Sample return of interstellar matter (SARIM)     

Ralf Srama  Thomas Stephan  Eberhard Grün  Norbert Pailer  Anton Kearsley  Amara Graps  Rene Laufer  Pascale Ehrenfreund  Nicolas Altobelli  Kathrin Altwegg  Siegfried Auer  Jack Baggaley  Mark J. Burchell  James Carpenter  Luigi Colangeli  Francesca Esposito  Simon F. Green  Hartmut Henkel  Mihaly Horanyi  Annette Jäckel  Sascha Kempf  Neil McBride  Georg Moragas-Klostermeyer  Harald Krüger  Pasquale Palumbo  Andre Srowig  Mario Trieloff  Peter Tsou  Zoltan Sternovsky  Oliver Zeile  Hans-Peter Röser 《Experimental Astronomy》2009,23(1):303-328

The scientific community has expressed strong interest to re-fly Stardust-like missions with improved instrumentation. We propose a new mission concept, SARIM, that collects interstellar and interplanetary dust particles and returns them to Earth. SARIM is optimised for the collection and discrimination of interstellar dust grains. Improved active dust collectors on-board allow us to perform in-situ determination of individual dust impacts and their impact location. This will provide important constraints for subsequent laboratory analysis. The SARIM spacecraft will be placed at the L2 libration point of the Sun–Earth system, outside the Earth’s debris belts and inside the solar-wind charging environment. SARIM is three-axes stabilised and collects interstellar grains between July and October when the relative encounter speeds with interstellar dust grains are lowest (4 to 20 km/s). During a 3-year dust collection period several hundred interstellar and several thousand interplanetary grains will be collected by a total sensitive area of 1 m². At the end of the collection phase seven collector modules are stored and sealed in a MIRKA-type sample return capsule. SARIM will return the capsule containing the stardust to Earth to allow for an extraction and investigation of interstellar samples by latest laboratory technologies.  相似文献   

Comets in the near-Earth object population   总被引：1，自引：0，他引：1  

Francesca DeMeo 《Icarus》2008,194(2):436-449

Because the lifespan of near-Earth objects (NEOs) is shorter than the age of the Solar System, these objects originate elsewhere. Their most likely sources are the main asteroid belt and comets. Through physical observations we seek to identify potential dormant or extinct comets among “asteroids” catalogued as NEOs and thereby determine the fraction of “comet candidates” within the total NEO population. Both discovery statistics and dynamical models indicate that candidate cometary objects in near-Earth space are predominantly found among those having a jovian Tisserand parameter Tj<3. Therefore, we seek to identify comet candidates among asteroid-like NEOs using three criteria: Tj<3, spectral parameters (C, D, T, or P taxonomic types), and/or low (<0.075) albedos. We present new observations for 20 NEOs having Tj<3, consisting of visible spectra, near-infrared spectra, and/or albedo measurements obtained using the NASA Infrared Telescope Facility, the Kitt Peak National Observatory 4 m, and the Magellan Observatory 6.5-m. Four of our “asteroid” targets have been subsequently confirmed as low activity comets. Thus our sample includes spectra of the nuclei of Comets 2002 EX12 = 169P (NEAT), 2001 WF2 = 182P (LONEOS), 2003 WY25 = D/1891 W1 (Blanplain), and Halley Family Comet 2006 HR30 = P/2006 HR30 (Siding Spring). From the available literature, we tabulate physical properties for 55 NEOs having Tj<3, and after accounting for possible bias effects, we estimate that 54±10% of NEOs in Tj<3 orbits have “comet-like” spectra or albedos. Bias corrected discovery statistics [Stuart, J.S., Binzel, R.P., 2004. Icarus 170, 295-311] estimate 30±5% of the entire NEO population resides in orbits having Tj<3. Combining these two factors suggests that 16±5% of the total discovered “asteroid-like” NEO population has “comet-like” dynamical and physical properties. Outer main-belt asteroids typically have similar taxonomic and albedo properties as our “comet candidates.” Using the model of Bottke et al. [Bottke, W.F., Morbidelli, A., Jedicke, R., Petit, J.M., Levison, H., Michel, P., Metcalfe, T.S., 2002. Icarus 156, 399-433] to evaluate source region probabilities, we conclude that 8±5% of the total asteroid-like NEO population have the requisite orbital properties, physical properties, and dynamical likelihood to have originated as comets from the outer Solar System.  相似文献   

