The interplanetary magnetic field environment at Mercury's orbit     

Haje Korth  Brian J. Anderson  Thomas H. Zurbuchen  James A. Slavin  Silvia Perri  Scott A. Boardsen  Daniel N. Baker  Sean C. Solomon  Ralph L. McNutt Jr. 《Planetary and Space Science》2011,59(15):2075-2085

Mercury is exposed to the most dynamic heliospheric space environment of any planet in the solar system. The magnetosphere is particularly sensitive to variations in the interplanetary magnetic field (IMF), which control the intensity and geometry of the magnetospheric current systems that are the dominant source of uncertainty in determinations of the internal planetary magnetic field structure. The Magnetometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has made extensive magnetic field observations in the inner heliosphere over the heliocentric distances of Mercury's orbit, between 0.31 and 0.47 AU. In this paper, Magnetometer data from MESSENGER, obtained at rates of 2 and 20 vector samples per second, are used together with previous observations in the inner heliosphere by Helios and at Earth by the Advanced Composition Explorer, to study the characteristics of IMF variability at Mercury's orbit. Although the average IMF geometry and magnitude depend on heliocentric distance as predicted by Parker, the variability is large, comparable to the total field magnitude. Using models for the external current systems we evaluate the impact of the variability on the field near the planet and find that the large IMF fluctuations should produce variations of the magnetospheric field of up to 30% of the dipole field at 200 km altitude, corresponding to the planned periapsis of MESSENGER's orbit at Mercury. The IMF fluctuations in the frequency range are consistent with turbulence, whereas evidence for dissipation was observed for . The transition between the turbulent and dissipative regimes is indicated by a break in the power spectrum, and the frequency of this break point is proportional to the IMF magnitude.  相似文献   

Ad hoc shared‐ride trip planning by mobile geosensor networks     

Stephan Winter  Silvia Nittel 《International journal of geographical information science》2013,27(8):899-916

Recent developments in miniaturization of computing devices, in location‐sensing technology and in ubiquitous short‐range wireless networks enable new types of social behaviour. This paper investigates one novel application of these technologies, ad hoc inner‐urban shared‐ride trip planning: Transportation clients such as pedestrians are seeking ad hoc shared rides from transportation hosts such as private automobiles, buses, taxi cabs or trains. While centralized trip planners are challenged by assigning clients and hosts in an ad hoc manner, in particular for non‐scheduled hosts, we consider the transportation network as a mobile geosensor network of agents that interact locally by short‐range communication and heuristic wayfinding strategies. This approach is not only fully scalable; we can also demonstrate that with short‐range communication, and hence, incomplete transportation network knowledge a system still can deliver near‐to‐optimal trips.  相似文献   

Real-time flood forecasting by relating local stage and remote discharge     

Silvia Barbetta  Tommaso Moramarco 《水文科学杂志》2013,58(9):1656-1674

Abstract

The rating curve model (RCM) proposed by Moramarco and co-authors is modified here for flood forecasting purposes without using rainfall information. The RCM is a simple approach for discharge assessment at a river site of interest based on relating the local recorded stage and the remote discharge monitored at an upstream gauged river site located some distance away. The proposed RCM for real-time application (RCM-RT), involves only two parameters and can be used for river reaches where significant lateral flows occur. The forecast lead time depends on the mean wave travel time of the reach. The model is found to be accurate for a long reach of the Po River (northern Italy) and for two branches of the Tiber River (central Italy) characterized by different intermediate drainage areas and wave travel times. Moreover, the assessment of the forecast uncertainty coming from the model parameters is investigated by performing a Monte Carlo simulation. Finally, the model capability to accurately forecast the exceedence of fixed hydrometric thresholds is analysed.

Editor D. Koutsoyiannis; Associate editor C. Perrin  相似文献   

A first estimation of tsunami hazard of the Pacific coast of Costa Rica from local and distant seismogenic sources     

Chacon-Barrantes  Silvia  Arozarena-Llopis  Isabel 《Ocean Dynamics》2021,71(8):793-810

Ocean Dynamics - Costa Rica has been affected by several local and distant tsunamis in the past, but the historical information is scarce and incomplete. Its Pacific coast stretches for over a...  相似文献   

B,V, and DDO photometric observations of red variable stars     

T. Storchi Bergmann  Silvia H. B. Livi  Roberto D. D. Costa 《Astrophysics and Space Science》1984,100(1-2):341-349

Light curves of the red variables L₂ Puppis, R Carinae, and S Carinae in the region of the spectrum covered by theB, V, and DDO photometry are presented. The behavior of the DDO color indices and their meaning for this type of star are discussed. S Carinae shows a different behavior from the other two stars that seems to be due to a population effect.  相似文献   

Le domaine Tariquide (arc de Gibraltar,Espagne et Maroc) : succession et hiatus de la sédimentation du Jurassique supérieur au Paléocène     

Michel Durand-Delga  Manuel Esteras  Silvia Gardin  Hélène Paquet 《Comptes Rendus Geoscience》2005,337(9):849-860

