bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of uncertainty in rock‐physics models on reservoir parameter estimation using seismic amplitude variation with angle and controlled‐source electromagnetics data
Authors: Chen Jinsong , Dickens Thomas A. 
Published: July 2008

ABSTRACTThis paper investigates the effects of uncertainty in rock‐physics models on reservoir parameter estimation using seismic amplitude variation with angle and controlled‐source electromagnetics data. The reservoir parameters are related to electrical resistivity by the Poupon model and to elastic moduli and density by the Xu‐White model. To handle uncertainty in the rock‐physics models, we consider their outputs to be random functions with modes or means given by the predictions of those rock‐physics models and we consider the parameters of the rock‐physics models to be random variables defined by specified probability distributions. Using a Bayesian framework and Markov Chain Monte Carlo sampling methods, we are able to obtain estimates of reservoir parameters and information on the uncertainty in the estimation. The developed method is applied to a synthetic case study based on a layered reservoir model and the results show that uncertainty in both rock‐physics models and in their parameters may have significant effects on reservoir parameter estimation. When the biases in rock‐physics models and in their associated parameters are unknown, conventional joint inversion approaches, which consider rock‐physics models as deterministic functions and the model parameters as fixed values, may produce misleading results. The developed stochastic method in this study provides an integrated approach for quantifying how uncertainty and biases in rock‐physics models and in their associated parameters affect the estimates of reservoir parameters and therefore is a more robust method for reservoir parameter estimation.
Effective permittivity of porous media: a critical analysis of the complex refractive index model
Authors: Brovelli Alessandro , Cassiani Giorgio 
Published: July 2008

ABSTRACTThe availability of reliable constitutive models linking the bulk electric properties of porous media to their inner structure is a key requirement for useful quantitative applications of noninvasive methods. This study focuses on the use of dielectric measurements to monitor fluid saturation changes in porous materials. A number of empirical, semi‐empirical and theoretical relationships currently exists that link the bulk dielectric constant with volumetric water content. One such relationship, named complex refractive index model or Lichteneker‐Rother model has been extensively applied in recent years. Here we first analyse the characteristics of this Lichteneker‐Rother model by means of theoretical considerations. This theoretical analysis indicates that the Lichteneker‐Rother exponent is dependent upon the geometrical properties of the porous structure, as well as the permittivity contrast between the different phases. Pore‐scale modelling and experimental data further support this result. The parameter estimation robustness in presence of synthetic data error is also assessed. This demonstrates that Lichteneker‐Rother parameters cannot, in general, be independently identified on the basis of bulk dielectric constant versus moisture content data.
Thermal effect of magma intrusion on the electrical properties of magnetic rocks from Hammamat sediments, Cairo, Egypt
Authors: Gomaa Mohamed M. , Elsayed Ragaa 
Published: July 2008

ABSTRACTThe thermal effects of magmatic intrusion on the conductivity and dielectric constant of magnetic rocks from Hammamat sediments, NE desert, Cairo, Egypt (latitude ∼27° and longitude ∼33°) were investigated experimentally in the laboratory using nonpolarizing electrodes. Granitic magma was intruded into the Hammamat sediments, which are a mixture of mainly magnetite with sandstone and due to the thermal effect the area around was extensively heated and altered to different degrees. Due to this magma intrusion, magnetite was transformed (by heating) to hematite to different degrees according to its location from the intrusion. Complex impedance measurements were performed in the frequency range of 10 Hz to 100 KHz at normal temperature (∼20°C) and at a relative humidity of ∼50% RH. Samples were collected at different locations perpendicular to the core of the magma intrusion. Experimental data indicate that the electrical properties vary strongly as we move away (with distance) from the magma intrusion. The conductivity of hematite is ∼10−2 S/m and that of magnetite is ∼104 S/m. As we move from magnetite to hematite (to the core of the magma intrusion) it is supposed that the conductivity will decrease but it was found that the conductivity increases (which is supposed to be abnormal). The conductivity increases with increasing frequency from ∼10−8 S/m to ∼10−5 S/m with almost power‐law dependence on frequency. The conductivity increases in the order of one decade due to the variation from magnetite to hematite. The increase of conductivity, as we move from magnetite to hematite, was argued to be due to the heating that partially or completely melts the samples, thus the porosity of the samples was decreased and accordingly the conductivity and dielectric constant increased. It was also supposed that the grains of the conductor in the samples are coated or isolated with insulator material. A percolation behaviour for the conductivity and dielectric constant, characteristic of random conductor‐insulator mixtures, was found with distance, where continuous paths of the conductive material occur accompanied by peaking of the dielectric constant.Complex impedance plots show that as we move in the direction of altered samples (towards hematite) the relation between real and imaginary impedance changes from a linear form to an arc of a depressed semicircle and increases in depression as we move in the direction of the altered samples, which is consistent with the above interpretation.
Comparison of outputs of a biophysical simulation model for pasture growth and composition with measured data under dryland and irrigated conditions in New Zealand
Authors: White T. A. , Johnson I. R. , Snow V. O. 
Published: July 2008

