1,721,486 research outputs found
PES studies of some short lived combustion intermediates
No full textA new multidetector photoelectron spectrometer has been used to study several short-lived molecules which are known to be important combustion intermediates. A detailed description of the instrument and in particular the problems associated with fluorine atom-molecule reactions are considered. Assignment of observed photoelectron spectra was achieved from experimental evidence and also with the aid of ab initio molecular orbital calculations performed on both the molecule and ion in each case. The first photoelectron bands of five alkyl radicals have been identified experimentally. The ethyl radical study suggested that the cation equilibrium geometry has a bridged structure whereas the cyclopropyl study indicated a cyclic cation structure with the α C-H lying in the carbon skeleton plane. Observation of both the n-propyl and isopropyl radicals led to estimates of the relative stabilities of the two cations. The neopentyl radical has also been studied. The first ionization energies of the isomeric hydroxymethly and methoxy radicals have been determined by photoelectron spectroscopy resulting in estimates of the relative energies of both neutral and cationic isomers in their ground electronic states. In addition, the first photoelectron band of two other oxygenated radicals, the methoxymethyl and oxiranyl radicals, have been observed experimentally. The gas phase reaction of fluorine atoms with benzene has been investigated. As a result the phenyl radical was observed via the abstraction reaction. The addition product, C_6H_6F, was also seen and this showed a kinetic isotope effect on deuteration. In addition, details of some mass spectrometric studies of methane combustion and calibration of the mass spectrometer for methyl radicals are presented. (D67262/86)</p
Some studies of the electronic structure of small molecules and solid metal oxides
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:DX86222 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Beyond significant
No full textThere has recently been much debate about the merits of null hypothesis significance testing (NHST). The American Statistical Association (ASA) recently advised researchers to avoid p-values, as these are commonly misused and misinterpreted. Bayesian inference is offered as an alternative; however, most researchers have received little or no training beyond the practise of NHST. In this talk, I will give a brief historical overview and a practical guide to current Bayesian data analysis methods. Amongst the topics covered are setting up a Bayesian model, parameter estimation, Bayes factors, model comparison and posterior predictive checking. The purpose of this talk will therefore be to familiarize the audience with Bayesian thinking and to demonstrate that with current software, Bayesian analysis is no longer restricted to a small number of expert statisticians
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Vestibular Cognition: A Computational Approach to Sensory Inference and Cognition
No full textThis dissertation is a compilation of publications and manuscripts that seek to advance the burgeoning field of vestibular cognition from two perspectives: (i) by developing a computational framework through which we can connect high-level cognitive capacities to perception of self-motion, and (ii) by investigating whether the perception of self- motion is itself cognitively penetrable, i.e. whether it can be influenced by cognition. In the first manuscript, we provide a formal account of the computations that are similar between self-motion perception, and imagined self-motion, which is conceptualized as a simulation of a dynamical system. This approach aims to provide novel insights into mental imagery, and introduces our sense of self-motion as a suitable sensory modality in which to investigate the connections between cognition and perception. This is largely due to the wealth of computational models that describe the vestibular sensory system in terms of probabilistic inference; this, in turn is due to the comparative simplicity of the peripheral vestibular sensors. In the second manuscript, we discuss how cognitive training may be beneficial to patients suffering bilateral loss of their vestibular sensors, and we seek to understand this in terms of computations that may enable patients to compensate for their loss of sensory input. In the third manuscript, we examine the effect of prior knowledge about the direction of passive self-motion on self-motion decision making. In this empirical study, we sought to determine which cognitive processes are affected by prior knowledge, using a diffusion decision model to analyze subjects’ choices and response times. Although not conclusive, we provide evidence that subjects incorporate their prior knowledge by both biasing their decision-making process and by changing their rate of evidence accumulation. The fourth manuscript is a perspective paper, in which we claim that, in order to understand mental imagery, it is not sufficient to focus merely on neural resources that are shared with perception, but that it is necessary to focus on the computations that are common to both. As such, this paper is a precursor to the first manuscript, which constitutes this thesis’ main contribution
Shifting formic acid dimers into perspective: vibrational scrutiny in helium nanodroplets
No full textVariations on the Author
No full text“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
No full textWe 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
- …
