186,376 research outputs found
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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
Functional connectivity between the dorsolateral prefrontal cortex and the ipsilateral primary motor cortex
No full textIntroduction
The prefrontal cortex has a crucial role in higher cognitive functions and various line of evidence point to a tight connectivity network between the dorsolateral prefrontal cortex (DFLPC, BA46) and the ipsilateral primary motor cortex (M1).
Objectives
The main objective of this study was to determine the precise timing and the spatial specificity of this functional connectivity during the performance of a choice-reaction task.
Materials and methods
Twin coil, neuronavigated transcranial magnetic stimulation (TMS) was used during the performance of a choice-reaction task. By varying the time of stimulation (ISI 6, 8, 12 ms) after a cue (stimulus-onset asynchronies 75, 100, 125 ms) which signalled either a free selection or specified finger movement, the interactions between BA46 and M1 could be investigated. Furthermore, we tested whether the influence of a BA46 stimulation is specific to muscles involved in the task or not by investigating task involved and not-involved muscles.
Results
Our results indicate that in unselected muscles during trials with externally specified responses, stimulation of BA46 increases excitability of M1 at a SOA of 75 ms. In freely selected trials, stimulation of BA46 at a SOA of 100 ms facilitates M1 excitability. Our data suggested that the main effects occured at a ISI of 12 ms pointing to an indirect connectivity. In selected muscles this differences disappeared and the M1 output to these muscles was influenced by whether or not the muscle was selected or not. No effects could be observed when BA9 was stimulated.
Conclusion
The present results suggest that there is anatomically specific functional connectivity between left BA46 and left M1 during free and specified selection of a movement. This is the first study allowing to draw conclusions about the precise timing of this important functional connectivity
In situ generation of the Ohira-Bestmann Reagent from stable sulfonyl azide:scalable synthesis of alkynes from aldehydes
No full textWe report an improved method for in situ generation of the Ohira-Bestmann reagent. Using the recently reported bench stable imidazole-1-sulfonyl azide as diazotransfer reagent, this new method represents a safe and scalable approach for the transformation of aldehydes into terminal alkynes. Furthermore the method features easier work-up compared to the existing in situ protocol due to increased aqueous solubility of waste products.</p
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
Deacylative 1,6-addition of Bestmann-Ohira reagent to p-quinone methides for the synthesis of α-diazo-β-diarylphosphonates and cis-stilbenyl phosphonates
No full textThe role of Bestmann-Ohira Reagent (BOR) as a conjugate addition partner is reported for the first time. Deacylation of BOR in the presence of ethanolic KOH and 1,6-addition of the resulting diazophosphonate anion to p-quinone methides (PQMs) provides β-disubstituted α-diazophosphonates in good to excellent yields in most cases. Such 1,6-adducts further undergo Rh-catalyzed elimination of the diazo group and 1,2-migration of the phenolic group to afford cis-stilbenylphosphonates with high E-selectivity. The migration of the phenolic group presumably takes place via a spirocyclopropane intermediate derived from the Rh-carbenoid
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
Muscle and Timing-specific Functional Connectivity between the Dorsolateral Prefrontal Cortex and the Primary Motor Cortex
No full textThe pFC has a crucial role in cognitive control, executive function, and sensory processing. Functional imaging, neurophysiological, and animal studies provide evidence for a functional connectivity between the dorsolateral pFC (DLPFC) and the primary motor cortex (M1) during free choice but not instructed choice selection tasks. In this study, twin coil, neuro-navigated TMS was used to examine the precise timing of the functional interaction between human left DLPFC and ipsilateral M1 during the execution of a free/specified choice selection task involving the digits of the right hand. In a thumb muscle that was not involved in the task, a conditioning pulse to the left DLPFC enhanced the excitability of the ipsilateral M1 during free selection more than specified selection 100 msec after presentation of the cue; the opposite effect was seen at 75 msec. However, the difference between free and externally specified conditions disappeared when a task-specific muscle was investigated. In this case, the influence from DLPFC was dominated by task involvement rather than mode of selection, suggesting that other processes related to movement execution were also operating. Finally, we show that the effects were spatially specific because they were absent when an adjacent area of DLPFC was stimulated. These results reveal temporally and spatially selective interactions between BA 46 and M1 that are both task and muscle specific
Dr. Edward P. Wimberly, ITC, July 2011
No full textThis video is a conversation with Dr. Edward P. Wimberly. Dr. Wimberly talks about his book, "No Shame in Wesley's Gospel: A Twenty-First Century Pastoral Gospel". Brad Ost, AUC Woodruff Library, is the interviewer
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