bluuebunny/crossref_metadata_2025_split huggingface dataset:
BACH HO FIELD, A FRACTURED GRANITIC BASEMENT RESERVOIR, CUU LONG BASIN, OFFSHORE SE VIETNAM: A “BURIED‐HILL” PLAY
Authors: Cuong Trinh Xuan , Warren J. K. 
Published: March 2009

A combination of seismic, wireline, FMI and core data shows that Bach Ho field in the Cuu Long Basin, offshore SE Vietnam, is an unusual “buried hill” reservoir. There is little or no production from associated siliciclastic “grus” or granite wash, and the fractured reservoir matrix is largely made up of unaltered acid igneous lithologies (mostly granites and granodiorites). A major NE‐SW late Oligocene reverse fault system cross‐cuts the field, with about 2000 m of lateral displacement in the highly productive Central Block. The associated fracture meshwork greatly enhances reservoir quality. Transpressional wrench faulting in the late Oligocene in this part of the field emplaced a block of brittle granitic rock on top of organic‐rich Eocene – Oligocene mudstones, and facilitated the early migration of hydrocarbons into the fracture network.Structure, not erosion, set up the 1000 m column of liquids in the fractured granodiorites which form the reservoir at Bach Ho. Faulted intervals with associated damage zones create an enhanced secondary porosity system in the granodiorite; effective porosities range from 3‐5% and occasionally up to 20%. Some associated fractures are partially blocked by authigenic calcite and kaolinite.Features that degrade reservoir quality at Bach Ho include: (i) a thin, low‐permeability clay‐plugged “rind” created by surface‐related (meteoric) Eocene – Oligocene weathering — this rind variably overprints the uppermost 10‐40 m of exposed basement throughout the Cuu Long Basin; and (ii) widespread hydrothermal cements which largely predate late Oligocene wrench faulting; cementation mostly took place during post‐magmatic cooling and precipitated zeolites, carbonates and silica in fractures which cut across both the igneous and the country rocks.Porosity‐occluding hydrothermal and authigenic precipitates developed in pre‐existing fractures in the Bach Ho granodiorite. These pre– late Oligocene mineral‐filled fractures acted as zones of structural weakness during and after subsequent late Oligocene structural deformation. Together with new fractures formed during thrusting, the older fractures may have reopened during thrust emplacement, and subsequent gravitational settling of, the Central Block.
INVESTIGATION OF ELASTIC INVERSION ATTRIBUTES USING THE EXPANSIBLE CLAY MODEL FOR WATER SATURATION
Authors: Ugbo J. O. , Ward C. R. , Lennox P. G. 
Published: March 2009

Quantitative X‐ray diffraction has been used to characterize water saturation levels in complex shaly sand reservoirs (i.e. shaly sands with infrequent carbonates and minor proportions of iron‐rich minerals such as pyrite and siderite). The results led to the design of a total expansible clay model for water saturation, which is similar in form to the Dual Water model except that the excess effect of the clay minerals has been accounted for by a volume‐conductivity relationship, rather than one of the usual volume‐porosity translations, effectively reducing the uncertainties in estimating water saturation. Given the ambiguities associated with predicting these petrophysical properties from data on rock properties, such as mineralogy, an investigation of the relationship of estimated water saturation based on the total expansible clay model to independently determined rock properties was undertaken using well log inversion and forward modelling techniques. The results show that there is consistency in the relationship between water saturation estimates made from the total expansible clay model and known elastic parameters such as primary and shear‐wave sonic velocity (Vp, Vs), bulk density (ρb) and impedance (I), when the Raymer‐Gardner‐Hunt model is used. Use of the Raymer‐Gardner‐Hunt model to reconstruct the required rock‐physics relationship avoids the classic limitation of the more advanced Gassman model, which assumes that the dry shear modulus is equivalent to the wet shear modulus (μdry=μwet).The present work raises further questions on the application of the Voigt‐Reuss‐Hill (VRH) limits, or the Hashin Shtrikman bounds for averaging the effective shear modulus of the dry matrix in complex shaly sand reservoirs, where a two‐mineral matrix is normally assumed. The study shows the inapplicability of the VRH or Hashin‐Shtrikman averaging techniques but provides a minor adjustment to the averaging that solves the problems faced in reconstructing the relationships between directly measured elastic properties and derived petrophysical properties for this type of reservoir rock.
Isolation and characterization of 15 nuclear microsatellite markers for Baillonella toxisperma Pierre (Sapotaceae), a low‐density tree species of Central Africa
Authors: NDIADE‐BOUROBOU D. , VAILLANT A. , FAVREAU B. , GAYRIN E. , BOUVET J. M. 
Published: March 2009

