The Grand Ethiopian Renaissance Dam built on the Nile has sparked conflicts for over twelve years now since it was first announced in 2009. But in 2020 when Ethiopia finally started to fill this behemoth of a dam hostilities ramped up between Egypt and Ethiopia. Because around 95% of Egypt's freshwater comes from the Nile and this dam is positioned upstreams of Egypt's vital water source. As such, Egypt did not take lightly to Ethiopia's challenge towards their historical water hegemony and responded with threats of violence and war. To further complicate this situation Egyp is facing an acute water shortage in 2025 and climate change will throw a wrench into the whole situation as droughts and floods will become more frequent as the world grows warmer. The empirical work of this thesis used a process-tracing approach to identify that realistic fears are driving Egypt to react with aggression and seek conflicts. However, Egypt's goal is to achieve cooperation and create a water-sharing agreement with Ethiopia. The problem is that Ethiopia does not want to give up their dam control and is satisfied with the status quo, while Egypt is striving to create a situation where they both have something to gain from cooperation. Be it through threatening to invade Ethiopia and blow the dam up or through their use of international institutions to force Ethiopia into cooperation. In the end, the conflict continues as no cooperation agreement has been signed.

A key aspect of immersive audio is realistic acoustics. To get plausible acoustics for an environment the impulse response can be generated using acoustic simulations and should ideally be updated in real-time for interactive applications. In this thesis the listening experience of sound generated with an interactive sound propagation engine was explored and compared to spatial sound produced with a static impulse response. The aim was to evaluate the sound experience for applications outside of virtual reality, with computational cost in consideration. This was done by conducting a user study where the participants got to interact and compare the two sound methods in different environments. The study was performed using a custom developed application integrated with a pre-existing sound propagation engine. The results from the user study showed no obvious perceptive difference between the two sound rendering methods that could justify the extra computations. Overall there was even a slight preference for the stereo method that used a static impulse response. However, there were qualities to both sound rendering methods that were preferred depending on the environment. Another thing that was investigated in the work of this thesis was how the varying accuracy of localization of sound in different directions can be used in acoustic ray tracing algorithms. An alternative sampling method was developed that uses a biased distribution based on spatial resolution of human hearing instead of traditional uniform sampling. The computation time of the random sampling phase increases, but could potentially reduce the number of ray samples needed. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>

Work done at Luleå Technical University regarding the RTIC RTOS framework is expanded upon to yield a convenient toolset for event-based instrumentation by exploiting debug peripherals available on the ARMv7-M platform. By parsing the source of an RTIC application and recovering instrumentation metadata from user-supplied information, the target-emitted trace stream is decoded and mapped to RTIC task events, yielding a timeline of events that can be analyzed live and postmortem by help of a recording host-side daemon. Relevant sections of the ARMv7-M standard are covered, and peripheral configuration covered in detail. An instrumentation result of a trivial RTIC application is presented and graphically plotted to exemplify the value of the toolset, and topics of future work to improve the toolset are outlined.

