The star formation histories of galaxies in the Sloan Digital Sky Survey   总被引：1，自引：0，他引：1  

Benjamin Panter  Raul Jimenez  Alan F. Heavens  Stephane Charlot 《Monthly notices of the Royal Astronomical Society》2007,378(4):1550-1564

We present the results of a moped analysis of  ∼3 × 10⁵  galaxy spectra from the Sloan Digital Sky Survey Data Release 3 (SDSS DR3), with a number of improvements in data, modelling and analysis compared with our previous analysis of DR1. The improvements include: modelling the galaxies with theoretical models at a higher spectral resolution of 3 Å, better calibrated data, an extended list of excluded emission lines and a wider range of dust models. We present new estimates of the cosmic star formation rate (SFR), the evolution of stellar mass density and the stellar mass function from the fossil record. In contrast to our earlier work the results show no conclusive peak in the SFR out to a redshift around 2 but continue to show conclusive evidence for 'downsizing' in the SDSS fossil record. The star formation history is now in good agreement with more traditional instantaneous measures. The galaxy stellar mass function is determined over five decades of mass, and an updated estimate of the current stellar mass density is presented. We also investigate the systematic effects of changes in the stellar population modelling, the spectral resolution, dust modelling, sky lines, spectral resolution and the change of data set. We find that the main changes in the results are due to the improvements in the calibration of the SDSS data, changes in the initial mass function and the theoretical models used.  相似文献   

GeoWeb and crisis management: issues and perspectives of volunteered geographic information   总被引：3，自引：0，他引：3  

Stephane Roche  Eliane Propeck-Zimmermann  Boris Mericskay 《GeoJournal》2013,78(1):21-40

Mapping, and more generally geopositioning, has become ubiquitous on the Internet. This democratization of geomatics through the GeoWeb results in the emergence of a new form of mapping based on Web 2.0 technologies. Described as Web-mapping 2.0, it is especially characterized by high interactivity and geolocation-based contents generated by users. A series of recent events (hurricanes, earthquakes, pandemics) have urged the development of numerous mapping Web applications intended to provide information to the public, and encourage their contribution to support crisis management. This new way to produce and spread geographic information in times of crisis brings up many questions and new potentials with regard to urgency services, Non Governmental Organisations (NGO), as well as individuals. This paper aims at putting into perspective the development of GeoWeb, both in terms of technologies and applications, against crisis management processes.  相似文献   

A new scenario framework for Climate Change Research: scenario matrix architecture   总被引：2，自引：2，他引：0  

Detlef P. van Vuuren  Elmar Kriegler  Brian C. O’Neill  Kristie L. Ebi  Keywan Riahi  Timothy R. Carter  Jae Edmonds  Stephane Hallegatte  Tom Kram  Ritu Mathur  Harald Winkler 《Climatic change》2014,122(3):373-386

This paper describes the scenario matrix architecture that underlies a framework for developing new scenarios for climate change research. The matrix architecture facilitates addressing key questions related to current climate research and policy-making: identifying the effectiveness of different adaptation and mitigation strategies (in terms of their costs, risks and other consequences) and the possible trade-offs and synergies. The two main axes of the matrix are: 1) the level of radiative forcing of the climate system (as characterised by the representative concentration pathways) and 2) a set of alternative plausible trajectories of future global development (described as shared socio-economic pathways). The matrix can be used to guide scenario development at different scales. It can also be used as a heuristic tool for classifying new and existing scenarios for assessment. Key elements of the architecture, in particular the shared socio-economic pathways and shared policy assumptions (devices for incorporating explicit mitigation and adaptation policies), are elaborated in other papers in this special issue.  相似文献   

The need for and use of socio-economic scenarios for climate change analysis: A new approach based on shared socio-economic pathways     

Elmar Kriegler  Brian C. O’Neill  Stephane Hallegatte  Tom Kram  Robert J. Lempert  Richard H. Moss  Thomas Wilbanks 《Global Environmental Change》2012,22(4):807-822

Socio-economic scenarios constitute an important tool for exploring the long-term consequences of anthropogenic climate change and available response options. A more consistent use of socio-economic scenarios that would allow an integrated perspective on mitigation, adaptation and residual climate impacts remains a major challenge. We assert that the identification of a set of global narratives and socio-economic pathways offering scalability to different regional contexts, a reasonable coverage of key socio-economic dimensions and relevant futures, and a sophisticated approach to separating climate policy from counter-factual “no policy” scenarios would be an important step toward meeting this challenge. To this end, we introduce the concept of “shared socio-economic (reference) pathways”. Sufficient coverage of the relevant socio-economic dimensions may be achieved by locating the pathways along the dimensions of challenges to mitigation and to adaptation. The pathways should be specified in an iterative manner and with close collaboration between integrated assessment modelers and impact, adaptation and vulnerability researchers to assure coverage of key dimensions, sufficient scalability and widespread adoption. They can be used not only as inputs to analyses, but also to collect the results of different climate change analyses in a matrix defined by two dimensions: climate exposure as characterized by a radiative forcing or temperature level and socio-economic development as classified by the pathways. For some applications, socio-economic pathways may have to be augmented by “shared climate policy assumptions” capturing global components of climate policies that some studies may require as inputs. We conclude that the development of shared socio-economic (reference) pathways, and integrated socio-economic scenarios more broadly, is a useful focal point for collaborative efforts between integrated assessment and impact, adaptation and vulnerability researchers.  相似文献   

A study of marine pollution caused by the release of metals into seawater following acid spills     

Jean-Yves Cabon  Stephane Le Floch 《Marine pollution bulletin》2010,60(7):998-1004

