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See detailEffects of wildflower strips and an adjacent forest on aphids and their natural enemies in a pea field
Hatt, Séverin ULiege; Mouchon, Pierre; Chevalier Mendes Lopes, Thomas ULiege et al

in Insects (2017), 8(3), 99

Landscape diversification is a key element for the development of sustainable agriculture. This study explores whether the implementation of habitats for pest natural enemies enhances conservation ... [more ▼]

Landscape diversification is a key element for the development of sustainable agriculture. This study explores whether the implementation of habitats for pest natural enemies enhances conservation biological control in an adjacent field. In the present study conducted in Gembloux (Belgium) in 2016, the effect of two different habitats (wildflower strips and a forest) and aphid abundance on the density of aphid natural enemies, mummified aphids and parasitism on pea plants was assessed through visual observations. The effect of the habitats on aphids was also evaluated. The habitats but not aphid density significantly affected hoverfly larvae, which were more abundant adjacent to wildflower strips than to the forest. The contrary was observed for ladybeetle adults, which were positively related with aphids but not affected by the adjacent habitats. The abundance of mummies and the parasitism rate were significantly affected by both the habitats and aphid density. They were both significantly enhanced adjacent to wildflower strips compared to the forest, but the total parasitism rate was low (<1%), questioning whether parasitoids could significantly control aphids on the pea crop. As for the aphids, their abundance was not significantly affected by the adjacent habitats. These results are discussed with respect to the potential of these habitats to provide overwintering sites and food resources for natural enemies, and thereby enhance conservation biological control. [less ▲]

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See detailAdvanced data processing for high-contrast imaging - Pushing exoplanet direct detection limits with machine learning
Gómez González, Carlos ULiege

Doctoral thesis (2017)

Since ancient times, mankind has wondered whether other solar systems exist around other stars somewhere in the Universe. It took many centuries to finally prove the existence of extra-solar planetary ... [more ▼]

Since ancient times, mankind has wondered whether other solar systems exist around other stars somewhere in the Universe. It took many centuries to finally prove the existence of extra-solar planetary systems. Nowadays, more than 3500 exoplanets have been discovered, mostly thanks to indirect detection methods. Indeed, the task of directly detecting exoplanets through high-contrast imaging (HCI) is a formidable challenge, and has only been enabled in the last decade thanks to advances in instrumentation and dedicated image processing algorithms. This last component of the exoplanet direct imaging pipeline is what ultimately pushes the detection limits and sensitivity of HCI instruments and survey campaigns. Unfortunately, the HCI community has been slow in adopting the latest developments in data management and machine learning for analyzing the increasing amount of available data. This dissertation is an attempt to fill in this very gap, and develops at the interface of computer science, machine learning, statistics, and astrophysics. This work contributes to the field of data processing for HCI in two main ways. On one hand, I have developed an open source \texttt{Python} library for taking HCI data from the raw state up to the characterization of companions. It implements state-of-the-art approaches and is positioning itself as one of the de facto software solutions for building HCI pipelines. I have also participated to the critical analysis of data from different first and second generation HCI instruments. On the other hand, I have approached the task of exoplanet detection in angular differential imaging sequences from a computer vision and machine learning perspective. This interdisciplinary work has led to novel algorithmic solutions, extending unsupervised learning techniques widely used in HCI and proposing advanced supervised learning approaches based on cutting-edge deep learning models. My novel algorithms have been presented using a robust performance assessment framework to produce large comparative performance studies. These studies show the improved sensitivity vs specificity trade-off of the proposed supervised detection approach. The proposed algorithms bring the possibility of re-processing existing HCI databases to maximize their scientific return and potentially improve the demographics of directly imaged exoplanets. [less ▲]

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See detailEconomic Development and Structural Change
Van Neuss, Leif ULiege

Doctoral thesis (2017)

This doctoral dissertation contributes to the understanding of structural change, often defined as the process of reallocation of economic activity and resources across the three broad sectors agriculture ... [more ▼]

