Fine Tuning of Ca(V)1.3 Ca2+ Channel Properties in Adult Inner Hair Cells Positioned in the Most Sensitive Region of the Gerbil Cochlea

Hearing relies on faithful signal transmission by cochlear inner hair cells (IHCs) onto auditory fibres over a wide frequency and intensity range. Exocytosis at IHC ribbon synapses is triggered by Ca2+ inflow through CaV1.3 (L-type) Ca2+ channels. We investigated the macroscopic (whole-cell) and elementary (cell-attached) properties of Ca2+ currents in IHCs positioned at the middle turn (frequency ,2 kHz) of the adult gerbil cochlea, which is their most sensitive hearing region. Using near physiological recordings conditions (body temperature and a Na+ based extracellular solution), we found that the macroscopic Ca2+ current activates and deactivates very rapidly (time constant below 1 ms) and inactivates slowly and only partially. Single-channel recordings showed an elementary conductance of 15 pS, a sub-ms latency to first opening, and a very low steady-state open probability (Po: 0.024 in response to 500-ms depolarizing steps at ,218 mV). The value of Po was significantly larger (0.06) in the first 40 ms of membrane depolarization, which corresponds to the time when most Ca2+ channel openings occurred clustered in bursts (mean burst duration: 19 ms). Both the Po and the mean burst duration were smaller than those previously reported in high-frequency basal IHCs. Finally, we found that middle turn IHCs are likely to express about 4 times more Ca2+ channels per ribbon than basal cells. We propose that middle-turn IHCs finely-tune CaV1.3 Ca2+ channel gating in order to provide reliable information upon timing and intensity of lower-frequency sounds

The chemical history of molecules in circumstellar disks. II. Gas-phase species

Context: The chemical composition of a molecular cloud changes dramatically as it collapses to form a low-mass protostar and circumstellar disk. Two-dimensional (2D) chemodynamical models are required to properly study this process. Aims: The goal of this work is to follow, for the first time, the chemical evolution in two dimensions all the way from a pre-stellar core into a circumstellar disk. Of special interest is the question whether the chemical composition of the disk is a result of chemical processing during the collapse phase, or whether it is determined by in situ processing after the disk has formed. Methods: Our model combines a semi-analytical method to get 2D axisymmetric density and velocity structures with detailed radiative transfer calculations to get temperature profiles and UV fluxes. Material is followed in from the core to the disk and a full gas-phase chemistry network -- including freeze-out onto and evaporation from cold dust grains -- is evolved along these trajectories. The abundances thus obtained are compared to the results from a static disk model and to observations of comets. Results: The chemistry during the collapse phase is dominated by a few key processes, such as the evaporation of CO or the photodissociation of H2O. At the end of the collapse phase, the disk can be divided into zones with different chemical histories. The disk is not in chemical equilibrium at the end of the collapse, so care must be taken when choosing the initial abundances for stand-alone disk chemistry models. Our model results imply that comets must be formed from material with different chemical histories: some of it is strongly processed, some of it remains pristine. Variations between individual comets are possible if they formed at different positions or different times in the solar nebula.Comment: 18 pages, 12 figures, accepted by A&

Correction: Sammer, M., et al. Strong Gradients in Weak Magnetic Fields Induce DOLLOP Formation in Tap Water. Water 2016, 8, 79

The authors wish to make the following corrections to this paper [1]: In all instances mentioning “2 kG·m−1”, these gradients should be replaced by “770 G·m−1 (WCM 62081992) and 740 G·m−1 (WCM 62083545)”: Abstract, page 1, line 4; Chapter 1 [...]</jats:p

Correction: Sammer, M., et al. Strong Gradients in Weak Magnetic Fields Induce DOLLOP Formation in Tap Water. Water 2016, 8, 79

The authors wish to make the following corrections to this paper [1]: In all instances mentioning &ldquo;2 kG&middot;m&minus;1&rdquo;, these gradients should be replaced by &ldquo;770 G&middot;m&minus;1 (WCM 62081992) and 740 G&middot;m&minus;1 (WCM 62083545)&rdquo;: Abstract, page 1, line 4; Chapter 1 [...

Strong Gradients in Weak Magnetic Fields Induce DOLLOP Formation in Tap Water

In 2012 Coey proposed a theory on the mechanism of magnetic water treatment based on the gradient of the applied field rather than its absolute strength. We tested this theory by measuring the effect of very weak field magnets (≤ 10 G) containing strong magnetic inhomogeneities (ΔB = 2 kG·m−1) on tap water samples by the use of electric impedance spectroscopy (EIS) and laser scattering. Our results show an increased formation of nm-sized prenucleation clusters (dynamically ordered liquid like oxyanion polymers or “DOLLOPs”) due to the exposure to the magnetic field and thus are consistent with Coey’s theory which is therefore also applicable to very weak magnetic fields as long as they contain strong gradients

Answer Set Programming via Controlled Natural Language Processing

Controlled natural languages are subsets of natural languages that can be used to describe a problem in a very precise way, furthermore they can often be translated automatically into a formal notation. We investigate in this paper how a controlled natural language can be used as a specification language for Answer Set Programming (ASP). ASP is a declarative approach to problem solving and has its roots in knowledge representation, logic programming, and constraint satisfaction. Solutions of ASP programs are stable models (= answer sets) that build the starting point for question answering. As a proof of concept, we translate a problem specification written in controlled natural language into an ASP program and compute a stable model that contains the answers to a number of questions.18 page(s

Dissimilatory nitrate reduction by Aspergillus terreus isolated from the seasonal oxygen minimum zone in the Arabian Sea

Background: A wealth of microbial eukaryotes is adapted to life in oxygen-deficient marine environments. Evidence is accumulating that some of these eukaryotes survive anoxia by employing dissimilatory nitrate reduction, a strategy that otherwise is widespread in prokaryotes. Here, we report on the anaerobic nitrate metabolism of the fungus Aspergillus terreus (isolate An-4) that was obtained from sediment in the seasonal oxygen minimum zone in the Arabian Sea, a globally important site of oceanic nitrogen loss and nitrous oxide emission. Results: Axenic incubations of An-4 in the presence and absence of oxygen and nitrate revealed that this fungal isolate is capable of dissimilatory nitrate reduction to ammonium under anoxic conditions. A 15N-labeling experiment proved that An-4 produced and excreted ammonium through nitrate reduction at a rate of up to 175 nmol (NH4+)-N-15 g(-1) protein h(-1). The products of dissimilatory nitrate reduction were ammonium (83%), nitrous oxide (15.5%), and nitrite (1.5%), while dinitrogen production was not observed. The process led to substantial cellular ATP production and biomass growth and also occurred when ammonium was added to suppress nitrate assimilation, stressing the dissimilatory nature of nitrate reduction. Interestingly, An-4 used intracellular nitrate stores (up to 6-8 mu mol NO3-g(-1) protein) for dissimilatory nitrate reduction. Conclusions: Our findings expand the short list of microbial eukaryotes that store nitrate intracellularly and carry out dissimilatory nitrate reduction when oxygen is absent. In the currently spreading oxygen-deficient zones in the ocean, an as yet unexplored diversity of fungi may recycle nitrate to ammonium and nitrite, the substrates of the major nitrogen loss process anaerobic ammonium oxidation, and the potent greenhouse gas nitrous oxide