1,720,967 research outputs found
Ancestral genetic diversity associated with the rapid spread of stress-tolerant coral symbionts in response to Holocene climate change
No full textCoral communities in the Persian/Arabian Gulf (PAG) withstand unusually high salinity levels and regular summer temperature maxima of up to ?35 °C that kill conspecifics elsewhere. Due to the recent formation of the PAG and its subsequent shift to a hot climate, these corals have had only <6,000 y to adapt to these extreme conditions and can therefore inform on how coral reefs may respond to global warming. One key to coral survival in the world’s warmest reefs are symbioses with a newly discovered alga, Symbiodinium thermophilum. Currently, it is unknown whether this symbiont originated elsewhere or emerged from unexpectedly fast evolution catalyzed by the extreme environment. Analyzing genetic diversity of symbiotic algae across >5,000 km of the PAG, the Gulf of Oman, and the Red Sea coastline, we show that S. thermophilum is a member of a highly diverse, ancient group of symbionts cryptically distributed outside the PAG. We argue that the adjustment to temperature extremes by PAG corals was facilitated by the positive selection of preadapted symbionts. Our findings suggest that maintaining the largest possible pool of potentially stress-tolerant genotypes by protecting existing biodiversity is crucial to promote rapid adaptation to present-day climate change, not only for coral reefs, but for ecosystems in general
Comparative Profiling of coral symbiont communities from the Caribbean, Indo-Pacific, and Arabian Seas
No full textCoral reef ecosystems are in rapid decline due to global and local
anthropogenic factors. Being among the most diverse ecosystems on Earth, a loss will
decrease species diversity, and remove food source for people along the coast.
The coral together with its symbionts (i.e. Symbiodinium, bacteria, and other
microorganisms) is called the ‘coral holobiont’. The coral host offers its associated
symbionts suitable habitats and nutrients, while Symbiodinium and coral-associated
bacteria provide the host with photosynthates and vital nutrients. Association of corals
with certain types of Symbiodinium and bacteria confer coral stress tolerance, and lack
or loss of these symbionts coincides with diseased or bleached corals. However, a
detailed understanding of the coral holobiont diversity and structure in regard to
diseases and health states or across global scales is missing.
This dissertation addressed coral-associated symbiont diversity, specifically of
Symbiodinium and bacteria, in various coral species from different geographic
locations and different health states. The main aims were (1) to expand the scope of
existing technologies, (2) to establish a standardized framework to facilitate
comparison of symbiont assemblages over coral species and sites, (3) to assess
Symbiodinium diversity in the Arabian Seas, and (4) to elucidate whether coral health
states have conserved bacterial footprints.
In summary, a next generation sequencing pipeline for Symbiodinium diversity
typing of the ITS2 marker is developed and applied to describe Symbiodinium
diversity in corals around the Arabian Peninsula. The data show that corals in the
Arabian Seas are dominated by a single Symbiodinium type, but harbor a rich variety
of types in low abundant. Further, association with different Symbiodinium types is
structured according to geographic locations. In addition, the application of 16S rRNA gene microarrays to investigate how differences in microbiome structure relate
to differences in health and disease demonstrate that coral species share common
microbial footprints in phenotypically similar diseases that are conserved between
regional seas. Moreover, corals harbor bacteria that are species-specific and distinct
from the diseased microbial footprints. The existence of conserved coral disease
microbiomes allows for cataloging diseases based on bacterial assemblage over coral
species boundaries and will greatly facilitate future comparative analyses
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
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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