1,721,024 research outputs found
Techniques for the establishment of corn - Brachiaria spp. intercrops
No full textForam conduzidos seis ensaios em campo objetivando avaliar os efeitos do manejo do consórcio entre milho e Brachiaria spp. na ocorrência de plantas daninhas, na produção de milho e de forragem e no desenvolvimento do feijoeiro cultivado sobre a palhada das espécies consorciadas. Em consórcio, a maioria das espécies daninhas anuais de propagação seminífera foi controlada por herbicidas do grupo químico das sulfoniluréias em mistura com atrazine, mesmo em subdoses, e as espécies perenes de propagação vegetativa não foram influenciadas pelo manejo químico. O milho e o manejo do consórcio com herbicidas afetaram as características morfológicas e anatômicas da parte aérea da forrageira consorciada, se comparada ao seu crescimento livre de competição. A Brachiaria spp. teve seu rendimento forrageiro reduzido em convivência com o milho, em relação ao cultivo solteiro, sendo maior essa redução quando o consórcio foi manejado com as sulfoniluréias e nas maiores doses. Contrariamente, observou-se maior rendimento de grãos de milho onde se manejou o consórcio com as sulfoniluréias em mistura com atrazine, obtendo-se nessa condição rendimento semelhante ao do monocultivo capinado. Entre sistemas de semeadura da forrageira consorciada com o milho, o arranjo de semeadura de duas linhas na entrelinha da cultura mostrou-se mais eficiente, em decorrência do maior rendimento forrageiro e do acúmulo de nutrientes na forragem. Após a colheita mecânica do milho, a forrageira apresentou menor desenvolvimento vegetativo onde o consórcio foi manejado com as sulfoniluréias, em relação ao manejo com o herbicida atrazine. A melhor condição de cultivo do feijão foi observada quando a cultura foi estabelecida na palha proveniente do consórcio do milho com B. brizantha.Six field trials were set up aiming at an evaluation of a maize - Brachiaria spp. intercrop management in its effects on the weed populations, maize and forage yield, and on the development of common bean cultivated on straw of the intercropped species. In the intercrop, most of the annual weeds with seminiferous propagation were controlled by an herbicide of the chemical group of the sulfonylureas in mixture with atrazine by early post-initial applications, even in subdoses. The perennial species with vegetative propagation were not influenced by the chemical management. Maize and herbicide management of the intercrop affected the morphological and anatomical traits of the shoots of the intercropped forage, compared to weeded sole crop. Brachiaria spp. presented a reduced forage yield in coexistence with maize, in relation to the sole crop. This reduction increased when the intercrop was treated with sulfonylurea, and under higher doses. On the other hand, a higher grain yield was observed in maize where the intercrop was managed with sulfonylurea together with atrazine. Under this condition, the grain yield was similar to that of weeded sole crop. Among the forage sowing intercrop methods, the most efficient system for a greater forage yield and nutrient accumulation in the forage was sowing in two rows in-between the maize. After the mechanical maize harvest, Brachiaria spp. presented a lower vegetative development where the intercrop had been treated with sulfonylurea, in relation to the management with atrazine. Best results for common bean were observed when the crop was established on straw of the maize - B. brizantha intercrop.Conselho Nacional de Desenvolvimento Científico e Tecnológic
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
Weed population dynamics in conventional and no-tillage of the corn crop
No full textCom o objetivo de avaliar os efeitos de sistemas de manejo do solo sobre a dinâmica populacional de plantas daninhas, especialmente a tiririca (Cyperus rotundus L.), e sobre a produção de milho para grão e silagem, foi instalado um experimento de campo, em um Podzólico Vermelho-Amarelo Câmbico, fase terraço, no município de Viçosa-MG. Na área experimental, antes da instalação do experimento predominava infestação alta (720 ± 130 plantas. m-2) e homogênea de tiririca. Os tratamentos foram constituídos de dois sistemas de manejo do solo (plantios convencional e direto), cultivados com milho para grão e silagem, em talhões com quatro repetições. No plantio convencional, antes da semeadura da cultura, o solo foi lavrado e gradeado, e, no plantio direto, foi realizada a dessecação das plantas daninhas com glyphosate + 2,4-D. As avaliações de plantas daninhas ocorreram antes e após a aplicação de atrazine e nicosulfuron em pós-emergência da cultura, respectivamente aos 20 e 55 dias após a emergência. A dinâmica populacional de plantas daninhas foi avaliada por meio do uso de características fitossociológicas baseadas na densidade, biomassa e freqüência das espécies amostradas. Os resultados demonstraram que aos 20 dias após a emergência da cultura, no plantio direto, houve maior densidade e importância relativa de espécies dicotiledôneas, principalmente Amaranthus deflexus, enquanto no plantio convencional prevaleceu maior densidade, dominância e importância relativa para tiririca, que suplantou a participação das demais espécies neste sistema. Após a aplicação dos herbicidas, a tiririca foi a espécie mais importante em todos os sistemas estudados, em relação às demais, com menor nível de infestação no plantio direto, no caso de milho para grão e silagem, quando comparado com o plantio convencional. Em ambas as finalidades de uso do milho (grão e silagem) houve redução do banco de tubérculos no plantio direto, predominando tubérculos dormentes, em relação ao plantio convencional. A interferência da tiririca reduziu o ganho de biomassas fresca e seca na cultura do milho, proporcionando melhores resultados para o plantio direto proveniente de milho para grão. Quanto à produção de grãos, não foram observadas diferenças significativas entre os sistemas de manejo do solo.The objective of this study was to evaluate the effect of soil management systems on weed population dynamics, specially the purple nutsedge (Cyperus rotundus. L), and on corn production for grain and silage. A field experiment was installed in a Cambic Yellow Red Podzolic soil, terrace phase, in Viçosa-MG. A high (720 ± 130 plants. m-2) and homogeneous nutsedge infestation prevailed in the experimental area, before the installation of the experiment. The treatments consisted of two soil management systems (conventional and no-tillage), cultivated with corn for grain and silage in blocks with four replications. Under conventional tillage, the soil was moldboard plowed before planting, and under no-tillage, weed desiccation was carried out with glyphosate and 2,4-D. The weed evaluations occurred before and after atrazine and nicosulfuron application in post emergence of the crop, at 20 and 55 days, respectively. Weed population dynamics was evaluated through of phytosociology characteristics based on density, biomass and frequency of the sampling species. The results showed at the 20 days after emergence crop, under no-tillage, there was a greater density and relative importance of broadleaf species, mainly Amaranthus deflexus, while under conventional tillage, a greater density, dominance and relative importance for nutsedge prevailed, that supplanted the participation of the other species in this system. The nutsedge was the most important species in all the studied systems after herbicide application, with smaller infestation level under no-tillage, in the corn for grain and silage, when compared with conventional tillage. For both corn use purposes (grain or silage), there was a reduction in the tuber bank under no-tillage, with dormancy tubers prevailing in comparison to conventional tillage. Nutsedge interference reduced biomass earnings in corn crop, providing better results no-tillage originated from corn for grain. No significant differences were observed among soil management systems for grain production.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio
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
- …
