3,112 research outputs found
Introduction to big data and data science: Methods and applications
No full textBig data and data science are transforming our world today in ways we could not have imagined at the beginning of the twenty-first century. The accompanying wave of innovation has sparked advances in healthcare, engineering, business, science, and human perception, among others. In this chapter we discuss big data and data science to establish a context for the state-of-the-art technologies and applications in this book. In addition, to provide a starting point for new researchers, we present an overview of big data management and analytics methods. Finally, we suggest opportunities for future research
Wren, C R, VX38422
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/427307Surname: WREN. Given Name(s) or Initials: C R. Military Service Number or Last Known Location: VX38422. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 32029.250322
Item: [2016.0049.59568] "Wren, C R, VX38422
Fiscal Stabilisation Policy and Fiscal Institutions
No full textIn this paper we analyse countercyclical fiscal policy within the context of a microfounded analysis of business cycle stabilisation. We show that tax and spending instruments can have a useful counter cyclical role, even after allowing for the distortionary nature of the instruments and the need for debt sustainability. A critical barrier to the use of fiscal instruments may be political economy concerns, and we survey recent suggestions involving alternative fiscal policy institutions.
Conservation Genetics of Alpine Rock Wren (Xenicus gilviventris)
No full textMany species occur in naturally subdivided populations due to spatial heterogeneity of the landscape. Such a pattern is especially evident in alpine species, where naturally fragmented habitat forms an ‘alpine archipelago’. High altitude habitat patches and the species they harbour can serve as effective models for monitoring global change processes in sensitive ecosystems.
The rock wren (Xenicus gilviventris) is a threatened alpine passerine belonging to the endemic New Zealand wren family (Acanthisittidae). This ancient family was once represented by at least seven species, however due to the impacts of introduced mammalian predators, only two species remain. Conservation management of rock wren has only recently commenced via the translocation of individuals to offshore islands, but genetic considerations are not currently a part of management practices. In this thesis, I investigated the role of genetic factors in the conservation management of rock wren and applied my findings to improve understanding of the species’ ecology and better inform future management efforts.
I sampled rock wren (n=221) from throughout their range and using 14 microsatellite markers combined with nuclear and mitochondrial DNA sequence data, describe significant differences in genetic variation and differentiation between rock wren populations across the South Island. A deep North–South genetic divergence was evident (3.7 ± 0.5% at cytochrome b), consistent with the ‘biotic gap’ hypothesis whereby Northern and Southern populations became restricted in ice-free refugia during the Pleistocene era of extensive glaciation c. 2 mya. There is some evidence for a larger refugium within the south of the rock wren’s range, as estimates of genetic variation and long-term effective population size are consistently larger for the Southern lineage. Although this finding may also be indicative of more optimal habitat in the south of the species’ range; supporting a higher density of rock wren long-term. Designation of Northern and Southern rock wren lineages as separate evolutionarily significant units (ESUs) is proposed.
Estimates of the long-term effective population size of rock wren are dramatically larger relative to contemporary estimates, indicating that in the past, rock wren sustained a much higher abundance than today. Whilst a genetic signature linking population decline within the Northern lineage to a timeframe of anthropogenic disturbance (i.e. the past c. 100 years) was not detected, there is some evidence for a recent population bottleneck within this timeframe in the South. This suggests that although natural historical climate fluctuations have clearly played an important role driving patterns of rock wren abundance in the past, these impacts are now being compounded by much more recent anthropogenic impacts, most likely, predation by introduced mammalian predators.
Significant fine-scale spatial genetic structure in rock wren was also detected, and a strong pattern of isolation by distance whereby genetic relatedness among neighbouring individuals is significantly greater than that among more distant or randomly located individuals. This pattern of gene flow is indicative of a stepping stone model of dispersal. A potential sex-bias in dispersal, suggestive of male natal philopatry, was also detected which may have further contributed to the strong pattern of fine-scale structuring. The spatial scale of positive genetic structure or ‘genetic patch size’ (i.e. the distance over which individuals were not genetically independent) was unexpectedly large (c.70 km) given the rock wren’s limited flight ability. Asymmetrical gene flow is also evident among populations within the Southern lineage, indicative that source-sink dynamics are operating. The Murchison Mountains appear to be a particularly important source of migrants for other populations. Therefore, management efforts, such as predator control, to ensure this population is conserved should be prioritised. Conversely, the Upper Hollyford and Lake Roe populations appear to be functioning as sink populations, with migration occurring into, but not out of these areas. By improving habitat quality in these areas (e.g. by controlling invasive species) there is potential that they may be converted from sinks into new source populations
QUANTITATIVE DESCRIPTION OF NESTS AND EGGS OF THE ISTHMIAN WREN CANTORCHILUS ELUTUS AND CABANIS'S WREN C. MODESTUS
No full textInformation on the nests (for reproduction and dormitory) and eggs of Cabanis's Wren Cantorchilus modestus and Isthmian Wren C. elutus is incomplete and limited to old records. Here, I describe quantitatively the reproductive nests and eggs of both species, and dormitory nests of Cabanis's Wren. Reproductive nests of both species were similar in size and structure: globular, with a lateral circular entrance, nests sometimes have an entrance tail and are a very dense structure made of dry vegetation fibers. However, Cabanis’s Wren dormitory nests were highly variable in their form (e.g., closed globular, low cup, and platform), with a weak structure of dry vegetation fibers that allowed an easy view of the interior from outside. The eggs were plain white, similar to those of other species within this genus.
