Structural adaptation of the bone tissue is mediated by loading-induced interstitial fluid flow w... more Structural adaptation of the bone tissue is mediated by loading-induced interstitial fluid flow within the bone microstructure. Within this framework, osteocytes fulfill the central mechanotransductive role in the bone remodeling process. While osteocytes have been demonstrated to be exquisitely sensitive to various forms of fluid flow stimulus in vitro, the effect of different oscillating fluid flow (OFF) parameters on osteocyte activity has yet to be systematically characterized. In this study, we investigate the effect of three OFF parameters on osteocyte activity in vitro and hypothesize that COX-2, RANKL, and OPG mRNA expression in osteocytes are sensitive to the OFF parameters: peak shear stress amplitude (0.5 Pa, 1 Pa, 2 Pa, and 5 Pa), oscillating frequency (0.5 Hz, 1 Hz, and 2 Hz), and total flow duration (1 h, 2 h, and 4 h). Our findings demonstrate that COX-2 mRNA levels are elevated in osteocytes subjected to higher peak shear stress amplitudes and longer flow durations, while RANKL/OPG mRNA levels decreased to a minimum threshold in response to higher peak shear stress amplitudes, faster oscillating frequencies, and longer flow durations. These findings suggest that dynamic fluid flow with higher peak shear stress amplitudes, faster oscillating frequencies, and longer loading durations provide the best conditions for promoting bone formation.
This paper describes a purely case-based undergraduate operations research course that has been s... more This paper describes a purely case-based undergraduate operations research course that has been successfully run in the industrial engineering program at the University of Toronto for 11 years. We describe the structure of the course, including the process adopted for solving the weekly cases, student assessment methods, and the choice of cases. Student feedback suggests that the course enhances the learning experience through the principle of learning by doing, provides a platform for integration of operations research methods learned in earlier classes, can be conducive to improving communication skills, and addresses the gap between theory and practice through a simulated workplace environment.
A Data Collection Strategy for Estimation of Cost Coefficients of a Linear Programming Model
Management Science, 1976
The problem considered is one of selecting from a number of alternative sources of information fo... more The problem considered is one of selecting from a number of alternative sources of information for the refinement of estimates of objective function coefficients of a linear programming model. The approach used is that of Bayesian decision theory. A sequential scheme for the computing of bounds on the value of information is devised. Using these bounds the information of greatest value may be identified.
Applications and curricula of decision analysis currently do not include methods to compute Bayes... more Applications and curricula of decision analysis currently do not include methods to compute Bayes' rule and obtain posteriors for non-conjugate prior distributions. The current convention is to force the decision maker's belief to take the form of a conjugate distribution, leading to a suboptimal decision. BUGS software, which uses MCMC methods, is numerically capable of obtaining posteriors for non-conjugate priors. By using the decision maker's true non-conjugate belief, the problems explored suggest that BUGS is able to produce a posterior distribution which leads to optimal decision making. Other methods exist which can use nonconjugate priors, but they must be implemented ad hoc as they do not have any supporting software. BUGS offers the distinct advantage of being implemented in existing software. This software has a gradual learning curve, and with simple coding can solve a wide range of decision analysis problems. BUGS is useful in making optimal decisions, and it is reasonably easy to learn and implement, therefore there is value in including BUGS in decision analysis curricula.
We review some mathematical programming models that capture the optimal bidding problem that powe... more We review some mathematical programming models that capture the optimal bidding problem that power producers face in day-ahead electricity auction markets. The models consider both price-taking and non-price taking assumptions. The models include linear and non-linear integer programming models, mathematical programs with equilibrium constraints, and stochastic programming models with recourse. Models are emphasized where the producer must self-schedule units and therefore must integrate optimal bidding with unit commitment decisions. We classify models according to whether competition from competing producers is directly incorporated in the model.
Structural adaptation of the bone tissue is mediated by loading-induced interstitial fluid flow w... more Structural adaptation of the bone tissue is mediated by loading-induced interstitial fluid flow within the bone microstructure. Within this framework, osteocytes fulfill the central mechanotransductive role in the bone remodeling process. While osteocytes have been demonstrated to be exquisitely sensitive to various forms of fluid flow stimulus in vitro, the effect of different oscillating fluid flow (OFF) parameters on osteocyte activity has yet to be systematically characterized. In this study, we investigate the effect of three OFF parameters on osteocyte activity in vitro and hypothesize that COX-2, RANKL, and OPG mRNA expression in osteocytes are sensitive to the OFF parameters: peak shear stress amplitude (0.5 Pa, 1 Pa, 2 Pa, and 5 Pa), oscillating frequency (0.5 Hz, 1 Hz, and 2 Hz), and total flow duration (1 h, 2 h, and 4 h). Our findings demonstrate that COX-2 mRNA levels are elevated in osteocytes subjected to higher peak shear stress amplitudes and longer flow durations, while RANKL/OPG mRNA levels decreased to a minimum threshold in response to higher peak shear stress amplitudes, faster oscillating frequencies, and longer flow durations. These findings suggest that dynamic fluid flow with higher peak shear stress amplitudes, faster oscillating frequencies, and longer loading durations provide the best conditions for promoting bone formation.
This paper describes a purely case-based undergraduate operations research course that has been s... more This paper describes a purely case-based undergraduate operations research course that has been successfully run in the industrial engineering program at the University of Toronto for 11 years. We describe the structure of the course, including the process adopted for solving the weekly cases, student assessment methods, and the choice of cases. Student feedback suggests that the course enhances the learning experience through the principle of learning by doing, provides a platform for integration of operations research methods learned in earlier classes, can be conducive to improving communication skills, and addresses the gap between theory and practice through a simulated workplace environment.
A Data Collection Strategy for Estimation of Cost Coefficients of a Linear Programming Model
Management Science, 1976
The problem considered is one of selecting from a number of alternative sources of information fo... more The problem considered is one of selecting from a number of alternative sources of information for the refinement of estimates of objective function coefficients of a linear programming model. The approach used is that of Bayesian decision theory. A sequential scheme for the computing of bounds on the value of information is devised. Using these bounds the information of greatest value may be identified.
Applications and curricula of decision analysis currently do not include methods to compute Bayes... more Applications and curricula of decision analysis currently do not include methods to compute Bayes' rule and obtain posteriors for non-conjugate prior distributions. The current convention is to force the decision maker's belief to take the form of a conjugate distribution, leading to a suboptimal decision. BUGS software, which uses MCMC methods, is numerically capable of obtaining posteriors for non-conjugate priors. By using the decision maker's true non-conjugate belief, the problems explored suggest that BUGS is able to produce a posterior distribution which leads to optimal decision making. Other methods exist which can use nonconjugate priors, but they must be implemented ad hoc as they do not have any supporting software. BUGS offers the distinct advantage of being implemented in existing software. This software has a gradual learning curve, and with simple coding can solve a wide range of decision analysis problems. BUGS is useful in making optimal decisions, and it is reasonably easy to learn and implement, therefore there is value in including BUGS in decision analysis curricula.
We review some mathematical programming models that capture the optimal bidding problem that powe... more We review some mathematical programming models that capture the optimal bidding problem that power producers face in day-ahead electricity auction markets. The models consider both price-taking and non-price taking assumptions. The models include linear and non-linear integer programming models, mathematical programs with equilibrium constraints, and stochastic programming models with recourse. Models are emphasized where the producer must self-schedule units and therefore must integrate optimal bidding with unit commitment decisions. We classify models according to whether competition from competing producers is directly incorporated in the model.
Uploads
Papers by daniel frances