Research Assoc

Liège, Belgium

Research Assoc

Liège, Belgium
SEARCH FILTERS
Time filter
Source Type

Genetic and morphological analyses revealed that the type specimen of Hume's Owl Strix butleri, the geographical provenance of which is open to doubt, differs significantly from all other specimens previously ascribed to this species. Despite the absence of vocal data definitively linked to the same population as the type specimen, we consider that two specieslevel taxa are involved, principally because the degree of molecular differentiation is close to that seen in other taxa of Strix traditionally recognised as species. Partially complicating this otherwise straightforward issue is the recent description of "Omani Owl S. omanensis" from northern Oman based solely on photographs and sound-recordings. We consider that there is clear evidence of at least some morphological congruence between the butleri type and the phenotype described as "omanensis". As a result, we review the relative likelihood of three potential hypotheses: that "omanensis" is a synonym of butleri; that "omanensis" is a subspecies of butleri; or that "omanensis" and butleri both represent species taxa. Until such time as specimen material of "omanensis" becomes available for genetic and comparative morphological analyses, we recommend that this name be considered as a synonym of butleri, especially bearing in mind the possibility (not previously considered in detail) that the type of butleri could have originated in Arabia, specifically from Oman. We describe other populations heretofore ascribed to S. butleri as a new species. Copyright © 2015 Magnolia Press.


Harrison S.E.,University of Adelaide | Guzik M.T.,University of Adelaide | Harvey M.S.,Western Australian Museum | Harvey M.S.,University of Western Australia | And 4 more authors.
Invertebrate Systematics | Year: 2014

The Yilgarn and Pilbara regions of Western Australia are considered biodiversity hotspots for subterranean invertebrates. While the relatively well studied (aquatic) stygofauna are typically constrained to geographically isolated habitats ('subterranean islands') and have likely originated from multiple independent epigean ancestors, the troglofauna found in cavernicolous calcretes and fractured rock remains largely unstudied. Here we focus on the pseudoscorpion genera Tyrannochthonius Chamberlin, 1929 and Lagynochthonius Beier, 1951, as common components of the troglofauna, to determine whether they also display highly restricted distributional patterns, and have independent origins. Bayesian and maximum likelihood analyses of sequence data from the mtDNA cytochrome c oxidase I (COI) and the small subunit 18S nuclear genes for subterranean and epigean species from both genera reveal divergent mtDNA lineages that are restricted to single aquifers and/or geographic locations. This strong geographic structuring of troglobitic pseudoscorpions is indicative of short-range endemism and supports the 'subterranean island' hypothesis. Further, independent sister relationships between subterranean and epigean taxa indicate multiple invasions into subterranean habitats, likely driven by post-Miocene aridification, consistent with that predicted for the stygofauna. The phylogeny also reveals that Tyrannochthonius+Lagynochthonius is monophyletic but that Lagynochthonius is polyphyletic and nested inside Tyrannochthonius. The results of this study point to common processes that have shaped the diversity and uniqueness of both stygofaunal and troglofaunal communities in Western Australia. © CSIRO 2014.


Beckers J.-M.,University of Liège | Beckers J.-M.,Honorary Research Assoc | Barth A.,University of Liège | Barth A.,Research Assoc | And 2 more authors.
Ocean Science | Year: 2014

We present a method in which the optimal interpolation of multi-scale processes can be expanded into a succession of simpler interpolations. First, we prove how the optimal analysis of a superposition of two processes can be obtained by different mathematical formulations involving iterations and analysis focusing on a single process. From the different mathematical equivalent formulations, we then select the most efficient ones by analyzing the behavior of the different possibilities in a simple and well-controlled test case. The clear guidelines deduced from this experiment are then applied to a real situation in which we combine large-scale analysis of hourly Spinning Enhanced Visible and Infrared Imager (SEVIRI) satellite images using data interpolating empirical orthogonal functions (DINEOF) with a local optimal interpolation using a Gaussian covariance. It is shown that the optimal combination indeed provides the best reconstruction and can therefore be exploited to extract the maximum amount of useful information from the original data. © Author(s) 2014.


