35 research outputs found
Non-BPS D-Branes in Light-Cone Green-Schwarz Formalism
Non-BPS D-branes are difficult to describe covariantly in a manifestly
supersymmetric formalism. For definiteness we concentrate on type IIB string
theory in flat background in light-cone Green-Schwarz formalism. We study both
the boundary state and the boundary conformal field theory descriptions of
these D-branes with manifest SO(8) covariance and go through various
consistency checks. We analyze Sen's original construction of non-BPS D-branes
given in terms of an orbifold boundary conformal field theory. We also directly
study the relevant world-sheet theory by deriving the open string boundary
condition from the covariant boundary state. Both these methods give the same
open string spectrum which is consistent with the boundary state, as required
by the world-sheet duality. The boundary condition found in the second method
is given in terms of bi-local fields that are quadratic in Green-Schwarz
fermions. We design a special ``doubling trick'' suitable to handle such
boundary conditions and prescribe rules for computing all possible correlation
functions without boundary insertions. This prescription has been tested by
computing disk one-point functions of several classes of closed string states
and comparing the results with the boundary state computation.Comment: 47 pages, 1 figure. Typos corrected, references added and slight
modification of certain explanation made. Version accepted for publication in
JHE
Computer program for nonlinear least square analysis of impedance and admittance data
A computer program to estimate the parameter value from the complex impedance data of the equivalent
circuit is reported. Non-linear complex least squares fitting is made using a laboratory microcomputer
(with real values). Different values are used as the initial guess in the iterative calculation of complex
least-square method which fits both real and imaginary components of the actual impedance. The
program is tested for simple RC circuits which are generally used to model the electrochemical system
by introducing random experimental errors and it is found to converge within a few number of iteration
Solid electrolyte systems - recent trends
Solid electrolytes, which possess high ionic conductivitiescomparable with those of aqueous
electrolytes, have received much attention in the last decade, as they play a major role in the
field of miniaturisation particularly as power sources. Recent developments in the field from
the point of view of materials, development of proper electrodes for battery applications, the
process of intercalation are highlighted. An account of the important electrochemical device
applications is dealt with
A process to make ordinary writing paper electrically conducting for use as base paper in zinc oxide paper based electrophotographic process
Improvements in or relating to the preparation of green photo luminascent copper activated zinc sulphider phosphor
Photoluminescence of oxygen dominated phosphors
The mechanism of fluorescence in (a) CaW04, (b) Zn2Si04:Mn, (c) 3.5 MgO + 0.5 MgF2 +
GeO, : Mn, and (dl 3Ca,(P04), Ca(F, C1)2:Sb3+, Mn2+ under excitation by shortwave ultraviolet
is explained by the electronic transitions involved in the activators. To get a daylight phosphor
conforming to 6500"K, a blending of a sb3+ activated halophosphate blue phosphor and a
Sb3+ and Mn2+ activated warmwhite phosphor is essential and the successful preparation of
the same is presente
Surface treatments of fluorine doped tin oxide films
Fluorinedoped tin oxide films prepared by spray pyrolysis were subjected to chemical etching using
hydrazine hydrate, mechanical polishing and electrochemical etching (cathodic), and the consequent
changes in the sheet resistance and optical transmiss~on of the films are reported. Scanning electron
microscopic examination revealed a change in the surface morphology of the film
Photoluminescence of oxygen dominated phosphors
The mechanism of fluorescence in (a) CaW04, (b) Zn2Si04:Mn, (c) 3.5 MgO + 0.5 MgF2 +
GeO, : Mn, and (dl 3Ca,(P04), Ca(F, C1)2:Sb3+, Mn2+ under excitation by shortwave ultraviolet
is explained by the electronic transitions involved in the activators. To get a daylight phosphor
conforming to 6500"K, a blending of a sb3+ activated halophosphate blue phosphor and a
Sb3+ and Mn2+ activated warmwhite phosphor is essential and the successful preparation of
the same is presente