1,721,408 research outputs found
Non-toxic protection against epibiosis
No full textEpibiosis on four marine benthic invertebrate species was found to be reduced relative to other nearby surfaces, suggesting the existence of an underlying protection against fouling. In all four cases, toxic chemical antifouling defenses were wanting or inconsistent. However, the lack of epibionts could be attributed to the existence of non-toxic protective properties in all instances, viz. periodic emergence and mutual grazing in the gastropod, Littorina littorea, cumulative filtration and an as yet unidentified fouling-reducing property of the periostracum of the bivalve Mytilus edulis, repellency and, possibly, mucus secretion in the colonial ascidian, Cystodytes lobatus, burrowing, periodic emergence (intertidal individuals) and moulting in the crustacean, Carcinus maenas. It seems that such protective systems are often multiple, consisting of several, more or less overlapping, adaptations to reduce fouling. Characteristics of these non-toxic, multiple protection systems and their significance for potential epibionts are discussed
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
Periprosthetic fracture fixation in osteoporotic bone
No full textFixation techniques of periprosthetic fractures are far from ideal although the number of this entity is rising. The presence of an intramedullary implant generates its own fracture characteristics since stiffness is altered along the bone shaft and certain implant combinations affect load resistance of the bone. Influencing factors are cement fixation of the implant, intramedullary locking and extramedullary or intramedullary localization of the implant and the cortical thickness of the surrounding bone. Cerclage wires are ideally suited to fix radially displaced fragments around an intramedullary implant but they are susceptible to axial and torsional load. Screws should be added if these forces have to be neutralized. Stability of the screw fixation itself can be enhanced by embracement configuration around the intramedullary implant. Poor bone stock quality, often being present in metaphyseal areas limits screw fixation. Cement augmentation is an attractive option in this field to enhance screw purchase. (C) 2016 Elsevier Ltd. All rights reserved
Experiment on washing procedures to extract positively buoyant microplastics (> 500 µm) from beach wrack
No full textThe "beach wrack - plastic separator" is the prototype of a simple construction that we used to assess two methods for washing beach wrack. Its main component is a polypropylene container that is 40 x 30 x 22 cm in size and has a volume of 20.8 l. Furthermore, we used two grids (39.5 cm x 25.5 cm) that could be inserted horizontally into the container and between which a beach wrack sample of 500 g could be placed. The grids were made of aluminium and had a mesh size of 1 cm x 1 cm. Two handles were attached to the lower of the two grids that allowed to move the grids vertically inside the container. As soon as the container was filled with 10 litres of tap water, the upper grid prevented the beach wrack from floating to the surface, while the lower kept it from settling on the bottom of the container. The separation of the plastic particles from the sample material was induced by moving the grids up and down manually or by bubbling pressured air, which was supplied through air inlets, through the beach wrack material.For assessing the extraction efficiency of the two washing procedures, 48 kg of beach wrack were collected at the beach of Falckenstein, which is located at the western shore of the outer Kiel Fjord, Germany, (N 54.391250, E 10.190728) from May to August 2018.
After collection, we divided the 48 kg into 96 batches of 500 g each, which were then spiked with microplastic particles. Half of the batches consisted of Zostera leaves, while the other half consisted of thalli of Fucus spp. We did not dry the material prior to spiking and we used two types of polymers of three size classes to be able to assess the influence of polymer type and particle size on the recovery rate. We have used polypropylene (PP) fragments with a density of 0.88 to 0.91 g/cm3 (Herrera et al., 2018) and spheres of expanded polystyrene (EPS), with a density of 0.01 to 0.05 g/cm3 (Herrera et al., 2018). The densities of both polymer types are lower than seawater. The different particle size classes were either manually created or directly purchased. We tested the following three size classes: 500 to 1000 µm, 1000 to 2000 µm and 2000 to 5000 µm.
We have produced PP fragments from plastic cups (wall thickness: 0.5 mm) that we collected at the driftline of the beach of Falckenstein, and which had the polymer type indicated on their bottom. The cups, which were free of epibionts, were cut into quadratic fragments that fell into the three size classes using a scissor. The EPS spheres were purchased in the same size classes. A defined number of particles from each of the three size classes was weighed on a laboratory scale. Then the particles were carefully mixed into the beach wrack at a weight ratio of 1 : 1x104 (2000 to 5000 µm) or 1 : 1x105 (the two remaining size classes).
To achieve the weight ratios mentioned above, we either added a) 19 particles of PP or 15 particles of EPS in the size range of 1000 to 2000 µm, b) 30 particles of PP or 20 particles of EPS in the size range of 500 to 1000 µm or c), 12 particles of PP or 26 particles of EPS in the size range of 2000 to 5000 µm to one individual batch. For each replicate, the PP and EPS particles were counted and weighed individually. After spiking, we let the beach wrack rest for a maximum of 20 minutes and then placed the material between the two grids in the beach wrack - plastic separator. The lower grid was at a distance of 1 to 2 cm to the bottom, what would allow negatively buoyant microplastic particles (not tested in this study) to sink to the bottom of the container and to accumulate underneath the lower grid.
The separation efficiency of both procedures was then analysed regarding the following four factors: 1. type of beach wrack, 2. polymer type 3. polymer size and 4. duration of washing. The principle component of the separation process was the induction of a water flow, which detached the plastic particles from the surface of the macrophyes and also released them from hollows between their leaves or thalli. In the manual washing process, this was achieved by moving the grids up and down ten times in quick succession with an amplitude of 15 cm. The amplitude as well as the speed and number of repetitions then resulted in an up- and downward flow of water through the sample material that was strong enough to separate the microplastic particles from the macrophytes. The released particles floated up and were picked manually from the water surface. The particles were identified as either PP or EPS particles belonging to one of the three size classes. This was done after each single movement of the grids (up and down), so that particle extraction success could be assessed for each polymer type/size class as a function of the washing effort. This procedure was repeated with both types of beach wrack (Zostera marina L. and Fucus spp.), for both particle types (PP fragments and EPS spheres) and for all size classes within each particle type. For each of these 12 treatment combinations (beach wrack type with two levels x particle type with two levels x size class with three levels), we had four replicates and we used new beach wrack and new plastic material for each of them.
The air-facilitated washing of the beach wrack was also done with tap water. For this, three cylindrical diffusor stones (diameter: 50 mm) were connected to an electric air compressor (Pontec PondoAir Set 200) via tubes (diameter: 4 mm, total length: 100 cm) and placed underneath the lower grid. Again, individual batches of 500 g of beach wrack were placed in between the two grids and were then bubbled with air for four hours at an overall discharge rate of 200 l pressured air/h. This rate generated a water flow through the sample material with a velocity that was sufficient to separate the microplastic particles from the beach wrack material. In addition to this, the air bubbles themselves presumably released particles from macrophyte surfaces or from hollows between their thalli or leaves. This was done by the shear stress they exerted when getting in direct contact with a particle or by transferring a momentum that set the particle in motion
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
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