1,720,957 research outputs found
Digital plant pathology: a foundation and guide to modern agriculture
No full textOver the last 20 years, researchers in the field of digital plant pathology have chased the goal to implement sensors, machine learning and new technologies into knowledge-based methods for plant phenotyping and plant protection. However, the application of swiftly developing technologies has posed many challenges. Greenhouse and field applications are complex and differ in their study design requirements. Selecting a sensor type (e.g., thermography or hyperspectral imaging), sensor platform (e.g., rovers, unmanned aerial vehicles, or satellites), and the problem-specific spatial and temporal scale adds to the challenge as all pathosystems are unique and differ in their interactions and symptoms, or lack thereof. Adding host–pathogen–environment interactions across time and space increases the complexity even further. Large data sets are necessary to enable a deeper understanding of these interactions. Therefore, modern machine learning methods are developed to realize the fast data analysis of such complex data sets. This reduces not only human effort but also enables an objective data perusal. Especially deep learning approaches show a high potential to identify probable cohesive parameters during plant-pathogen-environment interactions. Unfortunately, the performance and reliability of developed methods are often doubted by the potential user. Gaining their trust is thus needed for real field applications. Linking biological causes to machine learning features and a clear communication, even for non-experts of such results, is a crucial task that will bridge the gap between theory and praxis of a newly developed application. Therefore, we suggest a global connection of experts and data as the basis for defining a common and goal-oriented research roadmap. Such high interconnectivity will likely increase the chances of swift, successful progress in research and practice. A coordination within international excellence clusters will be useful to reduce redundancy of research while supporting the creation and progress of complementary research. With this review, we would like to discuss past research, achievements, as well as recurring and new challenges. Having such a retrospect available, we will attempt to reveal future challenges and provide a possible direction elevating the next decade of research in digital plant pathology
Anthropogenic impacts on mangrove and saltmarsh communities in eastern Australia
No full textAktuell lebt die Hälfte der Weltbevölkerung in urbanisierten Regionen und es wird erwartet, dass diese bis 2050 um weitere 13 % steigen wird. In Australien leben 85% der Bevölkerung in Küstennähe und durch die global steigende Bevölkerungsdichte sind dadurch auch insbesondere die tidebeeinflussten Feuchtgebiete entlang von Küsten, wie Mangroven und Salzmarsche, stark bedroht. In Südostaustralien nehmen insbesondere Salzmarsche einen empfindlichen Platz entlang des Höhengradienten von Gewässerufern ein. Sie kommen zwischen Mangroven, auf der seewärtigen Seite, und Süßwasservegetation sowie urbaner Bebauung, auf der landwärtigen Seite, vor. Zusätzlich zur landwärtigen Migration von Mangroven und dem steigenden Meeresspiegel, werden Salzmarsche durch abgeleitetes Regenwasser, insbesondere
bei Extremwetterereignissen, bedroht. Das verschmutzte Regenwasser, in dem sich Straßenabfälle, Öl, Benzin und Chemikalien anlagern, wird in vielen Fällen direkt in die Feuchtgebiete geleitet.
Die vorgelegte Dissertation kombiniert verschiedene Forschungsansätze, um auf unterschiedlichen geografischen Skalen den anthropogenen Einfluss auf Salzmarsch-Mangroven Gesellschaften entlang der Südostküste Australiens zu untersuchen. Zunächst untersuchten wir auf lokaler Ebene den Einfluss von kontaminiertem Süßwasser auf die Komposition und Verbreitung von Salzmarsch- und Mangrovengesellschaften. Wir konnten zeigen, dass das Einbringen von kontaminiertem Regenwasser, die Etablierung von exotischen Süßwasserpflanzen entlang der Salzmarsche begünstigt. Das abgeleitete Regenwasser und die dadurch erhöhten
Nährstoffgehalte unterstützen zudem die Ausbreitung von Mangroven. Da die Invasion von Süßwasserpflanzen von der Landseite, und die Mangrovenexpansion von der Seeseite her geschieht, werden die Salzmarschen von beiden Seiten bedrängt. Dies konnte besonders in industrialisierten Gebieten gezeigt werden.
