Managing Risk of Bidding in Display Advertising

In this paper, we deal with the uncertainty of bidding for display advertising. Similar to the financial market trading, real-time bidding (RTB) based display advertising employs an auction mechanism to automate the impression level media buying; and running a campaign is no different than an investment of acquiring new customers in return for obtaining additional converted sales. Thus, how to optimally bid on an ad impression to drive the profit and return-on-investment becomes essential. However, the large randomness of the user behaviors and the cost uncertainty caused by the auction competition may result in a significant risk from the campaign performance estimation. In this paper, we explicitly model the uncertainty of user click-through rate estimation and auction competition to capture the risk. We borrow an idea from finance and derive the value at risk for each ad display opportunity. Our formulation results in two risk-aware bidding strategies that penalize risky ad impressions and focus more on the ones with higher expected return and lower risk. The empirical study on real-world data demonstrates the effectiveness of our proposed risk-aware bidding strategies: yielding profit gains of 15.4% in offline experiments and up to 17.5% in an online A/B test on a commercial RTB platform over the widely applied bidding strategies

Abstract 13987: Underutilization of Oral Anticoagulant Therapy in At-Risk Patients With Atrial Fibrillation—Insights From a Multistate Healthcare System

Introduction: Oral anticoagulant (OAC) therapy significantly reduces the risk of thromboembolism among at-risk patients with atrial fibrillation (AF). Current guidelines provide strong support for an OAC in men and women with AF and CHA2DS2-VASc scores of \u3e2 and \u3e3, respectively. In spite of this, previous data has suggested that up to 40% of these patients are not treated in accordance with guideline recommendations. Hypothesis: We hypothesized that OAC therapy continues to remain significantly underutilized among at-risk patients with AF in real-world settings. Methods: We sought to evaluate the prevalence of OAC underuse and contributing factors in an ambulatory population of at-risk AF patients within a large multistate healthcare system. EHR and coding (ICD-10) data were used to identify patients with AF, calculate their CHA2DS2-VASc score, and define their current antithrombotic regimen. Demographics were assessed to allow for comparison between those receiving an OAC from those who were not. Chi square or Fisher exact tests were used to examine differences between groups. Results: Data was pulled from our EHR on 8/1/18, identifying 147,455 unique patients with AF, of which 102,728 (76.3%) had a CHA2DS2-VASc score \u3e2 (excluding female gender) (Table). Compared to those on an OAC, patients on antiplatelet therapy were more likely to have coronary artery disease, peripheral vascular disease, and prior MI (p Conclusions: In a contemporary, non-registry setting, OAC underuse remains substantial among at-risk patients with AF. Further investigation into tools that facilitate implementation of guideline-directed medical therapy is needed to limit preventable thromboembolic events in this population

Abstract 14012: Opportunities to Improve the Efficacy and Safety of Oral Anticoagulant Therapy in Atrial Fibrillation—Insights From a Multistate Healthcare System

Introduction: Vitamin K antagonists (VKAs) effectively reduce thromboembolic risk in atrial fibrillation (AF), but are limited by a narrow therapeutic window. Patients with reduced time in the therapeutic range (TTR) also face an increased risk of bleeding and ischemic events. Based in part on this, current guidelines give preference to direct-acting oral anticoagulants (DOACs) over VKAs in AF. Hypothesis: We hypothesized that DOACs are underutilized among those on oral anticoagulant therapy and that TTR remains suboptimal for large numbers of individuals on VKAs in real-world settings. Methods: We sought to evaluate a) the breakdown of OAC type and b) TTR for those on VKAs in an ambulatory population of at-risk AF patients within a large multistate healthcare system. EHR and coding (ICD-10) data were used to identify patients with AF, calculate their CHA2DS2-VASc score, and define their current antithrombotic regimen. For those on a VKA, TTR was assessed with the Rosendaal method and reported as mean values. Demographics were assessed to allow for comparison between those receiving a DOAC and a VKA, as well as, those with high (\u3e70%) vs. low ( Results: Data was pulled from our EHR on 8/1/18, identifying 147,455 unique patients with AF, of which 102,728 (76.3%) had a CHA2DS2-VASc score \u3e2 (excluding female gender). Among these at-risk patients, 61,698 (60.1%) were receiving an OAC, of which 47.8% were on a VKA and 52.2% were on a DOAC. The mean TTR was 56.3%, with 37.1%, 49.9% and 60.8% with TTRs \u3e70%, \u3e60%, and \u3e50%, respectively. Patients on a DOAC were more likely to be female and less likely to have heart failure, coronary artery disease, peripheral vascular disease, diabetes and renal disease (p70% were more likely to be male and less likely to have heart failure, diabetes, and renal disease (p Conclusions: In a contemporary, non-registry setting, VKAs continue to be used in nearly half of at-risk patients on an OAC for AF, with a suboptimal TTR in nearly two thirds. Further investigation is needed into tools that facilitate interchange from a VKA to a DOAC, particularly among those with a suboptimal TTR

Predicting Pathologic Response of Esophageal Cancer to Neoadjuvant Chemotherapy: The Implications of Metabolic Nodal Response for Personalized Therapy

