bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement of Blood-brain Barrier Permeability by Sodium Caprate
Authors: Ohnishi Toshimasa , Aida Kazunosuke , Awazu Shoji
Published: October 2002

We examined the effect of sodium caprate on the integrity of the tight junctions of brain capillary endothelial cells, using a modified in-situ brain perfusion technique. Model hydrophilic compounds used were [3H]mannitol, [14C]sucrose, [3H]PEG900, [3H]PEG4000, FITC-dextran 4000, FITC-dextran 20000 and FITC-dextran 70000.

The brain distribution volume of [14C]sucrose was significantly increased by sodium caprate in a concentration-dependent manner. The effective minimum concentration was 10 mM. Furthermore, the effects of sodium caprate on the distribution volumes of hydrophilic compounds, [3H]mannitol, [14C]sucrose, [3H]PEG900, [3H]PEG4000, FITC-dextran 4000, FITC-dextran 20 000 and FITC-dextran 70 000, showed a molecular weight dependence. A plot of apparent permeation clearance against diffusion coefficient values suggested that 20 mM sodium caprate induced pores so large that the above compounds could pass through the blood-brain barrier with negligible friction within the pore.

Our results showed that intracarotid sodium caprate perfusion could enhance the permeation of hydrophilic compounds through the blood-brain barrier.
Gastrointestinal Absorption of a New Reversible Proton Pump Inhibitor, YJA-20379-8, and its Pharmacokinetics after Oral Administration in Acetic Acid-induced Gastric Ulcer in Rats
Authors: Chung Su Y , Han Kye S , Kim Ho J , Kim Jonghan , Chang Man S , Lee Myung G
Published: October 2002

The absorption of YJA-20379-8 (3-butyryl-4-[5-(R)-(+)-methylbenzylamino]-8-ethoxy-1,7-naphthyridine) from various rat gastrointestinal segments was evaluated using in-situclosed-loops. The pharmacokinetics of the drug were also evaluated after oral administration to rats with acetic acid-induced gastric ulcer (AIURs). The concentrations of YJA-20379-8 in the biological samples were analyzed by HPLC.

The absorption of YJA-20379-8 from stomach and jejunum was fast, but approximately 50% of the drug was recovered from each segment at 24 h. The total areas under the plasma concentration-time curves from time zero to 24 h (AUC0-24h) were 161, 392, 233, 365, and 226 μg min mL−1 for stomach, duodenum, jejunum, ileum, and colon, respectively. After oral administration of the drug, the plasma concentrations and the resultant AUC0-12h were not significantly different between control and AIURs. The detection limits of YJA-20379-8 in human plasma and urine were 50 and 100ng mL−1, respectively.

The results suggest that modification of the oral dose of YJA-20379-8 may not be required in gastric ulcer patients if the present rat pharmacokinetic data could be extrapolated to man.
High-performance Liquid-chromatographic-Atmospheric-pressure Chemical-ionization Ion-trap Mass-spectrometric Identification of Isomeric C6-hydroxy and C20-hydroxy Metabolites of Methylprednisolone in the Urine of Patients Receiving High-dose Pulse Therapy
Authors: Vree Tom B , Maljers Louis , Van Den Borg Noud , Nibbering Nico M M , Verwey-Van Wissen Corrien P W G M , Lagerwerf Aart J , Maes Robert A A , Jongen P Jozef H
Published: October 2002

Fourteen metabolites of methylprednisolone have been analysed by gradient-elution high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS).

The compounds were separated on a Cp Spherisorb 5 μm ODS column connected to a guard column packed with pellicular reversed phase. The mobile phase was an acetonitrile-1.0% aqueous acetic acid gradient at a flow rate of 1.5 mL min−1.

The analysis gave a complete picture of parent drug, prodrugs and metabolites, and the α/β stereochemistry was resolved. The short (1-2h) elimination half-life of methylprednisolone is explained by extensive metabolism. The overall picture of the metabolic pathways of methylprednisolone is apparently simple—reduction of the C20 carbonyl group and further oxidation of the C20, C21 side chain (into C21COOH and C20COOH), in competition with or in addition to oxidation at the C6 position.
Chromatographic Resolution, Chiroptical Characterization and Preliminary Pharmacological Evaluation of the Enantiomers of Butibufen: a Comparison with Ibuprofen
Authors: Hoult J R S , Jackson B R , Benicka E , Patel B K , Hutt A J
Published: October 2002

Enantiomeric resolution of butibufen has been achieved on a cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase with hexane-isopropanol-trifluoroacetic acid, 100: 1.2: 0.02 (v/v/v) as mobile phase at a flow rate of 1.0 mL min−1.

Semi-preparative isolation of the enantiomers then chiroptical characterization indicated that the order of elution was (-)-R- before (+)-S-butibufen. When tested for their effects on the cyclooxygenase and 5-lipoxygenase pathways of eicosanoid metabolism in calcium ionophore-activated rat peritoneal leukocytes it was found that (+) -S-butibufen inhibited generation of thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) (cyclooxygenase pathway), with an IC50 of 1.5 μ (approx.), whereas the (-)-R enantiomer was essentially inactive. Neither enantiomer inhibited the 5-lipoxygenase pathway. In this regard, (+)-S-butibufen was approximately five times less potent as a cyclooxygenase inhibitor than (+)-S-ibuprofen.