AbstractSimulation models have a role in predicting and understanding the consequences of weather and management perturbations to biophysical systems. One such model is EcoMod – a biophysical simulation model of a pastoral ecosystem. It comprises a range of sub‐models that form the main components of pastoral ecosystems – namely plants, soils and ruminant livestock. These component models are integrated to simulate the complex interactions occurring within such systems. The purpose of this study was to test how well EcoMod simulated the changes in growth rate and plant composition of dryland and irrigated pasture production in a temperate climate through comparison with a long‐term (1966–2003) data set measured in New Zealand. The general behaviour of the modelled pastures was similar to those of the observed pastures. There was also close agreement between the measured and modelled total annual and monthly growth rates of dry matter (DM), particularly after modifying some of the parameters of plant growth to better represent the characteristics of dominant species present under dryland and irrigation pastures. There was greater discrepancy between measured and modelled pasture composition but in the case of the simulation of the dryland pasture, the proportional differences in species composition were much greater than the absolute differences in species composition. In addition to comparing the outputs of EcoMod to data from actual pasture production, model testing issues and potential sources of error between model outputs and data were also examined.
Selection of grazing‐tolerant lucerne cultivars
Authors: Pecetti L. , Romani M. , De Rosa L. , Piano E. 
Published: July 2008

AbstractImprovement of grazing‐tolerance in lucerne (Medicago sativa L.) is an objective of interest worldwide for the acknowledged potential of this species in pastures. A breeding programme applied standard methods of the selection for this trait, which implies continuous stocking and intensive grazing, to germplasm preliminarily selected for reportedly positive morphological attributes (large and deep crowns; non‐erect growth habit). In this study six experimental cultivars, originating from this programme, and three check varieties were evaluated. Grazing tolerance was assessed under continuous sheep stocking for 2 years. Herbage yield in 3 years and seed yield (in the second year) were also evaluated in distinct and contiguous sub‐experiments. One experimental cultivar had a prostrate habit, two were semi‐prostrate, and three were semi‐erect. Under grazing, five of them showed final persistence similar to, or better than, that of the tolerant check variety adopted in the standard test. In particular, the prostrate experimental cultivar (termed Camporegio) had remarkable persistence, although associated with low vigour, associated with the introgression of M. sativa ssp. falcata into its parentage. A semi‐erect cultivar (termed Verbena) possessed a good balance between grazing tolerance, potential dry‐matter yield and seed yield.
Long‐term responses in the yield of Eastern Gamagrass [Tripsacum dactyloides (L.) L.] to nitrogen fertilizer under two harvest regimes in the United States
Authors: Moyer J. L. , Sweeney D. W. 
Published: July 2008

