bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antagonistic and agonistic effects of an extracellular fragment of nectin on formation of E‐cadherin‐based cell‐cell adhesion
Authors: Honda Tomoyuki , Shimizu Kazuya , Kawakatsu Tomomi , Yasumi Masato , Shingai Tatsushi , Fukuhara Atsunori , Ozaki‐Kuroda Kumi , Irie Kenji , Nakanishi Hiroyuki , Takai Yoshimi 
Published: March 2003

AbstractBackground: Nectin is a Ca2+‐independent immunoglobulin‐like cell‐cell adhesion molecule at the E‐cadherin‐based cell‐cell adherens junctions (AJs), and comprises a family consisting of four members, nectin‐1, ‐2, ‐3, and ‐4. Nectin and E‐cadherin are associated with afadin and α‐catenin, actin filament (F‐actin)‐binding proteins connecting respective adhesion molecules to the actin cytoskeleton, but the role of nectin in the formation of the E‐cadherin‐based cell‐cell AJs has not yet been fully understood. To obtain evidence for this role of nectin, we attempted to develop an antagonist and/or agonist of nectin.Results: We made a recombinant extracellular fragment of nectin‐3 (Nef‐3). Nef‐3 trans‐interacted with cellular nectin‐1 and thereby diminished the formation of the nectin‐1‐based cell‐cell adhesion. This resulted in a reduction of the formation of the E‐cadherin‐based cell‐cell adhesion in L fibroblasts stably expressing both exogenous nectin‐1α and E‐cadherin (nectin‐1‐EL cells) and MDCK cells stably expressing exogenous nectin‐1α (nectin‐1‐MDCK cells). This antagonistic effect of Nef‐3 was also observed in L cells stably expressing exogenous E‐cadherin alone (EL cells) and wild‐type MDCK cells. Conversely, Nef‐3 coated on microbeads first recruited the nectin–afadin complex and then the E‐cadherin–catenin complex to the bead‐cell contact sites in nectin‐1‐EL and nectin‐1‐MDCK cells.Conclusion: These results suggest that nectin is necessary and sufficient for the recruitment of E‐cadherin to the nectin‐based cell‐cell adhesion sites and involved in the formation of E‐cadherin‐based cell‐cell AJs.
Processing, modelling and predicting time-lapse effects of overpressured fluid-injection in a fractured reservoir
Authors: Angerer Erika , Crampin Stuart , Li Xiang-Yang , Davis Thomas L. 
Published: March 2003

Summary
Time-lapse seismology is important for monitoring subsurface pressure changes and fluid movements in producing hydrocarbon reservoirs. We analyse two 4-D, 3C onshore surveys from Vacuum Field, New Mexico, USA, where the reservoir of interest is a fractured dolomite. In Phase VI, a time-lapse survey was acquired before and after a pilot tertiary-recovery programme of overpressured CO2 injection, which altered the fluid composition and the pore-fluid pressure. Phase VII was a similar time-lapse survey in the same location but with a different lower-pressure injection regime.
Applying a processing sequence to the Phase VI data preserving normal-incidence shear-wave anisotropy (time-delays and polarization) and maximizing repeatability, interval-time analysis of the reservoir interval shows a significant 10 per cent change in shear-wave velocity anisotropy and 3 per cent decrease in the P-wave interval velocities. A 1-D model incorporating both saturation and pressure changes is matched to the data. The saturation changes have little effect on the seismic velocities. There are two main causes of the time-lapse changes. Any change in pore-fluid pressures modifies crack aspect ratios. Additionally, when there are overpressures, as there are in Phase VI, there is a 90° change in maximum impedance directions, and the leading faster split shear wave, instead of being parallel to the crack face as it is for low pore-fluid pressures, becomes orthogonal to the crack face. The anisotropic poro-elasticity (APE) model of the evolution of microcracked rock, calculates the evolution of cracked rock to changing conditions. APE modelling shows that at high overburden pressures only nearly vertical cracks, to which normal incidence P waves are less sensitive than S waves, remain open as the pore-fluid pressure increases. APE modelling matches the observed time-lapse effects almost exactly demonstrating that shear-wave anisotropy is a highly sensitive diagnostic of pore-fluid pressure changes in fractured reservoirs.
In this comparatively limited analysis, APE modelling of fluid-injection at known pressure correctly predicted the changes in seismic response, particularly the shear-wave splitting, induced by the high-pressure CO2 injection. In the Phase VII survey, APE modelling also successfully predicted the response to the lower-pressure injection using the same Phase VI model of the cracked reservoir. The underlying reason for this remarkable predictability of fluid-saturated reservoir rocks is the critical nature and high crack density of the fluid-saturated cracks and microcracks in the reservoir rock, which makes cracked reservoirs critical systems.
Data and model uncertainty estimation for linear inversion
Authors: Kasper van Wijk , John A Scales , William Navidi , Luis Tenorio 
Published: March 2003

