Browsing by Subject "Biological systems"
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Item Analytical study of a control algorithm based on emotional processing(Texas A&M University, 2007-04-25) Chandra, ManikThis work presents a control algorithm developed from the mammalian emotional processing network. Emotions are processed by the limbic system in the mammalian brain. This system consists of several components that carry out different tasks. The system level understanding of the limbic system has been previously captured in a discrete event computational model. This computational model was modified suitably to be used as a feedback mechanism to regulate the output of a continuous-time first order plant. An extension to a class of nonlinear plants is also discussed. The combined system of the modified model and the linear plant are represented as a set of bilinear differential equations valid in a half space of the 3-dimensional real space. The bounding plane of this half space is the zero level of the square of the plant output. This system of equations possesses a continuous set of equilibrium points which lies on the bounding plane of the half space. The occurrence of a connected equilibrium set is uncommon in control engineering, and to prove stability for such cases one needs an extended Lyapunov-like theorem, namely LaSalle's Invariance Principle. In the process of using this Principle, it is shown that this set of equations possesses a first integral as well. A first integral is identified using the compatibility method, and this first integral is utilized to prove asymptotic stability for a region of the connect equilibrium set.Item Measuring system dynamics: mRNA, protein and metabolite profiling(2005) Lu, Peng; Marcotte, Edward M.Item Remote quantitative transport and imaging investigations of small fluorescent molecular probes in an interstitial tissue model(Texas Tech University, 1998-08) Houlne, Michael PatrickThe diffusive transport characteristics of a unique class of small fluorescent molecular probes in an interstitial tissue model are investigated using micro-endoscopy. The probes employed in the present work are organo-metallic complexes of polyazamacrocycles chelated to Terbium. These particular molecules have large Stoke's shifts, making them amendable to tissue analysis. The delocalized electronic structure of the organic chelate absorbs ultra-violate light (~270 nm) and, after inter-molecular transfer, the lanthanide cation fluoresces in the visible region (550 nm). The diffusive transport properties of the probe molecules are related to their chemical structure, which governs their affinity toward the components of the interstitial model. The basic polyazamacrocyde is functionalized with three phosphate groups. Presently, methyl, ethyl, propyl and butyl alkyl chains are added to the phosphate groups on the polyazamacrocyde to modify the affinity of the probes toward the components of the interstitial model. The interstitial tissue model is constructed by preparing a Type I collagen gel in phosphate buffer solution. Known quantities of the probe are injected into the gel and the resulting diffusive transport of the probe is digitally imaged through a micro-endoscope as a function of time. Microendoscopy coupled with digital imaging allows remote, quantitative analysis of the transport process in near real time. Cross sectional analysis of the images yields the concentration profile of the probe as it diffuses through the gel. The concentration profile is fit to Fick's second law of diffusion to determine the diffusion coefficient for each of the probe molecules.