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Since 1999, intensive research efforts have vastly increased what is known about the history of coerced migration of transatlantic slaves. A huge database of slave trade voyages from Columbus's era to the mid-nineteenth century is now available on an open-access Web site, incorporating newly discovered information from archives around the Atlantic world. The groundbreaking essays in this book draw on these new data to explore fundamental questions about the trade in African slaves. The research findings-that the size of the slave trade was 14 percent greater than had been estimated, that trade above and below the equator was largely separate, that ports sending out the most slave voyages were not in Europe but in Brazil, and more-challenge accepted understandings of transatlantic slavery and suggest a variety of new directions for important further research. For the most complete database on slave trade voyages ever compiled, visit www.slavevoyages.org.

Objective: The purpose of this paper is to provide some current information on the topic of the underserved and unserved populations including modern-day slaves, stateless/displaced persons, refugees/migrants and indigenous populations. Method: Speech-language pathology education and services for the underserved as well as unserved populations are discussed. Three case studies which demonstrate knowledge transfer and exchange as potential models for future development are presented. Conclusion: These case studies lead to more inquiries, studies, innovations and involvement from individuals and groups who are concerned about the underserved and unserved populations.

The majority of labor transactions throughout much of history and a significant fraction of such transactions in many developing countries today are \"coercive,\" in the sense that force or the threat of force plays a central role in convincing workers to accept employment or its terms. We propose a tractable principal-agent model of coercion, based on the idea that coercive activities by employers, or \"guns,\" affect the participation constraint of workers. We show that coercion and effort are complements, so that coercion increases effort, but coercion always reduces utilitarian social welfare. Better outside options for workers reduce coercion because of the complementarity between coercion and effort: workers with a better outside option exert lower effort in equilibrium and thus are coerced less. Greater demand for labor increases coercion because it increases equilibrium effort. We investigate the interaction between outside options, market prices, and other economic variables by embedding the (coercive) principal-agent relationship in a general equilibrium setup, and studying when and how labor scarcity encourages coercion. General (market) equilibrium interactions working through the price of output lead to a positive relationship between labor scarcity and coercion along the lines of ideas suggested by Domar, while interactions those working through the outside option lead to a negative relationship similar to ideas advanced in neo-Malthusian historical analyses of the decline of feudalism. In net, a decline in available labor increases coercion in general equilibrium if and only if its direct (partial equilibrium) effect is to increase the price of output by more than it increases outside options. Our model also suggests that markets in slaves make slaves worse off, conditional on enslavement, and that coercion is more viable in industries that do not require relationship-specific investment by workers.

The pervasiveness of tenancy in the postbellum South had countervailing effects on marriage between African Americans. Tenancy placed severe constraints on African American women's ability to find independent agricultural work. Freedwomen confronted not only planters' reluctance to contract directly with women but also whites' refusal to sell land to African Americans. Marriage consequently became one of African American women's few viable routes into the agricultural labor market. We find that the more counties relied on tenant farming, the more common was marriage among their youngest and oldest African American residents. However, many freedwomen resented their subordinate status within tenant marriages. Thus, we find that tenancy contributed to union dissolution as well as union formation among freedpeople. Microdata tracing individuals' marital transitions are consistent with these county-level results.

Bayesian additive regression trees (BART) is a Bayesian approach to flexible nonlinear regression which has been shown to be competitive with the best modern predictive methods such as those based on bagging and boosting. BART offers some advantages. For example, the stochastic search Markov chain Monte Carlo (MCMC) algorithm can provide a more complete search of the model space and variation across MCMC draws can capture the level of uncertainty in the usual Bayesian way. The BART prior is robust in that reasonable results are typically obtained with a default prior specification. However, the publicly available implementation of the BART algorithm in the R package BayesTree is not fast enough to be considered interactive with over a thousand observations, and is unlikely to even run with 50,000 to 100,000 observations. In this article we show how the BART algorithm may be modified and then computed using single program, multiple data (SPMD) parallel computation implemented using the Message Passing Interface (MPI) library. The approach scales nearly linearly in the number of processor cores, enabling the practitioner to perform statistical inference on massive datasets. Our approach can also handle datasets too massive to fit on any single data repository.

