152,751 research outputs found
Replication Data for: A Structural Model for the Coevolution of Networks and Behavior
No full textHsieh, Chih-Sheng, König, Michael D., and Liu, Xiaodong, (2022) “A Structural Model for the Coevolution of Networks and Behavior.” Review of Economics and Statistics 104:2, 355–367
Ultrafast Laser Fabrication of 3-D Photonic Components and Photonic Topological Insulators
No full textOptical waveguide interconnect has been considered as a key enabling technology to address bandwidth bottleneck limited by electrical wire at board levels. Current waveguide technology for optical interconnect were realized based on 2D waveguide technology based on layer-by-layer lithography schemes built on silicon or polymer substrates. As data rate explodes at chip and board levels, the optical routing complexity and high laser power required to support high data bandwidth demand a new waveguide interconnect topology.
In this dissertation, we study and explore ultrafast laser fabrication technology to build highly complex 3D waveguide lightwave circuits in glass substrates to support demand for high bandwidth optical interconnect. This dissertation first explores 3D waveguide structure fabrication in flexible glass substrates. Characteristics and performances of various waveguide devices inscribed in flexible glasses are compared with those built on polymer substrates. This work is then followed by development of an integrated laser manufacturing solution, using the same platform, to manufacture board-level optical interconnect waveguides and 45° total internal reflection (TIR) micromirror for vertical coupling. To expand 3D waveguide technology in optical fiber devices, 3D waveguide couplers and WDM components, two key components for fiber lasers, were directly fabricated on multi-core optical fibers, turning the silica fiber from a 1-D optical channel to a 3-D integrated system. Based on paraxial approximation, 3D coupled photonic waveguide array were designed, fabricated, and characterized to study photonic graphene under Gauge field. Results and efforts described in this dissertation demonstrated that, through the optimization of laser matter interaction, high-density 3D waveguide consists of more than 15 layer can be fabricated for a wide array of photonic applications
FIGURE 1. Petrocosmea panzhouensis Sheng H in Petrocosmea panzhouensis (Gesneriaceae), a new species from Guizhou, China
No full textFIGURE 1. Petrocosmea panzhouensis Sheng H.Tang & Tao Peng, sp. nov. A, B flowering plant C adaxial and abaxial surfaces of leaf blade D cymes, and bracts inside and outside (inset) E flower in front view F flower in side view, and calyx lobes outside and inside (inset) G flower in top view H opened corolla with pistil removed, showing stamens, and spots inside the corolla I stamens ventral and dorsal, and dehiscing terminal anther pores (inset) J pistil, cross section of ovary (inset), and red lines showing the shape of placentas K capsules of previous year L seeds of previous year. (Photographs by Sheng-Hu Tang).Published as part of Tang, Sheng-Hu, Zhang, Jian-Hua, Peng, Tao & Guo, Ying, 2022, Petrocosmea panzhouensis (Gesneriaceae), a new species from Guizhou, China, pp. 225-231 in Phytotaxa 572 (3) on page 226, DOI: 10.11646/phytotaxa.572.3.1, http://zenodo.org/record/732217
Attitudes Toward Languages in Nairobi
Get PDFClaims of a shift in attitudes toward indigenous, national and European languages in Africa have raised concerns of drastic language shift and consequent language death. In addition to these languages, certain African urban centers in recent decades have seen the birth of youth hybrid languages, which function as in-group markers, as well as tools for negotiating between the conflicting demands of tradition and modernity. In Nairobi Kenya, the youth language is known as Sheng. Attitudes toward Sheng as well as toward the indigenous, national and European language in Kenya are studied through survey research, examining difference between age groups, genders and socioeconomic classes. The data confirms claims of attitude shift. While English is the language gaining the strongest allegiance among the youth, Kenyans of all ages recognize the growing importance of Sheng. In the light of the history of similar languages, the positive attitudes of the youth toward Sheng can be considered a symptom of the gradual death of the indigenous languages
MeSH term explosion and author rank improve expert recommendations
Get PDFInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Sheng : the mixed language of Nairobi
