1,720,979 research outputs found
New insight in the neuropharmacological activity of Humulus lupulus L
No full textThe purpose of the present study was to investigate the effects of Humulus lupulus CO2 extract and its fraction containing α-acids on the central nervous system of rats. Both tested substances were able to prolong pentobarbital sleeping time, without affecting the latency to the loss of the righting reflex. This effect was dose-dependent, starting from a minimal dose of 10 mg/kg. Neither the extract nor its α-acid fraction affected the locomotor activity in the open field test or exerted an anxiolytic effect in rats submitted to the elevated plus-maze test. Interestingly both compounds reduced the immobility time during the behavioral despair test when administered three times (24, 5 and 1 h) before the test. In conclusion this report shows that Humulus lupulus CO2 extract exerts: (a) a pentobarbital sleep-enhancing property without influencing the motor behavior of rats; (b) an antidepressant activity. The same effects were elicited by the administration of the Humulus lupulus fraction containing α-acids, which can be considered as the major responsible for the enhanced pentobarbital effect and for the antidepressant property
Design of heat pipes on board accelerating vehicles using the 1D/3D co-simulation approach
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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
CFD analysis of a two-stroke air cooled engine designed for handheld products
No full textStill today, two-stroke engine layout is characterized by a wide share on the market thanks to its simpler construction that allows to reduce production and maintenance costs respecting the four-stroke engine. Two of the main application areas for the two-stroke engines are on small motorbikes and on handheld machines like chainsaws, brush cutters, and blowers. In both these application areas, two-stroke engines are generally equipped by a carburettor to provide the air/fuel mixture formation while
the engine cooling is assured by forcing an air stream all around the engine head and cylinder surfaces.
Focusing the attention on the two-stroke air-cooling system, it is not easy to assure its effectiveness all around the cylinder surface because the air flow easily separates from the cylinder walls producing local hot-spots on the cylinder itself. This problem can be bounded only by the optimization of the
cylinder fin design placed externally to the cylinder surface. In the present paper the authors present a first analysis of the thermal-flow behaviour of a two stroke engine designed for brush-cutter machine applications. The optimization of the air-cooling system of such a machine is a very challenging task
because the machine design is very compact forcing all the engine parts to remain quite close to each other. The proposed analysis is performed by the definition of a specific 3D-CFD simulation methodology based on the Conjugated Heat Transfer approach. The methodology was validated against experimental data
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
CFD Analysis of Injection Timing Influence on Mixture Preparation in a PFI Motorcycle Engine
No full textThe efficiency of engine operations, i.e. cold start, transient response and operating at idle, depends on the capability of
the injection fuel system to promote a homogeneous mixture formation through an efficient interaction with engine fluid
dynamics and geometry. The paper presents the development and the application of a methodology for running a CFD
PFI engine simulation. A preliminary assessment of the wall-film and droplet-wall interaction sub models has been
carried out in order to validate the methodology. Then a three-step numerical procedure has been adopted. The first two
steps are aimed to properly initialize the secondary breakup model depending on the type of injector installed on board in
order to achieve accurate predictions of spray characteristics. Then, in the third step, the CFD calculations have been
used to investigate the mixture formation with the particular focus to achieve an homogeneous mixture formation without
the contamination of the lubricant with fuel. A particular engine operating condition at low load is here discussed
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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