Geochronology of the American-Antarctic Ridge     

A. A. Schreider  Al. A. Schreider  A. A. Bulychev  J. Galindo-Zaldivar  A. Maldonado  G. L. Kashintsev 《Oceanology》2006,46(1):114-122

A new map of chrons for the American-Antarctic Ridge area has been compiled. Its analysis and the calculations performed showed that the seafloor spreading with respect to its axis started before 85 My B.P. The spreading directions were 115° (chrons C34-C29), 145° (chrons C29-C21), 110° (chrons C21-C5C), and 85° (chrons C5C-C1). The maximum rates of about 4 cm/year were reached earlier than 52 My B.P.; subsequently, a progressive general decrease in the spreading rate has been observed. According to our forecast, the spreading may cease in the following 3.5 My.  相似文献   

Alboran Sea late cenozoic tectonic and stratigraphic evolution     

A. Maldonado  A. C. Campillo  A. Mauffret  B. Alonso  J. Woodside  J. Campos 《Geo-Marine Letters》1992,12(2-3):179-186

Analysis of airgun seismic profiles from the Alboran Sea reveals a complex morphostructure with margins, basins, and structural highs. North of the Alboran Ridge, south-facing margins have a passive style of evolution, with thick progradational sequences of post-Messinian deposits, whereas north-facing margins are tectonized along structural highs with reduced sediment cover. Basins are extensional features developed since the Early Miocene by mechanisms of tectonic escape and pull-apart, under generalized northwest-southeast to north-south compression. Depositional sequences in this semi-land-locked sea were controlled by the local tectonism and influenced by global sea-level oscillations.  相似文献   

Gorringe Ridge gravity and magnetic anomalies are compatible with thrusting at a crustal scale     

J. Galindo-Zaldívar  A. Maldonado  A. A. Schreider 《Geophysical Journal International》2003,153(3):586-594

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Engagement in the Third U.S. National Climate Assessment: commitment,capacity, and communication for impact     

Emily Cloyd  Susanne C. Moser  Edward Maibach  Julie Maldonado  Tinqiao Chen 《Climatic change》2016,136(1):39-55

This paper examines the dynamics of energy investments and clean energy Research and Development (R&D) using a scenario-based modeling approach. Starting from the global scenarios proposed in the RoSE model ensemble experiment, we analyze the dynamics of investments under different assumptions regarding economic and population growth as well as availability of fossil fuel resources, in the absence of a climate policy. Our analysis indicates that economic growth and the speed of income convergence across countries matters for improvements in energy efficiency, both via dedicated R&D investments but mostly through capital-energy substitution. In contrast, fossil fuel prices, by changing the relative competitiveness of energy sources, create an economic opportunity for radical innovation in the energy sector. Indeed, our results suggest that fossil fuel availability is the key driver of investments in low carbon energy innovation. However, this innovation, by itself, is not sufficient to induce emission reductions compatible with climate stabilization objectives.  相似文献   

Engagement with indigenous peoples and honoring traditional knowledge systems     

Julie Maldonado  T. M. Bull Bennett  Karletta Chief  Patricia Cochran  Karen Cozzetto  Bob Gough  Margaret Hiza Redsteer  Kathy Lynn  Nancy Maynard  Garrit Voggesser 《Climatic change》2016,135(1):111-126

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A multi-tracer approach to delineate groundwater dynamics in the Rio Actopan Basin,Veracruz State,Mexico     

Juan Pérez Quezadas  Victor M. Heilweil  Alejandra Cortés Silva  Luis Araguas  María del Rocío Salas Ortega 《Hydrogeology Journal》2016,24(8):1953-1966

Geochemistry and environmental tracers were used to understand groundwater resources, recharge processes, and potential sources of contamination in the Rio Actopan Basin, Veracruz State, Mexico. Total dissolved solids are lower in wells and springs located in the basin uplands compared with those closer to the coast, likely associated with rock/water interaction. Geochemical results also indicate some saltwater intrusion near the coast and increased nitrate near urban centers. Stable isotopes show that precipitation is the source of recharge to the groundwater system. Interestingly, some high-elevation springs are more isotopically enriched than average annual precipitation at higher elevations, indicating preferential recharge during the drier but cooler winter months when evapotranspiration is reduced. In contrast, groundwater below 1,200 m elevation is more isotopically depleted than average precipitation, indicating recharge occurring at much higher elevation than the sampling site. Relatively cool recharge temperatures, derived from noble gas measurements at four sites (11–20 °C), also suggest higher elevation recharge. Environmental tracers indicate that groundwater residence time in the basin ranges from 12,000 years to modern. While this large range shows varying groundwater flowpaths and travel times, ages using different tracer methods (¹⁴C, ³H/³He, CFCs) were generally consistent. Comparing multiple tracers such as CFC-12 with CFC-113 indicates piston-flow to some discharge points, yet binary mixing of young and older groundwater at other points. In summary, groundwater within the Rio Actopan Basin watershed is relatively young (Holocene) and the majority of recharge occurs in the basin uplands and moves towards the coast.  相似文献   

Hispanic Immigrants' Vulnerabilities to Flood and Hurricane Hazards in Two United States Metropolitan Areas          下载免费PDF全文

Alejandra Maldonado  Timothy W. Collins  Sara E. Grineski 《Geographical review》2016,106(1):109-135

Research reveals that disasters are disproportionately debilitating for marginalized social groups. Numerous studies have examined racial/ethnic dimensions of disaster vulnerability, but few have focused on Hispanic immigrants. More research on Hispanic immigrants is needed, since they constitute a major component of the Hispanic population—the largest and fastest‐growing minority group in the U.S.—and because they experience distinctive cultural and immigration status disadvantages. We examine the flood/hurricane vulnerabilities of Hispanic immigrants in comparison to U.S.–born Hispanics and non‐Hispanic whites. Using mixed methods to analyze data from 429 surveys and 31 interviews with residents living in flood zones, we examine differences in self‐protective action, risk perception, and hazard knowledge between the three groups in Houston and Miami. Hispanic immigrants exhibited lower levels of self‐protection and hazard knowledge, and higher perceptions of risk, which reflects their heightened vulnerability. Risk‐reduction programs should target the particular vulnerabilities of Hispanic immigrants, and future studies should examine their vulnerabilities in other contexts.  相似文献   

Spatial characterization of the seawater upconing process in a coastal Mediterranean aquifer (Plana de Castellón,Spain): evolution and controls     

Olga García-Menéndez  Ignacio Morell  Bruno J. Ballesteros  Arianna Renau-Pruñonosa  Alejandra Renau-Llorens  Mª Vicenta Esteller 《Environmental Earth Sciences》2016,75(9):728

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An improved response spectrum method for calculating seismic design response. Part 1: Classically damped structures     

M. P. Singh  G. O. Maldonado 《地震工程与结构动力学》1991,20(7):621-635

A good response spectrum method, used for calculating the seismic design response for design inputs defined in terms of response spectra, should be able to include the effect of the higher modes, even though they may be truncated and not explicitly considered in the analysis. It should also be able to include the intercorrelation of the retained modes as well as their correlation with truncated modes. Herein one such method based on a suitable combination of the mode displacement and mode acceleration formulations of structural dynamics is proposed. Several numerical examples are presented to demonstrate the efficiency of the proposed approach vis-a-vis some other commonly used response spectrum approaches.  相似文献   

Retraction notice to “On the nature of relativistic stars” [Astropart. Phys. 32 (2009) 153-159]     

Silvia Morales  Alejandra Zorzi  Roberto Aquilano 《Astroparticle Physics》2011,35(1):40

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