Structural investigation of (111) oriented (BiFeO3)(1-x){\Lambda}/(LaFeO3)x{\Lambda} superlattices by X-ray diffraction and Raman spectroscopy

(BiFeO3)(1-x){\Lambda}/(LaFeO3)x{\Lambda} superlattices (SLs) with varying x have been grown by pulsed laser deposition on (111) oriented SrTiO3 substrates. In order to obtain good epitaxy and flat samples a conducting SrRuO3 buffer has been deposited prior to the superlattices to screen the polar mismatch for such (111) SrTiO3 orientation. X-ray diffraction reciprocal space mapping on different family of planes were collected and evidenced a room temperature structural change at x=0.5 from a rhombohedral/monoclinic structure for rich BiFeO3 to an orthorhombic symmetry for rich LaFeO3. This symmetry change has been confirmed by Raman spectroscopy and demonstrates the different phase stability compared to similar SLs grown on (100) SrTiO3. The strongly anisotropic strain and oxygen octahedral rotation/tilt system compatibility at the interfaces probably explain the orientation dependence of the phase stability in such superlattices.Comment: 17 pages, 3 figure

Triple superphosphate, potassium sulfate, and nitrogenous fertilizers effects on fitness and aggressiveness of Fusarium culmorum inducing wheat crown rot

This study examined the effects of N, P, and K fertilizers on Fusarium culmorum on in-vitro mycelial growth and biomass, and aggressiveness on wheat plants. Urea, phosphorus, potassium sulfate, and the mixture of similar amounts of these last two ingredients increased fungal biomass. Rearing mycelia on urea, the mixture, or phosphorus increased aggressiveness by 56%, 120%, and 130%, respectively. But this aggressiveness did not affect inoculated plants dry biomass. However, the inoculum that was reared on ammonium sulfate increased infected plant biomass. These findings infer that the management of this disease may rely on a proper type of fertilizers application. First, farmers are advised to avoid urea and use instead ammonium nitrate; second, place phosphorus and potassium sulfate under the seedbed away from any inoculum in the soil. Therefore, surveying disease development, its past events, soil health, and soil fertility is a prerequisite for any successful control of this disease. Keywords: Fusarium culmorum; Aggressiveness; Fitness; Nitrogen forms; Phosphorus; Potassium sulfate

Efficiency of islamic and conventional banks in countries with islamic banking

Our study aims at analyzing Islamic banks efficiency over the period 2001-2008. We found that they were efficient at 78.9%. The level of efficiency could however vary according to regions. Asia displays the highest score with 84.64%. Indeed, country like Malaysia and Pakistan implemented reforms in order to allow Islamic banks to better cope with the existing financial system. On the contrary countries with Islamic banking system do not necessarily display efficiency scores superior to the average. Further analyses on commercial banks, in the selected countries strengthen the conclusion for a regulatory environment suiting Islamic banking. Besides, the subprime crisis did not impact Islamic banks as evidenced by the dummy variable. Market power and profitability have negative impact on Islamic banks efficiency. Concentration leads to higher costs through slacks and inefficiency. Again other results from robustness checks appear to stress the specificity of Islamic banks, like their first aim for financing rural population

Interpreting the principal component analysis of multivariate density functions

Functional principal component analysis (FPCA) as a reduction data technique of a finite number T of functions can be used to identify the dominant modes of variation of numeric three-way data. We carry out the FPCA on multidimensional probability density functions, relate this method to other standard methods and define its centered or standardized versions. Grounded on the relationship between FPCA of densities, FPCA of their corresponding characteristic functions, PCA of the MacLaurin expansions of these characteristic functions and dual STATIS method applied to their variance matrices, we propose a method for interpreting the results of the FPCA of densities. This method is based on the investigations of the relationships between the scores of the FPCA and the moments associated to the densities. The method is illustrated using known Gaussian densities. In practice, FPCA of densities deals with observations of multidimensional variables on T occasions. These observations can be used to estimate the T associated densities (i) by estimating the parameters of these densities, assuming that they are Gaussian, or (ii) by using the Gaussian kernel method and choosing the matrix bandwidth by the normal reference rule. Thereafter, FPCA estimate is derived from these estimates and the interpretation method is carried out to explore the dominant modes of variation of the types of three-way data encountered in sensory analysis and archaeology

Optimal bandwidth matrices in functional principal component analysis of density functions

In order to explore and compare a finite number T of data sets by applying functional principal component analysis (FPCA) to the T associated probability density functions, we estimate these density functions by using the multivariate kernel method. The data set sizes being fixed, we study the behaviour of this FPCA under the assumption that all the bandwidth matrices used in the estimation of densities are proportional to a common parameter h and proportional to either the variance matrices or the identity matrix. In this context, we propose a selection criterion of the parameter h which depends only on the data and the FPCA method. Then, on simulated examples, we compare the quality of approximation of the FPCA when the bandwidth matrices are selected using either the previous criterion or two other classical bandwidth selection methods, that is, a plug-in or a cross-validation method