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Papers dedicated to Professor Dr. Wolfgang Schroter on the occasion of his 65th anniversary - Preface
No full textPapers dedicated to Professor Dr. Wolfgang Schroter on the occasion of his 65th anniversary - Preface
No full textEffects of temperature on the birefringence properties of polarisation maintaining fibres
No full textMany optical fibre sensors such as interferometers and gyros require the transmission of stable colinear polarised light. External perturbations such as bends and twists, however, lead to variations in the output polarisation state of light guided by ordinary single-mode optical fibres (Payne et al (1)). Highly birefringent fibres attempt to overcome this difficulty by deliberately introducing levels of intrinsic birefringence Δβ in excess of that produced by external factors, thereby rendering the polarisation state immune to all but the most major perturbations. Such fibres are characterised by their modal birefringence B, defined as nx - ny = λ/2π ΔB, where nx and ny refer to the refractive indices x and y respectively. A commonly quoted figure of merit however, is the so-called beat length Lp = λ/B at a given wavelength
SCALING THE SI METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR INTO THE 0.1-MU-M REGIME USING VERTICAL DOPING ENGINEERING
No full textConventional scaling of the Si MOSFET into the deep submicron regime requires high substrate doping levels. This extracts a severe speed penalty, if lower standby power consumption (i.e., good subthreshold behavior) is to be maintained. We explore the scaling of fully depleted silicon-on-insulator (SOI) structures, and show, both analytically and by numerical simulation, how the horizontal leakage is controlled by vertical doping engineering. Our analysis allows different structures to be evaluated in terms of a natural length scale indicating good subthreshold behavior. Finally, we describe how retrograde doping may be used to mimic the SOI concept in bulk Si. Our results show good subthreshold behavior in the deep submicron regime can be achieved without large junction capacitance, high threshold voltage, or heavy channel doping
Enhancement of birefringence in polarisation-maintaining fibres by thermal annealing
No full textThe thermal behaviour of highly birefringent polarisation-maintaining optical fibres is studied, and the thermal hysteresis of the birefringence is related to the quenching of the fibre. Suitable 'on-line' thermal annealing during fibre drawing is shown to be a method for the full development of the high anisotropic stresses potentially available in high birefringence structures using borosilicate stress-producing parts
Thermal properties of highly birefringent optical fibres and preforms
No full textTemperature cycling of highly birefringent optical fibers and preforms has been used to investigate the thermal properties of bow-tie and elliptically clad structures. The thermal hysteresis of the birefringence is shown to be a direct consequence of the thermal history of the fiber or preform and has been related to volume changes in the stress-producing borosilicate sections. Annealing increases the axial stress as well as the stress anisotropy and hence the birefringence. Increases of up to a factor of 2 in the birefringence on suitable thermal treatment indicate a new method for further improvement of high birefringence fibers. The implications of the results in the design, fabrication, and use of such fibers are discussed
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
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