Efficient Location Privacy In Mobile Applications

Location awareness is an essential part of today\u27s mobile devices. It is a well-established technology that offers significant benefits to mobile users. While location awareness has triggered the exponential growth of mobile computing, it has also introduced new privacy threats due to frequent location disclosures. Movement patterns could be used to identify individuals and also leak sensitive information about them, such as health condition, lifestyle, political/religious affiliations, etc. In this dissertation we address location privacy in the context of mobile applications. First we look into location privacy in the context of Dynamic Spectrum Access (DSA) technology. DSA is a promising framework for mitigating the spectrum shortage caused by fixed spectrum allocation policies. In particular, DSA allows license-exempt users to access the licensed spectrum bands when not in use by their respective owners. Here, we focus on the database-driven DSA model, where mobile users issue location-based queries to a white-space database in order to identify idle channels in their area. We present a number of efficient protocols that allow users to retrieve channel availability information from the white-space database while maintaining their location secret. In the second part of the dissertation we look into location privacy in the context of location-aware mobile advertising. Location-aware mobile advertising is expanding very rapidly and is forecast to grow much faster than any other industry in the digital era. Unfortunately, with the rise and expansion of online behavioral advertising, consumers have grown very skeptical of the vast amount of data that is extracted and mined from advertisers today. As a result, the consensus has shifted towards stricter privacy requirements. Clearly, there exists an innate conflict between privacy and advertisement, yet existing advertising practices rely heavily on non-disclosure agreements and policy enforcement rather than computational privacy guarantees. In the second half of this dissertation, we present a novel privacy-preserving location-aware mobile advertisement framework that is built with privacy in mind from the ground up. The framework consists of several methods which ease the tension that exists between privacy and advertising by guaranteeing, through cryptographic constructions, that (i) mobile users receive advertisements relative to their location and interests in a privacy-preserving manner, and (ii) the advertisement network can only compute aggregate statistics of ad impressions and click-through-rates. Through extensive experimentation, we show that our methods are efficient in terms of both computational and communication cost, especially at the client side

School Principals and the Child Welfare System: An Exploratory Study of Interviews Conducted on School Grounds

Investigators at child welfare agencies investigate allegations of abuse and neglect by interviewing the identified child victim. Schools are a customary location where an investigator may conduct the interview. Each state in America has independently determined the guidelines that determine how interviews are conducted. A literature review produced 17 articles that analyzed past legal proceedings where the constitutionality of whether a child could be interviewed at school without a warrant, court order, exigent circumstances, or parental consent was challenged. A national review of statutes and policies identified the varying approaches that states have authorized to regulate school-based interviews. Public school principals in Tennessee completed two surveys regarding school-based interviews. The first survey questioned what perceptions and understandings principals have of policies that regulate child welfare interview procedures. The second survey asked what steps that school principals have put in place to facilitate interview requests. Each survey was completed by 109 school principals. Revealed in the statutes and policies review was that policies issued by the Tennessee Department of Children’s Services (DCS) did not contain clear details to inform principals how to respond to all types of interview requests. The results of a binary logistic analysis suggested that the Title I status of the school that principals responded on behalf of was a statistically significant predictor of what knowledge principals had of DCS policies. Differences were found to exist between high school and non-high school principals in the results of Fisher’s exact test for how principals reported to facilitate interview requests. A research study with a larger sample size representing the responses from more principals in Tennessee is needed before recommending best practice standards for school-based interviews

What Storage Access Privacy is Achievable with Small Overhead?

Oblivious RAM (ORAM) and private information retrieval (PIR) are classic cryptographic primitives used to hide the access pattern to data whose storage has been outsourced to an untrusted server. Unfortunately, both primitives require considerable overhead compared to plaintext access. For large-scale storage infrastructure with highly frequent access requests, the degradation in response time and the exorbitant increase in resource costs incurred by either ORAM or PIR prevent their usage. In an ideal scenario, a privacy-preserving storage protocols with small overhead would be implemented for these heavily trafficked storage systems to avoid negatively impacting either performance and/or costs. In this work, we study the problem of the best $\mathit{storage\ access\ privacy}$that is achievable with only$\mathit{small\ overhead}$over plaintext access. To answer this question, we consider$\mathit{differential\ privacy\ access}$which is a generalization of the$\mathit{oblivious\ access}$security notion that are considered by ORAM and PIR. Quite surprisingly, we present strong evidence that constant overhead storage schemes may only be achieved with privacy budgets of$\epsilon = \Omega(\log n)$. We present asymptotically optimal constructions for differentially private variants of both ORAM and PIR with privacy budgets$\epsilon = \Theta(\log n)$with only$O(1)$overhead. In addition, we consider a more complex storage primitive called key-value storage in which data is indexed by keys from a large universe (as opposed to consecutive integers in ORAM and PIR). We present a differentially private key-value storage scheme with$\epsilon = \Theta(\log n)$and$O(\log\log n)$ overhead. This construction uses a new oblivious, two-choice hashing scheme that may be of independent interest.Comment: To appear at PODS'1

