bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Gas-Oil Ratio on the Behavior of Fractured Limestone Reservoirs
Authors: Jones-Parra Juan , Reytor Rafael Seijas 
Published: December 2007

Abstract
The porosities of fractured limestone reservoirs can be divided into two broad types in accordance with their effects on fluid distribution and fluid flow. In the coarse porosity, gravity segregation takes place freely and the resistance to fluid flow is very small. In the fine porosity there is no segregation and a high resistance to flow, and it has relative permeability characteristics similar to tight sandstones.
By analyzing the affect of the two porosities it is concluded that in some cases to recover the maximum amount of oil it is necessary to remove large quantities of gas from the reservoir by producing at high gas-oil ratios. In this manner the fine porosity is drained of its oil and the gas-oil contact drops slowly permitting higher production rates from the oil leg. Since this conclusion is contrary to widely accepted principles of conservation, a mathematical model (Fig. 1) was constructed to duplicate the conditions desired.
The behavior of the model indicates that under certain conditions it is possible to recover more oil by producing at high gas-oil ratios than by production at low gas-oil ratios, and that the rate of production is affected more by gas shut-offs than by the decrease in pressure (Figs. 2, 3, 4 and 5).

Introduction
It has been noted that certain limestone reservoirs behave in such a way as to indicate that there are two distinct types of porous spaces available for fluid storage and fluid flow. Regardless of the nature of these porous spaces the distinguishing characteristic is that in one type of porous space there is definite gravity segregation between the oil and the gas; while in the other, the gas evolved tends to remain distributed equally throughout the reservoir. For the sake of simplicity the porosity in which gravity segregation takes place at a fast enough rate to affect the behavior will be called "coarse porosity", while that in which this is not so will be termed "fine porosity".
Repressuring Improves Production in Mapiri Field
Authors: Clarke G.J. 
Published: December 2007

Abstract
Early production history of the U2 sand, Mapiri field, indicated that solution gas drive was the predominant producing mechanism, and by mid–1954 the reservoir pressure had dropped from the original 4,100 psi to below 3,000 psi for a production of approximately 3.25 million bbl, or 11 per cent of the oil initially in place. At this time it was predicted that the ultimate recovery by primary depletion would be only 5.9 million bbl or 19.6 per cent. Repressuring by gas injection was then initiated, and the reservoir pressure was raised to the original value of 4,100 psi by the end of 1957. It is planned to maintain the reservoir pressure at this level until depletion, at which time it is estimated that the recovery will be 32.4 per cent or 9,725,000 bbl, an increase of 3,825,000 bbl over recovery by primary depletion.
The performance to date has followed closely that predicted in 1954, and has indicated that gas has reentered solution in the oil leg, and that a sharp flood front has been formed. GOR's are consequently close to the solution ratio, and no serious channelling or gas breakthrough has occurred.

Introduction
Among the few major reservoirs in the Mapiri field, the U2 sand (Fig. 1), which lies at an average depth of 10,200 ft, was recognized at an early date as having good possibilities for a future gas injection project. This formation is a channel-type sand of Miocene-Oligocene age, in which the channel runs roughly north-south with the net sand thickness exceeding 60 feet in the center. The average thickness is 23.5 ft. Near the edges the thickness drops rapidly, being virtually unproducible in areas with less than 10 ft of net sand. The oil leg has a closure of about 600 ft and the water-oil contact is shown at an average depth of 9,450 ft below MSL.

