Laboratory simulation of interplanetary ultraviolet radiation (broad spectrum) and its effects on Deinococcus radiodurans     

Ivan Gláucio Paulino-Lima  Sérgio Pilling  Eduardo Janot-Pacheco  João Alexandre Ribeiro Gonçalves Barbosa  Alvaro Costa Leitão 《Planetary and Space Science》2010,58(10):1180-1040

The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m⁻², corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes.  相似文献   

A new percoid fish from the Eocene of Monte Bolca, Italy: Hendrixella grandei gen. & sp. nov.     

Alexandre F. Bannikov  Giorgio Carnevale 《Swiss Journal of Geoscience》2009,102(3):481-488

A new genus and species of percoid fish, Hendrixella grandei gen. & sp. nov. is described from the upper Ypresian limestone of Monte Bolca, Italy. It is based on four well-preserved specimens that show an elongate and slender body and a unique combination of features, including possession of 11 + 13 vertebrae, two series of intermuscular bones, fused haemal spine of third preural centrum, caudal fin with 17 principal rays and 11 upper and eight lower procurrent rays, predorsal formula 0/0/1 + 1/1/, two separated dorsal fins with rayless pterygiophore in-between, and a single supernumerary spine in both dorsal and anal fins. Due to this unique combination of features, Hendrixella cannot be placed within any existing fossil or extant percoid families and it is placed incertae sedis in the Percoidei. The possession of two series of intermuscular bones represents an unambiguous autapomorphy of Hendrixella. A comparative analysis of the distribution of intermusculars among percomorph fishes indicates that the intermuscular bones of the upper series can be homologized with the epineurals and those of the lower series are the homologs of the epicentrals of non-acanthomorphs.  相似文献   

Sub-pixel Mapping of Coarse Satellite Remote Sensing Images with Stochastic Simulations from Training Images     

Alexandre Boucher 《Mathematical Geosciences》2009,41(3):265-290

Super-resolution or sub-pixel mapping is the process of providing fine scale land cover maps from coarse-scale satellite sensor information. Such a procedure calls for a prior model depicting the spatial structures of the land cover types. When available, an analog of the underlying scene (a training image) may be used for such a model. The single normal equation simulation algorithm (SNESIM) allows extracting the relevant pattern information from the training image and uses that information to downscale the coarse fraction data into a simulated fine scale land cover scene. Two non-exclusive approaches are considered to use training images for super-resolution mapping. The first one downscales the coarse fractions into fine-scale pre-posterior probabilities which is then merged with a probability lifted from the training image. The second approach pre-classifies the fine scale patterns of the training image into a few partition classes based on their coarse fractions. All patterns within a partition class are recorded by a search tree; there is one tree per partition class. At each fine scale pixel along the simulation path, the coarse fraction data is retrieved first and used to select the appropriate search tree. That search tree contains the patterns relevant to that coarse fraction data. To ensure exact reproduction of the coarse fractions, a servo-system keeps track of the number of simulated classes inside each coarse fraction. Being an under-determined stochastic inverse problem, one can generate several super resolution maps and explore the space of uncertainty for the fine scale land cover. The proposed SNESIM sub-pixel resolution mapping algorithms allow to: (i) exactly reproduce the coarse fraction, (ii) inject the structural model carried by the training image, and (iii) condition to any available fine scale ground observations. Two case studies are provided to illustrate the proposed methodology using Landsat TM data from southeast China.  相似文献   

Chemical ionisation mass spectrometer for measurements of OH and Peroxy radical concentrations in moderately polluted atmospheres     

Alexandre Kukui  Gérard Ancellet  Georges Le Bras 《Journal of Atmospheric Chemistry》2008,61(2):133-154

