Wavelet analysis on transient behaviour of tidal amplitude fluctuations observed by meteor radar in the lower thermosphere above Bulgaria

International audienceOn the basis of bispectral analysis applied to the hourly data set of neutral wind measured by meteor radar in the MLT region above Bulgaria it was demonstrated that nonlinear processes are frequently and regularly acting in the mesopause region. They contribute significantly to the short-term tidal variability and are apparently responsible for the observed complicated behavior of the tidal characteristics. A Morlet wavelet transform is proposed as a technique for studying nonstationary signals. By simulated data it was revealed that the Morlet wavelet transform is especially convenient for analyzing signals with: (1) a wide range of dominant frequencies which are localized in different time intervals; (2) amplitude and frequency modulated spectral components, and (3) singular, wave-like events, observed in the neutral wind of the MLT region and connected mainly with large-scale disturbances propagated from below. By applying a Morlet wavelet transform to the hourly values of the amplitudes of diurnal and semidiurnal tides the basic oscillations with periods of planetary waves (1.5-20 days), as well as their development in time, are obtained. A cross-wavelet analysis is used to clarify the relation between the tidal and mean neutral wind variability. The results of bispectral analysis indicate which planetary waves participated in the nonlinear coupling with the atmospheric tides, while the results of cross-wavelet analysis outline their time intervals if these interactions are local

Nonmigrating tidal activity related to the sudden stratospheric warming in the Arctic winter of 2003/2004

This paper is focused on the nonmigrating tidal activity seen in the SABER/TIMED temperatures that is related to the major sudden stratospheric warming (SSW) taking place in the Arctic winter of 2003/2004. The emphasis is on the nonmigrating diurnal tides observed in the stratosphere and lower mesosphere which is usually accepted to be insignificant in comparison with that in the upper mesosphere and thermosphere. By using different independent spectral methods we found a significant amplification in December–January of the following nonmigrating 24-h tides: zonally symmetric (<I>s</I>=0), eastward propagating with zonal wavenumber 1 (E1), and westward propagating with zonal wavenumbers 2 and 3 (W2 and W3) tides. It has been found that the double peak nonmigrating tidal amplifications located in the stratosphere (~40 km) and in the lower mesosphere (~70 km) are a consequence of the maintained hydrostatic relation. By detailed comparison of the evolution and spatial structure of the nonmigrating diurnal tides with those of the migrating diurnal tide and stationary planetary waves (SPWs) evidence for a SPW-migrating tide interaction as a source of nonmigrating tides has been presented. Therefore, the nonmigrating 24-h tides turn out to be an important component of the middle atmosphere dynamics during the major SSW in the Arctic winter of 2003/2004

Optogenetics: Perspectives in biomedical research

© 2016, Nizhny Novgorod State Medical Academy. All rights reserved.Optogenetic tools, photochromic switches and genetically encoded biosensors revolutionized contemporary neuroscience research. These approaches provided unprecedented opportunities for monitoring and modulating the function of specific neurons and have literally shed light on the mechanisms of neuronal networks function in the brain. A number of light-sensitive biosensors for non-invasive monitoring of ions and enzymes have been developed. These molecular designs expand extremely rapidly and a number of new approaches for image analysis of various proteins in living cells have being proposed. In this review we discuss new tools for molecular imaging and remote activation of receptors, ionic channels and synaptic networks, as well as its potential for biomedical research

Upscaling urban recycled water schemes : An analysis of the presence of required governance conditions in the city of Sabadell (Spain)

Cleaning wastewater and using it again for secondary purposes is a measure to address water scarcity in urban areas. However, upscaling of recycled water schemes is challenging, and little is known about the governance conditions which are required for this. This paper addresses this knowledge gap. Based on a review of governance literature we suggest that five governance conditions are necessary for a successful upscaling of recycled water schemes: (1) policy leadership, (2) policy coordination, (3) availability of financial resources, (4) awareness of a problem, and (5) the presence of a public forum. We applied these concepts in a case study on the upscaling of a recycled water scheme in Sabadell, Spain. We reviewed policy documents, conducted a set of 21 semi-structured interviews, and attended two policy meetings about the subject. Our results suggest that Sabadell meets the required conditions for upscaling reused water to a certain extent. However, a public forum is not well-developed. We discuss the implications of this and conclude with some suggestions for future research and some lessons for other cities that plan to upscale their recycled water schemes

