The role of afterglow break-times as gamma-ray burst jet angle indicators     

L. Nava  G. Ghisellini  G. Ghirlanda  J. I. Cabrera  C. Firmani  V. Avila-Reese 《Monthly notices of the Royal Astronomical Society》2007,377(4):1464-1472

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Un exemple de volcanisme calco-alcalin de type orogénique mis en place en contexte de rifting (Cambrien de l'oued Rhebar,Meseta occidentale,Maroc)     

Hassan El Hadi  Abdelfatah Tahiri  Fernando Simancas Cabrera  Francisco González Lodeiro  Antonio Azor Pérez  David Jesús Martínez Poyatos 《Comptes Rendus Geoscience》2006,338(4):229-236

The Middle Cambrian calc-alkaline Oued Rhebar volcanic complex (western Meseta, Morocco) compares with rocks originated in orogenic contexts. The La/Nb ratios are relatively high (5.2), suggesting a lithospheric mantle origin. The La/Ta ratios, higher than 26, and the negative Nb anomaly indicate a lithospheric source contaminated by the continental crust. These rocks were generated in the Mesetian Mid-Cambrian rift and would have inherited their orogenic signature from the partial melting of a previously metasomatized mantle. To cite this article: H. El Hadi et al., C. R. Geoscience 338 (2006).  相似文献   

Nutrient inputs from submarine groundwater discharge on the Santiago reef flat, Bolinao, Northwestern Philippines     

Senal MI  Jacinto GS  San Diego-McGlone ML  Siringan F  Zamora P  Soria L  Cardenas MB  Villanoy C  Cabrera O 《Marine pollution bulletin》2011,63(5-12):195-200

Submarine groundwater discharge (SGD) on the reef flat of Bolinao, Pangasinan (Philippines) was mapped using electrical resistivity, 222Rn, and nutrient concentration measurements. Nitrate levels as high as 126 μM, or 1-2 orders of magnitude higher than ambient concentrations, were measured in some areas of the reef flat. Nutrient fluxes were higher during the wet season (May-October) than the dry season (November-April). Dissolved inorganic nitrogen (DIN=NO3+NO2+NH4) and soluble reactive phosphorus (SRP) fluxes during the wet season were 4.4 and 0.2 mmoles m(-2) d(-1), respectively. With the increase population size and anthropogenic activities in Bolinao, an enhancement of SGD-derived nitrogen levels is likely. This could lead to eutrophic conditions in the otherwise oligotrophic waters surrounding the Santiago reef flat.  相似文献   

Dark Matter: A Result of nonadditive gravitational forces     

Jesús Arturo Robles-Gutiérrez  Ernesto Lacomba Zamora  Jesús Martiniano Arturo Robles-Domínguez  Cinna Lomnitz  María Eugenia Robles-Gutiérrez 《Geofísica Internacional》2013,52(2):153-157

Experimental data in fluids suggest that nonadditive electromagnetic forces between 3 or more molecules account for the existence of critical points, triple states and phase transitions (Robles-Domínguez et al., 2007; Robles-Gutiérrez et al., 2010). Similar nonadditive forces between 3 or more molecules in the gravitational field incorporated into Newton’s universal gravitational law may also explain the existence of dark matter.  相似文献   

Tracing interactions between natural argillites and hyper-alkaline fluids from engineered cement paste and concrete: Chemical and isotopic monitoring of a 15-years old deep-disposal analogue     

I. Techer  D. Bartier  Ph. Boulvais  E. Tinseau  K. Suchorski  J. Cabrera  A. Dauzères 《Applied Geochemistry》2012

Samples of Toarcian argillite were collected both next to and far from a CEM II cement paste and a CEM II concrete, within the specific context of a 15-a old borehole located in the Tournemire Experimental Platform (Aveyron, France). The objectives were evaluation of the mineralogical and geochemical changes of the claystone at the contact with the cementitious materials and determination of the spatial extent of the interactions. The approach includes the examination of the mineralogical (XRD, SEM, TEM), chemical (major, trace, rare earth elements) and isotopic (Sr, C, O) compositions of argillite whole-rocks and of various soluble phases, at two scales: in the rock matrix (P1 scale) and along micro-cracks (P2 scale). The two study scales outline nearly similar mineralogical modifications, shown by the presence of Ca silicate hydrates (C–S–H) and newly-formed CaCO₃ within 10–15 mm of the cement paste and concrete. Chemical data from whole-rock argillites indicate few changes in a slightly thicker zone (18–20 mm), mainly consisting of an increase in the CaO wt.%, and a decrease in Sr contents. The other elementary contents remained quite constant except for MgO, which suggests redistribution with precipitation of a Mg-rich mineral phase at 20 mm from cement paste/concrete interface. Acetic acid leachates had more pronounced variations, including a decrease of the total elementary content in the same ‘geochemical disturbed zone’ (GDZ), together with a significant increase of the Sr isotopic ratios. A combination of Sr and C/O isotopic patterns was used to distinguish the behavior of secondary cementitious phases in the clay-rich rock: (i) calcite dissolution and re-precipitation is supported by C/O isotopic data and (ii) C–S–H neoformation is evidenced by the ⁸⁷Sr/⁸⁶Sr ratios; this tool also contributes to determine the origin of the fluids. The proportion of newly-formed C–S–H in the matrix and in the micro-cracks of the argillite is modeled.  相似文献   

