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La calidad de los datos radiométricos disponibles para el estudio del fenómeno megalítico en Iberia ha mejorado notablemente en los últimos quince años. Como resultado, comienzan a surgir detalles relevantes en cuanto a la secuencia, temporalidad y evolución de ciertos tipos de monumentos, construcciones específicas y agrupaciones de ellas. En este artículo ampliamos esta línea de investigación al mega-sitio de la Edad del Cobre de Valencina, situado en el suroeste de la península ibérica. Presentamos 46 dataciones de radiocarbono inéditas realizadas sobre hueso humano y procedentes del área de enterramiento ubicada en el cuadrante sureste de este yacimiento, que incluye la cueva artificial La Huera, el sector PP4-Montelirio y el gran tholos de Montelirio. A través de modelos bayesianos y espaciales, esas nuevas fechas se combinan con ocho ya publicadas para proporcionar una imagen de alta resolución de la temporalidad de la compleja secuencia de enterramientos y deposición formal que tuvo lugar allí durante el período de apogeo de uso del sitio entre c. 2900 y 2650 a. C. Examinamos las fechas de inicio, secuencia, disposición espacial, duración y fecha de finalización de 21 estructuras recientemente datadas, para discutir posteriormente las implicaciones de los resultados en términos de las prácticas sociales que llevaron a la formación de este mega-sitio.

Species declines and extinctions characterize the Anthropocene. Determining species vulnerability to decline, and where and how to mitigate threats, are paramount for effective conservation. We hypothesized that species with shared ecological traits also share threats, and therefore may experience similar population trends. Here, we used a Bayesian modeling framework to test whether phylogeny, geography, and 22 ecological traits predict regional population trends for 380 North American bird species. Groups like blackbirds, warblers, and shorebirds, as well as species occupying Bird Conservation Regions at more extreme latitudes in North America, exhibited negative population trends; whereas groups such as ducks, raptors, and waders, as well as species occupying more inland Bird Conservation Regions, exhibited positive trends. Specifically, we found that in addition to phylogeny and breeding geography, multiple ecological traits contributed to explaining variation in regional population trends for North American birds. Furthermore, we found that regional trends and the relative effects of migration distance, phylogeny, and geography differ between shorebirds, songbirds, and waterbirds. Our work provides evidence that multiple ecological traits correlate with North American bird population trends, but that the individual effects of these ecological traits in predicting population trends often vary between different groups of birds. Moreover, our results reinforce the notion that variation in avian population trends is controlled by more than phylogeny and geography, where closely related species within one region can show unique population trends due to differences in their ecological traits. We recommend that regional conservation plans, i.e. one-size-fits-all plans, be implemented only for bird groups with population trends under strong phylogenetic or geographic controls. We underscore the need to develop species-specific research and management strategies for other groups, like songbirds, that exhibit high variation in their population trends and are influenced by multiple ecological traits. [ABSTRACT FROM AUTHOR]

Nonparametric procedures are used to add flexibility to models. Three nonparametric item response models have been proposed, but not directly compared: the Kernel smoothing (KS-IRT); the Davidian-Curve (DC-IRT); and the Bayesian semiparametric Rasch model (SP-Rasch). The main aim of the present study is to compare the performance of these procedures in recovering simulated true scores, using sum scores as benchmarks. The secondary aim is to compare their performances in terms of practical equivalence with real data. Overall, the results show that, apart from the DC-IRT, which is the model that performs the worse, all the other models give results quite similar to those when sum scores are used. These results are followed by a discussion with practical implications and recommendations for future studies. [ABSTRACT FROM AUTHOR]

Se analiza la secuencia temporal funeraria de un monu­mento megalítico de la Meseta Norte, el dolmen de Los Zu­macales (Simancas, Valladolid), fechado anteriormente en torno a la primera mitad del IV milenio cal AC. La secuencia se basa en 12 nuevas dataciones radiocarbónicas por AMS obtenidas mediante huesos humanos, seleccionadas a partir del número mínimo de individuos representados en el osario. El modelado bayesiano de las fechas define un marco tempo­ral de uso entre 3846-3756 y 3627-3550 cal AC (1σ), coinci­dente con las primeras series funerarias megalíticas regionales. La concentración de la mayoría de las dataciones del IV mi­lenio cal AC revela que la utilización del dolmen fue proba­blemente más intensa en su primera etapa. Además, el análi­sis ha identificado un individuo depositado al inicio del Calcolítico, algo que, sin dejar de considerar que la fecha sea errónea, supondría el reconocimiento de una reutilización pre­histórica de la que nada se conocía hasta ahora.

