5,217 research outputs found

    The Adirondack Chronology

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    The Adirondack Chronology is intended to be a useful resource for researchers and others interested in the Adirondacks and Adirondack history.https://digitalworks.union.edu/arlpublications/1000/thumbnail.jp

    OberflĂ€chenemittierende Laser mit vertikaler KavitĂ€t (VCSELs) und VCSEL-Arrays fĂŒr Kommunikation und Sensorik

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    Future generations of optical wireless communication and sensing systems require compact, low-cost, reliable, and highly efficient light sources capable of transmitting modulated beams across free space at gigabit per second (Gbps) data rates and pulsed beams with sub-nanosecond rise and fall times. The infrared vertical cavity surface emitting laser (VCSEL) is exactly one such light source. Fifth generation (5G) systems promise to connect billions of people and trillions of Internet of Things gadgets and sensors at 1 to beyond 20 Gbps via newly auctioned millimeter wave (30 GHz to 300 GHz) spectral bands. By circa 2030 sixth generation (6G) systems envision vast broadband capacity with zero latency – enabling real-time virtual and mixed realities, human-machine interfaces, autonomous vehicles, and much more. The 6G technology adds terahertz wave emitters including infrared VCSELs and VCSEL arrays to vastly increase data rates, boost energy and spectral efficiency, and take advantage of available and unregulated spectral bands. I design, fabricate, and test new experimental VCSEL diodes and novel two-dimensional (2D) VCSEL diode arrays. I study the physics and performance trade-offs of VCSEL light emitters aimed at 5G and 6G optical wireless communication and sensing applications. Via in-house computer modeling and simulation programs, I design VCSEL epitaxial structures – composed of nanometer-thick aluminum-gallium-arsenide, indium-gallium arsenide, and gallium-arsenide-phosphide layers – with peak target emission wavelengths of 940 and 980 nanometers. A commercial foundry grows my experimental VCSEL epitaxial wafers by metal-organic vapor phase epitaxy on 3-inch diameter gallium-arsenide substrates. In my university cleanroom, I fabricate my VCSELs as quarter wafer test pieces using a new VCSEL Array 2018 mask set which contains single VCSELs, and several variations of novel 2D electrically parallel triple (3-element), septuple (7-element), and novemdecuple (19-element) geometric device designs. My fabricated devices feature high frequency, coplanar ground-signal-ground metal contact pads, and top-epitaxial-surface emission. I perform all device tests in my university laser diode laboratory via direct, on-wafer electrical probing under computer control, starting with continuous wave light output power-current-voltage sweeps via a calibrated photodiode-integrating sphere and variable current source. For emission spectra and small-signal frequency response measurements, I collect the emitted VCSEL light with a standard OM1 multiple mode optical fiber (MMF) – connected to either an optical spectrum analyzer or a photoreceiver. For on-wafer data transmission tests across OM1 MMF patch cords, I modulate my VCSELs with nonreturn to zero, pseudorandom bit patterns in the form of 2-level pulse amplitude modulation. I achieve record combinations of optical output power, bandwidth, and efficiency for my large oxide aperture diameter (larger than 20 micrometers) VCSELs and for my VCSEL arrays. For example, I demonstrate 200 milliwatts of optical output power, a bandwidth of 18 GHz, and a wall plug efficiency of 35 percent with a 19-element VCSEL array. I set several records for error free data transmission, for example, 40 Gbps for my triple and septuple VCSEL arrays and 25 Gbps for my novemdecuple VCSEL arrays, well beyond the previous record of 10 Gbps. My work is the first to investigate trade-offs in the highly nontrivial physics of VCSEL arrays aimed at high power and high bandwidth arrays for free space data transmission – producing new guiding principles for further device optimization and product development.ZukĂŒnftige Generationen optischer drahtloser Kommunikations- und Sensorsysteme erfordern