Geomorphic Response to Environmental Change : The Imprint of Deforestation and Agricultural Land Use on the Contemporary Landscape of the Pleiser Hügelland, Bonn, Germany

Central Europe has in many areas been subjected to continuous agricultural land use for several millennia. Deforestation and the introduction of agriculture to a previously undisturbed environment was not only a perturbation to the physical landscape system, but a shift to a qualitatively different landscape system. Within this landscape the production and redistribution of sediment has had consequences for the morphological development of the landscape. Furthermore, it has important implications for the sustainability of land use, for the design of engineering infrastructure, for contamination of waters and aquatic environments through sediment itself and as a result of associated particulate fluxes, for landform development, and for prognoses of all of these phenomena under changing climate and land use scenarios. Of particular interest, therefore, is a greater understanding of the relative significance of climatic and anthropogenic influences on the behaviour of geomorphic systems. This is important as we attempt to manage our activities so as to avoid, or at least minimise, adverse impacts on the landscape. This study deals with issues relating to geomorphic responses to environmental change. Investigations into late Holocene colluviation took place in the Pleiser Hügelland, a region of predominantly agricultural loess-covered hill country to the east of Bonn. Widespread deforestation occurred in this area in the early to middle Medieval period, and on isolated sites probably during the Iron Age or earlier. The agricultural land use which followed this deforestation introduced a new mechanism for the generation and redistribution of sediment throughout the landscape, i.e. tillage. Colluvial sediments are principally derived from loess and loess soils, but to an extent also from basalt, trachyt and Pleistocene alluvium. This investigation has sought to characterise the geomorphic response to this environmental change. Investigation took place in three separate study areas that represent landform elements of different hierarchical magnitude: zero-, first- and second-order drainage basins. Rates of sediment redistribution in the Auf dem Scheid catchment for the last 45 years have been modelled on the basis of 120 samples of 137Cs concentration. This indicates that for this period greater rates of sediment redistribution have occurred on arable land than on pasture. The two arable zones are net sediment export areas, with high sediment delivery ratios (88%, 77%), while the pasture zone is a net accumulation area (-23%). Furthermore, modelling the effects of two different process types highlights the way in which their interaction contributes to the sediment flux. High frequency/low magnitude tillage prepares sediment for further transport by water erosion processes. There is thus a constant supply of material for sediment redistribution. Water erosion is also the mechanism by which sediment is exported beyond the boundaries of arable areas. An attempt was made to develop a high resolution late Holocene sedimentation chronology in the Auf dem Scheid catchment using Optically Stimulated Luminescence (OSL) dating. Because of the mineral composition of the sediments in Auf dem Scheid, only limited success was achieved, and a high resolution chronology was not possible. Nevertheless, a considerable body of chronological information for colluvial sedimentation in a small area has been acquired. This and the stratigraphic information revealed during sample recovery indicates a rather complex history for the small (~5.4 ha) Auf dem Scheid catchment. At least four different phases of erosion-deposition can be inferred on the basis of OSL ages. The earliest of these is from sediments dated at ~4,400 a. The greatest rates of accumulation are associated with a Medieval event, which may be correlated with widely reported episode of catastrophic gullying. A long term sediment budget gives an estimated sediment delivery ratio of 74%. However, when it is recognised that many of the sediments associated with earlier erosional phases have been themselves eroded and exported in the