Nonlinear operators on graphs via stacks

International audienceWe consider a framework for nonlinear operators on functions evaluated on graphs via stacks of level sets. We investigate a family of transformations on functions evaluated on graph which includes adaptive flat and non-flat erosions and dilations in the sense of mathematical morphology. Additionally, the connection to mean motion curvature on graphs is noted. Proposed operators are illustrated in the cases of functions on graphs, textured meshes and graphs of images

SATURN: A Technological Demonstration Mission for Distributed SAR Imaging

The OHB-Italia S.p.A-led consortium is in the midst of Phase B of SATURN (Synthetic AperTure radar cUbesat foRmation flyiNg), part of ALCOR, an Italian Space Agency (ASI) programme promoting the development of the next generation Italian CubeSats. SATURN is a demonstration mission that features Multiple-Input-Multiple-Output (MIMO) technology applied to a Swarm of CubeSats equipped with Synthetic Aperture Radar (SAR) for Earth Observation. MIMO is based on cooperative active sensors, where each one transmits signals and receives the illuminated common area backscatter related to the entire swarm, increasing measurement performances with a trend approximatively equal to the square of the number of sensors. The complete SATURN constellation features 16 mini-swarms, each of 3 CubeSats, spread over 4 SSOs equally spaced by 3 hours of local time. The constellation is designed to provide an average revisit time of 1.5 h and an interferometric revisit time of 1 day worldwide. The aim of this demonstration mission is to verify MIMO technology applied to SAR on a mini-swarm of 3 CubeSats in close formation on a Low Earth Down-Dusk Sun Synchronous Orbit. Using OHB-I’s M3Multi Mission Modular platform equipped with a miniaturized SAR Instrument, developed by ARESYS S.r.l. and Airbus Italia S.p.A., our mission is able to achieve a resolution of 5x5 m over a 30 km swath. Thus, SATURN enables low-cost, scalable SAR missions for affordable access to space for public and private entities, overcoming the single point of failure of one large and complex satellite. Subsequent swarms, deploying from 3 to 48 CubeSats, are expected to bring technological innovations and improve Italy’s competitiveness in the European and global Earth Observation scenario

Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards: Part II. Validation of satellite-derived Volcanic Sulphur Dioxide Levels.

info:eu-repo/semantics/nonPublishe

Intercomparison of Metop-A SO<inf>2</inf> measurements during the 2010- 2011 Icelandic eruptions

The European Space Agency project Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards, was introduced after the eruption of the Icelandic volcano Eyjafjallajökull in the spring of 2010 to facilitate the development of an optimal End­to­End System for Volcanic Ash Plume Monitoring and Prediction. The Eyjafjallajökull plume drifted towards Europe and caused major disruptions of European air traffic for several weeks affecting the everyday life of millions of people. The limitations in volcanic plume monitoring and prediction capabilities gave birth to this observational system which is based on comprehensive satellite­derived ash plume and sulphur dioxide [SO2] level estimates, as well as a widespread validation using supplementary satellite, aircraft and ground­based measurements. Inter­comparison of the volcanic total SO2 column and plume height observed by GOME­2/Metop­A and IASI/Metop­A are shown before, during and after the Eyjafjallajökull 2010 eruptions as well as for the 2011 Grímsvötn eruption. Co­located ground­based Brewer Spectro­photometer data extracted from the World Ozone and Ultraviolet Radiation Data Centre for de Bilt, the Netherlands, are also compared to the different satellite estimates. Promising agreement is found for the two different types of instrument for the SO2 columns with linear regression coefficients ranging around from 0.64 when comparing the different instruments and 0.85 when comparing the two different IASI algorithms. The agreement for the plume height is lower, possibly due to the major differences between the height retrieval part of the GOME2 and IASI algorithms. The comparisons with the Brewer ground­based station in de Bilt, The Netherlands show good qualitative agreement for the peak of the event however stronger eruptive signals are required for a longer quantitative comparison.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Intercomparison of Metop-A SO2 measure- ments during the 2010- 2011 Icelandic eruptions