kompakte, kostengĂŒnstige, zuverlĂ€ssige und hocheffiziente Lichtquellen, die modulierte Strahlen mit Datenraten von Gigabit pro Sekunde (Gbps) und gepulste Strahlen mit Anstieg- und Abfallzeiten im Sub-Nanosekundenbereich ĂŒber den freien Raum ĂŒbertragen können. Infrarote, oberflĂ€chenemittierende Laser mit vertikaler KavitĂ€t (VCSEL) sind genau eine solche Lichtquelle. Systeme der fĂŒnften Generation (5G) versprechen, Milliarden von Menschen und Billionen von GerĂ€ten und Sensoren fĂŒr das Internet der Dinge mit 1 bis ĂŒber 20 Gbps ĂŒber neu versteigerte Millimeterwellen-SpektralbĂ€nder (30 GHz bis 300 GHz) zu verbinden. Bis etwa 2030 sehen Systeme der sechsten Generation (6G) eine enorme BreitbandkapazitĂ€t ohne Latenzzeit vor – sie ermöglichen virtuelle und gemischte RealitĂ€ten in Echtzeit, Mensch-Maschine-Schnittstellen, autonome Fahrzeuge und vieles mehr. Die 6G-Technologie fĂŒgt Terahertz-Wellensender hinzu, einschließlich Infrarot-VCSELs und VCSEL-Arrays, um die Datenraten signifikant zu erhöhen, die Energie- und Spektraleffizienz zu steigern und die verfĂŒgbaren und noch unregulierten SpektralbĂ€nder zu nutzen. In der vorliegenden Arbeit werden neue experimentelle VCSEL-Dioden und neuartige zweidimensionale (2D) VCSEL-Diodenarrays entworfen, hergestellt und getestet. Die Physik der VCSEL-Lichtemittern, welche auf 5G- und 6G-optische drahtlose Kommunikations- und Sensoranwendungen ausgerichtet sind, wird untersucht und Performance-Tradeoffs fĂŒr die angedachten Anwendungen werden identifiziert und analysiert. Über hauseigene Computermodellierungs- und Simulationsprogramme wurden epitaktische VCSEL-Strukturen – bestehend aus nanometerdicken Aluminium-Gallium-Arsenid-, Indium-Gallium-Arsenid- und Gallium-Arsenid-Phosphid-Schichten – mit Peak-ZielemissionswellenlĂ€ngen von 940 und 980 Nanometern entworfen. Ein kommerzieller Hersteller hat die experimentellen VCSEL-Epitaxiewafer durch metallorganische Gasphasenepitaxie auf Gallium-Arsenid-Substraten mit einem Durchmesser von 3 Zoll gewachsen. In einem Reinraum an der UniversitĂ€t wurden die VCSELs als Viertelwafer-TeststĂŒcke mit einem neuen VCSEL Array 2018-Maskensatz gefertigt, der einzelne VCSELs und mehrere Variationen von neuartigen elektrisch parallelen 2D-Tripel- (3-Element), Septuple- (7-Element) und Novemdecuple- (19-Elemente) Strukturdesigns enthĂ€lt. Bei den prozessierten Strukturen handelt es sich um Top-Emitter mit hochfrequenzkompatiblen koplanare Masse-Signal-Masse-Metallkontaktpads. Alle Device-Tests wurden computergesteuert in einem universitĂ€ren Laserdiodenlabor durch direktes elektrisches On-Wafer Probing durchgefĂŒhrt, beginnend mit Dauerstrich-Lichtausgangsleistung-Strom-Spannungs-Sweeps ĂŒber eine kalibrierte Photodioden-Integrationskugel und eine variable Stromquelle. FĂŒr Emissionsspektren und Kleinsignal-Frequenzgangmessungen wurde das emittierte VCSEL-Licht mit einer standardmĂ€ĂŸigen OM1-Multimode-Glasfaser (MMF) eingesammelt – verbunden mit einem optischen Spektrumanalysator oder einem FotoempfĂ€nger. FĂŒr On-Wafer-DatenĂŒbertragungstests ĂŒber OM1-MMF-Patchkabel wurden die VCSELs mit pseudozufĂ€lligen Bitmustern im Non-Return-To-Zero Format mit 2-Level-Pulsamplitudenmodulation moduliert. In dieser Arbeit werden bisher unerreichte Kombinationen von optischer Ausgangsleistung, Bandbreite und Effizienz fĂŒr VCSEL und VCSEL-Arrays mit großer Oxid-Apertur (grĂ¶ĂŸer als 20 Mikrometer) demonstriert. Beispielsweise werden 200 Milliwatt optische Ausgangsleistung, eine Bandbreite von 18 GHz und eine Konversionseffizienz elektrischer zu optischer Leistung von 35 Prozent mit einem 19-Element-VCSEL-Array erreicht. Zudem werden mehrere Rekorde fĂŒr fehlerfreie DatenĂŒbertragung aufgestellt, zum Beispiel 40 Gbps fĂŒr Triple- und Septuple-VCSEL-Arrays und 25 Gbps fĂŒr Novemdecuple-VCSEL-Arrays, weit ĂŒber den bisherigen Stand der Technik von 10 Gbps hinaus. Diese Arbeit ist die erste, die Trade-Offs in der hochgradig nichttrivialen Physik von VCSEL-Arrays untersucht, die auf Arrays mit hoher Leistung und hoher Bandbreite fĂŒr die DatenĂŒbertragung im freien Raum abzielen – und damit neue Leitprinzipien fĂŒr die weitere Bauelementoptimierung und Produktentwicklung schafft.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement

