1,721,380 research outputs found
Experimental and theoretical studies of unstable species
No full textThe work presented in this thesis is concerned with the study of unstable species using both experimental and theoretical methods. The experimental studies are described in Chapters 2 to 4, and the theoretical ab initio methods are considered in Chapters 5 and 6.Structured spectra of the à and C̃; states of Kr·NO have been obtained using one-colour and two-colour resonance-enhanced multiphoton ionisation spectroscopy. Estimates of the dissociation energies of both complexes are given. The appearance of spectra in both the Kr·NO+ and Kr+ mass channels was investigated, and mechanisms for the formation of Kr+ ions are discussed. Spectra of the à state of the Ar·NO complex are also presented. The non-Rydberg behaviour of the à states of Ar·NO and Kr·NO is discussed.Constant ionic state spectra of carbon monosulphide are presented in the photon energy range 11.3 - 20 electron volts using synchrotron radiation. The spectra, recorded using several vibrational components of the ground ionic state of CS have been assigned using quantum defect analysis.In Chapter 4, results obtained by scattering laser and synchrotron radiation off pulsed free jet expansions of Ar and N2O are presented. The results are interpreted in terms of Rayleigh scattering from clusters formed within the free jet. Information on the relative size of clusters formed is obtained and compared to literature data. Where synchrotron radiation was used, contributions from non-Rayleigh scattering processes are considered.ab initio molecular orbital calculations on the NO2+·X (X=H2O, N2, CO2) series of complexes are reported in Chapter 5. Optimised geometries and vibrational frequencies, as well as computed total energies have been used to calculate standard enthalpies, entropies and free energies for the complexing and ligand-switching reactions between the three molecular complexes. The results obtained have been compared to previous experimental and theoretical values where available.The intermolecular potential energy surface of the Ar·NO+ cationic complex has been calculated using ab initio molecular orbital calculations. The effect of level of theory, basis set, NO+ bond length and basis set superposition error was investigated. The calculated surfaces were used to obtain intermolecular vibrational frequencies, which were compared to previous calculations and experimental results.</p
Interstitial lung disease in children younger than 2 years
Full text linkChildhood interstitial lung disease (chILD) represents a highly abstract
heterogeneous group of rare disorders associated with substantial
morbidity and mortality. Although our understanding of chILD remains
limited, important advances have recently been made, the most important
being probably the appreciation that disorders that present in early life
are distinct from those occurring in older children and adults, albeit with
some overlap. chILD manifests with diffuse pulmonary infiltrates and
nonspecific respiratory signs and symptoms, making exclusion of common
conditions presenting in a similar fashion an essential preliminary step.
Subsequently, a systematic approach to diagnosis includes a careful history
and physical examination, computed tomography of the chest, and some
or all of bronchoscopy with bronchoalveolar lavage, genetic testing, and if
diagnostic uncertainty persists, lung biopsy. This review focuses on chILD
presenting in infants younger than 2 years of age and discusses recent
advances in the classification, diagnostic approach, and management of
chILD in this age range. We describe novel genetic entities, along with
initiatives that aim at collecting clinical data and biologic samples from
carefully characterized patients in a prospective and standardized fashion.
Early referral to expert centers and timely diagnosis may have important
implications for patient management and prognosis, but effective therapies
are often lacking. Following massive efforts, international collaborations
among the key stakeholders are finally starting to be in place. These have
allowed the setting up and conducting of the first randomized controlled
trial of therapeutic interventions in patients with chILD
Diagnosing primary ciliary dyskinesia
No full textThe National Specialist Commissioning Advisory Group (NSCAG) has funded three centres to establish and provide a national diagnostic service for England for children and adults suspected of suffering from primary ciliary dyskinesia (PCD). This is welcomed, as state of the art diagnostic testing will be available nationally which will increase the numbers of patients diagnosed with a condition in which early diagnosis has a very significant effect on both short-term and long-term morbidity. Inheritance is autosomal recessive with an incidence of around 1:15 000 in the Caucasian population and, as expected, we have found a much higher incidence in ethnic groups where consanguineous marriages are common. Accurate diagnosis will allow appropriate genetic counselling of families
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
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
Editorial: Difficult and severe asthma in children, volume II
No full textEditorial on difficult asthma. No abstract availabl
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