[Changes in partner relationship after organ transplantation: comparison between heart, liver, and kidney transplantation]

AIM: This study was conducted to delineate partnership-relation functioning over time and specifically matched to various organs such as heart, liver, and kidney. METHOD: Prospective, paralleled case-control-study including patients and their respective partners before and one year after organ transplantation in 23 heart-transplant recipients, 19 liver-transplant patients, and 16 kidney-transplant recipients. To assess partnership functioning, the FB-Z (family assessment measure) of Cierpka and Frevert was used. Statistics included descriptive methods, correlations, and analysis of variance including the items "organ" and "time". RESULTS: Heart-transplant recipients and their partners show significant better overall measures in their partnership ratings (sum-value) in comparison to liver or kidney patients and their partners. In all patient and partner groups, except in kidney-transplant recipients a significant deterioration over time is discernible in the subscales role performance and emotionality. In respect to the item "organ" significant differences were found in overall functioning and the subscale communication where heart-transplant recipients and their partners have significant better functioning compared to kidney or liver transplant patients. In kidney patients and their partners only communication changes to the better in the time course. CONCLUSION: In any organ transplantation the two sides of the coin are important to bear in mind, the one is the live-saving act of transplantation as such, the other is the important distress in the phase before but equally after the operation, mainly in the first year where patients and their respective partners have to be followed and treated even in respect to psychosocial and marital functioning

An anisotropic substrate grounded with a tensor impedance sheet for control of guided-waves and application to planar leaky-wave antenna design

A simple and practical design technique is proposed to control guided-waves on a dielectric substrate. In particular, by introducing longitudinal slots with a transverse and sub-wavelength periodicity in the bottom metallic surface of a dielectric slab, radial surface-wave (SW) fields can be controlled for bound plane-wave propagation. An analysis of this guide is provided were the longitudinal slots for the modified ground plane are modeled by a tensor impedance sheet. Numerical calculations are in agreement with the full-wave simulations were considerations have been made for the structure anisotropy. Routing concepts are further applied to a SW-fed planar leaky-wave antenna (LWA) defined by a transverse array of microstrip lines with periodic width-modulation. Improved realized gain values for the LWA design are observed (more than 2.5 dB) when compared to a conventional ground plane configuration. Our approach for field control can also be applied to new guides and transitions, routing circuits, and other planar structures which operate at microwave and millimeter-wave frequencies

Optimization of planar periodic leaky-wave antennas by selective surface-wave suppression

Planar periodic ‘bull-eye’ leaky-wave antennas are investigated for two-sided frequency beam scanning and broadside radiation at microwave and millimeter-wave frequencies. In particular, the ground plane and the radial configuration of the structures are optimized to support leakage of the fundamental TM mode of the guiding structure in a regime without any other modes, either bound or radiating, while also taking into consideration the TM and TE fields generated by the practical slot source integrated into the bottom ground plane. These design approaches can improve beam scanning quality, reduce reflection losses, minimize cross-polarization levels, and increase antenna gain. In addition, full-wave simulations and antenna measurements are in agreement with the developed Method of Moments dispersion analysis where continuous wide-angle beam scanning is observed over a large radiating bandwidth

Effects of the variation of the dielectric constant for a periodic, width-modulated microstrip line based sensor

Real-time monitoring and quantification of any physical, chemical, and/or mechanical variations within a given environment may be useful for different science and engineering systems. For instance, these type of sensors can monitor variations in temperature, gas-concentration [1], oil contamination [2], etc., and should be low cost, compact and lightweight. One methodology for such devices can be the monitoring of the sensors' electric response due to a particular stimulus from the environment under watch. In addition, these sensors should allow the observation and quantization of even small variations from a nominal value, especially in critical applications, including those related to security. © 2010 IEE

A circuits-based modeling approach for leaky-wave antennas using a transverse equivalent network representation

A modeling approach is developed for planar leaky-wave antennas (LWAs) where the guiding surface is characterized as a scalar transfer impedance such that the structure is represented by its transverse equivalent network in the spectral domain. This modeling procedure allows antenna designers to represent LWAs with an equivalent circuit which includes the antenna source for radiated power calculations and efficiency investigations. To demonstrate these concepts a numerical example is provided of a single-layer metallic strip grating LWA printed on a grounded dielectric slab. Proposed modeling techniques can also be applied to other single-layer LWA structures as well as more advanced multilayer configurations