    Freelance subtitlers in a subtitle production network in the OTT industry in Thailand: a longitudinal study

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    The present study sets out to investigate a subtitle production network in the over-the-top (OTT) industry in Thailand through the perspective of freelance subtitlers. A qualitative longitudinal research design was adopted to gain insights into (1) the way the work practices of freelance subtitlers are influenced by both human and non-human actors in the network, (2) the evolution of the network, and (3) how the freelance subtitlers’ perception of quality is influenced by changes occurring in the network. Eleven subtitlers were interviewed every six months over a period of two years, contributing to over 60 hours of interview data. The data analysis was informed by selected concepts from Actor-Network Theory (ANT) (Law 1992, 2009; Latour 1996, 2005; Mol 2010), and complemented by the three-dimensional quality model proposed by Abdallah (2016, 2017). Reflexive thematic analysis (Braun and Clarke 2019a, 2020b) was used to generate themes and sub-themes which address the research questions and tell compelling stories about the actor-network. It was found that from July 2017 to September 2019, the subtitle production network, which was sustained by complex interrelationships between actors, underwent a number of changes. The changes affected the work practices of freelance subtitlers in a more negative than positive way, demonstrating their precarious position in an industry that has widely adopted the vendor model (Moorkens 2017). Moreover, as perceived by the research participants, under increasingly undesirable working conditions, it became more challenging to maintain a quality process and to produce quality subtitles. Finally, translation technology and tools, including machine translation, were found to be key non-human actors that catalyse the changes in the network under study

    Safe and seamless transfer of control authority - exploring haptic shared control during handovers

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    This research aimed at investigating the impact of lateral assistance systems on drivers' performance and behaviour during transitions from Highly Automated Driving (HAD). The thesis focused on non-critical transitions and analysed the differences between system and user-initiated transitions. Hence, two experiments were developed and conducted in driving simulators to address questions relating to how handover procedures, which provide varying levels of lateral assistance, affect drivers' performance and behaviour at different stages of the transition. In particular, it was investigated which type of assistance yields better results depending on who initiated the transition of control. Drivers were induced to be Out-Of-The-Loop (OOTL) during periods of HAD and then exposed to both system and user-initiated transitions. Results showed that after user-initiated transitions, drivers were generally more engaged with the steering task and the provided assistance was not helpful and, in some cases, caused steering conflicts and a comfort drop. On the contrary, after system-initiated transitions, drivers were not engaged with the steering control and were more prone to gaze wandering. Strong lateral assistance proved to be most beneficial within the first 5 seconds of the transition, when drivers were not committed to the steering control. The provision of assistance at an operational level, namely when drivers had to keep the lane centre, was not enough to ensure good performance at a tactical level. Drivers were able to cope with tactical tasks, presented as lane changes, only after around 10 seconds from the start of the transitions in both user and system initiated cases (Chapter 3 and Chapter 4). The introduction of non-continuous lateral assistance, used to trigger steering conflicts and, in turn, a faster steering engagement, did not yield particular benefits during user-initiated transitions but it might have triggered a faster re-engagement process in system-initiated ones (Chapter 5). The results suggest that assisting drivers after user-initiated transitions is not advisable as the assistance might induce steering conflicts. On the contrary, it is extremely beneficial to assist drivers during system-initiated transitions because of their low engagement with the driving task. The thesis concludes with a general overview of the conducted studies and a discussion on future studies to take this research forward

    DETUROPE 2022

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    Great expectations: unsupervised inference of suspense, surprise and salience in storytelling

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    Stories interest us not because they are a sequence of mundane and predictable events but because they have drama and tension. Crucial to creating dramatic and exciting stories are surprise and suspense. Likewise, certain events are key to the plot and more important than others. Importance is referred to as salience. Inferring suspense, surprise and salience are highly challenging for computational systems. It is difficult because all these elements require a strong comprehension of the characters and their motivations, places, changes over time, and the cause/effect of complex interactions. Recently advances in machine learning (often called deep learning) have substantially improved in many language-related tasks, including story comprehension and story writing. Most of these systems rely on supervision; that is, huge numbers of people need to tag large quantities of data to tell the system what to teach these systems. An example would be tagging which events are suspenseful. It is highly inflexible and costly. Instead, the thesis trains a series of deep learning models via only reading stories, a self-supervised (or unsupervised) system. Narrative theory methods (rules and procedures) are applied to the knowledge built into the deep learning models to directly infer salience, surprise, and salience in stories. Extensions add memory and external knowledge from story plots and from Wikipedia to infer salience on novels such as Great Expectations and plays such as Macbeth. Other work adapts the models as a planning system for generating new stories. The thesis finds that applying the narrative theory to deep learning models can align with the typical reader. In follow up work, the insights could help improve computer models for tasks such as automatic story writing, assistance for writing, summarising or editing stories. Moreover, the approach of applying narrative theory to the inherent qualities built in a system that learns itself (self-supervised) from reading from books, watching videos, listening to audio is much cheaper and more adaptable to other domains and tasks. Progress is swift in improving self-supervised systems. As such, the thesis's relevance is that applying domain expertise with these systems may be a more productive approach in many areas of interest for applying machine learning

    Student Migration from Cameroon to China. Government Rhetoric and Student Experiences