Despite Civil Rights legislation, racial inequality persists, especially in the context of poverty. This study advances the literature on racial inequality and the Southern legacy of slavery by examining slavery's relationship with inequality in poverty. I analyze county-level U.S. Census data using regression and spatial data analysis techniques. I find the 1860 slave concentration is related to contemporary black-white inequality in poverty, independent of contemporary demographic and economic conditions, racialized wealth disparities and racial threat. My research suggests the importance of slavery for shaping existing U.S. racial inequality patterns. Insights derived from this research, including the formulation of legacy as a place-based, continuous phenomenon that is distinct from racial threat, provide the basis for future research on legacy's mechanisms.

A new master/slave model driven, and an optimization algorithm-based proportional–integral–derivative (PID) plus second-order derivative (PIDD 2 ) controller is proposed in this work for a stable and efficient operation of an automatic voltage regulator (AVR) system. In this context, an ideal reference model of Bode is used as a master model. The new improved optimization algorithm is constructed via integrating the Lévy flight mechanism into Runge–Kutta optimizing algorithm. This algorithm optimally tunes the PIDD 2 controller with the aid of a cost function known as integral of squared error. The latter control mechanism forms the slave model. As the PIDD 2 controller and the intelligent tuning algorithm attempt to follow the response dictated by the ideal reference model of the master model, a significant improvement is achieved for the efficiency and the stability of the AVR system. The proposed master/slave driven, and intelligent optimization algorithm-based PIDD 2 control approach presents more excellent transient response (steady state error, rise time, settling time, peak time, percent overshoot), frequency response (gain margin, phase margin and bandwidth), robustness and stability. Nonideal conditions such as measurement noise and the saturation at the input of the generator in the AVR are also considered to demonstrate the efficacy of the proposed method. Furthermore, the existing fifty-eight techniques in the literature are also used for performance comparison in order to present the more excellent efficiency of the proposed method from a wider perspective.

Many researchers use an ordinal scale to quantitatively measure and analyze concepts. Theoretically valid empirical estimates are robust in sign to any monotonic increasing transformation of the ordinal scale. This presents challenges for the point-identification of important parameters of interest. I develop a partial identification method for testing the robustness of empirical estimates to a range of plausible monotonic increasing transformations of the ordinal scale. This method allows for the calculation of plausible bounds around effect estimates. I illustrate this method by revisiting analysis by Nunn and Wantchekon (2011, American Economic Review, 101, 3221–3252) on the slave trade and trust in sub-Saharan Africa. Supplemental illustrations examine results from (i) Aghion et al. (2016, American Economic Review, 106, 3869–3897) on creative destruction and subjective well-being and (ii) Bond and Lang (2013, The Review of Economics and Statistics, 95, 1468–1479) on the fragility of the black–white test score gap.

Between 1774, the date of the first official enumeration, and the end of the following century, the population of Cuba grew ninefold to 1.6 million, mostly because of the slave trade, and immigration from Spain. While census data offer a relatively dependable mass of data, although spare in details, vital statistics are rare and of very poor quality. The paper attempts an analysis of the factors of growth of the three major “racial” groups—the White, the Mulatto, and the Black—and of their mixing. It confirmed the commonly accepted notion of the higher mortality, and lower fertility, of the Black population (mainly slaves): its losses due to the negative natural balance were more than offset in the first phase by the inflow of slaves. But the Black population declined in the second part of the nineteenth century with the demise of the trade. The theory of the fastest growth of the Mulatto group because of the frequent intrusion of the White males in the Black reproductive pool, could not be clearly verified, although it is fully supported by the developments of the following century.

This paper concerns the behavior of time-periodic solutions to 1D dissipative autonomous semilinear hyperbolic PDEs under the influence of small time-periodic forcing. We show that the phenomenon of forced frequency locking happens similarly to the analogous phenomena known for ODEs or parabolic PDEs. However, the proofs are essentially more difficult than for ODEs or parabolic PDEs. In particular, non-resonance conditions are needed, which do not have counterparts in the cases of ODEs or parabolic PDEs. We derive a scalar equation which answers the main question of forced frequency locking: Which time shifts u ( t + φ ) of the solution u ( t ) to the unforced equation do survive under which forcing?