1,720,967 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Pushing the limits: mass measurements of neutron deficient lanthanides at the proton drip line & ion trapping advancements using printed circuit boards
No full textAccurate mass measurements of proton-rich elements are essential for research in
nuclear structure. In the context of the light lanthanide region, nuclear properties
are significantly affected by substantial beta-decay Q-values, as well as low or
negative proton separation energies, and the confining effects of the Coulomb
barrier. Furthermore, precise mass measurements facilitate the calculation of
important quantities, including proton and neutron separation energies, thereby
providing valuable insights into phenomena such as proton radioactivity, two-proton
radioactivity, and exotic pairing phenomena.
Utilising high-resolution mass spectrometry at the GSI FRS-IC, 14 new isotopes
have been identified along the proton drip line, accompanied by 7 newly refined
mass uncertainties in the region spanning Barium (Ba) to Terbium (Tb) as
observed during the measurement campaign documented in S482. Simultaneous
measurements of over thirty-five nuclides were conducted, encompassing extensive
areas of the nuclide chart with stopped or thermalised nuclides. These findings,
along with the innovative technical methodologies employed, yield significant
insights into nuclear structure and facilitate the tracking of the proton drip line
between 100Sn and 150Lu.
To further enhance the capabilities of high-resolution mass spectrometry, a novel
approach entailing the utilisation of printed circuit boards (PCB-RFQ) has been
developed, constructed, and characterised. The PCB-RFQ system possesses the
ability to supplant multiple sections of experimental beam time due to its capacity
to achieve unity transport efficiency and generate ion bunches for an MR-TOFMS,
supplemented by a dedicated prototype for an injection trap system. This
process is accomplished by generating ion bunches of 133Cs with a time duration
of 2.6 (1) ns and a moderate energy spread of 20 eV, in contrast to typical spreads
of approximately 9 ns. This study elucidates the design and construction of the
PCB-RFQ system while also presenting investigations into its performance
Pilot Experiments with Relativistic Uranium Projectile and Fission Fragments Thermalized in a Cryogenic Gas-filled Stopping Cell
No full textVariations on the Author
Full text link“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
Pilotexperimente mit in einer kryogene gasgefüllten Stoppzelle thermalisierten relativistischen Projektil- und Spaltfragmenten
Full text linkHigh precision experiments and decay spectroscopy of exotic nuclei are of great interest for nuclear structure and nuclear astro-physics. They allow for studies of the nuclear structure far from stability, test of fundamental interactions and symmetries and give important input for the understanding of the nuclear synthesis in the universe. In the context of this work a second generation stopping cell for the low energy branch of the Super-FRS was commissioned at the FRS at GSI and significant improvements were made to the device. The prototype stopping cell is designed as a cryogenic stopping cell (CSC), featuring enhanced cleanliness and high area density. The CSC was brought into full operation and its performance characteristics were investigated including the maximal area density, extraction times, cleanliness and extraction efficiencies. In three commissioning experiments at the current GSI FRS facility in 2011, 2012 and 2014 up to 22 isotopes from 14 elements produced by in-flight projectile fragmentation and fission of 238-U could be thermalized and extracted with high efficiency. For the first time projectile and fission fragmentation produced at 1000 MeV/u could be thermalized in a stopping cell and provided as a low-energy beam of high brilliance for high precision experiments. The technical improvements of the CSC, such as an improved RF carpet, new cryocooler-based cooling system, a monitoring system of the cleanliness and the high density operation, made it possible to thermalize