As shared memory platforms continue to grow in core counts, the need for context-aware scheduling continues to grow. Context-aware scheduling takes into account characteristics of the system and application performance when making decisions. Traditionally applications run on a static thread count that is set at compile-time or at job start time, without taking into account the dynamic context of the system, other running applications, and potentially the performance of the application itself. However, many shared memory applications can easily be converted to malleable applications, that is, applications that can run with an arbitrary number of threads and can change thread counts during execution. Many new and intelligent scheduling decisions can be made when applications become context-aware, including expanding to ll an empty system or shrinking to accommodate a more parallelizable job. This thesis describes a prototype system called Resizing for Shared Memory (RSM), which supports OpenMP applications on shared memory platforms. RSM includes a main daemon that records performance information and makes resizing decisions as well as a communication library to allow applications to contact the RSM daemon and enact resizing decisions. Experimental results show that RSM can improve turn-around time and system utilization even using very simple heuristics and resizing policies. / Master of Science

The digital age has pushed people closer together than ever before. A device that fits in the palm of your hand allows instantaneous communication with billions of other human beings. People share everyday experiences, passing thoughts, personal photos, sometimes privately, often publicly. Distances between people and places feel reduced. Never has it been so easy to be so emotionally close to so many people. But as digital experiences become routine, our collective perceptions of closeness and distance shift. As virtual communities become larger, so does our awareness of the actual distance between things. Even though humans can be genuinely close to one another on the internet, fragments of meaning, tone, and physicality are often lost in distance. Over-dependence on digital connection can erode local communities and generate apathy towards the real systems we depend on for survival. This project aims to investigate strategies designers and architects may employ to regenerate and recontextualize local communities in the digital age. Research suggests that contemporary cities benefit from a softening of the barrier between public and private spaces. Porous and permeable boundaries between interior and exterior realms can allow dialogues to open and communities to grow, resulting in more enriched urban societies.

Cryptographic credential systems provide some possible solutions to the problem of privacy leakage of users in the ``virtual'' world. This thesis presents a privacy-preserving method which can enable the cryptographic credentials to have the capability of anonymous multi-show. Our approach builds on the work of Brands from the year 2000 which proposed a Digital Credential system that can protect users' privacy. This system is efficient but not perfect, since the Digital Credentials in that system can only be shown once to avoid linkability. We propose the use of a malleable signature technique to transform Brands' Digital Credentials from single-show to multi-show capability. In this thesis, we describe our modified issuing and showing protocols and discuss the security properties of our proposed scheme. We have a basic implementation (proof of concept) to support our concept and analysis of timing results is also provided. In the end, we point out a number of future directions which can be used to complement or improve this approach.

Traditionally, cryptographic algorithms are designed under the so-called black-box model, which considers adversaries that receive black-box access to the hardware implementation. Although a "black-box" treatment covers a wide range of attacks, it fails to capture reality adequately, as real-world adversaries can exploit physical properties of the implementation, mounting attacks that enable unexpected, non-black-box access, to the components of the cryptographic system. This type of attacks is widely known as physical attacks, and has proven to be a significant threat to the real-world security of cryptographic systems. The present dissertation is (partially) dealing with the problem of protecting cryptographic memory against physical attacks, via the use of non-malleable codes, which is a notion introduced in a preceding work, aiming to provide privacy of the encoded data, in the presence of adversarial faults. In the present thesis we improve the current state-of-the-art on non-malleable codes and we provide practical solutions for protecting real-world cryptographic implementations against physical attacks. Our study is primarily focusing on the following adversarial models: (i) the extensively studied split-state model, which assumes that private memory splits into two parts, and the adversary tampers with each part, independently, and (ii) the model of partial functions, which is introduced by the current thesis, and models adversaries that access arbitrary subsets of codeword locations, with bounded cardinality. Our study is comprehensive, covering one-time and continuous, attacks, while for the case of partial functions, we manage to achieve a stronger notion of security, that we call non-malleability with manipulation detection, that in addition to privacy, it also guarantees integrity of the private data. It should be noted that, our techniques are also useful for the problem of establishing, private, keyless communication, over adversarial communication channels. Besides physical attacks, another important concern related to cryptographic hardware security, is that the hardware fabrication process is assumed to be trusted. In reality though, when aiming to minimize the production costs, or whenever access to leading-edge manufacturing facilities is required, the fabrication process requires the involvement of several, potentially malicious, facilities. Consequently, cryptographic hardware is susceptible to the so-called hardware Trojans, which are hardware components that are maliciously implanted to the original circuitry, having as a purpose to alter the device's functionality, while remaining undetected. Part of the present dissertation, deals with the problem of protecting cryptographic hardware against Trojan injection attacks, by (i) proposing a formal model for assessing the security of cryptographic hardware, whose production has been partially outsourced to a set of untrusted, and possibly malicious, manufacturers, and (ii) by proposing a compiler that transforms any cryptographic circuit, into another, that can be securely outsourced.

