A Survey of Agent-Based Modeling Practices (January 1998 to July 2008)

In the 1990s, Agent-Based Modeling (ABM) began gaining popularity and represents a departure from the more classical simulation approaches. This departure, its recent development and its increasing application by non-traditional simulation disciplines indicates the need to continuously assess the current state of ABM and identify opportunities for improvement. To begin to satisfy this need, we surveyed and collected data from 279 articles from 92 unique publication outlets in which the authors had constructed and analyzed an agent-based model. From this large data set we establish the current practice of ABM in terms of year of publication, field of study, simulation software used, purpose of the simulation, acceptable validation criteria, validation techniques and complete description of the simulation. Based on the current practice we discuss six improvements needed to advance ABM as an analysis tool. These improvements include the development of ABM specific tools that are independent of software, the development of ABM as an independent discipline with a common language that extends across domains, the establishment of expectations for ABM that match their intended purposes, the requirement of complete descriptions of the simulation so others can independently replicate the results, the requirement that all models be completely validated and the development and application of statistical and non-statistical validation techniques specifically for ABM.Agent-Based Modeling, Survey, Current Practices, Simulation Validation, Simulation Purpose

An Analysis of the Correlation between ACT Scores and One-to-One Computing

This study examined whether a relationship exists between one-to-one computing and student achievement, specifically ACT scores. This study also examined whether relationships exist among teachers’ perceptions of one-to-one computing, teachers’ years of experience, subjects taught by teachers, teachers’ skill level in the use of a computer for instruction, and teachers’ perceptions of changes in ACT scores. The results of this study could help policymakers and educators with decisions regarding implementation of one-to-one computing programs. The sample of schools for investigating the relationship between one-to-one computing and ACT scores consisted of 33 secondary public schools with one-to-one computing programs located in school districts from multiple states in the United States. There were 122 teachers from 12 secondary public schools with one-to-one computing programs located in school districts from multiple states in the United States who participated in a survey regarding teachers’ perceptions of one-to-one computing. Prior to the implementation of one-to-one computing and the corresponding tests in the same schools, the average student ACT composite scores and ACT subtest scores in English, math, and reading were not statistically different from what they are after two years of implementation. A statistically significant difference was found between the average student ACT subtest scores in science in schools one year prior to implementing one-to-one computing and the average student ACT subtest scores in science in the same schools two years after implementing one-to-one computing. A statistically significant difference was not found between the average change in student ACT composite score and ACT subtest scores in the state and the average change in student ACT composite score and ACT subtest scores in schools with two years of experience in implementing one-to-one computing. A statistically significant relationship was not found among teachers’ perceptions of one-to-one computing, subjects taught by teachers, teachers’ skill level in the use of a computer for instruction, and teachers’ perceptions of changes in ACT scores. A modest significant inverse relationship was found between teachers’ perceptions of one-to-one computing and teachers’ years of experience. As teachers’ years of experience increase, their perceptions of one-to-one computing tend to become less positive

Plot to Kill the President: A Novel

I was always skeptical of The Warren Report as were countless other Americans over the decades. I was reenergized to look more closely at November 22,1963, by a chance encounter with Brian heath, a JFK aficionado, who had made some startling discoveries about the assassination. He had studied meticulously the Nix film and concluded that the fatal shot came from within the presidential limousine from the driver, William Greer. Similarly, that many of JFK’s cabinet members consisted of former OSS spooks, who dominated the CIA, and were major spokesman for the national security state and America’s global dominance. They saw JFK’s rapprochement with Khrushchev after the Cuban missile crisis a threat to their world view. Vietnam was the breaking point as they saw in his policy of gradual withdrawal, the fall Ho Chi Minh City, as heralding the collapse of all of southeast Asia to the Chinese, described as the domino theory. Ironically, the latter never occurred. Plot to Kill the President, is our answer to keeping alive the idealism of the new frontier and the coup d’état that transpired. Recent events around January 6 under Trump show how fragile democracy and its institutions are. These weaknesses were apparent during the JFK’s period when there rose a groundswell of powerful forces that called for his removal and dramatically altered the trajectory of American history.https://scholar.dominican.edu/books/1181/thumbnail.jp

RevBayes: Bayesian Phylogenetic Inference Using Graphical Models and an Interactive Model-Specification Language.

Programs for Bayesian inference of phylogeny currently implement a unique and fixed suite of models. Consequently, users of these software packages are simultaneously forced to use a number of programs for a given study, while also lacking the freedom to explore models that have not been implemented by the developers of those programs. We developed a new open-source software package, RevBayes, to address these problems. RevBayes is entirely based on probabilistic graphical models, a powerful generic framework for specifying and analyzing statistical models. Phylogenetic-graphical models can be specified interactively in RevBayes, piece by piece, using a new succinct and intuitive language called Rev. Rev is similar to the R language and the BUGS model-specification language, and should be easy to learn for most users. The strength of RevBayes is the simplicity with which one can design, specify, and implement new and complex models. Fortunately, this tremendous flexibility does not come at the cost of slower computation; as we demonstrate, RevBayes outperforms competing software for several standard analyses. Compared with other programs, RevBayes has fewer black-box elements. Users need to explicitly specify each part of the model and analysis. Although this explicitness may initially be unfamiliar, we are convinced that this transparency will improve understanding of phylogenetic models in our field. Moreover, it will motivate the search for improvements to existing methods by brazenly exposing the model choices that we make to critical scrutiny. RevBayes is freely available at http://www.RevBayes.com [Bayesian inference; Graphical models; MCMC; statistical phylogenetics.]

