bluuebunny/crossref_metadata_2025 huggingface dataset:
Circumstellar discs around solar mass stars in NGC 6611
Authors: Oliveira J. M. , Jeffries R. D. , van Loon J. Th. , Littlefair S. P. , Naylor T.
Published: March 2005

We have performed IZJHKL′ observations in NGC 6611, the young cluster that ionizes the Eagle Nebula. We have discovered a rich pre-main sequence concentrated around the O-stars in the cluster. As measured by their L′-band excesses, at least 58±5 per cent of the pre-main sequence objects (0.45 < M < 2 M⊙) have circumstellar discs. By comparing this disc frequency with frequencies determined for regions where the pre-main sequence stars are subject to less ionizing radiation, we find no evidence that the harsher environment of NGC 6611 (approximately an order of magnitude more ionizing Lyman continuum radiation than the Trapezium cluster) significantly hastens the dissipation of circumstellar discs around solar mass stars.
Dynamic Structural Integrity Assessment for Offshore Structures
Authors: Zhao W. , Burdekin F. M.
Published: March 2005

The paper initially presents the results of a dynamic structural integrity assessment for fracture of cracked plate and tubular members under sinusoidal loading at different frequencies. The behavior of cracked members and joints in an offshore structure under wave loading (Stokes 5th order or gridded wave) is then examined. Global structural dynamic analyses of a whole offshore jacket were carried out as the first step, then, a set of sub-models of joints was selected from chosen locations and modeled with through thickness cracks under the loading extracted from the global analysis. The sub-model dynamic results were analyzed to obtain the fracture response in terms of variation of crack tip opening displacement (CTOD). Related values of K, J and their rates were also calculated. These results are used to give guidance on methods for design and assessment of structural integrity under dynamic loading.
Numerical Study of Incompressible Flow About Transversely Oscillating Cylinder Pairs
Authors: Jester W. , Kallinderis Y.
Published: March 2005

A numerical investigation of incompressible flow about transversely oscillating cylinder pairs is performed. Both tandem and side-by-side arrangements undergoing both flow-induced and forced transverse oscillations are considered. A second-order projection scheme is used to solve the 2-D incompressible Navier Stokes equations and a staggered approach is used to couple flow and structural response. Automatic mesh deformation and adaptation are used to handle arbitrary motion of the bodies. Comparisons with experimental results indicate that the present numerical method can capture complex interference and flow–structure interaction phenomena. Specifically, results are presented that demonstrate wake galloping effects, in which a cylinder in the wake of another experiences large flow-induced vibration over a wide range of flow velocities, and the presence of an experimentally observed secondary peak in the flow-induced vibration of rigidly connected cylinders in a tandem arrangement. An explanation of this secondary peak is provided by employing appropriate visualization of the unsteady flow. Results for forced oscillation of a pair of cylinders in a side-by-side arrangement are also presented that show the effect of phase angle on the wake structure behind the cylinder pair.
Mooring Dynamics Phenomena Due to Slowly-Varying Wave Drift
Authors: Bernitsas Michael M. , Matsuura Joa˜o Paulo J. , Andersen Torgrim
Published: March 2005

The effects of slowly varying wave drift forces on the nonlinear dynamics of mooring systems have been studied extensively in the past 30 years. It has been concluded that slowly varying wave drift may resonate with mooring system natural frequencies. In recent work, we have shown that this resonance phenomenon is only one of several possible nonlinear dynamic responses of mooring systems to slowly varying wave drift excitation. We were able to reveal new phenomena based on the design methodology developed at the University of Michigan for autonomous mooring systems and treating slowly varying drift as an external time-varying force. In this paper, the U of M methodology is used systematically to reveal seven phenomena induced by mean and slowly varying drift forces; one of those is resonance. Conceptually, numerous qualitatively different behaviors may be induced. The next step toward the comprehensive identification of such phenomena is taken by introducing the method of harmonic balance to study nonautonomous mooring systems.
A Combined Riser Mooring System for Deepwater Applications
Authors: Hogg Brendan , Harte Annette M. , Grealish Frank
Published: March 2005

