Proposal for a race-track microtron with high peak current

In order to obtain high gain in a free electron laser a high-quality electron beam with high peak current is required. It is well-known that a microtron is able to produce a high-quality beam having low emittance and small energy spread (1%). Because a circular microtron has a limited high-current capability a race-track design is adopted for providing flexibility, better beam quality and of course higher peak current in the microbunch. Space charge problems may be severe in a microtron. It can be shown that bunching on certain specific subharmonic frequencies will lead to a strong reduction of the space charge problems. The general layout of our microtron design will be presented. The characteristics are: energy 25 MeV, micropulse 10° of the rf frequency of 3 GHz. Our aim is to come beyond the present state of the art with the following characteristics: relative energy spread 0.001, emittance 3 mm mrad, current in the micropulse 100 A, macropulse length 50 μs and subharmonic bunching at 1:64

Thermodynamics of polymolecular duplexes between phosphate-methylated DNA and natural DNA

Phosphate-methylated (P.M.) DNA possesses a very high affinity for complementary natural DNA, as a result of the absence of interstrand electrostatic repulsions. In this study, a model system phosphate-methylated d[Cn] with natural d(Gk) (n <k)is chosen for an investigation of the thermodynamic properties that determine duplex stability. The enthalpy change of a melting transition is shown to be considerably larger than is observed for corresponding natural DNA duplexes. It is found that H of GG/CC nearest neighbor pairwise interaction equals -15.6 kcal/mol, compared to -11.0 kcal/mol for the natural analog. The entropy change is strongly dependent on the length of the natural DNA strand and the number of phosphate-methylated DNA oligomers hybridized. The results are explained by means of a model in which a cooperative effect for subsequent hybridizations of phosphate-methylated DNA oligomers is assumed, thus giving additional stability

Acquired von Willebrand disease as a cause of recurrent mucocutaneous bleeding in primary thrombocythemia: Relationship with platelet count

We present a 4-year follow-up of a 42-year-old patient with primary thrombocythemia whose clinical course was complicated by two major mucocutaneous bleeding episodes. On both occasions an acquired functional von Willebrand factor deficiency was demonstrated. In contrast to what is reported in the literature, an inverse relationship between platelet number and plasma high-molecular-weight multimers of von Willebrand factor was established

The enigmatic WR46: A binary or a pulsator in disguise. III. Interpretation

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

The enigmatic WR46: A binary or a pulsator in disguise. II. The spectroscopy

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

A simple and fast method to exclude high Plasmodium falciparum parasitaemia in travellers with imported malaria

Background: Counts of malaria parasites in peripheral blood are important to assess severity of Plasmodium falciparum malaria. Thin and thick smears are routinely used for this purpose. Methods. In this study the Binax NOW® Malaria Test, an easy-to-perform rapid diagnostic test, with Histidine Rich Protein-2 (HRP-2) and aldolase as diagnostic markers, was used for semi-quantitative assessment of parasitaemia of P. faciparum. Results: In 257 patients with imported P. falciparum malaria, reactivity of aldolase increased with higher parasitaemia. In all patients with a parasitaemia above 50,000 asexual parasites/l (> 1%) co-reactivity of HRP-2 and aldolase was observed. Absence of aldolase reactivity in the presence of HRP-2 was a reliable predictive marker to exclude high (> 1%) parasitaemia in P. falciparum malaria. Conclusions: Assessment of HRP-2 and aldolase co-reactivity can be of help in clinical decision making in the acute care setting of returning travellers suspected of having malaria

On the variability of the visual binary WR86. WC7 with a β-Cephei companion

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe