1,723,570 research outputs found
Linked collectors and determiners for: A revision of the Anthaxia (Haplanthaxia) dispar Kerremans species-group (Coleoptera: Buprestidae: Anthaxiini).
No full textNatural history specimen data linked to collectors and determiners held within, "A revision of the Anthaxia (Haplanthaxia) dispar Kerremans species-group (Coleoptera: Buprestidae: Anthaxiini)". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/e1eaf13c-9009-4e84-836e-91bbf7d2c81e">https://bionomia.net/dataset/e1eaf13c-9009-4e84-836e-91bbf7d2c81e</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/e1eaf13c-9009-4e84-836e-91bbf7d2c81e">https://gbif.org/dataset/e1eaf13c-9009-4e84-836e-91bbf7d2c81e</a>. Formatted as a Frictionless Data package
Linked collectors and determiners for: Three new country records from the genus Limnephilus Leach, 1815 (Trichoptera: Limnephilidae) from the Republic of Kosovo.
No full textNatural history specimen data linked to collectors and determiners held within, "Three new country records from the genus Limnephilus Leach, 1815 (Trichoptera: Limnephilidae) from the Republic of Kosovo". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/de4ddd94-937b-4acc-9009-3d9e348c9ea1">https://bionomia.net/dataset/de4ddd94-937b-4acc-9009-3d9e348c9ea1</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/de4ddd94-937b-4acc-9009-3d9e348c9ea1">https://gbif.org/dataset/de4ddd94-937b-4acc-9009-3d9e348c9ea1</a>. Formatted as a Frictionless Data package
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
Applications of X-ray crystallography: studies into the structural perturbations of peri-substituted naphthalene derivatives
No full textThe majority of research in this thesis uses X-ray crystallography to investigate the structural features of peri-substituted naphthalene compounds. X-ray crystallography is introduced in chapter one, followed by a discussion on modes of distortion peri-substituted naphthalene derivatives can undergo, in chapter two.
In chapter three, compounds having non-bonded -SPh and -EPh (E = S, Se, or Te) peri-substituents are compared. These similar compounds react differently when oxidized with bromine. The oxidation products are used to discuss a recently proposed mechanism and a more specific mechanism is suggested.
In chapter four, a one-pot synthesis for naphtho[1,8-c,d]-1,2-diselenole (Se₂naph) is reported. Substituents were added to Se₂naph to form two new naphthalene compounds. The substituents are found to distort the Se-Se bond and influence packing.
In chapter five, several diselenium-containing compounds are used as ligands in platinum(II)-bisdiphosphine complexes. The preference for platinum(II) to stay square planar dictates the geometry around the metal center, not the rigidity of the naphthalene backbone.
Chapter six introduces (8-phenylsulfanylnaphth-1-yl)diphenylphosphine, a peri-substituted naphthalene containing -SPh and -PPh₂ substituents, and several derivatives. This ligand is used in a variety of complexes containing platinum(II), ruthenium(II), and copper(I) metal halides, whose coordination geometries are discussed in chapter 7. The naphthalene-based ligands in Cu(I) and Ru(II) seem to determine the geometry around the metal, whereas the metal center d-orbitals dominate in the Pt(II) examples.
Chapters eight and nine deviate from the naphthalene theme. In chapter eight, X-ray analysis of sulfoxide compounds is used to discuss the structural environment around the sulfur. Various intra- and inter-molecular interactions were discovered in crystal packing.
Finally, chapter 9 uses STANDARD (St ANDrews Automated Robotic Diffractometer) to statistically analyze numerous E₂Ph₂ (E = S, Se, or Te) crystals to determine chirality. It is intriguing that Te₂Ph₂ shows a preference for one enantiomer over the other
Synthesis and structural studies of group 16 peri-substituted naphthalenes and related compounds
No full textUnderstanding how atoms interact is a fundamental aspect of chemistry, biology and materials science. There have been great advances in the knowledge of covalent and ionic bonding over the past twenty years but one of the major challenges for chemistry is to develop full understanding of weak interatomic/intermolecular forces. This thesis describes fundamental studies that develop the basic understanding of weak interactions between heavier polarisable elements. The chosen methodology is to constrain heavy atoms using a rigid naphthalene backbone.
When substituents larger than hydrogen, are positioned at close proximity at the peri-positions of a naphthalene molecule they experience steric strain; the extent of which is dictated by intramolecular interactions. These interactions can be repulsive due to steric hindrance or attractive due to weak or strong bonding.
In efforts to understand the factors which influence distortion in sterically crowded naphthalenes and study possible weak intramolecular interactions between peri-atoms, investigations focussed on previously unknown mixed 1,8-disubstituted naphthalene systems. Mixed phosphorus-chalcogenide species were initially studied; three mixed phosphine compounds of the type Nap[ER][PPh2] were prepared along with their chalcogenides and a series of metal complexes.
The study of interactions between heavy atoms was progressed by investigations into a series of mixed chalcogenide compounds of the type Nap[EPh][E’Ph] (E = S, Se, Te). Subsequent reaction of the chalcogenide systems with the di-halogens, dibromine and diiodine, afforded a mixture of charge transfer and insertion adducts displaying an array of different geometries around the chalcogen atom.
From molecular structural studies, a collection of intramolecular peri-interactions were found, extending from no interaction due to repulsive effects, weak attractive 3c-4e type interactions and one example containing a strong covalent peri-bond. Further weak intramolecular interactions observed include CH-π and E•••E’ type interactions plus π-π stacking between adjacent phenyl rings. It was discovered that the bulk of the peri-atoms is influential on the distance between them, but this is not the only factor determining the naphthalene geometry. Inter- and intramolecular interactions can also have an impact and furthermore the number, size and electronic properties of substituents attached to the peri-atoms can determine molecular distortion
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