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.

Laser radar modeling for simulation and performance evaluation

Abstract: Laser radars have the unique capability to give both intensity and full 3-D images of an object or a scene. The latest addition to these capabilities is the possibility to acquire motion. These systems have many civilian and military applications such as terrain modeling, depth sounding, object detection, classification and positioning as well as object tracking. In order to fully understand the performance of laser radars vs experimental data a computer simulation model is of high value. We have developed a modularized computer model capable of modeling performance of a variety of laser radar systems. In order to derive the returned signal waveform from the object one has to account for the laser pulse time characteristics, media effects such as the atmospheric attenuation and scattering as well as object characteristics like shape, BRDF, surface roughness and others. The noise from target speckle and scintillations has to be coupled with detector noise generated by the inherent noise in the detectors and subsequent amplifiers and read out circuitry as well as the noise induced from the optical background. The result can be of help when designing and using new laser radar systems, as well as extending real system parameters and evaluate performance. We will give examples of simulated sensor data in different applications/scenarios together with some real measured data.

Homogenization of the Maxwell Equations: Case II. Nonlinear conductivity

Abstract: The Maxwell equations with uniformly monotone nonlinear electric conductivity in a heterogeneous medium, which may be non-periodic, are homogenized by two-scale convergence. We introduce a new set of function spaces appropriate for the nonlinear Maxwell system. New compactness results, of two-scale type, are proved for these function spaces. We prove existence of a unique solution for the heterogeneous system as well as for the homogenized system. We also prove that the solutions of the heterogeneous system converge weakly to the solution of the homogenized system. Furthermore, we prove corrector results, important for numerical implementations.

Clonality of erythromycin resistance in Francisella tularensis

Abstract: Objectives: We analysed diverse strains of Francisella tularensis subsp. holarctica to assess if its division into biovars I and II is associated with specific mutations previously linked to erythr ...

Whole-genome sequencing reveals distinct mutational patterns in closely related laboratory and naturally propagated Francisella tularensis strains.

Abstract: The F. tularensis type A strain FSC198 from Slovakia and a second strain FSC043, which has attenuated virulence, are both considered to be derivatives of the North American F. tularensis type A strain SCHU S4. These strains have been propagated under different conditions: the FSC198 has undergone natural propagation in the environment, while the strain FSC043 has been cultivated on artificial media in laboratories. Here, we have compared the genome sequences of FSC198, FSC043, and SCHU S4 to explore the possibility that the contrasting propagation conditions may have resulted in different mutational patterns. We found four insertion/deletion events (INDELs) in the strain FSC043, as compared to the SCHU S4, while no single nucleotide polymorphisms (SNPs) or variable number of tandem repeats (VNTRs) were identified. This result contrasts with previously reported findings for the strain FSC198, where eight SNPs and three VNTR differences, but no INDELs exist as compared to the SCHU S4 strain. The mutations detected in the laboratory and naturally propagated type A strains, respectively, demonstrate distinct patterns supporting that analysis of mutational spectra might be a useful tool to reveal differences in past growth conditions. Such information may be useful to identify leads in a microbial forensic investigation.