Search for the magnetic field of the O7.5 III star xi Persei

Cyclical wind variability is an ubiquitous but as yet unexplained feature among OB stars. The O7.5 III(n)((f)) star xi Persei is the brightest representative of this class on the Northern hemisphere. As its prominent cyclical wind properties vary on a rotational time scale (2 or 4 days) the star has been already for a long time a serious magnetic candidate. As the cause of this enigmatic behavior non-radial pulsations and/or a surface magnetic field are suggested. We present a preliminary report on our attempts to detect a magnetic field in this star with high-resolution measurements obtained with the spectropolarimeter Narval at TBL, France during 2 observing runs of 5 nights in 2006 and 5 nights in 2007. Only upper limits could be obtained, even with the longest possible exposure times. If the star hosts a magnetic field, its surface strength should be less than about 300 G. This would still be enough to disturb the stellar wind significantly. From our new data it seems that the amplitude of the known non-radial pulsations has changed within less than a year, which needs further investigation.Comment: 2 pages, 6 figures, contributed poster at IAU Symposium 259 "Cosmic Magnetic Fields: from Planets, to Stars and Galaxies", Tenerife, Spain, November 3-7, 200

A Firm-Specific Analysis of the Exchange-Rate Exposure of Dutch Firms

We examine the relationship between exchange-rate changes and stockreturns for a sample of Dutch firms over 1994-1998. We find that over50% of the firms are significantly exposed to exchange-rate risk.Furthermore, all firms with significant exchange-rate exposure benefitfrom a depreciation of the Dutch guilder relative to a trade-weightedcurrency index. This result confirms that firms in open economies,such as the Netherlands, exhibit significant exchange-rate exposure.We collect unique information on the most relevant individualcurrencies for each firm with respect to their influence on firmvalue. Our results indicate that the use of a trade-weighted currencyindex and the use of individual exchange rates are complements. Wealso measure the determinants of exchange-rate exposure. As expected,we find that firm size and the foreign sales ratio are significantlyand positively related to exchange-rate exposure. In contrast with ourhypothesis, off-balance hedging using derivatives has no significanteffects. Finally, in line with theory, we find that exposure issignificantly reduced through on-balance sheet hedging, i.e. throughforeign loans and by producing in factories abroad.risk management;The Netherlands;foreign exchange rates;international finance;exposure measurement

Two small-volume electrochemical cells for the measurement of surface enhanced Raman scattering

Two electrochemical cells, for performing surface enhanced Raman scattering (SERS), with submillilitre volumes are presented. One of the cells is especially developed for use in a Raman microspectrometer. The smallest cell uses only 80 mu l of sample. SER measurements are performed on 2*10-3 M adenine