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  • Public defence: 2018-12-17 14:00 L30, NOD-huset, Kista
    Homem, Irvin
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Advancing Automation in Digital Forensic Investigations2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Digital Forensics is used to aid traditional preventive security mechanisms when they fail to curtail sophisticated and stealthy cybercrime events. The Digital Forensic Investigation process is largely manual in nature, or at best quasi-automated, requiring a highly skilled labour force and involving a sizeable time investment. Industry standard tools are evidence-centric, automate only a few precursory tasks (E.g. Parsing and Indexing) and have limited capabilities of integration from multiple evidence sources. Furthermore, these tools are always human-driven.

    These challenges are exacerbated in the increasingly computerized and highly networked environment of today. Volumes of digital evidence to be collected and analyzed have increased, and so has the diversity of digital evidence sources involved in a typical case. This further handicaps digital forensics practitioners, labs and law enforcement agencies, causing delays in investigations and legal systems due to backlogs of cases. Improved efficiency of the digital investigation process is needed, in terms of increasing the speed and reducing the human effort expended. This study aims at achieving this time and effort reduction, by advancing automation within the digital forensic investigation process.

    Using a Design Science research approach, artifacts are designed and developed to address these practical problems. Summarily, the requirements, and architecture of a system for automating digital investigations in highly networked environments are designed. The architecture initially focuses on automation of the identification and acquisition of digital evidence, while later versions focus on full automation and self-organization of devices for all phases of the digital investigation process. Part of the remote evidence acquisition capability of this system architecture is implemented as a proof of concept. The speed and reliability of capturing digital evidence from remote mobile devices over a client-server paradigm is evaluated. A method for the uniform representation and integration of multiple diverse evidence sources for enabling automated correlation, simple reasoning and querying is developed and tested. This method is aimed at automating the analysis phase of digital investigations. Machine Learning (ML)-based triage methods are developed and tested to evaluate the feasibility and performance of using such techniques to automate the identification of priority digital evidence fragments. Models from these ML methods are evaluated in identifying network protocols within DNS tunneled network traffic. A large dataset is also created for future research in ML-based triage for identifying suspicious processes for memory forensics.

    From an ex ante evaluation, the designed system architecture enables individual devices to participate in the entire digital investigation process, contributing their processing power towards alleviating the burden on the human analyst. Experiments show that remote evidence acquisition of mobile devices over networks is feasible, however a single-TCP-connection paradigm scales poorly. A proof of concept experiment demonstrates the viability of the automated integration, correlation and reasoning over multiple diverse evidence sources using semantic web technologies. Experimentation also shows that ML-based triage methods can enable prioritization of certain digital evidence sources, for acquisition or analysis, with up to 95% accuracy.

    The artifacts developed in this study provide concrete ways to enhance automation in the digital forensic investigation process to increase the investigation speed and reduce the amount of costly human intervention needed.


  • Public defence: 2018-12-18 10:00 Vivi Täckholm-salen (Q-salen), NPQ-huset, Stockholm
    Sigurlásdóttir, Sara
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Influence of host and bacterial factors during Neisseria meningitidis colonization2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The human-restricted pathogen Neisseria meningitidis is a major cause of bacterial meningitis and sepsis worldwide. Colonization of the mucosal layer in the upper respiratory tract is essential to establish an asymptomatic carrier state and invasive disease. N. meningitidis encounters diverse environmental challenges during colonization and has evolved multiple strategies and virulence factors to survive and adapt within the host.

    Upon initial adhesion to the host epithelial cells, N. meningitidis forms pilus-mediated aggregates called microcolonies, which are characterized by interbacterial and host-cell interactions. Microcolonies promote long-term asymptomatic colonization within the host. However, the dispersal of single bacteria from microcolonies can help N. meningitidis to develop close contact with host cells and facilitate the invasion of mucosal surfaces or transmission to a new host.

    This thesis focuses on understanding how the interplay between the host, environment, and virulence factors influences N. meningitidis colonization. Paper I shows that the host-derived metabolite lactate induces rapid dispersal of N. meningitidis microcolonies. Further molecular characterization in Paper II revealed that lactate-induced dispersal is mediated by pilus retraction, occurs in a density-dependent manner, and is responsive to temperature. Paper III shows that the deletion of D-lactate dehydrogenase LdhA in N. meningitidis promotes aggregation and biofilm formation through an increase in the autolysis-mediated release of extracellular DNA. Finally, Paper IV examines the role of polynucleotide phosphorylase (PNPase) in the virulence of N. meningitidis. The deletion of PNPase resulted in a pilus-dependent increase in the aggregation and adhesion to epithelial cells. A PNPase mutant was growth deficient and highly attenuated in an in vivo mouse model. Transcriptional analysis revealed that PNPase plays a role as a major regulator in N. meningitidis.

