Prospective single and multi-phase short-circuit current levels in the Dutch transmission, sub-transmission and distribution grids

As elsewhere in the world, also in the Netherlands utilities face an increase in the actual and future short-circuit current levels at all voltages. This development is provoked by the required increase in transmission capacity as well as the concentration of power generation capacity. Large electricity production sites are moved to peripheral locations, thus overstressing the local transmission networks with respect to both the transmission capacity and the short-circuit power withstand capability. Dispersed power generation facilities, like windmills and co-generation plants for greenhouses, tend to appear in the same (optimal) neighborhoods, thus overstressing the local distribution and subtransmission networks. In the paper the development of short-circuit currents in the Dutch 400 kV-grid is illustrated. In addition, some particular aspects of the short-circuit currents will be addressed: three-phase and single phase fault currents, DC-time constants, peak values, contributions from transformers and distributed generators. Practical calculation guidelines on the actual short-circuit contribution from generators will be given. An example of design of a 400 kV station extension, emphasizing short-circuit current considerations is evaluated. National and international trends are addressed. More severe specifications of substation equipment lead to adapted designs and adequate testing procedures. Examples from testing of the consequences of short-circuit currents and fault arcs of 80 kA and above are highlighted

The cardiac sodium channel displays differential distribution in the conduction system and transmural heterogeneity in the murine ventricular myocardium

Cardiac sodium channels are responsible for conduction in the normal and diseased heart. We aimed to investigate regional and transmural distribution of sodium channel expression and function in the myocardium. Sodium channel Scn5a mRNA and Na(v)1.5 protein distribution was investigated in adult and embryonic mouse heart through immunohistochemistry and in situ hybridization. Functional sodium channel availability in subepicardial and subendocardial myocytes was assessed using patch-clamp technique. Adult and embryonic (ED14.5) mouse heart sections showed low expression of Na(v)1.5 in the HCN4-positive sinoatrial and atrioventricular nodes. In contrast, high expression levels of Na(v)1.5 were observed in the HCN4-positive and Cx43-negative AV or His bundle, bundle branches and Purkinje fibers. In both ventricles, a transmural gradient was observed, with a low Na(v)1.5 labeling intensity in the subepicardium as compared to the subendocardium. Similar Scn5a mRNA expression patterns were observed on in situ hybridization of embryonic and adult tissue. Maximal action potential upstroke velocity was significantly lower in subepicardial myocytes (mean +/- SEM 309 +/- 32 V/s; n = 14) compared to subendocardial myocytes (394 +/- 32 V/s; n = 11; P < 0.05), indicating decreased sodium channel availability in subepicardium compared to subendocardium. Scn5a and Na(v)1.5 show heterogeneous distribution patterns within the cardiac conduction system and across the ventricular wall. This differential distribution of the cardiac sodium channel may have profound consequences for conduction disease phenotypes and arrhythmogenesis in the setting of sodium channel diseas

Tbx2 and Tbx3 induce atrioventricular myocardial development and endocardial cushion formation

A key step in heart development is the coordinated development of the atrioventricular canal (AVC), the constriction between the atria and ventricles that electrically and physically separates the chambers, and the development of the atrioventricular valves that ensure unidirectional blood flow. Using knock-out and inducible overexpression mouse models, we provide evidence that the developmentally important T-box factors Tbx2 and Tbx3, in a functionally redundant manner, maintain the AVC myocardium phenotype during the process of chamber differentiation. Expression profiling and ChIP-sequencing analysis of Tbx3 revealed that it directly interacts with and represses chamber myocardial genes, and induces the atrioventricular pacemaker-like phenotype by activating relevant genes. Moreover, mutant mice lacking 3 or 4 functional alleles of Tbx2 and Tbx3 failed to form atrioventricular cushions, precursors of the valves and septa. Tbx2 and Tbx3 trigger development of the cushions through a regulatory feed-forward loop with Bmp2, thus providing a mechanism for the co-localization and coordination of these important processes in heart development

Pioneering disadvantage : consumer reactions to marketing mix strategies / M. Sadiq Sohail and Mohamad Farid Mahmood

Prior research has focused on the early entrant advantage, although a growing body of knowledgde suggests suggests that late movers have been outselling pioneers. In this research, the authors examine the issue of a pay phone service provider in Malaysia. In 1990, the company launches its product and creates an industry, but by the turn of the century, it has a meager 17 per cent of the market share. The Paper examines the specific issue of how a market pioneer has been eclipsed. It is hypothesized that the main cause of the declining sales is the in appropriate marketing mix strategies. The major findings based on a survey include consumers' acceptance level of the product, price, place, promotion, people, process and physical evidence strategies of the company

Sox4 mediates Tbx3 transcriptional regulation of the gap junction protein Cx43

Tbx3, a T-box transcription factor, regulates key steps in development of the heart and other organ systems. Here, we identify Sox4 as an interacting partner of Tbx3. Pull-down and nuclear retention assays verify this interaction and in situ hybridization reveals Tbx3 and Sox4 to co-localize extensively in the embryo including the atrioventricular and outflow tract cushion mesenchyme and a small area of interventricular myocardium. Tbx3, SOX4, and SOX2 ChIP data, identify a region in intron 1 of Gja1 bound by all tree proteins and subsequent ChIP experiments verify that this sequence is bound, in vivo, in the developing heart. In a luciferase reporter assay, this element displays a synergistic antagonistic response to co-transfection of Tbx3 and Sox4 and in vivo, in zebrafish, drives expression of a reporter in the heart, confirming its function as a cardiac enhancer. Mechanistically, we postulate that Sox4 is a mediator of Tbx3 transcriptional activity

The role of Tbx2 in the development of the atrioventriculair canal and conduction system of the heart. `Making the beat go on and on`

Het atrioventriculaire kanaal verbindt boezems en kamers in het embryonale hart. Daarnaast is het betrokken bij de scheiding van het hart in een linker- en rechterdeel. Het gen Tbx2 speelt een belangrijke rol in de ontwikkeling van het kanaal. Wim Aanhaanen deed onderzoek naar dit gen. Hij laat zien dat als het gen wordt uitgeschakeld, dit kan leiden tot ritmestoornissen in het volwassen hart

Transformatie van verzorgingstehuizen uit de jaren '60

VeldacademieArchitectureArchitecture and The Built Environmen

The stability of a facetted glass shell structure

The Master’s thesis has focussed on the stability of a facetted shell structure. The research contributes to a Ph.D. research currently carried out at the Technical University of Denmark (DTU), which investigates the possibilities to design and build a shell structure from flat glass panels. The structure is a so-called plate (facetted) structure, which is a relatively unknown, though very efficient structure type. By combining this structural typology with laminated float glass, a very transparent structure becomes possible. Since smooth shell structures are prone to buckling, it is very important to assess the behaviour of the glass facetted structure in this respect. During the research different aspects that are important for the stability of the structure have been investigated using a finite element model. Important was for instance the sensitivity of the structure to imperfections. Furthermore, the influence of the stiffness of the joints between the glass facets turns out to play an important role in the behaviour of the structure. Especially the normal stiffness (k_n) is vital, while the bending stiffness (k_m) is less important. Other aspects that have been considered are the robustness of the structure and the influence of the stiffness of the panels. The research has shown that the structural system and its combination with laminated float glass looks very promising.Design and ConstructionCivil Engineering and Geoscience