On the Accuracy of Equivalent Antenna Representations

The accuracy of two equivalent antenna representations, near-field sources and far-field sources, are evaluated for an antenna installed on a simplified platform in a series of case studies using different configurations of equivalent antenna representations. The accuracy is evaluated in terms of installed far-fields and surface currents on the platform. The results show large variations between configurations. The root-mean-square installed far-field error is 4.4% for the most accurate equivalent representation. When using far-field sources, the design parameters have a large influence of the achieved accuracy. There is also a varying accuracy depending on the type of numerical method used. Based on the results, some recommendations on the choice of sub-domain for the equivalent antenna representation are given. In industrial antenna applications, the accuracy in determining e.g. installed far-fields and antenna isolation on large platforms are critical. Equivalent representations can reduce the fine-detail complexity of antennas and thus give an efficient numerical descriptions to be used in large-scale simulations. The results in this paper can be used as a guideline by antenna designers or system engineers when using equivalent sources

Slutrapport: Mentor - adeptprogram för lärosäten

Två större lärosäten (mentorerna Högskolan i Gävle och Örebro universitet) ska på ett systematiskt sätt låta storleksmässigt små lärosäten, adepterna, ta del av deras erfarenhet och kompetens inom området IT-stödd distansutbildning. Mentorsprogrammet ger adeptlärosätena bättre kunskap om Nätuniversitetets verksamhet är önskvärd för deras egen del. Inbjudan har gått till Danshögskolan, Dramatiska institutet, Idrottshögskolan, Konstfack, Konsthögskolan, Musikhögskolan, Operahögskolan, Teaterhögskolan, och Ersta Sköndal högskola

KTH Royal Institute of Technology

Maria Malmström - Industrial Ecology, KTH Discussion of the KTH Royal Institute of Technology in SwedenOpe

Erythropoietin production by fetal mouse liver cells in response to hypoxia and adenylate cyclase stimulation

This study was done to investigate aspects of control of extrarenal erythropoietin (Ep) production. To this end we studied the effects of three stimuli of renal Ep production in the adult, i.e. hypoxia, cobalt, and activation of adenylate cyclase on Ep generation by cultured fetal mouse liver cells. The fetal liver was taken as a model for extrarenal Ep production because this organ is considered the predominant site of extrarenal Ep production. We found that Ep production by the cells increased as the oxygen concentration was decreased in the incubation atmosphere from 20% to 1%. Cobalt (10(-4)-10(-5) M) had no effect on Ep production. Activation of adenylate cyclase by forskolin (10(-5) M) or isoproterenol (10(-5) M) greatly enhanced Ep production. These findings indicate that the Ep-stimulating effect of cobalt is specific for the kidney. However, oxygen depletion and activation of adenylate cyclase seem to be more general stimuli in Ep-producing cells. Furthermore we found that Ep production in hypoxia correlated with lactate formation in the cultured liver cells. This finding suggests that Ep production in fetal livers under hypoxic conditions parallels the shift from aerobic to anaerobic cellular energy metabolism

The ties that bind - An exploratory study of social capital in peacebuilding initiatives in Guatemala

This thesis investigates the relationship between social capital and peacebuilding, and the potential contribution peacebuilding efforts can make in terms of generating social capital in post-conflict countries. Using a qualitative methodological approach, seven local civil society organizations in Guatemala were interviewed with the purpose of understanding in what way the organizations are contributing to the generation of social capital. The material was examined through an analytical framework consisting of three social capital dimensions and seven peacebuilding functions in order to explore the activities of the organizations and what dimensions of social capital that is expressed in their activities. The study finds that the organizations are engaged in several peacebuilding functions and are focusing their work through these functions towards generating bridging and linking social capital in Guatemala

Accountability and the making of knowledge statements : a study of academic discourse

