abstract: Quadratic growth curves of 2nd degree polynomial are widely used in longitudinal studies. For a 2nd degree polynomial, the vertex represents the location of the curve in the XY plane. For a quadratic growth curve, we propose an approximate confidence region as well as the confidence interval for x and y-coordinates of the vertex using two methods, the gradient method and the delta method. Under some models, an indirect test on the location of the curve can be based on the intercept and slope parameters, but in other models, a direct test on the vertex is required. We present a quadratic-form statistic for a test of the null hypothesis that there is no shift in the location of the vertex in a linear mixed model. The statistic has an asymptotic chi-squared distribution. For 2nd degree polynomials of two independent samples, we present an approximate confidence region for the difference of vertices of two quadratic growth curves using the modified gradient method and delta method. Another chi-square test statistic is derived for a direct test on the vertex and is compared to an F test statistic for the indirect test. Power functions are derived for both the indirect F test and the direct chi-square test. We calculate the theoretical power and present a simulation study to investigate the power of the tests. We also present a simulation study to assess the influence of sample size, measurement occasions and nature of the random effects. The test statistics will be applied to the Tell Efficacy longitudinal study, in which sound identification scores and language protocol scores for children are modeled as quadratic growth curves for two independent groups, TELL and control curriculum. The interpretation of shift in the location of the vertices is also presented. / Dissertation/Thesis / Doctoral Dissertation Statistics 2015

Power Analysis Attacks use the fact that power consumption in modern microprocessors and cryptographic devices depends on the instructions executed on them and so, it varies with time. This leak- age is mainly used to deduce cryptographic keys as well as algorithms by direct observation of power traces. Power Analysis is a recent field of study that has been developed for the last decade. Since then, the techniques used have evolved into more complex forms, that some- times require a variety of skills that makes the subject difficult to start with. Nowadays it is changeling to tackle the problem without expen- sive equipment; what is more, the off-the-shelf solutions to do Power Analysis Attacks are rare and expensive. This thesis aim to provide a low cost and open platform as an entry point to Power Analysis for a price under 10 USD. Besides that, it is designed to be able to per- form Simple Power Analysis and Differential Power Analysis attacks to a 8 bit microcontroller, including the software needed to automate the process of taking the measurements. Finally, the platform can be extended to cover a wide range of microcontrollers, microprocessors and cryptographic devices by simple insertion in a bread board, which makes it the perfect device for new comers to the field.

Philosophiae Doctor - PhD / Aid coordination in the health sector is known to be challenging in general, but even more in post-conflict settings, due to the multiplicity of actors of development, to the sense of emergency in providing health services, combined with the so-called weak institutional capacities‘ at local level, resulting from the conflict. This study sought to analyze broad determinants of aid coordination using the example of HRH policies in Burundi, during the post-conflict period. Burundi is a country in Central Africa, which experienced cyclic ethnic conflicts since its independence in 1962, the last conflict being the longest (1993-2006).Determinants of coordination were analyzed using the policy-analysis triangle (Gilson et Walt), using data from documents and semi-structured interviews, conducted in 2009 and in 2011, at national, provincial and facility-levels. A conceptual framework, combining organizational and social sciences theories, was devised in order to assess the organizational power of MoH, the one supposed to act as coordinator in the health sector. Findings showed a lack of coordination due to post-conflict specific context, to competition over scarce resources between both donor and recipient organizations and to an insufficiently incentivized and complex coordination process in practical. Most importantly, this research demonstrated the crucial role of post-conflict habitus and mistrust in the behavior of MoH and their influence on organizational power, and, in turn on their capacity to coordinate and exert an appropriate leadership. These findings, together with the growing body of literature on organizational sociology and collective trust, point at the crucial need to rebuild some of the wounded collective trust and organizational leadership in Burundi and in other fragile states.

The Keccak Sponge Function is the winner of the National Institute of Standards and Technology (NIST) competition to develop the Secure Hash Algorithm-3 Standard (SHA-3). Prior work has developed reference implementations of the algorithm and described the structures necessary to harden the algorithm against power analysis attacks which can weaken the cryptographic properties of the hash algorithm. This work demonstrates the architectural changes to the reference implementation necessary to achieve the theoretical side channel-resistant structures, compare their efficiency and performance characteristics after synthesis and place-and-route when implementing them on Field Programmable Gate Arrays (FPGAs), publish the resulting implementations under the Massachusetts Institute of Technology (MIT) open source license, and show that the resulting implementations demonstrably harden the sponge function against power analysis attacks.