These results show the enantiomeric specificity and pathway selectivity of this novel non-steroidal anti-inflammatory drug.
k-Opioid Receptors Behind the Blood-brain Barrier are Involved in the Anti-hypertensive Effects of Systemically Administered k-Agonists in the Conscious Spontaneously Hypertensive Rat
Authors: Shen S , Ingenito A J
Published: October 2002

We have shown previously that chronic intrahippocampal, intraperitoneal and subcutaneous administrations of non-peptide opioid receptor agonists induced depressor responses in the spontaneously hypertensive rat (SHR). However, it is not clear whether the hypotensive effect of systemic administration involves κ receptors behind the blood-brain barrier. In this study, the relative roles of central vs peripheral κ-opioid receptors in the hypotensive effect of κ-agonists was examined in conscious SHRs following chronic subcutaneous administration of two selective κ-agonists, BRL 52656 which freely penetrates the blood-brain barrier, and BRL 52974 which has only limited ability to do so.

Initial studies determined the dose-response relationship for each of the two drugs given intraperitoneally twice a day, while monitoring systolic arterial pressure (SAP), mean arterial pressure (MAP) and heart rate (HR) measured by the tail-cuff method. Both drugs caused biphasic arterial pressure responses, with lower doses of BRL 52656 causing depressor effects and higher doses resulting in pressor effects. By contrast, lower doses of BRL 52974 caused pressor effects and higher doses depressor effects. The biphasic effects occurred with BRL 52656 from 0.01 to 3.0 mg kg−1 and that for BRL 52974 from 0.1 to 30 mg kg−1. In subsequent studies the drugs were infused chronically, subcutaneously via osmotic minipumps over a 14-day period, BRL 52656 at 0.2 or 0.5 mg kg−1/day and BRL 52974 at 0.2 mg kg−1/day. At lower doses, BRL 52656 decreased SAP, MAP and HR but at higher doses only bradycardia was observed. BRL 52974 given chronically subcutaneously over 14 days had no significant effects on arterial pressure and decreased heart rate only after seven days of treatment.

Collectively, the results established that only the κ-agonist, which gained access to the central nervous system, lowered arterial pressure and heart rate, whereas the compound with limited ability to cross the blood-brain barrier was ineffective at equivalent doses. The complex dose-response pattern found with both drugs suggests that K-agonists have central hypotensive and bradycardic actions at low doses but at higher doses a mixture of both central and peripheral actions leads to hypertension and tachycardia.
Immunomodulatory Effect of Arctigenin, a Lignan Compound, on Tumour Necrosis Factor-α and Nitric Oxide Production, and Lymphocyte Proliferation
Authors: Cho Jae Youl , Kim Ae Ra , Yoo Eun Sook , Baik Kyong Up , Park Myung Hwan
Published: October 2002

We have investigated the immunomodulatory effects of arctigenin, a dibenzyl butyrolactone lignan compound, on tumour necrosis factor (TNF)-α and nitric oxide (NO) production, and lymphocyte proliferation.

Arctigenin inhibited strongly TNF-α production by lipopolysaccharide-stimulated murine macrophage RAW264.7 and differentiated human macrophage U937 with IC50 values of 5.0 and 3.9 μM, respectively, without displaying cytotoxicity. The TNF-α inhibitory effect of arctigenin in lipopolysaccharide-triggered RAW264.7 cells was increased by co-treatment with several known TNF-α inhibitors. It also potently attenuated T and B cell proliferation stimulated by concanavalin A and lipopolysaccharide in a dose-dependent manner with IC50 values of 2.9 and 14.6 μM, respectively. In contrast, the compound showed a different pattern in lipopolysaccharide- and interferon (IFN)-γ-induced NO production from RAW264.7 cells. Arctigenin inhibited NO release by IFN-γ signal, whereas it significantly enhanced lipopolysaccharide-triggered NO production in RAW264.7 cells.

The results suggested that arctigenin may regulate immune responses in activated macrophages and lymphocytes including TNF-α and NO production and lymphocyte proliferation.
Mathematical model of diesel fuel injection equipment incorporating non-linear fuel injection
Authors: Lee H-K , Russell M F , Bae C S
Published: October 2002

Stringent legislation on vehicle noise and pollutant emissions has created increasingly severe demands on the fuel injection equipment fitted to automotive diesel engines. In particular, the use of high pressure across smaller nozzle holes to reduce particulate emissions has increased the effects of non-linear compression of the fuel in the passages and volumes in the systems. The mathematical model to simulate high pressure injection system needs to incorporate this high-pressure non-linear behaviour. Condensation, which is continuous across the fuel phase boundary, has been introduced to replace the pressure. This non-linearity in compression has been incorporated into the wave equations by using a non-linear equation of state where the bulk modulus is assumed to change linearly with pressure. The calculation methods for wave disturbances and losses have been investigated and improved methods are presented. The model has been validated with a rotary pump—pipe—nozzle system, but it can be equally applied to other designs such as unit injector and common rail systems. Even though the linear model prediction is in accord with experimental results, the nonlinear model predictions of injection timing and peak line pressure are significantly better.
Dynamic simulation of a single-cylinder diesel engine including dynamometer modelling and friction
Authors: Zweiri Y. H. , Whidborne J. F. , Seneviratne L. D.
Published: October 2002