This study investigates the manifestation of speaker accountability in connection with knowledge statements in two different kinds of academic discourse. The study focuses on knowledge statements which feature a set of knowledge stating verbs, namely argue, claim, suggest, propose, maintain, assume and believe. A corpus is used as the empirical basis and a general metadiscursive approach primarily informed by ideas from a recent account of metadiscourse (Hyland 2005a) is adopted (combined with reasoning from dialogic frameworks, e.g. Todorov 1984, Bakhtin 1999). The study falls into four parts: First, the study establishes what it is in the utterance that affects the manifestation of speaker accountability in connection with knowledge statements; speaker accountability is associated with how vocally present or absent speakers are in their texts at the particular point of the knowledge statement, i.e. as connected to the concept of discourse voice. Discourse voice maps directly onto a scalar conception of accountability and a model describing this interactive relationship is proposed. Second, the study investigates differences between the knowledge stating verbs selected with respect to their occurrence in typical accountability contexts (i.e. contexts in which speakers are accountable to different degrees). The result of the corpus investigation indicates that the verbs investigated display significant differences in terms of typical accountability contexts. For example, believe is found to be a typical High accountability verb whereas claim is typically found in Low accountability contexts and suggest occurs as a typical Medium-to-High accountability verb. Third, the study also investigates potential differences in the typical accountability contexts of the knowledge stating verbs across two different academic disciplines. The corpus is divided into two sub-corpora, one part featuring texts from two linguistic journals and the other part featuring texts from two journals of literary theory and literary history. The outcome of the investigation is that there are few significant differences across the two sub-corpora. Knowledge stating verbs appear to occur in similar kinds of accountability contexts in linguistic and in literary texts. Finally, the study addresses the issue of what accountability is, i.e. its status in a theory of language. It is established that accountability can be explained by appeal to social knowledge. Such social knowledge is addressed at the level of metadiscourse in communication. The discussion leads to the proposal of a layered concept of metadiscourse where accountability is claimed to be directly associated with higher-level metadiscourse

Chewing up the wood-wide web : selective grazing on ectomycorrhizal fungi by collembola

This work was supported by the Natural Environment Research Council (NE/C507510/1). We thank S. Van der Linde, A. Sim, L. Shivraj, and P. Parkin.Peer reviewedPublisher PD

Mechanism of NaCl transport-stimulated prostaglandin formation in MDCK cells

Recently we have found that stimulation of NaCl transport in high-resistance MDCK cells enhances their prostaglandin formation. In the present study, we investigated the mechanisms by which prostaglandin formation could be linked to the ion transport in these cells. We found that stimulation of transport caused a transient stimulation of prostaglandin formation lasting 5-10 min. The rise in prostaglandin formation was paralleled by a rise of free intracellular arachidonic acid. Analysis of membrane lipids revealed that the rise of free arachidonic acid was paralleled by a loss of arachidonic acid from polyphosphoinositides. We failed to obtain indications for the stimulation of calcium-dependent phospholipase A2. However, we did obtain evidence that the incorporation of arachidonic acid into phospholipids was diminished during stimulation of ion transport, indicating a decreased rate of reesterification. Despite the fact that there was no significant fall in total cellular ATP on stimulation of ion transport, we found a high and transient rise of lactate production of the cells on stimulation of the ion transport indicating an alteration of the ADP/ATP ratio. Moreover, prostaglandin formation and lactate formation were linearly correlated in this situation. When glucose utilization was inhibited by mannoheptulose, the rise in lactate formation was abolished, whereas that of PG formation was unaltered, indicating that lactate formation and prostaglandin formation were not causally linked on stimulation of ion transport. Our results suggest that an increase in the rate of sodium chloride transport by MDCK cells stimulates formation by an inhibition of reesterification of free arachidonic acid.(ABSTRACT TRUNCATED AT 250 WORDS

2DDB – a bioinformatics solution for analysis of quantitative proteomics data

BACKGROUND: We present 2DDB, a bioinformatics solution for storage, integration and analysis of quantitative proteomics data. As the data complexity and the rate with which it is produced increases in the proteomics field, the need for flexible analysis software increases. RESULTS: 2DDB is based on a core data model describing fundamentals such as experiment description and identified proteins. The extended data models are built on top of the core data model to capture more specific aspects of the data. A number of public databases and bioinformatical tools have been integrated giving the user access to large amounts of relevant data. A statistical and graphical package, R, is used for statistical and graphical analysis. The current implementation handles quantitative data from 2D gel electrophoresis and multidimensional liquid chromatography/mass spectrometry experiments. CONCLUSION: The software has successfully been employed in a number of projects ranging from quantitative liquid-chromatography-mass spectrometry based analysis of transforming growth factor-beta stimulated fi-broblasts to 2D gel electrophoresis/mass spectrometry analysis of biopsies from human cervix. The software is available for download at SourceForge