Environmental impacts of household appliances in Europe and scenarios for their impact reduction     

Roland Hischier  Francesca Reale  Valentina Castellani  Serenella Sala 《Chemie der Erde / Geochemistry》2010

Assessing the environmental impact due to consumption of goods and services is a pivotal step towards achieving the sustainable development goal related to responsible production and consumption (i.e. SDG 12). Household appliances plays a crucial role and should be assessed in a systemic manner, namely considering all life cycle stages, technological efficiency, and affluence aspects. The present study assess the impact of such household appliances used in Europe, and tests scenarios of potential impact reduction at various scales. Life cycle assessment is applied to 14 different household appliances (ranging from dishwashers to television devices) selected to build a set of representative products, based on their economic value and diffusion in households in Europe. Related impacts are calculated with the Environmental Footprint method for calculating a Consumer Footprint “appliances” for the baseline year 2010. A number of scenarios encompassing eco-solutions on a technical level, changes in consumption pattern, behavioral changes, as well as the combination of all these aspects are run to estimate the Consumer Footprint related to household appliances for the year 2030, compared against this baseline scenario. The baseline Consumer Footprint is confirming the importance of the use phase in leading the impacts in almost all impact categories. Testing different scenarios concludes that there is a reduction of the impact for most of the categories (with up to 67% for the ozone depletion potential, and still around 35% for the global warming potential), while two of the here examined impact categories (i.e. land-use and mineral resource depletion) show an overall potential that is even negative – i.e. the results of all scenarios are higher than the ones of the 2010 baseline scenario. The increase in purchase and use of such appliances may offset energy efficiency benefits in some of the examined categories. Hence, the assessment of sustainability of appliances consumption should always include several scales, from the efficiency of the products (micro scale), to the improvement of the energy mix (meso scale), up to accounting for socio-economic drivers and patterns of consumption affecting the overall appliances stock (macro scale).  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   

First directional archaeomagnetic results from Syria: evidence from Tell Mishrifeh/Qatna     

Fabio Speranza  Lara Maritan  Claudio Mazzoli  Daniele Morandi Bonacossi  Francesca D'Ajello Caracciolo 《Geophysical Journal International》2006,165(1):47-52

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Probabilistic landslide hazard assessment at the basin scale   总被引：32，自引：9，他引：32  

Fausto Guzzetti  Paola Reichenbach  Mauro Cardinali  Mirco Galli  Francesca Ardizzone 《Geomorphology》2005,72(1-4):272-299

We propose a probabilistic model to determine landslide hazard at the basin scale. The model predicts where landslides will occur, how frequently they will occur, and how large they will be. We test the model in the Staffora River basin, in the northern Apennines, Italy. For the study area, we prepare a multi-temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1955 and 1999. We partition the basin into 2243 geo-morpho-hydrological units, and obtain the probability of spatial occurrence of landslides by discriminant analysis of thematic variables, including morphological, lithological, structural and land use. For each mapping unit, we obtain the landslide recurrence by dividing the total number of landslide events inventoried in the unit by the time span of the investigated period. Assuming that landslide recurrence will remain the same in the future, and adopting a Poisson probability model, we determine the exceedance probability of having one or more landslides in each mapping unit, for different periods. We obtain the probability of landslide size by analysing the frequency–area statistics of landslides, obtained from the multi-temporal inventory map. Assuming independence, we obtain a quantitative estimate of landslide hazard for each mapping unit as the joint probability of landslide size, of landslide temporal occurrence and of landslide spatial occurrence.  相似文献   

Latest Precambrian to Early Cambrian U–Pb zircon ages of augen gneisses from Calabria (Italy), with inference to the Alboran microplate in the evolution of the peri-Gondwana terranes     

Francesca Micheletti  Pierre Barbey  Annamaria Fornelli  Giuseppe Piccarreta  Etienne Deloule 《International Journal of Earth Sciences》2007,96(5):843-860

