43,677 research outputs found
The Linfield Review Staff
No full textThe Linfield Review staff gathers around Ms. A. Osterlund at the typewriter. This image can also be found on page 76 of the 1947 Oak Leaves.
(left to right): R. Shcmalz, W. Bishop, H. Dyer, C. Anderson, A. Osterlund, P. Schupp, D. Havill, H. Robinson, E. Heberthttps://digitalcommons.linfield.edu/lca_photos/1103/thumbnail.jp
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
High-performance operation of single-mode terahertz quantum cascade lasers with metallic gratings
No full textA periodic array of thin slits opened on a metallic surface can act as a one-dimensional photonic crystal for the propagation of surface-plasmon waves. We have used such structure for the implementation of distributed feedback resonators in quantum cascade lasers emitting near 2.5 THz. Single-mode emission, stable at all injection currents and operating temperatures, was achieved both in pulsed and continuous wave. The devices exhibited output powers of several milliwatts with low threshold current densities of ∼100 A cm2
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
THz semiconductor heterostructure laser
No full textThe terahertz region (1-10THz) of the electromagnetic spectrum offers ample opportunities in spectroscopy, free space communications, remote sensing and medical imaging. Yet, the use of THz waves in all these fields has been limited by the lack of appropriate, convenient sources. We here report on a semiconductor heterostructure injection laser that emits at THz frequencies (4.44THz, lambda similar to 67 mum) and has the potential for device-like implementation. It is based on the quantum cascade scheme employing interminiband transitions in the technologically mature AlGaAs/GaAs material system and features a novel kind of waveguide loosely based on the surface plasmon concept. The electron dynamics in the structure is analysed with the help of Monte-Carlo simulations including both carrier-carrier and carrier-phonon scattering. The lasers emit more than 2 mW of peak optical power and can be operated in pulsed mode up to 60 K with threshold current densities of few hundred A/cm(2). Continuous-wave operation is achieved at temperatures below 30K with output powers of 150 muW
Control and Filtering for Discrete Linear Repetitive Processes with H infty and ell 2--ell infty Performance
No full textRepetitive processes are characterized by a series of sweeps, termed passes, through a set of dynamics defined over a finite duration known as the pass length. On each pass an output, termed the pass profile, is produced which acts as a forcing function on, and hence contributes to, the dynamics of the next pass profile. This can lead to oscillations which increase in amplitude in the pass to pass direction and cannot be controlled by standard control laws. Here we give new results on the design of physically based control laws for the sub-class of so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control. The main contribution is to show how control law design can be undertaken within the framework of a general robust filtering problem with guaranteed levels of performance. In particular, we develop algorithms for the design of an H? and dynamic output feedback controller and filter which guarantees that the resulting controlled (filtering error) process, respectively, is stable along the pass and has prescribed disturbance attenuation performance as measured by and – norms
Terahertz quantum cascade lasers
No full textThe terahertz region (1-10 THz) of the electromagnetic spectrum offers paramount opportunities in spectroscopy, remote sensing, medical imaging and free space communications. Yet, the use of THz waves in all these fields has been limited by the lack of appropriate, convenient sources. We here report on unipolar semiconductor injection lasers that emit at THz frequencies (4.3 THz, lambda similar to 69mum and 3.5 THz, lambda similar to 85mum) and possess the potential for device-like implementation. They are based on the quantum cascade scheme employing interminiband transitions in the technologically mature AlGaAs/GaAs material system and feature a novel kind of waveguide loosely relying on the surface plasmon concept. Continuous-wave laser emission is achieved with low tresholds of a few hundred A/cm2 up to 45 K heat sink temperature and maximum output powers of more than 4 mW. Under pulsed excitation, peak output powers of 4.5 mW at low temperatures and still 1 mW at 65 K are measured. The maximum operating temperature is 67 K
Distributed feedback terahertz frequency quantum cascade lasers with dual periodicity gratings
No full textWe have developed terahertz frequency quantum cascade lasers that exploit a double-periodicity distributed feedback grating to control the emission frequency and the output beam direction independently. The spatial refractive index modulation of the gratings necessary to provide optical feedback at a fixed frequency, and simultaneously, a far-field emission pattern centered at controlled angles, was designed through use of an appropriate wavevector scattering model. Single mode terahertz (THz) emission at angles tuned by design between 0° and 50° was realized, leading to an original phase-matching approach for highly collimated THz quantum cascade lasers
Conservatismo en el simbolismo de Oaxaca: un breve informe.. Anales del Instituto Nacional de Antropología e Historia. Num. 49 Tomo I (1967-1968) Séptima Época (1967-1976)
No full textCaso, A. 1928 Las Estelas Zapotecas. Monografías del Museo Nacional de Arqueología, Historia y Etnografía. México.Caso, A. y Bernal, l. 1952 Urnas de Oaxaca. Memorias del Instituto Nacional de Antropología e Historia, II. México.Boos, Frank H. 1964 Las Urnas Zapotecas en el Museo Real de Ontario. Corpus Antiquitatum Americanensium, vol. l. Instituto Nacional de Antropología e Historia. México.Boos, Frank H. 1965 The Oaxacan Urn of the Zapotec God One Z and the Urn of his Feminine Companion. Wadsworth Athenaeum Bulletin. Sixth series, vol. 1. No. 2. Hartford, Connecticut.Boos, Frank H. 1966 The Ceramic Sculptures of Ancient Oaxaca. A. S. Barnes & Co., New York y Thomas Yoseloff Ltd., London.Leigh, H. 1958 An Identification of Zapotec Day Names. Boletín de Estudios Oaxaqueños, No. 6. Mexico City College, México.Paddock, J. 1966 Ancient Oaxaca. Stanford University Press
Contribution of Information and Communication Technology (ICT) in Country’S H-Index
No full textThe aim of this study is to examine the effect of Information and Communication Technology (ICT) development on country’s scientific ranking as measured by H-index. Moreover, this study applies ICT development sub-indices including ICT Use, ICT Access and ICT skill to find the distinct effect of these sub-indices on country’s H-index. To this purpose, required data for the panel of 14 Middle East countries over the period 1995 to 2009 is collected. Findings of the current study show that ICT development increases the H-index of the sample countries. The results also indicate that ICT Use and ICT Skill sub-indices positively contribute to higher H-index but the effect of ICT access on country’s H-index is not clear
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