For deepwater developments, riser and mooring system requirements become a significant factor in the cost of the overall field development. Therefore, methods for reducing the riser and mooring design requirements and minimizing the cost of these systems become increasingly important. This paper presents the design methodology for a combined riser mooring (CRM) system and demonstrates the feasibility of the system for a test case application in a deepwater development offshore West of Africa. The CRM system offers significant benefits over the independent riser and mooring systems, namely reduced riser dynamics, reduced vessel offsets, a smaller seafloor footprint and system installation prior to the arrival of the FPSO.
Comparison of Analytical and Centrifuge Model Tests for Suction Caissons Subjected to Combined Loads
Authors: Clukey Edward C. , Aubeny Charles P. , Murff James D.
Published: March 2005

A plastic limit formulation was previously developed for estimating caisson uplift in cohesive soils under general conditions of vertical, horizontal, and inclined loading. The formulation considers the effects of soil shear strength profile, caisson aspect ratio, anchor line attachment depth, and load inclination angle. Load capacity predictions from the plastic limit analyses are compared to data measured in seven centrifuge tests in which model caissons are subjected to purely vertical and inclined loads of various orientations. The effect of a bevel at the caisson tip is also investigated. Comparisons are also made to finite element predictions.
Physical Model Experiments to Assess the Hydrodynamic Interaction Between Floating Glacial Ice Masses and a Transiting Tanker
Authors: Gagnon R.
Published: March 2005

An array of nine fabricated models comprised of three different shapes, with three model sizes for each shape, has been utilized in tow tank tests to investigate the hydrodynamic interaction between glacial ice masses and a transiting tanker. A generic model tanker was towed past free-floating ice mass models at various speeds and proximities. The ice masses were either spherical, pyramidal or cylindrical in shape. The influence of waves of various periods and wave heights was also investigated. Sway and surge of the ice masses in response to the tanker passage were measured as the primary indicators of the hydrodynamic interactions. Notable among the many observed behaviors was that waves tended to enhance the degree of sway. Also, in the scenarios tested the magnitude of surge speed and sway speed were <10% of the tanker speed, and would therefore not significantly reduce impact speed during collisions. The program results are intended for use primarily in the validation of IOT’s numerical simulations of bergy bit/ship collisions, but can also serve as a validation database for simulation studies by other researchers.
Strength of Minimum Structure Platforms Under Ship Impact
Authors: Grewal Gage S. , Lee Marcus M. K.
Published: March 2005

This paper presents the findings of a numerical investigation into the strength of minimum structure platforms subject to a ship impact. The study has identified important design issues that should be addressed in order to improve the survivability and continued serviceability of minimum structures after a ship impact. It was found that, due to a lack of research effort, design guidelines governing ship impact on minimum structures are lacking in comparison with conventional jacket platforms. In particular, requirements governing the minimum amount of plastic energy absorption in minimum structures are not clearly defined. Ship impact analyses were therefore carried out in order to compare their structural integrity with that for a jacket under ship collision conditions and to evaluate the effects on their ultimate strength. The study not only established any degradation of system strength, but has also determined the amount of plastic energy absorption under various impact scenarios.
Development of chemically assisted etching method for GaAs-based optoelectronic devices
Authors: Gaillard M. , Rhallabi A. , Elmonser L. , Talneau A. , Pommereau F. , Pagnod-Rossiaux Ph. , Bouadma N.
Published: March 2005

Chemically assisted ion beam etching of GaAs-based materials using Cl2 reactive gas was has been experimentally and theoretically examined. The primary effort was the design of an etching system for high reproducibility and improved throughput. Characteristics of the etching process, i.e., etch rate, etch profiles, and surface morphology as a function of etching parameters, i.e., substrate temperature, Cl2 flow rate, ion current density, and energy are reported. In addition, we have analyzed the etched surfaces qualitatively by Auger electron spectroscopy, and quantitatively by atomic force microscopy. The developed process yielded stoichiometric and smooth GaAs surfaces. Moreover, in order to understand the mechanism of the Cl2 etching reaction with GaAs, a simulation of the etch profile evolution with time as function of etching parameters was carried out. Simulations were compared with experimentally derived data and were found to be in good agreement. Finally, the developed process was successfully applied to the fabrication of ridge waveguides GaAs/GaAlAs lasers with cw optical characteristics similar to wet chemical etched lasers.
Highly accurate coating composition control during co-sputtering, based on controlling plasma chromaticity
Authors: Anguita J. V. , Thwaites M. , Holton B. , Hockley P. , Holton B. , Rand S.
Published: March 2005

