Τρίτη 2 Ιανουαρίου 2018

Robustness of an innate releasing mechanism against degradation of acoustic communication signals in the grasshopper Chorthippus biguttulus

Abstract

Noise is a challenge for animals that use acoustic communication to find a mate. A potent source of noise in animal communication is that arising from other conspecific signals, whose co-occurrence can result in extensive interference—evident as the so called "cocktail-party problem"—that may affect the receiver mechanisms to detect potential mates. We studied grasshopper females to explore how modifications of the song pattern influence song recognition. First, we degraded an attractive model song with random fluctuations of increasing amplitudes out of different frequency bands, and determined "critical degradation levels" at which the females ceased to respond. A masker band with frequencies between 0 and 200 Hz, which covers the frequency range of the natural song envelope, was by 3–5 dB more destructive in hampering signal recognition than frequencies above 200 Hz. As second approach, we applied temporal disturbances such as accentuations or gaps at different positions within the song subunits and observed how response behavior was affected. Accentuations at subunit start increased, whereas those in the midst or at the end of a subunit reduced attractiveness. Gaps at these positions had diverse effects. The results are discussed with respect to neuronal filtering.



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Neighborhood Disadvantage and Neighborhood Affluence: Associations with Breastfeeding Practices in Urban Areas

Abstract

Objective To estimate the associations between neighborhood disadvantage and neighborhood affluence with breastfeeding practices at the time of hospital discharge, by race-ethnicity. Methods We geocoded and linked birth certificate data for 111,596 live births in New Jersey in 2006 to census tracts. We constructed indices of neighborhood disadvantage and neighborhood affluence and examined their associations with exclusive (EBF) and any breastfeeding in multilevel models, controlling for individual-level confounders. Results The associations of neighborhood disadvantage and affluence with breastfeeding practices differed by race-ethnicity. The odds of EBF decreased as neighborhood disadvantage increased for all but White women [Asian: Adjusted odds ratio (AOR) 0.82 (95% confidence interval (CI) 0.69–0.97); Black: AOR 0.77 (95% CI 0.70–0.86); Hispanic: AOR 0.78 (95% CI 0.70–0.86); White: AOR 0.99 (95% CI 0.91–1.08)]. The odds of EBF increased as neighborhood affluence increased for Hispanic [AOR 1.19 (95% CI 1.08–1.31)] and White [AOR 1.12 (95% CI 1.06–1.18)] women only. The odds of any breastfeeding decreased with increasing neighborhood disadvantage only for Hispanic women [AOR 0.85 (95% CI 0.79–0.92)], and increased for White women [AOR 1.16 (95% CI 1.07–1.26)]. The odds of any breastfeeding increased as neighborhood affluence increased for all except Hispanic women [Asian: AOR 1.31 (95% CI 1.13–1.51); Black: AOR 1.19 (95% CI 1.07–1.32); Hispanic: AOR 1.08 (95% CI 0.99–1.18); White: AOR 1.30 (95% CI 1.24–1.38)]. Conclusions Race-ethnic differences in associations between neighborhood disadvantage and affluence and breastfeeding practices at the time of hospital discharge indicate the need for specialized support to improve access to services.



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Low night-time heart rate is longitudinally associated with lower augmentation index and central systolic blood pressure in hypertension

Abstract

Purpose

Several studies have shown that the augmentation index (AIx) is negatively correlated with heart rate (HR). This led some authors to claim that the use of HR-lowering drugs may be detrimental in hypertension. The aim of this study was to assess the longitudinal and cross-sectional relationships of HR with AIx and central blood pressure (BP) in 346 subjects from the HARVEST (mean age 30.7 ± 8.5 years).

Methods

At baseline, HR was measured with 24-h ambulatory recording. Central hemodynamics were evaluated with Specaway DAT system after a median of 8.0 years from baseline. In multivariate linear regression analyses, AIx and central systolic BP were used as dependent variables and night-time HR or office HR as predictors adjusting for several risk factors and confounders.

Results

In fully adjusted models, baseline night-time HR was a significant positive predictor of AIx (p < 0.001) and central BP (p = 0.014) measured 8 years later. Adjusted office HR measured at the time of arterial distensibility assessment was inversely correlated with AIx (p = 0.001) a relationship which was attenuated after physical activity (p = 0.004) and left ventricular ejection time (p = 0.015) were taken into account. In addition, office HR was inversely correlated with central BP (p = 0.039) a relationship which was no longer significant after physical activity and ejection time were accounted for.

Conclusions

These data show that HR measured during sleep is longitudinally associated with AIx and central BP. Thus, low HR in the long term may have beneficial effects on central hemodynamics and the wall properties of the large arteries in hypertension.



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Δευτέρα 1 Ιανουαρίου 2018

The need to be aware of potential adverse effects

Abstract

We are pleased with the attention garnered by our recent publication in The Journal of Physiology investigating the potential of N-acetylcysteine as a therapeutic treatment for Duchenne muscular dystrophy (DMD).

This article is protected by copyright. All rights reserved



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CrossTalk proposal: an important astrocyte-to-neuron lactate shuttle couples neuronal activity to glucose utilisation in the brain



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CrossTalk opposing view: lack of evidence supporting an astrocyte-to-neuron lactate shuttle coupling neuronal activity to glucose utilisation in the brain



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Rebuttal from L. F. Barros and B. Weber



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