This doctoral dissertation contributes to the understanding of structural change, often defined as the process of reallocation of economic activity and resources across the three broad sectors agriculture (primary sector), manufacturing (secondary sector) and services (tertiary sector). Increasingly connected to the study of modern growth, the analysis of structural change has known an important revival over recent decades, due in part to the economic concerns associated with the movement of deindustrialization that has particularly affected the world’s most economically successful countries since the last third of the 20th century. These concerns have indeed fed many discussions on the causes and consequences of structural change, as well as on the role of policy instruments in driving and accompanying the inter-sectoral reallocation of activity. The first part of the thesis gets particularly interested in the driving forces behind the process of structural change. It begins by placing structural change in a very long historical perspective, notably shedding light on the factors that contributed to the emergence of the Industrial Revolution, an event characterized by the acceleration of structural change and traditionally considered as a turning point in the history of mankind because it eventually brought about modernity. It then analyzes the main causes of structural change in market economies, putting a particular emphasis on two mechanisms of structural change that have been largely overlooked in the recent multi-sector growth literature: changes in input-output (sectoral) linkages and changes in comparative advantage via globalization and trade. With respect to trade, an empirical analysis reveals that global exchanges have the potential to influence significantly and substantially a country’s sectoral patterns of employment, and that the estimated contribution of trade, especially of trade with developing countries, to recent structural change (deindustrialization) in affluent countries may be revised upwards when resorting to better-suited indicators of trade in manufactures. The second part of this doctoral thesis deals more with the economic effects of structural change. In particular, it proposes a new shift-share method, which is an accounting method aimed at computing the impact of the economic structure - or structural change - on a territory’s economic performance. By way of illustration, it provides an application to manufacturing employment in the Belgian provinces between 1995 and 2007. [less ▲]

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See detailFrom seed to vegetable and from vegetable to seed : constructing a right to existence
Hecquet, Corentin ULiege

Conference (2017, September 12)

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See detailSimultaneous detection of Wheat dwarf virus, northern cereal mosaic virus, barley yellow striate mosaic virus and rice black-streaked dwarf virus in wheat by multiplex RT-PCR
Zhang, Peipei; Liu, Yan; Liu, Wenwen et al

in Journal of Virological Methods (2017), 249

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See detailLiDAR aérien et autres nuages de points pour la cartographie multi-échelles
Poux, Florent ULiege; Neuville, Romain ULiege; Kasprzyk, Jean-Paul ULiege et al

Conference (2017, September 12)

Utilisation de nuage de points pour la cartographie 3D multi-échelles. Exemples d'utilisation et définition de workflows pour assurer l'interopérabilité lors de la fusion de données issues de différents ... [more ▼]

Utilisation de nuage de points pour la cartographie 3D multi-échelles. Exemples d'utilisation et définition de workflows pour assurer l'interopérabilité lors de la fusion de données issues de différents capteurs. [less ▲]

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See detailInfluences of feeding behaviour and forage quality on diurnal methane emission dynamics of grazing cows
Blaise, Yannick ULiege; Andriamandroso, Andriamasinoro ULiege; Heinesch, Bernard ULiege et al

in Berckmans, Daniel; Keita, Keita (Eds.) Precision Livestock Farming ‘17 (2017, September 12)

This study aimed to evaluate diurnal methane (CH4) emission dynamics of grazing cattle and highlight their relationships with biotic factors such as the feeding behaviour as well as seasonal changes in ... [more ▼]

This study aimed to evaluate diurnal methane (CH4) emission dynamics of grazing cattle and highlight their relationships with biotic factors such as the feeding behaviour as well as seasonal changes in pasture characteristics. Existing methods to assess grazing ruminants’ daily CH4 emissions provide useful insights to investigate mitigation strategies relying on feeding and genetic selection. Nonetheless such methods based on tracer gases (SF6) or feeding bins equipped with sniffers (e.g. GreenFeed) can hardly cover diurnal CH4 emission fluctuations which can influence the accuracy of total CH4 production estimations. Previous studies in barns showed that emission dynamics strongly vary during post feeding time, leading to a possible bias in estimates of daily CH4 emissions as high as 100%. To investigate whether such fluctuations are also taking place on pasture, a portable device was designed with infrared CH4 and CO2 sensors measuring concentrations in the exhaled air at a high sampling rate (4 Hz). Six grazing dry red-pied cows were equipped with the device and motion sensors during runs of 24h to monitor CH4 and CO2 emissions and detect their feeding behaviours (grazing, rumination and other behaviours), respectively. This experiment was performed in summer and fall in order to cover seasonal changes in pasture forage quality. Methane emission was estimated from the CH4:CO2 concentration ratio and the metabolic CO2 production of the cows. As for barn studies, variations were observed in total daily CH4 emission due to the seasons and diurnal variations were also observed due to animal behaviours. Relationships between animal feeding behaviour and CH4 emissions patterns on pasture were also unravelled. [less ▲]

