Improving the reference network in wide-area Persistent Scatterer Interferometry for non-urban areas

Advanced Interferometric SAR (InSAR) technique, namely, Persistent Scatterer Interferometry (PSI), allows long term deformation time series analysis with millimeter accuracy. Reference network arcs construction, arcs estimation and integration for PSs are an important step in PSI. In rural regions, low density of PSs leads to separate clusters during reference network construction. Also, in case of wide-area PSI using ERS-1/2 or Sentinel-1 data, the computational load can be very high. Due to this, the reference network processing is usually divided into overlapping blocks and merged later. This can however lead to spatial error propagation. This paper presents algorithms for improving the reference network in wide-area PSI, with a focus on non-urban areas

Bi-color atomic beam slower and magnetic field compensation for ultracold gases

Transversely loaded bidimensional-magneto-optical-traps (2D-MOT) have been recently developed as high flux sources for cold strontium atoms to realize a new generation of compact experimental setups. Here, we discuss on the implementation of a cross-polarized bi-color slower for a strontium atomic beam improving the 2D-MOT loading, and increasing the number of atoms in a final MOT by eleven times. Our slowing scheme addresses simultaneously two excited Zeeman substates of the 88Sr 1S0->1P1 transition at 461 nm. We also realized a 3-axis active feedback control of the magnetic field down to the microgauss regime. Such a compensation is performed thanks to a network of eight magnetic field probes arranged in a cuboid configuration around the atomic cold sample, and a pair of coils in Helmholtz configuration along each of three Cartesian directions. Our active feedback is capable of efficiently suppressing most of the magnetically-induced position fluctuations of the 689~nm intercombination-line MOT.Comment: 8 pages, 6 figure

Large Scale Interferometric Processing of Sentinel-1 Data over the Atacama Desert - a Contribution to the TecVolSA Project

The project TecVolSA (Tectonics and Volcanoes in South America) aims at developing an intelligent Earth Observation (EO) data processing system for monitoring the earthquake cycle and volcanic events in South America. The Remote Sensing Technology Institute of DLR participates to this project together with GFZ (German Research Centre for Geosciences). The project is partially financed by Helmholtz. So far we have processed about 40 Sentinel-1 slices covering the Atacama Desert with mixed Permanent Scatterer and Distributed Scatterer (PS/DS) techniques. The area is very dry and the spatio-temporal coverage is excellent. Tropospheric correction have been applied using ECMWF ERA5 data, hence improving the performance in observing both topography related and large scale deformation signals. The current results reveal, as expected, plenty of interesting signals to be interpreted (see attached figure for an overview of the velocity field). Preliminary GPS cross-validation, thanks to data freely available from the Geodetic Nevada Laboratory, confirm that the InSAR relative error in the estimated velocities is in the order of 1 mm/yr at large scale (>100 km) and confirms the large scale signal related to the subduction of the Nazca plate (see attached figure). More GNSS validation will be possible with additional GPS stations. The challenge of the project is the separation of different contributions to the InSAR measurements: apart from the tectonic effects, there are contributions coming from volcanic unrest, atmospheric delays, moisture effects, snow, flank instability (likely downhill creep or solifluction related to permafrost, see attached figure), salt lake growth, mining, and likely more. We are dealing with this complexity with a diversity of tools: physical modeling and statistical analysis, deep neural networks, and expert knowledge. GFZ contributes process knowledge, historic seismic data, in-situ motion measurements and observations and 4D geophysical modelling codes for producing a diverse database for the training of neural networks in order to autonomously discover significant events in noisy data. We tackle the problem as a semi-supervised multi-class classification approach where the labeling of the known deformation phenomena is provided by GFZ. Signals for which the source of deformation is unknown are identified and clustered automatically using advanced unsupervised machine-learning techniques. Therefore, we leverage from the advantages of both supervised and unsupervised learning and improve the accuracy for detection and classification of different deformation sources. The networks and AI-based methods are developed at DLR. This new approach (InSAR + Artificial Intelligence) should be able to process the massive data stream of the Copernicus Sentinel-1 SAR mission. South America was selected because manifold geophysical signals can be expected there in short time scales and plenty of in-situ data are available. This project will complement the current model-based geophysical research by a data-driven AI-based approach. Training and applying this intelligent system shall improve our understanding of geophysical processes related to natural and anthropogenic hazards. At a later stage the system shall be scalable to global processing capacity. Future developments on the InSAR processing will include ionospheric corrections based on split-spectrum and mosaicking of the velocity and displacement series. Some issues with the L1 processor are hindering the deployment of the split-spectrum technique. Stacks from the ascending geometry are already being processed and will help the geophysical interpretation