Using historical woodland creation to construct a long-term, large-scale natural experiment: The WrEN project
No full textNatural experiments have been proposed as a way of complementing manipulative experiments to improve ecological understanding and guide management. There is a pressing need for evidence from such studies to inform a shift to landscape-scale conservation, including the design of ecological networks. Although this shift has been widely embraced by conservation communities worldwide, the empirical evidence is limited and equivocal, and may be limiting effective conservation. We present principles for well-designed natural experiments to inform landscape-scale conservation and outline how they are being applied in the WrEN project, which is studying the effects of 160years of woodland creation on biodiversity in UK landscapes. We describe the study areas and outline the systematic process used to select suitable historical woodland creation sites based on key site- and landscape-scale variables – including size, age, and proximity to other woodland. We present the results of an analysis to explore variation in these variables across sites to test their suitability as a basis for a natural experiment. Our results confirm that this landscape satisfies the principles we have identified and provides an ideal study system for a long-term, large-scale natural experiment to explore how woodland biodiversity is affected by different site and landscape attributes. The WrEN sites are now being surveyed for a wide selection of species that are likely to respond differently to site- and landscape-scale attributes and at different spatial and temporal scales. The results from WrEN will help develop detailed recommendations to guide landscape-scale conservation, including the design of ecological networks. We also believe that the approach presented demonstrates the wider utility of well-designed natural experiments to improve our understanding of ecological systems and inform policy and practice
Data from: Population structure within an alpine archipelago: strong signature of past climate change in the New Zealand rock wren (Xenicus gilviventris)
No full textNaturally subdivided populations such as those occupying high-altitude habitat patches of the ‘alpine archipelago’ can provide significant insight into past biogeographical change and serve as useful models for predicting future responses to anthropogenic climate change. Among New Zealand's alpine taxa, phylogenetic studies support two major radiations: the first correlating with geological forces (Pliocene uplift) and the second with climatic processes (Pleistocene glaciations). The rock wren (Xenicus gilviventris) is a threatened alpine passerine belonging to the endemic New Zealand wren family (Acanthisittidae). Rock wren constitute a widespread, naturally fragmented population, occurring in patches of suitable habitat over c. 900 m in altitude throughout the length of the South Island, New Zealand. We investigated the relative role of historical geological versus climatic processes in shaping the genetic structure of rock wren (N = 134) throughout their range. Using microsatellites combined with nuclear and mtDNA sequence data, we identify a deep north–south divergence in rock wren (3.7 ± 0.5% at cytochrome b) consistent with the glacial refugia hypothesis whereby populations were restricted in isolated refugia during the Pleistocene c. 2 Ma. This is the first study of an alpine vertebrate to test and provide strong evidence for the glacial refugia hypothesis as an explanation for the low endemicity central zone known as the biotic ‘gap’ in the South Island of New Zealand
Habitat and landscape characteristics that influence Sedge Wren (<italic>Cistothorus platensis</italic>) and Marsh Wren (<italic>C. palustris</italic>) distribution and abundance in Great Lakes coastal wetlands
No full textUniversity of Minnesota M.S. thesis. August 2013. Major: Integrated Biosciences. Advisor: Gerald J. Niemi. 1 computer file (PDF); v, 188 pages, appendices 1-7.I analyzed habitat and landscape characteristics important to the Sedge Wren (Cistothorus platensis) and Marsh Wren (C. palustris) in Great Lakes coastal wetlands using breeding bird census data from two large projects in 2002-2003 and 2011-2012. Little is known about the population or distribution of these species in the Great Lakes region. For each of 840 survey points in coastal wetlands along the U.S. and Canadian shorelines, I used National Land Cover Data and Ontario Land Cover Data to calculate the percent cover of seven different land use classes within 500, 1000, and 2000 m buffers of each point. I combined these with climatic and landscape configuration variables as well as field-collected vegetation data to develop classification trees that predicted both Sedge and Marsh Wren presence and relative high abundance (≥3 wrens/site). After eliminating geographic variables, the best classification trees predicted Sedge Wrens to be present in wetlands with greater than 9% woody wetlands at the 2000 m buffer, and in high abundance in sites with less than 3% cattails and greater than 4% meadow vegetation. Marsh Wren presence was positively associated with emergent vegetation and cropland, and negatively associated with woody wetland at the 500 m buffer. Marsh Wrens were predicted to be in high abundance at sites with greater than 14% cattails. This classification tree analysis is a powerful predictive tool which significantly increases our ability to correctly predict the presence of these secretive wetland species. These results provide a basic understanding of characteristics of Great Lakes coastal wetlands important to two wetland-obligate bird species and can be useful in conservation decisions and management plans.Panci, Hannah. (2013). Habitat and landscape characteristics that influence Sedge Wren (Cistothorus platensis) and Marsh Wren (C. palustris) distribution and abundance in Great Lakes coastal wetlands. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/160254
The Optimal Monetary Policy Response to Exchange Rate Misalignments
No full textA common feature of exchange rate misalignments is that they produce a divergence between traded and non-traded goods sectors, which appears to pose a dilemma for policy makers. In this paper we develop a small open economy model which features traded and non-traded goods sectors with which to assess the extent to which monetary policy should respond to exchange rate misalignments. To do so we initially contrast the efficient outcome of the model with that under flexible prices and find that the flex price equilibrium exhibits an excessive exchange rate appreciation in the face of a positive UIP shock. By introducing sticky prices in both sectors we provide a role for policy in the face of UIP shocks. We then derive a quadratic approximation to welfare which comprises quadratic terms in the output gaps in both sectors as well as sectoral rates of inflation. These can be rewritten in terms of the usual aggregate variables, but only after including terms in relative sectoral prices and/or the terms of trade to capture the sectoral composition of aggregates. We derive optimal policy analytically before giving numerical examples of the optimal response to UIP shocks. Finally, we contrast the optimal policy with a number of alternative policy stances and assess the robustness of results to changes in model parameters.
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