1,721,414 research outputs found
Modelling of marine ecosystems : a viral solution to the DOC enigma
No full textThe role and dynamics of the ocean's pool of dissolved organic carbon (DOC) in both the marine carbon cycle and marine ecosystems is not well known. A large imbalance between net export and measured loss of carbon in the upper 150m of Bermuda remains unexplained. Knowledge of the processes that control the source and rate of production of DOC in the upper ocean, as well as its subsurface remineralisation rate and lifetime are required to explain the ocean's global distribution of nutrients. May viral lysis yield the carbon required to account for the fluxes into the semi-labile DOC pool of biogeochemical cycles? The role of marine viruses in ecosystem dynamics is determined and their impact on overall biological production rates and DOC production is analyzed. Viral induced collapse of plankton blooms is investigated. This is achieved through the development of an epidemics model based on a compartmental ecosystem model of the upper ocean. Inter-compartmental flows and fluxes to the deep ocean are plotted daily. A leapfrog integration method with a timestep of two hours is used. The model is run over the period of ten years for the Bermuda Station "S" area. Two thousand simulations are analyzed. Phytoplankton primary production and bacterial production are diverted by viral lysis into the synthesis of new viruses which are inactivated by natural UV radiation and then decay into DOC slowly. The remaining cell debris of lysed hosts flow directly into the detritus and DOC pools respectively. The effect of differing levels of contact rate, inactivation rate, decay time of inactivated viruses and sinking speed of detritus on overall production rates and biomass are investigated. Results show that marine viruses act as regulators of the size and timing of plankton blooms and are important partners in bacterial trophodynamics. The stability of the ecosystem is extremely sensitive to the contact rate between virus and host cells which provides the underlying mechanism for non linear epidemics. Increased levels of the contact rate determine higher viral infectivity and increase viral lysis which forces phytoplankton and bacterial collapses. The epidemics result in a considerable growth of bacterial production and hence viral lysis which increase with the shortening in decay time and the slowing of the detritus sinking speed. Variations in the level of the inactivation rate are found to have minor effect on the overall annual production rates but have large effect on the maximum daily flow into lysis during blooms. The model results on viral production foster support for the viral source of the high-molecular weight fraction of the semi-labile DOC, identify bacterial viruses as its main contributor and show a much improved fit to the observed data in comparison to previous modelling attempts without epidemics.</p
"ALQUEVA - paisagem como tema" / "ALQUEVA - landscape as a theme"
No full textAlqueva, paisagem como tema
Alqueva deixou de representar apenas uma aldeia esquecida no sul do Alentejo, tornando-se
no novo paradigma de desenvolvimento de toda uma região. A barragem e o grande lago do
Alqueva, como novos agentes de transformação, anunciam renovados futuros produtivos para
a industria agrária, mas lançam, igualmente, a interrogação sobre a real dimensão do impacto
ambiental que esta mudança está e irá produzir. Esta dupla e inevitável leitura a partir de um
território em processo complexo de mutação, vem evidenciar uma crescente atenção sobre
as questões patrimoniais, assim como um novo olhar sobre o que constitui e caracteriza esta
paisagem.
Alqueva passou, portanto a ser um sistema paisagem que importa estudar, não apenas enquanto
fenómeno cultural, produto de uma história e de uma estética, mas também, pela necessidade
de redesenhar o território com todas as suas novas evidências. Alqueva, de uma
aldeia no centro Alentejo, parte de um estrutura de micro aglomerados urbanos em rede, organizados
num vasto território também reserva Dark Sky, a uma nova marca identitária do
Alentejo, a paisagem como um tema.
Esta paisagem também se caracterizou por relações sociais e laborais, produtivas e culturais
como contadas no texto de José Cutileiro, Ricos e Pobres no Alentejo (1971), ou na musica de
José Afonso no documentário de Thomas Harlan Torre Bela (1975) sobre a ocupação de uma
grande herdade invocando as tensões sociopolíticas em redor dos senhores da terra. De certo
modo relembra também outras paisagens como nos mostra o filme Senso (1954) de Luchino
Visconti que inicia com uma cena da Opera Il Trovatore de Giuseppe Verdi que serve de fundo
para o tema do filme que decorre na paisagem agrícola da região do Veneto. Visconti, elege a
maestria do espaço arquitectónico de Andrea Palladio através da Villa Godi como condutor de
relações históricas e culturais, algumas delas com matriz semelhante das que se investigam
neste projecto.
O trabalho desenvolvido com os alunos de Projecto Avançado do Departamento de Arquitectura
da Universidade de Évora, entre 2013 e 2014, procurou, numa primeira leitura, reconhecer,
sistematizar e organizar uma vasta informação, associando aos dados cadastrais uma actualização
da cartografia, diferentes registos e marcas, que constituem um instrumento fundamental
de (des)codificação do território, com dados culturais e vivenciais; numa segunda
leitura, identificar, investigar e seleccionar os objectos arquitectónicos que mais directamente
manifestam marcas do impacto do grande lago e da erosão de um passado agrícola que se
alterou profundamente, como são exemplo os montes alentejanos que, apesar de grande parte
abandonados, ou desactivados da sua função original, representam uma importante matriz
funcional e produtiva.
O acto de percorrer o território, como método de abordagem para uma aproximação física
à intensidade própria dos lugares, é um acto que pretende desactivar o olhar que nada vê,
próprio das lógicas burocráticas-turísticas mais agressivas. A reflexão a partir de uma leitura
sequencial e gradual desde a macro escala à escala do espaço habitado, abriu campo para a
descoberta de programas e temas que apontam um novo sentido e significado de permanência
nesta paisagem.
Posicionar a resposta da arquitectura no ensaio e discussão destas problemáticas assume
uma forma de responsabilidade ética, no sentido de uma revalorização do património e da
paisagem e de uma necessária reposição dos seus valores potenciais e estruturais na nossa
contemporaneidade.
O livro que agora se apresenta, pretende fundamentalmente mostrar uma realidade poética e
arquitectónica de grande consistência, que urge revelar e .estudar, até nos seus paralelismos
com outras culturas do mediterrâneo. A sua divulgação pública, após um primeiro momento de
apresentação com a exposição no Museu da Luz, corresponde ainda a um desejo de inscrição
desta matéria de trabalho numa discussão alargado sobre estes temas.
Manifestamos o nosso agradecimento aos parceiros e apoios, institucionais e editoriais, que
tornaram estimulante a produção deste trabalho num contexto académico e possível a sua
organização e edição
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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