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- Title
- The Phenomenological Experience of Narrative Transportation.
- Creator
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Buchanan, William, Fiore, Stephen, Weger, Harry, Miller, Ann, University of Central Florida
- Abstract / Description
-
Previous research has attempted to identify consequences of mental transportation into narrative worlds. While scales have been developed and validated to measure readers' levels of transportation, the objective quantification has left researchers at a descriptive disadvantage for the full range of qualitative responses to this phenomenon. This study presents a qualitative method of inquiry designed to get at the experience of narrative transportation as it is lived: the phenomenological...
Show morePrevious research has attempted to identify consequences of mental transportation into narrative worlds. While scales have been developed and validated to measure readers' levels of transportation, the objective quantification has left researchers at a descriptive disadvantage for the full range of qualitative responses to this phenomenon. This study presents a qualitative method of inquiry designed to get at the experience of narrative transportation as it is lived: the phenomenological interview. Interview transcripts were inductively analyzed for common themes that indicate intersubjective features of narrative experience. Four main themes were identified, which were composed of 22 base-level experiences reported by participants. These findings corroborated the extant literature and provided a nuanced understanding of the phenomenon as it is lived.
Show less - Date Issued
- 2013
- Identifier
- CFE0004657, ucf:49883
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004657
- Title
- Analysis of Behaviors in Crowd Videos.
- Creator
-
Mehran, Ramin, Shah, Mubarak, Sukthankar, Gita, Behal, Aman, Tappen, Marshall, Moore, Brian, University of Central Florida
- Abstract / Description
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In this dissertation, we address the problem of discovery and representation of group activity of humans and objects in a variety of scenarios, commonly encountered in vision applications. The overarching goal is to devise a discriminative representation of human motion in social settings, which captures a wide variety of human activities observable in video sequences. Such motion emerges from the collective behavior of individuals and their interactions and is a significant source of...
Show moreIn this dissertation, we address the problem of discovery and representation of group activity of humans and objects in a variety of scenarios, commonly encountered in vision applications. The overarching goal is to devise a discriminative representation of human motion in social settings, which captures a wide variety of human activities observable in video sequences. Such motion emerges from the collective behavior of individuals and their interactions and is a significant source of information typically employed for applications such as event detection, behavior recognition, and activity recognition. We present new representations of human group motion for static cameras, and propose algorithms for their application to variety of problems.We first propose a method to model and learn the scene activity of a crowd using Social Force Model for the first time in the computer vision community. We present a method to densely estimate the interaction forces between people in a crowd, observed by a static camera. Latent Dirichlet Allocation (LDA) is used to learn the model of the normal activities over extended periods of time. Randomly selected spatio-temporal volumes of interaction forces are used to learn the model of normal behavior of the scene. The model encodes the latent topics of social interaction forces in the scene for normal behaviors. We classify a short video sequence of $n$ frames as normal or abnormal by using the learnt model. Once a sequence of frames is classified as an abnormal, the regions of anomalies in the abnormal frames are localized using the magnitude of interaction forces.The representation and estimation framework proposed above, however, has a few limitations. This algorithm proposes to use a global estimation of the interaction forces within the crowd. It, therefore, is incapable of identifying different groups of objects based on motion or behavior in the scene. Although the algorithm is capable of learning the normal behavior and detects the abnormality, but it is incapable of capturing the dynamics of different behaviors.To overcome these limitations, we then propose a method based on the Lagrangian framework for fluid dynamics, by introducing a streakline representation of flow. Streaklines are traced in a fluid flow by injecting color material, such as smoke or dye, which is transported with the flow and used for visualization. In the context of computer vision, streaklines may be used in a similar way to transport information about a scene, and they are obtained by repeatedly initializing a fixed grid of particles at each frame, then moving both current and past particles using optical flow. Streaklines are the locus of points that connect particles which originated from the same initial position.This approach is advantageous over the previous representations in two aspects: first, its rich representation captures the dynamics of the crowd and changes in space and time in the scene where the optical flow representation is not enough, and second, this model is capable of discovering groups of similar behavior within a crowd scene by performing motion segmentation. We propose a method to distinguish different group behaviors such as divergent/convergent motion and lanes using this framework. Finally, we introduce flow potentials as a discriminative feature to recognize crowd behaviors in a scene. Results of extensive experiments are presented for multiple real life crowd sequences involving pedestrian and vehicular traffic.The proposed method exploits optical flow as the low level feature and performs integration and clustering to obtain coherent group motion patterns. However, we observe that in crowd video sequences, as well as a variety of other vision applications, the co-occurrence and inter-relation of motion patterns are the main characteristics of group behaviors. In other words, the group behavior of objects is a mixture of individual actions or behaviors in specific geometrical layout and temporal order.We, therefore, propose a new representation for group behaviors of humans using the inter-relation of motion patterns in a scene. The representation is based on bag of visual phrases of spatio-temporal visual words. We present a method to match the high-order spatial layout of visual words that preserve the geometry of the visual words under similarity transformations. To perform the experiments we collected a dataset of group choreography performances from the YouTube website. The dataset currently contains four categories of group dances.
Show less - Date Issued
- 2011
- Identifier
- CFE0004482, ucf:49317
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004482
- Title
- THE NATURE OF TURBULENCE IN A NARROW APEX ANGLE ISOSCELES TRIANGULAR DUCT.
- Creator
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Krishnan, Vaidyanathan, Kapat, Jayanta, University of Central Florida
- Abstract / Description
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An experimental investigation was performed to ascertain the nature of turbulence in a narrow apex angle isosceles triangular duct. The study involved the design and construction of a low noise, low turbulence wind tunnel that had an isosceles triangular test section with an apex angle of 11.5°. Experiments involved the measurement of velocity fluctuations using hot wire anemometry and wall pressure fluctuations using a condenser microphone. Measurement of the velocity fluctuations...
