1,721,151 research outputs found
Melting line of calcium characterized by in situ LH-DAC XRD and first-principles calculations
No full textIn this work, the melting line of calcium has been characterized both experimentally, using synchrotron X-ray diffraction in laser-heated diamond-anvil cells, and theoretically, using first-principles calculations. In the investigated pressure and temperature range (pressure between 10 and 40 GPa and temperature between 300 and 3000 K) it was possible to observe the face-centred phase of calcium and to confirm (and characterize for the first time at these conditions) the presence of the body-centred cubic and the simple cubic phase of calcium. The melting points obtained with the two techniques are in excellent agreement. Furthermore, the present results agree with the only existing melting line of calcium obtained in laser-heated diamond anvil cells, using the speckle method as melting detection technique. They also confirm a flat slope of the melting line in the pressure range between 10 and 30 GPa. The flat melting curve is associated with the presence of the solid high-temperature body-centered cubic phase of calcium and to a small volume change between this phase and the liquid at melting. Reasons for the stabilization of the body-centered face at high-temperature conditions will be discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
High-pressure phase transformations in NdVO4 under hydrostatic, conditions: a structural powder x-ray diffraction study
No full textRoom temperature angle dispersive powder x-ray diffraction experiments on zircon-type NdVO4 were performed for the first time under quasi-hydrostatic conditions up to 24.5 GPa. The sample undergoes two phase transitions at 6.4 and 19.9 GPa. Our results show that the first transition is a zircon-to-scheelite-type phase transition, which has not been reported before, and contradicts previous non-hydrostatic experiments. In the second transition, NdVO4 transforms into a fergusonite-type structure, which is a monoclinic distortion of scheelite-type. The compressibility and axial anisotropy of the different polymorphs of NdVO4 are reported. A direct comparison of our results with former experimental and theoretical studies on other rare-earth orthovanadates found in literature highlights the importance of the role played by non-hydrostatic stresses in their high-pressure structural behavior
Variations on the Author
Full text link“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
Full text linkWe 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
Effects of high-pressure on the structural, vibrational, and electronic properties of monazite-type PbCrO4
Full text linkWe have performed an experimental study of the crystal structure, lattice dynamics, and optical properties of PbCrO 4 (the mineral crocoite) at ambient and high pressures. In particular, the crystal structure, Raman-active phonons, and electronic band gap have been accurately determined. X-ray-diffraction, Raman, and optical absorption experiments have allowed us also to completely characterize two pressure-induced structural phase transitions. The first transition is from a monoclinic structure to another monoclinic structure. It maintains the symmetry of the crystal but has important consequences in the physical properties; among others, a band-gap collapse is induced. The second one involves an increase of the symmetry of the crystal, a volume collapse, and probably the metallization of PbCrO 4. The results are discussed in comparison with related compounds, and the effects of pressure in the electronic structure are explained. Finally, the room-temperature equation of state of the low-pressure phases is also obtained. © 2012 American Physical Society.We acknowledge the financial support of the Spanish MCYT through Grants No. MAT2010-21270-C04-01/04 and No. CSD2007-00045. Financial support from the Spanish MICCIN under the Project No. CTQ2009-14596-C02-01 is also acknowledged, as well as from Comunidad de Madrid and European Social Fund: Grant No. S2009/PPQ-1551 4161893 (QUIMAPRES).Bandiello, E.; Errandonea, D.; Martinez-Garcia, D.; Santamaria-Perez, D.; Manjón Herrera, FJ. (2012). Effects of high-pressure on the structural, vibrational, and electronic properties of monazite-type PbCrO4. Physical Review B. 85:24108-1-24108-10. https://doi.org/10.1103/PhysRevB.85.024108S24108-124108-1085Clavier, N., Podor, R., & Dacheux, N. (2011). Crystal chemistry of the monazite structure. Journal of the European Ceramic Society, 31(6), 941-976. doi:10.1016/j.jeurceramsoc.2010.12.019Mooney, R. C. L. (1948). Crystal Structures of a Series of Rare Earth Phosphates. The Journal of Chemical