<p>Bistable switches are commonly observed in the regulation of critical processes such as cell cycles and differentiation. The switches possess two fundamental properties: memory and bimodality. Once switched ON, the switches can remember their ON state despite a drastic drop in stimulus levels. Furthermore, at intermediate stimulus levels with cellular noise, the switches can cause a population to exhibit bimodal distribution of cell states. Till date, experimental studies have focused primarily on cellular mechanisms that generate bistable switches and their impact on cellular dynamics. </p><p>Here, I study emergent bistability due to bacterial interactions with either synthetic gene circuits or antibiotics. A synthetic gene circuit is often engineered by considering the host cell as an invariable "chassis". Circuit activation, however, may modulate host physiology, which in turn can drastically impact circuit behavior. I illustrate this point by a simple circuit consisting of mutant T7 RNA polymerase (T7 RNAP*) that activates its own expression in bacterium Escherichia coli. Although activation by the T7 RNAP* is noncooperative, the circuit caused bistable gene expression. This counterintuitive observation can be explained by growth retardation caused by circuit activation, which resulted in nonlinear dilution of T7 RNAP* in individual bacteria. Predictions made by models accounting for such effects were verified by further experimental measurements. The results reveal a novel mechanism of generating bistability and underscore the need to account for host physiology modulation when engineering gene circuits.</p><p>In the context of antibiotic treatment, I investigate bistability as the underlying mechanism of inoculum effect. The inoculum effect refers to the decreasing efficacy of an antibiotic with increasing bacterial density. Despite its implication for the design of antibiotic treatment strategies, its mechanism remains poorly understood. Here I show that, for antibiotics that target the core replication machinery, the inoculum effect can be explained by bistable bacterial growth. My results suggest that a critical requirement for this bistability is sufficiently fast turnover of the core machinery induced by the antibiotic via the heat shock response. I further show that antibiotics that exhibit the inoculum effect can cause a "band-pass" response of bacterial growth on the frequency of antibiotic treatment, whereby the treatment efficacy drastically diminishes at intermediate frequencies. The results have implications on optimal design of antibiotic treatment.</p> / Dissertation

<p>The control of matter and phenomena at the nanoscale is fast becoming one of the most important challenges of the 21st century with wide-ranging applications from energy and health care to computing and material science. Conventional top-down approaches to nanotechnology, having served us well for long, are reaching their inherent limitations. Meanwhile, bottom-up methods such as self-assembly are emerging as viable alternatives for nanoscale fabrication and manipulation.</p><p>A particularly successful bottom up technique is DNA self-assembly where a set of carefully designed DNA strands form a nanoscale object as a consequence of specific, local interactions among the different components, without external direction. The final product of the self-assembly process might be a static nanostructure or a dynamic nanodevice that performs a specific function. Over the past two decades, DNA self-assembly has produced stunning nanoscale objects such as 2D and 3D lattices, polyhedra and addressable arbitrary shaped substrates, and a myriad of nanoscale devices such as molecular tweezers, computational circuits, biosensors and molecular assembly lines. In this dissertation we study multiple problems in the theory, simulations and experiments of DNA self-assembly. </p><p>We extend the Turing-universal mathematical framework of self-assembly known as the Tile Assembly Model by incorporating randomization during the assembly process. This allows us to reduce the tile complexity of linear assemblies. We develop multiple techniques to build linear assemblies of expected length N using far fewer tile types than previously possible.</p><p>We abstract the fundamental properties of DNA and develop a biochemical system, which we call meta-DNA, based entirely on strands of DNA as the only component molecule. We further develop various enzyme-free protocols to manipulate meta-DNA systems and provide strand level details along with abstract notations for these mechanisms. </p><p>We simulate DNA circuits by providing detailed designs for local molecular computations that involve spatially contiguous molecules arranged on addressable substrates via enzyme-free DNA hybridization reaction cascades. We use the Visual DSD simulation software in conjunction with localized reaction rates obtained from biophysical modeling to create chemical reaction networks of localized hybridization circuits that are then model checked using the PRISM model checking software.</p><p>We develop a DNA detection system employing the triggered self-assembly of a novel DNA dendritic nanostructure. Detection begins when a specific, single-stranded target DNA strand triggers a hybridization chain reaction between two distinct DNA hairpins. Each hairpin opens and hybridizes up to two copies of the other, and hence each layer of the growing dendritic nanostructure can in principle accommodate an exponentially increasing number of cognate molecules, generating a nanostructure with high molecular weight. </p><p>We build linear activatable assemblies employing a novel protection/deprotection strategy to strictly enforce the direction of tiling assembly growth to ensure the robustness of the assembly process. Our system consists of two tiles that can form a linear co-polymer. These tiles, which are initially protected such that they do not react with each other, can be activated to form linear co-polymers via the use of a strand displacing enzyme.</p> / Dissertation

