3,204 research outputs found
Trade-offs in the use of direct and indirect indicators of ecosystem degradation for risk assessment
Ecosystem risk assessments estimate the likelihood of major transformations (ecosystem collapse) over a specified time frame. They require an understanding of the biotic and abiotic processes that drive declines. Relative Severity and Extent of Decline quantify essential dimensions of ecosystem degradation as part of the International Union for the Conservation of Nature (IUCN) Red List of Ecosystems risk assessment protocol. These flexible and powerful concepts are operationalised through ecosystem-specific indicators of functional decline. Here, we examine trade-offs in risk assessment between direct, yet data-demanding indicators and indirect indicators that are more widely applicable with global data sets. Using a case study of multiple tropical glacier ecosystems, we compared estimates of risk based on a direct indicator of functional decline (ice mass) with those based on an indirect indicator (bioclimatic suitability). The direct estimate of Relative Severity was based on the projected changes in ice mass using a glacier ice mass balance and dynamics model, while the indirect estimate was calculated from the expected changes in suitability based on a correlative habitat suitability model parameterised with current occurrence records. For reference, we calculated probability of ecosystem collapse from simulations of the ice mass balance and dynamics model. We found that the indirect indicator systematically underestimated risks of ecosystem collapse compared to the direct indicator and returned a different rank order of risks across glaciers due to prominent discrepancies in some units. Small and isolated glaciers located outside the tropical Andes are uniformly exposed to high levels of degradation and have high probabilities of collapse before 2080, whereas tropical Andean glaciers exhibit different rates of degradation, but are expected to undergo very severe degradation before 2100. For these larger units a detailed analysis of spatial differences in future projections could inform regional and local strategies for future monitoring, management and conservation action that can benefit people and nature. Evaluating Relative Severity and Extent of Decline over time and with different ecosystem-specific indicators allowed us to describe trends across a group of functionally similar ecosystem types and compare their performance in assessment units of different size and risk of collapse. The methods could be applied to other ice or snow-dependent ecosystems, while the case study should be instructive for development of risk indicators in many other ecosystem types
Shifting cultivation and hunting across the savanna-forest mosaic in the Gran Sabana, Venezuela: Facing changes
Background. Human encroachment and overexploitation of natural resources in the Neotropics is constantly increasing. Indigenous communities all across the Amazon, are trapped between a population rise and a hot debate about the sustainability of hunting rates. The Garden Hunting hypothesis states that shifting cultivation schemes (conucos) used by Amazon indigenous communities may generate favorable conditions, increasing abundance of small and medium wildlife species close to the `gardens' providing game for indigenous hunters. Methods. Here, we combined camera trap surveys and spatially explicit interview dataset on Pemón indigenous hunting scope and occurrence in a mosaic of savanna and forest in the Gran Sabana, Venezuela to evaluate to what extent the wildlife resource use corresponds to Garden Hunting hypothesis. We applied the Royle_Nichols model and binomial regression in order to: (1) assess whether abundance of small and medium wildlife species is higher close to conucos and (2) evaluate whether hunters select hunting localities based on accessibility to wildlife resources (closeness to conuco) more than wildlife abundance. Results. We find mixed evidence supporting the Garden Hunting hypothesis predictions. Abundance of small and medium species was high close to conucos but the pattern was not statistically significant for most of them. Pemón seem to hunt in locations dominated by forest, where species abundance was predicted to be higher, than in close vicinity to conucos. Hunting scope was focused on the most abundant species located close to the conuco (Cuniculus paca), but also in less abundant and unavailable species (Crax alector, Tapirus terrestris and Odocoileus virginianus). Conclusions. Our research provided the first attempt of a systematic sampling survey in the Gran Sabana, generating a quantitative dataset that not only describes the current pattern of wildlife abundance, but sets the base-line to monitor temporal and spatial change in this region of highland Amazon. We discuss the applicability of the estimates generated as a baseline as well as, environmental challenges imposed by economic, social and cultural changes such as mining encroachment for wildlife management. Subjects Anthropology, Biodiversity, Conservation Biology, Ecology, Natural Resource Management
Leveraging limited data from wildlife monitoring in a conflict affected region in Venezuela
Efficient monitoring of biodiversity-rich areas in conflict-affected areas with poor rule of law requires a combination of different analytical approaches to account for data biases and incompleteness. In the upland Amazon region of Venezuela, in Canaima National Park, we initiated biodiversity monitoring in 2015, but it was interrupted by the establishment of a large-scale mining development plan in 2016, compromising the temporal and geographical extent of monitoring and the security of researchers. We used a resource selection function model framework that considers imperfect detectability and supplemented detections from camera trap surveys with opportunistic off-camera records (including animal tracks and direct sighting) to (1) gain insight into the value of additional occurrence records to accurately predict wildlife resource use in the perturbated area (deforestation, fire, swidden agriculture, and human settlements vicinity), (2) when faced with security and budget constraints. Our approach maximized the use of available data and accounted for biases and data gaps. Adding data from poorly sampled areas had mixed results on estimates of resource use for restricted species, but improved predictions for widespread species. If budget or resources are limited, we recommend focusing on one location with both on-camera and off-camera records over two with cameras. Combining camera trap records with other field observations (28 mammals and 16 birds) allowed us to understand responses of 17 species to deforestation, 15 to fire, and 13 to swidden agriculture. Our study encourages the use of combinations of methods to support conservation in high-biodiversity sites, where access is restricted, researchers are vulnerable, and unequal sampling efforts exist
Strong correlations between text quality and complex networks features
Concepts of complex networks have been used to obtain metrics that were
correlated to text quality established by scores assigned by human judges.
