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Articles 31 - 60 of 113
Full-Text Articles in Engineering
Working With Complexity: A Participatory Systems-Based Process For Planning And Evaluating Rural Water, Sanitation And Hygiene Services, Jeffrey P. Walters, Kate Neely, Karla Pozo
Working With Complexity: A Participatory Systems-Based Process For Planning And Evaluating Rural Water, Sanitation And Hygiene Services, Jeffrey P. Walters, Kate Neely, Karla Pozo
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Individuals working within the water, sanitation and hygiene for development (WASH) sector grapple daily with complex technical, social, economic, and environmental issues that often produce unexpected outcomes that are difficult to plan for and resolve. Here we propose a method we are calling the ‘Participatory Systems-based Planning and Evaluation Process’ (PS-PEP) that combines structural factor analysis and collaborative modeling to guide teams of practitioners, researchers, and other stakeholders through a process of modeling and interpreting how factors systemically and dynamically influence sustained access to WASH services. The use and utility of the PS-PEP is demonstrated with a regional team of …
Beneficial Aerodynamic Effect Of Wing Scales On The Climbing Flight Of Butterflies, Nathan Slegers, Michael Heilman, Jacob Cranford, Amy Lang, John Yoder, Maria Laura Habegger
Beneficial Aerodynamic Effect Of Wing Scales On The Climbing Flight Of Butterflies, Nathan Slegers, Michael Heilman, Jacob Cranford, Amy Lang, John Yoder, Maria Laura Habegger
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
It is hypothesized that butterfly wing scale geometry and surface patterning may function to improve aerodynamic efficiency. In order to investigate this hypothesis, a method to measure butterfly flapping kinematics optically over long uninhibited flapping sequences was developed. Statistical results for the climbing flight flapping kinematics of 11 butterflies, based on a total of 236 individual flights, both with and without their wing scales, are presented. Results show, that for each of the 11 butterflies, the mean climbing efficiency decreased after scales were removed. Data was reduced to a single set of differences of climbing efficiency using are paired t …
Exploring Agricultural Production Systems And Their Fundamental Components With System Dynamics Modelling, Jeffrey P. Walters, David W. Archer, Gretchen F. Sassenrath, John R. Hendrickson, Jon D. Hanson, John M. Halloran, Peter Vadas, Vladimir J. Alarcon
Exploring Agricultural Production Systems And Their Fundamental Components With System Dynamics Modelling, Jeffrey P. Walters, David W. Archer, Gretchen F. Sassenrath, John R. Hendrickson, Jon D. Hanson, John M. Halloran, Peter Vadas, Vladimir J. Alarcon
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Agricultural production in the United States is undergoing marked changes due to rapid shifts in consumer demands, input costs, and concerns for food safety and environmental impact. Agricultural production systems are comprised of multidimensional components and drivers that interact in complex ways to influence production sustainability. In a mixed-methods approach, we combine qualitative and quantitative data to develop and simulate a system dynamics model that explores the systemic interaction of these drivers on the economic, environmental and social sustainability of agricultural production. We then use this model to evaluate the role of each driver in determining the differences in sustainability …
Risk Attitudes And Global Infrastructure Technology Choices, Jessica Kaminsky, Jeffrey P. Walters
Risk Attitudes And Global Infrastructure Technology Choices, Jessica Kaminsky, Jeffrey P. Walters
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Past research shows that Hofstede’s cultural dimension of uncertainty avoidance explains variance in nations’ technology choice for sanitation and electricity infrastructure construction. The uncertainty avoidance dimension describes the way that nations deal with ambiguity and uncertainty. This paper is part of a larger project that links that previous national scale research to the project level that is most relevant to the construction practice. As such, this paper reviews methods from the literature that measure individual risk attitudes, including issues of measurement and risk determinants. For example, this paper discusses paid real-stakes lotteries, general risk questions, and context specific risk questions. …
Using Casual Loop Diagramming To Explore The Drivers Of The Sustained Functionality Of Rural Water Services In Timor-Leste, Kate Neely, Jeffrey P. Walters