heavy 238-U projectile fragments with total efficiencies of about 20% in the 2014 experiment. In addition the improvements lead to an increase in the stability and reliability of the CSC and the performance of the CSC during online experiments at the FRS Ion Catcher showed that the utilized techniques are ready for the final CSC for the low-energy branch of the Super-FRS at FAIR.The CSC was operated with an area density of up to 6.3 mg/cm^2 helium during online experiments, which is about three times larger than any stopping cell, using RF structures for the extraction of ions, has demonstrated. The area density and therefore the stopping power of the CSC is limited by the differential pumping. To overcome this limitation the CSC was tested with neon as a stopping gas with area densities of up to 11.3 mg/cm^2 helium equivalent, demonstrating a unprecedented area density for stopping cells based on RF structures. The RF carpet performed reliably and its potential for the future FAIR stopping cell was shown. During the experiments at GSI the mean extraction time of 221-Ac ions from the CSC to a silicon surface detector was measured, it amounts to 24 ms. This value is well in agreement with offline measurements using a pulsed 223-Ra recoil ion source. The combination of a high density stopping cell with high total efficiencies and a non-scanning high-resolution mass spectrometer can be used as an independent identification detector for exotic nuclei by their mass, allowing a recalibration of the in-flight detectors of any fragment separator. As a proof-of-principal experiment the CSC and a MR-TOF-MS have been used as a mass tagger for the FRS at GSI. 134-I ions were produced by in-flight fission from an 238-U primary beam at 1000 MeV/u and identified by the mass tagger. The new method does not rely on specific decay properties and therefore allows a recalibration of the fragment separator independent of the fragment and can also be used with stable nuclides. The usage of the CSC and a MR-TOF-MS will allow fast recalibration and a more effective usage of the limited amount of beam time for all experiments with exotic nuclei even in the case the nuclide of interest is not clearly identified by the in-flight detection scheme.With the CSC low energy experiments such as high-precision mass measurements and decay spectroscopy were made possible, the half lifes of 221-Ac and 223-Th have been measured, alpha spectroscopy of short lived nuclides (220-Ra, 17.9 ms) were performer. Due to the selective stopping of only one nuclide in the stopping cell the characteristic alphas of 24 nuclides were measured with almost zero background and their Q-alpha-values could be confirmed.Following a new approach, data from gamma spectroscopy, alpha spectroscopy and high resolution mass spectrometry of 211-Po were combined to study the angular momentum distribution arising from in-flight projectile fragmentation. This was possible by measuring the isomer ratio of 211-Po and comparing it to current predictions from the two-step abrasion-ablation model. It was shown that current models can not describe the angular momentum distribution of in-flight projectile fragmentation and that new measurements of isomer ratios are required in order to understand the angular momentum distribution.Im Rahmen dieser Arbeit wurde eine kryogene Stoppzelle (CSC) vollständig in Betrieb genommen, weiterentwickelt und ihrer Leistungsfähigkeit untersucht, welche die Vorteile der ISOL Methode an der in-flight Beschleunigeranlage GSI zur Verfügung stellt. Die kryogene Stoppzelle wurde während drei Teststrahlzeiten in 2011, 2012 und 2014 an der GSI Beschleunigeranlage als Teil des FRS Ion Catcher Experiments erprobt. Erstmals konnten relativistisch produzierter 238-U Projektil- und Spaltfragmente mit hoher Gesamteffizienz abgestoppt, thermalisiert und zu einem niederenergetischen Ionenstrahl geformt werden. Es wurden vielfältige Verbesserungen an dem System durchgeführt, z.B. die Überarbeitung der RF-Carpet Elektronik sowie die Umstellung der Kühlung des Systems von flüssigem Stickstoff auf einen externen Kryostaten. Alle diese Maßnahmen haben zu einer