1,720,985 research outputs found
Measurement and modelling of anomalous polarity pulses in a multi-electrode diamond detector
No full textInvestigation and development of thin diamond detectors
Full text linkIznimna električna, optička, toplinska i mehanička svojstva čine dijamant materijalom koji bi u skoroj budućnosti mogao zamijeniti siliciji u standardnoj upotrebi za izradu raznih elektroničkih sklopova, ali i detektora zračenja. Ključnu ulogu pritom ima napredak u proizvodnji umjetnih dijamantnih kristala postupkom kemijske depozicije ugljika iz parne faze (CVD). U ovom je radu razvijen transmisijski dijamantni detektor koji istovremeno služi i kao vakuumski prozor za izlaz ubzanih iona iz vakuumskog sustava ionskog ubrzivača u atmosferu. Uređaj se temelji na ultra-tankoj dijamantnoj membrani proizvedenoj jetkanjem debljeg CVD dijamantnog uzorka Ar-O2 plazmom. Zahvaljujući visokoj tvrdoći dijamanta, 6 mikrometara debela membrana u stanju je podnijeti znatno naprezanje uslijed razlike u tlakovima od 1 bar. Metalizacijom nasuprotnih strana dijamantne membrane i uspostavom električnog polja unutar detektora dolazi do stvaranja mjerljivog električnog signala pri upadu nabijenih čestica. Ostvarena, gotovo 100%-tna efikasnost detekcije čak i za ubrzane protone, vrlo je bitna kad se uzorci postavljeni izvan vakuumske komore žele ozračiti točnim brojem čestica, kao što je slučaj kod npr. ozračivanja živih stanica pojedinačnim ionima. Također, testovi otpornosti na zračenje pokazali su očekivano bolje ponašanje 6 mikormetarskog dijamantnog detektora u odnosu na 50 mikrometarski dijamantni i silicijski detektor, zbog čega je njegova primjena moguća i u uvjetima velikih struja čestica. Ipak, uočeni efekt polarizacije dijamantnih detektora predstavlja za sada nepremostivi problem pri detekciji teških iona kratkog dosega. Tada dolazi do djelomičnog poništenja narinutog električnog polja pa signal iz detektora opada.Because of the outstanding electrical, optical, thermal and mechanical properties, diamond is considered as a potential substitute that could replace silicon in production of standard electronic devices. A large success in growth of high quality synthetic diamonds by the chemical vapour deposition method has initiated research directed towards the application of this material for construction of charged particle detectors. In the present work, the development and analysis of a novel transmission diamond detector, based on the ultra-thin diamond membrane, are described. The 6 μm thick membrane was prepared by Ar-O2 plasma etching and serves simultaneously as a vacuum window which enables the extraction of the ion beam from the vacuum system of the accelerator into the atmosphere. Metallization of the opposite surfaces on the membrane allows for the electric field to be applied to the bulk of diamond plate. An impinging ion produces now a measurable electrical signal that can be recorded by standard electronic chain. A hit detection efficiency of close to 100%, even for energetic protons, makes the device ideal for applications that require accurate and controlled dose delivery to a sample that is placed outside of the vacuum chamber. Moreover, the results of the radiation-hardness test indicate a wider possible range of device applications, including those that involve high currents of charged particles or long exposure to radiation. However, the detection of short range ions is disturbed by the polarization effect which occurs due to deep level traps that are present in even the best quality diamond crystals
Modeliing γ-H2AX foci induction to mimic limitations in the scoring technique.
No full textAn approach based on track-structure calculations has been developed to take account of artefacts occurring during γ-H2AX foci detection in 2D images of samples analyzed through immunocytochemistry. The need of this works stems from the observed saturation in foci yields measured after X-ray doses higher than few grays, hindering an unambiguous quantification of DNA damage and of radiation effectiveness. The proposed modelling approach allows to simulate the observer's point of view for foci scoring, mimicking the selection of a slice Δz of the cell nucleus due to the microscope depth of field, and applying a clustering algorithm to group together damages within a resolution parameter r. Calculation results were benchmarked with experimental measurements at an early time-point for mouse breast cancer cells, irradiated with X-ray doses in the range 0-5 Gy. The model is able to reproduce the saturation in experimental data
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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