Abstract Baillonella toxisperma is a scattered endemic species of the Guineo‐Congolian forest. We developed 15 nuclear microsatellite markers specifically for B. toxisperma to analyse the genetic diversity of 188 individuals distributed in two natural populations in Gabon. On average, 8.3 alleles per locus were identified; observed heterozygosity ranged from 0.056 to 0.872 and expected heterozygosity from 0.282 to 0.823 among populations. Only three loci showed a significant departure to Hardy–Weinberg equilibrium, but no linkage disequilibrium was observed for any pair of loci.
Motion Planning and Tracking for Tip Displacement and Deflection
Angle for Flexible Beams
Authors: Siranosian Antranik A. , Krstic Miroslav , Smyshlyaev Andrey , Bement Matt 
Published: March 2009

Abstract
Explicit motion-planning reference solutions are presented for flexible beams with Kelvin–Voigt (KV) damping. The goal is to generate periodic reference signals for the displacement and deflection angle at the free-end of the beam using only actuation at the base. The explicit deflection angle reference solution is found as a result of writing the shear beam model in a strict-feedback form. Special “partial differential equation (PDE) backstepping” transformations relate the strict-feedback model to a “target system,” governed by an exponentially stable wave equation with KV damping, whose displacement reference solution is relatively easy to find. The explicit beam displacement reference solution is found using the target system solution and an inverse backstepping transformation. The explicit reference solutions for the wave equation and shear beam with KV damping are novel results. State-feedback tracking boundary controllers are found by extending previous PDE backstepping stabilization results. Application of the shear beam results to the more complicated Timoshenko beam is discussed.
High-Level Genetic Diversity but No Population Structure Inferred from Nuclear and Mitochondrial Markers of the Peritrichous CiliateCarchesium polypinumin the Grand River Basin (North America)
Authors: Gentekaki E. , Lynn D. H. 
Published: March 2009

ABSTRACTStudies that assess intraspecific genetic variation in ciliates are few and quite recent. Consequently, knowledge of the subject and understanding of the processes that underlie it are limited. We sought to assess the degree of intraspecific genetic variation inCarchesium polypinum(Ciliophora: Peritrichia), a cosmopolitan, freshwater ciliate. We isolated colonies ofC. polypinumfrom locations in the Grand River basin in Southwestern Ontario, Canada. We then used the nuclear markers—ITS1, ITS2, and the hypervariable regions of the large subunit rRNA—and an 819-bp fragment of the mitochondrial cytochromecoxidase I gene (cox-1) to investigate the intraspecific genetic variation ofC. polypinumand the degree of resolution of the above-mentioned markers at the population level. We also sought to determine whether the organism demonstrated any population structure that mapped onto the geography of the region. Our study shows that there is a high degree of genetic diversity at the isolate level, revealed by the mitochondrial markers but not the nuclear markers. Furthermore, our results indicate thatC. polypinumis likely not a single morphospecies as previously thought.
Differential Responses of Nitrate Reducer Community Size, Structure, and Activity to Tillage Systems
Authors: Chèneby D. , Brauman A. , Rabary B. , Philippot L. 
Published: March 2009

ABSTRACT
The main objective of this study was to determine how the size, structure, and activity of the nitrate reducer community were affected by adoption of a conservative tillage system as an alternative to conventional tillage. The experimental field, established in Madagascar in 1991, consists of plots subjected to conventional tillage or direct-seeding mulch-based cropping systems (DM), both amended with three different fertilization regimes. Comparisons of size, structure, and activity of the nitrate reducer community in samples collected from the top layer in 2005 and 2006 revealed that all characteristics of this functional community were affected by the tillage system, with increased nitrate reduction activity and numbers of nitrate reducers under DM. Nitrate reduction activity was also stimulated by combined organic and mineral fertilization but not by organic fertilization alone. In contrast, both negative and positive effects of combined organic and mineral fertilization on the size of the nitrate reducer community were observed. The size of the nitrate reducer community was a significant predictor of the nitrate reduction rates except in one treatment, which highlighted the inherent complexities in understanding the relationships the between size, diversity, and structure of functional microbial communities along environmental gradients.
RNA Interference-Mediated Silencing of Ornithine Decarboxylase and Spermidine Synthase Genes in
Trypanosoma brucei
Provides Insight into Regulation of Polyamine Biosynthesis
Authors: Xiao Yanjing , McCloskey Diane E. , Phillips Margaret A. 
Published: March 2009