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    Abstract This study examines China-Cameroon educational cooperation with focus on student migration from Cameroon to China. Student migration is approached from the perspectives of the states and Cameroonian students currently studying in China and those who have graduated and returned to Cameroon. Government rhetoric about student migration is one of the main topics of this thesis. Cameroonian authorities view student mobility to China as a means of ‘learning from China’ in sophisticated domains. This is in line with the Chinese government’s official rhetoric which portrays the training of African students and professionals as a ‘knowledge sharing’ strategy under a ‘Cooperation in Human Resources Development and Education’. It is within this framework that China has stated its commitment to assist Africa in Human Resources Development (HRD). I argue that discourses of ‘knowledge sharing’ and ‘learning from China’ do not translate into reality, due to structural and legal challenges students face during their training in China on the one hand, and the lack of a stringent student migration policy in Cameroon, on the other hand. This dissertation also contributes to the soft power debate. Beyond the official framing of the China-Africa educational cooperation as a measure of developmental support, the Chinese government (like many other countries in the world) unofficially resorts to education as a soft power resource. I engage with this debate using students® satisfaction with social and academic experiences as the precondition for education to become an effective strategy in China’s soft power or image-branding endeavor. I argue that despite China®s investment in a generous scholarship scheme and favorable student visa policy which have attracted an impressive number of African students and professionals in general, the outcome in terms of soft power is seemingly still limited. Despite their excitement with and praise for the quality of social facilities and the university infrastructure in China, Cameroonian students are dissatisfied with their overall academic and social experiences. Finally, the research endeavor assesses students’ migration motivations and expectations in comparison to that of the states. I argue that the two categories of stakeholders have divergent and contrasting expectations. Whereas the Cameroonian state views student migration as a means of transferring Chinese knowledge and know-how to Cameroon, the majority of the students (be them scholarship holders or self-funded students) do not necessarily prioritize acquiring knowledge and returning to Cameroon. The line between the economic and academic dimensions of their migratory projects is blurred. Enrolling in a Chinese university is not synonymous with having a sustainable academic project for a career prospect. It is rather embedded in a broader migration project of which the ultimate aim is to improve on one’s chances toward financial security and social mobility. Despite their dissatisfaction with the quality of education and social life in China, they appreciate and take advantage of resources and opportunities offered by the local economic environment. Furthermore, the Chinese language skills acquired during their stay in China increase the chances of the returnees in the labor market in Cameroon

    Integration of Organic Farm Waste into Smallholder Banana-Coffee-Based Farming Systems in the Kagera Region, NW Tanzania