Highly accurate control of sputtering processes is of paramount importance to industry. Plasma diagnostic equipment based on spectroscopic methods such as optical emission spectroscopy (OES) have been commercially available for many years and have the ability to deliver a high level of accuracy. Despite this, their complexity, demand for operator time, and disregard for the vast majority of the optical emission spectrum have rendered them as unpopular, and they are rarely used in manufacturing lines. This article introduces the measurement of the chromaticity of the plasma as a new method of analysis, as an alternative to OES. This method is simple, while maintaining a high level of sensitivity. Chromaticity monitors a wide range of the optical emission spectrum, obtaining a large amount of process information. It also averages and simplifies the data, making them easier to analyze.
High resolution electron energy loss spectroscopy study of Fomblin Z-tetraol thin films
Authors: Sung Dougyong , Gellman Andrew J. , Gui Jing , Ma Xiaoding
Published: March 2005

High resolution electron energy loss spectroscopy has been used to obtain vibrational spectra of Fomblin Z-tetraol lubricant films on a commercial magnetic hard disk. The energy loss intensities of the ν(CF2) stretching mode are roughly independent of scattering angle up to angles of Δθ<14° indicating that they are excited by impact scattering. As a consequence there is little information that can be gleaned from the spectra about molecular orientation on the surface. A negative ion resonance enhances the energy loss cross section of the ν(CF2) stretching mode at the impact energy of EI=4eV. It is possible that this resonance is associated with the known sensitivity of fluorocarbons to electron induced dissociation. Annealing the disk sample to T=700K causes a dramatic decrease in the intensity of C–F stretching modes and an increase of the loss features due to C–H stretching. This indicates that the Fomblin Z-tetraol has decomposed and is exposing the a-CHx overcoat on the magnetic media surface.
Erosive wear properties of Ti–Si–N nanocomposite coatings studied by micro-sandblasting
Authors: Zeng X. T. , Goto Takashi , Zhao L. R. , Ding X. Z. , Liew S. C. , Li G. Y.
Published: March 2005

Superhard Ti–Si–N nanocomposite coatings were deposited on high speed steel substrates by a combined dc/rf unbalanced reactive magnetron sputtering process. Erosion tests using angular Al2O3 particles (mixture of cylindrical and trihedral particles) with an average particle size of 17μm were carried out using air-sand blasting to investigate the erosive wear properties of the coating. For benchmarking purpose, three other hard or superhard coatings, namely, TiN, nanolayered TiN/NbN and multiple-layer CrTiN/NbN have also been evaluated under the same experimental conditions. In the air pressure range used in this work from 1.3 to 4.2 bar, the nanocomposite Ti–Si–N coatings demonstrated extremely low steady-state erosion rates compared with the other three coatings evaluated. However, pinholes associated with the particle impacts were observed in the tests of Ti–Si–N coating, which propagated with the increase of air pressure or particle velocity and the particle impingement duration, and eventually led to coating failure. The erosive failure mechanism and the dependence of the erosion rate on coating properties and experimental conditions were discussed based on the microstructural analysis.
Electrical properties of Cu/Ta interfaces under electrical current stressing
Authors: Liao Chien-Neng , Liou Kuen-Ming
Published: March 2005

Electrical properties of sputtered Cu/Ta interfaces under electric current stressing were measured using four-terminal Kelvin structures. It has been found that the Cu/Ta interfacial resistivity was effectively reduced by applying hydrogen plasma treatment on Ta surface prior to deposition of Cu thin film. Besides, a marked and irreversible reduction of contact resistance was observed when applying an electric current through the Cu/Ta interface above some threshold levels. A thermally assisted junction breakdown process is believed to be responsible for the huge contact resistance drop. The conduction mechanism through the Cu/Ta interfaces is also briefly discussed.
Shallow and thermally stable Pt∕W∕Au Ohmic contacts to p-type InGaSb
Authors: Wang S. H. , Robinson J. A. , Mohney S. E. , Bennett B. R.
Published: March 2005

We report a shallow, thermally stable Pt∕W∕Au (2∕50∕145nm) Ohmic contact to p-InGaSb prepared using a brief (NH4)2S rinse as part of the premetallization surface treatment. Cross-sectional transmission electron microscopy reveals that the Pt∕W∕Au contacts have better thermal stability than previously reported Pd∕W∕Au contacts, with the Pt∕W∕Au contacts remaining shallow even after they are aged at 250°C for 3days. The specific contact resistances of as-deposited Pt∕W∕Au, Pd∕W∕Au, Co∕W∕Au, Cu∕W∕Au, W∕Au, Cr∕W∕Au, and Ag∕W∕Au contacts are also compared, and the (NH4)2S rinse is found to partially relieve Fermi level pinning at the contact∕p-InGaSb interface.
Hydrogen pumping by austenitic stainless steel
Authors: Zajec Bojan , Nemanič Vincenc
Published: March 2005