Show moreAn experimental investigation was performed to ascertain the nature of turbulence in a narrow apex angle isosceles triangular duct. The study involved the design and construction of a low noise, low turbulence wind tunnel that had an isosceles triangular test section with an apex angle of 11.5°. Experiments involved the measurement of velocity fluctuations using hot wire anemometry and wall pressure fluctuations using a condenser microphone. Measurement of the velocity fluctuations reconfirms the coexistence of laminar and turbulent regions at a given cross section for a range of Reynolds numbers. The laminar region is concentrated closer to the apex while the turbulent region is found closer to the base. The point of transition is a function of the Reynolds number and moves closer to the apex as the flow rate is increased. Moreover, it was found in this investigation that traditional scaling of the turbulent statistical quantities do not hold good in this geometry. Although velocity fluctuations showed distinctive flow regimes, no such distinction could be seen in the dynamic wall pressure data. The nature of the dynamic wall pressure was uniform throughout the entire cross section suggesting that wall pressure fluctuations, unlike the velocity fluctuations, are able to travel from the base to the apex, without being damped. This implies that the relationship between the velocity and the pressure fluctuations applicable in the other systems does not hold well in a narrow apex angle isosceles triangular duct. Further, the typical scaling relationships applied to wall pressure spectra of other geometries doesn't apply in this scenario and the ratio of the RMS pressure fluctuation to the mean shear is much higher compared to a flat plate or pipe flow situation.
Show less - Date Issued
- 2007
- Identifier
- CFE0001955, ucf:47471
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001955
- Title
- AN HEDONOMIC EVALUATION OF PLEASURABLE HUMAN-TECHNOLOGY EXPERIENCE: THE EFFECT OF EXPOSURE AND AESTHETICS ON THE EXPERIENCE OF FLOW.
- Creator
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Murphy, Lauren, Hancock, Peter, University of Central Florida
- Abstract / Description
-
A framework was developed called the Extended Hedonomic Hierarchy (EHH) that provides a basis for evaluating pleasurable human-system experience. Results from a number of experiments within this framework that evaluated specific dimensions of the framework are reported. The 'Exposure' component of the EHH framework and hedonics of the system were investigated to see how changes would affect other dimensions, such as the occurrence of flow, the mode of interaction, and the needs of the user....
Show moreA framework was developed called the Extended Hedonomic Hierarchy (EHH) that provides a basis for evaluating pleasurable human-system experience. Results from a number of experiments within this framework that evaluated specific dimensions of the framework are reported. The 'Exposure' component of the EHH framework and hedonics of the system were investigated to see how changes would affect other dimensions, such as the occurrence of flow, the mode of interaction, and the needs of the user. Simulations and video games were used to investigate how repeated exposure affects flow, interaction mode, and the user needs. The Kansei Engineering method was used to measure user needs and investigate the effect of different hedonic properties of the system on user needs and flow. Findings reveal that: (a) pleasurable human-system experience increases linearly with repeated exposure to the technology of interest; (b) an habituation effect of flow mediated by day; (c) motivation to satisfy human need for technology is hierarchically structured and contributes to pleasurable human-system experience; (d) interactivity is hierarchically structured and seamless mode of interaction is a behavioral outcome of pleasurable human-system experience; (e) there are individual differences among users that affect the likelihood of experiencing pleasurable human-system interaction; (f) performance is positively correlated to flow and (g) the method of kansei engineering provides data from which informed decisions about design can be made and empirical research can be conducted. Suggestions for (a) making Hedonomics a reality in industry, the workplace, and in the field of Human Factors, (b) future research directions for Hedonomics, and (c) principles and guidelines for the practice of Hedonomics are discussed.
Show less - Date Issued
- 2005
- Identifier
- CFE0000875, ucf:46650
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000875
- Title
- MICROSCOPIC SURFACE TEXTURES CREATED BY INTERFACIAL FLOW INSTABILITIES.
- Creator
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Gu, Jing, Weiwei Deng, Dr., University of Central Florida
- Abstract / Description
-
In nature, microscopic surface textures impact useful function, such as the drag reduction of shark skin (Dean & Bhushan, 2010) and superhydrophobicity of the lotus leaf(Pan, Kota, Mabry, & Tuteja, 2013). In this study, we explore these phenomena by re-creating microscopic surface textures via the method of interfacial flow instability in drying polyvinylidene fluoride (PVDF) acetone solutions. In general, PVDF films can be made using either spin coating or electrospray deposition with...
Show moreIn nature, microscopic surface textures impact useful function, such as the drag reduction of shark skin (Dean & Bhushan, 2010) and superhydrophobicity of the lotus leaf(Pan, Kota, Mabry, & Tuteja, 2013). In this study, we explore these phenomena by re-creating microscopic surface textures via the method of interfacial flow instability in drying polyvinylidene fluoride (PVDF) acetone solutions. In general, PVDF films can be made using either spin coating or electrospray deposition with various weight concentrations in acetone. In order to study the morphology of the porous structure of PVDF films, wet deposition samples were fabricated by spin coating or near-field electrospray. Possible theories are discussed and examined to explain the formation of these porous structures resulting in development of a well-controlled method to create porous PVDF films with various pore sizes and pore densities. All samples are characterized and found to exhibit superhydrophobicity and drag reduction. To connect porous PVDF film morphology to the established field of dry particle fabrication, PVDF particle synthesis by far-field electrospray is also reviewed and discussed. An established method to generate polymer particles of different morphologies in other polymers (Almeria-Diez, 2012) by electrospray drying is confirmed using PVDF as well. Due to the ability of scalable and re-configurable electrospray, the microscopic surface textures can be applied to areas of any size to reduce drag or impart water-repelling properties.
Show less - Date Issued
- 2013
- Identifier
- CFH0004479, ucf:45066
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004479
- Title
- ON THE NATURE OF THE FLOW IN A SEPARATED ANNULAR DIFFUSER.
- Creator
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Dunn, Jason, Kapat, Jayanta, University of Central Florida
- Abstract / Description
-
The combustor-diffuser system remains one of the most studied sections of the turbomachine. Most of these investigations are due to the fact that quite a bit of flow diffusion is required in this section as the high speed flow exits the compressor and must be slowed down to enter the combustor. Like any diffusion process there is the chance for the development of an unfavorable adverse pressure gradient that can lead to flow separation; a cause of drastic losses within a turbine. There are...
