Re-Os Isotopic Measurements at the Femtomole Level in Natural Samples

Here we describe a new chemical separation method for Os and an improved mass spectrometric procedure for Re and Os. This technique is based on the selective extraction of OsO₄ from aqueous solution in liquid bromine. Among other advantages, this procedure avoids the cumbersome distillation procedure for Os and uses only commercial "off the shelf" PFA teflon labware. Blank levels for 0.5 g sample sizes are: 0.06 pg and 0.5 pg for Os and Re respectively. Samples containing as little as 1 pg g⁻¹ Os can be analysed reliably with this method. Adaptation to other dissolution methods is also discussed.     

Temporary labour migration and sustainable post-conflict return in Sierra Leone

Economic and social development indicators suggest that the small West African state of Sierra Leone is among the poorest countries in the world. Sierra Leone’s economy and quality of life deteriorated rapidly during a decade of political instability and civil war in the 1990s, when many people fled their homes and abandoned their livelihoods due to the rebel insurgency. This paper examines the post-war reconstruction scenario in Sierra Leone and presents recent evidence from two rural communities in the Eastern Province that were badly affected by the conflict. The paper considers the links between the farming and diamond mining sectors, which, despite severe dislocation during the conflict period, have proved to be remarkably resilient. It is argued that seasonal labour mobility associated with this dual economy has not only continued to be a key ingredient in sustaining livelihood portfolios, but is actually an essential pre-condition for the creation of an enabling environment for sustainable post-conflict return.

Utilizing the Potential of World View −2 for Discriminating Urban and Vegetation Features Using Object Based Classification Techniques

With the availability of very high resolution multispectral imagery, it is possible to identify small features in urban environment. Because of the multiscale feature and diverse composition of land cover types found within the urban environment, the production of accurate urban land cover maps from high resolution satellite imagery is a difficult task. This paper demonstrates the potential of 8 bands capability of World View 2 satellite for better automated feature extraction and discrimination studies. Multiresolution segmentation and object based classification techniques were then applied for discrimination of urban and vegetation features in a part of Dehradun, Uttarakhand, India. The study demonstrates that scale, colour, shape, compactness and smoothness have a significant influence on the quality of image objects achieved, which in turn governs the classified result. The object oriented analysis is a valid approach for analyzing high spatial and spectral resolution images. World View 2 imagery with its rich spatial and spectral information content has very high potential for discrimination of the less varied varieties of vegetation.     

Forecasting of cyclone Viyaru and Phailin by NWP-based cyclone prediction system (CPS) of IMD – an evaluation

An objective NWP-based cyclone prediction system (CPS) was implemented for the operational cyclone forecasting work over the Indian seas. The method comprises of five forecast components, namely (a) Cyclone Genesis Potential Parameter (GPP), (b) Multi-Model Ensemble (MME) technique for cyclone track prediction, (c) cyclone intensity prediction, (d) rapid intensification, and (e) predicting decaying intensity after the landfall. GPP is derived based on dynamical and thermodynamical parameters from the model output of IMD operational Global Forecast System. The MME technique for the cyclone track prediction is based on multiple linear regression technique. The predictor selected for the MME are forecast latitude and longitude positions of cyclone at 12-hr intervals up to 120 hours forecasts from five NWP models namely, IMD-GFS, IMD-WRF, NCEP-GFS, UKMO, and JMA. A statistical cyclone intensity prediction (SCIP) model for predicting 12 hourly cyclone intensity (up to 72 hours) is developed applying multiple linear regression technique. Various dynamical and thermodynamical parameters as predictors are derived from the model outputs of IMD operational Global Forecast System and these parameters are also used for the prediction of rapid intensification. For forecast of inland wind after the landfall of a cyclone, an empirical technique is developed. This paper briefly describes the forecast system CPS and evaluates the performance skill for two recent cyclones Viyaru (non-intensifying) and Phailin (rapid intensifying), converse in nature in terms of track and intensity formed over Bay of Bengal in 2013. The evaluation of performance shows that the GPP analysis at early stages of development of a low pressure system indicated the potential of the system for further intensification. The 12-hourly track forecast by MME, intensity forecast by SCIP model and rapid intensification forecasts are found to be consistent and very useful to the operational forecasters. The error statistics of the decay model shows that the model was able to predict the decaying intensity after landfall with reasonable accuracy. The performance statistics demonstrates the potential of the system for improving operational cyclone forecast service over the Indian seas.     

La vallée d'Ys : un paléoréseau hydrographique immergé en baie de Douarnenez (Finistère,France)

Interpretation of the recent high-resolution survey, CANADOU 2000, in the Bay of Douarnenez (Finistère, France) allowed us to restore the morphology of the substratum and the sedimentary filling of the bay. The Brioverian and Palaeozoic substratum reveals a well-defined network of incised valleys as results of successive emergence stages of the Bay during the Quaternary. Valleys join in a westward-widened mean valley, called Ys Valley. The present-day sedimentary fill of the bay of Douarnenez appears mainly controlled by the Holocene rise and the consecutive highstand. It comprises fluvial and estuarine deposits filling up incised valleys and marine sedimentation extending out of the incised valleys. To cite this article: G. Jouet et al., C. R. Geoscience 335 (2003).To cite this article: G. Jouet et al., C. R. Geoscience 335 (2003).     