In order to extend fluid-based flow control techniques that have been demonstrated at low subsonic speeds to high speed flows, it is necessary to develop actuators having sufficient momentum to control and manipulate high speed flows. Two fluidic actuation approaches are developed where the control jet may reach supersonic velocities and their performance is characterized. The first actuator is a compressible synthetic (zero net mass flux) jet. This is an extension of previous work on synthetic jets with an increase in driver power yielding substantial pressurization of the cavity such that the flow is compressible. The jet is generated using a piston/cylinder actuator, and the effects of variation of the orifice diameter, actuation frequency, and compression ratio are investigated. Operation in the compressible regime uniquely affects the time-dependent cylinder pressure in that the duty cycle of the system shifts such that the suction phase is longer than the blowing phase. The structure of the jet in the near-field is documented using particle image velocimetry and Schlieren flow visualization. In the range investigated, the stroke length is sufficiently long that the jet flow is dominated by a starting jet rather than a starting vortex (which is typical of low-speed synthetic jets). A simple, quasi-static numerical model of the cylinder pressure is developed and is in generally good agreement with the experimental results. This model is used to assess system parameters which could not be measured directly (e.g., the dynamic gas temperature and mass within the cylinder) and for predictions of the actuator performance beyond the current experimental range. Finally, an experiment is described with self-actuated valves mounted into the cylinder head which effectively icrease the orifice area in suction and overcome some of the limitations inherent to compressible operation. The second actuation concept is the combustion-driven jet actuator. This device consists of a small-scale (nominally 1 cc) combustion chamber which is filled with premixed fuel and oxidizer. The mixture is ignited using an integrated spark gap, creating a momentary high pressure burst within the combustor that drives a high-speed jet from an exhaust orifice. At these scales, the entire combustion process is complete within several milliseconds and the cycle resumes when fresh fuel/oxidizer is fed into the chamber and displaces the remaining combustion products. The actuator performance is characterized by using dynamaic measurements of the combustor pressure along with Schlieren flow visualization, limited dynamic thrust measurements, and flame photography. The effects of variation in the following system parameters are investigated: fuel type and mixture ratio, exhaust orifice diameter, chamber aspect ratio, chamber volume, fuel/air flow rate, ignition/combustion frequency, and spark ignition energy. The resulting performance trends are documented and the basis for each discussed. Finally, a proof-of-concept experiment demonstrates the utility of teh combustion-driven jet actuators at low-speed for transitory reattachment of a separated flow over an airfoil at high angles of attack.

In Taiwan, the rubber industry began to bloom from the Japanese Colonial Era, and most of the rubber technologies were originated from Japan. Its evolution began from the rubber parts to the synthetic rubber manufacturing. The most of synthetic rubber manufacturers are cooperated with companies from Japan and US, the rubber industry was allowed to develop vigorously in a short period of time. In contrary to Taiwan, China could only obtain the obsolete rubber technologies and management skills from the Former USSR due to economy sanction during the Cold War period. The rubber industries lagged behind in terms of quality, production efficiency, and management. As China embraced the Socialist Planned Economy after the Communist Victory in Civil War, the marketing and sales made subject to state control and development was being dragged. After the Reform and Opening-Up, although there were a bunch of rubber manufacturers from Japan and western countries started to establish local production activities in China, the foreign investment bogged down after the Tiananman Square Protest in 1989. Only the Taiwanese manufacturers moved their steps to China against the tide with modern production technologies and management skills. The complementary development brought by Taiwan and China contributed significant improvement in quality of Chinese rubber goods and became a story on everybody¡¦s lips on the cooperation of the rubber industries between two sides of Taiwan Strait. Rubber industries are closely related to national defense and consumer goods, which makes themselves equally import to plastic industries. However, due to the labor-intensive nature of rubber industries and the serious lack of labor force in Taiwan in 1990¡¦s, the Taiwanese rubber industries began to move their production sites to China and accelerated the inosculation of the rubber industries in Taiwan and China. As the main raw material of rubber industries, the synthetic rubber is no exceptional either. In the end of 20th Century, China has successfully become the ¡§World Factory¡¨ and the consumption and capacity of synthetic rubber became the top of the world. Then the financial crisis in 2008 turned the China¡¦s policies to concentrate the development of the domestic demand, which made China the ¡§World Market¡¨. In recent years, the relationships between Taiwan and China have been substantially improved. The Economy Cooperation Framework Agreement (ECFA) is officially signed and taking effects, the economical activities and relationships between both sides are expected to be more liberalized than the past. The study is specially focused on the evolution of the marketing channel of the synthetic rubber between Taiwan and China, and how ECFA is going to possibly affect the synthetic rubber industries. The study will integrate the writer¡¦s points of view and the various ideas abstracted from the interviews with the several Associations and main agents/distributors in Taiwan and China in order to infer the trends of future development of rubber industries. With this study, the readers who are in the business are allowed to be more clear about the evolution of the marketing channel of the synthetic rubber industries and the trends of future development, so that the readers can take the initiatives to prepare for the future.

