A first-overtone RR Lyrae star with cyclic period changes

A detailed light curve analysis is presented for a first-overtone RR Lyrae star, MACHO* J050918.712-695015.31, based on MACHO and OGLE-III observations. As a foreground object of the Large Magellanic Cloud, it gives an extraordinary opportunity to study an almost continuous, 12-year long dataset of a relatively bright (V~15.0 mag) RRc star with rapid period change. Cyclic period modulation is suggested by the O-C method, where the cycle length is about 8 years. With the available unique dataset, we could draw strong limits on other light curve changes that may be associated to the period modulation. We could exclude both multiple periodicity and amplitude modulation unambiguously. Any theoretical model should reproduce the observed lack of photometric modulations. Simple arguments are also given for possible hydromagnetic effects.Comment: 6 pages, 6 figures, accepted for publication in MNRA

Are there any abnormal returns for early moving companies? An event study analysis of Greek companies

This study examines the phenomenon of the early moving companies. 50 Greek companies of high capitalisation enlisted in the Athens Stock Exchange are tested as to whether their intention to merge with or acquire another company in the South-Eastern European region provides them with positive abnormal returns. The methodology and model used is the Event studies method and the Market Model. There were 109 events examined, an event being the day when the intention to invest was known to the public. Results show neither positive nor negative abnormal returns for the sample companies, being in partial agreement with the literature.early movers; abnormal returns; market models; early moving companies; Greece; high capitalisation; Athens stock exchange; mergers; acquisitions; M&A; South-Eastern Europe; event studies; investments.

Ianos—A Hurricane in the Mediterranean

International audienceDuring 15-21 September 2020, an intense medicane, named Ianos, formed over the warm Mediterranean Sea. Following a path of approximately 1,900 km, Medicane Ianos affected Greece resulting in four casualties and devastating damage in the western and central parts of Greece. Persistent gale force 1-min winds up to 44 m s−1 and wind gusts up to 54 m s−1 were recorded in Cephalonia Island (Ionian Sea), while record-breaking amounts of accumulated rainfall have been recorded in several Ionian islands, as well as in parts of central Greece. Analysis of the available observations showed that Ianos was the most intense medicane ever recorded in the Mediterranean. This paper aims at investigating the genesis and evolution of the medicane, based on in situ observations, satellite measurements, and model analyses. Toward that objective, Meteosat Second Generation (MSG) SEVIRI imagery, combined with lightning data permitted to follow the evolution of convective activity during the various phases of Ianos. This investigation is complemented with upper-air model analyses in order to evaluate the synoptic environment within which Ianos had formed and was sustained over 7 days. Finally, the Global Precipitation Measurement Core Observatory (GPM CO) satellite overpasses over Medicane Ianos provided invaluable information about its 3D structure, especially during its most intense phase

The effect of in vitro homocystinuria on the suckling rat hippocampal acetylcholinesterase

Homocystinuria is due to enzymatic deficiencies resulting in elevated blood levels of homocysteine (Hcy), homocystine (Hci), and/or methionine (Met) and the clinical presentation of mental retardation, seizures, and cardiovascular disease. Since these symptoms may be closely implicated with acetylcholinesterase (AChE) activity, we aimed to investigate whether this metabolic disorder affects the hippocampal AChE activity in 21 days suckling Wistar rat hippocampus. Various concentrations of Hcy, Hci (0.05-0.5 mM), or Met (0.05-2 mM) as well as Mixture A (Mix A) (0.3 mM (Hcy)+0.2 mM (Hci)+1.0 mM (Met) = in vitro cystathionine β-synthase deficiency homocystinuria), Mix B1 (Hcy 0.3 mM + Hci 0.2 mM=in vitro severe methylenetetrahydrofolate reductase deficiency homocystinuria) or Mix B2 (Hcy 0.1 mM+Hci 0.05 mM=in vitro mild methylenetetrahydrofolate reductase deficiency homocystinuria) were preincubated with homogenized hippocampii or with eel Electrophorus electricus pure AChE. AChE was evaluated spectrophotometrically. Hcy or Met stimulated hippocampal AChE by 50% (p < 0.001) at low concentrations of the amino acids (up to 0.3-0.5 mM), whereas Hci inhibited the enzyme by 40% (p < 0.001). Mix A, Mix B1, or Mix B2 activated hippocampal AChE by 40, 30, (p < 0.001), and 12% (p < 0.01), respectively. In contrast, the S-containing amino acids, Mix A, Mix B1, Mix B2 failed to affect the pure AChE activity. Conclusions: a) The presence of -SH group in Hcy and Met may result in hippocampal AChE stimulation and the redox isomer Hci in the inhibition of the enzyme, probably by producing free radicals, and b) The SH-amino acids seem to affect the hippocampal enzyme indirectly, possibly by lipid(s)-protein modifications(s) and Hci by inducing oxidative stress, since no effect was observed on pure AChE activity. © Springer Science+Business Media, Inc. 2006