Design and evaluation of a hybrid radiofrequency applicator for magnetic resonance imaging and RF induced hyperthermia: electromagnetic field simulations up to 14.0 Tesla and proof-of-concept at 7.0 Tesla

This work demonstrates the feasibility of a hybrid radiofrequency (RF) applicator that supports magnetic resonance (MR) imaging and MR controlled targeted RF heating at ultrahigh magnetic fields (B0>/=7.0T). For this purpose a virtual and an experimental configuration of an 8-channel transmit/receive (TX/RX) hybrid RF applicator was designed. For TX/RX bow tie antenna electric dipoles were employed. Electromagnetic field simulations (EMF) were performed to study RF heating versus RF wavelength (frequency range: 64 MHz (1.5T) to 600 MHz (14.0T)). The experimental version of the applicator was implemented at B0 = 7.0T. The applicators feasibility for targeted RF heating was evaluated in EMF simulations and in phantom studies. Temperature co-simulations were conducted in phantoms and in a human voxel model. Our results demonstrate that higher frequencies afford a reduction in the size of specific absorption rate (SAR) hotspots. At 7T (298 MHz) the hybrid applicator yielded a 50% iso-contour SAR (iso-SAR-50%) hotspot with a diameter of 43 mm. At 600 MHz an iso-SAR-50% hotspot of 26 mm in diameter was observed. RF power deposition per RF input power was found to increase with B0 which makes targeted RF heating more efficient at higher frequencies. The applicator was capable of generating deep-seated temperature hotspots in phantoms. The feasibility of 2D steering of a SAR/temperature hotspot to a target location was demonstrated by the induction of a focal temperature increase (DeltaT = 8.1 K) in an off-center region of the phantom. Temperature simulations in the human brain performed at 298 MHz showed a maximum temperature increase to 48.6C for a deep-seated hotspot in the brain with a size of (19x23x32)mm(3) iso-temperature-90%. The hybrid applicator provided imaging capabilities that facilitate high spatial resolution brain MRI. To conclude, this study outlines the technical underpinnings and demonstrates the basic feasibility of an 8-channel hybrid TX/RX applicator that supports MR imaging, MR thermometry and targeted RF heating in one device

The state of play: securities of childhood - insecurities of children

This article is broadly concerned with the positioning of children, both within and outside the subject area of International Relations. It considers the costs of an adult- 5 centric standpoint in security studies and contrasts this with investments made seemingly on behalf of children and their security. It begins by looking at how children and childhoods are constructed and contained - yet also defy categorization - at some cost to their protection. The many competing children and childhoods that are invoked in security discourses and partially sustain their victimcy are then illustrated. It is 10 argued that at their entry point into academia they are essentialized and sentimentalized. Power relations which subvert, yet also rely on children and childhoods can only be disrupted through a reconfiguration of politics and agency which includes an engagement with political literacy on a societal level and acknowledgement of the ubiquitous presence of war in all our live

From a 'terrorist' group to a 'civil defence' corps: the 'transformation' of the Kosovo Liberation Army

The Kosovo Liberation Army, which was regarded as a 'terrorist' group in the early 1990s, has now been 'transformed' into the Kosovo Protection Corps (KPC) with the primary objective of protecting this war-torn province against 'natural' disasters. The creation of a 'civilian', uniformed and 'multi-ethnic' corps is a unique experience for the international community as it has been undertaken by a United Nations interim administration within the sovereignty of a state-the now defunct Federal Republic of Yugoslavia-that had no input during the planning or implementation of this transformation process. In fact, if it ends up comprising the core of a future Kosovar army, as its members hope it will, the KPC is likely to pose a direct threat to the sovereignty of Serbia and Montenegro over Kosovo. This article explores the KPC transformation experience with a security sector reform perspective, focusing on institutional, political, financial and security aspects in order to identify lessons that can inform similar processes elsewhere

Effects of different pretreatment processes on viscose fabrics in different types and properties

In this study, the effects of different pretreatment processes on the properties of viscose fabrics (sulphur content, whiteness degree, weft yarn breaking force, crystallinity and fiber surface) and on the color efficiency and repeatability of the prints have been investigated. For this purpose, viscose fabrics obtained from different sources and containing different amounts of sulphur were causticized, bleached, and reductive-washed. After impregnation with urea, fabrics were printed with two reactive dyestuffs having the same reactivity, but different molecular sizes. Color values of both dyes were measured and fastness was tested and compared in order to observe the effects of different pretreatment processes. Different methods of sulphur analysis were also investigated and tested to determine the sulphur content of the fibres. Among these methods, the lead acetate method, which is a subjective evaluation system, has been selected as the most appropriate for practical working conditions of the plants, and a sulphur scale was formed according to this method. Accuracy of the scale was also confirmed by elemental analysis (CHNS-O) method. © The Textile Institute.This work was supported by the Scientific and Technical Research Council of Turkey, Textile Research Center. -