1,722,366 research outputs found
Self-mixing model of terahertz rectification in a metal oxide semiconductor capacitance
Full text linkMetal oxide semiconductor (MOS) capacitance within field effect transistors are of great interest in terahertz (THz) imaging, as they permit high-sensitivity, high-resolution detection of chemical species and images using integrated circuit technology. High-frequency detection based on MOS technology has long been justified using a mechanism described by the plasma wave detection theory. The present study introduces a new interpretation of this effect based on the self-mixing process that occurs in the field effect depletion region, rather than that within the channel of the transistor. The proposed model formulates the THz modulation mechanisms of the charge in the potential barrier below the oxide based on the hydrodynamic semiconductor equations solved for the small-signal approximation. This approach explains the occurrence of the self-mixing process, the detection capability of the structure and, in particular, its frequency dependence. The dependence of the rectified voltage on the bias gate voltage, substrate doping, and frequency is derived, offering a new explanation for several previous experimental results. Harmonic balance simulations are presented and compared with the model results, fully validating the model’s implementation. Thus, the proposed model substantially improves the current understanding of THz rectification in semiconductors and provides new tools for the design of detectors
The Motion of a Rigid Body in a Viscous Fluid: Results for Strong Solutions, Uniqueness and Integrability Properties
No full textIn this note, we show two results in the setting of Galdi-Silvestre strong solutions for the rigid body-viscous fluid interaction. The former, under an additional integrability assumption on the gradient of the initial datum, proves that the time derivative of the solution belongs to L2(0,T;L2(Ω)). The latter, thanks to a further assumption only on one solution, proves that the uniqueness holds in the quoted setting. However, our extra assumption for the uniqueness is certainly verified under the integrability assumption on the gradient of the initial datum. Hence, the set of solutions enjoying the uniqueness is not empty
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
Nutrition, Nutriceuticals in older women.
No full textFood components may influence either positively or negatively different
aspects of cancer initiation and growth, but clinical and epidemiological
data indicate that diet alone or single components of dietary products is
not associated with relevant cancer protection, an associated increase in
physical activity being required. Excess of total energy intake, as well as
alcohol consumption represent risk factors for cancer. Diets reach in fruits
and vegetables, probably but not certainly, reduce the risk of breast and
gastrointestinal cancer, the latter probably increased by preserved meat,
red meat, preserved salt fish and very hot drinks and food. Insufficient data
are present on the protective effects of fibre, fish, fatty acids, carotenoids,
vitamins B, C, E, calcium, or selenium and at the same time on the negative
effects of animal fats, heterocyclic amines, nitrosamines. Inconclusive data
seem to suggest that coffee and green tea may have a protective effect
on liver and colon-rectum cancer. Products rich in isoflavones appear to
be beneficial for endometrial cancer, with inconclusive results on breast
cancer. Folates may protect against gastrointestinal cancer. Antioxidant do
not seem to paly a major role, while vitamin D, seems to be important for
the prevention of some type of cancers such as that of colon-rectum, breast
and melanoma.
In conclusion, excessive calorie intake that induces overweight and obesity
represents a major risk factor for cancer along with alcohol consumption.
Data on modification of diet alone or of single dietary products are
inconclusive for cancer prevention
Acousto-optic interaction efficiency in Ti:LiNbO3 waveguide collinear Bragg diffraction cell
No full textTerahertz detection in MOS-FET: a new model by the self-mixing
No full textHigh frequency detection based on MOS-FET technology was long justified using a mechanism described by the plasma wave detection theory. In this paper we propose a new model based on the self-mixing process, taking place not in the channel, but in the depleted portion of the transistor body. Hydrodynamic semiconductor equations are solved in the small signal approximation. As a result, we present the dependence of the rectified voltage on the bias gate voltage, which fits carefully several experimental literature results
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
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