Three collimators were designed and built with mouse irradiation in mind. They were made to have a shapeable aperture that could deliver strange or complex dose shapes to spots on the animals. Current collimators are either custom-built, expensive, or only provide limited dose shapes. These provide self-customizable collimation at a minimum of cost. A mouse holder was also devised to reproducibly hold a mouse under the collimator. Construction of the holder and of each collimator is also covered. Each collimator was analyzed for flaws, holes, and penumbral width across various shapes of interest. A Norelco MG300 X-ray generator at the Texas A&M Nuclear Science Center was used in these tests. The lead collimator had a radial penumbra of 1.2 mm. The clay / lead shot collimator had a radial penumbra of 1.6 mm. The brass collimator had a radial penumbra of 1.75 mm. Vertical and horizontal penumbras are dependent on distance from the center of the beam. All readings are + 0.3 mm according to the resolution of the scanner used in this experiment. Each collimator is useful for different purposes.

Cryptography allows us to do magical things ranging from private communication over a public channel to securely evaluating functions among distrusting parties. For the real-world implementation of these tasks, efficiency is usually one of the most desirable objectives. In this work, we advance our understanding of efficient cryptographic constructions on several fronts.<div><br></div><div>Non-malleable codes are a natural generalization of error-correcting codes. It provides a weaker yet meaningful security guarantee when the adversary may tamper with the codeword such that error-correcting is impossible. Intuitively, it guarantees that the tampered codeword either encodes the original message or an unrelated one. This line of research aims to construct non-malleable codes with a high rate against sophisticated tampering families. In this work, we present two results. The first one is an explicit rate1 construction against all tampering functions with a small locality. Second, we present a rate-1/3 construction for three-split-state tampering and two-lookahead tampering.</div><div><br></div><div>In multiparty computation, fair computation asks for the most robust security, namely, guaranteed output delivery. That is, either all parties receive the output of the protocol, or no party does. By relying on oblivious transfer, we know how to construct MPC protocols with optimal fairness. For a long time, however, we do not know if one can base optimal fair protocol on weaker assumptions such as one-way functions. Typically, symmetric-key primitives (e.g., one-way functions) are much faster than public-key primitives (e.g., oblivious transfer). Hence, understanding whether one-way functions enable optimal fair protocols has a significant impact on the efficiency of such protocols. This work shows that it is impossible to construct optimal fair protocols with only black-box uses one-way functions. We also rule out constructions based on public-key encryptions and f-hybrids, where f is any incomplete function.</div><div><br></div><div>Collective coin-tossing considers a coin-tossing protocol among n parties. A Byzantine adversary may adaptively corrupt parties to bias the output of the protocol. The security ε is defined as how much the adversary can change the expected output of the protocol. In this work, we consider the setting where an adversary corrupts at most one party. 10 Given a target security ε, we wish to understand the minimum number of parties n required to achieve ε-security. In this work, we prove a tight bound on the optimal security. In particular, we show that the insecurity of the well-known threshold protocol is at most two times the optimal achievable security. </div>

Adaptive parallel applications that can change resources during execution, promise increased application performance and better system utilization. Furthermore, they open the opportunity for developing a new class of parallel applications driven by unpredictable data and events. The research issues in an adaptive parallel system are complex and interrelated. The nature and complexities of the relationships among these issues are not well researched and understood. Before developing adaptive applications or an infrastructure support for adaptive applications, these issues need to be investigated and studied in detail. One way of understanding and investigating these issues is by modeling and simulation. A model for adaptive parallel systems has been developed to enable the investigation of the impact of malleable workloads on its performance. The model can be used to determine how different model parameters impact the performance of the system and to determine the relationships among them Subsequently, a discrete event simulator has been developed to numerically simulate the model. Using the simulator, the impact of the variation in the number of malleable jobs in the workload, the flexibility, the negotiation cost, and the adaptation cost on system performance have been studied. The results and conclusions of these simulation experiments are presented in this dissertation. In general, the simulation results reveal that the performance improves with an increase in the number of malleable jobs in a workload, and that the performance saturates at a certain percentage of rigid to malleable jobs mix. A high percentage of malleable jobs is not necessary to achieve significant improvement in performance. The performance in general improves as the flexibility increases up to a certain point; then, it saturates. The negotiation cost impacts the performance, but not significantly. The number of negotiations for a given workload increases as number of malleable jobs increases up to a certain point, and then it decreases as number of malleable jobs increases further. The performance degrades as the application adaptation cost increases. The impact of the application adaptation cost on performance is much more significant compared to that of the negotiation cost.