Physics, 16(10), 1003-1003. doi:10.1063/1.1746668Ni, Y., Hughes, J. M., & Mariano, A. N. (1995). Crystal chemistry of the monazite and xenotime structures. American Mineralogist, 80(1-2), 21-26. doi:10.2138/am-1995-1-203Meldrum, A., Boatner, L. A., & Ewing, R. C. (1997). Displacive radiation effects in the monazite- and zircon-structure orthophosphates. Physical Review B, 56(21), 13805-13814. doi:10.1103/physrevb.56.13805RUBATTO, D., HERMANN, J., & BUICK, I. S. (2006). Temperature and Bulk Composition Control on the Growth of Monazite and Zircon During Low-pressure Anatexis (Mount Stafford, Central Australia). Journal of Petrology, 47(10), 1973-1996. doi:10.1093/petrology/egl033Lacomba-Perales, R., Errandonea, D., Meng, Y., & Bettinelli, M. (2010). High-pressure stability and compressibility ofAPO4(A=La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation. Physical Review B, 81(6). doi:10.1103/physrevb.81.064113Huang, T., Lee, J.-S., Kung, J., & Lin, C.-M. (2010). Study of monazite under high pressure. Solid State Communications, 150(37-38), 1845-1850. doi:10.1016/j.ssc.2010.06.042Long, Y. W., Yang, L. X., Yu, Y., Li, F. Y., Yu, R. C., Ding, S., … Jin, C. Q. (2006). High-pressure Raman scattering and structural phase transition inYCrO4. Physical Review B, 74(5). doi:10.1103/physrevb.74.054110Errandonea, D., Kumar, R., López-Solano, J., Rodríguez-Hernández, P., Muñoz, A., Rabie, M. G., & Sáez Puche, R. (2011). Experimental and theoretical study of structural properties and phase transitions in YAsO4and YCrO4. Physical Review B, 83(13). doi:10.1103/physrevb.83.134109Errandonea, D., Santamaria-Perez, D., Achary, S. N., Tyagi, A. K., Gall, P., & Gougeon, P. (2011). High-pressure x-ray diffraction study of CdMoO4 and EuMoO4. Journal of Applied Physics, 109(4), 043510-043510-5. doi:10.1063/1.3553850Errandonea, D., Santamaria-Perez, D., Grover, V., Achary, S. N., & Tyagi, A. K. (2010). High-pressure x-ray diffraction study of bulk and nanocrystalline PbMoO4. Journal of Applied Physics, 108(7), 073518. doi:10.1063/1.3493048Kraus, W., & Nolze, G. (1996). POWDER CELL – a program for the representation and manipulation of crystal structures and calculation of the resulting X-ray powder patterns. Journal of Applied Crystallography, 29(3), 301-303. doi:10.1107/s0021889895014920Rodríguez-Carvajal, J. (1993). Recent advances in magnetic structure determination by neutron powder diffraction. Physica B: Condensed Matter, 192(1-2), 55-69. doi:10.1016/0921-4526(93)90108-iPanchal, V., Manjón, F. J., Errandonea, D., Rodriguez-Hernandez, P., López-Solano, J., Muñoz, A., … Tyagi, A. K. (2011). High-pressure study of ScVO4by Raman scattering andab initiocalculations. Physical Review B, 83(6). doi:10.1103/physrevb.83.064111Lacomba-Perales, R., Errandonea, D., Segura, A., Ruiz-Fuertes, J., Rodríguez-Hernández, P., Radescu, S., … Muñoz, A. (2011). A combined high-pressure experimental and theoretical study of the electronic band-structure of scheelite-type AWO4 (A = Ca, Sr, Ba, Pb) compounds. Journal of Applied Physics, 110(4), 043703. doi:10.1063/1.3622322Klotz, S., Paumier, L., Le March, G., & Munsch, P. (2009). The effect of temperature on the hydrostatic limit of 4:1 methanol–ethanol under pressure. High Pressure Research, 29(4), 649-652. doi:10.1080/08957950903418194Errandonea, D., Meng, Y., Somayazulu, M., & Häusermann, D. (2005). Pressure-induced transition in titanium metal: a systematic study of the effects of uniaxial stress. Physica B: Condensed Matter, 355(1-4), 116-125. doi:10.1016/j.physb.2004.10.030Mao, H. K., Xu, J., & Bell, P. M. (1986). Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. Journal of Geophysical Research, 91(B5), 4673. doi:10.1029/jb091ib05p04673Effenberger, H., & Pertlik, F. (1986). Four monazite type structures: comparison of SrCrO4, SrSeO4, PbCrO4(crocoite), and PbSeO4. Zeitschrift für Kristallographie, 176(1-2), 75-83. doi:10.1524/zkri.1986.176.1-2.75Silva, E. N., Ayala, A. P., Guedes, I., Paschoal, C. W. A., Moreira, R. L., Loong, C.-K., & Boatner, L. A. (2006). Vibrational spectra of monazite-type rare-earth orthophosphates. Optical Materials, 29(2-3), 224-230. doi:10.1016/j.optmat.2005.09.001Wilkins, R. W. T. (1971). The Raman spectrum of crocoite. Mineralogical Magazine, 38(294), 249-250. doi:10.1180/minmag.1971.038.294.15Frost, R. L. (2004). Raman microscopy of selected chromate minerals. Journal of Raman Spectroscopy, 35(2), 153-158. doi:10.1002/jrs.1121Lacomba-Perales, R., Ruiz-Fuertes, J., Errandonea, D., Martínez-García, D., & Segura, A. (2008). Optical absorption of divalent metal tungstates: Correlation between the band-gap energy and the cation ionic radius. EPL (Europhysics Letters), 83(3), 37002. doi:10.1209/0295-5075/83/37002Urbach, F. (1953). The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids. Physical Review, 92(5), 1324-1324. doi:10.1103/physrev.92.1324Stoltzfus, M. W., Woodward, P. M., Seshadri, R., Klepeis, J.