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- Tran Luciani, Danwei, 1985-
(författare)
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Designing for sketching to support concept exploration
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sketching is a way of exploring early concepts through the act of externalization in a suitable material with the aid of a suitable tool. One could use paper and sketch with a pencil or go digital and sketch with code. What is appropriate to choose depends on the situation and on the skillset of the person who is going to sketch. When sketching is done successfully, the externalization can “speak back” and thus engage the sketcher, and others, in a conversation leading to a better understanding of the sketched concepts as well as new concept ideas. This is thoroughly documented in literature – a typical example would be an architect sketching a site plan on a flat piece of paper and being able to read into the possible movements in the third-dimensional space. Sketching generally works like this in familiar, that is, idiomatic situations for experienced sketchers. In unfamiliar or non-idiomatic situations, existing sketching tools are inadequate for expressing and exploring early concepts. For novice sketchers, with limited sketching literacy, even attempting to sketch in an idiomatic situation can be challenging.Through three cases, I design for concept exploration by enabling sketching to understand how this can be done in new situations. The first case deals with expert sketchers exploring non-idiomatic situations: professional creatives working with fulldome format for visual communication. The second case deals with novice sketchers exploring non-idiomatic situations: design students working with virtual reality. The third case deals with novice sketchers exploring idiomatic situations: air traffic controllers working with finding alternative routes for aircraft in the airspace with automation support.I take a constructive design approach by making design examples and reflecting during and after the process. With the help of the design examples, I engage domain experts through participatory co-design workshops and elicit insights in order to inspire further design work. What I learn through this dynamic making-workshopping-and-reflecting process forms the foundation of the knowledge contribution. It is presented here as three design tactics on how sketching could be like to support concept exploration: 1) be responsive, 2) emulate salient material properties, and 3) be lightweight.
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- Danylenko, Antonina, 1986-
(författare)
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Decision Algebra : A General Approach to Learning and Using Classifiers
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Processing decision information is a vital part of Computer Science fields in which pattern recognition problems arise. Decision information can be generalized as alternative decisions (or classes), attributes and attribute values, which are the basis for classification. Different classification approaches exist, such as decision trees, decision tables and Naïve Bayesian classifiers, which capture and manipulate decision information in order to construct a specific decision model (or classifier). These approaches are often tightly coupled to learning strategies, special data structures and the special characteristics of the decision information captured, etc. The approaches are also connected to the way of how certain problems are addressed, e.g., memory consumption, low accuracy, etc. This situation causes problems for a simple choice, comparison, combination and manipulation of different decision models learned over the same or different samples of decision information. The choice and comparison of decision models are not merely the choice of a model with a higher prediction accuracy and a comparison of prediction accuracies, respectively. We also need to take into account that a decision model, when used in a certain application, often has an impact on the application's performance. Often, the combination and manipulation of different decision models are implementation- or application-specific, thus, lacking the generality that leads to the construction of decision models with combined or modified decision information. They also become difficult to transfer from one application domain to another. In order to unify different approaches, we define Decision Algebra, a theoretical framework that presents decision models as higher order decision functions that abstract from their implementation details. Decision Algebra defines the operations necessary to decide, combine, approximate, and manipulate decision functions along with operation signatures and general algebraic laws. Due to its algebraic completeness (i.e., a complete algebraic semantics of operations and its implementation efficiency), defining and developing decision models is simple as such instances require implementing just one core operation based on which other operations can be derived. Another advantage of Decision Algebra is composability: it allows for combination of decision models constructed using different approaches. The accuracy and learning convergence properties of the combined model can be proven regardless of the actual approach. In addition, the applications that process decision information can be defined using Decision Algebra regardless of the different classification approaches. For example, we use Decision Algebra in a context-aware composition domain, where we showed that context-aware applications improve performance when using Decision Algebra. In addition, we suggest an approach to integrate this context-aware component into legacy applications.