Sand Characteristics
The sand is a fine to coarse-grained sandstone, hard, quartzitic and massive with some secondary cementation. It is heterogeneous with variations in vertical and horizontal permeability, and individual lenses vary widely in thickness. The porosity varies considerably both vertically and horizontally and the weighted average for the reservoir is approximately 12 per cent.
No effect of human chorionic gonadotropin treatment due to threatened abortion in early pregnancy for birth outcomes
Authors: Czeizel Andrew , Dudás István , Gidai János , Horváth-Puhó Erzsébet 
Published: December 2007

Abstract
Human chorionic gonadotropin (HCG) is used parenterally for treatment of threatened abortions and repeated spontaneous abortion in pregnant women. No controlled epidemiological studies of preterm birth and low birthweight newborns in pregnant women with HCG treatment have been published while the results of animal investigations were controversial. The data of 97 pregnant women with HCG treatment in the second and third months of pregnancy due to threatened abortion and/or previous spontaneous abortion(s) was compared with the data of other 38,054 pregnant women in the population-based large data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities. There was no difference in mean gestational age at delivery and birth weight, in addition the rate of preterm birth and low birthweight newborns. Parenteral HCG treatment in the early pregnancy due to threatened abortion did not associate with a higher risk for preterm births or low birthweight newborns. However, a higher occurrence of gestational diabetes was found in pregnant women with HCG treatment and there was a slight male excess among newborn infants (p=0.06).
Tabacco use in smokeless and smoking forms and its effect on periodontal health in India
Authors: Jacob Vimal , Vellappally Sajith , Smejkalova Jindra , Rajkumar Krishnan , Cermakova Eva , Fiala Zdenek , Somanathan Rakesh , Shriharsha Pilathadka 
Published: December 2007

Abstract
The aim of the present study was to establish the relationship between tobacco use and periodontal health in an adult sample in India. A cross-sectional population-based study was conducted in a province of southern India. A total of 805 subjects between the ages of 30 and 69 years were interviewed, and clinical examinations were made by three cooperating dentists. The examiners recorded oral mucosal findings, gingivitis, and the Community Periodontal Index of Treatment Needs index using a WHO-621 Trinity probe. Among the 805 participants, 72% were males and 28% were females. Among regular smokers, 98% were males and 2% were females. In the studied population, 64.6% visited the dentist only when they had some dental problems. Oral mucosal findings were present more in of the regular smokers and chewing tobacco users than in the non-consumers. The maximum findings from six sextants indicate that non-consumers exhibited higher rates of healthy periodontium and bleeding on probing but lower rates of pockets than tobacco consumers. The present analysis shows that tobacco use exerts a strong and chronic effect on periodontium and oral mucosa and reduces bleeding on probing.
Fulminant Wegener’s granulomatosis with multiorgan dysfunction
Authors: Sinkovic Andreja , Pahor Artur 
Published: December 2007

Abstract
Fulminant cases of Wegener’s granulomatosis (WG) with severe lung and kidney dysfunction may resemble pneumonia with sepsis and multiorgan dysfunction. Increased serum levels of antineutrophyl citoplasmic autoantibodies (c-ANCA) and proteinase 3 antibodies (PR3) confirm the correct diagnosis and are essential to start early immunosupressive treatment to improve the outcome. With the emphasis on diagnostic dilemmas, we present a 61-year old patient with fulminant WG, resembling pneumonia with sepsis and multiorgan dysfunction. After antibiotics and supportive measures increased serum levels of c-ANCA and PR3 confirmed the suspicion of WG and adequate immunosupressive treatment improved the patient’s condition. We concluded that it is important to include vasculitis in the differential diagnosis of unexplained multiorgan dysfunction, because only early adequate immunosuppressive therapy in combination with other resuscitation measures improves survival.
Plant functional group composition and large‐scale species richness in European agricultural landscapes
Authors: Liira Jaan , Schmidt Torsten , Aavik Tsipe , Arens Paul , Augenstein Isabel , Bailey Debra , Billeter Regula , Bukáček Roman , Burel Françoise , De Blust Geert , De Cock Raphaël , Dirksen Jolanda , Edwards Peter J. , Hamerský Roman , Herzog Felix , Klotz Stefan , Kühn Ingolf , Le Coeur Didier , Miklová Pavlina , Roubalova Martina , Schweiger Oliver , Smulders Marinus J.M. , van Wingerden Walter K.R.E. , Bugter Rob , Zobel Martin 
Published: December 2007