Show moreThe combustor-diffuser system remains one of the most studied sections of the turbomachine. Most of these investigations are due to the fact that quite a bit of flow diffusion is required in this section as the high speed flow exits the compressor and must be slowed down to enter the combustor. Like any diffusion process there is the chance for the development of an unfavorable adverse pressure gradient that can lead to flow separation; a cause of drastic losses within a turbine. There are two diffusion processes in the combustor-diffuser system: The flow first exits the compressor into a pre-diffuser, or compressor discharge diffuser. This diffuser is responsible for a majority of the pressure recovery. The flow then exits the pre-diffuser by a sudden expansion into the dump diffuser. The dump diffuser comprises the majority of the losses, but is necessary to reduce the fluid velocity within acceptable limits for combustion. The topic of active flow control is gaining interest in the industry because such a technique may be able to alleviate some of the requirements of the dump diffuser. If a wider angle pre-diffuser with separation control were used the fluid velocity would be slowed more within that region without significant losses. Experiments were performed on two annular diffusers to characterize the flow separation to create a foundation for future active flow control techniques. Both diffusers had the same fully developed inlet flow condition, however, the expansion of the two diffusers differed such that one diffuser replicated a typical compressor discharge diffuser found in a real machine while the other would create a naturally separated flow along the outer wall. Both diffusers were tested at two Reynolds numbers, 5x104 and 1x105, with and without a vertical wall downstream of the exit to replicate the dump diffuser that re-directs the flow from the pre-diffuser outlet to the combustor. Static pressure measurements were obtained along the OD and ID wall of the diffusers to determine the recovered pressure throughout the diffuser. In addition to these measurements, tufts were used to visualize the flow. A turbulent CFD model was also created to compare against experimental results. In the end, the results were validated against empirical data as well as the CFD model. It was shown that the location of the vertical wall was directly related to the amount of separation as well as the separation characteristics. These findings support previous work and help guide future work for active flow control in a separated annular diffuser both computationally and experimentally.
Show less - Date Issued
- 2009
- Identifier
- CFE0002953, ucf:47944
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002953
- Title
- Experimental and Numerical Study of Endwall Film Cooling.
- Creator
-
Mahadevan, Srikrishna, Kapat, Jayanta, Verma, Shashi, Vasu Sumathi, Subith, Ahmed, Kareem, Shivamoggi, Bhimsen, University of Central Florida
- Abstract / Description
-
This research work investigates the thermal performance of a film-cooled gas turbine endwall under two different mainstream flow conditions. In the first part of the research investigation, the effect of unsteady passing wakes on a film-cooled pitchwise-curved surface (representing an endwall without airfoils) was experimentally studied for heat transfer characteristics on a time-averaged basis. The temperature sensitive paint technique was used to obtain the local temperatures on the test...
Show moreThis research work investigates the thermal performance of a film-cooled gas turbine endwall under two different mainstream flow conditions. In the first part of the research investigation, the effect of unsteady passing wakes on a film-cooled pitchwise-curved surface (representing an endwall without airfoils) was experimentally studied for heat transfer characteristics on a time-averaged basis. The temperature sensitive paint technique was used to obtain the local temperatures on the test surface. The required heat flux input was provided using foil heaters. Discrete film injection was implemented on the test surface using cylindrical holes with a streamwise inclination angle of 35? and no compound angle relative to the mean approach velocity vector. The passing wakes increased the heat transfer coefficients at both the wake passing frequencies that were experimented. Due to the increasing film cooling jet turbulence and strong jet-mainstream interaction at higher blowing ratios, the heat transfer coefficients were amplified. A combination of film injection and unsteady passing wakes resulted in a maximum pitch-averaged and centerline heat transfer augmentation of ? 28% and 31.7% relative to the no wake and no film injection case. The second part of the research study involves an experimental and numerical analysis of secondary flow and coolant film interaction in a high subsonic annular cascade with a maximum isentropic throat Mach number of ? 0.68. Endwall (platform) thermal protection is provided using discrete cylindrical holes with a streamwise inclination angle of 30? and no compound angle relative to the mean approach velocity vector. The surface flow visualization on the inner endwall provided the location of the saddle point and the three-dimensional separation lines. Computational predictions showed that the leading-edge horseshoe vortex was confined to approximately 1.5% of the airfoil span for the no film injection case and intensified with low momentum film injection. At the highest blowing ratio, the film cooling jet weakened the horseshoe vortex at the leading-edge plane. The passage vortex was intensified with coolant injection at all blowing ratios. It was seen that increasing average blowing ratio improved the film effectiveness on the endwall. The discharge coefficients calculated for each film cooling hole indicated significant non-uniformity in the coolant discharge at lower blowing ratios and the strong dependence of discharge coefficients on the mainstream static pressure and the location of three-dimensional separation lines. Near the airfoil suction side, a region of coalesced film cooling jets providing close to uniform film coverage was observed, indicative of the mainstream acceleration and the influence of three-dimensional separation lines.
Show less - Date Issued
- 2015
- Identifier
- CFE0005973, ucf:50775
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005973
- Title
- Inverse-Consistent Determination of Young's Modulus of Human Lung.
- Creator
-
Seyfi Noferest, Behnaz, Ilegbusi, Olusegun, Santhanam, Anand, Kassab, Alain, Moslehy, Faissal, University of Central Florida
- Abstract / Description
-
Human lung undergoes respiration-induced deformation due to sequential inhalation and exhalation. Accurate determination of lung deformation is crucial for tumor localization and targeted radiotherapy in patients with lung cancer. Numerical modeling of human lung dynamics based on underlying physics and physiology enables simulation and virtual visualization of lung deformation. Dynamical modeling is numerically complicated by the lack of information on lung elastic behavior, structural...
