Energy Minimization Algorithm for Estimation of Clock Skew and Reception Window Selection in Wireless Networks.

The synchronization of time between devices is one of the more important and challenging problems in wireless networks. We discuss the problem of maximization of the probability of receiving a message from a device using a limited listening time window to minimize energy utilization. We propose a solution to two important problems in wireless networks of battery-powered devices: a method of establishing a connection with a device that has been disconnected from the system for a long time and developed unknown skew and also two approaches to follow-up clock synchronization using the confidence interval method. We start with the analysis of measurements of clock skew. The algorithms are evaluated using extensive simulations and we discuss the selection of parameters balancing between minimizing the energy utilization and maximizing the probability of reception of the message. We show that the selection of a time window of growing size requires less energy to receive a packet than using the same size of time window repeated multiple times. The shifting of reception windows can further decrease the energy cost if lower packet reception probability is acceptable. We also propose and evaluate an algorithm scaling the reception window size to the interval between the packet transmission.

Energy-Efficient Crowdsensing of Human Mobility and Signal Levels in Cellular Networks.

The paper presents a practical application of the crowdsensing idea to measure human mobility and signal coverage in cellular networks. Currently, virtually everyone is carrying a mobile phone, which may be used as a sensor to gather research data by measuring, e.g., human mobility and radio signal levels. However, many users are unwilling to participate in crowdsensing experiments. This work begins with the analysis of the barriers for engaging people in crowdsensing. A survey showed that people who agree to participate in crowdsensing expect a minimum impact on their battery lifetime and phone usage habits. To address these requirements, this paper proposes an application for measuring the location and signal strength data based on energy-efficient GPS tracking, which allows one to perform the measurements of human mobility and radio signal levels with minimum energy utilization and without any engagement of the user. The method described combines measurements from the accelerometer with effective management of the GPS to monitor the user mobility with the decrease in battery lifetime by approximately 20%. To show the applicability of the proposed platform, the sample results of signal level distribution and coverage maps gathered for an LTE network and representing human mobility are shown.

[Thrombosis within the area of muscle bridge as a cause of myocardial infarction]. / Zakrzep w obszarze mostka miesniowego jako przyczyna zawalu serca.

Muscle bridge with concomitant sclerotic lesions may cause myocardial infarction (MI). We present a case of 70 year-old woman, who suffered from MI due to sclerotic lesion located within the anterior descending artery, right above the muscle bridge. Implanting two drug eluting stents resulted in restoration of proper flow through the vessel, widening the sclerotic lesion and the area of muscle bridge.

[Left ventricular thrombus--variability of causes and clinical presentation--four case reports]. / Skrzeplina w swietle lewej komory. Róznorodnosc przyczyn i przebiegu klinicznego na podstawie czterech przypadków.

Thrombi occurring in heart chambers, particularly in the left ventricle, are very often due to diseases leading to heart dilation. Thrombi could dissolve spontaneously or as a result of pharmacological treatment. They could also be mobilizes and produce emboli. The risk of emboli vary significantly from low to extremely high due to different morphology and mobility of thrombi. The most effective treatment of thrombi is to cure the underlying disease. Additionally antithrombotic agents or surgical treatment may be applied. In this article 4 cases with different clinical course treated only with drugs are presented.