The nature of the Wolf–Rayet galaxy Mrk 209 from photoionization models     

Enrique Pérez-Montero †  Ángeles I. Díaz ‡ 《Monthly notices of the Royal Astronomical Society》2007,377(3):1195-1205

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Growth and photosynthetic responses to copper stress of an invasive cordgrass, Spartina densiflora     

Mateos-Naranjo E  Redondo-Gómez S  Cambrollé J  Enrique Figueroa M 《Marine environmental research》2008,66(4):459-465

Spartina densiflora Brongn. is found in coastal marshes of south-west Spain, growing in sediments with between 300 and 3000mg Cu kg(-1) total soil DW (450-4500mg Cu kg(-1) supposing that the soil porosity is 0.5). An experiment was designed to investigate the effect of copper from 0 to 5000mgkg(-1) (64mmoll(-1)) on the photosynthetic apparatus and the growth of S. densiflora. We also determined total ash, copper, calcium, magnesium and phosphorous concentrations, as well as C/N ratio. S. densiflora survived to concentrations as high as 320mg Cukg(-1) DW in leaves, although excess of Cu diminished water use efficiency and Ca-, Mg- and P-uptake. Also, quantum efficiency of PSII, net photosynthetic rate, stomatal conductance and pigment concentrations declined with increasing external Cu. Finally, the decline in the photosynthetic function resulted in a biomass reduction of between 50 and 80% (for 600 and 5000mg Cu kg(-1), respectively).  相似文献   

Cosmic impact versus terrestrial origin of the Azuara structure (Spain): A review     

Angel L. Corts  Enrique Díaz‐Martínez  Enrique Sanz‐Rubio  Jesús Martínez‐Frías  Cristina Fernndez 《Meteoritics & planetary science》2002,37(6):875-894

Abstract— The Azuara structure is the largest one proposed so far in Spain as possibly related to a cosmic impact event. A review of the evidence set forward in favor of and against its cosmic origin indicates that the discussion is not yet finished. Some megascopic features (inverted stratigraphy, megabreccia, negative gravity anomalies) and shock‐metamorphic effects (planar deformational features) have been described in relation with the structure, although their real significance has been questioned and is still being debated. Comparison with other similar‐sized verified impacts suggests that unequivocal impactogenic features are yet to be found before the Azuara structure can be related to a cosmic impact. Until then, the Azuara structure should be considered as an unverified impact structure, and should not be included in global comprehensive maps of terrestrial impact structures.  相似文献   

Evaluating Duero's basin (Spain) response to the NAO phases: spatial and seasonal variability     

Enrique Morán‐Tejeda  López‐Moreno Ignacio  Ceballos‐Barbancho Antonio  Vicente‐Serrano Sergio M. 《水文研究》2011,25(8):1313-1326

In this study, we analysed the influence of the North Atlantic Oscillation (NAO) on the hydrological response of the Duero River (central Spain) and its tributaries. We identified the positive and negative phases of the winter NAO for the period 1961–2006 and related precipitation and river discharge anomalies. Significant differences in precipitation and river discharge were found between the positive and negative NAO phases with negative anomalies (dry conditions) during positive NAO periods, and positive anomalies (wet conditions) during negative NAO periods. Marked differences were also found in the precipitation and river discharge response times to the NAO episodes, with an immediate response for precipitation but a lag and more sustained response for river discharges. Differing patterns were also identified in the response of river discharge to the NAO throughout the Duero basin. The physical characteristics of watersheds (including area, altitude and permeability explained most of the differences in the timing and magnitude of anomalies in the river discharge in response to the NAO. The findings highlight the great variability in the hydrological response of rivers to the NAO episodes. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Building a VO-compliant Radio Astronomical DAta Model for Single-dish radio telescopes (RADAMS)     

Juan de Dios Santander-Vela  Emilio García  Stephane Leon  Victor Espigares  José Enrique Ruiz  Lourdes Verdes-Montenegro  Enrique Solano 《Experimental Astronomy》2012,34(3):623-652

The Virtual Observatory (VO) is becoming the de-facto standard for astronomical data publication. However, the number of radio astronomical archives is still low in general, and even lower is the number of radio astronomical data available through the VO. In order to facilitate the building of new radio astronomical archives, easing at the same time their interoperability with VO framework, we have developed a VO-compliant data model which provides interoperable data semantics for radio data. That model, which we call the Radio Astronomical DAta Model for Single-dish (RADAMS) has been built using standards of (and recommendations from) the International Virtual Observatory Alliance (IVOA). This article describes the RADAMS and its components, including archived entities and their relationships to VO metadata. We show that by using IVOA principles and concepts, the effort needed for both the development of the archives and their VO compatibility has been lowered, and the joint development of two radio astronomical archives have been possible. We plan to adapt RADAMS to be able to deal with interferometry data in the future.  相似文献   

Monte Carlo simulations of radio pulses in atmospheric showers using ZHAireS     

Jaime Alvarez-Muñiz  Washington R. Carvalho Jr.Enrique Zas 《Astroparticle Physics》2012,35(6):325-341

We present predictions for the radio pulses emitted by extensive air showers using ZHAireS, an AIRES-based Monte Carlo code that takes into account the full complexity of ultra-high energy cosmic-ray induced shower development in the atmosphere, and allows the calculation of the electric field in both the time and frequency domains. We do not presuppose any emission mechanism and our results are compatible with a superposition of geomagnetic and charge excess radio emission effects. We investigate the polarization of the electric field as well as the effects of the refractive index n and shower geometry on the radio pulses. We show that geometry, coupled to the relativistic effects that appear when using a realistic refractive index n > 1, play a prominent role on the radio emission of air showers.  相似文献   

