187,838 research outputs found
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Ulysses spacecraft in situ detections of cometary dust trails
No full textThe Ulysses spacecraft was launched in 1990 and, after a Jupiter swing-by in 1992, became the first interplanetary spacecraft orbiting the Sun on a highly inclined trajectory with an inclination of 79 ∘ . The spacecraft was equipped with an impact ionization dust detector which provided 17 years of in situ dust measurements in interplanetary space from 1990 to 2007. Cometary meteoroid streams (also referred to as trails) exist along the orbits of comets, forming fine structures of the interplanetary dust cloud. We use the Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model (Soja RH et al . 2015 Characteristics of the dust trail of 67P/Churyumov-Gerasimenko: an application of the IMEX model. Astron. Astrophys. 583 , A18. (doi: 10.1051/0004-6361/201526184 )) to predict cometary stream traverses by Ulysses and re-analyse the Ulysses dust dataset in order to identify impacts of cometary stream particles detected during such trail traverses. We identify 19 particles compatible with three Ulysses trail traverses on 12 March 1995, 25–27 April 2001 and 16–19 May 2001. The particle origin is compatible with up to five comets, i.e. 10P/Tempel 2, 146P/Shoemaker-LINEAR, 267P/LONEOS and possibly 45P/Honda-Mrkos-Pajdušáková and P/1999 RO28 (LONEOS). We find a dust spatial density in these trails of approximately 2 − 7 ⋅ 10 − 8 m − 3 . The radii of the detected cometary stream particles derived from the dust instrument calibration are in the micrometre range. The in situ analysis of meteoroid trail particles in space, which can be traced back to their source bodies, opens a new opportunity for remote compositional analysis of comets and asteroids without the necessity to send a spacecraft to or even land on these celestial bodies, opening new opportunities for future space missions equipped with in situ dust analyzers. This article is part of the theme issue 'Dust in the Solar System and beyond'
The Network-Extended Mind
No full textWhereas the traditional view in cognitive science has been to view mind and cognition as something that is the result of essentially inner, neural processes, the extended cognition perspective claims that at least some human mental states and processes stem from complex webs of causal influence involving extra-neural resources, most notably the resources of our social and technological environments. In this chapter, we explore the possibility that contemporary and near-future network systems are poised to extend and perhaps transform our human cognitive potential. We also examine the extent to which the information and network sciences are relevant to our understanding of various forms of cognitive extension, particularly with respect to the formation, maintenance and functioning of extended cognitive systems in network-enabled environments. Our claim is that the information and network sciences are relevant on two counts: firstly, they support an understanding of the mechanisms underpinning socially- and technologically-mediated forms of cognitive extension; secondly, they serve to guide and inform engineering efforts that strive to enhance and expand our cognitive capabilities. We discuss the relevance and applicability of these conclusions to current and future research exploring the contribution of network technologies to military coalition operations
Towards spatial assessment of carbon sequestration in peatlands: spectroscopy based estimation of fractional cover of three plant functional types
No full textPeatlands accumulated large carbon (C) stocks as peat in historical times. Currently however, many peatlands are on the verge of becoming sources with their C sequestration function becoming sensitive to environmental changes such as increases in temperature, decreasing water table and enhanced nitrogen deposition. Long term changes in vegetation composition are both, a consequence and indicator of future changes in C sequestration. Spatial continuous accurate assessment of the vegetation composition is a current challenge in keeping a close watch on peatland vegetation changes. In this study we quantified the fractional cover of three major plant functional types (PFTs; Sphagnum mosses, graminoids, and ericoid shrubs) in peatlands, using field spectroscopy reflectance measurements (400–2400 nm) on 25 plots differing in PFT cover. The data was validated using point intercept methodology on the same plots. Our results showed that the detection of open Sphagnum versus Sphagnum covered by vascular plants (shrubs and graminoids) is feasible with an R2 of 0.81. On the other hand, the partitioning of the vascular plant fraction into shrubs and graminoids revealed lower correlations of R2 of 0.54 and 0.57, respectively. This study was based on a dataset where the reflectance of all main PFTs and their pure components within the peatland was measured at local spatial scales. Spectrally measured species or plant community abundances can further be used to bridge scaling gaps up to canopy scale, ultimately allowing upscaling of the C balance of peatlands to the ecosystem level
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
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Strub (Marcel). La ville de Fribourg (Les monuments d'art et d'histoire du canton de Fribourg, t. II). Bâle, Birkhäuser, 1956, in-8°, VIII- 412 p., 437 fig. — Reinle (Adolf). Das Amt Sursee (Die Kunstdenkmäler des Kantons Lu-zern, t. IV)
No full textAubert Marcel. Strub (Marcel). La ville de Fribourg (Les monuments d'art et d'histoire du canton de Fribourg, t. II). Bâle, Birkhäuser, 1956, in-8°, VIII- 412 p., 437 fig. — Reinle (Adolf). Das Amt Sursee (Die Kunstdenkmäler des Kantons Lu-zern, t. IV). In: Bulletin Monumental, tome 115, n°1, année 1957. pp. 68-69
Strub (Marcel). La ville de Fribourg (Les monuments d'art et d'histoire du canton de Fribourg, t. II). Bâle, Birkhäuser, 1956, in-8°, VIII- 412 p., 437 fig. — Reinle (Adolf). Das Amt Sursee (Die Kunstdenkmäler des Kantons Lu-zern, t. IV)
No full textAubert Marcel. Strub (Marcel). La ville de Fribourg (Les monuments d'art et d'histoire du canton de Fribourg, t. II). Bâle, Birkhäuser, 1956, in-8°, VIII- 412 p., 437 fig. — Reinle (Adolf). Das Amt Sursee (Die Kunstdenkmäler des Kantons Lu-zern, t. IV). In: Bulletin Monumental, tome 115, n°1, année 1957. pp. 68-69
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
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