14,278 research outputs found
Monetary overhang and the dynamics of prices, exchange rates, and income in the transition to a market economy
The long road from capitalism to capitalism the Eastern European economies have made has been paved with many economic problems, but the transition from a command economy into a market economy is likely to become a bumpy ride as well. Apart from the major real economic reforms that have to take place, combined with virtual turnaround of the political structure, several countries aiming to reform face a monetary problem as well. Due to persistent state budget deficits, financed by the printing press, a so called monetary overhang threatens the reform process. Monetary overhang is here defined as the excess of money supply over demand at the current price level and at world market interest rates. The consequences of the monetary overhang under a planning system are obvious: the fixity of prices prevents the real money supply from falling to its equilibrium level, and the situation of repressed inflation translates into long queues in front of shops, forced savings, and, if not checked, into a flourishing black market and corruption. The official exchange rate is overvalued, but import demand is checked by rationing of foreign exchange.
Influence of intensity distribution on the meltpool and clad shape for laser cladding
The influence of the optical system on the laser cladding process is studied, in particular with respect to the burn-in shape: the penetration of the meltpool into the substrate. The beam caustic and intensity profiles for the commonly used out-of-focus laser clad operation are presented and discussed. To avoid the disadvantages of the out-of-focus operation, a novel telezoom optical system is developed, which allows in-focus operation with a sufficiently large focus with a uniform intensity distribution and a spot diameter ranging from 3 up to over 6 mm. Different typical burn-in shapes are indicated, as they can be found in cross sections of experimental clads. The influence of the intensity distribution on the occurring burn-in shapes is discussed, as well as other phenomena that can play a role, such as flow recirculation cells in the meltpool
FTIR and XPS studies on corrosion resistant SiO2 coatings as a function of the humidity during deposition
The degradation of SiO2 coatings deposited on alloys by metal organic chemical vapour deposition (MOCVD) in sulphidizing high-temperature environments is determined by delamination and crack formation. With increasing water concentration during deposition, the crack density in silica decreases and the critical thickness for delamination of SiO2 coatings increases. This improvement is supposed to be caused by compositional changes in the SiO2 coating. In this study presence of water and silanol groups as measured by Fourier transform infrared spectroscopy(FTIR) and the Si:O ratio as measured by XPS are discussed in relation to the protective properties. The FTIRmeasurements show that the coatings deposited in more humid environments contain more silanol groups and have lower stress levels. The coatings obtained under all deposition conditions consisted of stoichiometric SiO2.0 as determined by XPS. The presence of silanol groups reduces the viscosity of the coating, and stress relaxation by viscous flow becomes enhanced, thereby improving the coating performance
Cohomological Yang-Mills theories on Kähler 3-folds
We study topological gauge theories with Nc = (2; 0) supersymmetry based on stable bundles
on general Kähler 3-folds. In order to have a theory that is well defined and well behaved,
we consider a model based on an extension of the usual holomorphic bundle by including a
holomorphic 3-form. The correlation functions of the model describe complex 3-dimensional
generalizations of Donaldson-Witten type invariants. We show that the path integral can be
written as a sum of contributions from stable bundles and a complex 3-dimensional version
of Seiberg-Witten monopoles. We study certain deformations of the theory, which allow us
to consider the situation of reducible connections. We shortly discuss situations of reduced
holonomy. After dimensional reduction to a Kähler 2-fold, the theory reduces to Vafa-Witten
theory. On a Calabi-Yau 3-fold, the supersymmetry is enhanced to Nc = (2; 2). This model
may be used to describe classical limits of certain compactifications of (matrix) string theory
Fission Hindrance in hot 216Th: Evaporation Residue Measurements
The fusion evaporation-residue cross section for 32S+184W has been measured
at beam energies of E_beam = 165, 174, 185, 196, 205, 215, 225, 236, 246,and
257 MeV using the ATLAS Fragment Mass Analyzer. The data are compared with
Statistical Model calculations and it is found that a nuclear dissipation
strength, which increases with excitation energy, is required to reproduce the
excitation function. A comparison with previously published data show that the
dissipation strength depends strongly on the shell structure of the nuclear
system.Comment: 15 pages 9 figure
How Well Does AdS/QCD Describe QCD?
AdS/QCD is an extra-dimensional approach to modeling hadronic physics,
motivated by the AdS/CFT correspondence in string theory. AdS/QCD models are
often more accurate than would have been expected at energies below a few GeV.
We address the question of why these models are so successful, and respond to
some of the criticisms that have been waged against these models.Comment: To appear in proceedings of Crossing the Boundaries: Gauge Dynamics
at Strong Coupling (Shifmania), Minnesota, May 14-17, 2009. 12 pages, 2 eps
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Models for Bundles on Calabi-Yau: A Proposal for Matrix String Compactifications
We describe a class of supersymmetric gauged linear sigma-model, whose target space is the infinite dimensional space of bundles on a Calabi-Yau 3- or 2-fold. This target space can be considered the configuration space of D-branes wrapped around the Calabi-Yau. We propose that this model can be used to define matrix string theory compactifications. In the infrared limit the model flows to a superconformal non-linear sigma-model whose target space is the moduli space of BPS configurations of branes on the compact space, containing the moduli space of semi-stable bundles. We argue that the bulk degrees of freedom decouple in the infrared limit if semi-stability implies stability. We study topological versions of the model on Calabi-Yau 3-folds. The resulting B-model is argued to be equivalent to the holomorphic Chern-Simons theory proposed by Witten. The A-model and half-twisted model define the quantum cohomology ring and the elliptic genus, respectively, of the moduli space of stable bundles on a Calabi-Yau 3-fold
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