  • Public defence: 2018-12-20 10:00 De Geersalen, Geovetenskapens hus, Stockholm
    Malafry, Laurence
    Stockholm University, Faculty of Social Sciences, Department of Economics.
    Inequality and Macroeconomic Policy: Essays on Climate, Immigration and Fiscal Intervention2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis consists of four self-contained essays in economics.

    Optimal Climate Policy with Household Wealth Inequality. Policy makers concerned with setting optimal carbon taxes to address climate change externalities often employ integrated assessment models (IAMs). While these models differ on their assumptions of climate damage impacts, discounting and technology, they conform on their assumption of complete markets and a representative household. In the face of global inequality and significant vulnerability of asset poor households, I relax the complete markets assumption and introduce a realistic degree of global household inequality. A simple experiment of introducing a range of global carbon taxes shows a household's position on the global wealth distribution predicts the identity of their most preferred carbon price.

    Immigration Shocks, Equilibrium Unemployment and Inequality. The purpose of this paper is to present a proof-of-concept model for assessing the impact of immigration shocks on a country's equilibrium unemployment, wages and inequality. The model implements labour market matching in the workhorse heterogeneous agent macro model with precautionary savings. In this setting, I perform several transition experiments exploring the channels and mechanisms through which a substantial immigration shock affects macroeconomic outcomes, including conditional welfare and economic integration. I find that the identity of the immigration cohort, as well as, features of the receiving economy matter for both the magnitude and direction of the response.

    Fiscal Multipliers in the 21st Century. Fiscal multipliers appear to vary greatly over time and space. Based on VARs for a large number of countries, we document a strong correlation between wealth inequality and the magnitude of fiscal multipliers. In an attempt to account for this finding, we develop a life-cycle, overlapping-generations economy with uninsurable labor market risk. We calibrate our model to match key characteristics of a number of OECD economies, including the distribution of wages and wealth, social security, taxes, and government debt and study how a fiscal multiplier depends on various country characteristics. We find that the fiscal multiplier is highly sensitive to the fraction of the population who face binding credit constraints and also to the average wealth level in the economy. These findings together help us generate a cross-country pattern of multipliers that is quite similar to that in the data.

    Fiscal Consolidation Programs and Income Inequality. Following the Great Recession, many European countries implemented fiscal consolidation policies aimed at reducing government debt. Using three different empirical approaches, we document a strong positive relationship between higher income inequality and stronger recessive impacts of fiscal consolidation. To explain this finding, we develop a life-cycle, overlapping generations economy with uninsurable labor market risk. We calibrate our model to match key characteristics of a number of European economies, including the distribution of wages and wealth, and study the effects of fiscal consolidation programs. We find that higher income risk induces precautionary savings behavior, which decreases the proportion of credit-constrained agents in the economy. Our model produces a cross-country correlation between inequality and the fiscal consolidation multipliers in line with the data.

  • Public defence: 2019-01-10 13:00 Högbomsalen, Geovetenskapens hus, Stockholm
    Pas Schrijver, Annemiek
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Pastoralists, Mobility and Conservation: Shifting rules of access and control of grazing resources in Kenya's northern drylands2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Pastoral mobility is seen as the most effective strategy to make use of constantly shifting resources. In northern Kenya, mobile pastoralism as a highly-valued strategy to manage grazing areas and exploit resource variability is becoming more complex. Policy and project implementation has historically been driven by the imperative to secure land tenure and improve pasture in bounded areas through State-led settlement schemes. Relatively recently, increased (inter)national interests in nature and wildlife conservation on community land in the northern pastoralist regions see conservation and development as crucial and urgent requirements for stimulating economic growth and security. This study presents the case of Samburu pastoral mobility within the context of such shifting social and environmental circumstances. It focuses on changing rules of access and control of livestock resources. These transformations are analysed in the context of the large-scale establishment of community conservancies and what role these conservancies play in the actual use and transformation of space for pastoralists. Empirically, this thesis is based on a total of eighteen months fieldwork including semi-structured interviews and observations in Samburu, Isiolo and Laikipia. It demonstrates how the principal of reciprocal access to pasture between pastoralists is giving way to conditional access based on membership of more formal, territory-based institutions such as community conservancies. It further shows how access to private land may be open for negotiation through the formation of grazing arrangements, which are also used to control pastoralists’ movements beyond enclosed land. In spite of a rhetoric acknowledging the multiple benefits of livestock mobility, current policy entails a continuation of past policy and project implementation where prescriptions still revolve around conservation enclosures and settlement politics. The thesis concludes that such processes of territoriality are likely to produce unexpected and potentially disappointing outcomes, while struggle and conflict persist.

  • Public defence: 2019-01-11 10:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Reitti, Marcus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diaryliodonium Salts: Synthesis, Applications and Computational Investigations2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organic chemists have the ability to create complex organic molecules by connecting molecular building blocks in different ways. To name a few, these molecules are used as medicines, pesticides or in our household electronics, and are therefore crucial to life as we know it. While many excellent methods for the connection of these fragments are known, serious issues regarding efficiency and sustainability remain. Our research concerns the use of diaryliodonium salts as a way of improving on these issues. Diaryliodonium salts are hypervalent iodine reagents used to transfer aryl groups to suitable nucleophiles. This thesis concerns the synthesis of these reagents and their use in the formation of carbon-nitrogen and carbon-oxygen bonds.

