Environmental studies with Landsat images have revealed many of the problems faced by wetland ecosystem, which are crucial for the conservation of biodiversity and the natural values of our planet. ...The study of LULC changes in wetlands through remote sensing constantly helps to identify and combat their main environmental threats improving the conservation of these natural habitats. Starting in mid-2015, the Sentinel-2 satellite opens new possibilities in the field of earth observation thanks to its higher spatial, spectral and temporal resolution becoming a powerful source of information for LULC monitoring in wetland areas. However, researchers may ask them selves to what extent Sentinel-2 is an improvement over Landsat 8 for general purposes. This research test if there is a real difference in the quality of the results delivered by both Sentinel-2 and Landsat 8 imagery when basic classification methods are applied.
The study uses Sentinel-2 and Landsat 8 imagery to produce LULC maps in a Mediterranean wetland area applying an object based classification method in order to compare the accuracy and reliability in the surface detected by both satellites. The results show that an object based classification using only the Sentinel-2 and Landsat 8 image information, without band indexes or ancillary data, offers very similar results for most LULC classes, being the overall accuracy around 87–88% with slightly better results when using Sentinel-2. Although using Sentinel-2 leads to an increase in file size and processing times, the analysis of certain LULC classes presents an improvement compared to Landsat 8, detecting more linear and small size elements with a better delineation of image features in the classified map. However, these improvements should not underestimate the value of Landsat imagery in the future since both satellites provide high precision information, so they can and should coexist and be used together to increase data availability in order to have the best possible results in remote sensing research.
•Sentinel-2 improves spatial, spectral and temporal resolution regarding Landsat 8.•Classification results with both satellites are very similar for most LULC classes.•Small objects and linear elements are better represented with Sentinel-2.•Both satellites can be used together in remote sensing studies with good results.•Full use of Sentinel-2 increases technical requirements of remote sensing studies.
Ischemic stroke, triggered by an obstruction in the cerebral blood supply, leads to infarction of the affected brain tissue. An accurate and reproducible automatic segmentation is of high interest, ...since the lesion volume is an important end-point for clinical trials. However, various factors, such as the high variance in lesion shape, location and appearance, render it a difficult task.
In this article, nine classification methods (e.g. Generalized Linear Models, Random Decision Forests and Convolutional Neural Networks) are evaluated and compared with each other using 37 multiparametric MRI datasets of ischemic stroke patients in the sub-acute phase in terms of their accuracy and reliability for ischemic stroke lesion segmentation. Within this context, a multi-spectral classification approach is compared against mono-spectral classification performance using only FLAIR MRI datasets and two sets of expert segmentations are used for inter-observer agreement evaluation.
The results of this study reveal that high-level machine learning methods lead to significantly better segmentation results compared to the rather simple classification methods, pointing towards a difficult non-linear problem. The overall best segmentation results were achieved by a Random Decision Forest and a Convolutional Neural Networks classification approach, even outperforming all previously published results. However, none of the methods tested in this work are capable of achieving results in the range of the human observer agreement and the automatic ischemic stroke lesion segmentation remains a complicated problem that needs to be explored in more detail to improve the segmentation results.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Spuren digitaler Artikulationen Nick Böhnke, Christoph Richter, Christoph Schröder, Martina Ide, Heidrun Allert / Heidrun Allert, Nick Böhnke, Martina Ide, Christoph Richter, Christoph Schröder
2022
eBook
Scheinbar unablässig wird in den Sozialen Medien gepostet und geliked. Soziale Medien fungieren als Orte informeller und direkter Kommunikation sowie Interaktion, an denen neue kulturelle ...Ausdrucksformen verhandelt und weitergetragen werden. Hier zeigt sich eine derart komplexe Gemengelage unterschiedlichster und zugleich aufeinander bezogener digitaler Mediennutzungspraktiken, dass die theoretische Annäherung an die Überschüssigkeit sozialer Praktiken in Sozialen Medien nur im Denken eines Entzugs stattfinden kann.Ausgehend von der Interdependenz von Aisthesis, Artikulation und Technik unternehmen die Beiträger*innen des Bandes Versuche, die Spuren kultureller Bildungs- und Transformationsprozesse in Sozialen Medien aus unterschiedlichen disziplinären Perspektiven (auf-)zulesen.
