1,720,973 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
The indigenous agroforestry systems of the south-eastern Rift Valley escarpment, Ethiopia : Their biodiversity, carbon stocks, and litterfall
No full textAgroforestry systems integrate trees into agricultural landscapes and provide a number of ecosystem services. Studies on agroforestry systems have so far mainly focused on their spatial design, food production, soil fertility management and system interactions, and little attention has been given to their ecosystem services, such as biodiversity conservation and carbon sequestration.
The objectives of the study were to determine and evaluate the floristic diversity, the above- and below-ground biomass carbon (C) and soil organic carbon (SOC) stocks, and the litterfall production and associated C and nitrogen (N) fluxes of three indigenous agroforestry systems in south-eastern Rift valley escarpments, in Gedeo, Ethiopia. Three indigenous agroforestry systems studied were Enset (Ensete ventricosum (Welw.) Cheesman), Enset-coffee, and Fruit-coffee. C stocks in biomass and soil (0 60 cm layer) (Mg C ha-1) were determined for each agroforestry system, and litterfall collected for seven woody species for a period of 12 months. Allometric equations were derived to estimate the biomass of enset and coffee while published allometric equations were used to determine the biomass of other tree and shrub species. The biomass values were then converted into C stocks.
A total of 58 woody species, belonging to 49 genera and 30 families were recorded. Of all woody species identified, 86% were native. The Enset and Enset-coffee systems contained the highest proportion native woody species (92% and 89%, respectively). In all, 22 native woody species were recorded as of interesLyhennelmät for conservation using International Union for Conservation of Nature (IUCN) Red lists and local criteria.
The square power equation using stump diameter at 40 cm (d40), Y = b1d402 (R2 > 0.80) and the power equation using d10 (diameter at 10 cm height) and height, Y=b1d10b2hb3 (R2 > 0.90) were found to be the best for predicting aboveground biomass of coffee (Coffea arabica L.) and total biomass of enset, respectively. The agroforestry C stock (biomass C plus SOC) was the highest for the Enset-coffee system (293 Mg C ha-1) and the lowest for the Enset (235 Mg C ha-1) system. Biomass (above- and belowground) C stocks were the highest for the Enset-coffee system (116 ±65 Mg C ha-1), followed by Fruit-coffee (79 ±24) and Enset (49 ±44) systems. Trees (fruit and non-fruit) formed 81, 89 and 80% of total biomass C stocks for Enset, Enset-coffee and Fruit-coffee agroforestry systems, respectively; the remainder being coffee, enset, litter, herbaceous plants, and fine root biomass. SOC to biomass C ratios were 4:1 for the Enset system, 2:1 for Fruit-coffee system, and 1.5:1 for the Enset-coffee system.
Monthly litterfall production per unit crown area decreased in the order: Croton macrostachyus Del. > Erythrina brucei Schweinf. > Cordia africana Lam. > Persea americana Mill. > Mangifera indica L. > Coffea arabica L. > Millettia ferruginea (Hochst.) Bak. The annual litterfall production (sum of seven species) averaged 7430 kg ha-1(land area) for the Enset system, 10187 for the Enset-coffee system and 12938 for the Fruit-coffee system. The associated annual C fluxes (kg ha-1) were 2803 (Enset system), 3928 (Enset-coffee system) and 5145 (Fruit-coffee system) and the corresponding N fluxes were 190 (kg ha-1), 257 and 278.
This research shows that the native woody species and C stocks observed in the three indigenous agroforestry systems were among the highest reported for tropical agroforestry systems. Thus, it should be given more attention, to counteract the local threat of these species from the wild and offset greenhouse gases (GHGs) emission. The indigenous agroforestry systems of the south-eastern Rift Valley escarpment in Ethiopia form a win-win opportunity by supporting livelihoods and providing food for a dense human population while also maintaining native floristic diversity and mitigating climate change through carbon sequestration. Key words Biomass, Carbon sequestration, Coffee, Enset, Floristic diversity, Gedeo, Indigenous agroforestry system, Litterfall fluxes, South-eastern EthiopiaPeltometsäjärjestelmät turvaavat puiden säilymisen maatalousalueilla ja tarjoavat monia ekosysteemipalveluja. Näiden järjestelmien tutkimus on tähän saakka painottunut eri osakomponenttien yhdistelyvaihtoehtoihin ja keskinäiseen vuorovaikutukseen, ruoantuotannon lisäämisen mahdollisuuksiin sekä maaperän ravinnetalouteen. Sen sijaan vain vähän huomiota on kiinnitetty peltometsäviljelyn tuottamiin ekosysteemipalveluihin. Tämän tutkimuksen tavoitteena oli mitata perinteisissä peltometsäjärjestelmissä kasvilajiston monimuotoisuutta, maanpäällisen ja maanalaisen biomassan hiilen määrää, maaperän orgaanisen hiilen määrää sekä karikkeen muodostumista ja siihen liittyvää hiilen ja typen kiertoa. Tutkimuspaikkana oli Suuren hautavajoamalaakson reunajyrkänne Gedeon lähellä Etiopiassa.
Tulokset osoittavat, että puulajistoltaan rikkaimpia olivat paikallisen kotoperäisen, banaanikasvien heimoon kuuluvan enset-ravintokasvin vallitsemat peltometsäjärjestelmät. Enemmän kaupalliseen tuotantoon keskittyvät järjestelmät olivat puulajistoltaan köyhempiä, ja niissä esiintyi yleisesti vieraita viljelypuulajeja.
Kolmessa erilaisessa perinteisessä peltometsäjärjestelmässä nyt mitattu hiilen määrä oli korkeimpia mitä yleensä on tavattu trooppisessa peltometsäviljelyssä. Johtopäätöksenä oli että nämä Hautavajoamalaakson rinteiden perinteiset peltometsäjärjestelmät Etiopiassa tuottavat moninkertaisen hyödyn. Ne turvaavat viljelijöiden ruoantuotannon ja toimeentulon alueella, jolla väestön tiheys on suuri, samalla kun ne toimivat paikallisen kasvilajiston monimuotoisuuden turvaajina ja hillitsevät, suuren hiilensidontakykynsä vuoksi, myös ilmastonmuutosta.
Avainsanat: Biomassa, Hiilen sidonta, Kahvi, Enset, Gedeo, Perinteinen peltometsäviljely, Karikkeen ravinnekierto, Alkuperäislajit, Kaakkois-Etiopiaei saavutettav
Combretum-Terminalia vegetation accumulates more carbon stocks in the soil than the biomass along the elevation ranges of dryland ecosystem in Southern Ethiopia
No full textVariations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
