bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phylogeny of the clusioid clade (Malpighiales): Evidence from the plastid and mitochondrial genomes
Authors: Ruhfel Brad R. , Bittrich Volker , Bove Claudia P. , Gustafsson Mats H. G. , Philbrick C. Thomas , Rutishauser Rolf , Xi Zhenxiang , Davis Charles C. 
Published: January 2011

• Premise of the study: The clusioid clade includes five families (i.e., Bonnetiaceae, Calophyllaceae, Clusiaceae s.s., Hypericaceae, and Podostemaceae) represented by 94 genera and ∼1900 species. Species in this clade form a conspicuous element of tropical forests worldwide and are important in horticulture, timber production, and pharmacology. We conducted a taxon‐rich multigene phylogenetic analysis of the clusioids to clarify phylogenetic relationships in this clade.• Methods: We analyzed plastid (matK, ndhF, and rbcL) and mitochondrial (matR) nucleotide sequence data using parsimony, maximum likelihood, and Bayesian inference. Our combined data set included 194 species representing all major clusioid subclades, plus numerous species spanning the taxonomic, morphological, and biogeographic breadth of the clusioid clade.• Key results: Our results indicate that Tovomita (Clusiaceae s.s.), Harungana and Hypericum (Hypericaceae), and Ledermanniella s.s. and Zeylanidium (Podostemaceae) are not monophyletic. In addition, we place four genera that have not been included in any previous molecular study: Ceratolacis, Diamantina, and Griffithella (Podostemaceae), and Santomasia (Hypericaceae). Finally, our results indicate that Lianthus, Santomasia, Thornea, and Triadenum can be safely merged into Hypericum (Hypericaceae).• Conclusions: We present the first well‐resolved, taxon‐rich phylogeny of the clusioid clade. Taxon sampling and resolution within the clade are greatly improved compared to previous studies and provide a strong basis for improving the classification of the group. In addition, our phylogeny will form the foundation for our future work investigating the biogeography of tropical angiosperms that exhibit Gondwanan distributions.
L'intégration monétaire en Afrique : particularités et rationalité économique
Authors: Musungaie André Nyembwe 
Published: January 2011

Résumé Nous décrivons les zones monétaires existantes et passons en revue les projets d’intégration monétaire en cours en Afrique avec en toile de fond l’étude de la rationalité économique de cette intégration. Nous présentons aussi les arguments qui font l’attrait des zones monétaires à la lumière notamment des effets de la crise financière internationale sur l’inflation, particulièrement en Afrique subsaharienne. Codes JEL : F33, F36
Moving source profile data processing, modelling and comparison with 3D surface seismic data at the CO2SINK project site, ketzin, Germany
Authors: Yang Can , Juhlin Christopher , Enescu Nicoleta , Cosma Calin , Ltith Stefan 
Published: January 2011

ABSTRACTBaseline moving source profiling data were acquired in borehole Ketzin 202/2007 along seven lines at the Ketzin CO2 injection site in 2007. The data were recorded on eight three‐component receivers spaced 10 m apart over a depth interval of 470–540 m. The main objective of the moving source profile survey was to generate high‐resolution seismic images around the borehole. This was especially important given that the 3D surface seismic data in the area have a low fold at the injection site. Mapping of the sandy layers in the target formation (Stuttgart Formation) at around 630 m, the approximate CO2 injection depth, was another objective of the research. A comparison with repeat moving source profile surveys, during and after the injection, will be done in the future. A processing sequence consisting in hodogram analysis, wavefield separation and prestack migration was applied to the moving source profile data. A median filter was used to separate the downgoing and upgoing wave modes. The data were processed to generate depth migrated images in the vicinity of the borehole that could be compared with the 3D surface seismic data. Both the modelling studies that were carried out and the migrated images, indicate that the sandy layers within the Stuttgart Formation can potentially be imaged in the moving source profile data whereas reflections from these layers are not as clearly observed in the 3D surface seismic data.
Integrated inversion of TEM and seismic data facilitated by high penetration depths of a segmented receiver setup
Authors: Nyboe Nicklas S. , Jørgensen Flemming , Sørensen Kurt 
Published: January 2011