AbstractEastern Gamagrass [Tripsacum dactyloides (L.) L.] is a perennial C4 grass with potentially high productivity. Intensive management through the application of nitrogen (N) fertilizer and frequency of cutting, however, may be required to maximize its potential for forage production. This study determined the long‐term and residual responses of Eastern Gamagrass in terms of dry matter (DM) yield and tiller density to three annual application rates (0, 50 or 100 kg ha−1) of a N‐fertilizer solution applied by broadcasting or knife placement for 5 out of the 10 years of the study, and harvested using one‐cut or two‐cut regimes. Application of N‐fertilizer increased total DM yield in the 5 years of N applications by 0·44 with the first increment of 50 kg N ha−1, and by an additional 0·15 with the next increment of 50 kg N ha−1. In the first year that directly followed N‐fertilizer applications, DM yield was 0·175 higher than the no fertilizer treatment when 50 kg ha−1 had been previously applied and a further 0·16 higher when 100 kg ha−1 had been previously applied. Dry matter yields were greater from the one‐cut than the two‐cut regime only in years when no N‐fertilizer was applied. Knife placement of N‐fertilizer increased total DM yield only at 100 kg N ha−1. Tiller densities were generally higher under the one‐cut than the two‐cut regime, particularly when N‐fertilizer was broadcast. The application of N‐fertilizer increased herbage production, especially when responses in the year subsequent to application are considered.
Iron‐induced mucosal pathology of the upper gastrointestinal tract: a common finding in patients on oral iron therapy
Authors: Kaye P , Abdulla K , Wood J , James P , Foley S , Ragunath K , Atherton J 
Published: July 2008

Aims:  Upper gastrointestinal injury from iron tablets at therapeutic dose is not widely recognized. The aim was to document cases of iron‐related upper gastrointestinal (GI) pathology and to determine frequency of occurrence.Methods and results:  We prospectively studied patients with iron deficiency anaemia undergoing upper GI endoscopy from November 2005 to July 2006. Cases of upper GI iron deposition from these and other cases extracted retrospectively between 1999 and 2006 were examined histopathologically and patient notes were reviewed. In the prospective study, 15/160 patients investigated for iron deficiency anaemia [16.1% (15/93) of those taking oral iron tablets] had iron deposition noted on routine haematoxylin and eosin staining. In this plus the retrospective series, 59 patients were identified with 64 episodes of iron deposition. Eighty‐six percent (6/7) with oesophageal iron deposition had associated erosion. Sixty‐three percent (29/46) with gastric iron deposition had erosion and 80% (37/46) had reactive gastritis. Duodenal deposition was usually (91%, 10/11) within macrophages in villous tips with no erosion. Ninety‐eight percent (58/59) of iron deposition cases had documented oral iron intake.Conclusions:  Iron deposition in the upper GI tract is common in patients taking iron tablets. It is frequently associated with mucosal disruption in the oesophagus and stomach.
The T‐cell pool is anergized in patients with multiple sclerosis in remission
Authors: Fransson Moa E. , Liljenfeldt Lina S. E. , Fagius Jan , Tötterman Thomas H. , Loskog Angelica S. I. 
Published: July 2008

SummaryRelapsing–remitting multiple sclerosis (RRMS) is a complex autoimmune disease of the central nervous system with oscillating phases of relapse and remission. RRMS has been considered to be driven by T helper type 1 (Th1) lymphocytes but new data indicate the involvement of Th17 responses. In the present study, blood samples from patients (n = 48) and healthy individuals (n = 44) were evaluated for their immunological status. T cells from patients with RRMS expressed high levels of the activation marker CD28 (P < 0·05) and secreted both interferon‐γ (CD8: P < 0·05) and interleukin‐17 upon polyclonal mitogen or myelin oligodendrocyte glycoprotein antigen stimulation. However, T cells from patients with RRMS in remission, in contrast to relapse, had poor proliferative capacity (P < 0·05) suggesting that they are controlled and kept in anergy. This anergy could be broken with CD28 stimulation that restored the T‐cell replication. Furthermore, the patients with RRMS had normal levels of CD4+ Foxp3+ T regulatory cells but the frequency of Foxp3+ cells lacking CD127 (interleukin‐7 receptor) was lower in patients with MS (mean 12%) compared to healthy controls (mean 29%). Still, regulatory cells (CD25+ sorted cells) from patients with RRMS displayed no difference in suppressive capacity. In conclusion, patients in relapse/remission demonstrate in vitro T‐cell responses that are both Th1 and Th17 that, while in remission, appear to be controlled by tolerogenic mechanisms yet to be investigated.
The immunomodulatory activity of human umbilical cord blood‐derived mesenchymal stem cells in vitro
Authors: Wang Meng , Yang Yuan , Yang Dongming , Luo Fei , Liang Wenjie , Guo Shuquan , Xu Jianzhong 
Published: July 2008

