Characterizing clay mineralogy in Lake Towuti,Indonesia, with reflectance spectroscopy     

Andrea K. Weber  James M. Russell  Timothy A. Goudge  Mark R. Salvatore  John F. Mustard  Satria Bijaksana 《Journal of Paleolimnology》2015,54(2-3):253-261

  相似文献   

Possible gamma-ray burst radio detections by the Square Kilometre Array. New perspectives     

Alan Cosimo Ruggeri  Salvatore Capozziello 《Astrophysics and Space Science》2016,361(9):279

  相似文献   

The thin and medium filters of the EPIC camera on-board XMM-Newton: measured performance after more than 15 years of operation     

Marco Barbera  Fabio Gastaldello  Luisa Sciortino  Simonpietro Agnello  Gianpiero Buscarino  Alfonso Collura  Nicola La Palombara  Ugo Lo Cicero  Nicola Sartore  Andrea Tiengo  Salvatore Varisco  Anna Maria Venezia 《Experimental Astronomy》2016,42(2):179-197

After more than 15 years of operation of the EPIC camera on board the XMM-Newton X-ray observatory, we have reviewed the status of its Thin and Medium filters. We have selected a set of Thin and Medium back-up filters among those still available in the EPIC consortium and have started a program to investigate their status by different laboratory measurements including: UV/VIS transmission, Raman scattering, X-Ray Photoelectron Spectroscopy, and Atomic Force Microscopy. Furthermore, we have investigated the status of the EPIC flight filters by performing an analysis of the optical loading in the PN offset maps to gauge variations in the optical and UV transmission. We both investigated repeated observations of single optically bright targets and performed a statistical analysis of the extent of loading versus visual magnitude at different epochs. We report the results of the measurements conducted up to now. Most notably, we find no evidence for change in the UV/VIS transmission of the back-up filters in ground tests spanning a 2 year period and we find no evidence for change in the optical transmission of the thin filter of the EPIC-pn camera from 2002 to 2012. We point out some lessons learned for the development and calibration programs of filters for X-ray detectors in future Astronomy missions.  相似文献   

Biogeochemical effects of disturbance in shallow water sediment by macroalgae harvesting boats     

Lenzi M  Finoia MG  Persia E  Comandi S  Gargiulo V  Solari D  Gennaro P  Porrello S 《Marine pollution bulletin》2005,50(5):512-519

In the shallow water of Orbetello lagoon, macroalgae harvesting boats produce sediment disturbance. To evaluate the effect of this, during 2001-2002, a trial study was carried out in the lagoon in order to: verify seasonal and diurnal trends in nutrients and estimate the quantity of resuspended organic sediment. An unbalanced and balanced ANOVA (one and two way) analysis was applied. The disturbance did not produce strong and lasting eutrophication effects. In the seasonal survey, dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) showed significant decreases in disturbed areas at the end of the trial, while the control area showed a constant, significant increase. Dissolved organic nitrogen (DON) and phosphorus (DOP) significantly increased everywhere. In disturbed areas, sediment redox (Eh((NHE))) increased and porosity values decreased, contrary to the control area. Total organic carbon (TOC) remained unchanged in disturbed areas, but increased in the control area, where the C:P ration increased. The fall-out of sedimentary material resuspended by boat action for as far as 50 m from the boat route, was 189 g(dw)m(-2) made up mainly of organic matter. This disturbance could be the cause of change in vegetation in the lagoon.  相似文献   

Stress–strain history from the geological evolution of the Orvieto and Radicofani cliff slopes (Italy)     

Francesca Bozzano  Alberto Bretschneider  Salvatore Martino 《Landslides》2008,5(4):351-366

The study proposes geological evolution models for the cliff slopes of the two Italian towns of Orvieto (Umbria) and Radicofani (Tuscany). The models were validated by the use of a stress–strain numerical modelling, implemented by the finite-difference code FLAC 5.0. The numerical modelling was approached in a sequential way, by assuming specific stiffness values related to the evolutionary stages. For this purpose, unconventional laboratory tests were performed aiming at reproducing the stress path related to the geological evolution model, using standard equipment for CID triaxial testing. The geological evolution models infer that deformation in both cases is driven by stress reduction. At the Orvieto plateau, stress reduction is induced by stress relief involving a tuff plate; in the case of Radicofani, stress reduction is due to stress release in consequence of lateral erosion of clay. Numerical simulations refine the lithotechnical zoning of the two investigated slopes, introducing a stress–strain criterion in addition to the conventional geological and geomechanical ones.  相似文献   

A new late glacial to early Holocene palaeobotanical and archaeological record in the Eastern Pre‐Alps: the Palughetto basin (Cansiglio Plateau,Italy)     

