Graphs provide powerful abstractions, and are widely used in different areas. There has been an increasing demand in using the graph data model to represent data in many applications such as network management, web page analysis, knowledge graphs, social networks. These graphs are usually dynamic and represent the time evolving relationships between entities. Enforcing and maintaining data quality in graphs is a critical task for decision making, operational efficiency and accurate data analysis as recent studies have shown that data scientists spend 60-80% of their time cleaning and organizing data [2]. This effort motivates the need for effective data cleaning tools to reduce the user burden. The study of data quality management focuses along a set of dimensions, including data consistency, data deduplication, information completeness, data currency, and data accuracy. Achieving all these data characteristics is often not possible in practice due to personnel costs, and for performance reasons. In this thesis, we focus on tackling three problems in two data quality dimensions: data consistency and data deduplication. To address the problem of data consistency over temporal graphs, we present a new class of data dependencies called Temporal Graph Functional Dependency (TGFDs). TGFDs generalize functional dependencies to temporal graphs as a sequence of graph snapshots that are induced by time intervals, and enforce both topological constraints and attribute value dependencies that must be satisfied by these snapshots. We establish the complexity results for the satisfiability and implication problems of TGFDs. We propose a sound and complete axiomatization system for TGFDs. We also present efficient parallel algorithms to detect inconsistencies in temporal graphs as violations of TGFDs. To address the data deduplication problem, we first address the problem of key discovery for graphs. Keys for graphs use topology and value constraints to uniquely identify entities in a graph database and keys are the main tools for data deduplication in graphs. We present two properties that define a key, including minimality and support and an algorithm to mine keys over graphs via frequent subgraph expansion. However, existing key constraints identify entities by enforcing label equality on node types. These constraints can be too restrictive to characterize structures and node labels that are syntactically different but semantically equivalent. Lastly, we propose a new class of key constraints, Ontological Graph Keys (OGKs) that extend conventional graph keys by ontological subgraph matching between entity labels and an external ontology. We study the entity matching problem with OGKs. We develop efficient algorithms to perform entity matching based on a Chase procedure. The proposed dependencies and algorithms in this thesis improve consistency detection in temporal graphs, automate the discovery of keys in graphs, and enrich the semantic expressiveness of graph keys. / Dissertation / Doctor of Science (PhD)

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This can be considered as a multidisciplinary research where ideas from Operations Research, Data Science and Logic came together to solve an inconsistency handling problem in a special type of ontology. / High data quality is a prerequisite for accurate data analysis. However, data inconsistencies often arise in real data, leading to untrusted decision making downstream in the data analysis pipeline. In this research, we study the problem of inconsistency detection and repair of the Ontology Multi-dimensional Data Model (OMD). We propose a framework of data quality assessment, and repair for the OMD. We formally define a weight-based repair-by-deletion semantics, and present an automatic weight generation mechanism that considers multiple input criteria. Our methods are rooted in multi-criteria decision making that consider the correlation, contrast, and conflict that may exist among multiple criteria, and is often needed in the data cleaning domain. After weight generation we present a dynamic programming based Min-Sum algorithm to identify minimal weight solution. We then apply evolutionary optimization techniques and demonstrate improved performance using medical datasets, making it realizable in practice. / Thesis / Master of Computer Science (MCS) / Accurate data analysis requires high quality data as input. In this research, we study inconsistency in an ontology known as Ontology Multi-dimensional Data (OMD) Model and propose algorithms to repair them based on their automatically generated relative weights. We proposed two techniques to restore consistency, one provides optimal results but takes longer time compared to the other one, which produces sub-optimal results but fast enough for practical purposes, shown with experiments on datasets.

