1,721,080 research outputs found
Chemical sensing in the submillimeter wave regime
No full text© 2004 COPYRIGHT SPIE--The International Society for Optical EngineeringT-ray systems offer an exciting range of capabilities for chemical and biological diagnostics using the emerging technology of terahertz pulse imaging. We report results from the first Australian T-ray program and discuss how MOEMS techniques can be applied to decrease the system size. A small portable T-Ray system will cost less and is needed, for example, in endoscopic applications.Samuel P. Mickan, Xi-Cheng Zhang, Jesper Munch, and Derek Abbot
Yellow laser performance of Dy 3+ in co-dopedDy,Tb:LiLuF4
No full textWe present laser results obtained from a Dy3+-Tb3+ co-doped LiLuF4 crystal, pumped by a blue emitting InGaN laser diode, aiming for generation of a compact 578 nm source. We exploit the yellow Dy3+ transition F9/24⇒H13/26 to generate yellow laser emission. The lifetime of the lower laser level is quenched, via energy transfer, to co-doped Tb3+ ions in the fluoride crystal. We report the growth technique, spectroscopic study, and room temperature continuous wave laser results in a hemispherical cavity at 574 nm, and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden S01-P30 ytterbium clock transition, which is recommended as a secondary representation of the second in the international system of units
Increased sensitivity in T-ray liquid spectroscopy using rapid sample modulation
No full text© 2004 COPYRIGHT SPIE--The International Society for Optical EngineeringPulsed THz (T-ray) spectroscopy is sensitive, non-invasive tool for studying materials from physics to biology, but transmission measurements of liquid samples, especially water, have been limited by noise. This paper shows that the accuracy of T-ray material parameter measurements of liquid samples can be greatly increased, especially for highly-absorbing liquids, by using a rapid modulation of the liquid in the T-ray beam path, coupled with a novel implementation of mean and amplitude detection to T-ray spectroscopy. The experiments are supported by calculations quantifying the sources of uncertainty. Liquid transmission T-ray studies are valuable for understanding solvation dynamics of salts, exploring long-range structure in mixtures and probing biomolecules in suspension.Samuel P. Mickan, Jesper Munch, Xi-Cheng Zhang, and Derek Abbot
In vitro osteosarcoma biosensing using THz time domain spectroscopy
No full text© 2004 COPYRIGHT SPIE--The International Society for Optical EngineeringTerahertz time domain spectroscopy (THz-TDS) has a wide range ofapplications from semiconductor diagnostics to biosensing. Recentattention has focused on bio-applications and several groups havenoted the ability of THz-TDS to differentiate basal cell carcinomatissue from healthy dermal tissue ex vivo.The contrast mechanism is unclear but has been attributed toincreased interstitial water in cancerous tissue. In this work weinvestigate the THz response of human osteosarcoma cells andnormal human bone cells grown in culture to isolate the cells'responses from other effects. A classification algorithms basedon a frequency selection by genetic algorithm is used to attemptto differentiate between the cell types based on the THz spectra.Encouraging preliminary results have been obtained.Bradley S. Ferguson, Haibo Liu, Shelley Hay, David Findlay, Xi-Cheng Zhang, and Derek Abbot
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
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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