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- Gutzmann, Tobias
(författare)
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Benchmarking Points-to Analysis
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Points-to analysis is a static program analysis that, simply put, computes which objects created at certain points of a given program might show up at which other points of the same program. In particular, it computes possible targets of a call and possible objects referenced by a field. Such information is essential input to many client applications in optimizing compilers and software engineering tools.Comparing experimental results with respect to accuracy and performance is required in order to distinguish the promising from the less promising approaches to points-to analysis. Unfortunately, comparing the accuracy of two different points-to analysis implementations is difficult, as there are many pitfalls in the details. In particular, there are no standardized means to perform such a comparison, i.e, no benchmark suite - a set of programs with well-defined rules of how to compare different points-to analysis results - exists. Therefore, different researchers use their own means to evaluate their approaches to points-to analysis. To complicate matters, even the same researchers do not stick to the same evaluation methods, which often makes it impossible to take two research publications and reliably tell which one describes the more accurate points-to analysis.In this thesis, we define a methodology on how to benchmark points-to analysis. We create a benchmark suite, compare three different points-to analysis implementations with each other based on this methodology, and explain differences in analysis accuracy.We also argue for the need of a Gold Standard, i.e., a set of benchmark programs with exact analysis results. Such a Gold Standard is often required to compare points-to analysis results, and it also allows to assess the exact accuracy of points-to analysis results. Since such a Gold Standard cannot be computed automatically, it needs to be created semi-automatically by the research community. We propose a process for creating a Gold Standard based on under-approximating it through optimistic (dynamic) analysis and over-approximating it through conservative (static) analysis. With the help of improved static and dynamic points-to analysis and expert knowledge about benchmark programs, we present a first attempt towards a Gold Standard.We also provide a Web-based benchmarking platform, through which researchers can compare their own experimental results with those of other researchers, and can contribute towards the creation of a Gold Standard.
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- Jarrick, Simon, 1977-
(författare)
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Immunoglobulin A nephropathy and disease complications : register-based studies
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Immunoglobulin A nephropathy (IgAN) is the commonest primary glomerular disease worldwide. A kidney biopsy is required for the diagnosis. IgA immune-complex depositions sets off a cascade leading to renal scarring, proteinuria and hypertension. Peaking in young adults, IgAN contributes significantly to the burden of chronic kidney disease, which in turn may lead to cardiovascular disease and death. As IgAN peaks in childbearing age, its effect on pregnancy outcomes is of interest. All studies use the same cohort of 4126 patients with a biopsy diagnosis of IgAN, identified through the combination of computerized andmanual search in biopsy reports from all Swedish kidney pathology labs. In study I, a random subset of 127 patients from the biopsy cohort were selected for diagnosis validation by patient chart review. IgAN was confirmed or likely in 121 cases (positive predictive value > 95 %). Mean age at diagnosis was 39.6 years, 74 % were male. Study II compared mortality in IgAN patients and an individuallymatched reference population by survival analysis. IgAN was associated with an increase of 53 % in all-cause and 59 % in cardiovascular mortality, with an absolute excess death rate of in 310 person years. Mortality before end-stage renal disease was not significantly increased.Study III used a similar design to examine incident fatal and non-fatal ischemic heart disease (IHD) in IgAN patients and the same reference populations. We found an 86 % increase in IHD hazard and an absolute excess IHD risk of one per 340 person-years. In study IV, outcomes of 327 pregnancies in 208 women with IgAN were compared to reference pregnancies without IgAN, indicating increased odds of preterm birth < 37 weeks gestation, but not for very preterm birth < 34 weeks. Preeclampsia odds were quadrupled. Stillbirth and neonatal death were both uncommon and not increased in IgAN.
