MgAl2O4 spinels from Allende and NWA 763 carbonaceous chondrites: Structural refinement,cooling history,and trace element contents     

Davide Lenaz  Vanni Lughi  Diego Perugini  Maurizio Petrelli  Gianluca Turco  Birger Schmitz 《Meteoritics & planetary science》2019,54(12):3089-3100

MgAl₂O₄ spinels from Allende and NWA 763 carbonaceous chondrites were studied by X‐ray single crystal diffraction, SEM, electron microprobe, LA‐ICP‐MS, and Raman spectroscopy. Those from Allende are almost pure, but, in one case, we found a strong FeO_tot zonation. Spinels from NWA 763 show Mg‐Fe²⁺ substitutions. Almost pure MgAl₂O₄ spinels from both meteorites underwent slow cooling and reached their intracrystalline closure temperature (T_c) in the range 460–520 °C. The NWA 763 spinel with higher FeO content shows a T_c of about 720 °C. X‐ray single crystal diffraction and Raman spectroscopy suggest a slow cooling and an ordered structure with trivalent cations in M site and divalent in T site. Among the trace elements, Ti and Co are enriched with respect to the terrestrial analogs, while Mn, Ni, and Sn show intermediate values between different terrestrial occurrences. Vanadium cannot be used as a tracer of extraterrestrial origin as for Cr‐spinels, because its content is similar in extraterrestrial and terrestrial spinels. In the zoned crystal from Allende, Co show a strong zonation similar to that of FeO.  相似文献   

A multidisciplinary study of the Cape Peloro brackish area (Messina, Italy): characterisation of trophic conditions, microbial abundances and activities     

Marcella Leonardi  Filippo Azzaro  Maurizio Azzaro  Gabriella Caruso  Monique Mancuso  Luis Salvador Monticelli  Giovana Maimone  Rosabruna La Ferla  Francesco Raffa  & Renata Zaccone 《Marine Ecology》2009,30(S1):33-42

In the framework of the VECTOR DIVCOST Project, a 2-year investigation was started in 2006, with the aim of testing the sensibility of microbial parameters to environmental changes and of assessing whether they can provide information about functional changes in the carbon cycle. The investigation was performed in the surface waters of two small brackish ponds (Ganzirri and Faro), located in the Cape Peloro transitional area (Sicily, Italy). The seasonal changes in both the microbial compartment [bacterioplankton, vibrios, exoenzymatic hydrolysis of proteins and polysaccharides, bacterial secondary production (HBP) and community respiration] and the trophic state of suspended matter [total suspended matter (TSM), particulate organic carbon (POC), particulate organic nitrogen (PON), C/N] were analysed in relation to the hydrological characteristics [temperature, salinity, oxygen, fluorescence, NH₄, NO₂, NO₃, PO₄]. Despite marked differences in the nutritional input and the diversification in both carbon budget and trophic level, the two ponds show similar trends in many of the investigated factors, hardly influenced by seasonal variations. Temporally coupled trends were observed for some parameters (enzyme activities, vibrios abundances, respiratory activity), whereas others (POC, PON, heterotrophic bacterial production, bacterioplankton) showed a seasonal shift between the two lakes. The different behaviour found for the some biotic parameters suggests that their response to environmental conditions may be modulated differently between the two lakes, which, despite their spatial proximity and reciprocal connection, do not always show contemporaneous functional processes.  相似文献   

Coastal Phytoplankton Do Not Rest in Winter     

Adriana Zingone  Laurent Dubroca  Daniele Iudicone  Francesca Margiotta  Federico Corato  Maurizio Ribera d’Alcalà  Vincenzo Saggiomo  Diana Sarno 《Estuaries and Coasts》2010,33(2):342-361

The climatology and interannual variability of winter phytoplankton was analyzed at the Long Term Ecological Research Station MareChiara (LTER-MC, Gulf of Naples, Mediterranean Sea) using data collected from 1985 to 2006. Background winter chlorophyll values (0.2–0.5 μg chl a dm⁻³) were associated with the dominance of flagellates, dinoflagellates, and coccolithophores. Winter biomass increases (<5.47 μg chl a dm⁻³) were often recorded until 2000, generally in association with low-salinity surface waters (37.3–37.9). These blooms were most often caused by colonial diatoms such as Chaetoceros spp., Thalassiosira spp., and Leptocylindrus danicus. In recent years, we observed more modest and sporadic winter biomass increases, mainly caused by small flagellates and small non-colonial diatoms. The resulting negative chl a trend over the time series was associated with positive surface salinity and negative nutrient trends. Physical and meteorological conditions apparently exert a strict control on winter blooms, hence significant changes in winter productivity can be foreseen under different climatic scenarios.  相似文献   

