Spin dynamics of FeGa3−x_{3-x}Gex_x studied by Electron Spin Resonance

The intermetallic semiconductor FeGa$_{3}$ acquires itinerant ferromagnetism upon electron doping by a partial replacement of Ga with Ge. We studied the electron spin resonance (ESR) of high-quality single crystals of FeGa$_{3-x}$Ge$_x$ for $x$ from 0 up to 0.162 where ferromagnetic order is observed. For $x = 0$ we observed a well-defined ESR signal, indicating the presence of pre-formed magnetic moments in the semiconducting phase. Upon Ge doping the occurrence of itinerant magnetism clearly affects the ESR properties below $\approx 40$~K whereas at higher temperatures an ESR signal as seen in FeGa$_{3}$ prevails independent on the Ge-content. The present results show that the ESR of FeGa$_{3-x}$Ge$_x$ is an appropriate and direct tool to investigate the evolution of 3d-based itinerant magnetism.Comment: 12 pages, 7 figure

Molecular biology of the kallikrein-kinin system: from structure to function

The participation of the kallikrein-kinin system, comprising the serine proteases kallikreins, the protein substrates kininogens and the effective peptides kinins, in some pathological processes like hypertension and cardiovascular diseases is still a matter of controversy. The use of different experimental set-ups in concert with the development of potent and specific inhibitors and antagonists for the system has highlighted its importance but the results still lack conclusivity. Over the last few years, transgenic and gene-targeting technologies associated with molecular biology tools have provided specific information about the elusive role of the kallikrein-kinin system in the control of blood pressure and electrolyte homeostasis. cDNA and genomic sequences for kinin receptors B2 and B1 from different species were isolated and shown to encode G-protein-coupled receptors and the structure and pharmacology of the receptors were characterized. Transgenic animals expressing an overactive kallikrein-kinin system were established to study the cardiovascular effects of these alterations and the results of these investigations further corroborate the importance of this system in the maintenance of normal blood pressure. Knockout animals for B2 and B1 receptors are available and their analysis also points to the role of these receptors in cardiovascular regulation and inflammatory processes. In this paper the most recent and relevant genetic animal models developed for the study of the kallikrein-kinin system are reviewed, and the advances they brought to the understanding of the biological role of this system are discussed.Universidade Federal de São Paulo (UNIFESP)Max-Delbrück Center for Molecular MedicineUNIFESPSciEL

Theorising the take-up of ICT : can Valsiner's three zones framework make a contribution?

This paper explores the contribution of theory to understanding the take-up of ICT and, in particular, it describes how Valsiner’s three zones framework came to be used in a study of lecturers in Saudi higher education institutions. The paper describes the value of theory and, in the process, illustrates some of the approaches taken in the literature on teachers’ use of ICT. The challenges faced in theorising are also covered. The paper then gives the background to a study of ICT use among university lecturers before moving to a discussion of methodology and presentation of key findings. Next, attention shifts to explaining key aspects of Valsiner’s zones framework and showing how this framework was applied to explain the modest but differentiated use of ICT across eight institutions. Finally, the paper discusses the strengths and limitations of the zones framework and highlights some of the wider challenges which theorisation pose