1,721,053 research outputs found
Heuristic and deterministic computational solutions for solid-state NMR and molecular spectroscopy
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107680.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 13 juni 2013Promotores : Meerts, W.L., Kentgens, A.P.M., Groenenboom, G.C.129 p
High resolution UV spectroscopy and laser-focused nanofabrication
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32583.pdf (Publisher’s version ) (Open Access)This thesis combines two at first glance different techniques: High Resolution Laser Induced Fluorescence Spectroscopy (LIF) of small aromatic molecules and Laser Focusing of atoms for Nanofabrication. The thesis starts with the introduction to the high resolution LIF technique of small aromatic molecules seeded in molecular beams. It contains a description of the experimental setup and describes the upgrade from the intra-cavity frequency doubling of the 'visible' dye laser to the doubling in an external resonator. This greatly facilitates the experiments by decoupling the dye laser operation from the UV generation step and by increasing the obtained UV power available for the experiment. The latter enables studies of molecules previously unaccessible for the LIF due to their too weak fluorescence signal (like for example bio-molecules). The introduction is closed with the description of the extremely useful method of automated assignment of the rotationally resolved LIF spectra by genetic algorithm (GA). In the following chapters: 2 to 6, different high resolution LIF studies on molecules and molecular clusters are presented, namely the weakly bound van der Waals complexes of tetracene with Ar and Kr atoms (Chapter 2), o-, m-cresols (Chapter 3), p-cresol (4-methylphenol) and its binary water cluster (Chapter 4), resorcinol (Chapter 5) and 4,4'-dimethylaminobenzonitrile (DMABN, Chapter 6). Every molecule presents some interesting points, which are underlined in aforementioned chapters.Chapter 7 contains an introduction to the laser-focused nanofabrication technique. It briefly describes the used experimental setup, laser cooling and focusing of atoms and it also gives a short overview of what other groups have done in the area. It finishes with some important characteristics of chromium and iron - the elements used by me in the laser-focused nanofabrication experiments. The last two chapters present nanofabrication of an intriguing quasiperiodic chromium structures (Chapter 8) and extension of the technique to another technologically important material - iron (Chapter 9). Both experiments provided technical challenges and after realization, if still perfected, can promise materials with interesting physical properties: complete photonic band gap - quasiperiodic chromium structures and extremely coherent ferromagnetic iron nanolines.RU Nijmegen, Physics, 08 september 2005Promotor : Rasing, T.H.M. Co-promotores : Meerts, W.L., Schmitt, M.172 p
Structure and dynamics in small biomolecular systems
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65655.pdf (Publisher’s version ) (Open Access)The exact structures of large, biologically interesting molecules such as proteins are very important for the functions these molecules fulfill. In order to increase our understanding of the relationship between structure and function and to enhance the predictive power of theoretical models the structures of several small model systems have been determined very accurately. Each of these systems is closely related to important structural elements in proteins or DNA. The structure determination itself proceeds through irradiation of these molecules with UV laserlight and subsequent determination of the wavelengths which have been absorbed. From this analysis the rotational energy levels of the molecule can be determined, which are connected to its structure. It turns out that, above all, the structures of systems with multiple chemically weak bonds such as hydrogen bonds differ substantially from theoretical predictions. Since the overall shape of practically all larger biomolecules is determined by these types of bonds, this result has potentially large implications for the analysis of structure and function of biomolecules. The thesis features a comprehensive introduction to the field of high-resolution molecular spectroscopy, assuming a BSc. degree in physics, chemistry or related field. The six following chapters each describe a separate molecular system. These are the benzoic acid dimer (chapter 2), the clusters of phenol with one and two argon atoms (chapter 3), O-toluidine (chapter 4), the 7-azaindole one and two water clusters (chapter 5), the phenol dimer (chapter 6) and benzimidazole (chapter 7).Radboud Universiteit Nijmegen, 20 februari 2009Promotores : Meerts, W.L., Zande, W.J. van der Co-promotor : Schmitt, M.136 p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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