Lava stones from Neapolitan volcanic districts in the architecture of Campania region,Italy     

Alessio Langella  Domenico Calcaterra  Piergiulio Cappelletti  Abner Colella  Maria Pia D’Albora  Vincenzo Morra  Maurizio de Gennaro 《Environmental Earth Sciences》2009,59(1):145-160

Results of a research carried out on the lavas from Campi Flegrei and Somma-Vesuvius volcanic districts are reported here. The lavas have been widely employed, since Roman age, in several important monumental buildings of the Campania region, mainly in the town of Naples and in its province. They are classified as trachytes (Campi Flegrei products), tephri-phonolites and phono-tephrites (Somma-Vesuvius complex) from a petrographical point of view. Sampling was carried out from well-known exploitation districts. A substantial chemical difference between the products of the two sectors was confirmed, while petrophysical characterization evidenced similarity among the two different materials, although some differences were recorded even in samples coming from the same exploitation site.  相似文献   

Insights on the spreading of the Tyrrhenian Sea from the magnetic anomaly pattern     

Giovanni Florio  Maurizio Fedi  Federico Cella 《地学学报》2011,23(2):127-133

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Geodemographics as a tool for targeting neighbourhoods in public health campaigns   总被引：2，自引：1，他引：1  

Jakob Petersen  Maurizio Gibin  Paul Longley  Pablo Mateos  Philip Atkinson  David Ashby 《Journal of Geographical Systems》2011,13(2):173-192

Geodemographics offers the prospects of integrating, modelling and mapping health care needs and other health indicators that are useful for targeting neighbourhoods in public health campaigns. Yet reports about this application domain has to date been sporadic. The purpose of this paper is to examine the potential of a bespoke geodemographic system for neighbourhood targeting in an inner city public health authority, Southwark Primary Care Trust, London. This system, the London Output Area Classification (LOAC), is compared to six other geodemographic systems from both governmental and commercial sources. The paper proposes two new indicators for assessing the performance of geodemographic systems for neighbourhood targeting based on local hospital demand data. The paper also analyses and discusses the utility of age- and sex standardisation of geodemographic profiles of health care demand.  相似文献   

An approach to <Emphasis Type="Italic">DEM</Emphasis> analysis for landform classification based on local gradients     

Sergio Camiz  Maurizio Poscolieri 《Earth Science Informatics》2018,11(2):287-305

In this paper we propose an exploratory methodology, devoted to classify the pixels of a Digital Elevation Model (DEM), to be used as a morphometric basis for studies in other frameworks. The aim is to classify the terrain units according to eight topographical local gradients, computed as differences between each pixel and the eight surrounding ones. A partition of the pixels into homogeneous classes is carried out, emphasizing different details of the terrain units characteristics. Each class is described by a complete set of statistics of terrain attributes, including elevation, slope, and aspect, and graphical tools are used to ease the understanding of the partition. In addition, appropriate colours are attributed to each class, in order to build a thematic map that may simulate a three-dimensional effect. They are defined by computing their hue and saturation according to each class mean slope and aspect, respectively. Applications to Mount Soratte (Italy) and Cephalonia island (Greece) show how the results may be successfully used to describe in different ways the morphometric structure of the terrain under study and provide appropriate graphical representations.  相似文献   

The Butterfly Diagram Fine Structure     

Maurizio Ternullo 《Solar physics》2007,240(1):153-164

The present work describes the evolution of the sunspot zone in cycles 20, 21, and 22. In each cycle, and in both hemispheres, the equatorward drift of the spot zone “center of mass” results from the alternation of five or six prograde (namely, equatorward) segments, with other stationary or poleward segments. The duration of the stationary/retrograde phases (resulting from averaging data pertaining to the six semicycles examined here) amounts to ≈36% of the total duration of these semicycles. In the prograde phases, the drift rate is almost twice the “traditional” equatorward rate, resulting only from the extreme positions of the spot zone center of mass (at the beginning and at the end of the cycle). If there were no stationary/retrograde phases, the cycle duration would be half the actual one. We conclude that the retrograde phases should not be regarded as accidental; rather, they are essential features of the 11-year cycle.  相似文献   

The speciation of ions in Tiber river estuary waters     

Frank J. Millero  Giuseppe Macchi  Maurizio Pettine 《Estuarine, Coastal and Shelf Science》1981,13(5):517-534

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The relativistic precession of the orbits     

Maurizio M. D’Eliseo 《Astrophysics and Space Science》2012,342(1):15-18

The relativistic precession can be quickly inferred from the nonlinear polar orbit equation without actually solving it.  相似文献