This thesis integrated geology, geophysics, and petroleum engineering data to build a detailed reservoir characterization models for three gas pay sands in the Grand Isle 33 & 43 fields, offshore Louisiana. The reservoirs are Late Miocene in age and include the upper (PM), middle (QH), and lower (RD) sands. The reservoir models address the stratigraphy of the upper (PM) sand and help delineate the lower (RD) reservoir. In addition, this research addresses the partially depleted QH-2 reservoir compartment. The detailed models were constructed by integrating seismic, well log, and production data. These detailed models can help locate recoverable oil and gas that has been left behind. The upper PM model further delineated that the PM sand has several areas that are shaled-out effectively creating a flow barrier within reservoir compartments. Due to the barrier in the PM-1 reservoir compartment, an area of potentially recoverable hydrocarbons remains. In Grand Isle 33, the middle QH sand was partially depleted in the QH-2 reservoir compartment by a series of development wells. Bottom hole pressure data from wells in Grand Isle 32 & 33 reveal that the two QH fault compartments are in communication across a leaking fault. Production wells in the QH-1 compartment produced reserves from the QH-2 compartment. The lower RD sand model helped further delineate the reservoir in the RD-2 compartment and show that this compartment has been depleted. The RD model also shows the possible presence of remaining recoverable hydrocarbons in the RD-1 compartment. It is estimated that about 6.7 billion cubic feet of gas might remain within this reservoir waiting to be recovered. A seismic amplitude anomaly response from the QH and RD sands is interpreted to be a lithologic indicator rather than the presence of hydrocarbons. Amplitude response from the PM level appears to be below the resolution of the seismic data. A synthetic seismogram model was generated to represent the PM and surrounding sands. This model shows that by increasing the frequency of the seismic data from 20 Hz to a dominant frequency of 30 Hz that the PM and surrounding sands could be seismically resolvable. Also the PM-1 compartment has possible recoverable hydrocarbons of 1.5 billion cubic feet of gas remaining.

Sustaining development is becoming one of the challenges to enterprises because concerns to the natural and human environments are always being overlooked by the enterprises which intend to get sustaining advantages, especially at the globalization competing situations among enterprises. In general, only part pictures of the sustaining development can be observed by the first department (personal department) from a private viewpoint. The second department (government) is always a stumbling block to the enterprises which intend to move to foreign countries. The third department (nonprofit organization) dedicates to the development of human well-beings and citizen aesthetics which can eventually become a part of business culture. Enterprises with the concept of sustaining development for environments should agree to the viewpoints of the second and the third departments and would like to melt those into their business cultures. By the melting, a coexistence concept for the enterprises, the society and the consumers can be developed, and the social responsibilities and duties may be brought into the enterprises further. Finally, it will become an active motivation force which accelerates business development and their social responsibility mission, and eventually becomes a global sustaining development for human beings. Taiwan¡¦s leading position of synthetic leather manufacture in the world has been replaced due to its higher domestic labor, land costs and enterprise out-moving. However, some companies of the industry is still developing and promising by taking the policies of producing centralization, variety, and high value-additive products. For facing world-wide competition in the future, the industry should have an overall strategy on the viewpoints of business administration and environmental policy. In this study, two approaches, namely business competition strategy and business environmental policy, were adopted to develop subjects for obtaining a sustainable development to the synthetic leather industry. Investigation results indicate that a world-wide plumb-integration on cost competition, and producing centralized, high-variety, and high value-additive products might be a practical strategy for competing with the world plant mainland China. By a case study in this report, the strategy has been shown to be effective for abating negative impacts from current situations of world trade liberalization, inside cost promotion, and enterprise out-moving Pollution prevention has been regarded as a burden to enterprises. However, investigation results also indicate that by planning and implementation of environmental policies such as process waste reduction, energy saving, clean production, and development of environment-friendly products, the synthetic leather industry can find a more promising way.