Crayfish throughout North America, Europe, and Asia host assemblages of obligate ectosymbiotic annelid worms called branchiobdellidans. The work presented here is a detailed experimental and observational study of the ecological interactions between crayfish and their worms. In a comprehensive literature review, I show that branchiobdellidans have complex and context-dependent effects on their hosts, serving as both beneficial cleaners and tissue-consuming parasites. Using a field survey and laboratory experiments, I provide novel evidence for age-specific resistance as an adaptation to maximize life-long benefits of a mutualism. Specifically, I show that Cambarus crayfish display a consistent ontogenetic shift in resistance to the colonization of branchiobdellidans and this shift likely reflects underlying changes in the costs and benefits of symbiosis. I then show that this change in host resistance creates predictable patterns of symbiont diversity and composition throughout host ontogeny. Host resistance limits within-host symbiont communities to a few weakly interacting species, whereas relaxed resistance leads to more diverse symbiont communities that have strong interactions among symbiont taxa. Thus, host resistance has direct effects on within-host symbiont community structure by selectively filtering colonizing species, and indirect effects by moderating the strength of interactions among symbionts. Lastly, in a detailed study of the worm Cambarincola ingens, I depict a symbiont dispersal strategy that yields highly predictable transmission dynamics during pairwise host-host encounters and shows that variation in transmission dynamics can be explained by the fitness outcomes for dispersing symbionts. Field observations revealed that worm reproduction is contingent on host size and intraspecific competition for preferred microhabitats. Using a predictive model that assumes transmission of symbionts only when current conditions yield fitness below a minimum threshold, I was able to predict individual transmission events much more accurately than a comparable null model that assumed a fixed probability of transmission. My work provides empirical support for the emerging trend among researchers that advocates the adaptation of general ecological frameworks to understand symbiont population structure and diversity, but my work also emphasizes the value of detailed natural history studies to uncover system-specific ecological and co-evolutionary processes such as partner control mechanisms, symbiont microhabitat selections, and symbiont dispersal strategies. / Ph. D.

En el trabajo con el título "Analytical study of accelerated light ageing and cleaning effects on acrylic and PVAc dispersion paints used in Modern and Contemporary Art" se han empleado diferentes técncias analíticas con el fin de optimizar protocolos experimentales para la caracterización de la estabilidad de acrílicos y acetatos de polivinilo (PVAc) frente a ensayos de envejecimeinto acelerado y tratamientos de limpieza. El estudio de los procesos de degradación causados por la exposición a la luz se ha desarrollado sobre una amplia seria de muestras acrílicas y vinílicas expuestas a dos tipos de envejecimiento acelerado con condiciones de envejecimiento artificail representativas de un envejecimiento natural. La información química y mecánica obtenida por ambos ensayos de envejecimiento acelerado permitió identificar procesos de degradación específicos tales como entrecruzamiento o escisión de cadenas. Las conclusiones obtenidas de forma general apuntan que los acrílicos son materiales más estables que los vinílicos y los estireno-acrílicos. Asimsismo, en este estudio se han aborado los efectos de los tratamientos de limpieza bien de base acuosa, bien con disolventes orgánicos, en las propiedades físico-qúimicas en muestras acrílicas y vinílicas. También se han evaluado otros métodos de limpieza tales como geles o emulsiones. Los resultados indican que los tratamientos acuosos extraen aditivos, afectan la morfología e inducen cambios en las propiedades mecánicas de las muestras. Estos efectos pueden ser reducidos con el uso de sistemas alternativos de limpieza. / De Sousa Ramos Félix Silva, M. (2011). Analytical study of accelerated light ageing and cleaning effects on acrylic and PVAc dispersion paints used in Modern and Contemporary Art [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/13829