Calibration and functional analysis of three genetically encoded Cl-/pH sensors

Monitoring of the intracellular concentrations of Cl- and H+ requires sensitive probes that allow reliable quantitative measurements without perturbation of cell functioning. For these purposes the most promising are genetically encoded fluorescent biosensors, which have become powerful tools for non-invasive intracellular monitoring of ions, molecules and enzymatic activity. A ratiometric CFP/YFP-based construct with a relatively good sensitivity to Cl- has been developed (Markova et al., 2008; Waseem et al., 2010). Recently, a combined Cl-/pH sensor (ClopHensor) opened the way for simultaneous ratiometric measurement of these two ions (Arosio et al., 2010). ClopHensor was obtained by fusion of a red-fluorescent protein (DsRed-monomer) to the E2GFP variant that contains a specific Cl--binding site. This construct possesses pKa = 6.8 for H+ and Kd in the 40-50 mM range for Cl- at physiological pH (~7.3) As in the majority of cell types the intracellular Cl- concentration ([Cl-]i) is about 10 mM, the development of sensors with higher sensitivity is highly desirable. Here we report the intracellular calibration and functional characterization of ClopHensor and its two derivatives: the membrane targeting PalmPalm-ClopHensor and the H148G/V224L mutant with improved Cl- affinity, reduced pH dependence and pKa shifted to more alkaline values. For functional analysis, constructs were expressed in CHO cells and [Cl-]i was changed by using pipettes with different Cl- concentrations during whole-cell recordings. Kd values for Cl- measured at 33°C and pH ~ 7.3 were, respectively, 39 mM, 47 mM and 21 mM for ClopHensor, PalmPalm-ClopHensor and the H148G/V224L mutant. PalmPalm-ClopHensor resolved responses to activation of Cl--selective glycine receptor channels better than did ClopHensor. Our observations indicate that these different ClopHensor constructs are promising tools for non- invasive measurement of [Cl-]i in various living cells. © 2013 Mukhtarov, Liguori, Waseem, Rocca, Buldakova, Arosio and Bregestovski

Transgenic mouse lines for non-invasive ratiometric monitoring of intracellular chloride

Chloride is the most abundant physiological anion and participates in a variety of cellular processes including trans-epithelial transport, cell volume regulation, and regulation of electrical excitability. The development of tools to monitor intracellular chloride concentration ([Cli]) is therefore important for the evaluation of cellular function in normal and pathological conditions. Recently, several Cl-sensitive genetically encoded probes have been described which allow for non-invasive monitoring of [Cli]. Here we describe two mouse lines expressing a CFP-YFP-based Cl probe called Cl-Sensor. First, we generated transgenic mice expressing Cl-Sensor under the control of the mouse Thy1 mini promoter. Cl-Sensor exhibited good expression from postnatal day two (P2) in neurons of the hippocampus and cortex, and its level increased strongly during development. Using simultaneous whole-cell monitoring of ionic currents and Cl-dependent fluorescence, we determined that the apparent EC50 for Cli was 46 mM, indicating that this line is appropriate for measuring neuronal [Cli] in postnatal mice. We also describe a transgenic mouse reporter line for Cre-dependent conditional expression of Cl-Sensor, which was targeted to the Rosa26 locus and by incorporating a strong exogenous promoter induced robust expression upon Cre-mediated recombination. We demonstrate high levels of tissue-specific expression in two different Cre-driver lines targeting cells of the myeloid lineage and peripheral sensory neurons. Using these mice the apparent EC50 for Cli was estimated to be 61 and 54 mM in macrophages and DRG, respectively. Our data suggest that these mouse lines will be useful models for ratiometric monitoring of Cli in specific cell types in vivo. © 2013 Batti, Mukhtarov, Audero, Ivanov, Paolicelli, Zurborg, Gross, Bregestovski and Heppenstall