Levels and chemical speciation of arsenic in polychaetes: a review     

Daniele Fattorini  Alessandra Notti  Magdalena N. Halt  Maria Cristina Gambi  & Francesco Regoli 《Marine Ecology》2005,26(3-4):255-264

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Do endocrine disrupting chemicals threaten Mediterranean swordfish? Preliminary results of vitellogenin and Zona radiata proteins in Xiphias gladius     

M. Cristina Fossi  Silvia Casini  Stefania Ancora  Alessandra Moscatelli  Antonella Ausili  Giuseppe Notarbartolo-di-Sciara 《Marine environmental research》2001,52(5)

Endocrine Disrupting Chemicals (EDCs) have the potential to alter hormone pathways that regulate reproductive processes in wildlife and fishes. In this research the hypothesis that Mediterranean top predator species (such as large pelagic fish) are potentially at risk due to EDCs is investigated. These marine organisms tend to accumulate high concentrations of EDCs such as polyhalogenated aromatic hydrocarbons (PHAHs). The potential effects of EDCs on a fish species of commercial interest, the top predator Xiphias gladius (swordfish), were investigated using vitellogenin (Vtg) and Zona radiata proteins (Zrp) as diagnostic and prognostic biomarkers. Dramatic induction of typically female proteins (Vtg and Zrp) was detected by ELISA and Western Blot in adult males of the species. These results are the first warning of the potential risk for reproductive function of Mediterranean top predators, and suggest the need for continuous monitoring of this fragile marine environment.  相似文献   

The statistical approach to the study of planetary surfaces     

R. Bianchi  A. Coradini  M. Fulchignoni 《Earth, Moon, and Planets》1980,22(3):293-304

A review of the statistical methods and their application to the planetary sciences is presented. Univariate and multivariate methods are used, with different sophistication levels, to the search for the relationships between samples and/or variables belonging to data coming from space missions. Some numerical expressions, which summarize the information in mathematical terms, such as the mean, the variance, and the coefficient of variation are the best known and most widely used to perform a preliminar analysis of a data set. Techniques of regression and trend analysis allow us to compare the reciprocal behaviour of different variables, each treated as an univariate one. Making inferences about the statistical parameters permits the determination of the range of the parameter values which are consistent with the information contained in the samples. Multivariate analysis is devoted to the study of multidimensional (i.e., of several variables) distributions of the samples. The analysis of the variance is a multivariate technique useful in investigating whether or not two or more groups of multivariate observations come from populations with the same mean value. The discriminant analysis provides a function for classifying multivariate observations into groups. One of the simpler factorial techniques is the principal-components method in which the original variables are associated in a typical form that can be interpreted in terms of a genetic process. TheR-mode analysis is useful in identifying the number of important variables. TheQ-mode analysis permits us to group the observations providing clusters of samples. TheG-mode method, where the original multivariate distribution is transformed in a univariate quasi-Gaussian distribution, can be applied to identify homogenous group of samples and to classify new samples on the basis of the general groups.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.  相似文献   

X-ray spectromicroscopic investigation of natural organochlorine distribution in weathering plant material     

Alessandra C. Leri  Matthew A. Marcus 《Geochimica et cosmochimica acta》2007,71(23):5834-5846

Natural organochlorine (Cl_org) is ubiquitous in soil humus, but the distribution and cycling of different Cl species during the humification of plant material is poorly understood. Our X-ray spectromicroscopic studies indicate that the distributions of Cl_org and inorganic Cl⁻(Cl_inorg) in oak leaf material vary dramatically with decay stage, with the most striking changes occurring at the onset of weathering. In healthy or senescent leaves harvested from trees, Cl_inorg occurs in sparsely distributed, highly localized “hotspots” associated with trichomes as well as in diffuse concentration throughout the leaf tissue. The Cl_inorg associated with trichomes exists either in H-bonded form or in a solid salt matrix, while the Cl_inorg in diffuse areas of lower Cl concentration appears exclusively in H-bonded form. Most solid phase Cl_inorg leaches from the leaf tissue during early weathering stages, whereas the H-bonded Cl_inorg appears to leach away slowly as degradation progresses, persisting through advanced weathering stages. In unweathered leaves, aromatic and aliphatic Cl_org were found in rare but concentrated hotspots. In weathered leaves, by contrast, aromatic Cl_org hotspots are prevalent, often coinciding with areas of elevated Fe or Mn concentration. Aromatic Cl_org is highly soluble in leaves at early weathering stages and insoluble at more advanced stages. These results, combined with optical microscopy, suggest that fungi play a role in the production of aromatic Cl_org in weathering leaf material. Aliphatic Cl_org occurs in concentrated hotspots in weathered leaves as well as in diffuse areas of low Cl concentration. The distribution and speciation of Cl in weathering oak leaves depicted by this spectromicroscopic study provides new insight into the formation and cycling of Cl_org during the decay of natural organic matter.  相似文献   

Validation and fusion of different databases in preparation of high-resolution geoid determination     

Alessandra Borghi  Daniela Carrion  Giovanna Sona 《Geophysical Journal International》2007,171(2):539-549

