1,720,966 research outputs found
Importance of timing: Vulnerability of semi-arid rangeland systems to increased variability in temporal distribution of rainfall events as predicted by future climate change
No full textIntegrating spatio-temporal variation in resource availability and herbivore movements into rangeland management: RaMDry—An agent-based model on livestock feeding ecology in a dynamic, heterogeneous, semi-arid environment
No full textReproductive and economic performance of local livestock in southwestern Madagascar: Potentials and constraints of a highly extensive system
No full textIn the dry Mahafaly region of southwestern Madagascar, livestock keeping plays a key role in people's livelihoods. Especially zebu cattle and goats are socially important and contribute considerably to regular income of local households. We therefore analyzed the reproductive performance of local breeds along with livestock owners' culling strategies to determine herd dynamics, opportunities for economic development, as well as potential improvements, by using a combined methodical, both production-oriented and economic approach. Data was collected through interviews on the progeny history of breeding females (506 cows and 593 does) and their offspring (721 calves and 1073 kids). Based on the results, reproduction parameters were calculated and entered into the PRY Herd Life model to simulate herd development for present management (status quo) and two alternate scenarios assuming either (i) improved feeding and resulting higher productivity of breeding females or (ii) improved culling. Based on prices collected at local markets, a Monte Carlo simulation was used to estimate annual costs and revenues from livestock keeping. Age at first parturition was 40.5 +/- 11.2 months for cattle and 213 +/- 9.8 months for goats. Females from both species showed long parturition intervals (cattle 24.2 +/- 8.7 months, goats 12.4 +/- 5.7 months) whereas reported offspring mortality was low with 2.5% of cattle and 18.8% of goats dying before reaching maturity. On the other hand, market prices, especially for zebus, were quite high, leading to annual contribution margins of 33 per cattle unit and 11 (sic) per goat unit. The simulations indicated that improved feeding could support substantial herd expansion and productive offtake rates, whereas,improved culling would stabilize livestock numbers and concomitantly increase monetary herd output. Even though the current livestock husbandry system appears profitable, it might reach its limits in the near future due to the region's restricted ecological carrying capacity. Increasing livestock offtake would allow livestock keepers to raise their economic benefit without compromising herd development or enhancing the pressure on pasture resources. (C) 2016 Elsevier Ltd. All rights reserved
Assessing protected area effectiveness in western Tanzania: Insights from repeated line transect surveys
Full text linkA research article was submitted to The African Journal of Ecology Volume 61, Issue 3 September 2023In many parts of East Africa, wildlife populations have declined over the past decades. Given these trends, site-based studies are needed to assess how protected areas with differing management strategies enable the effective conservation of wildlife populations. In Tanzania, game reserves are managed for tourist hunting, while national parks are managed for non-consumptive wildlife-based tourism. To assess the relative performance of these management strategies, we here focus on two areas: Rukwa Game Reserve (RGR) and Katavi National Park (KNP). Based on systematically designed line distance surveys in 2004 and 2021, we compared densities and group sizes of large mammal populations (African elephant, giraffe, buffalo, zebra, topi, and hartebeest) over time. Contrary to published ecosystem-wide declines observed in numerous species which considered earlier baselines, we did not detect significant population declines between 2004 and 2021. While these new results showing apparent stable populations do not invalidate earlier studies on wildlife declines, they could indicate a stabilisation phase after declines. This highlights the importance of considering appropriate temporal baselines and historical contexts when assessing conservation effectiveness
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
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
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