Texts produced by high-school students in Portuguese were represented as
scale-free networks (word adjacency model), from which typical network features
such as the in/outdegree, clustering coefficient and shortest path were
obtained. Another metric was derived from the dynamics of the network growth,
based on the variation of the number of connected components. The scores
assigned by the human judges according to three text quality criteria
(coherence and cohesion, adherence to standard writing conventions and theme
adequacy/development) were correlated with the network measurements. Text
quality for all three criteria was found to decrease with increasing average
values of outdegrees, clustering coefficient and deviation from the dynamics of
network growth. Among the criteria employed, cohesion and coherence showed the
strongest correlation, which probably indicates that the network measurements
are able to capture how the text is developed in terms of the concepts
represented by the nodes in the networks. Though based on a particular set of
texts and specific language, the results presented here point to potential
applications in other instances of text analysis.Comment: 8 pages, 8 figure
Creating a GUI for Zori, a Quantum Monte Carlo Program
Rappture is a new GUI development kit that enables developers to build I/O interfaces for specific applications. In this article, the authors describe the Rappture toolkit's use in generating a GUI for the Zori computer code
Statistical Laws Governing Fluctuations in Word Use from Word Birth to Word Death
We analyze the dynamic properties of 10^7 words recorded in English, Spanish
and Hebrew over the period 1800--2008 in order to gain insight into the
coevolution of language and culture. We report language independent patterns
useful as benchmarks for theoretical models of language evolution. A
significantly decreasing (increasing) trend in the birth (death) rate of words
indicates a recent shift in the selection laws governing word use. For new
words, we observe a peak in the growth-rate fluctuations around 40 years after
introduction, consistent with the typical entry time into standard dictionaries
and the human generational timescale. Pronounced changes in the dynamics of
language during periods of war shows that word correlations, occurring across
time and between words, are largely influenced by coevolutionary social,
technological, and political factors. We quantify cultural memory by analyzing
the long-term correlations in the use of individual words using detrended
fluctuation analysis.Comment: Version 1: 31 pages, 17 figures, 3 tables. Version 2 is streamlined,
eliminates substantial material and incorporates referee comments: 19 pages,
14 figures, 3 table
Fostering the healthcare workforce during the COVID‐19 pandemic: Shared leadership, social capital, and contagion among health professionals
Health professionals managing patients with COVID-19 disease are at high risk of contagion. All medical personnel involved in caring for patients need coordination, knowledge and trust. Empirical work on human resources has tended to focus on the effects of human resource practices on performance, whereas leadership and social interactions have been overlooked. Based upon interviews with medical staff working in specialised medical units, this study uses the social capital theory to examine relationships among shared leadership, social capital, and contagion rates. First, shared leadership was found to positively affect COVID-19 contagion among health professionals. Second, by sharing information and a common language, and showing high levels of trust, namely social capital, medical units seem to reduce contagion rates of COVID-19. In other words, shared leadership plays a fundamental role in improving performance in healthcare by means of social capital
Domain-wall profile in the presence of anisotropic exchange interactions: Effective on-site anisotropy
Starting from a D-dimensional XXZ ferromagnetic Heisenberg model in an
hypercubic lattice, it is demonstrated that the anisotropy in the exchange
coupling constant leads to a D-dependent effective on-site anisotropy
interaction often ignored for D>1. As a result the effective width of the wall
depends on the dimensionality of the system. It is shown that the effective
one-dimensional Hamiltonian is not the one-dimensional XXZ version as assumed
in previous theoretical work. We derive a new expression for the wall profile
that generalizes the standard Landau-Lifshitz form. Our results are found to be
in very good agreement with earlier numerical work using the Monte Carlo
method. Preceding theories concerning the domain wall contribution to
magnetoresistance have considered the role of D only through the modification
of the density of states in the electronic band structure. This Brief Report
reveals that the wall profile itself contains an additional D dependence for
the case of anisotropic exchange interactions.Comment: 4 pages; new title and abstract; 1 figure comparing our results with
earlier numerical work; a more general model containing the usual on-site
anisotropy; new remarks and references on the following two topics: (a)
experimental evidence for the existence of spin exchange anisotropy, and (b)
preceding theories concerning the domain wall contribution to
magnetoresistance; to appear in Phys. Rev.
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