Swedish Defence Research Agency

About: Swedish Defence Research Agency is a government organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Radar & Laser. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

Factors Determining the 13 C Abundance of Soil-Respired CO 2 in Boreal Forests

Abstract: Analysis of the isotopic composition of the CO 2 respired from soils may reveal information about the important component of the ecosystem C balance. This is crucial, since a large terrestrial sink for atmospheric CO 2 has been located in the northern hemisphere, and the vast boreal forests may be largely responsible. At the same time, boreal and arctic ecosystems have large amounts of C stored in the soil, and could potentially become a source of CO 2 in a warmer climate promoting more rapid decomposition of soil organic matter. Furthermore, the northern hemisphere has complex dynamics in terms of annual fluctuations in both the concentration of CO 2 in the atmosphere and its δ l3 C. It is of utmost importance to understand the causes of this variability, since it interferes with the partitioning between the ocean and the terrestrial contributions in global models. This chapter aims to provide an update on the reviews by Flanagan and Ehleringer and Ehleringer et al. on the causation of the δ 13 C of the soil CO 2 efflux and, in doing this, focuses on the boreal forests.

The contribution of hypoxia to the association between sleep apnoea, insomnia, and cardiovascular mortality in community-dwelling elderly with and without cardiovascular disease.

Abstract: Aims: This study explores if nightly hypoxia (i.e. percentage of sleep time with oxygen saturation lower than 90% (SaO2<90%)) contributed to the association between sleep-disordered breathing (S ...

Iterative Reception for Acoustic Underwater MIMO Communications

Abstract: This paper presents a soft input/soft output linear equalizer for Alamouti encoded MIMO signals. The derived structure allows for simultaneous equalization of MIMO channels and decoding of Alamouti coded signals. The equalizer/decoder is here used within the turbo equalization framework to exploit the complex and rich characteristics of the acoustic underwater channel. Such schemes can operate ate very low Signal-to-Noise Ratio (SNR) levels enabling high transmission rates over long distances. We investigate the viability of the technique by using a simulation example and by studying its behavior for a real scenario, using data collected in the Baltic sea.

Evaluating Algorithms for Detection of Compromised Social Media User Accounts

Abstract: Hijacking of user accounts on Online Social Networks (OSNs) such as Twitter is increasingly used for purposes such as large-scale spam campaigns and cyber crime-related scams and phishing attacks, but also for purposes such as spreading terrorism propaganda and as part of information operations in political and military conflicts. We present a novel method for evaluation of the performance of algorithms for detection of compromised social media accounts. In short, we create two artificially "hijacked accounts" by randomly selecting two genuine user accounts and after a number of successive posts switch the remaining posts between them. This allows us to create large amounts of training and/or test data, something which is not easy to find for this problem. Further, the developed method is utilized to evaluate the performance of a modified version of the existing COMPA system.