bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated geological and geophysical exploration for concealed ores beneath cover in the Chaihulanzi goldfield, northern China
Authors: Liu Hongtao , Liu Jianming , Yu Changming , Ye Jie , Zeng Qingdong 
Published: September 2010

ABSTRACTAn integrated geological and geophysical investigation was carried out in the near‐mine areas of the Chaihulanzi gold‐field, Inner Mongolia, northern China, to determine the south‐eastern strike extension of the principal mineralized shear system, in the search for new resources. In this case study, surface geophysical surveys played an important role in defining the mineralized structures beneath cover. A re‐investigation of the mine geology by observing the underground exposures of mineralization and its hosting structures, coupled with re‐evaluation and re‐examination of previous exploration data, revealed that the mineralization style at the Chaihulanzi gold‐field is not the skarn‐type as previously assumed, but is structurally controlled by an oblique‐sinistral shear structure. Moreover, a south‐eastward shallow‐plunging mineralized corridor within the principal mineralized shear system was also identified, implying that the ore‐forming fluid‐flow might move through the mineralizing system, from the south‐east at depth to the north‐west. These new geological findings imply that the mineralized shear system should extend much farther south‐eastwards along strike beneath cover, and thus a conceptual target area was proposed. A detailed geophysical survey program, involving the application of VLF‐EM, Stratagem EH4, CSAMT and gradient IP measurements, was carried out to test the validity of the conceptual target. Orientation surveys on the geologically known Line‐18 traverse revealed that VLF‐EM and Stratagem EH4 were the most effective methods of detecting the unseen mineralized system, whereas CSAMT could only provide low‐resolution data, and IP proved to be unsuitable in this environment due to the ubiquitous presence of graphite‐bearing schists in and around the mineralized system. A follow‐up systematic VLF‐EM survey highlighted the principal mineralized shear system as a linear conductive belt, tracing the principal mineralized system for a further 750 m of strike length beneath cover from the previous exploration limit (Line 18). Stratagem EH4 soundings over six parallel traverses perpendicular to the mineralized trend revealed that the principal mineralized shear structure extends for more than 500 m in the dip direction, a strong indication of the presence of potential deep mineralization under the surveyed area. Detailed modelling of the Stratagem EH4 sounding images provided well‐defined targets for test drilling. Subsequent test drilling on some of these targets returned encouraging results as several core‐intercepts of economic gold mineralization were encountered. This led to a more extensive drilling and underground prospecting program, focusing on deep mineralization south‐eastwards along the mineralized trend.
Analytical solution for the electric potential in arbitrary anisotropic layered media applying the set of Hankel transforms of integer order
Authors: Pervago E. , Mousatov A. , Shevnin V. 
Published: September 2010

ABSTRACTThe analytical solution and algorithm for simulating the electric potential in an arbitrarily anisotropic multilayered medium produced by a point DC source is here proposed. The solution is presented as a combination of Hankel transforms of integer order and Fourier transforms based on the analytical recurrent equations obtained for the potential spectrum. For the conversion of the potential spectrum into the space domain, we have applied the algorithm of the Fast Fourier Transform for logarithmically spaced points. A comparison of the modelling results with the power‐series solution for two‐layered anisotropic structures demonstrated the high accuracy and computing‐time efficiency of the method proposed.The results of the apparent‐resistivity calculation for both traditional pole‐pole and tensor arrays above three‐layered sequence with an azimuthally anisotropic second layer are presented. The numerical simulations show that both arrays have the same sensitivity to the anisotropy parameters. This sensitivity depends significantly on the resistivity ratio between anisotropic and adjacent layers and increases for the models with a conductive second layer.
Anisotropic migration velocity analysis: Application to a data set from West Africa
Authors: Sarkar Debashish , Tsvankin Ilya 
Published: September 2010