A new version of an atmospheric pressure chemical ionisation mass spectrometer has been developed for ground based in situ atmospheric measurements of OH and total peroxy (HO₂ + organic peroxy) radicals. Based on the previously developed principle of chemical conversion of OH radicals to H₂SO₄ in reaction with SO₂ and detection of H₂SO₄ using an ion molecule reaction with NO₃^─, the new instrument is equipped with a turbulent chemical conversion reactor allowing for measurements in moderately polluted atmosphere at NO concentrations up to several ppb. Unlike other similar devices, where the primary NO₃^─ ions are produced using radioactive ion sources, the new instrument is equipped with a specially developed corona discharge ion source. According to laboratory measurements, the overall accuracy and detection limits are estimated to be, respectively, 25% and 2 × 10⁵ molecule cm^-3 for OH and 30% and 1 × 10⁵ molecule cm^-3 for HO₂ at 10 min integration times. The detection limit for measurements of OH radicals under polluted conditions is 5 × 10⁵ molecules cm^-3 at 10 min integration times. Examples of ambient air measurements during a field campaign near Paris in July 2007 are presented demonstrating the capability of the new instrument, although with reduced performance due to the employment of non isotopic SO₂.  相似文献   

Understanding Causes of Conflict Over Common Village Pastures – A Comparative Analysis of Property Rights in Azerbaijan and Georgia     

Regina Neudert  Insa Theesfeld  Alexandre Didebulidze  Naiba Allahverdiyeva  Volker Beckmann 《社会与自然资源》2020,33(3):347-367

Abstract

Conflicts in the management of renewable natural resources are situations in which actors have diverging opinions on issues of natural resource use. In the literature, among the causal factors for conflicts discussed are resource wealth or scarcity and the role of governance. The evidence, however, is contradictory. In order to analyze the role of governance in more detail, we propose a combined analysis of property rights and conflicts. In this way, an improved understanding of the causes of local conflicts over renewable natural resources can be achieved. We use comparative case study data from pasture management in the Caucasus region, first, to classify conflicts according to the bundle of property rights approach and, second, to explore how the causal factors resource scarcity and current governance contribute to those conflicts.  相似文献   

Gauging extreme floods on YouTube: application of LSPIV to home movies for the post‐event determination of stream discharges          下载免费PDF全文

Raphaël Le Boursicaud  Lionel Pénard  Alexandre Hauet  Fabien Thollet  Jérôme Le Coz 《水文研究》2016,30(1):90-105

Movies taken by witnesses of extreme flood events are increasingly available on video sharing websites. They potentially provide highly valuable information on flow velocities and hydraulic processes that can help improve the post‐flood determination of discharges in streams and flooded areas. We investigated the troubles and potential of applying the now mature large‐scale particle image velocimetry (LSPIV) technique to such flood movies that are recorded under non‐ideal conditions. Processing was performed using user‐friendly, free software only, such as Fudaa‐LSPIV. Typical issues related to the image processing and to the hydrological analysis are illustrated using a selected example of a pulsed flash‐flood flow filmed in a mountainous torrent. Simple corrections for lens distortion (fisheye) and limited incoherent camera movement (shake) were successfully applied, and the related errors were reduced to a few percents. Testing the different image resolution levels offered by YouTube showed that the difference in time‐averaged longitudinal velocity was less than 5% compared with full resolution. A limited number of GRPs, typically 10, is required, but they must be adequately distributed around the area of interest. The indirect determination of the water level is the main source of uncertainty in the results, usually much more than errors because of the longitudinal slope and waviness of the free‐surface of the flow. The image‐based method yielded direct discharge estimates of the base flow between pulses, of the pulse waves, and of the time‐averaged flow over a movie sequence including a series of five pulses. A comparison with traditional indirect determination methods showed that the critical‐depth method may produce significantly biassed results for such a fast, unsteady flow, while the slope‐area method seems to be more robust but would overestimate the time‐averaged flow rate if applied to the high‐water marks of a pulsed flow. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Estimating the uncertainty of video-based flow velocity and discharge measurements due to the conversion of field to image coordinates     

Jérôme Le Coz  Benjamin Renard  Vincent Vansuyt  Magali Jodeau  Alexandre Hauet 《水文研究》2021,35(5):e14169