The recent drive to reduce emissions and improve efficiency means that there is a real need for improved models for the simulation of direct-injection diesel engines. With a view to improving the transient fuel control, a model of the non-linear transient dynamics of a generic direct-injection single-cylinder diesel engine is developed in order to predict the instantaneous engine speed and torque. The instantaneous crankshaft speed is determined from the solution of the engine—external load dynamics equation, where the engine torque is tracked on a crank angle basis. The model is based on an analysis of all the major forces internal to the engine and dynamometer. The friction components of the piston assembly, the bearings, the valve train, the pumping and the pumps are also included. The model is implemented in MATLAB:SIMULINK, and simulation results of both transient and steady state dynamics are presented. The simulation results of the instantaneous engine speed are compared with measured data, and it is seen that there is excellent agreement between them.
Aerodynamic modelling of multistage compressor flow fields Part 1: Analysis of rotor-stator-rotor aerodynamic interaction
Authors: Hall E J
Published: October 2002

The primary purpose of this study was to investigate improved numerical techniques for predicting flows through multistage compressors. The vehicle chosen for this study was the Pennsylvania State University Research Compressor (PSRC). The PSRC facility consists of a 3 1/2-stage axial flow compressor which shares design features which are consistent with embedded stages of modern gas turbine engine axial flow compressors. In Part 1 of this two-part paper, several computational fluid dynamics techniques were applied to predict both steady and unsteady flows through the PSRC facility. Interblade row coupling via a circumferentially averaged mixing-plane approach was employed for steady flow analysis. A mesh density sensitivity study was performed to define the minimum mesh requirements necessary to achieve reasonable agreement with the experimental data. Time-dependent flow predictions were performed using a time-dependent interblade row coupling technique. These calculations evaluated the aerodynamic interactions occurring between rotor 2, stator 2 and rotor 3 for the PSRC rig.
Towards the control of a powered orthosis for people with muscular dystrophy
Authors: Rahman T , Ramanathan R , Stroud S , Sample W , Seliktar R , Harwin W , Alexander M , Scavina M
Published: October 2002

The paper describes the development of a passive/active orthosis for people with limited anti-gravity strength in their arms. This is symptomatic of conditions such as muscular dystrophy and spinal muscular atrophy. A passive orthosis was designed and developed using linear elastic elements. The system is being tested with children with disabilities and preliminary results are encouraging. An RT200 robot was also used as a test-bed for an active orthosis. The robot was instrumented with a six-axis force/torque sensor at the end-effector. The force acted as the input to the robot. The robot kinematics and dynamics were modelled. A number of control schemes were implemented on the test-bed including force proportional to velocity and acceleration; these schemes were evaluated with two subjects.
Vibrational Energy Distribution of SiO Produced via the Chemical Activation of SiH3OH
Authors: Takahara Atsuko , Araki Ryuta , Tezaki Atsumu , Matsui Hiroyuki
Published: October 2002

Vibrationally excited SiO has been observed in the 193 nm photolysis of N2O/SiH4 mixtures with and without great excess of H2. While SiH4 + O(1D) (1) has been known to produce SiO in the mixture without H2, present kinetic analyses of SiO and OH indicate that SiH3 + OH (2) is responsible for the SiO production in the mixture with H2. The observed nascent vibrational distributions, approximated by Boltzmann distributions of Tv = 5200 ± 660 K for (1) and 2800 ± 790 K for (2), are reasonably accounted for by a statistical model assuming multi-step unimolecular decomposition of hot silanol.
A Correlation between Boiling Points and Refractive Indices of Organic Compounds : A Possible Role of Fluorine Atoms in Intermolecular Interactions
Authors: Katagiri Toshimasa , Uneyama Kenji
Published: October 2002

Correlations between boiling points and refractive indices of halogenated organic compounds are described. We note fair to excellent linear relationships between the boiling points of the compounds and the refractive indices.
Syntheses of Mycophenolic Acid and Its Analogs by Palladium Methodology
Authors: Lee Youngmin , Fujiwara Yasunari , Ujita Katsuji , Nagatomo Miki , Ohta Hiroshi , Shimizu Isao
Published: October 2002

Syntheses of mycophenolic acid (MPA, 1) and its analogs were carried out using palladium-catalyzed Heck carbonylation and olefination. Thus, the reaction of 2-bromo-3,5-dimethoxybenzyl alcohol (4) in toluene under carbon monoxide at 180 °C in the presence of palladium catalyst using sodium carbonate as a base gave 5,7-dimethoxyphthalide (5) in 88% yield. The phthalide 7 was converted to 6-iodo-5,7-dimethoxy-4-methylphthalide (8). Reaction of aromatic iodide 8 with isoprene and dimethyl malonate in the presence of palladium(0) catalyst gave the three component coupling product 9, which was converted into 1 in three steps. 4-NorMPA (16) and 4-homoMPA (22) were synthesized similarly.
Upper‐tropospheric flow transitions during rapid tropical cyclone intensification
Authors: Davidson Noel E. , Kar Sajal K.
Published: October 2002

Evidence is presented of upper‐tropospheric flow transitions during rapid tropical cyclone (TC) intensification. Transitions occur when a mid‐latitude upper trough, with a wind maximum on its eastern flank, located well to the west of a storm, relaxes as anticyclogenesis occurs near to, and east of, its equatorward extremity. During these episodes, the flow is characterized by weak inertial stability. It is proposed that this allows extremely rapid and large‐scale changes to occur in the upper‐level environment of the storm. The new environment provides seemingly favourable conditions of reduced wind shear, development of a downstream trough very near the storm, and access for the storm outflow to the tropical easterlies and mid‐latitude westerlies.