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    In the studied Kagera region (NW Tanzania), smallholder banana-coffee-based farming systems developed over hundreds of years. To this day, they traditionally consist of four components: the older and younger homegardens (kibanja and kikamba in the local Bantu language), woodland (kabira), and grassland (rweya). The management of organic farm waste has played an essential role in maintaining soil fertility, diversity, and agricultural productivity in these agroforestry systems. However, rapid population growth since Tanzania’s independence in the 1960s, an influx of refugees in the 1990s, and accompanying environmental degradation have shaped large parts of the study region. As a result, farm sizes, crop yields, and food security have declined, soils and farming systems have degraded, and impoverishment has increased. The overall objective of this study was to investigate whether degraded homegardens can be transformed back into multifunctional, sustainable, and fertile agroforestry systems through sustainable organic farm waste management. Organic farm waste embraced crop and tree residues, kitchen and food waste including cooking ash (as inorganic residue), livestock manure and urine, animal bones, as well as human faeces and urine. The objective was subdivided into three targets and related research foci: (1) to understand the status quo of organic farm waste management in the research area, (2) to evaluate modification options for sustainable banana-coffee-based systems, and (3) to evaluate an optimisation of organic farm waste management to increase agricultural production. An interview of 150 smallholder households on the current availability and uses of organic farm waste was conducted (1). The survey encompassed geographical variables, economic data, and household and agricultural information relating to the Water-Soil-Waste Nexus and the Water-Energy-Food Nexus. A farm household typology was constructed to categorise the farm households according to their biomass production and use of organic farm waste. Five focus group discussions were held in a local farmer field school to evaluate training on sustainable land use management (2). The farmer field school had trained about 750 farm households in de-graded banana-coffee-based farming systems in the last two decades. Also here, a typology construction of trained farm households was created. Both typologies were compared to each other. Nutrient cycles of the homegardens of trained and untrained farm house-holds were calculated (3) using the following scenarios: S0: business as usual; S1: the use of 80% of the available human urine; S2: the incorporation of 0.5 t yr-1 of the herbaceous legume species Crotalaria grahamiana into the soil; S3: the production of 5 m3 yr-1 of CaSa-compost (human excreta and biochar) and its application on 600 m2 of land; and S4: a combination of S1, S2, and S3. Results revealed that integrated organic farm waste management still plays a key role in farm nutrient and soil fertility management in these farming systems, but to a lower extent than in the past (status quo). Smallholder farmers that apply organic farm waste to their fields – using in situ, pit, ring-hole, and mixed composting techniques – have higher yields. However, the knowledge on waste management – traditionally passed on from generation to generation – has declined. Today, only one-third of these households earn a reasonable living from their agricultural products. Female-led households with a high age-dependency ratio and farmers with problematic socio-economic backgrounds continue to be the most vulnerable to food insecurity. In comparison, the implementation of training on sustainable land-use management has considerably improved farmers’ livelihoods. Successfully implemented knowledge on sustainable soil and farm nutrient management, including the modification of composting techniques, afforestation, selection of appropriate crop and tree species, improved labour allocation and time management, agricultural record-keeping, as well as gender-responsive communication and decision-making, has led to a transition: from degraded agricultural to multifunctional agroforestry systems. However, also here, one-third of the trained farmers has hardly transformed at all and has remained vulnerable to difficulties with food security, income diversification, and access to education. Comparing the nutrient balance between the homegardens of untrained and trained households, the homegardens of trained households are more likely to have a positive nutrient balance than those of untrained ones. Although untrained households would improve the nutrient balance under all management scenarios, their nutrient balances do not actually turn positive, especially not for nitrogen. Besides, nutrient cycles in the homegardens of all households remain ‘open’ because farmers currently import nutrients from the surrounding area, e.g., through fodder from the grassland. To overcome this dependency, short-term nutrient deficiencies might be alleviated with a precise application of mineral fertiliser and by fostering zero grazing. However, limited access to mineral fertiliser, labour-intensive manure collection and compost production against a background