In recent years, microservice architecture has surpassed monolithic architecture in popularity among developers by providing a flexible way of developing complex distributed applications. Whereas a monolithic application functions as a single indivisible unit, a microservices-based application comprises a collection of loosely coupled services that communicate with each other to fulfill the requirements of the application. Consequently, different services in a microservices-based application can be developed and deployed independently. However, this flexibility is achieved at the expense of reduced observability of microservices-based applications complicating the debugging of such applications. The reduction of observability can be compensated by performing distributed tracing in microservices-based applications. Distributed tracing refers to observing requests propagating through a distributed system to collect observability data that can aid in understanding the interactions among the services and pinpoint failures and performance issues in the system. Open- Telemetry, an open-source observability framework supported by Cloud Native Computing Foundation (CNCF), defines a standardized specification for generating observability data. Nevertheless, instrumenting an application with an observability framework incurs performance overhead. To tackle this deterioration of performance and to reduce the cost of persisting observability data, only a subset of the requests are typically traced by performing head-based or tail-based sampling. In this work, we present a tail-based sampling framework using stream processing techniques. The developed framework demonstrated promising performance in our experiments by saving approximately a third of memory-based storage compared to an OpenTelemetry tail-based sampling module. Moreover, being compliant with the OpenTelemetry specifications, our framework aligns well with the OpenTelemetry ecosystem. / Under de senaste åren har mikrotjänstarkitektur överträffat monolitisk arkitektur i popularitet bland utvecklare genom att erbjuda ett flexibelt sätt att utveckla komplexa distribuerade tillämpningar. Medan en monolitisk tillämpning fungerar som en enda odelbar enhet, består en mikrotjänstbaserad tillämpning av en samling löst kopplade tjänster som kommunicerar med varandra för att uppfylla tillämpningens krav. Därför kan olika tjänster i en mikrotjänstbaserad tillämpning utvecklas och driftsättas oberoende av varandra. Denna flexibilitet uppnås dock på bekostnad av minskad observerbarhet för mikrotjänstbaserade tillämpningar, vilket försvårar felsökningen av sådana tillämpningar. Den minskade observerbarheten kan kompenseras genom att utföra distribuerad spårning i mikrotjänstbaserade tillämpningar. Distribuerad spårning innebär att man observerar förfrågningar som sprids genom ett distribuerat system för att samla in data om observerbarhet som kan hjälpa till att förstå interaktionerna mellan tjänsterna och lokalisera fel och prestandaproblem i systemet. OpenTelemetry, ett ramverk för observerbarhet med öppen källkod som stöds av Cloud Native Computing Foundation (CNCF), definierar en standardiserad specifikation för att generera observerbarhetsdata. Att instrumentera en tillämpning med ett ramverk för observerbarhet medför dock en överbelastning av prestanda. För att hantera denna försämring av prestanda och för att minska kostnaden för att bevara observerbarhetsdata spåras vanligtvis endast en delmängd av förfrågningarna genom att utföra s.k. “head-based sampling” eller “tail-based sampling”. I det här arbetet presenterar vi ett ramverk för tail-based sampling med hjälp av strömbehandlingsteknik. Den utvecklade ramen visade lovande prestanda i våra experiment genom att spara ungefär en tredjedel av den minnesbaserade lagringen jämfört med en OpenTelemetry-modul för tail-based sampling. Eftersom vårt ramverk är förenligt med OpenTelemetry-specifikationerna är det dessutom väl anpassat till OpenTelemetry-ekosystemet.

The study in this thesis concerns Storglaciären, a very well known and studied glacier in northern Sweden. The glacier has been an object for research since the endof the 19th century. During the meltseason of 2012 25 dyetracing experiments were executed. These experiments were conducted to investigate the internal drainage system of Storglaciären in the lower ablation area. Similar studies were done in 1989 by Regine Hock and Roger Leb Hooke (1993). The outcome of the study in 2012 has been compared with their results to see if any changes in the drainage systemhave occurred. The results have also been compared to the results of Seaberg etal. (1988) from their experiments in 1984 and 1985. Studies of glacier behaviour are important since they have a large impact on the local and global environment. Moreover it has been observed that smaller glaciers (such as Storglaciären), that are easier to reach and to work on, have similar behaviour as bigger glaciers, making them good objects for research (Jansson, 1996). The experiments were conducted between the 6th and 24th of august and executed by first injecting dye into moulins on the glacier and then measuring the concentration of dye in the proglacial streams merging out from the front of Storglaciären. Rhodamine WT was used as dye. Storglaciären has three main pro-glacialstreams named Nordjåkk, Centerjåkk and Sydjåkk. Nordjåkk merges from the northside and the other two from the south side of the glacier front. Measurements were in the beginning taken in all of the streams but since no concentration was visible in Nordjåkk the focus was at the end of the fieldperiod only at Centerjåkk and Sydjåkk, which both had detectable dye concentrations. Both manual and automatical measurements were done. Breakthrough curves (concentration vs. time) were plotted for each experimentand for both Centerjåkk and Sydjåkk. From these curves calculations were donefollowing the methods in Willis et al. (2011). The main parameters calculatedwere: transit velocity, dispersivity and dye recovery. Breakthrough curves were also modelled for each experiment using the method in Willis et al. (1990). Overall the drainage system in the lower part of the ablation area of Storglaciärenhas not changed signicantly during the past 20 years. But the drainage systemseems to be divided into dierent parts using both a straight channel system and a distributed system. The distributed system of 2012 seems to be more homogeneous than in 1989 but whether the system is braided or consists of a linked cavity systemis hard to tell. Differences seen this year compared to previous investigations are that the transition from an early to a late season drainage system occurred later in the meltseason. The dominating subglacial stream in 2012 was Centerjåkk and not Sydjåkk as in previous investigations (Nordjåkk dominated north as before). The meltseason lasted only a few weeks in 2012 because of the cold conditions and low precipitation. This may have had a big inuence on the behaviour of the glacier.

