1,721,252 research outputs found
Complex role of the exopolysaccharidic matrix in biological soil crusts
No full textIn arid and semiarid environments, soil carbon sequestration (CO2 fixation) by
cyanobacteria and by biological soil crusts (BSC) is considered an eco-friendly and natural
process to increase soil C content and a viable pathway to contrast desertification and to favor
soil rehabilitation. Within this context, inoculation-based techniques with exopolysaccharideproducing cyanobacteria have proved to be a viable and sustainable pathway to increase soil
biomass, soil stabilization, and to increase soil fertility. In this presentation, a particular focus
will be given on the role of the extracellular polysaccharidic matrix (EPM) synthesized by
cyanobacteria in giving the structure to natural or induced BSCs and to enhance their water
trapping and retaining capability. EPM was extracted with methods aimed at separately
removing the tightly bound exopolysaccharidic fraction (TB-EPS) and the loosely bound
exopolysaccharidic fraction (colloidal EPS; C-EPS) from BSCs having different ages. The
fractions were analyzed in terms of monosaccharidic composition, and molecular weight (MW)
distribution. We observed that the relative amounts of uronic acids increase in the EPM with the
age of the crusts, implying advantages for the community-water relations. In addition, we also
Abstracts – Third International Workshop on Biological Soil Crusts
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observed significant differences in MW distribution between the two EPS fractions, being TBEPS mostly composed by one molecular fraction having high MW, while C-EPS showed to be
also composed by low MW fractions. This difference suggests distinct roles of TB-EPS and CEPS fractions within the crust system. Indeed, TB-EPS most likely affects BSC structure and
water-retaining properties, while C-EPS most likely contributes to the intake of C in the soil,
thus favoring the growth of the chemoheterotrophic microbial community. The role of EPM in
water capture from non-rainfall sources, water maintenance at the topsoil, and in maintaining a
high water potential was also shown
Effect of inoculated cyanobacteria on the structure and development of inducedbiological soil crust
No full textCyanobacteria are feasible eco-friendly candidates to trigger soil improvement andenrichment. According to several studies, cyanobacteria could be employed as inoculants in differentcontexts, from agricultural to arid and hyper-arid systems. Successful soil inoculation withcyanobacteria leads to the development of cyanobacterial crusts, which are recognized as the firstlevel of development of biological soil crusts, the latter being a key natural and ecologicallyfundamental component in many stressed ecosystems on Earth. Much of the success as inoculants isowed to the productivity and the characteristics of extracellular polysaccharides (EPSs) which arecomplex heteropolymers, which contribute to soil conglomeration and biolayer stability. In order toinvestigate the role of EPSs in cyanobacterial crust development during the first stages of the process,we employed different strains isolated from natural desert biological soil crusts and inoculated them,alone or combined, on fine sand in a microcosm (indoor) experiment. Besides monitoring the growthparameters and the development of the crusts, we evaluated EPS productivity during developmentand we investigated their composition and molecular weight distribution using ion-exchangechromatography and size-exclusion chromatography. Both loosely-bound (less condensed) andtightly-bound EPS fractions were considered in the investigation. In addition, some soil chemo-physical and hydrology-related soil parameters potentially affected by EPS excretion were monitored,at regular intervals, during crust development. The results obtained showed how the use of theselected strains led to the development of stable cyanobacterial crusts in very short times. This study prominently points out at the paramount role of EPSs in determining the observed variations in someof the parameters observed during the experiment duration
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
The Role of Targeted HIV Screening in the Emergency Department: A Scoping Review
Full text linkBACKGROUND: Human immunodeficiency virus (HIV) infection continues to expand worldwide and a significant proportion of infection is still undiagnosed. Recent studies have addressed the impact and feasibility of 'opt-out' HIV screening in Emergency Departments (EDs) in urban settings at high HIV prevalence, whereas little is known about the yield of implementing 'targeted' HIV testing especially in low-prevalence areas.OBJECTIVE: The present study undertakes a scoping review of research carried out on the implementation of targeted HIV screening in adult EDs to determine the impact, feasibility and acceptability of HIV testing in different HIV prevalence settings.DESIGN: Online databases (EMBASE, MEDLINE) were used to identify papers published between 2000 to 2020. A threeconcept search was employed with HIV (HIV, Human immunodeficiency virus infection, HIV infections), targeted testing (Target, screening or testing) and emergency medicine (Emergency Service, emergency ward, A&E, accident and emergency or Emergency Department) (28th February 2020). Only full-text articles written in English, French, Spanish or Italian and using impact and/or feasibility and/or acceptability of the program as primary or secondary outcomes were analysed.RESULTS: The search returned 416 articles. Of these, 12 met inclusion criteria and were included in the final review. Most of the included studies were carried out in the United States (n=8; 67%) and in areas of high HIV prevalence (n=11; 92%). Three (20%) were randomized control studies. While the rate of newly diagnosed HIV cases varied widely (0.03-2.2%), likely due to methodological heterogeneity between studies, the linkage of new HIV diagnosis was often high (80-100%) and median CD4+ cell count was always greater than 200 cells per microliter. Targeted HIV screening was found to be cost-effective (out of 2 studies) and well accepted by participants (out 2 studies).CONCLUSIONS: Targeted HIV screening at the ED can be impactful, feasible and well accepted, but often requires extra funding and staff. Most previous work has focused on areas of high disease prevalence
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
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