Search results for " Methods"
showing 10 items of 4102 documents
Nature of the non-exponential primary relaxation in structural glass-formers probed by dynamically selective experiments
1998
Several experimental methods feature the potential to distinguish between slow and fast contributions to the non-exponential, ensemble averaged primary response in glass-forming materials. Some of these techniques are based on the selection of subensembles using multi-dimensional nuclear magnetic resonance, optical bleaching, and non-resonant spectral hole burning. Others, such as the time-dependent solvation spectroscopy, measure microscopic responses induced by local perturbations. Using several of these methods it could be demonstrated for various glass-forming materials that the non-exponential relaxation results from a superposition of dynamically distinguishable entities. The experime…
First principles simulations of 2D Cu superlattices on the MgO(0 0 1) surface
2004
AbstractFirst principles slab simulations of copper 2D superlattices of different densities on the perfect MgO(001) surface are performed using the DFT method as implemented into the CRYSTAL98 computer code. In order to clarify the nature of interfacial bonding, we consider regular 1/4, 1/2 and 1 monolayer (ML) coverages and compare results of our calculations with various experimental and theoretical data. Our general conclusion is that the physical adhesion associated with a Cu polarization and charge redistribution gives the predominant contribution to the bonding of the regular Cu 2D layer on the MgO(001) surface.
Calculations of the atomic and electronic structure for SrTiO3 perovskite thin films
2001
The results of calculations of SrTiO3 (100) surface relaxation and rumpling with two different terminations (SrO and TiO2) are presented and discussed. We have used the ab initio Hartree–Fock (HF) method with electron correlation corrections and the density functional theory (DFT) with different exchange–correlation functionals, including hybrid exchange techniques. All methods agree well on surface energies and on atomic displacements, as well as on the considerable increase of covalency effects near the surface. More detailed experiments on surface rumpling and relaxation are necessary for further testing of theoretical predictions.
DFT plane wave calculations of the atomic and electronic structure of LaMnO3(001) surface
2009
We present the results of ab initio DFT plane wave periodic structure calculations of the LaMnO3 (001) surface. The effects related to three different kinds of pseudopotentials, the slab thickness, magnetic ordering, and surface relaxation are studied and discussed. The antiferromagnetic surface lowest in energy (that is, the spins on Mn ions are parallel in basal plane and antiparallel from plane to plane) has a considerable atomic relaxation up to the fourth plane from the surface. The calculated (Bader) effective charges and the electronic density maps demonstrate a considerable reduction of the Mn atom ionicity on the surface accompanied by a covalent contribution to the Mn–O bonding.
The assessment of parenting in the child welfare practice
1999
Abstract This study analyzed how parenting and factors considered as important determinants of parental care are assessed in the child welfare practice during the placement process, using ethnographic content analysis of case records. The assessment of parenting and the factors affecting it was unsystematic and unplanned with no consistency between cases. The documentary mentions concerning the quality of parent-child relationships were surprisingly rare. The descriptions concentrated more on parents' problems than problems in parenting and the qualities of the parent-child relationship. This study indicated that apart from the need for systematized assessment methods in Finnish child welfa…
Unitary Space–Time Constellation Design Based on the Chernoff Bound of the Pairwise Error Probability
2008
Unitary space-time constellation design is considered for noncoherent multiple-antenna communications, where neither the transmitter nor the receiver knows the fading coefficients of the channel. By employing the Clarke's subdifferential theorem of the sum of the kappa largest singular values of a unitary matrix, we present a numerical optimization procedure for finding unitary space-time signal constellations of any dimension. The Chernoff bound of the pairwise error probability is used directly as a design criterion. The constellations are found by performing gradient descent search on a family ldquosurrogaterdquo functions that converge to the maximum pairwise error probability. The comp…
mplicit Identification of Contact Parameters in a Continuous Chain Model
2011
Accurate contact modeling is of great importance in the field of dynamic chain simulations. In this paper emphasis is on contact dynamics for a time-domain simulation model of large chains guided in a closed loop track. The chain model is based on theory for unconstrained rigid multibody dynamics where contact within the chain and with the track is defined through continuous point contacts using the contact indentation and rate as means. This paper presents an implicit method to determine contact parameters of the chain model through the use of none gradient optimization methods. The set of model parameters are estimated by minimizing the residual between simulated and measured results. The…
Delving Into the Body Fears’. Teacher Training in Art Education Attending to the Work of Women Artists
2018
Planteamos el uso del arte contemporáneo en la formación de docentes. Consideramos de gran interés acercar los actuales dispositivos del arte a las futuras generaciones de maestros y maestras, ya que en el mundo del arte se están tratando temáticas sociales y culturales que van a resultar decisivas en la labor que deberán llevar a cabo quienes eduquen. Desde una perspectiva regeneradora y vitalista, proponemos una posibilidad de estrategias en la formación artística del colectivo docente. Integramos temáticas que habitualmente no se tratan en el ámbito escolar, pero que están vinculadas a las emociones, a las necesidades y a la vida cotidiana del alumnado. Conceptos como «el miedo» o «el cu…
Management of Microbiological Quality of Meat in the Context of Rapid Tenderization
2018
Abstract This paper focuses on the study of the microbiological load of pork and beef meat, in the context of utilising fast methods of tenderizing them. The study highlights, through both classic and fast methods, the microbial load of fresh, salted and smoked pork and beef meat. It has been established that fresh pork is at around 7,2x104-8,5x104CFU/g, whereas fresh beef sits at around 2,3x103 CFU/g. For salted, smoked and classically tenderized, these values are between 3,3x104 CFU/g and 4,7x104CFU/g for pork and 6,1x102 CFU/g for beef. The method of rapid tenderizing leads to highlighting a decreased microbial load: 2,2x103 CFU/g-5,4x103CFU/g for pork, 2,8x102 CFU/g for beef, which cons…
Utility of the Mantel-Haenszel Procedure for Detecting Differential Item Functioning in Small Samples
2004
Sample-size restrictions limit the contingency table approaches based on asymptotic distributions, such as the Mantel-Haenszel (MH) procedure, for detecting differential item functioning (DIF) in many practical applications. Within this framework, the present study investigated the power and Type I error performance of empirical and inferential criteria for DIF detection in small samples. Sample sizes (50/50, 100/50, 200/50, and 100/100 for the reference and focal groups, respectively), ability distributions (equal and unequal), and amount of DIF (moderate and high) were manipulated. The results show the advantages of employing theMHchi-square statistic using high levels of significance (•…