Grid computing, like other technologies of the Information Technology, was created and developed in the mid 90 in the academic scope. The idea of this technology is to use computer resources without worrying about acquisition new resources and physical location. The focus of computational grids is associated with the execution of applications that demand high computing power or adapt to distributed environments. This makes the environment dynamic and heterogeneous, characteristics that make resource management, scheduling and fault tolerance a great challenge. Grid applications are usually programmed through a framework of grid computing. In this work we present TUXUR, designed to manage the execution of tasks in computing grids. Theis framework is specialized in malleable tasks that allow being divided into independent subtasks of known size. The framework dynamically adjusts the size of the subtasks within the resources made available by grid. The main objective of this adjustment is to try to maximize the use of available computational power, balancing the workload of the components of the grid, according to the capacity of each one. The results of the evaluation show that this goal was achieved, maximizing resource utilization and decreasing the final execution time. / Grades de computadores, como outras tecnologias de Tecnologia da Informação, foi criada e desenvolveu-se em meados dos anos 90 no âmbito acadêmico. A ideia desta tecnologia é utilizar os recursos de computadores, sem se preocupar com a aquisição de novos recursos e localização física. O foco das grades computacionais está associado à execução de aplicações que demandam alto poder computacional ou se adaptam a ambientes distribuídos. Isto torna o ambiente dinâmico e heterogêneo, características que fazem a gerência de recursos, escalonamento e tolerância a falhas um grande desafio. Aplicações de grades são geralmente programadas através de um framework de computação em grade. Neste trabalho apresentamos o TUXUR, projetado para gerenciar a execução de tarefas em grades computacionais. O framework é especializado em tarefas maleáveis, que permitem ser divididas em subtarefas independentes de tamanho conhecido. O framework ajusta dinamicamente o tamanho das subtarefas de acordo com os recursos disponibilizados pela grade. O principal objetivo deste ajuste é tentar maximizar a utilização do poder computacional disponibilizado, equilibrando a carga de trabalho entre os componentes da grade, de acordo com a capacidade de cada um. Os resultados encontrados na avaliação evidenciam que esse objetivo foi alcançado, aproveitando ao máximo a utilização dos recursos e diminuindo o tempo final de execução.

Product configuration systems (PCS) have the ability to significantly streamline the internal sales process within engineering-to-order (ETO) companies due to its ability to e.g. automate design and quotation processes. This is made possible through the accumulation of product specific knowledge put into a software which is used to create customer adaptable products at lower costs. PCS development is regarded resource heavy endeavors, and many projects have thus a hard time achieving an overall profitability. Recent studies have tried to establish frameworks that supports companies in achieving successful implementation processes. However, these studies mainly focus on technical implications and monetary benefits while lacking to establish and consider a comprehensive picture for the likelihood of PCS success. Thereby, this case study establishes a holistic framework for executives of ETO companies to consider when deciding on whether to invest in a PCS. The findings show that PCS provides benefits to its adopting organization by reducing engineering time and lead time during the sales process, increasing product specification quality, improving knowledge facilitation, contributing to the development of a streamlining mindset among its employees and provide the organization with an increased digital agility. For the organization to reap these benefits, it is highly dependent on its current setting (e.g. available resources, competences, organizational identity etc.), which should be evaluated thoroughly before deciding for investment. The study show that PCS investment should, in addition to streamlining sales process, be seen as a strategic investment. In a society influenced by digital solutions, PCS investment can be regarded a catalyst for organizations to become malleable, which have been suggested as a prerequisite for organizations in order to adopt to a digitally driven business environment. Additionally, implementing a PCS showed to contribute to the three pillars of sustainability by streamlining both the sales process as well as the, to some extent, assembly and production processes.

Many attempts have been made to determine what factors are most important in one’s potential for learning to read. These have been investigated for the purpose of determining effective instructional procedures. This chapter on literacy development aims to problematize instructional approaches that emphasize children’s deficits and, instead, make more visible approaches that build on children’s strengths, regardless of their individual differences. A fundamental belief must be that literacy is teachable and, for all children, learnable. This chapter will delineate those aspects of literacy that are malleable, evidenced by case studies and research review, and will suggest pathways (i.e., skills, strategies, and procedures) that are most effective for teachers and researchers to pursue. It describes connections to the broad field of deafness and literacy development and implications for teachers, administrators, service providers, and others concerned with the literacy success of deaf and hard-of-hearing children.