Amplification by stochastic interference

A new method is introduced to obtain a strong signal by the interference of weak signals in noisy channels. The method is based on the interference of 1/f noise from parallel channels. One realization of stochastic interference is the auditory nervous system. Stochastic interference may have broad potential applications in the information transmission by parallel noisy channels

Experimental in vivo fenestration of guinea pig cochlea using 2.79 Μm laser radiation

Erbium-YSGG laser systems are promising tools in ear, nose and throat (ENT) surgery. The high absorption in biological tissues, resulting in precise tissue ablation with minimal thermal tissue damage, and the possibility to guide the radiation through optical fibres make the 2.79 Μm wavelength a favourite for microsurgery. In order to simulate the fenestration of the human stapes foot plate required for prosthesis implantation when treating otosclerosis, five guinea pig cochleae were irradiated in vivo until perforation was achieved. The laser-induced temperature rise and pressure transients evoke activity in the inner hair cells that was investigated by micro-iontophoresis. Perforation of the cochlea bone (hole diameter of 350 Μm) can be performed with a few laser pulses and high precision with a thermal damage zone of<100 Μm. The bone ablation rate is 10 ± 2 Μm pulse-1 at a radiant exposure of 12 J cm-2. The functionality of the afferent inner hair cells in the guinea pig cochlea was verified before and after laser treatment using glutamate receptor agonists AMPA and NMDA. For the above selected laser parameters, the induced 15-min enhanced activity was blockable with the specific reversible AMPA and NMDA antagonists CNQX and AP-7. Micro-iontophoresis confirms the reversibility of cochlea functionality after its perforation with Er-YSGG laser pulses. A limit of radiant exposure around 12 J cm-2 is found for safe fenestration. It is demonstrated that the Er-YSGG laser is a precise and safe instrument whilst still using adequate laser parameters. On the other hand, this study demonstrates the potential of uncontrollable and unintended induced damage, resulting from vapour channel formation in the perilymph, if a high laser radiant exposure is applie

Hydraulic engineering in the 21st century: Where to?

For centuries, hydraulic engineers were at the forefront of science. The last forty years marked a change of perception in our society with a focus on environmental sustainability and management, particularly in developed countries. Herein, the writer illustrates his strong belief that the future of hydraulic engineering lies upon a combination of innovative engineering, research excellence and higher education of quality. This drive continues a long tradition established by eminent scholars like Arthur Thomas IPPEN, John Fisher KENNEDY and Hunter ROUSE

Drag Reduction in Open Channel Flow by Aeration and Suspended Load

In supercritical open channel flows air is entrained at the free surface. Such air-water flows, called self-aerated flows, exhibit smaller friction losses than non-aerated flows. New data on drag reduction in self-aerated flows are presented. It is shown that the drag reduction process is linked with the presence of an air concentration boundary layer next to the channel bottom. An analogy with dilute polymer solutions and micro bubble modified boundary layers is developed and it is suggested that the presence of air next to the bottom increases the effective viscosity of the mixture and the sublayer thickness. A parallel with sediment laden flows is also developed. Although the distribution of suspended sediments differs from the distribution of air bubbles, it is suggested that the mechanisms of drag reduction observed in suspended sediment flows are similar to those in self-aerated flows