ABSTRACT

Polyamine biosynthesis is a drug target for the treatment of African sleeping sickness; however, mechanisms regulating the pathway in
Trypanosoma brucei
are not well understood. Recently, we showed that RNA interference (RNAi)-mediated gene silencing or the inhibition of
S
-adenosylmethionine decarboxylase (AdoMetDC) led to the upregulation of the AdoMetDC activator, prozyme, and ornithine decarboxylase (ODC) proteins. To determine if this regulatory response is specific to AdoMetDC, we studied the effects of the RNAi-induced silencing of the spermidine synthase (SpdSyn) and ODC genes in bloodstream form
T. brucei
. The knockdown of either gene product led to the depletion of the polyamine and trypanothione pools and to cell death. Decarboxylated AdoMet levels were elevated, while AdoMet was not affected. There was no significant effect on the protein levels of other polyamine pathway enzymes. The treatment of parasites with the ODC inhibitor α-difluoromethylornithine gave similar results to those observed for ODC knockdown. Thus, the cellular response to the loss of AdoMetDC activity is distinctive, suggesting that AdoMetDC activity controls the expression levels of the other spermidine biosynthetic enzymes. RNAi-mediated cell death occurred more rapidly for ODC than for SpdSyn. Further, the ODC RNAi cells were rescued by putrescine, but not spermidine, suggesting that the depletion of both putrescine and spermidine is more detrimental than the depletion of spermidine alone. This finding may contribute to the effectiveness of ODC as a target for the treatment of African sleeping sickness, thus providing important insight into the mechanism of action of a key antitrypanosomal agent.
Structure and Complexity of a Bacterial Transcriptome
Authors: Passalacqua Karla D. , Varadarajan Anjana , Ondov Brian D. , Okou David T. , Zwick Michael E. , Bergman Nicholas H. 
Published: March 2009

ABSTRACT

Although gene expression has been studied in bacteria for decades, many aspects of the bacterial transcriptome remain poorly understood. Transcript structure, operon linkages, and information on absolute abundance all provide valuable insights into gene function and regulation, but none has ever been determined on a genome-wide scale for any bacterium. Indeed, these aspects of the prokaryotic transcriptome have been explored on a large scale in only a few instances, and consequently little is known about the absolute composition of the mRNA population within a bacterial cell. Here we report the use of a high-throughput sequencing-based approach in assembling the first comprehensive, single-nucleotide resolution view of a bacterial transcriptome. We sampled the
Bacillus anthracis
transcriptome under a variety of growth conditions and showed that the data provide an accurate and high-resolution map of transcript start sites and operon structure throughout the genome. Further, the sequence data identified previously nonannotated regions with significant transcriptional activity and enhanced the accuracy of existing genome annotations. Finally, our data provide estimates of absolute transcript abundance and suggest that there is significant transcriptional heterogeneity within a clonal, synchronized bacterial population. Overall, our results offer an unprecedented view of gene expression and regulation in a bacterial cell.
Neural Correlates of Human Body Perception
Authors: Aleong Rosanne , Paus Tomáš 
Published: March 2009

Abstract
The objective of this study was to investigate potential sex differences in the neural response to human bodies using fMRI carried out in healthy young adults. We presented human bodies in a block-design experiment to identify body-responsive regions of the brain, namely, extrastriate body area (EBA) and fusiform body area (FBA). In a separate event-related “adaptation” experiment, carried out in the same group of subjects, we presented sets of four human bodies of varying body size and shape. Varying levels of body morphing were introduced to assess the degree of morphing required for adaptation release. Analysis of BOLD signal in the block-design experiment revealed significant Sex × Hemisphere interactions in the EBA and the FBA responses to human bodies. Only women showed greater BOLD response to bodies in the right hemisphere compared with the left hemisphere for both EBA and FBA. The BOLD response in right EBA was higher in women compared with men. In the adaptation experiment, greater right versus left hemisphere response for EBA and FBA was also identified among women but not men. These findings are particularly novel in that they address potential sex differences in the lateralization of EBA and FBA responses to human body images. Although previous studies have found some degree of right hemisphere dominance in body perception, our results suggest that such a functional lateralization may differ between men and women.
On the Temporal Relation of Top–Down and Bottom–Up Mechanisms during Guidance of Attention
Authors: Wykowska Agnieszka , Schubö Anna 
Published: March 2009

