1,720,959 research outputs found
Records of the Australian redclaw crayfish Cherax quadricarinatus (von Martens, 1868) on the island of Puerto Rico
No full textThe redclaw crayfish, Cherax quadricarinatus (von Martens, 1868), a tropical freshwater crayfish endemic to Northern Australia and Southern Papua New Guinea, was introduced to the island of Puerto Rico in the late 1990's. Redclaw has established populations within man-made reservoirs and ponds across the island, where impoundments have impeded the migration and recruitment of native decapods, potentially opening niche space for the redclaw. We present a case study focused on documenting the presence/absence, sex ratio, size class, and standing stock biomass of redclaw populations from six reservoirs (Carraizo, Cidra, Carite, Guajataca, El Guineo, Dos Bocas), as well as from various holding ponds of an aquaculture facility (Caribe Fisheries) located near the town of Lajas in the southwestern part of the island where the crayfish are considered pests. Crayfish were detected in 5 out of the 7 sample locations (Carraizo, Cidra, Carite, Guajataca, and Caribe Fisheries). A total of N = 150 crayfish were caught during sampling, with 91% being adults (N = 136) and sex counts resulting in a 0.81 male to female ratio. Standard Carapace Length (SCL) ranged from 16 mm (Guajataca) to 82 mm (Carraizo). No significant difference in SCL was found between adult males (48.32 mm +/- 1.62 SE) and females (48.17 mm +/- 1.47 SE) (F-(1,F-134) = 0.81, P = 0.37), as well as between SCL in M:F ratio among sample sites (F-(4,F-134) = 0.84, P = 0.50). However, a significant difference in total mean SCL among sample sites was found (F-(4,F-134) = 16.96, P < 0.0001). A post-hoc Tukey-Kramer test indicated that individuals in Carraizo, located close to the area of initial redclaw introduction into the headwaters of the Loiza River, had the largest mean SCL (61.38 mm). Mean standing stock biomass per individual ranged from 1.46 g (Guajataca) to 9.71 g (Carraizo). These biomass estimates provide the first insight into the energy supplements that redclaw provides to higher trophic levels (e.g. predatory fish) in these reservoirs. Furthermore, with populations of native decapods having been completely extirpated from most impounded watersheds, introduced redclaw could fill in the empty niche space by processing organic matter and by providing a direct consumption item to recreational fish species. This could reestablish the missing links in the cycling of nutrients and transfer of energy within reservoirs.National Science Foundation (NSF)Published articl
RELATIONSHIP OF CHAIN-FORMING ARAPHID DIATOM COMMUNITIES FOUND IN HYDROLOGICALLY VARIABLE WETLANDS
No full textDiatoms, a common group of algae made of silica, are found to be high quality bioindicators. The former Bo Ginn National Fish Hatchery in Millen, Georgia, United States was used to study the modifications done on spring-fed wetlands. Ponds were modified based on inundation period and featured eight total wetlands, five were temporarily inundated and three were permanently inundated. All samples were collected using a benthic core sampler. The goals of this research were to (1) identify diatoms to the lowest taxonomic level, (2) compare algal metrics between the varying inundations and the top versus bottom of the sediment cores and (3) observe and analyze chain formation of Staurosira construens Ehrenberg. Previous research on this project found that S. construens dominated all samples with over 50% relative abundance. It is a chain-forming diatom and there is importance in observing these chains in order to document reproductive and diminution series traits that might be observable within samples. Current data shows high abundance of chains and the average number of frustules within a chain being four frustules. Chain showed diatom’s ability to survive and reproduce, leading to increased number of chains. There was a higher prevalence of chains within the temporary wetlands; however, there were more total temporary ponds overall. These digested samples were compared to live samples collected from the spring, the wetlands’ water source, and there were higher length of chains. There is theory that length of chain varied on both the practice of digestion and mounting of slides or the live collection of samples from the spring. This research contributes to the understanding of the effects of anthropogenic use on the ecosystem even years after the hatchery closed along with the relationship between chain length and size within sediment cores of top and bottom as well as inundation
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
Variations 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
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