An up to date determination of a high-resolution geoid requires the use of best available databases concerning digital terrain model (DTM), bathymetry, global geopotential model and gravity field. The occasion to revisit methods to validate and merge different data sets has been created by a new project for the determination of a new European Geoid.
Since the computation of the latest European geoid and quasi-geoid model (EGG97), significant new or improved data sets have become available, such as new global geopotential models from CHAMP and GRACE missions, new national and global DTMs and new or upgraded gravity data sets.
In the context of the new European Gravity and Geoid Project (EGGP), within the IAG Commission 2, some data validation tests have been performed in the Italian zone.
In the area 19°× 17° wide, covering Italy, three kinds of tests have been performed: comparison among different DTMs in order to choose the best one to be used; comparisons in terms of geoid computation in some coastal areas, to evaluate bathymetry effects, and the validation of the EIGEN-CG01C and EIGEN-CG03C new global models up to degree and order 360.
These preliminary tests lead to the choice of SRTM DTM (integrated in no-data holes), with an added bathymetry derived by the Italian 1:25 000 official cartography near the coasts and the NOAA bathymetry in high seas. The validation of the new global models and the comparison with EGM96 model show that, in terms of geoid computation, the EGM96 yields better results. Moreover, the validation of new available land gravity data and the cross-validation of two sets of gravity data on sea have been completed.  相似文献   

Multi-step SETARMA predictors in the analysis of hydrological time series   总被引：1，自引：0，他引：1  

Alessandra Amendola  Marcella Niglio 《Physics and Chemistry of the Earth》2006,31(18):1118-1126

The performance of the self-exciting threshold autoregressive moving average model in forecasting river flow data is investigated. Multi-step forecasts of two daily time series are generated through three different nonlinear predictors. The model adequacy to capture the main features of the data under study and its forecasting performance are analysed and discussed.  相似文献   

Influence of metal oxides in the colorimetric determination of acid volatile sulfide in sediments     

Janaina L. Oliveira  Alessandra Eugênio  Júlio C. Rodrigues de Azevedo  Jorge Nozaki 《洁净——土壤、空气、水》2006,34(4):383-388

The sediment of Lagoa dos Patos‐MS, Brazil, was investigated to verify the influence of metal sulfides and oxyhydroxides of Mn and Fe on the heavy metal availability. The spectrophotometric method of methylene blue was used, with 8 interlinked tubes containing the samples with SnCl₂, where N₂ was introduced to release the H₂S extracted with 6.0 mol L^–1 HCl, and trapped in 0.05 M NaOH solution. The influence of SO₄^2–, Mn(IV) and Fe(III) oxyhydroxides was investigated with samples constituted by a mixture of MnO₂; Na₂SO₄; FeCl₃, and sediments. The presence of SnCl₂ was very important to avoid the interferences of iron and manganese oxyhydroxides. The method of standard addition was applied and the efficiency was (100.8 ± 9.4)%. The ratio among the quantities of metals potentially available and the acid volatile sulfide (AVS) indicate that the system presents small metals availability to the benthic community, by the existence of sulfide capable to immobilize the metal as insoluble sulfide.  相似文献   

Intercomparison of Boron Isotope and Concentration Measurements. Part II: Evaluation of Results   总被引：3，自引：1，他引：3  

Roberto Gonfiantini  Sonia Tonarini  Manfred Grning  Alessandra Adorni‐Braccesi  Assad S. Al‐Ammar  Marcus Astner  Sebastien Bchler  Ramon M. Barnes  Randy L. Bassett  Alain Cocherie  Annette Deyhle  Andrea Dini  Giorgio Ferrara  Jrme Gaillardet  Judith Grimm  Catherine Guerrot  Urs Krhenbühl  Graham Layne  Damien Lemarchand  Anette Meixner  D. Jack Northington  Maddalena Pennisi  Eva Reitznerov  Ilia Rodushkin  Naoji Sugiura  Regina Surberg  Sabine Tonn  Michael Wiedenbeck  Samuel Wunderli  Yingkai Xiao  Thomas Zack 《Geostandards and Geoanalytical Research》2003,27(1):41-57

The Istituto di Geoscienze e Georisorse (IGG), on behalf and with the support of the International Atomic Energy Agency (IAEA), prepared eight geological materials (three natural waters and five rocks and minerals), intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials were distributed to twenty seven laboratories - virtually all those performing geochemical boron isotope analyses in the world -which agreed to participate in the intercomparison exercise. Only fifteen laboratories, however, ultimately submitted the isotopic and/or concentration results they obtained on the intercomparison materials. The results demonstrate that interlaboratory reproducibility is not well reflected by the precision values reported by the individual laboratories and this observation holds true for both boron concentration and isotopic composition. The reasons for the discrepancies include fractionations due to the chemical matrix of materials, relative shift of the zero position on the δ¹¹B scale and a lack of well characterized materials for calibrating absolute boron content measurements. The intercomparison materials are now available at the IAEA (solid materials) and IGG (waters) for future distribution.  相似文献   

Numerical investigation of the Break-down threshold for a restricted three-body problem     

Alessandra Celletti  Claude Froeschl 《Planetary and Space Science》1998,46(11-12)

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SCUBA imaging of the NGC 7331 dust ring     

S. Bianchi  P. B. Alton  J. I. Davies  & M. Trewhella 《Monthly notices of the Royal Astronomical Society》1998,298(3):L49-L53

We present observations of the spiral galaxy NGC 7331 using the Submillimetre Common User Bolometer Array (SCUBA) on the James Clark Maxwell Telescope. We have detected a dust ring of 45 arcsec radius (3.3 kpc) at wavelengths of 450 and 850 μm. The dust ring is in good correspondence with other observations of the ring in the mid-infrared (MIR), CO and radio continuum, suggesting that the observed dust is associated with molecular gas and star formation. A B  −  K colour map shows an analogous ring structure with an asymmetry about the major axis, consistent with the extinction being produced by a dust ring. The derived temperature of the dust lies between 16 and 31 K and the gas-to-dust ratio lies between 150 and 570, depending on the assumed dust emission efficiency index (β = 1.5 or 2).  相似文献