AbstractQuestion:Which are the plant functional groups responding most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricultural landscapes?Location:25 agricultural landscape areas in seven European countries.Methods:We examined the plant species richness and abundance in 4 km × 4 km landscape study sites. The plant functional group classification was derived from the BIOLFLOR database. Factorial decomposition of functional groups was applied.Results:Natural habitat availability and low land use intensity supported the abundance and richness of perennials, sedges, pteridophytes and high nature quality indicator species. The abundance of clonal species, C and S strategists was also correlated with habitat area. An increasing density of field edges explained a decrease in richness of high nature quality species and an increase in richness of annual graminoids. Intensive agriculture enhanced the richness of annuals and low nature quality species.Conclusions:Habitat patch availability and habitat quality are the main drivers of functional group composition and plant species richness in European agricultural landscapes. Linear elements do not compensate for the loss of habitats, as they mostly support disturbance tolerant generalist species. In order to conserve vascular plant species diversity in agricultural landscapes, the protection and enlargement of existing patches of (semi‐) natural habitats appears to be more effective than relying on the rescue effect of linear elements. This should be done in combination with appropriate agricultural management techniques to limit the effect of agrochemicals to the fields.
Plant phenology, leaf traits and leaf litterfall of contrasting life forms in the arid Patagonian Monte, Argentina
Authors: Campanella M. Victoria , Bertiller Mónica B. 
Published: December 2007

AbstractQuestion: Do coexisting plant life forms differ in overall phenology, leaf traits and patterns of leaf litterfall?Location: Patagonian Monte, Chubut Province, Argentina.Methods: We assessed phenology, traits of green and senesced leaves and the pattern of leaf litterfall in 12 species of coexisting life forms (perennial grasses, deciduous shrubs, evergreen shrubs).Results: We did not identify differences in phenology, leaf traits and patterns of leaf litterfall among life forms but these attributes contrasted among species. Independent of the life form, the maintenance of green leaves or vegetative growth during the dry season was mostly associated with leaves with high leaf mass per area (LMA) and high concentration of secondary compounds. Low LMA species produced low litterfall mass with low concentration of secondary compounds, and high N concentration. High LMA species produced the largest mass of leaf litterfall. Accordingly, species were distributed along two main dimensions of ecological variation, the dimension secondary compounds in leaves ‐ length and timing of the vegetative growth period (SC ‐ VGP) and the dimension leaf mass per area ‐ leaf litterfall mass (LMA ‐ LLM).Conclusions: Phenology, leaf traits and leaf litterfall varied among species and overlapped among life forms. The two dimensions of ecological variation among species (SC ‐ VGP, LMA ‐ LLM) represent distinct combinations of plant traits or strategies related to resource acquisition and drought tolerance which are reflected in the patterns of leaf litterfall.
Wind dispersal of alpine plant species: A comparison with lowland species
Authors: Tackenberg Oliver , Stöcklin Jürg 
Published: December 2007

AbstractQuestion: The prominent role of wind dispersal in alpine habitats has been recognized early but has rarely been quantified. The aim of this study is to compare wind dispersal under alpine and lowland conditions and to analyse whether differences are caused by species traits, e.g. terminal velocity of seeds (Vterm) or weather conditions.Location and Methods: We characterized wind dispersal potential of > 1100 Central European species using measured Vterm To quantify the habitat effect on wind dispersal, we measured meteorological key‐parameters and simulated dispersal distance spectra of nine selected species under typical alpine conditions (foreland of the Scaletta‐glacier, Switzerland) and typical lowland conditions (grassland in Bad Lippspringe, Germany).Results: Lowland species had higher Vterm compared to alpine species. However, this difference is absent when only species of species of open habitats are concerned. The meteorological measurements showed that the alpine habitat was mainly characterized by higher frequency and strength of updrafts. The simulations showed that under alpine conditions long distance dispersal occurred much more frequent.Conclusions: More than 50 % of the alpine species have a fair chance to be dispersed by wind over long distances, while this proportion is less than 25 % for species from open habitats in the lowland. The more prominent role of wind dispersal in alpine habitats is mainly a result of differences in environmental conditions, namely more intense vertical turbulence in the alpine habitat, and does not result from prominent differences in plant traits, namely Vterm, between alpine and lowland species.
Opposite responses of vascular plant and moss communities to changes in humus form, as expressed by the Humus Index
Authors: Lalanne Arnault , Bardat Jacques , Lalanne‐Amara Fouzia , Gautrot Thierry , Ponge Jean‐François 
Published: December 2007

