Modified protein expression in the tectorial membrane of the cochlea reveals roles for the striated sheet matrix

The tectorial membrane (TM) of the mammalian cochlea is a complex extracellular matrix which, in response to acoustic stimulation, displaces the hair bundles of outer hair cells (OHCs), thereby initiating sensory transduction and amplification. Here, using TM segments from the basal, high-frequency region of the cochleae of genetically modified mice (including models of human hereditary deafness) with missing or modified TM proteins, we demonstrate that frequency-dependent stiffening is associated with the striated sheet matrix (SSM). Frequency-dependent stiffening largely disappeared in all three TM mutations studied where the SSM was absent either entirely or at least from the stiffest part of the TM overlying the OHCs. In all three TM mutations, dissipation of energy is decreased at low (<8 kHz) and increased at high (>8 kHz) stimulus frequencies. The SSM is composed of polypeptides carrying fixed charges, and electrostatic interaction between them may account for frequency-dependent stiffness changes in the material properties of the TM. Through comparison with previous in vivo measurements, it is proposed that implementation of frequency-dependent stiffening of the TM in the OHC attachment region facilitates interaction among tones, backward transmission of energy, and amplification in the cochlea

The Development of a Single Frequency Place in the Mammalian Cochlea: The Cochlear Resonance in the Mustached Bat Pteronotus parnellii

Cochlear microphonic potentials (CMs) were recorded from the sharply tuned, strongly resonant auditory foveae of 1- to 5-week-old mustached bats that were anesthetized with Rompun and Ketavet. The fovea processes Doppler-shifted echo responses of the constant-frequency component of echolocation calls. During development, the frequency and tuning sharpness of the cochlear resonance increases, and CM ringing persists for longer after the tone. CM is relatively insensitive at tone onset and grows linearly with increased stimulus level. During the tone, the CM is more sensitive and grows compressively with increased stimulus level and phase leads onset CM by 90° for frequencies below the resonance. CM during the ringing is also sensitive and compressive and phase leads onset CM by 180° below the resonance and lags it by 180° above the resonance. Throughout postnatal development, CMs measured during the tone and in the ringing increase both in sensitivity and compression. The cochlear resonance appears to be attributable to interaction between two oscillators. The more broadly tuned oscillator dominates the onset response, and the narrowly tuned oscillator dominates the ringing. Early in development, mechanical coupling between the oscillators results in a relatively broadly tuned system with several frequency modes in the CM at tone onset and in the CM ringing. Beating occurs between the resonance and the stimulus response during the tone and between two components of the narrowly tuned oscillator at tone offset. At maturity, the CM has three modes for frequencies within 10 kHz of the resonance at tone onset and a single, sharply tuned mode in the ringing

Volatile hydrocarbons inhibit methanogenic crude oil degradation

Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5-nC10, methylcyclohexane, benzene, toluene, and xylenes) were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12-nC34) and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene) were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales) were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 μmol CH4/g sediment/day) with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12-nC34). For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 μmol CH4/g sediment/day). This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers

Synchronization of a Nonlinear Oscillator: Processing the Cf Component of the Echo-Response Signal in the Cochlea of the Mustached Bat

Cochlear microphonic potential (CM) was recorded from the CF2 region and the sparsely innervated zone (the mustached bat's cochlea fovea) that is specialized for analyzing the Doppler-shifted echoes of the first-harmonic (~61 kHz) of the constant-frequency component of the echolocation call. Temporal analysis of the CM, which is tuned sharply to the 61 kHz cochlear resonance, revealed that at the resonance frequency, and within 1 msec of tone onset, CM is broadly tuned with linear magnitude level functions. CM measured during the ongoing tone and in the ringing after tone offset is 50 dB more sensitive, is sharply tuned, has compressive level functions, and the phase leads onset CM by 90°: an indication that cochlear responses are amplified during maximum basilar membrane velocity. For high-level tones above the resonance frequency, CM appears at tone onset and after tone offset. Measurements indicate that the two oscillators responsible for the cochlear resonance, presumably the basilar and tectorial membranes, move together in phase during the ongoing tone, thereby minimizing net shear between them and hair cell excitation. For tones within 2 kHz of the cochlear resonance the frequency of CM measured within 2 msec of tone onset is not that of the stimulus but is proportional to it. For tones just below the cochlear resonance region CM frequency is a constant amount below that of the stimulus depending on CM measurement delay from tone onset. The frequency responses of the CM recorded from the cochlear fovea can be accounted for through synchronization between the nonlinear oscillators responsible for the cochlear resonance and the stimulus tone

