Evaluación de la diagénesis ósea mediante el uso de microscopía electrónica de barrido (MEB): aproximaciones analíticas aplicables a muestras arqueológicas

El objetivo del presente trabajo es realizar una revisión de las aproximaciones analíticas aplicables al estudio de la diagénesis ósea -dentro del campo más amplio de la tafonomía- que se basan en el uso de la microscopía electrónica de barrido (MEB). Para ello, se presenta a) una síntesis de los conocimientos actuales acerca de los procesos diagenéticos que afectan a la integridad histológica de los restos óseos, tanto humanos como faunísticos, en depósitos sedimentarios terrestres; b) una exposición abreviada de los principios generales de la microscopía electrónica, particularmente de la MEB y c) un comparación de las diferencias -en cuanto a requerimientos, información obtenible y ventajas/desventajas asociadas- entre los análisis centrados en los dos principales tipos de imágenes producidas por un MEB, es decir, las de electrones retrodispersados y las de electrones secundarios. Se concluye que, dada la disponibilidad relativamente amplia de esta tecnología, el factor crítico para una incorporación más activa del MEB en la investigación arqueológica y bioantropológica no es el acceso al equipamiento, sino la apropiada identificación de los problemas de investigación a resolver, así como la adecuada selección y ejecución de las técnicas de observación y análisis a emplear.The aim of this paper is to review analytic approaches to bone diagenesis based on the use of scanning electron microscopy (SEM). In order to do this, we present a) a synthesis of current knowledge about diagenetic processes affecting the histological integrity of human and faunal skeletal remains in terrestrial sedimentary deposits; b) a brief description of the general principles of electron microscopy, particularly of SEM, and c) a comparison of the main differences -in terms of requirements, recoverable information, and associated pros and cons- between analyses centered on the use of either of the two main kinds of images produced by a SEM, i.e., backscattered electron images and secondary electron images. It is concluded that, given the relatively wide availability of this technology, the critical factor to a more active involvement of SEM in archaeological and bioanthropological research is not the access to equipment, but the correct identification of the research problems to be solved, as well as the proper selection and implementation of the observational and analytical techniques to be employed.Dossier: Los estudios de histología ósea en Antropología BiológicaAsociación de Antropología Biológica de la República Argentina (AABRA

A simple and convenient transformation of L-lysine into pyridinoline and deoxypyridinoline, two collagen cross-links of biochemical interest

Starting from L-lysine as the only chiral building block, pyridinoline and deoxypyridinoline are efficiently synthesised, thus mimicking the postranscriptional formation of these collagen cross-links

Evaluación de la diagénesis ósea mediante el uso de microscopía electrónica de barrido (MEB): aproximaciones analíticas aplicables a muestras arqueológicas

El objetivo del presente trabajo es realizar una revisión de las aproximaciones analíticas aplicables al estudio de la diagénesis ósea -dentro del campo más amplio de la tafonomía- que se basan en el uso de la microscopía electrónica de barrido (MEB). Para ello, se presenta a) una síntesis de los conocimientos actuales acerca de los procesos diagenéticos que afectan a la integridad histológica de los restos óseos, tanto humanos como faunísticos, en depósitos sedimentarios terrestres; b) una exposición abreviada de los principios generales de la microscopía electrónica, particularmente de la MEB y c) un comparación de las diferencias -en cuanto a requerimientos, información obtenible y ventajas/desventajas asociadas- entre los análisis centrados en los dos principales tipos de imágenes producidas por un MEB, es decir, las de electrones retrodispersados y las de electrones secundarios. Se concluye que, dada la disponibilidad relativamente amplia de esta tecnología, el factor crítico para una incorporación más activa del MEB en la investigación arqueológica y bioantropológica no es el acceso al equipamiento, sino la apropiada identificación de los problemas de investigación a resolver, así como la adecuada selección y ejecución de las técnicas de observación y análisis a emplear.The aim of this paper is to review analytic approaches to bone diagenesis based on the use of scanning electron microscopy (SEM). In order to do this, we present a) a synthesis of current knowledge about diagenetic processes affecting the histological integrity of human and faunal skeletal remains in terrestrial sedimentary deposits; b) a brief description of the general principles of electron microscopy, particularly of SEM, and c) a comparison of the main differences -in terms of requirements, recoverable information, and associated pros and cons- between analyses centered on the use of either of the two main kinds of images produced by a SEM, i.e., backscattered electron images and secondary electron images. It is concluded that, given the relatively wide availability of this technology, the critical factor to a more active involvement of SEM in archaeological and bioanthropological research is not the access to equipment, but the correct identification of the research problems to be solved, as well as the proper selection and implementation of the observational and analytical techniques to be employed.Asociación de Antropología Biológica de la República Argentina (AABRA

Further characterisation of differences between TL and AB zebrafish (Danio rerio): gene expression, physiology and behaviour at day 5 of the larval stage

Contains fulltext : 175469.pdf (publisher's version ) (Open Access)15 p

The impact of the melting layer on the passive microwave cloud scattering signal observed from satellites: A study using TRMM microwave passive and active measurements

International audienc

Analysis and evaluation of WRF microphysical schemes for deep moist convection over south-eastern South America (SESA) using microwave satellite observations and radiative transfer simulations

International audienc

Meso-scale modelling and radiative transfer simulations of a snowfall event over France at microwaves for passive and active modes and evaluation with satellite observations

Microwave passive and active radiative transfer simulations are performed with the Atmospheric Radiative Transfer Simulator (ARTS) for a mid-latitude snowfall event, using outputs from the Meso-NH mesoscale cloud model. The results are compared to the corresponding microwave observations available from MHS and CloudSat. The spatial structures of the simulated and observed brightness temperatures show an overall agreement since the large-scale dynamical structure of the cloud system is reasonably well captured by Meso-NH. However, with the initial assumptions on the single-scattering properties of snow, there is an obvious underestimation of the strong scattering observed in regions with large frozen hydrometeor quantities. A sensitivity analysis of both active and passive simulations to the microphysical parametrizations is conducted. Simultaneous analysis of passive and active calculations provides strong constraints on the assumptions made to simulate the observations. Good agreements are obtained with both MHS and CloudSat observations when the single-scattering properties are calculated using the "soft sphere" parametrization from Liu (2004), along with the Meso-NH outputs. This is an important step toward building a robust data set of simulated measurements to train a statistically based retrieval scheme

Meso-scale modelling and radiative transfer simulations of a snowfall event over France at microwaves for passive and active modes and evaluation with satellite observations

Microwave passive and active radiative transfer simulations are performed with the Atmospheric Radiative Transfer Simulator (ARTS) for a mid-latitude snowfall event, using outputs from the Meso-NH mesoscale cloud model. The results are compared to the corresponding microwave observations available from MHS and CloudSat. The spatial structures of the simulated and observed brightness temperatures show an overall agreement since the large-scale dynamical structure of the cloud system is reasonably well captured by Meso-NH. However, with the initial assumptions on the single-scattering properties of snow, there is an obvious underestimation of the strong scattering observed in regions with large frozen hydrometeor quantities. A sensitivity analysis of both active and passive simulations to the microphysical parametrizations is conducted. Simultaneous analysis of passive and active calculations provides strong constraints on the assumptions made to simulate the observations. Good agreements are obtained with both MHS and CloudSat observations when the single-scattering properties are calculated using the "soft sphere" parametrization from Liu (2004), along with the Meso-NH outputs. This is an important step toward building a robust data set of simulated measurements to train a statistically based retrieval scheme