AbstractQuestion:Does the distribution of plant species found in forests correlate with variation in the Humus Index (based on a ranking of humus forms) and, if so, do the species exhibit different responses according to phyletic lineages?Location:Paris Basin, France, with a temperate Atlantic climateMethods:Mosses and vascular plants (herbs, ferns) were inventoried in two broad‐leaved forests with contrasting soil conditions, where 15 and 16 sites were investigated, respectively. Variety of stand age and prevailing soil conditions were analysed in 5 plots and 20 sub‐plots in a grid at each site. Mantel tests were used to estimate correlations between the Humus Index and plant species richness, taking into account spatial autocorrelation.Results:The local (plot, sub‐plot) species richness of moss communities increased with the Humus Index, i.e. when humus forms shifted from mull to moder. The reverse phenomenon was observed in vascular communities. The opposite response of these two plant groups could be explained by opposite strategies for nutrient capture which developed in the course of their evolutionary history.Conclusions:Although not necessarily causative, the Humus Index predict fairly well changes in species richness which occur in forest vegetation, provided that phyletic lineages and geographical position are taken into consideration.
Theory of Magnetocrystalline Anisotropy and Magnetoelasticity in Transition‐metal Systems
Authors: Wu Ruqian 
Published: December 2007

AbstractProgresses of the first principles determinations of magnetocrystalline anisotropy of transition metal systems are reviewed in this chapter. It is clear that modern density functional approaches can provide reliable predictions for magnetic anisotropy energies of transition metal elements in different environments. The physical pictures extracted from theoretical data are indispensable for manipulations of magnetic anisotropy needed for technological applications. The present status of theoretical capability for studies of magnetostriction is also discussed.
Theory of Magnetocrystalline Anisotropy and Magnetoelasticity in 4
f
and 5
f
Metals
Authors: Johansson Børje , Brooks Michael S.S. 
Published: December 2007

Abstract
The origins and consequences of magnetocrystalline anisotropy energy (MAE) and magnetoelastic coupling in terms of the electronic structure of 4f and 5f elements are reviewed. In the heavy rare‐earth metals, the large molecular fields dominate and the MAE arises primarily from the crystalline electric field (CEF) with modifications due to the magnetostriction. In lighter rare earths, the molecular fields can be small and the MAE energy may then be dominated by multipolar interactions. The light actinide metals do not order magnetically, however, compounds of light actinide metals have a rich variety of magnetic ordering strongly influenced by the MAE energy and magnetoelastic effects, with CEF and multipolar interactions frequently being of the same order as exchange interactions.
Magnetism of Low‐dimensional Systems: Theory
Authors: Blügel Stefan , Bihlmayer Gustav 
Published: December 2007

Abstract
The article discusses the ground‐state properties of low‐dimensional magnets from the viewpoint of the electronic structure theory. The results presented arose from first‐principles calculations based on the material‐specific density‐functional theory. The focus lies on ultrathin films, wires, chains, and clusters with ferromagnetic, antiferromagnetic, and complex noncollinear magnetic phases. We discuss which systems become magnetic in low dimensions, their respective values for the spin and orbital magnetic moments, the magnetic ground‐state structures, and the magnetic anisotropy determining the orientation of the magnetization as well as how these properties are altered by respective substrates. The emphasis of the article lies in the development of the physical intuition by discussing the chemical trend of the properties of these magnets. Case studies of benchmark systems such as the magnetic surface alloy c(2 × 2)‐MnCu/Cu(100), Ni/Cu(100), which exhibits a magnetic reorientation transition, Fe/W(110), or Co chains on Pt(111) are discussed in more detail. A brief introduction to the basic concepts, notions, models, and theory is given, in order to provide a framework in which the surprising and partly peculiar results can be understood and interpreted. This includes the density‐functional theory, the Heisenberg model, the dipolar and magnetocrystalline anisotropy, the Dzyaloshinsky–Moriya interaction, the Stoner model, the role of the coordination number for the appearance of magnetism, and the estimation of the critical temperature.
Molecular Magnets: Phenomenology and Theory
Authors: Pederson Mark R. , Baruah Tunna 
Published: December 2007