The Middle Mississippian component at Aztalan was a mixed, LateWoodland / Mississippian occupation sited within a heavily fortified habitation and mound center that is located on a tributary of the Rock River in Wisconsin. It represents the northernmost large Cahokian-related village recorded. The Oneota Lake Koshkonong Locality of the Rock River drainage is located approximately 20 km south of Aztalan, and it consists of a 25 km2 area along the northwest shore with a small cluster of habitation settlements. Sixty-eight radiocarbon measurements have been obtained from Aztalan, and 52 from Oneota settlements in the Lake Koshkonong Locality. We discuss how to best interpret this dataset, and we use Bayesian chronological modeling to analyze these dates. The results suggest that (1) Aztalan's Late Woodland (Kekoskee phase) occupation began in the AD 900s or early AD 1000s, (2) Aztalan's Mississippian occupation ceased in the AD 1200s, (3) Oneota occupations at Lake Koshkonong began after AD 1050 and were established by the AD 1200s, and (4) Oneota occupations at Lake Koshkonong continued after Aztalan's Mississippian abandonment until at least the late AD 1300s. Additionally, the results demonstrate that Aztalan was fortified with a palisade with bastions for much of the Mississippian occupation, suggesting a contested presence in a multiethnic landscape. [ABSTRACT FROM AUTHOR]

Gracias al reciente desarrollo de la cronología radiocarbónica, por primera vez existe una serie de dataciones robusta y fiable para analizar uno de los tipos de monumentos megalíticos más característicos de la península ibérica, las sepulturas tipo tholos. Una nueva serie de 193 fechas pertenecientes a 42 sepulturas distribuidas por el sur de España y el centro y sur de Portugal ha sido analizada utilizando modelos estadísticos y herramientas de análisis espacial. Los resultados permiten establecer cuatro conclusiones principales: i) las tumbas tipo tholos aparecieron por primera vez en el sureste de Iberia alrededor del siglo XXXII cal BC como un desarrollo independiente; ii) a partir de esa región se fueron extendiendo progresivamente hasta alcanzar su máxima expansión en el siglo XXIX cal BC; iii) los tholoi también difieren regionalmente en sus períodos de uso: largos periodos de actividad mortuoria en el sureste versus cortos períodos en el suroeste; y iv) a partir del 2200 cal BC, la actividad funeraria quedó restringida a prácticas ocasionales de reutilización, excepto en el sureste donde se documentan dos periodos de intensa actividad mortuoria en los siglos XIX y XIV cal BC respectivamente. Esta variabilidad regional enfatizaría diferentes trayectorias sociales para los dos focos principales de tumbas tipo tholos, las regiones del sureste y suroeste de la península ibérica.

As the use of large-scale radiocarbon datasets becomes more common and applications of Bayesian chronological modeling become a standard aspect of archaeological practice, it is imperative that we grow a community of both effective users and consumers. Indeed, research proposals and publications now routinely employ Bayesian chronological modeling to estimate age ranges such as statistically informed starts, ends, and spans of archaeological phenomena. Although advances in interpretive techniques have been widely adopted, sampling strategies and determinations of appropriate sample sizes for radiocarbon data remain generally underdeveloped. As chronological models are only as robust as the information we feed into them, formal approaches to assessing the validity of model criteria and the appropriate number of radiocarbon dates deserve attention. In this article, through a series of commonly encountered scenarios, we present easy-to-follow instructions for running simulations that should be used to inform the design and construction of chronological models. [ABSTRACT FROM AUTHOR]

This paper summarises recent test excavations at five Mound Village sites in the south-eastern sector of Acre state, Brazil, including Caboquinho, Boa Esperança, Tocantins, Dois Círculos IV and V. Radiocarbon dates obtained from the excavation of these sites refine the chronology of this archaeological tradition. To improve the chronologies of the mound villages in Acre for which radiocarbon dates were available, we modelled them using Bayesian statistics. Bayesian modelling of new radiocarbon dates from basal contexts of nine sites in the region establish the beginning of this archaeological tradition at ~ AD 952-1216. Nine dates from ten construction phases at the Caboquinho site establish the longest sequence from ~ AD 1169-1309 to colonial times. The stratigraphy of the test units reported in this study confirms previous results indicating that mounds are the result of alternating construction and occupation episodes. Dates from the Dois Círculos IV Rectangular Mound Village ~ AD 1367-1451 indicates that Rectangular Villages are broadly contemporaneous with Circular Mound Villages. Single dates from three superimposed villages at Dois Círculos V suggest the succession of village construction. Overall, these preliminary results make a contribution to a better understanding of the timing of emergence and demise of Mound Village construction. [ABSTRACT FROM AUTHOR]

Rebuilding and repairing damaged physical infrastructure is a primary source of disaster aid spending following major earthquakes. Although aid distribution is monitored, it is not well understood how economic support and technical assistance affect reconstruction behavior. This study develops and evaluates a Bayesian item response theory modeling framework for estimating the probability of reconstructive action from household-level survey data. Household responses on reconstruction status, aid received, and willingness to commit additional resources from Inter-Agency Common Feedback Project surveys (n = 5,913) collected eleven, twelve, and fourteen months after the Gorkha, Nepal, earthquake are used to estimate the probability of reconstructive action. Results show differences in marginal reconstruction probabilities ranging from 2 to 78 percent across varying combinations of aid receipt and household willingness to commit additional resources. Estimated reconstruction probabilities are lowest for households with low willingness to commit additional resources and households that have not received a reconstruction-related engineering consultation. All model results showed strong variability with geographic location. These findings provide detailed quantitative estimates of earthquake recovery that have not previously been available and offer a promising methodology for using future postdisaster household-level survey data. [ABSTRACT FROM AUTHOR]