To characterize corticostriatal projections from rodent sensorimotor cortex, the anterograde tracers biotinylated dextran amine (BDA) and fluororuby (FR) were injected into the whisker representations of the primary motor (MI) and somatosensory (SI) cortices. Reconstructions of labeled terminals and their beaded varicosities in the neostriatum and thalamus were analyzed quantitatively to determine the degree of labeled overlap in both of these subcortical structures. Corticostriatal projections from the vibrissal representation in MI were more extensive than corresponding projections from SI. Both cortical areas sent dense projections to the dorsolateral neostriatum, but the MI vibrissal representation also projected to regions located more rostrally and medially. Despite these differences, both MI and SI projected to overlapping parts of the dorsolateral neostriatum. Tracer injections in both cortical areas also produced dense anterograde and retrograde labeling in the medial sector of the posterior complex of the thalamus (POm). Because POm is somatotopically organized and has reciprocal connections with both SI and MI cortices, the amount of labeled overlap in POm was used to indicate whether the tracers were injected into corresponding whisker representations of MI and SI. We found that the proportion of labeled overlap in the neostriatum was highly correlated with the amount of labeled overlap in POm. These results indicate that the rodent neostriatum receives convergent projections from corresponding regions in MI and SI cortex. Furthermore, the thalamocortical projections of the POm indicate that it may modulate corticostriatal outputs from corresponding representations in MI and SI.

Novice programming students often fail or drop out of beginner’s programming courses. One reason for this are incomplete or incorrect mental models, especially with regards to variable assignment and execution sequence, meaning that students have structural misconceptions of how a computer functions. To help correct such misconceptions, this study develops, tests, and assesses an intervention to correct mental models. The intervention consists of an in-class exercise that revolves around code tracing, which is an activity in which students execute code by hand and keep track of variables and their values by using pen and paper. In order to assess the exercise’s effectiveness, participants completed a baseline test and a follow-up test. The study found that a large proportion of the students held inviable mental models with regards to either variable assignment, execution sequence, or variable scope—or any combination of the three. Post-exercise tests showed a significant improvement across all three of the aforementioned categories of misconceptions, especially with regards to execution sequence. To achieve wide-scale implementation of the proposed intervention, the study identified a number of obstacles and opportunities. In terms of obstacles, the baseline and follow-up tests need further sophistication to increase sensitivity. Relatedly, it is necessary to develop software that generates randomized baseline tests, follow-up tests, and code tracing exercise problems. Key opportunities are the intervention’s low-tech nature, limited time needed for the exercise, as well as effectiveness.

