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Shift‐share is a popular technique used by policymakers and researchers alike to decompose the change in a variable into within and between effects, intensive and extensive margins, or other comparable effects. One reason for the popularity of shift‐share is its relative simplicity compared to econometric techniques. However, often overlooked is that a shift‐share is actually an index number problem that uses differences instead of ratios. Techniques developed in index number theory accentuate the fact that the traditional shift‐share is biased. This paper proposes using the Bennet index to achieve unbiased measurements in shift‐share decompositions. In addition to solving the bias problem, the Bennet index removes the need for a residual and may be even simpler to calculate. While this paper is primarily theoretical, it also explores the differences between the traditional shift‐share and the Bennet index—both chained and fixed base—to measure the competitive and composition effects of Canada's export performance in the United States since 1990. [ABSTRACT FROM AUTHOR]

Engineering practitioners have widely adopted probabilistic methods for estimating liquefaction triggering hazards. Unfortunately, incorrect application of these methods has become commonly accepted in the United States and throughout many parts of the world. In this paper, we describe two specific incorrect applications of probabilistic liquefaction triggering prediction models that are commonly used in engineering practice: (1) improper parametric uncertainty characterization when using the models, and (2) the application of a conservative factor of safety thresholds to deterministic cyclic resistance ratio boundaries. These two practices and their implications are discussed, and illustrative examples and figures are presented. We also discuss the apparent inconsistencies in what constitutes an acceptable risk for liquefaction hazards and other significant geotechnical hazards, such as slope stability. We demonstrate the need to collectively consider the likelihoods of all aspects of liquefaction hazard problems—susceptibility, initiation, and effects—when calculating and considering liquefaction risk. Finally, we point to the concept and framework of performance-based earthquake engineering as a logical and objective path forward for dealing with the challenges raised in this study. [ABSTRACT FROM AUTHOR]

In pediatrics, an increasing need for transplantable organs exists. This study aimed to describe the epidemiology of pediatric deceased donors in the United States. This retrospective observational study utilized data from the Organ Procurement and Transplantation Network (OPTN) from 2000 to 2015. Patients were stratified based on method of organ donation. Demographic variables and mechanism of death were then compared. A total of 14,481 deceased pediatric organ donors, donation after brain death (DBD) and donation after circulatory death (DCD), were included in the study, of which 8% were DCD donors. A significant difference (p<0.001) existed between the two donor groups with respect to ethnicity and mechanism of death. The annual trend of DCD and DBD donors showed an inverse relationship. During the 15‐year study period the number of DBD donors decreased from 985 to 785 per year while DCD donors increased from 15 to 146 per year. As well, overall organs transplanted per year decreased from 3,475 to 3,117 over the 15‐year study period. Significant differences exist between pediatric DBD donors and DCD donors, specifically with respect to ethnicity and mechanism of death. The number of pediatric DBD donors is decreasing while the number of pediatric DCD is slowly rising, making it increasingly important to be able to characterize these donors to better identify eligible DCD donors to optimize organ utilization. [ABSTRACT FROM AUTHOR]

Anatomically similar rhegmatogenous retinal detachments (RRDs) can be treated with scleral buckle (SB), pars plana vitrectomy (PPV), or SB combined with PPV (PPV/SB). This study compares moderately complex phakic primary RRD treated with SB, PPV, or PPV/SB to review anatomic and visual outcomes. Multicenter, retrospective, interventional cohort study. Data were gathered on all patients from multiple retina practices in the United States with RRD in 2015 and >90 days of follow-up. The cohort of phakic patients with moderately complex RRD was analyzed. A large and detailed database was generated. Eyes with findings that would bias toward PPV (vitreous hemorrhage, dense cataract, proliferative vitreoretinopathy, giant retinal tear, among others) were excluded. Age <40 years (bias toward SB) was excluded. Comparable cases of moderately complex RRD were then chosen naive to surgeon, surgery, and outcome for subgroup analysis. Single surgery anatomic success (SSAS), defined as retinal attachment with no other RRD surgery within 90 days, is the main outcome measure. Final visual acuity is the secondary outcome measure. Pearson's chi-square and analysis of variance were used to test treatment effect of surgery type on SSAS and vision. Single surgery anatomic success was noted in 155 of 169 SB cases (91.7%), 207 of 249 PPV cases (83.1%), and 271 of 297 PPV/SB cases (91.2%). Scleral buckle and PPV/SB were superior to PPV for SSAS (P = 0.0041). For macula-on or split cases, SB had significantly better visual outcomes than PPV or PPV/SB even after controlling for cataract (cases with minimal cataract at final follow-up or after cataract surgery) (P < 0.001). For phakic moderately complex primary RRDs in this study of PPV versus SB versus PPV/SB, SB had the best visual outcomes, and PPV had the worst SSAS outcomes. [ABSTRACT FROM AUTHOR]

