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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Hybrid Question Answering over Linked Data

Bahmid, Rawan 13 August 2018 (has links)
The emergence of Linked Data in the form of knowledge graphs in RDF has been one of the most recent evolutions of the Semantic Web. This led to the development of question answering systems based on RDF and SPARQL to allow end users to access and benefit from these knowledge graphs. However, a lot of information on the Web is still unstructured, which restricts the ability of answering questions whose answer does not exist in a knowledge base. To tackle this issue, hybrid question answering has emerged as an important challenge. In fact, hybrid question answering entails the task of question answering by combining both structured (RDF) and unstructured knowledge sources (text) into one answer. This thesis tackles hybrid question answering based on natural language questions. It focuses on the analysis and improvement of an open source system called HAWK, identifies its limitations and provides solutions and recommendations in the form of a generic question-answering pipeline called HAWK_R. Our system mostly uses heuristic methods, patterns and the ontological schema and knowledge base and provides three main additions: question classification, annotation and answer verification and ranking based on query content. Our results show a clear improvement over the original HAWK based on several Question Answering over Linked Data (QALD) competitions. In fact, our methods are not limited to HAWK and can also help increase the performance of other question answering systems.
72

HDT crypt: Compression and Encryption of RDF Datasets

Fernandez Garcia, Javier David, Kirrane, Sabrina, Polleres, Axel, Steyskal, Simon January 2018 (has links) (PDF)
The publication and interchange of RDF datasets online has experienced significant growth in recent years, promoted by different but complementary efforts, such as Linked Open Data, the Web of Things and RDF stream processing systems. However, the current Linked Data infrastructure does not cater for the storage and exchange of sensitive or private data. On the one hand, data publishers need means to limit access to confidential data (e.g. health, financial, personal, or other sensitive data). On the other hand, the infrastructure needs to compress RDF graphs in a manner that minimises the amount of data that is both stored and transferred over the wire. In this paper, we demonstrate how HDT - a compressed serialization format for RDF - can be extended to cater for supporting encryption. We propose a number of different graph partitioning strategies and discuss the benefits and tradeoffs of each approach.
73

Framework pre Android aplikácie založené na geolokácii a používajúce Linked Data / Framework for geolocation-based Android applications using Linked Data

Snoha, Matej January 2018 (has links)
Title: Framework for geolocation-based Android applications using Linked Data Author: Bc. Matej Snoha The aim of this thesis is to design and implement a framework for geolo- cation based mobile applications using Linked Data. Introduced are Linked Data technologies in the context of mobile application develop- ment, data modeling, and geographical queries. This work follows the software development lifecycle from requirement gathering, software analysis, design of the application framework and its individual compo- nents, up to the implementation of required functionality and subsequent deployment and evaluation of the functional application framework. The resulting implementation of the framework consists of a mobile applica- tion that displays nearby places from Linked Data datasets on a map and a cloud service with a repository of required definitions. It serves to demonstrate functionality of the theoretical part of the work in real-life scenarios.
74

Visual knowledge graph management tool / Visual knowledge graph management tool

Woska, Aleš January 2016 (has links)
Linked data are usually visualized as graph structures which are useful for browsing resources but less useful for viewing structured data. This thesis proposes a solution how to visualize linked data in a tabular structure. The goal of the visualization is to make an orientation in data easier for a user. A tabular structure for specific data can be designed and managed in a graphic editor. Visualized data can be checked for errors and can be edited to obtain a script which fixes them. Powered by TCPDF (www.tcpdf.org)
75