Optimized cytogenetic risk-group stratification of KMT2A-rearranged pediatric acute myeloid leukemia

A comprehensive international consensus on the cytogenetic risk-group stratification of KMT2A-rearranged (KMT2A-r) pediatric acute myeloid leukemia (AML) is lacking. This retrospective (2005-2016) International Berlin-Frankfurt-Münster Study Group study on 1256 children with KMT2A-r AML aims to validate the prognostic value of established recurring KMT2A fusions and additional cytogenetic aberrations (ACAs) and to define additional, recurring KMT2A fusions and ACAs, evaluating their prognostic relevance. Compared with our previous study, 3 additional, recurring KMT2A-r groups were defined: Xq24/KMT2A::SEPT6, 1p32/KMT2A::EPS15, and 17q12/t(11;17)(q23;q12). Across 13 KMT2A-r groups, 5-year event-free survival probabilities varied significantly (21.8%-76.2%; P &lt; .01). ACAs occurred in 46.8% of 1200 patients with complete karyotypes, correlating with inferior overall survival (56.8% vs 67.9%; P &lt; .01). Multivariable analyses confirmed independent associations of 4q21/KMT2A::AFF1, 6q27/KMT2A::AFDN, 10p12/KMT2A::MLLT10, 10p11.2/KMT2A::ABI1, and 19p13.3/KMT2A::MLLT1 with adverse outcomes, but not those of 1q21/KMT2A::MLLT11 and trisomy 19 with favorable and adverse outcomes, respectively. Newly identified ACAs with independent adverse prognoses were monosomy 10, trisomies 1, 6, 16, and X, add(12p), and del(9q). Among patients with 9p22/KMT2A::MLLT3, the independent association of French-American-British-type M5 with favorable outcomes was confirmed, and those of trisomy 6 and measurable residual disease at end of induction with adverse outcomes were identified. We provide evidence to incorporate 5 adverse-risk KMT2A fusions into the cytogenetic risk-group stratification of KMT2A-r pediatric AML, to revise the favorable-risk classification of 1q21/KMT2A::MLLT11 to intermediate risk, and to refine the risk-stratification of 9p22/KMT2A::MLLT3 AML. Future studies should validate the associations between the newly identified ACAs and outcomes and unravel the underlying biological pathogenesis of KMT2A fusions and ACAs.</p

Optimized cytogenetic risk-group stratification of KMT2A-rearranged pediatric acute myeloid leukemia

A comprehensive international consensus on the cytogenetic risk-group stratification of KMT2A-rearranged (KMT2A-r) pediatric acute myeloid leukemia (AML) is lacking. This retrospective (2005-2016) International Berlin-Frankfurt-Münster Study Group study on 1256 children with KMT2A-r AML aims to validate the prognostic value of established recurring KMT2A fusions and additional cytogenetic aberrations (ACAs) and to define additional, recurring KMT2A fusions and ACAs, evaluating their prognostic relevance. Compared with our previous study, 3 additional, recurring KMT2A-r groups were defined: Xq24/KMT2A::SEPT6, 1p32/KMT2A::EPS15, and 17q12/t(11;17)(q23;q12). Across 13 KMT2A-r groups, 5-year event-free survival probabilities varied significantly (21.8%-76.2%; P < .01). ACAs occurred in 46.8% of 1200 patients with complete karyotypes, correlating with inferior overall survival (56.8% vs 67.9%; P < .01). Multivariable analyses confirmed independent associations of 4q21/KMT2A::AFF1, 6q27/KMT2A::AFDN, 10p12/KMT2A::MLLT10, 10p11.2/KMT2A::ABI1, and 19p13.3/KMT2A::MLLT1 with adverse outcomes, but not those of 1q21/KMT2A::MLLT11 and trisomy 19 with favorable and adverse outcomes, respectively. Newly identified ACAs with independent adverse prognoses were monosomy 10, trisomies 1, 6, 16, and X, add(12p), and del(9q). Among patients with 9p22/KMT2A::MLLT3, the independent association of French-American-British-type M5 with favorable outcomes was confirmed, and those of trisomy 6 and measurable residual disease at end of induction with adverse outcomes were identified. We provide evidence to incorporate 5 adverse-risk KMT2A fusions into the cytogenetic risk-group stratification of KMT2A-r pediatric AML, to revise the favorable-risk classification of 1q21/KMT2A::MLLT11 to intermediate risk, and to refine the risk-stratification of 9p22/KMT2A::MLLT3 AML. Future studies should validate the associations between the newly identified ACAs and outcomes and unravel the underlying biological pathogenesis of KMT2A fusions and ACAs