ABSTRACTAlthough it is widely recognized that anisotropy can have a significant influence on the focusing and positioning of migrated reflection events, conventional depth imaging methods still operate with isotropic velocity fields. Here, we present an application of a 2D migration velocity analysis (MVA) algorithm, designed for factorized v(x, z) VTI (transversely isotropic with a vertical symmetry axis) media, to an offshore data set from West Africa. By approximating the subsurface with factorized VTI blocks, it is possible to decouple the spatial variations in the vertical velocity from the anisotropic parameters with minimal a priori information.Since our method accounts for lateral velocity variation, it produces more accurate estimates of the anisotropic parameters than those previously obtained with time‐domain techniques. The values of the anellipticity parameter η found for the massive shales exceed 0.2, which confirms that ignoring anisotropy in the study area can lead to substantial imaging distortions, such as mis‐stacking and mispositioning of dipping events. While some of these distortions can be removed by using anisotropic time processing, further marked improvement in image quality is achieved by prestack depth migration with the estimated factorized VTI model. In particular, many fault planes, including antithetic faults in the shallow part of the section, are better focused by the anisotropic depth‐migration algorithm and appear more continuous. Anisotropic depth migration facilitates structural interpretation by eliminating false dips at the bottom of the section and improving the images of a number of gently dipping features.One of the main difficulties in anisotropic MVA is the need to use a priori information for constraining the vertical velocity. In this case study, we successfully reconstructed the time–depth curve from reflection data by assuming that the vertical velocity is a continuous function of depth and estimating the vertical and lateral velocity gradients in each factorized block. If the subsurface contains strong boundaries with jumps in velocity, knowledge of the vertical velocity at a single point in a layer is sufficient for our algorithm to determine all relevant layer parameters.
Wavefield Migration plus Monte Carlo Imaging of 3D Prestack Seismic Data
Authors: Bonomi Ernesto , Brieger Leesa M. , Cazzola Luca , Zanoletti Francesco 
Published: September 2010

ABSTRACTPrestack wave‐equation migration has proved to be a very accurate shot‐by‐shot imaging tool. However, 3D imaging with this technique of a large field acquisition, especially one with hundreds of thousands of shots, is prohibitively costly. Simply adapting the technique to migrate many superposed shot‐gathers simultaneously would render 3D wavefield prestack migration cost‐effective but it introduces uncontrolled non‐physical interference among the shot‐gathers, making the final image useless. However, it has been observed that multishot signal interference can be kept under some control by averaging over many such images, if each multishot migration is modified by a random phase encoding of the frequency spectra of the seismic traces.In this article, we analyse this technique, giving a theoretical basis for its observed behaviour: that the error of the image produced by averaging over M phase encoded migrations decreases as M−1. Furthermore, we expand the technique and define a general class of Monte‐Carlo encoding methods for which the noise variance of the average imaging condition decreases as M−1; these methods thus all converge asymptotically to the correct reflectivity map, without generating prohibitive costs.The theoretical asymptotic behaviour is illustrated for three such methods on a 2D test case. Numerical verification in 3D is then presented for one such method implemented with a 3D PSPI extrapolation kernel for two test cases: the SEG–EAGE salt model and a real test constructed from field data.
A multigrid solver for 3D electromagnetic diffusion
Authors: Mulder W.A. 
Published: September 2010

ABSTRACTThe performance of a multigrid solver for the time‐harmonic electromagnetic problem in geophysical settings is investigated. The frequencies are sufficiently small for waves travelling at the speed of light to be negligible, so that a diffusive problem remains. The discretization of the governing equations is obtained by the finite‐integration technique, which can be viewed as a finite‐volume generalization of Yee's staggered grid scheme. The resulting set of discrete equations is solved by a multigrid method.The convergence rate of the multigrid method decreased when the grid was stretched. The slower convergence rate of the multigrid method can be compensated by using bicgstab2, a conjugate‐gradient‐type method for non‐symmetric problems. In that case, the multigrid solver acts as a preconditioner. However, whereas the multigrid method provides excellent convergence with constant grid spacings, it performs less than satisfactorily when substantial grid stretching is used.
Seeing below the basalt – offshore Faroes
Authors: Gallagher Joseph W. , Dromgoole Peter W. 
Published: September 2010