meantime, this sediment delivery ratio can be considered to be an overestimate. In the absence of high magnitude events, further reworking of colluvial sediments stored in the Auf dem Scheid catchment is unlikely. Thus, although there is a reasonably efficient mid- to long term coupling of source and sink within the Auf dem Scheid, the external coupling is weak and Auf dem Scheid can be considered to be a closed system. OSL ages were also acquired from the fill of two fossil gullies in a single slope study area in the nearby Forstbach catchment. They have been filled with sediments eroded from the formerly agricultural slopes. The ages of gully fill indicate that these features are ~1,300 years old. In general, the ages of colluvia in the both Auf dem Scheid and Forstbach give evidence of considerable erosional activity occurring at a considerably earlier period than had previously been thought. An inference is that deforestation and the introduction of agriculture may have occurred much earlier than has previously been thought in at least this part of the Pleiser Hügelland. Further, both study sites are dominated by the evidence of agricultural processes. Although gullying associated with large scale rainfall-runoff has occurred in both, there is no evidence of this in the contemporary landscape. Thus, expressed in terms of transient form ratios, both are considered insensitive to gullying, but sensitive to low magnitude diffusive erosional processes. Stratigraphic evidence of process behaviour was derived on the basis of a series of core transects in the Heidersiefen basin (2nd order). Large volumes of agriculturally initiated sediment are also present in this area. A long term sediment budget (FEISE 1999) indicated relatively low sediment delivery ratios (~30%) for first and second order drainage basins. However, construction of infrastructure in more recent times has caused a decoupling of sediment source areas from channel deposition sites, and sediment delivery within the Heidersiefen catchment has been reduced. This has influenced the geomorphic effectiveness of rainfall-runoff, which is capable of eroding in-channel sediment storage in even relatively low magnitude events. The presence of a perennial channel means that the sediments in storage in Heidersiefen are more susceptible to reworking than those in Auf dem Scheid or the Forstbach study site. Thus, more than the other study sites, Heidersiefen does not exhibit the same sensitivity to agricultural land use. The two principal processes of sediment generation and redistribution that operate within this landscape (tillage and rainfall-runoff) are markedly different with respect to their frequency/magnitude/effectiveness. Tillage occurs with high frequency, i.e. on a regular basis, 2-3 times per year. Tillage is a very effective transport mechanism in terms of the volume of material it moves over longer periods, but its effects remain localised as transport is only over very small distances. More significantly, tillage increases the susceptibility of soils to water erosion processes. There is greater variability in the frequency/magnitude/effectiveness of rainfall-runoff events. Those with sufficient energy to erode and transport some small amount of sediment (i.e. through overland flow and rilling) probably occur at least as frequently as tillage. These events are able to transport small amounts of material over small distances. But those with sufficient energy to cause gullying - and thus potentially the erosion and transport of volumes of material comparable with a single ploughing operation - are considerably less frequent. Not only does the magnitude of rainfall-runoff influence the amount of material moved, it also determines the distance of transport. The effects of small magnitude events remain relatively localised, just as with ploughing. Sediment may simply remain within the field and be reincorporated into the plough horizon with the next ploughing operation; or it may be transported to a local depositional zone. At the other extreme, gullies generated by high magnitude rainfall-runoff events are potentially capable of transporting sediment out of the system entirely. The relative frequency of rainfall-runoff events of varying magnitude, and their temporal sequence, is thus