Learning and Visceral Temptation in Dynamic Savings Experiments

In models of optimal savings with income uncertainty and habit formation, people should save early to create a buffer stock, to cushion bad income draws and limit the negative internality from habit formation. In experiments in this setting, people save too little initially, but learn to save optimally within four repeated lifecycles, or 1-2 lifecycles with “social learning.” Using beverage rewards (cola) to create visceral temptation, thirsty subjects who consume immediately overspend compared to subjects who only drink after time delay. The relative overspending of immediate-consumption subjects is consistent with hyperbolic discounting and dual-self models. Estimates of the present-bias choices are β=0.6-0.7, which are consistent with other studies (albeit over different time horizons)

Learning and Visceral Temptation in Dynamic Saving Experiments

This paper tests two explanations for apparent undersaving in life cycle models: bounded rationality and a preference for immediacy. Each was addressed in a separate experimental study. In the first study, subjects saved too little initially—providing evidence for bounded rationality—but learned to save optimally within four repeated life cycles. In the second study, thirsty subjects who consume beverage sips immediately, rather than with a delay, show greater relative overspending, consistent with quasi-hyperbolic discounting models. The parameter estimates of overspending obtained from the second study, but not the first, are in range of several empirical studies of saving (with an estimated β = 0.6–0.7)

The Impact of After School Tutoring on Math Achievement: Perceptions of African American Males and Those Who Teach Them

Despite increases in overall academic achievement, African American males continue to struggle in the area of mathematics. Data from the National Assessment of Educational Progress (NAEP) indicates that eighth grade African American males had the lowest levels of mathematics success of all subgroups in 2013, with only 13% performing at or above the proficient performance level in math. An approach to increasing the academic achievement of African American males has been to provide extended learning time beyond the typical secondary education experience. After school programs are one such example. Many studies indicate that after school programs have had some positive effects on math achievement. However, missing from the literature are qualitative studies that examine the impact of after school programs specifically on math achievement for African American males from the perspectives of the students and teachers involved in the programs. This qualitative study explores the experiences and perceptions of five African American male middle school students and three math teachers who tutor in an after school program at one middle school in southern California. The purpose of the study was to understand, from their perspective, the factors that were internal and external to the after school program that supported or challenged math achievement. Document analysis, observations of students’ regular math class and after school class, and participant interviews revealed the influence that teachers, pedagogy, attendance, peers and educational structure had on student engagement and students’ intrinsic motivation to learn math. This study exposes the complexity of raising math achievement even when students are given a second chance. It has important implications for educators, school program directors and school administrators who are engaged in efforts to increase the math achievement of African American male students

Increased hazard of myocardial infarction with insulin‐provision therapy in actively smoking patients with diabetes mellitus and stable ischemic heart disease: The BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial

Background In the BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial, randomization of diabetic patients with stable ischemic heart disease to insulin provision ( IP ) therapy, as opposed to insulin sensitization ( IS ) therapy, resulted in biochemical evidence of impaired fibrinolysis but no increase in adverse clinical outcomes. We hypothesized that the prothrombotic effect of IP therapy in combination with the hypercoagulable state induced by active smoking would result in an increased risk of myocardial infarction ( MI ). Methods and Results We analyzed BARI 2D patients who were active smokers randomized to IP or IS therapy. The primary end point was fatal or nonfatal MI . PAI ‐1 (plasminogen activator inhibitor 1) activity was analyzed at 1, 3, and 5 years. Of 295 active smokers, MI occurred in 15.4% randomized to IP and in 6.8% randomized to IS over the 5.3 years ( P =0.023). IP therapy was associated with a 3.2‐fold increase in the hazard of MI compared with IS therapy (hazard ratio: 3.23; 95% confidence interval, 1.43–7.28; P =0.005). Baseline PAI ‐1 activity (19.0 versus 17.5 Au/mL, P =0.70) was similar in actively smoking patients randomized to IP or IS therapy. However, IP therapy resulted in significantly increased PAI ‐1 activity at 1 year (23.0 versus 16.0 Au/mL, P =0.001), 3 years (24.0 versus 18.0 Au/mL, P =0.049), and 5 years (29.0 versus 15.0 Au/mL, P =0.004) compared with IS therapy. Conclusions Among diabetic patients with stable ischemic heart disease who were actively smoking, IP therapy was independently associated with a significantly increased hazard of MI . This finding may be explained by higher PAI ‐1 activity in active smokers treated with IP therapy. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 00006305. </jats:sec

