Tres miradas sobre una escápula arqueológica de vicuña procedente de un sitio cordillerano (ARQ18, San Juan, Argentina)

Este trabajo se inserta en un proyecto mayor de investigación que tiene como objetivo principal contribuir al conocimiento de la subsistencia humana en el Centro-Oeste argentino. Especialmente, se refiere al aprovechamiento de camélidos, estableciendo la presencia de diversos morfotipos (silvestres y domésticos), y determinando las estrategias económicas implementadas para su consumo, por parte de los pobladores de la región a lo largo del Holoceno. Frente a la necesidad de precisar la identificación de restos arqueológicos de camélidos se aplican variadas técnicas de análisis, siendo las más frecuentes: osteometría, morfología de incisivos y fibras, y recientemente isótopos estables y ADNa. Cada una presenta fortalezas y limitaciones, y por ello se considera que su combinación podría mejorar la discriminación buscada. Se presentan, a modo de ejemplo, resultados de la combinación de osteometría, pruebas estadísticas multivariadas, isótopos y ADNa, realizada sobre un espécimen arqueológico, una escápula del sitio ARQ-18, con contexto fechado en 3090 años Cal. A.P. (3340-2870, 2 sigma), con el objetivo de lograr su identificación taxonómica. El espécimen testeado se identificó como vicuña, morfométricamente similar a seis especímenes comparativos actuales. En cambio, los resultados de isótopos no permitieron una discriminación taxonómica, mientras que el ADNa la alcanzó a nivel de subespecie para Vicugna. Frente a ello, se apunta a fortalecer la osteometría, pruebas estadísticas y colecciones de referencia, dado que han arrojado satisfactorios resultados en diversas partes de los Andes. Comparada con los otros métodos novedosos, tiene más potencia para distinguir entre camélidos domésticos y silvestres. Resulta más económica, no destructiva, puede aplicarse sobre una mayor cantidad de especímenes y con básicos requisitos en conservación, además sus resultados pueden replicarse.This paper is part of a larger research project, whose principal goals include contributing to the knowledge of human subsistence in Central West Argentina. Specifically, they address the use of camelids, establishing the presence of diverse morphotypes (wild and domestic) and determining economic strategies, in terms of the consumption of these animals by inhabitants of the region throughout the Holocene. Given the necessity of more precisely identifying camelid archaeological remains, various techniques have been used. The most common are: osteometry, incisor and fiber morphology, and recently, stable isotopes and aDNA. Each of these analysis has strengths and weaknesses, and for this reason, combining them may be able to improve the desired distinction. This paper presents, as an example, a combination of osteometry, multivariate statistics, isotopes, and aDNA from a single archaeological specimen, a scapula from the site ARQ-18, in a context dated to 3090 cal B.P. (3340-2870, 2 sigma), with the goal of identifying the species. The tested specimen was identified as Vicugna vicugna, as it is morphometrically similar to six modern comparative specimens. In contrast, the results of isotopes did not allow for a taxonomic discrimination, while the aDNA did so to the level of genus. Based on this, osteometry, statistical tests, and reference collections should be improved, which have already been successfully applied in various parts of the Andes. Compared to the other newer methods, osteometry has more potential to distinguish between domestic and wild camelids. It is much affordable, non- destructive, does not require excellent preservation, and generates results which can be replicated.Fil: Gasco, Alejandra Valeria. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Paleoecología Humana; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Metcalf, Jessica. University of Colorado; Estados Unido

On the optimization of bipartite secret sharing schemes

Optimizing the ratio between the maximum length of the shares and the length of the secret value in secret sharing schemes for general access structures is an extremely difficult and long-standing open problem. In this paper, we study it for bipartite access structures, in which the set of participants is divided in two parts, and all participants in each part play an equivalent role. We focus on the search of lower bounds by using a special class of polymatroids that is introduced here, the tripartite ones. We present a method based on linear programming to compute, for every given bipartite access structure, the best lower bound that can be obtained by this combinatorial method. In addition, we obtain some general lower bounds that improve the previously known ones, and we construct optimal secret sharing schemes for a family of bipartite access structures.Peer ReviewedPostprint (author's final draft

Negative Selection on BRCA1 Susceptibility Alleles Sheds Light on the Population Genetics of Late-Onset Diseases and Aging Theory