an important aspect in determining the pattern of sediment generation and redistribution. There is evidence that high magnitude rainfall-runoff events have formed gullies. However, the age of these features - as revealed by the luminescence-derived ages of their fills - indicates that this has not happened very frequently. In the intervening period between the recurrence of high magnitude events, their morphological effects have been removed by the sediment generated by smaller events. Of equal importance are configurational aspects of the landscape system. These relate to the spatial distribution of the individual process domains, both relative to each other and within the landscape system. It also relates to the spatial distribution of sediment sources/sinks and of the different components of the system hierarchy, and importantly the extent to which (a) sources and sinks and (b) systematic elements are coupled. This is influenced by both the magnitude of each of these elements, and by the energy available for transporting material from one element to the next. The principal geomorphic response to environmental change has been the generation of large amounts of sediment through (a) initial deforestation and (b) the subsequent effects of tillage and rainfall-runoff processes. However, the low levels of energy available for transport of this sediment - due to both low relief and a low frequency of high energy rainfall events - and sometimes weak coupling between components of the sediment flux have restricted the amount of sediment entering the regional sediment flux. The post-deforestation, agricultural landscape can thus be characterised with a transport limited sediment flux. This contrasts with a generally assumed stable pre-deforestation landscape which exhibited low rates of process behaviour and therefore a supply limited sediment flux.Viele Regionen Mitteleuropas werden seit einigen Jahrtausenden durch kontinuierliche Ackernutzung geprägt. Entwaldung und die Einführung der Landwirtschaft in eine zuvor unberührte Umwelt bedeutete nicht nur die Störung des physischen Systems der Landschaft, sondern auch den Übergang in ein Landschaftssystem neuer Prägung. Innerhalb dieser Landschaft hatte die Produktion und Umlagerung von Sediment Auswirkungen auf die morphologische Entwicklung der Landschaft. Darüber hinaus ist der Eingriff bedeutungsvoll bezüglich die Nachhaltigkeit der Landnutzung, den Bau infrastruktureller Einrichtungen, bezüglich der Verunreinigung von Wasser und Wasserreservoirs durch das Sediment selbst und durch den damit verbundenem Stofftransport, bezüglich der Landschaftsentwicklung und der Vorhersage all dieser Erscheinungen unter sich ändernden Landnutzungs- und Klimaszenarien. Es ist daher von besonderem Interesse, klimatische und anthropogene Einflüsse in ihrer relativen Bedeutung für das Verhalten der geomorphologischen Systeme besser zu verstehen. Dieses Verstehen ist besonders dann wichtig, wenn wir versuchen, unsere Aktivitäten so zu steuern, dass Eingriffe vermieden oder zumindest reduziert werden. Diese Untersuchung beschäftigt sich Themen, die sich auf die Reaktion des geomorphologischen Systems auf Umweltveränderungen beziehen. Gegenstand sind spät-holozäne Kolluvien, die hauptsächlich aus Löss, aber auch aus Basalt, Trachyttuff und Schotter hervorgegangen sind. Die Untersuchungen haben in der überwiegend landwirtschaftlich genutzten Region des Pleiser Hügelland östlich von Bonn stattgefunden. Die Rodung in diesem Gebietes begann im frühen bis mittleren Mittelalter, an einigen Stellen vermutlich bereits während der Eisenzeit oder früher. Die darauffolgende Ackernutzung führte mit dem Pflügen einen neuen Prozess der Sedimentmobilisierung und -umverteilung innerhalb der Landschaft ein. Die vorliegende Untersuchung ist darauf ausgerichtet, die Reaktionen der beteiligten geomorphologischen Einheiten auf diese Umweltveränderung zu charakterisieren. Die Arbeiten wurden in drei räumlich getrennten Untersuchungsgebieten durchgeführt, die Landschaftselemente unterschiedlicher hierarchischer Ordnung repräsentieren: Einzugsgebiete nullter ("Forstbach", 0,9 ha), erster ("Auf dem Scheid", ~5.4 ha) und zweiter Ordnung ("Heidersiefen", ~14 ha). Auf Basis von 137Cs Konzentration im Oberboden wurden die Sedimentumverteilungsraten