The underlying goal of neuroscience research is to understand how the nervous system functions to bring about behavior. A detailed map of neural circuits is required for scientists to tackle this question. To this purpose, we developed a synthetic and genetically-encoded system, TRanscellular ACtivation of Transcription (TRACT) to monitor cell-cell contact. Upon ligand-receptor interaction at sites of cell-cell contact, the transmembrane domain of an engineered Notch receptor is cleaved by intramembrane proteolysis and releases a fragment that regulates transcription in the receptor-expressing cell. We demonstrate that in cultured cells, the synthetic receptor can be activated to drive reporter gene expression by co-incubation with ligand-expressing cell or by growth on ligand-coated surfaces. We further show that TRACT can detect interactions between neurons and glia in the Drosophila brain; expressing the ligand in spatially-restricted subsets of neurons leads to transcription of a reporter in the glial cells that interact with those neurons. To optimize TRACT for neural tracing, we attempted to target the synthetic receptor to post-synaptic sites by fusion with the intracellular domain of Drosophila neuroligin2. However, this modification only facilitate the receptor to be localized homogeneously throughout the neurites. The induction data of the modified receptor shows that the new receptor has better sensitivity compared to the original receptor, but the ligand-receptor interaction still happened at non-synaptic sites of membrane contact. To further target the ligand to pre-synaptic sites, we fused the ligand to different pre-synaptic markers. We found the one fused with synaptobrevin is likely located at axon terminals, but only able to trigger moderate induction. Therefore, more examinations are required to further characterize the capability of this ligand. In summary, TRACT is useful for monitoring cell-cell interactions in animals and could also be used to genetically manipulate cells based on contact. Moreover, we believe that proper targeting of the ligand to synaptic sites will improve the specificity of TRACT for synaptic connections in the future.

This thesis intends to establish whether and to what degree possible explanations for the Visegrad Group´s response to the 2015-2016 migration crisis can be provided by Postfunctionalism and Intergovernmentalism. The purpose of this study is not to explicitly test the two theories but to use them as tools to better understand the case under analysis, by applying a non-competitive approach. Based on the elaboration of 21 official statements released by the Visegrad Group between 2015-2016, findings show that both theories could (partially) confirmed my initial hypotheses. I conclude that security matters (as Intergovernmentalist suggests) consisted in the lion´s share in the statements, while economy matters (as also suggested by Intergovernmentalism) did not. When it comes to identity matters (as Postfunctionalism suggests), I conclude that those were used in connection to security matters, with the aim of forging a common European response to the crisis and to justify the partisan reaction of the Visegrad Group.

Large-scale distributed systems---such as supercomputers, cloud computing platforms, and distributed applications---routinely suffer from slowdowns and crashes due to software and hardware problems, resulting in reduced efficiency and wasted resources. These large-scale systems typically deploy monitoring or tracing systems that gather a variety of statistics about the state of the hardware and the software. State-of-the-art methods either analyze this data manually, or design unique automated methods for each specific problem. This thesis builds on the vision that generalized automated analytics methods on the data sets collected from these complex computing systems provide critical information about the causes of the problems, and this analysis can then enable proactive management to improve performance, resilience, efficiency, or security significantly beyond current limits. This thesis seeks to design scalable, automated analytics methods and frameworks for large-scale distributed systems that minimize dependency on expert knowledge, automate parts of the solution process, and help make systems more resilient. In addition to analyzing data that is already collected from systems, our frameworks also identify what to collect from where in the system, such that the collected data would be concise and useful for manual analytics. We focus on two data sources for conducting analytics: numeric telemetry data, which is typically collected from operating system or hardware counters, and end-to-end traces collected from distributed applications. This thesis makes the following contributions in large-scale distributed systems: (1) Designing a framework for accurately diagnosing previously encountered performance variations, (2) designing a technique for detecting (unwanted) applications running on the systems, (3) developing a suite for reproducing performance variations that can be used to systematically develop analytics methods, (4) designing a method to explain predictions of black-box machine learning frameworks, and (5) constructing an end-to-end tracing framework that can dynamically adjust instrumentation for effective diagnosis of performance problems. / 2021-09-28T00:00:00Z