ABSTRACTExploration in the basalt covered areas of the Faroes offshore has always suffered from poor seismic imaging below the basalt. Long offset 2D and 3D seismic data were acquired and a significant improvement in the seismic image below top basalt has been achieved. Deep towing of the source and receiver cables helped by extending the seismic bandwidth towards lower frequencies. Bubble‐tuned rather than conventional peak‐tuned source arrays gave little, if any, incremental benefit. The improvement in the imaging comes primarily from the approach to processing the data. High frequencies (dominantly noise) are filtered out of the data early in the processing to concentrate on the low frequency data. Careful multiple removal is important with several passes of demultiple being applied to the data using both Surface‐Related Multiple Elimination (SRME) and Radon techniques. Velocity analysis is performed as an iterative process taking into account the geological model. Reprocessing legacy 2D surveys, acquired with wide‐ranging parameters, using these processing techniques improved these datasets significantly, indicating that sub‐basalt imaging seems to be more sensitive to processing than to the choice of acquisition parameters.
The spatial distribution of forest biomass in the Brazilian Amazon: a comparison of estimates
Authors: Houghton R. A. , Lawrence K. T. , Hackler J. L. , Brown Sandra 
Published: September 2010

AbstractThe amount of carbon released to the atmosphere as a result of deforestation is determined, in part, by the amount of carbon held in the biomass of the forests converted to other uses. Uncertainty in forest biomass is responsible for much of the uncertainty in current estimates of the flux of carbon from land‐use change. In the present contribution several estimates of forest biomass are compared for the Brazilian Amazon, based on spatial interpolations of direct measurements, relationships to climatic variables, and remote sensing data. Three questions were posed: First, do the methods yield similar estimates? Second, do they yield similar spatial patterns of distribution of biomass? And, third, what factors need most attention if we are to predict more accurately the distribution of forest biomass over large areas?   The answer to the first two questions is that estimates of biomass for Brazil's Amazonian forests (including dead and belowground biomass) vary by more than a factor of two, from a low of 39 PgC to a high of 93 PgC. Furthermore, the estimates disagree as to the regions of high and low biomass. The lack of agreement among estimates confirms the need for reliable determination of aboveground biomass over large areas. Potential methods include direct measurement of biomass through forest inventories with improved allometric regression equations, dynamic modelling of forest recovery following observed stand‐replacing disturbances, and estimation of aboveground biomass from airborne or satellite‐based instruments sensitive to the vertical structure plant canopies.
Adaptive microevolutionary responses to simulated global warming inSimocephalus vetulus: a mesocosm study
Authors: VAN DOORSLAER WENDY , STOKS ROBBY , JEPPESEN ERIK , DE MEESTER LUC 
Published: September 2010

AbstractAlthough several studies suggest the occurrence of microevolutionary responses that may allow local persistence of populations under global warming, rigorous experimental proof is lacking. Here, we combined the realism and rigid, replicated experimental design of a large‐scale mesocosm study where populations of the zooplankterSimocephalus vetuluswere exposed for 1 year to different global warming scenarios with a life table experiment under laboratory conditions at three temperatures that eliminated confounding, nongenetic factors. Our results provide solid proof for a rapid microevolutionary response to global warming in both survival and the subcomponents of individual performance (age at reproduction and number of offspring), which may allow populations ofS. vetulusto persist locally under predicted scenarios of global warming. Such microevolutionary responses may buffer changes in community structure under global warming and help explain the outcome of previous mesocosm studies finding only marginal effects of global warming at the community level.
Compositional similarity among urban floras within and across continents: biogeographical consequences of human‐mediated biotic interchange
Authors: LA SORTE FRANK A. , McKINNEY MICHAEL L. , PYŠEK PETR 
Published: September 2010