im Einzugsgebiet "Auf dem Scheid" für die letzten 45 Jahre modelliert. Diese zeigen, daß die Sedimentumlagerung auf Ackerland jene auf Grünland bedeutend überstiegen hat. Es gibt zwei Ackerlandzonen, die Netto-Sedimentaustragsgebiete mit hohen Sedimentaustragsraten (88%, 77%) sind, während die Grünland-Zone mit einer Sedimentaustragsrate von -23% ein Netto-Akkumulationsgebiet darstellt. Weiterhin konnte durch den Einsatz numerischer Modelle veranschaulicht werden, in welcher Weise die beiden Prozesstypen Pflügen und Wassererosion zum Sedimenttransfer beitragen. Mit hoher Frequenz und geringer Magnitude stellt Pflügen Sediment für den Weitertransport durch Wassererosionsprozesse bereitet. Somit steht zu jedem Zeitpunkt Sediment für die Umverteilung zur Verfügung. Wassererosion hingegen ist der Prozeß, der Sediment über die Feldgrenzen hinweg transportiert. Mit der Datierungsmethode der Optisch Stimulierten Lumineszenz (OSL) wurde versucht, eine hochauflösende Chronologie für die spät-holozänen Sedimente im Einzugsgebiet 'Auf dem Scheid' zu erstellen. Aufgrund der Mineralzusammensetzung der Sedimente, war dies nur in begrenzt erfolgreich und eine hochauflösende Chronologie konnte nicht erstellt werden. Trotzdem konnte eine beachtliche Menge chronologischer Informationen zur Kolluvienbildung zusammengetragen werden, die zusammen mit den stratigraphischen Befunden, ein komplexes Bild für die Entwicklung des kleinen Einzugsgebiets ergeben. Mindestens vier Erosions- bzw. Akkumulations-Phasen können auf der Grundlage der OSL-Alter identifiziert werden. Die älteste wird durch Sedimente repräsentiert, die etwa 4,400 a alt sind. Die höchsten Akkumulationsraten gehen auf mittelalterliche Ereignisse zurück, die mit mehrfach beschriebenen Perioden katastrophalen Schluchtenreißens korreliert werde können. Eine Abschätzung der holozänen Sedimentbilanz ergibt ein Sedimentaustragsverhältnis von 74%. Dieser Wert sollte jedoch als Maximalwert angesehen werden, da ein Großteil der Sedimente aus früheren Erosionsphasen in der Zwischenzeit erodiert und ausgeräumt wurden. Eine weitere Umverteilung von kolluvialem Material im Einzugsgebiet Auf dem Scheid ist lediglich durch Ereignisse hoher Magnitude zu erwarten. Daher ist trotz der eher effizienten mittel- bis langfristigen Kopplung von Quellen und Senken innerhalb des Einzugsgebiets die externe Ankopplung schwach und das Gebiet Auf dem Scheid kann als ein geschlossenes System angesehen werden. Innerhalb des nahegelegenen Einzugsgebietes 'Forstbach' wurden an einem Einzelhang die Sedimentfüllungen zweier fossiler Gräben untersucht und mit OSL datiert. Die Sedimente sind Korrelate früherer landwirtschaftlicher Nutzung der angrenzenden Hänge. Ihre Akkumulation begann vor etwa 1,300 Jahren. Die Alter der Kolluvien, sowohl von Auf dem Scheid als auch von Forstbach, weisen auf eine beachtliche Erosionsaktivität hin, die erheblich früher stattgefunden hat als bislang angenommen. Daher muß geschlossen werden, daß die Abholzung und die Einführung des Ackerbaus sehr viel früher erfolgte, als für diesen Teil des Pleiser Hügellandes bisher angenommen wurde. Beide Untersuchungsgebiete sind dominiert von den Auswirkungen landwirtschaftlicher Prozesse. Obwohl in beiden Einzugsgebieten das mit großen Niederschlags-/Erosionsereignissen einhergehende Schluchtenreissen stattgefunden hat, gibt es hierfür an der heutigen Landschaftsoberfläche keine Hinweise. Bezüglich der "transient form ratios" müssen deshalb beide Untersuchungsgebiete als insensitiv für Schluchtenreissen bezeichnet werden. Hingegen sind beide aber als sensitiv für diffuse Erosionsprozesse mit geringer Magnitude einzustufen. Stratigraphische Befunde für das Prozeßverhalten wurden aus einer Reihe von Catenen im Heidersiefen Einzugsgebiet (2. Ordnung) gewonnen. Auch hier sind große Mengen landwirtschaftlich verursachten Sediments vorhanden. Eine langfristige Sedimentbilanz (FEISE 1999) erbrachte mit ~30% eine relativ niedrige Sedimentaustragsrate für Einzugsgebiete erster und zweiter Ordnung. Allerdings wurden durch den Bau von Infrastruktur in jüngerer Zeit die Sedimentquellen von den Sedimentspeichern am Gerinne entkoppelt und der Sedimentaustrag reduziert. Dies beeinflußte auch die geomorphologische Wirksamkeit von Niederschlags/Abflussereignissen, die