of land scarcity, labour shortage, prolonged dry seasons, and socio-economic imbalances, remain major challenges. To conclude, action needs to be taken and supporting policies and regulations need to be developed, e.g., on the safe use of organic farm waste and wastewater in smallholder agriculture to contribute towards achieving key Sustainable Development Goals of the United Nations. The relevant goals are Goal 2 (Zero hunger), Goal 7 (Affordable and clean energy), and Goal 15 (Life on land). None of the un-trained smallholder households lives under the conditions that these goals intend to prescribe. Only one-third of the trained farming households is one step closer to achieving these targets. To counteract this, a roadmap may serve as a starting point for future initiatives to develop coherent policies and science-based guidelines.:List of figures 7 List of tables 13 Abbreviations and acronyms 17 Units 20 Abstract 21 Zusammenfassung 23 1 Introduction 29 1.1 Problem identification and structure of this thesis 29 1.2 Study area 31 1.2.1 Environment 31 1.2.2 History and development of agriculture 37 1.2.3 Social, economic, and ecological challenges 44 1.3 Objectives 46 1.4 Research questions 47 1.4.1 The status quo of organic farm waste management 48 1.4.2 The transition towards multifunctionality 49 1.4.3 The optimisation of farm waste management 50 1.5 List of publications 53 2 Status quo of organic farm waste management 55 Highlights 55 Graphical abstract 56 Abstract 56 Keywords 57 2.1 Introduction 57 2.2 Background 59 2.2.1 The development of banana-coffee-based farming systems in Karagwe 59 2.2.2 The traditional role of organic farm waste 62 2.3 Materials and methods 63 2.3.1 Study area 63 2.3.2 Methods 65 2.4 Results 67 2.4.1 Farm household typology 67 2.4.2 Status quo of the farm waste management 72 2.4.3 Today's gender roles in agriculture 75 2.5 Discussion 78 2.6 Conclusions and recommendations 81 2.7 Declaration of competing interest 82 2.8 Acknowledgements 82 2.9 References 83 3 Traditional and adapted composting practices 91 Abstract 91 3.1 Introduction 92 3.1.1 Banana-coffee-based farming systems in the highlands of Tanzania 95 3.1.2 Composting practices 98 3.1.3 Traditional: In-situ and pit composting 100 3.1.4 Adapted: On-surface composting 101 3.2 Case studies 102 3.2.1 Traditional composting in the Kagera region 102 3.2.2 On-surface composting in the Morogoro region 104 3.3 Discussion 107 3.4 Conclusion 109 3.5 References 110 4 Transition towards multifunctional farming systems 115 Graphical abstract 115 Highlights 116 Abstract 116 Keywords 117 4.1 Introduction 117 4.2 Materials and methods 120 4.2.1 Study area 120 4.2.2 CaSa-compost 120 4.2.3 Data collection 121 4.2.4 Data analysis 124  4.3 Results 125 4.3.1 Group A: Successful farm households 126 4.3.2 Group B: Moderate successful farm households 134 4.3.3 Group C: Failing farm households 136 4.3.4 Remaining challenges and bottlenecks 138 4.4 Discussion 139 4.5 Conclusions and recommendations 143 4.6 Acknowledgements 144 4.7 References 145 5 Optimised nutrient management 155 Abstract 155 Keywords 156 5.1 Introduction 157 5.2 Materials and methods 158 5.2.1 Study area 158 5.2.2 Data 160 5.3 Results 175 5.4 Discussion 181 5.4.1 Methodology 181 5.4.2 Results 181 5.5 Conclusions and recommendations 186 5.6 Appendix A 188 5.7 References 192 6 Synthesis 199 6.1 Summary and discussion of the results 199 6.1.1 The status quo of organic farm waste management 199 6.1.2 The modification of traditional farm waste management 203 6.1.3 The optimisation of farm waste management 206 6.2 Relevance to the Sustainable Development Goals (SDGs) 208 6.3 Outline of a roadmap for the implementation of the SDG target 2.4 211 6.4 Limitations 215 6.5 Concluding discussion and recommendations 215 7 References 221 8 Appendix 233 8.1 Data set of smallholder farm households 233 Abstract 234 Keywords 235 8.1.1 Specifications table 235 8.1.2 Value of the data 237 8.1.3 Data description 237 8.1.4 Experimental design, materials, and methods 238 Ethics statement 240 Declaration of competing interest 240 Acknowledgments 240 References 240 8.2 Survey data 243 8.2.1 Meta data 243 8.2.2 Geographical data 245 8.2.3 Household information 251 8.2.4 Agricultural information 257 8.2.5 Economic data and Water-Energy-Food (WEF) Nexus 285 8.2.6 Gender-specific distribution of tasks within the farming family 298Bananen-Kaffee-basierte Anbausysteme haben eine lange Tradition in Ostafrika. In der Kagera-Region im Nordwesten Tansanias entwickelten sich ĂŒber Jahrhunderte hinweg ertragreiche Bananen-Kaffee-basierte Anbausysteme in kleinbĂ€uerlicher Landwirtschaft. Die Böden der HausgĂ€rten waren durch die kontinuierliche Zugabe von kompostierten organischen AbfĂ€llen dunkel, humusreich und fruchtbar. Jedoch verlor dieses nachhaltige Agroforstsystem in der Kagera-Region in den letzten 50 Jahren zunehmend an Bedeutung. Die GrĂŒnde dafĂŒr waren in erster Linie der rasche Anstieg der Bevölkerung seit der UnabhĂ€ngigkeit Tansanias in den 1960er-Jahren sowie der Zustrom von FlĂŒchtlingen in den 1990er-Jahren. Beides fĂŒhrte zu einer Erhöhung der Nachfrage nach Nahrungsmitteln, Baumaterial und Brennholz, die noch immer wichtigste Energiequelle zum Kochen mit einhergehender Degradierung, massiver Entwaldung sowie nachlassender