2,295,228 research outputs found
Bad Hersfeld. Blick auf Sanatorium St. Wigbertshöhe u. die Stadt
No full textBAD HERSFELD. BLICK AUF SANATORIUM ST. WIGBERTSHÖHE U. DIE STADT
Bad Hersfeld. Blick auf Sanatorium St. Wigbertshöhe u. die Stadt ( -
Comment on “Rapid Advance of Spring Arrival Dates in Long-Distance Migratory Birds”
No full textJonzén et al. (Reports, 30 June 2006, p. 1959) proposed that the rapid advance of spring migration dates of long-distance migrants throughout Europe reflects an evolutionary response to climate change. However, most migrants should not advance their migration time because the phenology of their breeding grounds has not changed. It is more likely that migration speed has changed in response to improved environmental circumstances.
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No experimental evidence for local competition in the nestling phase as a driving force for density-dependent avian clutch size
No full text1. In birds, local competition for food between pairs during the nestling phase may affect nestling growth and survival. A decrease in clutch size with an increase in breeding density could be an adaptive response to this competition. To investigate whether breeding density causally affected the clutch size of great tits (Parus major), we manipulated breeding density in three out of eight study plots by increasing nest-box densities. We expected clutch size in these plots to be reduced compared to that in control plots.
2. We analysed both the effects of variation in annual mean density (between-year comparisons) and experimental density (within-year comparison between plots) on clutch size variation, the occurrence of second broods and nestling growth. We examined within-female variation in clutch size to determine whether individual responses explain the variation over years.
3. Over the 11 years, population breeding density increased (from 0·33 to 0·50 pairs ha–1) while clutch size and the occurrence of second broods decreased (respectively from 10·0 to 8·5 eggs and from 0·39 to 0·05), consistent with a negative density-dependent effect for the whole population. Nestling growth showed a declining but nonsignificant trend over years.
4. The decline in population clutch size over years was primarily explained by changes occurring within individuals rather than selective disappearance of individuals laying large clutches.
5. Within years, breeding density differed significantly between manipulated plots (0·16 pairs ha–1 vs. 0·77 pairs ha–1) but clutch size, occurrence of second broods and nestling growth were not affected by the experimental treatment, resulting in a discrepancy between the effects of experimental and annual variation in density on reproduction.
6. We discuss two hypotheses that could explain this discrepancy: (i) the decline in breeding performance over time was not due to density, but resulted from other, unknown factors. (ii) Density did cause the decline in breeding performance, but this was not due to local competition in the nestling phase. Instead, we suggest that competition acting in a different phase (e.g. before egg laying or after fledgling) was responsible for the density effect on clutch size among years.
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Produção sustentável de pimenta-do-reino em tutor vivo de gliricídia no estado do Pará: bases econômicas e de qualidade.
No full textA pimenta-do-reino é a mais importante especiaria comercializada no mundo e como se trata de uma commodity, a tendência do mercado é a comercialização de produtos originados de sistemas de produção sustentáveis, com contribuição relevante do uso de tutor vivo de Gliricidia sepium L. em substituição ao estacão (tutor morto), na produção de pimenta-do-reino. Entretanto, a adoção desta tecnologia é limitada em decorrência da escassez de informações (irrigação, espaçamento, nutrição, manejo entre outros fatores de produção) sobre as interações entre o comportamento das cultivares de pimenteira-do-reino a esse tipo de tutor, para consolidação de um sistema de produção sustentável. Portanto, o estudo consiste em identificar as condições adequadas de irrigação e adubação em que a cultura da pimenteira-do-reino cultivada em tutor vivo tenha as exigências hídricas e nutricionais atendidas para a produção com qualidade e viabilidade econômica no Nordeste Paraense. Com o uso da irrigação, assinalou-se uma menor demanda hídrica com o uso de Gliricidia sepium no sistema de irrigação com duas linhas, e menor custo. A implantação do tutor vivo de gliricídia, com custos menores, comparados ao tutor morto, assegura recursos financeiros para a adoção de irrigação. No estabelecimento da cultura, referenda-se os níveis de adubação mínimos (60g de uréia, 40g de P2O5 e 70g de K2O por planta), que equivalem à recomendação de adubação na literatura. A qualidade da pimenta-do-reino produzida com o uso da gliricídia obteve incremento com relação aos índices de densidade, extrato etéreo e piperina. Os resultados desse estudo indicam evidentes contribuições do uso de tutor vivo de gliricídia na circularidade econômica da cadeia da pimenta-do-reino. Neste cenário, recomenda-se o estabelecimento de políticas públicas, voltadas ao desenvolvimento e validação de inovações tecnológicas que assegurem o incremento de produtividade, qualidade do produto e redução de riscos na cadeia produtiva da pimenta-do-reinoTese (Doutorado em Agronomia) - Universidade Federal Rural da Amazônia, Belém, PA. Orientador: Joaquim Alves de Lima Junior; Coorientador: Oriel Filgueira de Lemos, Embrapa Amazônia Oriental
Interference between the sexes in foraging Bar-tailed Godwits Limosa lapponica
No full textSexual size dimorphism is common in many bird species. A consequence of sexual size dimorphism is that the larger sex has larger food requirements, and also that it might be dominant over the smaller sex. We studied the foraging behaviour of Bar-tailed Godwits Limosa lapponica, a highly sexually size dimorphic species. Our interest is in intersexual competition and its consequences for habitat use. Male and female Bar-tailed Godwits were distributed non-randomly over the intertidal foraging areas. Males were concentrated on exposed mud flats, while females occurred more along the waterline. Also within these habitat types, the sexes associated with same-sex individuals. Males were more susceptible to intraspecific kleptoparasitism than females, which we suggest is the cause of the unequal spatial distribution of male and female Bar-tailed Godwits. Females seem to monopolise the better quality foraging areas, leaving males the rest.
Fitness consequences of avian personalities in a fluctuating environment
No full text1. Intraspecific variation in reproductive decisions is generally considered as a reaction to environmental circumstances. We show that variation in reproductive parameters also covaries with intraspecific variation in personality. 2. During 4 years, we studied reproductive parameters in a natural population of great tits in association with a personality trait: exploratory behaviour as measured in a novel environment. 3. Nest success, fledgling size and condition were all correlated with this personality trait. Slow-exploring females had a higher nest success and largest fledglings. Fledgling condition was affected by the interaction between male and female exploratory behaviour, with assortative pairs at both ends of the behavioural spectrum producing fledglings in best condition. Fast-exploring males bred in nestboxes that produced heavy fledglings in other years. 4. We hypothesize that fast-exploring individuals are better able in defending or obtaining a high quality territory, while slow-exploring individuals are either better parents or have better chicks which may, in part, explain the patterns in reproductive success. We discuss how these patterns in reproduction can explain earlier reported relationships between offspring recruitment and avian personality and may result in the maintenance of intraspecific genetic variation in personality. [KEYWORDS: boldness ; exploration ; fitness ; genetic variation ; personality ; reproduction]
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