Enhanced molecular abundances in low-mass star-forming cores     

Serena Viti  Sukina Natarajan  David A. Williams 《Monthly notices of the Royal Astronomical Society》2002,336(3):797-802

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A laboratory survey of the thermal desorption of astrophysically relevant molecules     

Mark P. Collings  Mark A. Anderson  Rui Chen  John W. Dever  Serena Viti  David A. Williams  Martin R. S. McCoustra 《Monthly notices of the Royal Astronomical Society》2004,354(4):1133-1140

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Effects of rainwater-harvesting-induced artificial recharge on the groundwater of wells in Rajasthan, India     

John M. Stiefel  Assefa M. Melesse  Michael E. McClain  René M. Price  Elizabeth P. Anderson  Narendra K. Chauhan 《Hydrogeology Journal》2009,17(8):2061-2073

In light of the increasing deterioration of groundwater supplies in Rajasthan, India, rainwater harvesting practices in southern Rajasthan were studied to determine the effects of artificially recharged groundwater on the supply and quality of local groundwater. A physical and geochemical investigation utilizing environmental tracers (δ¹⁸O and Cl^–), groundwater level and groundwater quality measurements, and geological surveys was conducted with two objectives: (1) to quantify the proportion of artificially recharged groundwater in wells located near rainwater harvesting structures and (2) to examine potential effects of artificial recharge on the quality of groundwater in these wells. A geochemical mixing model revealed that the proportion of artificial recharge in these wells ranged from 0 to 75%. Groundwater tracer, water table, and geological data provided evidence of complex groundwater flow and were used to explain the spatial distribution of artificial recharge. Furthermore, wells receiving artificial recharge had improved groundwater quality. Statistical analysis revealed a significant difference between the water quality in these wells and wells determined not to receive artificial recharge, for electrical conductivity and SO ₄ ^– . The findings from this study provide quantitative evidence that rainwater harvesting structures in southern Rajasthan influence the groundwater supply and quality of nearby wells by artificially recharging local groundwater.  相似文献   

A comparison of galaxy merger history observations and predictions from semi-analytic models     

Serena Bertone  Christopher J. Conselice 《Monthly notices of the Royal Astronomical Society》2009,396(4):2345-2358

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Revealing the “fingerprints” of the magnetic precursor of C-shocks     

Izaskun Jiménez-Serra  Jesús Martín-Pintado  Arturo Rodríguez-Franco  Paola Caselli  Serena Viti  Tom Hartquist 《Astrophysics and Space Science》2008,313(1-3):159-163

We present the first C-shock and radiative transfer model that calculates the evolution of the line profiles of neutral and ion species like SiO, H¹³CO⁺ and HN¹³C for different flow times along the propagation of the shock through the unperturbed gas. We find that the line profiles of SiO characteristic of the magnetic precursor stage have very narrow linewidths and are centered at velocities close to the ambient cloud velocity, as observed toward the young shocks in the L1448-mm outflow. Consistently with previous works, our model also reproduces the broad SiO emission detected in the high velocity gas in this outflow, for the downstream postshock gas in the shock. This implies that the different velocity components observed in L1448-mm are due to the coexistence of different shocks at different evolutionary stages.  相似文献   

Probabilistic Analysis of Suture Lines Developed in Ammonites: The Jurassic Examples of Hildocerataceae and Hammatocerataceae     

Andrea Di Cencio  Serena Doria 《Mathematical Geosciences》2017,49(6):737-750

Ammonites are extinct molluscs belonging to Class Cephalopoda which lived during the Mesozoic Era. Their usefulness in Jurassic and Cretaceous paleontology and biostratigraphy studies has been widely proved. They have been studied by several authors worldwide to achieve information regarding their habitats and the climate of the world in past eras. A probabilistic analysis of the paleo-environmental causes that generated complex suture lines in ammonites has been made by means of coherent upper conditional previsions defined with respect to Hausdorff outer measures. In particular, studies have centered on the role of hydrostatic pressure.  相似文献   

Study of Volcanic Sources at Long Valley Caldera,California, Using Gravity Data and a Genetic Algorithm Inversion Technique   总被引：2，自引：0，他引：2  

M.?CharcoEmail author  J.?Fernández  K.?Tiampo  M.?Battaglia  L.?Kellogg  J.?McClain  J. B.?Rundle 《Pure and Applied Geophysics》2004,161(7):1399-1413

We model the source inflation of the Long Valley Caldera, California, using a genetic algorithm technique and micro-gravity data. While there have been numerous attempts to model the magma injection at Long Valley Caldera from deformation data, this has proven difficult given the complicated spatial and temporal nature of the volcanic source. Recent work illustrates the effectiveness of considering micro-gravity measurements in volcanic areas. A genetic algorithm is a problem-solving technique which combines genetic and prescribed random information exchange. We perform two inversions, one for a single spherical point source and another for two-sources that might represent a more spatially distributed source. The forward model we use to interpret the results is the elastic-gravitational Earth model which takes into account the source mass and its interaction with the gravity field. The results demonstrate the need to incorporate more variations in the model, including another source geometry and the faulting mechanism. In order to provide better constraints on intrusion volumes, future work should include the joint inversion of gravity and deformation data during the same epoch.  相似文献   

Recent advances in star-formation studies     

David A Williams  Serena Viti 《Astronomy& Geophysics》2005,46(1):1.30-1.31

David A Williams and Serena Viti survey the contributions made to this fast-moving field at a recent RAS Discussion Meeting. The resulting debates were often both challenging and confrontational.  相似文献   

The structure of the oceanic crust off southern Peru determined from an ocean bottom seismometer     

Charles A. Meeder  B.T.R. Lewis  J. McClain 《Earth and Planetary Science Letters》1977,37(1):13-28

An oceanic crustal model has been produced for the Nazca plate south of the Nazca Ridge prior to subduction into the Peru-Chile Trench at 18°S latitude. Consistent delays of theP_n arrivals and a discontinuity in the tau-p curve indicate a low-velocity zone at the base of the crust. Observed upper mantle velocities are low; however, the mantle velocity increases with depth, at least to 20 km, to a value of 8.5 km/s. A possible petrological cause for the low-velocity zone is partially serpentinized peridotite; however, no clear refracted shear waves were observed to constrain this interpretation.  相似文献   

Passive radiometry of the ocean from space—an overview     

E. Paul McClain 《Boundary-Layer Meteorology》1980,18(1):7-24

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