Die Betroffenheit von relativer Einkommensarmut weist große regionale Unterschiede auf. In der herkömmlichen Betrachtung mit (nominal) bundeseinheitlichem Schwellenwert zeigt sich ein deutliches ...Ost-West-Gefälle (5 Prozentpunkte Differenz) und ein fast ebenso großer Stadt-Land-Unterschied. Ein nominal gleich hoher Einkommensschwellenwert hat in den verschiedenen Regionen Deutschlands jedoch eine unterschiedlich hohe Kaufkraft. Daher werden hier die Individualeinkommen um die regionalen Preisunterschiede bereinigt, und es wird analog zur Einkommensarmut die relative Kaufkraftarmut berechnet. Diese weist differenziertere regionale Muster mit einem stark ausgeprägten Stadt-Land-Gefälle aus: Die Unterschiede zwischen ostdeutschen und westdeutschen Bundesländern betragen bei der relativen Kaufkraftarmut 2 Prozentpunkte, die Differenz zwischen Stadt und Land dagegen fast 8 Prozentpunkte. Die hohe Betroffenheit der Städte ergibt sich zum einen aus dem dort hohen Preisniveau. Zum anderen ist der Bevölkerungsanteil von Gruppen mit deutschlandweit erhöhter Armutsgefährdung (beispielsweise Arbeitslose, Alleinerziehende, Personen mit Migrationshintergrund) in Städten überdurchschnittlich hoch. Zudem sind diese Gruppen in Großstädten besonders stark armutsgefährdet.
We propose a novel method to avoid stereo window violations at screen borders. These occur for objects in front of the zero parallax plane, which appear in front of the (physical) screen, and that ...are clipped for one eye while still being visible for the other eye. This contradicts other stereo cues, particularly disparity, potentially resulting in eye strain and simulator sickness. In interactive and dynamic virtual environments, where the user controls the camera, for example, via head tracking, it is impossible to avoid stereo window violations completely. We propose Dynparity, a novel rendering method to eliminate the conflict between clipping and negative disparity, by introducing a nonuniform stereoscopic projection. For each vertex in front of the zero parallax plane, we compute the stereoscopic projection such that the parallax approaches zero toward the edge of the screen. Our approach works entirely on the GPU in real‐time and can be easily included in modern game engines. We conducted a user study comparing our method to the standard stereo projection on a large‐screen stereo wall with head tracking. Our results show significantly reduced simulator sickness when using Dynparity compared to the standard stereo rendering.
Stereo window violations in 3D rendering occur when virtual objects in front of a physical screen are clipped at the screen borders. Dynparity introduces a real‐time, per‐vertex, nonuniform projection to eliminate this adversary effect. Our user study shows that Dynparity significantly reduces simulator sickness compared to standard stereo rendering on a large stereo projection screen.
Fiscal rules have become popular to limit deficits and high debt burdens in many countries. A growing literature examines their impact based on aggregate fiscal performance. So far, no evidence ...exists on how fiscal rules influence deficit expectations of fiscal policy makers. In the context of the German debt brake, we study this expectation dimension. In a first step, we introduce a dynamic model in an environment characterized by lagged implementation of a new rule, which in turn characterizes the setup of the German debt brake and raises credibility issues. In a second step, we analyze a unique survey of members of all 16 German state parliaments and show that the debt brake's credibility is far from perfect. The heterogeneity of compliance expectations in the survey corresponds to our theoretical predictions regarding states' initial fiscal conditions, specific state fiscal rules, and bailout perceptions. In addition, there is a robust asymmetry in compliance expectations between insiders and outsiders (both for in-state vs. out-of-state politicians and the incumbent government vs. opposition dimension), which we attribute to overconfidence rather than noisy information.
