1,722,877 research outputs found
Sinogastromyzon nantaiensis Chen, Han and Fang 2002
No full text118. Sinogastromyzon nantaiensis Chen, Han and Fang, 2002:240, figs. 1–2 Holotype: NMMBP 465 (44.7), Laonon River, Kaoping basin, Darjin, Liukuei, Pingtung County, Taiwan, Aug. 1994, coll. I.–S. Chen. Paratype: NMMBP 466 (3, 36.8–40.3), same data as holotype; NMMBP 467 (7, 33.4–44.2), Laonon River, Kaoping basin, Tsaolan, Liukuei, Pingtung County, S Taiwan, Feb. 1995, coll. I.–S. Chen et al.; NMMBP 468 (2, 29.8–35.6), Nanhaur River, Tzengwen River, Peiliao, Tainan County, Taiwan, 29 Oct. 1999, coll. I.–S.Chen and R.–S. Wu.Published as part of Ho, Hsuan-Ching & Shao, Kwang-Tsao, 2011, 2957, pp. 1-74 in Zootaxa 2957 on page 3
New methods and applications of energy decomposition analysis based on large-scale first principles quantum mechanics
No full textMolecular systems with functional domains serve as a practical motivation for understanding the factors that contribute to the interaction energy. The ability to decompose the interaction energy of a group of interacting subsystems is an important method in studying the chemical nature of the interactions. Energy decomposition analysis (EDA) is a family of schemes that allows such dissection of the interaction energy into chemically relevant components depending on the scheme used. Since different EDA schemes decompose the interaction energy differently, the interpretation of the resulting components differs among schemes. However, various EDA schemes provide complementary insights into the interactions between chemical entities. In this work, two EDA schemes are developed or extended: Hybrid Absolutely Localized Molecular Orbitals (HALMO) and Combined Localized Molecular Orbitals (CLMO). Both EDA schemes have been implemented as part of a linkable library alongside the computational chemistry package, ONETEP. Since ONETEP is a linear-scaling software package, an important application of such decomposition analysis is in the study of large, nontrivial molecular systems for more insightful understanding of chemical interactions, which in turn can lead to more accurate and focused design of chemical systems. Systems such as biomolecules usually contain several self-stabilizing domains that can fold independently and have important functions. Defining the fragments of a supermolecule is necessary in EDA, and if done appropriately given the context of a particular application, the fragmentation of a biomolecule can elucidate the intramolecular interactions that contribute to the functions of the system as a whole. Two major methods of self-consistent field for molecular interaction (SCF MI) are examined and made more mathematically transparent. SCF MI was originally designed to exclude basis set superposition error (BSSE) from molecular interactions. However, SCF MI is also used in separating charge transfer from polarization in HALMO EDA. Studying several SCF MI methods provides HALMO EDA alternatives for separating charge transfer as an EDA component. Due to ONETEP’s linear scaling, large biomolecules or large samples of biomolecules could be studied for their interactions or distributions of specific properties. The primary type of biomolecule studied in this work is double-stranded DNA (dsDNA) and how its stability relates to guanine-cytosine (GC) content, which is a measure of the amount of guanines or cytosines in nucleic acids. By examining the interaction energies in terms of EDA components, contributions to the variabilities within and across GC-content groups are examined and are correlated with differing stabilities despite having same GC content. Ensemble density-functional theory (EDFT) optimizes the molecular orbitals of a system at finite electronic temperatures and allows occupancies to be fractional when the band gap is sufficiently small. EDA methods are normally developed for the pure state and pose difficulties in decomposing the interaction energy of a conductor due to the fractional occupancies that are part of the optimization process in EDFT. As such, fractional occupancies have been incorporated in the EDA optimization process of the fragmented species, thereby allowing EDA to be applied to systems of relevance to catalysis and metallic systems. The adaptations of EDA and SCF MI to metallic systems are novel and were validated using samples from catalysis and batteries, and HALMO EDA has provided reasonable decompositions of interaction energies and revealed some trends from SCF MI that correlate with charge distributions and chemical intuition
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
Energy decomposition analysis method for metallic systems
No full textIn this work, we present the first extension of an energy decomposition analysis (EDA) method to metallic systems. We extend the theory of our Hybrid Absolutely Localized Molecular Orbitals (HALMO) EDA to take into account that molecular orbitals in metallic systems are partially occupied, which is done by weighted orthogonalization (WO) of the molecular orbitals using their associated fractional occupancies as weights in the construction of the projection operators. These operators are needed for the self-consistent field for molecular interaction (SCF MI) computation of the polarization-energy contribution to the interaction. The method gives more weight to orbitals that have higher occupancies and treats each fragment as metallic. The resulting HALMO EDA for metallic systems naturally reduces to the insulator version and produces the same results when applied to an insulating system. We present the theory and implementation of our new approach, and we demonstrate it with sample calculations of relevance to industrial materials. This work provides a new EDA paradigm and tool for the study and analysis of interactions in metallic systems within large-scale DFT calculations
Analysis of DNA interactions and GC content with energy decomposition in large-scale quantum mechanical calculations
No full textGC content is a contributing factor to the stability of nucleic acids due to hydrogen bonding. More hydrogen bonding generally results in greater stability. Empirical evidence, however, has suggested that the GC content of a nucleic acid is a poor predictor of its stability, implying that there are sequence-dependent interactions besides what its GC content indicates. To examine how much such sequence-dependent interactions affect the interaction energies of double-stranded DNA (dsDNA) molecules, dsDNA molecules of different sequences are generated and examined in silico for variabilities in the interaction energies within each group of dsDNA molecules of the same GC content. Since the amount of hydrogen bonding depends on the GC content, holding the GC content fixed when examining the differences in interaction energies allows sequence-dependent interactions to be isolated. The nature of sequence-dependent interactions is then dissected using energy decomposition analysis (EDA). By using EDA, the components of the interactions that depend on the neighboring base pairs help explain some of the variability in the interaction energies of the dsDNA molecules despite having the same GC content. This work provides a new paradigm and tool for the study and analysis of the distributions of interaction components in dsDNA with the same GC content using EDA within large-scale quantum chemistry calculations
Brushwork and Spirit: The realistic ink figure painting of Chen Han sheng
Full text linkPainter Chen Han sheng has resolutely chosen the path of realistic ink figure painting. He explores an artistic language suitable for self-expression through sketching, drawing on traditional landscape and flower-and-bird painting ink techniques for figure painting. With the sentiment of a literati, he experiences life, pays attention to society, shapes the spirit of the times with traditional brush and ink, and thus explores an academic and artistic path in realistic painting
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
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
- …
