876 research outputs found

    Towards a More Equal City: Framing the Challenges and Opportunities

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    Cities are growing differently today than before. As much as 70 percent of people in emerging cities in Asia, Africa and Latin America is under-served. Furthermore, cities face challenges in four areas:Highest rates of urbanization are in sub-Saharan Africa, South and Southeast AsiaUrbanization is now happening in more low-income countries than in the pastThe share of poor people living in urban areas is on the rise worldwideCities in the Global South have the fewest public resources per capitaWe need a new approach that will benefit all urban residents and create sustainable, productive cities for the 21st century. The World Resources Report (WRR) examines if prioritizing access to core urban services, we can create cities that are prosperous and sustainable for all people.This first installment of the WRR developed a new categorization of cities into emerging, struggling, thriving, and stabilizing cities. It focuses on solutions for struggling and emerging cities—over half the cities included in the analysis—because they have the greatest opportunity to alter their development trajectory

    Shrubs indirectly increase desert seedbanks through facilitation of the plant community

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    The mechanisms supporting positive ecological interactions are important. Foundation species can structure desert biodiversity by facilitating seedbanks of annual plants, but the direct and indirect mechanisms of shrub effects on seedbank have not been experimentally decoupled. We conducted the first test of shrubs increasing seedbank densities through direct effects on the seedbank (i.e. shrub seed-trapping, animal-mediated dispersal) and indirect effects by facilitating the annual plant community (i.e. seed deposition, annual seed-trapping). Two distinct desert ecosystems were used to contrast transient seedbank densities in shrub and open microsites by manipulating annual plant density and the presence of the persistent seedbank. We measured transient seedbank densities at the end of the growing season by collecting soil samples and extracting seeds from each respective treatment. Transient seedbank densities were greatest in shrub canopies and with relatively higher annual plant densities. The persistent seedbank contributed to transient seedbank densities only in one desert and in the open microsite. Shrubs indirectly increased seedbank densities by facilitation the seed production of the annual plants. Therefore, shrubs are increasing seedbank independently of the annual plant community, likely through trapping effects, and dependently by facilitating seed production of the annuals. These findings provide evidence for a previously undescribed mechanism that supports annual seedbanks and thus desert biodiversity. We also identify shrubs as being significant drivers of desert plant communities and emphasize the need to consider multiple mechanisms to improve our ability to predict the response of ecosystems to change.York University Librarie

    Integrating econimic costs into the analysis of flexible conservation management strategies

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    Flexible conservation management, where measures are selected in each decision period and depending on the current state of the ecological system, are generally perceived as superior to fixed management, where the same measure is applied in each decision period independent of the current state of the system. In past comparisons of fixed and flexible conservation strategies the additional costs that arise only in flexible strategies have usually been ignored. In this paper we present a framework to integrate these 'costs of flexible management' into the evaluation of flexible conservation strategies. Using the example of an endangered butterfly species we demonstrate that the costs of flexible management may reverse the rank order of flexible and fixed conservation strategies, such that fixed strategies may lead to better ecological results than flexible ones for the same financial budget. --conservation,ecological-economic model,extinction,flexible management

    Overlooked examples of cloud self-organization at the mesoscale

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    Stratocumulus clouds are common in the tropical and subtropical marine boundary layer, and understanding these clouds is important due to their significant impact on the earth's radiation budget. Observations show that the marine boundary layer contains complex, but poorly understood processes, which, from time to time, result in the observable self-organization of cloud structures at scales ranging from a few to a few thousand kilometers. Such shallow convective cloud features, typically observed as hexagonal cells, are known generally as mesoscale cellular convection (MCC). Actinoform clouds are rarer, but visually more striking forms of MCC, which possess a radial structure. Because mesoscale cloud features are typically too large to be observed from the ground, observations of hexagonal cells historically date only to the beginning of satellite meteorology. Examples of actinoform clouds were shown in the venerable “Picture of the Month” series in Monthly Weather Review in the early 1960s, but these clouds were generally forgotten as research focused on hexagonal cells. Recent high-resolution satellite images have, in a sense, “rediscovered” actinoform clouds, and they appear to be much more prevalent than had been previously suspected. We show a number of examples of actinoform clouds from a variety of locations worldwide. In addition, we have conducted a detailed case study of an actinoform cloud system using data from the Multiangle Imaging SpectroRadiometer (MISR) and the Geostationary Operational Environmental Satellite (GOES), including analysis of cloud heights, radiative properties, and the time-evolution of the cloud system. We also examine earlier theories regarding actinoform clouds in light of the new satellite data

