1,721,028 research outputs found
Spectroscopy and inter/intramolecular dynamics in Honor of Walther Caminati
No full textNo abstract- Editoria
Internal dynamics of cyclohexanol and the cyclohexanol-water adduct
No full textTwo conformers of cyclohexanol and the cyclohexanol-water adduct have been characterized in a jet expansion using rotational spectroscopy. In the gas phase, cyclohexanol adopts an equatorial position for the hydroxyl group, with the two conformers differing in the orientation of the hydroxylic hydrogen, either gauche or trans with respect to the aliphatic hydrogen at C(1). Axial cyclohexanol was not detected in the jet. The transitions of the gauche conformer are split into two component lines due to the tunneling effect of the O-H internal rotation, which connects two equivalent gauche minima. The tunneling splitting in the vibrational ground state has been determined to be ΔE 0+0- = 52(2) GHz. From this splitting, the inversion barriers connecting the two equivalent gauche conformers have been determined using a flexible model to be B 2 = 377 cm -1 . A single isomer is detected for the cyclohexanol-water dimer, in which the water molecule acts as a proton donor to the equatorial gauche ring. The presence of torsional tunneling in the adduct suggests a concerted large-amplitude-motion in which the internal rotation in the ring is accompanied by a torsion of the water molecule, to produce an equivalent enantiomer. The torsional tunneling in the adduct is reduced to ΔE 0+0- = 32.7(4) GHz and the potential barrier in the complex increases to B 2 = 494 cm -1
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
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
The low internal rotation barriers of halogenated toluenes: Rotational spectrum of 2,4-difluorotoluene
No full textAppropriate 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
Rotational Spectroscopy Pinpoints the Tetrahydrate as the Onset of Water Self-Aggregation in Sevoflurane Hydration
No full textCharacterizing the interactions between water and volatile anesthetics at a molecular level is crucial for understanding their mechanisms of action. We employed broadband molecular rotational spectroscopy (CP-FTMW) and extensive isotopic substitution experiments to generate and characterize the stepwise addition of up to four water molecules to the volatile anesthetic sevoflurane, a flexible molecule with multiple binding sites. The substantial amount of isotopic data enabled the conclusive derivation of accurate structural information. The observed structures contain the most stable conformer of the previously identified monomer, with water clusters favorably interacting with the molecule to form an open chain with up to three water molecules. Notably, two isomers were detected for the tetrahydrate, which exhibit a cyclic structure with either a clockwise or anticlockwise orientation, resembling that of the pure water tetramer. The four-water marks a transition where water–water interactions dominate over direct sevoflurane–water interactions driving the assembly of the water network
THE LOW FREQUENCY BROADBAND FOURIER TRANSFORM MICROWAVE SPECTROSCOPY OF HEXAFLUOROPROPYLENE OXIDE, CFCFOCF
No full textthe John B. Stephenson Fellowship Of Aca Is Gratefully; Shipman, Steven T.; Neill, Justin L.; Lesarri, Alberto; Pate, Brooks H.Author Institution: Department of Natural Sciences, Union College, Barbourville, KY 40906; Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904; Departmento de Quimica Fisica, Universidad de Valladolid, Facultad de Ciencias, Valladolid, 47005 SPAIN; Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904The pure rotational spectra of hexafluoropropylene oxide (HFPO), CFCFOCF, as well as its C (1.07\%) and O (0.205\%) isotopomers were recorded in natural abundance from 2.0 to 26 GHz. Low frequency transitions (2 - 8 GHz) were measured by a recently designed chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer at the University of Virginia. The observed spectra lines of C isotopomers (in natural abundance) demonstrate the capability and sensitivity of the CP-FTMW spectrometer operating in 2 - 8 GHz region. The spectra in 8.0 - 26 GHz region were recorded by a Fabry-Perot cavity Fourier transform microwave (FP-FTMW) spectrometer. All the five isotopologues of HFPO were found, and their spectroscopic constants were fit from assigned spectral lines using JB95 and Picketts SPFIT suite of programs. For the dominate HFPO isotopomer: = 2217.04887(11) MHz, = 1101.48958(5) MHz, = 936.60131(5) MHz, = 55.0(2) Hz, = 107.5(9) Hz, = -20(2) Hz, = 8.49(6) Hz, and = -266(2) Hz. The experimentally determined molecular structure and rotational constants are in a good agreement with our density functional theory calculation using B3LYP/6-31g(d) method
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
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