The aim of this thesis is, firstly, to design and create the measuring environment for the research of electromagnetic side-channel attacks in cryptography; and secondly, to inform readers about the basics of electromagnetic and power side-channel attacks which present effective ways of the modern cryptosystems’ cryptoanalysis. In the theoretical part, the basic side-channel attacks, including their history and models, are described. The main part is focused on the explanation of the basic principles of power and electromagnetic side-channel attacks. Then, the work describes the basic physical principles of electromagnetic fields; and also the methods which can be used to measure the electromagnetic field. An example of the origination of the electromagnetic field in microprocessors is included. In the next part of the work the theoretical foundation necessary for successful implementation of the measurement of electromagnetic fields on the PIC microprocessor is presented. Next part of the chapter is devoted to the AES encryption standard, the activity of which is examined in the practical part. Furthermore, the magnetic probes, designed according to the theoretical knowledge are described. Also the research environment is described in this chapter. The list of measuring instruments used in the practical part is also included. The practical part of the work deals with the implementation aspects designed to achieve the ideal measurement conditions, such as the choice of appropriate probe, the appropriate location and distance between the probe and the measured system, setup of the oscilloscope and signal synchronization. Furthermore, the measured electromagnetic waveforms for selected instructions are presented. After that follows an analysis of the individual rounds of the AES encryption standard; the analysis of whole AES standard is also included. Then, the methods of simple and differential electromagnetic analysis are implemented. With regard to the knowledge gained in the practical part of the work, the possible countermeasures implemented against the power and electromagnetic side channel attacks are described. The final part of the work comprises a brief review of results.

No description available.

<p>Mediation analyses play a critical role in social and personality psychology research. However, current approaches for assessing power and sample size in mediation models have limitations, particularly when dealing with complex mediation models and multiple mediator sequential models. These limitations stem from limited software options and the substantial computational time required. In this part, we address these challenges by extending the joint significance test and product of coefficients test to incorporate the fourth-pathed mediated effect and generalized kth-pathed mediated effect. Additionally, we propose a model-based bootstrap method and provide convenient R tools for estimating power in complex mediation models. Through our research, we demonstrate that power decreases as the number of mediators increases and as the influence of coefficients varies. We summarize our results and discuss the implications of power analysis in relation to mediator complexity and coefficient influence. We provide insights for researchers seeking to optimize study designs and enhance the reliability of their findings in complex mediation models. </p> <p>Matching is a crucial step in causal inference, as it allows for more robust and reasonable analyses by creating better-matched pairs. However, in real-world scenarios, data are often collected and stored by different local institutions or separate departments, posing challenges for effective matching due to data fragmentation. Additionally, the harmonization of such data needs to prioritize privacy preservation. In this part, we propose a new hierarchical framework that addresses these challenges by implementing differential privacy on raw data to protect sensitive information while maintaining data utility. We also design a data access control system with three different access levels for designers based on their roles, ensuring secure and controlled access to the matched datasets. Simulation studies and analyses of datasets from the 2017 Atlantic Causal Inference Conference Data Challenge are conducted to showcase the flexibility and utility of our framework. Through this research, we contribute to the advancement of statistical methodologies in matching and privacy-preserving data analysis, offering a practical solution for data integration and privacy protection in causal inference studies. </p> <p>Biomarker discovery is a complex and resource-intensive process, encompassing discovery, qualification, verification, and validation stages prior to clinical evaluation. Streamlining this process by efficiently identifying relevant biomarkers in the discovery phase holds immense value. In this part, we present a likelihood ratio-based approach to accurately identify truly relevant protein markers in discovery studies. Leveraging the observation of unimodal underlying distributions of expression profiles for irrelevant markers, our method demonstrates promising performance when evaluated on real experimental data. Additionally, to address non-normal scenarios, we introduce a kernel ratio-based approach, which we evaluate using non-normal simulation settings. Through extensive simulations, we observe the high effectiveness of the kernel method in discovering the set of truly relevant markers, resulting in precise biomarker identifications with elevated sensitivity and a low empirical false discovery rate.  </p>