Das zweite Projekt zielte darauf ab, die vorherige Feldstudie unter kontrollierten Bedingungen im Gewächshaus zu überprüfen. Dazu invadierten wir 28 Mesokosmen, bestehend aus nativen Salzmarscharten, mit vier verschiedenen exotischen Süßwasserpflanzen. Die Nährstoffgehalte und der Salzgehalt im Boden wurden den natürlichen Konzentrationen und denen in industriellen Gebieten angepasst. Unsere Ergebnisse zeigten, dass die Etablierung von exotischen Arten unter natürlichen Bedingungen (hoher Salzgehalt und niedriger Nährstoffgehalt) stark eingeschränkt ist. Geringer Salzgehalt im Boden durch Süßwassereintrag erhöhte die Überlebensrate der exotischen Pflanzen signifikant. Erhöhte Nährstoffgehalte führten zwar zu stärkerer Biomasseproduktion, verbesserten allerdings nicht die Überlebensrate.
In einem weiteren Gewächshausexperiment untersuchten wir die Auswirkungen von
erhöhtem CO2 und variierendem Salzgehalt auf das Wachstum von zwei verschiedenen Mangrovenarten. Diese wuchsen zum einen isoliert und zum anderen in Konkurrenz mit einer Salzmarschgesellschaft, bestehend aus drei typischen Salzmarscharten Südostaustraliens. Hohe CO2 Konzentrationen unterstützten sowohl den Mangroven als auch den Salzmarschwuchs.
Klimawandelbedingte Erhöhung von CO2 wird somit die Migration von Mangroven in Salzmarschhabitate erleichtern. Besonders wenn weitere Faktoren, wie Herbivorie und der Anstieg des Meeresspiegels, die Konkurrenzfähigkeit der Salzmarsche reduzieren.
In einer letzten Studie testeten wir auf regionaler Ebene die Ergebnisse aus der ersten
Feldstudie, mit Hilfe von Fernerkundungstechniken. Anhand von Lauftaufnahmen über einen Zeitraum von 42 Jahren untersuchten wir, ob die Veränderungen innerhalb der Feuchtgebietvegetation in stark modifizierten Gewässern beobachtet werden können. Unsere Analyse zeigte, dass weite Bereiche von Salzmarschen seit den 1970er Jahren verloren gegangen sind. Im Gegensatz dazu, hat die Fläche von Casuarina spp. und Melaleuca spp. Pflanzengemeinschaften stark zugenommen, was uns vermuten lässt, dass diese von der Landseite aus in die Salzmarsche migrierten. Jedoch konnten wir anhand der Anzahl der Bilder, den Verlust von Salzmarsche durch Mangroven Migration nicht belegen.
Tidebeeinflusste Feuchtgebiete gelten in der Regel nicht als durch Süßwasserpflanzen
invasionsanfällige Ӧkosysteme. Wir konnten jedoch zeigen, dass die Einengung der Salzmarsche, in unmittelbarer Nähe zu urbanen Gebieten, von Mangroven auf der Seeseite und von exotischen Pflanzen auf der Landseite durch Abwassereinleitung verschlimmert wird. Dieser Trend ist besonders stark entlang industrialisierten Ästuaren durch den erhöhten Süßwasserund Nährstoffeintrag. Auch einheimische Süßwasserpflanzen, die natürlich am Rand der Salzmarschzone vorkommen, scheinen über die letzten 42 Jahre stark vom Frischwassereintrag profitiert zu haben. Dieser Trend ist besonders stark entlang industrialisierten Ästuaren durch den erhöhten Süßwasser- und Nährstoffeintrag. Managementstrategien, wie bepflanzte Pufferzonen und Bildungsprogramme, die zum Beispiel auf eine Verminderung des Nährstoffeintrages hinzielen, werden dringend benötigt. Wenn die Verdrängung der Salzmarsche nicht vermindert wird gehen nicht nur Lebensräume für viele Tierarten verloren, sondern auch wichtige ökosystematische Dienstleistungen, die uns Menschen betreffen.Currently, half of the global population is living in urban areas and it is expected to
rapidly grow by 13% until 2050. In Australia, 85% of its population lives within 50 km of the coastline. Population growth will strongly impact intertidal coastal wetlands, such as mangroves and saltmarshes. In particular saltmarshes occur in a vulnerable position between mangroves on the seaward side and freshwater plants and human development on the landward side. Saltmarshes are facing threats from rising sea level, landward migration of mangroves, and in urban regions, from stormwater run-offs carrying litter, nutrients, oil, petrol and agrochemicals.