On techniques for pay-as-you-go data integration of linked data

Christodoulou, Klitos January 2015 (has links)
It is recognised that nowadays, users interact with large amounts of data that exist in disparate forms, and are stored under different settings. Moreover, it is true that the amount of structured and un-structured data outside a single well organised data management system is expanding rapidly. To address the recent challenges of managing large amounts of potentially distributed data, the vision of a dataspace was introduced. This data management paradigm aims at reducing the complexity behind the challenges of integrating heterogeneous data sources. Recently, efforts by the Linked Data (LD) community gave rise to a Web of Data (WoD) that interweaves with the current Web of documents in a way that it is useful for data consumption by both humans and computational agents. On the WoD, datasets are structured under a common data model and published as Web resources following a simple set of guidelines that enables them to be linked with other pieces of data, as well as, to be annotated with useful meta data that help determine their semantics. The WoD is an evolving open ecosystem including specialist publishers as well as community efforts aiming at re-publishing isolated databases as LD on the WoD, and annotating them with meta data. The WoD raises new opportunities and challenges. However, currently it mostly relies on manual efforts for integrating the large amounts of heterogeneous data sources on the WoD. This dissertation makes the case that several techniques from the dataspaces research area (aiming at on-demand integration of data sources in a pay-as-you-go fashion) can support the integration of heterogeneous WoD sources. In so doing, this dissertation explores the opportunities and identifies the challenges of adapting existing pay-as-you-go data integration techniques in the context of LD. More specifically, this dissertation makes the following contributions: (1) a case-study for identifying the challenges when existing pay-as-you-go data integration techniques are applied in a setting where data sources are LD; (2) a methodology that deals with the 'schema-less' nature of LD sources by automatically inferring a conceptual structure from a given RDF graph thus enabling downstream tasks, such as the identification of matches and the derivation of mappings, which are, both, essential for the automatic bootstrapping of a dataspace; and (3) a well-defined, principled methodology that builds on a Bayesian inference technique for reasoning under uncertainty to improve pay-as-you-go integration. Although the developed methodology is generic in being able to reason with different hypothesis, its effectiveness has only been explored on reducing the uncertain decisions made by string-based matchers during the matching stage of a dataspace system.
76

A Role for Integrin-linked Kinase In Oligodendrocyte Mediated Myelination of the Central Nervous System

Michalski, John-Paul January 2014 (has links)
The interplay between oligodendrocyte (OL) and extracellular matrix (ECM) is critical to the proper maturation of this unique cell type. Recent work has established the β1 integrin-signaling pathway, a mediator for ECM/OL interactions, as an essential component of myelin sheath formation in the central nervous system (CNS). A major downstream effector of β1 integrin is integrin-linked kinase (ILK), an adaptor and structural platform protein. Herein, we (1) generated a model system to study ILK in vivo and (2) employed the model to elucidate ILK’s role in regulating OL biology. To assess the importance of ILK in OL-mediated myelination, we ablated ILK in primary OLs. ILK loss delayed morphological maturation and led to filamentous actin accumulation in the processes and cell body. Further, we noted an upregulation in RhoA activity, with pathway inhibition rescuing an OL subset. We next moved our studies in vivo. First, we assessed the proteolipid protein promoter’s utility as OL-specific Cre driver. Protocols established, we generated an ILK conditional knockout line (Ilk cKO). Ultrastructural analysis of Ilk cKO optic nerves revealed increased number of amyelinated nerve fibers at P14 with subsequent recovery by P28. The observed transient defects were due neither to a loss nor a gain in total number of mature or progenitor OLs. To rationalize recovery, we grew ILK-depleted OLs on an “inert” substrate. Here, while morphology improved, ILK-depleted OLs were characterized by enlarged and sluggish growth cones as well as microtubule disorganization. Taken together, our data suggests a role for ILK in regulating the morphological maturation of OLs both in vitro and in vivo, the loss of which results in defective OL branching and membrane formation with phenotype and subsequent recovery dependent upon niche complexity.
77

Transformace a publikace otevřených a propojitelných dat / Transformation and publication of Open and Linked Data

Nohejl, Petr January 2013 (has links)
The principle of Open Data and Linked data is in growing interest of many organizations, developers and even government institutions. This work is aimed on providing actual information about development of Open and Linked data, further there are introduced featured tools for creating, manipulating, transformation and other operations regarding Open and Linked Data. Finally, there is description of development of Linked Data application based on universal visualization system Payola.
78

Linked open data pro informace veřejného sektoru / Linked Open Data for Public Sector Information