AbstractTwo mechanisms are said to be responsible for guiding focal attention in visual selection: bottom–up, saliency-driven capture and top–down control. These mechanisms were examined with a paradigm that combined a visual search task with postdisplay probe detection. Two SOAs between the search display and probe onsets were introduced to investigate how attention was allocated to particular items at different points in time. The dynamic interplay between bottom–up and top–down mechanisms was investigated with ERP methodology. ERPs locked to the search displays showed that top–down control needed time to develop. N2pc indicated allocation of attention to the target item and not to the irrelevant singleton. ERPs locked to probes revealed modulations in the P1 component reflecting top–down control of focal attention at the long SOA. Early bottom–up effects were observed in the error rates at the short SOA. Taken together, the present results show that the top–down mechanism takes time to guide focal attention to the relevant target item and that it is potent enough to limit bottom–up attentional capture.
Brain Structures Involved in Visual Search in the Presence and Absence of Color Singletons
Authors: Talsma Durk , Coe Brian , Munoz Douglas P. , Theeuwes Jan 
Published: March 2009

Abstract
It is still debated to what degree top–down and bottom–up driven attentional control processes are subserved by shared or by separate mechanisms. Interactions between these attentional control forms were investigated using a rapid event-related fMRI design, using an attentional search task. Following a prestimulus mask, target stimuli (consisting of a letter C or a mirror image of the C, enclosed in a diamond outline) were presented either at one unique location among three nontarget items (consisting of a random letter, enclosed in a circle outline; 50% probability), or at all four possible target locations (also 50% probability). On half the trials, irrelevant color singletons were presented, consisting of a color change of one of the four prestimulus masks, just prior to target appearance. Participants were required to search for a target letter inside the diamond and report its orientation. Results indicate that, in addition to a common network of parietal areas, medial frontal cortex is uniquely involved in top–down orienting, whereas bottom–up control is mainly subserved by a network of occipital and parietal areas. Additionally, we found that participants who were better able to suppress orienting to the color singleton showed middle frontal gyrus activation, and that the degree of top–down control correlated with insular activity. We conclude that, in addition to a common set of parietal areas, separate brain areas are involved in top–down and bottom–up driven attentional control, and that frontal areas play a role in the suppression of attentional capture by an irrelevant color singleton.
Bursaphelenchus tokyoensis n. sp. (Nematoda: Parasitaphelenchinae) isolated from dead wood of the Japanese red pine, Pinus densiflora Sieb. & Zucc., in Japan
Authors: Kanzaki Natsumi , Aikawa Takuya , Giblin-Davis Robin 
Published: March 2009

AbstractBursaphelenchus tokyoensis n. sp. is described and figured from a dead Japanese red pine, Pinus densiflora. Despite several attempts, the new species was not successfully cultured and so individuals isolated from the original dead log were used as type specimens. The new species has a body length of ca 710 μm (male) and 770 μm (female), medium values of ratio a (ca 32-38 for males and ca 29-41 for females), b ratio of ca 10-12 (male) and 11-14 (female), c ratio of ca 24-29 (male) and 30-41 (female), c′ ratio of ca 2.3 (male) and ca 2.0 (female), ca 11-14 μm long stylet, four lines in the lateral field, relatively small (ca 14-16 μm), smoothly arcuate spicule lacking clear condylus, rostrum and cucullus, seven male caudal papillae and short and broad female tail with variable-shaped terminus. The new species is typologically close to B. idius but can be distinguished by male caudal papillae arrangement, female tail length and number of lateral lines. Inferred trees based upon molecular phylogenetic analysis of near full length (ca 1.6 kb) small subunit and ca 0.7 kb of the D2/D3 expansion segment of the large subunit of ribosomal DNA placed B. tokyoensis n. sp. closest to the xylophilus- and africanus-groups. However, the new species is distinguished from members of these groups by its characteristic spicule morphology and relative molecular phylogenetic placement.
Distribution and population structure of two bacterial-feeding nematode genera in ice-free areas in East Antarctica
Authors: Boström Sven , Sohlenius Björn 
Published: March 2009

