1,720,968 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
Beating spatio-temporal coupling: Implications for pulse shaping and coherent control experiments
Get PDFDiffraction of finite sized laser beams imposes a limit on the control that can be exerted over ultrafast pulses. This limit manifests as spatio-temporal coupling induced in standard implementations of pulse shaping schemes. We demonstrate the influence this has on coherent control experiments that depend on finite excitation, sample, and detection volumes. Based on solutions used in pulse stretching experiments, we introduce a double-pass scheme that reduces the errors produced through spatio-temporal coupling by at least one order of magnitude. Finally, employing single molecules as nanoscale probes, we prove that such a double pass scheme is capable of artifact-free pulse shaping at dimensions two orders of magnitude smaller than the diffraction limit.Fil: Brinks, Daan. Institut de Ciencies Fotoniques; EspañaFil: Hildner, Richard. Institut de Ciencies Fotoniques; España. University of Bayreuth; AlemaniaFil: Stefani, Fernando Daniel. Institut de Ciencies Fotoniques; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; ArgentinaFil: Van Hulst, Niek F.. Universidad de Barcelona. Institució Catalana de Recerca i Estudis Avançats; España. Institut de Ciencies Fotoniques; Españ
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
Nanoscale Coherent Control. Ultrafast dynamics of single molecules, individual light harvesting complexes and discrete nanoantennas at room temperature.
Get PDFUltrafast pulses allow observation of molecular dynamics with femtosecond time resolution through pump probe
experiments. However, averaging over an ensemble of molecules tends to wash out phase sensitive information, necessary
to probe quantum effects, due to the intrinsic inhomogeneity in molecular conformations, orientations and interactions that
lead to unique potential energy landscapes for each molecule.
It is therefore important to go beyond the ensemble average when looking at quantum dynamics of organic systems at room
temperature, and resolve the behaviour of specific molecules on an individual basis.
In this thesis, we show the creation, manipulation and observation of ultrafast coherent effects in single molecules at room
temperature, and resolve a certain measure of environmental influence on the specific dynamics of each molecule. Moreover,
we apply this insight to investigate a functional light harvesting biosystem, and lay the basis for a technique that has the time
and space resolution required to observe these systems in vivo.
In chapter 1, we introduce the concepts and techniques the research in this thesis is built on.
In chapter 2, we treat the possibility of controlling ultrafast pulses at the high-NA diffraction limit, and come to conclusions
about the procedure to follow there that hold for all pulse-shaping experiments. We show in proof of principle experiments
that we can control the ultrafast characteristics of optical pulses in nanometric excitation volumes.
In chapters 3 and 4 we report the creation, detection and control of ultrafast quantum dynamics in single organic molecules at
room temperature. We show that manipulation of superposition states is possible in these systems within a coherence
dephasing time of ~50 fs. This leads to the first observation of rabi-oscillations in room temperature single molecules, to
ultrafast operation of an organic qubit, and to the creation of non-stationary superposition states (vibrational wavepackets).
We probe the influence of the local environment on the composition and dynamics of these wavepackets and show we can
optimize the state preparation protocol for each individual molecule in its own nanoenvironment, leading to high fidelity
coherent control. In these chapters we lay out the proof of principle work of detecting the quantumdynamics of a complex
system in interaction with its environment at room temperature.
In chapter 5 we discuss application of these techniques to the investigation of long lived coherence in photosynthetic
systems. We show that electronic coherence between different rings of the LH2 system persists to time scales of 100s of
femtoseconds at room temperature. Moreover we show that the energy transfer pathways in LH2 adapt to environmentally
induced changes in the molecule and that the nature of the transfer remains coherent for each pathway, providing strong
evidence that coherent energy transfer is the optimum process for energy transfer in photosynthesis.
Finally, in chapter 6 we take the technical development one step further and report on the creation of a framework based on
plasmonic antennas that allows for control of the amplitude-phase characteristics in nanometric sized hotspot fields. We
show for the first time that the ultrafast characteristics of plasmonic hotspots can directly be engineered through design of the
plasmonic system and experimentally demonstrate two much-anticipated examples: a sub-diffraction resolution phase
shaper and an ultrafast plasmonic switch for pump probe experiments.
The results presented in this thesis form the first creation and observation of ultrafast coherent dynamics in individual
molecular systems at room temperature. This is a necessary step to be able to do true quantum tomography in complex
systems, resolve the influence of the environment on molecular dynamics, and investigate the physics that determines
evolutionary optimization and functionality in biomolecules.DOCTORAT EN FOTÒNICA (Pla 2007
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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