-H., & Bursten, B. (2007). Structure and Bonding in SnWO4, PbWO4, and BiVO4: Lone Pairs vs Inert Pairs. Inorganic Chemistry, 46(10), 3839-3850. doi:10.1021/ic061157gParhi, P., & Manivannan, V. (2009). Novel microwave initiated synthesis of Zn2SiO4 and MCrO4 (M=Ca, Sr, Ba, Pb). Journal of Alloys and Compounds, 469(1-2), 558-564. doi:10.1016/j.jallcom.2008.02.010Knight, K. S. (1996). A neutron powder diffraction determination of the thermal expansion tensor of crocoite (PbCrO4) between 60 K and 290 K. Mineralogical Magazine, 60(403), 963-972. doi:10.1180/minmag.1996.060.403.11Birch, F. (1978). Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300°K. Journal of Geophysical Research, 83(B3), 1257. doi:10.1029/jb083ib03p01257Errandonea, D., & Manjón, F. J. (2008). Pressure effects on the structural and electronic properties of ABX4 scintillating crystals. Progress in Materials Science, 53(4), 711-773. doi:10.1016/j.pmatsci.2008.02.001Errandonea, D., Lacomba-Perales, R., Ruiz-Fuertes, J., Segura, A., Achary, S. N., & Tyagi, A. K. (2009). High-pressure structural investigation of several zircon-type orthovanadates. Physical Review B, 79(18). doi:10.1103/physrevb.79.184104Errandonea, D., Kumar, R. S., Gracia, L., Beltrán, A., Achary, S. N., & Tyagi, A. K. (2009). Experimental and theoretical investigation ofThGeO4at high pressure. Physical Review B, 80(9). doi:10.1103/physrevb.80.094101Gracia, L., Beltrán, A., & Errandonea, D. (2009). Characterization of theTiSiO4structure and its pressure-induced phase transformations: Density functional theory study. Physical Review B, 80(9). doi:10.1103/physrevb.80.094105Santamaría-Pérez, D., Gracia, L., Garbarino, G., Beltrán, A., Chuliá-Jordán, R., Gomis, O., … Segura, A. (2011). High-pressure study of the behavior of mineral barite by x-ray diffraction. Physical Review B, 84(5). doi:10.1103/physrevb.84.054102Errandonea, D., Gracia, L., Beltrán, A., Vegas, A., & Meng, Y. (2011). Pressure-induced phase transitions in AgClO4. Physical Review B, 84(6). doi:10.1103/physrevb.84.064103Lacomba-Perales, R., Martinez-García, D., Errandonea, D., Le Godec, Y., Philippe, J., Le Marchand, G., … López-Solano, J. (2010). Experimental and theoretical investigation of the stability of the monoclinicBaWO4-II phase at high pressure and high temperature. Physical Review B, 81(14). doi:10.1103/physrevb.81.144117Knight, K. S. (2000). A high temperature structural phase transition in crocoite (PbCrO4) at 1068 K: crystal structure refinement at 1073 K and thermal expansion tensor determination at 1000 K. Mineralogical Magazine, 64(2), 291-300. doi:10.1180/002646100549193Snyman, H. C., & Pistorius, C. W. F. T. (1963). Some crystallographic properties of CaSeO4and its hydrates. Zeitschrift für Kristallographie, 119(1-2), 151-154. doi:10.1524/zkri.1963.119.1-2.151Errandonea, D., & Manjón, F. J. (2009). On the ferroelastic nature of the scheelite-to-fergusonite phase transition in orthotungstates and orthomolybdates. Materials Research Bulletin, 44(4), 807-811. doi:10.1016/j.materresbull.2008.09.024Panchal, V., Errandonea, D., Segura, A., Rodríguez-Hernandez, P., Muñoz, A., Lopez-Moreno, S., & Bettinelli, M. (2011). The electronic structure of zircon-type orthovanadates: Effects of high-pressure and cation substitution. Journal of Applied Physics, 110(4), 043723. doi:10.1063/1.3626060Errandonea, D., Martínez-García, D., Lacomba-Perales, R., Ruiz-Fuertes, J., & Segura, A. (2006). Effects of high pressure on the optical absorption spectrum of scintillating PbWO4 crystals. Applied Physics Letters, 89(9), 091913. doi:10.1063/1.2345228López-Moreno, S., Rodríguez-Hernández, P., Muñoz, A., Romero, A. H., & Errandonea, D. (2011). First-principles calculations of electronic, vibrational, and structural properties of scheelite EuWO4under pressure. Physical Review B, 84(6). doi:10.1103/physrevb.84.064108Errandonea, D., Segura, A., Martínez-García, D., & Muñoz-San Jose, V. (2009). Hall-effect and resistivity measurements in CdTe and ZnTe at high pressure: Electronic structure of impurities in the zinc-blende phase and the semimetallic or metallic character of the high-pressure phases. Physical Review B, 79(12). doi:10.1103/physrevb.79.125203Errandonea, D., Segura, A., Muñoz, V., & Chevy, A. (1999). Effects of pressure and temperature on the dielectric constant of GaS, GaSe, and InSe: Role of the electronic contribution. Physical Review B, 60(23), 15866-15874. doi:10.1103/physrevb.60.1586
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
- …