The magnitude of negative selection on alleles involved in age-specific mortality decreases with age. This is the foundation of the evolutionary theory of senescence. Because of this decrease in negative selection with age, and because of the absence of reproduction after menopause, alleles involved in women's late-onset diseases are generally considered evolutionarily neutral. Recently, genetic and epidemiological data on alleles involved in late onset-diseases have become available. It is therefore timely to estimate selection on these alleles. Here, we estimate selection on BRCA1 alleles leading to susceptibility to late-onset breast and ovarian cancer. For this, we integrate estimates of the risk of developing a cancer for BRCA1-carriers into population genetics frameworks, and calculate selection coefficients on BRCA1 alleles for different demographic scenarios varying across the extent of human demography. We then explore the magnitude of negative selection on alleles leading to a diverse range of risk patterns, to capture a variety of late-onset diseases. We show that BRCA1 alleles may have been under significant negative selection during human history. Although the mean age of onset of the disease is long after menopause, variance in age of onset means that there are always enough cases occurring before the end of reproductive life to compromise the selective value of women carrying a susceptibility allele in BRCA1. This seems to be the case for an extended range of risk of onset functions varying both in mean and variance. This finding may explain the distribution of BRCA1 alleles' frequency, and also why alleles for many late-onset diseases, like certain familial forms of cancer, coronary artery diseases and Alzheimer dementia, are typically recent and rare. Finally, we discuss why the two most popular evolutionary theories of aging, mutation accumulation and antagonistic pleiotropy, may underestimate the effect of selection on survival at old ages

Connecting climate information with health outcomes

In this chapter we consider a range of factors that need to be taken into account when seeking to use climate information to improve health decision-making. Identifying causal mechanisms that link climate drivers with specific health issues is an important starting point for policy-makers. Matching decision time-horizons to climate information in a way that takes account of scale issues, uncertainties in the underlying data and modelling approaches as well as institutional barriers to knowledge and data sharing is also critical. And of course, all of this is dependent on a solid understanding of the climate information (including its limitations) that is available to health decision-makers. A researcher may be satisfied with a simple times-series of climate data from an authoritative source; a decision-maker needs to know that the climate information is robust, available for routine use and scalable (i.e., can be used over the entire region of interest)

Persistence in epidemic metapopulations: quantifying the rescue effects for measles, mumps, rubella and whooping cough

Metapopulation rescue effects are thought to be key to the persistence of many acute immunizing infections. Yet the enhancement of persistence through spatial coupling has not been previously quantified. Here we estimate the metapopulation rescue effects for four childhood infections using global WHO reported incidence data by comparing persistence on island countries vs all other countries, while controlling for key variables such as vaccine cover, birth rates and economic development. The relative risk of extinction on islands is significantly higher, and approximately double the risk of extinction in mainland countries. Furthermore, as may be expected, infections with longer infectious periods tend to have the strongest metapopulation rescue effects. Our results quantitate the notion that demography and local community size controls disease persistence

Preservation Methods Differ in Fecal Microbiome Stability, Affecting Suitability for Field Studies.

Immediate freezing at -20°C or below has been considered the gold standard for microbiome preservation, yet this approach is not feasible for many field studies, ranging from anthropology to wildlife conservation. Here we tested five methods for preserving human and dog fecal specimens for periods of up to 8 weeks, including such types of variation as freeze-thaw cycles and the high temperature fluctuations often encountered under field conditions. We found that three of the methods-95% ethanol, FTA cards, and the OMNIgene Gut kit-can preserve samples sufficiently well at ambient temperatures such that differences at 8 weeks are comparable to differences among technical replicates. However, even the worst methods, including those with no fixative, were able to reveal microbiome differences between species at 8 weeks and between individuals after a week, allowing meta-analyses of samples collected using various methods when the effect of interest is expected to be larger than interindividual variation (although use of a single method within a study is strongly recommended to reduce batch effects). Encouragingly for FTA cards, the differences caused by this method are systematic and can be detrended. As in other studies, we strongly caution against the use of 70% ethanol. The results, spanning 15 individuals and over 1,200 samples, provide our most comprehensive view to date of storage effects on stool and provide a paradigm for the future studies of other sample types that will be required to provide a global view of microbial diversity and its interaction among humans, animals, and the environment. IMPORTANCE Our study, spanning 15 individuals and over 1,200 samples, provides our most comprehensive view to date of storage and stabilization effects on stool. We tested five methods for preserving human and dog fecal specimens for periods of up to 8 weeks, including the types of variation often encountered under field conditions, such as freeze-thaw cycles and high temperature fluctuations. We show that several cost-effective methods provide excellent microbiome stability out to 8 weeks, opening up a range of field studies with humans and wildlife that would otherwise be cost-prohibitive