCA spectra confirm our earlier ROSAT detection of intrinsic X-ray absorption associated with the source. The absorbing material obscures a central engine of quasar-like luminosity. The luminosity is variable, having dropped by a factor of two since the ROSAT observations 4 years before. The ASCA data also provide evidence for a broad iron emission line from the source, with an intrinsic FWHM of ~ 120,000 km/s. Interpreting the line as fluorescent emission from the inner parts of an accretion disk, we can constrain the inclination of the disk to be $> 35$ degree, and the inner radius of the disk to be $< 70$ Schwarzschild radii. Our results support unified schemes for active galaxies, and demonstrate a remarkable similarity between the X-ray properties of this powerful radio source, and those of lower luminosity, Seyfert 1 galaxies.Comment: MNRAS in press. 7 pages, 5 figures in MNRAS LaTex styl

C. elegans BED domain transcription factor BED-3 controls lineage-specific cell proliferation during organogenesis

The control of cell division is critical to organogenesis, but how this control is achieved is not fully understood. We found that mutations in bed-3, encoding a BED Zn-finger domain transcription factor, confer a phenotype where a specific set of cell divisions during vulval organogenesis is lost. Unlike general cell cycle regulators in Caenorhabditis elegans, the function of bed-3 is restricted to specific lineages. Transcriptional reporters suggest that bed-3 is expressed in a limited number of cell types including vulval cells whose divisions are affected in bed-3 mutants. A bed-3 mutation also affects the expression pattern of the cdh-3 cadherin gene in the vulva. The phenotype of bed-3 mutants is similar to the phenotype caused by mutations in cog-1 (Nkx6), a component of a gene regulatory network controlling cell type specific gene expression in the vulval lineage. These results suggest that bed-3 is a key component linking the gene regulatory network controlling cell-type specification to control of cell division during vulval organogenesis