1,721,008 research outputs found
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
Variations on the Author
Get PDF“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
Get PDFWe 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
Observations and analysis of water in molecular outflows and shocks
No full textThis thesis describes observations and analysis of molecular outflows from young stellar objects. The observations using the Odin satellite are described in Paper I, where a non-LTE radiative transfer code has been used to estimate the ortho-water abundance in seven molecular outflows and one super-nova remnant. Elevated abundances are found in several sources, as expected in continuous type shocks. Also a correlation between the maximum outflow velocity and the abundance is found.
Complementary observations of formyl (HCO+) have been carried out with the Onsala 20 meter antenna. A correlation between formyl and water has previously been observed towards continuum sources in the Milky Way and for that reason we make observations of the sources observed with Odin and proposed for the Herschel Space Observatory.
An Accelerated Lamda Iteration code (ALI) is used to obtain information from observed line profiles. Varying the ortho-water abundance, line profiles are computed for various gas densities and kinetic temperatures. For the source HH54 B, observations of CO and H2O have been made using Odin, SEST and Herschel. A simple model of a curved bowshock fits the observations reasonably well and enables us to determine the kinetic temperature and the density of the source. The ALI code is also used to make predictions for the forthcoming observations with Herschel
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Observations and analysis of water in molecular outflows and shocks
No full textThis thesis describes observations and analysis of molecular outflows from young stellar objects. The observations using the Odin satellite are described in Paper I, where a non-LTE radiative transfer code has been used to estimate the ortho-water abundance in seven molecular outflows and one super-nova remnant. Elevated abundances are found in several sources, as expected in continuous type shocks. Also a correlation between the maximum outflow velocity and the abundance is found. Complementary observations of formyl (HCO+) have been carried out with the Onsala 20 meter antenna. A correlation between formyl and water has previously been observed towards continuum sources in the Milky Way and for that reason we make observations of the sources observed with Odin and proposed for the Herschel Space Observatory. An Accelerated Lamda Iteration code (ALI) is used to obtain information from observed line profiles. Varying the ortho-water abundance, line profiles are computed for various gas densities and kinetic temperatures. For the source HH54 B, observations of CO and H2O have been made using Odin, SEST and Herschel. A simple model of a curved bowshock fits the observations reasonably well and enables us to determine the kinetic temperature and the density of the source. The ALI code is also used to make predictions for the forthcoming observations with Herschel
Water in molecular outflows and shocks: Studies with Odin and Herschel
No full textThis thesis describes observations and analyses of water in molecular outflows from young stellar objects. The abundance of this molecule (with respect to molecular hy- drogen) is deduced from observations carried out with primarily the Odin and Herschel telescopes. The large spatial extents of molecular outflows allow for mapping obser- vations to be done with both facilities, but in addition to this, spectroscopy also allow for the investigation of the kinematics. The observations discussed in this thesis were acquired over the years 2002 to 2011.
In the first appended research paper, observations of 15 different shocked regions are reported. The targets were primarily molecular outflows, but two supernova rem- nants were also observed. This study shows that the water abundance in the gas is elevated in the presence of shock waves. Furthermore, the water abundance seems to correlate with the maximum velocity of the shocked gas.
In the second paper, previously published observations of the Herbig-Haro object HH 54 are followed up, using APEX, Odin and Herschel. In this work we investigate the relative cooling contribution from CO and H2O and we compare the results with most recent shock models. CO dominates the cooling and we conclude that planar shock models do not explain the observations satisfactorily. Instead we find that a curved geometry can completely account for the observed line profile shapes in the two species. The inferred water abundance is lower than what was previously expected.
In the third paper, Herschel mapping observations of VLA 1623 are presented. The ground-state transitions of o-H2O were mapped using the HIFI and PACS instruments but also higher energy transitions were observed towards selected positions in the out- flow lobes. The observed H2O(110 −101) line profiles show a variety of shapes over the observed region and also from this work, we conclude that the water abundance is lower than expected. In addition to this, it is now clear that the regions responsible for the emission in water are warmer than the regions traced by CO. A comparison with H2 data obtained with Spitzer allows us to estimate the physical parameters of the flow. This leads us to conclude, that it does not matter which molecular tracer we use when we infer the force and the power of the VLA 1623 outflow. The analysis is followed up in a letter where we include also the L 1448 and L 1157 outflows
Water in molecular outflows and shocks: Studies with Odin and Herschel [Elektronisk resurs]
No full textThis thesis describes observations and analyses of water in molecular outflows from young stellar objects. The abundance of this molecule (with respect to molecular hy- drogen) is deduced from observations carried out with primarily the Odin and Herschel telescopes. The large spatial extents of molecular outflows allow for mapping obser- vations to be done with both facilities, but in addition to this, spectroscopy also allow for the investigation of the kinematics. The observations discussed in this thesis were acquired over the years 2002 to 2011.In the first appended research paper, observations of 15 different shocked regions are reported. The targets were primarily molecular outflows, but two supernova rem- nants were also observed. This study shows that the water abundance in the gas is elevated in the presence of shock waves. Furthermore, the water abundance seems to correlate with the maximum velocity of the shocked gas.In the second paper, previously published observations of the Herbig-Haro object HH 54 are followed up, using APEX, Odin and Herschel. In this work we investigate the relative cooling contribution from CO and H2O and we compare the results with most recent shock models. CO dominates the cooling and we conclude that planar shock models do not explain the observations satisfactorily. Instead we find that a curved geometry can completely account for the observed line profile shapes in the two species. The inferred water abundance is lower than what was previously expected.In the third paper, Herschel mapping observations of VLA 1623 are presented. The ground-state transitions of o-H2O were mapped using the HIFI and PACS instruments but also higher energy transitions were observed towards selected positions in the out- flow lobes. The observed H2O(110 −101) line profiles show a variety of shapes over the observed region and also from this work, we conclude that the water abundance is lower than expected. In addition to this, it is now clear that the regions responsible for the emission in water are warmer than the regions traced by CO. A comparison with H2 data obtained with Spitzer allows us to estimate the physical parameters of the flow. This leads us to conclude, that it does not matter which molecular tracer we use when we infer the force and the power of the VLA 1623 outflow. The analysis is followed up in a letter where we include also the L 1448 and L 1157 outflows
- …
