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Now showing 1 - 10 of 6650
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    The Dynamics of death: determining the relationship between within-host pathogen dynamics and host mortality
    (Georgia Institute of Technology, 2021-09-01) O'Sullivan, Tim Sean ; Biology
    Infectious diseases remain a major cause of global mortality, yet basic questions concerning the relationship between within-host pathogen processes and epidemiological patterns of mortality remain obscure. Following an introductory chapter one, we lay out the conceptual challenge in chapter two – how do within-host pathogen dynamics (pathogen burden p(t) as a function of time since infection t) link to changes in epidemiological risk of death, m(t)? We perform a structured literature review of the existing biomedical literature on controlled animal infections, and find consistent support across 28 experiments for an exponentially increasing risk of death m(t) with time since infection. We then illustrate that survival data alone is insufficient to infer pathogen dynamics p(t), with multiple models of pathogen growth and host-pathogen interactions consistent with observed survival data. In chapter three we develop an experimental C. elegans / Pseudomonas aeruginosa infection model platform to allow non-invasive tracking of p(t), via fluorescence-tagged pathogen imaging. Our calibration results show that quantitative inference to pathogen density from fluorescence intensity is not reliable. As a result of this roadblock, in chapter four we turn to a destructive sampling approach, coupled to non-invasive imaging to identify live and dead worms. Estimating pathogen burden in both live and dead worms indicates that pathogen growth is approximately exponential across the transition from host life to death. Our control experiments indicate substantial background mortality in our experimental design, limiting our ability to map mortality onto pathogen dynamics. In chapter five we discuss methodological improvements to our platform, plus potential avenues for future research building on the results presented in this thesis.
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    Polar - legendre duality in convex geometry and geometric flows
    (Georgia Institute of Technology, 2008-07-10) White, Edward C., Jr. ; Harrell, Evans M. ; Guillermo Goldsztein ; Mohammad Ghomi ; Mathematics
    This thesis examines the elegant theory of polar and Legendre duality, and its potential use in convex geometry and geometric analysis. It derives a theorem of polar - Legendre duality for all convex bodies, which is captured in a commutative diagram. A geometric flow on a convex body induces a distortion on its polar dual. In general these distortions are not flows defined by local curvature, but in two dimensions they do have similarities to the inverse flows on the original convex bodies. These ideas can be extended to higher dimensions. Polar - Legendre duality can also be used to examine Mahler's Conjecture in convex geometry. The theory presents new insight on the resolved two-dimensional problem, and presents some ideas on new approaches to the still open three dimensional problem.
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    Constructions and Invariants of High-Dimensional Legendrian Submanifolds
    (Georgia Institute of Technology, 2023-07-17) Roy, Agniva ; Etnyre, John B. ; Hom, Jennifer ; Belegradek, Igor ; Margalit, Dan ; Casals, Roger ; Mathematics
    This thesis explores the question of understanding Legendrian submanifolds in contact manifolds of dimension greater than 3. There are two primary contributions. First, we explore two natural constructions of Legendrian spheres from supporting open book decompositions and show that these always yield the standard Legendrian unknot. Second, in joint work with Hughes, we explore the Legendrians obtained from the doubling construction in dimension 5, and represent them as Legendrian weaves. We show that a large family of pairwise non-isotopic Legendrians can be obtained by looking at doubles associated to torus links T(2, n). Further we also mention theorems in progress regarding the fillability of these doubled Legendrians.
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    Physics of Morphogenetic Matter
    (Georgia Institute of Technology, 2021-11-08) Gardel, Margaret ; Georgia Institute of Technology. School of Physics ; University of Chicago. Dept. of Physics
    My lab studies how the movement and shape of living cells is controlled by living materials constructed by protein assemblies within the cell interior. In this talk, I will describe my lab’s recent efforts to understand the design principles of the active, soft materials that drive morphogenesis of epithelial tissue. In particular, we are interested in the design principles by which protein-based materials generate, relax, sense and adapt to mechanical force. Here I will describe our current experimental efforts to study the regulation of the shape and size of epithelial cells. If time allows, I will discuss how physical constraints govern cell size regulation in epithelial tissue.
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    Assessing the conformation shift of transfer RNA phenylalanine in the presence of iron(II) and magnesium(II)
    (Georgia Institute of Technology, 2013-05-08) Hoskyns, Spencer ; Chemistry and Biochemistry
    The combining of the small subunit and large subunit (LSU) of the ribosome activates the synthesis and extension of a polypeptide through peptide bond formation at the peptidyl transferase center (PTC). This complex incorporates transfer RNA (tRNA) for the transfer of an amino acid to a growing polypeptide chain. Core sequences of ribosomal RNA (rRNA) are coordinated by magnesium cations and quasi-encapsulating ribosomal proteins. Superimposition of LSU crystal structures of many prokaryotic and archaeal species reveals a structurally conserved, magnesium rich core near the site of peptidyl transfer2. The structural change of tRNA in the presence of magnesium(II) could have serious implications for its interactivity with the PTC for peptidyl transfer. Circular dichroism spectroscopy was utilized to determine the structural change associated with the presence of magnesium(II).
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    Analysis of landsat data and testing of hypothesis for Charleston earthquake
    (Georgia Institute of Technology, 1987) Long, Leland Timothy ; Georgia Institute of Technology. Office of Sponsored Programs ; Georgia Institute of Technology. School of Geophysical Sciences ; Georgia Institute of Technology. Office of Sponsored Programs
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    Part I--Approaches to the synthesis of e̲n̲d̲o̲ triazolines; Part II--Chemistry of carotane sesquiterpenoids
    (Georgia Institute of Technology, 1975-08) Clower, Marion Grove ; Zalkow, Leon H. ; Chemistry
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    Interfacial phenomena in bounded simple liquids
    (Georgia Institute of Technology, 1991-08) Sutton, Stephen P. ; O'Shea, Donald C. ; Physics