Show moreHuman lung undergoes respiration-induced deformation due to sequential inhalation and exhalation. Accurate determination of lung deformation is crucial for tumor localization and targeted radiotherapy in patients with lung cancer. Numerical modeling of human lung dynamics based on underlying physics and physiology enables simulation and virtual visualization of lung deformation. Dynamical modeling is numerically complicated by the lack of information on lung elastic behavior, structural heterogeneity as well as boundary constrains. This study integrates physics-based modeling and image-based data acquisition to develop the patient-specific biomechanical model and consequently establish the first consistent Young's modulus (YM) of human lung. This dissertation has four major components: (i) develop biomechanical model for computation of the flow and deformation characteristics that can utilize subject-specific, spatially-dependent lung material property; (ii) develop a fusion algorithm to integrate deformation results from a deformable image registration (DIR) and physics-based modeling using the theory of Tikhonov regularization; (iii) utilize fusion algorithm to establish unique and consistent patient specific Young's modulus and; (iv) validate biomechanical model utilizing established patient-specific elastic property with imaging dataThe simulation is performed on three dimensional lung geometry reconstructed from four-dimensional computed tomography (4DCT) dataset of human subjects. The heterogeneous Young's modulus is estimated from a linear elastic deformation model with the same lung geometry and 4D lung DIR. The biomechanical model adequately predicts the spatio-temporal lung deformation, consistent with data obtained from imaging. The accuracy of the numerical solution is enhanced through fusion with the imaging data beyond the classical comparison of the two sets of data. Finally, the fused displacement results are used to establish unique and consistent patient-specific elastic property of the lung.
Show less - Date Issued
- 2015
- Identifier
- CFE0006391, ucf:51512
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006391
- Title
- Thermally induced motion, collision and mixing of levitated droplets.
- Creator
-
Davanlou, Ashkan, Kumar, Ranganathan, Cho, Hyoung Jin, Deng, Weiwei, Mansy, Hansen, Shivamoggi, Bhimsen, University of Central Florida
- Abstract / Description
-
This dissertation investigates the motion of a levitated droplet experimentally and analytically against the Marangoni flow in an immiscible outer fluid at higher speeds than is possible currently. Based on our earlier experiments, when a droplet is released from a height of 1.5 (-) 4 times its diameter from the liquid surface, it can overcome the impact and stay levitated at the liquid-air interface due to the existence of an air gap between the droplet and the liquid film. In order to...
Show moreThis dissertation investigates the motion of a levitated droplet experimentally and analytically against the Marangoni flow in an immiscible outer fluid at higher speeds than is possible currently. Based on our earlier experiments, when a droplet is released from a height of 1.5 (-) 4 times its diameter from the liquid surface, it can overcome the impact and stay levitated at the liquid-air interface due to the existence of an air gap between the droplet and the liquid film. In order to explain this behavior of droplet traveling against the counter-current motion, we propose a simple approach: first, the Marangoni convection inside the thin film is considered without the droplet floating on the surface. By using a level-set method and solving the Navier-Stokes equation, the free surface velocity and deformation are calculated. Then, these quantities are used to solve for droplet velocity and drag coefficient simultaneously using a force balance. In order to compare the simulation results, experiments with levitated water droplets on an immiscible carrier liquid, FC-43, were conducted for various temperature gradients, and droplet velocities were measured at different locations using high-speed imaging. The experimental results are in good agreement with the developed theoretical model. For a Reynolds number range of 2-32, it is shown that the drag coefficients are up to 66% higher than those for the fully immersed sphere at the same Reynolds numbers. A correlation is proposed to calculate the drag coefficient of levitated droplets for various temperature drops across the channel.For the first time, it is shown that it is possible to realize the natural coalescence of droplets through Marangoni effect without any external stimulation, and deliver the coalesced droplet to a certain destination through the use of surface tension gradients. The effects of the various shapes and sizes upon collision are studied. Regions of coalescence and stretching separation of colliding droplets are delineated based on Weber number and impact number. The existence of the transition line between coalescence and stretching separation in this passive mode of transport is similar to what was observed in the literature for forced coalescence at significantly higher Weber numbers. It is also found that a thermocapillary environment improves the mixing process. In order to illustrate and quantify the mixing phenomenon, the dispensed droplets were made of potassium hydroxide and phenolphthalein which is used as a pH indicator. The experiments show the possibility to reach mixing rates as high as 74% within 120 ms. This study offers new insight to thermo-coalescence and demonstrates how natural coalescence could be used to transport, mix and collect biochemical assays more efficiently. The results of this research can be engineered to enhance the performance of self-cleaning surfaces and micro-total analysis systems ((&)#181;TAS), where sample transport, filtration, chemical reactions, separation and detection are of great interest.
Show less - Date Issued
- 2015
- Identifier
- CFE0006213, ucf:51106
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006213
- Title
- Climate and landscape controls on seasonal water balance at the watershed scale.
- Creator
-
Chen, Xi, Wang, Dingbao, Chopra, Manoj, Hagen, Scott, Sumner, David, University of Central Florida
- Abstract / Description
-
The main goal of this dissertation is to develop a seasonal water balance model for evaporation, runoff and water storage change based on observations from a large number of watersheds, and further to obtain a comprehensive understanding on the dominant physical controls on intra-annual water balance. Meanwhile, the method for estimating evaporation and water storage based on recession analysis is improved by quantifying the seasonal pattern of the partial contributing area and contributing...
Show moreThe main goal of this dissertation is to develop a seasonal water balance model for evaporation, runoff and water storage change based on observations from a large number of watersheds, and further to obtain a comprehensive understanding on the dominant physical controls on intra-annual water balance. Meanwhile, the method for estimating evaporation and water storage based on recession analysis is improved by quantifying the seasonal pattern of the partial contributing area and contributing storage to base flow during low flow seasons. A new method for quantifying seasonality is developed in this research. The difference between precipitation and soil water storage change, defined as effective precipitation, is considered as the available water. As an analog to climate aridity index, the ratio between monthly potential evaporation and effective precipitation is defined as a monthly aridity index. Water-limited or energy-limited months are defined based on the threshold of 1. Water-limited or energy-limited seasons are defined by aggregating water-limited or energy-limited months, respectively. Seasonal evaporation is modeled by extending the Budyko hypothesis, which is originally for mean annual water balance; while seasonal surface runoff and base flow are modeled by generalizing the proportionality hypothesis originating from the SCS curve number model for surface runoff at the event scale. The developed seasonal evaporation and runoff models are evaluated based on watersheds across the United States. For the extended Budyko model, 250 out of 277 study watersheds have a Nash-Sutcliff efficiency (NSE) higher than 0.5, and for the seasonal runoff model, 179 out of 203 study watersheds have a NSE higher than 0.5. Furthermore, the connection between the seasonal parameters of the developed model and a variety of physical factors in the study watersheds is investigated. For the extended Budyko model, vegetation is identified as an important physical factor that related to the seasonal model parameters. However, the relationship is only strong in water-limited seasons, due to the seasonality of the vegetation coverage. In the seasonal runoff model, the key controlling factors for wetting capacity and initial wetting are soil hydraulic conductivity and maximum rainfall intensity respectively. As for initial evaporation, vegetation is identified as the strongest controlling factor. Besides long-term climate, this research identifies the key controlling factors on seasonal water balance: the effects of soil water storage, vegetation, soil hydraulic conductivity, and storminess. The developed model is applied to the Chipola River watershed and the Apalachicola River basin in Florida for assessing potential climate change impact on the seasonal water balance. The developed model performance is compared with a physically-based distributed hydrologic model of the Soil Water Assessment Tool, showing a good performance for seasonal runoff, evaporation and storage change.
