Opportunistic Routing for Multi-flow Video Dissemination over Flying Ad-Hoc Networks

A reliable and robust routing service for Flying Ad-Hoc Networks (FANETs) must be able to adapt to topology changes. User experience on watching live video sequences must also be satisfactory even in scenarios with buffer overflow and high packet loss ratio. In this paper, we introduce a Cross-layer Link quality and Geographical-aware beaconless opportunistic routing protocol (XLinGO). It enhances the transmission of simultaneous multiple video flows over FANETs by creating and keeping reliable persistent multi-hop routes. XLinGO considers a set of cross-layer and human-related information for routing decisions, as performance metrics and Quality of Experience (QoE). Performance evaluation shows that XLinGO achieves multimedia dissemination with QoE support and robustness in a multi-hop, multi-flow, and mobile network environments.

A Comparative Analysis of Beaconless Opportunistic Routing Protocols for Video Dissemination over Flying Ad-Hoc Networks

A reliable and robust routing service for Flying Ad-Hoc Networks (FANETs) must be able to adapt to topology changes, and also to recover the quality level of the delivered multiple video flows under dynamic network topologies. The user experience on watching live videos must also be satisfactory even in scenarios with network congestion, buffer overflow, and packet loss ratio, as experienced in many FANET multimedia applications. In this paper, we perform a comparative simulation study to assess the robustness, reliability, and quality level of videos transmitted via well-known beaconless opportunistic routing protocols. Simulation results shows that our developed protocol XLinGO achieves multimedia dissemination with Quality of Experience (QoE) support and robustness in a multi-hop, multi-flow, and mobile networks, as required in many multimedia FANET scenarios.

Cross-Layer Optimizations for Multimedia Distribution over Wireless Multimedia Sensor Networks and Flying Ad-Hoc Networks with Quality of Experience Support

The proliferation of multimedia content and the demand for new audio or video services have fostered the development of a new era based on multimedia information, which allowed the evolution of Wireless Multimedia Sensor Networks (WMSNs) and also Flying Ad-Hoc Networks (FANETs). In this way, live multimedia services require real-time video transmissions with a low frame loss rate, tolerable end-to-end delay, and jitter to support video dissemination with Quality of Experience (QoE) support. Hence, a key principle in a QoE-aware approach is the transmission of high priority frames (protect them) with a minimum packet loss ratio, as well as network overhead. Moreover, multimedia content must be transmitted from a given source to the destination via intermediate nodes with high reliability in a large scale scenario. The routing service must cope with dynamic topologies caused by node failure or mobility, as well as wireless channel changes, in order to continue to operate despite dynamic topologies during multimedia transmission. Finally, understanding user satisfaction on watching a video sequence is becoming a key requirement for delivery of multimedia content with QoE support. With this goal in mind, solutions involving multimedia transmissions must take into account the video characteristics to improve video quality delivery. The main research contributions of this thesis are driven by the research question how to provide multimedia distribution with high energy-efficiency, reliability, robustness, scalability, and QoE support over wireless ad hoc networks. The thesis addresses several problem domains with contributions on different layers of the communication stack. At the application layer, we introduce a QoE-aware packet redundancy mechanism to reduce the impact of the unreliable and lossy nature of wireless environment to disseminate live multimedia content. At the network layer, we introduce two routing protocols, namely video-aware Multi-hop and multi-path hierarchical routing protocol for Efficient VIdeo transmission for static WMSN scenarios (MEVI), and cross-layer link quality and geographical-aware beaconless OR protocol for multimedia FANET scenarios (XLinGO). Both protocols enable multimedia dissemination with energy-efficiency, reliability and QoE support. This is achieved by combining multiple cross-layer metrics for routing decision in order to establish reliable routes.

Context-aware Adaptation Mechanism for Video Dissemination over Flying Ad-Hoc Networks

The user experience on watching live video se- quences transmitted over a Flying Ad-Hoc Networks (FANETs) must be considered to drop packets in overloaded queues, in scenarios with high buffer overflow and packet loss rate. In this paper, we introduce a context-aware adaptation mechanism to manage overloaded buffers. More specifically, we propose a utility function to compute the dropping probability of each packet in overloaded queues based on video context information, such as frame importance, packet deadline, and sensing relevance. In this way, the proposed mechanism drops the packet that adds the minimum video distortion. Simulation evaluation shows that the proposed adaptation mechanism provides real-time multimedia dissemination with QoE support in a multi-hop, multi-flow, and mobile network environments.

Stab or throw? Biomechanical studies on the injuring potential of glass fragments

During a Christmas party, two male guests started fighting. The perpetrator was allegedly pushed onto a glass table by the victim or fell into the table together with that man so that the glass top broke and caused a cut wound on the perpetrator's back. According to his statement he then threw a fragment of the broken glass table in the direction of the other man hitting him accidentally in a way so that the subclavian artery was severed and he died from exsanguination. Tests on the breaking characteristics of the glass table, the flying behaviour and the kinetics of thrown glass fragments conducted on various models supported the conclusion that the fatal injury on the victim's neck could not have been caused by a thrown glass fragment. It was much more likely that a stab with a blade-shaped glass fragment was the cause of the fatal injuries.

