130,759 research outputs found
The influence of density on frequency-dependent food selection: a comparison of four experiments with wild birds
No full textWe compare the results of four experiments, conducted at different times and with different protocols, that explored the relationship between frequency-dependent selection and prey density in wild birds feeding on artificial populations of coloured baits. One (experiment 4) used pastry baits that differed only in the presence or absence of a red stripe, and this experiment provided no evidence for any kind of selective behaviour. The other three experiments used green and brown baits, and they all provided evidence for a trend towards increasing anti-apostatic selection with high densities (>100 baits m–2). However, one of these (experiment 3) provided no evidence for frequency-dependent selection at low densities (0.5–20 baits m–2), while the other two experiments concurred in suggesting a trend towards increasing apostatic selection with low densities (down to 2 baits m–2). Together, these experiments both support and qualify the published findings of experiment 1 that frequency- dependent selection by wild birds on bait populations is modified by density. Experiment 4 indicates that frequency-dependent selection may break down entirely if bait types are too similar, while experiment 3 indicates that some details of this trend with density will depend either on the protocol used or on exogenous changes in the birds’ feeding behaviour
Nanoparticles, Their protein corona and impact on the immune function of human lung cells
No full textParticles with a single dimension smaller than 100 nm are called nanoparticles (NPs). There is a large amount of epidemiology that anthropogenic particles cause increased mortality, increased risk of asthma and increased incidence of lung adenocarcinoma.Inhaled NPs can reach the lung terminus, interacting with a lipid lining at the air-liquid interface (pulmonary surfactant (PSf)) and with an aqueous hydrophase beneath. Studies in serum have shown that upon contact with blood, proteins very rapidly adsorb to the particle surface, thus the particle accrues a biological identity. However, no such interaction studies have been performed in the pulmonary system, where there is a complex interplay of proteins and lipids. The interaction of NPs with PSf is poorly understood. Prior to reaching the lung epithelium, NPs must translocate through this layer.The aims of this thesis are to firstly explore the interactions of NPs with proteins and lipids in the lung and secondly investigate the toxicity and effect on the immunological action of lung cells.NPs were incubated with pulmonary lavage fluid and adsorbed proteins were analysed using state-of-the-art, high resolution, quantitative mass spectrometry. To investigate the interactions of NPs with PSf, particles were incubated with a porcine surfactant. The bound lipids were analysed by qualitative mass spectrometry. The effect of NPs and the NP-protein-corona was investigated in cell lines by a number of techniques.Unique proteins were observed on each particle type, however the main contributors contribution was from a few key proteins. There was no biophysical property of these bound proteins that could predict their affinity to a particle. Surfactant associated protein A, B and D (SP-A, B, D) were observed to be bound to the particle surface. SP-A was bound with high abundance, suggesting it is likely these particles may interfere with PSf in vivo. All particles retained lipids on their surface through binding mediated by electrostatic interactions. Aminated-polystyrene and titanium dioxide NPs were capable of interfering with PSf in vitro. There was little observed effect of the particles to induce inflammation.The key findings suggest that the protein corona does not predict particle toxicity. Any observed effect is due to the core particle chemistry, not an acquired bio-identity. The toxicity of particles observed through epidemiological surveys could be caused from the inhibition of pulmonary surfactant, not from direct toxicity of the particles themselves
Generation of novel trimeric fragments of human SP-A and SP-D after recombinant soluble expression in E. coli
No full textSurfactant treatment for neonatal respiratory distress syndrome has dramatically improved survival of preterm infants. However, this has resulted in a markedly increased incidence of sequelae such as neonatal chronic inflammatory lung disease. The current surfactant preparations in clinical use lack the natural lung defence proteins surfactant proteins (SP)-A and D. These are known to have anti-inflammatory and anti-infective properties essential for maintaining healthy non-inflamed lungs. Supplementation of currently available animal derived surfactant therapeutics with these anti-inflammatory proteins in the first few days of life could prevent the development of inflammatory lung disease in premature babies. However, current systems for production of recombinant versions of SP-A and SP-D require a complex solubilisation and refolding protocol limiting expression at scale for drug development. Using a novel solubility tag, we describe the expression and purification of recombinant fragments of human (rfh) SP-A and SP-D using Escherichia coli without the need for refolding. We obtained a mean (± SD) of 23.3 (± 5.4) mg and 86 mg (± 3.5) per litre yield of rfhSP-A and rfhSP-D, respectively. rfhSP-D was trimeric and 68% bound to a ManNAc-affinity column, giving a final yield of 57.5 mg/litre of highly pure protein, substantially higher than the 3.3 mg/litre obtained through the standard refolding protocol. Further optimisation of this novel lab based method could potentially make rfhSP-A and rfhSP-D production more commercially feasible to enable development of novel therapeutics for the treatment of lung infection and inflammation.</p
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Editorial--Rules Of The Game
No full textFirst issue of journal, published in England by Pergamon Press Ltd. Editor is Bruce D. Whitwell. Editorial (p. 6) by L. D. Miles emphasizes role of competition in business
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
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