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See detailManaging and authenticating non-institutional users in Alma: two experiences
Brownlie, Helen; De Groof, Robert ULiege; Renaville, François ULiege

Conference (2017, September 12)

The management of patron information within Alma is primarily reliant on two systems – the creation and updating of patron information by an external system such as student management or HR systems or ... [more ▼]

The management of patron information within Alma is primarily reliant on two systems – the creation and updating of patron information by an external system such as student management or HR systems or internally within Alma itself. A recent survey of the Alma community indicated the majority of institutions utilize a mixture of these external and internal processes. In addition to providing access to affiliated staff and students more than 89% of institutions responded that they provided user accounts to non-affiliated users such as the general public, members of other academic institutions, alumni, etc. Providing authenticated access to library services for the latter group relies heavily on Alma for password management. This presentation will outline the processes in place at the University of Otago and at the University of Liège for managing and authenticating non-institutional users and the possible effect of Ex Libris' proposed changes to internal authentication. [less ▲]

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See detailSampling only 10 μL of whole blood to study the bioavailability of itraconazole formulations in rats
Kok, Miranda ULiege; Thiry, Justine ULiege; Evrard, Brigitte ULiege et al

Conference (2017, September 12)

Background Volumetric absorptive microsampling (VAMS) offers a unique opportunity to collect small and accurate quantities of biological fluids. This sampling technique is of great interest for volume ... [more ▼]

Background Volumetric absorptive microsampling (VAMS) offers a unique opportunity to collect small and accurate quantities of biological fluids. This sampling technique is of great interest for volume-limited samples and for the collection of multiple samples from the same animal. This serial sample collection may reduce the number of required study animals, thereby fulfilling the three Rs rule (refine, reduce, replace). Here, we demonstrate the applicability of VAMS to study the bioavailability of drug formulations in rats. Methods Four itraconazole-containing formulations were successively administered to rats with a wash-out period of one week. VAMS was used to collect 14 whole blood samples of only 10 μL each within a time frame of 48 hours after administration of the different drug formulations. Particular attention was paid to sample preparation and stability. The extraction of itraconazole and its main metabolite hydroxy-itraconazole was optimized to provide a high recovery and minimal matrix effects. A developed and validated LC–MS/MS method was used for the quantification of the two compounds. Pharmacokinetic profiles for the different formulations were constructed and compared. Results The stability of itraconazole and hydroxy-itraconazole in dried VAMS samples of whole rat blood could not be guaranteed for more than a day when the samples were stored at room temperature. However, samples were stable for at least two weeks when stored at -80°C after sample preparation. Differences in pharmacokinetic profiles were observed for the tested drug formulations. Whole blood concentrations of itraconazole and its main metabolite were significantly higher after administration of three in-house produced formulations compared to concentrations obtained with a commercially available product. Moreover, these in vivo results could be partly related to in vitro dissolution rates of the various formulations. Conclusions VAMS is an attractive approach for bioavailability studies. Due to the low blood volumes per sampling point, the same rats can be used to compare various drug formulations. Therefore, the number of required animals can be drastically reduced. Moreover, this helps to suppress the inter-individual variability and strengthens the validity of results. [less ▲]

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See detailComparaison de l'impact de deux méthodes d'apprentissage sur la sécurité d'administration des médicaments : stages cliniques versus simulation
Servotte, Jean-Christophe ULiege; Galerin, Catherine ULiege; Ghuysen, Alexandre ULiege et al

Conference (2017, September 12)

Introduction Drug administration is the act nurses most frequently do. However, 50% of errors occur during administration. The damage these errors causes to patients, results in excess mortality rates and ... [more ▼]

