Now showing items 11-20 of 588
The ‘forma specialis’ issue in Fusarium: A case study in Fusarium solani f. sp. pisi
The Fusarium solani species complex (FSSC) has been studied intensively but its association with legumes, particularly under European agro-climatic conditions, is still poorly understood. In the present study, we investigated phylogenetic relationships and aggressiveness of 79 isolates of the FSSC collected from pea, subterranean clover, white clover and winter vetch grown under diverse agro-climatic and soil conditions within Temperate and Mediterranean Europe. The isolates were characterized by sequencing tef1 and ...
Introducing the Logarithmic finite element method: a geometrically exact planar Bernoulli beam element
We propose a novel finite element formulation that significantly reduces the number of degrees of freedom necessary to obtain reasonably accurate approximations of the low-frequency component of the deformation in boundary-value problems. In contrast to the standard Ritz–Galerkin approach, the shape functions are defined on a Lie algebra—the logarithmic space—of the deformation function. We construct a deformation function based on an interpolation of transformations at the nodes of the finite element. In the case ...
Microscale-Motivated Continuum Damage Simulations of Brittle Ceramics under Thermomechanical Loading
Two approaches towards modeling damage in a brittle material caused by thermomechanical loading are presented. Bothrelyonmicrocrack growth, in the first case in ahomogeneousmatrix, in the second one at grain boundaries.Two-scale simulations e.g. of thermal shocks applied to single-phase or layered structures are performed in connection with the finite element method. Damage and crack patterns are predicted just as quantities like residual strength or critical temperature jumps.
Wünschenswerte Erschwernisse beim Lernen
Der Beitrag beleuchtet didaktische Maßnahmen, die unter dem Begriff „Wünschenswerte Erschwernisse“ zusammengefasst werden. Diese Maßnahmen erschweren zwar kurzfristig das Lernen, langfristig aber fördern sie das Behalten und den Transfer des Gelernten. Vier dieser wünschenswerten Erschwernisse sind empirisch besonders gut belegt: 1) Das verteilte Lernen, 2) das verschachtelte Lernen, 3) der Testungseffekt und 4) der Generierungseffekt. Zu jeder dieser wünschenswerten Erschwernisse werden aktuelle Forschungsergebnisse ...
Emerging Development Pathways of Urban Livestock Production in Rapidly Growing West Africa Cities
In this study, we try to capture the degree of specialization or integration, and of intensification or extensification, of (peri-) urban livestock production, along with the factors that influence such decisions and their impact on natural resource uses. A total of 181 and 187 structured questionnaires were completed in livestock-keeping households in Ouagadougou (Burkina Faso) and Tamale (Ghana). Categorical principal component and two-step cluster analysis were used to identify homogenous groups of livestock-keeping ...
Boxwood Borer Heterobostrychus brunneus (Coleoptera: Bostrichidae) Infesting Dried Cassava: A Current Record from Southern Ethiopia
Insect specimens of adult beetles and larvae of 7–9 and 9–10 mm length, respectively were collected from infested dry cassava at two locations from multiple stores in southern Ethiopia. The specimens were identified as Heterobostrychus brunneus (Murray, 1867) commonly known as boxwood borer and auger beetle. The study presents a current record of H. brunneus in Ethiopia, particularly in the context of infesting food products. Additionally, a wide geographical distribution of the pest was reviewed and presented in ...
Crack Paths at Multiple-crack Systems in Anisotropic Simulation and Experiment
This paper is targeted on numerical methods for accurate crack tip loading analysis and crack path prediction. Those are based on finite element calculations of the boundary value problem. Applying path-independent integrals to curved cracks in order to accurately calculate the J-integral, energy release rate (ERR) or stress intensity factors (SIF) is still not state of the art. Contours which are not confined to the crack tip require special analytical preparation and numerical treatment to supply results which are ...
Applying Least Absolute Shrinkage Selection Operator and Akaike Information Criterion Analysis to Find the Best Multiple Linear Regression Models between Climate Indices and Components of Cow’s Milk
This study focuses on multiple linear regression models relating six climate indices (temperature humidity THI, environmental stress ESI, equivalent temperature index ETI, heat load HLI, modified HLI (HLI new), and respiratory rate predictor RRP) with three main components of cow’s milk (yield, fat, and protein) for cows in Iran. The least absolute shrinkage selection operator (LASSO) and the Akaike information criterion (AIC) techniques are applied to select the best model for milk predictands with the smallest ...
Effect of Auger recombination and leakage on the droop in InGaN/GaN quantum well LEDs
(Optical Society of America, 2014)
We investigate the effect of the epitaxial structure and the acceptor doping profile on the efficiency droop in InGaN/GaN LEDs by the physics based simulation of experimental internal quantum efficiency (IQE) characteristics. The device geometry is an integral part of our simulation approach. We demonstrate that even for single quantum well LEDs the droop depends critically on the acceptor doping profile. The Auger recombination was found to increase stronger than with the third power of the carrier density and has ...
Sustainable rural development in Ukraine: Legal aspect
(Section Specialized Partnerships in Sustainable Food Systems and Food Sovereignty at the University of Kassel, Germany and Federation of German Scientists (VDW), 2018-12-26)
Sustainable rural development involves the attainment of a balanced development of the economic, ecological and social spheres within a community. For this purpose, the state agrarian policy should be aimed at achieving three goals: 1) food security of the state; 2) solving of social and environmental problems in rural areas; and, 3) the transformation of the agrarian sector into a highly effective, competitive domestic and foreign market economy sector of the state. Therefore, the purpose of the article is to study ...