Use of three widely spread plant species from American arid regions for exploration of tin mineralizations

The ability to accumulate trace element contents of three plant species of widespread occurrence in the semi-arid regions of middle and southern South America (Larrea cuneifolia Cav., Cercidium praecox (Ruiz & Pav.) Harms, and Bulnesia retama (Gillies ex Hook. & Arn.) Griseb.) has been considered in order to determine their application to the exploration of tin mineralizations. Two of the three studied species can be considered as suitable for biogeochemical exploration (L. cuneifolia and C. praecox). Concentrations of As, Cd, and Mo reflect the known tin mineralization. L. cuneifolia and B. retama showed the highest and lowest trace element accumulation rates. Only zinc is preferentially accumulated in C. praecox. In addition, L. cuneifolia and C. praecox could be of environmental interest in As-bearing areas due to the accumulation capability for such element.     

Simulations of high-latitude spots on Jupiter: Constraints on vortex strength and the deep wind

We combine high-resolution observations of the dynamical behavior of small vortices (diameters ?5000 km) located at latitude 60°N on Jupiter with forward modeling, using the EPIC atmospheric model, to address two open questions: the dependence of the zonal winds with depth, and the strength of vortices that are too small to apply cloud tracking to their internal structure. The observed drift rates of the vortices can only be reproduced in the model when the zonal winds increase slightly with depth below the cloud tops, with a vertical shear that is less than was measured at 7°N at the southern rim of a 5-μm hotspot by the Galileo Probe Doppler Wind Experiment (DWE). This supports the idea that Jupiter's vertical shear may vary significantly with latitude. Our simulations suggest that the morphology of the mergers between vortices mainly depends on their maximum tangential velocities, the best results occurring when the tangential velocity is close to the velocity difference of the alternating jets constraining the zone in which the vortices are embedded. We use this correlation, together with the high-resolution data available for the White Ovals, to derive an empirical relationship between the maximum tangential velocity of a jovian vortex and its size, normalized by the strength and size of the encompassing shear zone. The Great Red Spot stands out as a significant anomaly to this relationship, but interestingly it is becoming less so with time.     

Non-diffusive propagation of ultra high energy cosmic rays

We report the results of 3D simulations of non-diffusive propagation of Ultra High Energy Cosmic Rays (UHECR) (E > 10²⁰ eV) through the intergalactic and extended halo media. We quantify the expected angular and temporal correlations between the events and the sources, and the temporal delay between protons and gamma-ray counterparts with a common origin for both halo and extragalactic origins. It is shown that the proposed UHECR-supergalactic plane source associations require either extremely high values of the halo magnetic field over as much as 100 kpc length scale or a very large correlation length for the IGM, even for the largest possible values of the intergalactic magnetic field. It can be stated that the UHECR seem to point to the sources even more strongly than previously believed. The simulations also show that the calculated time delays between UHE protons and gamma-ray counterparts do not match the claimed GRB-UHECR associations for either cosmological or extended halo distance scales.     

Integrated water resource management in a major canal command in eastern India

The present rice‐dominated cropping system in the Hirakud canal command (eastern India) is under severe threat due to imbalance between irrigation water supply and demand. The canal water supply, which is the only source of irrigation, only meets 54% of the demand at 90% probability of exceedance (PE). In order to mitigate the irrigation water deficit from canal water, groundwater is considered as a supplemental source. Quasi‐three‐dimensional groundwater flow simulation modelling was, therefore, carried out by using Visual MODFLOW to detect the change in hydraulic head due to transient pumping stresses. The simulation model was calibrated and validated satisfactorily. Sensitivity analysis of the model parameters shows that groundwater recharge is most sensitive followed by aquifer hydraulic conductivity at almost all the sites of the command area, whereas the model is comparatively less sensitive to specific storage and specific yield. Enhanced pumping scenarios showed that groundwater extraction can be increased up to 50 times of the existing pumping without causing any adverse effect to the aquifer but the aquifer does not permit to exploit water in order to fulfill the irrigation water demand even at 10% PE. Hence, it is imperative to develop an optimal land and water resources management plan of the command area. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of clustering and selection algorithms for the study of multivariate wave climate

Recent wave reanalysis databases require the application of techniques capable of managing huge amounts of information. In this paper, several clustering and selection algorithms: K-Means (KMA), self-organizing maps (SOM) and Maximum Dissimilarity (MDA) have been applied to analyze trivariate hourly time series of met-ocean parameters (significant wave height, mean period, and mean wave direction). A methodology has been developed to apply the aforementioned techniques to wave climate analysis, which implies data pre-processing and slight modifications in the algorithms. Results show that: a) the SOM classifies the wave climate in the relevant “wave types” projected in a bidimensional lattice, providing an easy visualization and probabilistic multidimensional analysis; b) the KMA technique correctly represents the average wave climate and can be used in several coastal applications such as longshore drift or harbor agitation; c) the MDA algorithm allows selecting a representative subset of the wave climate diversity quite suitable to be implemented in a nearshore propagation methodology.     