Show less - Date Issued
- 2014
- Identifier
- CFE0005313, ucf:50519
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005313
- Title
- Computational Fluid Dynamics Simulation of United Launch Alliance Delta IV Hydrogen Plume Mitigation Strategies.
- Creator
-
Guimond, Stephen, Kassab, Alain, Divo, Eduardo, Vasu Sumathi, Subith, University of Central Florida
- Abstract / Description
-
During the launch sequence of the United Launch Alliance Delta IV launch vehicle, large amounts of pure hydrogen are introduced into the launch table and ignited by Radial-Outward-Firing-Igniters (ROFIs). This ignition results in a significant flame, or plume, that rises upwards out of the launch table due to buoyancy. The presence of the plume causes increased and unwanted heat loads on the surface of the vehicle. A proposed solution is to add a series of fans and structures to the existing...
Show moreDuring the launch sequence of the United Launch Alliance Delta IV launch vehicle, large amounts of pure hydrogen are introduced into the launch table and ignited by Radial-Outward-Firing-Igniters (ROFIs). This ignition results in a significant flame, or plume, that rises upwards out of the launch table due to buoyancy. The presence of the plume causes increased and unwanted heat loads on the surface of the vehicle. A proposed solution is to add a series of fans and structures to the existing launch table configuration that are designed to inject ambient air in the immediate vicinity of the launch vehicle's nozzles to suppress the plume rise. In addition to the air injection, secondary fan systems can be added around the launch table openings to further suppress the hydrogen plume. The proposed air injection solution is validated by computational fluid dynamics simulations that capture the combustion and compressible flow observed during the Delta IV launch sequence. A solution to the hydrogen plume problem will have direct influence on the efficiency of the launch vehicle: lower heat loads result in thinner vehicle insulation and thus allow for a larger payload mass. Current results show that air injection around the launch vehicle nozzles and air suppression around the launch table openings significantly reduces the size of the plume around the launch vehicle prior to liftoff.
Show less - Date Issued
- 2014
- Identifier
- CFE0005500, ucf:50345
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005500
- Title
- GENETIC AND PHENOTYPIC EVOLUTION IN THE ORNATE CHORUS FROG (PSEUDACRIS ORNATA): TESTING THE RELATIVE ROLES OF NATURAL SELECTION, MIGRATION, AND GENETIC DRIFT.
- Creator
-
Degner, Jacob, Hoffman, Eric, University of Central Florida
- Abstract / Description
-
Understanding how migration, genetic drift, and natural selection interact to maintain the genetic and phenotypic variation we observe in natural populations is a central goal of population genetics. Amphibians provide excellent model organisms for investigating the interplay between these evolutionary forces because amphibians are generally characterized by limited dispersal abilities, high philopatry, and are obligately associated with the areas around suitable habitats (e.g. breeding ponds...
Show moreUnderstanding how migration, genetic drift, and natural selection interact to maintain the genetic and phenotypic variation we observe in natural populations is a central goal of population genetics. Amphibians provide excellent model organisms for investigating the interplay between these evolutionary forces because amphibians are generally characterized by limited dispersal abilities, high philopatry, and are obligately associated with the areas around suitable habitats (e.g. breeding ponds). Thus, on relatively small geographic scales, the relative effects of all of these evolutionary forces can be studied together. Here, we study the interaction of migration, genetic drift, natural selection, and historical process in the ornate chorus frog (Pseudacris ornata). We report the development and characterization of 10 polymorphic microsatellite genetic markers. Number of alleles per locus ranged from 2 to 21 averaging 9.2 and expected heterozygosities ranged from 0.10 to 0.97 averaging 0.52. However, in an analysis of two populations, three locus-by-population comparisons exhibited significant heterozygote deficiencies and indicated that null alleles may be present some loci. Furthermore, we characterized genetic structure and historical biogeographic patterns in P. ornata using these microsatellite markers along with mitochondrial DNA sequence data. Our data indicate that in these frogs, migration may play a large role in determining population structure as pairwise estimates of FST were relatively small ranging from 0.04 to 0.12 (global FST = 0.083). Additionally, we observed an overall pattern of isolation-by-distance in neutral genetic markers across the species range. Moreover, our data suggest that the Apalachicola River basin does not impede gene flow in P. ornata as it does in many vertebrate taxa. Interestingly, we identified significant genetic structure between populations separated by only 6 km. However, this fine scale genetic structure was only present in the more urbanized of two widespread sampling localities. Finally, in this study, we demonstrated that there was a significant correlation between the frequency of green frogs and latitude. There was a higher frequency of green frogs in southern samples and a lower frequency of green frogs in northern samples. However, when we interpreted this phenotypic cline in light of the overall pattern of isolation-by-distance, it was apparent that the neutral evolutionary forces of genetic drift and migration could explain the cline, and the invocation of natural selection was not necessary.
Show less - Date Issued
- 2007
- Identifier
- CFE0001721, ucf:47319
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001721
- Title
- PREDICTING COGNITIVE WORKLOAD WITH MEASURES FROM FUNCTIONAL NEAR-INFRARED SPECTROSCOPY (FNIRS) AND HEART RATE.
