Scaling geospatial searches in large spatial databases

Modern geographical databases, which are at the core of geographic information systems (GIS), store a rich set of aspatial attributes in addition to geographic data. Typically, aspatial information comes in textual and numeric format. Retrieving information constrained on spatial and aspatial data from geodatabases provides GIS users the ability to perform more interesting spatial analyses, and for applications to support composite location-aware searches; for example, in a real estate database: “Find the nearest homes for sale to my current location that have backyard and whose prices are between $50,000 and $80,000”. Efficient processing of such queries require combined indexing strategies of multiple types of data. Existing spatial query engines commonly apply a two-filter approach (spatial filter followed by nonspatial filter, or viceversa), which can incur large performance overheads. On the other hand, more recently, the amount of geolocation data has grown rapidly in databases due in part to advances in geolocation technologies (e.g., GPS-enabled smartphones) that allow users to associate location data to objects or events. The latter poses potential data ingestion challenges of large data volumes for practical GIS databases. In this dissertation, we first show how indexing spatial data with R-trees (a typical data pre-processing task) can be scaled in MapReduce—a widely-adopted parallel programming model for data intensive problems. The evaluation of our algorithms in a Hadoop cluster showed close to linear scalability in building R-tree indexes. Subsequently, we develop efficient algorithms for processing spatial queries with aspatial conditions. Novel techniques for simultaneously indexing spatial with textual and numeric data are developed to that end. Experimental evaluations with real-world, large spatial datasets measured query response times within the sub-second range for most cases, and up to a few seconds for a small number of cases, which is reasonable for interactive applications. Overall, the previous results show that the MapReduce parallel model is suitable for indexing tasks in spatial databases, and the adequate combination of spatial and aspatial attribute indexes can attain acceptable response times for interactive spatial queries with constraints on aspatial data.

Algorithms for efficient transaction management and consistent queries in client -server semantic object-oriented parallel databases

Large read-only or read-write transactions with a large read set and a small write set constitute an important class of transactions used in such applications as data mining, data warehousing, statistical applications, and report generators. Such transactions are best supported with optimistic concurrency, because locking of large amounts of data for extended periods of time is not an acceptable solution. The abort rate in regular optimistic concurrency algorithms increases exponentially with the size of the transaction. The algorithm proposed in this dissertation solves this problem by using a new transaction scheduling technique that allows a large transaction to commit safely with significantly greater probability that can exceed several orders of magnitude versus regular optimistic concurrency algorithms. A performance simulation study and a formal proof of serializability and external consistency of the proposed algorithm are also presented.^ This dissertation also proposes a new query optimization technique (lazy queries). Lazy Queries is an adaptive query execution scheme which optimizes itself as the query runs. Lazy queries can be used to find an intersection of sub-queries in a very efficient way, which does not require full execution of large sub-queries nor does it require any statistical knowledge about the data.^ An efficient optimistic concurrency control algorithm used in a massively parallel B-tree with variable-length keys is introduced. B-trees with variable-length keys can be effectively used in a variety of database types. In particular, we show how such a B-tree was used in our implementation of a semantic object-oriented DBMS. The concurrency control algorithm uses semantically safe optimistic virtual "locks" that achieve very fine granularity in conflict detection. This algorithm ensures serializability and external consistency by using logical clocks and backward validation of transactional queries. A formal proof of correctness of the proposed algorithm is also presented. ^

Monetary cost -efficient query distribution in ISDN -connected heterogeneous databases

Current technology permits connecting local networks via high-bandwidth telephone lines. Central coordinator nodes may use Intelligent Networks to manage data flow over dialed data lines, e.g. ISDN, and to establish connections between LANs. This dissertation focuses on cost minimization and on establishing operational policies for query distribution over heterogeneous, geographically distributed databases. Based on our study of query distribution strategies, public network tariff policies, and database interface standards we propose methods for communication cost estimation, strategies for the reduction of bandwidth allocation, and guidelines for central to node communication protocols. Our conclusion is that dialed data lines offer a cost effective alternative for the implementation of distributed database query systems, and that existing commercial software may be adapted to support query processing in heterogeneous distributed database systems. ^

