La investigación del ADN antiguo: Directrices sobre las precauciones, controles y el tratamiento de las muestras

The young discipline of palaeogenetics has developed into a successful and expectant field of archaeobiological research within the last decade. Palaeogenetic investigation (e.g. PCR, DNA sequencing) of ancient specimens is, however, susceptible to falsification by the presence of contamination from more recent times. Contamination which can lead to amplification of non-authentic sequences is known to stem from several sources: (i) human biomolecules derived from the persons performing the genetic experiments, perhaps also from the archeologists and other persons who have previously handled the specimens or (ii) edaphic DNA sequences derived primarily from bacterial or fungal growth upon the specimen. A third source of contamination can arise from (iii) substances used for conservation of specimens. Here we give advice on the correct processing of prehistoric bone samples when further molecular biological examination is required. Along with the demonstration of necessary precautions and working conditions, we further explain how an unequivocal DNA contamination monitoring is performed.La paleogenética se ha convertido en los últimos años en una disciplina coronada de éxito que ofrece grandes expectativas para el desarrollo de la investigación arqueobiológica. No obstante, la investigación paleogenética (p. ej: PCR, secuenciación del ADN) de especímenes antiguos es susceptible de ser falsificada por la presencia de una contaminación más reciente. Actualmente sabemos que la contaminación que provoca la amplificación de secuencias ''no auténticas" procede de las siguientes fuentes: (i) las biomoléculas humanas provienen de la persona que realiza el experimento genético o incluso también del arqueólogo u otras personas que previamente hayan tenido contacto con el espécimen; (ii) de secuencias de ADN edáficas derivadas básicamente del crecimiento bacterial o fúngico en el seno del espécimen. La tercera fuente de contaminación puede surgir de las substancias (iii) empleadas para la conservación del espécimen. El objetivo de este artículo consiste en aportar una serie de consejos sobre el modo correcto para tratar las muestras de material óseo prehistórico, en el caso que se pretenda realizar ulteriores exámenes biomoleculares. Con esta finalidad presentamos detalladamente las precauciones y condiciones necesarias de trabajo, así como una explicación de cómo puede controlarse la contaminación del ADN. Resulta prometedora la introducción de las herramientas y de la metodología paleogenéticas en el marco de la investigación arqueológica. Tal y como se observa en la mayoría de las publicaciones recientes, existe un gran número de cuestiones que pueden beneficiarse del estudio paleogenético. Cabe citar, entre otras, por ejemplo, los métodos para la reconstrucción de las estructuras sociales en la Prehistoria (a saber, la determinación de las relaciones de parentesco), o ciertas aplicaciones de la investigación paleopatológica. Por otra parte, el repertorio de técnicas disponibles para el análisis del ADN fósil, incluso del que está altamente degradado, permite elucidar, y en algunos casos dar respuesta, a antiguas cuestiones de interés general sobre la evolución de la humanidad. Con la ayuda de métodos más extensos y de un conjunto de técnicas de ADNa optimizadas eficazmente, la paleogenética, en tanto que joven disciplina, se establecerá por sí misma como un instrumento importante de la investigación arqueológica y antropológica. Sin duda alguna, la colaboración científica internacional permitiría una mayor y mejor aceptación de estos métodos en el seno de las disciplinas implicadas, así como fuera de ellas y, en consecuencia, llevaría a una mejor cualidad de la investigación dentro de las ciencias paleo genéticas. Cabe desear que en un futuro próximo se intensifique el intercambio de conocimientos y experiencias entre los grupos de trabajo que estudian las sociedades antiguas

Preliminary Design of a Remotely Piloted Aircraft System for Crop-Spraying on Vineyards

This paper describes the preliminary design of an innovative concept rotary-wing Unmanned Aircraft System (UAS) for precision agriculture and aerial spraying applications. Aerial spraying of plant protection products and pesticides shows open challenges in terms of performance and regulatory requirements. In particular*the focus here is on highlighting the advantages of the proposed solution in performing precise and expeditious interventions, coping with the spray drift problem (i.e. minimization of drift). Flight performances and agronomists' requirements are combined to define the mission and the aerial vehicle and spray system design

Burdigalian deposits of the Santa Cruz Formation in the Sierra Baguales, Austral (Magallanes) Basin: Age, depositional environment and vertebrate fossils