INTRODUCTION Only a minority of esophageal cancers demonstrates a pathological tumor response (pTR) to neoadjuvant chemotherapy (NAC). 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) is often used for restaging after NAC and to assess response. Increasingly, it is used during therapy to identify unresponsive tumors and predict pTR , using avidity of the primary tumor alone. However, definitions of such metabolic tumor response (mTR) vary. We aimed to comprehensively re-evaluate metabolic response assessment using accepted parameters, as well as novel concepts of metabolic nodal stage (mN) and nodal response (mNR). PATIENTS AND METHODS This was a single-center retrospective UK cohort study. All patients with esophageal cancer staged before NAC with PET-CT and after with CT or PET-CT and undergoing resection from 2006-2014 were identified. pTR was defined as Mandard tumor regression grade 1-3; imaging parameters included metrics of tumor avidity (standardized uptake value [SUV]max/mean/peak), composites of avidity and volume (including metabolic tumor volume), nodal SUVmax, and our new concepts of mN stage and mNR. RESULTS Eighty-two (27.2%) of 301 patients demonstrated pTR. No pre-NAC PET parameters predicted pTR. In 220 patients re-staged by PET-CT, The optimal tumor ΔSUVmax threshold was a 77.8% reduction. This was as sensitive as the current PET Response Criteria in Solid Tumors (PERCIST) 30% reduction, but more specific with a higher negative predictive value (p<0.001). ΔSUVmax and Δlength independently predicted pTR, and composite avidity/spatial metrics outperformed avidity alone. Whilst both mTR and mNR were associated with pTR, in 82 patients with FDG-avid nodes before NAC we observed mNR in 10 (12.2%) not demonstrating mTR. CONCLUSION Current definitions of metabolic response are suboptimal and too simplistic. Composite avidity/volume measures improve prediction. mNR may further improve response assessment, by specifically assessing metastatic tumor sub-populations, likely responsible for disease relapse, and should be urgently assessed when considering aborting therapy on the basis of mTR alone

Phase Separation and Magnetic Order in K-doped Iron Selenide Superconductor

Alkali-doped iron selenide is the latest member of high Tc superconductor family, and its peculiar characters have immediately attracted extensive attention. We prepared high-quality potassium-doped iron selenide (KxFe2-ySe2) thin films by molecular beam epitaxy and unambiguously demonstrated the existence of phase separation, which is currently under debate, in this material using scanning tunneling microscopy and spectroscopy. The stoichiometric superconducting phase KFe2Se2 contains no iron vacancies, while the insulating phase has a \surd5\times\surd5 vacancy order. The iron vacancies are shown always destructive to superconductivity in KFe2Se2. Our study on the subgap bound states induced by the iron vacancies further reveals a magnetically-related bipartite order in the superconducting phase. These findings not only solve the existing controversies in the atomic and electronic structures in KxFe2-ySe2, but also provide valuable information on understanding the superconductivity and its interplay with magnetism in iron-based superconductors

Taming Charge Transport in Semiconducting Polymers with Branched Alkyl Side Chains

National Research Fund of Luxembourg. Grant Number: 6932623; Croucher Foundation; Kodak Graduate Fellowship; Office of Naval Research. Grant Number: N00014-17-1-2214; U.S. Department of Energy. Grant Number: DE-AC02-76SF0051

Acoustic Metameterial with Negative Modulus

We present experimental and theoretical results on an acoustic metamaterial that exhibits negative effective modulus in a frequency range from 0 to 450 Hz. One-dimensional acoustic metamaterial with an array of side holes on a tube was fabricated. We observed that acoustic waves above 450 Hz propagated well in this structure, but no sound below 450 Hz passed through. The frequency characteristics of the metamaterial has the same form as that of the permittivity in metals due to the plasma oscillation. We also provide a theory to explain the experimental results

Superconducting Sr2RuO4 Thin Films without Out-of-Phase Boundaries by Higher-Order Ruddlesden-Popper Intergrowth

Ruddlesden-Popper (RP) phases (An+1B n O3n+1, n = 1, 2,···) have attracted intensive research with diverse functionalities for device applications. However, the realization of a high-quality RP-phase film is hindered by the formation of out-of-phase boundaries (OPBs) that occur at terrace edges, originating from lattice mismatch in the c-axis direction with the A'B'O3 (n = ∞) substrate. Here, using strontium ruthenate RP-phase Sr2RuO4 (n = 1) as a model system, an experimental approach for suppressing OPBs was developed. By tuning the growth parameters, the Sr3Ru2O7 (n = 2) phase was formed in a controlled manner near the film-substrate interface. This higher-order RP-phase then blocked the subsequent formation of OPBs, resulting in nearly defect-free Sr2RuO4 layer at the upper region of the film. Consequently, the Sr2RuO4 thin films exhibited superconductivity up to 1.15 K, which is the highest among Sr2RuO4 films grown by pulsed laser deposition. This work paves the way for synthesizing pristine RP-phase heterostructures and exploring their unique physical properties