Using Casual Loop Diagramming To Explore The Drivers Of The Sustained Functionality Of Rural Water Services In Timor-Leste, Kate Neely, Jeffrey P. Walters
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
It is recognized that international water sector development work has issues with a lack of sustained positive outcomes. A large driver of this outcome is how NGOs work with communities to implement and then manage water services. Many NGOs tend to focus their efforts on improving their reach and organisational growth by continually engaging in new projects. This behaviour is largely driven by short-term donor funding models that reward extended coverage, leaving little focus on sustained outcomes. Similarly, community-based management (CBM) schemes often impede sustained services as a result of the community’s limited capacity to operate and maintain the technology. …
Experimental Investigation Of Stochastic Parafoil Guidance Using A Graphics Processing Unit, Nathan Slegers, Andrew Brown, Jonathan Rogers
Experimental Investigation Of Stochastic Parafoil Guidance Using A Graphics Processing Unit, Nathan Slegers, Andrew Brown, Jonathan Rogers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Control of autonomous systems subject to stochastic uncertainty is a challenging task. In guided airdrop applications, random wind disturbances play a crucial role in determining landing accuracy and terrain avoidance. This paper describes a stochastic parafoil guidance system which couples uncertainty propagation with optimal control to protect against wind and parameter uncertainty in the presence of impact area obstacles. The algorithm uses real-time Monte Carlo simulation performed on a graphics processing unit (GPU) to evaluate robustness of candidate trajectories in terms of delivery accuracy, obstacle avoidance, and other considerations. Building upon prior theoretical developments, this paper explores performance of the …
Planning Rural Water Services In Nicaragua: A Systems-Based Analysis Of Impact Factors Using Graphical Modeling, Jeffrey P. Walters, Paul S. Chinowsky
Planning Rural Water Services In Nicaragua: A Systems-Based Analysis Of Impact Factors Using Graphical Modeling, Jeffrey P. Walters, Paul S. Chinowsky
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
The success or failure of rural water services in the developing world is a result of numerous factors that interact in a complex set of connections that are difficult to separate and identify. This research effort presented a novel means to empirically reveal the systemic interactions of factors that influence rural water service sustainability in the municipalities of Darío and Terrabona, Nicaragua. To accomplish this, the study employed graphical modeling to build and analyze factor networks. Influential factors were first identified by qualitatively and quantitatively analyzing transcribed interviews from community water committee members. Factor influences were then inferred by graphical …
Long-Term Functionality Of Rural Water Services In Developing Countries: A System Dynamics Approach To Understanding The Dynamic Interaction Of Causal Factors, Jeffrey P. Walters, Amy N. Javernick-Will
Long-Term Functionality Of Rural Water Services In Developing Countries: A System Dynamics Approach To Understanding The Dynamic Interaction Of Causal Factors, Jeffrey P. Walters, Amy N. Javernick-Will
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Research has shown that sustainability of rural water infrastructure in developing countries is largely affected by the dynamic and systemic interactions of technical, social, financial, institutional, and environmental factors that can lead to premature water system failure. This research employs systems dynamic modeling, which uses feedback mechanisms to understand how these factors interact dynamically to influence long-term rural water system functionality. To do this, the research first identified and aggregated key factors from literature, then asked water sector experts to indicate the polarity and strength between factors through Delphi and cross impact survey questionnaires, and finally used system dynamics modeling …
Management Of Rural Water Services In Nicaragua: A Systematic Network Approach To Evaluating Stakeholder Alignment, Jeffrey P. Walters, Amy N. Javemick-Will
Management Of Rural Water Services In Nicaragua: A Systematic Network Approach To Evaluating Stakeholder Alignment, Jeffrey P. Walters, Amy N. Javemick-Will