The European Space Agency project Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Avi­ ation Hazards, was introduced after the eruption of the Icelandic volcano Eyjafjallajökull in the spring of 2010 to facilitate the development of an optimal End­to­End System for Volcanic Ash Plume Monitoring and Predic­ tion. The Eyjafjallajökull plume drifted towards Europe and caused major disruptions of European air traffic for several weeks affecting the everyday life of millions of people. The limitations in volcanic plume monitoring and prediction capabilities gave birth to this observational system which is based on comprehensive satellite­derived ash plume and sulphur dioxide [SO2] level estimates, as well as a widespread validation using supplementary satellite, aircraft and ground­based measurements. Inter­comparison of the volcanic total SO2 column and plume height observed by GOME­2/Metop­A and IASI/Metop­A are shown before, during and after the Eyjaf­ jallajökull 2010 eruptions as well as for the 2011 Grímsvötn eruption. Co­located ground­based Brewer Spectro­ photometer data extracted from the World Ozone and Ultraviolet Radiation Data Centre for de Bilt, the Nether­ lands, are also compared to the different satellite estimates. Promising agreement is found for the two different types of instrument for the SO2 columns with linear regression coefficients ranging around from 0.64 when comparing the different instruments and 0.85 when comparing the two different IASI algorithms. The agree­ ment for the plume height is lower, possibly due to the major differences between the height retrieval part of the GOME2 and IASI algorithms. The comparisons with the Brewer ground­based station in de Bilt, The Nether­ lands show good qualitative agreement for the peak of the event however stronger eruptive signals are required for a longer quantitative comparison.

MONITORING SNOW COVER IN ALPINE REGIONS THROUGH THE INTEGRATION OF MERIS AND AATSR ENVISAT SATELLITE OBSERVATIONS

ABSTRACT The ENVISAT mission with a suite of high performance sensors offers some opportunities for mapping snow cover at regional and catchment scale. The geometric resolution of MERIS data and the spectral resolution of AATSR data are suitable for these purposes. A new approach, developed in the framework of the GLASNOWMAP project (ESA-DUP2) for monitoring snow cover in Alpine regions, based on the combined use of MERIS and AATSR observations, and topographic information, is proposed. As MERIS spectral bands are not completely proper for the discrimination of snow from clouds -due to the lack of short wave infrared channels -a multisource classification scheme has been developed to combine the results obtained by the classification of MERIS data with the information on cloud distribution as derived from AATSR data; the integration is performed with the aid of snow elevation distribution as derived from the Digital Elevation Model. A supervised fuzzy statistical classifier (Wang 1990) has been chosen to perform classification of MERIS images, being particularly suited for the representation of land cover class mixture. The classifier bases estimates of the distribution of pixels in multispectral space on the concept of the probability measure of fuzzy events to produce an output of the proportions of individual components. A cloud normalized index has been defined to extract clouds from AATSR images previously registered and resampled on MERIS images. The results of MERIS and AATSR processing are integrated to produce a snow cover map masked over the cloud covered areas, taking into account also the elevation. The Alpine region is selected as test area to demonstrate the potential and limitations of the novel approach. In particular, the attention is focused on three regions of Northern Italy (Valle d&apos;Aosta, Piemonte, Lombardia). The first results obtained by the application of this new method to Earth Observation data will be presented and analysed. INTRODUCTION The quantitative estimation of the extent and depth of snow cover, the stored amount of water, the state of snow metamorphism and intensity of snowmelt runoff are of prime importance to hydrologists and managers of water resources. In the recent years the increased demand for water resources has led to a conflict between human needs and the needs to sustain freshwater ecosystems. On seasonal to annual timescales, the accumulation and melting of snow dominates the hydrological cycle of many alpine and high latitude drainage basins. Over 50% of Eurasia and North America can be seasonally covered by snow GLASNOWMAP-IS OVERVIEW The GLASNOWMAP project proposes to define and implement an information service for monitoring of glacier and snow cover changes

Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards: Part I. Validation of satellite-derived Volcanic Ash Levels.

info:eu-repo/semantics/nonPublishe

Volcanic SO2 measurements by UV-TIR satellite retrievals: validation by using the ground-based FLAME network at Mt. Etna

info:eu-repo/semantics/nonPublishe

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field