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Response to simulated El Niño stress by Macrocystis pyrifera
Get PDFCompelling evidence on environmental and species distribution changes due to global climate change have greatly increased over the last decades and extreme events like marine heatwaves (MHWs) (concurrent high temperature and low nutrient) are increasing in frequency, duration and intensity. The giant kelp, Macrocystis pyrifera (L.) C.A. Agardh forms dense marine forests serving as a foundation species in ecosystems that are of great ecological and economic importance. Thus, the objective of this study was to test for evidence of local adaptation to conditions representative of MHWs stress in the field on a regional level, encompassing areas with different oceanographic regimes and genetic groups. Adult blades from two depths and four regions of the Northeast Pacific were exposed to simulated nutrient and thermal stress conditions. The results clearly showed that M. pyrifera populations at the southernmost limit displayed greater thermal tolerance in their photosynthetic physiology. Compared to the other regions, surface blades from the South suffered reduced impact on the photosynthetic apparatus, with Fv/Fm values at 24ºC 15.5% higher than the regional mean. Thermally-sensitive parameters governed mainly by enzymatic processes (rETRmax and Ek) were unaffected over the 15 - 24ºC range in the southernmost region, suggesting adaptation to local environmental conditions. Amongst the bottom blades collected at depth, photosynthetic responses to stress were rather similar among different regions. The F1 juvenile generation grown in vitro from parental source material did not exhibit a significant reductions in Fv/Fm under the moderate stress temperature used (21ºC), but rETRmax and Ek remained significantly higher in the Southern regions. Consistently poor photosynthetic responses to thermal stress were observed in the North-Center region (Santa Barbara) in all experiments, suggesting genetically-based fitness reduction. Our results also highlighted the need for further research on the synergistic effects of low nutrients availability and high thermal stress considering different life stages of M. pyrifera.Evidências científicas de alterações no ambiente e distribuição de espécies devido a mudanças climáticas de caracter global, tem aumentado largamente nas últimas décadas. Eventos como as ondas de calor marinhas, têm aumentado a sua frequência (em cerca de 38%), duração e intensidade, ameaçando vários ecossistemas marinhos como recifes de coral, pradarias marinhas e florestas marinhas, assim com espécies de grande relevância económica. Espécies como as lagostas e as amêijoas foram afetadas através da redução do habitat e por stress térmico, o que resultou num aumento da mortalidade, na redução do tamanho dos indivíduos e da sua taxa de reprodução.
O Kelp gigante, Macrocystis pyrifera (L.) C.A. Agardh é o kelp com maior distribuição nos oceanos que forma extensas florestas marinhas, com uma canópia densa na superfície resultando numa grande produção primária a qual alimenta diretamente organismos herbívoros mas maioritariamente detritívoros. Devido a sua densidade e dimensão, as florestas de M. pyrifera são capazes de alterar as condições ambientas locais, nomeadamente reduzindo correntes e luz, criando um habitat heterogéneo, abrigando um grande número de espécies. Assim, funciona como uma espécie fundadora do ecossistema apresentando grande relevância ecológica e económica.
A fotossíntese é influenciada pela temperatura que regula as taxas de reações e movimentos de solutos dentro das células das algas tendo sido utilizada com sucesso noutros estudos, para quantificar o efeito de aumento de temperatura em kelps. Um dos métodos mais comuns para medir respostas fotossintéticas em eco-fisiologia é o fluorómetro (PAM), pois é capaz de determinar eficientemente as taxas fotossintéticas em laboratório e também no campo.
A utilização de técnicas de deteção remota como boias e satélites em estudos oceanográficos, permite obter dados a uma grande escala e com grande regularidade possibilitando a análise de padrões e fatores relevantes como por exemplo oscilações da temperatura da superfície do mar (SST) ou movimentos da camada de gelo polar. Esta técnica pode também ser utilizada para gravar eventos a uma escala temporal mais curta, como blooms de fitoplâncton e processos de afloramento costeiro. Dado que a macroalga M. pyrifera forma uma canópia densa à superfície da água do mar, a utilização de dados de satélite (capazes de detetar a fluorescência da Clorofila a). Esta ferramenta tornou-se essencial na análise da distribuição, padrões sazonais de crescimento e correlação das florestas de kelp gigante com fenómenos ambientais como furacões ou eventos como o El Niño. A análise de climatologias, resumos de uma ou mais variáveis (SST ou Clorofila a) em escalas temporais grandes, utiliza modelos de fluxos atmosféricos e oceanográficos com enormes bases de dados e capacidade de processamento dos mesmos (como por exemplo o sistema de reanalise de dados oceanográficos ORAS4). Estes aumentam a quantidade e qualidade dos dados utilizáveis para estudar os fatores ambientais que afetam a espécie em estudo e permitem a criação de cenários de hipotéticos de alterações na distribuição destas espécies.
O objetivo deste estudo foi procurar evidências de adaptação local a condições representativas de stress relacionado com ondas de calor marinhas (temperaturas altas e baixa concentração de nutrientes) a um nível regional numa área que engloba regimes oceanografias diferentes, assim como diferentes grupos genéticos.
Em 2015, lâminas de M. pyrifera adultas amostradas a duas profundidades e provenientes de quatro regiões do Pacifico Noroeste foram expostas a um gradiente de água do mar a 3 temperaturas (15, 20 e 24ºC) e nutrientes (meio não enriquecido e enriquecido com Provasoli (PES)) replicados (x3), simulando condições similares fenómenos com o El Niño. Tanques de 30L contendo água do mar filtrada foram equipados com termostatos para regular a temperatura, bombas de circulação de água e aparelhos de registo de temperatura para registar o seu perfil. As condições de cultura foram: salinidade a 35ppm, ciclos de 14:10 luz:escuro a 80 μE· m-2·s-1 e os tratamentos com adição de nutrientes foram enriquecidos com 20 mL·L-1 PES.
Os resultados das experiências revelaram, com grande expressividade, que as populações de kelp gigante do limite sul da distribuição geográfica no hemisfério norte, expressavam na sua resposta fotossintética uma maior tolerância ao stress. Comparada com as outras regiões, as lâminas da superfície da região Sul, demonstraram uma menor perturbação no aparelho fotossintético com os valores do parâmetro Fv/Fm 15.5% superiores à média regional, nos tratamentos a 24ºC. Também na região Sul, os parâmetros relacionados com os processos fotossintéticos de enzimas termo sensíveis (rETRmax e Ek) foram mais elevados a 24ºC comparativamente com os tratamentos a 20ºC, o que não sucedeu nas outras regiões. Nas lâminas amostradas junto ao fundo, as repostas fotossintéticas ao stress apresentaram maior semelhança entre regiões. Esporófitos juvenis crescidos em laboratório, a partir do tecido reprodutivo recolhido nas mesmas populações amostradas para as lâminas adultas, não exibiram uma redução significativa do parâmetro Fv/Fm, provavelmente devido à temperatura máxima utilizada (21ºC) a qual não foi suficientemente alta para causar stress térmico. No entanto, os parâmetros rETRmax e Ek foram significativamente mais altos na região Sul. A região Norte-Centro (Santa Barbara, Califórnia) revelou os níveis mais baixos de resposta fotossintética ao stress em todas as experiências, incluindo nos esporófitos F1. Este facto aponta para uma possível redução de fitness devido a fatores genéticos. Os nossos resultados realçam também a necessidade de futuras investigações nos efeitos sinérgicos de baixa disponibilidade de nutrientes, associada a elevadas temperaturas considerando diferentes etapas no ciclo de vida de M. pyrifera
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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