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Water sector literature attributes a substantial cause of rural water system failure in developing countries to poor alignment between water service stakeholders. This study aimed to investigate a means for assessing stakeholder alignment by comparing the systemic interaction of stakeholder values, where the term ‘stakeholder values’ refers to aspects stakeholders believe are necessary to ensure rural water services are sustainable. The research held focus groups with key stakeholder groups involved in the management of rural water infrastructure in Terrabona, Nicaragua, to identify stakeholder values, and then used cross-impact analysis to evaluate how these values interacted to form stakeholder value networks …
Liver Sinusoid On A Chip: Long-Term Layered Co-Culture Of Primary Rat Hepatocytes And Endothelial Cells In Microfluidic Platforms, Young Bok (Abraham) Kang, Temitope R. Sodunke, Jason Lamontagne, Joseph Cirillo, Caroline Rajiv, Michael J. Bouchard, Moses Noh
Liver Sinusoid On A Chip: Long-Term Layered Co-Culture Of Primary Rat Hepatocytes And Endothelial Cells In Microfluidic Platforms, Young Bok (Abraham) Kang, Temitope R. Sodunke, Jason Lamontagne, Joseph Cirillo, Caroline Rajiv, Michael J. Bouchard, Moses Noh
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
We describe the generation of microfluidic platforms for the co-culture of primary hepatocytes and endothelial cells; these platforms mimic the architecture of a liver sinusoid. This paper describes a progressional study of creating such a liver sinusoid on a chip system. Primary rat hepatocytes (PRHs) were co-cultured with primary or established endothelial cells in layers in single and dual microchannel configurations with or without continuous perfusion. Cell viability and maintenance of hepatocyte functions were monitored and compared for diverse experimental conditions. When primary rat hepatocytes were co-cultured with immortalized bovine aortic endothelial cells (BAECs) in a dual microchannel with continuous …
Gust Mitigation Of Micro Air Vehicles Using Passive Articulated Wings, Adetunji Oduyela, Nathan Slegers
Gust Mitigation Of Micro Air Vehicles Using Passive Articulated Wings, Adetunji Oduyela, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Birds and insects naturally use passive flexing of their wings to augment their stability in uncertain aerodynamic environments. In a similar manner, micro air vehicle designers have been investigating using wing articulation to take advantage of this phenomenon. The result is a class of articulated micro air vehicles where artificial passive joints are designed into the lifting surfaces. In order to analyze how passive articulation affects performance of micro air vehicles in gusty environments, an efficient 8 degree-of-freedom model is developed. Experimental validation of the proposed mathematical model was accomplished using flight test data of an articulated micro air vehicle …
High-Efficiency Thrust Vector Control Allocation, Jeb S. Orr, Nathan Slegers
High-Efficiency Thrust Vector Control Allocation, Jeb S. Orr, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
A generalized approach to the allocation of redundant thrust vector slew commands for multi-actuated launch vehicles is presented, where deflection constraints are expressed as omniaxial or elliptical deflection limits in gimbal axes. More importantly than in the aircraft control allocation problem, linear allocators (pseudoinverses) are preferred for large booster applications to facilitate accurate prediction of the control-structure interaction resulting from thrust vectoring effects. However, strictly linear transformations for the allocation of redundant controls cannot, in general, access all of the attainable moments for which there is a set of control effector positions thatsatisfles the constraints. In this paper, the control …
Hfc(310) High Brightness Sources For Advanced Imaging Applications, William A. Mackie, Josh M. Lovell, Todd W. Curtis, Gerald G. Megara
Hfc(310) High Brightness Sources For Advanced Imaging Applications, William A. Mackie, Josh M. Lovell, Todd W. Curtis, Gerald G. Megara
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
The authors report on electron emission from HfC(310) operating in extended Schottky emission mode. Data are gathered from test stands as well as through operation in a commercial scanning electron microscope. Emitter end-form geometry consisted of rounded, via electrochemical etching, and truncated, via ion milling. The authors demonstrate high angular intensity operation of >60 mA/sr especially for the rounded end-form emitters. Advantages include robustness of the material, which is not reliant on material supply as is the case with standard ZrO/W(100) sources. Hence, operation is available over a much larger range of temperatures, fields, and potentially pressures. Operation in a …