A global shallow‐water model, initialized with objective analyses at the 200 hPa level, is used to study the phenomenon, and the interaction between the environmental flow and local sources of mass and momentum. The sources are used to represent the effects of inner‐core deep convection in the outflow layer. Using the technique it seems possible, as a first approximation, to isolate the environment from the vortex development. It is shown that flow transitions are mostly independent of the presence of the TC. Short term, local enhancement of divergence over the TC occurs during superposition of environmentally‐induced divergence with the mass source. However, formation of the upper‐level vortex is the distinguishing feature of the intensification, and this occurs during an upper‐tropospheric flow transition. It is shown: (i) that the reduction in ventilation is associated with flow transitions, (ii) that these transitions directly influence the development of the upper vortex of the TC via downstream development of a weak environmental trough, and (iii) that the transitions indirectly influence the vortex development by allowing the momentum and mass sources to operate more efficiently to assist in both the development of the vortex and the outflow channels at small radii.

Several examples of flow transitions during intensification are presented to support the proposed hypothesis. Copyright © 2002 Royal Meteorological Society.
Stratified flow over a mountain with a gap: Linear theory and numerical simulations
Authors: Zängl G.
Published: October 2002

Linear theory and numerical simulations are used to investigate gap flows. Both gaps embedded in a long mountain ridge and gaps located between two isolated mountain peaks are considered. The study mainly focuses on level gaps so as to isolate three‐dimensional effects from two‐dimensional gravity‐wave propagation. Special attention is given to qualitative differences between the linear and the nonlinear flow regimes, the linear regime being defined by the absence of gravity‐wave breaking.

In the linear regime, wind and pressure perturbations along a level gap axis are found to be qualitatively similar to those over a mountain ridge or peak, but of lower amplitude and longer horizontal wavelength. They are caused by vertically propagating gravity waves radiating from the mountain ridges (peaks) towards the gap axis and by low‐level confluence within the gap. In the nonlinear regime, however, these two processes are of minor importance due to upstream blocking and low‐level wave breaking. Instead, the pressure difference across the mountain ridge primarily drives the gap flow, which tends to be decoupled from the flow over the adjacent ridge. In contrast to the linear regime, gap winds are as strong as or even stronger than the winds over the mountain ridge. Surface friction is found to reduce the near‐surface wind speed more strongly for mountain ridges than for gaps. Copyright © 2002 Royal Meteorological Society.
Transition Economies: Performance and Challenges
Authors: Svejnar Jan
Published: October 2002

I present data and assess the first twelve years of the transition from plan to market. Transformations have taken place, but the income gap between the transition and advanced economies has widened. Transition countries further east have performed worse than those further west, but policies matter. All countries carried out quickly Type I reforms, such as macroeconomic stabilization, price liberalization, small-scale privatization, and breakup of state-owned enterprises. They differed in Type II reforms, such as large-scale privatization and development of banking and legal systems. Countries that developed a functioning legal framework and corporate governance have performed better than others.
Environmental Policy Since Earth Day I: What Have We Gained?
Authors: Freeman A. Myrick
Published: October 2002

I review the data on costs and benefits of the major environmental laws passed during the 1970s. The winners in terms of benefit-cost analysis include: getting lead out of gasoline; controlling particulate air pollution; reducing the concentration of lead in drinking water; and the cleanup of hazardous waste sites with the lowest cost per cancer case avoided under Superfund The losers include: mobile source air pollution control; water pollution control; and many of the regulations and cleanup decisions taken under the Federal Insecticide, Fungicide, and Rodenticide Act, the Toxic Substances Control Act, the Safe Drinking Water Act, and Superfund.
What Really Matters in Auction Design
Authors: Klemperer Paul
Published: October 2002

The most important issues in auction design are the traditional concerns of competition policy-preventing collusive, predatory, and entry-deterring behavior. Ascending and uniform-price auctions are particularly vulnerable to these problems. The Anglo-Dutch auctiona hybrid of the sealed-bid and ascending auctions-may perform better. Effective antitrust is also critical. Notable fiascoes in auctioning mobile-phone licenses, television franchises, companies, eletricty, etc., and especially the European “third-generation” (UMTS) spectrum auctions, show that everything depends on the details of the context. Auction design is not “one size fits all.”
Retrospectives: Captains of Industry
Authors: Dixon Robert
Published: October 2002

