AJUR Volume 18 Issue 3 (December 2021)

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Links to individual manuscripts, abstracts, and keywords are provided below.

p. 3. An Optimal Control Experiment for an SEIRS Epidemiological Model
Tanner Snyder & Ryan Nierman
Department of Mathematics and Computer Science, Madonna University, Livonia, MI
ABSTRACT: This work studies an optimal control model for a discrete-time Susceptible/Exposed/Infective/Removed/Susceptible (SEIRS) deterministic epidemiological model with a finite time horizon and changing population. The model presented converts a continuous SEIRS model that would typically be solved using differential equations into a discrete model that can be solved using dynamic programming. The discrete approach more closely resembles real life situations, as the number of individuals in a population, the rate of vaccination to be applied, and the time steps are all discrete values. The model utilizes a previously developed algorithm and applies it to the presented SEIRS model. To demonstrate the applicability of the algorithm, a series of numerical results are presented for various parameter values.
KEYWORDS: Control; Cost; Discrete; Disease; Epidemiology; Minimization; Modeling; Optimality; SEIRS; Vaccination

p. 15. Factors Associated with Surgery Among South Asian American and Non-Hispanic White Women with Breast Cancer
Lydia Lo & Jaya M. Satagopan
Department of Industrial and Systems Engineering, School of Engineering, Rutgers University,New Brunswick, NJ
Department of Biostatistics and Epidemiology & Center for South Asian Quantitative Health and Education, School of Public Health, Rutgers University, New Brunswick, NJ
ABSTRACT: South Asian American (SA) women are diagnosed with more aggressive breast cancer than non-Hispanic White (NHW) women. Understanding the factors associated with the types of surgery received by these women sheds light on disease management in these culturally distinct populations. We used data on age at diagnosis, stage, grade, estrogen and progesterone receptors, and surgery from 4,590 SA and 429,030 NHW breast cancer cases in the Surveillance, Epidemiology and End Results (SEER) program. We used logistic regression with surgery as the binary outcome (subcutaneous, total, or radical mastectomy (STRM) versus partial mastectomy, no, unknown or other (PNUM)) and included additive effects of all the variables and interactions of age, stage, grade, and estrogen and progesterone receptors with race/ethnicity. Type I error of 5% was used to assess statistical significance of the effects. SA were significantly more likely than NHW cases to receive STRM relative to PNUM surgery among women diagnosed at or after age 50 years and having localized stage disease (Odds Ratio (OR) = 1.27, 95% Confidence Interval (CI) = 1.06 – 1.52). Further, SA were significantly less likely than NHW cases to receive STRM relative to PNUM surgery among those diagnosed before age 50 years and having regional or distant stage disease (OR = 0.75, 95% CI = 0.59 – 0.95 for age at diagnosis < 40 years; OR = 0.77, 95% CI = 0.62 – 0.95 for age at diagnosis 40-49 years). The type of surgery received by SA and NHW women differ according to age at diagnosis and disease stage. 
KEYWORDS: Breast Cancer; Surgery; Cancer Health Equity; Disease Characteristics; South Asian American; Non-Hispanic White; Logistic Regression; Interaction

p. 25. The Effect of Perceived Uncertainty on Competitive Behavior
Duncan James Drewry & Zachary Reese
Weinberg Institute for Cognitive Science, University of Michigan, Ann Arbor, MI
Department of Psychology, University of Michigan, Ann Arbor, MI
ABSTRACT: How do people behave in the face of uncertainty? Some studies suggest that even when they are unaware of how others will behave, people default to cooperative behavior; however, other research suggests that uncertainty leads to more competitive behavior. Little research has examined how individual differences moderate such behavioral decisions. This study proposes that a stable (dispositional) sense of justice may, ironically, lead to more competitive behavior. Specifically, people who score highly in belief in a just world, system justification, and religiosity, and low in ambiguity tolerance may be more inclined to compete rather than cooperate because they believe people who experience positive outcomes deserve those outcomes regardless of the means taken to achieve them. Across two studies, participants (N = 288) engaged in a prisoner’s dilemma game — a task where they must choose to compete or cooperate — and completed the aforementioned individual difference measures. Results show that people tended to cooperate, but those high in system justification and belief in a just world were more likely to compete. In other words, people with a strong sense of cosmic justice were likely to exhibit competitive behavior under uncertain conditions.
KEYWORDS: Ambiguity Tolerance; Competition; Cooperation; Just World Beliefs; Prisoner’s Dilemma; Prosocial Behavior; Religiosity; System Justification; Uncertainty