1,720,956 research outputs found
Estimation of Above-Ground Biomass using Vegetation Indices in a Selected Mangrove Vegetation in Thambalagam Bay, Trincomalee
No full textMangroves are extremely productive ecosystems along the coast that help to mitigate climate change by absorbing carbon dioxide from the atmosphere. Understanding the carbon storage capacity is critical for assessing these ecosystems' resilience and vulnerability to climate change. The aim of this study is to estimate carbon dioxide (CO2) absorption by mangroves and to find the equation to derive AGB using the best vegetation index for mangrove forest in the selected site of Thambalagam Bay using GIS and remote sensing techniques. The purposive sampling method was used to select a site from the mangrove forest around Thambalagam Bay in Trincomalee District. A field survey was carried out in the selected and the site was divided into five strata based on the species’ dominance and named according to the dominant species. The five stratas are Avicenia marina, Rhizophora, Multispecies, Luminetzera racemose, Avicenia officinalis. The fishnet tool divided each stratum into plots (10m×10m). Twenty sampling plots were taken based on Simple random sampling. AGB was calculated using allometric equations of each mangrove species in each plot. Finally, the total AGB of each stratum was calculated as (ton/ha). The above-ground carbon stock and CO2 absorption for each stratum were calculated as (ton/ha) using empirical equations;(AGC = AGB × 0.47), (Total CO2 absorbed = AGC (ton/ha) × 44/12). Vegetation indices (NDVI, SAVI, GNDVI, RVI) maps of the selected site for the year 2022 were prepared using ArcMap 10.8. Polynomial regression analysis between vegetation indices and AGB was carried out to find the best vegetation index to predict AGB using Minitab 17 statistical software. The best vegetation index was selected based on the high R2 value. Results of the polynomial regression analysis show NDVI had a strong correlation ( = 7232 − 20420 + 144822; r2=92.10%) with above-ground biomass (AGB) in the Thambalagamam Bay mangrove forest. Increasing order of total absorbed CO2 relevant to stratum are Luminetzera racemose (186.195 ton/ha), Multi species (439.858 ton/ha), Rhizopora mucronate (453.825 ton/ha), Avicena officinalis(675.937 ton/ha), Avicena marina (2635.572 ton/ha). In total, 4391.387 ton/ha of CO2 was absorbed by the selected site of the mangrove forest around Thambalagam bay. The study highlights the importance of efforts to preserve the long-term survival of mangrove ecosystems in the face of global climate change.
Keywords: Mangrove, Above-ground biomass (AGB), Above-ground carbon stock (AGC), CO2 absorption, Climate change
 
Assessing the Impact of Land Use Dynamics on Urban Heat Island Effect: A Remote Sensing Analysis of Vavuniya DSD, Sri Lanka (2003-2023)
No full textThe rapid expansion of human activities has caused significant Land Use and Land Cover changes, impacting local climate through Urban Heat Island (UHI) effect. Although many studies have focused on the impact of urban development on the UHI effect, this study addresses the combination effect of urban development, agricultural expansion, forest loss, and soil texture in the heat effect by examining the dynamics of LULC changes. The study explores temporal trends and spatial patterns of LULC changes in Vavuniya DSD and their correlation with Land Surface Temperature (LST). Landsat and MODIS datasets were used to classify LULC and generate LST maps through advanced Remote sensing techniques. The relationship between LST and LULC was analyzed using trend analysis, correlation analysis, analysis of variance (ANOVA), geostatistical analysis, and regression analysis. Key findings reveal significant expansion in built-up areas (0.84 km²/year) and agricultural land (1.96 km²/year), alongside a notable decline in forest cover (-2.865 km²/year). The linear trend model for Mean MODIS LST values (2003-2023) shows a positive trend: Yt =30.285+0.0187t, including an annual LST increase of 0.0187°C. Regression analysis indicates a strong correlation between LST and both NDBI and NDBSI, identifying urbanization, agricultural expansion, and deforestation as key drivers of LST increases. Moran’s I index shows a significant positive spatial autocorrelation in LST for all years (2003, 2008, 2013, 2018, and 2023), indicating a cluster effect of similar LST values. Using the Getis-Ord Gi* method, hot spot, and cold spot analysis identified an increasing trend in high LST cluster points and a decreasing trend in low LST clusters over the study period. The influence of soil texture on LST reveals that soil with higher clay content exhibits higher LST, while sandy soils tend to have lower LST. The findings highlight the importance of sustainable land management practices to mitigate climate change impacts.
Keywords: Climate change, Land Use Land Cover, Land Surface Temperature, Remote sensing, Urban Heat Island effec
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
No full textWe 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
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