Abstract Taiwan Synthetic Resin industry filed, undergoing fifty hard years, this is a mature industry and most of companies have been built up a certain scale of production. Since 1997 the China government combined economic reform with open policy to create a rapid economy growth. With the appeal of market superiority rising and low production cost, truly attracts many inverters enter the target market. Under such strong market competitive, some of Taiwan Synthetic Resin companies have successfully transferred into a high-tech industrial territory, some of companies were standing on their original basis to improve its competition ability. Hence, there is obviously difference of the final business performance in between them. This thesis is based on the case study for Q company, engaged in manufacturing Synthetic Resin related products. The research methodologies take various theoretical analyses such as the ¡§Value Chain¡¨ model of Michael Porter and ¡§Strategic Alliance¡¨ to investigate the business strategy of those listed companies and OTC of Taiwan Synthetic Resin industry. Hope this research should provide useful information about the related strategic usage and future development of the Synthetic Resin industry. The key points of finding in this study may be summarized as under: 1) The technical resource of Taiwan Synthetic Resin industry is mainly demanded on technical alliance and the R&D capability is still under developing. 2) The rapid economic growth and development of the Mainland China caused more difficult environment for Taiwan company future development in the business transformation strategy. 3) The enterprise resource is key success factor in achieving competitive advantages in operation, technology and marketing in the industry field. Key words: Synthetic Resin¡BValue Chain¡BStrategic Alliance¡BBusiness transformation

An experimental investigation was undertaken to test the effectiveness of a novel design for controlling the aerodynamics of an airfoil. A synthetic jet actuator (SJA) was placed inside a NACA 0015 airfoil with its jet at 12.5% of the chord length, hereby referred to as the leading edge actuator. Four centrifugal fans across the span were mounted at 70% of the chord and the jet formed by them was located at 99% of the chord, hereby referred to as the trailing edge actuator. The effects of these actuators on the aerodynamic properties were studied, separately and then in conjunction, with varying angles of attack. The leading edge actuator delays the onset of stall up to 24 degrees, the maximum angle of attack that could be attained. The control of the aerodynamics was achieved by controlling the amount of separated region. There was no effect of the actuation at lower angles of attack. The trailing edge actuator provides aerodynamic control at both low and high angles of attack. The study investigated the effect of jet momentum coefficient on the aerodynamic properties for various angles of attack. The data obtained shows that lift control (in both positive and negative direction) was achieved even at low angles. The actuator enhances the aerodynamic properties by changing the pressure distribution as well as by delaying flow separation. Study of the combined actuation shows that the synthetic jet actuator was very effective in delaying stall when the trailing edge jet was ejected from the upper surface. For the case when the jet is ejected from the lower surface, there is less control. This can be accounted for by the difference in aerodynamic loading for both cases.

Thesis (M.Eng.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 95-100.

Dramatic land-cover changes have occurred in a broad range of spatial and temporal scales over the last decades. Satellite remote sensing, which can observe the earth's surface in a consistent manner, has been playing an important role in monitoring and evaluating land-cover changes. Meanwhile, optical remote sensing, a common approach to acquiring land-cover information, is limited by weather conditions and thus is greatly constrained in areas with frequent cloud cover and rainfall. Recent advances in polarimetric SAR (PolSAR) provide a promising means to extract timely information of land-cover changes regardless of weather conditions. SAR satellite can pass through an area from different orbits, namely ascending orbit and descending orbit. The PolSAR images from the same orbit will have similar backscattering even with different incident angles. But if images are acquired from different orbits, the backscattering will vary greatly, which causes many difficulties to land cover change detection. The proposed algorithms in this study can perform land cover change detection in three situations: 1) repeat-pass images (image from the same orbit and with same incident angle, 2) images from the same orbit but with different incident angle, and 3) images from different orbits. Using images from different orbits will largely reduce the monitoring interval which is important in the surveillance of natural disasters. The present study proposes 1) a sub-pixel automatic registration technique, 2) an automatic change detection technique and 3) an iterative framework to process a time series of PolSAR images that can be applied to the PolSAR images from different orbits. Firstly, automatic registration is crucial to the change detection task because a small positional error will largely degrade the accuracy of change detection. The automatic registration technique is based on the multi-scale Harris corner detector. To improve the efficiency and robustness, the orientation angle differencing method is proposed to reject outliers. This differencing method has been proved effective even in the experiment of using PolSAR images from different orbits when less than 5% of the feature point matches are correct. Secondly, the change detection technique can automatically detect land-cover conversions and classify the newly input image. Hierarchical segmentation has been applied in the change detection which generates objects within the constraint of the previous classification map. Multivariate kernel density estimation is applied to classify newly input PolSAR image. The experiments show that the proposed change detection technique can mitigate the effect of polarimetric orientation shift when the PolSAR images are from different orbits, and it can achieve high accuracy even when complex local deformation is appeared. Lastly, the iterative framework, which integrates the automatic registration and automatic change detection techniques, is proposed to process a time series of PolSAR images. In the iterative process, no obvious decrease of classification accuracy is observed. Therefore, the proposed framework provides a potential treatment to derive land-cover dynamics from a time series of PolSAR images from different orbits. / published_or_final_version / Urban Planning and Design / Doctoral / Doctor of Philosophy