Sentiment-Topic Modelling in Text Mining

Peer reviewed

Sentiment-Topic Modelling in Text Mining

Peer reviewed

A Curated Corpus for Sentiment-Topic Analysis

Postprint

Sentiment-Topic Modelling in Text Mining

Peer reviewed

Saúde da população “trans”: uma revisão sistemática da produção teórica brasileira

This dissertation analyzed the existing work on travestility and transsexuality whose problematic research focused on issues related to health and / or health services. For this purpose, a Literature Review Systematized Descriptive in virtual databases was performed: Bank of Higher Education Personnel Improvement Coordination Thesis (CAPES), Brazilian Digital Library of Theses and Dissertations (BDTD), Scielo and PubMed, between the years 1997 and 2014 in Brazil. We used the search terms "transsexual," "transvestite" and "transgender", each associated with the search term "health", in Portuguese and English. Complementing this search, we used the Documentary Analysis methodology to assess pamphlets productions, institutional documents and non-governmental organizations (NGOs), which were incorporated into the discussion. 295 papers were identified, among theses, dissertations and scientific articles. Of these, 223 were excluded and 72 selected for analysis. Thus, it obtained five theses and dissertations 21 on the topic of travestility and 7 theses and dissertations 9 that deal with transsexuality. Among the selected papers, 16 deal with transsexuality and health, 5 address the issue of travestility and health and work, 9 refer to the term "transgender" and "health". Even though it is an emerging field of research, there is an apparent deviation of the speech, previously anchored in questions whose topics are related to confrontation, infection or illness by HIV / AIDS (level of specialized care) for discussions on the health care for transsexuals in the process (level of specialized care). Still, few papers have specific trans attention in primary care associated with a comprehensive health care, with the empowerment of individuals, respecting the power of life, which are configured as important issues for the Public Policy on Health today.

Mining dynamic databases for frequent closed itemsets

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Research databases page usability test - August 2016

During the summer of 2016, Duke University Libraries staff began a project to update the way that research databases are displayed on the library website. The new research databases page is a customized version of the default A-Z list that Springshare provides for its LibGuides content management system. Duke Libraries staff made adjustments to the content and interface of the page. In order to see how Duke users navigated the new interface, usability testing was conducted on August 9th, 2016.

Mining dynamic databases for frequent closed itemsets

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The epidemiology, healthcare and societal burden and costs of asthma in the UK and its member nations: analyses of standalone and linked national databases

Background: There are a lack of reliable data on the epidemiology and associated burden and costs of asthma. We sought to provide the first UK-wide estimates of the epidemiology, healthcare utilisation and costs of asthma. 

Methods: We obtained and analysed asthma-relevant data from 27 datasets: these comprised national health surveys for 2010-11, and routine administrative, health and social care datasets for 2011-12; 2011-12 costs were estimated in pounds sterling using economic modelling. 

Results: The prevalence of asthma depended on the definition and data source used. The UK lifetime prevalence of patient-reported symptoms suggestive of asthma was 29.5 % (95 % CI, 27.7-31.3; n = 18.5 million (m) people) and 15.6 % (14.3-16.9, n = 9.8 m) for patient-reported clinician-diagnosed asthma. The annual prevalence of patient-reported clinician-diagnosed-and-treated asthma was 9.6 % (8.9-10.3, n = 6.0 m) and of clinician-reported, diagnosed-and-treated asthma 5.7 % (5.7-5.7; n = 3.6 m). Asthma resulted in at least 6.3 m primary care consultations, 93,000 hospital in-patient episodes, 1800 intensive-care unit episodes and 36,800 disability living allowance claims. The costs of asthma were estimated at least £1.1 billion: 74 % of these costs were for provision of primary care services (60 % prescribing, 14 % consultations), 13 % for disability claims, and 12 % for hospital care. There were 1160 asthma deaths. 

Conclusions: Asthma is very common and is responsible for considerable morbidity, healthcare utilisation and financial costs to the UK public sector. Greater policy focus on primary care provision is needed to reduce the risk of asthma exacerbations, hospitalisations and deaths, and reduce costs.