The Influence Of Partial And Full Thickness Tears On Infraspinatus Tendon Strain Patterns, Kayt E. Frisch, David Marcu, Geoffrey S. Baer, Darryl G. Thelen, Ray Vanderby
The Influence Of Partial And Full Thickness Tears On Infraspinatus Tendon Strain Patterns, Kayt E. Frisch, David Marcu, Geoffrey S. Baer, Darryl G. Thelen, Ray Vanderby
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Tears on the bursal and articular sides of the rotator cuff tendons are known to behave differently and strain is thought to play a role in this difference. This study investigates the effect of tear location on the changes in three strain measurements (grip-to-grip, insertion, and mid-substance tissue) in a sheep infraspinatus tendon model during axial loading. We introduced a 14mm wide defect near the insertion from either the articular or bursal side of the tendon to three depths (3 mm, 7mm & full) progressively. For each condition, tendons were sinusoidally stretched (4% at 0.5 Hz) while insertion and midsubstance …
Layered Long Term Co-Culture Of Hepatocytes And Endothelial Cells On A Transwell Membrane: Toward Engineering The Liver Sinusoid, Young Bok (Abraham) Kang, Siddhartha Rawat, Joseph Cirillo, Michael Bouchard, Hongseok (Moses) Noh
Layered Long Term Co-Culture Of Hepatocytes And Endothelial Cells On A Transwell Membrane: Toward Engineering The Liver Sinusoid, Young Bok (Abraham) Kang, Siddhartha Rawat, Joseph Cirillo, Michael Bouchard, Hongseok (Moses) Noh
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
This paper presents a novel liver model that mimics the liver sinusoid where most liver activities occur. A key aspect of our current liver model is a layered co-culture of primary rat hepatocytes (PRHs) and primary rat liver sinusoidal endothelial cells (LSECs) or bovine aortic endothelial cells (BAECs) on a transwell membrane. When a layered co-culture was attempted with a thin matrigel layer placed between hepatocytes and endothelial cells to mimic the Space of Disse, the cells did not form completely separated monolayers. However, when hepatocytes and endothelial cells were cultured on the opposite sides of a transwell membrane, PRHs …
Interleukin Expression After Injury And The Effects Of Interleukin-1 Receptor Antagonist, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Stacey L. Brickson, William L. Murphy, Geoffrey S. Baer
Interleukin Expression After Injury And The Effects Of Interleukin-1 Receptor Antagonist, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Stacey L. Brickson, William L. Murphy, Geoffrey S. Baer
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Ligament and tendon repair involves a complex series of coordinated events orchestrated by various cell types, cytokines and other factors. The repair process extends months to years and results in scar tissue mechanically inferior to native tissue. This is in clear contrast to tissue "regeneration" which would recapitulate the native tissue. Numerous approaches to stimulate a regenerative scenario have been attempted, including tissue-engineering, non-steroidal anti-inflammatories, ultrasonic, or electrical stimulation, but none have resulted in complete regeneration. In pursuit of a more regenerative outcome, it is important to understand the fundamentals of the normal healing process. Previous work from our lab …
Flow-Induced Voltage Generation Over Monolayer Graphene In The Presence Of Herringbone Grooves, Seung Ho Lee, Young Bok (Abraham) Kang, Wonsuk Jung, Yousung Jung, Soohyun Kim, Hongseok (Moses) Noh
Flow-Induced Voltage Generation Over Monolayer Graphene In The Presence Of Herringbone Grooves, Seung Ho Lee, Young Bok (Abraham) Kang, Wonsuk Jung, Yousung Jung, Soohyun Kim, Hongseok (Moses) Noh
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
While flow-induced voltage over a graphene layer has been reported, its origin remains unclear. In our previous study, we suggested different mechanisms for different experimental configurations: phonon dragging effect for the parallel alignment and an enhanced out-of-plane phonon mode for the perpendicular alignment (Appl. Phys. Lett. 102:063116, 2011). In order to further examine the origin of flow-induced voltage, we introduced a transverse flow component by integrating staggered herringbone grooves in the microchannel. We found that the flow-induced voltage decreased significantly in the presence of herringbone grooves in both parallel and perpendicular alignments. These results support our previous interpretation.
