Polytopal Bier spheres and Kantorovich-Rubinstein polytopes of weighted cycles

The problem of deciding if a given triangulation of a sphere can be realized as the boundary sphere of a simplicial, convex polytope is known as the "Simplicial Steinitz problem". It is known by an indirect and non-constructive argument that a vast majority of Bier spheres are non-polytopal. Contrary to that, we demonstrate that the Bier spheres associated to threshold simplicial complexes are all polytopal. Moreover, we show that all Bier spheres are starshaped. We also establish a connection between Bier spheres and Kantorovich-Rubinstein polytopes by showing that the boundary sphere of the KR-polytope associated to a polygonal linkage (weighted cycle) is isomorphic to the Bier sphere of the associated simplicial complex of "short sets"

Assessing the extraction efficiency of CaCl2 and rhizon extraction methods after the application of organic matter and CaCl2 as soil amendments to enhance the mobility of Cd and Zn

A pot experiment was conducted to study the extractability of cadmium and zinc by CaCl 2 and rhizon extraction methods after the application of organic matter and chloride as soil amendments. Two methods, Rhizon and CaCl 2 extraction methods were concurrently employed to study the effects of the various amendments on the mobility of Cd and Zn. Both CaCl 2 and Rhizon extraction methods generally extracted appreciable amounts of the heavy metals after the application of the amendments. However, the results from the experiment shows that the Rhizon samplers extracted higher concentrations of both Cd and Zn as compared to the CaCl 2 extraction method. The use of rhizon soil moisture sampler is also non destructive to the soil and makes it possible to ascertain levels of heavy metals at equilibrium in the soil solution without changing the compisition of the soil solution in the process of extracting it. Assessment of the soil pH in the soil samples and the Rhizon extracts after the application of the amendments showed no significant difference with the control. Comparatively, application of CaCl 2 had a significant mobilizing effect on the mobility of both Cd and Zn as a result of the combined effect of complexation of Cd and Zn by the chloride anion, and by the fact that Cd and Zn are referentially absorbed in cation exchange positions. Therefore the Ca 2+ ion can displace these metals into the soil solution

Intermittent Connectivity for Exploration in Communication-Constrained Multi-Agent Systems

Motivated by exploration of communication-constrained underground environments using robot teams, we study the problem of planning for intermittent connectivity in multi-agent systems. We propose a novel concept of information-consistency to handle situations where the plan is not initially known by all agents, and suggest an integer linear program for synthesizing information-consistent plans that also achieve auxiliary goals. Furthermore, inspired by network flow problems we propose a novel way to pose connectivity constraints that scales much better than previous methods. In the second part of the paper we apply these results in an exploration setting, and propose a clustering method that separates a large exploration problem into smaller problems that can be solved independently. We demonstrate how the resulting exploration algorithm is able to coordinate a team of ten agents to explore a large environment

Geometry of entanglement witnesses parameterized by SO(3) group

We characterize a set of positive maps in matrix algebra of 4x4 complex matrices. Equivalently, we provide a subset of entanglement witnesses parameterized by the rotation group SO(3). Interestingly, these maps/witnesses define two intersecting convex cones in the 3-dimensional parameter space. The existence of two cones is related to the topological structure of the underlying orthogonal group. We perform detailed analysis of the corresponding geometric structure.Comment: 10 page

ANALYSIS OF THE TAXATION SYSTEM IN ROMANIA IN THE ECONOMIC CRISIS CONTEXT

In this paper we try to realize a study on the interdependencies and correlation between the fiscal policy and financial and economic crisis in Romania. First, we analyze the taxation system in Romania before and after the start of economic crisis to establish the correlation between the level of taxation and the economic growth rate. The sense of correlation is important for analysis the direction of the government fiscal policy in the present context. It is important to follow the major changes of fiscal system after economic crisis beginning to anticipate the opportunity of these fiscal measures in the new economic climate.fiscal policy, financial turmoil, budget deficit, Romanian economy, tax burden.

Spin-Hall Effect in A Symmetric Quantum Wells by A Random Rashba Field

Changes dopant ion concentrations in the sides of a symmetric quantum well are known to create a random Rashba-type spin-orbit coupling. Here we demonstrate that, as a consequence, a finite size spin-Hall effect is also present. Our numerical algorithm estimates the result of the Kubo formula for the spin-Hall conductivity, by using a tight-binding approximation of the Hamiltonian in the framework of a time-dependent Green's function formalism, well suited for very large systems.Comment: 4 pages, 4 figures in eps forma

LDA+DMFT Approach to Magnetocrystalline Anisotropy of Strong Magnets

The new challenges posed by the need of finding strong rare-earth free magnets demand methods that can predict magnetization and magnetocrystalline anisotropy energy (MAE). We argue that correlated electron effects, which are normally underestimated in band structure calculations, play a crucial role in the development of the orbital component of the magnetic moments. Because magnetic anisotropy arises from this orbital component, the ability to include correlation effects has profound consequences on our predictive power of the MAE of strong magnets. Here we show that incorporating the local effects of electronic correlations with dynamical mean-field theory provides reliable estimates of the orbital moment, the mass enhancement and the MAE of YCo5.Comment: 7 pages, 4 figures, published versio