Video-based hydrometry continues to develop for contactless discharge measurements, automated flood gauging stations and the use of crowd-sourced flood videos for discharge reconstruction. Irrespective of the velocimetry algorithm used (LSPIV, STIV, PTV…), orthorectification of the images is necessary beforehand, so that each pixel has the same known physical size. Most times, the orthorectification transformation is a plane-to-plane projection from the water surface to the camera sensor. Two approaches are typically used to compute the coefficients of this transformation: their calibration from ground reference points (GRPs) with known image and real-world coordinates (“implicit calibration”) or their calculation from the values of the intrinsic (focal length, sensor size) and extrinsic (position, angles) parameters of the camera (“explicit calibration”). In this paper, we develop a Bayesian method which makes it possible to combine the implicit and explicit approaches in a probabilistic framework. The Bayesian approach can be used from situations suitable for the implicit approach (plenty of GRPs) to situations propitious to the explicit approach (well-known camera parameters). The method is illustrated using synthetic views of a typical streamgauging scene with known true values of the parameters and GRP coordinates. We show that combining observational and prior information is generally beneficial to get precise estimates. Further tests carried out with a real scene of the Arc River at Randens, France, in flood conditions illustrate the impact of the number, uncertainty and spatial distribution of GRPs on the final uncertainty of flow velocity and discharge.  相似文献   

Hybrid models of reactive transport in porous and fractured media     

Ilenia BattiatoDaniel M. Tartakovsky  Alexandre M. TartakovskyT.D. Scheibe 《Advances in water resources》2011,34(9):1140-1150

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3D resistivity gridding of large AEM datasets: A step toward enhanced geological interpretation     

Alexandre Pryet  James Ramm  Jean-Paul Chilès  Esben Auken  Benoit Deffontaines  Sophie Violette 《Journal of Applied Geophysics》2011,75(2):277-283

We develop a technique allowing 3D gridding of large sets of 1D resistivity models obtained after inversion of extensive airborne EM surveys. The method is based on the assumption of a layered-earth model. 2D kriging is used for interpolation of geophysical model parameters and their corresponding uncertainties. The 3D grid is created from the interpolated data, its structure accurately follows the geophysical model, providing a lightweight file for a good rendering. Propagation of errors is tracked through the quantification of uncertainties from both inversion and interpolation procedures. The 3D grid is exported to a portable standard, which allows flexible visualization and volumetric computations, and improves interpretation. The method is validated and illustrated by a case-study on Santa Cruz Island, in the Galapagos Archipelago.  相似文献   

The 1979 nice airport tsunami: mapping of the flood in Antibes     

Alexandre Sahal  Anne Lemahieu 《Natural Hazards》2011,56(3):833-840

On 16 October 1979, a tsunami of a local origin hits the French Riviera around Nice, France, killing 8 people and generating important economic losses. Its impact was felt from Hyères to Menton, France. The main effect of this tsunami was flooding in the neighborhoods of La Salis and La Garoupe, Antibes, France. A synthesis of unpublished reports written in the context of an administrative investigation was conducted. Various archives were also consulted (newspapers, fire and rescue unit reports, insurance reports, etc.), and a field survey was organized in 2009 to record testimonies from the inhabitants who witnessed the flood in La Salis, Antibes, the area where the effects of the tsunami were the greatest. A geo-database of the neighborhood of La Salis was built using available aerial imagery, land cover data and digital terrain models, to reconstruct the surface of the flooded area as it was in 1979 and as it is now. Comparing precise testimonies and the 1979 topographic information available allowed the authors to precisely map the flood and to deduce the runup values which reached 3.5 m locally, with a maximal distance of flooding of 150 m inland. This paper provides modelers with precious information about the extent of flooding and the time sequence in order to reconstitute the propagation and flooding of the 16 October 1979 tsunami. This information highlights the fact that the French Riviera is a low hazard, but high vulnerability area.  相似文献