Some error estimates for the finite volume element method for a parabolic problem

We study spatially semidiscrete and fully discrete finite volume element methods for the homogeneous heat equation with homogeneous Dirichlet boundary conditions and derive error estimates for smooth and nonsmooth initial data. We show that the results of our earlier work \cite{clt11} for the lumped mass method carry over to the present situation. In particular, in order for error estimates for initial data only in $L_2$ to be of optimal second order for positive time, a special condition is required, which is satisfied for symmetric triangulations. Without any such condition, only first order convergence can be shown, which is illustrated by a counterexample. Improvements hold for triangulations that are almost symmetric and piecewise almost symmetric

Mafic alkaline metasomatism in the lithosphere underneath East Serbia: evidence from the study of xenoliths and the host alkali basalts

Effects of mafic alkaline metasomatism have been investigated by a combined study of the East Serbian mantle xenoliths and their host alkaline rocks. Fertile xenoliths and tiny mineral assemblages found in depleted xenoliths have been investigated. Fertile lithologies are represented by clinopyroxene (cpx)-rich lherzolite and spinel (sp)-rich olivine websterite containing Ti–Al-rich Cr-augite, Fe-rich olivine, Fe–Al-rich orthopyroxene and Al-rich spinel. Depleted xenoliths, which are the predominant lithology in the suite of East Serbian xenoliths, are harzburgite, cpx-poor lherzolite and rare Mg-rich dunite. They contain small-scale assemblages occurring as pocket-like, symplectitic or irregular, deformation-assisted accumulations of metasomatic phases, generally composed of Ti–Al- and incompatible element-rich Cr-diopside, Cr–Fe–Ti-rich spinel, altered glass, olivine, apatite, ilmenite, carbonate, feldspar, and a high-TiO2 (c. 11 wt%) phlogopite. The fertile xenoliths are too rich in Al, Ca and Fe to simply represent undepleted mantle. By contrast, their composition can be reproduced by the addition of 5–20 wt% of a basanitic melt to refractory mantle. However, textural relationships found in tiny mineral assemblages inside depleted xenoliths imply the following reaction: opx+sp1 (primary mantle Cr-spinel) ±phlogopite+Si-poor alkaline melt=Ti–Al-cpx+sp2 (metasomatic Ti-rich spinel)±ol±other minor phases. Inversion modelling, performed on the least contaminated and most isotopically uniform host basanites (87Sr/86Sr=c. 0.7031; 143Nd/144Nd=c. 0.5129), implies a source that was enriched in highly and moderately incompatible elements (c. 35–40× chondrite for U–Th–Nb–Ta, 2× chondrite for heavy rare earth elements (HREE), made up of clinopyroxene, carbonate (c. 5%), and traces of ilmenite (c. 1%) and apatite (c. 0.05%). A schematic model involves: first, percolation of CO2- and H2O-rich fluids and precipitation of metasomatic hydrous minerals; and, second, the subsequent breakdown of these hydrous minerals due to the further uplift of hot asthenospheric mantle. This model links intraplate alkaline magmatism to lithospheric mantle sources enriched by sublithospheric melts at some time in the past

Charge transfer mechanism and Tc(x) dependence in Y0.8(Ca)0.2Ba2Cu3O6+x

We propose a model for charge transfer mechanism in Y0.8(Ca)0.2Ba2Cu3O6+x to count hole doping of CuO2 planes and x dependence of critical transition temperature T_c. It is assumed the total number of doped holes in the planes is sum of holes that are introduced through two separate channels: substitution of Y3+ by Ca2+ and from CuO chains that are longer than a minimal (critical) length l_min needed for charge transfer to take place. The T_c(x) dependence is obtained by combining calculated x dependence of doping, p(x), and universal T_c versus p relation. Although calculated T_c(x) dependences for l_min=3 and l_min=4 both remarkably correlate to the experimental T_c(x), we argue that the value l_min=4 gives a reasonable overall agreement.Comment: Four pages of text, 2 figures, corrected typing error in abstract: Y2+ and Ca3+ replaced by Y3+ and Ca2+. Thw word "each" added in page 3, line 4. Accepted in Superconductor Science and Technology, on 07.Apr.2008, after having been considerably revise

Recherches sur l'élimination du chlorophos-32 de l’organisme des lapins et des brebis