- Creator
-
Duany, John, Bohil, Corey, University of Central Florida
- Abstract / Description
-
The objective of this study was to assess low to high levels of Cognitive Workload by measuring heart rate and cortical blood flow in real-time. Four conditions were implemented into a within-subjects experimental design. Two conditions of difficulty and two conditions of trial order were used to illicit different levels of workload which will be analyzed with psychophysiological equipment. Functional Near-Infrared Spectroscopy (fNIRS) has become more prominent for measuring the blood...
Show moreThe objective of this study was to assess low to high levels of Cognitive Workload by measuring heart rate and cortical blood flow in real-time. Four conditions were implemented into a within-subjects experimental design. Two conditions of difficulty and two conditions of trial order were used to illicit different levels of workload which will be analyzed with psychophysiological equipment. Functional Near-Infrared Spectroscopy (fNIRS) has become more prominent for measuring the blood oxygenation levels in the prefrontal cortex of individuals operating in hazardous work environments, students with learning disabilities, and in research for military training. This is due to the fNIR device being highly mobile, inexpensive, and able to produce a high-spatial resolution of the dorsolateral prefrontal cortex during executive functioning. Heart Rate will be measured by an Electrocardiogram, which will be used in concordance with fNIR oxygenation levels to predict if an individual is in a condition that produces low or high mental workload. Successfully utilizing heart rate and blood oxygenation data as predictors of cognitive workload may validate implementing multiple physiological devices together in real-time and may be a more accurate solution for preventing excessive workload.
Show less - Date Issued
- 2013
- Identifier
- CFH0004478, ucf:45070
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004478
- Title
- Dynamic Behavior and Performance of Different Types of Multi-Effect Desalination Plants.
- Creator
-
Abdelkareem, Mohamed, Chow, Louis, Mansy, Hansen, Das, Tuhin, Duranceau, Steven, University of Central Florida
- Abstract / Description
-
Water and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of...
Show moreWater and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of primary energy and electricity consumption compared to other thermal desalination systems. The motivation for this research is to address thermo-economics and dynamic behavior of different MED feed configurations with/without vapor compression (VC). A new formulation for the steady-state models was developed to simulate different MED systems. Adding a thermal vapor compressor (TVC) or mechanical vapor compression (MVC) unit to the MED system is also studied to show the advantage of this type of integration. For MED-TVC systems, results indicate that the parallel cross feed (PCF) configuration has better performance characteristics than other configurations. A similar study of MED-MVC systems indicates that the PCF and forward feed (FF) configurations require less work to achieve equal distillate production. Reducing the steam temperature supplied by the MVC unit leads to an increase in second law efficiency and a decrease in specific power consumption (SPC) and total water price. Following the fact that the MED may be exposed to fluctuations (disturbances) in input parameters during operation. Therefore, there is a requirement to analyze their transient behavior. In the current study, the dynamic model is developed based on solving the basic conservation equations of mass, energy, and salt. In the case of heat source disturbance, MED plants operating in the backward feed (BF) may be exposed to shut down due to flooding in the first effect. For all applied disturbances, the change in the brine level is the slowest compared to the changes in vapor temperature, and brine and vapor flow rates. For MED-TVC, it is recommended to limit the seawater cooling flow rate reduction to under 12% of the steady-state value to avoid dryout in the evaporators. A reduction in the motive steam flow rate and cooling seawater temperature of more than 20% and 35% of steady-state values, respectively, may lead to flooding in evaporators and plant shutdown. Simultaneous combinations of two different disturbances with opposing effects have only a modest effect on plant operation and they can be used to control and mitigate the flooding/drying effects caused by the disturbances. For the MED-MVC, the compressor work reduction could lead to plant shutdown, while a reduction in the seawater temperature will lead to a reduction in plant production and an increase in SPC.
Show less - Date Issued
- 2019
- Identifier
- CFE0007423, ucf:52735
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007423
- Title
- Fusing Freight Analysis Framework and Transearch Data: An Econometric Data Fusion Approach.
- Creator
-
Momtaz, Salah Uddin, Eluru, Naveen, Abdel-Aty, Mohamed, Anowar, Sabreena, Zheng, Qipeng, University of Central Florida
- Abstract / Description
-
A major hurdle in freight demand modeling has always been the lack of adequate data on freight movements for different industry sectors for planning applications. Freight Analysis Framework (FAF), and Transearch (TS) databases contain annualized commodity flow data. The primary motivation for our study is the development of a fused database from FAF and TS to realize transportation network flows at a fine spatial resolution (county-level) while accommodating for production and consumption...
Show moreA major hurdle in freight demand modeling has always been the lack of adequate data on freight movements for different industry sectors for planning applications. Freight Analysis Framework (FAF), and Transearch (TS) databases contain annualized commodity flow data. The primary motivation for our study is the development of a fused database from FAF and TS to realize transportation network flows at a fine spatial resolution (county-level) while accommodating for production and consumption behavioral trends (provided by TS). Towards this end, we formulate and estimate a joint econometric model framework grounded in maximum likelihood approach to estimate county-level commodity flows. The algorithm is implemented for the commodity flow information from 2012 FAF and 2011 TS databases to generate transportation network flows for 67 counties in Florida. The data fusion process considers several exogenous variables including origin-destination indicator variables, socio-demographic and socio-economic indicators, and transportation infrastructure indicators. Subsequently, the algorithm is implemented to develop freight flows for the Florida region considering inflows and outflows across the US and neighboring countries. The base year models developed are employed to predict future year data for years 2015 through 2040 in 5-year increments at the same spatial level. Furthermore, we disaggregate the county level flows obtained from algorithm to a finer resolution - statewide transportation analysis zone (SWTAZ) defined by the FDOT. The disaggregation process allocates truck-based commodity flows from a 79-zone system to an 8835-zone system. A two-stage factor multiplication method is proposed to disaggregate the county flow to SWTAZ flow. The factors are estimated both at the origin and destination level using a random utility factional split model approach. Eventually, we conducted a sensitivity analysis of the parameterization by evaluating the model structure for different numbers of intermediate stops in a route and/or the number of available routes for the origin-destinations.
Show less - Date Issued
- 2018
- Identifier
- CFE0007763, ucf:52384
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007763
- Title
- Understanding How, Where and How much Freight Flows Using 2012 Commodity Flow Survey Data.