Focal depths and mechanisms of Tohoku-Oki aftershocks from teleseismic P wave modeling

Aftershocks of the 2011 Tohoku-Oki great earthquake have a wide range of focal depths and fault plane mechanisms. We constrain the focal depths and focal mechanisms of 69 aftershocks with M _w > 5.4 by modeling the waveforms of teleseismic P and its trailing near-surface reflections pP and sP. We find that the “thrust events” are within 10 km from the plate interface. The dip angles of these thrust events increase with depth from ~5° to ~25°. The “non-thrust events” vary from 60 km above to 40 km below the plate interface. Normal and strike-slip events within the overriding plate point to redistribution of stress following the primary great earthquake; however, due to the spatially variable stress change in the Tohoku-Oki earthquake, an understanding of how the mainshock affected the stresses that led to the aftershocks requires accurate knowledge of the aftershock location.     

The coral communities of the Islas Marias archipelago,Mexico: structure and biogeographic relevance to the Eastern Pacific

Various authors have suggested that the Islas Marias archipelago, Mexico, may play a significant biogeographic role in the dispersal of Indo Pacific coral species into the Eastern Pacific; however, the coral communities of this archipelago have received scarce attention to date. Here, we first addressed coral community structure across the islands and, by employing ordination analysis, minimum spanning tree and particle‐tracking experiments, used this information to evaluate the relevance of the archipelago for coral dispersal. Twenty‐four coral communities were recorded in the archipelago. Coral cover varied significantly among islands: Maria Cleofas had large values (38.5%), intermediate values were observed for Maria Madre (26.5%) and Maria Magdalena (22.84%), and relatively low values were recorded for San Juanito (18.5%). Coral communities mainly consisted of Pocillopora (57.3%) and Porites (25.5%) species, while species of Pavona (16%) and Psammocora (0.6%) made relatively minor contributions. Thirteen stony coral species were identified in the archipelago; of these Psammocora profundacella and Pavona duerdeni represent new records. Ordination analysis, minimum spanning tree and particle‐tracking experiments suggested similar connecting paths in the studied area; in general, the Islas Marias stands as a route for coral dispersal of Indo Pacific species into the Northeastern Pacific. In a regional context, the Islas Marias has three major biogeographic implications to coral dispersal: (i) the archipelago stands as a major stepping stone for the transport of species and individuals among the Revillagigedo archipelago, the Gulf of California and the tropical Mexican Pacific; (ii) the Islas Marias may play a seminal role in maintaining the genetic connectivity between southern and northern coral populations along the Mexican Pacific and (iii) because of its relatively pristine status and low levels of human impact, the archipelago may potentially serve as a source of coral propagules for ecosystem recovery in the Gulf of California and along the Pacific coast of the Mexican mainland following natural and/or human induced perturbations.     

Particle-size effects on dissolved arsenic adsorption to an Australian laterite

In this study, arsenic adsorption to an Australian laterite has been examined for a particle-size range between 38 μm and 25 mm. The results show that particle size influences both kinetic and equilibrium characteristics of arsenic adsorption. The equilibrium adsorption capacity increases from around 100 mg kg^?1 for laterite particles coarser than 4 mm, to around 160 mg kg^?1 for laterite particles between 75 μm and 4 mm, and to over 200 mg kg^?1 for laterite particles finer than 75 μm. The kinetic adsorption data can be fitted with the pseudo-second-order reaction model, in particular for finer particles where the film diffusion and/or surface reaction are important processes. The model-fitted rate constant remains steady for laterite particles coarser than 2 mm, increases moderately with particle size in the range between 75 μm and 2 mm, and increases dramatically for laterite particles finer than 75 μm. These arsenic adsorption behaviours can be explained by the relative importance of two particle-size-dependent processes: quick external-surface adsorption (more important for fine particles) and slow intraparticle adsorption (more important for coarse particles). Most of the external-surface adsorption completes in the first hour of the experiment. To apply the studied laterite for dissolved arsenic removal, it is recommended that fine particles, in particular finer than 75 μm, should be used if the contact time is the limitation, and that coarse particles, in particular 2–4 mm, should be used if sufficient contact time is available.     

Variations in the dynamic response of structures founded on piles induced by obliquely incident SV waves

Although the seismic actions generally consist of a combination of waves, which propagates with an angle of incidence not necessarily vertical, the common practice when analyzing the dynamic behavior of pile groups is based on the assumption of vertically incident wave fields. The aim of this paper is to analyze how the angle of incidence of SV waves affects the dynamic response of pile foundations and piled structures. A three-dimensional boundary element-finite element coupling formulation is used to compute impedances and kinematic interaction factors corresponding to several configurations of vertical pile groups embedded in an isotropic homogeneous linear viscoelastic half-space. These results, which are provided in ready-to-use dimensionless graphs, are used to determine the effective dynamic properties of an equivalent single-degree-of-freedom oscillator that reproduces, within the range where the peak response occurs, the response of slender and nonslender superstructures through a procedure based on a substructuring model. Results are expressed in terms of effective flexible-base period and damping as well as maximum shear force at the base of the structure. The relevance and main trends observed in the influence of the wavefront angle of incidence on the dynamic behavior of the superstructure are inferred from the presented results. It is found that effective damping is significantly affected by the variations of the wave angle of incidence. Furthermore, it comes out that the vertical incidence is not always the worst-case scenario.