Steigerung des Leistungsvermögens (Stopp- und Extraktionseffizienz) und der Zuverlässigkeit der CSC geführt. Eine verbesserte Stabilität des Betriebs der Stoppzelle erlaubten erfolgreiche Experimente am FRS Ion Catcher.Die Stoppzelle wurde dabei mit einer Flächendichte von bis zu 6.3 mg/cm^2 Helium betrieben. Das ist mehr als das Dreifache, was bisher mit einer RF-basierenden Stoppzelle erreicht werden konnte. Durch die hohe Flächendichte ließen sich Stoppeffizienzen von bis zu 27% für 223-Th Projektilfragmente erzielen. Durch die Verbesserungen der Sauberkeit der kryogenen Stoppzelle ergaben sich sehr hohe Extraktionseffizienzen von ungef"ahr 80%. Weiterhin konnten die exotischen Kerne als reine Strahlen, teilweise auch als doppelt geladene Ionen und ohne Addukte extrahiert werden. Dadurch konnten sie erfolgreich für hochauflösende Massenspektroskopie und Zerfallsspektroskopie bereit gestellt werden. Aus der Kombination von hoher Stopp- und Extraktionseffizienz ergaben sich Gesamteffizienzen von bis zu 20%.Die Flächendichte und somit das Stoppvermögen der CSC war durch das differentielle Pumpen limitiert. Um das Verhalten des RF-Carpets bei höheren Dichten zu testen, wurde Neon als Stoppgas eingesetzt. Der Einsatz von Neon erlaubte den erfolgreichen Betrieb bei Flächendichten, die für Helium dem von 11.3 mg/cm^2 entsprechen. Dies entspricht fast dem Sechsfachen, was mit RF-basierten Stoppzellen bisher erreicht werden konnte. Der Betrieb des RF-Carpets bei diesen hohen Dichten zeigt das Potential der Technik für den Einsatz am zukünftigen LEB des S-FRS. Weiterhin ermöglicht ein Betrieb der kryogenen Stoppzelle mit Neon eine Steigerung des Stoppvermögens, was in der Zukunft bei Experimenten zur Isotop- oder Isomersuche eine Effizienzsteigerung bewirken kann.Die Kombination aus einer Stoppzelle mit einer hohen Flächendichte und einem sensitiven, nicht scannenden, hochauflösenden Multireflektions Flugzeitmassenspektrometer (MR-TOF-MS) erlaubt eine direkte Identifikation von exotischen Kernen anhand ihrer Masse. Der Einsatz der CSC und eines MR-TOF-MS als sogenannter Mass-Tagger, ermöglicht eine Identifikation der Ionen und somit eine Kalibration der Detektoren zur Teilchenidentifikation Im-Fluge am FRS. Diese Methode ist deutlich flexiebler als die bisherigen Verfahren und erlaubt eine viel effizientere Nutzung von Strahlzeiten für fast alle Experimente am FRS und zukünftigem Super-FRS, da sie nicht auf Zerfällen basiert und somit für alle Nuklide verwendet werden kann. Weiterhin können dadurch auch Nuklide identifiziert werden, die in der Identifikation Im-Fluge nicht aufgelöst werden können. Das Konzept wurde erfolgreich mit der Identifikation von 134-I am FRS Ion Catcher gezeigt.Das hohe Leistungsvermögen erlaubte eine Vielzahl an Messungen an über 22 Isotopen von 14 Elementen. Unter anderem wurde die Lebensdauer von 221-Ac und 223-Th gemessen sowie Experimente mit extrem kurzlebigen Nukliden durchgeführt (220-Ra, 17.9 ms Halbwertszeit). Hierbei wurde selektives Abstoppen von Nukliden in der Stoppzelle als zusätzliche Separation nach der Separation Im-Fluge eingesetzt. Dies erlaubte Alpha Zerfallsspktroskopie mit fast isotopenreinen niederenergetischen Ionen und somit die Bestimmung der Q-alpha Energien von 19 Nukliden. Die Alpha Energien von 24 Zerf"allen konnten best"atigt und der Fehler des Q-alpha Wert von 221-Ac verbessert werden.Weiterhin erlaubte die kryogene Stoppzelle Experimente zum Isomer zu Grundzustandsverhältnis von 211-Po und somit eine ÜberprÜfung der Drehmomentverteilung bei der Fragmentation von 238-U bei relativistischen Energien. Das Isomerenverhältniss wurde mit Vorhersagen verglichen. Dies zeigte, dass aktuelle Modelle zur Bevölkerung von angeregten Kernzuständen dieses nicht ausreichend beschreiben und Abweichungen bis zu einem Faktor 4 bis 10 vorliegen können. Modelle, die eine empirische Verbreiterung der Drehmomentverteilung während der Kernabregungsphase des Fragmentationsporzesses annehmen, beschreiben die gemessenen Isomer zu Grundzustandsverhältnis deutlich besser
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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