Measurement of the transfered impendance of the shield cable by the impulse current method using a Fourier processor

This paper is an application of the Fast Fourier Transform for the measurement of the transfer impedance of the shielded cables at the frequencies above 100 MHz . In the first part we present an overview of the principle of the measurement of the transfer impedance . We describe the signal processing method used in this special case . The second part of the paper is related to the Fourier processor designed to compute the Fourier tansform in few seconds and for 2,048 signal samples . We give the main steps of the algorithm and the simplifications which have been used in the numerical code .Mesure de l'impédance de transfert de câbles blindés aux fréquences supérieures à 100 MH

Responses of Auditory Nerve and Anteroventral Cochlear Nucleus Fibers to Broadband and Narrowband Noise: Implications for the Sensitivity to Interaural Delays

The quality of temporal coding of sound waveforms in the monaural afferents that converge on binaural neurons in the brainstem limits the sensitivity to temporal differences at the two ears. The anteroventral cochlear nucleus (AVCN) houses the cells that project to the binaural nuclei, which are known to have enhanced temporal coding of low-frequency sounds relative to auditory nerve (AN) fibers. We applied a coincidence analysis within the framework of detection theory to investigate the extent to which AVCN processing affects interaural time delay (ITD) sensitivity. Using monaural spike trains to a 1-s broadband or narrowband noise token, we emulated the binaural task of ITD discrimination and calculated just noticeable differences (jnds). The ITD jnds derived from AVCN neurons were lower than those derived from AN fibers, showing that the enhanced temporal coding in the AVCN improves binaural sensitivity to ITDs. AVCN processing also increased the dynamic range of ITD sensitivity and changed the shape of the frequency dependence of ITD sensitivity. Bandwidth dependence of ITD jnds from AN as well as AVCN fibers agreed with psychophysical data. These findings demonstrate that monaural preprocessing in the AVCN improves the temporal code in a way that is beneficial for binaural processing and may be crucial in achieving the exquisite sensitivity to ITDs observed in binaural pathways

Multidimensional Characterization and Differentiation of Neurons in the Anteroventral Cochlear Nucleus

Multiple parallel auditory pathways ascend from the cochlear nucleus. It is generally accepted that the origin of these pathways are distinct groups of neurons differing in their anatomical and physiological properties. In extracellular in vivo recordings these neurons are typically classified on the basis of their peri-stimulus time histogram. In the present study we reconsider the question of classification of neurons in the anteroventral cochlear nucleus (AVCN) by taking a wider range of response properties into account. The study aims at a better understanding of the AVCN's functional organization and its significance as the source of different ascending auditory pathways. The analyses were based on 223 neurons recorded in the AVCN of the Mongolian gerbil. The range of analysed parameters encompassed spontaneous activity, frequency coding, sound level coding, as well as temporal coding. In order to categorize the unit sample without any presumptions as to the relevance of certain response parameters, hierarchical cluster analysis and additional principal component analysis were employed which both allow a classification on the basis of a multitude of parameters simultaneously. Even with the presently considered wider range of parameters, high number of neurons and more advanced analytical methods, no clear boundaries emerged which would separate the neurons based on their physiology. At the current resolution of the analysis, we therefore conclude that the AVCN units more likely constitute a multi-dimensional continuum with different physiological characteristics manifested at different poles. However, more complex stimuli could be useful to uncover physiological differences in future studies

Computational science for energy research

Computational science complements theory and experiments. It can deliver knowledge and understanding in application areas where the latter two can not. Computational science is particularly important for the simulation of various energy-related processes, ranging from classical energy processes as combustion and subsurface oil-reservoir flows to more modern processes as wind-farm aerodynamics, photovoltaics and – very challenging from a computational perspective – tokamak-plasma physics. The current special issue finds its origin in the Second Frontiers in Computational Physics Conference, centered around the theme energy, and held 3–5 June 2015 in Zürich, Switzerland. The conference provided a forum for exchanging knowledge and expertise on advanced computational methods for the computer simulation of various energy processes. We hope that the resulting special issue will prove to be informative and useful for researchers interested in computational science for energy research. We thank all people who have helped us in preparing this special issue: the reviewers, the technical editors of the Journal of Computational Physics, and most of all the authors

Binaural and cochlear disparities

Binaural auditory neurons exhibit “best delays” (BDs): They are maximally activated at certain acoustic delays between sounds at the two ears and thereby signal spatial sound location. BDs arise from delays internal to the auditory system, but their source is controversial. According to the classic Jeffress model, they reflect pure time delays generated by differences in axonal length between the inputs from the two ears to binaural neurons. However, a relationship has been reported between BDs and the frequency to which binaural neurons are most sensitive (the characteristic frequency), and this relationship is not predicted by the Jeffress model. An alternative hypothesis proposes that binaural neurons derive their input from slightly different places along the two cochleas, which induces BDs by virtue of the slowness of the cochlear traveling wave. To test this hypothesis, we performed a coincidence analysis on spiketrains of pairs of auditory nerve fibers originating from different cochlear locations. In effect, this analysis mimics the processing of phase-locked inputs from each ear by binaural neurons. We find that auditory nerve fibers that innervate different cochlear sites show a maximum number of coincidences when they are delayed relative to each other, and that the optimum delays decrease with characteristic frequency as in binaural neurons. These findings suggest that cochlear disparities make an important contribution to the internal delays observed in binaural neurons

Transiently responsive protein–polymer conjugates via a ‘grafting-from’ RAFT approach for intracellular co-delivery of proteins and immune-modulators

‘Grafting-from’ RAFT polymerization is used to synthesize protein–polymer conjugates that change from the soluble to the aggregated state in response to temperature, but become fully soluble by acid triggered hydrolysis.</p

Correction: Polymer–protein conjugation <i>via</i> a ‘grafting to’ approach – a comparative study of the performance of protein-reactive RAFT chain transfer agents

Correction for ‘Polymer–protein conjugation via a ‘grafting to’ approach – a comparative study of the performance of protein-reactive RAFT chain transfer agents’ by N. Vanparijs et al., Polym. Chem., 2015, DOI: 10.1039/c4py01224k.</p