Use of levodopa to relieve pain from painful symmetrical diabetic polyneuropathy

Levodopa has been used to treat some painful conditions and found to be effective in neuropathic pain due to herpes zoster in a double-blind study. From our anecdotal observations about the efficacy of levodopa on diabetic neuropathic pain, we designed a double-blind placebo-controlled study to test levodopa in painful diabetic neuropathy. Twenty-five out-patients with painful symmetrical diabetic polyneuropathy were admitted to the study. Fourteen patients were given 100 mg levodopa plus 25 mg benserazide to be taken three times per day for 28 days. Eleven patients were given identical placebo capsules. A blinded neurologist evaluated the patients clinically and performed Visual Analogue Scale (VAS) measurement every week from day 0 to day 28. The results seemed promising and levodopa may be a choice for the control of pain in neuropathy for which we do not have many alternative treatments.     

A game-theoretic look at simple relay channel

In this paper, we address the crosslayer problem of joint medium access control (MAC) and routing in ad hoc wireless networks from the novel perspective of stochastic dynamic games. As a starting point to understand the efficient modes of wireless network operation, we look at the basic problem of multi-hop communication over the simple topology of a single relay channel. A stochastic game is formulated for transmitter and relay nodes competing over collision channels to deliver packets to a common destination node using alternative paths. We rely on a reward mechanism to stimulate cooperation for packet forwarding and evaluate the conflicting multiple access and routing strategies of direct communication and relaying through a detailed foray into the questions of cooperation incentives, throughput, delay and energy-efficiency. Under the separate models of selfish and cooperative network operation, we study the interactions among the equilibrium strategies and present a detailed performance analysis based on multiple system parameters that involve the packet arrival rates, throughput rewards, delay and energy costs. The material in this paper was partially presented at WIOPT’04: Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, Cambridge, UK, March 2004. Prepared through collaborative participation in the Communications and Networks Consortium sponsored by the U. S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0011. The U. S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. Anthony Ephremides received his B.S. degree from the National Technical University of Athens (1967), and M.S. (1969) and Ph.D. (1971) degrees from Princeton University, all in electrical engineering. He has been at the University of Maryland since 1971, and currently holds a joint appointment as professor in the Electrical Engineering Department and the Institute of Systems Research (ISR). He is co-founder of the NASA Center for Commercial Development of Space on Hybrid and Satellite Communications Networks established in 1991 at Maryland as an offshoot of the ISR. He was a visiting professor in 1978 at the National Technical University of Athens, Greece, and in 1979 at the Electrical Engineering and Computer Science Department of the University of California at Berkeley and INRIA, France. During 1985–1986 he was on leave at Massachusetts Institute of Technology and the Swiss Federal Institute of Technology, Zurich. He has also been director of the Fairchild Scholars and Doctoral Fellows Program, an academic and research partnership program in satellite communications between Fairchild Industries and the University of Maryland. He has been President of the Information Theory Society of the IEEE (1987), and served on the Board of the IEEE (1989 and 1990). His interests are in the areas of communication theory, communication systems and networks, queuing systems, signal processing, and satellite communications. Yalin Evren Sagduyu received his B.S. degree from Bogazici University, Turkey, and M.S. degree from the University of Maryland at College Park in 2000 and 2002, respectively, all in electrical engineering. He is currently working toward his Ph.D. degree at the University of Maryland, where he has been a graduate research assistant with ISR since 2000. His research interests include wireless communication, ad hoc and sensor network design and optimization, stochastic game theory and network coding.     

Training overhead for decoding random linear network codes in wireless networks

We consider multicast communications from a single source to multiple destinations through a wireless network with unreliable links. Random linear network coding achieves the min-cut flow capacity; however, additional overhead is needed for end-to-end error protection and to communicate the network coding matrix to each destination. We present a joint coding and training scheme in which training bits are appended to each source packet, and the channel code is applied across both the training and data. This scheme allows each destination to decode jointly the network coding matrix along with the data without knowledge of the network topology. It also balances the reliability of communicating the network coding matrices with the reliability of data detection. The throughput for this scheme, accounting for overhead, is characterized as a function of the packet size, channel properties (error and erasure statistics), number of independent messages, and field size. We also compare the performance with that obtained by individual channel coding of training and data. Numerical results are presented for a grid network that illustrate the reduction in throughput due to overhead.     

