1,721,036 research outputs found
Mathematical modelling of ATP dynamics and decision-making processes in biological systems
No full textCeller er avhengige av ATP (adenosine triphosphate), deres primære energivaluta, for å ta viktige beslutninger angående genuttrykk, overlevelsesstrategier og respons på skiftende miljøer. I denne oppgaven samler vi ideer fra den matematiske studien av genregulatoriske nettverk, tilbakemeldingskontroll og reaksjonsdiffusjonsmodeller for å forstå hvordan variasjoner i ATP-nivåer oppstår og påvirker cellulær aktivitet.
Først, ved å bruke en finkornet matematisk modell av genregulerende nettverk (GRN), undersøker vi hvordan ATP-tilgjengelighet påvirker en celles evne til å ta regulatoriske beslutninger gjennom genuttrykk. Vi viser at høyere ATP-tilgjengelighet forbedrer beslutningskapasiteten ved å øke antallet stabile genekspresjonstilstander som støttes av cellen. På den annen side, når ATP-nivået er lavt, reduseres evnen til å ta beslutninger, noe som fører til mer begrenset cellulær atferd. Vi ser deretter på rollen til tilbakemeldingskontrollmekanismer for å optimalisere cellulær beslutningstaking. Ved å bruke et proportional-integral-derivative (PID) kontrollrammeverk, utforsker vi hvordan celler balanserer fordelene med adaptive responser med de energiske kostnadene ved å sanse og reagere på miljøet. Vår analyse viser at mens regulatorisk kontroll hjelper organismer med å tilpasse seg endrede miljøforhold, krever den også energi for å sanse og behandle informasjon. Denne avveiningen antyder at celler må optimalisere energibruken ved å justere nivået på tilbakemeldingskontroll som svar på endringer i miljøet og tilgjengeligheten av ressurser. Til slutt bruker vi en reaksjonsdiffusjonsmodell for å studere den romlige fordelingen av ATP i celler. Funnene våre viser at ATP ikke alltid er jevnt fordelt, men snarere danner konsentrasjonsgradienter som er påvirket av det romlige arrangementet av mitokondrier og ATP-forbrukende aktiviteter. Disse gradientene påvirker fordelingen av energi i cellen. Når ATP-kilder som mitokondrier er romlig gruppert, kan det oppstå betydelige variasjoner i ATP-konsentrasjon gjennom cellen. Omvendt, i celler der mitokondrier er mer jevnt fordelt, forblir ATP-nivåene mer ensartede, noe som sikrer en jevn tilførsel av energi til cellulære funksjoner.
Ved å kombinere disse perspektivene gir vår studie en bredere forståelse av hvordan variasjon i energitilgjengelighet påvirker cellulær atferd, og bidrar til å forklare hvordan celler tilpasser seg, overlever og presterer godt under ulike miljøforhold.Cells depend on ATP (adenosine triphosphate), their primary energy currency, to make important decisions regarding gene expression, survival strategies, and responses to changing environments. In this thesis, we bring together ideas from the mathematical study of gene regulatory networks, feedback control, and reaction-diffusion models to understand how variations in ATP levels arise, and influence cellular activity.
First, using a fine-grained mathematical model of gene regulatory networks (GRNs), we examine how ATP availability impacts a cell’s ability to make regulatory decisions through gene expression. We show that higher ATP availability improves decision-making capacity by increasing the number of stable gene expression states supported by the cell. On the other hand, when ATP level is low, the ability to make decisions is reduced, leading to more constrained cellular behavior. We then look at the role of feedback control mechanisms in optimizing cellular decision-making. Using a proportional-integral-derivative (PID) control framework, we explore how cells balance the benefits of adaptive responses with the energetic costs of sensing and responding to their environment. Our analysis shows that while regulatory control helps organisms to adapt to changing environmental conditions, it also requires energy for sensing and processing information. This trade-off suggests that cells must optimize their energy use by adjusting the level of feedback control in response to change in the environment and the availability of resources. Lastly, we use a reaction-diffusion model to study the spatial distribution of ATP within cells. Our findings show that ATP is not always uniformly distributed but rather forms concentration gradients that are influenced by the spatial arrangement of mitochondria and ATP-consuming activities. These gradients affect the distribution of energy within the cell. When ATP sources such as mitochondria are spatially clustered, significant variations in ATP concentration can occur across the cell. Conversely, in cells where mitochondria are more evenly distributed, ATP levels remain more uniform, ensuring a consistent supply of energy to cellular functions.
By combining these perspectives, our study provides a broader understanding of how variability in energy availability influences cellular behavior, helping to explain how cells adapt, survive, and perform well in various environmental conditions.Doktorgradsavhandlin
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
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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