A unified approach for covariance matrix estimation under Stein loss

In this paper, we address the problem of estimating a covariance matrix of a multivariate Gaussian distribution, relative to a Stein loss function, from a decision theoretic point of view. We investigate the case where the covariance matrix is invertible and the case when it is non--invertible in a unified approach

A Three-Phase Grid-Connected PV System Based on SAPF for Power Quality Improvement

This paper proposes a combined system of three-phase four-wire shunt active power filter (SAPF), and photovoltaic generator (PVG), to solve the power quality problems such as harmonic currents, poor power factor, and unbalanced load. In addition, the proposed system can inject the issued energy from the PVG into the utility grid. To increase the efficiency of the PVG and extract the maximum photovoltaic (PV) power under variable atmospheric conditions, a maximum power point tracking (MPPT) technique based on perturb and observe (P&O) is implemented in the DC/DC boost converter. The effectiveness of the proposed PVG-SAPF (PVG and SAPF) based on the use of synchronous reference frame theory (SRF theory) under unbalanced nonlinear load. The proposed PVG-SAPF is validated through numerical simulations using Matlab/Simulink software. The simulation results show the effectiveness of the proposed PVG-SAPF.

A unified approach for covariance matrix estimation under Stein loss

In this paper, we address the problem of estimating a covariance matrix of a multivariate Gaussian distribution, from a decision theoretic point of view, relative to a Stein type loss function. We investigate the case where the covariance matrix is invertible and the case when it is non–invertible in a unified approach

Alternative Splicing Regulates Targeting of Malate Dehydrogenase in Yarrowia lipolytica

Alternative pre-mRNA splicing is a major mechanism contributing to the proteome complexity of most eukaryotes, especially mammals. In less complex organisms, such as yeasts, the numbers of genes that contain introns are low and cases of alternative splicing (AS) with functional implications are rare. We report the first case of AS with functional consequences in the yeast Yarrowia lipolytica. The splicing pattern was found to govern the cellular localization of malate dehydrogenase, an enzyme of the central carbon metabolism. This ubiquitous enzyme is involved in the tricarboxylic acid cycle in mitochondria and in the glyoxylate cycle, which takes place in peroxisomes and the cytosol. In Saccharomyces cerevisiae, three genes encode three compartment-specific enzymes. In contrast, only two genes exist in Y. lipolytica. One gene (YlMDH1, YALI0D16753g) encodes a predicted mitochondrial protein, whereas the second gene (YlMDH2, YALI0E14190g) generates the cytosolic and peroxisomal forms through the alternative use of two 3′-splice sites in the second intron. Both splicing variants were detected in cDNA libraries obtained from cells grown under different conditions. Mutants expressing the individual YlMdh2p isoforms tagged with fluorescent proteins confirmed that they localized to either the cytosolic or the peroxisomal compartment

Multipole rate coefficients for collisional excitation of Fe XIII by isotropic electrons

The multipole rate coefficients $$C^K$$ for excitation of highly charged ions by impact with isotropic electrons are required in the analysis of intensity and polarization of line emission from hot plasmas exposed to anisotropic external radiation. Assuming a Maxwellian electron energy distribution, we calculate $$C^K$$ for transitions between fine-structure levels of the Si-like ion Fe XIII in the temperature range $$(0.7-5)\times 10^6$$ K. Selected results for transitions within the $$3s^23p^2$$ ground configuration and from $$3s^23p^2$$ to $$3s^23p3d$$ levels are given. These transitions are of interest in solar corona diagnostics based on the infrared forbidden lines at 1074.7 and 1079.8 nm and extreme ultraviolet optically-allowed lines at 202.0 and 203.8 Å. To obtain $$C^K$$, we need the multipole collision strengths $$\varOmega ^K$$ which we calculate in a wide range of electron energy in the relativistic distorted-wave approximation, using a modified version of the excitation program of the Flexible Atomic Code