Modeling Adoption and Usage of Competing Products

The emergence and wide-spread use of online social networks has led to a dramatic increase on the availability of social activity data. Importantly, this data can be exploited to investigate, at a microscopic level, some of the problems that have captured the attention of economists, marketers and sociologists for decades, such as, e.g., product adoption, usage and competition. In this paper, we propose a continuous-time probabilistic model, based on temporal point processes, for the adoption and frequency of use of competing products, where the frequency of use of one product can be modulated by those of others. This model allows us to efficiently simulate the adoption and recurrent usages of competing products, and generate traces in which we can easily recognize the effect of social influence, recency and competition. We then develop an inference method to efficiently fit the model parameters by solving a convex program. The problem decouples into a collection of smaller subproblems, thus scaling easily to networks with hundred of thousands of nodes. We validate our model over synthetic and real diffusion data gathered from Twitter, and show that the proposed model does not only provides a good fit to the data and more accurate predictions than alternatives but also provides interpretable model parameters, which allow us to gain insights into some of the factors driving product adoption and frequency of use

An index of political support for decentralization: the Spanish case.

This paper presents a method to make measurable what was not: the discourses of politicians regarding decentralization. For this purpose, we develop a “matrix of arguments” and a set of indexes, and apply them to provide a snapshot of the politicians’ views on the “General Law of Budgetary Stability”, a landmark for the process of decentralization in Spain.political party, matrix of decentralization, arguments, index of decentralization.

Students’ Uptake of Written Feedback in an Egyptian University Language Program

Feedback is by no means a straightforward path; rather, the feedback on the writing process involves several factors on the part of both educators and students at a university level. It is important to note that feedback can be given in different ways to each student, while uptake may vary across educational institutions. This study explored students’ perceptions on engagement strategies, uptake, and emotional responses to the feedback phenomenon. Past studies on feedback and uptake prompted the investigation of this area. The study includes tentative answers to the wealth of questions that have contributed to the field of feedback. This research relied on student work, questionnaires, and interviews in order to gain insight into learners’ uptake, teachers’ engagement strategies, and students’ emotional responses towards written feedback (WF). The study aims to suggest practical ways to facilitate student engagement by revealing their emotional reactions and improving feedback delivery. The study was conducted at a leading English-language instruction institution located in Cairo, Egypt. The researcher sent a questionnaire to 69 participants, collected 30 writing samples with WF, and interviewed 8 participants. The findings in this study were consistent with the results of similar studies, where educators implement several feedback strategies, resulting in a high level of student engagement and uptake of feedback. The present exploration sheds light on the relationship between students and their teacher’s feedback in one of the prestigious universities in Cairo. Keywords: writing tasks, written feedback, emotional responses, student perceptions, student engagement, feedback practices, feedback strategies, student uptak

A thermal comfort model for high-altitude regions in the Ecuadorian Andes

Of Ecuador's 3.75 million households, 33% live in poor-quality and substandard dwellings. Construction standards provide metrics and criteria for energy and comfort performance evaluation; that plays a significant role in designing adequate and affordable dwellings. Due to a lack of supporting evidence, the thermal comfort criteria have been adopted from international standards, such as ASHRAE 90.2:2018. In the absence of accurate contextualised comfort models, building standards can trigger a combination of wasting energy and exacerbating discomfort. Furthermore, householders' environmental perception may be affected by particular weather and geographical conditions. Therefore, this research aims to define thermal comfort criteria, aligned with residents' perception in subtropical highlands, to be used for the thermal performance assessment in dwellings in the Ecuadorian Andes. The research combined cross-sectional thermal comfort surveys and thermal performance simulation. Data was collected in three locations between 2400 and 3000 meters above sea level. This thesis's main outcomes add knowledge on why and how people adapt to high-altitude locations. Thermal comfort temperatures are significantly different across the study locations due to altitude. Moreover, the comfort temperature differences also rely upon the broader limits of comfort acceptability for lower altitudes and acclimatised subjects. On the contrary, the range is narrower at higher altitudes and non-acclimatised residents. The derived high-altitude thermal comfort algorithm for the Ecuadorian Highlands resulted from the regression of the comfort temperature and the 24-hour mean outdoor air temperature. Over 80% of comfort hours were estimated for the study archetypes based on the high-altitude comfort model. International comfort models consistently overestimate the percentage of hours of discomfort for all the study archetypes. Moreover, the discomfort could increase up to 30% for dwellings in compliance with the thermal insulation requirement of the Ecuadorian construction standard (NEC11). The research outcomes are expected to contribute with grounded evidence to the development of local construction policy

IS THE CURRENT DEFINITION OF THE METABOLIC SYNDROME A USEFUL TOOL FOR THE DETECTION OF CARDIOVASCULAR DISEASE IN NON-HISPANIC BLACKS?