Diurnal variation in the initiation of rainfall over the Indian subcontinent during two different monsoon seasons of 2008 and 2009

In the present study, the diurnal variations in the time of initiation of rainfall, during two contrasting monsoon seasons of 2008 (below normal) and 2009 (normal) over the Indian subcontinent and surrounding oceanic areas has been analyzed. Harmonic analysis was used to detect the spatial variation of the diurnal cycle of the time of initiation of rainfall, as obtained at half-hourly intervals from the Kalpana 1 satellite. In general, the diurnal cycle in the time of initiation is strongest in regions where convective clouds are predominant, while it is weaker in regions where the clouds are predominantly stratiform with long-lived medium to high cloud cover. In the interior of the subcontinent, the time of maximum mainly occurred in the afternoon to evening hours, with a distinct southeast to northwest gradation. Substantial spatial variations were detected in the diurnal patterns between a normal and below normal monsoon years. Spatially, rainfall is initiated later in 2009 compared to 2008 over most of the interior of the Indian subcontinent. The most distinct difference was observed over the core monsoon region in central India, where the diurnal patterns were stronger in 2009 compared to 2008. On the other hand, over the oceans surrounding the Indian subcontinent, the initiation times are generally earlier in 2009.     

When Is Asia?

Recently, in geography and related disciplines, there has been a call to generate conceptual frameworks from the Global South. Such a call does not imply cataloging the diversity and plurality of the world but rather requires new understandings of relationalities and transformations. In this article, I contribute to these ongoing endeavors by thinking from Asia. In doing so, I interpret Asia not as a bounded geographical location but instead as interconnected space. In particular, I pay attention to how such interconnections reference Asian models of development, thereby creating a politics of futurity. A study of the making of Asian futures allows a broader understanding of the renewal of development in a rearranged south–north world.     

Complex deep seismic anisotropy below the Scandinavian Mountains

Several seismological projects focused on the deep structure of the Scandinavian Mountains, in Norway and neighbouring Sweden. We use these recordings to study seismic anisotropy by analysing the birefringence of SKS and SKKS phases. These phases, which should be polarised radially, are split into an additional transverse component if they propagate through an anisotropic medium. Our results are directions Φ of the apparent fast shear wave polarisation and delay times δt between the split phases. For station KONO in Southern Norway, we find frequency-dependent Φ and δt values, indicating a depth-dependent anisotropy. Additionally, Φ and δt values vary with epicentre backazimuths in Norway, indicating a complex anisotropic structure in the crust and upper mantle. Stacking of the SKS/SKKS waveforms improves the signal-to-noise ratio along one station line and allows us to better determine the splitting parameters. A unique and complete model of the complex anisotropy cannot be obtained due to the limited observed backazimuth range. Near-surface tectonic structures correlate with the splitting pattern and thus the crust is one anisotropic layer in the region. Partly preferred orientations in the rock fabric at the surface can be correlated with Φ. Below one or more anisotropic layers must exist to explain the backazimuth- and frequency-dependent observations, as well as the long δt values (>2 s) which cannot be explained with crustal anisotropy alone. The spatial distribution of the splitting results indicates that different tectonics units, e.g. the Sveconorwegian, the Central and Northern Svecofennian and the Caledonian nappes, are each characterised by specific anisotropic signatures.     

A Dynamical Statistical Model for Prediction of a Tropical Cyclone

A dynamical statistical method is applied for operational forecasting of the Bay of Bengal tropical cyclone “Nargis” of April–May 2008. The method consists of three forecast components, namely (a) analysis of Genesis Potential Parameter (GPP) and maximum potential intensity, (b) track prediction, and (c) 12 hourly intensity prediction for forecasts up to 72 hours. The results of the study showed that GPP could provide necessary predictive signal at early stages of development on the further intensification of the low pressure system into a tropical cyclone. The landfall forecast position errors by different operational numerical models (NWP) showed landfall position errors ranging from 10 km to 150 km and landfall time error ranges from 6 hours early to 6 hours delay. The dynamical statistical model is capable to provide 12 hourly nearly realistic intensity forecasts up to 60 hours of forecast.     

Exposure history of the Torino meteorite

Abstract— We determined He, Ne, Ar, ¹⁰Be, ²⁶Al, ³⁶Cl, and ¹⁴C concentrations, as well as cosmic-ray track densities and halogen concentrations in different specimens of the H6 chondrite Torino, in order to constrain its exposure history to cosmic radiation. The Torino meteoroid had a radius of ～20 cm and travelled in interplanetary space for 2.5–10 Ma. Earlier, Torino was part of a larger body. The smallest possible precursor had a radius of 55 cm and a journey through space longer than ～65 Ma. If the first-stage exposure took place in a body with a radius of >3 m or in the parent asteroid, then it lasted nearly 300 Ma. The example of Torino shows that it is easy to underestimate first-stage exposure ages when constructing two-stage histories.