Simultaneous minimal model of homogeneous toric deformation

For a flat family of Du Val singularities, we can take a simultaneous resolution after finite base change. It is an interesting problem to consider this analogy for a flat family of higher dimensional canonical singularities. In this note, we consider an existence of simultaneous terminalization for K. Altmann's homogeneous toric deformation whose central fibre is an affine Gorenstein toric singularity. We obtain examples that there are no simultaneous terminalization even after finite base change and give a sufficient condition for an existence of simultaneous terminalization. Some examples of 4-dimensional flop are obtained as an application.Comment: LaTeX2e, 8 pages with no figures, [email protected]

Role of the plasma-electrode bias and the transverse magnetic field upon H- ion extraction in the negative ion source

Non peer reviewedPublisher PD

Hodge Theory and Algebraic Geometry

Hodge Theory and Algebraic Geometry 2002/10/7-11 Department of Mathematics, Hokkaido University 石井志保子（東工大）Nash problem on arc families for singularities 内藤広嗣　（名大多元） 村上雅亮（京大理）Surfaces with c^2_1= 3 and \kai(O) = 2, which have non-trivial 3-torsion divisors 大野浩二（大阪大）On certain boundedness of fibred Calabi-Yau s threefolds 阿部健（京大理） 春井岳（大阪大）The gonarlity of curves on an elliptic ruled surface 山下剛（東大数理）開多様体のp進etale cohomology と crystalline cohomology 中島幸喜（東京電機大）Theorie de Hodge III pour cohomologies p-adiques 皆川龍博　（東工大）On classification of weakened Fano 3-folds 斉藤夏男（東大数理）Fano threefold in positive characteristic 石井亮（京大工）Variation of the representation moduli of the McKay quiver 前野俊昭（京大理）群のコホモロジーと量子変形 宮岡洋一（東大数理）　次数が低い有理曲線とファノ多様体 池田京司（大阪大）Subvarieties of generic hypersurfaces in a projective toric variety 竹田雄一郎（九大数理）Complexes of hermitian cubes and the Zagier conjecture 臼井三平（大阪大）SL(2)-orbit theorem and log Hodge structures (Joint work with Kazuya Kato) 鈴木香織（東大数理)\rho(X) = 1, f \le 2 のQ-Fano 3-fold Fanoの分

Base manifolds for fibrations of projective irreducible symplectic manifolds

Given a projective irreducible symplectic manifold $M$ of dimension $2n$, a projective manifold $X$ and a surjective holomorphic map $f:M \to X$ with connected fibers of positive dimension, we prove that $X$ is biholomorphic to the projective space of dimension $n$. The proof is obtained by exploiting two geometric structures at general points of $X$: the affine structure arising from the action variables of the Lagrangian fibration $f$ and the structure defined by the variety of minimal rational tangents on the Fano manifold $X$

ALMA Temporal Phase Stability and the Effectiveness of Water Vapor Radiometer

Atacama Large Millimeter/submillimeter Array (ALMA) will be the world largest mm/submm interferometer, and currently the Early Science is ongoing, together with the commissioning and science verification (CSV). Here we present a study of the temporal phase stability of the entire ALMA system from antennas to the correlator. We verified the temporal phase stability of ALMA using data, taken during the last two years of CSV activities. The data consist of integrations on strong point sources (i.e., bright quasars) at various frequency bands, and at various baseline lengths (up to 600 m). From the observations of strong quasars for a long time (from a few tens of minutes, up to an hour), we derived the 2-point Allan Standard Deviation after the atmospheric phase correction using the 183 GHz Water Vapor Radiometer (WVR) installed in each 12 m antenna, and confirmed that the phase stability of all the baselines reached the ALMA specification. Since we applied the WVR phase correction to all the data mentioned above, we also studied the effectiveness of the WVR phase correction at various frequencies, baseline lengths, and weather conditions. The phase stability often improves a factor of 2 - 3 after the correction, and sometimes a factor of 7 improvement can be obtained. However, the corrected data still displays an increasing phase fluctuation as a function of baseline length, suggesting that the dry component (e.g., N2 and O2) in the atmosphere also contributes the phase fluctuation in the data, although the imperfection of the WVR phase correction cannot be ruled out at this moment.Comment: Proc. SPIE 8444-125, in press (7 pages, 4 figures, 1 table

Fibrations on four-folds with trivial canonical bundles

Four-folds with trivial canonical bundles are divided into six classes according to their holonomy group. We consider examples that are fibred by abelian surfaces over the projective plane. We construct such fibrations in five of the six classes, and prove that there is no such fibration in the sixth class. We classify all such fibrations whose generic fibre is the Jacobian of a genus two curve.Comment: 28 page

Probabilistic Fragmentation and Effective Power Law

A simple fragmentation model is introduced and analysed. We show that, under very general conditions, an effective power law for the mass distribution arises with realistic exponent. This exponent has a universal limit, but in practice the effective exponent depends on the detailed breaking mechanism and the initial conditions. This dependence is in good agreement with experimental results of fragmentation.Comment: 4 pages Revtex, 2 figures, zipped and uuencode

Lagrangian fibrations of holomorphic-symplectic varieties of K3^[n]-type

Let X be a compact Kahler holomorphic-symplectic manifold, which is deformation equivalent to the Hilbert scheme of length n subschemes of a K3 surface. Let L be a nef line-bundle on X, such that the 2n-th power of c_1(L) vanishes and c_1(L) is primitive. Assume that the two dimensional subspace H^{2,0}(X) + H^{0,2}(X), of the second cohomology of X with complex coefficients, intersects trivially the integral cohomology. We prove that the linear system of L is base point free and it induces a Lagrangian fibration on X. In particular, the line-bundle L is effective. A determination of the semi-group of effective divisor classes on X follows, when X is projective. For a generic such pair (X,L), not necessarily projective, we show that X is bimeromorphic to a Tate-Shafarevich twist of a moduli space of stable torsion sheaves, each with pure one dimensional support, on a projective K3 surface.Comment: 34 pages. v3: Reference [Mat5] and Remark 1.8 added. Incorporated improvement to the exposition and corrected typos according to the referees suggestions. To appear in the proceedings of the conference Algebraic and Complex Geometry, Hannover 201

Staggered magnetism in LiV2_2O4_4 at low temperatures probed by the muon Knight shift

We report on the muon Knight shift measurement in single crystals of LiV2O4. Contrary to what is anticipated for the heavy-fermion state based on the Kondo mechanism, the presence of inhomogeneous local magnetic moments is demonstrated by the broad distribution of the Knight shift at temperatures well below the presumed "Kondo temperature" ($T^*\simeq 30$ K). Moreover, a significant fraction ($\simeq10$ %) of the specimen gives rise to a second component which is virtually non-magnetic. These observations strongly suggest that the anomalous properties of LiV2O4 originates from frustration of local magnetic moments.Comment: 11 pages, 5 figures, sbmitted to J. Phys.: Cond. Mat