1,721,075 research outputs found
Addressing climate variability and extreme events in the ocean with spectral time series analysis and neural network models
No full textIn the context of the Copernicus Climate Change Service project (C3S) we outline a set of time series analysis methods, showing their application to oceanic essential climate variables, mainly Sea Surface Temperature (SST), both globally and in regions of particular interest, such as the North Atlantic, tropical Pacific and Indian Oceans as well as the Mediterranean basin. The goal is to decompose observations into their main components, to be considered as average conditions, anomaly patterns, slow varying trend components, evaluating main periodicities and studying variability patterns.
We introduce and show the comparison between linear and nonlinear methods for extraction of main features in SST data, where the nonlinear method is obtained with the application of a feed-forward neural network with the architecture of an autoencoder. The Singular Spectral Analysis method (SSA) is shown for extracting the main periodic oscillations in time series, showing both its ability of treating climate indices and usability for spatio-temporal gap-filling of data records, which is typically the case that occurs with when dealing with satellite data.
We also highlight the importance of studying extreme events as defined by SST, that is those events which represent the tails of observations’ probability distribution, known as the Marine Heat Waves (MHWs). We outline their hierarchical characterisation and the detection procedure, presenting results on the global scale but also giving insight of a specific study-case in the Mediterranean basin. Indeed, the Mediterranean Sea has been experiencing a nearly constant positive trend over the last decades, accounting for a total increase of 1.5°C in the satellite era (from 1981 to present), and we analyse how this influences the MHWs detection. Hence we propose a second detection approach, based on first detrending the series, wanting to evaluate the variability itself once decoupled from a changing baseline climate and give comparison of results.
Within the framework of neural networks, we investigate the equivalence of two paradigmatic models, the Hopfield model (HN) and the Boltzmann Machine (BM), firstly when dealing with random centred patterns and secondly also generalising duality to biased patterns. Since HN has a robust statistical mechanics background that enables a clear picture of retrieval capabilities, and BMs constitute the building block of deep neural architectures, this duality gives a route to follow in addressing explainable Artificial Intelligence (AI), which is nowadays an always more demanded feature for such methods, to allow further comprehension of results, as well as increased control and capability of improving these
Conjugate Additions of O-Nucleophiles to Activated Glycals:Stereoselective Synthesis of 2-Phosphonyl O-Glycoside Derivatives
No full textSynthesis of new 2-phospono-a-D-glycoside derivatives by stereoselective oxa-Michael addition to a D-galacto derived enone
No full textThe synthesis of new 2-phosphono-a-D-glycoside derivatives by stereoselective oxa-Michael addition to an enone derived from D-galactal and containing a phosphonate group is described. Retro-Michael reactions were prevented by tandem acetylation to trap the unstable enolic intermediates. The stereochemistry of the addition products was established by NOESY experiments and explained with molecular mechanics (MM) and density functional theory (DFT) calculations
Role of ionic liquids in protein refolding: native/fibrillar versus treated lysozyme
No full textSeveral ionic liquids (ILs) are known to revert aggregation processes and to improve the in vitro refolding of denatured/fibrillar proteins. Here, Raman spectroscopy is exploited to verify the refolding capability of several ammonium-based ILs and to identify the microscopic signatures of the structural rearrangements induced by the interaction of ILs with fibrillar lysozyme. We collected and carefully analyzed spectra from native, fibrillar and ILs-treated Several ionic liquids (ILs) are known to revert aggregation processes and to improve the in vitro refolding of denatured/fibrillar proteins. Here, Raman spectroscopy is exploited to verify the refolding capability of several ammonium-based ILs and to identify the microscopic signatures of the structural rearrangements induced by the interaction of ILs with fibrillar lysozyme. We collected and carefully analyzed spectra from native, fibrillar and ILs-treated fibrillar lysozyme to follow the microscopic process induced by ILs. These allowed us to identify different mechanisms of interaction depending on the length of the cation alkyl chain. A clear refolding effect was observed with EAN, as well as a tendency of the longer alkyl chain (PAN and BAN) of dissolving the fibril packing. A specific interaction mainly affecting the aromatic residues was identified for MEOAN (a long chain ILs with an ether group). The whole of the results, thus, provides new and detailed information on the ILs–protein interaction and shows Raman spectroscopy as a simple, reliable and effective diagnostic technique in this field.to follow the microscopic process induced by ILs. These allowed us to identify different mechanisms of interaction depending on the length of the cation alkyl chain. A clear refolding effect was observed with EAN, as well as a tendency of the longer alkyl chain (PAN and BAN) of dissolving the fibril packing. A specific interaction mainly affecting the aromatic residues was identified for MEOAN (a long chain ILs with an ether group). The whole of the results, thus, provides new and detailed information on the ILs–protein interaction and shows Raman spectroscopy as a simple, reliable and effective diagnostic technique in this field
2-Fosfono-3-osso-glicali: utili intermedi per la sintesi stereoselettiva di C- e O- glicosil derivati
No full textMichael Type Addition Reactions of O,S and N-nucleophiles on Hex-1-en-2-diethoxyphosphoryl-3-uloses Derived from Glycals
No full textA closer look at wound infections and healing
No full textWound healing is a physiological process that involves several successive and often overlapping phases that lead to the restoration of the integrity of the skin after an injury, accident or surgery: haemostasis and inflammation, proliferation and remodeling. The interruption or slowing down of these processes can cause abnormal or impaired wound healing. There are now numerous data and clinical studies that highlight the roles of estrogens on normal cutaneous homeostasis and wound healing. In postmenopausal women, for example, the reduced speed of wound healing processes has been clearly related to estrogen deficiency, especially in relation to inflammation and re-granulation, while treatment with exogenous estrogens can reverse these effects. We report here on the complex role of estrogens and estrogenic derivatives in wound healing process, with a focus on their therapeutic use, and on which
strategies have been explored to find substances with poor systemic effects
Carbon dots as bioactive antifungal nanomaterials
No full textNowadays, the widespread diffusion of infections caused by opportunistic fungi represents a demanding threat for global health security. This phenomenon has also worsened by the emergence of contagious events in hospitalisation environments and by the fact that many fungi have developed harsh and serious resistance mechanisms to the traditional antimycotic drugs. Hence, the design of novel antifungal agents is a key factor to counteract mycotic infections and resistance. Within this context, nanomaterials are gaining increasing attention thanks to their biocidal character. Among these, carbon dots (CDs) represent a class of zero-dimensional, photoluminescent and quasi-spherical nanoparticles which, for their great and tuneable features, have found applications in catalysis, sensing and biomedicine. Nevertheless, only a few works define and recapitulate their antifungal properties. Therefore, we aim to give an overview about the recent advances in the synthesis of CDs active against infective fungi. We described the general features of CDs and fungal cells, by highlighting some of the most common antimycotic mechanisms. Then, we evaluated the effects of CDs, antimicrobial drugs-loaded CDs and CDs-incorporated packaging systems on different fungi and analysed the use of CDs as fluorescent nano-trackers for bioimaging, showing, to all effects, their promising application as antifungal agents
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