ABSTRACTResearch aimed at improving and developing methods for noise reduction in the transient electromagnetic method (TEM) has resulted in an alternative strategy for performing TEM measurements called the segmented receiver coil setup. The measurement strategy involves the simultaneous use of two receiver coils and the resulting TEM data sets have demonstrated signal‐to‐noise ratio improvements of up to a factor of 25 when compared to the traditional setup. This significant improvement has opened up new opportunities for deeper penetration and hence an enhanced integrated inversion with seismic data sets. A case study is presented in which the segmented receiver coil setup is employed in the western part of Denmark. Previous geophysical investigations performed in the same area include multi‐channel reflection seismic measurements and SkyTEM measurements performed with an early version of the SkyTEM instrument having a limited depth of investigation. Deep structures recognized in the seismic data therefore remained unresolved in the SkyTEM data. Notably the elevation of the highly conductive Palaeogene clay, expected to be encountered at approximately 300 m depth in the area, has not been determined by the use of SkyTEM data. With the increased signal‐to‐noise ratio of the segmented receiver coil setup it is possible to resolve resistivity changes to greater depth and thus to achieve an enhanced integrated inversion together with the seismic data. The geological setting between depths of 200–300 m, which is effectively only mapped two‐dimensionally along seismic lines, can be mapped three‐dimensionally using the segmented receiver coil setup. In order to obtain the most reliable geological information, from the TEM data individual soundings are inverted in 1D utilizing the seismic data as a priori information thereby optimizing every single inversion model setup to the local sedimentary stratification. Ultimately, the larger penetration depth is the key to an improved geological understanding of the study area, because the integrated interpretation of seismic and TEM data sets yields valuable lithological and structural information that cannot be resolved by either data type alone.
Estimation of inelastic seismic material properties of a surficial sea‐bed from multi‐component marine seismic data
Authors: Eggenberger Kurt , Muijs Remco , Robertsson Johan , van Manen Dirk‐Jan , Holliger Klaus 
Published: January 2011

ABSTRACTTo date, state‐of‐the‐art seismic material parameter estimates from multi‐component sea‐bed seismic data are based on the assumption that the sea‐bed consists of a fully elastic half‐space. In reality, however, the shallow sea‐bed generally consists of soft, unconsolidated sediments that are characterized by strong to very strong seismic attenuation. To explore the potential implications, we apply a state‐of‐the‐art elastic decomposition algorithm to synthetic data for a range of canonical sea‐bed models consisting of a viscoelastic half‐space of varying attenuation. We find that in the presence of strong seismic attenuation, as quantified by ‐values of 10 or less, significant errors arise in the conventional elastic estimation of seismic properties. Tests on synthetic data indicate that these errors can be largely avoided by accounting for the inherent attenuation of the seafloor when estimating the seismic parameters. This can be achieved by replacing the real‐valued expressions for the elastic moduli in the governing equations in the parameter estimation by their complex‐valued viscoelastic equivalents. The practical application of our parameter procedure yields realistic estimates of the elastic seismic material properties of the shallow sea‐bed, while the corresponding ‐estimates seem to be biased towards too low values, particularly for S‐waves. Given that the estimation of inelastic material parameters is notoriously difficult, particularly in the immediate vicinity of the sea‐bed, this is expected to be of interest and importance for civil and ocean engineering purposes.
Automation of the SLUTH method: a novel approach to airborne magnetic data interpretation
Authors: Ulla Joshua , Smith Richard , Samson Claire , Vallée Marc 
Published: January 2011

ABSTRACTA useful property of the anomalous magnetic field associated with some simple geological bodies is that the field is homogeneous with respect to horizontal distance and height. Its horizontal and vertical derivatives are also homogeneous fields so the angle ratio of the lateral gradient over the vertical gradient is constant along rays emanating outward from a single point that represents the body location. Hence drawing these raypaths, which connect the same values at different upward continued heights along a profile, can be used to identify the location and depth of the source. This is the basis for the source location using the total‐field homogeneity (SLUTH) method. A six‐step procedure is proposed to automate the SLUTH method, allowing large amounts of data to be interpreted quickly and easily. Furthermore, the rate of decay of the field along these raypaths provides a means to estimate the type of body that is the cause of the anomaly. Once the type of body is known, a quantity related to the susceptibility can be estimated.An analysis of the results in the case when there is interaction between two proximal magnetic sheets shows a distortion when the bodies are within 600 m of each other. A similar distortion is seen when analysing field data from Timmins, Ontario, Canada, which consists of many other magnetic body models such as contacts and thin sheets. Adding noise to synthetic data shows that the estimates we obtain for the source parameters are robust for the typical noise levels seen in survey data.Because a lot of information about the characteristics of the causative geologic body can be determined using the method, it is a challenge to summarize the results on a single map. Our approach is to use different shaped symbols for each type of body, with the size of the symbol being proportional to the susceptibility‐thickness and the shade indicative of the error in estimating the position. Data from Chibougamau, Quebec, Canada are used to illustrate these display techniques.
Self‐potential signatures associated with an injection experiment at an in situ biological permeable reactive barrier
Authors: Davis Caroline A. , Slater Lee D. , Kulessa Bernd , Ferguson Andrew S. , Atekwana Estella A. , Doherty Rory , Kalin Robert 
Published: January 2011