In the present study, hydrogen sorption and desorption kinetics close to equilibrium were investigated in a pinched-off AISI 316 steel cell by a sensitive pressure-rise method. The pressure was monitored with a spinning rotor gauge (SRG) just before the pinch-off and after it for 6months at two stabilized temperatures: 25°C and 55°C. The preprocessing of the cell (of uniform wall thickness 0.15mm volume 125cm3, and inner surface 460cm2) consisted of baking at 200°C for 109h with several evacuation cycles to ultrahigh vacuum (UHV). The quantity of released hydrogen during the bake-out procedure equaled the average concentration change ΔC=2.8×1017at.Hcm−3. After the pinch-off intentionally done in the high vacuum range where hydrogen represented the residual atmosphere, surprisingly the hydrogen pressure slowly declined from the initial p(328K)=3.7×10−4mbar, with an initial rate dp∕dt=−5.5×10−11mbar∕s and later attained a stable value, which could be termed the equilibrium. In similar reported experiments, where valving-off began in the UHV, the dp∕dt was always positive and constant over several orders of magnitude in pressure. During 6months of measurements, a sudden temperature jump from 25°Cto55°C or back was applied a few times to investigate the stability of the equilibrium or the impact on the pressure course. The most plausible explanation of the results is given along with discussion whether hydrogen permeated through the cell wall or if it was absorbed in the cell wall.
Effect of Ar post-oxidation annealing on oxide–4H-SiC interfaces studied by capacitance to voltage measurements and photoemission spectroscopy
Authors: Hijikata Y. , Yaguchi H. , Yoshida S. , Ishida Y. , Yoshikawa M.
Published: March 2005

The effect of post-oxidation annealing in Ar atmosphere (Ar POA) on 4H-SiC–oxide interfaces has been studied by capacitance to gate-bias voltage (C–V) measurements and photoemission spectroscopy (PES). It was found from the C–V measurements that the shift of the C–V curve disappears when the Ar POA temperature is higher than 600 °C. On the other hand, angle-resolved x-ray photoelectron spectroscopy measurements revealed that the thickness of the intermediate layers containing Si1+ oxidation states observed at the interfaces decreases abruptly when the Ar POA temperature exceeds 500 °C. In ultraviolet photoelectron spectra, O2p peaks were changed by Ar POA at temperatures higher than 600 °C, which is the temperature where the shift of the C–V curve disappears in C–V measurements. This shows that the change in O2p bonding by Ar POA is the origin of the shift observed in C–V characteristics. A model of structural changes in the interfaces by Ar POA has been proposed based on the results of PES measurements and those of C–V measurements.
Development of Immunoglobulin M Capture Enzyme-Linked Immunosorbent Assay To Differentiate Human Flavivirus Infections Occurring in Australia
Authors: Taylor Carmel , Simmons Russell , Smith Ina
Published: March 2005

We report the development of a flavivirus immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (MAC-ELISA) which improves the determination of an infecting flavivirus serotype over that by current serological methods. A panel of 165 IgM-positive sera from flavivirus patients with specific diagnostic results was tested by the flavivirus MAC-ELISA using a panel of 10 antigens. For 134 of these sera (81.2%), the highest reactivity was demonstrated against the infecting virus, which was consistent with the original diagnostic result. Specific antibody reactions inconsistent with the original diagnosis were found for six sera (3.6%). In our experience, the flavivirus-serotyping ELISA provides a rapid and accurate alternative to other serological tests, such as hemagglutination inhibition, for the specific diagnosis of flavivirus infections.
Application of Monoclonal Antibodies in Functional and Comparative Investigations of Heavy-Chain Immunoglobulins in New World Camelids
Authors: Daley L. P. , Gagliardo L. F. , Duffy M. S. , Smith M. C. , Appleton J. A.
Published: March 2005

