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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
Spatially confined responses of mouse visual cortex to intracortical magnetic stimulation from micro-coils
No full textObjective. Electrical stimulation via microelectrodes implanted in cortex has been suggested as a potential treatment for a wide range of neurological disorders. Despite some success however, the effectiveness of conventional electrodes remains limited, in part due to an inability to create specific patterns of neural activity around each electrode and in part due to challenges with maintaining a stable interface. The use of implantable micro-coils to magnetically stimulate the cortex has the potential to overcome these limitations because the asymmetric fields from coils can be harnessed to selectively activate some neurons, e.g. vertically-oriented pyramidal neurons while avoiding others, e.g. horizontally-oriented passing axons. In vitro experiments have shown that activation is indeed confined with micro-coils but their effectiveness in the intact brain of living animals has not been evaluated. Approach. To assess the efficacy of stimulation, a 128-channel custom recording microelectrode array was positioned on the surface of the visual cortex (ECoG) in anesthetized mice and responses to magnetic and electric stimulation were compared. Stimulation was delivered from electrodes or micro-coils implanted through a hole in the center of the recording array at a rate of 200 pulses per second for 100 ms. Main results. Both electric and magnetic stimulation reliably elicited cortical responses, although activation from electric stimulation was spatially expansive, often extending more than 1 mm from the stimulation site, while activation from magnetic stimulation was typically confined to a similar to 300 mu m diameter region around the stimulation site. Results were consistent for stimulation of both cortical layer 2/3 and layer 5 as well as across a range of stimulus strengths. Significance. The improved focality with magnetic stimulation suggests that the effectiveness of cortical stimulation can be improved. Improved focality may be particularly attractive for cortical prostheses that require high spatial resolution, e.g. devices that target sensory cortex, as it may lead to improved acuity.
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
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
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Mechanistic Electrochemical Characterization of Novel Microelectrode Arrays and Their Application in Mapping Brain Activity across Species and Humans
Get PDFElectrocorticography (ECoG) arrays are used in clinical mapping for neurosurgical resection and hold the promise for less damaging brain-machine interfaces. Current clinical ECoG electrodes face physical limits to the number of contact sites, spatial resolution (centimeter scale), and contact diameter (millimeter scale), and thus cannot resolve the dynamically changing neural activity over sub-millimeter scales . In addition to these practical limitations, current clinical electrode arrays are constrained to non-conformal electrode-carriers/substrates and to less-optimal metal electrochemical interfaces. Increasing the flexibility of clinical electrodes may lead to higher signal-to-noise ratios as well as higher spatial specificity and this also requires overcoming substantial physical barriers due to the compromised metal electrochemical interface properties.The objectives of this thesis, described in seven chapters, are to develop high performance, safe, and durable neural electrode interfaces to yield stable, high signal-to-noise ratio cortical recordings in animal models as well as in humans. In the second chapter, we demonstrate that sterilization of PEDOT:PSS electrophysiology devices can be performed using an autoclave. We find that autoclaving is a viable sterilization method, leaving morphology unaltered and causing only minor changes in electrical properties. These results pave the way for the widespread utilization of PEDOT:PSS electrophysiology devices in the clinic.In the third chapter, we translate the use of robust PEDOT:PSS microelectrode arrays for safe intraoperative monitoring of the human brain. PEDOT:PSS micro-electrodes measured significant differential neural modulation under various clinically relevant conditions. We report the first evoked (stimulus-locked) cognitive activity with changes in amplitude across pial surface distances as small as 400 μm, potentially enabling basic neurophysiology studies at the scale of neural micro-circuitry.In the fourth and fifth chapters, we present the first systematic study of scaling effects on the electrochemical properties of Pt and Au metallic and PEDOT:PSS organic electrodes from neural recording and stimulation perspectives. PEDOT:PSS coating reduced the impedances of metallic electrodes by up to 18X. The overall reduced noise of the PEDOT:PSS microelectrodes enable a lower noise floor for recording action-potentials with high fidelity. We observed a substantial enhancement in charge injection capacity up to 9.5X for PEDOT:PSS microelectrodes compared to metal ones and 88% lower required power for injecting the same charge density. These results permit quantitative optimization of contact material and diameter for different ECoG applications.In the sixth chapter, We report an effective method of mechanically anchoring the PEDOT within the Au nanorod (Au-nr) structure and demonstrate that it provides enhanced adhesion and overall PEDOT layer stability under various electrochemical (charge injection) and In vivo stability tests. In the seventh chapter, we report the fabrication of pure Pt nanorods (PtNRs) by utilizing low-temperature selective dealloying to develop scalable and biocompatible 1D platinum nanorod (PtNR) arrays that exhibit superb electrochemical properties at various length scales for high-performance neurotechnologies. PtNR arrays record brain activity with cellular resolution from the cortical surfaces in birds, mice, and non-human primates; demonstrating the PtNR microelectrode system as a robust system for high performance and stable neural electrode interfaces
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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