Summary
Inverse theory concerns the problem of making inferences about physical systems from indirect noisy measurements. Information about the errors in the observations is essential to solve any inverse problem, otherwise it is impossible to say when a feature ‘fits the data’. In practice, however, one seldom has a direct estimate of the data errors. We exploit the trade-off between data prediction and model or data structure to determine both model-independent and modelbased estimates of the noise characteristics from a single realization of the data. Noise estimates are then used to characterize the set of reasonable models that fit the data, for example, by bintersecting prior model parameter constraints with the set of data fitting models. This prior information can also be used to set bounds on the bias.We illustrate our methods with synthetic examples of vertical seismic profiling and cross-well tomography.
Inversion of normal moveout for monoclinic media1
Authors: Grechka Vladimir , Contreras Pedro , Tsvankin Ilya 
Published: March 2003

Multiple vertical fracture sets, possibly combined with horizontal fine layering, produce an equivalent medium of monoclinic symmetry with a horizontal symmetry plane. Although monoclinic models may be rather common for fractured formations, they have hardly been used in seismic methods of fracture detection due to the large number of independent elements in the stiffness tensor. Here, we show that multicomponent wide‐azimuth reflection data (combined with known vertical velocity or reflector depth) or multi‐azimuth walkaway VSP surveys provide enough information to invert for all but one anisotropic parameters of monoclinic media.In order to facilitate the inversion procedure, we introduce a Thomsen‐style parametrization for monoclinic media that includes the vertical velocities of the P‐wave and one of the split S‐waves and a set of dimensionless anisotropic coefficients. Our notation, defined for the coordinate frame associated with the polarization directions of the vertically propagating shear waves, captures the combinations of the stiffnesses responsible for the normal‐moveout (NMO) ellipses of all three pure modes. The first group of the anisotropic parameters contains seven coefficients (ε(1,2), δ(1,2,3) and γ(1,2)) analogous to those defined by Tsvankin for the higher‐symmetry orthorhombic model. The parameters ε(1,2), δ(1,2) and γ(1,2) are primarily responsible for the pure‐mode NMO velocities along the coordinate axes x1 and x2 (i.e. in the shear‐wave polarization directions). The remaining coefficient δ(3) is not constrained by conventional‐spread reflection traveltimes in a horizontal monoclinic layer. The second parameter group consists of the newly introduced coefficients ζ(1,2,3) which control the rotation of the P‐, S1‐ and S2‐wave NMO ellipses with respect to the horizontal coordinate axes. Misalignment of the P‐wave NMO ellipse and shear‐wave polarization directions was recently observed on field data by Pérez et al.Our parameter‐estimation algorithm, based on NMO equations valid for any strength of the anisotropy, is designed to obtain anisotropic parameters of monoclinic media by inverting the vertical velocities and NMO ellipses of the P‐, S1‐ and S2‐waves. A Dix‐type representation of the NMO velocity of mode‐converted waves makes it possible to replace the pure shear modes in reflection surveys with the PS1‐ and PS2‐waves. Numerical tests show that our method yields stable estimates of all relevant parameters for both a single layer and a horizontally stratified monoclinic medium.
The 3D shear experiment over the Natih field in Oman: the effect of fracture‐filling fluids on shear propagation
Authors: Van Der Kolk C.M. , Guest W.S. , Potters J.H.H.M. 
Published: March 2003

