2,002 research outputs found
Remarks on Pure Spin Connection Formulations of Gravity
In the derivation of a pure spin connection action functional for gravity two
methods have been proposed. The first starts from a first order lagrangian
formulation, the second from a hamiltonian formulation. In this note we show
that they lead to identical results for the specific cases of pure gravity with
or without a cosmological constant
Towards a path integral for the pure-spin connection formulation of gravity
A proposal for the path-integral of pure-spin-connection formulation of
gravity is described, based on the two-form formulation of Capovilla et. al. It
is shown that the resulting effective-action for the spin-connection, upon
functional integration of the two-form field and the auxiliary matrix
field is {\it non-polynomial}, even for the case of vanishing
cosmological constant and absence of any matter couplings. Further, a
diagramatic evaluation is proposed for the contribution of the matrix-field to
the pure spin connection action.Comment: 8 pages in plain-TeX.-----IUCAA_TH/9
2-Form Gravity of the Lorentzian Signature
We introduce a new spinorial, BF-like action for the Einstein gravity. This
is a first, up to our knowledge, 2-form action which describes the real,
Lorentzian gravity and uses only the self-dual connection. In the generic case,
the corresponding classical canonical theory is equivalent to the
Einstein-Ashtekar theory plus the reality conditions
Identification and structural characterisation of a partially arabinosylated lipoarabinomannan variant isolated from a Corynebacterium glutamicum ubiAmutant
Arabinan polysaccharide side-chains are present in both Mycobacterium tuberculosis and Corynebacterium glutamicum in the heteropolysaccharide arabinogalactan (AG), and in M. tuberculosis in the lipoglycan, lipoarabinomannan (LAM). Herein, we show by quantitative sugar and glycosyl linkage analysis that C. glutamicum possesses a much smaller LAM version, Cg-LAM, characterised by single t-Araf residues linked to th
Topological Lattice Gravity Using Self-Dual Variables
Topological gravity is the reduction of general relativity to flat
space-times. A lattice model describing topological gravity is developed
starting from a Hamiltonian lattice version of B\w F theory. The extra
symmetries not present in gravity that kill the local degrees of freedom in
theory are removed. The remaining symmetries preserve the
geometrical character of the lattice. Using self-dual variables, the conditions
that guarantee the geometricity of the lattice become reality conditions. The
local part of the remaining symmetry generators, that respect the
geometricity-reality conditions, has the form of Ashtekar's constraints for GR.
Only after constraining the initial data to flat lattices and considering the
non-local (plus local) part of the constraints does the algebra of the symmetry
generators close. A strategy to extend the model for non-flat connections and
quantization are discussed.Comment: 22 pages, revtex, no figure
Higgs Bosons: Intermediate Mass Range at e+e- Colliders
We elaborate on the production of the Standard Model Higgs particle at
high-energy colliders through the reaction .
Particular emphasis is put on the intermediate mass range. In addition to the
signal we discuss in detail the background processes. Angular distributions
which are sensitive to the spin and parity of the Higgs particle are analyzed.Comment: Standard Latex. 15 pages. 11 figures available by fax or regular
mail. MAD/PH/749, DESY 93-064, UdeM-LPN-TH-93-143, NUHEP-TH-93-1
Automated glycan assembly of arabinomannan oligosaccharides from Mycobacterium tuberculosis
Arabinomannan (AM) polysaccharides are clinical biomarkers for Mycobacterium tuberculosis (MTB) infections due to their roles in the interaction with host cells and interference with macrophage activation. Collections of defined AM oligosaccharides can help to improve the understanding of these polysaccharides and the development of novel therapeutical and diagnostic agents. Automated glycan assembly (AGA) was employed to prepare the core structure of AM from MTB, containing α-(1,6)-Man, α-(1,5)-Ara, and α-(1,2)-Man linkages. The introduction of a capping step after each glycosylation and further optimized reaction conditions allowed for the synthesis of a series of oligosaccharides, ranging from hexa- to branched dodecasaccharides
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