Petritchev M., Lazarov V. Recherches sur l’élimination du chlorophos-32 de l’organisme des lapins et des brebis. In: Bulletin de l'Académie Vétérinaire de France tome 122 n°9, 1969. pp. 889-895

Magnetic domain-wall creep driven by field and current in Ta/CoFeB/MgO

Creep motion of magnetic domain wall (DW), thermally activated DW dynamics under subthreshold driving forces, is a paradigm to understand the interaction between driven interfaces and applied external forces. Previous investigation has shown that DW in a metallic system interacts differently with current and magnetic field, manifesting itself as different universality classes for the creep motion. In this article, we first review the experimental determination of the universality classes for current- and field-driven DW creeps in a Ta/CoFeB/MgO wire, and then elucidate the underlying factors governing the obtained results. We show that the nature of torque arising from current in association with DW configuration determines universality class for the current-induced creep in this system. We also discuss the correlation between the field-induced DW creep characteristics and structure observed by a transmission electron microscope. The observed results are expected to provide a deeper understanding for physics of DW motion in various magnetic materials

Facial soft tissue thicknesses in Bulgarian adults: relation to sex, body mass index and bilateral asymmetry

Background: The aim of the study is to measure the facial soft tissue thicknesses (STTs) in Bulgarians, to evaluate the relation of the STTs to the nutritional status, sex and bilateral asymmetry, and to examine the correlations between the separate STTs as well as between the STTs and body weight, height, and body mass index (BMI). In the present study, the facial STTs were measured on computed tomography scans of the head of Bulgarian adults. Materials and methods: The STTs were measured at 7 midline and 9 bilateral landmarks. The measurements were performed in the free software InVesalius in the axial and sagittal planes. The mean, standard deviation, minimum and maximum values, median and coefficient of variation were reported for the STT at each landmark according to the sex and BMI category. The BMI, sex and bilateral differences were assessed for statistical significance. Pearson correlation analysis was applied to assess the strength and direction of the relationships between the STTs and body height, weight and BMI, as well as between separate STTs. Results and Conclusions: The facial soft tissues in Bulgarian adults changed in accordance with the nutritional status of the individual and in both sexes all STTs augmented with the increasing BMI. For both normal and overweight BMI categories, males had more soft tissue at the majority of facial points than females, as the only exceptions were observed in the cheek zone, where STTs were thicker in females. Significant bilateral differences were observed in either sex and BMI category. Stronger correlations were established for the STTs in the jaw region and between the cheek and jaw soft tissues. Besides, the correlations between the homologous bilateral landmarks were among the strongest ones

The world energy production, consumption and productivity in the energy sector, population and the per capita growth: Regression analysis

In this paper was investigated the relationship between GDP per capita growth and Log of energy production, energy consumption per capita, the log of productivity in energy sector and population. Data covered sample for 220 countries and world regions, years covered from 1980 to 2002.The results showed that if energy consumption increases by 1% GDP per capita growth will decline by 0,57%, if energy production will rise by 1% growth will rise by 1,51%, if population rise by 1% growth will decline by 0,098%, although this coefficient is statistically here below significance. If productivity in energy sector rise by 1% growth will rise by 1,32%

Ways to Reduce Water Erosion on Mountainous Slope Lands

The most important problem in the highland area is the development of technologies to reduce water erosion and improve soil fertility preservation. In order to restore degraded soils of slope lands, a number of measure is undertaken, among them planting crops across the slope and rational fertilizer treatment. To reduce erosion processes, mineral fertilizers were applied depending on the steepness of slope. High sections with the steepness of 9–10∘ received ammonium sulphate in a quantity of 60 kg/ha. Lower part of the slope with the steepness of 5–7∘ received ammonia nitrate as a nitrogen fertilizer in a quantity of 80 kg/ha, while the gentle sloping part with 2–5∘ had urea-formaldehyde fertilizer incorporated under winter tillage in a quantity of 50 kg/ha. At that, stripes were formed across the slope where tall-growing perennial herbs were planted: hill mustard (Bunias orentalis L.), silphium (Silphium perfaliatum), Eastern galega (Galeqa orientalis L.), cock’s foot grass (Dakfilis qlamerata L.). The research results have shown that thanks to fertilizers, yield of crops increases by a factor of 1.5–2, while soil losses reduced from 0.042 to 0.018 t/ha