This is the final paper in a series on the 3D multicomponent seismic experiment in Oman. In this experiment a 3D data set was acquired using three‐component geophones and with three source orientations. The data set will subsequently be referred to as the Natih 9C3D data set. We present, for the first time, evidence demonstrating that shear waves are sensitive to fluid type in fractured media. Two observations are examined from the Natih 9C3D data where regions of gas are characterized by slow shear‐wave velocities. One is that the shear‐wave splitting map of the Natih reservoir exhibits much larger splitting values over the gas cap on the reservoir. This increase in splitting results from a decrease in the slow shear‐wave velocity which senses both the fractures and the fracture‐filling fluid. Using a new effective‐medium model, it was possible to generate a splitting map for the reservoir that is corrected for this fluid effect. Secondly, an anomaly was encountered on the shear‐wave data directly above the reservoir. The thick Fiqa shale overburden exhibits a low shear‐wave velocity anomaly that is accompanied by higher shear reflectivity and lower frequency content. No such effects are evident in the conventional P‐wave data. This feature is interpreted as a gas chimney above the reservoir, a conclusion supported by both effective‐medium modelling and the geology.With this new effective‐medium model, we show that introduction of gas into vertically fractured rock appears to decrease the velocity of shear waves (S2), polarized perpendicular to the fracture orientation, whilst leaving the vertical compressional‐wave velocity largely unaffected. This conclusion has direct implications for seismic methods in exploration, appraisal and development of fractured reservoirs and suggests that here we should be utilizing S‐wave data, as well as the conventional P‐wave data, as a direct hydrocarbon indicator.
Free Air CO2 Enrichment of potato (Solanum tuberosum L.): development, growth and yield
Authors: Miglietta F. , Magliulo V. , Bindi M. , Cerio L. , Vaccari F. P. , Loduca V. , Peressotti A. 
Published: March 2003

AbstractA FACE (Free Air CO2 Enrichment) experiment was carried out on Potato (Solanum tuberosum L., cv. Primura) in 1995 in Italy. Three FACE rings were used to fumigate circular field plots of 8 m diameter while two rings were used as controls at ambient CO2 concentrations. Four CO2 exposure levels were used in the rings (ambient, 460, 560 and 660 μmol mol–1). Phenology and crop development, canopy surface temperature, above‐ and below‐ground biomass were monitored during the growing season. Crop phenology was affected by elevated CO2, as the date of flowering was progressively anticipated in the 660, 560, 460 μmol mol–1 treatments. Crop development was not affected significantly as plant height, leaf area and the number of leaves per plant were the same in the four treatments. Elevated atmospheric CO2 levels had, instead, a significant effect on the accumulation of total nonstructural carbohydrates (TNC = soluble sugars + starch) in the leaves during a sunny day. Specific leaf area was decreased under elevated CO2 with a response that paralleled that of TNC concentrations. This reflected the occurrence of a progressive increase of photosynthetic rates and carbon assimilation in plants exposed to increasingly higher levels of atmospheric CO2. Tuber growth and final tuber yield were also stimulated by rising CO2 levels. When calculated by regression of tuber yield vs. the imposed levels of CO2concentration, yield stimulation was as large as 10% every 100 μmol mol–1 increase, which translated into over 40% enhancement in yield under 660 μmol mol–1. This was related to a higher number of tubers rather than greater mean tuber mass or size. Leaf senescence was accelerated under elevated CO2 and a linear relationship was found between atmospheric CO2 levels and leaf reflectance measured at 0.55 μm wavelength. We conclude that significant CO2 stimulation of yield has to be expected for potato under future climate scenarios, and that crop phenology will be affected as well.
Effects of environment during growth on the sensitivity of leaf conductance to changes in humidity
Authors: Bunce James A. 
Published: March 2003

