Reduction of the model noise in non-linear reconstruction via an efficient calculation of the incident field: application to a 434 MHz Scanner

Microwave tomography has been drastically boosted by the development of efficient reconstruction algorithms based on an iterative solution of the corresponding non-linear inverse problem. The accuracy of the electric field radiated by the antennas of a microwave scanner, inside the target area, has been shown to play a significant role on the overall image quality. Taking into account the antenna environment is of prime importance, especially when operating at low frequency. For instance, the wall of a 60 cm diameter whole-body microwave scanner cannot be neglected at 434 MHz, even when using the immersion technique consisting of putting the target in water. Indeed, at such a frequency, the attenuation introduced by water is not sufficient to avoid multiple reflections on the scanner boundary walls. Consequently, the method of calculating the incident field constitutes a key factor in iteratively solving non-linear inverse problems. The selected technique must accommodate high accuracy while maintaining acceptable calculation complexity. In this paper, three distinct techniques are analysed. They are based on the use of i) free-space and ii) non free-space Green's function, and iii) a FDTD approach. All these techniques have been firstly investigated for their 2D version, being used in 2D reconstruction algorithms. However, the scattered field data are collected in a 3D scanner. For assessing the validity of the previous 2D techniques, their results have been compared to both experimentally and 3D-FDTD results.Peer ReviewedPostprint (published version

Microwave imaging techniques for biomedical applications

Microwaves have been considered for medical applications involving the detection of organ movements and changes in tissue water content. More particularly cardiopulmonary interrogation via microwaves has resulted in various sensors monitoring ventricular volume change or movement, arterial wall motion, respiratory movements, pulmonary oedema, etc. In all these applications, microwave sensors perform local measurements and need to be displaced for obtaining an image reproducing the spatial variations of a given quantity. Recently, advances in the area of inverse scattering theory and microwave technology have made possible the development of microwave imaging and tomographic instruments. This paper provides a review of such equipment developed at Suplec and UPC Barcelona, within the frame of successive French-Spanish PICASSO cooperation programs. It reports the most significant results and gives some perspectives for future developments. Firstly, a brief historical survey is given. Then, both technological and numerical aspects are considered. The results of preliminary pre-clinical assessments and in-lab experiments allow to illustrate the capabilities of the existing equipment, as well as its difficulty in dealing with clinical situations. Finally, some remarks on the expected development of microwave imaging techniques for biomedical applications are given.Peer ReviewedPostprint (published version

Design, realization and measurements of a miniature antenna for implantable wireless communication systems

The design procedure, realization and measurements of an implantable radiator for telemetry applications are presented. First, free space analysis allows the choice of the antenna typology with reduced computation time. Subsequently the antenna, inserted in a body phantom, is designed to take into account all the necessary electronic components, power supply and bio-compatible insulation so as to realize a complete implantable device. The conformal design has suitable dimensions for subcutaneous implantation (10 x 32.1 mm). The effect of different body phantoms is discussed. The radiator works in both the Medical Device Radiocommunication Service (MedRadio, 401-406 MHz) and the Industrial, Scientific and Medical (ISM, 2.4-2.5 GHz) bands. Simulated maximum gains attain and -28.8 and -18.5 dBi in the two desired frequency ranges, respectively, when the radiator is implanted subcutaneously in a homogenous cylindrical body phantom (80 x 110 mm) with muscle equivalent dielectric properties. Three antennas are realized and characterized in order to improve simulation calibration, electromagnetic performance, and to validate the repeatability of the manufacturing process. Measurements are also presented and a good correspondence with theoretical predictions is registered

Unravelling the complexity of domestication:A case study using morphometrics and ancient DNA analyses of archaeological pigs from Romania

Funding statement. This work was supported by the Natural Environment Research Council (NE/F003382/1) and the Leverhulme Trust (F/00 128/AX) Acknowledgements. Archaeozoological analyses conducted by A. Ba˘la˘s¸escu were supported by three grants from the Romanian National Authority for Scientific Research, CNCS UEFISCDI (PN-II-RU-TE-20113-0146, PN-II-ID-PCE-2011-3-0982 and PN-IIID-PCE-2011-3-1015). We thank the archeologists Ca˘ta˘lin Bem, Alexandru Dragoman, Valentin Dumitras¸cu, Laura Dietrich, Raluca Koga˘lniceanu, Cristian Micu, Sta˘nica Pandrea, Valentin Parnic, George Trohani, Valentina Voinea for the material they generously provided. We thank the many institutions and individuals that provided sample material and access to collections, especially the curators of the Museum fu¨r Naturkunde, Berlin; Muse´um National d’Histoire Naturelle, Paris; Muse´um d’Histoire Naturelle, Gene`ve; Museum fu¨r Haustierkunde, Halle; National Museum of Natural History, Washington; The Field Museum, Chicago and The American Museum of Natural History, New York; The Naturhistorisches Museum, BernPeer reviewedPublisher PD