This study examined the potential metal pollution induced by the accidental spill of different acids into seawater. The acids sink to the bottom according to their densities and subsequently react with marine sediments. The acids selected for this study were acetic, hydrochloric, nitric, sulfuric, and phosphoric acids; the metallic elements selected were Cr, Cu, Fe, Mn, Pb and Zn. The sediment was collected in Brest Harbour. The percentages of metals released from this sediment in the presence of various concentrations of acids in seawater were important; concentrations of approximately 7 mg L⁻¹ for Mn and 60 mg L⁻¹ for Zn were observed under our experimental conditions. We also examined the rate of release of these metals from the sediment into the seawater in the presence of the different acids and under different experimental conditions. We found that most of the metallic elements were released from the sediments into the seawater during the first fifteen minutes of exposure. After this time, a high degree of pollution was induced if acids leached into seawater were not rapidly diluted.  相似文献   

An opportunity to connect the morphodynamics of alternate bars with their sedimentary products     

Stephane Rodrigues  Nicolas Claude  Philippe Juge  Jean‐Gabriel Breheret 《地球表面变化过程与地形》2012,37(2):240-248

Field investigations that help clarify local sedimentary processes involved in the migration of alternate bars as a consequence of flood events are lacking. A simple approach combining scour chains, stratigraphy and frequent bathymetric surveys is proposed to connect the dynamics of free migrating alternate bars present in disconnected channels of large sandy‐gravelly rivers with their sedimentary products and vice versa. The results show that the spatial distribution of bars before a flood partly governs the scour and fill processes and that the sediment transport rates vary significantly on a single cross‐section. This can be due to preferential axes of the migration of the bars determined by their location on the cross‐section, the bank direction and the discharge. The approach allows the reconstruction of local sedimentary processes involved in alternate bar migration by combining maximum scour depths reached during a flood with frequent channel bed topography surveys and post‐flood stratigraphy. It is also possible to distinguish deposited and preserved sediments compared with sediments by‐passed during the flood. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Electrochemical Degradation of Carbamazepine in Aqueous Solutions – Optimization of Kinetic Aspects by Design of Experiments          下载免费PDF全文

Patricia Palo  Joaquin R. Dominguez  Jesús Sánchez‐Martín  Teresa González 《洁净——土壤、空气、水》2014,42(11):1534-1540

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Spatial Heterogeneity in Earthquake Fault-Like Systems     

J. Kazemian  R. Dominguez  K. F. Tiampo  W. Klein 《Pure and Applied Geophysics》2015,172(8):2167-2177

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IPCC-AR4 climate simulations for the Southwestern US: the importance of future ENSO projections     

Francina Dominguez  Julio Cañon  Juan Valdes 《Climatic change》2010,99(3-4):499-514

Future climate trends for the Southwestern US, based on the climate models included in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, project a more arid climate in the region during the 21st century. However, future climate variability associated with El Niño Southern Oscillation (ENSO)—an important driver for winter climate variability in the region—have not been addressed. In this work we evaluate future winter ENSO projections derived from two selected IPCC models, and their effect on Southwestern US climate. We first evaluate the ability of the IPCC coupled models to represent the climate of the Southwest, selecting the two models that best capture seasonal precipitation and temperature over the region and realistically represent ENSO variability (Max Planck Institute’s ECHAM5 and the UK Met Office HadCM3). Our work shows that the projected future aridity of the region will be dramatically amplified during La Niña conditions, as anomalies over a drier mean state, and will be characterized by higher temperatures (~0.5°C) and lower precipitation (~3 mm/mnt) than the projected trends. These results have important implications for water managers in the Southwest who must prepare for more intense winter aridity associated with future ENSO conditions.  相似文献   

Deep structure, recent deformation and analog modeling of the Gulf of Cadiz accretionary wedge: Implications for the 1755 Lisbon earthquake     

Marc-André Gutscher  Stephane Dominguez  Pascal Leroy 《Tectonophysics》2009,475(1):85-149

The Gulf of Cadiz spans the plate boundary between Africa and Eurasia west of the Betic-Rif mountain belt. A narrow east dipping subduction zone descends beneath the Gulf of Cadiz and the straits of Gibraltar. The deep crustal structure of the Gulf and the adjacent SW Iberian and Moroccan margins is constrained by numerous multi-channel seismic reflection and wide-angle seismic surveys. A compilation of these existing studies is presented in the form of depth to basement, sediment thickness, depth to Moho and crustal thickness maps. These structural maps image an E-W trending trough, with thin (< 10 km) crust beneath the Gulf of Cadiz. This trough is filled by an eastward thickening wedge of sediments, reaching a thickness of 10-15 km in the eastern Gulf. These sediments are tectonically deformed, primarily along a series of westward-vergent thrust faults and represent a 200-250 km wide accretionary wedge. The northern and especially the southern limits of the accretionary wedge are marked by sharp morphological lineaments showing evidence of recent deformation. These tectonic limits are situated in an internal position with respect to the Miocene deformation front (external Betic and Rif allocthons), which has been abandoned. At the western boundary of the accretionary wedge, near the adjacent Seine and Horseshoe abyssal plains, an E-W trending basement high (Coral Patch Ridge) can be seen indenting the deformation front in an asymmetric manner. Analog modeling is performed using granular materials accreted against a semicircular backstop (representing the basement of the Rif and Betic mountain belts). The modeling initially produces a symmetric, arcuate accretionary wedge. The ensuing collision of an oblique rigid indenter retards accretion on one side, resulting in an embayment and a locally steeper deformation front. The deformation pattern observed in morphology and high-resolution seismic profiles suggests the accretionary wedge and underlying subduction system is still active. The implications of active subduction for the source region of the 1755 Lisbon earthquake and the regional seismic hazard assessment are discussed.  相似文献