A Multi-objective Approach for Data Collection in Wireless Sensor Networks

International audienceWireless sensors networks (WSNs) are deployed to collect huge amounts of data from the environment. This produced data has to be delivered through sensor's wireless interface using multi-hop communications toward a sink. The position of the sink impacts the performance of the wireless sensor network regarding delay and energy consumption especially for relaying sensors. Optimizing the data gathering process in multi-hop wireless sensor networks is, therefore, a key issue. This article addresses the problem of data collection using mobile sinks in a WSN. We provide a framework that studies the trade-off between energy consumption and delay of data collection. This framework provides solutions that allow decision makers to optimally design the data collection plan in wireless sensor networks with mobile sinks

Beyond 8 THz Displacement-field Nano-switches for 5G and 6G Communications

The rapid progress in high capacity communication systems is reaching extremely high data rates of 100 Gb s−1, which demands electronic switches with cut-off frequencies well above 1 THz. The excellent electron transport properties of III-V heterojunctions could potentially enable terahertz devices, however, the high parasitic capacitances and contact resistances in traditional ultra-scaled electronic devices, such as transistors and diodes, hinder their potential. Here we demonstrate that the fast switching of displacement fields strongly confined in a few-nanometers-thin crystal between a textured metal and an electron sheet, so called displacement-field nano-switch, can provide cut-off frequencies above 8 THz, enabling an efficient switching of terahertz signals. The device offers extremely low ON state resistances approaching 100 Ω μm, low parasitic capacitances in range of 100 aF μm−1, excellent impedance matching capability, and fast switching times down to 10 ps. We demonstrate the application of these devices for high data rate modulation and mixing. The outstanding performance and integration capability of displacement-field nano-switches pave the way towards mm-wave and terahertz integrated circuits with applications in 5G and 6G communications, among others

Thigh-length compression stockings and DVT after stroke

Controversy exists as to whether neoadjuvant chemotherapy improves survival in patients with invasive bladder cancer, despite randomised controlled trials of more than 3000 patients. We undertook a systematic review and meta-analysis to assess the effect of such treatment on survival in patients with this disease