570 research outputs found
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A quantitative narrative on movement, disease and patch exploitation in nesting agent groups
Abstract Animal relocation data has recently become considerably more ubiquitous, finely structured (collection frequencies measured in minutes) and co-variate rich (physiology of individuals, environmental and landscape information, and accelerometer data). To better understand the impacts of ecological interactions, individual movement and disease on global change ecology, including wildlife management and conservation, it is important to have simulators that will provide demographic, movement, and epidemiology null models against which to compare patterns observed in empirical systems. Such models may then be used to develop quantitative narratives that enhance our intuition and understanding of the relationship between population structure and generative processes: in essence, along with empirical and experimental narratives, quantitative narratives are used to advance ecological epistemology. Here we describe a simulator that accounts for the influence of consumer-resource interactions, existence of social groups anchored around a central location, territoriality, group-switching behavior, and disease dynamics on population size. We use this simulator to develop new and reinforce existing quantitative narratives and point out areas for future study. Author summary The health and viability of species are of considerable concern to all nature lovers. Population models are central to our efforts to assess the numerical and ecological status of species and threats posed by climate change. Models, however, are crude caricatures of complex ecological systems. So how do we construct reliable assessment models able to capture processes essential to predicating the impacts of global change on population viability without getting tied up in their vast complexities? We broach this question and demonstrate how models focusing at the level of the individual (i.e., agent-based models) are tools for developing robust, narratives to augment narratives arising purely from empirical data sources and experimental outcomes. We do this in the context of nesting social groups, foraging for food, while exhibiting territoriality and group-switching behavior; and, we evaluate the impact of disease on the viability of such populations
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Adequacy of SEIR models when epidemics have spatial structure: Ebola in Sierra Leone.
Dynamic SEIR (Susceptible, Exposed, Infectious, Removed) compartmental models provide a tool for predicting the size and duration of both unfettered and managed outbreaks-the latter in the context of interventions such as case detection, patient isolation, vaccination and treatment. The reliability of this tool depends on the validity of key assumptions that include homogeneity of individuals and spatio-temporal homogeneity. Although the SEIR compartmental framework can easily be extended to include demographic (e.g. age) and additional disease (e.g. healthcare workers) classes, dependence of transmission rates on time, and metapopulation structure, fitting such extended models is hampered by both a proliferation of free parameters and insufficient or inappropriate data. This raises the question of how effective a tool the basic SEIR framework may actually be. We go some way here to answering this question in the context of the 2014-2015 outbreak of Ebola in West Africa by comparing fits of an SEIR time-dependent transmission model to both country- and district-level weekly incidence data. Our novel approach in estimating the effective-size-of-the-populations-at-risk ( Neff) and initial number of exposed individuals ( E0) at both district and country levels, as well as the transmission function parameters, including a time-to-halving-the-force-of-infection ( tf/2) parameter, provides new insights into this Ebola outbreak. It reveals that the estimate R0 â 1.7 from country-level data appears to seriously underestimate R0 â 3.3 - 4.3 obtained from more spatially homogeneous district-level data. Country-level data also overestimate tf/2 â 22 weeks, compared with 8-10 weeks from district-level data. Additionally, estimates for the duration of individual infectiousness is around two weeks from spatially inhomogeneous country-level data compared with 2.4-4.5 weeks from spatially more homogeneous district-level data, which estimates are rather high compared with most values reported in the literature. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'. This issue is linked with the subsequent theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'
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Simulation and Analysis of Animal Movement Paths using Numerus Model Builder
ABSTRACT Animal movement paths are represented by point-location time series called relocation data. How well such paths can be simulated, when the rules governing movement depend on the internal state of individuals and environmental factors (both local and, when memory is involved, global) remains an open question. To answer this, we formulate and test models able to capture the essential statistics of multiphase versions of such paths (viz., movement-phase-specific step-length and turning-angle means, variances, auto-correlation, and cross correlation values), as well as broad scale movement patterns. The latter may include patchy coverage of the landscape, as well as the existence of home-range boundaries and gravitational centers-of-movement (e.g., centered around nests). Here we present a Numerus Model Builder implementation of two kinds of models: a high-frequency, multi-mode, biased, correlated random walk designed to simulate real movement data at a scale that permits simulation and identification of path segments that range from minutes to days; and a model that uses statistics extracted from relocation dataâeither empirical or simulatedâto construct movement modes and phases at subhourly to daily scales. We evaluate how well our derived statistical movement model captures patterns produced by our more detailed simulation model as a way to evaluate how well derived statistical movement models may capture patterns occurring in empirical data