    Office politics: When managers flatter the CEO, but undermine him with journalists

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    The need to ingratiate themselves with the boss hurts their self-esteem and makes them resentful, find Gareth Keeves, James Westphal and Michael McDonal

    Einfluss von Metall-Cluster auf den photovoltaischen Effekt in organischen DĂĽnnschichtsystemen

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    Ziel der hier vorliegenden Arbeit war es, die Frage zu klaren, ob Plasmonenabsorption in Metallclustem sich positiv auf photovoltaisch aktive Systeme auswirken kann. Als Ansatz diente dabei die Hypothese, dals bei Metallclustern, die in ein elektrisches Feld eingebracht werden, durch Plasmonenresonanzabsorption von Photonen eine gerichtete Ladungstrageremission moglich ist. Hergestellt wurden die Cluster durch Aufdampfen von Silberinselschichten im Vakuum mit anschlieBendem Tempern, so daB gut separierte Cluster mit fast kugelformiger Gestalt entstanden. Eingebettet wurden die Silbercluster dann in photovoltaisch aktive Farbstoffschichten aus Zink-Phthalocyanin und/oder aus Methylsubstituiertem Perylen-Pigment, Als elektrische Kontakte dienten dabei auf dem Glassubstrat transparentes, leitendes Indiumzinnoxid und als Ruckkontakt Silber oder Gold. Die Proben wurden optisch und photoelektrisch untersucht. Es konnte im Rahmen dieser Arbeit gezeigt werden, daB Silbercluster in dem elektrischen Feld eines ITO/ZnPc-Schottky-Kontaktes zur Erhohung des Photostroms in dem Wellenlangenbereich fUhren, bei dem ZnPc eine minimale Absorption besitzt, bei dem aber genau die Plasmonenresonanz der Metallcluster liegt. Zur Erklarung dieses Effektes wurde ein auf Elektronenniveaus beruhendes Energiemodell entwickelt, welches die Moglichkeit zur Erzeugung von Ladungstragerpaaren aufgrund des Zerfalls von Clusterplasmonen in einem elektrischen Feld beschreibt

    Radon als Tracer in der Luftqualitätsüberwachung

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    Die Luftverschmutzung ist weltweit nach wie vor eines der größten Umweltprobleme. Bei der Ursachenanalyse gestaltet es sich als besonders schwierig den höchst variablen Einfluss der meteorologischen Bedingungen auf die Schadstoffkonzentration zu eliminieren (Immission) und damit wirksame Luftreinhaltemaßnahmen zu entwickeln. Mit der vorliegenden Arbeit werden Methoden vorgestellt und diskutiert, die das natürlich vorkommende radioaktive Edelgas Radon als atmosphärischen Tracer nutzen, um den Einfluss der meteorologischen Bedingungen auf die Immissionskonzentration auszuschalten und damit unterschiedliche Schadstoffkonzentrationen objektiv vergleichbar zu machen. Für einen Zeitraum von vier Jahren wurden hierfür an einer Luftgütemessstation des städtischen Hintergrunds die Luftschadstoffe Stickstoffdioxid (NO2) und Feinstaub als PM10 und PM2.5 sowie das radioaktive Edelgas Radon gemessen. Zudem wurden Daten einer verkehrsnahen Station verwendet sowie meteorologische Daten.Air pollution is one of the main environmental problems worldwide. Beside the emission the spread of air pollutants is affected by the shape of the earth surface, the land use and the meteorological conditions of the near surface atmosphere. In this conection the meteorological conditions are very difficult to estimate, because these conditions are a result of the combination of many variables which furthermore change in a short period. With this work are methods presented and discussed which use the naturally occurring noble gas Radon as a tracer in the atmospheric boundary layer. Measured data were analyzed with statistical methods and the Radon-Tracer-Method. For a period of four years there were measured the air pollutants nitrogen dioxide (NO2) and particulate matter (PM10, PM2.5) and the tracer Radon. The measurement took place at an air quality control station in the urban background. Furthermore, there were used data from an urban traffic station at a high frequented main street (hot spot) and meteorological data

    Comparison of an automatic analysis and a manual analysis of conjunctival microcirculation in a sheep model of haemorrhagic shock

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    Life-threatening diseases of critically ill patients are known to derange microcirculation. Automatic analysis of microcirculation would provide a bedside diagnostic tool for microcirculatory disorders and allow immediate therapeutic decisions based upon microcirculation analysis
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