This paper traces the origin and use of the term “captains of industry.” Introduced by the Scottish historian and essayist Thomas Carlyle in the midnineteenth century, its meanings and associations were very different from today. For Carlyle, they were ferocious instruments of social control who would force the unemployed and idle to work and, if necessary, discipline them. The term, if not the meaning, rapidly entered the popular lexicon. It was brought into economics by Francis Walker, the first president of the AEA, who argued that the captain of industry was a fourth factor of production and the engine of industrial progress. While many other writers shared this view, Veblen did not.
Policy Watch: The Federal Employees Health Benefits Plan
Authors: Feldman Roger , Thorpe Kenneth E , Gray Bradley
Published: October 2002

This feature contains short articles on topics that are currently on the agendas of policymakers, thus illustrating the role of economic analysis in illuminating current debates. Suggestions for future columns and comments on past ones should be sent to C. Eugene Steuerle, c/o Journal of Economic Perspectives, The Urban Institute, 2100 M Street NW, Washington, D.C. 20037.
Oligopsony and Monopsonistic Competition in Labor Markets
Authors: Bhaskar V , Manning Alan , To Ted
Published: October 2002

We argue that models of oligopsony or monopsonistic competition provide insights and explanation for many empirical phenomena in labor markets. Using a simple model with job differentiation and preference heterogeneity, we illustrate how such models can be employed to explain the existence of wage dispersion, the persistence of labor market discrimination, market failures in the provision of training and the anomalous employment effects of minimum wages.
Perspectives on the Future of Oil
Authors: Bentley R.W. , Booth R.H. , Burton J.D. , Coleman M.L. , Sellwood B.W. , Whitfield G.R.
Published: October 2002

This paper assesses the risk of near-term oil shortages due to resource limits.

Part I reviews the basics of the problem, including: • definitions, • broad quantities of oil available, • a simple model of how production develops from a group of fields, • actual production profiles of countries past peak.

Part II examines the adequacy of the data available for estimating the total quantity of conventional oil, discussing separately: • the oil in reserves, • oil expected from reserves growth, and • oil yet-to-find.

A contrast is made between the data used by the oil industry, and that available in the public domain.

Part III outlines approaches taken by a variety of groups to model the future supply of oil. These groups include Campbell/Laherrère, the IEA, USGS, the EU, and some oil economists.

Part IV presents oil production forecasts from a number of these groups for some specific countries; for the “Rest-of-the World”, and for the world as a whole.

In Part V, the scope for non-conventional oil, and also gas, to offset a decline in conventional oil is examined.

Finally, in Part VI, some wider implications of the situation are presented.

The general arguments of the paper are: • It is useful to define conventional oil by recovery method. • Oil production in a region goes over peak when flow from new sources cannot compensate for the declining flow from existing sources. • Public domain reserves data hold only proved reserves, and contain serious errors. • Industry data are more reliable, and hold (proved + probable) reserves. • Much of ‘reserves growth’ is simply the increase from proved to (proved + probable). • The world's conventional oil ultimate is probably between 2,000 and 2,700 Gb. • But find rates are low, so peaking dates are not affected by high ultimates.

The conclusions of the paper therefore are: • Non-OPEC oil production is currently close to its resource-limited peak. • The world's all-oil resource-limited peak is likely within about a decade. • These resource limits are likely to have serious economic and political repercussions.
Temperature/Pressure Changes Impact Hydrates from Coast to Slope, Northern Gulf of Mexico
Authors: Lowrie Allen , Moffett Susan , Jenkins Linda
Published: October 2002

The northern Gulf of Mexico's passive margin is interrelated and synergistic with both regional and local inputs. Regional inputs may be thought of as deterministic and may include eustatic sea-level oscillations, sediment deposition from erosion of uplifted areas, climate above and below sea level, compression and dewatering of sediments once deposited, and related tectonics. The synergistic sum of these deterministic processes impacts the occurrence of natural gas and their hydrate phases.

Along the foot of the continental slope, compression is transmitted to the sediment beneath and down-dip. Hydrates occur when suitable cold temperatures and high pressures are present. In water depths of ∼4 km, the hydrate stability zone (HSZ) may be up to 1 km thick. A prograding slope imparts regional pressures. Local pressures may be sufficient to catalyze the gas-to-hydrate phase change. Further compression may cause the zone to heat and/or to generate fractures, promoting hydrate disassociation and/or escape.

The impact of a salt/shale lateral wedge or diapir (or both) entering the zone can be observed in several ways. Increased salinity raises the gaseous phase, thereby reducing hydrate existence. Increased heat also augments gaseousness. Note that shales dissipate heat and that the top of a salt diapir can be cool, even though overall salt is a heat conductor relative to sediments. Migrating salt/shale can promote fracturing, where the size and rate of migration determine the dimensions and frequency of fractures. As gases enterfractions, gas may expand and possibly block further gas entrance. Local sediment shattering and thermal anomalies could obviate the gas expansion effect.

As the Louann Salt, which is located over the slope-sediment wedge, advances basinward, the amount of compression rises. Thus, temperatures and pressures change and the pattern of gases/hydrates are dynamic. Specific local predictions are subtle and may be regarded as probabilistic in model development.