Theoretical analysis and simulation for avoiding antenna oscillations without distributed resistance     

Gonzalo Garcia  Jos A. Uribe  David Ulloa  Rodrigo Zamora  Gino Casassa 《Journal of Applied Geophysics》2009,67(4):374

The so-called Wu and King antenna pattern is widely used in GPR because of its simple design and construction features. The main disadvantage is its limited efficiency due to transmitter energy losses which occur through lumped resistors. Based on the analysis of the electromagnetic field behaviour across the antenna, it is possible to replace the effect of the resistors by either storing the energy of the electric pulses, or damp them by means of one matched resistor, which will theoretically improve the efficiency of the antenna. In this paper we provide a theoretical analysis using a modified transmission line model together with simulation based on delayed potentials among other electromagnetic software, and measurement results using an impulse transmitter with fast MOSFET switches and a matched resistor that support this idea.  相似文献   

Ability of High-Resolution Resistivity Tomography to Detect Fault and Fracture Zones: Application to the Tournemire Experimental Platform,France     

C. Gélis  M. Noble  J. Cabrera  S. Penz  H. Chauris  E. M. Cushing 《Pure and Applied Geophysics》2016,173(2):573-589

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Coastal pollution due to increasing nutrient flux in aquaculture sites     

C. P. C. David  Y. Y. Sta. Maria  F. P. Siringan  J. M. Reotita  P. B. Zamora  C. L. Villanoy  E. Z. Sombrito  R. V. Azanza 《Environmental Geology》2009,58(2):447-454

The supply of nitrogen and phosphorus in coastal zones through time is reflected in the nutrients’ concentration in the sediment record. Five aquaculture sites in the Philippines were investigated in an effort to establish how long-term changes in land and coastal water use could have led to biogeochemical modifications affecting the coastal ecosystem. Samples from study sites show a narrow concentration range for nitrogen and did not reveal any significant trend through time. In contrast, phosphorus concentrations in most sites start at less than 20 ppm in sediments 30 years and older. The phosphorus value continuously increase in younger sediments, with each site having a different magnitude change as well as timing of when the major increase happened. The uppermost 10 cm, representing the last 15 years in sites with age control, typically show a 2- to 3-fold increase in P load values. Historical increase in nutrient load also coincides with harmful algal bloom events in each area; when effective P input exceeded 130 kg/km² per year. Lastly, the observed increase may be attributed to several factors including physical attributes of the area, urbanization of coastal zones, but most importantly in the proliferation of aquaculture activities.  相似文献   

A hybrid deterministic and stochastic approach for tsunami hazard assessment in Iquique,Chile     

González  Juan  González  Gabriel  Aránguiz  Rafael  Melgar  Diego  Zamora  Natalia  Shrivastava  Mahesh N.  Das  Ranjit  Catalán  Patricio A.  Cienfuegos  Rodrigo 《Natural Hazards》2020,101(1):231-253

Natural Hazards - This paper presents an investigation of the collapse of a 325-year-old multi-tiered heritage temple during the 2015 Gorkha earthquake in Kathmandu, Nepal. The research comprises a...  相似文献   

Laboratory study of self-potential signals during releasing of CO₂ and N₂ plumes     

Cristian Vieira  Alexis MaineultMaria Zamora 《Comptes Rendus Geoscience》2012,344(10):498-507

Carbon Capture Sequestration (CCS) projects require, for safety reasons, monitoring programmes focused on surveying gas leakage on the surface. Generally, these programmes include detection of chemical tracers that, once on the surface, could be associated with CO₂ degassing. We take a different approach by analysing feasibility of applying electrical surface techniques, specifically Self-Potential. A laboratory-scale model, using water-sand, was built for simulating a leakage scenario being monitored with non-polarisable electrodes. Electrical potentials were measured before, during and after gas injection (CO₂ and N₂) to determine if gas leakage is detectable. Variations of settings were done for assessing how the electrical potentials changed according to size of electrodes, distance from electrodes to the gas source, and type of gas. Results indicated that a degassing event is indeed detectable on electrodes located above injection source. Although the amount of gas could not be quantified from signals, injection timespan and increasing of injection rate were identified. Even though conditions of experiments were highly controlled contrasting to those usually found at field scale, we project that Self-Potential is a promising tool for detecting CO₂ leakage if electrodes are properly placed.  相似文献