• Higher behavioral diversity with participation in more behavioral studies over time. • No relationship between welfare and concurrent study participation. Voluntary participation in behavioural studies offers several scientific, management, and welfare benefits to non-human primates (NHPs). Aside from the scientific benefit of increased understanding of NHP cognition, sociality, and behaviour derived from noninvasive behavioural studies, participation itself has the potential to provide functional simulations of natural behaviours, enrichment opportunities, and increased control over the captive environment, all of which enhance welfare. Despite a developing consensus that voluntary participation offers these welfare enhancements, little research has empirically investigated the ways that participation in behavioural studies may affect welfare. In the current study, we investigated potential relationships between captive chimpanzee welfare and long-term, repeated voluntary participation in noninvasive behavioural studies. We collected behavioural data on 118 chimpanzees at the National Center for Chimpanzee Care (NCCC) in Bastrop, Texas, USA between 2016 and 2018 using 15-minute focal animal samples. Additionally, we collected information on 41 behavioural studies conducted between 2010 and 2018 with the NCCC chimpanzees that involved exposure to a stimulus or manipulation. The total number of behavioural studies in which chimpanzees had participated over the approximately eight-year period was then examined in relation to levels of behavioural diversity, abnormal behaviour, rough scratching, inactivity, and locomotion using a series of regression analyses that controlled for rearing status and age of the chimpanzee at the time of data collection. Analyses revealed significant, positive relationships between the total number of studies in which chimpanzees participated and 1) behavioural diversity scores, R2 adj = 0.21, F (3,114) = 11.25, p < 0.001; and 2) rough scratching, R2 adj = 0.11, F (3,114) = 6.01, p = 0.001. The positive relationship between behavioural diversity scores and the total number of studies in which chimpanzees participated seems unsurprising, although we cannot draw conclusions about the directionality of this relationship. The result that rough scratching and the total number of studies in which chimpanzees participated were positively correlated is unexpected. However, rough scratching made up less than 1% of all activity in the current study, and as such, this result may not be biologically meaningful. These findings suggest that participation in behavioural studies is not likely to be detrimental to chimpanzee well-being, and may even be beneficial. Data such as these, which empirically investigate existing recommendations can help inform decisions pertaining to the participation of chimpanzees in behavioural research. [ABSTRACT FROM AUTHOR]

In this paper, we introduce the composite multiscale cross-sample entropy (CMCSE) which may induce undefined entropies and then further propose the refined composite multiscale cross-sample entropy (RCMCSE) which modifies CMCSE. First, we apply multiscale cross-sample entropy (MCSE), CMCSE and RCMCSE methods to three types of artificial time series in order to test the validity and accuracy of these methods. Results show that RCMCSE reduces not only standard deviation, but also the probability of inducing undefined entropy effectively, which can provide better robustness and more accurate entropies. Then, these three methods are employed to investigate financial time series including US and Chinese stock indices. For the study between stock indices in the same region, some conclusions which are consistent with previous study are drawn by the RCMCSE results. Meanwhile, it can be found that undefined entropies are induced and the numbers of inducing undefined entropy by three methods for investigation between three US stock indices and two Chinese mainland stock indices are given. Compared with MCSE and CMCSE, RCMCSE method is capable of reducing the number of undefined entropy and providing more accurate entropies. Moreover, the differences on inducing undefined entropy between results for US stock indices & two Chinese mainland stock indices and results for US stock indices & HSI demonstrate a much closer relation between US stock markets and HSI than between US stock markets and two Chinese mainland stock markets. Hence, it can be concluded that RCMCSE is more applicable for the study between US and Chinese stock markets. [ABSTRACT FROM AUTHOR]

