The fully connected N-dimensional skeleton: probing the evolution of the cosmic web

A method to compute the full hierarchy of the critical subsets of a density field is presented. It is based on a watershed technique and uses a probability propagation scheme to improve the quality of the segmentation by circumventing the discreteness of the sampling. It can be applied within spaces of arbitrary dimensions and geometry. This recursive segmentation of space yields, for a $d$-dimensional space, a $d-1$ succession of $n$-dimensional subspaces that fully characterize the topology of the density field. The final 1D manifold of the hierarchy is the fully connected network of the primary critical lines of the field : the skeleton. It corresponds to the subset of lines linking maxima to saddle points, and provides a definition of the filaments that compose the cosmic web as a precise physical object, which makes it possible to compute any of its properties such as its length, curvature, connectivity etc... When the skeleton extraction is applied to initial conditions of cosmological N-body simulations and their present day non linear counterparts, it is shown that the time evolution of the cosmic web, as traced by the skeleton, is well accounted for by the Zel'dovich approximation. Comparing this skeleton to the initial skeleton undergoing the Zel'dovich mapping shows that two effects are competing during the formation of the cosmic web: a general dilation of the larger filaments that is captured by a simple deformation of the skeleton of the initial conditions on the one hand, and the shrinking, fusion and disappearance of the more numerous smaller filaments on the other hand. Other applications of the N dimensional skeleton and its peak patch hierarchy are discussed.Comment: Accepted for publication in MNRA

ASKI: full-sky lensing map making algorithms

Within the context of upcoming full-sky lensing surveys, the edge-preserving non- linear algorithm Aski is presented. Using the framework of Maximum A Posteriori inversion, it aims at recovering the full-sky convergence map from surveys with masks. It proceeds in two steps: CCD images of crowded galactic fields are deblurred using automated edge-preserving deconvolution; once the reduced shear is estimated, the convergence map is also inverted via an edge- preserving method. For the deblurring, it is found that when the observed field is crowded, this gain can be quite significant for realistic ground-based surveys when both positivity and edge-preserving penalties are imposed during the iterative deconvolution. For the convergence inversion, the quality of the reconstruction is investigated on noisy maps derived from the horizon N-body simulation, with and without Galactic cuts, and quantified using one-point statistics, power spectra, cluster counts, peak patches and the skeleton. It is found that the reconstruction is able to interpolate and extrapolate within the Galactic cuts/non-uniform noise; its sharpness-preserving penalization avoids strong biasing near the clusters of the map; it reconstructs well the shape of the PDF as traced by its skewness and kurtosis; the geometry and topology of the reconstructed map is close to the initial map as traced by the peak patch distribution and the skeleton's differential length; the two-points statistics of the recovered map is consistent with the corresponding smoothed version of the initial map; the distribution of point sources is also consistent with the corresponding smoothing, with a significant improvement when edge preserving prior is applied. The contamination of B-modes when realistic Galactic cuts are present is also investigated. Leakage mainly occurs on large scales.Comment: 24 pages, 21 figures accepted for publication to MNRAS

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three genomic nomenclature systems to all sequence data from the World Health Organization European Region available until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation, compare the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2

Position Paper on Water, Energy, Food and Ecosystem (WEFE) Nexus and Sustainable development Goals (SDGs)

The EU and the international community is realising that the Water, Energy, Food and Ecosystem components are interlinked and require a joint planning in order to meet the daunting global challenges related to Water, Energy and Food security and maintaining the ecosystem health and in this way, reach the SDGs. If not dealt with, the world will not be able to meet the demand for water, energy and food in a not too far future and, in any case, in a not sustainable way. The strain on the ecosystems resulting from unsustainable single-sector planning will lead to increasing poverty, inequality and instability. The Nexus approach is fully aligned with and supportive of the EU Consensus on Development. Key elements of the Consensus will require collaborative efforts across sectors in ways that can be supported/implemented by a Nexus approach. In this way, transparent and accountable decision-making, involving the civil society is key and common to the European Consensus on Development and the Nexus approach. The Nexus approach will support the implementation of the SDG in particular SDG 2 (Food), SDG 6 (Water) and SDG 7 (Energy), but most SDGs have elements that link to food, water and energy in one or other way, and will benefit from a Nexus approach. The SDGs are designed to be cross-cutting and be implemented together, which is also reflected in a WEFE Nexus approach. A Nexus approach offers a sustainable way of addressing the effects of Climate Change and increase resilience. The WEFE Nexus has in it the main drivers of climate change (water, energy and food security) and the main affected sectors (water and the environment). Decisions around policy, infrastructure, … developed based on the WEFE Nexus assessments will be suitable as elements of climate change mitigation and adaptation. In fact, it is difficult to imagine solutions to the climate change issue that are not built on a form of Nexus approach. The Nexus approach is being implemented around the world, as examples in the literature demonstrate. These examples together with more examples from EU and member state development cooperation will help build experience that can be consolidated and become an important contribution to a Toolkit for WEFE Nexus Implementation. From the expert discussions, it appears that because of the novelty of the approach, a Toolkit will be an important element in getting the Nexus approach widely used. This should build on experiences from practical examples of NEXUS projects or similar inter-sectorial collaboration projects; and, there are already policy, regulation and practical experience to allow institutions and countries to start applying the Nexus concept.JRC.D.2-Water and Marine Resource

Barriers in Implementation of Wastewater Reuse: Identifying the Way Forward in Closing the Loop

<jats:title>Abstract</jats:title><jats:p>The business case for circular economy in water management perspective has gain relevance in the recent times. By 2030, it is estimated that 160% of global total available water will be required to satisfy demand of anthropogenic-related activities and increasing waste-related water will be produced. Gaps on the conceptual framing of water reuse within supply chain management are clearly emerging and the demand for decision support systems helping at assessing effective water consumption in industrial setting is pressing. Despite the numerous local initiatives towards wastewater resource usage, barriers remain for its implementation in practice. Through a systematic review of previous studies in this field, the barriers towards the uptake of wastewater use in agriculture were classified according to the PESTEL (political, economic, social, technological, environmental and legal) framework. Alongside political and legal support, it is identified that for an economically and environmentally sustainable scheme for incentivising the deployment of feasible technologies, there is also a need to gain acceptance for wastewater usage in society in order to enhance the deployment of existing technological solutions. Addressing these factors in tandem can aid the development towards a circular economy for wastewater.</jats:p&gt

Retinal neovascularization in a case of macular branch retinal vein occlusion

Background, Retinal neovascularization (RNV) has never been described in cases of macular branch retinal vein occlusion (MBRVO), due to the limited amount of ischemia in this form of retinal vein occlusion. Ischemic areas as wide as 5-10 disc diameters were required by previous studies to count as ischemic cases of central or major branch retinal vein occlusion. Case report. A 56-year-old woman who had been suffering from MBRVO for 3 years presented at the posterior pole a zone of non-perfusion, extending over 7.5 disc areas, and three small tufts of RNV. RNV regressed after two subsequent laser treatments of the ischemia. Retrohyaloid hemorrhage was observed 2 months after the first treatment. Conclusion. Since the average diameter of the non-perfused area was about 2.75 disc diameters, this case demonstrates that small RNVs can appear in less extensive areas of ischemia than is generally believed