AbstractVery dense populations of nematodes of the genera Plectus and Panagrolaimus were found in moss cushions and in ornithogenic soils in a number of localities on mountain outcrops (nunataks) penetrating the ice sheet and in a coastal oasis in East Antarctica. These high abundances permitted analysis of the structure of populations from various sites. Patterns of distribution and size-class composition in nematode populations from the Basen nunatak, and from scattered samples taken in a larger area including several nunataks and one coastal oasis in Dronning Maud Land, were investigated. It is suggested that the composition of developmental stages and structure of the nematode populations are influenced by environmental conditions such as food supply, temperature and maybe predation or competition from coexisting populations of tardigrades, protozoans and rotifers. The results indicated that the population dynamics were not synchronised among the sites. In several populations the animals appeared well fed with a high frequency of gravid females. In the more extreme localities, in particular, the proportion of adults was very high, and in these sites the recruitment to the populations appeared to be rather low as indicated by the low proportion of juveniles. The structure of the nematode populations seemed little influenced by various combinations of co-occurring tardigrades or rotifers. There were some differences in population structure between nematode populations from different nunataks which could possibly be caused by genetic variability due to long periods of isolation.
Differential susceptibility of entomopathogenic nematodes to nematophagous fungi from Florida citrus orchards
Authors: Bright Diane , El-Borai Fahiem , Stuart Robin , Graham James , Cubero Jaime , Duncan Larry 
Published: March 2009

AbstractLaboratory experiments were conducted to study the effects of various trapping and endoparasitic nematophagous fungi (NF) isolated from Florida citrus orchards on five entomopathogenic nematode (EPN) species that show various distributions across Florida's citrus industry. Four trapping NF (Arthrobotrys oligospora, A. dactyloides, A. musiformis and Gamsylella gephyropaga) and two endoparasitic NF (Catenaria sp. and Myzocytium sp.) were tested against Steinernema diaprepesi (Sd), S. glaseri (Sg), S. riobrave (Sr), Heterorhabditis zealandica (Hz) and H. indica (Hi). Fungi were added to soil microcosms either as a pure culture on agar plugs (trapping NF) or as fungal-colonised nematodes (endoparasitic NF) on agar plugs, concurrently with 2000 EPN of a given species. After 7 or 14 days exposure, nematodes were recovered from the soil using Baermann funnels. The recovery of all EPN species was reduced between 56-92% by G. gephyropaga. Neither Sd or Sg were affected by any species of Arthrobotrys, whereas A. musiformis reduced recovery of all other EPN and A. oligospora reduced numbers of all other species except Hi. Both endoparasitic NF reduced the recovery of all EPN except Hi by at least 82%. The data are consistent with the hypothesis that NF may play a role in regulating regional patterns of abundance and diversity of EPN species in Florida, which in turn regulate the abundance of a major citrus pest, the Diaprepes root weevil, Diaprepes abbreviatus.
Bernardius lineatus gen. n., sp. n. (Enoplida: Enchelidiidae), a remarkable nematode with ornamented cuticle from a Brazilian tropical sandy beach
Authors: da Fonsêca-Genevois Veronica , Venekey Virág , Decraemer Wilfrida , Smol Nic 
Published: March 2009

AbstractBernardius lineatus gen. n., sp. n. is described from a sandy beach at Tamandaré Bay, Brazil. It possesses the main characteristics of the family Enchelidiidae (Nematoda: Enoplida), but is unique by the presence of a body cuticle ornamented with longitudinal ridges formed by small rods, an entirely different character to all other members of the order Enoplida. The new genus is also characterised by a long, subdivided, buccal cavity with two subventral teeth and numerous denticles and the arrangement of the anterior sensilla in two crowns, the anterior crown being papilliform and the posterior crown consisting of six external labial and four cephalic sensilla, setiform. The relationships of the genera within the Enchelidiidae are discussed and an emended family diagnosis provided.