1,355,422 research outputs found
A Tribute to Manne Siegbahn
No full textSpectroscopy came to dominate the 19th century, with a crucial role for Swedish physicists. It was Anders Ångström who introduced the tenmillionth part of a millimeter as the wavelength unit (1868), a unit that was adopted by Rowland for his tables of the solar spectral lines (1887-1893). Janne Rydberg, then, followed in Ångström's footsteps in searching for relations between the emission spectra of the elements and their place in the Periodic Table. Röntgen's new rays became a next challenge, demanding a form of spectroscopy of their own. Manne Siegbahn, an assistant of Rydberg, then, devised appropriate instruments of ever increasing precision
Caractéristiques d'un spectbométbe β du type Siegbahn-Slatis
No full textA long lens β ray Siegbahn-Slatis spectrometer has been tested. The best resolution found is 0.5 % with Th B. Under normal conditions we obtained 3 % transmission with 1.5 % resolution. We have studied conversion lines and continuous spectra. The accuracy in the spectrum shape may attain 1 %.Un spectromètre type Siegbahn-Slatis a été mis au point. Ses performances ont été étudiées. Sa résolution maximum est de 0,5 % avec Th B. On obtient par ailleurs 3 % de transmission pour 1,5 % de résolution. Des raies et des spectres ont été tracés. La précision dans la forme des spectres semble pouvoir atteindre 1 %
Scientometric analysis of synchronous references in the Physics Nobel lectures, 1981-1985 : a pilot study
No full textScientometric analysis of synchronous references in the nine Physics Nobel lectures by Nicolaas Bloembergen (1981), Arthur L. Schawlow (1981), Kai M. Siegbahn (1981), Kenneth G. Wilson (1982), Subrahmanyan Chandrasekhar (1983), William A. Fowler (1983), Carlo Rubbia (1984), Simon van der Meer (1984), and Klaus von Klitzing (1985) indicated high variations: No. of Synchronous References ranged from 24 (Meer) to 283 (Siegbahn); Synchronous Self-References ranged from 5 (Rubbia) to 88 (Siegbahn); synchronous references to others ranged from 10 (Chandrasekhar) to 255 (Wilson); Synchronous Self-Reference Rates ranged from 6.66 % (Rubbia) to 65.51 % (Chandrasekhar); Single-Authored References ranged from 15 (Klitzing) to 160 (Wilson); Multi-Authored References ranged from 4 (Chandrasekhar) to 194 (Siegbahn); Collaboration Coefficient in the synchronous references ranged from 0.14 (Chandrasekhar) to 0.75 (Klitzing); and Recency (age of 50 % of the latest references) ranged from 2 (Klitzing) to 18 (Chandrasekhar) years. Seventy five per cent of the references belonged to journal articles. Highly referred journals were Astrophysical Journal, Physical Review B, Physical Review Letters, Arkiv Fuer Fysik, Surface Science, Physics Letters, and IEEE Transactions on Nuclear Science.
See: Scientometrics Vol. 61 No.1, pp.55-68
Introduction to Kai Siegbahn's memorial issue
No full textKai Siegbahn is mainly known to the afterworld for his development of spectroscopies which have provided a detailed understanding of the electronic structure of atoms, molecules and condensed matter. These spectroscopies are based on the discoveries made by him and his collaborators in the beginning of the 1960s which led to a Nobel prize in physics for Kai in 1981. The collection of papers in the present volume illustrate the present status of the many flourishing aspects of electron spectroscopy which have developed as a result of his initial ideas and their background in nuclear physics experimentation. (C) 2009 Elsevier B.V. All rights reserved.</p
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
Variations 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
Growing up with one ear : central auditory structure and function in unilateral ear canal atresia
No full textThe following thesis aims to give more insight into the functional and structural response of the central auditory system to congenital unilateral ear canal atresia (UCA) and the accompanying asymmetric hearing with conductive hearing loss on the atretic side.There is clear evidence that unilateral hearing loss, including UCA, has a negative impact on sound localization ability and perception of speech in noise. There is a spread in performance within the group, and the reason for this is not well known. In paper I of this thesis we examined sound localization with eye tracking and perception of speech in a cocktail party setting, in participants with congenital unilateral ear canal atresia, who had no hearing aids before age 12 (n=12) and compared to normal hearing references. Results show that the level of hearing loss on the atretic ear was associated with sound localization ability but not to speech perception.In the second study, participants with UCA (n=17) underwent MRI-scanning of the brain with diffusion weighted imaging (DWI). A method is described how to segment the white matter bundle between the medial geniculate body of the thalamus and the primary auditory cortex, the acoustic radiation (AR). Methods to define the AR are previously described in high resolution diffusion weighted imaging (DWI) scans but is very time consuming or has problems with including more structures around the primary auditory cortex (PAC). An algorithm was trained to quickly segment the core of the AR in individual clinical scans. The white matter tract was also assessed with measurements of fractional anisotropy (FA), but no differences were found between UCA and normal hearing (NH) controls.The third study describes the measurements of the grey matter of the primary auditory cortex of the Heschl’s gyrus in the same participants as in paper II. Thickness and volume of the Heschl’s gyrus were compared within the groups of UCA and controls, and between the groups. A difference in thickness was found between the left and right side (right thicker than left, corrected p=0.0012) in UCA, whereas controls had symmetric thickness. Volumes and total thickness were not different compared to controls.Rat brains from 12 months old rats with a surgically constructed left-sided ear canal atresia were examined in study IV. DWI was acquired in a research camera for rodents, 9.4 T magnetic field and a prolonged scanning time. Tractography and FA measurements were obtained both from whole brains and from tracts between auditory regions of interest (ROIs) using two different software. FA was generally higher in UCA rats than in controls. The AR was asymmetric in FA (leftList of scientific papersI. Siegbahn M, Engmér Berglin C, Hultcrantz M, Asp F. (2021). Adults with unilateral congenital ear canal atresia -sound localization ability and speech in competing speech in unaided condition. Acta Otolaryngol. 2021 Jul;141(7):689-694.https://doi.org/10.1080/00016489.2021.1921843II. Siegbahn M, Engmér Berglin C, Moreno R. (2022). Automatic segmentation of the core of the acoustic radiation in humans. Front Neurol. 2022 Sep 23, 13: 934650.https://doi.org/10.3389/fneur.2022.934650III. Siegbahn M, Jörgens D, Aspp F, Hultcrantz M, Moreno R, Engmér Berglin C. Asymmetry in cortical thickness of the Heschl’s gyrus in unilateral ear canal atresia. Otology & Neurotology. https://doi.org/10.1097/mao.0000000000004137IV. Siegbahn M, Kraft S, Maschio F, Hultcrantz M, Engmér Berglin C, Moreno R. White matter tracts of the auditory pathways in experimental unilateral ear canal atresia. [Manuscript]</p
The GEANT4 toolkit for microdosimetry calculations: Application to microbeam radiation therapy (MRT)
No full textMicrodosimetry for Microbeam Radiation Therapy (MRT): theoretical calculations using the Monte Carlo toolkit
No full text- …