bereits bei geringer Magnitude zur Erosion von Sediment im Gerinne führen. Das perennierende Gerinne bedeutet für das Heidersiefen-Gebiet, dass die darin gespeicherten Sedimente gegenüber Aufarbeitung anfälliger sind als jene im Gebiet Auf dem Scheid. Verglichen mit den anderen Untersuchungsgebieten ist Heidersiefen daher weniger sensitiv für ackerbaulicher Nutzung. Die beiden Hauptprozesse der Bodenerosion und -umverteilung, die in dieser Landschaft wirksam sind (Pflügen und Wassererosion) unterscheiden sich sehr stark in ihrer Frequenz/Magnitude/Effektivität. Das Pflügen geschieht mit hoher Frequenz, d.h. in regelmäßigen Abständen 2-3 mal pro Jahr, womit über längere Zeiträume große Volumina bewegen werden. Die Auswirkung des Pflügens bleibt jedoch lokal begrenzt, da der Transport nur über geringe Distanzen hinweg erfolgt. Entscheidender jedoch ist, dass Pflügen die Anfälligkeit des Bodens für Wassererosion erhöht. Die Variabilität der Frequenz/Magnitude/Effektivität bei Niederschlags/Abflussereignissen ist höher. Niederschlagsereignisse deren Energie für Erosion und Transport geringer Bodenmengen ausreichend ist (das heißt durch Oberflächenerosion und Rillenerosion), treten wahrscheinlich mindestens so häufig auf wie das Pflügen des Ackers. Diese Ereignisse können geringe Mengen Bodenmaterial über kurze Distanzen transportieren. Dagegen sind solche Niederschlagsereignisse erheblich seltener, die genügend Energie zur Erzeugung von Rinnen haben und damit eine Sedimentumverteilung vergleichbar der eines einzigen Pflügens bewirken. Die Stärke des Niederschlages beeinflußt nicht nur die Menge des erodierten Materials, sondern auch die Transportstrecke. Die Auswirkungen von schwachen Niederschlagsereignissen bleiben auf einen relativ kleinen Raum beschränkt, wie auch die des Pflügens. Das erodierte Bodenmaterial verbleibt auf dem Feld und wird mit dem nächsten Pflügen wieder in den Pflughorizont eingearbeitet oder in örtlichen Ablagerungszonen gespeichert. Das andere Extrem sind Rinnen und Gräben, die durch Starkregenereignisse entstehen, und die potentiell fähig sind, Sediment aus dem Gesamtsystem hinaus zu transportieren. Die relative Häufigkeit von Niederschlagsereignissen unterschiedlicher Stärke und deren zeitliche Abfolge, ist daher ein wichtiger Aspekt bei der Bestimmung von Mustern der Sedimentbildung und Sedimentverteilung. Es gibt Hinweise dafür, dass durch Starkregen/-abflussereignisse Gullies geformt wurden. Jedoch spricht das Alter dieser Formen - wie durch die OSL-Alter der Füllungen erwiesen - dafür, dass dies nicht sehr häufig geschehen ist. In den Zeiträumen zwischen dem Auftreten dieser Starkregenereignisse, sind ihre geomorphologischen Auswirkungen durch Sedimente beseitigt worden, die von kleinen Ereignissen stammen. Von ähnlicher Bedeutung sind Aspekte der räumlichen Anordnung des Landschaftssystems. Diese betreffen die Verteilung der einzelnen Prozeßdomänen, sowohl relativ zu einander als auch innerhalb des Landschaftssystems. Sie beziehen sich auf die räumliche Verteilung der Sedimentquellen und -senken und auf die verschiedenen Komponenten der Systemhierarchien, wie auch auf das Ausmaß der Kopplung von a) Quellen und Senken und b) einzelnen Systemkomponenten. Dies wird beeinflußt von der Größe jedes einzelnen Elements, wie auch der vorhandenen Energie für den Materialtransport von einem zum nächsten Element. Die grundlegende geomorphologische Reaktion auf eine Umweltveränderung war die Erzeugung von großen Sedimentmengen durch a) die erstmalige Abholzung und b) die nachfolgenden Auswirkungen von Pflügen und Niederschlag/Abfluss-Prozessen. Jedoch hat das geringe zum Sedimenttransport zur Verfügung stehende Energieniveau die Menge an Sediment, das in den regionalen Sedimenttransfer eingebracht wird, begrenzt. Dies liegt sowohl an den geringen Hangneigungen und der geringen Häufigkeit von Starkregenereignisse, als auch an der schwachen Kopplung einzelner Komponenten des Sedimenttransfers. Die entwaldete und agrarisch genutzte Landschaft ist deshalb durch einen transportbegrenzten Sedimenttransfer charakterisiert. Sie hebt sich von der ursprünglichen Waldlandschaft ab, deren Zustand allgemein als stabil angenommen wird und die sich durch geomorphologische Stabilität und einen nachschubbegrenzten Sedimenttransfer auszeichnet