Association of inferior vena cava filter placement for venous thromboembolic disease and a contraindication to anticoagulation with 30-day mortality

Importance: Despite the absence of data from randomized clinical trials, professional societies recommend inferior vena cava (IVC) filters for patients with venous thromboembolic disease (VTE) and a contraindication to anticoagulation therapy. Prior observational studies of IVC filters have suggested a mortality benefit associated with IVC filter insertion but have often failed to adjust for immortal time bias, which is the time before IVC filter insertion, during which death can only occur in the control group. Objective: To determine the association of IVC filter placement with 30-day mortality after adjustment for immortal time bias. Design, Setting, and Participants: This comparative effectiveness, retrospective cohort study used a population-based sample of hospitalized patients with VTE and a contraindication to anticoagulation using the State Inpatient Database and the State Emergency Department Database, part of the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality, from hospitals in California (January 1, 2005, to December 31, 2011), Florida (January 1, 2005, to December 31, 2013), and New York (January 1, 2005, to December 31, 2012). Data analysis was conducted from September 15, 2015, to March 14, 2018. Exposure: Inferior vena cava filter placement. Main Outcomes and Measures: Multivariable Cox proportional hazard models were constructed with IVC filters as a time-dependent variable that adjusts for immortal time bias. The Cox model was further adjusted using the propensity score as an adjustment variable. Results: Of 126 030 patients with VTE, 61 281 (48.6%) were male and the mean (SD) age was 66.9 (16.6) years. In this cohort, 45 771 (36.3%) were treated with an IVC filter, whereas 80 259 (63.7%) did not receive a filter. In the Cox model with IVC filter status analyzed as a time-dependent variable to account for immortal time bias, IVC filter placement was associated with a significantly increased hazard ratio of 30-day mortality (1.18; 95% CI, 1.13-1.22; P \u3c .001). When the propensity score was included in the Cox model, IVC filter placement remained associated with an increased hazard ratio of 30-day mortality (1.18; 95% CI, 1.13-1.22; P \u3c .001). Conclusions and Relevance: After adjustment for immortal time bias, IVC filter placement was associated with increased 30-day mortality in patients with VTE and a contraindication to anticoagulation. Randomized clinical trials are needed to determine the efficacy of IVC filter placement in patients with VTE and a contraindication to anticoagulation

original antigenic Sin: the Downside of Immunological Memory and Implications For Covid-19

The concept of original antigenic sin (OAS) was put forth many years ago to explain how humoral memory responses generated against one set of antigens can affect the nature of antibody responses elicited to challenge infections or vaccinations containing a similar but not identical array of antigens. Here, we highlight the link between OAS and the germinal center reaction (GCR), a process unique to activated B cells undergoing somatic hypermutation and class switch recombination. It is the powerful response of activated memory B cells and the accompanying GCR that establish the foundations of OAS. We apply these concepts to the current COVID-19 pandemic and put forth several possible scenarios whereby OAS may result in either beneficial or harmful outcomes depending, hypothetically, on prior exposure to antigens shared between SARS-CoV-2 and seasonal human coronaviruses (hCoVs) that include betacoronaviruses (e.g., HCoV-OC43 and HCoV-HKU1) and alphacoronaviruses (e.g., HCoV-NL63 and HCoV-HKU1) (E. M. Anderson, E. C. Goodwin, A. Verma, C. P. Arevalo, et al., medRxiv, 2020, https://doi.org/10.1101/2020.11.06.20227215; S. M. Kissler, C. Tedijanto, E. Goldstein, Y. H. Grad, and M. Lipsitch, Science 368:860-868, 2020, https://doi.org/10.1126/science.abb5793)