Erhaltung der Bodenfruchtbarkeit und das Auslassen notwendiger Brachzeiten und GrĂŒndungen. Infolgedessen wurden den Böden ĂŒber fĂŒnf Jahrzehnte mehr NĂ€hrstoffe entzogen als zugefĂŒgt, was zu einer Abnahme der Bodenfruchtbarkeit fĂŒhrte. Die ErnteertrĂ€ge aller ein- und mehrjĂ€hrigen Kulturpflanzen sind zurĂŒckgegangen und die Böden sowie die Vegetation der HausgĂ€rten sind teilweise stark degradiert. Seitdem sind die ErnĂ€hrungssicherheit und der Wohlstand der lokalen Bevölkerung sowie die fĂŒr Tansanias Wirtschaft wichtigen Exporte von Bananen (Musa L.) und Kaffee (Coffea canephora L. var. robusta) aus der Kagera-Region gefĂ€hrdet. Ziel dieser Dissertation war es, zu untersuchen, ob der jetzigen Degradierung der HausgĂ€rten, die fĂŒr die ErnĂ€hrungssicherung der Bevölkerung entscheidend sind, durch eine erneute, stĂ€rkere und nachhaltige Einbindung organischer AbfĂ€lle entgegengewirkt werden kann und so wie einst multifunktionale, nachhaltige und fruchtbare Agroforstsysteme entstehen können. Dieses Ziel wurde in drei untergeordnete Ziele unterteilt: (1) das VerstĂ€ndnis des Ist-Zustandes des organischen Abfallmanagements im Forschungsgebiet, (2) die Untersuchung von Modifikationsmöglichkeiten fĂŒr nachhaltige Bananen-Kaffee-basierte Agrarforstsysteme sowie (3) die Evaluierung der Optimierungsmöglichkeiten des organischen Abfallmanagements zur Steigerung der landwirtschaftlichen Produktion. FĂŒr jedes Ziel wurde eine Forschungsfrage entwickelt: (1) Inwieweit werden die organischen AbfĂ€lle bereits genutzt (Ist-Zustand) und kann abgeschĂ€tzt werden, ob das momentane Abfallmanagement ausreicht, um die Bodenfruchtbarkeit und die Produktion von Nahrungsmitteln und EnergietrĂ€gern zu erhöhen und damit die Armut zu reduzieren; (2) Ob und wie das derzeitige Management organischer AbfĂ€lle verbessert werden könnte, um die Bodenfruchtbarkeit und die Biomasseproduktion zu erhöhen; (3) Ob und wie negative NĂ€hrstoffbilanzen in positive umgewandelt werden können, wenn das organische Abfallmanagement in den Anbausystemen optimiert und verbessert in den landwirtschaftlichen Stoffkreislauf integriert werden wĂŒrde. Zur Beantwortung der ersten Frage wurden 150 kleinbĂ€uerliche Haushalte zu ihrer aktuellen landwirtschaftlichen Produktion, der VerfĂŒgbarkeit und Aufbereitung von organischen AbfĂ€llen sowie deren Verwendung im Anbau der wichtigsten ein- und mehrjĂ€hrigen Kulturpflanzen befragt. Die Befragung umfasste geografische und ökonomische Daten sowie haushaltsbezogene und landwirtschaftliche Informationen in Bezug auf den Wasser-Boden-Abfall-Nexus und den Wasser-Energie-Nahrungsmittel-Nexus. Mit den erhobenen Daten wurde eine expertenbasierte Typologie der befragten Haushalte erstellt, um diese nach ihrer Biomasseproduktion sowie der Nutzung von organischen AbfĂ€llen zu kategorisieren. BezĂŒglich der zweiten Frage wurden fĂŒnf Fokusgruppendiskussionen mit den Ausbildern und Ausbilderinnen einer lokalen Bauernschule durchgefĂŒhrt, die in den vergangenen zwei Jahrzehnten mehr als 700 kleinbĂ€uerliche Haushalte in nachhaltiger Landwirtschaft schulten. Dabei wurde ebenfalls eine expertenbasierte Typologie der geschulten Haushalte erstellt. Beide Haushaltstypologien wurden hingehend ihrer Biomasseproduktion, organischen Abfallnutzung und Wohlstandes miteinander verglichen. Im Rahmen der dritten Fragestellung wurden die NĂ€hrstoffkreislĂ€ufe der HausgĂ€rten von geschulten und nicht geschulten Bauernhaushalten analysiert. Dabei wurden folgende Szenarien berĂŒcksichtigt: S0: der normale Betrieb ohne Änderungen (Ist-Zustand); S1: die Nutzung von 80 % des verfĂŒgbaren menschlichen Urins; S2: die Einarbeitung von 0,5 Tonnen pro Jahr der krautigen Leguminosenart Crotalaria grahamiana in den Boden; S3: die Produktion von jĂ€hrlich 5 Kubikmetern CaSa-Kompost, bestehend aus menschlichen Ausscheidungen und Biokohle, und dessen Ausbringung auf 600 Quadratmetern in den HausgĂ€rten; und S4: eine Kombination aus S1, S2 und S3. Entsprechende Daten wurden der Literatur entnommen. Die Ergebnisse zeigten, dass die Einbindung organischer AbfĂ€lle auch in degradierten Bananen-Kaffee-basierten Anbausystemen noch immer eine SchlĂŒsselrolle im NĂ€hrstoff- und Bodenfruchtbarkeitsmanagement spielt, jedoch zu einem niedrigeren Ausmaß als noch vor 50 Jahren. An Bedeutung verlor dabei auch die traditionelle Weitergabe des Wissens ĂŒber Kompostierung durch erschwerte sozio-ökonomische Bedingungen. Generell wurde festgestellt, dass Kleinbauernfamilien, die organische AbfĂ€lle auf ihren Feldern ausbringen, höhere landwirtschaftliche ErtrĂ€ge erzielen. Das Potenzial zur Erhaltung der Bodenfruchtbarkeit wird dabei jedoch aktuell nicht vollstĂ€ndig ausgeschöpft, und nur ein Drittel der herkömmlichen kleinbĂ€uerlichen Haushalte erzielt einen den LebensumstĂ€nden annĂ€hernd angemessenen Lebensunterhalt (Ist-Zustand). Ein weiteres Drittel der ungeschulten Haushalte nutzt organische DĂŒnger zu einem geringeren Ausmaß und erzielt deswegen und wegen weiterer SchwĂ€chen im landwirtschaftlichen Management geringere ErnteertrĂ€ge. Sie sind damit stĂ€rker armutsgefĂ€hrdet als die erstgenannte Gruppe. Jedoch sind v. a. Haushalte, die von alleinerziehenden Frauen gefĂŒhrt werden (ebenfalls ein Drittel der befragten Haushalte), am stĂ€rksten von ErnĂ€hrungsunsicherheit und Armut