Abstract

One special class of molecular magnets may be characterized as a finite array of exchange‐coupled transition metal ions that are held in place by ligands. Depending upon the relative strength of the exchange‐coupling and the spin‐orbit interactions, two different types of collective excitations can emerge as the low‐energy excitations. When spin‐orbit interactions are negligible, the lowest excitations are generally highly correlated and are associated with changes in spin‐coupling. Such systems may be described within a Heisenberg Hamiltonian. A description of how to calculate parameters for such a Hamiltonian is presented in this work. However, the phenomenon now referred to as resonant tunnelling of magnetization (RTM) occurs when the exchange coupling is sufficiently strong that the electronic ground state of the molecule may be well idealized as a single Ising‐like configuration of spin‐ordered metal centers. Within this idealization the spin‐orbit energy depends upon axis of spin‐quantization and the magnetic behavior can be described in terms of a simple anisotropy Hamiltonian. In this work we review these points through discussions of two nanostructures which here are respectively referred to as the V
15
spin molecular magnet and the Mn
12
‐Acetate anisotropic molecular magnet. The distinctions between these two classes are reviewed. In particular we emphasize that more complicated collective behaviors may occur in cases with either low‐energy electronic excitations or for cases where a decoupling of the kinetic‐exchange and spin‐orbit interaction energies does not occur. For the latter idealized case, it is still somewhat remarkable that the anisotropy Hamiltonians of many of the AMM may be computationally determined from second‐order perturbative analyses of the collinear spin‐ordered state within an all‐electron density‐functional formalism. The primary emphasis of this work is to provide many details related to the perturbative derivation of the Hamiltonian for an AMM. A combination of analytic and computational techniques are used in the derivation.
Interplay of Superconductivity and Magnetism
Authors: Takahashi Saburo , Maekawa Sadamichi 
Published: December 2007

Abstract
The interplay between superconductivity and ferromagnetism in superconductor/ferromagnet structures are discussed. One of the novel phenomena due to the proximity effect in the structures is a damped oscillation of the Cooper‐pair wavefunction in ferromagnets, leading to ferromagnetic Josephson π junctions. It is demonstrated that the π junctions are used as quantum bit (qubit) in quantum computing. Andreev reflection at superconductor/ferromagnet point contacts provides a powerful method for probing the spin‐polarization of various ferromagnets. Spin injection in hybrid nanostructures allows the electrical control of the interplay of superconductivity and magnetism.
Magnetization Dynamics Including Thermal Fluctuations: Basic Phenomenology, Fast Remagnetization Processes and Transitions Over High‐energy Barriers
Authors: Berkov Dmitri V. 
Published: December 2007

AbstractThis chapter is devoted to general problems arising as a result of numerical simulations of dynamical remagnetization properties taking into account thermal fluctuations. After a short introduction to the dissipation treatment in micromagnetics, we proceed with the detailed analysis of difficulties emerging when thermal fluctuations are included in the micromagnetic equation of motion, converting this deterministic differential equation into a stochastic one. Special attention is paid to thermal noise correlations, which can appear as a consequence of the discretization of a continuous micromagnetic problem. We conclude with a brief review of numerical methods developed for the study of the transitions over high‐energy barriers, that is, in the situation where standard Langevin dynamics fails due to prohibitively large computational times.