1,721,005 research outputs found
Fabrication of Graphene Field Effect Transistors (GFET) possessing a photoelectrical response
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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
Photoelectrical response of Graphene Field Effect Transistors (GFETs)
No full textIn this work, we present Graphene Field Effect Transistors (GFETs) with photoelectrical response due to the photovoltaiceffect.
Our final aim is to use a GFET to down convert an optical to a radiofrequency signal. The technological steps used for the devices fabrication
as well as the photoelectrical characterization will be reported. Photoelectrical measurements were performed by using a 405
nm laser diode source, whose output beam was pulse amplitude-modulated at 1.33 kHz by means of a laser driver.
The electrical signal out of the GFETs (in a common source amplifier configuration) was measured using a lock-in amplifier synchronized to the same reference frequency of the laser driver. This gave us the possibility to evaluate the optical response as a function of both the incident laser power and the DC biasing of the device. In particular, in order to explore the GFETs photovoltaic characteristics, we decided to perform low noise measurements at zero bias (VDS=0) and with VGS ranging between -2V and +2V. We found that the optical response of our device depends on the static polarization of the gate-source voltage and it shows a linear trend as a function of the incident laser power
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
Photocurrent generation in Graphene Field Effect Transistors (GFETs)
No full textIn this work, we focused on the study of Graphene Field Effect Transistors (GFETs) photoelectrical response due to the combination of photovoltaic and photo-thermoelectric effects. The technological steps for the transistors fabrication together with their electro-optic response will be presented.
Measurements were performed by using a 405 nm laser diode with AM modulation at 1.33 KHz shined onto the sample under test. GFETs electrical output signals were measured by using a lock-in amplifier synchronized to the same reference frequency of the laser driver. This gave us the possibility to evaluate the optical characteristics as a function of both the incident laser power and the static polarization of the device. We found that the optical response of our devices depends on the static polarization of the gate-source voltage and it shows a linear trend as a function of the incident laser power
Microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions
No full textGraphene is a relatively new material whose unique properties have attracted significant interest for its use in electronic and photonic applications. In particular, field effect has been proved in graphene samples and this feature, together with the high carrier mobility observed, makes graphene an interesting solution for high frequency electronics.
In our work, we performed a statistical analysis in order to evaluate the microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions. In more detail, for the first time, we studied the behavior of the cut-off frequency (ft) and of the output impedance (Zout) at varying both the gate-drain/gate-source distance (Δ) and the gate length (Lg). In order to perform the abovementioned statistical analysis, we fabricated 24 GFETs families on the same chip. Each family is composed of 10 equal devices, with the same Δ and Lg values. After their fabrication, the GFETs were characterized in both DC and RF regimes. DC measurements allowed us to obtain the transconductance curves (Id vs Vgs) and, hence, to evaluate the static transconductance (gm), whose value deeply influences the cut-off frequency. The scattering parameters were then measured, in the region where gm shows its highest value, by using a vector network analyzer. This allowed us to evaluate the short circuit current gain (h21), ft and Zout
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