3D FEM Simulations of a shape rolling process

A finite element model has been developed for the simulation of the shape rolling of stator\ud vanes. These simulations should support the design of rolling tools for new vane types. For the time being\ud only straight vanes (vanes with a constant cross-section over the length) are studied. In that case the rolling\ud process can be considered stationary and an ALE formulation is suitable to calculate the steady state. Results\ud of simulations and experiments for a symmetrical straight vane are presente

In vitro studies of osteosarcoma: a researcher's perspective of quantity and quality

Article / Letter to editorCWT

The discovery of a new massive O-type close binary: tau CMa (HD 57061), based on HIPPARCOS and Walraven photometry

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

DC modeling of composite MOS transistors

Mixed-signal circuit design on sea-of-gates arrays requires the use of composite MOSTs, combinations of in-series and in-parallel connected unit MOSTs. To avoid an increase in circuit simulation complexity these are in general replaced by artificial single MOSTs. The analysis in this paper shows that a straightforward replacement will lead to incorrect results. Series MOSTs (in-series connected unit MOSTs) are essentially different from single MOSTs due to the presence of diffusion areas interrupting the channel at regular distances. The influence of lateral diffusion, charge sharing, and series resistance needs to be reconsidered. The theoretical results are confirmed by measurements on an experimental IC. Parameter decks of existing MOST models for circuit level simulation can be modified easily to reflect the length dependences of composite MOST parameters

In vitro studies of osteosarcoma: a researcher's perspective of quantity and quality

Merit, Expertise and Measuremen

A more reliable PCR for detection of Mycobacterium tuberculosis in clinical samples

Diagnostic techniques based on PCR have two major problems: false-positive reactions due to contamination with DNA fragments from previous PCRs (amplicons) and false-negative reactions caused by inhibitors that interfere with the PCR. We have improved our previously reported PCR based on the amplification of a fragment of the Mycobacterium tuberculosis complex-specific insertion element IS6110 with respect to both problems. False-positive reactions caused by amplicon contamination were prevented by the use of uracil-N-glycosylase and dUTP instead of dTTP. We selected a new set of primers outside the region spanned by the formerly used primers to avoid false-positive reactions caused by dTTP-containing amplicons still present in the laboratory. With this new primer set, 16 copies of the IS6110 insertion element, the equivalent of two bacteria, could be amplified 10(10) times in 40 cycles, resulting in a mean efficiency of 77% per cycle. To detect the presence of inhibitors of the Taq polymerase, which may cause false-negative reactions, part of each sample was spiked with M. tuberculosis DNA. The DNA purification method using guanidinium thiocyanate and diatoms effectively removed most or all inhibitors of the PCR. However, this was not suitable for blood samples, for which we developed a proteinase K treatment followed by phenol-chloroform extraction. This method permitted detection of 20 M. tuberculosis bacteria per ml of whole blood. Various laboratory procedures were introduced to reduce failure or inhibition of PCR and avoid DNA cross contamination. We have tested 218 different clinical specimens obtained from patients suspected of having tuberculosis. The samples included sputum (n=145), tissue biopsy samples (n=25), cerebrospinal fluid (n=15), blood (n=14), pleural fluid (n=9), feces, (n=7), fluid from fistulae (n=2), and pus from a wound (n=1). The results obtained by PCR were consistent with those obtained with culture, which is the "gold standard." We demonstrate that PCR is a useful technique for the rapid diagnosis of tuberculosis at various sites