Single-network wide-area persistent scatterer interferometry: Algorithms with application to Sentinel-1 inSAR data

With the launch of ESA’s Sentinel-1 SAR mission, focus is on wide-area Persistent Scatterer Interferometry (PSI) for deformation monitoring. Here, first, non-urban areas also need to be processed; and this requires robust algorithms for scatterer selection, network construction and inversion, and atmospheric phase removal. Second, the computational load can be very high, due to which, the processing is usually divided into overlapping blocks and merged later. This can however lead to spatial error propagation. This paper presents algorithms which have been developed for a robust PSI reference network estimation

Interferometric Processing of Sentinel-1 TOPS Data

Sentinel-1 (S-1) has an unparalleled mapping capacity. In Interferometric Wide Swath (IW) mode, three subswaths imaged in the novel Terrain Observation by Progressive Scans (TOPS) SAR mode result in a total swath width of 250 km. Sentinel-1 has become the European workhorse for large area mapping and interferometric monitoring at medium resolution. The interferometric processing of TOPS data requires however special consideration of the signal properties, resulting from the ScanSAR-type burst imaging and the antenna beam steering in azimuth. The high Doppler rate in azimuth sets very stringent coregistration requirements, making the use of Enhanced Spectral Diversity (ESD) necessary to obtain the required fine azimuth coregistration accuracy. Other unique aspects of processing IW data, such as azimuth spectral filtering, image resampling and data deramping and reramping, are reviewed giving a recipe-like description that enables the user community to use Sentinel-1 IW mode repeat-pass SAR data. Interferometric results from Sentinel-1A are provided, demonstrating the mapping capacity of the S-1 system and its interferometric suitability for geophysical applications. An interferometric evaluation of a coherent interferometric pair over Salar de Uyuni, Bolivia is provided, where several aspects related to coregistration, deramping and synchronization are analysed. Additionally, a spatial and temporal evaluation of the along-track shifts, which are directly related to the orbital/instrument timing error, measured from the SAR data is shown that justifies the necessity to refine the azimuth shifts with ESD. The spatial evaluation indicates high stability of the azimuth shifts for several slices of a datatake

Interferometric Evaluation of Sentinel-1A TOPS data

The European radar satellite Sentinel 1A was launched in April 2014 as the first of the Copernicus Space Component. The Sentinel 1 system has been conceived to provide repeat-pass interferometric capabilities with wide area coverage for medium resolution applications. Wide-swath is achieved by employing the novel TOPS (Terrain Observation by Progressive Scans) acquisition mode. The contribution of this talk focuses on an interferometric evaluation of Sentinel-1A data. A brief description of the interferometric algorithms of the Integrated Wide Area Processor at DLR is provided. The spectral properties of TOPS data are exposed and the stringent coregistration accuracy emphasized, where a pixelwise ESD-based estimator is proposed. Burst mode data require that repeat-pass acquisitions are synchronized in order to obtain coherence over distributed scatterers. An evaluation of the common Doppler bandwidth for two stack of S1A scenes is provided. By exploiting the high sensitivity of TOPS data to the measurement of the along-track shift, an assessment of the shifts is as well provided for two scenarios. In the first place a temporal analysis is done with two stacks of acquisitions in different acquisiton geometries. Geophysical effects as diferential solid Earth tides are compensated. The outcome of this analysis indicates that a mere geometric coregistration is not enough to obtain accurate interferometric results, being necessary to compensate for orbital timing errors. The second analysis focuses on the systematic evaluation of the along-track shifts for a datatake composed by several slices, where good spatial stability is shown