1,721,302 research outputs found
Anharmonic, Temperature, and Matrix Effects on the Molecular Structure and Vibrational Frequencies of Lanthanide Trihalides LnX3 (Ln = La, Lu; X = F, Cl).
No full textMP2 and CCSD(T) ab initio calculations have been carried out to elucidate geometrical structure and vibrational frequencies of representative lanthanide trihalides LnX3 (Ln = La, Lu; X = F, Cl) explicitly including temperature, anharmonic, inert-gas matrix, and spin−orbit effects. The results have been compared with gas-phase electron diffraction, gas-phase IR measurements, and IR spectra of molecules trapped in inert-gas matrices. On the Born−Oppenheimer surface LaCl3, LuF3, and LuCl3 adopt trigonal planar (D3h) geometry while LaF3 assumes a slightly pyramidal (C3v) structure. Because of normal-mode anharmonicities, the resulting thermal average bond angles are considerably lower than the equilibrium ones, while vibrationally averaged bond lengths are predicted to be longer. The inert-gas matrix effects, modeled by the coordination of two inert-gas molecules LnX3·IG2 (IG = Ne, Ar, Xe, and N2), are substantial and strongly depend on the polarizability of coordinating particles. Coordinating inert-gas units always favor the tendency of LnX3 molecules to adopt planar structure and induce noticeable frequency shifts
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
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
Study of the shelf-life of cured cv Tarocco oranges by sensory and physicochemical parameters
No full textPhysical treatments at temperatures > 30 degrees C and RH > 90% (curing) are useful to limit fungal attacks on citrus fruits post-harvest. In order to evaluate the effect of such treatment on the shelf-life of fruits, cv Tarocco oranges were subjected to curing under various time-temperature combinations and then kept at 8 degrees C and 90% RH for 60 days. Sensory and physicochemical parameters were determined for samples (fresh, at the end of curing, after 20, 40 and 60 days). At the end of the trial, no fungal attacks were detected on fruits. Principal component analysis (PCA) showed differences between fresh and 60 day stored samples. Damage on fruits was proportional to the heat damage of curing. Sensory and physicochemical variables provided different information. The former discriminate samples along the first PC, where the descriptors juiciness, acid and aroma are associated with fresh. Colour differences Delta E, Hunter's parameter a (red-green component) and acidity discriminate samples along the second P
PTF: an Extensible Component for Sharing and Using Knowledge on Pedo-Transfer functions
No full textSoil data availability for modelling purposes is often insufficient for the application of physical or semi-empirical models simulating soil hydrology. Standard soil surveys frequently do not include hydrological characteristics of the soil, such as either parameters of water retention and conductivity functions or, simpler than the former, estimates of soil water content at field capacity and wilting point. Even when at least part of such data is available, a quality control is needed to ensure not only that values fit within expected ranges, but also to check for consistency across parameters in a specific soil. The use of pedotransfer functions (PTF) allows estimating "what we need from what we have", that is, it allows estimating soil hydrological parameters from soil data often available. The literature makes available a large number of PTF, and new ones are being proposed. Such PTF range from very simple empirical functions, to complex soil physical models. Users must select a PTF to be used based on both available data and their a-priori knowledge about the soil to be simulated. Still, the choice of the PTF to be used is at times controversial, and users may want to compare the estimate made by several PTF against the same data. Also, users may want to test their own PTF, may be specific for a set of soils and thus perfectly adequate for application in a specific contest, against well known ones. An extensible and easily reusable library encapsulating a collection of PTF can be an important tool to support development and operational use of soil-related models, and to share the increasing knowledge about PTF. The objective of this paper is to illustrate the free available component PTF (PedoTransfer Functions). The component is available for both Windows.NET and JAVA platforms, and it is made available with some proof of concept applications (inclusive of source code) in C#, VB.NET and Java, which show how to extend the component and how to use it. The software component presented in this paper meets the following main requirement: i) easy to reuse; ii) with a clear ontology of the variables used in each PTF, where units, value range, and significance, are unambiguously defined; iii) extensible by third parties independently, allowing for an open system to which scientists can contribute; iv) freely available for non-commercial use
New production and service roles of the building firms in Italy: problems and perspectives
No full textAb initio Study on Spectroscopic Properties of GdF3 and GdCl3
No full textThe geometry and vibrational frequencies of the GdX3 (X = F and Cl) molecules have been analyzed at the ab initio level with extended basis sets, employing relativistic effective core potential, and evaluating electronic correlation by means of second-order perturbative (MP2) and coupled cluster (CCSD and CCSD(T)) methods. Anharmonicities, temperature, and inert-gas matrix effects have been explicitly included. The MP2, CCSD, and CCSD(T) calculations on the systems in the gas phase indicate a trigonal planar equilibrium structure for GdCl3 and a quasiplanar geometry for GdF3. Vibrationally averaged bond angle, evaluated by means of a simple one-dimensional treatment, is considerably smaller than the equilibrium value and both molecules have a pyramidal thermal average structure, in agreement with recent electron diffraction measurements. The theoretical estimate of Gd−X bond lengths depends on both the electronic correlation treatment and the basis set quality, thus indicating the desirability of high-level calculations. Experimental and theoretical comparison becomes quantitative after including thermal correction. Anharmonic vibrational frequencies have been computed through the vibrational self-consistent field method followed by the second-order perturbation correction. For both gadolinium trihalides, the ν2 out-of-plane bending potential shows a huge “negative” anharmonic form and hot bands fall at considerably higher energies than the fundamental one. Although the anharmonicities for the remaining modes are small, they are important for a correct interpretation of experimental IR spectra. The inert-gas matrix interactions, modeled by coordination of one and two inert-gas molecules GdX3·IGm (IG = Ne, Ar, Xe, and N2; m = 1 and 2), are substantial and GdX3 structures strongly depend on the number of coordinating molecules and on the interaction strength. As a consequence, all normal-mode frequencies slightly diminish as GdX3- -IGm interactions grow, while the ν2 out-of-plane bending frequency significantly increases
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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