- Creator
-
Keya, Nowreen, Eluru, Naveen, Abdel-Aty, Mohamed, Anowar, Sabreena, Uddin, Nizam, University of Central Florida
- Abstract / Description
-
In recent years, with increased economic globalization, growing e-commerce and internet based shopping, freight movement patterns are undergoing a transformative change. The shipment size distribution is moving towards a higher share of smaller size shipments affecting transportation mode and vehicle type requirements. In addition, freight transportation mode is closely affected by the destination location (and its attributes). In our dissertation, we contribute to freight research by...
Show moreIn recent years, with increased economic globalization, growing e-commerce and internet based shopping, freight movement patterns are undergoing a transformative change. The shipment size distribution is moving towards a higher share of smaller size shipments affecting transportation mode and vehicle type requirements. In addition, freight transportation mode is closely affected by the destination location (and its attributes). In our dissertation, we contribute to freight research by developing a comprehensive framework to examine the how, where and how much freight flows in US. Specifically, we study the following dimensions of freight flow: (1) transportation mode, (2) mode and shipment weight choice and (3) mode and destination choice. For analyzing mode choice, an advanced discrete freight mode choice model- a hybrid utility-regret based model system has been estimated while accommodating for shipper level unobserved heterogeneity. To demonstrate the applicability of the proposed model system, detailed policy analyses examining the implementation of vehicle fleet automation and rerouting of freight movements away from a region were considered. While shipment weight could be considered as an explanatory variable in modeling mode choice (or vice-versa), it is more likely that the decision of mode and shipment choice is a simultaneous process. This joint decision is investigated both simultaneously employing a closed form copula structure and sequentially employing latent segmentation based sequence model. For destination choice, we investigated the connection between shipping mode and destination choice of shipment in a latent segmentation based sequential form. The analysis for the dissertation is conducted using 2012 Commodity Flow Survey (CFS) data.
Show less - Date Issued
- 2018
- Identifier
- CFE0007574, ucf:52569
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007574
- Title
- Automated Synthesis of Unconventional Computing Systems.
- Creator
-
Hassen, Amad Ul, Jha, Sumit Kumar, Sundaram, Kalpathy, Fan, Deliang, Ewetz, Rickard, Rahman, Talat, University of Central Florida
- Abstract / Description
-
Despite decades of advancements, modern computing systems which are based on the von Neumann architecture still carry its shortcomings. Moore's law, which had substantially masked the effects of the inherent memory-processor bottleneck of the von Neumann architecture, has slowed down due to transistor dimensions nearing atomic sizes. On the other hand, modern computational requirements, driven by machine learning, pattern recognition, artificial intelligence, data mining, and IoT, are growing...
Show moreDespite decades of advancements, modern computing systems which are based on the von Neumann architecture still carry its shortcomings. Moore's law, which had substantially masked the effects of the inherent memory-processor bottleneck of the von Neumann architecture, has slowed down due to transistor dimensions nearing atomic sizes. On the other hand, modern computational requirements, driven by machine learning, pattern recognition, artificial intelligence, data mining, and IoT, are growing at the fastest pace ever. By their inherent nature, these applications are particularly affected by communication-bottlenecks, because processing them requires a large number of simple operations involving data retrieval and storage. The need to address the problems associated with conventional computing systems at the fundamental level has given rise to several unconventional computing paradigms. In this dissertation, we have made advancements for automated syntheses of two types of unconventional computing paradigms: in-memory computing and stochastic computing. In-memory computing circumvents the problem of limited communication bandwidth by unifying processing and storage at the same physical locations. The advent of nanoelectronic devices in the last decade has made in-memory computing an energy-, area-, and cost-effective alternative to conventional computing. We have used Binary Decision Diagrams (BDDs) for in-memory computing on memristor crossbars. Specifically, we have used Free-BDDs, a special class of binary decision diagrams, for synthesizing crossbars for flow-based in-memory computing. Stochastic computing is a re-emerging discipline with several times smaller area/power requirements as compared to conventional computing systems. It is especially suited for fault-tolerant applications like image processing, artificial intelligence, pattern recognition, etc. We have proposed a decision procedures-based iterative algorithm to synthesize Linear Finite State Machines (LFSM) for stochastically computing non-linear functions such as polynomials, exponentials, and hyperbolic functions.
Show less - Date Issued
- 2019
- Identifier
- CFE0007648, ucf:52462
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007648
- Title
- Semi-Analytical Solutions of Non-linear Differential Equations Arising in Science and Engineering.
- Creator
-
Dewasurendra, Mangalagama, Vajravelu, Kuppalapalle, Mohapatra, Ram, Rollins, David, Kumar, Ranganathan, University of Central Florida
- Abstract / Description
-
Systems of coupled non-linear differential equations arise in science and engineering are inherently nonlinear and difficult to find exact solutions. However, in the late nineties, Liao introduced Optimal Homotopy Analysis Method (OHAM), and it allows us to construct accurate approximations to the systems of coupled nonlinear differential equations.The drawback of OHAM is, we must first choose the proper auxiliary linear operator and then solve the linear higher-order deformation equation by...
Show moreSystems of coupled non-linear differential equations arise in science and engineering are inherently nonlinear and difficult to find exact solutions. However, in the late nineties, Liao introduced Optimal Homotopy Analysis Method (OHAM), and it allows us to construct accurate approximations to the systems of coupled nonlinear differential equations.The drawback of OHAM is, we must first choose the proper auxiliary linear operator and then solve the linear higher-order deformation equation by spending lots of CPU time. However, in the latest innovation of Liao's " Method of Directly Defining inverse Mapping (MDDiM)" which he introduced to solve a single nonlinear ordinary differential equation has great freedom to define the inverse linear map directly. In this way, one can solve higher order deformation equations quickly, and it is unnecessary to calculate an inverse linear operator.Our primary goal is to extend MDDiM to solve systems of coupled nonlinear ordinary differential equations. In the first chapter, we will introduce MDDiM and briefly discuss the advantages of MDDiM Over OHAM. In the second chapter, we will study a nonlinear coupled system using OHAM. Next three chapters, we will apply MDDiM to coupled non-linear systems arise in mechanical engineering to study fluid flow and heat transfer. In chapter six we will apply this novel method to study coupled non-linear systems in epidemiology to investigate how diseases spread throughout time. In the last chapter, we will discuss our conclusions and will propose some future work. Another main focus is to compare MDDiM with OHAM.
