1,720,981 research outputs found
Recommended from our members
Environmental influences on the host finding behavior of juvenile black-legged ticks
Full text linkVector feeding behavior can have a profound influence on the transmission of vector-borne diseases. In the case of black-legged ticks, Ixodes scapularis, which vectors the agents of Lyme disease, babesiosis, and other pathogens, the timing and propensity of questing can determine which hosts are fed upon as well as the risk of contact with humans. Yet we know little about the controls and constraints on tick host finding behavior under natural conditions. Ticks must balance the demand for an encounter with a blood meal host with the risk of desiccation while on a fixed energy budget. Prior research has suggested that questing activity varies with conditions (e.g., temperature, relative humidity), light-dark cycles, and energy reserves, but the findings have been idiosyncratic and the dominant factor(s) in nature remains unknown. We measured questing activity of nymphs and larvae during the day and night in microcosm enclosures spanning a range of suitable tick habitats within a site in the Northeast. Nymph activity increased slightly during dawn and dust, opposite of larvae, and declined slightly with air temperature and rain. Although, the patterns of activity were not consistent across all of the sites, rather it appears that a percentage of ticks may have quested continuously regardless of conditions, indicating that neither climatic conditions nor light-dark cycles have an appreciable influence on tick questing activity
Recommended from our members
The effects of aquatic community members on the persistence of an amphibian Ranavirus
Full text linkCommunity interactions can strongly influence disease dynamics in myriad ways, particularly for pathogens that persist while unprotected by their host for a portion of their life cycles. Ranaviruses--often-lethal viruses of cold-blooded vertebrate hosts transmitted by direct contact, and via water, sediment, and fomites--offer an interesting system for understanding these community influences. It is unclear how long ranaviruses remain infectious in the aquatic environment. Previous research suggests persistence times of days to years, depending on the specific conditions used in the study. Viral interactions with the biotic community may explain some of these discrepancies as studies in which virions were held in sterile conditions had much longer persistence times than those where virions were unprotected. To address the role of the biotic community and particulate matter on ranavirus persistence we experimentally inoculated filter-sterilized, UV-treated, and unmanipulated pond water with an FV3-like Ranavirus and took samples over 78 days, quantifying viral titers with real-time quantitative PCR and plaque assays. Viral counts dropped quickly in all pond water treatments; by an average of an order of magnitude in less than one day in unmanipulated pond water and eight days in filter-sterilized pond water. In a second experiment we measured viral titers over 24 hours in virus-spiked spring water with 0, 1, 2, 5, or 10 Daphnia pulex at two different food concentrations. Presence of D. pulex resulted in a reductions of active ranavirus concentrations by approximately an order of magnitude in 24 hours, although concentrations of viral DNA were largely unchanged. Daphnia themselves did not accumulate the virus. We conclude from these experiments that both microbial and zooplanktonic communities can play an important role in ranavirus epidemiology, rapidly inactivating aquatic concentrations of these viruses and thereby minimizing environmental transmission. We suspect that interactions with the biotic community will be important for most pathogens with environmental resting or transmission stages
Recommended from our members
Are scavengers good for your health? The effect of scavengers on disease transmission
Full text linkScavenging of infectious carcasses by heterospecific organisms may play an important, but insufficiently understood, role in disease transmission. Infected carcasses can be a major source of new infections in wildlife. In cases where diseases can cause an accumulation of infectious carcasses, a robust scavenging community could reduce the ability of the carcasses to cause new infections by quickly removing infected tissue. Alternatively, scavengers could exacerbate the spread of diseases by exposing susceptible organisms to infectious tissue. Identifying the role of scavengers in disease transmission is a crucial part of understanding the broader community interactions in disease systems. We carried out a study to determine the efficiency of scavenging invertebrates to remove carcass material from larval Long-toed Salamanders (Ambystoma macrodactylum), and investigated the effect of scavenging by an efficient larval invertebrate (Family: Dytiscidae) on the transmission of Frog Virus 3 (Genus: Ranavirus, Family: Iridoviridae) from carcasses. The feasibility of scavenging in the wild having an effect on carcass persistence, and therefore transmission, was estimated using the maximum scavenging efficiency of Dytiscidae larva from their functional response to carcass density, and using field survey counts to estimate relative densities of Dytiscidae larvae and A. macrodactylum in two ponds. We found that at least two families of invertebrates will scavenge readily on larval A. macrodactylum, (Dytiscidae and Aeshnidae). Using Dytiscidae larvae, we showed that scavenging on the carcass caused a significant decrease (44.5%) in the proportion of new infections caused by contact with a carcass, and that efficient scavenging has a similar effect on new infections as a physical barrier preventing naïve individuals from contacting a carcass. There was no evidence that scavenging increases infections indirectly through the water. An estimation of the potential effect of scavenging in two ponds showed that the maximum ability of the Dytiscidae to remove salamander carcasses varies through time and across ponds, but in at least some ponds, the scavengers would not be clearly overwhelmed by carcass density. Our results suggest that scavenging negatively influences disease transmission from carcasses, and this could potentially scale up to the population-level
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
- …
