Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 27 for “"Negative feedback loops"”.
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How bacteria tune mixed positive/negative feedback loops to generate diverse gene expression dynamics
… generate their response through a mixed positive/negative feedback loop (a common alternative sigma factor circuit motif). We use this fact to build a general sigma factor model. In it, we predict a range of behaviours that these circuits should be capable of producing, including both previously …
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Negative feedback regulation as a means to constrain the oncogenic potential of mutant Egfr in NSCLC
… respond to an oncogenic lesion by upregulating negative feedback pathways to counteract the induction of aberrant signaling, and disabling these feedback mechanisms may be an essential component of the progression of EGFR mutant tumors. A multitude of positive and negative feedback loops …
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Systematic Analysis of Crosstalk in the PDGF Receptor Signal Transduction Network
… effects in the respective pathways and negative feedback loops. Motivated by those dynamics, a kinetic model of the network was formulated and used to precisely quantify the relative contributions of PI3K-dependent and -independent modes of Ras/Erk activation.
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Physiological IRE-1-XBP-1 and PEK-1 signaling in Caenorhabditis elegans larval development and immunity
… physiological conditions. Our data suggest that negative feedback loops involving the activation of IRE-1-XBP-1 and PEK-1 pathways serve essential roles not only at the extremes of ER stress but also in the maintenance of ER homeostasis under physiological conditions.
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THE CRISPRATOR: A FEEDBACK CONTROLLER IN MAMMALIAN CELLS FOR ROBUST PERFECT ADAPTATION
… RPA can be achieved by mechanisms like integral feedback control, a specific implementation of Negative Feedback loops. However, the engineering of synthetic biomolecular circuits implementing an integral controller able to confer RPA in living cells is still an open problem, which if solved …
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Mathematical Modeling of Perifusion Cell Culture Experiments
… explain the data. Our model indicates that two negative feedback loops, one fast and one slow, are needed to explain the data and we give their biological bases. We demonstrate that different LH outcomes in oxytocin and GnRH stimulations might originate from different receptor dynamics. We …
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Barriers to implementation of new programs and pedagogies in K-12 STEM Education : a systems perspective
… leverage are identified that can interrupt the negative feedback loops creating pedagogical lock-in, and three case studies of international attempts at pedagogical reform are presented to illustrate effective strategies to utilize these leverage points. General policy recommendations are then …
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Forest fire management in Portugal : developing system insights through models of social and physical dynamics
… System Dynamics, to explore how self-regulating feedback loops affect the outcomes of forest fire management decisions over time. Two models are developed. The strategic model explores the dynamic between suppression and prevention expenditure and its effect on long-term burned area. The …
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Control of neuronal circuits: from biology to robotics
… behaviour is rooted in the presence of mixed feedback. The behaviour is regulated using output feedback and also an adaptive control that tunes the gains of the positive and negative feedback loops. Adaptive control is aligned with neuromodulation, which is central to the adaptation and …
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Endogenous control of stochastic gene expression in the development of Caenorhabditis elegans
… leading to the discovery of multiple novel feedback loops within the Wnt pathway. Applying computational network inference, I revealed a network of interlocking positive and negative feedback loops, which I subsequently show to have a topological advantage in dampening stochastic noise in …
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Anthropometric measurements, sexual development and serum reproductive hormonal levels among boys in the rural Western Cape
… entire pubertal stages and the classic endocrine Negative Feedback Loops in hy pothalamic pituitary gonadal axis were established earlier. Conclusion: The results provide further evidence for the effects potentially from agricultural pesticides exposure in the pattern of growth in height and …
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Bifurcation Analysis and Qualitative Optimization of Models in Molecular Cell Biology with Applications to the Circadian Clock
… trivial task to understand how the positive and negative feedback loops interact to generate an oscillator capable of a) maintaining a 24-hour rhythm in constant conditions; b) entraining to external light and temperature signals; c) responding to pulses of light in a rather particular, …
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Profit cycle dynamics by Kawika Pierson.
… airline industry that includes more endogenous feedbacks than previous models, as well as formulations for several strategies that have been employed by airlines to mitigate the cycles. While I find that, consistent with earlier research, the delay in acquiring capacity is an important …
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Investigating the role of the Caenorhabditis elegans unfolded protein response in immunity and development
… evidence suggesting that the IRE-1 and PEK- 1 negative feedback loops function constitutively to maintain ER proteostasis, even during growth under standard, "unstressed" conditions. Together, these studies highlight the integral role of UPR signaling in C. elegans physiology, and future work, …
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Induction kinetics of the PhoQ-PhoP two-component system in Escherichia coli
… that this impulse response is caused by a negative feedback loop in which active PhoP transcribes mgrB, a gene encoding a small membrane protein that interacts directly with PhoQ to repress the output of the system. MgrB selectively inhibits the ability of PhoQ to phosphorylate PhoP, and …
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A Structural and Biochemical Analysis of the Drosophila Protein Period
… of approximately 24 hours and are based on negative feedback loops. The molecular components of circadian clocks are conserved among animals, and a key element in all such clocks is the protein Period (PER), a circadian transcription inhibitor. The stable production, posttranslational …
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Reconstructing gene function and gene regulatory networks in prokaryotes
… displays dynamics of a particular category where negative feedback loops determine the dynamical behaviour of the network.
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Investigating the relationship between clock gene stability and the pace of the vertebrate segmentation clock
… transcription in the PSM depend on transient negative feedback loops that rely on unstable protein products. However, the pacemaker mechanism that underlies this segmentation clock is poorly understood and little experimental evidence exists linking the level of clock proteins to the …
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Mathematical modelling of negative feedback signal transduction processes
… this thesis we present mathematical models for negative feedback signal transduction processes. Signal transduction pathways are often equipped with negative feedbacks. Negative feedback loops are important components that exhibit oscillations in concentrations of the substances involved, both …
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