Lower variability of radionuclide activities in upland dairy products compared to soils and vegetation: Implication for environmental survey

Contamination of the environment by radionuclides is usually estimated using soil and grass sampling. However, radionuclides are often not homogeneously distributed in soils. In the alpine Mercantour region (Western Alps, France) a large heterogeneity in Chernobyl 137Cs deposition has been previously observed. Here we report additional 137Cs results together with new 90Sr and Pu data for soil, grass, milk, and cheese samples. The results show that radioisotopes from nuclear weapons tests fallout are more homogeneously distributed than Chernobyl 137Cs. Further, we observe that the 137Cs and 90Sr contents are less variable in milk samples than in grass or soil samples. This can be attributed to the homogenization effect of cow vagrancy during grazing. Hence milk seems to be a more robust sample than soil or grass to evaluate the extent of contamination on a regional scale. We explore this idea by comparing own unpublished 90Sr results and 90Sr results from the literature to establish the relationship between altitude of grazing and contamination of soil and milk for Western Europe. There is a significant positive correlation between soil contamination and altitude and an even closer correlation between milk 90Sr activity (A) and altitude (h): A = A0 + ek·h where A0 is the expected activity of milk sampled at sea level (A0 = 0.064 ± 0.014 Bq g-1 Ca) and h is the altitude of grazing, k being a constant (k = 0.95 × 10-3 ± 0.11 × 10-3 m-1 Bq g-1 Ca). The fact that there is less scattering in the relationship for the 90Srmilk-altitude than for 90Srsoil-altitude suggests, again, that milk is a well-suited sample for environmental survey. The relationship between the altitude of grazing and the 90Sr content of milk and cheese can also be used to assess the authenticity of dairy products. © 2006 Elsevier Ltd. All rights reserved

Diffusion imaging with a multi-echo MISSTEC sequence

An imaging method is presented to measure the water-diffusion coefficient. The sequence (MISSTEC) uses the simultaneous acquisition of a spin echo and several stimulated echoes with the same intensity except for diffusion weighting. The optimal number of stimulated echoes was calculated to minimize the diffusion coefficient error (D). D values obtained in vitro and in vivo were in good agreement with those from the spin-echo sequence (IntraVoxel Incoherent Motion [IVIM] method). The total acquisition time is half that of the classic IVIM method

True stress and Poisson's ratio of tendons during loading.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tExcessive axial tension is very likely involved in the aetiology of tendon lesions, and the most appropriate indicator of tendon stress state is the true stress, the ratio of instantaneous load to instantaneous cross-sectional area (CSA). Difficulties to measure tendon CSA during tension often led to approximate true stress by assuming that CSA is constant during loading (i.e. by the engineering stress) or that tendon is incompressible, implying a Poisson's ratio of 0.5, although these hypotheses have never been tested. The objective of this study was to measure tendon CSA variation during quasi-static tensile loading, in order to assess the true stress to which the tendon is subjected and its Poisson's ratio. Eight equine superficial digital flexor tendons (SDFT, about 30cm long) were tested in tension until failure while the CSA of each tendon was measured in its metacarpal part by means of a linear laser scanner. Axial elongation and load were synchronously recorded during the test. CSA was found to linearly decrease with strain, with a mean decrease at failure of -10.7±2.8% (mean±standard deviation). True stress at failure was 7.1-13.6% higher than engineering stress, while stress estimation under the hypothesis of incompressibility differed from true stress of -6.6 to 2.3%. Average Poisson's ratio was 0.55±0.12 and did not significantly vary with load. From these results on equine SDFT it was demonstrated that tendon in axial quasi-static tension can be considered, at first approximation, as an incompressible material.Direction Générale de l’Enseignement et de la Recherche (French Ministry of Agriculture)Région Basse-NormandieInstitut National de la Recherche Agronomiqu