•Examines theoretically and empirically how fiscal rules influence deficit expectations of policy makers•Theoretical model highlights the role of initial fiscal conditions and bailout expectations for compliance•Empirical analysis tests hypotheses from theoretical model using survey data from 639 members of German state parliaments•Perceptions about compliance differ between in state and out of state politicians due to overconfidence
A mechanism to restructure the debt of an insolvent euro country is a missing element in the emerging institutional architecture of the euro area. The introduction of an insolvency procedure for ...sovereigns faces a dilemma: in the foreseeable future, its introduction would risk pushing Europe back into acute crisis; but the indefinite postponement of reform would impair the credibility of a future regime change. Against this background, this article reviews arguments and existing blueprints for sovereign insolvency procedures in the euro area and develops a Viable Insolvency Procedure for Sovereigns. This procedure avoids any sudden measures which could destabilize the present fragile situation but carefully designs an irreversible transition toward the new regime. The proposal comprises two pillars: an insolvency procedure for the long run and a credible bridge toward that system.
Bereits der Einführung des Mindestlohns zum 1.1.2015 ist eine Debatte über Tarifautonomie und Beschäftigungseffekte vorausgegangen. In der Ex-post-Betrachtung lässt sich feststellen, dass die ...negativen Beschäftigungsverhältnisse im Wesentlichen ausgeblieben sind. Nun hat die Ampelregierung die politisch bestimmte Erhöhung des Mindestlohns auf 12 Euro beschlossen. Es stellt sich die Frage, ob diese deutliche Anhebung den Mindestlohn auf eine Höhe setzt, die sozialpolitische Risiken in sich birgt und zu Arbeitsplatzverlusten im Niedriglohnbereich führen wird.
The introduction of the minimum wage on 1 January 2015 was preceded by a lively debate on collective bargaining autonomy and employment effects. In an expost analysis, it appears that the negative employment effects have essentially failed to materialise. Now the German "traffic light" coalition government has decided on an increase of the minimum wage of 12 euros. The question now is whether this significant increase will set the minimum wage at a level that entails socio-political risks and will lead to job losses in the low-wage sector.
Wetlands are the most fragile and threatened ecosystems worldwide, and also one of the most rapidly declining. At the same time wetlands are typically biodiversity hotspots and provide a range of ...valuable ecosystem services, such as water supply and purification, disaster risk reduction, climate change adaptation, and carbon sequestration.
Pressures on wetlands are likely to further intensify in the coming decades due to increased global demand for land and water, and due to climate change. Stakeholders at all levels of governance have to be involved to slow, stop and reverse these processes. However, the information they need on wetland extent, their ecological character, and their ecosystem services is often scattered, sparse and difficult to find and access.
The freely available Sentinel satellite data of the Copernicus Programme, as well as the Landsat archive, provide a comprehensive basis to map and inventory wetland areas (extent), to derive information on the ecological status, as well as long- and short-term trends in wetland characteristics. However, making use of these Earth Observation (EO) resources for robust and standardized wetland monitoring requires expert knowledge on often complex data processing techniques, which impedes practical implementation. In this respect, the Satellite-based Wetland Observation Service (SWOS), a Horizon 2020 funded project (www.swos-service.eu) has developed and made disseminated monitoring approaches based on EO data, specifically designed for less experienced satellite data users.
The SWOS monitoring tools aim at assisting countries in conducting national wetland inventories for their Sustainable Development Goals (SDG) reporting and monitoring obligations, and additionally facilitates other monitoring obligations such as those required by the Ramsar Convention and supports decision-making in local conservation activities. The four main components of the SWOS approach are: map and indicator production; software development; capacity building; and initializing the GEO Wetlands Community Portal. Wetland managers and data analysists from more than fifty wetland sites and river basins across Europe, the Middle East, and Africa investigated the benefits and limitations of this EO-based wetland mapping and monitoring approach.
We describe research that applies the SWOS tools to test their potential for the mapping of wetlands in a case study based in Albania, and show its effectiveness to derive metrics relevant to the monitoring of SDG indicator 6.6.1.
•Tools for EO-based SDG indicator 6.6.1 reporting are demonstrated.•Standardized nomenclature and GEOclassifier tools for indicator development.•GEO-Wetlands Community Portal to demonstrate policy-related wetland reporting tools.•Albania example to show-case nationwide policy-related reporting opportunities.
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