Small hive beetles, Aethina tumida, are vectors of Paenibacillus larvae

The transmission of honeybee pathogens by free-flying pests, such as small hive beetles (=SHB), would be independent of bees and beekeepers and thereby constitute a new challenge for pathogen control measures. Here we show that larval and adult SHB become contaminated with Paenibacillus larvae spores when exposed to honeybee brood combs with clinical American foulbrood (=AFB) symptoms in the laboratory. This contamination persists in pupae and newly emerged adults. After exposure to contaminated adult SHB, honeybee field colonies showed higher numbers of P. larvae spores in worker and honey samples after five weeks. Despite these results, the rather low number of P. larvae spores on adult SHB suggests that clinical AFB outbreaks are not likely. However, even small spore numbers can be sufficient to spread P. larvae. Therefore, our data clearly show that SHB are vectors of P. larvae. We suggest considering the role of SHB in AFB control in areas where both pests are established.

Differentiation of ante-mortem and post-mortem fractures with MRI: a case report

We describe a case of a fatal speed flying accident in which the victim was electrocuted, burned and fell from a great height. Post-mortem imaging revealed acute appearing fractures on CT, without bone marrow oedema on MRI. Based on the known clinical imaging findings of bone marrow oedema in acute fractures, we concluded that the speed flyer died from electrocution rather than the fall and that the fractures occurred post-mortem. Radiological imaging augmented the reconstruction of the peri-mortem events. Further research is needed to assess whether bone marrow oedema in acute fractures is a reliable vital sign.

UAVNet: A Mobile Wireless Mesh Network Using Unmanned Aerial Vehicles

We developed UAVNet, a framework for the autonomous deployment of a flying Wireless Mesh Network using small quadrocopter-based Unmanned Aerial Vehicles (UAVs). The flying wireless mesh nodes are automatically interconnected to each other and building an IEEE 802.11s wireless mesh network. The implemented UAVNet prototype is able to autonomously interconnect two end systems by setting up an airborne relay, consisting of one or several flying wireless mesh nodes. The developed software includes basic functionality to control the UAVs and to setup, deploy, manage, and monitor a wireless mesh network. Our evaluations have shown that UAVNet can significantly improve network performance.

Herbivory in Spiders: The Importance of Pollen for Orb-Weavers

Orb-weaving spiders (Araneidae) are commonly regarded as generalist insect predators but resources provided by plants such as pollen may be an important dietary supplementation. Their webs snare insect prey, but can also trap aerial plankton like pollen and fungal spores. When recycling their orb webs, the spiders may therefore also feed on adhering pollen grains or fungal spores via extraoral digestion. In this study we measured stable isotope ratios in the bodies of two araneid species (Aculepeira ceropegia and Araneus diadematus), their potential prey and pollen to determine the relative contribution of pollen to their diet. We found that about 25% of juvenile orb-weaving spiders’ diet consisted of pollen, the other 75% of flying insects, mainly small dipterans and hymenopterans. The pollen grains in our study were too large to be taken up accidentally by the spiders and had first to be digested extraorally by enzymes in an active act of consumption. Therefore, pollen can be seen as a substantial component of the spiders’ diet. This finding suggests that these spiders need to be classified as omnivores rather than pure carnivores.

The phenomenology of lucid dreaming: An online survey.

In lucid dreams the dreamer is aware that he or she is dreaming. Although such dreams are not that uncommon, many aspects of lucid dream phenomenology are still unclear. An online survey was conducted to gather data about lucid dream origination, duration, active or passive participation in the dream, planned actions for lucid dreams, and other phenomenological aspects. Among the 684 respondents who filled out the questionnaire, there were 571 lucid dreamers (83.5%). According to their reports, lucid dreams most often originate spontaneously in adolescence. The average lucid dream duration is about 14 minutes. Lucid dreamers are likely to be active in their lucid dreams and plan to accomplish different actions (e.g., flying, talking with dream characters, or having sex), yet they are not always able to remember or successfully execute their intentions (most often because of awakening or hindrances in the dream environment). The frequency of lucid dream experience was the strongest predictor of lucid dream phenomenology, but some differences were also observed in relation to age, gender, or whether the person is a natural or self-trained lucid dreamer. The findings are discussed in light of lucid dream research, and suggestions for future studies are provided.

Adaptive Beaconless Opportunistic Routing for Multimedia Distribution

User experience on watching live videos must be satisfactory even under the inuence of different network conditions and topology changes, such as happening in Flying Ad-Hoc Networks (FANETs). Routing services for video dissemination over FANETs must be able to adapt routing decisions at runtime to meet Quality of Experience (QoE) requirements. In this paper, we introduce an adaptive beaconless opportunistic routing protocol for video dissemination over FANETs with QoE support, by taking into account multiple types of context information, such as link quality, residual energy, buffer state, as well as geographic information and node mobility in a 3D space. The proposed protocol takes into account Bayesian networks to define weight vectors and Analytic Hierarchy Process (AHP) to adjust the degree of importance for the context information based on instantaneous values. It also includes a position prediction to monitor the distance between two nodes in order to detect possible route failure.

Sensitivity and Fragmentation Calibration of the ROSINA Reflectron-type Time-Of-Flight Mass Spectrometer

The goal of this work was to increase the performance and to calibrate one of the ROSINA sensors, the Reflectron-type Time-Of-Flight mass spectrometer, currently flying aboard the ESA Rosetta spacecraft. Different optimization techniques were applied to both the lab and space models, and a static calibration was performed using different gas species expected to be detected in the vicinity of comet 67P/Churyumov-Gerasimenko. The database thus created was successfully applied to space data, giving consistent results with the other ROSINA sensors.