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- Lundberg, Jonas
(författare)
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Bibliometrics as a research assessment tool : impact beyond the impact factor
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: While bibliometrics is frequently used as a tool for research assessment and is thought of as objective, quantitative and unobtrusive, the usability of bibliometric indicators has seldom been properly assessed and their value therefore been questioned. The aim of this thesis is to explore and develop the utility of bibliometrics as a research assessment tool. This is done through four studies that address the validity of bibliometrics as a research assessment tool. The issues that are further investigated are related with field delineation (Study I), collaboration (II) and research performance (I/III/IV). Materials and methods: The thesis is primarily based on data from the citation indices (Cl) produced by Thomson Scientific. In the different studies bibliometric indicators are calculated based on 24 223 (I), 62 104 (II) 6 142 055 (III) and 596 (IV) publications. To assess the validity of bibliometric indicators calculated using the Cl, these are combined with data from PubMed (I) and compared with data from manual assessments (I), financial data (II) and a Swedish system for identification and early assessment of new methods in health care (IV). Three new indicators are developed based on theoretical reasoning (III). Results: Frequently used bibliometric methods do not allow valid assessment of the development of research areas (I) or collaboration between academia and industry (II). There are also flaws associated with the current state-of-the-art performance indicator (III). At the same time, there are bibliometric methods available that can be used for identifying research areas (I) and there are certain types of collaboration between academia and industry that accurately can be described using bibliometric indicators (II). New performance indicators, which assign equal weight to all publications and control for the skewed and differing distribution of citations over publications, have been developed (III). Publications related to health care technologies that are deemed as very promising by clinical experts receive high scores using these indicators (IV). Discussion: The results of this thesis show that uncritical assessments of research areas based on rudimentary article identification strategies or collaboration analyses based solely on coauthorship data may be misleading and thus provide incorrect information for decision-making. At the same time, a correct use of refined bibliometric indicators may provide valuable background information for decision makers.
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- Lundberg, Jonas, 1961
(författare)
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Energy metabolism in skeletal muscle during ischemia and reperfusion. Experimental and clinical aspects.
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microsurgical operations, using free vascularised transfer of tissues, induce an obligatory period of ischemia followed by reperfusion. The degree of ischemia and reperfusion injury is dependent on the ischemia time. To deminish the injury after skeletal muscle tissue transfers, a preservation method is needed all along with improved mechanistical knowledge. This is important especially in a situation where the aim of the transfer is a functioning unit and in circumstances where a long ischemia time is expeceted, such as complicated cases or during reoperations. The aim of this thesis was to evaluate the ischemia and reperfusion injury in the clinical and experimental situation with special reference to energy metabolism and to evaluate different treatments using energy metabolites as markers for the degree of injury.Muscle biopsies from patients having microsurgical muscle transfers were analysed for high energy phosphates, during ischemia and reperfusion, by high pressure liquid chromatography (HPLC) and by in vitro 31P- magnetic resonance spectroscopy (MRS). To evaluate different treatments, a model of pedicled rat rectus femoris muscle was developed where phosphorous metabolites and intracellular pH were analysed during ischemia and reperfusion by in vitro and in vivo 31P- MRS, continuously and noninvasively. Results from the clinical study showed a partial recovery of PCr to 79% of normal control after revascularisation and a mean ischemia time of 114 min (median 85 min). Furthermore, regression analysis showed a recovery of 60% after 3 h of ischemia and 1 h of reperfusion, in accordance with earlier experimental results, why it is of great importance to further elucidate the mechanisms behind ischemia and reperfusion injury, and to establish preservation methods for the muscle cell. Hypothermia of 9-12°C improved the energetic recovery after postischemic reperfusion with 22% regarding PCr and with 35% regarding ATP compared to room temperature (22-24°C). Intracellular pH was also improved after postischemic recovery (pH 6.88 in hypothermia , pH 6.55 at room temperature). Illumination with Singlet Oxygen Energy (SOE), (l= 634 nm) on skeletal muscle preserved in NaCl or Perfadex decreased the high energy phosphate degradation, thus improving the cellular energy status. Furthermore, SOE-illumination on the in vivo rat skeletal muscle model showed a decreased degradation of 21% regarding ATP during ischemia. SOE-illumination also improved postischemic energetic recovery as demonstrated with an improvement of 22% regarding PCr and with 20% regarding ATP, measured continuously by in vivo 31P MRS.This thesis has thus demonstrated in a novel approach mechanistic similarities between experimental and clinical energetic behavior of skeletal muscle during ischemia and reperfusion. It is also shown that muscle cell injury after ischemia and reperfusion can be deminished by hypothermia.Isolated skeletal muscle can be better preserved by illumination with SOE. Furthermore, skeletal muscle ischemia and reperfusion injury in the living animal can be significantly decreased by illumination with SOE.