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Por primera vez en el estudio del fenómeno megalítico del sureste de la Península Ibérica se ha obtenido una serie radiocarbónica para el análisis de sus manifestaciones más antiguas. Se han datado 30 restos antropológicos de sepulturas tipo rundgräber y de tumbas de cámara y corredor pertenecientes a las necrópolis de Las Churuletas, La Atalaya y Llano de El Jautón. El análisis estadístico de esta serie radiocarbónica ha permitido establecer las siguientes conclusiones: i) el inicio de la actividad funeraria ocurriría entre el 3730-3650 cal BC y el final entre el 2395-2270 cal BC; ii) las sepulturas tipo rundgräber son las que poseen una duración más corta, finalizando entre el 2650-2505 cal BC; III) la datación de diferentes sepulturas y necrópolis muestra una importante heterogeneidad en sus periodos de uso; y iv) a partir de principios del III milenio se produciría una significativa intensificación de la actividad funeraria paralela al incremento demográfico y desarrollo del poblamiento.

Fremont societies of the Uinta Basin incorporated domesticates into a foraging lifeway over a 1,000-year period from AD 300 to 1300. Fremont research provides a unique opportunity to critically examine the social and ecological processes behind the adoption and abandonment of domesticates by hunter-gatherers. We develop and integrate a 2,115-year precipitation reconstruction with a Bayesian chronological model for the growth of Fremont societies in the Cub Creek reach of Dinosaur National Monument. Comparison of the archaeological chronology with the precipitation record suggests that the florescence of Fremont societies was an adaptation to multidecadal precipitation variability with an approximately 30-plus-year periodicity over most, but not all, of the last 2,115 years. Fremont societies adopted domesticates to enhance their resilience to periodic droughts. We propose that reduced precipitation variability from AD 750 to AD 1050, superimposed over consistent mean precipitation availability, was the tipping point that increased maize production, initiated agricultural intensification, and resulted in increased population and development of pithouse communities. Our study develops a multidecadal/multigenerational model within which to evaluate the strategies underwriting the adoption of domesticates by foragers, the formation of Fremont communities, and the inherent vulnerabilities to resource intensification that implicate the eventual dissolution of those communities. [ABSTRACT FROM AUTHOR]

Abstract: Ecological communities typically change along gradients of human impact, although it is difficult to estimate the footprint of impacts for diffuse threats such as pollution. We developed a joint model (i.e., one that includes multiple species and their interactions with each other and environmental covariates) of benthic habitats on lagoonal coral reefs and used it to infer change in benthic composition along a gradient of distance from logging operations. The model estimated both changes in abundances of benthic groups and their compositional turnover, a type of beta diversity. We used the model to predict the footprint of turbidity impacts from past and recent logging. Benthic communities far from logging were dominated by branching corals, whereas communities close to logging had higher cover of dead coral, massive corals, and soft sediment. Recent impacts were predicted to be small relative to the extensive impacts of past logging because recent logging has occurred far from lagoonal reefs. Our model can be used more generally to estimate the footprint of human impacts on ecosystems and evaluate the benefits of conservation actions for ecosystems. [ABSTRACT FROM AUTHOR]

Introduction. Chagas disease is a systemic infection caused by the protozoan Trypanosoma cruzi. There is evidence that environmental factors favor the maintenance of the infection. Objective. To understand the spatial distribution patterns of risk, and environmental and socioeconomic factors that favour the spread of Chagas disease. Material and methods. Data on Chagas disease incidence in the Huasteca Potosina were collected during 2003-2012 and then analyzed by a Bayesian method of spatial regression. Results. A clear pattern of spatial distribution of incidence of the disease in the Huasteca was observed, and it was significantly correlated with the final multivariate regression model using variables such as the minimum temperature, % of households with dirt floors, % of households without running water, % of population with three years and over speaking indigenous languages only, % of population over 15 years illiterate, % entitled to health care, % of households with some level of overcrowding and % of households with basic services. Conclusions. The analysis showed that the indigenous population is the most affected by Chagas disease and that was related to lack to basic services (health, education, housing), therefore, those conditions favor not only the presence of the vector but also the disease. In the Huasteca, this population lives in areas of difficult access, which hinders the implementation of appropriate programs to control the vector and the infection. [ABSTRACT FROM AUTHOR]

In the last 20 years, the growing availability of radiometric data has led to profound changes in the archaeological study of cultural and social processes in European Late Prehistory. In this paper, we examine how the combined use of spatial analysis and Bayesian modelling can further contribute to an enhanced interpretation of the temporality of a major social phenomenon: the "megalithisation" process in Iberia. For the first time, it is possible to compare hypotheses regarding the start date, speed and direction of the spread of this major process for the whole of Iberia, and not just for selected regions or single sites. [ABSTRACT FROM AUTHOR]