Evaluation Findings from the California Wellness Foundation's Teen Pregnancy Prevention Initiative

Highlights research findings from a comprehensive program evaluation of the Teen Pregnancy Prevention Initiative, a ten-year, $60-million effort to decrease the incidence of teen pregnancies in California

Batched differentially private information retrieval

Private Information Retrieval (PIR) allows several clients to query a database held by one or more servers, such that the contents of their queries remain private. Prior PIR schemes have achieved sublinear communication and computation by leveraging computational assumptions, federating trust among many servers, relaxing security to permit differentially private leakage, refactoring effort into an offline stage to reduce online costs, or amortizing costs over a large batch of queries. In this work, we present an efficient PIR protocol that combines all of the above techniques to achieve constant amortized communication and computation complexity in the size of the database and constant client work. We leverage differentially private leakage in order to provide better trade-offs between privacy and efficiency. Our protocol achieves speed-ups up to and exceeding 10x in practical settings compared to state of the art PIR protocols, and can scale to batches with hundreds of millions of queries on cheap commodity AWS machines. Our protocol builds upon a new secret sharing scheme that is both incremental and non-malleable, which may be of interest to a wider audience. Our protocol provides security up to abort against malicious adversaries that can corrupt all but one party.1414119 - National Science Foundation; CNS-1718135 - National Science Foundation; CNS-1931714 - National Science Foundation; HR00112020021 - Department of Defense/DARPA; 000000000000000000000000000000000000000000000000000000037211 - SRI Internationalhttps://www.usenix.org/system/files/sec22-albab.pdfPublished versio