Efficacy of a Series of Alkylammonium Compounds Against Wood Decay Fungi and Termites

The efficacy of four alkylammonium compounds was determined for eight common wood decay fungi and Reticulitermes sp. termites in laboratory tests. All of the compounds tested were found to be effective against both fungi and termites, but only dialkyldimethylammonium chloride was fully effective against all of the brown- and white-rot fungi tested in this study. On the basis of this and other studies, it is concluded that some of the alkylammonium compounds are satisfactory wood preservatives for the treatment of softwoods used in out-of-ground contact applications. More extensive field studies will be required before their potential as ground contact wood preservatives can be determined

Integration of Hydrogen Technology into Large Scale Industrial Manufacturing in Ontario

Power-to-Gas is particularly applicable in Ontario’s energy market, due to the abundance of curtailed renewable energy. During off peak hours this results in not only low carbon, but low-cost electricity making hydrogen generation a highly profitable and environmentally friendly venture. Despite the benefits listed above, there has yet to be a full-scale adoption of Power-to-Gas technology both globally and in the local market. This eliminate this hesitation there is a requirement for diverse, profitable proof of concept installations and a public uncertainty regarding the inherent safety of the technology. It is the objective of this thesis to address these concerns by demonstrating the versatility of hydrogen in different energy system configurations, to show how layered revenue streams can produce profits in the face of policy uncertainty and by outlining the risks and control methods available to mitigate the safety concerns associated with Hydrogen. The first paper presented in this thesis will address the question of whether a business case with strong financial returns is possible for a finished goods manufacture. Here we demonstrate the potential to capitalize on multiple revenue streams under a single investment and highlight some of the ancillary assets including reduction in air pollution and balance of the electrical grid. This design was developed for an automotive manufacturer requiring a total capital investment of $2,620,448 and resulting in a payback period of 2.8 years. Based on a sensitivity analysis, the annual revenue for selling hydrogen at$1.5 to $12 per kgH2 can sum to$54,741 to $437,928. In the modelled carbon tax program, CO2 allowances can be sold at$18 to $30 per tonne CO2 and the model predicts a CO2 offset of 2359.7 tonnes. The second paper develops a case study that further expands on the use of a single pathway, the is the use of hydrogen enriched natural gas. This paper analyzes the integration of an electrolyzer unit into a manufacturer’s CHP microgrid and both explores the impact a carbon tax has on its feasibility and carries out a failure mode and effects analysis to highlight the safe nature of the technology. Currently realizable capital incentives can see IRRs as high as 13.76$750,000. To realize financial feasibility, the carbon price in Ontario must achieve or exceed a minimum of 60$/ton CO2e. In all economically feasible, cases the system operating under an optimal storage coefficient and operational limit produced an emission offset greater than 3000-ton CO2 per year

Does the use of home-based assistive rehabilitation technology enhance the functional benefits of botulinum toxin in children with cerebral palsy who have upper limb movement difficulties: a single-blind randomised controlled trial.

Background. Spastic cerebral palsy is a common cause of childhood activity limitation that restricts children’s personal development. Botulinum toxin is a spasticity treatment that can improve upper limb activity limitation when combined with rehabilitation therapy. We investigated whether use of a computer-assisted arm rehabilitation (CAAR) device enhanced the benefits of botulinum toxin treatment of the upper limb of children with cerebral palsy. Method. Fifteen children with cerebral palsy aged 5 – 12 years old undergoing botulinum toxin treatment for spasticity of the upper limb were randomly allocated into a CAAR group and a control group using minimisation, a procedure that balances groups for prognostic factors e.g. age and disability. Children used CAAR at home for 6 weeks. Assessments were carried out by blinded assessor at baseline, six and twelve weeks. Primary outcome measure. ABILHAND-kids. Secondary outcome measure. Canadian Occupational Performance Measure (COPM). Results. ABILHAND-kids. Activity limitation worsened following botulinum toxin treatment. An ANCOVA revealed that this was not significant (median scores, all participants: baseline, 0.8084; six weeks, 0.145; twelve weeks, 0.334; p=0.462) and that there was no difference between groups (p=0.699). COPM. A Friedman’s ANOVA revealed a statistically significant improvement that was clinically non-significant (baseline score, 4/10; six week score, 4.6/10; twelve week score, 4.6/10; p=0.031). A Kruskal-Wallis ANOVA revealed no difference in scores between groups at each time point. CAAR use. Mean daily use, 7 minutes. Maximum use, 256 minutes (played over 24 days, mean daily use 10.667 minutes). Sample size. This sample size was underpowered by 75%. Conclusion. This study potentially supports evidence that botulinum treatment should be used only in combination with rehabilitation therapy but it was not adequately powered and a Type II error cannot be ruled out. The CAAR device did not engage the children enough to promote sufficient intensity and repetition of arm movements