Introduction Drug administration is the act nurses most frequently do. However, 50% of errors occur during administration. The damage these errors causes to patients, results in excess mortality rates and health care costs, hence leading to a major public health problem. Therefore, it is advisable to consider the training of future nurses on the practice of this delicate act. The objective of this study is to evaluate the impact of teaching by simulation combined with the internship on the safety administration of intravenous drugs by nursing students, compared to just the internship alone. Material and method A selection of 99 students from the bachelors’ block two of the Namur-Liege-Luxembourg Higher Institute of Nursing met the inclusion criteria under consideration. They were divided into two groups, one experimental group which participated in a simulation session and a control group, the latter did not participate in the simulation session. At the start of the research, all students were assessed by an objective structured clinical examination (OSCE) with the theme of modifying infusion and syringe flow rates. They were also asked to complete a questionnaire concerning their knowledge and self-efficacy feeling related to drug administration. The experimental group then participated in the simulation sessions. The experimental group and the control group also went into four weeks of training in medical or surgical services before participating in the second stage of the study. The latter consisted of the same tests and questionnaires as stage one of the study. The evolution of the results of the two groups was first observed separately before being compared. Results The majority of the results shows that the simulation improves, in a way significantly more important than the clinical course, the acquisition of skills and knowledge, as well as the feeling of self-efficacy in drug administration. On the other hand, the assessment of the level of stress linked to drug administration and the professional attitude evaluated during the OSCE were not significantly more improved by the simulation than by the training alone (stress: p-value = 0.8269, professional attitude = 0.9857). Conclusions For the students in the experimental group, the simulation showed a positive impact on the skills, knowledge and feeling of self-efficacy associated with drug administration. Changes and continuation of the study would make it possible to go further in the generalization of results, in the evaluation of learning outcomes, and to attest to their sustainability. [less ▲]

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See detailContributions to deep reinforcement learning and its applications in smartgrids
François-Lavet, Vincent ULiege

Doctoral thesis (2017)

Reinforcement learning and its extension with deep learning have led to a field of research called deep reinforcement learning. Applications of that research have recently shown the possibility to solve ... [more ▼]

Reinforcement learning and its extension with deep learning have led to a field of research called deep reinforcement learning. Applications of that research have recently shown the possibility to solve complex decision-making tasks that were previously believed extremely difficult for a computer. Yet, deep reinforcement learning requires caution and understanding of its inner mechanisms in order to be applied successfully in the different settings. As an introduction, we provide a general overview of the field of deep reinforcement learning. In the first part of this thesis, we provide an analysis of reinforcement learning in the particular setting of a limited amount of data and in the general context of partial observability. In this setting, we focus on the tradeoff between asymptotic bias (suboptimality with unlimited data) and overfitting (additional suboptimality due to limited data), and theoretically show that while potentially increasing the asymptotic bias, a smaller state representation decreases the risk of overfitting. An original theoretical contribution relies on expressing the quality of a state representation by bounding $L_1$ error terms of the associated belief states. We also discuss and empirically illustrate the role of other parameters to optimize the bias-overfitting tradeoff: the function approximator (in particular deep learning) and the discount factor. In addition, we investigate the specific case of the discount factor in the deep reinforcement learning setting case where additional data can be gathered through learning. In the second part of this thesis, we focus on a smartgrids application that falls in the context of a partially observable problem and where a limited amount of data is available (as studied in the first part of the thesis). We consider the case of microgrids featuring photovoltaic panels (PV) associated with both long-term (hydrogen) and short-term (batteries) storage devices. We propose a novel formalization of the problem of building and operating microgrids interacting with their surrounding environment. In the deterministic assumption, we show how to optimally operate and size microgrids using linear programming techniques. We then show how to use deep reinforcement learning to solve the operation of microgrids under uncertainty where, at every time-step, the uncertainty comes from the lack of knowledge about future electricity consumption and weather dependent PV production. [less ▲]

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See detailContent Working Group Report 2016-2017
Renaville, François ULiege; Varjabedian, Kathy

Conference (2017, September 11)

Report on the activities in 2016-2017 of the Content Working Group (previously Knowledge Base Advisory Board [KBAB]).

