Echocardiography and assessing fluid responsiveness: acoustic quantification again into the picture?

Accurate identification of fluid responsiveness has become an important issue in critically ill patients. Pulse pressure and stroke volume variation have been shown to be reliable predictors of fluid responsiveness. Apart from these two valuable techniques, echo-Doppler offers an interesting alternative for estimating the adequacy of filling. Acoustic quantification is a high-tech tool for delineating the blood-tissue interface on-screen in real time. Cannesson and coworkers utilized this technique in ventilated patients to assess stroke area changes, with the intention being to predict fluid responsiveness

Quasiparticle energy relaxation in superconducting tunnel junctions used as photon detectors

We exploit the results of recent work (Poelaert, Ph.D. Thesis, University of Twente, 1999) showing that energetic quasiparticles in a superconductor relax to an energy, called balance energy, larger than the superconducting energy gap, despite of the large density of states available at the gap. This feature may have a major impact on the performance of superconducting tunnel junctions used as photon detectors. We show how the balance energy and the parameters for photon detection are sensitive to the superconducting proximity effect. In particular, we show that the balance energy also exists for non-proximized structures, obeying the BCS theory

Lattice-dynamics of a Disordered solid-solid Interface

Generic properties of elastic phonon transport at a disordered interface are studied. The results show that phonon transmittance is a strong function of frequency and the disorder correlation length. At frequencies lower than the van Hove singularity the transmittance at a given frequency increases as the correlation length decreases. At low frequencies, this is reflected by different power-laws for phonon conductance across correlated and uncorrelated disordered interfaces which are in approximate agreement with perturbation theory of an elastic continuum. These results can be understood in terms of simple mosaic and two-colour models of the interface.Comment: 17 pages, 5 figures, submitted to PR

Training in critical care echocardiography

Echocardiography is useful for the diagnosis and management of hemodynamic failure in the intensive care unit so that competence in some elements of echocardiography is a core skill of the critical care specialist. An important issue is how to provide training to intensivists so that they are competent in the field. This article will review issues related to training in critical care echocardiography