Liver On A Chip; Engineering The Liver Sinusoid, Young Bok (Abraham) Kang
Liver On A Chip; Engineering The Liver Sinusoid, Young Bok (Abraham) Kang
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
We have developed a novel microfluidic device using poly-dimethylsiloxane (PDMS) microchannels for long term, layered co-culture of primary rat hepatocytes (PRH) and endothelial cells (EC) to mimic the liver sinusoid. Three microfluidic configurations were investigated as shown in Figure 1. In configuration 1, where PRH and rat adrenal medullary endothelial cells (RAMEC) were cocultured with matrigel in layers in a single PDMS microchannel, cells remained viable for 30 days. In configuration 3, where PRH and liver sinusoidal endothelial cells (LSEC) were cultured on the opposite sides of the microporous membrane between two microchannels under static and dynamic conditions, PRH retained …
Layered Hepatocytes And Endothelial Cells On A Transwell Membrane: Toward Engineering The Liver Sinusoid, Young Bok (Abraham) Kang, Joseph Cirillo, Siddhartha Rawat, Michael Bouchard, Hongseok (Moses) Noh
Layered Hepatocytes And Endothelial Cells On A Transwell Membrane: Toward Engineering The Liver Sinusoid, Young Bok (Abraham) Kang, Joseph Cirillo, Siddhartha Rawat, Michael Bouchard, Hongseok (Moses) Noh
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
This paper presents a novel liver model that mimics the liver sinusoid where most liver activities occur. A key aspect of our current liver model is a layered co-culture of primary rat hepatocytes (PRHs) and primary rat liver sinusoidal endothelial cells (LSECs) or bovine aortic endothelial cells (BAECs) on a transwell membrane. When a layered co-culture was attempted with a thin Matrigel layer placed between hepatocytes and endothelial cells to mimic the space of Disse, the cells did not form completely separated monolayers. However, when hepatocytes and endothelial cells were cultured on the opposite sides of a transwell membrane, PRHs …
Robust Parafoil Terminal Guidance Using Massively Parallel Processing, Jonathan Rogers, Nathan Slegers
Robust Parafoil Terminal Guidance Using Massively Parallel Processing, Jonathan Rogers, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Terminal guidance of autonomous parafoils is a difficult problem in which wind uncertainty and system underactuation are major challenges. Existing strategies almost exclusively use impact error as the criterion for optimality. Practical airdrop systems, however, must also include other criteria that maybe even more important than impact error for some missions, such as ground speed at impact or constraints imposed by drop zones with restrictions on flight patterns. Furthermore, existing guidance schemes determine terminal trajectories using deterministic wind information and may result in a solution that works in ideal wind but may be sensitive to variations. The work described here …
Projectile Fire-Control Algorithm In A Spatially Varying Wind Field, Lakmal Kaviratna, Mark Costello, Nathan Slegers
Projectile Fire-Control Algorithm In A Spatially Varying Wind Field, Lakmal Kaviratna, Mark Costello, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
The fire-control solution is an important element of any modern weapon system, providing precise aiming of the gun to enable highly accurate projectile impact. To be practical, the fire-control solution must be computed rapidly and reliably while simultaneously including all pertinent physical effects that can alter the trajectory and impact point. Current fire-control solutions account for the effect of atmospheric wind in a rudimentary manner, typically assuming a constant crosswind that is estimated in the field or measured at the firing site. With the advent of advanced wind-measurement systems (light detection and ranging, for example), it is now possible to …
Learning From Failure In Systems Engineering: A Panel Discussion, Nathan Slegers, Ronald T. Kadish, Gary E. Payton, John Thomas, Michael D. Griffin, Dan Dumbacher
Learning From Failure In Systems Engineering: A Panel Discussion, Nathan Slegers, Ronald T. Kadish, Gary E. Payton, John Thomas, Michael D. Griffin, Dan Dumbacher
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
