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Despite the abundance of literature on free and open source software (FOSS), its impact on individual developers’ productivity is a topic that is under explored. Moreover, the traditional measures of developers’ productivity are based on objective measures (lines of code) instead of subjective measures (self-rated productivity). To bridge this gap and add new knowledge to existing literature, the study explored the impact of FOSS on developers’ productivity based on self-rated productivity measure. Hence, the study used an exploratory approach of qualitative research, a theoretical framework and interviews as a method of data collection. The findings indicate that FOSS actually has a positive impact on developers’ productivity and the rate of adoption is high among young and experienced developers. However, the risks and security challenges that come with FOSS based on its open model actually creates room for lack of trust and thus can reduce the adoption rate. Though FOSS has improved developers’ productivity when it comes to software development, the issues of poor documentation and lack of documentation encountered when trying to modify or enhance FOSS actually hinder developers’ productivity. Hence the free and open source software community should come up with ways of tackling these challenges in order for the developers to be more productive.

Investigations are increasingly conducted online by not only novice sleuths but also by professionals -- in both competitive and collaborative environments. These investigations rely on publicly available information, called open source intelligence (OSINT). However, due to their online nature, OSINT investigations often present coordination, technological, and ethical challenges. Through semi-structured interviews with 14 professional OSINT investigators from nine different organizations, we examine the social collaboration and competition patterns that underlie their investigations. Instead of purely competitive or purely collaborative social models, we find that OSINT organizations employ a combination of both, and that each has its own advantages and disadvantages. We also describe investigators' use of and challenges with existing OSINT tools. Finally, we conclude with a discussion on supporting investigators' with more appropriable tools and making investigations more social. / Master of Science / Investigations are increasingly conducted online by not only novice investigators but also by professionals, such as private investigators or law enforcement agents. These investigations are conducted in competitive environments, such as Capture The Flag (CTF) events where contestants solve crimes and mysteries, but also in collaborative environments, such as teams of investigative journalists joining skills and knowledge to uncover and report on crimes and/or mysteries. These investigations rely on publicly available information called open source intelligence (OSINT) which includes public social media posts, public databases of information, public satellite imagery...etc. OSINT investigators collect and authenticate open source intelligence in order to conduct their investigations and synthesize the authenticated information they gathered to present their findings. However, due to their online nature, OSINT investigations often present coordination, technological, and ethical challenges. Through semi-structured interviews with 14 professional OSINT investigators from nine different organizations, we examine how these professionals conduct their investigations, and how they coordinate the different individuals and investigators involved throughout the process. By analyzing these processes, we can discern the social collaboration and competition patterns that enable these professionals to conduct their investigations. Instead of purely competitive or purely collaborative social models, we find that OSINT organizations employ a combination of both, and that each has its own advantages and disadvantages. In other words, professional OSINT investigators compete with each other but also collaborate with each other at different stages of their investigations or for different investigative tasks. We also describe investigators' use of and challenges with existing OSINT tools and technologies. Finally, we conclude with a discussion on supporting investigators with tools that can adapt to their different needs and investigation types and making investigations more social.

No / The surprise advent of the peer-to-peer payment system Bitcoin in 2009 has raised various concerns regarding its relationship to established economic market ideologies. Unlike fiat currencies, Bitcoin is based on open-source software; it is a secure cryptocurrency, traded as an investment between two individuals over the internet, with no bank involvement. Computationally, this is a very innovative solution, but Bitcoin’s popularity has raised a number of security and trust concerns among mainstream economists. With cities and countries, including San Francisco and Germany, using Bitcoin as a unit of account in their financial systems, there is still a lack of understanding and a paucity of models for studying its use, and the role Bitcoin might play in real physical economies. This project tackles these issues by analysing the ramifications of Bitcoin within economic models, by building a computational model of the currency to test its performance in financial market models. The project uses established agent-based modelling techniques to build a decentralised Bitcoin model, which can be ‘plugged into’ existing agent-based models of key economic and financial markets. This allows various metrics to be subjected to critical analysis, gauging the progress of digital economies equipped with Bitcoin usage. This project contributes to the themes of privacy, consent, security and trust in the digital economy and digital technologies, enabling new business models of direct relevance to NEMODE. As computer scientists, we consider Bitcoin from a technical perspective; this contrasts with and complements other current Bitcoin research, and helps document the realizable risks Bitcoin and similar currencies bring to our current economic world. This report outlines a comprehensive collection of risks raised by Bitcoin. Risk management is a discipline that can be used to address the possibility of future threats which may cause harm to the existing systems. Although there has been considerable work on analysing Bitcoin in terms of the potential issues it brings to the economic landscape, this report performs a first ever attempt of identifying the threats and risks posed by the use of Bitcoin from the perspective of computational modeling and engineering. In this project we consider risk at all levels of interaction when Bitcoin is introduced and transferred across the systems. We look at the infrastructure and the computational working of the digital currency to identify the potential risks it brings. Additional information can be seen in our forthcoming companion report on the detailed modeling of Bitcoin.

