659 research outputs found
The equivariant Todd genus of a complete toric variety, with Danilov condition
We write the equivariant Todd class of a general complete toric variety as an
explicit combination of the orbit closures, the coefficients being analytic
functions on the Lie algebra of the torus which satisfy Danilov's requirement
Local Euler-Maclaurin formula for polytopes
We give a local Euler-Maclaurin formula for rational convex polytopes in a
rational euclidean space . For every affine rational polyhedral cone C in a
rational euclidean space W, we construct a differential operator of infinite
order D(C) on W with constant rational coefficients, which is unchanged when C
is translated by an integral vector. Then for every convex rational polytope P
in a rational euclidean space V and every polynomial function f (x) on V, the
sum of the values of f(x) at the integral points of P is equal to the sum, for
all faces F of P, of the integral over F of the function D(N(F)).f, where we
denote by N(F) the normal cone to P along F.Comment: Revised version (July 2006) has some changes of notation and
references adde
Cohomological Partition Functions for a Class of Bosonic Theories
We argue, that for a general class of nontrivial bosonic theories the path
integral can be related to an equivariant generalization of conventional
characteristic classes.Comment: 9 pages; standard LATEX fil
Lambda theories of effective lambda models
A longstanding open problem is whether there exists a non-syntactical model
of untyped lambda-calculus whose theory is exactly the least equational
lambda-theory (=Lb). In this paper we make use of the Visser topology for
investigating the more general question of whether the equational (resp. order)
theory of a non syntactical model M, say Eq(M) (resp. Ord(M)) can be
recursively enumerable (= r.e. below). We conjecture that no such model exists
and prove the conjecture for several large classes of models. In particular we
introduce a notion of effective lambda-model and show that for all effective
models M, Eq(M) is different from Lb, and Ord(M) is not r.e. If moreover M
belongs to the stable or strongly stable semantics, then Eq(M) is not r.e.
Concerning Scott's continuous semantics we explore the class of (all) graph
models, show that it satisfies Lowenheim Skolem theorem, that there exists a
minimum order/equational graph theory, and that both are the order/equ theories
of an effective graph model. We deduce that no graph model can have an r.e.
order theory, and also show that for some large subclasses, the same is true
for Eq(M).Comment: 15 pages, accepted CSL'0
Effective lambda-models vs recursively enumerable lambda-theories
A longstanding open problem is whether there exists a non syntactical model
of the untyped lambda-calculus whose theory is exactly the least lambda-theory
(l-beta). In this paper we investigate the more general question of whether the
equational/order theory of a model of the (untyped) lambda-calculus can be
recursively enumerable (r.e. for brevity). We introduce a notion of effective
model of lambda-calculus calculus, which covers in particular all the models
individually introduced in the literature. We prove that the order theory of an
effective model is never r.e.; from this it follows that its equational theory
cannot be l-beta or l-beta-eta. We then show that no effective model living in
the stable or strongly stable semantics has an r.e. equational theory.
Concerning Scott's semantics, we investigate the class of graph models and
prove that no order theory of a graph model can be r.e., and that there exists
an effective graph model whose equational/order theory is minimum among all
theories of graph models. Finally, we show that the class of graph models
enjoys a kind of downwards Lowenheim-Skolem theorem.Comment: 34
Equivariant Kaehler Geometry and Localization in the G/G Model
We analyze in detail the equivariant supersymmetry of the model. In
spite of the fact that this supersymmetry does not model the infinitesimal
action of the group of gauge transformations, localization can be established
by standard arguments. The theory localizes onto reducible connections and a
careful evaluation of the fixed point contributions leads to an alternative
derivation of the Verlinde formula for the WZW model. We show that the
supersymmetry of the model can be regarded as an infinite dimensional
realization of Bismut's theory of equivariant Bott-Chern currents on K\"ahler
manifolds, thus providing a convenient cohomological setting for understanding
the Verlinde formula. We also show that the supersymmetry is related to a
non-linear generalization (q-deformation) of the ordinary moment map of
symplectic geometry in which a representation of the Lie algebra of a group
is replaced by a representation of its group algebra with commutator . In the large limit it reduces to the ordinary moment map of
two-dimensional gauge theories.Comment: LaTex file, 40 A4 pages, IC/94/108 and ENSLAPP-L-469/9
In Vitro Impact of Triatomine Salivary Glands Extracts Introduced to Endothelial Cells
Chagas Disease (AKA Trypanosomiasis) is caused by biting/feeding behavior from the arthropod vector Triatoma (subfamily of Reduviidae family), that house the endoparasite Trypanosoma cruzi, which can then be passed to human and mammalian hosts (Schmidt, et al., 2011). Resources are currently being utilized to help minimize the effects and susceptibility of Chagas within endemic areas. Previous research has demonstrated that there are biochemical interactions between specific Triatoma salivary proteins and host cells (Ribeiro, Assumpção, Van Pham, Francischetti, & Reisenman, 2012).This study examined the interactions made from salivary proteins procured from the T. sanguisuga and T. indictiva species with the expression of two glycoproteins, fibronectin (angiogenic) and thrombospondin (antiangiogenic) when exposed to Human Umbilical Vein Endothelial Cells (HUVECs)
On transversally elliptic operators and the quantization of manifolds with -structure
An -structure on a manifold is an endomorphism field
\phi\in\Gamma(M,\End(TM)) such that . Any -structure
determines an almost CR structure E_{1,0}\subset T_\C M given by the
-eigenbundle of . Using a compatible metric and connection
on , we construct an odd first-order differential operator ,
acting on sections of , whose principal symbol is of the
type considered in arXiv:0810.0338. In the special case of a CR-integrable
almost -structure, we show that when is the generalized
Tanaka-Webster connection of Lotta and Pastore, the operator is given by D
= \sqrt{2}(\dbbar+\dbbar^*), where \dbbar is the tangential Cauchy-Riemann
operator.
We then describe two "quantizations" of manifolds with -structure that
reduce to familiar methods in symplectic geometry in the case that is a
compatible almost complex structure, and to the contact quantization defined in
\cite{F4} when comes from a contact metric structure. The first is an
index-theoretic approach involving the operator ; for certain group actions
will be transversally elliptic, and using the results in arXiv:0810.0338,
we can give a Riemann-Roch type formula for its index. The second approach uses
an analogue of the polarized sections of a prequantum line bundle, with a CR
structure playing the role of a complex polarization.Comment: 31 page
How to Integrate a Polynomial over a Simplex
This paper settles the computational complexity of the problem of integrating
a polynomial function f over a rational simplex. We prove that the problem is
NP-hard for arbitrary polynomials via a generalization of a theorem of Motzkin
and Straus. On the other hand, if the polynomial depends only on a fixed number
of variables, while its degree and the dimension of the simplex are allowed to
vary, we prove that integration can be done in polynomial time. As a
consequence, for polynomials of fixed total degree, there is a polynomial time
algorithm as well. We conclude the article with extensions to other polytopes,
discussion of other available methods and experimental results.Comment: Tables added with new experimental results. References adde
Lower dimensional volumes and the Kastler-Kalau-Walze type theorem for Manifolds with Boundary
In this paper, we define lower dimensional volumes of spin manifolds with
boundary. We compute the lower dimensional volume for
5-dimensional and 6-dimensional spin manifolds with boundary and we also get
the Kastler-Kalau-Walze type theorem in this case
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