The Birth of a Nation as American Myth
The Birth of a Nation was one of the most important films of all time, both for its technical and aesthetic achievements and for its enduring legacy of racism. This paper uses Bruce Lincoln\u27s approach to myth as a form of discourse and Robert Bellah\u27s notion of civil religion to show how Birth might be understood as a mythic component of American civil religion. From this perspective, Birth serves as a paradigmatic story of American origins rooted in ideas of white supremacy. At the end of the article Oscar Micheaux\u27s work, Within our Gates, is used to briefly demonstrate filmic strategies for countering Birth as myth
Developing a survey instrument to evaluate tertiary chemistry students' attitudes and learning experiences
New Zealand tertiary institutions, like others worldwide, have experienced a decline in science and chemistry enrolments in recent times as students seek other career paths that they perceive to be more lucrative. In a previous article we described a qualitative study of the learning experiences of students enrolled in a first year chemistry course at a New Zealand tertiary institution. Researchers in education and science education have two choices of methodology, a qualitative or a quantitative approach, and each possesses advantages and disadvantages. Qualitative studies typically use resource intensive data gathering techniques such as interviews. These studies are useful in that they allow researchers to study issues of interest in great depth and, for example, allow investigators to probe for underlying reasons about students' views for abstract scientific concepts. However, because qualitative studies are more labour intensive, they typically involve only small numbers of participants, which in the minds of many researchers and teachers results in a lack of generalisability. In other words, it is not necessarily clear what implications the findings hold in other contexts. In contrast, quantitative studies involve larger numbers of participants. By the judicious use of statistical analysis, researchers can investigate changes and trends, and extrapolate their findings to a large (or target) population. However, whilst the results from quantitative studies are more generalisable, they are often less detailed. Hence researchers are confronted with a trade-off situation in which they must choose between the depth of understanding provided from qualitative studies, versus the generalisability of a quantitative approach: because of this dilemma, increasingly researchers employ a mixed methodology approach. In this paper we describe a quantitative study that complements previous qualitative work. We report on the development of a questionnaire that investigates tertiary level learning experiences of chemistry students, along with their attitude toward chemistry and chemistry self-efficacy
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Rate of photosynthetic induction in fluctuating light varies widely among genotypes of wheat.
Crop photosynthesis and yield are limited by slow photosynthetic induction in sunflecks. We quantified variation in induction kinetics across diverse genotypes of wheat for the first time. Following a preliminary study that hinted at wide variation in induction kinetics across 58 genotypes, we grew 10 genotypes with contrasting responses in a controlled environment and quantified induction kinetics of carboxylation capacity (Vcmax) from dynamic A versus ci curves after a shift from low to high light (from 50 ”mol m-2 s-1 to 1500 ”mol m-2 s-1), in five flag leaves per genotype. Within-genotype median time for 95% induction (t95) of Vcmax varied 1.8-fold, from 5.2 min to 9.5 min. Our simulations suggest that non-instantaneous induction reduces daily net carbon gain by up to 15%, and that breeding to speed up Vcmax induction in the slowest of our 10 genotypes to match that in the fastest genotype could increase daily net carbon gain by up to 3.4%, particularly for leaves in mid-canopy positions (cumulative leaf area index â€1.5 m2 m-2), those that experience predominantly short-duration sunflecks, and those with high photosynthetic capacities
Crooked Arrows
This is a film review of Crooked Arrows (2012), directed by Steve Rash
Design Performance Measurement in the Construction Sector: A Pilot Study
This paper examines the role and deployment of design performance measurements (DPMs) in the construction industry, focusing on the consulting engineering sector, the design 'heart' of construction. Compared with manufacturing, there has been very little research on the use of DPMs in construction, and firms often struggle to find appropriate performance indicators. Using results from structured questionnaires, the paper shows that the few DPMs which do exist focus mainly on cost. Other measures are needed to address quality, innovative performance and client satisfaction. In contrast to manufacturing, DPMs in construction also need to address the project-based, multi-firm and non-routine nature of construction design, as well as the separation of design from manufacturing, build and operation. Interviews and workshops with industrialists were used to identify recent DPM practices in construction and combine these with lessons from other sectors. The resulting DPM tools provide guidance on how to: (a) integrate design into wider business processes in construction; (b) identify key design indicators, at both project and firm level; and (c) use DPMs to provide a balanced scorecard for design performance.performance indicators, design integration, design indicators, construction industry
The brow-antlered deer in Burmaâits distribution and status
Two of the three subspecies of brow-antlered deer are endangered and only the Burmese subspecies is still relatively abundant. Even so, it is a species of major concern in Burma. The authors describe the results of their surveys to determine the deer's status, the main threats to its survival and what needs to be done to conserve i
A solution to Darwinâs dilemma of 1859 : Exceptional preservation in Salterâs material from the late Ediacaran Longmyndian Supergroup, England
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