387 research outputs found

    Forbidden oxygen lines at various nucleocentric distances in comets

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    To study the formation of the [OI] lines - i.e., 5577 A (the green line), 6300 A and 6364 A (the two red lines) - in the coma of comets and to determine the parent species of the oxygen atoms using the green to red-doublet emission intensity ratio (G/R ratio) and the lines velocity widths. We acquired at the ESO VLT high-resolution spectroscopic observations of comets C/2002 T7 (LINEAR), 73P-C/Schwassmann-Wachmann 3, 8P/Tuttle, and, 103P/Hartley 2 when they were close to the Earth (< 0.6 au). Using the observed spectra, we determined the intensities and the widths of the three [OI] lines. We have spatially extracted the spectra in order to achieve the best possible resolution of about 1-2", i.e., nucleocentric projected distances of 100 to 400 km depending on the geocentric distance of the comet. We have decontaminated the [OI] green line from C2 lines blends. It is found that the observed G/R ratio on all four comets varies as a function of nucleocentric projected distance. This is mainly due to the collisional quenching of O(1S) and O(1D) by water molecules in the inner coma. The observed green emission line width is about 2.5 km/s and decreases as the distance from the nucleus increases which can be explained by the varying contribution of CO2 to the O(1S) production in the innermost coma. The photodissociation of CO2 molecules seems to produce O(1S) closer to the nucleus while the water molecule forms all the O(1S) and O(1D) atoms beyond 1000 km. Thus we conclude that the main parent species producing O(1S) and O(1D) in the inner coma is not always the same. The observations have been interpreted in the framework of the coupled-chemistry-emission model of Bhardwaj & Raghuram (2012) and the upper limits of CO2 relative abundances are derived from the observed G/R ratios. Measuring the [OI] lines could indeed provide a new way to determine the CO2 relative abundance in comets.Comment: accepted for publication in A&A, the abstract is shortene

    Philo of Alexandria: Holiness as self-possession and selftranscendence

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    Philo’s writings can be seen as a crucial link between Hellenistic Judaism and early Christianity, particularly in his way of drawing on Greek philosophy in reading the scriptures. Pierre Hadot has pointed out how Graeco-Roman philosophy was seen at that time as a practical subject aiming at the care of self in its twofold movement of interiorisation and exteriorisation. This article explores how Philo draws on these aspects of philosophy to articulate his Jewish understanding of the journey towards perfection or holiness

    Effect of Copper And/Or Bacitracin On The Sulphur Amino Acid Requirements Of Turkeys

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    A nonsignificant but consistent depressing effects from additions of combined copper (120 ppm) and zinc bacitracin (50 or 75 g per ton) was observed in a previous study. One of the factors that has been suspected to be affected by copper is utilization of sulfur containing amino acids. Thus, a factorial experiment was conducted to study the effect of copper (120 ppm) and/or zinc bacitracin (25 g per ton) on the level of sulfur amino acids at 85%, 100% and 115% of NRC (1977) requirements. The low protein density series of Guenthner et al. (1978) was used (23, 20, 18, 16, 14 and 12%). Dietary protein level was reduced at 4-week intervals

    Similarity after Goodman

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    © The Author(s) 2010. This article is published with open access at Springerlink.com Abstract In a famous critique, Goodman dismissed similarity as a slippery and both philosophically and scientifically useless notion. We revisit his critique in the light of important recent work on similarity in psychology and cognitive science. Specifically, we use Tversky’s influential set-theoretic account of similarity as well as Gärdenfors’s more recent resuscitation of the geometrical account to show that, while Goodman’s critique contained valuable insights, it does not warrant a dismissal of similarity. 1 Formal Modes of Similarity For much of the twentieth century, both philosophical and psychological theorizing about similarity has been dominated by the geometrical model o

    Documenting marine species traits in the World Register of Marine Species (WoRMS): current status, future plans and encountered challenges