AbstractSoybeans (Glycine max) and grain amaranth (Amaranthus hypochondriacus) were grown at a range of temperatures, carbon dioxide concentrations and light conditions in controlled environment chambers, and the response of leaf conductance to water vapour to changes in humidity was then measured under a standard set of conditions. The sensitivity of conductance was analysed in terms of (i) the absolute sensitivity of conductance to changes in leaf to air water vapour pressure difference (LAVPD), (ii) the sensitivity of conductance relative to the absolute value of conductance, and (iii) the slope of the relationship between conductance and an index incorporating assimilation rate, carbon dioxide concentration and relative humidity. The sensitivity of conductance varied substantially with growth conditions for all three analyses in both species. The growth temperature of 25 °C increased the sensitivity of conductance by all three measures compared with growth at 20 or 30 °C in amaranth, with little difference between 25 and 30 °C in soybean. Growth at elevated carbon dioxide decreased sensitivity in amaranth by all three measures, and decreased the absolute but not the relative sensitivity in soybean. Growth at reduced photon flux density and growth at high stand density reduced sensitivity in amaranth by all three measures. In soybean, growth at high stand density reduced sensitivity by all three measures, but growth at low photon flux density increased the relative sensitivity. The sensitivity of leaf conductance to changes in humidity varied by a factor of two or more with growth environment by all measures of sensitivity in both the C3 and the C4 species.
Methane emission by termites and oxidation by soils, across a forest disturbance gradient in the Mbalmayo Forest Reserve, Cameroon
Authors: Macdonald Jannette A. , Eggleton PauL. , Bignell David E. , Forzi Francis , Fowler David 
Published: March 2003

AbstractMethane fluxes were measured, using static chambers, across a disturbance gradient in a West African semi‐deciduous humid forest. Soil‐feeding termite biomass was simultaneously determined, in an attempt to examine its influence on the net soil‐atmosphere exchange of CH4. CH4 emission rates from individual termite species were determined under laboratory conditions, permitting the gross production of CH4 to be compared with net fluxes to the atmosphere. Both net CH4 oxidation(‐) and emission were observed, and CH4 fluxes ranged from – 24.6 to 40.7 ng m–2 s–1. A statistically significant relationship between termite biomass and CH4 flux was observed across the forested sites such that: CH4 flux (ng m–2 s–1) = 4.95 × termite biomass (gm–2)–10.9 (P < 0.001). Rates of CH4 oxidation were on average 60% smaller at the clearfelled and Terminalia plantation sites than at the near‐primary forest site. Two of the disturbed sites were net CH4 sources during one of the sampling periods. Disturbance of tropical forests, resulting in a decrease in the CH4 sink capacity of the soil, may therefore increase the contribution of termite‐derived CH4 to the atmosphere. Measurements from the mounds of the soil‐feeding termites Thoracotermes macrothorax and Cubitermes fungifaber from the old plantation site gave a CH4 emission of 636 and 53.4 ng s–1 mound–1, respectively. The forest floor surrounding the mounds was sampled in three concentric bands. Around the mound of T. macrothorax the soil was a net source of CH4 estimated to contribute a further 148 ng s–1. Soil surrounding the mound of C. fungifaber was mostly a net sink. The mounds of soil‐feeding termites are point sources of CH4, which at the landscape scale may exceed the general sink capacity of the soil, to an extent dependent on seasonal variations in soil moisture and level of disturbance.
The implications of predicted climate change for insect pests in the UK, with emphasis on non‐indigenous species
Authors: CANNON RAYMOND J. C. 
Published: March 2003

AbstractRecent estimates for global warming predict increases in global mean surface air temperatures (relative to 1990) of between 1 and 3.5 °C, by 2100. The impact of such changes on agricultural systems in mid‐ to high‐latitude regions are predicted to be less severe than in low‐latitude regions, and possibly even beneficial, although the influence of pests and diseases is rarely taken into account. Most studies have concluded that insect pests will generally become more abundant as temperatures increase, through a number of inter‐related processes, including range extensions and phenological changes, as well as increased rates of population development, growth, migration and over‐wintering. A gradual, continuing rise in atmospheric CO2will affect pest species directly (i.e. the CO2fertilization effect) and indirectly (via interactions with other environmental variables). However, individual species responses to elevated CO2vary: consumption rates of insect herbivores generally increase, but this does not necessarily compensate fully for reduced leaf nitrogen. The consequent effects on performance are strongly mediated via the host species. Some recent experiments under elevated CO2have suggested that aphids may become more serious pests, although other studies have discerned no significant effects on sap‐feeding homopterans. However, few, if any of these experiments have fully considered the effects on pest population dynamics. Climate change is also considered from the perspective of changes in the distribution and abundance of species and communities. Marked changes in the distribution of well‐documented species – including Odonata, Orthoptera and Lepidoptera – in north‐western Europe, in response to unusually hot summers, provide useful indications of the potential effects of climate change. Migrant pests are expected to respond more quickly to climate change than plants, and may be able to colonize newly available crops/habitats. Range expansions, and the removal of edge effects, could result in the increased abundance of species presently near the northern limits of their ranges in the UK. However, barriers to range expansions, or shifts, may include biotic (competition, predation, parasitism and disease), as well as abiotic, factors. Climatic phenomena, ecosystem processes and human activities are interactive and interdependent, making long‐term predictions extremely tenuous. Nevertheless, it appears prudent to prepare for the possibility of increases in the diversity and abundance of pest species in the UK, in the context of climate change.
Microbial community structure and global trace gases
Authors: SCHIMEL JOSHUA P. , GULLEDGE JAY. 
Published: March 2003