A game-theoretic analysis of denial of service attacks in wireless random access

In wireless access, transmitter nodes need to make individual decisions for distributed operation and do not necessarily cooperate with each other. We consider a single-receiver random access system of non-cooperative transmitters with the individual objectives of optimizing their throughput rewards, transmission energy costs and delay costs. The non-cooperative transmitter behavior may be purely selfish or may also reflect malicious objectives of generating interference to prevent the successful transmissions of the other nodes as a form of denial of service attack. Our goal is to evaluate the interactions between selfish and malicious nodes that have the dual objectives of optimizing their individual performance measures and blocking the packet transmissions of the other selfish nodes. We assume saturated packet queues of infinite buffer capacities and consider a general multi-packet reception channel that allows packet captures in the presence of simultaneous transmissions. In this context, we formulate a non-cooperative random access game of selecting the individual probabilities of transmitting packets to a common receiver. We derive the non-cooperative transmission strategies in Nash equilibrium. The analysis provides insights for the optimal strategies to block random access of selfish nodes as well as the optimal defense mechanisms against the possible denial of service attacks of malicious nodes in wireless networks. The results are also compared with the cooperative equilibrium strategies that optimize the total system utility (separately under random access and scheduled access). A pricing scheme is presented to improve the non-cooperative operation. For distributed implementation, we formulate a repeated game of the best-response strategy updates and introduce adaptive heuristics (based on the channel feedback only) provided that the system parameters are not explicitly known at the individual transmitters.

On Joint MAC and Network Coding in Wireless Ad Hoc Networks

This paper addresses network coding in wireless networks in conjunction with medium access control (MAC). It is known that coding over wired networks enables connections with rates that cannot be achieved by routing. However, the properties of wireless networks (e.g., omnidirectional transmissions, destructive interference, single transceiver per node, finite energy) modify the formulation of time-varying network coding in a way that reflects strong interactions with underlying MAC protocols and deviates from the classical approach used in wired network coding. To perform network coding over conflict-free transmission schedules, predetermined network realizations are separately activated by a time-division mechanism and the content of network flows is derived through network coding to optimize performance measures such as achievable throughput and energy costs. A systematic method is presented to construct linear wireless network codes and interactions with MAC schedules are discussed under wireless assumptions. Network coding is also extended to operate with arbitrary (random or scheduled access based) MAC protocols. Alternatively, conflict-free transmission schedules are jointly constructed with network codes by decomposing wireless networks into subtrees and employing graph coloring on simplified subtree graphs. Finally, network coding and plain routing are compared in terms of throughput, energy and delay performance under different MAC solutions.     

Omega-3 fatty acids decreased irritability of patients with bipolar disorder in an add-on,open label study

This is a report on a 37-patient continuation study of the open ended, Omega-3 Fatty Acid (O-3FA) add-on study. Subjects consisted of the original 19 patients, along with 18 new patients recruited and followed in the same fashion as the first nineteen. Subjects carried a DSM-IV-TR diagnosis of Bipolar Disorder and were visiting a Mood Disorder Clinic regularly through the length of the study. At each visit, patients' clinical status was monitored using the Clinical Monitoring Form. Subjects reported on the frequency and severity of irritability experienced during the preceding ten days; frequency was measured by way of percentage of days in which subjects experienced irritability, while severity of that irritability was rated on a Likert scale of 1 – 4 (if present). The irritability component of Young Mania Rating Scale (YMRS) was also recorded quarterly on 13 of the 39 patients consistently. Patients had persistent irritability despite their ongoing pharmacologic and psychotherapy.     

