Determination of spin polarization in InAs/GaAs self-assembled quantum dots

The spin polarization of electrons trapped in InAs self-assembled quantum dot ensembles is investigated. A statistical approach for the population of the spin levels allows one to infer the spin polarization from the measure values of the addition energies. From the magneto-capacitance spectroscopy data, the authors found a fully polarized ensemble of electronic spins above 10 T when $\mathbf{B}\parallel[001]$ and at 2.8 K. Finally, by including the g-tensor anisotropy the angular dependence of spin polarization with the magnetic field $\mathbf{B}$ orientation and strength could be determined.Comment: 3 pages, 2 figures, Accepted Appl. Phys. Let

Acnowledging for spatial effects in the Portuguese housing markets

The aim of this paper is to revisit a former paper on the Portuguese housing market (1995), acknowledging for spatial effects in order to interpret housing market changes over 1995-2001. The paper will include a first section devoted to explain the differences between the OLS regression analysis and spatial econometrics, explaining the theoretical background used to develop a spatial lag model with the same database; the second section will show the misspecification problems we found when we ran the same model for after 1995-1998 databases; the third section is devoted to describe new housing literature findings relating housing market evolution with the macroeconomic cycles in Portugal; as a consequence the fourth section will include the method we developed with recent census data, to explain the evolution of the country macroeconomic cycles and the agents’ new behavioural attitudes concerning housing; finally and using spatial analysis we can understand the main changes occurred over the 1995-2001 period. The evaluation of the results contradicts some mainstream scholar and political knowledge to explain spatial inequalities between coast and interior municipalities. Complexity issues seem to be present when we consider the way different market agents make decisions on housing markets, looking this good either as a place to live or an alternative investment asset. In the concluding remarks we raise some new interesting questions for further research.

Finite size and finite temperature studies of the osp(1∣2)osp(1|2) spin chain

We study a quantum spin chain invariant by the superalgebra $osp(1|2)$. We derived non-linear integral equations for the row-to-row transfer matrix eigenvalue in order to analyze its finite size scaling behaviour and we determined its central charge. We have also studied the thermodynamical properties of the obtained spin chain via the non-linear integral equations for the quantum transfer matrix eigenvalue. We numerically solved these NLIE and evaluated the specific heat and magnetic susceptibility. The analytical low temperature analysis was performed providing a different value for the effective central charge. The computed values are in agreement with the numerical predictions in the literature.Comment: 26 pages, 2 figure

Optimal sampling strategies for multiscale stochastic processes

In this paper, we determine which non-random sampling of fixed size gives the best linear predictor of the sum of a finite spatial population. We employ different multiscale superpopulation models and use the minimum mean-squared error as our optimality criterion. In multiscale superpopulation tree models, the leaves represent the units of the population, interior nodes represent partial sums of the population, and the root node represents the total sum of the population. We prove that the optimal sampling pattern varies dramatically with the correlation structure of the tree nodes. While uniform sampling is optimal for trees with ``positive correlation progression'', it provides the worst possible sampling with ``negative correlation progression.'' As an analysis tool, we introduce and study a class of independent innovations trees that are of interest in their own right. We derive a fast water-filling algorithm to determine the optimal sampling of the leaves to estimate the root of an independent innovations tree.Comment: Published at http://dx.doi.org/10.1214/074921706000000509 in the IMS Lecture Notes--Monograph Series (http://www.imstat.org/publications/lecnotes.htm) by the Institute of Mathematical Statistics (http://www.imstat.org