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- Lundberg, Jonas, 1964-
(författare)
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Fast and Precise Points-to Analysis
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many software engineering applications require points-to analysis. These client applications range from optimizing compilers to integrated program development environments (IDEs) and from testing environments to reverse-engineering tools. The software engineering applications are often user-interactive, or used in an edit-compile cycle, and need the points-to analysis to be fast and precise.In this compilation thesis, we present a new context- and flow-sensitive approach to points-to analysis that is both fast and precise. This is accomplished by a new SSA-based flow-sensitive dataflow algorithm (Paper 1) and a new context-sensitive analysis (Paper 2). Compared to other well-known analysis approaches our approach is faster in practice, on average, twice as fast as the call string approach and by an order of magnitude faster than the object-sensitive technique. In fact, it shows to be only marginally slower than a context-insensitive baseline analysis. At the same time, it provides higher precision than the call string technique and is similar in precision to the object-sensitive technique. We confirm these statements with experiments in Paper 2.Paper 3 is a systematic comparison of ten different variants of context-sensitive points-to analysis using different call-depths for separating the contexts. Previous works indicate that analyses with a call-depth only provides slightly better precision than context-insensitive analysis and they find no substantial precision improvement when using a more expensive analyses with call-depth . The hypothesis in Paper 3 is that substantial differences between the context-sensitive approaches show if (and only if) the precision is measured by more fine-grained metrics focusing on individual objects (rather than methods and classes) and references between them. These metrics are justified by the many applications requiring such detailed object reference information.The main results in Paper 3 show that the differences between different context-sensitive analysis techniques are substantial, also the differences between the context-insensitive and the context-sensitive analyses with call-depth are substantial. The major surprise was that increasing the call-depth did not lead to any substantial precision improvements. This is a negative result since it indicates that, in practice, we cannot get a more precise points-to analysis by increasing the call-depth. Further investigations show that substantial precision improvements can be detected for but they occur at such a low detail level that they are unlikely to be of any practical use.
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- Lundberg, Jonas, 1974-
(författare)
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Shaping electronic news : A case study of genre perspectives on interaction design
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes and analyzes implications of going from hypertext news to hypermedia news through a process of design, involving users and producers. As in any product development, it is difficult to conceive design of a novel news format that does not relate to earlier genres, and thus to antecedent designs. The hypothesis is that this problem can be addressed by explicitly taking a genre perspective to guide interaction design. This thesis draws on genre theory, which has previously been used in rhetoric, literature, and information systems. It is also informed by theories from humancomputer interaction. The methodological approach is a case study of the ELIN project, in which new tools for online hypermedia newspaper production were developed and integrated. The study follows the project from concept design to interaction design and implementation of user interfaces, over three years. The thesis makes three contributions. Firstly, a genre perspective on interaction design is described, revealing broadly in what respects genre affects design. Secondly, the online newspaper genre is described. Based on a content analysis of online newspaper front-pages, and interviews with users and producers, genre specific design recommendations regarding hypertext news front-page design are given. A content analysis of Swedish online newspapers provides a basis for a design rationale of the context stream element, which is an important part of the news context on article pages. Regarding hypervideo news, design rationale is given for the presentation of hypervideo links, in the context of a hypermedia news site. The impact on news production in terms of dynamics of convergence is also discussed. Thirdly, the design processes in cooperative scenario building workshops are evaluated, regarding how the users and producers were able to contribute. It provides implications and lessons learned for the workshop phase model. A discourse analysis also reveals important facilitator skills and how participants relied on genre in the design process.
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