Blacks in the country suffer from higher prevalences of obesity, diabetes, hypertension and cardiovascular disease compared to whites. Paradoxically, they have the lowest prevalence of the Metabolic Syndrome (MS) compared to whites and Mexican Americans. This is likely due to the fact that blacks tend to have lower triglycerides (TG) and higher high density cholesterol (HDL) levels. We challenged the current lipid criteria established by the Adult Treatment Panel III for the detection of the MS and set out to find more appropriate TG and HDL cutoffs to detect the MS in blacks. Using data from the National Health and Nutrition Examination Survey from 1999-2006, we identified that a more appropriate TG cutoff for blacks to detect the MS is 110 mg/dL but were not able to identify more suitable HDL cutoffs. Our results confirm that race/ethnic-specific criteria should be established for the detection of the MS across racial/ethnic groups

Oral History Transcript - Isabel Amaro Rodriguez

https://scholarworks.utrgv.edu/spanishlandgrantsoralhistories/1032/thumbnail.jp

Learning and Forecasting Opinion Dynamics in Social Networks

Social media and social networking sites have become a global pinboard for exposition and discussion of news, topics, and ideas, where social media users often update their opinions about a particular topic by learning from the opinions shared by their friends. In this context, can we learn a data-driven model of opinion dynamics that is able to accurately forecast opinions from users? In this paper, we introduce SLANT, a probabilistic modeling framework of opinion dynamics, which represents users opinions over time by means of marked jump diffusion stochastic differential equations, and allows for efficient model simulation and parameter estimation from historical fine grained event data. We then leverage our framework to derive a set of efficient predictive formulas for opinion forecasting and identify conditions under which opinions converge to a steady state. Experiments on data gathered from Twitter show that our model provides a good fit to the data and our formulas achieve more accurate forecasting than alternatives

Variation in dengue virus plaque reduction neutralization testing: systematic review and pooled analysis.

BackgroundThe plaque reduction neutralization test (PRNT) remains the gold standard for the detection of serologic immune responses to dengue virus (DENV). While the basic concept of the PRNT remains constant, this test has evolved in multiple laboratories, introducing variation in materials and methods. Despite the importance of laboratory-to-laboratory comparability in DENV vaccine development, the effects of differing PRNT techniques on assay results, particularly the use of different dengue strains within a serotype, have not been fully characterized.MethodsWe conducted a systematic review and pooled analysis of published literature reporting individual-level PRNT titers to identify factors associated with heterogeneity in PRNT results and compared variation between strains within DENV serotypes and between articles using hierarchical models.ResultsThe literature search and selection criteria identified 8 vaccine trials and 25 natural exposure studies reporting 4,411 titers from 605 individuals using 4 different neutralization percentages, 3 cell lines, 12 virus concentrations and 51 strains. Of 1,057 titers from primary DENV exposure, titers to the exposure serotype were consistently higher than titers to non-exposure serotypes. In contrast, titers from secondary DENV exposures (n = 628) demonstrated high titers to exposure and non-exposure serotypes. Additionally, PRNT titers from different strains within a serotype varied substantially. A pooled analysis of 1,689 titers demonstrated strain choice accounted for 8.04% (90% credible interval [CrI]: 3.05%, 15.7%) of between-titer variation after adjusting for secondary exposure, time since DENV exposure, vaccination and neutralization percentage. Differences between articles (a proxy for inter-laboratory differences) accounted for 50.7% (90% CrI: 30.8%, 71.6%) of between-titer variance.ConclusionsAs promising vaccine candidates arise, the lack of standardized assays among diagnostic and research laboratories make unbiased inferences about vaccine-induced protection difficult. Clearly defined, widely accessible reference reagents, proficiency testing or algorithms to adjust for protocol differences would be a useful first step in improving dengue PRNT comparability and quality assurance