Gestação após gastroplastia para tratamento de obesidade mórbida: série de casos e revisão da literatura

Objetivo: relatar a evolução de uma série de casos de gestação em mulheres previamente submetidas à cirurgia de bypass gástrico para tratamento de obesidade grave. Métodos: cinco casos consecutivos de gravidez após gastroplastia ocorridos entre 2001 e 2004 foram avaliados. As pacientes tinham idade entre 30 e 34 anos e todas haviam sido submetidas à cirurgia de Capella. Aspectos clínicos, laboratoriais e do acompanhamento materno e fetal foram considerados, durante o período gestacional e após o parto. Foi realizada revisão da literatura internacional, por meio das bases de dados MEDLINE e Web of Science, utilizando os seguintes unitermos: gastroplasty, gastric bypass surgery, bariatric surgery e pregnancy. Resultados: todas as gestações observadas foram únicas e não ocorreram complicações obstétricas, durante o seguimento pré-natal e parto. Também não houve registro de recém-nascidos prematuros ou de baixo peso ao nascimento. Conclusão: nossos dados sugerem que a gravidez após gastroplastia é segura para a mãe e feto. Entretanto, em virtude do limitado volume de informação disponível sobre o tema, investigações adicionais são necessárias para estabelecer recomendações apropriadas com relação ao seguimento dessas gestações _________________________________________________ABSTRACT Purpose: we report a small series of pregnant women who underwent gastric bypass surgery for severe obesity, with a review of the literature on this topic. Methods: five consecutive cases of pregnancy after gastroplasty between 2001 and 2004 were evaluated, and clinical, laboratory and therapeutic features were considered. Patients were 30 to 34 years old and all had been submitted to gastroplasty by the Capella technique. The outcomes for both the pregnant woman and the fetus were evaluated. A search of the English language literature was done through MEDLINE and Web of Science databases with the following terms: gastroplasty, gastric bypass surgery, bariatric surgery, and pregnancy. Results: all 5 pregnancies were singleton. No major obstetric complications were observed and there were no premature or lowbirth weight infants. Conclusion: our data suggest that pregnancy following gastroplasty is safe for mother and fetus. However, since information about this topic is limited, further investigations are required to establish appropriate recommendations concerning the follow-up of these pregnancies

LDA-TM : A two-step approach to twitter topic data clustering

The Twitter System is the biggest social network in the world, and everyday millions of tweets are posted and talked about, expressing various views and opinions. A large variety of research activities have been conducted to study how the opinions can be clustered and analyzed, so that some tendencies can be uncovered. Due to the inherent weaknesses of the tweets - very short texts and very informal styles of writing - it is rather hard to make an investigation of tweet data analysis giving results with good performance and accuracy. In this paper, we intend to attack the problem from another aspect - using a two-layer structure to analyze the twitter data: LDA with topic map modelling. The experimental results demonstrate that this approach shows a progress in twitter data analysis. However, more experiments with this method are expected in order to ensure that the accurate analytic results can be maintained.

An Exploration of the Data Collection Methods Utilised with Children, Teenagers and Young People (CTYPs)

Background: The impact of cancer upon children, teenagers and young people can be profound. Research has been undertaken to explore the impacts upon children, teenagers and young people with cancer, but little is known about how researchers can ‘best’ engage with this group to explore their experiences. This review paper provides an overview of the utility of data collection methods employed when undertaking research with children, teenagers and young people. A systematic review of relevant databases was undertaken utilising the search terms ‘young people’, ‘young adult’, ‘adolescent’ and ‘data collection methods’. The full-text of the papers that were deemed eligible from the title and abstract were accessed and following discussion within the research team, thirty papers were included. Findings: Due to the heterogeneity in terms of the scope of the papers identified the following data collections methods were included in the results section. Three of the papers identified provided an overview of data collection methods utilised with this population and the remaining twenty seven papers covered the following data collection methods: Digital technologies; art based research; comparing the use of ‘paper and pencil’ research with web-based technologies, the use of games; the use of a specific communication tool; questionnaires and interviews; focus groups and telephone interviews/questionnaires. The strengths and limitations of the range of data collection methods included are discussed drawing upon such issues as of the appropriateness of particular methods for particular age groups, or the most appropriate method to employ when exploring a particularly sensitive topic area. Conclusions: There are a number of data collection methods utilised to undertaken research with children, teenagers and young adults. This review provides a summary of the current available evidence and an overview of the strengths and limitations of data collection methods employed.