The Xilinx Partial Reconfiguration tool kits have been instrumental for performing a wide variety of research on Xilinx FPGAs. These tool kits provide a methodology for creating rectangular partial reconfiguration modules that can be swapped in and out of a static baseline design with one or more PR slots. This thesis presents a new PR toolkit called OpenPR that, for starters, provides similar functionality to the Xilinx PR tool kits. The distinguishing feature of this toolkit is that it is being released as open source, and is intended to be customizable to the needs of researchers. OpenPR has been designed to be easy to use, extensible, portable, and compatible with a wide range of Xilinx software and devices. Aside from supporting the slot-based PR paradigm, OpenPR also provides a solid base for further research into partial reconfiguration and FPGA productivity oriented design tools. / Master of Science

Bitstream generation has traditionally been the single part of the FPGA design flow that has not been openly reproduced. This work enables bitstream generation for "limited" resources without reverse-engineering or violating End-User License Agreement terms. Two use cases in particular have motivated this work--embedded bitstream generation and fast bitstream generation for small changes in design--both of which are not feasible with the Xilinx's bitstream generation tool. The approach is to first define a set of primitives which can implement an arbitrary digital design and create a library of micro-bitstreams of the primitives. An input design is then mapped to the set of primitives and a bitstream for the design is generated by merging the corresponding micro-bitstreams. This work uses architectural primitives. Initial support is limited to the Virtex-5 and Virtex-7 family of FPGAs from Xilinx, but it can be extended to other Xilinx architectures. Nearly all routing resources in the device, as well as the most common logic resources are supported by this work. / Master of Science

Microalgae are photosynthetic organisms considered to be one of the most promising high-value chemicals and biofuel-producing organisms. However, there are several challenges for the widespread implementation of industrial processes using microalgae. The work presented in this dissertation proposes solutions to the different challenges involving the use of microalgae as microbial cell factories. To investigate the application of anaerobic digestion as a way to generate nutrients for microbial growth, salmon offal was used as substrate for anaerobic digestion, and soil from a flooded run-off pond on the Virginia Tech campus in Blacksburg, VA. A fast reduction in volatile solids and the short-chain fatty acid production profile is favorable for the growth of microalgae. A novel algae strain Scenedesmus sp. A6 was isolated from a decorative waterfountain in a hotel in Madison, IN. Mixotrophic growth trials were conducted using wastewater from the salmon offal digestion, that demostrated the A6 isolate grows six times faster in the wastewater then autotrophically. Bioassays of ethanolic cell extracts of A6 cultures demonstrated antimicrobial activity against E. coli cells at concentrations above 50 µg/ml. Genome sequencing and assembly revealed multiple copies of genes involved with acetate and ammonia metabolism, and several genes involved with secondary metabolite synthesis. An alternative to the high capital investment of photobioreactors for the cultivation of microalgae is the use of open-source and open-hardware bioreactor controller. Here, the concept of an open-hardwate bioreactor control called ``BioBrain'' is introduced. The BioBrain device is based on the Arduino Mega micro-controller board, and is capable of monitoring and controlling culture conditions during simple strain characterization studies, with an estimated construction cost of less than $800 USD. Finally, a new primer design tool for the ligation-independant cloning technique 𝜆-PCR was developed called lambdaPrimeR. The contributions of this work are the discovery and development of different tools that can overcome the challenges of the use of microalgae as microbial cell factories in industrial processes. / Ph. D. / Microalgae are single-celled organisms capable of photosynthesis and have the potential to revolutionize fuel and high-value chemical production. However, the high process costs involving the cultivation and biomass harvesting of these organisms limits the number of industrial applications of microalgae. Therefore, reduction of the overall costs of any process involving microalgae is vital for the widespread use of these organisms in industry. On this dissertation, I explore different approaches to tackle the challenges of using microalgae as a high-value chemicals cell factories. First, the use of anaerobic digestion of salmon offal to generate low-cost nutrients for algae growth is successfully demonstrated, with the discovery of a novel algae isolate Scenedesmus sp. A6, capable of very robust growth on the anaerobic digestion wastewater. Further characterization of this novel isolate showed that it has antimicrobial activity against E. coli cells. Therefore, the Scenedesmus sp. A6 isolate has the potential to be used as a high-value chemical cell factory. Reduction in equipment and instrumentation costs was also achieved by the design and construction of an open-hardware and open-source bioreactor controller device called the “BioBrain”, and a low-cost modular bubble column photobioreactor called “The Big Large Tube”. Together, these two devices represent a significant reduction in equipment costs for the cultivation of microalgae. Finally, an open-source Bioinformatics tool called “lambdaPrimeR” was developed to facilitate the use of a novel Genetic Engineering technique called λ-PCR, that has the potential to make genetic engineering of microalgae much easier.