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See detailPreliminary Phytochemical Content and Antidiabetic Potential Investigations of Panda oleosa (Pierre) Used in Kisangani Areas
Katemo Muhoya, Frédéric; Kadima Ntokamunda, Justin; Njakarinala Ranarivelo et al

in American Journal of Analytical Chemistry (2017), 8

Panda oleosa Pierre (POP), a tropical plant tree, has been used in traditional medicine in Kisangani city and around to treat various diseases including diabètes and HIV/AIDs. This study aims to evaluate ... [more ▼]

Panda oleosa Pierre (POP), a tropical plant tree, has been used in traditional medicine in Kisangani city and around to treat various diseases including diabètes and HIV/AIDs. This study aims to evaluate the chemical composition of POP extracts while setting up chromatographic fingerprints for their quality control, and the anti-hyperglycemic potential of trunk bark aqueous extracts of POP. Common chemical reactions were used for identification of main secondary metabolic groups. Thin layer chromatography was used to set up several chromatographic fingerprints of water and alcoholic extracts while evaluating chemical composition. Oral glucose tolerance test served to induce hyperglycemia in a rabbit model. The extracts were given as 25 mg/kg, 50 mg/kg, and 100 mg/kg body weight, 30 minutes before loading animals with glucose 4 g/kg. Blood samples were collected at various times: just before extracts (T-30), before (T0) and after glucose load (T30, T60, T120, and T180). Blood glucose levels were measured with One Touch Glucometer. The identification tests revealed the presence of saponins (3.58%), tannins (5%); alkaloids, quinones, flavonoids, and terpenes sterols could not be formerly detected by the reagents used. Interesting chromatographic spots were observed whose behaviors are of catechic tannin proanthocyanes. The extract significantly reduced glucose levels in dose dependent manner as compared to control and glibenclamide reference groups. The average of mean percentage of reduction in glucose level at T120 with the extract 100 mg/kg was close to that of glibenclamide 0.25 mg/kg (49% and 40.2%). These findings back the traditional use of the plant to treat diabetic patients and constitute a foundation for an extensive study to find a new antidiabetic phythomedicine. [less ▲]

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See detailBuckling of steel plates at elevated temperatures: Theory of perfect plates vs finite element analysis
Maraveas, Chrysanthos ULiege; Gernay, Thomas ULiege; Franssen, Jean-Marc ULiege

in Proceedings of CONFAB'17 Conference (2017, September 11)

The local buckling capacity of fire exposed thin-walled steel cross sections is affected by the reduction in strength and stiffness due to elevated temperatures and the amplitude of the initial local ... [more ▼]

The local buckling capacity of fire exposed thin-walled steel cross sections is affected by the reduction in strength and stiffness due to elevated temperatures and the amplitude of the initial local imperfections. Several researchers have proposed design methods to calculate the capacity of the plates (i.e. web and flanges) that compose these steel members at elevated temperatures, but they used different shapes of steel plates (sides ratio a/b) and different amplitudes of local imperfections. This variability in hypotheses happens because there is no clear provision defining the numerical modeling procedure for fire design of steel plates in the codes (European or US). According to the theory of perfect plates, the critical load depends of the shape of the rectangular plate (e.g. the sides ratio a/b) and the corresponding buckling mode (number of half waves), the boundary and the loading conditions. This paper reviews the existing code provisions and compares the existing design models and their assumptions for thin-walled steel cross sections. Elements of the theory of perfect plates are presented. Parametric finite element analyses are then conducted on isolated steel plates at elevated temperatures to investigate the effect of the plate shape (a/b ratio) and imperfections (amplitude and number of half wave lengths). From the analysis, the governing parameter will be estimated (a/b vs imperfections) for simulation of isolated flanges and webs. Finally, recommendations for the numerical modeling of steel plates at elevated temperatures are proposed. [less ▲]

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See detailIdentification et analyse fonctionnelle de nouveaux variants d’épissage du CD46 des bovidés, le (co)-récepteur du virus BVD/MD
Alzamel, Nidal ULiege

Doctoral thesis (2017)

The pestivirus bovine viral diarrhea virus (BVDV) is known to bind to the CD46 molecule, which subsequently promotes entry of the virus. Mapping of the BVD-virion-binding site has shown that two peptides ... [more ▼]