ESSAYS ON TARGETED PROGRAMS IN EDUCATION

This dissertation examines three examples of education policy that affect students' decision-making at three different stages of the academic career. In the first chapter, I examine how grant aid can affect the re-enrollment and graduation rates of bachelor's degree-seeking students. I use administrative data from the State of Maryland to study the state's largest need-based grant aid program using a regression discontinuity design. I find positive effects of grant receipt on re-enrollment beginning in the second year and a 10\% increase in the rate of persistence to the fourth year, with similar-sized, but more imprecise effects on graduation within 5 years of entry. In the second chapter, I study State Loan Repayment Programs which pay down a physician's medical school debt in exchange for a period of service in a health care provider shortage area. I gather data from individual states on the amounts that their programs offer over time and use changes in designations of health care provider shortage areas to implement a generalized differences-in-differences strategy. I find no overall effect of the programs on the physician-to-population ratio of an area eligible for the program, though I do find evidence of a positive effect on the physician-to-population ratio when I focus on the age group where physicians are most likely to be recent medical school graduates. In the third chapter, I examine the effect of high school Career and Technical Education coursework completion on postsecondary enrollment, degree completion, and early career earnings. I utilize two estimation strategies. The first is a propensity score matching approach and the second is an instrumental variables approach based on the distance between a student's high school and a CTE Center that offers the coursework. The two strategies generally find that CTE is associated with a substitution from four-year programs to two-year programs, and positive effects on early career earnings

Association of intestinal alkaline phosphatase with necrotizing enterocolitis among premature infants

Importance: Necrotizing enterocolitis (NEC) in preterm infants is an often-fatal gastrointestinal tract emergency. A robust NEC biomarker that is not confounded by sepsis could improve bedside management, lead to lower morbidity and mortality, and permit patient selection in randomized clinical trials of possible therapeutic approaches. Objective: To evaluate whether aberrant intestinal alkaline phosphatase (IAP) biochemistry in infant stool is a molecular biomarker for NEC and not associated with sepsis. Design, Setting, and Participants: This multicenter diagnostic study enrolled 136 premature infants (gestational age, \u3c37 weeks) in 2 hospitals in Louisiana and 1 hospital in Missouri. Data were collected and analyzed from May 2015 to November 2018. Exposures: Infant stool samples were collected between 24 and 40 or more weeks postconceptual age. Enrolled infants underwent abdominal radiography at physician and hospital site discretion. Main Outcomes and Measures: Enzyme activity and relative abundance of IAP were measured using fluorometric detection and immunoassays, respectively. After measurements were performed, biochemical data were evaluated against clinical entries from infants\u27 hospital stay. Results: Of 136 infants, 68 (50.0%) were male infants, median (interquartile range [IQR]) birth weight was 1050 (790-1350) g, and median (IQR) gestational age was 28.4 (26.0-30.9) weeks. A total of 25 infants (18.4%) were diagnosed with severe NEC, 19 (14.0%) were suspected of having NEC, and 92 (66.9%) did not have NEC; 26 patients (19.1%) were diagnosed with late-onset sepsis, and 14 (10.3%) had other non-gastrointestinal tract infections. For severe NEC, suspected NEC, and no NEC samples, median (IQR) fecal IAP content, relative to the amount of IAP in human small intestinal lysate, was 99.0% (51.0%-187.8%) (95% CI, 54.0%-163.0%), 123.0% (31.0%-224.0%) (95% CI, 31.0%-224.0%), and 4.8% (2.4%-9.8%) (95% CI, 3.4%-5.9%), respectively. For severe NEC, suspected NEC, and no NEC samples, median (IQR) enzyme activity was 183 (56-507) μmol/min/g (95% CI, 63-478 μmol/min/g) of stool protein, 355 (172-608) μmol/min/g (95% CI, 172-608 μmol/min/g) of stool protein, and 613 (210-1465) μmol/min/g (95% CI, 386-723 μmol/min/g) of stool protein, respectively. Mean (SE) area under the receiver operating characteristic curve values for IAP content measurements were 0.97 (0.02) (95% CI, 0.93-1.00; P \u3c .001) at time of severe NEC, 0.97 (0.02) (95% CI, 0.93-1.00; P \u3c .001) at time of suspected NEC, 0.52 (0.07) (95% CI, 0.38-0.66; P = .75) at time of sepsis, and 0.58 (0.08) (95% CI, 0.42-0.75; P = .06) at time of other non-gastrointestinal tract infections. Mean (SE) area under the receiver operating characteristic curve values for IAP activity were 0.76 (0.06) (95% CI, 0.64-0.86; P \u3c .001), 0.62 (0.07) (95% CI, 0.48-0.77; P = .13), 0.52 (0.07) (95% CI, 0.39-0.67; P = .68), and 0.57 (0.08) (95% CI, 0.39-0.69; P = .66), respectively. Conclusions and Relevance: In this diagnostic study, high amounts of IAP protein in stool and low IAP enzyme activity were associated with diagnosis of NEC and may serve as useful biomarkers for NEC. Our findings indicated that IAP biochemistry was uniquely able to distinguish NEC from sepsis