A market concept for media problems: A few theses
The author explores the concept of markets and marketplaces and how they apply to media and research on media activities. He argues that media markets cannot be considered to be self‐defining, self‐regulatory systems because of their interdependent relations with other subsystems in society, and that traditional regulatory policies are inadequate for dealing with contemporary media because of changing temporal and social factors.
Cross-diagnostic validity of the Nottingham health profile index of distress (NHPD)
BackgroundThe Nottingham Health Profile index of Distress (NHPD) has been proposed as a generic undimensional 24-item measure of illness-related distress that is embedded in the Nottingham Health Profile (NHP). Data indicate that the NHPD may have psychometric advantages to the 6-dimensional NHP profile scores. Detailed psychometric evaluations are, however, lacking. Furthermore, to support the validity of the generic property of outcome measures evidence that scores can be interpreted in the same manner in different diagnostic groups are needed. It is currently unknown if NHPD scores have the same meaning across patient populations. This study evaluated the measurement properties and cross-diagnostic validity of the NHPD as a survey instrument among people with Parkinson's disease (PD) and peripheral arterial disease (PAD).MethodsData from 215 (PD) and 258 (PAD) people were Rasch analyzed regarding model fit, reliability, differential item functioning (DIF), unidimensionality and targeting. In cases of cross-diagnostic DIF this was adjusted for and the impact of DIF on the total score and person measures was assessed.ResultsThe NHPD was found to have good overall and individual item fit in both disorders as well as in the pooled sample, but seven items displayed signs of cross-diagnostic DIF. Following adjustment for DIF some aspects of model fit were slightly compromised, whereas others improved somewhat. DIF did not impact total NHPD scores or resulting person measures, but the unadjusted scale displayed minor signs of multidimensionality. Reliability was > 0.8 in all within- and cross-diagnostic analyses. Items tended to represent more distress (mean, 0 logits) than that experienced by the sample (mean, -1.6 logits).ConclusionThis study supports the within- and cross-diagnostic validity of the NHPD as a survey tool among people with PD and PAD. We encourage others to reassess available NHP data within the NHPD framework to further evaluate the strengths and weaknesses of this simple patient-reported index of illness-related distress.
Ceramic microwave antennas for mobile applications
Due to their medium to high permittivity values, ceramic microwave materials are attractive as building blocks for miniaturised antenna solutions. Further advantages are low dielectric losses and an excellent temperature stability of standard ceramic materials. Yet, the permittivity of the ceramic material also has a strong influence on the radiation efficiency and bandwidth of the antenna. This implies that in the design process a suitable compromise has to be found between the degree of miniaturisation on the one hand and the antenna efficiency and bandwidth on the other. We describe two approaches towards efficient miniaturised ceramic microwave antennas: the dielectric resonator antenna (DRA) with partial metallisation and the shorting post patch antenna. We focus on design steps taken to ensure both a high degree of miniaturisation and high values of the radiation efficiency, the choice of the ceramic material and the experimental performance of the antennas.