485 research outputs found
Taxonomic status of the Liberian Greenbul Phyllastrephus leucolepis and the conservation importance of the Cavalla Forest, Liberia
We thank Jochen Martens for his long-lasting patience in dealing with the specimen of leucolepis, and Brian Hillcoat for comments and advice. It is hardly possible to thank by name all those who have supported WG over the past 30 years and more since 1981 in the fields of forest ecology and ornithology in eastern Liberia. In particular, we express gratitude to Alex Peal and Theo Freeman, both Heads of Wildlife and National Parks, for their many years of cooperation, and the Silviculture Officers Wynn Bryant, Momo Kromah and Steve Miapeh. The knowledge of the tree experts Joe Keper and Daniel Dorbor helped us to gain insights into the ecological complexities of the relationship between man, birds and trees. William Toe worked for three years as bird trapper and assistant in bird banding. WG’s attachment to the University of Liberia and to the students who so often accompanied him was made possible by Ben Karmorh from the Environmental Protection Agency (EPA) and University of Liberia. NABU, the German Conservation Society, has supported the Liberian projects for almost 30 years now. We also thank Nigel Collar, Françoise Dowsett-Lemaire and Hannah Rowland for comments and advice. We thank the African Bird Club and the Royal Society for the Protection of Birds for helping to fund the 2013 expedition to the Cavalla Forest, in particular Alice Ward-Francis, Robert Sheldon, Alan Williams and Keith Betton. We also are extremely grateful to Michael Garbo and staff of the Society for the Conservation of Nature in Liberia for all manner of help with the expedition, to Harrison Karnwea and colleagues at the Forest Development Authority of Liberia for permissions and other support, as well as to Emmanuel Loqueh, Trokon Grimes, Flomo Molubah and Amos ‘Dweh’ Dorbor for being such excellent companions in the field. YL performed the genetic work as part of her M.Sc. (Genetics) at the University of Aberdeen, whose support is acknowledged.Peer reviewedPublisher PD
Powdery mildew responsive genes of resistant grapevine cultivar 'Regent'
The ascomycete Erysiphe necator causes powdery mildew disease of grapevine, a disastrous infection which is commonly defeated with multiple fungicide applications in viticulture. Breeding for natural resistance of quality grapes (Vitis vinifera) is thus a major aim of current efforts. The cultivar 'Regent' is resistant to powdery mildew due to an introgression from an American Vitis sp. resistance donor. To identify key regulatory elements in defense responses of 'Regent' we performed transcript analyses after challenging with E. necator inoculation in comparison with a susceptible grapevine. A set of genes selected from preliminary microarray hybridization results were investigated by RT-qPCR. The data indicate an important role of transcription factors MYB15, WRKY75, WRKY33, WRKY7, ethylene responsive transcription factors ERF2 and ERF5 as well as a CZF1/ZFAR transcripton factor in regulating the early defense when the fungus starts the interaction with its host by the formation of haustoria
High-resolution 3D phenotyping of the grapevine root system using X-ray Computed Tomography
Plant roots are essential for water and nutrient uptake and contribute to the plants' response to environmental stress factors. As the hidden half of a plant, investigation of root systems is highly challenging, most of available methods are destructive and very labour-intensive. In this proof-of-concept study, a non-invasive X-ray micro computed tomography (X-ray µCT) method was applied to investigate the phenotypic variation of the complex three-dimensional (3D) architecture of grapevine roots as a function of genotype and soil. Woody cuttings of 'Calardis Musqué', 'Villard Blanc' and V3125 ('Schiava Grossa' x 'Riesling') were cultivated in polypropylene columns filled with two different soil types, clay loam and sandy loam, for 6 weeks. Afterwards, the columns were scanned once using the technique of X-ray µCT. The received raw data were analysed for the reconstruction of 3D root system models (3D model), which display a non-destructive visualization of whole, intact root systems with a spatial resolution of 42 µm. The 3D models of all investigated plants (in total 18) were applied to quantify root system characteristics precisely by measuring adventitious root length, lateral root length, total root length, root system surface area, root system volume and root growth angles from the woody cutting relative to a horizontal axis. The results showed that: (i) early root formation and root growth differed between genotypes, especially between 'Calardis Musqué' and 'Villard Blanc'; and (ii) the soil type does influence adventitious root formation of V3125, but had minor effects on 'Calardis Musqué' and 'Villard Blanc'. In conclusion, this innovative, high-resolution method of X-ray µCT is suitable for high resolution phenotyping of root formation, architecture, and rooting characteristics of grapevine woody cuttings in a non-destructive manner, e.g. to investigate root response to drought stress and would provide new insights into phylloxera root infection
Inferring the Scale of OpenStreetMap Features
International audienceTraditionally, national mapping agencies produced datasets and map products for a low number of specified and internally consistent scales, i.e. at a common level of detail (LoD). With the advent of projects like OpenStreetMap, data users are increasingly confronted with the task of dealing with heterogeneously detailed and scaled geodata. Knowing the scale of geodata is very important for mapping processes such as for generalization of label placement or land-cover studies for instance. In the following chapter, we review and compare two concurrent approaches at automatically assigning scale to OSM objects. The first approach is based on a multi-criteria decision making model, with a rationalist approach for defining and parameterizing the respective criteria, yielding five broad LoD classes. The second approach attempts to identify a single metric from an analysis process, which is then used to interpolate a scale equivalence. Both approaches are combined and tested against well-known Corine data, resulting in an improvement of the scale inference process. The chapter closes with a presentation of the most pressing open problem
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Notes on the behaviour, plumage and distribution of the White-tailed Swallow Hirundo megaensis