Microbiome and Autism

Background: Autism Spectrum Disorders (ASD) are a group of neurologic conditions that affect behavior, communication, and social interaction in children and adults all over the world. Several recent studies correlate these disorders with alterations of the gut microbiome due to the possible imbalance of the gut-brain axis. This possible connection opens new avenues to explore the unknown areas of ASD pathogenesis and the new opportunities for managing this disorder. The goal of this systematic review is to analyze the existing knowledge on microbiome changes in ASD and to understand its importance in the biological and behavioral context of ASD patients. Methods: A systematic search covering the topics of ASD and microbiome was performed on PubMed and completed on October 7, 2019. Twenty-eight articles were included and their quality was assessed. The data extracted for analysis was related to the participants characteristics, the study type and method of analysis, the instrument used to diagnose ASD and the main outcomes of said investigation. Results: Most of the reviewed studies found microbiome changes in ASD patients in comparison with neurotypical subjects. However, there was no specific pattern of bacterial changes found. The studies focused mostly on Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria. Out of all these phyla, the only one that exhibited a clear trend in ASD subjects was Firmicutes, mainly the order Clostridiales and Clostridium species, with a documented increase in ASD subjects in ten studies. Conclusion: This review suggests that there is an altered microbiome in ASD. However, the current analysis was not able to establish a set of bacterial changes characteristic to this pathology. Nevertheless, the gut-brain axis relationship seems to be one worth pursuing in hopes to establish a clear pathophysiological path to this disorder.As Perturbações do Espetro Autista (PEA) são um conjunto de condições neurológicas que afetam a comunicação e a interação social, com padrões repetitivos e restritivos de comportamento e hipo ou hiper-reactividade a estímulos sensoriais e ambientais. Estas condições são definidas pela sua clínica, visto que a sua patogénese não se encontra ainda esclarecida. Existem fatores genéticos e ambientais implicados na génese das PEA, e também múltiplas comorbilidades com destaque para os distúrbios gastrointestinais. A elevada prevalência destes distúrbios em crianças com PEA leva à hipótese de que, para além de meras comorbilidades, estes possam ser parte do mecanismo causal desta patologia. Assim, através da teoria do “gut-brain axis” ou eixo intestino-cérebro, é possível estabelecer uma ligação entre estas duas componentes da PEA. O eixo intestino-cérebro define-se como o conjunto de interações nervosa, endócrina e imunológica que se estabelece entre o SNC e o trato GI. Um elemento fundamental desta comunicação é a microbiota, o conjunto de bactérias e outros microrganismos que residem num particular nicho biológico, neste caso o trato intestinal humano. No meio intestinal, estas bactérias produzem metabolitos essenciais para a sinalização endócrina e imunológica, comunicando também com o SNC através de recetores do nervo vago. O microbioma intestinal é também promotor da motilidade, produtor de vitaminas e tem um efeito protetor contra organismos patogénicos entéricos. No entanto, quando em desequilíbrio ou disbiose, pode produzir toxinas que atingem o SNC. Esta revisão sistemática procurou explorar a relação entre as alterações no microbioma humano e a patogénese da PEA. Foi realizada uma pesquisa na base de dados PubMed usando a expressão: “(("Autistic Disorder"[Mesh]) OR ("Autism Spectrum Disorder"[Mesh])) AND (("Microbiota"[Mesh]) OR ("Gastrointestinal Microbiome"[Mesh]))”. Os critérios de inclusão foram: estudos observacionais ou de intervenção, realizados em indivíduos com PEA e com referência à sua relação com a microbiota intestinal, redigidos em inglês. Foram também incluídos estudos referidos nas referências das revisões sistemáticas e meta-analises englobadas na pesquisa inicial. A qualidade dos estudos foi avaliada segundo os critérios STROBE e TREND e os principais dados extraídos foram: o número de participantes do estudo, o tipo de estudo e a metodologia usada, o/os instrumento/os usados para diagnosticar PEA e os principais resultados obtidos. Usando as recomendações do PRISMA (Preferred Reporting for Systematic Reviews and Meta-Analysis) foram incluídos 28 estudos nesta revisão. Foram estudadas 1169375 crianças com idades compreendidas entre 1 e 18 anos. Os estudos foram divididos em 3 grupos para facilitar a sua análise e discussão: “Standard comparison”, “Comparison by exposure variables” e "Comparison after intervention”. O primeiro grupo comparava linearmente o microbioma de indivíduos com PEA com o de sujeitos neurotípicos. O segundo reunia os estudos de coorte que procuravam verificar o impacto de variáveis que alterariam o microbioma, segundo os autores, para concluir se essa exposição teria influência num posterior diagnóstico de PEA. O último grupo reunia os estudos de intervenção com suplementos ou probióticos em crianças com PEA. A maioria dos estudos revelou uma diferença significativa entre o microbioma dos indivíduos com PEA e o dos controlos, mas as diferenças registadas não foram constantes entre estudos, com a notável exceção da ordem Clostridiales e da espécie Clostridium, que demostrou um notável aumento nos indivíduos com PEA. No primeiro grupo de estudos, apenas 2 em 18 consideraram que não havia uma divergência entre os microbiomas. No entanto, os próprios estudos foram realizados em condições bastante diferentes: 9 comparavam as crianças com PEA com os seus irmãos neurotípicos, enquanto os restantes 11 usaram controlos da comunidade; apenas 2 estudos abordaram a micobiota; um estudo analisou crianças e mães como uma unidade em termos de distribuição destes microrganismos e outro estudo recolheu os seus dados usando biopsias retais, ao invés de amostras fecais, por exemplo. Em relação aos estudos de coorte, não foi encontrada nenhuma relação causal entre os fatores testados (parto por cesariana, uso de antibióticos nos primeiros anos de vida) e a incidência de PEA. Os estudos de intervenção demostraram um efeito positivo da suplementação e probióticos na alteração da composição do microbioma, mas estes efeitos nem sempre se revelaram a nível sintomático. Assim, foi verificada uma diferença não negligenciável entre o microbioma de um indivíduo com PEA e o microbioma neurotípico. Esta conclusão pode ser uma base para futura pesquisa nesta aérea, através de um estudo que procure uniformizar os fatores que influenciam a microbiota e as suas condições de desenvolvimento

The role of digitally native, nonprofit news media in the future of American journalism: an exploratory study

