A methodology for spatially representing the likelihood of occurrence of natural contaminants in groundwater

This paper presents a novel method of spatially representing the likelihood of occurrence of a contaminant in groundwater at the scale of a municipality or watershed. The specific contaminant of concern in the case study area is arsenic, which is variably present in groundwater at concentrations exceeding the 10 µg/l drinking water guideline. The method used to produce the likelihood of occurrence map incorporates confidence of geochemical interpretation based on availability of information and data on each aquifer. While demonstrated using arsenic as the contaminant of interest, the approach is readily adapted to other groundwater constituents. The final map is intended to be of use to water managers as it provides a spatial representation of aquifers of concern and identifies areas where further sampling or monitoring may be needed.     

Hazard analysis of seismic submarine slope instability

To assess the risk associated with a submarine landslide, one must estimate the probability of slope failure and its consequences. This paper proposes a procedure to estimate the probability of earthquake-induced submarine slope failure (hazard) based on probabilistic seismic hazard analyses, ground response analyses and advanced laboratory tests. The outcomes from these analyses are treated in a probabilistic framework, with analytical simulations using mathematical techniques such as the first-order reliability method, Monte Carlo simulation and Bayesian updating. Fragility curves of slope failure during the earthquake (co-seismic) and after the earthquake (post-seismic) were developed in this study, and were shown to provide a clear and well-organized procedure to estimate the annual failure probability of a submarine slope under earthquake loading.     

Investigation of Shuttle Radar Topography Mission data of the possible impact structure at Serra da Cangalha,Brazil

Abstract— The Serra da Cangalha crater structure in northeast Brazil, ?13 km in diameter, has long been widely considered to be a confirmed impact structure, based on reports of shatter cone findings. Only very limited field work has been carried out at this crater structure. Landsat Thematic Mapper (TM) and Shuttle Radar Topography Mission (SRTM) data sets for the region around this crater structure are compared here with regard to their suitability to determine first‐order structural detail of impact crater structures. The SRTM data provide very detailed information regarding drainage patterns and topography. A pronounced central ring of up to 300 m elevation above the surrounding area, two comparatively subdued intermediate rings of 6 and 10.5 km diameter, respectively, and the broad, complex crater rim of up to >100 m elevation can be distinguished in the Serra da Cangalha data. The maximum cratering‐related regional deformation (radial and concentric features) seems to be limited to a radial distance of 16–18 km from the center of the structure. A first comparison of macrostructural information from several impact structures with that from Serra da Cangalha does not yield firm trends, but the database is still very small at this stage. The varied nature of the target geology strongly influences the development of structural features in any impact event.     

On the construction of dynamic systems from given integrals

In this communication we propose a new approach for studying a particular type of inverse problems in mechanics related to the construction of a force field from given integrals.An extension of the Danielli problem is obtained. The given results are applied to the Suslov problem, and illustrated in specific examples.     

Climatic natural disasters,political risk,and international trade

This paper statistically analyzes the effects of climatic natural disasters and political risk on bilateral trade in a large-N sample of countries and years. Our theory suggests that the effects of these forces on trade need to be studied together and that the two forces may interact with one another. In the statistical analysis, the unit of analysis is a pair of countries and the model is based on the trade gravity design. The results show that the direct effects of increases in the incidence of disasters and the political risk level in the importer or the exporter countries are negative, reducing trade. The results for the interaction between the two forces show (1) as the incidence of disasters increases, the marginal effect of political risk on trade becomes more negative, which indicates a greater decline in trade and (2) as political risk declines the marginal effect of disasters becomes less negative, indicating a smaller decline in trade. Additional analyses demonstrate the robustness of these results to changes in model specification, disaster measure, and estimation method. In the bigger picture, our findings suggest that if climate change increases the incidence of climatic disasters as projections of the global science suggest, the growth of economic globalization may decline, ceteris paribus.     

Lake‐level changes in central Patagonia (Argentina): crossing environmental thresholds for Lateglacial and Holocene human occupation

The role and extent of climate as a cause of the expansion and decline of human cultures is still debatable. It is clear, however, that human–environment interactions are enhanced and interplay more closely in climatically sensitive areas such as around hydrologically closed basins. Lago Cardiel is located at 49° S in the very arid rain shadow east of the Andes, providing an exceptionally receptive system to changes in hydrological balance. Results of a geophysical survey combined with sedimentological and geochemical studies provide a continuous Lateglacial–Holocene record of substantial water‐level changes. These variations, combined with archaeological results from the catchment area, offer a unique possibility to explore the pattern of peopling within this remote area of the globe and its possible relation to climate change. Human occupation in Patagonia is well documented towards the Andes throughout the entire Holocene. Archaeological data from the Lago Cardiel basin, however, show an apparent lack of human activity during the first part of this period, which coincides with well‐constrained high lake levels. Our results show an intriguing coincidence between low lake level and increasing human occupation, suggesting that the Lago Cardiel basin has focused human use during intervals with relatively lower effective moisture such as during the Late Pleistocene, but its evidence may have been submerged. This interpretation is confirmed by archaeological remains from Lago Strobel, another perennial lake with a comparable catchment located in the same climatic region and thus sharing the same climatic history as Lago Cardiel. Copyright © 2009 John Wiley & Sons, Ltd.     

Some analytical results about periodic orbits in the restricted three body problem with dissipation

We present some analytical results about the existence of periodic orbits for the planar restricted three body problem with dissipation considered recently by Celletti et?al. (CMDA 109, 265, 2011) We show that, under fairly general conditions on the dissipation term, the circular orbits cannot be continued to the dissipative framework. Moreover, we give general conditions for the occurrence or not of a Hopf bifurcation around the libration points L ₄ and L ₅. Our results are consistent with the numerical findings of Celletti et?al.     

The brightening of Saturn’s F ring

Image photometry reveals that the F ring is approximately twice as bright during the Cassini tour as it was during the Voyager flybys of 1980 and 1981. It is also three times as wide and has a higher integrated optical depth. We have performed photometric measurements of more than 4800 images of Saturn’s F ring taken over a 5-year period with Cassini’s Narrow Angle Camera. We show that the ring is not optically thin in many observing geometries and apply a photometric model based on single-scattering in the presence of shadowing and obscuration, deriving a mean effective optical depth τ ≈ 0.033. Stellar occultation data from Voyager PPS and Cassini VIMS validate both the optical depth and the width measurements. In contrast to this decades-scale change, the baseline properties of the F ring have not changed significantly from 2004 to 2009. However, we have investigated one major, bright feature that appeared in the ring in late 2006. This transient feature increased the ring’s overall mean brightness by 84% and decayed with a half-life of 91 days.