ABSTRACTStrategies available to evaluate the performance of in situ permeable reactive barriers are currently not well developed and often rely on fluid and media sampling directly from the permeable reactive barrier (PRB). Here, we investigate the utility of the self‐potential method as a technique to monitor in situ PRB performance. Our field study was conducted at in situ biological PRB in Portadown, Northern Ireland, UK, which was emplaced to assist in the remediation of groundwater contamination (e.g., hydrocarbons, ammonia) that resulted from the operations and waste disposal practices of a former gasworks. Borehole measurements were collected during the injection of contaminant groundwater slugs in an attempt to monitor/detect the response of the microbial activity associated with the breakdown of the added contaminants into the PRB. In addition, an uncontaminated groundwater slug was injected into a different portion of the PRB as a ‘control’ and measurements were collected for comparison to the response of the contaminant slugs. The results of the SP signals due to the contaminant injections show that the magnitude of the response was relatively small (<10 mV) yet showed a consistent decrease during both contaminant injections. The net decrease in recorded during the contaminant injections slowly rebounded to near background values through ~44 hours post‐injection. The response during the uncontaminated injection showed a slight, albeit negligible (within the margin of error), 1 mV increase in the measured signals, in contrast to the contaminant injections. The results of the signals recorded from the uncontaminated groundwater injection also persisted through a period of ~47 hours after injection but show a net increase in relative to pre‐injection values. Based on the difference in response between the contaminated and uncontaminated injections, we suggest that the responses are likely to be the result of differences in the chemistry of the injection types (contaminated versus uncontaminated) and in situ groundwater. We argue that the signals associated with the contaminated injections are dominated by diffusion (electrochemical) potential, possibly enhanced by a microbial effect. While the results of our investigation show a consistent response associated with the contaminant injections that is dominated by diffusional effects, further studies are required in order to better understand the effect of microbial activity on signals and the potential utility for the method to detect/monitor changes that may be indicative of biological PRB performance.
Geophysical characterization of riverbed hydrostratigraphy using electrical resistance tomography
Authors: Clifford Jeremy , Binley Andrew 
Published: January 2011

ABSTRACTThe subsurface structure of a riverbed can play an important role in groundwater‐surface water interactions. Knowledge of this structure provides a basis for characterizing the physical and geochemical processes in this region, for example, how hydrostratigraphy relates to groundwater seeps or controls the transport of nutrients across this critical interface. However, characterization of riverbed sediments using conventional hydrological techniques is difficult and particularly challenging for assessing contiguous units of variable geometry. Also, the destructive nature of conventional drilling in a riverbed is often problematic in some systems because of the disturbance to the ecosystem it supports. Geophysical techniques may provide significant advantages over conventional characterization techniques, provided i) there exists a distinct contrast in the geophysical properties of hydrological units and ii) sufficient resolution and sensitivity to these contrasts can be achieved. We show, through modelling and field application, how electrical resistivity tomography can be used to provide useful knowledge about shallow hydrostratigraphy of riverbed environments. Through synthetic modelling, we show that the main factor affecting sensitivity below the surface water/subsurface interface is the ratio of electrical conductivities of surface water and sub‐strata. The modelling reveals that as this ratio increases, the sensitivity shifts upward across the interface, reducing the information yielded from below the riverbed. We also show that this, coupled with the variability in the riverbed topography and composition, has the effect of rendering conventional data coverage from short arrays unusable. With suitable selection of electrode configuration and measurement scheme, informative results are, however, achievable. We report on a field trial applied to the River Leith, a small groundwater‐fed stream in the Eden Valley of Cumbria, UK. The effect of the depth of the water column is shown and although the depth of investigation is relatively shallow, enough structure is revealed to show the boundary between the sandstone aquifer and overlying alluvial sediments. Our findings from model and field studies suggest that electrical geophysical methods could have a valuable role complementing conventional measurements in shallow hydrogeological characterization studies.
Quantifying field‐scale surface soil water content from proximal GPR signal inversion in the time domain
Authors: Jadoon Khan Zaib , Lambot Sébastien , Scharnagl Benedikt , van der Kruk Jan , Slob Evert , Vereecken Harry 
Published: January 2011