Indexación: Web of Science; Scielo.ABSTRACT. A succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales, northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago Argentino region in Santa Cruz Province, Argentina. These include the Estancia 25 de Mayo Formation and the basal part of the Santa Cruz Formation. The lithological correlation is also confirmed by detrital zircon ages (maximum age of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a postColhuehuapian, pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to 17.8 Ma. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe in southwestern Argentina, supporting the assumption of a regional continuity between these deposits. A measured lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small, meandering rivers and ephemeral floodplain lakes. The sedimentation coincides with intensified uplift of the Patagonian Andes during the ‘Quechua Phase’ of Andean tectonism, which is reflected by a change in paleocurrent directions from northwest to east-northeast. Keywords: Burdigalian, Santa Cruz Formation, Santacrucian SALMA, ‘Notohippidian’ fauna, Meandering rivers.RESUMEN. Una sucesión de estratos marinos y continentales en el flanco meridional del cerro Cono, en la sierra Baguales, al noreste de Torres del Paine, se correlaciona con estratos al sur de la región de lago Argentino en la Provincia de Santa Cruz, República Argentina. Estas unidades incluyen la Formación Estancia 25 de Mayo y la parte basal de la Formación Santa Cruz. La correlación litológica es, además, confirmada por datación de circones detríticos (edad máxima de 18,23±0,26 Ma) y un variado ensamble de vertebrados fósiles terrestres de edad post-Colhuehuapense a pre-Santacrucense en la escala de Edades Mamífero Sudamericanas (EMAS), con un rango temporal de entre 19 a 17,8 Ma. Edades similares han sido reportadas para la parte basal de la Formación Santa Cruz, en estancia Quién Sabe, en el suroeste de Argentina, ratificando la continuidad regional entre estos depósitos. Se presenta una columna estratigráfica y se interpreta el ambiente de depositación como una llanura costera con pequeños ríos sinuosos y lagos efímeros. La edad de sedimentación coincide con el solevantamiento de los Andes Patagónicos durante la 'Fase Quechua', lo que se ve reflejado por un cambio en la dirección de las paleocorrientes desde el noroeste hacia el este-noreste.http://ref.scielo.org/csxwd

Validation of a gas chromatography-mass spectrometry method for the analysis of sterol oxidation products in serum

A validated gas chromatography-mass spectrometry (GC-MS) detection method for the quantitative analysis of sterol oxidation products (SOPs) in serum is described. After a lipid extraction procedure with chloroform-methanol, a cold saponification and purification by solid phase extraction, oxysterols were derivatized to form trimethyl-sylil-ethers which were subjected to GC-MS analysis. Calibration curves for cholesterol oxidation products showed determination coefficient (R(2)) of 1.0, with low values for the coefficient of variation of the response factors (< 1%). Detection and quantification limits were below 5 ng/mL and 10 ng/mL, respectively. Recovery data were between 77.65% and 110.29% (CV < 10% for all compounds). Good results were obtained for within- and between-day repeatability, with values below 10%. In conclusion, the method performed is suitable for the determination and quantification of SOPs in serum

Hybrid loss exceedance curve (HLEC) for disaster risk assessment

Taken into account that the natural hazard risk is a contingent liability and, therefore, a sovereign risk for national governments, it is important to assess properly the potential losses to design a suitable risk reduction, retention and transfer strategy. In this article, a disaster risk assessment methodology is proposed based on two approaches: on the one hand, the empiric estimation of losses, using information available from local disaster databases, allowing estimating losses due to small-scale events and, on the other hand, probabilistic evaluations to estimate losses for greater or even catastrophic events, for which information usually is not available due to the lack of historical data. A &lsquo;&lsquo;hybrid&rsquo;&rsquo; loss exceedance curve is thus determined, which combines the results of these two approaches and represents the disaster risk in a proper and complete way. This curve merges two components: the corresponding to small and moderate losses, calculated using an inductive and retrospective analysis, and the corresponding to extreme losses, calculated using a deductive and prospective analysis. Applications of this risk assessment technique are given in this article for eleven countries

Relationship Between Bioimpedance-Determined Body Composition and Peritoneal Transport in Peritoneal Dialysis

PURPOSE: In peritoneal dialysis (PD) patients, body fluid homeostasis is dependent on peritoneal elimination of water and solutes. Patients with less favorable peritoneal transport parameters should be more overhydrated. Despite this, the association between faster transport and overhydration (OH) is weak, and the factors that influence hydration status are still poorly characterized. Modified peritoneal equilibration tests (PET) offer us new parameters that might correlate better with hydration status, like free water transport (FWT). The aim of this study was thus to establish the relationships between new peritoneal transport parameters and body composition parameters estimated by bioimpedance spectroscopy (BIS). METHODS: Prospective observational study on incident PD patients with a baseline and 1-year follow-up evaluation. RESULTS: 61 patients were included in the baseline evaluation, 19 of whom had a 1-year follow-up evaluation; 67.2% were fluid overloaded. There was a negative correlation between D/P creatinine and FWT (r = -0.598, p = 0.000). The fraction of FWT was negatively correlated with OH (r = -0.302, p = 0.018). Peritoneal protein losses (PPL) were also correlated with OH (r = 0.287, p = 0.028). There were no significant differences in OH according to small-solute transport status or fluid output parameters. After 1 year, we observed a significant worsening of renal function and an improvement in 24-hour ultrafiltration (UF) and hydration status, but we detected no differences in peritoneal transport of water or solutes that could explain these changes. CONCLUSIONS: There is a poor relationship between kidney/peritoneal function parameters and body composition parameters. The fraction of FWT and PPL may be underestimated markers of peritoneal health and of its contribution to the hydration status.info:eu-repo/semantics/publishedVersio

Ultrafast control of Rabi oscillations in a polariton condensate

We report the experimental observation and control of space and time-resolved light-matter Rabi oscillations in a microcavity. Our setup precision and the system coherence are so high that coherent control can be implemented with amplification or switching off of the oscillations and even erasing of the polariton density by optical pulses. The data is reproduced by a fundamental quantum optical model with excellent accuracy, providing new insights on the key components that rule the polariton dynamics.Comment: 5 pages, 3 figures, supplementary 7 pages, 4 figures. Supplementary videos: https://drive.google.com/folderview?id=0B0QCllnLqdyBNjlMLTdjZlNhbTQ&usp=sharin