7,162 research outputs found

    Sharing the burden : on the division of parental care and vocalizations during incubation

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    In species with biparental care, individuals only have to pay the costs for their own parental investment, whereas the contribution of their partner comes for free. Each parent hence benefits if its partner works harder, creating an evolutionary conflict of interest. How parents resolve this conflict and how they achieve the optimal division of parental tasks often remains elusive. In this study, we investigated whether lesser black-backed gulls (Larus fuscus) divide parental care during incubation equally and whether this correlates with the extent of vocalizations between pair-members during incubation. We then investigated whether pairs showing more evenly distributed incubation behavior had a higher reproductive success. To this end, we recorded incubation behavior and vocalizations for 24-h time periods. Subsequently, we experimentally increased or decreased brood sizes in order to manipulate parental effort, and followed offspring development from hatching till fledging. Although incubation bouts were, on average, slightly longer in females, patterns varied strongly between pairs, ranging from primarily female incubation over equal sex contributions to male-biased incubation. Pairs contributing more equally to incubation vocalized more during nest relief and had a higher reproductive output when brood sizes were experimentally increased. Thus, vocalizations and a more equal division of parental care during incubation may facilitate higher levels of care during the nestling period, as suggested by a greater reproductive success when facing high brood demand, or they indicate pair quality

    Diffuse interstellar bands {\lambda}5780 and {\lambda}5797 in the Antennae Galaxy as seen by MUSE

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    ABRIDGED: Diffuse interstellar bands (DIBs) are faint spectral absorption features of unknown origin. Research on DIBs beyond the Local Group (LG) will surely blossom in the era of the ELTs. A possibility that needs to be explored is the use of integral field spectrographs. We do so by using MUSE data for the Antennae Galaxy, the closest major galaxy merger. High S-to-N spectra were created by co-adding the signal of many spatial elements. The emission of the underlying stellar population was modeled using STARLIGHT. To our knowledge, we have derived the first maps for the DIBs at l5780 and l5797 in galaxies outside the LG. The l5780 DIB was detected in an area of ~0.6 arcmin2, corresponding to a linear scale of ~25 kpc2. This region was sampled using >200 independent lines of sight. The DIB l5797 was detected in >100 independent lines of sight. Both DIBs are associated with a region with high emission in the HI 21 cm line, implying a connection between atomic gas and DIBs, as the correlations for the Milky Way also suggest. Conversely, there is mild spatial association between the two DIBs and the molecular gas, in agreement with results for our Galaxy that indicate a lack of correlation between DIBs and molecular gas. The overall structure for the DIB strength distribution and extinction are comparable. Within the system, the l5780 DIB clearly correlates with the extinction. Both DIBs follow the relationship between equivalent width and reddening when data for several galaxies are considered. Unidentified Infrared emission Bands (UIBs, likely caused by PAHs) and the l5780 and l5797 DIBs show similar but not identical spatial distributions. We attribute the differences to extinction effects without necessarily implying a radically different nature of the respective carriers. The results illustrate the enormous potential of integral field spectrographs for extragalactic DIB research.Comment: 12 pages, 13 figures, accepted by Astronomy & Astrophysics; version corrected by English edito

    Status of the ILC Main Linac BPM R&D

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    An introduction and the status of R&D activities for a high-resolution, "cold" beam position monitor (BPM) and the related read-out electronics are discussed. Two different BPM detector concepts, to be attached to the SC quadrupole and located inside the ILC cryomodule, are currently under investigation: A resonant dipole-mode cavity-style BPM pickup, developed at Fermilab, and a re-entrant resonant coaxial waveguide BPM, designed by CEA-Saclay. While the 1.5 GHz dipole-mode cavity BPM is still in the R&D phase, the re-entrant BPM has already passed first beam tests, including its read-out system. Furthermore, the LAPP group is developing radiation tolerant digital read-out systems, which are tested at the CLIC test facility (CTF).Comment: LCWS / ILC08 conference contribution, 6 pages, 6 figure

    Bernard Yarnton Mills 1920-2011

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    Bernie Mills is remembered globally as an influential pioneer in the evolving field of radio astronomy. His contributions with the 'Mills Cross' at the CSIRO Division of Radiophysics and later at the University of Sydney's School of Physics and the development of the Molonglo Observatory Synthesis Telescope (MOST) were widely recognised as astronomy evolved in the years 1948-1985 and radio astronomy changed the viewpoint of the astronomer as a host of new objects were discovered

    A Wire Position Monitor System for the 1.3 GHZ Tesla-Style Cryomodule at the Fermilab New-Muon-Lab Accelerator

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    The first cryomodule for the beam test facility at the Fermilab New-Muon-Lab building is currently under RF commissioning. Among other diagnostics systems, the transverse position of the helium gas return pipe with the connected 1.3 GHz SRF accelerating cavities is measured along the ~15 m long module using a stretched-wire position monitoring system. An overview of the wire position monitor system technology is given, along with preliminary results taken at the initial module cool down, and during further testing. As the measurement system offers a high resolution, we also discuss options for use as a vibration detector.Comment: 4 pp. 15th International Conference on RF Superconductivity (SRF2011). 25-29 Jul 2011. Chicago, Illinois, US

    High Resolution BPM Upgrade for the ATF Damping Ring at KEK

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    A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented.Comment: 3 pp. 10th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators DIPAC 2011, 16-18 May 2011. Hamburg, German
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