5,295 research outputs found
Variations of Hodge Structure Considered as an Exterior Differential System: Old and New Results
This paper is a survey of the subject of variations of Hodge structure (VHS)
considered as exterior differential systems (EDS). We review developments over
the last twenty-six years, with an emphasis on some key examples. In the
penultimate section we present some new results on the characteristic
cohomology of a homogeneous Pfaffian system. In the last section we discuss how
the integrability conditions of an EDS affect the expected dimension of an
integral submanifold. The paper ends with some speculation on EDS and Hodge
conjecture for Calabi-Yau manifolds
Extremal degenerations of polarized Hodge structures
We describe a Hodge theoretic approach to the question: In what ways can a
smooth projective variety degenerate?Comment: v.2 (typos corrected), comments welcom
A Novel 2.5D Culture Platform to Investigate the Role of Stiffness Gradients on Adhesion-Independent Cell Migration
Current studies investigating the role of biophysical cues on cell migration focus on the use of culture platforms with static material parameters. However, migrating cells in vivo often encounter spatial variations in extracellular matrix stiffness. To better understand the effects of stiffness gradients on cell migration, we developed a 2.5D cell culture platform where cells are sandwiched between stiff tissue culture plastic and soft alginate hydrogel. Under these conditions, we observed migration of cells from the underlying stiff substrate into the alginate matrix. Observation of migration into alginate in the presence of integrin inhibition as well as qualitative microscopic analyses suggested an adhesion-independent cell migration mode. Observed migration was dependent on alginate matrix stiffness and the RhoA-ROCK-myosin-II pathway; inhibitors specifically targeting ROCK and myosin-II arrested cell migration. Collectively, these results demonstrate the utility of the 2.5D culture platform to advance our understanding of the effects of stiffness gradients and mechanotransductive signaling on adhesion-independent cell migration
Period Mappings and Ampleness of the Hodge line bundle
We discuss progress towards a conjectural Hodge theoretic completion of a
period map. The completion is defined, and we conjecture that it admits the
structure of a compact complex analytic variety. The conjecture is proved when
the image of the period map has dimension 1,2. Assuming the conjecture holds,
we then prove that the augmented Hodge line bundle extends to an ample line
bundle on the completion. In particular, the completion is a projective
algebraic variety that compactifies the image, analogous to the
Satake-Baily-Borel compactification.Comment: 62 pages. v2 significant revision of the initial submission (v1); v3
further improvements and new references adde
Matrix elements and duality for type 2 unitary representations of the Lie superalgebra gl(m|n)
The characteristic identity formalism discussed in our recent articles is
further utilized to derive matrix elements of type 2 unitary irreducible
modules. In particular, we give matrix element formulae for all
gl(m|n) generators, including the non-elementary generators, together with
their phases on finite dimensional type 2 unitary irreducible representations.
Remarkably, we find that the type 2 unitary matrix element equations coincide
with the type 1 unitary matrix element equations for non-vanishing matrix
elements up to a phase.Comment: 24 pages. arXiv admin note: text overlap with arXiv:1311.424
Reduced Wigner coefficients for Lie superalgebra gl(m|n) corresponding to unitary representations and beyond
In this paper fundamental Wigner coefficients are determined algebraically by
considering the eigenvalues of certain generalized Casimir invariants. Here
this method is applied in the context of both type 1 and type 2 unitary
representations of the Lie superalgebra gl(mjn). Extensions to the non-unitary
case are investigated. A symmetry relation between two classes of Wigner
coefficients is given in terms of a ratio of dimensions.Comment: 17 page
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