1,720,953 research outputs found
Die Wirkung von Alizarin, Calcein und dem Oberflächenmarker PKH2 auf das Proliferationsverhalten von Rothirsch-Geweihzellen
Get PDFIn einer experimentellen Studie sollte anhand von Zellkulturen die Wirkung von
Fluoreszenzfarbstoffen auf das Proliferationsverhalten von Rothirsch-Geweihzel
len überprüft werden. Die Untersuchung wurde in zwei Versuchsanordnungen
durchgeführt. In der ersten Anordnung wurden über 27 Tage vier Gruppen von
Zellen in 6-Well-Platten kultiviert. Die drei Verumgruppen wurden jeweils mit den
Fluoreszenzfarbstoffen Calcein, Alizarin-Komplexone und PKH2 als Zusatz zu
DME-Medium inkubiert. Eine Kontrollgruppe lief parallel zu jeder Verumgruppe
mit. Innerhalb der 27 Tage des Versuch wurden an 12 Tagen die Zellzahl be
stimmt, so dass für jede Gruppe 12 Serien als Tripletts kultiviert wurden, so dass
insgesamt 144 Wells im ersten Versuch mit Zellkulturen beimpft wurden. Die Zell
zahl wurde mit der MTT-Methode bestimmt, wobei die Zellzahl einer genau fest
gelegten Exstinktion des MTT-Tests zugeordnet wurde. Dazu kann eine Neu
bauer-Zählkammer zum Einsatz. Von jedem Well wurden 3 Extinktionen gemes
sen. Aus den 9 Messwerten pro Versuchstag wurden dann der Mittelwert berech
net und für die weitere Darstellung in den Grafiken benutzt. Zur Differenzierung
der Proliferation wurden auch die Berechnung der mittleren Generationszeit, die
Anzahl der Generationen und die kumulative Zellzahl herangezogen.
In der zweiten Versuchsanordnung wurde neben der Zellzahlbestimmung die
Calceinintensität in den fluoreszierenden Zellen gemessen, um einen Zusam
menhang zwischen der Proliferation und der Farbstoffbeladung ableiten zu kön
nen.
Als wesentliche Ergebnisse konnte festgestellt werden, dass die Farbstoffe einen
geringen Einfluss auf die Proliferation der Zellen haben, der mit zunehmender
Kultivierungszeit aber immer größer wird. Alle Farbstoffe haben in den ersten 8
bis 10 Tagen keinen Einfluss auf die Proliferation. Gegenüber der Kontrollgruppe
zeigt Alizarin die stärkste Hemmung der Proliferation, gefolgt von Calcein und
PKH2. Am deutlichsten wird dies durch die kumulativen Zellzahl, der mittleren
Generationszeit und der Anzahl der Generationen alle in Abhängigkeit von der
Kulturzeit vermittelt. Auch die Normalisierung der zeitabhängigen Zellzahl und
ihre Differenzenbildung mit der Kontrollgruppe vermittelt brauchbare Ergebnisse,
während der einfache Auftrag der Zellzahl gegen die Kulturzeit sich als unüber
sichtlich darstellt.
Im zweiten Versuchsansatz wurde lediglich Calcein über 44 Tage weiter unter
sucht, da Alizarin-Komplexone nur eine geringe Fluoreszenz und sich PKH2 für
den längeren Einsatz unter den vorliegen Versuchsbedingen nicht stabil gegen
das Ausbleichen zeigte. Calcein hingegen ließ sich sehr gut detektieren. Das Ma
ximum seiner Zellkonzentration konnte zwischen dem 18. und 28. Tag in der Kul
tur festgestellt werden. Es wurde jedoch nur von wenigen Zellen aufgenommen,
die ab dem 28 Tage zum Ende des Versuchs hin stark in ihrer Zahl abnahmen.
Aufgrund der vorliegenden Ergebnisse kann vermutet werden, dass insbeson
dere Alizarin und Calcein, die häufigsten Fluorochrome in Tierversuchen zu Kno
chenexploration, keinen wesentlichen Einfluss auf die Zellproliferation haben, da
sie zumeist im beschränkten Umfang und nur kurzfristig appliziert werden.In an experimental study, the effect of fluorescent dyes on the proliferation behavior of red deer antler cells was examined using cell cultures. The investigation was conducted in two experimental setups.
In the first setup, four groups of cells were cultured in 6-well plates over a period of 27 days. The three test groups were incubated with the fluorescent dyes Calcein, Alizarin Complexone, and PKH2 as an additive to the DME medium. A control group was run in parallel to each test group. Over the 27-day experiment, the cell count was determined on 12 different days, with 12 series cultivated as triplicates for each group. This resulted in a total of 144 wells inoculated with cell cultures in the first experiment. The cell count was determined using the MTT assay, where the cell number was correlated with a precisely defined extinction value of the MTT test. A Neubauer counting chamber was used for this purpose. Three extinction values were measured for each well, and the mean of the 9 measurements per test day was calculated and used for graphical representation. To further differentiate proliferation, the average generation time, the number of generations, and the cumulative cell count were also analyzed.
In the second experimental setup, in addition to cell count determination, the Calcein intensity in fluorescent cells was measured to identify a potential correlation between proliferation and dye uptake.
The key findings indicate that the dyes have a minimal effect on cell proliferation, though this influence increases with longer cultivation times. During the first 8 to 10 days, none of the dyes affected proliferation. Compared to the control group, Alizarin exhibited the strongest inhibition of proliferation, followed by Calcein and PKH2. This effect was most evident in the cumulative cell count, average generation time, and the number of generations, all dependent on the culture duration. Normalization of time-dependent cell counts and their differences from the control group provided useful results, whereas simply plotting cell count against culture time appeared unclear.
In the second experimental approach, only Calcein was further investigated over 44 days, as Alizarin Complexone exhibited low fluorescence and PKH2 was not stable against fading under the given experimental conditions for long-term use. Calcein, however, was well-detectable. Its maximum cell concentration was observed between days 18 and 28 in culture. However, it was only taken up by a few cells, which significantly declined in number from day 28 until the end of the experiment.
Based on these results, it can be assumed that Alizarin and Calcein, which are among the most commonly used fluorochromes in animal experiments for bone exploration, do not have a significant impact on cell proliferation, as they are typically applied in limited amounts and only for short durations.2025-02-2
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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