The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Neil K. Dhingra - One of the best experts on this subject based on the ideXlab platform.
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Structured Decentralized Control of Positive Systems With Applications to Combination Drug Therapy and Leader Selection in Directed Networks
IEEE Transactions on Control of Network Systems, 2019Co-Authors: Neil K. Dhingra, Marcello Colombino, Mihailo R. JovanovićAbstract:We study a class of structured optimal control problems in which the main diagonal of the dynamic matrix is a linear function of the design variable. While such problems are in general challenging and nonconvex, for positive systems we prove convexity of the H2 and H∞ optimal control formulations that allow for arbitrary convex constraints and regularization of the control input. Moreover, we establish differentiability of the H∞ norm when the graph associated with the dynamical generator is weakly connected and develop a customized algorithm for computing the optimal solution even in the absence of differentiability. We apply our results to the problems of leader selection in directed consensus networks and Combination Drug Therapy for human immunodeficiency virus (HIV) treatment. In the context of leader selection, we address the combinatorial challenge by deriving upper and lower bounds on optimal performance. For Combination Drug Therapy, we develop a customized subgradient method for efficient treatment of diseases whose mutation patterns are not connected.
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Structured decentralized control of positive systems with applications to Combination Drug Therapy and leader selection in directed networks
IEEE Transactions on Control of Network Systems, 2019Co-Authors: Neil K. Dhingra, Marcello Colombino, Mihailo R. JovanovicAbstract:We study a class of structured optimal control problems in which the main diagonal of the dynamic matrix is a linear function of the design variable. While such problems are in general challenging and nonconvex, for positive systems we prove convexity of the $H_2$ and $H_\infty$ optimal control formulations which allow for arbitrary convex constraints and regularization of the control input. Moreover, we establish differentiability of the $H_\infty$ norm when the graph associated with the dynamical generator is weakly connected and develop a customized algorithm for computing the optimal solution even in the absence of differentiability. We apply our results to the problems of leader selection in directed consensus networks and Combination Drug Therapy for HIV treatment. In the context of leader selection, we address the combinatorial challenge by deriving upper and lower bounds on optimal performance. For Combination Drug Therapy, we develop a customized subgradient method for efficient treatment of diseases whose mutation patterns are not connected.
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on the optimal control problem for a class of monotone bilinear systems
arXiv: Optimization and Control, 2016Co-Authors: Neil K. Dhingra, Marcello Colombino, Mihailo R. Jovanovic, Anders Rantzer, Roy S SmithAbstract:We consider a class of monotone systems in which the control signal multiplies the state. Among other applications, such bilinear systems can be used to model the evolutionary dynamics of HIV in the presence of Combination Drug Therapy. For this class of systems, we formulate an infinite horizon optimal control problem, prove that the optimal control signal is constant over time, and show that it can be computed by solving a finite-dimensional non-smooth convex optimization problem. We provide an explicit expression for the subdifferential set of the objective function and use a subgradient algorithm to design the optimal controller. We further extend our results to characterize the optimal robust controller for systems with uncertain dynamics and show that computing the robust controller is no harder than computing the nominal controller. We illustrate our results with an example motivated by Combination Drug Therapy.
Hanns-juergenreulen - One of the best experts on this subject based on the ideXlab platform.
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Combination Drug Therapy and Mild Hypothermia
Stroke, 1999Co-Authors: Robertschmid-elsaesser, Edwinhungerhuber, Stefanzausinger, Alexanderbaethmann, Hanns-juergenreulenAbstract:Background and Purpose—Hypothermia has been suggested to be the most potent therapeutic approach to reduce experimental ischemic brain injury identified to date, and mild hypothermia is increasingly used for neuroprotection during neurovascular surgery. We have recently demonstrated that combined administration of tirilazad mesylate and magnesium provides for an overall enhanced neuroprotective effect. The present study was designed to determine whether the efficacy of mild hypothermia (33°C) can be increased by Combination pharmacoTherapy with tirilazad and magnesium (MgCl2). Methods—Forty Sprague-Dawley rats were subjected to transient, middle cerebral artery occlusion and were randomly assigned to 1 of 4 treatment arms (n=10 each): (1) normothermia+vehicle, (2) normothermia+tirilazad+MgCl2, (3) hypothermia+vehicle, or (4) hypothermia+tirilazad+MgCl2. Cortical blood flow was monitored by a bilateral laser-Doppler flowmeter, and the electroencephalogram was continuously recorded. Functional deficits were...
Myra T. Belgeri - One of the best experts on this subject based on the ideXlab platform.
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MonoTherapy versus Combination Drug Therapy for the treatment of benign prostatic hyperplasia.