This paper summarizes the discussion of the Learning from Failure in Systems Engineering panel that was held in Huntsville, AL on November 8, 2010. The panel objective was to discuss how systems engineers respond to and learn from failure and identify future directions important to the community. The panel consisted of four representatives with experience in government, industry, and academia: (1) Ronald Kadish from Booz Allen Hamilton and former director of the Missile Defense Agency, (2) Gary Payton, retired Deputy Under Secretary of the Air Force for Space Programs, (3) John Thomas from Booz Allen Hamilton and President-elect of INCOSE, …
Specialized System Identification For Parafoil And Payload Systems, Michael Ward, Mark Costello, Nathan Slegers
Specialized System Identification For Parafoil And Payload Systems, Michael Ward, Mark Costello, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
There are a number of peculiar aspects to parafoil and payload systems that make it difficult to apply conventional system identification procedures used for aerospace systems. Parafoil and payload systems are unique because typically there is very little sensor information available, the sensors that are available are separated from the canopy by a complex network of flexible rigging, the systems are very sensitive to wind and turbulence, the systems exhibit a number of nonlinear behaviors, and the systems exhibit a high degree of variability from flight to flight. The current work describes a robust system identification procedure developed to address …
Evaluation Of Multibody Parafoil Dynamics Using Distributed Miniature Wireless Sensors, Chrystine M. Gorman, Nathan Slegers
Evaluation Of Multibody Parafoil Dynamics Using Distributed Miniature Wireless Sensors, Chrystine M. Gorman, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Guided parafoils arc composed of two primary bodies, a payload and parafoil. The payload encompasses the majority ofthe ovcrdll system mass; however, the parafoil generates the majority of aerodynamic loads and is the sole source of control. Despite the canopy being the source of control, the sensor systems used for guidance are located away from the parafoil. Many multi body models exist in literature and use different degrees of freedom to represent parafoil-payload relative motion. However, in many cases, simulations are used to investigate how the relative motion between bodies affects the overall dynamics without experimental validation determining the accuracy …
Non-Isothermal Cool Flames In Unstirred Static Reactors: A Compressible Model With Global Kinetics, Michael R. Foster, Howard Pearlman
Non-Isothermal Cool Flames In Unstirred Static Reactors: A Compressible Model With Global Kinetics, Michael R. Foster, Howard Pearlman
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
A compressible model is developed with kinetics based on the Wang–Mou five-step global kinetic scheme and used to evaluate the temperature, concentration, and velocity fields characteristic of low temperature combustion in unstirred static reactors. This work relaxes the assumption of small exothermicity that enabled prior studies to employ the Boussinesq approximation, valid for cases where BT << 1, i.e., slow reactions and cool flames. In this study, the range of validity of the model is extended to cases with large temperature excursions, including multi-stage ignition. For the weakly exothermic cases considered, including modes of slow reaction and cool flames, the Boussinesq approximation is completely adequate. However, it overpredicts the density change and underpredicts the ignition delay time for high-temperature ignitions. Qualitative comparison with experimental results acquired at microgravity conditions are also discussed.
Quantification Of Collagen Organization Using Fractal Dimensions And Fourier Transforms, Kayt E. Frisch, Sarah E. Duenwald-Kuehl, Hirohito Kobayashi, Connie S. Chamberlain, Roderic S. Lakes, Ray Vanderby Jr.
Quantification Of Collagen Organization Using Fractal Dimensions And Fourier Transforms, Kayt E. Frisch, Sarah E. Duenwald-Kuehl, Hirohito Kobayashi, Connie S. Chamberlain, Roderic S. Lakes, Ray Vanderby Jr.