SummaryBone marrow‐derived mesenchymal stem cells (BM‐MSC) are currently being investigated in preclinical and clinical settings because of their self‐renewal and multipotent differentiative capacity or their immunosuppressive function. However, BM may be detrimental because of the highly invasive donation procedure and BM‐MSC decline with age. Therefore, MSC derived from other sources have been considered as an alternative. However, there is only limited knowledge on their immunomodulatory properties. Human umbilical cord blood (UCB) cells are good substitutes for BM‐MSC because of the immaturity of newborn cells. In this study, we successfully isolated MSC from UCB. The morphological phenotypes, cell cycle status, surface markers and differentiation potential of these clonally expanded cells are consistent with BM‐MSC. Furthermore, UCB‐MSC expanded in vitro retain low immunogenicity and an immunomodulatory effect. Flow cytometry analysis showed that UCB‐MSC did not express CD40, CD40 ligand, CD80, CD86 and major histocompatibility complex class II molecules. We have demonstrated that UCB‐MSC are incapable of inducing allogeneic peripheral blood mononuclear cell (PBMC) proliferation and have a dose‐dependent inhibition of PBMC immune responses in mixed lymphocyte reactions (MLR) and phytohaemagglutinin activation assays, even after interferon‐γ treatment. Additionally, we have found that UCB‐MSC can suppress the function of mature dendritic cells. Using transwell systems, we have demonstrated an inhibition mechanism that depends on both cell contact and soluble factors. Based on the findings we conclude that banked UCB could serve as a potential alternative source of MSC for allogeneic application in the future.
Fatty acid‐induced induction of Toll‐like receptor‐4/nuclear factor‐κB pathway in adipocytes links nutritional signalling with innate immunity
Authors: Schaeffler Andreas , Gross Philipp , Buettner Roland , Bollheimer Cornelius , Buechler Christa , Neumeier Markus , Kopp Andrea , Schoelmerich Juergen , Falk Werner 
Published: July 2008

SummaryTo study the effects of fatty acids and the involvement of the Toll‐like receptor‐4/nuclear factor‐κB (TLR‐4/NF‐κB) pathway with respect to the secretion of adipokines from adipocytes 3T3‐L1 adipocytes were stimulated with increasing doses of fatty acids. The secretion of adiponectin, resistin and monocyte chemoattractant protein‐1 (MCP‐1) was measured by enzyme‐linked immunosorbent assay. The NF‐κB p65 nuclear translocation and TLR‐4 expression were investigated by Western blot. The effects mediated by NF‐κB were tested using a specific NF‐κB‐inhibitor and TLR‐4‐induced effects were analysed with a neutralizing TLR‐4 antibody. Binding of 14C‐labelled fatty acids to TLR‐4/MD‐2 was investigated using a FLAG‐tagged extracellular part of TLR‐4 fused to full‐length MD‐2 via a linker (lipopolysaccharide‐Trap). The messenger RNA (mRNA) expression of adipokines in abdominal adipose tissue of rats fed a standard chow or a high‐fat diet was investigated by reverse transcription–polymerase chain reaction. The TLR‐4 is induced during adipocyte differentiation and its expression is enhanced following fatty acid stimulation. The stimulatory effects of stearic and palmitic acids on MCP‐1 secretion and of palmitoleic acid on resistin secretion are mediated via NF‐κB. The stimulatory effects of stearic, palmitic and palmitoleic acids on resistin secretion and the stimulatory effect of stearic acid on MCP‐1 secretion are mediated via TLR‐4. Fatty acid‐mediated effects are caused by an endogenous ligand because fatty acids were shown not to bind directly to TLR‐4/MD‐2. Adipose tissue mRNA expression and serum levels of adipokines did not differ in rats fed a high‐fat diet. These data provide a new molecular mechanism by which fatty acids can link nutrition with innate immunity.
Role of a serine residue (S278) in the pore‐facing region of the houseflyl‐glutamate‐gated chloride channel in determining sensitivity to noncompetitive antagonists
Authors: Hirata K. , Ishida C. , Eguchi Y. , Sakai K. , Ozoe F. , Ozoe Y. , Matsuda K. 
Published: July 2008