The American journal of geriatric pharmacotherapy, 2005Co-Authors: Youlanda T. Logan, Myra T. BelgeriAbstract:Abstract Background: Benign prostatic hyperplasia (BPH) is a medical condition occurring in older men (ie, those aged >60 years) resulting from enlargement of the prostate gland. Consequently, affected men may experience bother-some urinary tract symptoms and diminished quality of life. The risk of lower urinary tract symptoms and complications such as acute urinary retention (AUR) may increase if BPH is untreated. Currently, 2 classes of Drugs—α-adrenergic blockers (α-blockers) and 5α-reductase inhibitors—are indicated for the treatment of BPH. Although the 2 classes are commonly used in Combination, the evidence has frequently not been supportive of this practice. Results from the Medical Therapy of Prostatic Symptoms (MTOPS) trial, the largest and longest clinical trial on this topic to date, revisited the role of Combination Therapy in the treatment of BPH. Objective: This review presents published trials evaluating α-blockers or 5α-reductase inhibitors used alone or in Combination for the treatment of BPH. Methods: A MEDLINE search was conducted (December 1974 to November 2004) using the MeSH term prostatic hyperplasia limited to the subheading of Drug Therapy. These results were cross-referenced with the MeSH term Combination Drug Therapy. An additional search was conducted using the MeSH terms finasteride and adrenergic α-antagonists limited to adverse effects and therapeutic uses. These results were cross-referenced with prostatic hyperplasia and Combination Drug Therapy. Review articles and meta-analyses were also used. Results: The Veterans Affairs Cooperative Studies Benign Prostatic Hyperplasia Study Group and the Prospective European Doxazosin and Combination Therapy studies were well-designed trials that failed to support the theory that Combination Therapy is preferred over α-blockers alone. Finasteride was also shown to be no better than placebo for the outcomes of symptom score and peak urinary flow rates. Other trials suggested that Combination Therapy (which included finasteride) was more effective at reducing symptom scores in men with enlarged prostates at 1 year and that α-blockers may be successfully discontinued once patients are stabilized on finasteride. Although it was a prespecified secondary end point, the incidence of surgery or AUR was reduced by 51% using finasteride over placebo. The additive benefit finasteride provides in reducing symptoms, risk of AUR, and invasive surgery was observed within the first year of treatment and correlated with larger prostate sizes (mean [SD], ∼55 [26] mL). The MTOPS trial further demonstrated a relative risk reduction of 66% in clinical progression rates for the Combination-Therapy group versus 39% for the doxazosin group compared with placebo (P Conclusion: Based on the literature, Combination Therapy has been proven to relieve symptoms and delay progression of BPH in men with moderate to severe symptoms and moderately enlarged prostate glands.
Mihailo R. Jovanovic - One of the best experts on this subject based on the ideXlab platform.
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Structured decentralized control of positive systems with applications to Combination Drug Therapy and leader selection in directed networks
IEEE Transactions on Control of Network Systems, 2019Co-Authors: Neil K. Dhingra, Marcello Colombino, Mihailo R. JovanovicAbstract:We study a class of structured optimal control problems in which the main diagonal of the dynamic matrix is a linear function of the design variable. While such problems are in general challenging and nonconvex, for positive systems we prove convexity of the $H_2$ and $H_\infty$ optimal control formulations which allow for arbitrary convex constraints and regularization of the control input. Moreover, we establish differentiability of the $H_\infty$ norm when the graph associated with the dynamical generator is weakly connected and develop a customized algorithm for computing the optimal solution even in the absence of differentiability. We apply our results to the problems of leader selection in directed consensus networks and Combination Drug Therapy for HIV treatment. In the context of leader selection, we address the combinatorial challenge by deriving upper and lower bounds on optimal performance. For Combination Drug Therapy, we develop a customized subgradient method for efficient treatment of diseases whose mutation patterns are not connected.
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on the optimal control problem for a class of monotone bilinear systems
arXiv: Optimization and Control, 2016Co-Authors: Neil K. Dhingra, Marcello Colombino, Mihailo R. Jovanovic, Anders Rantzer, Roy S SmithAbstract:We consider a class of monotone systems in which the control signal multiplies the state. Among other applications, such bilinear systems can be used to model the evolutionary dynamics of HIV in the presence of Combination Drug Therapy. For this class of systems, we formulate an infinite horizon optimal control problem, prove that the optimal control signal is constant over time, and show that it can be computed by solving a finite-dimensional non-smooth convex optimization problem. We provide an explicit expression for the subdifferential set of the objective function and use a subgradient algorithm to design the optimal controller. We further extend our results to characterize the optimal robust controller for systems with uncertain dynamics and show that computing the robust controller is no harder than computing the nominal controller. We illustrate our results with an example motivated by Combination Drug Therapy.
Stephen R. Williams - One of the best experts on this subject based on the ideXlab platform.
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Comparative efficacy of Combination Drug Therapy in refractory epilepsy
Neurology, 2011Co-Authors: Nicholas P. Poolos, Lindsay N. Warner, Sophia Z. Humphreys, Stephen R. WilliamsAbstract:Objective: We retrospectively examined treatment records of developmentally disabled adults with highly refractory epilepsy to determine whether any Combinations of 8 of the most commonly used antiepileptic Drugs (AEDs) possessed superior efficacy. Methods: We obtained the treatment records from 148 developmentally disabled adults with refractory epilepsy cared for in 2 state-run institutions. These records charted monthly convulsive seizure occurrence and AED regimen over 30 years. We studied the effects of 8 commonly used AEDs alone and in Combination on seizure frequency in within-patient comparisons. Results: Out of the 32 most frequently used AED Combinations, we found that only the Combination of lamotrigine and valproate had superior efficacy, measured against both an aggregate measure of other AED regimens to which patients were exposed, and in head-to-head comparisons with other AED Combinations. We also found that while use of 2 concurrent AEDs provided improved efficacy over monoTherapy, use of 3 AEDs at a time provided no further benefit over two. Conclusions: These results suggest that at least one AED regimen provides significantly better efficacy in refractory convulsive epilepsy, and that AEDs should be used no more than 2 at a time. Limitations of the study include its retrospective design, lack of randomization, and small sample sizes for some Drug Combinations. Future prospective trials are needed in this challenging clinical population.