Multi-layer optimization with backpressure and genetic algorithms for multi-hop wireless networks

This paper presents an efficient scheme to optimize multiple layers in multi-hop wireless networks with throughput objectives. Considering channel sensing and power control at the physical layer, a non-convex throughput optimization problem is formulated for resource allocation and a genetic algorithm is designed to allow distributed implementation. To address link and network layers, a localized back-pressure algorithm is designed to make routing, scheduling, and frequency band assignments along with physical-layer considerations. Our multi-layer scheme is extended to cognitive radio networks with different user classes and evaluate our analytical solution via simulations. Hardware-in-the-loop emulation test results obtained with real radio transmissions over emulated channels are presented to verify the performance of our distributed multi-layer optimization solution for multi-hop wireless networks. Finally, a security system is considered, where links have their security levels and data flows require certain security levels on each of its links. This problem is addressed by formulating additional constraints to the optimization problem.     

Cross-Layer Optimization of MAC and Network Coding in Wireless Queueing Tandem Networks

In wireless networks, throughput optimization is an essential performance objective that cannot be adequately characterized by a single criterion (such as the minimum transmitted or sum-delivered throughput) and should be specified over all source-destination pairs as a rate region. For a simple and yet fundamental model of tandem networks, a cross-layer optimization framework is formulated to derive the maximum throughput region for saturated multicast traffic. The contents of network flows are specified through network coding (or plain routing) in network layer and the throughput rates are jointly optimized in medium access control layer over fixed set of conflict-free transmission schedules (or optimized over transmission probabilities in random access). If the network model incorporates bursty sources and allows packet queues to empty, the objective is to specify the stability region as the set of maximum throughput rates that can be sustained with finite packet delay. Dynamic queue management strategies are used to expand the stability region toward the maximum throughput region. Network coding improves throughput rates over plain routing and achieves the largest gains for broadcast communication and intermediate network sizes. Throughput optimization imposes fundamental tradeoffs with transmission and processing energy costs such that the throughput-optimal operation is not necessarily energy efficient.     

Generalized tonic-clonic status epilepticus: causes, treatment, complications and predictors of case fatality

We retrospectively reviewed the clinical course of 66 patients treated for generalized tonic-clonic status epilepticus at the Ege University neurological intensive care unit from 1988 to 1997. Seventy-two per cent of the study group had a pre-existing seizure disorder, and antiepileptic drug withdrawal was the most prominent cause of status epilepticus. The other causes included drug toxicity, central nervous system infection, cerebrovascular disease, tumour and trauma. Seventy-three per cent of all patients responded to the first-line therapy (diazepam and/or phenytoin), and the remainder were considered to have refractory status epilepticus and required pentobarbital anaesthesia. Overall case fatality was 21%, but death could be attributed directly to status epilepticus and/or treatment complication in 10% of the study group. Major determinants of fatal outcomes were: increasing age, longer duration of status epilepticus before initiation of therapy and central nervous system infection as a causal factor.     

The problem of medium access control in wireless sensor networks

In this article we revisit the problem of scheduled access through a detailed foray into the questions of energy consumption and throughput for MAC protocols in wireless sensor networks. We consider a static network model that rules out simultaneous transmission and reception by any sensor node and consequently requires partitioning of nodes into disjoint sets of transmitters and receivers at any time instant. Under the assumption of circular transmission (reception) ranges with sharp boundaries, a greedy receiver activation heuristic is developed relying on the network connectivity map to determine distinct receiver groups to be activated within disjoint time intervals. To conserve limited energy resources in sensor networks, the time allocation to each receiver group is based on the residual battery energy available at the respective transmitters. Upon activating each receiver group separately, the additional time-division mechanism of group TDMA is imposed to schedule transmissions interfering at the non-intended destinations within separate fractions of time in order to preserve the reliable feedback information. The two-layered time-division structure of receiver activation and group TDMA algorithms offers distributed and polynomial-time solutions (as required by autonomous sensor networks) to the problems of link scheduling as well as energy and throughput-efficient resource allocation in wireless access. The associated synchronization and overhead issues are not considered in this article.