Clustering of luminous red galaxies – I. Large-scale redshift-space distortions     

Anna Cabré  Enrique Gaztañaga 《Monthly notices of the Royal Astronomical Society》2009,393(4):1183-1208

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Paleoenvironmental and paleoecological reconstruction of a freshwater oasis in savannah grassland at FLK North, Olduvai Gorge, Tanzania     

Gail M. Ashley  Doris Barboni  Manuel Dominguez-Rodrigo  Henry T. Bunn  Audax Z.P. Mabulla  Fernando Diez-Martin  Rebeca Barba  Enrique Baquedano   《Quaternary Research》2010,74(3):333-343

The records of early hominins are commonly localized both temporally and spatially even in archaeologically rich basins like Olduvai Gorge, Tanzania. The FLK North site was discovered in 1960, but the reason for the exact location of this dense concentration of fossils and stone tools on a lake-margin flat has not been explained. We present new geological and geochemical information from six excavations in upper Bed I, which revealed up to 1.4-m-thick carbonate deposits, attesting to the presence of freshwater springs in the area surrounding FLK North. The δ¹⁸O signatures of the tufa are typical for meteoric water that has evolved during evaporation. Tuff IF that caps the sequence was deposited on uneven topography with the highest area a low-relief ridge between two faults at the archaeological site and lowest areas being sites of groundwater discharge. The model proposed here is that rainfall on adjacent highlands was transported to the basin where faults acted as conduits for water. Similar hydrogeological settings at modern lakes Manyara and Eyasi, currently support lush groundwater forest and woodland despite arid climate. FLK North may have been an “oasis” offering freshwater and shelter for consuming meat by both carnivores and hominins.  相似文献   

Tsunamis and Tsunami Hazards in Central America     

Mario Fernandez  Enrique Molina  Jens Havskov  Kuvvet Atakan 《Natural Hazards》2000,22(2):91-116

A tsunami catalogue for Central America is compiledcontaining 49 tsunamis for the period 1539–1996,thirty seven of them are in the Pacific and twelve inthe Caribbean. The number of known tsunamis increaseddramatically after the middle of the nineteenth century,since 43 events occurred between 1850 and 1996. This isprobably a consequence of the lack of populationliving near the coast in earlier times.The preliminary regionalization of the earthquakessources related to reported tsunamis shows that, inthe Pacific, most events were generated by theCocos-Caribbean Subduction Zone (CO-CA). At theCaribbean side, 5 events are related with the NorthAmerican-Caribbean Plate Boundary (NA-CA) and 7 withthe North Panama Deformed Belt (NPDB).There are ten local tsunamis with a specific damagereport, seven in the Pacific and the rest in theCaribbean. The total number of casualties due to localtsunamis is less than 455 but this number could behigher. The damages reported range from coastal andship damage to destruction of small towns, and theredoes not exist a quantification of them.A preliminary empirical estimation of tsunami hazardindicates that 43% of the large earthquakes (Ms 7.0) along the Pacific Coast of Central America and100% along the Caribbean, generate tsunamis. On thePacific, the Guatemala–Nicaragua coastal segment hasa 32% probability of generating tsunamis after largeearthquakes while the probability is 67% for theCosta Rica–Panama segment. Sixty population centers onthe Pacific Coast and 44 on the Caribbean are exposedto the impact of tsunamis. This estimation alsosuggests that areas with higher tsunami potential inthe Pacific are the coasts from Nicaragua to Guatemalaand Central Costa Rica; on the Caribbean side, Golfode Honduras Zone and the coasts of Panama and CostaRica have major hazard. Earthquakes of magnitudelarger than 7 with epicenters offshore or onshore(close to the coastline) could trigger tsunamis thatwould impact those zones.  相似文献   

A modular injection system, multilevel sampler, and manifold for tracer tests   总被引：1，自引：0，他引：1  

Mailloux BJ  Fuller ME  Rose GF  Onstott TC  DeFlaun MF  Alvarez E  Hemingway C  Hallet RB  Phelps TJ  Griffin T 《Ground water》2003,41(6):816-827

Ground water injection and sampling systems were developed for bacterial transport experiments in both homogenous and heterogeneous unconsolidated, surficial aquifers. Two types of injection systems, a large single tank and a dynamic mixing tank, were designed to deliver more than 800 L of amended ground water to the aquifer over 12 hours, without altering the ground water temperature, pH, Eh, or dissolved gas composition. Two types of multilevel samplers (MLSs) were designed and installed. Permanent MLSs performed well for the homogenous surficial aquifer, but their installation procedure promoted vertical mixing, which could obfuscate experimental data obtained from vertically stratified, heterogeneous aquifers. A novel, removable MLS was designed to fit in 2- and 4-inch wells. Expandable O-rings between each sampling port hydraulically isolated each port for sample collection when a nut was tightened at the land surface. A low-cost vacuum manifold system designed to work with both MLS designs used 50 mL centrifuge tubes to efficiently sample 12 MLS ports with one peristaltic pump head. The integrated system was developed and used during four field campaigns over a period of three years. During each campaign, more than 3000 ground water samples were collected in less than one week. This system should prove particularly useful for ground water tracer, injection, and push-pull experiments that require high-frequency and/or high-density sampling.  相似文献