AbstractAnthropogenic activities have weakened biogeographical barriers to dispersal resulting in the global spread and establishment of an increasing number of non‐native species. We examine the broad‐scale consequences of this phenomenon based on an analysis of compositional similarity across urban floras in the northeastern United States and Europe. We test the prediction that homogenization of species composition is uniquely defined within vs. between continents based on the time and place of origin of non‐native species. In this case, for archaeophytes and neophytes in Europe (introduced before and after ad 1500, respectively) and non‐native species originating from within and outside the United States. More species in urban floras were shared within than between continents. Within Europe, archaeophytes shared more species across urban floras compared with neophytes; strong associations were not observed for non‐native species across US urban floras. Between the two continents, non‐native species in the United States that originated from outside the United States shared species primarily with archaeophytes but also with European natives and neophytes. These results suggest that the direction of biotic interchange was unidirectional with species moving primarily from Europe to the United States with archaeophytes playing a primary and non‐native species originating from outside the two continents a secondary role as a homogenizing source. Archaeophytes, based on combination of biogeographical, evolutionary, and ecological factors in association with a long history of anthropogenic influence, appear to have played a prominent role in the continental and intercontinental homogenization of species composition. This suggests that the uniform homogenization of the Earth's biota is not imminent and is presently directed by a combination of biogeographically defined anthropogenic and historical factors.
Prognostic relevance of tumour cell‐associated uPAR expression in invasive ductal breast carcinoma
Authors: Kotzsch Matthias , Bernt Katharina , Friedrich Katrin , Luther Elvira , Albrecht Sybille , Gatzweiler Axel , Magdolen Viktor , Baretton Gustavo , Zietz Christian , Luther Thomas 
Published: September 2010

Kotzsch M, Bernt K, Friedrich K, Luther E, Albrecht S, Gatzweiler A, Magdolen V, Baretton G, Zietz C & Luther T (2010) Histopathology 57, 461–471 Prognostic relevance of tumour cell‐associated uPAR expression in invasive ductal breast carcinomaAims:  The urokinase‐type plasminogen activator receptor (uPAR) is a key molecule for pericellular proteolysis in tumour cell invasion and metastasis. The aim was to evaluate the prognostic impact of uPAR in invasive breast cancer dependent on which cell types within the tumour express uPAR.Methods and results:  uPAR expression was analysed by immunohistochemistry in 270 tumour tissue specimens of invasive ductal breast carcinomas using tissue microarrays. For evaluation of uPAR immunoexpression we used the epitope‐mapped, uPAR domain II‐specific monoclonal antibody IID7. High uPAR score values in both tumour cells (uPAR‐Tc) and stromal cells were significantly related to high tumour grade (G3), and inversely correlated with oestrogen receptor status. On multivariate analysis, high uPAR‐Tc values contributed independent prognostic information for disease‐free survival (hazard ratio 1.93, P = 0.007) when adjusted for prognostically relevant clinicopathological parameters, whereas uPAR expression in stromal cells was not related to prognosis. In addition, elevated uPAR‐Tc values were found to be prognostic indicators in clinically relevant subgroups of patients with invasive breast cancer.Conclusions:  In invasive breast cancer uPAR expression in invasive carcinoma cells, but not in stromal cells, has a significant impact on patients’ prognosis, and contributes to a more aggressive tumour phenotype.
Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France
Authors: Hajri A. , Meyer D. , Delort F. , Guillaumès J. , Brin C. , Manceau C. 
Published: September 2010

A new bacterial disease of Persian (English) walnut (Juglans regia) has been observed in France. This disease, called vertical oozing canker (VOC), is characterized by vertical cankers on trunks and branches of affected walnut trees with oozing exudates. To determine the aetiology of the disease, a study was carried out in 79 walnut orchards and nurseries located in southeastern and southwestern France. Bacterial analysis from diseased samples yielded 36 strains identified as Xanthomonas arboricola and 32 strains identified as Brenneria nigrifluens on the basis of biochemical tests. The causal agent of VOC was identified as X. arboricola by pathogenicity tests on walnut. Fluorescent amplified fragment length polymorphism (F‐AFLP) was carried out on 36 strains of X. arboricola collected in this study, 24 strains of X. arboricola pv. juglandis isolated from walnut blight symptoms and one strain of X. arboricola pv. corylina included as an outgroup. Based on cluster analysis of F‐AFLP data, most X. arboricola strains responsible for main VOC outbreaks showed a high degree of similarity, forming a cluster clearly separate from strains of X. arboricola pv. juglandis isolated from walnut blight symptoms. It is suggested that VOC is caused by a distinct genetic lineage within the pathovar juglandis of X. arboricola that is also able to cause classical bacterial blight symptoms on walnut leaves and fruits.
Alluvial fan and wetland interactions: evidence of seasonal slope wetlands from the Silurian of south central Wales, UK
Authors: HILLIER ROBERT D. , WATERS RICHARD A. , MARRIOTT SUSAN B. , DAVIES JEREMY R. 
Published: September 2010