AbstractGlobal change can affect soil processes by either altering the functioning of existing organisms or by restructuring the community, modifying the fundamental physiologies that drive biogeochemical processes. Thus, not only might process rates change, but the controls over them might also change. Moreover, previously insignificant processes could become important. These possibilities raise the question ‘Will changes in climate and land use restructure microbial communities in a way that will alter trace gas fluxes from an ecosystem?’ Process studies indicate that microbial community structure can influence trace gas dynamics at a large scale. For example, soil respiration and CH4 production both show ranges of temperature response among ecosystems, indicating differences in the microbial communities responsible. There are three patterns of NH4+ inhibition of CH4 oxidation at the ecosystem scale: no inhibition, immediate inhibition, and delayed inhibition; these are associated with different CH4 oxidizer communities. Thus, it is possible that changes in climate, land‐use, and disturbance regimes could alter microbial communities in ways that would substantially alter trace gas fluxes; we discuss the data supporting this conclusion. We also discuss approaches to developing research linking microbial community structure and activity to the structure and functioning of the whole ecosystem. Modern techniques allow us to identify active organisms even if they have not been cultivated; in combination with traditional experimental approaches we should be able to identify the linkages between these active populations and the processes they carry out at the ecosystem level. Finally, we describe scenarios of how global change could alter trace gas fluxes by altering microbial communities and how understanding the microbial community dynamics could improve our ability to predict future trace gas fluxes.
Responses of three generations of a xylem‐feeding insect, Neophilaenus lineatus (Homoptera), to elevated CO2
Authors: Brooks G. L. , Whittaker J. B. 
Published: March 2003

AbstractA population of the xylem‐feeding spittlebug, Neophilaenus lineatus, on blocks of natural vegetation transferred to large hemispherical chambers was studied over two generations with continuous exposure to elevated CO2 (600 ppm). The third generation was transferred from the blocks to potted Juncus squarrosus to enable measurements of fecundity. The principal food plant throughout was Juncus squarrosus. Survival of the nymphs was reduced by more than 20% in elevated CO2 relative to ambient (350 ppm) in both years of the main experiment. Elevated CO2 also delayed development by one or more nymphal instars in each year. Fecundity was not significantly affected.The C/N ratio of whole Juncus leaves was increased in elevated CO2 and the transpiration rates of the plants were reduced. These changes may have been responsible for the effect of elevated CO2 on spittlebug performance. However, other factors such as plant architecture and microclimate may also be important.
First‐year growth response of trees in an intact forest exposed to elevated CO2
Authors: Naidu Shawna L. , Delucia Evan. H. 
Published: March 2003

SummaryAlthough elevated atmospheric CO2 has been shown to increase growth of tree seedlings and saplings, the response of intact forest ecosystems and established trees is unclear. We report results from the first large‐scale experimental system designed to study the effects of elevated CO2 on an intact forest with the full complement of species interactions and environmental stresses. During the first year of exposure to ^ 1.5 Ë ambient CO2, canopy loblolly pine (Pinus taeda, L.) trees increased basal area growth rate by 24% but understorey trees of loblolly pine, sweetgum (Liquidambar styraciflua L.), and red maple (Acer rubrum L.) did not respond. Winged elm (Ulmus alata Michx.) had a marginally significant increase in growth rate (P = 0.069). These data suggest that this ecosystem has the capacity to respond immediately to a step increase in atmospheric CO2; however, as exposure time increases, nutrient limitations may reduce this initial growth stimulation.