This thesis used various approaches to examine the anthropogenic effects on the mangrove and saltmarsh communities of south-east Australia. First on a local scale, where we investigated the impact of polluted urban stormwater on saltmarsh and mangrove species composition and distribution. We showed that stormwater facilitates the growth of exotic freshwater plants into saltmarsh vegetation downslope of stormwater outlets and the expansion of mangroves into saltmarsh vegetation from the seaward side. This results in a squeezing effect on the saltmarshes that occur between urban development and mangrove forest. This effect was found to be strongest in industrialised areas.
In a second study, we aimed to validate our findings of the field study in a controlled
greenhouse experiment. We established 28 mesocosms containing a mixture of native saltmarsh community and invaded them with four different exotic plant seedlings. The nutrient and salinity levels were adjusted according to those found in natural and industrial areas. Our findings suggest that under natural conditions of saltmarsh habitat (high salinity-low nutrients), the establishment of exotic plant seedlings is restricted. Lower salinity through freshwater input increased the survival of invading exotic species significantly. Additional nutrients increased biomass production but not necessarily survival of exotics.
In another glasshouse experiment, we investigated the effect of elevated CO2 and
changes in salinity on seedling growth of two mangrove species grown individually and in a model saltmarsh community. Elevated CO2 promoted mangrove and saltmarsh growth. It can be assumed that under rising CO2, mostly caused by anthropogenic climate change, mangrove encroachment into saltmarshes will be facilitated. Especially if other disturbing factors, such as herbivory or rising sea level, will reduce the competition effect of saltmarshes.
Finally, at the regional scale, we used a remote sensing approach to assess if the changes in vegetation pattern, observed in our field study (Chapter 2), can be detected in aerial images of extremely modified catchments over a 42-year period. Our analysis showed that large areas of saltmarshes have been lost since 1970. By contrast, saltmarsh fringing Casuarina and Melaleuca communities greatly increased, indicating seaward encroachment into saltmarsh communities. However, based on the number of our imagery, the loss of saltmarsh could not be associated with mangrove expansion.
While intertidal coastal wetlands are generally not considered as threatened through
species invasion, due to their adaptation to saline environments, we showed that urban saltmarshes are indeed threatened by a squeezing effect from the seaward side by mangroves and from the landward side by exotic plants and freshwater plants. This trend is particularly threatening with high disturbances in industrialised estuaries by freshwater and nutrient input. Management strategies, such as buffer zones and educational programs to foster the avoidance of overfertilization, are needed to avoid the freshening of intertidal wetlands in proximity to urban development. Further squeezing of saltmarsh communities in urban areas will lead to its destruction and thus to a loss of important habitat as well as ecosystem services they provide to
us humans
An applied framework to unlocking multi-angular UAV reflectance data : a case study for classification of plant parameters in maize (Zea mays)
No full textOptical sensors, mounted on uncrewed aerial vehicles (UAVs), are typically pointed straight downward to simplify structure-from-motion and image processing. High horizontal and vertical image overlap during UAV missions effectively leads to each object being measured from a range of different view angles, resulting in a rich multi-angular reflectance dataset. We propose a method to extract reflectance data, and their associated distinct view zenith angles (VZA) and view azimuth angles (VAA), from UAV-mounted optical cameras; enhancing plant parameter classification compared to standard orthomosaic reflectance retrieval. A standard (nadir) and a multi-angular, 10-band multispectral dataset was collected for maize using a UAV on two different days. Reflectance data was grouped by VZA and VAA (on average 2594 spectra/plot/day for the multi-angular data and 890 spectra/plot/day for nadir flights only, 13 spectra/plot/day for a standard orthomosaic), serving as predictor variables for leaf chlorophyll content (LCC), leaf area index (LAI), green leaf area index (GLAI), and nitrogen balanced index (NBI) classification. Results consistently showed higher accuracy using grouped VZA/VAA reflectance compared to the standard orthomosaic data. Pooling all reflectance values across viewing directions did not yield satisfactory results. Performing multiple flights to obtain a multi-angular dataset did not improve performance over a multi-angular dataset obtained from a single nadir flight, highlighting its sufficiency. Our openly shared code (https://github.com/ReneHeim/proj_on_uav) facilitates access to reflectance data from pre-defined VZA/VAA groups, benefiting cross-disciplinary and agriculture scientists in harnessing the potential of multi-angular datasets
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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