The accelerating influence of humans on mammalian macroecological patterns over the late Quaternary

The transition of hominins to a largely meat-based diet ~1.8 million years ago led to the exploitation of other mammals for food and resources. As hominins, particularly archaic and modern humans, became increasingly abundant and dispersed across the globe, a temporally and spatially transgressive extinction of large-bodied mammals followed; the degree of selectivity was unprecedented in the Cenozoic fossil record. Today, most remaining large-bodied mammal species are confined to Africa, where they coevolved with hominins. Here, using a comprehensive global dataset of mammal distribution, life history and ecology, we examine the consequences of “body size downgrading” of mammals over the late Quaternary on fundamental macroecological patterns. Specifically, we examine changes in species diversity, global and continental body size distributions, allometric scaling of geographic range size with body mass, and the scaling of maximum body size with area. Moreover, we project these patterns toward a potential future scenario in which all mammals currently listed as vulnerable on the IUCN\u27s Red List are extirpated. Our analysis demonstrates that anthropogenic impact on earth systems predates the terminal Pleistocene and has grown as populations increased and humans have become more widespread. Moreover, owing to the disproportionate influence on ecosystem structure and function of megafauna, past and present body size downgrading has reshaped Earth\u27s biosphere. Thus, macroecological studies based only on modern species yield distorted results, which are not representative of the patterns present for most of mammal evolution. Our review supports the concept of benchmarking the “Anthropocene” with the earliest activities of Homo sapiens

Observational data analysis using generalizability theory and general and mixed linear models: An empirical study of infant learning and development

Accurate evaluation of early childhood competencies is essential for favoring optimal development, as the first years of life form the foundations for later learning and development. Nonetheless, there are still certain limitations and deficiencies related to how infant learning and development are measured. With the aim of helping to overcome some of the difficulties, in this article we describe the potential and advantages of new data analysis techniques for checking the quality of data collected by the systematic observation of infants and assessing variability. Logical and executive activity of 48 children was observed in three ages (18, 21 and 24 months) using a nomothetic, follow-up and multidimensional observational design. Given the nature of the data analyzed, we provide a detailed methodological and analytical overview of generalizability theory from three perspectives linked to observational methodology: intra- and inter-observer reliability, instrument validity, and sample size estimation, with a particular focus on the participant facet. The aim was to identify the optimal number of facets and levels needed to perform a systematic observational study of very young children. We also discuss the use of other techniques such as general and mixed linear models to analyze variability of learning and development. Results show how the use of Generalizability Theory allows controlling the quality of observational data in a global structure integrating reliability, validity and generalizability. Una adecuada evaluación de las competencias infantiles tem-pranas es esencial para potenciar un desarrollo óptimo, pues los primeros años de vida son la base de todo el desarrollo y aprendizaje posterior. Sin embargo, todavía existen ciertas limitaciones y deficiencias en el ámbito de la medición del desarrollo y aprendizaje infantil. Con el objetivo último de contribuir a la mejora de esta situación, este trabajo presenta las posibilida-des y ventajas que ofrecen nuevas técnicas de análisis de datos, tanto para controlar la calidad de los datos infantiles registrados a través de observa-ción sistemática como para analizar su variabilidad. Se ha observado en tres edades diferentes (18, 21 y 24 meses) la actividad lógica y ejecutiva de 48 niños usando un diseño observacional nomotético, de seguimiento y mul-tidimensional. Dadas las particularidades de los datos del estudio que presentamos, desde el punto de vista metodológico y su análisis, realizamos análisis pormenori-zados a través de la Teoría de la Generalizabilidad en tres vertientes posi-bles en un estudio observacional: Análisis de la fiabilidad intra e inter-observadores, Análisis de la validez del instrumento de observación y Es-timación muestral de las facetas estudiadas (en concreto, la de participan-tes). De esta forma, se pretende optimizar el número de facetas y niveles necesarios para llevar a cabo un estudio de tales características. Además, se utilizan otras técnicas analíticas para conocer la variabilidad del desarrollo y aprendizaje infantil, como son el Modelo Lineal General y el Modelo MIXED. Los resultados indican cómo el uso de la Teoría de la Generalizabilidad permite controlar la calidad de los datos observacionales en una estructura única que integra la fiabilidad, validad y generalizabilidad

Asymptotics of Regulated Field Commutators for Einstein-Rosen Waves

We discuss the asymptotic behavior of regulated field commutators for linearly polarized, cylindrically symmetric gravitational waves and the mathematical techniques needed for this analysis. We concentrate our attention on the effects brought about by the introduction of a physical cut-off in the study of the microcausality of the model and describe how the different physically relevant regimes are affected by its presence. Specifically we discuss how genuine quantum gravity effects can be disentangled from those originating in the introduction of a regulator.Comment: 9 figures, 19 pages in DIN A4 format. Accepted for publication in Journal of Mathematical Physic