Fourier Modeling of the Left Ventricle Parasternal Boundary

Any parasternal boundary of the left ventricle of the heart, manually extracted from an echocardiographic image, can be modeled using smoothing by truncating the Fourier serie of its polar development round an inner origin . The choice of a central origin, that annulates the Fourier coefficient at the first harmonic, minimizes the quadratic distance between the manual boundary and the modeled one. The parameters of the model are the coordinates of this central origin, and the non-truncated Fourier coefficients. The geometrical interpretation of each of these parameters, very simple, gives them a useful significance for the medical diagnosis. In an other hand, the analysis of the smoothed boundaries evolution for a complete cardiac cycle yields to measuring the isotropy of the contractions. Finally, it is possible to extract the parameters ofa non-closed boundary by implicit interpolation on the lacking portions.ZRToéuts cuonmtéour parasternal du ventricule gauche du coeur, extrait manuellement sur une image échocardiographique, est modélisable par lissage en tronquant la série de Fourier de son développement polaire autour d'une origine interne . Le choix d'une origine centrale, qui correspond à l'annulation du coefficient de Fourier au premier harmonique, minimise l'écart quadratique entre le contour manuel et le contour modélisé . Les paramètres du modèle sont les coordonnées de cette origine centrale ainsi que les coefficients de Fourier non tronqués . L'interprétation géométrique de ces paramètres, très simple, leur confère une signification utile pour le diagnostic médical. D'autre part, l'analyse de l'évolution des contours lissés pendant le cycle cardiaque conduit à une mesure de l'isotropie des contractions . Enfin, il est possible d'extraire les paramètres d'un contour non fermé par interpolation implicite sur les portions manquantes

Porosity microstructures of a sandstone affected by a normal fault

Dans un système de failles normales de la bordure du fossé rhénan, les interactions eaux-roches de part et d’autre de ces failles peuvent contrôler les conditions des circulations fluides. L’objectif de ce travail est de caractériser les structures du réseau poreux dans la zone endommagée autour d’une de ces failles. Il est intéressant d’étudier la relation entre porosité et perméabilité dans cette zone. Des études pétrographiques et pétrophysiques, des mesures microthermométriques sur des inclusions fluides et la composition isotopique de l’oxygène ont permis de caractériser les structures de porosité des roches et notamment des ciments primaires et secondaires. Le couplage de ces approches montre qu’une faille normale peut à la fois jouer le rôle de drain et de barrière à la circulation des fluides. En fonction de la direction de circulation, la faille joue le rôle de drain en laissant remonter les fluides parallèlement au plan de faille et le rôle de barrière, en focalisant les circulations dans le toit. L’anisotropie, notamment des propriétés de transfert héritées des conditions de dépôts fluviatiles, est profondément modifiée par les transferts subits dans le matériau. Ainsi les modifications des transferts dépendent des modifications du réseau poreux : l’hétérogénéité de la structure du réseau et l’anisotropie d’orientation ou de connectivité. Ce modèle de circulation est contrôlé par une interaction entre les modifications des structures du réseau poreux et les circulations fluides, entraînant des modifications de l’anisotropie de certaines propriétés du matériau autour de la faille

Hydrological Behaviour of Tritium on the Former Semipalatinsk Nuclear Test Site (Kazakhstan) Determined using Stable Isotope Measurements

Tritium and stable isotope (deuterium 2H and 18O) concentrations have been determined in natural waters collected from shallow lakes, wells, streams and rivers inside and in the vicinity of the former Semipalatinsk Nuclear Test Site (NE Kazakhstan). The Semipalatinsk Test Site (STS) was one of the main proving grounds for the testing of nuclear weapons by the former Soviet Union. Tritium activity concentrations have been determined by liquid scintillation counting, while hydrogen isotopic composition have been determined using a GV-Isoprime mass spectrometer coupled to an elemental analyzer. Tritium activity concentrations recorded in lake waters (in most cases >10 Bq L-1) were significantly higher than those in well, stream and the Irtysh River waters. In lake waters, enrichments in deuterium and 18O (δD and δ18O varying between –5 and –64 ‰ V-SMOW and –8.4 and +5.5 ‰ V-SMOW, respectively), and high salt concentrations, strongly suggest that significant evaporation has occurred. In contrast, deuterium and tritium signatures of ‘common’ surface and underground waters at the STS were mostly typical of present-day isotope backgrounds of natural waters in NE Kazakhstan. In STS, come salt lakes like Bajansor and Tumatsor with elevated tritium activity from 12 to 15 Bq L-1 lie close to the Global Meteoric Water Line. The potential tritium source for these lakes is residual concentration of tritium after former nuclear test in STS. The study provides evidence to show that export of tritium from underground nuclear test areas and tritium enrichment produced by evaporation are both important determinants of tritium concentrations in standing waters on the Semipalatinsk test site

The effect of induced forelimb lameness on thoracolumbar kinematics during treadmill locomotion

