Comment on "On the negative value of dielectric permittivity of the water surface layer" [Appl. Phys. Lett. 83, 4506 (2003)]

The recent interpretation of the positive resonance frequency shift in dielectric resonators loaded by water is reviewed. Instead of the invoked negative dielectric constant of water surface layer, it is demonstrated that the experimental results are fully reproduced by taking into account the dielectric losses of the sample.Comment: PDF Acrobat 4.0 file, 2 pages, 2 figures, submitted to Appl. Phys. Let

Axially open nonradiative structures: an example of single-mode resonator based on the sample holder

The concept of nonradiative dielectric resonator is generalized in order to include axially open configurations having rotational invariance. The resulting additional nonradiative conditions are established for the different resonance modes on the basis of their azimuthal modal index. An approximate chart of the allowed dielectric and geometrical parameters for the TE011 mode is given. A practical realization of the proposed device based on commercial fused quartz tubes is demonstrated at millimeter wavelengths, together with simple excitation and tuning mechanisms. The observed resonances are characterized in their basic parameters, as well as in the field distribution by means of a finite element method. The predictions of the theoretical analysis are well confirmed, both in the general behaviour and in the expected quality factors. The resulting device, in which the sample holder acts itself as single-mode resonating element, combines an extreme ease of realization with state-of-the-art performances. The general benefits of the proposed open single-mode resonators are finally discussed.Comment: 18 pages, 10 figure

Complex Response Function of Magnetic Resonance Spectrometers

A vectorial analysis of magnetic resonance spectrometers, based on traveling wave resonators and including the reference arm and the automatic control of frequency, has been developed. The proposed model, valid also for stationary wave resonators, gives the response function of the spectrometer for any working condition, including scalar detectors with arbitrary response law and arbitrary excitation frequency. The purely dispersive and purely absorptive linear responses are discussed in detail for different scalar detectors. The developed approach allows for optimizing the performances of the spectrometer and for obtaining the intrinsic lineshape of the sample in a very broad range of working conditions. More complex setups can be modeled following the proposed scheme.Comment: PDF Acrobat 4.0 file, 15 pages, 2 figures, revised version with added reference and corrected typo

Video feedback intervention: a case series in the context of childhood hearing impairment

Background: Recent research shows that parental sensitivity can explain a significant and unique amount of growth in speech and language outcomes in children with cochlear implants. In this intervention study we explored the impact of an intervention designed to support parental sensitivity on children's communication development. Aims: This study tests the effect of a complex intervention in the context of childhood hearing impairment using a case study design of three families. Propositions for each case were made using parental report of the child's development in an attempt to identify change in outcome measurements that were not likely to be due to general development in the child or a halo effect from the intervention. Methods and Results: Multiple pre- and post-intervention measures were taken. Outcome measures were mother–child contingencies to vocal utterances, emotional availability and an assessment of early communication in the child. Results for each case showed that improvements in some outcome measurements were found after the intervention and were maintained at follow-up. Conclusions & Implications: Taking account of developmental change in intervention studies with children is challenging. Single-subject intervention studies can be designed to allow research interventions to be tailored to meet families’ specific needs. Video interaction guidance may support pre-linguistic communicative development in children with hearing impairment

Video feedback intervention: a case series in the context of childhood hearing impairment

Background: Recent research shows that parental sensitivity can explain a significant and unique amount of growth in speech and language outcomes in children with cochlear implants. In this intervention study we explored the impact of an intervention designed to support parental sensitivity on children's communication development. Aims: This study tests the effect of a complex intervention in the context of childhood hearing impairment using a case study design of three families. Propositions for each case were made using parental report of the child's development in an attempt to identify change in outcome measurements that were not likely to be due to general development in the child or a halo effect from the intervention. Methods and Results: Multiple pre- and post-intervention measures were taken. Outcome measures were mother–child contingencies to vocal utterances, emotional availability and an assessment of early communication in the child. Results for each case showed that improvements in some outcome measurements were found after the intervention and were maintained at follow-up. Conclusions & Implications: Taking account of developmental change in intervention studies with children is challenging. Single-subject intervention studies can be designed to allow research interventions to be tailored to meet families’ specific needs. Video interaction guidance may support pre-linguistic communicative development in children with hearing impairment