Dimensionality reduction for click-through rate prediction: Dense versus sparse representation

In online advertising, display ads are increasingly being placed based on real-time auctions where the advertiser who wins gets to serve the ad. This is called real-time bidding (RTB). In RTB, auctions have very tight time constraints on the order of 100ms. Therefore mechanisms for bidding intelligently such as clickthrough rate prediction need to be sufficiently fast. In this work, we propose to use dimensionality reduction of the user-website interaction graph in order to produce simplified features of users and websites that can be used as predictors of clickthrough rate. We demonstrate that the Infinite Relational Model (IRM) as a dimensionality reduction offers comparable predictive performance to conventional dimensionality reduction schemes, while achieving the most economical usage of features and fastest computations at run-time. For applications such as real-time bidding, where fast database I/O and few computations are key to success, we thus recommend using IRM based features as predictors to exploit the recommender effects from bipartite graphs.Comment: Presented at the Probabilistic Models for Big Data workshop at NIPS 201

Sex differences in mortality of admitted patients with personality disorders in North Norway - a prospective register study.

It is well established that patients with serious mental disorders have higher mortality than the general population, yet there are few studies on mortality of both natural and unnatural causes in patients with personality disorders. The aim of this study was to investigate the mortality of in-patients with personality disorder diagnosis in a 27-year follow-up cohort in North Norway, with a special focus on gender differences. Based on a hospital case register covering 1980 to 2006, 284 female and 289 male patients were included. The cohort was linked to the Norwegian Cause of Death Registry for information concerning mortality. The mortality rates were adjusted for age by applying a Poisson regression model. The relative mortality in men compared to women was tested with Cox regression with attained age as the time variable. The number of deaths to be expected among the patients if the mortality rates of the general population in Norway had prevailed was estimated and excess mortality, expressed by the standardized mortality ratio (SMR), calculated. When compared to the mortality in the general population, men and women with personality disorder diagnoses had 4.3 (95% CI: 3.2 - 5.9) and 2.9 (95% CI: 1.9 - 4.5) times, respectively, increased total mortality. Patients with personality disorder diagnoses have particularly high mortality for unnatural deaths; 9.7 (95% confidence interval (CI): 6.3 - 15.1) times higher for men and 17.8 (95% CI: 10.1 - 30.3) for women, respectively, and even higher for suicides – 15 (95% CI: 9–27) for men and 38 (95% CI: 20–70) for women. The mortality due to natural causes was not statistically significantly increased in women, whereas men had 2.8 (95% CI: 1.8 - 4.4) times higher mortality of natural deaths than the general population. Compared to the general population, patients with a personality disorder have high mortality, particularly mortality from unnatural causes. The number of deaths caused by suicides is especially high for women. Men also have higher mortality of natural causes than the general population

Optimized workflow to modify microRNA expression in primary human intravascular cells

Background - A comprehensive dissection of the role of microRNAs (miRNAs) in gene regulation and subsequent cell functions requires a specific and efficient knockdown or overexpression of the miRNA of interest; these are achieved by transfecting the cell of interest with a miRNA inhibitor or a miRNA mimic, respectively. Inhibitors and mimics of miRNAs with a unique chemistry and/or structural modifications are available commercially and require different transfection conditions. Here, we aimed to investigate how various conditions affect the transfection efficacy of two miRNAs with high and low endogenous expression, miR-15a-5p and miR-20b-5p respectively, in human primary cells. Results - MiRNA inhibitors and mimics from two commonly used commercial vendors were employed, i.e., mirVana (Thermo Fisher Scientific) and locked nucleic acid (LNA) miRNA (Qiagen). We systematically examined and optimized the transfection conditions of such miRNA inhibitors and mimics to primary endothelial cells and monocytes using either a lipid-based carrier (lipofectamine) for delivery or an unassisted uptake. Transfection of LNA inhibitors with either phosphodiester (PE)- or phosphorothioate (PS)-modified nucleotide bonds, delivered using a lipid-based carrier, efficiently downregulated the expression levels of miR-15a-5p already 24 h following transfection. MirVana miR-15a-5p inhibitor displayed a less efficient inhibitory effect, which was not improved 48 h following a single transfection or two consecutive transfections. Interestingly, LNA-PS miR-15a-5p inhibitor efficiently reduced the levels of miR-15a-5p when delivered without a lipid-based carrier in both ECs and monocytes. When using a carrier, mirVana and LNA miR-15a-5p and miR-20b-5p mimics showed similar efficiency 48 h following transfection to ECs and monocytes. None of the miRNA mimics effectively induced overexpression of the respective miRNA when given to primary cells without a carrier. Conclusion - LNA miRNA inhibitors efficiently downregulated the cellular expression of miRNA, such as miR-15a-5p. Furthermore, our findings suggest that LNA-PS miRNA inhibitors can be delivered in the absence of a lipid-based carrier, whereas miRNA mimics need the aid of a lipid-based carrier to achieve sufficient cellular uptake