130,377 research outputs found
Evaluating resilience of tree communities in fragmented landscapes: linking functional response diversity with landscape connectivity
No full textAim Multiple agents of change increasingly impact functioning of forest ecosystems, for which management plans often ignore how local disturbances and habitat fragmentation jointly operate on ecological resilience at different scales. We examined sensitivity of functional response diversity (FD ) to variation in species diversity to predict ecological resilience to future disturbances across tree communities and evaluated the role of landscape connectivity in maintaining ecological resilience at the landscape scale. Location Centre‐du‐Quebec, Quebec, Canada. Methods We inventoried private forests and calculated FD and community‐weighted means to determine the extent to which forest‐use intensity affects ecological resilience. Subsequently, we constructed a regional map of FD , from which a spatial network was extracted. To assess potential impacts of fragmentation in maintaining FD at the landscape scale, we examined how the functional connectivity of the landscape, measured by the probability of connectivity (PC ), varied across a range of maximum seed dispersal distances. Lastly, we evaluated the importance of individual forest fragments in maintaining landscape FD by measuring the connectivity fractions of PC . Results Across tree communities, ecological resilience was low as FD increased sharply with species diversity. Forests with high FD were dominated by species with trait values associated with greater resilience to future anthropogenic disturbances rather than to future climate change. FD was maintained across the landscape by forest fragments acting as intermediate stepping stones in the transfer of seeds. Main conclusions We employed a novel approach based on spatial networks to extend the functional diversity concept from the local to the landscape scale. Our results suggest that seed dispersal over sufficiently large distances can maintain ecological resilience in fragmented landscapes and buffer changes in local‐scale FD . Otherwise, FD is maintained by local processes, meaning that ecological resilience of isolated forest fragments depends strongly on land use type and intensity
Improved potentiometric SECM imaging of galvanic corrosion reactions
No full textThe galvanic corrosion of Zn-Cu systems has been monitored in situ using scanning electrochemical microscopy in the potentiometric mode. Here, the initial studies performed using double-barrel microelectrodes for the simultaneous detection of local pH and Zn ion concentration changes in single lines scans, have been extended to the obtention of 2-D maps of Cu2+ and Zn2+ ions. The construction and calibration of a novel Cu2+ ion selective microelectrode is reported. New scanning algorithms and data evaluation tools have been explored for faster acquisition rates than those limited by the time constants associated to potentiometric response
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
Multi-barrel electrodes containing an internal micro-reference for the improved visualization of the galvanic corrosion of magnesium using potentiometric SECM
No full textSimultaneous monitoring of pH and Mg2+ distributions above AZ63 magnesium alloy, either
spontaneously corroding or galvanically coupled with iron, was achieved using SECM in the
potentiometric operation. By introducing an internal micro-reference electrode in a multi-barrel
arrangement of the ion-selective microelectrode used as scanning probe, superior performance
was achieved compared to conventional single-barrel and double-barrel assemblies. In this way,
the impact of the overestimated acidification accompanying metal dissolution using conventional
tips was established from model experiments using non ion-sensitive open micropipettes and pH
antimony microelectrodes. It is shown that the simultaneously acquired pH and pMg maps
provide complementary information on the spontaneous and galvanic corrosion of AZ63
magnesium allo
A novel scanning electrochemical microscopy strategy for the investigation of anomalous hydrogen evolution from AZ63 magnesium alloy
No full textThe evolution of hydrogen gas from corroding magnesium arises not exclusively from the
cathodic half-cell reaction due to the consumption of the electrons released by the dissolving
metal, but anodized magnesium generates significant amounts of H2 gas as well. In addition,
the increase of the anodic overpotential enhances the rate of hydrogen gas generation.
Therefore, spatially-resolved detection of the actual sites for hydrogen evolution related to
anodically-activated sites is attempted using scanning electrochemical microscopy (SECM).
This work describes a new experimental procedure for SECM based on a three-step (off-onoff)
anodization operation sequence that was designed to obtain new insights into the behavior
of magnesium and magnesium alloys when they are subjected to anodic polarization. Results
obtained with scanning electrochemical microscopy (SECM) and scanning vibrating electrode
technique (SVET) experiments presented here demonstrate the catalytic properties of the
magnesium-oxide film for the hydrogen-evolution reactio
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