1,720,955 research outputs found
On the biology and epidemiology of the feral pigeon (Columba livia)
Get PDFFeral pigeons (Columba livia, Gmelin 1789) are among the most abundant vertebrates in the urban environment of almost every city in the world. Close contacts to humans bear the risk of transmission of zoonotic pathogens and parasites. The most important of these zoopathogens is the bacterium Chlamydia psittaci, the agent of avian chlamydiosis and human psittacosis/ornithosis. Many human infections reported in the medical literature were attributed to brief and transient contacts to feral pigeons in the urban environment. The aim of the present thesis is to investigate the prevalence of C. psittaci in the feral pigeon population of Basel, to identify possible routes of transmission in the city and to propose measures for the prevention of zoonotic C. psittaci transmissions.
In a preliminary study, 47 faecal samples were collected from nest boxes in a feral pigeon loft in Basel, Switzerland. In addition 34 samples were collected from the feather dust film on the water surface of public fountains, where feral pigeons regularly bathe. All 81 samples were tested for the presence of chlamydial antigen by use of an antigen-ELISA assay. Initially the ELISA assay yielded a high proportion of positive results: 8 out of 47 (23.5 %) faecal samples and 26 out of 34 (76.5 %) of the water film samples were tested positive. However, a subsequent blocking test revealed only one true positive faecal sample, which could be confirmed by microarray. This ELISA assay was not used for further studies.
In the main study, the prevalence of C. psittaci shedding in free ranging feral pigeons living in a pigeon loft in Basel was investigated. A total of 202 individual birds were tested on four different time points between 2007 and 2009 by analysis of pharyngeal and cloacal swabs. Some of the birds could be tested repeatedly. All samples were analyzed by use of a species-specific nested PCR assay targeting the ompA gene of C. psittaci. The tested feral pigeons were shedding C. psittaci by respiratory secretions, since 9 out of 447 (2.0 %) of the pharyngeal swabs were tested positive. Furthermore, 11 out of 348 (3.2 %) of the cloacal swabs were tested positive, indicating that these birds are shedding C. psittaci in their faecal droppings. In total, C. psittaci was documented in 17 of 202 individual birds (8.4 %). The majority of the positive birds were shedding the pathogen intermittently. At present, this is the first study to test individual free-living feral pigeons repeatedly and therefore the first to prove intermittent shedding of C. psittaci in these birds. Genotyping of the positive samples by real-time PCR revealed C. psittaci genotype B in 7 of the birds, as well as a mixed infection with the genotypes A, B and E/B in one bird. A mixed infection with three different chlamydial genotypes could be documented for the first time. Seven of the birds that tested positive immigrated into the pigeon loft as adults, including the bird with the mixed infection. Thus, it could be proven how the interconnectedness of feral pigeon subpopulations favours the spread of pathogens. Additionally, 620 faecal samples from public sites in the city were analyzed. However, C. psittaci could not be detected in these faecal samples from the urban environment.
Feral pigeons on building facades, on balconies and window ledges, or in open attics pose a health risk. Avoiding attractive building structures already during building design is the best and most cost-effective way to prevent problems with feral pigeons in the future. We identified the structural parameters required to proof a building against feral pigeons. It could be demonstrated that feral pigeons are not able to pass through an outlet width of 4 cm, the respective outlet height is 5 cm, and a pigeon-safe square opening size is not exceeding 6 × 6 cm. A feral pigeon is not able to sit on a ledge if it’s width is 4 cm or smaller. The pigeon-safe angle of inclination for smooth construction materials (tinplate, glass, plastics) is 25°, for medium rough materials (wood, plane concrete) 35°, and for rough materials (sandstone, rough concrete) at least 50°. With these essential data, required to proof a building against feral pigeons, we contribute to the prevention of disease transmissions and parasite infestations due to these birds.
The low proportion of our feral pigeons in Basel, which are shedding C. psittaci, could be documented. However, C. psittaci could not be detected in faecal samples from public sites in the urban environment. The regular cleaning of streets and squares in Basel additionally contributes to public health, since potentially infectious feral pigeon faeces are removed quickly. Considering the numerous opportunities of close contacts to feral pigeons in the urban environment, a transmission of the pathogen from feral pigeons to humans can never be ruled out. Therefore, feral pigeons present a significant potential health risk
Protecting buildings against feral pigeons
Get PDFFeral pigeons (Columba livia, Gmelin 1789) cause different problems for building owners when using structures for daytime perching, sleeping, and breeding. Problems include fouling of building facades and pavements, transmission of allergens and pathogenic microorganisms, and infestations with ectoparasites emanating from breeding sites. Owners are primarily interested in keeping away unwanted pigeons from their property. Pest control companies offer different deterrent systems, of widely varying efficacy, for proofing buildings against feral pigeons. A better solution is avoiding attractive structures during building design or subsequent alterations of existing structures used by feral pigeons. With our study, we elaborate the relevant structural data to help to maintain a building free of pigeons. We performed experiments with free ranging feral pigeons in a feral pigeon loft in the City of Basel, Switzerland. The maximum outlet width a pigeon is not able to pass through is 4cm; the respective outlet height is 5cm and a pigeon-safe square opening is not larger than 6 × 6cm. The maximum ledge width a pigeon is not able to sit on is 4cm. The pigeon-safe angle of inclination for smooth construction materials (tinplate, glass, plastics) is 25°, for medium rough materials (wood, plane concrete) 35°, and for rough materials (sandstone, rough concrete) at least 50°. Additionally, we studied the behavioral strategies used by feral pigeons to surmount our experimental constructional restrictions, ledge width, and ledge inclinations. Our data provide the essential data to prevent feral pigeons from using building structure
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
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