Equal subtlety is experienced along the ocean/land contact. Hydrate existence is determined by gas chemistry, whether methane or ethane is present. As the sea level oscillates, temperatures and pressures also oscillate. Landward, the HSZ limit during sea-level highs is disassociated, and a new, more basinward HSZ is established. Specific landward HSZ limit is determined by the gas chemistry.
Modelling of Re-Working Carbonate Sediments under Strong Tidal Current Setting
Authors: Nakayama Kazuo , Baba Kei , Matsuda Fumiaki , Tsukui Osamu , Yoshida Takasumi , Iwahashi Ryotaro
Published: October 2002

A numerical model has been developed which successfully simulated not only carbonate precipitation but also re-sedimentation of carbonate material under a strong tidal current environment. Carbonate reservoirs in oil fields, offshore Abu Dhabi, were deposited under such environments, so that there is difficulty to predict the reservoir heterogeneity in the exploitation stage where no more appraisal wells would be available. A numerical process model is the only solution for predicting reservoir heterogeneity under such conditions; however, most of the carbonate models that have been developed in recent years take account only of the generation of carbonate material under specified depositional environments. Sedimentation by tidal currents, which is similar to clastic sedimentation, was also neglected in the models because of its lesser importance for carbonate reservoir characterization. The present model estimates in detail the distribution of tidal current velocity in the field by using a commercial flow model with multi-layered systems. For a simplification, only the bed load transportation was taken into account for transportation of carbonate sediments. It was possible to formulate the effect by bed load transportation as a function of water depth, grain size and current velocity at each point for a given grid system. For simulation of a longer period of ancient sedimentation, the ‘Mean Field Method’ and ‘Error Tolerance Level’ are introduced for effective calculation of the equivalent result using longer time conditions than daily tidal cycles. The model developed was tested against the present-day geologic situation from the Bahamas where many of the input parameters can be observed. Then it is applied to the real oil field, offshore Abu Dhabi. We could reproduce the geologic sequences that are conceptually similar to the observations in both cases. The model thus has the potential to predict ancient reservoir quality at the petroleum exploitation stage.
Inverse Methods and Uncertainties in Stratigraphy and Basin Analysis
Authors: Lerche Ian
Published: October 2002

Quantitative models are often constructed in attempts to uncover the evolution of stratigraphic and basinal systems from present-day data. These models contain parameters related to the imposed boundary and initial conditions, as well as intrinsic parameters connected to the intrinsic evolution of the systems through equations of state taken to describe dynamical, chemical and flow processes. The use of inverse methods to determine these parameters is often undertaken by optimizing the model development in order to minimize the disagreement of the model with observations. We show here that several methods of optimization are possible, and we compare and contrast their intrinsic assumptions and relative numerical speeds. The problems of finite data sampling, with uncertainty of precision, accuracy, sensitivity and sampling frequency and distribution also play a major role in attempting to obtain the parameters required. In addition, different choices of control functions chosen for the minimization are shown to lead to different optimum parameter values, so that there is also a uniqueness problem in any inverse method chosen. The three methods considered here are simulated annealing, genetic algorithms, and the fast path tomographic method. Newton line search methods and Simplex solvers are also mentioned, but they are already known to be very much slower than any of the other three methods. The implications of the investigation reported here are that extreme care must be exercised in using data, models, and methods in attempts to uncover the evolution of a system. Failure to be absolutely sharp in what is being done can easily lead to overstating the results of an inverse method beyond its level of ability to resolve the problem. And the manner in which a problem fails to be resolved is also one of the crucial factors to be determined from any inverse method applied to such problems.
Sidetrack and Recompletion Risks in Oil Fields. V. Sidetrack Uncertainties and Parameter Sensitivities
Authors: Lerche I. , Noeth S.
Published: October 2002

Models of total estimated reserves, of future selling price per barrel of oil, and of the chances that undertaking a sidetrack will not kill a producing well, and that the sidetrack will also be successful, all provide parameter values that are used to estimate the worth of undertaking the sidetrack. However, such parameter values are themselves uncertain and therefore contribute uncertainty to the sidetrack worth. To decide to undertake a sidetrack requires that some idea is to hand of the sensitivity of the assessed worth to parameter variations, so that one knows where to place effort to minimize the uncertainty of the estimated worth. In this paper we show how models of such effects can be incorporated into the evaluation of sidetrack worth and its sensitivity to parameter uncertainties. In addition we show how the relative contributions of ranges and distribution types of the uncertainties can be evaluated. In this way one knows precisely where to focus efforts to improve matters prior to undertaking the sidetrack, and one also determines the range of likely outcomes with some statistical sharpness should one decide for or against undertaking the sidetrack. Several simple numerical illustrations are given to demonstrate the influence of different choices of parameter models on the assessment of the best worth and its uncertainty for a sidetrack situation.
Value Change in Oil and Gas Production: I. Additional Information at Fixed Cost but Variable Resolution Probability
Authors: Lerche I. , Noeth S.
Published: October 2002