Of the three immunoglobulin G (IgG) isotypes described to occur in camelids, IgG2 and IgG3 are distinct in that they do not incorporate light chains. These heavy-chain antibodies (HCAbs) constitute approximately 50% of the IgG in llama serum and as much as 75% of the IgG in camel serum. We have produced isotype-specific mouse monoclonal antibodies (MAbs) in order to investigate the roles of HCAbs in camelid immunity. Seventeen stable hybridomas were cloned, and three MAbs that were specific for epitopes on the γ chains of llama IgG1, IgG2, or IgG3 were characterized in detail. Affinity chromatography revealed that each MAb bound its isotype in solution in llama serum. The antibodies bound to the corresponding alpaca IgGs, to guanaco IgG1 and IgG2, and to camel IgG1. Interestingly, anti-IgG2 MAbs bound three heavy-chain species in llama serum, confirming the presence of three IgG2 subisotypes. Two IgG2 subisotypes were detected in alpaca and guanaco sera. The MAbs detected llama serum IgGs when they were bound to antigen in enzyme-linked immunosorbent assays and were used to discern among isotypes induced during infection with a parasitic nematode. Diseased animals, infected with
Parelaphostrongylus tenuis
, did not produce antigen-specific HCAbs; rather, they produced the conventional isotype, IgG1, exclusively. Our data document the utility of these MAbs in functional and physiologic investigations of the immune systems of New World camelids.
Acellular Pertussis Vaccine Protects against Exacerbation of Allergic Asthma Due toBordetella pertussisin a Murine Model
Authors: Ennis Darren P. , Cassidy Joseph P. , Mahon Bernard P.
Published: March 2005

The prevalence of asthma and allergic disease has increased in many countries, and there has been speculation that immunization promotes allergic sensitization.Bordetella pertussisinfection exacerbates allergic asthmatic responses. We investigated whether acellular pertussis vaccine (Pa) enhanced or preventedB. pertussis-induced exacerbation of allergic asthma. Groups of mice were immunized with Pa, infected withB. pertussis, and/or sensitized to ovalbumin. Immunological, pathological, and physiological changes were measured to assess the impact of immunization on immune deviation and airway function. We demonstrate that immunization did not enhance ovalbumin-specific serum immunoglobulin E production. Histopathological examination revealed that immunization reduced the severity of airway pathology associated with sensitization in the context of infection and decreased bronchial hyperreactivity upon methacholine exposure of infected and sensitized mice. These data demonstrate unequivocally the benefit of Pa immunization to health and justify selection of Pa in mass vaccination protocols. In the absence of infection, the Pa used in this study enhanced the interleukin-10 (IL-10) and IL-13 responses and influenced airway hyperresponsiveness to sensitizing antigen; however, these data do not suggest that Pa contributes to childhood asthma overall. On the contrary, wild-type virulentB. pertussisis still circulating in most countries, and our data suggest that the major influence of Pa is to protect against the powerful exacerbation of asthma-like pathology induced byB. pertussis.
Daily variations in oxygen consumption, antioxidant defenses, and lipid peroxidation in the gills and hepatopancreas of an estuarine crab
Authors: Maciel F E , Rosa C E , Santos E A , Monserrat J M , Nery L E.M
Published: March 2005

This study identified daily variations in oxygen consumption, antioxidant-defense system, and lipoperoxidation in the gills and hepatopancreas of the crab Chasmagnathus granulata (Dana, 1851) (Decapoda, Brachyura). In gills, oxygen consumption was higher in the early afternoon and in the middle of the night (p < 0.05). Lipoperoxidation level and non-proteic sulfhydryl content were higher in the middle of the night (p < 0.05). The enzyme glutathione-S-transferase showed lower activity at the end of photophase and higher values during the night (p < 0.05). The enzyme catalase did not show daily variation in activity (p > 0.05). Oxygen consumption in the hepato pancreas showed a similar profile to that in gills, i.e., higher values in the early afternoon and the middle of the night. Glutathione-S-transferase activity and lipoperoxidation levels showed significant variation, with lower values during the afternoon and peaks in the middle of the night (p < 0.05). Catalase activity was significantly higher (p < 0.05) in the middle of the night. The non-proteic sulfhydryl content remained fairly constant (p > 0.05). The results showed daily variations in aerobic metabolism of the gills and hepatopancreas of C. granulata, with concomitant oxidative damage (lipoperoxidation), but with differences between tissues. Whereas in the gills the defense system focused on catalase and non-proteic sulfhydryl, in the hepatopancreas other non-enzymatic components and other antioxidant enzymes besides catalase and glutathione-S-transferase might be involved.
Effects of constrained females on offspring sex ratios ofNasonia vitripennisin relation to local mate competition theory
Authors: King B H , D'Souza J A
Published: March 2005