Mynarz, Jindřich January 2012 (has links)
The diploma thesis introduces the domain of proactive disclosure of public sector information via linked open data. At the start, the legal framework encompassing public sector information is expounded along with the basic approaches for its disclosure. The practices of publishing data as open data are defined as an ap- proach for proactive disclosure that is based on the application of the principle of openness to data with the goal to enable equal access and equal use of the data. The reviewed practices range from necessary legal actions, choices of appropriate technologies, and ways in which the technologies should be used to achieve the best data quality. Linked data is presented as a knowledge technology that, for the most part, fulfils the requirements on open technology suitable for open data. The thesis extrapolates further from the adoption of linked open data in the public sector to recognize the impact and challenges proceeding from this change. The distinctive focus on the side supplying data and the trust in the transformative effects of technological changes are identified among the key sources of these challenges. The emphasis on technologies for data disclosure at the expense of a more careful attention to the use of data is presented as a possible source of risks that may undermine the...
79

An Enzyme-Linked Immunosorbent Assay (ELISA) for Pantothenate

Smith, Allen H. 01 May 1981 (has links)
An enzyme-linked immunosorbent assay (ELISA) for pantothenate has been developed. Antibodies induced in rabbits against bovine serum albumin-pantothenate conjugate were specifically purified by affinity chromatography. This process served to reduce the amount of endogenous pantothenate attached to the antibody, as well as to purify the antibody. The purified antibodies were covalently linked to alkaline phosphatase (Sigma type VII) with glutaraldehyde (0.05% aqueous solution). An immobilized pantothenate substrate was first obtained by attaching human serum albumin-pantothenate conjugate to the surface of polystyrene culture tubes by passive adsorption. The binding of the enzyme labelled antibody (E-AB} to this substrate is proportionately inhibited by free pantothenate as standards or as samples for analysis. The inhibition of E-AB immobilization was quantitated at 405 nm by the hydrolysis of p-nitrophenyl phosphate as indicated by the formation of p-nitrophenol. A standard curve was plotted on log logit paper, and was linear in the range of 2 through 1000 ng pantothenate. Initial experiments show that the ELISA will be useful in assessing pantothenate in deproteinized blood samples and in food extracts.
80

Integrin-linked Kinase (ILK) expression in moderately differentiated human oesophageal squamous carcinoma cell lines: A growth factor modulation, activity and link to adhesion

Driver, Glenn Alan 19 May 2008 (has links)
Abstract Integrin-linked Kinase (ILK) is an integrin-associated protein kinase, which regulates growth factor-signalling pathways and cell-ECM adhesion events. Abrogated ILK expression or activity has been implicated in contributing to oncogenic transformation. We examined the role played by ILK in growth factor-stimulated and integrin signalling events in five human oesophageal squamous cell carcinoma cell lines (HOSCCs), known to overexpress the EGF receptor. Western blot analysis revealed the presence of ILK (59kDa) in all the moderately differentiated HOSCC lines. ILK1 was confirmed as being the predominant isoform. Densitometrically analysed Western blots showed that, per unit of protein, ILK is expressed uniformly across the cell lines under standard culture conditions. Following EGF (10 ng/ml) and TGFβ1 (1 ng/ml) treatment, ILK expression increased in all five HOSCCs. Indirect immunofluorescence microscopy showed the majority of ILK to localise at a cytoplasmic/nuclear level, with a proportion of ILK localising at the membrane, which resembled the distribution pattern of the β3 integrin subunit. This membranal distribution most likely follows that of the adhesion plaques although lesser, and variable, amounts were also identified throughout the cytoplasm. The functionality of the ILK1 kinase domain was demonstrated using myelin basic protein (MBP)-based kinase assays. EGF and TGFβ1 treatment produced an increase in ILK activity in the WHCO3 cell line of 3.5 fold, but a decrease in activity in the other cell lines, which are suggested to involve the actions of PTEN. The identification of nuclear ILK was surprising, and the mechanism for nuclear ILK localisation was suggested to involve a caveolae-associated protein, caveolin-1. Cell adhesion assays revealed that KP-392-mediated inhibition of ILK resulted in a nonsignificant reduction in cell adhesion to collagen and fibronectin. These data provide distinctive evidence for the influence of growth factors on ILK expression, but a duality in the effect on ILK activity. This apparent dichotomy is noteworthy and may be of particular relevance in HOSCC. It is further suggested that KP-392-induced ILK inhibition destabilises the αβ integrin heterodimer and that PI3K acts upstream of ILK-mediated cell adhesion events in HOSCCs. This suggests that ILK mediates integrin associated processes in human oesophageal SCC cell lines.

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