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    The importance of describing species patterns and the underlying processes explaining these patterns is essential to assess the status and future evolution of marine ecosystems. This requires biological information on functional and structural species traits such as feeding ecology, body size, reproduction, life history, etc.To accommodate this need, the World Register of Marine Species (WoRMS) (WoRMS Editorial Board 2017) is expanding its content with trait information (Costello et al. 2015), subdivided into 3 main categories: (1) taxonomy related traits, e.g. paraphyletic groups, (2) biological and ecological traits-specific characteristics of a taxon, e.g. body size or feeding type and (3) human defined traits, e.g. the legal protection status of species, whether a species is introduced, harmful, or used as an ecological indicator.Initially, priority was given to the inclusion of traits that could be applied to the majority of marine taxa and where the information was easily available. The main driver for this approach was that the inclusion of these traits should result in new research, which in turn would drive improvements in the quality and quantity of trait information. Pilot projects were carried out for different species groups, allowing a thorough documentation of a selection of traits. In parallel, a standard vocabulary was put together (http://www.marinespecies.org/traits/wiki/), based on already existing resources to cover all marine life. All documented traits needed to be compliant with this vocabulary, in order to make the data as widely useable as possible, across groups. Defining a trait across all marine life is not trivial, as scientists can use terms in a different way between groups. This stresses the importance for users to realize these differences in terminology, before they analyse a trait across all taxa.Some traits were thought to be quite straightforward to document, although practice proved otherwise. Such a trait is body size, where the aim was to document the numerical value of the ‘maximum body size in length’. In reality, a lot of variation is possible (e.g. for fish: fork length versus standard length) and maximum size is not always considered relevant from an ecological point of view. On the other hand, documenting numerical body size for each marine species is quite time consuming. Therefore, a complementary size trait will be documented, indicating whether taxa are considered as micro, meio, macro or mega.Whereas the initial approach was to complete the register for each tackled trait relevant for all marine species, we now complement this by (1) documenting several traits within a specific group, regardless whether this trait is also present in other taxon groups, and (2) documenting one specific trait, covering a variety – but not all – taxonomic groups, e.g. the composition of the skeleton for calcareous animals.Where possible, we aim to document a trait on a higher taxonomic level to allow the work to progress more rapidly. As the database allows top-down inheritance of traits, exceptions can easily be documented. In addition, collaborations are sought with already running initiatives such as Encyclopedia of Life.Very soon, all the documented traits will be searchable through the Marine Species Traits Portal. The human-defined traits are already accessible through the EMODnet Biology Portal (http://www.emodnet-biology.eu/toolbox), in combination with distribution information from the European Ocean Biogeographic Information System (EurOBIS; www.eurobis.org; Vandepitte et al. 2011; Vandepitte et al. 2015) and taxonomy from WoRMS (www.marinespecies.org). Through the LifeWatch Taxonomic Backbone (LW-TaxBB) (http://www.lifewatch.be/data-services/), services are offered to access these traits, combined with data and information from other resources such as WoRMS and (Eur)OBIS.We would like to acknowledge the EMODnet Biology and the LifeWatch project, in which the Flanders Marine Institute (VLIZ) – host institute of WoRMS – is responsible for the development of the LW-TaxBB. Both projects provide funding for the documentation of trait data and development of services allowing researchers to easily access the available data, in combination with data from other sources

    Aphia for a World Register of Marine Species (WoRMS)

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    An authoritative and global register of all marine species is urgently needed to facilitate biological data management and exchange, the integration of ecological and biodiversity data with non-biological ocean data, and to assist taxonomists in describing new species, revisions and correcting past nomenclatural confusion. The exercise of producing this list has added benefits in fostering collaboration between experts at a global scale and maintaining taxonomic expertise. Easy access to the register will allow local ecologists and biologists to use correct taxonomic names, and will encourage addition of overlooked species to the list. This will in turn stimulate a.o. biodiversity Species’(WoRMS) is the logical next step for ocean biodiversity informatics (OBI) to become an everyday and essential supporting infrastructure for the marine sciences, monitoring and environmental management. WoRMS is a standards based, quality controlled, expert validated, open-access infrastructure for research, education, and data and resource management. It builds on experience in developing the European Register of Marine Species and the Ocean Biogeographic Information System, and will collaborate with and contribute to the GBIF’s ECAT and planned Global Names Architecture, Species 2000, the Catalogue of Life, the Ocean Biogeographic Information System, the Encyclopaedia of Life, SeaLifeBase, IOC’s International Oceanographic Data and Information Exchange, and related initiatives. The Aphia database, developed and maintained by the Flanders Marine Institute (VLIZ), serves as the IT platform for WoRMS. Currently, well over 100 world leading taxonomists are contributing towards this World Register WoRMS webportal and all its functionalities, such as the web-based services and the online edit tool for the taxonomic experts. For further details see http://www.marinespecies.org
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