56 research outputs found
The pulsation spectrum of VX Hydrae
We present the results of a two-year, multisite observing campaign
investigating the high-amplitude delta Scuti star VX Hydrae during the 2006 and
2007 observing seasons. The final data set consists of nearly 8500 V-band
observations spanning HJD 2453763.6 to 2454212.7 (2006 January 28 to 2007 April
22). Separate analyses of the two individual seasons of data yield 25
confidently-detected frequencies common to both data sets, of which two are
pulsation modes, and the remaining 23 are Fourier harmonics or beat frequencies
of these two modes. The 2006 data set had five additional frequencies with
amplitudes less than 1.5 mmag, and the 2007 data had one additional frequency.
Analysis of the full 2006-2007 data set yields 22 of the 25 frequencies found
in the individual seasons of data. There are no significant peaks in the
spectrum other than these between 0 and 60 c/d. The frequencies of the two main
pulsation modes derived from the 2006 and 2007 observing seasons individually
do not differ at the level of 3-sigma, and thus we find no conclusive evidence
for period change over the span of these observations. However, the amplitude
of f(1) = 5.7898 c/d changed significantly between the two seasons, while the
amplitude of f(0) = 4.4765 c/d remained constant; amplitudes of the Fourier
harmonics and beat frequencies of f(1) also changed. Similar behavior was seen
in the 1950s, and it is clear that VX Hydrae undergoes significant amplitude
changes over time.Comment: 14 pages, 5 figures, published in Publications of the Astronomical
Society of the Pacific, v.121, p.1076 (October 2009
Postglacial expansion of the arctic keystone copepod calanus glacialis
Calanus glacialis, a major contributor to zooplankton biomass in the Arctic shelf seas, is a key link between primary production and higher trophic levels that may be sensitive to climate warming. The aim of this study was to explore genetic variation in contemporary populations of this species to infer possible changes during the Quaternary period, and to assess its population structure in both space and time. Calanus glacialis was sampled in the fjords of Spitsbergen (Hornsund and Kongsfjorden) in 2003, 2004, 2006, 2009 and 2012. The sequence of a mitochondrial marker, belonging to the ND5 gene, selected for the study was 1249 base pairs long and distinguished 75 unique haplotypes among 140 individuals that formed three main clades. There was no detectable pattern in the distribution of haplotypes by geographic distance or over time. Interestingly, a Bayesian skyline plot suggested that a 1000-fold increase in population size occurred approximately 10,000 years before present, suggesting a species expansion after the Last Glacial Maximum.GAME from the National Science Centre, the Polish Ministry of Science and Higher Education Iuventus Plus [IP2014 050573]; FCT-PT [CCMAR/Multi/04326/2013]; [2011/03/B/NZ8/02876
Bank Consolidation and the Provision of Banking Services: The Case of Small Commercial Loans
Bathyconchoecilla, a new genus of deep plankto-benthic halocyprids (Ostracoda, Myodocopa) from the northern Pacific and an overview of Bathyconchoeciinae
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