The auditory cortex of the house mouse: left-right differences, tonotopic organization and quantitative analysis of frequency representation

Multi-unit electrophysiological mapping was used to establish the area of the left- and right-hemisphere auditory cortex (AC) of the mouse and to characterize various fields within the AC. The AC of the left hemisphere covered a significantly larger (factor of 1.30) area compared to that of the right side. Based on best-frequency (BF) maps and other neuronal response characteristics to tone and noise bursts, five fields (primary auditory field, anterior auditory field, second auditory field, ultrasonic field, dorsoposterior field) and two small non-specified areas could be delimited on both hemispheres. The relative sizes of these fields and areas were similar on both sides. The primary and anterior auditory fields were tonotopically organized with counter running frequency gradients merging in the center of the AC. These fields covered BF ranges up to about 45 kHz. Higher BFs up to about 70 kHz were represented non-tonotopically in the separate ultrasonic field, part of which may be considered as belonging to the primary field. The dorsoposterior and second auditory fields were non-tonotopically organized and neurons had special response properties. These characteristics of the mouse AC were compared with auditory cortical maps of other mammals.     

Fast and Accurate Thickness Determination of Unknown Materials using Terahertz Time Domain Spectroscopy

We present a fast and accurate time domain based algorithm which extracts simultaneously the thickness and refractive index of highly transparent samples from terahertz time domain spectroscopy data. The utilized transfer function considers the Fabry-Perot oscillations of the sample and enables to analyze data with multiple reflections. The algorithm can also be applied to signals corrupted by vapor absorption lines. Since the data extraction takes only fractions of a second, this computation method is well suited for real-time monitoring of industrial processes. We show that the accuracy of the new algorithm is comparable to that of sophisticated, highly accurate and time consumptive frequency domain algorithms.     

Sulfate determines the glucosinolate concentration of horseradish in vitro plants (Armoracia rusticana Gaertn., Mey. & Scherb.)

BACKGROUND: Horseradish plants (Armoracia rusticana) contain high concentrations of glucosinolates. Former studies have revealed that Armoracia plants cultivated in vitro have markedly lower glucosinolate concentrations than those grown in soils. Yet, these studies neglected that the sulfate concentration in the growth medium may have had a strong impact on glucosinolate metabolism. Accordingly, in this study horseradish in vitro plants were cultivated with differing sulfate concentrations and the glucosinolate concentrations were quantified by ion pair HPLC. RESULTS: Cultivation in 1.7 mmol L^?1 sulfate (as used in the prior studies) resulted in the accumulation of 16.2 µmol g^?1 DW glucosinolates, while the glucosinolate concentration increased to more than 23 µmol g^?1 DW when 23.5 mmol L^?1 sulfate was used in the medium. Correspondingly, the glucosinolate concentration decreased to 1.6 µmol g^?1 DW when sulfate concentration was lowered to 0.2 mmol L^?1. CONCLUSION: Since the glucosinolate accumulation in relation to the sulfate concentration follows a typical saturation curve, we deduce that the availability of sulfate determines the glucosinolate concentration in horseradish in vitro plants. © 2012 Society of Chemical Industry     

Modelling the effects of environmental conditions on wind turbine failures

Operation and maintenance is one of the main cost drivers of modern wind farms and has become an emerging field of research over the past years. Understanding the failure behaviour of wind turbines (WTs) can significantly enhance operation and maintenance processes and is essential for developing reliability and strategic maintenance models. Previous research has shown that especially the environmental conditions, to which the turbines are exposed to, affect their reliability drastically. This paper compares several advanced modelling techniques and proposes a novel approach to model WT system and component failures based on the site‐specific weather conditions. Furthermore, to avoid common problems in failure modelling, procedures for variable selection and complexity reduction are discussed and incorporated. This is applied to a big failure database comprised of 11 wind farms and 383 turbines. The results show that the model performs very well in several situations such as modelling general WT failures as well as failures of specific components. The latter is exemplified using gearbox failures.     

A nanostructured electrochromic supercapacitor

We report the first successful application of an ordered bicontinuous double-gyroid vanadium pentoxide network in an electrochromic supercapacitor. The freestanding vanadia network was fabricated by electrodeposition into a voided block copolymer template that had self-assembled into the double-gyroid morphology. The highly ordered structure with 11.0 nm wide struts and a high specific surface to bulk volume ratio of 161.4 μm(-1) is ideal for fast and efficient lithium ion intercalation/extraction and faradaic surface reactions, which are essential for high energy and high power density electrochemical energy storage devices. Supercapacitors made from such gyroid-structured vanadia electrodes exhibit a high specific capacitance of 155 F g(-1) and show a strong electrochromic color change from green/gray to yellow, indicating the capacitor's charge condition. The nanostructuring approach and utilizing an electrode material that has intrinsic electrochemical color-change properties are concepts that can be readily extended to other electrochromic intercalation compounds.     

Caffeine in your drink: natural or synthetic?

Owing to possible adulteration and health concerns, it is important to discriminate between natural and synthetic food ingredients. A new method for compound-specific isotope analysis (CSIA) by coupling high-temperature reversed-phase liquid chromatography to isotope ratio mass spectrometry (HT-RPLC/IRMS) was developed for discrimination of natural and synthetic caffeine contained in all types of drinks. The analytical parameters such as stationary phase, column inner diameter, and column temperature were optimized for the separation of caffeine directly from drinks (without extraction). On the basis of the carbon isotope analysis of 42 natural caffeine samples including coffee beans, tea leaves, guaraná powder, and maté leaves, and 20 synthetic caffeine samples from different sources by high-temperature reversed-phase liquid chromatography coupled to isotope ratio mass spectrometry, it is concluded that there are two distinguishable groups of caffeine δ(13)C-values: one between -25 and -32‰ for natural caffeine, and the other between -33 and -38‰ for synthetic caffeine. Isotope analysis by HT-RPLC/IRMS has been applied to identify the caffeine source in 38 drinks. Four mislabeled products were detected due to added but nonlabeled synthetic caffeine with δ(13)C-values lower than -33‰. This work is the first application of HT-RPLC/IRMS to real-world food samples, which showed several advantages: simple sample preparation (only dilution), high throughput, long-term column stability, and high precision of δ(13)C-value. Thus, HT-RPLC/IRMS can be a very promising tool in stable isotope analysis of nonvolatile compounds.