AbstractDistal environs of the Ludlow‐age Trichrug Formation from south central Wales (UK) detail deposition on the outer fringe of an ephemeral debris flow‐dominated alluvial fan. Debrites and subordinate sheetflood deposits are interbedded with sporadic thin sandstone‐dominated heterolithic units deposited in shallow, ephemeral ponds in the axial valley. The latter slope wetland system fringed the permeable alluvial fan deposits, being maintained by streamflow, precipitation and ground water recharge. A prolonged high water table is indicated by low chroma intervals interpreted as the result of gleying. A variety of redoximorphic indicators, including colour mottling and ferricrete concretions, are evidence of iron mobilization and concentration associated with a seasonally fluctuating water table. The slope wetlands were colonized periodically by Skolithos‐generating organisms, most likely to have been arthropods. The widespread occurrence of redoximorphic indicators and ferricrete contrasts markedly with calcrete Vertisols in penecontemporaneous continental deposits (Lower Old Red Sandstone) of the region. It is likely that the alluvial fan‐toe area was the site of a wetland depression, which maintained a high, though fluctuating, water table. In contrast the alluvial channel reaches of the surrounding drainage network were significantly better drained, with floodplains prone to wetting and drying and Vertisol palaeopedogenesis.
A questionnaire to measure health practitioners’ attitudes to partnership in medicine taking: LATCon II
Authors: Knapp Peter , Raynor David K. , Thistlethwaite Jill E. , Jones Marc B. 
Published: September 2010

AbstractObjectives  To revise and improve an existing scale to measure health practitioners’ attitudes to partnership in medicine taking and to ascertain the views of medical students, nursing students and pre‐registration pharmacists on concordance.Background  The traditional model of the practitioner‐patient interaction incorporates a practitioner‐centred approach, focusing on the disease rather than the patient. The philosophy of ‘concordance’ (or ‘partnership in medicine‐taking’) puts the patient at the centre of the interaction, with the patient interacting reciprocally with the practitioner. The Leeds Attitude to Concordance (LATCon) scale was developed in 2001 to assess practitioners’ and patients’ attitudes to concordance. However, thinking on concordance has developed since then and the present study aimed to revise the scale to ensure that it reflected current thinking and also to increase its reliability and validity.Design  A pool of potential items was developed and sent to three subject experts for opinion. An attitudinal Likert scale of 31 items was developed. Its completion was followed by statistical item reduction to 20 items. The shorter scale was completed by the same participants 4–6 weeks later.Setting and participants  The study was set in a university in the UK. Participants were 183 medical students, nursing students, and pre‐registration pharmacists.Results and discussion  The study derived a 20 item scale, including five negatively‐worded items, with good levels of internal and test‐retest reliability. Factor analysis suggested five main factors. A statistically significant difference in attitudes was found between student nurses and medical students, and student nurses and pre‐registration pharmacists, with student nurses being more in agreement with the concordant approach. Overall, participants were in agreement with the concordant approach to medicine taking.The UK National Health Service advocates partnership in medical care and is encouraging both practitioners and patients to work to introduce this. There is increased awareness of the patients’ perspective by practitioners, but its impact on their practice remains unclear. Education and skills teaching must continue for the benefits of a concordant approach to be seen. The LATCon scale could play a useful role in education and training, and in research assessing the movement towards the new approach.