Empirical studies of how constrained females affect sex ratio are few. Constrained females are those that can produce only sons (e.g., in haplodiploid species, females that have not mated or older females that have used up their sperm). In the parasitoid wasp Nasonia vitripennis (Walker, 1836), failure to mate soon after emergence increased the probability of a female being constrained and thus affected sex ratio directly. Local mate competition theory shows that whether a female is constrained can also affect sex ratio indirectly by affecting what sex ratio other females produce. However, this was not the case in N. vitripennis. A female's sex ratio was not significantly different when she was with another young mated female versus a virgin female or an old mated female depleted of sperm. These results suggest that N. vitripennis females may be unable to recognize whether another female is constrained. The increased proportion of sons in response to other females relative to when alone did not persist the day after exposure.
ENERGY INTAKE, MEAL FREQUENCY, AND HEALTH: A Neurobiological Perspective
Authors: Mattson Mark P.
Published: March 2005

▪ Abstract  The size and frequency of meals are fundamental aspects of nutrition that can have profound effects on the health and longevity of laboratory animals. In humans, excessive energy intake is associated with increased incidence of cardiovascular disease, diabetes, and certain cancers and is a major cause of disability and death in industrialized countries. On the other hand, the influence of meal frequency on human health and longevity is unclear. Both caloric (energy) restriction (CR) and reduced meal frequency/intermittent fasting can suppress the development of various diseases and can increase life span in rodents by mechanisms involving reduced oxidative damage and increased stress resistance. Many of the beneficial effects of CR and fasting appear to be mediated by the nervous system. For example, intermittent fasting results in increased production of brain-derived neurotrophic factor (BDNF), which increases the resistance of neurons in the brain to dysfunction and degeneration in animal models of neurodegenerative disorders; BDNF signaling may also mediate beneficial effects of intermittent fasting on glucose regulation and cardiovascular function. A better understanding of the neurobiological mechanisms by which meal size and frequency affect human health may lead to novel approaches for disease prevention and treatment.
Ficoll and dextran vs. globular proteins as probes for testing glomerular permselectivity: effects of molecular size, shape, charge, and deformability
Authors: Venturoli Daniele , Rippe Bengt
Published: March 2005

Polydisperse mixtures of dextran or Ficoll have been frequently used as molecular probes for studies of glomerular permselectivity because they are largely inert and not processed (reabsorbed) by the proximal tubules. However, dextrans are linear, flexible molecules, which apparently are hyperpermeable across the glomerular barrier. By contrast, the Ficoll molecule is almost spherical. Still, there is ample evidence that Ficoll fractional clearances (sieving coefficients) across the glomerular capillary wall (GCW) are markedly higher than those for neutral globular proteins of an equivalent in vitro Stokes-Einstein (SE) radius. Physical data, obtained by “crowding” experiments or measurements of intrinsic viscosity, suggest that the Ficoll molecule exhibits a rather open, deformable structure and thus deviates from an ideally hard sphere. This is also indicated from the relationship between (log) in vitro SE radius and (log) molecular weight (MW). Whereas globular proteins seem to behave in a way similar to hydrated hard spheres, polydisperse dextran and Ficoll exhibit in vitro SE radii that are much larger than those for compact spherical molecules of equivalent MW. For dextran, this can be partially explained by a high-molecular-size asymmetry. However, for Ficoll the explanation may be that the Ficoll molecule is more flexible (deformable) than are globular proteins. An increased compressibility of Ficoll and an increased deformability and size asymmetry for dextran may be the explanation for the fact that the permeability of the GCW is significantly higher when assessed using polysaccharides such as Ficoll or dextran compared with that obtained using globular proteins as molecular size probes. We suggest that molecular deformability, besides molecular size, shape, and charge, plays a crucial role in determining the glomerular permeability to molecules of different species.
Role of the renin-angiotensin system in the pathogenesis of preeclampsia
Authors: Shah Dinesh M.
Published: March 2005

