1,721,360 research outputs found
Vulnerability of algae and seagrasses to climate change
No full textBiodiversity is undergoing rapid and worrying changes, partially driven by anthropogenic activities. Human impacts and climate change (e.g. increasing temperature and ocean acidification) represent the most serious threats to biodiversity and ecosystem functioning.
Aim of this study was to assess, analysing the scientific literature and published data, how climate change can affect algae and seagrasses, evaluating their vulnerability and the possibility to use these organisms as indicators. Algae and seagrasses have a central role for several important ecological processes in aquatic ecosystems, and their loss can lead repercussions for the ecological function. Climate stressors affected acquatic vegetation, acting both in isolation and in combination with local perturbations (e.g. nutrient enrichment), reducing the resilience of marine communities. Ocean acidification has negative effects on calcification rates of calcareous algae; sea warming affects both the stability of Posidonia oceanica meadows and their potential recolonization. Considering future climate scenario researchers and policy makers have to plan measures to preserve biodiversity and the status of health of the marine ecosystems
Differences in the growth cycle of Ruppia cirrhosa (Petagna) Grande in a Mediterranean shallow system
Full text linkRuppia cirrhosa growth cycle was analysed in a southern Mediterranean shallow system throughout 1 year. We examined the temporal variation in R. cirrhosa cover percentage, shoot density, biomass, leaf length, no. flowers m-2 and no. fruits m-2 in
two groups of pond characterized by differences in some environmental parameters. Ponds were comparable for salinity and temperature but they differed for other environmental parameters such as water depth, level of suspended organic matter and
chlorophyll a (CHL a). Biological parameter values were higher in B ponds, characterized by lower values of water depth, suspended organic matter and CHL a. A seasonal trend for all considered biological parameters in both typologies of ponds with maximum values in summer was also observed. Moreover, differences were observed between the two groups of ponds in relation to the reproductive strategy adopted by the plant, with populations subjected to a higher organic input and a lower water depth displaying an annual cycle. Results showed how R. cirrhosa is able to resist and to adapt to variations in
environmental conditions because of the plasticity and flexibility in the growth cycle and in the reproductive effort
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
Definizione e sviluppo di modelli di calcolo da utilizzare per l'analisi ed il dimensionamento di strumenti radar ad apertura sintetica (SAR) frammentati, basati su configurazioni di tipo Bistatico (un trasmettitore ed un ricevitore piazzati su satelliti distinti) o Multistatico (un trasmettitore e ricevitori multipli piazzati su satelliti distinti
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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
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