Abstractγ‐Hexachlorocyclohexane (γ‐HCH), fipronil and picrotoxinin are noncompetitive antagonists (NCAs) ofl‐glutamate‐gated chloride channels (GluCls), yet their potencies are weaker than those on γ‐aminobutyric acid receptors (GABARs). The A302S mutation ofDrosophilaRDL (resistant to dieldrin) GABAR confers NCA resistance, and housefly GluCls (MdGluCls) possess S278 as the residue corresponding to the A302. Thus, the effects of S278A mutation on the NCA actions on MdGluCls were investigated. The S278A mutation resulted in enhanced blocking by NCAs of the MdGluCl response to 30 µMl‐glutamate. However, such actions of γ‐HCH and picrotoxinin, but not of fipronil, on the S278A mutant were reduced with 200 µMl‐glutamate. Further increases in thel‐glutamate concentration led to potentiation by NCAs of the mutant response tol‐glutamate.
Highly similar piggyBac elements in Bactrocera that share a common lineage with elements in noctuid moths
Authors: Handler A. M. , Zimowska G. J. , Armstrong K. F. 
Published: July 2008

AbstractThe piggyBac IFP2 transposable element, originally discovered in a Trichoplusia ni cell line, also exists as nearly identical elements in other noctuid lepidopterans, and in several species of the tephritid genus Bactrocera. To further define the distribution of piggyBacs in Bactrocera, and compare their relationship to sequences found in Lepidoptera, a survey by PCR amplification was performed in a range of Bactrocera species. Highly similar piggyBac sequences were found in all B. dorsalis complex species tested, as well as in species in the B. zonata and B. frauenfeldi complexes. All nucleotide sequences had > 94% identity to corresponding sequences in the T. ni IFP2 element, and > 88% identity among the sequences. Conserved primers did not amplify any distantly related sequences that have been found by computational searches in a wider range of insect and non‐insect species. Notably, 55 nucleotide substitutions relative to IFP2 were common to all the Bactrocera sequences, 44 of which exist in piggyBacs previously sequenced from moths, with 17 resulting in amino acid substitutions. These piggyBac elements, that apparently traversed orders by horizontal transfer, probably arose from a lineage separate from IFP2 and the other known elements in T. ni. Implications for the presence of nearly identical piggyBacs, in widely distributed insects, to the applied use of piggyBac vectors are discussed.
Assessment of mark–recapture models to estimate the abundance of a humpback whale feeding aggregation in Southeast Alaska
Authors: Straley Janice M. , Quinn II Terrance J. , Gabriele Christine M. 
Published: July 2008

AbstractAim The aim of this study was to use photographs of the unique pattern on the ventral surface of the flukes to estimate the abundance of humpback whales (Megaptera novaeangliae) in a discrete feeding aggregation in northern Southeast Alaska.Location The study was located in northern Southeast Alaska, USA, in the eastern North Pacific Ocean.Methods This study evaluated mark–recapture models, ranging from the simpler models (pooled and stratified, closed Petersen estimators) to more complex multi‐strata models (closed Darroch and open Hilborn). The Akaike Information Criterion, corrected (AICc) was used as a model comparison statistic.Results Our best estimate of whale abundance in northern Southeast Alaska in 2000 is 961 whales [95% confidence interval (657, 1076)]. This estimate comes from the Hilborn open, multi‐strata approach with constant migration over time, time‐dependent capture probabilities by area, and a fixed survival rate of 0.98. The simpler models were problematic owing to several aspects of whale behaviour, including that (1) the whales did not mix randomly throughout the study area, (2) some whales emigrated temporarily outside the study area and were not available for capture, and (3) whales were not equally identifiable because they did not behave in the same way when they showed their flukes upon diving. This led to heterogeneity in capture probability and a bias in the estimates. The more complex models stratified by area, and using migration movements among areas, compensated for some of these issues when estimating population size.Main conclusions We believe that the Hilborn open, multi‐strata model produced the best estimate because: (1) it incorporated the best information about survival, (2) it used detailed information about the various release groups, (3) the analysis provided an integrated environment in which parameters such as migration and capture probabilities are shared, (4) the three strata encompassed a large portion of the areas used by whales, and (5) the Hilborn model selected was superior in terms of model selection criteria and biological realism. These data provide valuable insights into the numbers and movements of humpback whales in three areas of Southeast Alaska.