Chang Y.K.,Research Assoc | Zaman Q.,Dalhousie University | Esau T.,Dalhousie University | Schumann A.W.,University of Florida
Applied Engineering in Agriculture | Year: 2014

An automated sensing system consisting of hardware and software was developed for spot-application of herbicide in pruned wild blueberry fields. The hardware of the system consisted of a ruggedized PC, four digital cameras, a signal output unit, an 8-channel computerized variable rate controller (VRC), a flow controller, a pocket PC, solenoid valves, a servo valve, a flow meter, and nozzles mounted on an all-terrain vehicle. Custom software was developed in C++ and installed in the ruggedized PC to acquire images from the cameras and process in real-time to calculate the fraction of green pixels for weed detection in each image. Green contrast between weed and non-weed area in pruned wild blueberry fields was used to develop a robust and effective discriminating algorithm. Red-Green-Blue (RGB) images were converted to normalized green ratio binary images using the ratio of 255*G/(R+G+B) followed by segmentation for the discrimination. Custom software was capable of processing images to differentiate weed area from non-weed area in realtime and send the signal to the VRC to open the valve in the specific section of the boom where the weeds were detected. The normalized green ratio algorithm showed very reliable accuracy under different outdoor light conditions (>500 lux) and shade conditions. The sensing system performed well for accurate weed detection and for sending signals to the VRC for spraying the correct weed targets at up to 8 km ha-1 ground speed in the fields.


Van Vuuren M.,University of Pretoria | Penzhorn B.L.,University of Pretoria | Penzhorn B.L.,Research Assoc
OIE Revue Scientifique et Technique | Year: 2015

The role of African wildlife inthe occurrence of vector-borne infections in domestic animals has gained renewed interest as emerging and re-emerging infections occur worldwide at an increasing rate. In Africa, biodiversity conservation and the expansion of livestock production have increased the risk of transmitting vector-borne infections between wildlife and livestock. The indigenous African pathogens with transboundary potential, such as Rift Valley fever virus, African horse sickness virus, bluetongue virus, lumpy skin disease virus, African swine fever virus, and blood-borne parasites have received the most attention. There is no evidence for persistent vector-borne viral infections in African wildlife. For some viral infections, wildlife may act as a reservoir through the inter-epidemic circulation of viruses with mild or subclinical manifestations. Wildlife may also act as introductory or transporting hosts when moved to new regions, e.g. for lumpy skin disease virus, Rift Valley fever virus and West Nile virus. Wildlife may also act as amplifying hosts when exposed to viruses in the early part of the warm season when vectors are active, with spillover to domestic animals later in the season, e.g. with bluetongue and African horse sickness. Some tick species found on domestic animals are more abundant on wildlife hosts; some depend on wildlife hosts to complete their life cycle. Since the endemic stability of a disease depends on a sufficiently large tick population to ensure that domestic animals become infected at an early age, the presence of wildlife hosts that augment tick numbers may be beneficial. Many wild ungulate species are reservoirs of Anaplasma spp., while the role of wildlife in the epidemiology of heartwater (Ehrlichia ruminantium infection) has not been elucidated. Wild ungulates are not usually reservoirs of piroplasms that affect livestock; however, there are two exceptions: zebra, which are reservoirs of Babesia caballi and Theileria equi, and buffalo, which are reservoirs of Theileria parva. The latter causes Corridor disease when transmitted from buffaloto cattle, butthis appears to be a self-limiting condition, at least in southern Africa. Wild animals are important reservoirs of tsetse-transmitted Trypanosoma spp. infection. The distribution and abundance of some tsetse species, e.g. Glossina morsitans and G. pallidipes, are closely related to the occurrence of their preferred wildlife hosts.


Werner L.,University of California at Santa Cruz | McDowell C.,University of California at Santa Cruz | Denner J.,Research Assoc
SIGCSE 2013 - Proceedings of the 44th ACM Technical Symposium on Computer Science Education | Year: 2013

There is growing interest in how we can use computer logging data to improve computational tools and pedagogies to engage children in complex thinking and self-expression, but our techniques lag far behind our theories. Only recently have learning scientists begun to measure, collect, analyze, and report how data informs the science of children's learning. In this paper, we describe our initial efforts towards developing tools to mine computer logging data for information on how to enhance learning opportunities. The data were collected as part of an NSFfunded project, and include logs from 320 middle school students using Alice to program computer games in semester-long courses. We describe some lessons learned and decisions made in the process of reconstructing high-level user actions in Alice from low-level Alice logs. Copyright © 2013 ACM.

Loading Research Assoc collaborators
Loading Research Assoc collaborators