The worth of producing an oilfield is governed by future uncertainties that are related both to changes in reservoir behaviour and to on-going production. Costs and selling price of product also influence the decision to produce further reserves. Acquisition of new information, and decisions to produce based on interpretations of the new information, are usually undertaken to maximise the total worth of an oilfield to a corporation, or to minimise total loss. Because acquisition of new information is not cost-free, future further development decisions are influenced by such costs and also the anticipated new worth assuming the acquired data resolve, at least partially, any uncertainty in expected future reserves. This paper is the first in a series designed to illustrate how one can use probabilistic risking methods to handle such uncertainties. A simple deterministic assessment is made of when new information is worthwhile. With the sole exception of the probability of a successful value change resulting from new information, all other parameters describing the oilfield are taken to be precise and it is also taken that new information resolves unequivocally the residual worth of the oilfield. These conditions will be gradually relaxed in future papers to illustrate their importance to the decision-making process. Systematically varying the probability of success, which is the sole unknown, allows one to assess when anticipated new net gains would exceed those by continuing production of the field the way it is. In particular, one can determine how high the success probability needs to be for such an eventuality and compare this value against a corporate-mandated Minimum Acceptable Chance in order to make a decision consistent with the corporate constraints. To assess the uncertainty, measures of bulk volatility and also of upside and downside volatile risk are used as yardsticks. Simple numerical examples are provided to show how these factors can be quantified and used in oilfield development and production situations.
Value Change in Oil and Gas Production: II. Additional Information with Variable Cost and Variable Success Probability
Authors: Lerche I. , Noeth S.
Published: October 2002

This paper in the series dealing with development options for producing oil fields considers the effects of uncertainty in parameters influencing the future expected value of the filed worth depending on strategies for field development based on the acquisition of information in relation to business “as is”. Three simple illustrations show how the uncertainty in estimated ranges of parameters for the business “as is” situation, the potential development under acquisition of information, and the combined uncertainty of both scenarios, can be quantified and an informed decision made as to how to proceed based upon the information available and also the uncertainty of that information. In addition, a quantification of the sensitivity of worth to the uncertainty in the parameters is provided so that one can quickly determine where to concentrate effort to narrow the ranges of the most important parameters causing the uncertainty in estimates of worth. This advantage allows one to ignore less important parameters and spend time effort and money on narrowing the ranges of factors determining the major fuzziness in estimates of worth.
Sidetrack and Recompletion Risks in Oil Fields. VIII. Reviving the Nearly Dead
Authors: Lerche I. , Noeth S.
Published: October 2002

The decision to undertake rejuvenation of an oilfield that is close to extinction depends on the estimates that one makes of the likely enhanced reserves to be recovered by such a treatment relative to the proven reserves that are still producible. One trades certainty of returns, albeit small, for uncertain returns that could be significant relative to the small residual oil being produced. In addition, there is always the chance that undertaking the rejuvenation of the nearly dead field will be unsuccessful and /or kill the current known production. This paper shows how one can assess the best course of action to take dependent on the range of uncertainty for the estimated rejuvenation production and also dependent on the estimates of both a successful rejuvenation treatment and the chances of killing the known production. Sensitivity charts show which parameter is causing the greatest uncertainty in estimates of total worth both with and without the rejuvenation treatment and, therefore, where one should concentrate in order to narrow the range of uncertainty of likely profit. The decision to revive the nearly dead, or let natural death take its course for an almost exhausted production, can then be made with a greater certainty that a rejuvenation attempt will produce more worthwhile gains. Several numerical illustrations are given to illuminate these points.
Relationships between Heating Value and Lignin, Moisture, Ash and Extractive Contents of Biomass Fuels
Authors: Demirbas Ayhan
Published: October 2002

Various fuel characteristics, such as moisture, ash, lignin, holocellulose and extractive contents of different biomass species were determined on ash-free dry weight and extractive-free dry weight basis to find out relationship, if any, between ash and extractive content with the higher heating value. Moisture in biomass generally decreases its heating value. Ash and extractive content are two important parameters directly affecting the heating value. High ash content of a plant part makes it less desirable as fuel, whereas high extractive content adds to its desirability. Again the heat content, which is a very important factor affecting utilization of any material as a fuel, is affected by the proportion of extractives present in it. Extractives raised the higher heating values of the biomass samples.
Energy Exploitation of Agricultural Residues in Crete
Authors: Vamvuka D. , Tsoutsos T.D.
Published: October 2002

The island of Crete is a typical Mediterranean area with a high biomass potential, the major part of which is still unexploited or irrationally exploited, but at the same time has a problematic energy supply during the high touristic season. In this paper the energy content of the biomass potential is estimated, as a parameter to alleviate the energy system of the island. The exploitation of biomass is studied with reference to the following aspects:

The major residue production (olive kernel, husks – citrus fruits, grapes), branches (olive tree, citrus tree, grape tree); The qualitative analysis (proximate, ultimate, calorific value, ash analysis) of samples of basic agricultural residues of the Cretan production (vineshoots, olive tree wood and citrus, olive kernel).
Low Frequency Sounds in Dwellings: A Case Control Study
Authors: van den Berg Frits (G.P.)
Published: October 2002

The purpose of this study is to systematically assess the level and spectral distribution of low frequency (LF) sounds in dwellings. Measurements of broad and narrow band sound levels have been made in 36 Dutch dwellings in 1998. In 19 dwellings there were complaints about LF noise, in 17 others no complaints had been reported. According to measured broad band and spectral levels complainants' dwellings can be divided into three categories with ‘considerable’, ‘some’ and ‘no’ LF sound. Measured levels and scores on proposed LF noise criteria in complainants' dwellings as a group however are not significantly different from dwellings without complaints. In cases' dwellings more narrow band LF components are present, but on average at a lower level compared to controls' dwellings.
Annoyance of Low Frequency Noise and Traffic Noise
Authors: Mortensen Frank Rysgaard , Poulsen Torben
Published: October 2002

