1,779 research outputs found
Limited Area Numerical Weather Prediction
No full textTwo limited area model derivatives of the numerical weather prediction model COSMO-DE operated by the German Meteorological Service are introduced. The aim is to obtain frequently updated highly re-solved predictions in a limited area as an aerodrome. The predictions include dynamic parameters as wind and turbulence kinetic energy and thermodynamic quantities as temperature and humidity but also the amount of snow, rain and hail. The models are used in the airport environments of Frankfurt (COSMO-FRA) and Munich (COSMO-MUC) for aircraft wake vortex, thunderstorm activity, and wintry weather warning applications, as detailed in Sections 2.1 to 2.4
N-methyl-D-aspartate receptor stimulation activates tyrosinase and promotes melanin synthesis in the ink gland of the cuttlefish Sepia officinalis through the nitric oxide/cGMP signal transduction pathway
No full textThe tyrosinase-catalyzed conversion of L-tyrosine to melanin represents the most distinctive biochemical pathway in the ink gland of the cuttlefish Sepia officinalis; however, the molecular mechanisms underlying its activation have remained so far largely uncharted. In this paper we demonstrate for the first time that L-glutamate can stimulate tyrosinase activity and promote melanin synthesis in Sepia ink gland via the N-methyl-D-aspartate (NMDA) receptor/NO/cGMP signal transduction pathway. Incubation of intact ink glands with either L-glutamate or NMDA resulted in an up to 18-fold increase of tyrosinase activity and a more than 6-fold elevation of cGMP levels. Comparable stimulation of tyrosinase was induced by an NO donor and by 8-bromo-cGMP. An NMDA receptor antagonist, NO synthase (NOS) inhibitors, and a guanylate cyclase blocker suppressed NMDA-induced effects. Immunohistochemical evidence indicated that enhanced cGMP production was localized largely in the mature part of the ink gland. Increased de novo synthesis of melanin was demonstrated in NMDA- and NO-stimulated ink glands by a combined microanalytical approach based on spectro-photometric determination of pigment levels and high performance liquid chromatography quantitation of pyrrole-2,3,5-tricarboxylic acid, a specific melanin marker, in melanosome containing fractions. These results fill a longstanding gap in the understanding of the complex biochemical mechanisms underlying activation of melanogenesis in the mature ink gland cells of S. officinalis and disclose a novel physiologic role of the excitatory neurotransmitter glutamate mediated by the NMDA receptor/NO/cGMP signaling pathway
Consistent Partial Matching of Shape Collections via Sparse Modeling
No full textRecent efforts in the area of joint object matching approach the problem by taking as input a set of pairwise maps, which are then jointly optimized across the whole collection so that certain accuracy and consistency criteria are satisfied. One natural requirement is cycle-consistencynamely the fact that map composition should give the same result regardless of the path taken in the shape collection. In this paper, we introduce a novel approach to obtain consistent matches without requiring initial pairwise solutions to be given as input. We do so by optimizing a joint measure of metric distortion directly over the space of cycle-consistent maps; in order to allow for partially similar and extra-class shapes, we formulate the problem as a series of quadratic programs with sparsity-inducing constraints, making our technique a natural candidate for analysing collections with a large presence of outliers. The particular form of the problem allows us to leverage results and tools from the field of evolutionary game theory. This enables a highly efficient optimization procedure which assures accurate and provably consistent solutions in a matter of minutes in collections with hundreds of shapes
Cosmo/Skymed AO Projects – Advanced 2D and 3D Focusing of Cosmo/Skymed SAR Data
No full textWe present a research project, funded by the Italian Space Agency (ASI), aimed at performing 2D and 3D Focusing of COSMO/SkyMed (CSK) SAR Data. We describe the main objectives of the project, briefly illustrate employed techniques, and finally present the obtained results. The latter show that sub-meter resolution can be achieved in the enhanced spotlight CSK acquisition mode, and that by using 3D focusing it is possible to resolve scatterers at different slant heights within the same range-azimuth resolution cell, even in areas characterized by severe height discontinuities and large thermal dilations effects
A calcium-dependent nitric oxide synthase and NMDAR1 glutamate receptor in the ink gland of Sepia officinalis. A hint to a regulatory role of nitric oxide in melanogenesis?
