Panagiotis Labropoulos

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Aims. This paper discusses the spectral occupancy for performing radio astronomy with the Low-Frequency Array (LOFAR), with a focus on imaging observations. Methods. We have analysed the radio-frequency interference (RFI) situation in two 24-h surveys with Dutch LOFAR stations, covering 30– 78 MHz with low-band antennas and 115–163 MHz with high-band(More)
The functional response of females of the phytoseiid mite, Iphiseius degenerans (Berlese), to increasing densities of females of its prey, Tetranychus urticae Koch and Eutetranychus orientalis Klein, on bean leaves, were studied under laboratory conditions. Our results indicated that the predator consumed significantly more items of E. orientalis than of T.(More)
The LOFAR radio telescope consists of tens of thousands of dipole antennas that combine their signals to operate as a single large radio telescope. The truly innovative aspect of this new telescope is that its pointing system is not mechanical. It is steered by combining the electric signals from different elements using advanced beam-forming software.(More)
One of the problems facing experiments designed to detect redshifted 21cm emission from the epoch of reionization (EoR) is the presence of foregrounds which exceed the cosmological signal in intensity by orders of magnitude. When fitting them so that they can be removed, we must be careful to minimize 'overfitting', in which we fit away some of the(More)
A number of experiments are set to measure the 21-cm signal of neutral hydrogen from the Epoch of Reionization (EoR). The common denominator of these experiments are the large data sets produced, contaminated by various instrumental effects, ionospheric distortions, RFI and strong Galactic and extragalactic foregrounds. In this paper, the first in a series,(More)
Detecting redshifted 21-cm emission from neutral hydrogen in the early Universe promises to give direct constraints on the epoch of reionization (EoR). It will, though, be very challenging to extract the cosmological signal (CS) from foregrounds and noise which are orders of magnitude larger. Fortunately, the signal has some characteristics which(More)
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