Mindfulness-Based Cognitive Therapy: Further Issues in Current Evidence and Future Research

The authors respond to the article by H. F. Coelho, P. H. Canter, and E. Ernst (2007)A. T. Beck, C. H. Ward, M. Mendelson, J. Mock, & J. Erbaugh, 1961) after treatment

Systematic review of topical treatments for fungal infections of the skin and nails of the feet

OBJECTIVE: To identify and synthesise the evidence for efficacy and cost effectiveness of topical treatments for superficial fungal infections of the skin and nails of the feet. DESIGN: Systematic review. INTERVENTIONS: Topical treatments for superficial fungal infections. MAIN OUTCOME MEASURES: Cure confirmed by culture and microscopy for skin and by culture for nails in patients with clinically diagnosed fungal infections. RESULTS: Of 126 trials identified in 121 papers, 72 (57.1%) met the inclusion criteria. Placebo controlled trials yielded pooled relative risks of failure to cure skin infections: allylamines (0.30, 95% confidence interval 0.24 to 0.38); azoles (0.54, 0.42 to 0.68); undecenoic acid (0.28, 0.11 to 0.74); and tolnaftate (0.46, 0.17 to 1.22). Although meta-analysis of 11 trials comparing allylamines and azoles showed a relative risk of failure to cure of 0.88 (0.78 to 0.99) in favour of allylamines, there was evidence of language bias. Seven reports in English favoured allylamines (0.79, 0.69 to 0.91), but four reports in foreign languages showed no difference between the two drugs (1.01, 0.90 to 1.13). Neither trial of nail infections showed significant differences between alternative topical treatments. CONCLUSIONS: Allylamines, azoles, and undecenoic acid were efficacious in placebo controlled trials. There are sufficient comparative trials to judge relative efficacy only between allylamines and azoles. Allylamines cure slightly more infections than azoles but are much more expensive than azoles. The most cost effective strategy is first to treat with azoles or undecenoic acid and to use allylamines only if that fails

A phase field method for tomographic reconstruction from limited data.

Classical tomographic reconstruction methods fail for problems in which there is extreme temporal and spatial sparsity in the measured data. Reconstruction of coronal mass ejections (CMEs), a space weather phenomenon with potential negative effects on the Earth, is one such problem. However, the topological complexity of CMEs renders recent limited data reconstruction methods inapplicable. We propose an energy function, based on a phase field level set framework, for the joint segmentation and tomographic reconstruction of CMEs from measurements acquired by coronagraphs, a type of solar telescope. Our phase field model deals easily with complex topologies, and is more robust than classical methods when the data are very sparse. We use a fast variational algorithm that combines the finite element method with a trust region variant of Newton’s method to minimize the energy. We compare the results obtained with our model to classical regularized tomography for synthetic CME-like images

Learning to manage public service organizations better: A scenario for teaching public administration

In the context of public value, it is argued that there is a need to adopt the learning organization philosophy to manage public service organizations better. For collaborative work with public sector managers or in management education, a fictitious scenario is presented to develop the concept of the learning organization as paradox. Faced with multiple and conflicting demands, public managers find it difficult to change organizational behavior in response to new knowledge. The scenario demonstrates how learning organization philosophy can be used to translate new knowledge into new behaviors. Key skills required for public managers to exploit the knowledge of all organizational members and confront the challenges of a contested concept, such as public value, are developed and comprise: summarizing evidence; making judgements, sharing thought processes on a contentious issue, and arriving at a consensus together. Contributions to public administration theory and practice are discussed

Experimental test of the planar tunneling model for ballistic electron emission spectroscopy

Using planar theory of ballistic electron emission spectroscopy with the addition of scattering at the metal-semiconductor interface, we calculate an expected change in the ratio of the collector current (Ic) to the tunnel current (It) as It is varied in the well-known system Au/GaAs(100). This alternative spectroscopy is performed experimentally and is shown to differ drastically from the theory, which nevertheless agrees well with standard voltage spectroscopy. From this discrepancy, we question the applicability of one-dimensional (1D) planar theory to an inherently 3D system