52 research outputs found
Concentration in Knowledge Output: A case of Economics Journals
No full textThis paper assesses the degree of author concentration in seven economics journals, which were published in India during 1990-2002. To measure the degree of author concentration, Lotka's Law was used. Moreover, we also make an exploratory analysis of the geographic, economics subfield and institutional concentration in 704 economics journals. An important finding of this paper is that specialized journals in the sample report the highest degree of author concentration. This result is quite similar to the findings by Cox and Chung (1991). Furthermore, there are several instances showing that the journals lean towards certain norms; this may affect the flow of innovative ideas into economics. We conclude that a knowledge activity, involving the high degree of concentration and a biased publication process, may affect the flow of new ideas into the discipline.Concentration, Lotka's Law
Reconstructing visibility graphs with simple robots
No full textWe consider the problem of finding a minimalistic configuration of sensors that enable a simple robot inside an initially unknown polygon P on n vertices to reconstruct the visibility graph of P. The robot can sense features of its environment through its sensors, and it is allowed to move from vertex to vertex. We aim at understanding which sensorial capabilities are sufficient for the reconstruction of the visibility graph of P. We are able to show that the combinatorial visibilities at every vertex do not contain enough information even when combined with the knowledge of the exact interior angle at each vertex. Using sensors that can put distant vertices into a spatial relation on the other hand can in some cases enable our robot to reconstruct the visibility graph of P. We show that this is true for a sensor that can distinguish whether the angle between two vertices the robot sees is convex or reflex, as long as the robot is capable of identifying the vertex it last visited. We also show that measuring angles exactly is enough, if the robot has a compass. © 2010 Springer
Reconstructing visibility graphs with simple robots
No full textWe consider the problem of finding a minimalistic configuration of sensors that enable a simple robot inside an initially unknown polygon P on n vertices to reconstruct the visibility graph of P. The robot can sense features of its environment through its sensors, and it is allowed to move from vertex to vertex. We aim at understanding which sensorial capabilities are sufficient for the reconstruction of the visibility graph of P. We are able to show that the combinatorial visibilities at every vertex do not contain enough information even when combined with the knowledge of the exact interior angle at each vertex. Using sensors that can put distant vertices into a spatial relation on the other hand can in some cases enable our robot to reconstruct the visibility graph of P. We show that this is true for a sensor that can distinguish whether the angle between the lines toward two visible vertices is convex or reflex, as long as the robot is capable of identifying the vertex it last visited. We also show that measuring angles exactly is enough, if the robot has a compass. © 2012 Elsevier B.V. All rights reserved
Carrier multiplication in van der Waals layered transition metal dichalcogenides
No full text© 2019, The Author(s).Carrier multiplication (CM) is a process in which high-energy free carriers relax by generation of additional electron-hole pairs rather than by heat dissipation. CM is promising disruptive improvements in photovoltaic energy conversion and light detection technologies. Current state-of-the-art nanomaterials including quantum dots and carbon nanotubes have demonstrated CM, but are not satisfactory owing to high-energy-loss and inherent difficulties with carrier extraction. Here, we report CM in van der Waals (vdW) MoTe2 and WSe2 films, and find characteristics, commencing close to the energy conservation limit and reaching up to 99% CM conversion efficiency with the standard model. This is demonstrated by ultrafast optical spectroscopy with independent approaches, photo-induced absorption, photo-induced bleach, and carrier population dynamics. Combined with a high lateral conductivity and an optimal bandgap below 1 eV, these superior CM characteristics identify vdW materials as an attractive candidate material for highly efficient and mechanically flexible solar cells in the future11sciescopu
Lotka' s Law, Co-authorship and Interdisciplinary Publishing
No full textThe robustness or breakdown of Lotka's law about the frequency distribution of scientific productivity depends on scientific cooperation, counting methods, interdisciplinary publishing and selection methods for sample collections. We have chosen to analyse the relationship using Mandelbrot's equivalent distribution model because this model is sensitive and uses the original data (scores). Five sets of authors and publications, the two sets used by Lotka, a set from High Energy Physics, a set from Microbiology and a set based on applicants to a research programme promoting young researchers have been used. It is shown that even for a sample of authors in High-Energy Physics with extremely strong co-authorship, Mandelbrot's distribution law is robust when complete-normalized (fractional) counting is used whereas complete counting results in a breakdown. In the field of Microbiology with much weaker cooperation, both counting methods result in a breakdown of Mandelbrot's law. Today a field like Microbiology with the corresponding set of journals, probably has a large content of interdisciplinary publishing and therefore no more fulfills the precondition of Lotka's law, that the total production of the authors (sources) is considered. For a set of applicants for the Emmy Noether Programme of the German Research Foundation. Mandelbrot's law breaks down despite the fact that all publications co-authored by the applicants are taken into account. In agreement with Bayes' theorem of conditional probabilities these results lead to the conjecture that any selection process of authors and/or publications causes a breakdown of Mandelbrot's law and, as a consequence Lotka's law
Ferromagnetism in MnX2 ( X = S, Se) monolayers
No full textUsing density functional theory combined with Monte Carlo (MC) simulations, we show that the two dimensional (2D) MnS2 and MnSe2 sheets are ideal magnetic semiconductors with long-range magnetic ordering and high magnetic moments (3 mu(B) per unit cell), where all the Mn atoms are ferromagnetically coupled, and the Curie temperatures (T-C) estimated for MnS2 and MnSe2 by the MC simulations are 225 and 250 K, respectively, which can be further increased to 330 K and 375 K by applying 5% biaxial tensile strains.Chemistry, PhysicalPhysics, Atomic, Molecular & ChemicalSCI(E)[email protected]
Fish distribution dynamics in the Aghanashini estuary of Uttara Kannada, west coast of India
No full textFish diversity (77 species) in the Aghanashini River estuary of the Indian west coast is linked to variable salinity conditions and zones I, II and III for high, medium and low salinity respectively. Zone I, the junction between Arabian Sea and the estuary, had all species in yearly succession due to freshwater conditions in monsoon to high salinity in pre-monsoon. The medium (zone II) and low (zone III) salinity mid and upstream portions had maximum of 67 and 39 fish species respectively. Maintenance of natural salinity regimes in estuary, among other ecological factors, is critical for its fish diversity
Book Review: J. Ouseparampil, Bhartrhari's Vākyapadīya Kanda-1, Pune: published by the author, 274 Pp. Rs. 400 (US$15). (Hardback)
No full text2007-09departmental bulletin pape
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