242 research outputs found
M. Kontsevich's graph complex and the Grothendieck-Teichmueller Lie algebra
We show that the zeroth cohomology of M. Kontsevich's graph complex is
isomorphic to the Grothendieck-Teichmueller Lie algebra grt_1. The map is
explicitly described. This result has applications to deformation quantization
and Duflo theory. We also compute the homotopy derivations of the Gerstenhaber
operad. They are parameterized by grt_1, up to one class (or two, depending on
the definitions). More generally, the homotopy derivations of the (non-unital)
E_n operads may be expressed through the cohomology of a suitable graph
complex. Our methods also give a second proof of a result of H. Furusho,
stating that the pentagon equation for grt_1-elements implies the hexagon
equation
Formality theorems for Hochschild chains in the Lie algebroid setting
In this paper we prove Lie algebroid versions of Tsygan's formality
conjecture for Hochschild chains both in the smooth and holomorphic settings.
In the holomorphic setting our result implies a version of Tsygan's formality
conjecture for Hochschild chains of the structure sheaf of any complex manifold
and in the smooth setting this result allows us to describe quantum traces for
an arbitrary Poisson Lie algebroid. The proofs are based on the use of
Kontsevich's quasi-isomorphism for Hochschild cochains of R[[y_1,...,y_d]],
Shoikhet's quasi-isomorphism for Hochschild chains of R[[y_1,...,y_d]], and
Fedosov's resolutions of the natural analogues of Hochschild (co)chain
complexes associated with a Lie algebroid.Comment: 40 pages, no figure
One-dimensional Chern-Simons theory
We study a one-dimensional toy version of the Chern-Simons theory. We
construct its simplicial version which comprises features of a low-energy
effective gauge theory and of a topological quantum field theory in the sense
of Atiyah.Comment: 37 page
Hypercommutative operad as a homotopy quotient of BV
We give an explicit formula for a quasi-isomorphism between the operads
Hycomm (the homology of the moduli space of stable genus 0 curves) and
BV/ (the homotopy quotient of Batalin-Vilkovisky operad by the
BV-operator). In other words we derive an equivalence of Hycomm-algebras and
BV-algebras enhanced with a homotopy that trivializes the BV-operator.
These formulas are given in terms of the Givental graphs, and are proved in
two different ways. One proof uses the Givental group action, and the other
proof goes through a chain of explicit formulas on resolutions of Hycomm and
BV. The second approach gives, in particular, a homological explanation of the
Givental group action on Hycomm-algebras.Comment: minor corrections added, to appear in Comm.Math.Phy
Formality theorems for Hochschild complexes and their applications
We give a popular introduction to formality theorems for Hochschild complexes
and their applications. We review some of the recent results and prove that the
truncated Hochschild cochain complex of a polynomial algebra is non-formal.Comment: Submitted to proceedings of Poisson 200
a prospective âbefore/afterâ cohort study
Objectives Antibiotic resistance has risen dramatically over the past years.
For individual patients, adequate initial antibiotic therapy is essential for
clinical outcome. Computer-assisted decision support systems (CDSSs) are
advocated to support implementation of rational anti-infective treatment
strategies based on guidelines. The aim of this study was to evaluate long-
term effects after implementation of a CDSS. Design This prospective
âbefore/afterâ cohort study was conducted over four observation periods within
5â
years. One preinterventional period (pre) was compared with three
postinterventional periods: directly after intensive implementation efforts
(post1), 2â
years (post2) and 3â
years (post3) after implementation. Setting
Five anaesthesiological-managed intensive care units (ICU) (one
cardiosurgical, one neurosurgical, two interdisciplinary and one intermediate
care) at a university hospital. Participants Adult patients with an ICU stay
of >48â
h were included in the analysis. 1316 patients were included in the
analysis for a total of 12â
965 ICU days. Intervention Implementation of a
CDSS. Outcome measures The primary end point was percentage of days with
guideline adherence during ICU treatment. Secondary end points were
antibiotic-free days and all-cause mortality compared for patients with low
versus high guideline adherence. Main results Adherence to guidelines
increased from 61% prior to implementation to 92% in post1, decreased in post2
to 76% and remained significantly higher compared with baseline in post3, with
71% (p=0.178). Additionally, antibiotic-free days increased over study
periods. At all time periods, mortality for patients with low guideline
adherence was higher with 12.3% versus 8% (p=0.014) and an adjusted OR of 1.56
(95% CI 1.05 to 2.31). Conclusions Implementation of computerised regional
adapted guidelines for antibiotic therapy is paralleled with improved
adherence. Even without further measures, adherence stayed high for a longer
period and was paralleled by reduced antibiotic exposure. Improved guideline
adherence was associated with reduced ICU mortality
Morita Equivalence, Picard Groupoids and Noncommutative Field Theories
In this article we review recent developments on Morita equivalence of star
products and their Picard groups. We point out the relations between
noncommutative field theories and deformed vector bundles which give the Morita
equivalence bimodules.Comment: Latex2e, 10 pages. Conference Proceeding for the Sendai Meeting 2002.
Some typos fixe
On the Open-Closed B-Model
We study the coupling of the closed string to the open string in the
topological B-model. These couplings can be viewed as gauge invariant
observables in the open string field theory, or as deformations of the
differential graded algebra describing the OSFT. This is interpreted as an
intertwining map from the closed string sector to the deformation (Hochschild)
complex of the open string algebra. By an explicit calculation we show that
this map induces an isomorphism of Gerstenhaber algebras on the level of
cohomology. Reversely, this can be used to derive the closed string from the
open string. We shortly comment on generalizations to other models, such as the
A-model.Comment: LaTeX, 48 pages. Citation adde
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