No full textA calcium-dependent nitric oxide synthase and NMDAR1 glutamate receptor in the ink gland of Sepia officinalis. A hint to a regulatory role of nitric oxide in melanogenesis?
No full textItalian COSMO-SkyMed atlas: R-Index and the percentage of measurability of movement
No full textSAR (Synthetic Aperture Radar) satellite interferometry is a helpful remote sensing technique for large areas analyses and monitoring, especially where the study area is difficult to access for practical or for legal reasons. As a result, the use of these techniques has significantly increased over the past three decades. Among the available different satellite constellations displaying different spatial and temporal resolutions, COSMO-SkyMed of the Italian Space Agency (ASI) represents a cutting-edge reality. COSMO-SkyMed constellation, launched in 2007 by ASI, is a valuable Earth observation tool that provides all-weather, day-and-night imaging capabilities with high resolution and a short revisit time. In this study, we produced an atlas for the entire Italian peninsula using two parameters (R-Index and Percentage of measurability of movement), in order to evaluate the quality and a-priori applicability of satellite interferometry data collected by the COSMO-SkyMed constellation. The atlas was obtained by means of the implementation of different model builders in the GIS (Geographical Information Systems) environment, providing a semi-automatic way to generate the above-mentioned outputs. The R-Index describes the likelihood of detecting Permanent Scatterers in mountainous areas, while the Percentage of measurability of movement indicates the percentage of real motion that interferometry can detect at a certain point in the analyzed region. A high-detail Digital Terrain Model (DTM) has been used to identify the most suitable areas for satellite interferometry monitoring and studying. The results of our analysis showed that the R-Index and the Percentage of measurability of movement could be used to pre-evaluate the quality of satellite interferometry data collected by the COSMO-SkyMed constellation. This research has important implications for disaster response, environmental monitoring, and scientific research and is one of a few cases in the world in which a unified representation for an entire country is provided
Evaluating Ice Microphysics in NWP Models with Satellite Observations
No full textIce clouds are an important part of the Earth’s atmospheric water cycle and have a large impact on the global radiation budget. Yet ice clouds are still poorly understood and their correct representation remains a major challenge for state-of-the-art atmospheric models. Also, the evaluation of the models’ performance with respect to ice clouds is not straightforward; remote sensing instruments, for example, measure other quantities than the models predict. Therefore, two basic evaluation approaches exist: observation-to-model (commonly termed retrieval) and model-to-observation (commonly termed forward operator). Both approaches introduce errors into the comparison of models and observations because of the necessary intrinsic assumptions. The common practice in model evaluation of choosing either the one or the other of these approaches might give an incomplete picture.
The present study evaluates the ice microphysics of two numerical weather prediction (NWP) models currently operational at the German weather service (Deutscher Wetterdienst, DWD): the global model GME and the regional model COSMO-DE (an application of the Consortium for Small-scale Modelling, COSMO). In doing so, this study contributes significantly to ongoing model development at DWD. Both case studies and long-term evaluations are carried out. Cloud Satellite (CloudSat) Cloud Profiling Radar (CPR) observations are heavily relied on; the CPR is the first and — up to date — only cloud radar in space and is able to vertically resolve even optically thick clouds. This study focuses on one specific question raised for each of the respective models and while doing so applies both approaches; the standard CloudSat radar reflectivity factor–ice water content (IWC) retrieval for the observation-to-model approach and the forward operator QuickBeam for the model-to-observation approach. This enables for one, to profit from the full informational content, and for the other, to compare both approaches directly to each other and evaluate them.
For the global model GME, two precipitation schemes, a diagnostic and a prognostic one, are compared and evaluated. The focus is on the question whether the new prognostic scheme is capable of capturing ice clouds more realistically than the old diagnostic scheme. The prognostic scheme is shown to exhibit improved performance in comparison to the diagnostic scheme in terms of IWC magnitude. In both models snow is found to dominate over cloud ice in total IWC, emphasizing the need for including snow in the model’s radiation budget in the future. Furthermore, one reason for the remaining difference between the prognostic scheme and the observations — the unrealistic fall speed of snow — is identified. As a consequence, the new prognostic scheme with an adapted parameterization for snow fall speed was successfully introduced into operational service at DWD.