The Coupling of Shape Dynamics to Matter

Shape Dynamics (SD) is a theory dynamically equivalent to vacuum General Relativity (GR), which has a different set of symmetries. It trades refoliation invariance, present in GR, for local 3-dimensional conformal invariance. This contribution to the Loops 11 conference addresses one of the more urgent questions regarding the equivalence: is it possible to incorporate normal matter in the new framework? The answer is yes, in certain regimes. We present general criteria for coupling and apply it to a few examples.The outcome presents bounds and conditions on scalar densities (such as the Higgs potential and the cosmological constant) not present in GR.Comment: 4 pages. Contribution to Loops '11 conference in Madrid, to appear in Journal of Physics: Conference Series (JPCS

Evolution Operators for Linearly Polarized Two-Killing Cosmological Models

We give a general procedure to obtain non perturbative evolution operators in closed form for quantized linearly polarized two Killing vector reductions of general relativity with a cosmological interpretation. We study the representation of these operators in Fock spaces and discuss in detail the conditions leading to unitary evolutions.Comment: Accepted for publication in Physical Review

Estimación de la captura de carbono en plantaciones de álamo clon 1-63/51 de la comuna de retiro, región del Maule

58 p.Actualmente en el mundo existe una gran preocupación por el calentamiento de la tierra debido al aumento de las concentraciones de gases de efecto invernadero. Uno de los principales responsables del efecto invernadero es el CO2 en la atmosfera, originado principalmente por las actividades antropicas. Los bosques y plantaciones son unos de los grandes sumideros del CO2, que contribuyen al secuestro de carbono atmosférico por medio de la fotosíntesis y la acumulación de biomasa. El objetivo del presente estudio fue cuantificar la fijación de carbono en una plantación de álamos del clon I-63/51 presente en la comuna de Retiro, región del Maule. Para la estimación del carbono fijado en las fuentes de la biomasa aérea, raíz, hojarasca y suelo, se utilizaron parcelas circulares de 500 m2. En cada parcela se midieron la altura total del árbol y su diámetro a la altura del pecho (1.3 m). Dentro de la parcela, se ubicaron subparcelas de 1 m2, donde se tomaron muestras de hojarasca y suelo (profundidad de 0 – 30 cm). Para la estimación de la biomasa aérea, se utilizaron ecuaciones generales. Para el caso de la hojarasca, se estimó la biomasa seca a través del peso húmedo y seco. La biomasa de las raíces, se estimo en base a un porcentaje (24%) con respecto a la biomasa aérea. Para el cálculo de carbono orgánico de la biomasa aérea, hojarasca y raíces, se utilizó un factor de 0.531. El carbono orgánico del suelo, se determinó en el laboratorio de suelo de la Universidad Austral de Chile. Entre los rodales estudiados, el rodal el Calabozo presentó la mayor cantidad de carbono fijado en sus diferentes fuentes (120.8 tC/ha), siguiéndole el rodal San Juan con 90.1 tC/ha y por último el rodal las Lenguas con 61.1 tC/ha. El componente fuste representó entre el 67.9 a 73.6 % de carbono almacenado en el sistema, siguiéndole la biomasa de la raíz de 16.4 al 17.6 %, el suelo de 6.6 a 11.6 % y por último la hojarasca de 2.1 a 4.1 %./SUMMARY: Currently in the world, there is a concern for the global warming of the earth, due to the increase in the concentrations of greenhouse gases. One of the main responsible for the greenhouse effect is the dioxide of carbon in the atmosphere, mainly due to human activities. Forests and plantations are one of the large sinks of carbon dioxide, which contributes to the abduction of atmospheric carbon in carrying out their photosynthesis and biomass accumulation. The objective of this study was to quantify the fixation of carbon in a poplar plantation of the clone I-63/51 present at the commune of Retiro, region Maule. For the estimation of the carbon fixed in the component of biomass aerial, root, leaf litter and soil, were used circular plots of 500 m2. In each plot, proceeded to inventory, were measured the total height of the tree and its diameter at breast height (1.3 m). Within the plot a subplot of 1 m2 was located, where samples were taken from leaf litter and soil (depth of 0 - 30 cm). For the estimation of the aerial biomass, were used general equations. In the case of the leaf litter, were estimate by the dry and humid samples. The biomass roots were estimate in base of the 24% of the biomass aerial. For the calculation of organic carbon from the biomass aerial, leaf litter and roots, were estimate by the factor defect of 0.531. Organic carbon in the soil, it was determined in the laboratory of soil of the Universidad Austral de Chile. Among the stands studied stand the Calabozo presented the greatest amount of carbon fixed in their different sources (120.8 tC/ha), followed by stand San Juan with 90.1 tC/ha and finally the stand the Lenguas with 61.1 tC/has. The component stem represent between 67.9 to 73.6 % of carbon stored in the system, followed by the biomass from the root of 16.4 to 17.6 %, the soil from 6.6 to 11.6 % and finally the leaf litter of 2.1 to 4.1 %