Farmers markets (FM) have become increasingly popular almost tripling over the past two decades due to the rising interest in local and/or organic foods. Within this same time period, notable farmers market foodborne illness outbreaks; such as E. coli O157:H7 and strawberries and Salmonella and peas; have occurred, and emphasize the importance of food safety practices at farmers markets. Some farmers may be encouraged to follow Good Agricultural Practices (GAPs) to limit the contamination of fresh produce; however, GAPs programs are complex and also very driven by wholesale buyers. Furthermore, many FM growers are unfamiliar with GAPs or do not believe it is applicable to them. The Food Safety Modernization Act (FSMA) was passed in 2011, and shifted the food safety paradigm from a reactive to proactive approach introducing seven different rules including the Preventive Controls for Human Foods (PCHFR) and the Produce Safety Rule (PSR). Each FSMA rule does contain exemptions for smaller-scale operations (e.g., farms, facilities) that allows them to be excluded from the rule, or excluded from certain aspects of the rule. Generally, most FM vendors may satisfy exemptions from the FSMA regulations (e.g., be exempt from the FSMA Produce Safety Rule because of commodities); however, to our knowledge, no studies have assessed the regulatory compliance requirements of FM vendors to the FSMA regulations. This dissertation explored the regulatory requirements of FM vendors, and the accessibility of FSMA materials for these audiences. Additionally, due to the sudden and unprecedented global COVID-19 pandemic, an objective was added that explored how COVID-19 influenced behavior changes among this audience. Interviews were conducted and found that all vendors (100%) were exempt from the PCHFR and that most vendors (67%) were exempt from the PSR, some were qualified exempt (28%), and a few (5%) were covered. This study also found that farmers market vendors received information mainly from University Cooperative Extension sources. The COVID-19 pandemic greatly impacted hygiene and health practices at FMs. Market personnel (managers and vendors) implemented many different hygiene and health practices at their markets. The major source of COVID-19 food safety information for market personnel was local and federal government; as well as University Cooperative Extension. Accessibility analyses showed that many FM or COVID-19 resources were not accessible due to populations that rely on produce safety resources generated by Cooperative Extension due to (i) navigation or web accessibility errors, (ii) high literacy level requirements, and (iii) lack of keep (i.e., resources were not up-to-date, or continuously managed or monitored). These findings will inform the development of FM targeted resources, that are also, accessible to a more diverse and inclusive audience. One example is a produce safety resource on the updated agricultural water requirements that is developed to an 8th grade reading level, with no broken links or additional navigations errors, and if a PDF version is available, proper headers and titles. / Doctor of Philosophy / Farmers markets (FMs) have increased in popularity over the two decades with because of interest by consumers to support local agriculture, buy organic products, or because they believe these foods to be safer from bacteria and viruses. Shopping at a FMs does not necessarily make the products any safer compared to buying it from a grocery store. It is important that farmers markets follow proper food safety practices during the growing, harvesting, and preparation of produce for sale. One example is the prevention of animal feces from getting on the produce or in a water source that would be used. Another would be to follow proper hygiene practices such as handwashing after using the bathroom. These two examples and others are detailed in a law passed by President Obama in 2011 called the Food Safety Modernization Act (FSMA), which allows the Food and Drug Administration to begin its proactive instead of reactive food safety approach. FSMA does not have to be followed by all food entities. Depending on how much a farm makes in revenue (<$25,000) or if they grow products deemed as "not risky,", they may be exempt. These types of products such as potatoes, beets, and corn are safer because they will be cooked before consumption killing any bacteria or viruses that may exist. Other products such as romaine lettuce and tomatoes are usually consumed fresh without cooking and are thus riskier if there are any bacteria or viruses on it. Interviews were conducted to understand if farmers market vendors need to comply with FSMA. Most vendors are not required to follow FSMA because they gross less than $25,000 or their products were already covered by other food safety regulations such as meat being covered by the USDA. Additionally, how the COVID-19 pandemic influenced FMs was explored. Two surveys, one for vendors and one for managers, were distributed to stakeholders. FMs adapted really well to the challenging COVID-19 landscape and implemented COVID-19 preventive measures such as social distancing, mask wearing, and providing hand sanitizer and handwashing stations to continue to operate and keep their customers and employees safe. After understanding the characteristics and the unique challenges to food safety implementation that these market personnel may face, additional research was done to understand if currently available resources were accessible. Accessibility was evaluated using website and PDF accessibility checkers and a readability level checker. Resources should be easy to navigate and written to around a 8th grade level to make it easy to understand. There is a lack of well-crafted, accessible resources that address the unique challenges that farmers market personnel may face. These considerations should be considered when creating these materials.

Detta examensarbete fokuserar på att minska vikten på en undervattens rengöringsrobot (bottensug) som kallas W50. För närvarande väger den ungefär 28 kg, och vårt mål är att reducera vikten till strax under 20 kg. Om det primära målet inte uppnås, kommer detta arbete att presentera alternativa förslag eller koncept som kan underlätta för WEDA AB att fortsätta sin strävan efter en lättare och mer effektiv bottensug. Genom en kombination av konstruktionsanalys, materialval och marknadsundersökningar av andra möjliga tillverkare undersöker vi olika möjligheter att minska vikten utan att kompromissa med prestanda och funktionalitet så mycket. Resultatet och förslagen från detta arbete kommer att bidra till att optimera W50:s totala vikt, samtidigt som den fortsätter att vara kraftfull och effektiv jämfört med sina konkurrenter. Produktutveckling och produktframtagning har varit ett lyckat försök, nya komponenter har tagits fram och befintliga produkter har utvecklats med nya material eller omkonstrueras. / This thesis focuses on reducing the weight of an underwater cleaning robot (bottom suction) called W50. Currently it weighs approximately 28g, and our goal is to reduce the weight to just under 20 kg. If the primary goal is not achieved, this work will present alternative proposals or concepts that can make it easier for Weda AB to continue its quest for a lighter and more efficient bottom suction. Through a combination of design analysis material selection and market research of other possible manufacturers, we investigate various possibilities to reduce weight without compromising performance and functionality as much. The results and suggestions from this work will help to optimize the overall weight of the W50, while continuing to be powerful and efficient compared to its competitors. Product Development has been a successful attempt, new components have been developed and existing products have been developed with new materials or redesigned.