The White-tailed Swallow Hirundo megaensis is a threatened and poorly known bird endemic to southern Ethiopia, where it is restricted to a small area of Acacia savanna. Despite the paucity of previous nest records, we found 67 nests in the years 2010–14, commonly in village huts lived in by people, and report the first confirmation of nesting (two certain records) in termite mounds. Its nests are small mud cups lined with grass and animal hair, fixed to roof joists and similar to those of its sister species, the Pearl-breasted Swallow H. dimidiata of southern Africa, although it appears to lay larger clutches (3–4 pure white eggs) and breed less frequently, producing one brood in each of its two rain-driven breeding seasons (April–June and October–November). The same nests are reportedly used in these two seasons, presumably by the same pairs. Incubation lasts 16–17 days, with some broods showing clearly smaller chicks and hence presumably asynchronous hatching. Study of nestlings in the hand and museum skins confirmed that juveniles can be determined by their shorter tails, browner heads and frequently also wings, and reduced white in the tail. Although birds are typically seen singly or in pairs, flocks of up to 50, sometimes mixed with other hirundines, can occur. The breeding range appears to be almost identical to that of the Ethiopian Bush-crow Zavattariornis stresemanni but regular sightings of White-tailed Swallows since 2005 at the Liben Plain, 120 km to the east of the core area, suggest that the birds are frequent visitors there.We are grateful to the numerous funding bodies which have supported this research over several years: NERC, RSPB, British Birdfair, African Bird Club, British Ornithologists’ Union, Gesellschaft für Tropenornithologie, Tim Whitmore Zoology Fund, Magdalene College (Cambridge), Cambridge Philosophical Society, and BirdLife Preventing Extinctions Programme; and especially to Julian Francis. We also thank Robert Prys-Jones at the Natural History Museum (NHMUK) for access to specimens; Les Colley for his photograph used in Fig. 5; Stefanie Rick for her excellent drawings used in Fig. 9; Steve Rooke (Sunbird Tours), Bernard, Willem and Sjoerd Oosterbaan, Simon Busuttil, Merid Gabremichael and Claire Spottiswoode for providing additional information and sightings; Alazar Dakar, Abiy Dange, Birhan Dessalegn, Solomon Desta, Okotu Dida, Ali Guche, Sam Jones, Gufu Kashina, Stuart Marsden, Tesfaye Mekonnen, Samson Zelleke and many others including all the staff of Borana National Park for help with fieldwork; Angela Turner and John Atkins for their services as referees; and the Borana villagers who so kindly allowed us into their homes to study the White-tailed Swallow’s nests and without whose hospitality our knowledge of this species would be much poorer.This is the author accepted manuscript. The final version is available from African Bird Club
Investigation of efficient strain measurements at smallest areas applying the time to digital (TDC) principle
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Further notes on the natural history of the Ethiopian Bush-crow Zavattariornis stresemanni
The Ethiopian Bush-crow Zavattariornis stresemanni is a charismatic and Endangered endemic bird of southern Ethiopia, whose general biology remains under-studied. We present field notes and observations from 2008 to 2014, covering many aspects of the species’ behaviour and morphology. Bush-crows breed co-operatively in response to both of the local rainy seasons, but group size and fidelity of helpers appears to be variable. Bush-crow nests were found for the first time on man-made structures; a low power distribution pole and a tall electricity pylon. The display of one bush-crow to another is further described. Juveniles can be identified by darker coloration around the face, bright red gapes and distinctive begging calls. Adults possess lightweight, low-density body feathers and it appears that bush-crows have a moult phenology that overlaps extensively with breeding, a trait unusual in birds. Post-breeding dispersal is often limited, although anecdotal evidence and a handful of observations suggest that some individuals cover greater distances between breeding seasons. We report the first confirmed predation of a bush-crow, and supplement this with notes on other interspecific interactions. Finally, bush-crows were found for the first time north-west of Yabello (a small range extension), and we discuss the implications of local movements and range fluctuations in the context of the species’ apparent climatic range limitation.This is the author accepted manuscript. The final version is available from African Bird Club via https://www.africanbirdclub.org/bulletins/abc-bulletin-231-march-2016/further-notes-natural-history-ethiopian-bush-cro
Percolative phase separation induced by nonuniformly distributed excess oxygens
The zero-field La and Mn nuclear magnetic resonances were
studied in with different oxygen
stoichiometry . The signal intensity, peak frequency and line
broadening of the La NMR spectrum show that excess oxygens have a
tendency to concentrate and establish local ferromagnetic ordering around
themselves. These connect the previously existed ferromagnetic clusters
embedded in the antiferromagnetic host, resulting in percolative conduction
paths. This phase separation is not a charge segregation type, but a
electroneutral type. The magnetoresistance peak at the temperature where
percolative paths start to form provides a direct evidence that phase
separation is one source of colossal magnetoresistance effect.Comment: 4 pages, 5 figure
Nanosized Sodium-Doped Lanthanum Manganites: Role of the Synthetic Route on their Physical Properties
In this paper we present the results of the synthesis and characterisation of
nanocrystalline La1-xNaxMnO3+delta samples. Two synthetic routes were employed:
polyacrylamide-based sol-gel and propellant synthesis. Pure, single phase
materials were obtained with grain size around 35 nm for the sol-gel samples
and around 55 nm for the propellant ones, which moreover present a more broaden
grain size distribution. For both series a superparamagnetic behaviour was
evidenced by means of magnetisation and EPR measurements with peculiar features
ascribable to the different grain sizes and morphology. Preliminary
magnetoresistivity measurements show enhanced low-field (< 1 T)
magnetoresistance values which suggest an interesting applicative use of these
manganites.Comment: 31 Pages 10 Figures to appear in Chem. Mate
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