1,859 research outputs found
Medium-resolution echelle spectroscopy of pulsating variables and exoplanet host stars with sub-meter telescopes
Here we present two of our interesting results obtained over the last 18
months from spectroscopic monitoring of binary pulsating stars and exoplanet
host stars. Our investigations are very promising by demonstrating that modern
fiber-fed spectrographs open a whole new chapter in the life of small national
and university observatories.Comment: 3 pages, 3 figures. To be published in the proceedings of the
workshop on "Observing techniques, instrumentation and science for
metre-class telescopes", Sep. 2013, Tatranska Lomnica, Slovaki
Splitting Proofs for Interpolation
We study interpolant extraction from local first-order refutations. We
present a new theoretical perspective on interpolation based on clearly
separating the condition on logical strength of the formula from the
requirement on the com- mon signature. This allows us to highlight the space of
all interpolants that can be extracted from a refutation as a space of simple
choices on how to split the refuta- tion into two parts. We use this new
insight to develop an algorithm for extracting interpolants which are linear in
the size of the input refutation and can be further optimized using metrics
such as number of non-logical symbols or quantifiers. We implemented the new
algorithm in first-order theorem prover VAMPIRE and evaluated it on a large
number of examples coming from the first-order proving community. Our
experiments give practical evidence that our work improves the state-of-the-art
in first-order interpolation.Comment: 26th Conference on Automated Deduction, 201
A new problem with cross-species amplification of microsatellites: Generation of non-homologous products
Microsatellites have been widely used in studies on population genetics, ecology and evolutionary biology. However, microsatellites are not always available for the species to be studied and their isolation could be time-consuming. In order to save time and effort researchers often rely on cross-species amplification. We revealed a new problem of microsatellite cross-species amplification in addition to size homoplasy by analyzing the sequences of electromorphs from seven catfish species belonging to three different families (Clariidae, Heteropneustidae and Pimelodidae). A total of 50 different electromorphs were amplified from the seven catfish species by using primers for 4 microsatellite loci isolated from the species Clarias batrachus. Two hundred and forty PCR-products representing all 50 electromorphs were sequenced and analyzed. Primers for two loci amplified specific products from orthologous loci in all species tested, whereas primers for the other two loci produced specific and polymorphic bands from some non-orthologous loci, even in closely related non-source species. Size homoplasy within the source species was not obvious, whereas extensive size homoplasy across species were detected at three loci, but not at the fourth one. These data suggest that amplification of products from non-orthologous loci and appearance of size homoplasy by cross-amplification are locus dependent, and do not reflect phylogenetic relationship. Amplification of non-orthologous loci and appearance of size homoplasy will lead to obvious complications in phylogenetic interference, population genetic and evolutionary studies. Therefore, we propose that sequence analysis of cross-amplification products should be conducted prior to application of cross-species amplification of microsatellites
Discovery of the spectroscopic binary nature of the classical Cepheids FN Aql and V1344 Aql
We present the analysis of photometric and spectroscopic data of two
classical Cepheids, FN Aquilae and V1344 Aquilae. Based on the joint treatment
of the new and earlier radial velocity data, both Galactic Cepheids have been
found to be a member in a spectroscopic binary system.
To match the phases of the earlier radial velocity data correctly with the
new ones, we also determined the temporal behaviour of the pulsation period of
these Cepheids based on all available photometric data. The O-C graph covering
about half century shows slight changes in the pulsation period due to stellar
evolution for both Cepheids.Comment: 7 pages, 6 figures, 7 tables, accepted for publishing in the MNRA
PALLADIUM BASED CONTACTS TO GaAs AND InP
Au(85nm)/Pd(55nm) and Pd(55nm) metallizations were deposited on GaAs(lOO) and InP(100) substrates. The samples were heat treated in a scanning electron microscope (SEM) equipped with a quadrupole mass spectrometer. The simultaneous observation of the volatile component loss (in situ) by Evolved Gas Analysis (EGA) and the change in surface morphology by SEM during the heart treatment using a heating rate of 30°C/min
were carried out. The interaction of the metallization with compound semiconductor substrates was observed after the heat treatment by transmission electron microscopy (TEM) using samples prepared by cross-sectional technique.
In the course of the present work a large volatile component (arsenic and phosphorus) loss was observed for the samples coated by single layer metallization (at 410° C for Pd/GaAs and at 580°C for Pd/InP) and two peaks were registered in the case of Au/Pd metallization. In the latter case the cause of the second evaporation peak is the
interaction between diffused gold and compound semiconductor. The SEM images of the surfaces demonstrate a significant change of the surface morphology at the singularities of the EGA curves.
The grains grown into the semiconductors are shown by the cross-sectional images of the heat treated samples
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