In the regional NWP model COSMO-DE, a long-known bias between brightness temperatures simulated from COSMO-DE forecasts and those observed by Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) is investigated. The pivotal question is whether a novel two-moment cloud ice scheme exhibits improved
performance with respect to this bias and, if that is so, why. It is shown that the novel two-moment cloud ice scheme does indeed reduce this bias and can therefore be considered an improvement in comparison to two standard schemes, the two-category ice scheme and the currently operational three-category ice scheme. The improvement in simulated brightness temperatures is due to a vertical redistribution of cloud ice to lower model levels. Furthermore, sensitivity studies identify two of the four changes introduced, which are responsible for most of the improved performance: the change to a different heterogeneous nucleation scheme and the inclusion of cloud ice sedimentation. Enhanced vertical level number and modifications in aerosol number concentrations reveal comparatively little effect. As a consequence, cloud ice sedimention will be included per se in DWD’s future NWP model, the Icosahedral non-hydrostatic (ICON) model, currently still under development.
Concerning the two evaluation approaches conducted, the present study finds the general features in the two evaluations to be captured by both approaches. Some details are captured merely by the one or the other approach, in which case both approaches together give the more complete picture. However, the model-to-observation approach appears to be easier to interpret; its uncertainties are easier to assess than those of the observation-to-model approach and it ensures a better control over the comparison
Bayesian mesh adaptation for estimating distributed parameters
No full textThe problem of estimating numerically a distributed parameter from indirect measurements arises in many applications, and in that context the choice of the discretization plays an important role. In fact, guaranteeing a certain level of accuracy of the forward model that maps the unknown to the observations may require a fine discretization, adding to the complexity of the problem and to the computational cost. On the other hand, reducing the complexity of the problem by adopting a coarser discretization may increase the modeling error and can be very detrimental for ill-posed inverse problems. To balance accuracy and complexity, we propose an adaptive algorithm for adjusting the discretization level automatically and dynamically while estimating the unknown distributed parameter by an iterative scheme. In the Bayesian paradigm, all unknowns, including the metric that defines the discretization, are modeled as random variables. Our approach couples the discretization with a Bayesian hierarchical hyperparameter that is estimated simultaneously with the unknown parameter of primary interest. The viability of the proposed algorithm, the Bayesian mesh adaptation (BMA) is assessed on two test cases: a fan-beam X-ray tomography problem and an inverse source problem for a Darcy flow model
N-methyl –D-aspartate receptor stimulation activates tyrosinase and promotes melanin synthesis in the ink gland of the cuttlefish Sepia officinalis through the nitric oxide/cGMP signal trasduction pathway.
No full textThe tyrosinase-catalyzed conversion of l-tyrosine to melanin represents the most distinctive biochemical pathway in the ink gland of the cuttlefish Sepia officinalis; however, the molecular mechanisms underlying its activation have remained so far largely uncharted. In this paper we demonstrate for the first time that l-glutamate can stimulate tyrosinase activity and promote melanin synthesis in Sepia ink gland via the N-methyl-d-aspartate (NMDA) receptor/NO/cGMP signal transduction pathway. Incubation of intact ink glands with either l-glutamate or NMDA resulted in an up to 18-fold increase of tyrosinase activity and a more than 6-fold elevation of cGMP levels. Comparable stimulation of tyrosinase was induced by an NO donor and by 8-bromo-cGMP. An NMDA receptor antagonist, NO synthase (NOS) inhibitors, and a guanylate cyclase blocker suppressed NMDA-induced effects. Immunohistochemical evidence indicated that enhanced cGMP production was localized largely in the mature part of the ink gland. Increased de novo synthesis of melanin was demonstrated in NMDA- and NO-stimulated ink glands by a combined microanalytical approach based on spectrophotometric determination of pigment levels and high performance liquid chromatography quantitation of pyrrole-2,3, 5-tricarboxylic acid, a specific melanin marker, in melanosome-containing fractions. These results fill a longstanding gap in the understanding of the complex biochemical mechanisms underlying activation of melanogenesis in the mature ink gland cells of S. officinalis and disclose a novel physiologic role of the excitatory neurotransmitter glutamate mediated by the NMDA receptor/NO/cGMP signaling pathway
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