163 research outputs found
Chiral expansion and Macdonald deformation of two-dimensional Yang-Mills theory
We derive the analog of the large Gross-Taylor holomorphic string
expansion for the refinement of -deformed Yang-Mills theory on a
compact oriented Riemann surface. The derivation combines Schur-Weyl duality
for quantum groups with the Etingof-Kirillov theory of generalized quantum
characters which are related to Macdonald polynomials. In the unrefined limit
we reproduce the chiral expansion of -deformed Yang-Mills theory derived by
de Haro, Ramgoolam and Torrielli. In the classical limit , the expansion
defines a new -deformation of Hurwitz theory wherein the refined
partition function is a generating function for certain parameterized Euler
characters, which reduce in the unrefined limit to the orbifold Euler
characteristics of Hurwitz spaces of holomorphic maps. We discuss the
geometrical meaning of our expansions in relation to quantum spectral curves
and -ensembles of matrix models arising in refined topological string
theory.Comment: 45 pages; v2: References adde
Ion beam effect on Ge-Se chalcogenide glass films: Non-volatile memory array formation, structural changes and device performance
The conductive bridge non-volatile memory technology is an emerging way to
replace traditional charge based memory devices for future neural networks and
configurable logic applications. An array of the memory devices that fulfills
logic operations must be developed for implementing such architectures. A
scheme to fabricate these arrays, using ion bombardment through a mask, has
been suggested and advanced by us. Performance of the memory devices is
studied, based on the formation of vias and damage accumulation due to the
interactions of Ar+ ions with GexSe1-x (x=0.2, 0.3 and 0.4) chalcogenide
glasses as a function of the ion energy and dose dependence. Blanket films and
devices were created to study the structural changes, surface roughness, and
device performance. Raman Spectroscopy, Atomic Force Microscopy (AFM), Energy
Dispersive X-Ray Spectroscopy (EDS) and electrical measurements expound the Ar+
ions behavior on thin films of GexSe1-x system. Raman studies show that there
is a decrease in area ratio between edge-shared to corner-shared structural
units, revealing occurrence of structural reorganization within the system as a
result of ion/film interaction. AFM results demonstrate a tendency in surface
roughness improvement with increased Ge concentration, after ion bombardment.
EDS results reveal a compositional change in the vias, with a clear tendency of
greater interaction between ions and the Ge atoms, as evidenced by greater
compositional changes in the Ge rich films
Comparative Microstructural Study of the Diffusion Zone Between Ni-Cr Alloy and Different Dental Ceramics
Detailed knowledge of bonding mechanisms, between the metal and ceramic parts in conventional dental systems, can help the development of new, improved systems and the optimisation of recent technologies. Despite their allergic potential, the NiCr alloys are still amongst the most often used dental materials so their investigation is important. The aim of the study was to carry out a
detailed microstructural investigation and to compare the reaction layer developed between three different dental ceramics and NiCr alloy under different firing conditions. For the measurements six identical samples were cast from WIRON 99 (Bego, Konstantz, Germany) alloy. Ceramic opaquers were fired on the polished surface
using Vision (Wohlwend AG), Vita VMK 95 (Vita) and Carat(DeTrey/Dentsplay) materials. Two samples were produced from each type of opaquers by different firing conditions. The TEM investigations were performed by using a 2000FX-II microscope with a Link-lsis EDS system. Similar growth processes of the phases were observed in all of the investigated systems in the sense that an amorphous phase was formed on the metal-ceramic interface
producing bubble like inclusions on the metal surface. The main component of this phase is silicon oxide in the case of Carat and Vita ceramics, while in the case of Vision potassium and nickel oxides were observed after the normal firing process. In all systems and at all firing conditions a nanocrystalline Cr2O3 layer (with about 50 nm
grain size) was commonly observed. This investigation was supported in part by ETT Grant 2001-3
Stimulated structural changes of Se in nanolayered composite films
International audienceAmorphous selenium (a-Se) is the simplest model material for investigation of the well-known photoinduced structural and optical transformations in amorphous chalcogenides. Since a lot of parameters and characteristics of materials essentially change at nanoscale, we applied nanostructuring to a -Se in nanomultilayers, obtained by pulsed laser deposition. The enhancement of photo- and thermally-induced crystallization was observed in a-Se/aluminosilicate nanomultilayers due to the initially heterogeneous state of Se in such samples, in comparison with single a -Se layers
Optical Nanocomposites Based on High Nanoparticles Concentration and Its Holographic Application
Purification and characterization of a small dermatan sulphate proteoglycan implicated in the dilatation of the rat uterine cervix
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