1,720,958 research outputs found
Comparative evaluation between E-Glass and hemp fiber composites application in rotorcraft interiors
No full textThe present paper describes concepts and a preliminary project of a helicopter device, to investigate the use of natural fiber composites for semi-structural applications, such as electronic racks. The aim of the study consists on the evaluation of the substitution of the steel electronic rack, mounted on the helicopter Eurocopter AS 350 Écureuil, with a new version, utilizing hemp fabric/epoxy composite material. This replacement will permit to have an environmental friendly product and lower disposal costs and weight. Lower weight for helicopters and more in general for aircraft means lower fuel consumption, lower pollution and costs. The new rack has been designed using structural static and dynamic analysis through Finite Element Method (FEM). Results are promising from the structural point of view. In fact, a weight reduction of 8.01 kg (55.6%) with respect to steel has been obtained without significantly increasing the production cost. A comparison with glass fabric/epoxy composites is also provided. The results for both the composite materials are very similar, but the advantages for the environment demonstrate that is worthy choosing natural fiber composites configuration
Comparative evaluation between E-Glass and Hemp fiber Composites for Rotorcraft Interiors Applications
No full textThe present paper describes concepts and a preliminary project of a helicopter device, to investigate the use of natural fiber composites for semi-structural applications, such as electronic racks. The aim of the study consists on the evaluation of the substitution of the steel electronic rack, mounted on the helicopter Eurocopter AS 350 Écureuil, with a new version, utilizing hemp fabric/epoxy composite material. This replacement will permit to have an environmental friendly product and lower disposal costs and weight. Lower weight for helicopters and more in general for aircraft means lower fuel consumption, lower pollution and costs. The new rack has been designed using structural static and dynamic analysis through Finite Elements Method (FEM). Results are promising from the structural point of view. In fact, a weight reduction of 8.01 kg (55.6%) with respect to steel has been obtained without significantly increasing the production cost. A comparison with glass fibers fabric/epoxy composites is also provided. The results for both the composite materials are very similar, but the advantages for the environment demonstrate that is worthy choosing natural fiber composites configuration
L-carnitine and short chain ester in tears from patients with dry eye
No full textPURPOSE: The tear film is essential for the integrity of the ocular surface. In ocular diseases such as dry eye syndrome (DES), tear film osmolarity is increased relative to normal physiological conditions. DES can be caused by deficiency in lachrymation, hyperevaporation, or surface alterations. Carnitines, shown to have osmoregulatory properties, are thought to regulate tear film osmolarity, thus protecting the corneal surface from damage. We investigated the presence of carnitine in tears, compared tear carnitine concentrations in healthy subjects and in DES patients and speculate on carnitine's potential role as a protective agent in the tear film. METHODS: Tears were collected from 10 healthy subjects and 10 DES patients. Carnitine levels were assessed by high performance liquid chromatography-mass spectrometry. RESULTS: Carnitine and its derivatives were detected in the tear samples. In DES patients, concentrations were substantially lower than in healthy subjects; the mean concentrations were L-carnitine, 3.27 +/- 0.80 and 8.94 +/- 0.50 microMol/L; L-acetylcarnitine, 1.66 +/- 0.50 and 3.05 +/- 0.65 microMol/L; and L-propionylcarnitine, 0.30 +/- 0.11 and 0.57 +/- 0.13 microMol/L, in DES patients and healthy subjects, respectively. CONCLUSIONS: Although increased tear film osmolarity has been previously observed in DES patients, our study showed lower carnitine levels in DES patients than in healthy subjects, rather than the increased levels expected, although a causal relationship between carnitine levels and hyperosmolarity has not been established. The damage to ocular surface cells because of exposure to hypertonic tear film observed in DES may be partially because of an imbalance in the concentration of carnitine molecules in the tear film relative to the ocular surface cells. We propose, therefore, that carnitine solutions may have a role in preventing the adverse effects of observed hyperosmolarity and suggest that further studies are now warranted to investigate the clinical application of carnitine in the treatment of
Comparison of Three Lubricant Eye Drop Solutions in Dry Eye Patients
No full textPurpose. Lubricant eye drops that restore physiological osmolarity represent a promising strategy for dry eye syndrome as hyperosmolarity plays a central role in this disease. This preliminary study compared three lubricant eye drop solutions with different osmolarities and compositions in subjects with this condition.
Methods. Subjects with dry eye syndrome undergoing treatment with benzalkonium chloride-containing lubricant eye drops were randomized to Carnidrop (n = 9), Optive (n = 9), or Blu Sal (n = 9). Fluorescein break-up time (FBUT) and Ocular Protection Index (OPI) were measured at baseline, 15 min, and 60 min after instillation to evaluate the stability and quality of the tear film.
Results. At 15 min, a significant increase in FBUT vs. baseline was reported with Carnidrop (from 2.0 +/- 0.8 to 4.8 +/- 2.0; p = 0.004) but not in patients who received Optive or Blu Sal. At 60 min, FBUT was significantly increased vs. baseline with Carnidrop (from 2.0 +/- 0.8 to 6.0 +/- 2.8, p = 0.001) and Optive (from 2.9 +/- 2.8 to 4.3 +/- 2.9, p = 0.004) but not with Blu Sal. At 15 min, OPI was significantly increased from baseline in only the Carnidrop group (from 0.4 +/- 0.2 to 1.0 +/- 0.4, p = 0.003). This increase was significantly greater with Carnidrop than with Blu Sal (p = 0.003). At the 60 min evaluation, OPI remained significantly increased from baseline in only the Carnidrop group (p = 0.003).
Conclusions. Carnidrop produces a larger increase in FBUT and OPI than Optive and Blu Sal in subjects with dry eye syndrome over a 1 h period, possibly because of its hypo-osmolarity and high osmolyte (in particular l-carnitine) content. The instillation of compounds that improve the quality and stability of the tear film, which are impaired in dry eye syndrome, could be effective in the treatment of this conditio
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
L-Carnitine enhances extracellular matrix synthesis in human primary chondrocytes
No full textOsteoarthritis (OA) is one of the most common degenerative joint disease for which there is no cure. It is
treated mainly with non-steroidal anti-inflammatory drugs to control the symptoms and some supplements, such as
glucosamine and chondroitin sulphate in order to obtain structure-modifying effects. Aim of this study is to investigate
the effects of L-carnitine, a molecule with a role in cellular energy metabolism, on extracellular matrix synthesis in human primary chondrocytes (HPCs). Dosedependent effect of L-carnitine on cartilage matrix production, cell proliferation and ATP synthesis was esamine by incubating HPCs with various amounts of molecule in
monolayer (2D) and in hydromatrix scaffold (3D). L-Carnitine affected extracellular matrix synthesis in 3D in a
dose-dependent manner; moreover, L-carnitine was very effective to stimulate cell proliferation and to induce ATP
synthesis, mainly in 3D culture condition. In conclusion, L-carnitine enhances cartilage matrix glycosaminoglycan
component production and cell proliferation, suggesting that this molecule could be useful in the treatment of
pathologies where extracellular matrix is degraded, such as OA. To our knowledge, this is the first study where the
effects of L-carnitine are evaluated in HPCs
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
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