In situ U–Pb dating of zircons from five samples of Calabrian augen gneisses shows that their protoliths are Latest Precambrian to Early Cambrian in age (562 ± 15, 547 ± 7, 540 ± 4, 539 ± 16 and 526 ± 10 Ma), and contain Archaean (3.1 Ga), Palaeoproterozoic (1.7–2.4 Ga) and Neoproterozoic (0.6–0.9 Ga) inheritance. Geochemical signature of augen gneisses is typical of high-K calc-alkaline post-collisional magmatism. Their Sr–Nd isotopic compositions [0.7093 < (⁸⁷Sr/⁸⁶Sr)_i < 0.7139; −3.2 < ɛ_Nd(t) < −5.4; 1.5 < T _DM < 1.7 Ga] indicate the involvement of a crustal component in significant proportions. The Calabrian augen gneisses have, therefore, to be distinguished from the orthogneisses of Sardinia and northern Algeria, and from the porphyroids of Sicily, which are Middle Ordovician. By contrast, the Calabrian augen gneisses show a close similarity to the Pan-African post-collisional granitoids of the northern edge of the West African craton (e.g. the Moroccan Anti-Atlas). This suggests a peri-Gondwana origin and corroborates previous palaeogeodynamic reconstructions attributing the Alboran microplate to the northern margin of the West African craton.  相似文献   

Predictive ground motion scaling in Switzerland: Best estimates and uncertainties     

Francesca?Bay  Stefan?WiemerEmail author  Donat?F?h  Domenico?Giardini 《Journal of Seismology》2005,9(2):223-240

Spectral ground motion (1 to 15 Hz) as a function of distance is modeled for events spanning 3.0 <M_w ≤ 7.0 in Switzerland. The parameters required to simulate ground motion with a stochastic approach are inverted from 2958 horizontal and vertical component waveforms of small to moderate size events (2.0 ≤ M_{L} ≤ 5.2) in the distance range 10 to 300 km recorded on hard rock sites. Using a Monte Carlo simulation, we establish a significantly different amplification of about a factor of 1.9 between the Alpine Foreland and the Alps. To assess the trade-off between the free parameters of our stochastic model and their influence on the predictive ground motion relationship, we perform a grid search over the five-dimensional solution space. The uncertainties are separated into epistemic and aleatory parts; the main epistemic uncertainty is attributed to the lack of data forM > 5. To constrain the viable models at large magnitudes, results from worldwide scaling studies are evaluated in light of the Swiss data. The model that explains best the low observed stress drops at small magnitudes (Δσ ≅ 3 bar) yet matches observed intensities of historical earthquakes assumes a stress drop increasing with moment asM₀^0.25. For three sites in Switzerland we evaluate the sensitivity of the epistemic uncertainty by computing probabilistic hazard curves. Our model offers the most comprehensive and detailed study of spectral ground motion for Switzerland to date.  相似文献   

A broad iron Kα line at z= 1.146     

Andrea Comastri  Marcella Brusa  Francesca Civano 《Monthly notices of the Royal Astronomical Society》2004,351(1):L9-L13

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X-ray spectral analysis of optically faint sources in the Chandra deep fields     

Francesca Civano  rea Comastri  Marcella Brusa 《Monthly notices of the Royal Astronomical Society》2005,358(2):693-704

We present the results of a detailed spectral analysis of optically faint hard X-ray sources in the Chandra deep fields selected on the basis of their high X-ray to optical flux ratio (X/O). The stacked spectra of high X/O sources in both Chandra deep fields, fitted with a single power-law model, are much harder than the spectrum of the X-ray background (XRB). The average slope is also insensitive to the 2–8 keV flux, being approximately constant around Γ≃ 1 over more than two decades, strongly indicating that high X/O sources represent the most obscured component of the XRB. For about half of the sample, a redshift estimate (in most of the cases a photometric redshift) is available from the literature. Individual fits of a few of the brightest objects and of stacked spectra in different redshift bins imply column densities in the range  10²²–10^23.5 cm⁻²  . A trend of increasing absorption towards higher redshifts is suggested.  相似文献