The pestivirus bovine viral diarrhea virus (BVDV) is known to bind to the CD46 molecule, which subsequently promotes entry of the virus. Mapping of the BVD-virion-binding site has shown that two peptides, 66EQIV69 and 82GQVLAL87, located on antiparallel beta sheets in the most distal complement control protein module (CCP1), provide the attachment platform. In the present study, we reveal new CD46-encoding transcripts that are predicted to encode CCP1-containing soluble forms. Further, we show that the serum of most adult cattle contains soluble CD46 (sCD46) and that a recombinant soluble isoform neutralizes BVDV infectivity in an in vitro assay. We have then established an ELISA for determination of plasma sCD46 in a large cohort of animals. Overall, serum sCD46 amounts to 8 ± 18 ng/mL (mean ± SD, n = 543), with a IC [95-105] ranging from 6,4 to 9,8 ng/mL and extreme values between 0 and 178 ng/mL. We found that sCD46 is not detectable in fetal and neonatal sera and that its plasma concentration increases progressively up to adulthood. We also detected high- and low-sCD46 performers and show that this phenotype does not depend of environment. As modern rearing techniques make it possible to disseminate genetically-determined phenotypes very quickly in a population, a large-scale study examining whether high-sCD46 animals provide epidemiological protection against BVDV infection and transmission should be undertaken [less ▲]

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See detailExtracting oscillating components from nonstationary time series: A wavelet-induced method
Deliège, Adrien ULiege; Nicolay, Samuel ULiege

in Physical Review. E : Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics (2017), 96

This paper consists in the description and application of a method called wavelet-induced mode extraction (WIME) in the context of time-frequency analysis. WIME aims to extract the oscillating components ... [more ▼]

This paper consists in the description and application of a method called wavelet-induced mode extraction (WIME) in the context of time-frequency analysis. WIME aims to extract the oscillating components that build amplitude modulated-frequency modulated signals. The essence of this technique relies on the successive extractions of the dominant ridges of wavelet-based time-frequency representations of the signal under consideration. Our tests on simulated examples indicate strong decomposition and reconstruction skills, trouble-free handling of crossing trajectories in the time-frequency plane, sharp performances in frequency detection in the case of mode-mixing problems, and a natural tolerance to noise. These results are compared with those obtained with empirical mode decomposition. We also show that WIME still gives meaningful results with real-life data, namely, the Oceanic Niño Index. [less ▲]

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See detailAn update on ozone profile trends for the period 2000 to 2016
Steinbrecht, Wolfgang; Froidevaux, Lucien; Fuller, Ryan et al

in Atmospheric Chemistry and Physics (2017), 17(17), 10675-10690

Ozone profile trends over the period 2000 to 2016 from several merged satellite ozone data sets and from ground-based data by four techniques at stations of the Network for the Detection of Atmospheric ... [more ▼]

Ozone profile trends over the period 2000 to 2016 from several merged satellite ozone data sets and from ground-based data by four techniques at stations of the Network for the Detection of Atmospheric Composition Change indicate significant ozone increases in the upper stratosphere, between 35 and 48 km altitude (5 and 1 hPa). Near 2 hPa (42 km), ozone has been increasing by about 1.5 % per decade in the tropics (20°S to 20°N), and by 2 to 2.5 % per decade in the 35° to 60° latitude bands of both hemispheres. At levels below 35 km (5 hPa), 2000 to 2016 ozone trends are smaller and not statistically significant. The observed trend profiles are consistent with expectations from chemistry climate model simulations. Using three to four more years of observations and updated data sets, this study confirms positive trends of upper stratospheric ozone already reported, e.g., in the WMO/UNEP Ozone Assessment 2014, or by Harris et al. (2015). The additional years, and the fact that nearly all individual data sets indicate these increases, give enhanced confidence. Nevertheless, a thorough analysis of possible drifts and differences between various data sources is still required, as is a detailed attribution of the observed increases to declining ozone depleting substances and to stratospheric cooling. Ongoing quality observations from multiple independent platforms are key for verifying that recovery of the ozone layer continues as expected. [less ▲]

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