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Lake atomske jezgre proučavane reakcijama izazvanim snopom 13C
Get PDFThe study of light nuclei is one of the most active areas in the nuclear physics today. Nuclei in the mass region A < 20 have been used as a testing sample for different theoretical models since the early days of nuclear physics. Nowadays the advent of ab initio calculations in various frameworks and the astrophysical interest makes the precise experimental data even more important. One of the topics of interest in the structure of light nuclei are the neutron-rich oxygen isotopes, starting already with astrophysically important 17O. One of the challenging questions in this field of research is how does the well developed cluster structure in 16O change with addition of neutrons in heavier oxygen isotopes. Therefore, the topic of this work is the study of the cluster-structure of the 17O and 18O. In this work results of two experiments are presented: the 13C+4He resonant elastic scattering on a thick gas target measurement and the 13C+9Be resonant particle spectroscopy measurement at E13C = 72 MeV. Both measurements were used due to their selectivity in populating the cluster-state candidates in 17O and 18O. The known 13C(4He,4He) elastic scattering cross-section has been extended both in angle (to the 175∘ in direct kinematics) and energy (up to Ex(17O)=13.8 MeV). The measured cross-section can be reproduced by using published set of parameters from the comprehensive Rmatrix fit. The new part of the spectrum contains several resonances of interest, for which the tentative values of spin, parity and Wigner ratio were determined using a simplified R-matrix fitting method. The resonant particle spectroscopy study of the 13C+4He→ 13C+ 4He+ 5He reaction has provided an improvement in statistics and the energy range covered by the previous study. Resonances decaying to the 13C*+4He decay channel were observed as well. The results of both measurements combined point to the pronounced a-cluster nature of the 8.9 MeV, 9.15 MeV and the 13.57 MeV 17O excited states. This is in accordance with predictions of the 17O rotational band based on the weakly coupled neutron to the well-known a-cluster structure in the 16O. However, precise determination of exact spins and parities, as well as partial and total widths are crucial to confirm the existence of the proposed rotational band. The results for the 18O nucleus were obtained from the 13C+9Be reaction measurements using the resonant particle spectroscopy method. The decays of the 18O* nucleus to the 14C+4He and 14C*+4He channels were studied, confirming the results and extending the excitation energy range of previous studies, as well as observing the a-decay of highly excited states for the first time. The results suggest that the 18O states decaying to the 14C+4He channel do not decay to the 14C*+4He channel and vice-versa, possibly due to a different structure. The 6He decay of the 18O has been observed for the first time, at an excitation energy Ex(18O) ≈ 26:5 MeV. Additional studies are necessary to assess the possibility of the 12C+2n+4He molecular structure of the 18O nucleus. In the study of the 13C+9Be→ 10Be+ 8Begs+ 4He reaction a few possible peaks that could indicate the 10Be+8Begs decay of the 18O nucleus were observed, but statistics was too low to obtain conclusive results. Therefore, additional measurements have to be performed. The resonant particle spectroscopy method may be used to collect the high quality data that would allow to compare the partial widths of the states, as well as to extract additional information using a DWBA calculation. The resonant elastic scattering may be used in order to clarify the spin and parity assignments of the cluster or molecular state candidates at higher 18O excitation energies, but the data on all the relevant inelastic channels have to be measured as well.Proučavanje lakih jezgra danas je jedno od najaktivnijih područja nuklearne fizike. Jezgre masenog područja A<20 korištene su za ispitivanje raznih modela nuklearne strukture još od ranih dana nuklearne fizike. Danas su pojavom ab initio računa u raznim modelima te zbog astrofizičke važnosti lakih jezgara precizni eksperimentalni podaci još potrebniji. Jedno od izazovnih pitanja u ovom području istraživanja je kako se naglašena klasterska struktura jezgre 16O mijenja dodavanjem neutrona u težim izotopima kisika. Stoga je tema ovog rada proučavanje klasterske građe izotopa 17O i 18O. U ovom su radu predstavljeni rezultati dvaju eksperimenata: rezonantnog elastičnog raspršenja 13C+4He na debeloj plinskoj meti te mjerenja reakcija 13C+9Be, koje su analizirane metodom rezonantne čestične spektroskopije. Oba su mjerenja odabrana zbog visoke selektivnosti za pobuđivanje stanja moguće klasterske građe u jezgrama 17O i 18O. Područje poznatog udarnog presjeka elastičnog raspršenja 13C(4He,4He) prošireno je u kutnom rasponu (ovo mjerenje odgovara kutu od 175∘ u direktnoj kinematici) te energiji (do Ex(17O) = 13:8 MeV). Izmjeren udarni presjek može se reproducirati korištenjem objavljenih parametara koji su rezultat opsežne prilagodbe višekanalnom R-matricom. Novoizmjereni dio spektra sadrži nekoliko zanimljivih rezonanci za koje su pojednostavljenom prilagodbom R-matrice određeni provizorni spin i paritet te Wignerov omjer. Metodom rezonantne čestične spektroskopije proučena je reakcija 13C+4He → 13C+4He+5He a dobiveni rezultati imaju bolju statistiku i pokrivaju šire područje energija pobuđenja od ranije objavljenih. Također su opažene rezonance koje se raspadaju kanalom 13C*+4He. Rezultati oba mjerenja ukazuju na izraženu a- klastersku građu pobuđenih stanja jezgre 17O na energijama 8.9 MeV, 9.15 MeV i 13.57 MeV. Taj je rezultat u skladu sa predviđanjem rotacijske vrpce 17O zasnovane na poznatoj a-klasterskoj strukturi jezgre 16O i slabo vezanom neutronu. Ipak, precizno određivanje spinova i pariteta stanja, kao i njihovih parcijalnih i ukupnih širina, ključno je za potvrđivanje postojanja predložene rotacijske vrpce. Rezultati za jezgru 18O dobiveni su mjerenjem reakcija 13C+9Be, pomoću metode rezonantne čestične spektroskopije. Raspadi jezgre 18O* kanalima 14C+4He i 14C*+4He potvrdili su informacije o poznatim stanjima te proširili područje energija pobuđenja iz ranijih istraživanja. Pritom je za visokopobuđena stanja jezgre 18O po prvi puta opažen a-raspad. Dobiveni rezultati pokazuju da se stanja koja se raspadaju kanalom 14C+4He ne raspadaju kanalom 14C*+4He i obrnuto, vjerojatno zbog različite strukture. Po prvi je puta opažen 6He raspad jezgre 18O, na energiji pobuđenja Ex(18O) ≈ 26:5 MeV. Potrebna su dodatna istraživanja kako bi se donio zaključak o postojanju moguće molekularne strukture oblika 12C+2n+4He. Analizom reakcije 13C+9Be → 10Be+ 8Begs + 4He pronađeni su mogući vrhovi koji bi mogli ukazivati na 10Be+8Begs raspad pobuđenih stanja jezgre 18O, no broj događaja je premalen da bi se mogao donijeti zaključak. Dakle, potrebna su dodatna mjerenja. Tehnikom rezonantne čestične spektroskopije mogli bi se prikupiti visokokvalitetni podaci, iz kojih bi bilo moguće usporediti parcijalne širine stanja, kao i izdvojiti podatke o strukturi korištenjem DWBA računa. Rezonantno elastično raspršenje može se iskoristiti za razjašnjavanje vrijednosti spina i pariteta klasterskih ili molekulskih stanja na višim energijama pobuđenja 18O, no pritom treba prikupiti i podatke o neelastičnim kanalima
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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