Abstract-Disruption of leptin signaling is associated with obesity, heart failure, and cardiac hypertrophy, but the role of leptin in cardiac myocyte apoptosis is unknown. We tested the hypothesis that apoptosis increases in leptin-deficient ob/ob and leptin-resistant db/db mice and is associated with aging and left ventricular hypertrophy, increased DNA damage, and decreased survival. We studied young (2-to 3-month-old) and old (12-to 14-month-old) ob/ob and db/db mice and wild-type (WT) controls (nϭ2 to 4 per group). As expected, ventricular wall thickness and heart weights were similar among young ob/ob, db/db, and WT mice, but higher in old ob/ob and db/db versus old WT. Young ob/ob and db/db showed markedly elevated apoptosis by TUNEL staining and caspase 3 levels compared with WT. Differences in apoptosis were further accentuated with age. Leptin treatment significantly reduced apoptosis in ob/ob mice both in intact hearts and isolated myocytes. Tissue triglycerides were increased in ob/ob hearts, returning to WT levels after leptin repletion. Furthermore, the DNA damage marker, 8oxoG (8-oxo-7,8-dihydroguanidine), was increased, whereas the DNA repair marker, MYH glycosylase, was decreased in old ob/ob and db/db compared with old WT mice. Both ob/ob and db/db mice had decreased survival compared with WT mice. We conclude that leptin-deficient and leptin-resistant mice demonstrate increased apoptosis, DNA damage, and mortality compared with WT mice, suggesting that normal leptin signaling is necessary to prevent excess age-associated DNA damage and premature mortality. These data offer novel insights into potential mechanisms of myocardial dysfunction and early mortality in obesity.

obile ad hoc networks (MANETs) are distinguished from other types of networks by their physical characteristics, organizational format, and dynamic topology:• Physical characteristics: Wireless channels are inherently error-prone, due to effects such as multipath fading, interference, and shadowing; causing unpredictable link bandwidth and packet delay.• Organizational format: The distributed nature of MANETs means that channel resources cannot be assigned in a predetermined way.• Dynamic topology: As hosts in a MANET are mobile, links are created and destroyed in an unpredictable way. Therefore, the network status can change quickly, causing hosts to have imprecise knowledge of the current network state. Because of device mobility in MANETs and the shared nature of the wireless medium, offering guaranteed quality of service (QoS), such as bandwidth, delay, delay jitter, and packet delivery ratio, is not practical. Therefore, soft QoS and QoS adaptation are proposed instead. Soft QoS implies that failure to meet QoS is allowed, for example, when routes break or the network becomes partitioned [1]. However, if a network changes too fast to propagate the topology status information, it is challenging to offer even soft QoS. Therefore, combinatorial stability -which means that given a specific time window topology changes occur sufficiently slowly to allow successful propagation of all topology updates as necessary [2] -must be met in order to provide QoS.Certain applications, such as real-time applications that can optimize their performance based on feedback about network resource availability, can benefit from QoS adaptation. For example, layered coding allows enhanced layers of different quality levels to be transmitted, provided a minimum bandwidth is guaranteed for transmitting the base layer. By providing feedback to the application about available resources, the application can alter its coding strategy to provide the best quality for the current resource limitations.Routing is used to set up and maintain routes between nodes to support data transmission. Early MANET routing protocols focused on finding a feasible route from a source to a destination, without any consideration for optimizing the utilization of network resources or for supporting specific application requirements. To support QoS, the essential problem is to find a route with sufficient available resources to meet the QoS constraints and possibly to incorporate optimizations, such as finding the lowest cost or most stable of the routes that meet the QoS constraints. Given these goals, the following are the basic design considerations for a QoS-aware routing protocol.• Resource estimation: To offer a resource-guaranteed route, the key concept is to obtain information about the available resources from lower layers. This information helps in performing call admission and QoS adaptation. Most existing techniques focus on bandwidth and/or delay QoS constraints, and thus, the bandwidth available to a node or link and/or the delay must be estimated...

Currently, wireless sensor network has been widely used in environment monitoring. The skyline query, as an important operator for multiple criteria decision making and data mining, plays an important role in many sensing applications. Though skyline queries have been well-studied in traditional database system, the existing solutions designed for data stored in a centralized site are not directly applicable to sensor environment due to the unique characteristics of wireless sensor network. In this paper, we propose an energy-efficient algorithm, called Sliding Window Skyline Monitoring Algorithm (SWSMA), to continuously maintain sliding window skylines over a wireless sensor network. Specifically, SWSMA employs two types of filters within each sensor to reduce the amount of data transferred and save the energy consumption as a consequence. In addition to SWSMA, a set of optimization mechanisms are also discussed to improve the performance of SWSMA. Our extensive simulation studies show that SWSMA together with the optimization techniques performs effectively on reducing communication cost and saving the energy on monitoring sliding window skylines.

We propose in this paper an optimized, polymorphic, hybrid multicast routing protocol for MANET. This new polymorphic protocol attempts to benefit from the high efficiency of proactive behavior (in terms of quicker response to transmission requests) and the limited network traffic overhead of the reactive behavior, while being power, mobility, and vicinity-density (in terms of number of neighbor nodes per specified area around a mobile node) aware. The proposed protocol is based on the principle of adaptability and multibehavioral modes of operations. It is able to change behavior in different situations in order to improve certain metrics like maximizing battery life, reducing communication delays, improving deliverability, etc. The protocol is augmented by an optimization scheme, adapted from the one proposed for the Optimized Link State Routing protocol (OLSR) in which only selected neighbor nodes propagate control packets to reduce the amount of control overhead. Extensive simulations and comparison to peer protocols demonstrated the effectiveness of the proposed protocol in improving performance and in extending battery power longevity.

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Sensor networks face a number of challenges when deployed in unpredictable environments under dynamic, quickly changeable demands, and when shared by many partners, which is often the case in military and security applications. To partially address these challenges, we present a novel target tracking algorithm that can be deployed on various sensor nodes and invoked dynamically when needed by the presence of targets. We also demonstrate that an auction-based mechanism can be used to provide efficient and localized wireless sensor network congestion management for bursty traffic of abstract services based just on user-assigned priorities to different services and the quality of information provided by the services. We present results from using this auction mechanism to resolve congestion caused by packets from competing target tracking missions.

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