Show less - Date Issued
- 2019
- Identifier
- CFE0007624, ucf:52551
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007624
- Title
- ARCHITECTURAL SUPPORT FOR IMPROVING COMPUTER SECURITY.
- Creator
-
Kong, Jingfei, Zhou, Huiyang, University of Central Florida
- Abstract / Description
-
Computer security and privacy are becoming extremely important nowadays. The task of protecting computer systems from malicious attacks and potential subsequent catastrophic losses is, however, challenged by the ever increasing complexity and size of modern hardware and software design. We propose several methods to improve computer security and privacy from architectural point of view. They provide strong protection as well as performance efficiency. In our first approach, we propose a new...
Show moreComputer security and privacy are becoming extremely important nowadays. The task of protecting computer systems from malicious attacks and potential subsequent catastrophic losses is, however, challenged by the ever increasing complexity and size of modern hardware and software design. We propose several methods to improve computer security and privacy from architectural point of view. They provide strong protection as well as performance efficiency. In our first approach, we propose a new dynamic information flow method to protect systems from popular software attacks such as buffer overflow and format string attacks. In our second approach, we propose to deploy encryption schemes to protect the privacy of an emerging non-volatile main memory technology ÃÂ phase change memory (PCM). The negative impact of the encryption schemes on PCM lifetime is evaluated and new methods including a new encryption counter scheme and an efficient error correct code (ECC) management are proposed to improve PCM lifetime. In our third approach, we deconstruct two previously proposed secure cache designs against software data-cache-based side channel attacks and demonstrate their weaknesses. We propose three hardware-software integrated approaches as secure protections against those data cache attacks. Also we propose to apply them to protect instruction caches from similar threats. Furthermore, we propose a simple change to the update policy of Branch Target Buffer (BTB) to defend against BTB attacks. Our experiments show that our proposed schemes are both security effective and performance efficient.
Show less - Date Issued
- 2010
- Identifier
- CFE0003211, ucf:48589
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003211
- Title
- Signals Delivered By Interleukin-7 Regulate The Activities Of Bim And JunD In T Lymphocytes.
- Creator
-
Ruppert, Shannon, Khaled, Annette, Self, William, Zervos, Antonis, Teter, Kenneth, University of Central Florida
- Abstract / Description
-
Interleukin-7 (IL-7) is an essential cytokine for lymphocyte growth that has the potential for promoting proliferation and survival. While the survival and proliferative functions of IL-7 are well established, the identities of IL-7 signaling components in pathways other than JAK/STAT, that accomplish these tasks remain poorly defined. To this end, we used IL-7 dependent T-cells to examine those components necessary for cell growth and survival. Our studies revealed two novel signal...
Show moreInterleukin-7 (IL-7) is an essential cytokine for lymphocyte growth that has the potential for promoting proliferation and survival. While the survival and proliferative functions of IL-7 are well established, the identities of IL-7 signaling components in pathways other than JAK/STAT, that accomplish these tasks remain poorly defined. To this end, we used IL-7 dependent T-cells to examine those components necessary for cell growth and survival. Our studies revealed two novel signal transducers of the IL-7 growth signal: BimL and JunD. IL-7 promoted the activity of JNK (Jun N-terminal Kinase), and that JNK, in turn, drove the expression of JunD, a component of the Activating Protein 1 (AP-1) transcription factors. Inhibition of JNK/JunD blocked glucose uptake and HXKII gene expression, indicating that this pathway was responsible for promoting HXKII expression. After a bioinformatics survey to reveal possible JunD-regulated genes activated early in the IL-7 signaling cascade, our search revealed that JunD could control the expression of proteins involved in signal transduction, cell survival and metabolism, including Pim-1. Pim-1, an IL-7 induced protein, was inhibited upon JNK or JunD inhibition. Our hypothesis that JunD positively regulated proliferation was confirmed when the proliferation of primary CD8+ T-cells cultured with IL-7 was impaired upon treatment with JunD siRNA. These results show that the IL-7 signal is more complex than the JAK/STAT pathway, activating JNK and JunD to induce rapid growth through the expression of metabolic factors like HXKII and Pim-1. When metabolic activities are inhibited, cells undergo autophagy, or cell scavenging, to provide essential nutrients. Pro-apoptotic Bim was evaluated for its involvement in autophagy. Bim is a BH3-only member of the Bcl-2 family that contributes to T-cell death. Partial rescue of T-cells occurs when Bim and the interleukin-7 receptor are deleted, implicating Bim in IL-7-deprived T-cell apoptosis. Alternative splicing results in three different isoforms: BimEL, BimL, and BimS. To study the effect of Bim deficiency and define the function of the major isoforms, Bim-containing and Bim-deficient T-cells, dependent on IL-7 for growth, were used. Loss of Bim in IL-7-deprived T-cells delayed apoptosis, but blocked the degradative phase of autophagy. The conversion of LC3-I to LC3-II was observed in Bim-deficient T-cells, but p62, which is degraded in autolysosomes, accumulated. To explain this, BimL, was found to support acidification of lysosomes associated with autophagic vesicles. Key findings showed that inhibition of lysosomal acidification accelerated death upon IL-7 withdrawal only in Bim-containing T-cells, indicating that in these cells autophagy was protective. IL-7 dependent T-cells lacking Bim were insensitive to inhibition of autophagy or lysosomal acidification. BimL co-immunoprecipitated with dynein and Lamp1-containing vesicles, indicating BimL could be an adaptor for dynein to facilitate loading of lysosomes. In Bim deficient T-cells, lysosome-tracking probes revealed vesicles of less acidic pH. Over-expression of BimL restored acidic vesicles in Bim deficient T-cells, while other isoforms, BimEL and BimS, associated with intrinsic cell death. These results reveal a novel role for BimL in lysosomal positioning that may be required for the formation of functional autolysosomes during autophagy.
Show less - Date Issued
- 2012
- Identifier
- CFE0004435, ucf:49331
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004435