782 research outputs found

    The data mining: An analysis of 20 eclipsing binary light-curves observed by the INTEGRAL/OMC

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    Twenty eclipsing binaries were selected for an analysis from a huge database of observations made by the INTEGRAL/OMC camera. The photometric data were processed and analyzed, resulting in a first light-curve study of these neglected eclipsing binaries. Most of the selected systems are the detached ones. The system ET Vel was discovered to be an eccentric one. Due to missing spectroscopic study of these stars, further detailed analyses are still needed.Comment: 4 pages, published in 2009 New Astronomy 14, 12

    Measuring the effective phonon density of states of a quantum dot

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    We employ detuning-dependent decay-rate measurements of a quantum dot in a photonic-crystal cavity to study the influence of phonon dephasing in a solid-state quantum-electrodynamics experiment. The experimental data agree with a microscopic non-Markovian model accounting for dephasing from longitudinal acoustic phonons, and identifies the reason for the hitherto unexplained difference between non-resonant cavity feeding in different nanocavities. From the comparison between experiment and theory we extract the effective phonon density of states experienced by the quantum dot. This quantity determines all phonon dephasing properties of the system and is found to be described well by a theory of bulk phonons.Comment: 5 pages, 3 figures, submitte

    Die U-topia der UrsprĂĽnglichen Einheit

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    A comparison of condition factor and gona dosomatic index of sardine Sardinops sagax stocks in the northern and southern Benguela upwelling ecosystems, 1984–1999

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    Time-series of condition factor (CF) and gonadosomatic index (GSI) were generated using general linear models (GLM) for sardine Sardinops sagax stocks in the northern and southern Benguela ecosystems over the period 1984–1999. During this period the biomass of sardine in the northern Benguela remained at relatively low levels of African Journal of Marine Science 2001, 23: 123–13

    Risk-based surveillance for human health hazards: the example of Trichinella

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    Increasing demands for cost-effectiveness in surveillance for human health hazards can be met by introducmg risk-based principles. This implies targeting subpopulations w1th higher risk of infection compared to the whole population. We demonstrate how historical data from surveillance can be used to assess risk of infection. The model is called Discounting historical evidence and depends mainly on two variables: Annual risk of introduction Plntro and surveillance system sensitivity SSe (ability to detect infection if present). The model Implies simulations that reiterate for a number of years, and for each year the output is updated with the confidence on absence of infection. Trichinella spiralis infection in pigs is used as an example. In Denmark, pigs at slaughter are tested (currently 23 million per year), and despite of \u3e 70 years of sampling no pigs have been found positive. Hence, we concluded that Plntro is low. SSe can be estimated from the maximum number of infected carcasses expected under the specified design prevalence, and the sensitivity of the test applied. According to the assessment, the prevalence of Trichmella in Danish pigs is negligible (\u3c1 case/million). Based on this , a risk-based surveillance programme for Trichinella is designed that targets all out-door reared pigs as well as all sows and boars (currently 610,000 per year). Compared to confined pigs, outdoor-reared pigs have higher risk of getting Trichinella because of their exposure to wildlife, which might harbour Trichinella. Sows and boars are at increased risk, because they live longer than fimshers. Again, SSe and Plntro are estimated and the model is used to show how risk-based surveillance can be applied without jeopardizing human health. Finally, we incorporate wildlife surveys and test quality assurance in the programme. The model results are included in an application to the European Commission concern1ng Denmark\u27s status as a region with negligible risk of Trichinella

    Biotic interactions promote local adaptation to soil in plants

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    Although different ecological factors shape adaptative evolution in natural habitats, we know little about how their interactions impact local adaptation. Here we used eight generations of experimental evolution with outcrossing Brassica rapa plants as a model system, in eight treatment groups that varied in soil type, herbivory (with/without aphids), and pollination mode (hand- or bumblebee-pollination), to study how biotic interactions affect local adaptation to soil. First, we show that several plant traits evolved in response to biotic interactions in a soil-specific way. Second, using a reciprocal transplant experiment, we demonstrate that significant local adaptation to soil-type evolved in the “number of open flowers”, a trait used as a fitness proxy, but only in plants that evolved with herbivory and bee pollination. Whole genome re-sequencing of experimental lines revealed that biotic interactions caused a 10-fold increase in the number of SNPs across the genome with significant allele frequency change, and that alleles with opposite allele frequency change in different soil types (antagonistic pleiotropy) were most common in plants with an evolutionary history of herbivory and bee pollination. Our results demonstrate that the interaction with mutualists and antagonists can facilitate local adaptation to soil type through antagonistic pleiotropy

    Period changes in six semi-detached Algol-type binaries

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    Six semi-detached Algol-type binaries lacking a period analysis were chosen to test for a presence of a third body. The O-C diagrams of these binaries were analyzed with the least-squares method by using all available times of minima. Also fourteen new minima, obtained from our observations, were included in the present research. The light-time effect was adopted as a main factor for the detailed description of the long-term period changes. Third bodies were found with orbital periods from 46 up to 84 years, and eccentricities from 0.0 to 0.78 for the selected binaries. The mass functions and the minimal masses of such bodies were also calculated.Comment: 14 pages, 8 figure
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