    The first project investigates the possibility to synthesize unsymmetrical diaryliodonium salts starting from elemental iodine and arenes, as such a method could be more cost efficient and sustainable compared to existing methods starting from iodoarenes. It was found that highly sterically congested diaryliodonium salts could be synthesized in high yields.

    Next, we applied diaryliodonium salts in the arylation of nitrite to form aromatic nitro compounds. The methodology offered a broad scope with good to excellent yields. Furthermore, we presented the in situ functionalization of diaryliodonium salts that had been formed from iodoarenes and arenes. This conceptually novel approach could be a step towards a catalytic reaction using diaryliodonium salts.

    In the third project we investigated the mechanisms of O-arylations with diaryliodonium salts to provide a deeper understanding of the reaction pathways involved in product and byproduct formation. Reactions between electron-rich diaryliodonium salts, hydroxides or secondary alcohols were studied.  When using hydroxide as the nucleophile, the side products could be suppressed by the addition of aryne traps, suggesting such an intermediate in the reaction. A novel mechanism for the formation of the aryne was proposed based on DFT calculations.  When alcohols were used we detected the oxidation of the alcohol rather than aryne products. The oxidized product was shown to not originate from arynes or a radical process but was formed via an intramolecular deprotonation from a 4-coordinated intermediate as suggested by DFT-calculations and experiments.

    In the final project we developed two complementary methods for the synthesis of phenols using hydroxide surrogates as nucleophiles. These compounds have previously been difficult to make using diaryliodonium salts due to aryne formation or overarylation to form diaryl ethers. The first method used hydrogen peroxide as the surrogate and allowed formation of electron-deficient and moderately electron-rich phenols. The synthesis of ortho-alkyl substituted phenols could be accomplished by using silanols as the surrogate. This allowed us to synthesize several highly congested phenols in good yields. Highly electron-rich diaryliodonium salts were, however, not compatible with either of the two methods.

  • Public defence: 2019-01-11 13:00 JMK-salen, Garnisonen, Stockholm
    Faggella, Chiara
    Stockholm University, Faculty of Humanities, Department of Media Studies.
    "Not So Simple": Reassessing 1951, G.B. Giorgini and the launch of Italian fashion2019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation aims to shed light on the circumstances that allowed Italy to become a reputable country of origin in the international fashion market. In particular, my contribution to the historiography of Italian fashion is a reassessment of the role played by Giovanni Battista Giorgini, whose involvement with the fashion and handicraft industries has not been fully investigated by scholars so far. Drawing upon Marc Bloch’s paradigm against the “fetish of the single cause”, I argue that the historiography of Italian fashion is not so simple and linear as it has been presented so far. Instead, the appearance of Giorgini’s Italian High Fashion Shows from 1951 needs to be contextualized with other historical facts. By outlining a populous scenario of different actors and concurring events, this dissertation breaks away from the simplistic notion of Italian fashion being born overnight in 1951.

    Chapter one discusses the ways in which the idea of an Italian look emerged in the US press already before the end of World War II, and identifies the linguistic and visual features that characterized these earliest reports. Chapter two discusses the contributions to the promotion of Italian fashion merchandise in the United States by Max Ascoli, an antifascist Italian émigré who moved to New York in the late 1930s. His philanthropic involvement with the Italian handicraft industry is discussed in order to understand how the US market's faith in Italian goods had to be restored in relation to the perceived quality of exported goods. Chapter three focuses on Giovanni Battista Giorgini, presents a critical overview of his biography and identifies his earliest attempts at promoting Italian products to US and Canadian markets. Particular emphasis is given to Giorgini's role as an employee of the Allied Forces during the Allied occupation of Florence, and to the overlapping vicissitudes of his work with an American touring exhibition, Italy at Work, initiated by Ascoli. Chapter four discusses the activities of Giorgini’s competitors in Italy, that is agencies, associations and individuals that were operating in postwar times to export Italian fashion in the United States. Chapter five finally discusses the organization of Giorgini’s Italian High Fashion Shows in Florence between 1951 and 1953, the organization of his business venture and the ways in which the Shows solidified earlier representations of Italian fashion in the US press, becoming a benchmark for years to come.

    This study concludes that the historicisation of Giorgini, and his contribution to the promotion of Italy as an independent, non-derivative fashion market for export, was made possible thanks to a larger network of transatlantic actors that, immediately after World War II, strove for the same business goals. Eventually, this dissertation provides a historical perspective that defies the simplistic categorization of the past in straight compartments, in this case blurring the margins between Fascist and liberated, democratic Italy.

    The full text will be freely available from 2020-01-11 09:00