No full textThe purpose of this dissertation is to determine whether Sheng, a language spoken in the Eastlands area of Nairobi, Kenya, is a mixed language (incorporating Swahili, English and local vernaculars). The study focuses on the lexicon and morphosyntax, but social factors are examined as well. Three broad research questions are addressed: (1) Does Sheng have a core vocabulary separate from that of Swahili? (2) How do the system morphemes of Sheng compare with those of Swahili? And (3) in what manner does Sheng provide its speakers a new identity?With respect to question one, the core lexicon, like Russenorsk's, Trio-Ndjuka's and Michif's, manifests a nearly fifty-fifty split in Sheng (52% Swahili; 48% other), making it a mixed language lexically.As for question two, the analysis reveals that Sheng has a composite morphosyntax. No object or relative affixes are marked on the verb. Predicate-argument structure from English has provided a null relativizer. The aerial feature imperfective suffix -a(n)g- is preferred 68% of the time. Noun classes show convergence leveling. The marker ma- serves as the generic plural. The diminutive markers, (ka-, to-), constitute a complete non-Swahili subsystem. Consequently, Sheng is also a mixed language morphosyntactically.In reference to question three, a negative correlation exists between competence in Sheng and income and housing. Though the affluent display a negative attitude towardSheng, they agree with the lower socio-economic groups that Sheng has a communicative utility in metropolitan Kenya. A comparison of the usage in the different residential areas establishes that community-wide grammatical norms (i. e., stability) exist in Sheng. Over two decades without institutional support for Swahili provided a niche in which Sheng, a non-standard language variety, flourished and a new urban identity emerged.Eastlanders walk a linguistic tightrope, balancing between the labels mshamba (`rube') and Mswahili (`slick talker'). However, Sheng provides a sociolinguistic embodiment symbolizing what nuances their existence. Over time, speakers formed a new identity group, whose language was initially `off target' (1899-1963) but subsequently became deliberate postcolonially. Finally, the name of the language itself (Sheng < LiSheng < lish-eng < English) results from and is symbolic of this social transformation.Thesis (Ph. D.)Department of Englis
FIGURES 3A–D in Draconarius manus sp. nov., the third species of D. pseudocoreanus - group from China (Araneae: Agelenidae)
No full textFIGURES 3A–D. Draconarius manus sp. nov., Habitus OF HOLOtype maLe (A) and paratype FemaLe (B).Published as part of Wang, Yan-Chao & Zhang, Zhi-Sheng, 2018, Draconarius manus sp. nov., the third species of D. pseudocoreanus - group from China (Araneae: Agelenidae), pp. 397-400 in Zootaxa 4418 (4) on page 399, DOI: 10.11646/zootaxa.4418.4.7, http://zenodo.org/record/124482
MBER Space-Time Decision Feedback Equalization assisted Multiuser Detection for Multiple Antenna Aided SDMA Systems
No full textThis paper proposes a space-time decision feedback equalization (ST-DFE) assisted multiuser detection (MUD) scheme for multiple receiver antenna aided space division multiple access systems. A minimum bit error rate (MBER) design is invoked for the MUD, which is shown to be capable of improving the achievable bit error rate performance and enhancing the attainable system capacity over that of the standard minimum mean square error (MMSE) design. An adaptive implementation of the MBER ST-DFE assisted MUD is proposed using a stochastic gradient-based least bit error rate algorithm, which is demonstrated to consistently outperform the classical least mean square (LMS) algorithm, while achieving a lower computational complexity than the LMS algorithm for the binary signalling scheme. Our simulation results demonstrate that the MBER ST-DFE assisted MUD is more robust to channel estimation errors as well as to potential error propagation imposed by decision feedback errors, compared to the MMSE ST-DFE assisted MUD. Index Terms—Decision feedback equalizer, minimum bit error rate, minimum mean square error, multiple antennas, multipleinput multiple-output, multiuser detection, space-division multiple access, space-time processing
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
Adaptive Bayesian Space-Time Equalisation for Multiple Receive-Antenna Assisted Single-Input Multiple-Output Systems
No full textThis contribution considers nonlinear space–time equalisation (STE) for multiple receive-antenna induced single-input multipleoutput (SIMO) systems. By exploiting the inherent symmetry of the underlying optimal Bayesian STE solution, a novel symmetric radial basis function (RBF) based STE scheme is proposed, which is capable of approaching the optimal Bayesian equalisation performance. Adaptive implementation of this symmetric RBF (SRBF) based STE can be achieved conveniently by estimating the SIMO channels using the least mean square channel estimator and computing the optimal RBF centres from the resulting SIMO channel matrix estimate. Simulation results also demonstrate that the performance of this SRBF based STE is robust with respect to the choice of the RBF variance value. The proposed adaptive solution is then extended to the space–time decision feedback equalisation (ST-DFE) structure
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