How content analysis may complement and extend the insights of discourse analysis: an example of research on constructions of abortion in South African newspapers 1978–2005

Although discourse analysis is a well-established qualitative research methodology, little attention has been paid to how discourse analysis may be enhanced through careful supplementation with the quantification allowed in content analysis. In this article, we report on a research study that involved the use of both Foucauldian discourse analysis (FDA) and directed content analysis based on social constructionist theory and our qualitative research findings. The research focused on the discourses deployed, and the ways in which women were discursively positioned, in relation to abortion in 300 newspaper articles, published in 25 national and regional South African newspapers over 28 years, from 1978 to 2005. While the FDA was able to illuminate the constitutive network of power relations constructing women as subjects of a particular kind, questions emerged that were beyond the scope of the FDA. These questions concerned understanding the relative weightings of various discourses and tracing historical changes in the deployment of these discourses. In this article, we show how the decision to combine FDA and content analysis affected our sampling methodology. Using specific examples, we illustrate the contribution of the FDA to the study. Then, we indicate how subject positioning formed the link between the FDA and the content analysis. Drawing on the same examples, we demonstrate how the content analysis supplemented the FDA through tracking changes over time and providing empirical evidence of the extent to which subject positionings were deployed

A physical-based approach for modeling cycle-to-cycle variations within a zero-dimensional/one-dimensional simulation environment

In the spark-ignition engine development and optimization process, the cyclic variability of combustion is an essential and current issue. Cycle-to-cycle variations are extensively investigated by means of quasi-dimensional (zero-dimensional/one-dimensional) simulation modeling. To date, these model approaches have been limited either because they neglected particularly significant physical causes and factors influencing cyclic combustion variations or because of their solely empirical combustion modeling basis. However, in order to ensure the high validity of simulation results, quasi-dimensional model approaches have to accurately describe the physical background of engine combustion. Therefore, a new cyclic combustion variation model is introduced in this study. This cycle-to-cycle variation model is based on previously developed, highly sophisticated physical turbulence, ignition and combustion models, thus for the first time enabling the physical description of cycle-to-cycle variation. The model integrates the most significant physical causes of combustion variations and the factors which influence them, obtained from a literature study. Hence, the derived cycle-to-cycle variation model can physically react to changes in engine parameters such as the engine speed, load, spark timing, valve lift and timing as well as the air–fuel equivalence ratio λ. For validation, the new cycle-to-cycle variation model is compared to a state-of-the-art cycle-to-cycle variation model and analyzed by means of engines with different combustion processes. This new cycle-to-cycle variation model uniquely features the physical background of the underlying combustion model and the integration of more influencing factors than in previous approaches. Another unique feature is its basis on extensive experimental data, gained by changing various engine parameters for homogeneous charge spark-ignition engines with different combustion/engine concepts. These include engines with high turbulence generation or a long expansion stroke via crank and valve train

Giant Traps Associated with Extended Defects in GaN and SIC

Extended defects in semiconductors can trap charge and lead to changes in carrier concentration and mobility. Here we consider the trapping effects of pores, microcracks, and dislocations in GaN and SiC, as analyzed by deep level transient spectroscopy (DLTS), transmission electron microscopy (TEM), and scanning surface potential microscopy (SSPM). The defect structures are modeled as spheres, plates, and cylinders for pores, cracks, and dislocations, respectively, and their potentials are directly compared with those measured by holographic TEM and SSPV. The dynamics of the capture and emission processes are investigated by DLTS, although the standard DLTS analysis framework is not applicable here and must be replaced by a more general formalism. As an example, 40-nm-dia. nanopores in SiC can each hold more than 100 electrons, and they exhibit anomalous capture and emission properties. (c) 2005 WILEY-VCH Verlag GmbH E Co. KGaA, Weinheim

Giant Traps Associated with Extended Defects in GaN and SIC

Extended defects in semiconductors can trap charge and lead to changes in carrier concentration and mobility. Here we consider the trapping effects of pores, microcracks, and dislocations in GaN and SiC, as analyzed by deep level transient spectroscopy (DLTS), transmission electron microscopy (TEM), and scanning surface potential microscopy (SSPM). The defect structures are modeled as spheres, plates, and cylinders for pores, cracks, and dislocations, respectively, and their potentials are directly compared with those measured by holographic TEM and SSPV. The dynamics of the capture and emission processes are investigated by DLTS, although the standard DLTS analysis framework is not applicable here and must be replaced by a more general formalism. As an example, 40-nm-dia. nanopores in SiC can each hold more than 100 electrons, and they exhibit anomalous capture and emission properties. (c) 2005 WILEY-VCH Verlag GmbH E Co. KGaA, Weinheim

Local P-Type Conductivity in N-GaN and N-ZnO Layers Due to Inhomogeneous Dopant Incorporation

We report on scanning capacitance microscopy (SCM) investigations of Fe-doped GaN and nitrogen-doped ZnO layers. Macroscopically, these samples electrically behave in conventional I-V and C-V measurements like semi-insulating or n-type material, respectively. However, in SCM we found local p-type regions surrounded by an n-type matrix instead of homogeneous and uniform layer conductivity. A comparison with topography reveales that these p-type islands with extensions in the micrometer scale exclusively appear in the vicinity of structural defects and grain boundaries. This doping related effect is discussed in terms of selective dopant incorporation at these defects. (c) 2005 Elsevier B.V. All rights reserved

III–V quantum light source and cavity-QED on Silicon

Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects, is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon’s indirect band-gap. III–V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III–V material grown directly on silicon substrates. The high quality of the III–V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems

Giant Traps on the Surface of Hydride Vapor Phase Epitaxy-Grown Free-Standing GaN

Extended defects on the top surface of a 250-µm-thick free-standing GaN sample, grown by hydride vapor phase epitaxy (HYPE), were studied by deep level transient spectroscopy (DLTS) and scanning surface potential microscopy (SSPM). For comparison, similar studies were carried out on as-grown HVPE-GaN samples. In addition to the commonly observed traps in as-grown HYPE-GaN, the DLTS measurements on free-standing GaN reveal a very high concentration of deep traps (similar to 1.0 eV) within about 300 nm of the surface. These traps show nonexponential capture kinetics, reminiscent of those associated with large defects, that can accumulate multiple charges. The SSPM measurements clearly reveal the presence of charged microcracks on the top surface of the sample. It appears that the giant traps may be associated with these microcracks, but we cannot rule out the involvement of other extended defects associated with the near-surface damage caused by the polishing/etching procedure

Local P-Type Conductivity in N-GaN and N-ZnO Layers Due to Inhomogeneous Dopant Incorporation

We report on scanning capacitance microscopy (SCM) investigations of Fe-doped GaN and nitrogen-doped ZnO layers. Macroscopically, these samples electrically behave in conventional I-V and C-V measurements like semi-insulating or n-type material, respectively. However, in SCM we found local p-type regions surrounded by an n-type matrix instead of homogeneous and uniform layer conductivity. A comparison with topography reveales that these p-type islands with extensions in the micrometer scale exclusively appear in the vicinity of structural defects and grain boundaries. This doping related effect is discussed in terms of selective dopant incorporation at these defects. (c) 2005 Elsevier B.V. All rights reserved