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Collagen fibers and fibrils that comprise tendons and ligaments are disrupted or damaged during injury. Fibrillogenesis during healing produces a matrix that is initially quite disorganized, but remodels over time to resemble, but not replicate, the original roughly parallel microstructure. Quantification of these changes is traditionally a laborious and subjective task. In this work we applied two automated techniques, fast Fourier transformation (FFT) and fractal dimension analysis (FA) to quantify the organization of collagen fibers or fibrils. Using multi-photon images of collagen fibers obtained from rat ligament we showed that for healing ligaments, FA differentiates more clearly between the different …
Mobilization Of Endocrine‐Disrupting Chemicals And Estrogenic Activity In Simulated Rainfall Runoff From Land‐Applied Biosolids, Ben D. Giudice, Thomas M. Young
Mobilization Of Endocrine‐Disrupting Chemicals And Estrogenic Activity In Simulated Rainfall Runoff From Land‐Applied Biosolids, Ben D. Giudice, Thomas M. Young
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Municipal biosolids are commonly applied to land as soil amendment or fertilizer as a form of beneficial reuse of what could otherwise be viewed as waste. Balanced against this benefit are potential risks to groundwater and surface water quality from constituents that may be mobilized during storm events. The objective of the present study was to characterize the mobilization of selected endocrinedisrupting compounds, heavy metals, and total estrogenic activity in rainfall runoff from land-applied biosolids. Rainfall simulations were conducted on soil plots amended with biosolids. Surface runoff and leachate was collected and analyzed for the endocrinedisrupting compounds bisphenol A, 17a-ethynylestradiol, …
The Influence Of Macrophage Depletion On Ligament Healing, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Sijian Wang, Xipei Yang, Nico Van Rooijen, Geoff S. Baer, Stacey L. Brickson, Ray Vanderby
The Influence Of Macrophage Depletion On Ligament Healing, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Sijian Wang, Xipei Yang, Nico Van Rooijen, Geoff S. Baer, Stacey L. Brickson, Ray Vanderby
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Despite a complex cascade of cellular events to reconstruct damaged extracellular matrix (ECM), ligament healing results in a mechanically inferior, scar-like tissue. During normal healing, the number of macrophages significantly increases within the wound site. Then, granulation tissue expands into any residual, normal ligamentous tissue (creeping substitution), resulting in a larger region of healing, greater mechanical compromise, and an inefficient repair process. To study the effects of macrophages on the repair process, bilateral, surgical rupture of their medial collateral ligaments (MCLs) was done on rats. Treatment animals received liposome-encapsulated clodronate, 2 days before rupture to ablate phagocytosing macrophages. Ligaments were …
The Influence Of Interleukin-4 On Ligament Healing, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Sijian Wang, Xipei Yang, Stacey L. Brickson, Ray Vanderby
The Influence Of Interleukin-4 On Ligament Healing, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Sijian Wang, Xipei Yang, Stacey L. Brickson, Ray Vanderby
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Despite a complex cascade of cellular events to reconstruct the damaged extracellular matrix, ligament healing results in a mechanically inferior scarred ligament. During normal healing, granulation tissue expands into any residual normal ligamentous tissue (creeping substitution), resulting in a larger region of healing, greater mechanical compromise and an inefficient repair process. To control creeping substitution and possibly enhance the repair process, the antiinflammatory cytokine, interleukin-4 (IL-4), was administered to rats before and after rupture of their medial collateral ligaments. In vitro experiments showed a time-dependent effect on fibroblast proliferation after IL-4 treatment. In vivo treatments with IL-4 (100 ng/mL IV) …
Terminal Guidance Of Autonomous Parafoils In High Wind-To-Airspeed Ratios, Nathan Slegers, O A. Yakimenko
Terminal Guidance Of Autonomous Parafoils In High Wind-To-Airspeed Ratios, Nathan Slegers, O A. Yakimenko
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Autonomous precision placement of parafoils is challenging because of their limited control authority and sensitivity to winds. In particular, when wind speed is near the airspeed, guidance is further complicated by the parafoils inability to penetrate the wind. This article specifically addresses the terminal phase and develops an approach for generating optimal trajectories in real-time based on the inverse dynamics in the virtual domain. The method results in efficient solution of a two-point boundary-value problem using only a single optimization parameter allowing the trajectory to be generated at a high rate, mitigating effects of the unknown winds. It is shown …