Enabling Topological Planning with Monocular Vision

Topological strategies for navigation meaningfully reduce the space of possible actions available to a robot, allowing use of heuristic priors or learning to enable computationally efficient, intelligent planning. The challenges in estimating structure with monocular SLAM in low texture or highly cluttered environments have precluded its use for topological planning in the past. We propose a robust sparse map representation that can be built with monocular vision and overcomes these shortcomings. Using a learned sensor, we estimate high-level structure of an environment from streaming images by detecting sparse vertices (e.g., boundaries of walls) and reasoning about the structure between them. We also estimate the known free space in our map, a necessary feature for planning through previously unknown environments. We show that our mapping technique can be used on real data and is sufficient for planning and exploration in simulated multi-agent search and learned subgoal planning applications.Comment: 7 pages (6 for content + 1 for references), 5 figures. Accepted to the 2020 IEEE International Conference on Robotics and Automatio

Social Event Detection via sparse multi-modal feature selection and incremental density based clustering

Combining items from social media streams, such as Flickr photos and Twitter tweets, into meaningful groups can help users contextu- alise and effectively consume the torrents of information now made available on the social web. This task is made challenging due to the scale of the streams and the inherently multimodal nature of the information to be contextualised. We present a methodology which approaches social event detection as a multi-modal clustering task. We address the various challenges of this task: the selection of the features used to compare items to one another; the construction of a single sparse affinity matrix; combining the features; relative importance of features; and clustering techniques which produce meaningful item groups whilst scaling to cluster large numbers of items. In our best tested configuration we achieve an F1 score of 0.94, showing that a good compromise between precision and recall of clusters can be achieved using our technique

Effective use of microbial biomass products to facilitate the complete replacement of fishery resources in diets for the black tiger shrimp, Penaeus monodon

A series of experiments were conducted with black tiger shrimp (Penaeus monodon) juveniles to firstly determine the effects of reducing fishmeal inclusion in a diet and then to evaluate the potential for a microbial bioactive to support complete replacement of both fishmeal and fish oil in feeds when fed under clear-water and green-water conditions. The isoproteic and isoenergetic replacement of fishmeal resulted in a consistent decline in growth performance indicating that at every decrease in fishmeal below an inclusion level of 45% there was a decline in performance. In a subsequent trial undertaken in a clear-water tank system diets devoid of both fishmeal and fish oil fed to shrimp were demonstrated to produce poorer performance than a fishmeal and fish oil reference diet. However the addition of a microbial bioactive to the diet resulted in not only a compensation for the replacement of these ingredients but also additional growth. Replication of the clear-water trial in a green-water tank system not only produced similar results, but also showed that the green-water system largely compensated for the performance lost through replacement of fishmeal and fish oil. However it was also shown that the use of the microbial bioactive in the diets still resulted in improved growth performance of shrimp. This study has effectively demonstrated a viable strategy for not only a complete replacement of all fishery products in shrimp diets, but also an improved performance strategy. © 2014

Identification of genes involved in reproduction and lipid pathway metabolism in wild and domesticated shrimps

The aims of this study were to identify genes involved in reproduction and lipid pathway metabolism in Penaeus monodon and correlate their expression with reproductive performance. Samples of the hepatopancreas and ovaries were obtained from a previous study of the reproductive performance of wild and domesticated P. monodon broodstock. Total mRNA from the domesticated broodstock was used to create two next generation sequencing cDNA libraries enabling the identification of 11 orthologs of key genes in reproductive and nutritional metabolic pathways in P. monodon. These were identified from the library of de novo assembled contigs, including the description of 6 newly identified genes. Quantitative RT-PCR of these genes in the hepatopancreas prior to spawning showed that the domesticated mature females significantly showed higher expression of the Pm Elovl4, Pm COX and Pm SUMO genes. The ovaries of domesticated females had a significantly decreased expression of the Pm Elovl4 genes. In the ovaries of newly spawned females, a significant correlation was observed between hepatosomatic index and the expression of Pm FABP and also between total lipid content and the expression of Pm CYP4. Although not significant, the highest levels of correlation were found between relative fecundity and Pm CRP and Pm CYP4 expression, and between hatching rate and Pm Nvd and Pm RXR expression. This study reports the discovery of genes involved in lipid synthesis, steroid biosynthesis and reproduction in P. monodon. These results indicate that genes encoding enzymes involved in lipid metabolism pathways might be potential biomarkers to assess reproductive performance.&nbsp