1,720,974 research outputs found
A spatially explicit agent-based model of the interactions between jaguar populations and their habitats
No full textAgent-based models can predict system-level properties of populations from stochastic simulation of fine-scale movements. One important application to conservation lies in their ability to consider the impact of individual variation in movement and decision-making on populations under future landscape changes. Here, we present a spatially explicit agent-based simulation of a population of jaguars (Panthera onca) in a mixed forest and farmland landscape in Central America that demonstrates an application of least-cost modelling, a description of the way that agents move through their environment, to equilibrium population dynamics. We detail the construction and application of the model, and the processes of calibration, sensitivity analysis and validation with empirical field data. Simulated jaguars underwent feeding, reproduction, and mortality events typical of natural populations, resulting in realistic population dynamics and home range sizes. Jaguar agents located inside protected forest reserves exhibited higher fitness (fecundity, energy reserves, age and age of mortality) as well as lower energy- and habitat-related mortality than jaguar agents located outside these reserves. Changes in fecundity directly affected the dynamics of simulated populations to a larger degree than either mortality or agent–agent interactions. Model validation showed similar patterns to camera traps in the field, in terms of landscape utilisation and the spatial distribution of individuals. The model showed less sensitivity to socially motivated and fine-scale movements, apart from those directed towards feeding and reproduction, but reflected the interactions and movement of naturally occurring populations in this region. Applications of the model will include testing impacts on population dynamics of likely future changes in landscape structure and connectivity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Jaguar (Panthera onca) density and tenure in a critical biological corridor
No full textWe estimated jaguar density and tenure, and investigated ranging behavior, using camera traps across the Maya Forest Corridor, a human-influenced landscape in central Belize that forms the only remaining connection for jaguar populations inhabiting two regional forest blocks: the Selva Maya and the Maya Mountain Massif. Jaguars were ubiquitous across the study area. Similar to the neighboring Selva Maya, mean density ranged from 1.5 to 3.1 jaguars per 100 km2, estimated by spatial capture-recapture models. Cameras detected almost twice as many males as females, probably reflecting detection bias, and males ranged more widely than females within the camera grid. Both sexes crossed two major rivers, while highway crossings were rare and male-biased, raising concern that the highway could prevent female movement if traffic increases. Jaguars were more transient where the landscape was fragmented with settlements and agriculture than in contiguous forest. Compared with jaguars in the protected forests of the Maya Mountains, jaguars in central Belize displayed a lower potential for investment in intraspecific communication, indicative of a lower quality landscape; however, we did detect mating behavior and juveniles. Tenure of individuals was shorter than in the protected forests, with a higher turnover rate for males than females. At least three-quarters of reported jaguar deaths caused by people were male jaguars, and the majority was retaliation for livestock predation. Jaguars seem relatively tolerant to the human-influenced landscape of central Belize. However, intensification of game hunting and lethal control of predators would threaten population persistence, while increased highway traffic and clear-cutting riparian forest would severely limit the corridor function. Our results show that the viability of the corridor, and thus the long-term survival of jaguar populations in this region, will depend on appropriate land-use planning, nonlethal control of livestock predators, enforcement of game hunting regulations, and wildlife-friendly features in future road developments
Food habits of sympatric jaguars and pumas across a gradient of human disturbance
No full textJaguars Panthera onca coexist with pumas Puma concolor across their entire range. In areas where they occur together their coexistence may be facilitated by differences in diet. This study compared food habits of jaguars and pumas in Belize, Central America, across a protected lowland rainforest and the neighbouring human-influenced landscape. Diets were determined from 362 jaguar scats and 135 puma scats, identified by genetic analysis. In the protected forest, dietary breadths were low for jaguars and pumas and showed little overlap. In this habitat each relied heavily on a single medium-sized (5–10 kg) prey species: armadillos Dasypus novemcinctus for jaguars, and pacas Agouti paca for pumas. Both cats also took larger prey (>10 kg), mainly white-lipped peccaries Tayassu pecari by jaguars and red brocket deer Mazama americana by pumas. In unprotected fragmented lands, jaguar scats rarely contained large wild prey species; rather, a diet of relatively small wild prey was supplemented with larger domestic species. Pumas did not take domestic species and were scarce outside the protected forest, possibly indicating competition with humans for pacas and deer, which are also prized game species in the region. This study is the largest analysis to date of sympatric jaguar and puma diets in both forest and farmland. We suggest that jaguar predation on cattle may be reduced by ensuring that game hunting is sustainable and potentially by augmenting forests within the human matrix with large wild ungulates. The supplementation could benefit both of the cat species, and the local game hunting economy.<br/
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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