To reduce the use of whole animals and the costs associated with them researchers are constantly ... more To reduce the use of whole animals and the costs associated with them researchers are constantly working on the development of stable and effective hepatocyte cell-based in vitro systems that can provide more relevant data earlier in the development process. Isolated hepatocytes or their enzymes comprise the base of most in- vitro DMPK and Tox assays. Because most hepatospecific functions are typically lost in the first days of culture, they are of limited use in cases where compounds clear slowly, or where metabolites are generated over extended periods of time. Here, we will present a novel canine in-vitro model that exhibits metabolic capacities which are maintained for up to two weeks. We then used this model to compare metabolite profiles for 9 reference low clearing compounds. In addition, the toxicity of 51 compounds was evaluated. ABSTRACT predicting the pharmacokinetic and toxicological properties of drugs as early as possible in the development process can materially reduc...
Selfish behavior at the Medium Access (MAC) Layer can have devastating side effects on the perfor... more Selfish behavior at the Medium Access (MAC) Layer can have devastating side effects on the perfor- mance of wireless networks, with effects similar to those of Denial of Service (DoS) attacks. In this paper we consider the problem of detection and prevention of node misbehavior at the MAC layer, focusing on the back-off manipulation by selfish nodes. We first propose an algorithm that ensures honest behavior of non-colluding participants. Furthermore, we analyze the problem of colluding selfish nodes, casting the problem within a minimax robust detection framework and providing an optimal detection rule for the worst-case attack scenarios. Finally, we evaluate the performance of single and colluding attackers in terms of detection delay. Although our approach is general and can be used with any probabilistic distributed MAC protocol, we focus our analysis on the IEEE 802.11 MAC.
Proceedings of the 3rd international conference on High confidence networked systems, 2014
ABSTRACT We introduce a new problem formulation for understanding the threats and vulnerabilities... more ABSTRACT We introduce a new problem formulation for understanding the threats and vulnerabilities of process control systems. In particular, we consider an adversary that has compromised sensor or actuator signals of a control system and needs to identify the best time to launch an attack. We have previously shown that attackers might not be able to reach if the timing of their Denial-of-Service (DoS) attacks is not chosen strategically: Therefore, if the timing of a DoS attack is not chosen correctly, the attack can have limited impact; however, if the timing of the attack is chosen carefully, the attack has higher chances of succeeding. We formulate the problem of selecting a good time to launch DoS attacks as an optimal stopping problem that the adversary has to solve in real-time. In particular, we use the theory for the Best-Choice Problem to identify an optimal stopping criteria and then use a low pass filter to identify when the time series of a process variable has reached its peak. We identify some of the complexities associated with solving the problem and outline directions for future work.
Proceedings of the ACM workshop on Digital rights management - DRM '06, 2006
Page 1. Towards a Secure and Interoperable DRM Architecture Gelareh Taban, Alvaro A. Cárdenas and... more Page 1. Towards a Secure and Interoperable DRM Architecture Gelareh Taban, Alvaro A. Cárdenas and Virgil D. Gligor Department of Electrical and Computer Engineering University of Maryland, College Park gtaban, acardena, gligor@umd.edu ...
To reduce the use of whole animals and the costs associated with them researchers are constantly ... more To reduce the use of whole animals and the costs associated with them researchers are constantly working on the development of stable and effective hepatocyte cell-based in vitro systems that can provide more relevant data earlier in the development process. Isolated hepatocytes or their enzymes comprise the base of most in- vitro DMPK and Tox assays. Because most hepatospecific functions are typically lost in the first days of culture, they are of limited use in cases where compounds clear slowly, or where metabolites are generated over extended periods of time. Here, we will present a novel canine in-vitro model that exhibits metabolic capacities which are maintained for up to two weeks. We then used this model to compare metabolite profiles for 9 reference low clearing compounds. In addition, the toxicity of 51 compounds was evaluated. ABSTRACT predicting the pharmacokinetic and toxicological properties of drugs as early as possible in the development process can materially reduc...
Selfish behavior at the Medium Access (MAC) Layer can have devastating side effects on the perfor... more Selfish behavior at the Medium Access (MAC) Layer can have devastating side effects on the perfor- mance of wireless networks, with effects similar to those of Denial of Service (DoS) attacks. In this paper we consider the problem of detection and prevention of node misbehavior at the MAC layer, focusing on the back-off manipulation by selfish nodes. We first propose an algorithm that ensures honest behavior of non-colluding participants. Furthermore, we analyze the problem of colluding selfish nodes, casting the problem within a minimax robust detection framework and providing an optimal detection rule for the worst-case attack scenarios. Finally, we evaluate the performance of single and colluding attackers in terms of detection delay. Although our approach is general and can be used with any probabilistic distributed MAC protocol, we focus our analysis on the IEEE 802.11 MAC.
Proceedings of the 3rd international conference on High confidence networked systems, 2014
ABSTRACT We introduce a new problem formulation for understanding the threats and vulnerabilities... more ABSTRACT We introduce a new problem formulation for understanding the threats and vulnerabilities of process control systems. In particular, we consider an adversary that has compromised sensor or actuator signals of a control system and needs to identify the best time to launch an attack. We have previously shown that attackers might not be able to reach if the timing of their Denial-of-Service (DoS) attacks is not chosen strategically: Therefore, if the timing of a DoS attack is not chosen correctly, the attack can have limited impact; however, if the timing of the attack is chosen carefully, the attack has higher chances of succeeding. We formulate the problem of selecting a good time to launch DoS attacks as an optimal stopping problem that the adversary has to solve in real-time. In particular, we use the theory for the Best-Choice Problem to identify an optimal stopping criteria and then use a low pass filter to identify when the time series of a process variable has reached its peak. We identify some of the complexities associated with solving the problem and outline directions for future work.
Proceedings of the ACM workshop on Digital rights management - DRM '06, 2006
Page 1. Towards a Secure and Interoperable DRM Architecture Gelareh Taban, Alvaro A. Cárdenas and... more Page 1. Towards a Secure and Interoperable DRM Architecture Gelareh Taban, Alvaro A. Cárdenas and Virgil D. Gligor Department of Electrical and Computer Engineering University of Maryland, College Park gtaban, acardena, gligor@umd.edu ...
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