Static and dynamic semantics of NoSQL languages

We present a calculus for processing semistructured data that spans differences of application area among several novel query languages, broadly categorized as "NoSQL". This calculus lets users define their own operators, capturing a wider range of data processing capabilities, whilst providing a typing precision so far typical only of primitive hard-coded operators. The type inference algorithm is based on semantic type checking, resulting in type information that is both precise, and flexible enough to handle structured and semistructured data. We illustrate the use of this calculus by encoding a large fragment of Jaql, including operations and iterators over JSON, embedded SQL expressions, and co-grouping, and show how the encoding directly yields a typing discipline for Jaql as it is, namely without the addition of any type definition or type annotation in the code

Evaluation of bias in HIV seroprevalence estimates from national household surveys

Submitted by Gilvan Almeida ([email protected]) on 2016-12-07T12:03:30Z No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) FieldEvaluation.pdf: 177639 bytes, checksum: 417e97b6da6816379d956c2c88c54fef (MD5)Rejected by Éder Freyre ([email protected]), reason: Refazer on 2017-02-14T16:35:23Z (GMT)Submitted by Gilvan Almeida ([email protected]) on 2019-02-06T16:28:18Z No. of bitstreams: 2 FieldEvaluation.pdf: 177639 bytes, checksum: 417e97b6da6816379d956c2c88c54fef (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5)Approved for entry into archive by Regiane Silva ([email protected]) on 2019-08-26T13:12:58Z (GMT) No. of bitstreams: 2 FieldEvaluation.pdf: 177639 bytes, checksum: 417e97b6da6816379d956c2c88c54fef (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5)Made available in DSpace on 2019-08-26T13:12:58Z (GMT). No. of bitstreams: 2 FieldEvaluation.pdf: 177639 bytes, checksum: 417e97b6da6816379d956c2c88c54fef (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008Fundação Alfredo da Matta. Manaus, AM, Brasil.London School of Hygiene & Tropical Medicine. London, UK.Fundação Alfredo da Matta. Manaus, AM, Brasil.Fundação Alfredo da Matta. Manaus, AM, Brasil.Fundação Alfredo da Matta. Manaus, AM, Brasil.Fundação Oswaldo Cruz. Escola Nacional de Saúde Pública Sergio Arouca. Rio de Janeiro, RJ, Brasil.World Health Organization. Geneva, Switzerland.OBJECTIVES: To assess the performance, usefulness and cost of a rapid treponemal antibody assay (VisiTect Syphilis) to detect syphilis in high risk populations. METHODS: People who attended STI clinics in Manaus, Brazil, were screened for syphilis using the fluorescent treponemal antibody absorption (FTA-Abs) test and a non-treponemal test (Venereal Diseases Research Laboratory (VDRL)), and for HIV. Finger prick blood samples were tested with VisiTect Syphilis. The rapid test was evaluated against the reference FTA-Abs and for its usefulness in detecting active syphilis (FTA-Abs and VDRL positive). Operational performance was assessed through providers' and patients' interviews. An economic evaluation was conducted from the provider's perspective. RESULTS: 510 patients (60% men) were enrolled, of whom 13 (2.5%) were HIV-1 seropositive. Syphilis prevalence (FTA-Abs) was 18% and active syphilis prevalence was 7.5%. 11% (57/506) of samples were positive by VisiTect. The sensitivity, specificity, positive and negative predictive values of VisiTect Syphilis were 57% (95% CI 45.8 to 66.7), 99% (95% CI 97.0 to 99.6), 91% (95% CI 80.0 to 96.7) and 91% (95% CI 88.0 to 93.5), respectively. VisiTect Syphilis identified 79% (30/38) of active syphilis cases. The cost per case of syphilis was $16.8 for VDRL,$33.2 for low cost and $56.3 for high cost VisiTect Syphilis; the cost per case of active syphilis was$21.3, $57.5 and$97.6, respectively. Patients identified finger prick pain and preference for venous blood collection as minor barriers to test use. CONCLUSION: VisiTect Syphilis had low sensitivity in field use and was less cost effective than conventional VDRL. However, rapid and correct identification of a high proportion of active syphilis cases combined with operational characteristics suggest a role in high risk populations

Regular Expression Subtyping for XML Query and Update Languages

XML database query languages such as XQuery employ regular expression types with structural subtyping. Subtyping systems typically have two presentations, which should be equivalent: a declarative version in which the subsumption rule may be used anywhere, and an algorithmic version in which the use of subsumption is limited in order to make typechecking syntax-directed and decidable. However, the XQuery standard type system circumvents this issue by using imprecise typing rules for iteration constructs and defining only algorithmic typechecking, and another extant proposal provides more precise types for iteration constructs but ignores subtyping. In this paper, we consider a core XQuery-like language with a subsumption rule and prove the completeness of algorithmic typechecking; this is straightforward for XQuery proper but requires some care in the presence of more precise iteration typing disciplines. We extend this result to an XML update language we have introduced in earlier work.Comment: ESOP 2008. Companion technical report with proof

Selectivity Estimation for SPARQL Triple Patterns with Shape Expressions

International audienceShEx (Shape Expressions) is a language for expressing constraints on RDF graphs. In this work we optimize the evaluation of conjunctive SPARQL queries, on RDF graphs, by taking advantage of ShEx constraints. Our optimization is based on computing and assigning ranks to query triple patterns , dictating their order of execution. We first define a set of well formed ShEx schemas, that possess interesting characteristics for SPARQL query optimization. We then define our optimization method by exploiting information extracted from a ShEx schema. We finally report on evaluation results performed showing the advantages of applying our optimization on the top of an existing state-of-the-art query evaluation system

Factors associated with self-reported discrimination against men who have sex with men in Brazil

OBJECTIVE: To estimate self-reported discrimination due to sexual orientation among men who have sex with men (MSM) in Brazil and to analyze associated factors. METHODS: A cross-sectional study of 3,859 MSM recruited in 2008–2009 with respondent driven sampling. Data collection conducted in health centers in 10 Brazilian cities. A face-to-face questionnaire was used and rapid HIV and syphilis tests conducted. Aggregated data were weighted and adjusted odds ratio estimated to measure the association between selected factors and self-reported discrimination due to sexual orientation. RESULTS: The sample was predominantly young, eight plus years of schooling, pardo (brown), single, low-income, and identified themselves as gay or homosexual. The prevalence of self-reported discrimination due to sexual orientation was 27.7% (95%CI 26.2–29.1). Discrimination was independently associated with: age < 30 years, more years of schooling,community involvement and support, history of sexual and physical violence, suicidal thoughts, and unprotected receptive anal intercourse. CONCLUSIONS: The prevalence of self-reported discrimination among MSM in Brazil is high. These results challenge the assumptions that MSM-specific prevention and support programs are not required or that health professionals do not need special training to address MSM needs