The annoyance of different low frequency noise sources was determined and compared to the annoyance from traffic noise. Twenty-two subjects participated in laboratory listening tests. The sounds were presented by loudspeakers in a listening room and the spectra of the low frequency noises were dominated by the frequency range 10 Hz to 200 Hz. Pure tone hearing thresholds down to 31 Hz were also measured. Eighteen normal hearing subjects and four subjects with special low-frequency problems participated in the tests.
Evaluation of Low-Frequency Noise in Dwellings. New Polish Recommendations
Authors: Mirowska Marianna
Published: October 2002

This paper presents new Polish recommendations for the estimation of low-frequency noise (LFN) penetrating into dwellings from appliances installed inside or outside the building (Recommendation No 358/98 of the Building Research Institute). The proposed new assessment criteria were based on the measurement data of annoying noises, investigation of the effects of noise on the health of the exposed inhabitants, laboratory tests of thresholds of narrow and broad-band noise perception and a review of the present literature. In order to assess the noise spectra measured in dwellings, the A10 characteristic has been accepted as the rating curve. Its levels, L, for one-third-octave bands are determined by the relation LA10 = 10 – kA, where kA is the A-weighting. Low-frequency noise is annoying when the sound pressure levels of the noise exceed the A10 curve and simultaneously exceed the background noise level by more than 10 dB for tonal noise and by 6 dB for broadband noise.
Low-Frequency Noise Emission of Finnish Large-Calibre Weapons
Authors: Pääkkönen Rauno , Parri Asko , Tiili Juhani
Published: October 2002

Noise emissions from large-calibre weapons were measured in a shooting area according to Danish guidelines. At a distance of 100 m the peak levels (LCpeak) were 146–159 dB for the bazooka, 148–163 dB for the 155-mm cannon, 147–151 for the mortar, 128–141 dB for the antiaircraft cannon and 146–155 for the 1-kg TNT explosion. The C-weighted exposure levels (LCE1s) were 127–136 dB for the bazooka, 134–140 dB for the 155-mm cannon, 122–129 dB for the mortar and 104–115 dB for the antiaircraft cannon. Sound directivity proved to be a significant parameter for weapons. The most prominent octave bands were typically lower than 100 Hz.
Assessment of Noise with Low Frequency Line Spectra — Practical Cases
Authors: Sørensen Michael Friis
Published: October 2002

Many small power plants have been built in Denmark in recent years. These plants are often situated near dwellings giving rise to complaints about annoyance of low frequency noise and vibration indoors. Normally the annoying low frequency noise is in the frequency range 10–200 Hz. Since it is created by combustion engines the noise has a line spectrum. In Denmark the A-weighted total level in the frequency range 10–160 Hz LpA, LF is used for assessment and legislation about low frequency noise exposure in dwellings. From our experience solving practical low frequency noise and vibration problems LpA,LF seems to overestimate the annoyance of very low frequency noise whereas noise with the major spectral content near 160 Hz seems to be underestimated. This problem is discussed based on our experience.
Occupational Disease Induced by Hand Transmitted Vibration — The Relationship between Characteristics of Case and Kind of Tool
Authors: Yamada Shin'ya , Sakakibara Hisataka
Published: October 2002

In statistics of workers' accidents under the Compensation Law in Japan, the number of cases of occupational disease due to hand-arm vibration in private enterprises was 2,120 from 1994 to 1997. These consisted of 712 cases (33.6%) by rock drill operation, 372 (17.5%) by chain saw, 323 (15.2%) by pick hammer, 241 (11.4%) by concrete vibrator, 80 (3.8%) by concrete breaker, 61 (2.9%) by bush cutter, 50 (2.4%) by chipping hammer, and 51 (2.4%) by portable grinder, among others. The clinical features of vibration disease differ greatly with the kind of tool. Each tool has its own characteristic of an engineering nature, which, combined with many factors in operation at the workplace, will induce characteristic clinical features. Nine cases from our laboratory cases are discussed in this connection.
The Influence of the Concentration of Cyclohexane Radicals Bonded with an Si100 Silica Gel Surface upon the Retention of Some Hydrocarbons in Gas Chromatography
Authors: Nasuto R.
Published: October 2002

Four adsorbents based on silica gel Si100 with chemically bonded cyclohexane have been prepared as stationary phases for gas chromatography. The concentrations of cyclohexane radicals thus bonded with the silica gel surface were 1.35, 3.35, 4.17 and 6.02 μmol/m2, respectively. Separation of aliphatic (C6–C12), aromatic (benzene, toluene and m-xylene) and some polar organic compounds (chloroform, ethylene chloride, chlorobenzene, p-chlorotoluene and ethyl benzene) by gas chromatography using columns packed with the prepared adsorbents was studied. It was concluded that the retention of some compounds was increased on the column packed with an adsorbent of 1.35 μmol/m2 concentration relative to that measured on the column packed with the unmodified silica gel. On columns packed with adsorbents with a higher bonded phase concentration than 1.35 μmol/m2, the retention times of all the compounds studied chromatographically decreased with an increase in the bonded phase concentration.