Roberto Avigliano  Giulio Di Anastasio  Salvatore Improta  Marco Peresani  Cesare Ravazzi 《第四纪科学杂志》2000,15(8):789-803

A late glacial to early Holocene lacustrine and peat succession, rich in conifer remains and including some palaeolithic flint artefacts, has been investigated in the Palughetto intermorainic basin (Venetian Pre‐Alps). The geomorphological and stratigraphical relationships, ¹⁴C dates and pollen analyses allow a reconstruction of the environmental history of the basin and provide significant insights into the reforestation and peopling of the Pre‐Alps. The onset of peat accumulation is dated to 14.4–14.1 kyr cal. BP, coinciding with reforestation at middle altitudes that immediately post‐dates the immigration of Larix decidua and Picea abies subsp. europaea. Plant macrofossils point to the expansion of spruce about 14.3 kyr cal. BP, so far one of the earliest directly dated in the late glacial period of southern Europe. The previous hypothesis of an early Holocene spruce immigration in the Southern Alps from Slovenia needs reconsideration. Organic sedimentation stopped at the end of the Younger Dryas and was followed by the evolution of hydromorphic soils containing lithic artefacts, anthropic structures and wood charcoal. The typological features of the flint implements refer human occupation of the site to the end of the recent Epigravettian. Charcoals yielded dates either consistent with, or younger than, the archaeological chronology, in the early and middle Holocene. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Sediment delivery processes and the spatial distribution of caesium-137 in a small Sicilian basin     

Vito Ferro  Costanza Di Stefano  Giuseppe Giordano  Salvatore Rizzo 《水文研究》1998,12(5):701-711

The sediment delivery processes occurring in a small Sicilian basin are modelled using the spatially distributed SEDD model recently proposed by Ferro and Minacapilli. The model is applied by using soil data (grain-size distribution, organic matter content, etc.) of 129 samples uniformly distributed over the study area and compiling the available information (topographic map, soil data, etc.) into a Geographical Information System. Finally, the predictive capability of the distributed sediment delivery approach is tested experimentally using the caesium-137 measurement technique. The comparison between calculated sediment yield and the corresponding measured caesium-137 loss is used to validate the SEDD model at the scale of both the single morphological unit and the entire basin. © 1998 John Wiley & Sons, Ltd.  相似文献   

Effects of mariculture on macrobenthic assemblages in a western mediterranean site   总被引：2，自引：0，他引：2  

Paolo Tomassetti  Emma Persia  Isabel Mercatali  Danilo Vani  Veronica Marussso  Salvatore Porrello 《Marine pollution bulletin》2009,58(4):533-541

The effects of solid organic wastes from a marine fish farm on sediment was tested using macrobenthic fauna as biological indicators. Impact on benthic fauna was evaluated in the vicinity of a fish farm in the Tyrrhenian Sea (Western Mediterranean) between July 2001 and October 2002. Changes in benthic community structure were investigated using multivariate, distributional and univariate analyses (diversity indices, AMBI and M-AMBI). The results showed sharp disturbance of assemblages under the cages and no effects in the area more than 25 m from the cages. Sediment alterations were related to an increase in farmed biomass and its wastes, as well as to low current speed that allowed accumulation of organic matter on the sea floor. It was possible to follow the ecological succession from slightly altered assemblages to heavily polluted ones in the very short period of a single fish fattening cycle (15 months).  相似文献   

Calcified microbial mats date prehistoric canals—Radiocarbon assay of organic extracts from travertine     

Barbara M. Winsborough  S. Christopher Caran  James A. Neely  Salvatore Valastro 《Geoarchaeology》1996,11(1):37-50

A methodology for radiocarbon dating of calcified microbial mats has been developed and successfully applied in establishing a preliminary chronology for the prehistoric carbonate-encrusted canals of the Tehuacán Valley of Puebla, Mexico. In contrast to traditional carbonate dating techniques, this method focuses on the organic carbon component of the calcareous sediments. This method is based on the assumptions that (1) the carbon being dated is derived from the organisms associated with travertine buildup on canals, (2) these organisms are incorporated into the travertine contemporaneous with calcite precipitation, and (3) this carbon is then sequestered from most subsequent contamination and secondary fractionation. Evidence supporting these assumptions includes δ¹³C values, cultural chronologies, and stratigraphic relationships consistent with expectations. © 1996 John Wiley & Sons, Inc.  相似文献   

Damage detection of a steel–concrete composite frame by a multilevel approach: Experimental measurements and modal identification     

Giuseppe Chellini  Guido De Roeck  Luca Nardini  Walter Salvatore 《地震工程与结构动力学》2008,37(15):1763-1783

  相似文献