Unprecedented changes in journalism practices have been occurring since the 21st century ushered in the digital age. News gathering methods, means of information delivery, and consumer habits have altered dramatically because of technological advances, causing a disruption in the traditional business model. Newspapers, historically the key instrument for investigative and public affairs reporting in the United States, have been the media sector facing the biggest decline in revenue and circulation. While the audience is migrating to traditional news outlets online, the advertisers are not. Free services such as eBay and Craig\u27s List have contributed to a nearly 50% drop in revenue for newspapers. Therefore, the once profitable news industry is no longer as attractive to corporate owners with commercial interests. The response has been severe budget and staff cuts. An estimated 30% of traditional journalism jobs have been eliminated. In response to the fiscal crisis, 60 nonprofit news organizations have formed, mostly online, with the mission of performing public service journalism. Hearings on the future of news have been held by a U.S. Senate committee, the Federal Trade Commission, and the Federal Communications Commission, which is researching whether these digitally native nonprofit news outlets should be eligible for government funding, similar to the public broadcasting system. The purpose of this exploratory study was to gain a better understanding of how these digitally native nonprofit journalists view their role in the future of public service journalism and determine whether government financing is appropriate or even desired by the leaders of these organizations. Findings suggest that the leaders view their role as necessary to democracy because they provide information about public affairs, serve as a watchdog of government officials, and engage the public in a discussion of community issues using digital technology. However, they cannot perform these functions alone. The leaders see partnerships with commercial and public media as key to their success. The respondents also are concerned with diversifying their revenue streams beyond foundation and philanthropic funding. They do not support direct government subsidies, however, because they believe that type of support would present ethical and credibility issues

Increasing boys' and girls' intention to avoid teenage pregnancy: a cluster randomised control feasibility trial of an interactive video drama based intervention in post-primary schools in Northern Ireland

Background: Adolescent men have a vital yet neglected role in reducing unintended teenage pregnancy (UTP). There is a need for gender-sensitive educational interventions. Objectives: To determine the value and feasibility of conducting an effectiveness trial of the If I Were Jack Relationship and Sexuality Education (RSE) intervention in a convenience quota sample of post-primary schools in Northern Ireland. Secondary objectives were to assess acceptability to schools, pupils (male/female, aged 14–15 years) and parents/guardians; to identify optimal delivery structures and systems; to establish participation rates and reach, including equality of engagement of different socioeconomic and religious types; to assess trial recruitment and retention rates; to assess variation in normal RSE practice; to refine survey instruments; to assess differences in outcomes for male and female pupils; to identify potential effect sizes that might be detected in an effectiveness trial and estimate appropriate sample size for that trial; and to identify costs of delivery and pilot methods for assessing cost-effectiveness. Design: Cluster randomised Phase II feasibility trial with an embedded process and economic evaluation. Intervention: A teacher-delivered classroom-based RSE resource – an interactive video drama (IVD) with classroom materials, teacher training and an information session for parents – to immerse young people in a hypothetical scenario of Jack, a teenager whose girlfriend is unintentionally pregnant. It addresses gender inequalities in RSE by focusing on young men and is designed to increase intentions to avoid UTP by encouraging young people to delay sexual intercourse and to use contraception consistently in sexual relationships. Main outcome measures: Abstinence from sexual intercourse (delaying initiation of sex or returning to abstinence) or avoidance of unprotected sexual intercourse (consistent correct use of contraception). Secondary outcomes included Knowledge, Attitudes, Skills and Intentions. Results: The intervention proved acceptable to schools, pupils and parents, as evidenced through positive process evaluation. One minor refinement to the parental component was required, namely the replacement of the teacher-led face-to-face information session for parents by online videos designed to deliver the intervention to parents/guardians into their home. School recruitment was successful (target 25%, achieved 38%). No school dropped out. Pupil retention was successful (target 85%, achieved 93%). The between-group difference in incidence of unprotected sex of 1.3% (95% confidence interval 0.55% to 2.2%) by 9 months demonstrated an effect size consistent with those reported to have had meaningful impact on UTP rates (resulting in an achievable sample size of 66 schools at Phase III). Survey instruments showed high acceptability and reliability of measures (Cronbach’s alpha: 0.5–0.7). Economic evaluation at Phase III is feasible because it was possible to (1) identify costs of delivering If I Were Jack (mean cost per pupil, including training of teachers, was calculated as £13.66); and (2) develop a framework for assessing cost-effectiveness. Conclusion: Trial methods were appropriate, and recruitment and retention of schools and pupils was satisfactory, successfully demonstrating all criteria for progression to a main trial. The perceived value of culture- and gender-sensitive public health interventions has been highlighted. Future work: Progression to a Phase III effectiveness trial. Trial registration: Current Controlled Trials ISRCTN99459996. Funding: This project was funded by the NIHR Public Health Research programme and will be published in full in Public Health Research; Vol. 5, No. 1. See the NIHR Journals Library website for further project information