ABSTRACTWe applied inverse modelling of zero‐offset, air‐raised ground‐penetrating radar (GPR) data to measure soil surface water contents over a bare agricultural field. The GPR system consisted of a vector network analyser combined with a low‐frequency 0.2–2.0 GHz off‐ground monostatic horn antenna, thereby setting up an ultra‐wideband stepped‐frequency continuous‐wave radar. A fully automated platform was created by mounting the radar system on a truck for real‐time data acquisition. An antenna calibration experiment was performed by lifting the whole setup to different heights above a perfect electrical conductor. This calibration procedure allowed the flittering out of the antenna effects and antenna‐soil interactions from the raw radar data in the frequency domain. To avoid surface roughness effects, only the lower frequency range of 0.2–0.8 GHz was used for signal processing. Inversions of the radar data using the Green’s functions were performed in the time domain, focusing on a time window containing the surface reflection. GPR measurements were conducted every 4 m along a transect of 100 m. In addition, five time‐domain reflectometry measurements were randomly recorded within the footprint of the GPR antenna. A good agreement was observed between the GPR and time‐domain reflectometry soil water content estimates, as compared to the previous study performed at the same test site using a higher frequency 0.8–1.6 GHz horn antenna. To monitor the dynamics of soil water content, a pair of time‐domain reflectometry probes was installed at 8 cm depth near the footprint of the GPR antenna and both time‐domain reflectometry and GPR measurements were carried out for a period of 20 days. A good agreement of the trend was observed between the time‐domain reflectometry and GPR time‐lapse data with respect to several precipitation events. The proposed method and truck‐mounted setup appear to be promising for the real‐time mapping and monitoring of surface soil moisture contents at the field scale.
Weathering variations in a granitic massif and related geotechnical properties through seismic and electrical resistivity methods
Authors: Olona Javier , Pulgar Javier A. , Fernández‐Viejo Gabriela , López‐Fernández Carlos , González‐Cortina Juan M. 
Published: January 2011

ABSTRACTMapping and distribution with depth of alteration in rocks is critical in engineering planning because it has a fundamental impact on the geotechnical properties of the materials. Lateral heterogeneity on a weathered rock massif makes boreholes inadequate for its complete characterization. Geophysical methods increase spatial sampling along the study area and can be related to geotechnical parameters, so subsoil conditions can be better understood.In order to determine its geotechnical qualities and variability along two different profiles, we attempt to characterize a granite massif in north‐west Spain by the integration of results from seismic refraction, multichannel analysis of surface waves (MASW) and electrical resistivity tomography methods (ERT). The study area, the so‐called Carlés granite, shows all the weathering grades from sandy soil to fresh rock. A reference borehole where samples were taken and laboratory measurements were made, serves as a direct check for the results of one of the profiles, the other being interpreted without any direct information. This approach has permitted the evaluation of the advantages and limitations of each geophysical method and created an accurate geotechnical model of the massif, correlating physical and geotechnical parameters such as rock quality designation, weathering grade, or standard penetration test.The field seismic velocities have been compared with the ultrasonic measurements at the laboratory, permitting an evaluation of the field and laboratory elastic constants. The trend in the values of these parameters agrees with the field and laboratory test for the shallow parts of the massif. However, unrealistic elastic constants have been obtained for fresh rock based on the results of the field experiments. This is related to an apparent underestimation of the velocity of seismic S‐waves for the deepest layers. This fact suggests that the methodology followed throughout this work is able to provide a full geotechnical model of an altered rock massif for the first tens of metres, discriminating between different weathered levels. It is also useful and reliable when inferring elastic constants for depths of up to 20 m. However, its validity becomes doubtful with depth, so care must be taken when calculating elastic moduli and trying to extrapolate directly to a rock massif.
Shallow seismic investigation of surface deformation associated with the Kilmichael dome, Montgomery County, Mississippi, USA
Authors: Sloan Steven D. , Harris James B. 
Published: January 2011

ABSTRACTThe Kilmichael dome structure is a circular feature exposed in unconsolidated early Tertiary sediments of north‐central Mississippi, USA. The structural complexity of the area, including zones of intense faulting and uplifted strata, has led to several suggested origins for the formation of the Kilmichael dome, including meteorite impact and regional tectonics; however, the origin remains unknown. As part of an undergraduate student research project, we acquired shallow shear‐wave seismic reflection data over a complex zone of surface faults on the northern flank of the Kilmichael dome, with the goal of imaging the subsurface expression of deformation associated with faulting expressed along an exposed road cut. We also collected multi‐component downhole seismic data in a nearby borehole to analyse the shear‐wave velocity structure of the shallow sediments and observe possible anisotropy. Polarization analysis of the downhole data identified shear‐wave anisotropy consistent with structural alignments in the area. Interpretation of the reflection profile and particle motion plots from the downhole data allowed correlation with shallow structural features of the Kilmichael dome.