The originality of the Malm–Cretaceous series of the Tariquides (Gibraltar arc), as compared to those of the Rifian–Betic ‘Dorsale’ (Alboran domain), and especially with the Penibetic (Iberia) domain, is emphasized. In the Los Pastores Group, near Algeciras, Upper Tithonian nodular limestones directly lie on the Dogger and are followed by Aptychus-bearing limestones (Late Berriasian to Barremian). In the Musa Group, Rif, radiolarites are followed by siliceous limestones (Kimmeridgian–Tithonian), then by karst and massflow breccias connected to a Berriasian tectonics, by Aptychus-bearing marly limestones, then by karst filled by Turonian limestones, and finally by Maastrichtian–Palaeocene polychrome pelites, whose micropalaeontological and mineral compositions (clay minerals, FeMn nodules) refer to a deep-sea, probably infra-CCD, sedimentation. To cite this article: M. Durand-Delga et al., C. R. Geoscience 337 (2005).  相似文献   

XMM–Newton EPIC and Optical Monitor observations of Her X-1 over the 35-d beat period     

Silvia Zane  Gavin Ramsay  Mario A. Jimenez-Garate  Jan Willem den Herder  Charles J. Hailey 《Monthly notices of the Royal Astronomical Society》2004,350(2):506-516

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Cambro-Ordovician Magmatism in SE Brazil: U-Pb and Rb-Sr Ages, Combined with Sr and Nd Isotopic Data of Charnockitic Rocks from the Varzea Alegre Complex     

Julio Cezar Mendes  Silvia Regina de Medeiros  Ian McReath  Cristina Maria Pinheiro de Campos   《Gondwana Research》2005,8(3):337-345

In the central-southern region of Espírito Santo State, southeastern Brazil, several granitoids with a variable composition intruded high-grade metamorphic rocks, in the northern segment of the Ribeira fold belt. A close relationship between hydrous and anhydrous facies is present in some of the plutons, including the Varzea Alegre Igneous Complex, which has an inner domain formed by gabbro, diorite and granite, and an irregular outer ring of charnockitic rocks. These green megaporphyritic charnockites have primary anhydrous mineral assemblage, I-type and metaluminous character, and high-K calc-alkaline signature. U-Pb zircon single crystal ages obtained by TIMS indicate crystallization at about 500 Ma, similar to other late tectonic plutons of this part of the Ribeira belt. Sr and Nd isotopic ratios ranging from 0.7078 to 0.7096 and 0.5114 to 0.5116 respectively, are interpreted to be indicative of a hybrid origin from crustal and mantle-derived magmas. A binary diagram using Sr isotope ratios also demonstrates that the genesis of the charnockites probably included both magma mixing and fractional crystallization processes.  相似文献   

What criticality in cellular automata models of earthquakes?   总被引：1，自引：0，他引：1  

Silvia Castellaro  Francesco Mulargia 《Geophysical Journal International》2002,150(2):483-493

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Application of biomarkers for assessing the biological impact of dredged materials in the Mediterranean: the relationship between antioxidant responses and susceptibility to oxidative stress in the red mullet (Mullus barbatus)     

Regoli F  Pellegrini D  Winston GW  Gorbi S  Giuliani S  Virno-Lamberti C  Bompadre S 《Marine pollution bulletin》2002,44(9):912-922

In the period 1997-2000, approximately 1,800,000 m3 of material dredged from the Port of Leghorn was discharged into a sea dumping site located 14 miles from the coast. The red mullet (Mullus barbatus) was used as a bioindicator species for monitoring the biological impact of these discharges on a geographical and temporal scale. Organisms were sampled over three years (1998-2000) at different stations and several biomarkers, both of exposure and effect, were analyzed. Bioavailability of specific classes of pollutants was evaluated by analyzing levels of metallothioneins, the activity of cytochrome P450 1A (CYPIA) and of glutathione S-transferases. Among biomarkers of effect, special attention was paid to the balance between prooxidant challenge and antioxidant defenses, and to the appearance of damage caused by oxidative stress. The analyses of the main components of the antioxidant system included superoxide dismutase, catalase, glutathione peroxidases, glutathione reductase, glyoxalase I and II, and total glutathione. These data were integrated with the measurement of total oxyradical scavenging capacity (TOSC) as an indication of the overall biological resistance to toxicity of different forms of oxyradicals (peroxyl radicals, hydroxyl radicals and peroxynitrite). Results indicated a biological impact in organisms sampled near the disposal site; the impact was particularly evident during 1999 and mainly related to organic chemicals such as PAH. Exposure to these pollutants also caused variations in the levels and activity of several antioxidants. The analysis of TOSC, however, revealed that the overall capacity of specific tissues of organisms to absorb various oxidants was not seriously compromised when challenged with increased prooxidant pressures. Variations of single antioxidants were useful in revealing early warning "biological responses", while integration with TOSC analyses indicated if such changes also reflect a more integrated and functional "biological effect" with possible consequences at the organisms level. The red mullet appears to be a useful sentinel species for a biomarker approach to monitoring impact caused by dredged materials.  相似文献