1,720,957 research outputs found
Novel aluminium air batteries for ultralight micro-aircraft
No full textThis thesis investigates the feasibility of using a structural aluminium air battery to power an ultralight, unmanned micro-aircraft. Weight loss, voltammetry and scanning electron microscopy have been used to investigate the rate of corrosion and anodic dissolution of aluminium materials in potential battery electrolytes. Various alloys were examined in both alkaline and saline electrolytes and there were substantial differences in corrosion resistance, types of corrosion and overpotential required for anodic dissolution. It was found that high purity aluminium and alloys with small additions of certain metals had better corrosion resistance in alkaline solution. No materials investigated would allow extended storage of a battery; emphasis was therefore placed on a cell where 8M KOH Vias added immediately before discharge. AB50V, an AI-Mg-Ga-Sn alloy, was selected as the negative electrode in a small aluminium-air battery. This alloy had an open circuit potential of ~ -2.0 V vs. SCE and gave a current density of 100 rnA cm-2 at ~ -1.8 V vs. SeE. A test battery cell was constructed incorporating a Pt-catalysed air cathode, and a battery voltage of ~ 1 J V at a current density of 160 rnA cm-2 was obtained using the AB50Valloy. The non-availability commercially of more alloys \vith fully specified compositions and a controlled range of compositions hampered both the scientific interpretation of the data and the optimisation of battery performance. High surface area fOTIns of aluminium should substantially improve this performance but are only available commercially in Al of unspecified composition. Commercially available AI foams were found to corrode very rapidly. Stacked meshes made with melts pun aluminium were compressed, and although they showed reasonable structural strength, did not show the required performance; meltspun fibres are inherently impure due to the fabrication process and so were lillsuitable for making high purity alloys. With the low weight of the current structural polymer foam used in production of the U A V, the positioning of the battery system on the plane is constrained to a skin around the nose cone. Such a design would, however, provide additional structural support to the aircraft, increase significantly the volume for electronics and sensory equipment in the pod. and reduce heating of such equipment by the battery operation.</p
Alterations in cerebrospinal fluid apolipoprotein E and amyloid beta-protein after traumatic brain injury
No full textThere is evidence that apolipoprotein E (apoE) and amyloid beta-protein (Abeta), which are implicated in the pathology of chronic neurodegenerative disorders, are involved in the response of the brain to acute injury; however, human in vivo evidence is sparse. We conducted a prospective observational study to determine the magnitude and time-course of alterations in cerebrospinal fluid (CSF) apoE and Abeta concentrations after traumatic brain injury (TBI), and the relationship of these changes to severity of injury and clinical outcome. Enzyme linked immunosorbant assay (ELISA) was used to assay apoE, Abeta(1-40) and Abeta(1-42) in serial CSF samples from 13 patients with TBI and 13 controls. CSF S100B and tau were assayed as surrogate markers of brain injury. There was a significant decrease in CSF apoE (p < 0.001) and Abeta (p< 0.001) after TBI contrasting the observed elevation in CSF S100B (p < 0.001) and tau (p < 0.001) concentration. There was significant correlation (r = 0.67, p = 0.01) between injury severity and the decrease in Abeta(1-40) concentration after TBI. In vivo, changes in apoE and Abeta concentration occur after TBI and may be important in the response of the human brain to injury
Cerebrospinal fluid apolipoprotein E concentration decreases after traumatic brain injury
No full textThe APOE epsilon4 allele has been associated with unfavorable outcome after several types of acute brain injury, yet the biological mechanisms underlying this observation are poorly understood. Postmortem and experimental brain injury studies suggest the presence of increased amounts of apolipoprotein E (apoE) within the neuropil after acute brain injury. We assayed the concentration of apolipoprotein E in the cerebrospinal fluid (CSF) of non-injured controls and patients with traumatic brain injury (TBI) to determine whether differences exist, and if these differences correlate with injury severity and clinical outcome. CSF apoE and S100B, a marker of injury severity, were measured by enzyme linked immunosorbant assay. CSF was sampled from 27 traumatic brain injury patients (mean age 32, median 25, range 16-65 years) within 3 days of injury, and 28 controls (mean age 40, median 37, range 19-73 years). The TBI patients all had a Glasgow Coma Score (GCS) of less than eight (i.e., severe head injury). Clinical outcome was determined using the Glasgow Outcome Score (GOS). The average concentration of apoE in the CSF of controls was 12.4 mg/L (95% CI: 10.5-14.3 mg/L) and in TBI patients was 3.7 mg/L (95% CI: 2.1-4.1 mg/L; Mann-Whitney: p < 0.0001). In contrast, the concentration of S100B in the CSF of TBI patients was significantly higher than that of controls (Mann-Whitney: p < 0.0001). We speculate that apoE is retained within the parenchyma of the central nervous system in response to injury where in view of previous data, it may have a protective role
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
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