Search results for " density"
showing 10 items of 2709 documents
First-principles phonon calculations of Fe4+impurity in SrTiO3
2012
The results of hybrid density functional theory calculations on phonons in Sr(Fe(x)Ti(1-x))O(3) solid solution within the formalism of a linear combination of atomic orbitals are presented. The phonon density of states (DOS) calculated for 6.25% Fe(4+) impurities is reported and defect-induced phonon modes are identified. Based on our calculations and group-theoretical analysis, we suggest for the first time an interpretation of experimentally observed Raman- and IR-active modes.
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.
Semiconducting half-Heusler and LiGaGe structure type compounds
2009
Compounds with LiAlSi (half-Heusler) and LiGaGe structure types have been investigated by means of band structure calculations. The LiAlSi structure type is known as the half-Heusler structure type, whereas LiGaGe is a closely related hexagonal variant. A remarkable feature of some XYZ half-Heusler compounds with 8 and 18 valence electrons is, that despite being composed of only metallic elements, they are semiconductors. More than 100 semiconducting compounds within these structure types are known. LiGaGe compounds have an additional degree of freedom, namely the degree of puckering of the layers. These compounds can become semiconducting at a certain degree of puckering. Half-metallic beh…
Examination Technique of Confocal Laser Endomicroscopy
2007
The first publication about a confocal fluorescence microscope integrated into the distal tip of a conventional colonoscope (Pentax EC 3830FK, Tokyo, Japan) appeared in 2004 [1], showing that in vivo microscopy at subcellular resolution (0.7 µm) simultaneously displayed with white-light endoscopy had become possible. Today, endomicroscopy can be performed in the upper and lower GI tract [2]–[10]. This chapter deals with the examination technique of confocal laser endomicroscopy.
Influence of 150 Years of Land Use on Anthropogenic and Natural Carbon Stocks in Emilia-Romagna Region (Italy)
2011
Changes in land use/cover that are commonly associated with urbanization can dramatically influence the amount, chemical form, and spatial distribution of carbon (C) stocks. Measured values and relative literature for composition of natural and anthropogenic materials have been compiled. These data are used in conjunction with land cover statistics and expert assessment of building design to calculate C stocks associated with 150 years of land use change and development for an area of the Po River Valley, Northern Italy. Using 4 time periods (1853, 1954, 1976, and 2003), we demonstrate that the C stocks within this densely populated area have undergone considerable modification. A 52% incre…
Thresholds for impaired species recovery
2015
Studies on small and declining populations dominate research in conservation biology. This emphasis reflects two overarching frameworks: the small-population paradigm focuses on correlates of increased extinction probability; the declining-population paradigm directs attention to the causes and consequences of depletion. Neither, however, particularly informs research on the determinants, rate or uncertainty of population increase. By contrast, Allee effects (positive associations between population size and realized per capita population growth rate, r realized , a metric of average individual fitness) offer a theoretical and empirical basis for identifying numerical and temporal threshol…
Utility of island populations in re-introduction programmes--relationships between Arabian gazelles (Gazella arabica) from the Farasan Archipelago an…
2014
Understanding local adaptation and population differentiation is vital to the success of re-introduction initiatives. As other mammals living on islands, Arabian gazelles (G. arabica) show reduced body size on the Farasan archipelago, which we corroborated in this study through morphometric analyses of skulls. In the light of the steep population decline on the Arabian Peninsula – but stable population development on the archipelago – we tested the potential suitability of Farasan gazelles as a source for re-introductions on the mainland. We therefore investigated genetic differentiation between Farasan and mainland populations using eleven nuclear microsatellite loci and detected a distinc…
Segregated ice and liquefaction effects on compaction of fragipans
2004
The brittleness of fragipans is generally ascribed to the close-packing fabric arrangement acquired at the initial step of pedogenesis thanks to physical processes. However, there is an on-going debate over the agent causing soil densification. In this work, we tested the plausibility that ice segregation or liquefaction could have been the cause of the compaction of four fragipans. Two of them are located in nonseismic areas that have experienced periglacial conditions; one is from a strongly seismic area not affected by periglacial conditions, while the fourth site underwent moderate seismic activity and slight periglacial conditions. After disaggregation in the laboratory, soil specimens…
Populated Places and Conspicuous Consumption: High Population Density Cues Predict Consumers’ Luxury-Linked Brand Attitudes
2021
Population density has been identified as an ecological factor with considerable behavioral implications. The present research aimed to examine whether the mere perception of more (vs. less) populated places can change consumers’ luxury-linked brand attitudes. To this end, we experimentally manipulated consumers’ perceptions of population density using pictorial exposure to high (vs. low) population density cues. The results revealed a significant interaction between manipulated population density and perceived brand luxury on brand attitudes. Specifically, exposure to high rather than low population density cues resulted in more positive (negative) attitudes toward brands deemed to be more…
Uncertainty quantification analysis of the biological Gompertz model subject to random fluctuations in all its parameters
2020
[EN] In spite of its simple formulation via a nonlinear differential equation, the Gompertz model has been widely applied to describe the dynamics of biological and biophysical parts of complex systems (growth of living organisms, number of bacteria, volume of infected cells, etc.). Its parameters or coefficients and the initial condition represent biological quantities (usually, rates and number of individual/particles, respectively) whose nature is random rather than deterministic. In this paper, we present a complete uncertainty quantification analysis of the randomized Gomperz model via the computation of an explicit expression to the first probability density function of its solution s…