1,721,294 research outputs found
A Pair Spectrometer for Nuclear Astrophysics Applications
No full textA spectrometer using two fully depleted silicon detectors (in a ΔE − E configuration) has been realized with the goal of directly measuring the production rate of the e+e− pairs emitted in E0 transition of the 12C(α, γ)16O reaction. This is a key reaction in nuclear astrophysics, which takes place\ud
during the He burning stage of red giant stars and thus regulates the carbon/oxygen abundance in the Universe. In particular, we are interested to determine the e+e− pair cross section at energies below 2 MeV, where theoretical\ud
estimate is possible by using the R- matrix extrapolation. Experimental e+e− pair emission data at this energy thus provides a valuable tool to validate such analytical approximate scheme. Resolution and efficiency measurements\ud
have been carried out using 241Am +239 Pu source, the α source, 32P,207 Bi β sources and the 19F(p, α)16O fusion evaporation reaction below 1 MeV on beam reaction at CIRCE tandem accelerator (Caserta, Italy).\ud
The results obtained approve to be in good agreement with our GEANT4 simulation
Structural Refinement of Ni doped LiFePO4 Materials used in Energy Storage Devices
No full textNew materials with advanced functional properties are needed to improve the performances of energy storage devices like rechargeable lithium ion (Li-ion) batteries, currently used in a variety of applications. In this work\ud
we have concentrated our efforts in the synthesis and detailed characterization of promising cathode materials such as metal-doped LiFePO4 Olivines.\ud
We have succesfully synthesized Ni-doped solid solutions LiFe1−xNixPO4 (0≥x≤0.15,0.9,1.0) and the novel materials were characterized by elemental analysis and scanning electron microscopy. Some materials were electrochemically\ud
tested by cyclic voltammetry, showing that Ni doping may play a role in reducing electrode polarization increasing slightly the performances in Liion cells at low Ni concentrations x. The solid solutions were deeply studied\ud
by X-ray diffraction (XRD) and X-ray Absorption Spectroscopy (XAS), in order to check modifications of the lattice and of the local structure as well as possible correlations with the functional properties. Rietveld refinement of XRD data showed that Ni doping induces an anisotropic contraction of the unit cell which mainly concerns the volume of the M2 octahedral sites.\ud
Results of both XRD and XAS techniques are consistent and indicates the formation of homogeneous impurity-free solid solutions for x ≤ 0.15, ordering of Li in the (octahedral) M1 site, and of Fe and Ni in the M2 site of the olivine structure. Ni doping is found to induce an anisotropic shrinking of the unit cell with both Fe and Ni six-coordinated with oxygens, occupying distorted octahedral sites. The local structure measured by XAS shows that\ud
average Fe-O and Ni-O distances do not change appreciably with Ni doping indicating that the reduction of cell size is mainly associated with the presence of shorter Ni-O distances at M2 sites. Possible connections among the\ud
presence of a distribution of distorted octahedra of different size in the structure and different electrochemical performances of the material as a function\ud
of doping are briefly discussed.\ud
Most results of this work, obtained in the framework of an extended collaboration, were published on an international scientific journal (Journal of Power Source, vol. 213, 287-295 (2012
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
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
The effect of electric and chiral magnetic conductivities on azimuthally fluctuating electromagnetic fields and observables in isobar collisions
Get PDFWe study the space-time evolution of electromagnetic fields along with the
azimuthal fluctuations of these fields and their correlation with the initial
matter geometry specified by the participant plane in the presence of finite
electric and chiral magnetic
conductivities in Ru+Ru and Zr+Zr collisions at GeV. We
observe the partially asymmetric behavior of the spatial distributions of the
electric and magnetic fields in a conducting medium when compared to the
Lienard-Wiechert (L-W) solutions, and deceleration of the decay of the fields
is observed in both isobar collisions. While studying the correlation between
the magnetic field direction and the participant plane, we see the sizeable
suppression of the correlation in the presence of finite conductivities when
compared to the L-W case, reflecting the importance of taking into account the
medium properties such as conductivities while calculating the magnetic field
induced observable quantities
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
- …
