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A physics exhibit to show the effect of the aerosol in the atmosphere on electromagnetic wave propagation
No full textIn this paper it is explained the construction and utility of a didactic exhibit about the effect of aerosol in atmosphere on electromagnetic wave propagation. The exhibit is composed by a lamp simulating the Sun, a Plexiglas case (the atmosphere), white or black panels (surface albedo), a combustion chamber to supply aerosol inside the case and other equipments. There are temperature and relative humidity of air sensors and 5 light sensors to measure direct and scattered light. It is possible to measure the cooling effect of aerosol inside the case and the increasing in scattered ligh
Misura della velocità della luce con mezzi modici
No full textA simple way of measuring the speed of light in an educational context using one or couple of mirrors and some easily available common electronic equipment is describe
Misure della variazione del flusso dei raggi cosmici con l'altitudine per mezzo di un pallone aerostatico
No full textOur target is to measure cosmic ray flux at different altitudes, with didactic detector.
The detector is based on project “muon detector” presented on website www.astroparticelle.it .
The idea is to use 2 fluorescent tube lamps. When a muon hits the detector, it ionizes some atoms of gas of the lamp. Putting an electric tension (order of 1 kV) outside the tube with electrodes spaced 10cm each other, the ionized atom goes toward one electrode. If ionized atom hit glass produces lamp, as internal surface of these lamps are coated with fluorescent powder. First step is looking lamp with human eyes.
Second step: we would automatize muons detection. To observe lamps we put a light sensor for each sector of the detector (the sections are 5 for each tube). To discriminate environmental radioactive event we use a coincidence method: if we see an event in each tube we assume that this is a cosmic ray, because in general only a cosmic ray has sufficient energy to pass to the second lamp.
The apparatus is controlled by a microcontroller board Arduino.
To measure cosmic ray flux at different altitudes the detector will be uplift with a balloon filled with helium gas. It is under study a communication system and a GPS localization system to reach more control of balloon flight.
The project has important educational purpose: students can approach to modern physics with simple detector that can be reproduced with everyday equipments. It gives us the opportunity to teach some simple electronic components: diode, transistor and photodiode and/or photoresistor
A Physics Exhibit to Show the Effect of the Aerosol in the Atmosphere on Electromagnetic Wave Propagation
No full textAbstractIn this paper it is explained the construction and utility of a didactic exhibit about the effect of aerosol in atmosphere on electromagnetic wave propagation. The exhibit is composed by a lamp simulating the Sun, a Plexiglas case (the atmosphere), white or black panels (surface albedo), a combustion chamber to supply aerosol inside the case and other equipments. There are temperature and relative humidity of air sensors and 5 light sensors to measure direct and scattered light. It is possible to measure the cooling effect of aerosol inside the case and the increasing in scattered light
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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