This paper presents a probabilistic method to establish schedule contingency levels based on percent completion of the project. The objective is providing a distribution for contingency for various percent completion levels which allows the project owner/manager to choose the schedule contingency at their comfort level. The proposed method is applied on real data from a number of US transit projects and actual schedule overruns for different phases of the project development (preliminary engineering, final design and construction) are analyzed. These values are used to establish the required contingency at the conclusion of each of the mentioned project phases. Additionally, using these values, the required contingency at various points during the construction phase (such as 25% and 50% completion) is calculated and reported. This approach can be used by project owners to plan realistic schedules during various phases of the project, providing better control on duration and the opportunity for being prepared to take necessary action in case the available schedule contingency falls below reasonable levels. [ABSTRACT FROM AUTHOR]

The article examines the ideal dimensions of rectangular paper used in folding origami in the U.S. It explores the author's experience of allowing his students to investigate the different paper sizes, learn mathematical knowledge through problem solving and employ geometric modeling, number theory and algebraic concepts. It is noted that students manage to prove their conjectures and find the importance of minimizing repeated squares in obtaining the desired rectangle.

The article presents the solutions to mathematical problems provided by the National Council of Teachers of Mathematics in the U.S. These entails measuring angle PSQ which is an exterior of angle TQR, finding the integers needed for a given set of numbers, and finding the total hours to complete the trip for a given situation. The problems are adapted from various mathematical competitions. These include the 2009 Pascal, Cayley, and Fermat Mathematics Contests and from the American Regions Mathematics League 2009 Competition.

The article reports on the use of climate variables modeling tropical cyclone (CT) intensity with quantile regression in the U.S. An advantage of the quantile regression approach compared to traditional parametric extreme value model is that it permits easier interpretation of model coefficients. It is mathematically proven that parameters of the Generalized Pareto Distribution for extreme events can be applied to approximate coefficients for the extreme quantiles.

Focuses on the teaching of Pythagorean triples in the middle school mathematics curriculum in the United States. Definition and examples of a Pythagorean triple; Illustration of triples with integer difference of one; Investigation on the possibility of triples with integer difference of two and three; Classification of triples as primitive and nonprimitive.

Explores the nested ecology of infections by using martingale theorem of probability theory to study the endemic limit and apply Ito's stochastic calculus to analyze the approach to endemicity. Tuberculosis in Sweden and New York City, New York; AIDS in the United States; Conclusions.

Reports on a three week summer workshop for high school students held at Colorado College in 1992 and 1993. Examination of selected great problems from set theory, number theory and calculus using original sources; Improvement of lecture approach in 1992 by discovery approach and daily writing in 1993; Problem solving techniques; Listing of mathematical themes and sources.

The article reports on the methods being explored by the National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center (SPC) to explore the societal impacts of severe weather in the U.S. It states that SPC is using a combination of probabilistic forecasts and high-resolution population data to determine the societal impacts of tornadoes and tornadic thunderstorms. It also examines population density as an integral part of the methods.

The article reports a breakthrough in understanding of mathematics' "mock theta functions." Since they were first referred to by Indian mathematician Srinivasa Ramanujan in 1920, number theorists have struggled to understand these numerical expressions. In 2007, mathematicians Ken Ono and Kathrin Bringmann, of the University of Wisconsin at Madison, succeeded in using modern mathematical techniques to create an explanatory framework for mock theta functions and how to derive them.