Reasons for performing study: Lameness has often been suggested to result in altered movement of the back, but there are no detailed studies describing such a relationship in quantitative terms. Objectives: To quantify the effect of induced subtle forelimb lameness on thoracolumbar kinematics in the horse. Methods: Kinematics of 6 riding horses was measured at walk and at trot on a treadmill before and after the induction of reversible forelimb lameness grade 2 (AAEP scale 1-5). Ground reaction forces (GRF) for individual limbs were calculated from kinematics. Results: The horses significantly unloaded the painful limb by 11.5% at trot, while unloading at walk was not significant. The overall flexion-extension range of back motion decreased on average by 0.2° at walk and increased by 3.3° at trot (P<0.05). Changes in angular motion patterns of vertebral joints were noted only at trot, with an increase in flexion of 0.9° at T10 (i.e. angle between T6, T10 and T13) during the stance phase of the sound diagonal and an increase in extension of the thoracolumbar area during stance of the lame diagonal (0.7° at T13, 0.8° at T17, 0.5° at L1, 0.4° at L3 and 0.3° at L5) (P<0.05). Lameness further caused a lateral bending of the cranial thoracic vertebral column towards the lame side (1.3° at T10 and 0.9° at T13) (P<0.05) during stance of the lame diagonal. Conclusions: Both range of motion and vertebral angular motion patterns are affected by subtle forelimb lameness. At walk, the effect is minimal, at trot the horses increased the vertebral range of motion and changed the pattern of thoracolumbar motion in the sagittal and horizontal planes, presumably in an attempt to move the centre of gravity away from the lame side and reduce the force on the affected limb. Potential relevance: Subtle forelimb lameness affects thoracolumbar kinematics. Future studies should aim at elucidating whether the altered movement patterns lead to back and/or neck dysfunction in the case of chronic lameness

First light of VLT/HiRISE: High-resolution spectroscopy of young giant exoplanets

A major endeavor of this decade is the direct characterization of young giant exoplanets at high spectral resolution to determine the composition of their atmosphere and infer their formation processes and evolution. Such a goal represents a major challenge owing to their small angular separation and luminosity contrast with respect to their parent stars. Instead of designing and implementing completely new facilities, it has been proposed to leverage the capabilities of existing instruments that offer either high-contrast imaging or high-dispersion spectroscopy by coupling them using optical fibers. In this work, we present the implementation and first on-sky results of the High-Resolution Imaging and Spectroscopy of Exoplanets (HiRISE) instrument at the Very Large Telescope (VLT), which combines the exoplanet imager SPHERE with the recently upgraded high-resolution spectrograph CRIRES using single-mode fibers. The goal of HiRISE is to enable the characterization of known companions in the H band at a spectral resolution on the order of R = λ/∆λ = 100 000 in a few hours of observing time. We present the main design choices and the technical implementation of the system, which is constituted of three major parts: the fiber injection module inside of SPHERE, the fiber bundle around the telescope, and the fiber extraction module at the entrance of CRIRES. We also detail the specific calibrations required for HiRISE and the operations of the instrument for science observations. Finally, we detail the performance of the system in terms of astrometry, temporal stability, optical aberrations, and transmission, for which we report a peak value of ~3.9% based on sky measurements in median observing conditions. Finally, we report on the first astrophysical detection of HiRISE to illustrate its potential

First light of VLT/HiRISE: High-resolution spectroscopy of young giant exoplanets

A major endeavor of this decade is the direct characterization of young giant exoplanets at high spectral resolution to determine the composition of their atmosphere and infer their formation processes and evolution. Such a goal represents a major challenge owing to their small angular separation and luminosity contrast with respect to their parent stars. Instead of designing and implementing completely new facilities, it has been proposed to leverage the capabilities of existing instruments that offer either high contrast imaging or high dispersion spectroscopy, by coupling them using optical fibers. In this work we present the implementation and first on-sky results of the HiRISE instrument at the very large telescope (VLT), which combines the exoplanet imager SPHERE with the recently upgraded high resolution spectrograph CRIRES using single-mode fibers. The goal of HiRISE is to enable the characterization of known companions in the $H$ band, at a spectral resolution of the order of $R = \lambda/\Delta\lambda = 100\,000$, in a few hours of observing time. We present the main design choices and the technical implementation of the system, which is constituted of three major parts: the fiber injection module inside of SPHERE, the fiber bundle around the telescope, and the fiber extraction module at the entrance of CRIRES. We also detail the specific calibrations required for HiRISE and the operations of the instrument for science observations. Finally, we detail the performance of the system in terms of astrometry, temporal stability, optical aberrations, and transmission, for which we report a peak value of $\sim$3.9% based on sky measurements in median observing conditions. Finally, we report on the first astrophysical detection of HiRISE to illustrate its potential.Comment: 17 pages, 15 figures, 3 tables. Submitted to A&A on 19 September 202