1,277 research outputs found
Engineering Exchange Coupling in Double Elliptic Quantum Dots
Coupled elliptic quantum dots with different aspect ratios containing up to
two electrons are studied using a model confinement potential in the presence
of magnetic fields. Single and two particle Schroedinger equations are solved
using numerical exact diagonolization to obtain the exchange energy and
chemical potentials. As the ratio between the confinement strengths in
directions perpendicular and parallel to the coupling direction of the double
dots increases, the exchange energy at zero magnetic field increases, while the
magnetic field of the singlet-triplet transition decreases. By investigating
the charge stability diagram, we find that as inter-dot detuning increases, the
absolute value of the exchange energy increases superlinearly followed by
saturation. This behavior is attributed to the electron density differences
between the singlet and triplet states in the assymetric quantum dot systems.Comment: 5 pages, 5 figure
Prospects for the development of advanced grain processing in Russia
Purpose: The article is devoted to the identifying and evaluating promising areas of advanced grain and legumes processing development as a strategically important area for import substitution and food security of the agribusiness complex. Methodology/Approach: To achieve this goal, it is necessary to solve the following tasks: the analysis of advanced grain and legumes processing products; the evaluation of the current Russian market for advanced grain processing products; the identification of promising products and directions of the advanced grain processing industry development. Findings: According to the analysis in this article, this industry is in its infancy, despite the fact that in most developed countries of the world, advanced grain processing is widely elaborated. The key reasons for the Russia's lag there involve the lack of domestic techniques and highly qualified specialists in this field. Processing grain into flour, starches, glucose syrups, biofuels and organic acids makes possible manufacturing plastic and other products. To realize the Russia's potential in manufacturing high-value-added agricultural products, it is necessary to provide state support for investment projects for wheat deep processing through preferential lending and taxation, and co-financing of projects. The strategic goal of the Russian agribusiness in the medium and long term should be changing the structure of manufacturing and export in order to export finished products, but not raw materials. Practical implications: The results of this research could be introduced in the process of strategic planning of the agribusiness development and import substitution policy in Russia. Originality/Value: The key contribution of this study lies in the findings of the advanced grain processing industries’ analysis in Russia with the regional aspects taken into account.peer-reviewe
A-Model Correlators from the Coulomb Branch
We compute the contribution of discrete Coulomb vacua to A-Model correlators
in toric Gauged Linear Sigma Models. For models corresponding to a compact
variety, this determines the correlators at arbitrary genus. For non-compact
examples, our results imply the surprising conclusion that the quantum
cohomology relations break down for a subset of the correlators.Comment: 27 pages, 1 xy-pic figur
Electroweak gauge boson production at hadron colliders through O(alpha_s^2)
We describe a calculation of the O(alpha_s^2) QCD corrections to the fully
differential cross section for W and Z boson production in hadronic collisions.
The result is fully realistic in that it includes spin correlations, finite
width effects, gamma-Z interference and allows for the application of arbitrary
cuts on the leptonic decay products of the W and Z. We have implemented this
calculation into a numerical program. We demonstrate the use of this code by
presenting phenomenological results for several future LHC analyses and recent
Tevatron measurements, including the W cross section in the forward rapidity
region and the central over forward cross section ratio.Comment: 11 pages, 4 figure
Multidimensional integrable vacuum cosmology with two curvatures
The vacuum cosmological model on the manifold describing the evolution of Einstein spaces of non-zero
curvatures is considered. For the Einstein equations are reduced to the
Abel (ordinary differential) equation and solved, when dim dim. The Kasner-like behaviour of the
solutions near the singularity is considered ( is synchronous
time). The exceptional ("Milne-type") solutions are obtained for arbitrary .
For these solutions are attractors for other ones, when . For dim and certain two-parametric
families of solutions are obtained from ones using "curvature-splitting"
trick. In the case , a family of non-singular
solutions with the topology is found.Comment: 21 pages, LaTex. 5 figures are available upon request (hard copy).
Submitted to Classical and Quantum Gravit
Crossover from diffusive to strongly localized regime in two-dimensional systems
We have studied the conductance distribution function of two-dimensional
disordered noninteracting systems in the crossover regime between the diffusive
and the localized phases. The distribution is entirely determined by the mean
conductance, g, in agreement with the strong version of the single-parameter
scaling hypothesis. The distribution seems to change drastically at a critical
value very close to one. For conductances larger than this critical value, the
distribution is roughly Gaussian while for smaller values it resembles a
log-normal distribution. The two distributions match at the critical point with
an often appreciable change in behavior. This matching implies a jump in the
first derivative of the distribution which does not seem to disappear as system
size increases. We have also studied 1/g corrections to the skewness to
quantify the deviation of the distribution from a Gaussian function in the
diffusive regime.Comment: 4 pages, 4 figure
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