Many multiagent systems are environments where distinct decision-makers compete, explicitly or implicitly, for scarce resources. In these competitive environments, itcan be advantageous for agents to cooperate and form teams, or coalitions; this cooperation gives agents strategic advantage to compete for scarce resources. Multiagent systems thus can be characterized in terms of competition and cooperation. To evaluate the effectiveness of cooperation for particular coalitions, we derive measures based on comparing these different coalitions at their respective equilibria. However, relying on equilibrium results leads to the interesting question of stability. Control theory and cooperative game theory have limitations that make it hard to apply them to study our questions about stabililty and evaluate cooperation in competitive environments. In this thesis we will lay a foundation towards a theory of coalition stability and robustness for multiagent systems. We then apply this condition to form a methodology toevaluate cooperation for market structure analysis.

No description available.

Side-channel attacks pose significant challenges to the security of embedded systems, often allowing attackers to circumvent encryption algorithms in minutes compared to the trillions of years required for brute-force attacks. To mitigate these vulnerabilities, various countermeasures have been developed. This study focuses on two specific countermeasures: randomization of the encryption algorithm’s clock and the incorporation of a dummy core to disguise power traces. The objective of this research is to identify the optimal frequencies that yield the highest level of randomness when these two countermeasures are combined. By investigating the interplay between clock randomization and the presence of dummy cores, we aim to enhance the overall security of embedded systems. The insights gained from this study will contribute to the development of more robust countermeasures against side-channel attacks, bolstering the protection of sensitive information and systems. To achieve this, we conduct simulations and perform side-channel attacks on an FPGA to establish the relationship between frequencies and the resulting protection. We break the encryption on a non-duplicated circuit and note the least amount of measured power traces necessary and the timing overhead. We do this for all sets of frequencies considered which gives a good indication of which sets of frequencies give good protection. By comparing the frequencies generated with those from the duplicated circuit we use similar conclusions to prove whether a frequency set is secure or not. Based on our results we argue that having one frequency lower than half of the base frequency and the other frequencies being close but not higher than the base gives the highest security compared to the timing overhead measured. / Sido-kanal attacker utgör betydande utmaningar för säkerheten hos integrerade system och möjliggör ofta för angripare att kringgå krypteringsalgoritmer på minuter jämfört med de miljarder år som krävs för brute-force attacker. För att minska dessa sårbarheter har olika motåtgärder utvecklats. Denna studie fokuserar på två specifika motåtgärder: slumpmässig anpassning av krypteringsalgoritmens klocka och användningen av en dummykärna för att maskera strömsignaler. Syftet med denna forskning är att identifiera optimala frekvenser som ger högsta grad av slumpmässighet när dessa två motåtgärder kombineras. Genom att undersöka samverkan mellan slumpmässig anpassning av klockan och närvaron av dummykärnor strävar vi efter att förbättra den övergripande säkerheten hos integrerade system. De insikter som erhålls från denna studie kommer att bidra till utvecklingen av mer robusta motåtgärder mot sido-kanals attacker och stärka skyddet av känsliga system och information. För att uppnå detta genomför vi simuleringar och utför sido-kanals attacker på en FPGA för att etablera sambandet mellan frekvenser och det resulterande skyddet. Vi knäcker krypteringen på en icke-duplicerad krets och noterar den minsta mängden mätta strömsignaler som krävs samt tids fördröjning. Vi gör detta för alla uppsättningar av frekvenser som övervägs, vilket ger en god indikation på vilka frekvensuppsättningar som ger ett bra skydd. Genom att jämföra de genererade frekvenserna med dem från den duplicerade kretsen drar vi slutsatser för att bevisa om en frekvensuppsättning är säker eller inte. Baserat på våra resultat argumenterar vi för att ha en frekvens som är lägre än hälften av basfrekvensen och att de andra frekvenserna är nära men inte högre ger högsta säkerhet jämfört med den uppmätta tids fördröjningen.