betroffen. Dabei spielen problematische, sozio-ökonomische HintergrĂŒnde eine erschwerende Rolle. Um das Ausmaß dieser Armutsspirale zu verringern, entwickelte eine lokale Bauernschule eine umfangreiche Ausbildung im Bereich nachhaltiger Landwirtschaft. Die erfolgreiche Implementierung der Ausbildung in die eigene Produktion hat die Lebensgrundlage von mindestens einem Drittel der geschulten Bauernhaushalte deutlich verbessert. Erfolgreich umgesetztes Wissen haben dazu gefĂŒhrt, dass degradierte Bananen-Kaffee-basierte Anbausysteme sich zunehmend zu multifunktionalen Agroforstsystemen entwickeln. Hierdurch hat sich nur fĂŒr ein Drittel der ausgebildeten Bauern bereits die Lage signifikant verbessert. Ein weiteres Drittel befindet sich noch in dem Transformationsprozess. Ihre ErtrĂ€ge bleiben jedoch unter denen der ersten Gruppe. Die dritte Gruppe innerhalb der geschulten Bauernhaushalte konnte das erworbene Wissen wiederum nicht oder nur kaum in die Praxis umsetzen. Diese Gruppe bleibt in Bezug auf ErnĂ€hrungssicherheit, Einkommens-diversifizierung und Zugang zu Bildung stark vulnerabel. Im Vergleich der NĂ€hrstoffbilanzen der HausgĂ€rten zwischen den geschulten und den ungeschulten Bauernhaushalten zeigen erstere eher eine positive NĂ€hrstoffbilanz als letztere. Obwohl sich die NĂ€hrstoffbilanzen der Felder ungeschulter Haushalte unter allen Managementszenarien verbessern wĂŒrden, wĂŒrden sie jedoch noch negativ bleiben, insbesondere fĂŒr Stickstoff. DarĂŒber hinaus sind die NĂ€hrstoffkreislĂ€ufe in den HausgĂ€rten aller Familien nicht geschlossen, da ein Großteil der NĂ€hrstoffe aus der Umgebung importiert wird, z. B. durch die Verwendung von Futtermittel aus dem umliegenden Grasland.:List of figures 7 List of tables 13 Abbreviations and acronyms 17 Units 20 Abstract 21 Zusammenfassung 23 1 Introduction 29 1.1 Problem identification and structure of this thesis 29 1.2 Study area 31 1.2.1 Environment 31 1.2.2 History and development of agriculture 37 1.2.3 Social, economic, and ecological challenges 44 1.3 Objectives 46 1.4 Research questions 47 1.4.1 The status quo of organic farm waste management 48 1.4.2 The transition towards multifunctionality 49 1.4.3 The optimisation of farm waste management 50 1.5 List of publications 53 2 Status quo of organic farm waste management 55 Highlights 55 Graphical abstract 56 Abstract 56 Keywords 57 2.1 Introduction 57 2.2 Background 59 2.2.1 The development of banana-coffee-based farming systems in Karagwe 59 2.2.2 The traditional role of organic farm waste 62 2.3 Materials and methods 63 2.3.1 Study area 63 2.3.2 Methods 65 2.4 Results 67 2.4.1 Farm household typology 67 2.4.2 Status quo of the farm waste management 72 2.4.3 Today's gender roles in agriculture 75 2.5 Discussion 78 2.6 Conclusions and recommendations 81 2.7 Declaration of competing interest 82 2.8 Acknowledgements 82 2.9 References 83 3 Traditional and adapted composting practices 91 Abstract 91 3.1 Introduction 92 3.1.1 Banana-coffee-based farming systems in the highlands of Tanzania 95 3.1.2 Composting practices 98 3.1.3 Traditional: In-situ and pit composting 100 3.1.4 Adapted: On-surface composting 101 3.2 Case studies 102 3.2.1 Traditional composting in the Kagera region 102 3.2.2 On-surface composting in the Morogoro region 104 3.3 Discussion 107 3.4 Conclusion 109 3.5 References 110 4 Transition towards multifunctional farming systems 115 Graphical abstract 115 Highlights 116 Abstract 116 Keywords 117 4.1 Introduction 117 4.2 Materials and methods 120 4.2.1 Study area 120 4.2.2 CaSa-compost 120 4.2.3 Data collection 121 4.2.4 Data analysis 124  4.3 Results 125 4.3.1 Group A: Successful farm households 126 4.3.2 Group B: Moderate successful farm households 134 4.3.3 Group C: Failing farm households 136 4.3.4 Remaining challenges and bottlenecks 138 4.4 Discussion 139 4.5 Conclusions and recommendations 143 4.6 Acknowledgements 144 4.7 References 145 5 Optimised nutrient management 155 Abstract 155 Keywords 156 5.1 Introduction 157 5.2 Materials and methods 158 5.2.1 Study area 158 5.2.2 Data 160 5.3 Results 175 5.4 Discussion 181 5.4.1 Methodology 181 5.4.2 Results 181 5.5 Conclusions and recommendations 186 5.6 Appendix A 188 5.7 References 192 6 Synthesis 199 6.1 Summary and discussion of the results 199 6.1.1 The status quo of organic farm waste management 199 6.1.2 The modification of traditional farm waste management 203 6.1.3 The optimisation of farm waste management 206 6.2 Relevance to the Sustainable Development Goals (SDGs) 208 6.3 Outline of a roadmap for the implementation of the SDG target 2.4 211 6.4 Limitations 215 6.5 Concluding discussion and recommendations 215 7 References 221 8 Appendix 233 8.1 Data set of smallholder farm households 233 Abstract 234 Keywords 235 8.1.1 Specifications table 235 8.1.2 Value of the data 237 8.1.3 Data description 237 8.1.4 Experimental design, materials, and methods 238 Ethics statement 240 Declaration of competing interest 240 Acknowledgments 240 References 240 8.2 Survey data 243 8.2.1 Meta data 243 8.2.2 Geographical data 245 8.2.3 Household information 251 8.2.4 Agricultural information 257 8.2.5 Economic data and Water-Energy-Food (WEF) Nexus 285 8.2.6 Gender-specific distribution of tasks within the farming family 29
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