Preeclampsia is a hypertensive disorder unique to pregnancy with consistent involvement of the kidney. The renin-angiotensin system (RAS) has been implicated in the pathogenesis of preeclampsia. In the gravid state, in addition to the RAS in the kidney, there is a tissue-based RAS in the uteroplacental unit. Increased renin expression observed both in human preeclampsia and in a transgenic mouse model with a human preeclampsia-like syndrome supports the concept that activation of the uteroplacental RAS, with angiotensin II entering the systemic circulation, may mediate the pathogenesis of preeclampsia. A novel disease paradigm of the two-kidney one-clip (2K-1C) Goldblatt model is presented for preeclampsia, wherein the gravid uterus is the clipped “kidney” and the two maternal kidneys represent the unclipped kidney. Validation of the 2K-1C Goldblatt model analogy requires evidence of elevated angiotensin II in the peripheral circulation before vascular maladaptation in preeclampsia. Convincing evidence of the elevation of angiotensin II in preeclampsia does not exist despite the fact that much of vascular pathogenesis appears to be due to angiotensin type I (AT1) receptor activation. Vascular maladaptation with increased vasomotor tone, endothelial dysfunction, and increased sensitivity to angiotensin II and norepinephrine in manifest preeclampsia may be explained on the basis of angiotensin II-mediated mechanisms. Recently, novel angiotensin II-related biomolecular mechanisms have been described in preeclampsia. These include AT1and bradykinin B2receptor heterodimerization and the production of an autoantibody against AT1. Various organ systems with a predilection for involvement in preeclampsia are each a site of a tissue-based RAS. How angiotensin II-mediated mechanisms may explain the primary clinical-pathological features of preeclampsia is described. Future investigations are proposed to more precisely define the role of activation of the uteroplacental RAS in the mechanisms underlying preeclampsia.
Protein Z in normal pregnancy
Authors: Stiller Ruth , Roos Malgorzata , Zimmermann Roland , Quack Loetscher Katharina C.
Published: March 2005

Changes in the coagulation and fibrinolytic systems during pregnancy lead to a higher risk of thromboembolism. These changes include the increase of many clotting factors, as well as a significant fall in activity of fibrinolytic proteins, such as protein C. Protein Z is a vitamin-K-dependent plasma glycoprotein and inhibits the activation of factor X by serving as a cofactor to a plasma proteinase inhibitor. Protein Z deficiency has recently been reported in women with unexplained early fetal losses, and antibodies to protein Z can contribute to adverse pregnancy outcomes. The aim of this study was to determine the range of protein Z in normal pregnancies at different gestational weeks in a cross-sectional and a longitudinal setting. In the longitudinal study we found a 20% increase (p=0.006) of protein Z from first trimester to delivery and a 30% decrease (p<0.0001) 6 to 12 weeks after delivery. In the cross-sectional study these findings were reproducible. In summary, our data show a progressive increase in protein Z levels with gestational age in normal pregnancies and a return to normal levels around 6 to 12 weeks postpartum. The normal increase of protein Z during pregnancy may balance the increase of clotting factors to protect pregnant women from thrombosis.
Suppression of rat breast cancer metastasis and reduction of primary tumour growth by the small synthetic urokinase inhibitor WX-UK1
Authors: Setyono-Han Buddy , Stürzebecher Jörg , Schmalix Wolfgang A. , Muehlenweg Bernd , Sieuwerts Anieta M. , Timmermans Mieke , Magdolen Viktor , Schmitt Manfred , Klijn Jan G. M. , Foekens John A.
Published: March 2005

The serine protease uPA (urokinase-type plasminogen activator) and its receptor uPAR (CD87) are often elevated in malignant tumours, hence, inhibition of this tumour-associated plasminogen activation system provides an attractive target for therapeutic strategies. WX-UK1, a derivative of 3-aminophenylalanine in the L-conformation with inhibitory antiproteolytic properties, was tested for its specificity spectrum using specific chromogenic paranitroanilide peptide substrates. The corresponding D-enantiomer of WX-UK1 was used as a control. The anti-tumour and anti-metastatic (number of lung foci and weight of the axillary lymph nodes) properties were studied by subcutaneous administration of WX-UK1 to Brown Norwegian (BN) rats carrying orthotopically transplanted BN472 rat breast tumours. WX-UK1 selectively inhibited tumour-related proteases from rats and humans such as uPA, plasmin, or thrombin in the sub or low micromolar range. The activity was stereoselective as the D-enantiomer of WX-UK1 inhibited uPA and plas-min at approximately 70-fold higher Ki
values than the active L-form. Chronical administration of the L-enantiomer of WXUK1 impaired primary tumour growth and metastasis of BN472 rat breast cancer in a dose-dependent manner. The minimum inhibitory dosage with maximal effect was between 0.15 and 0.3 mg/kg/day. The inactive D-enatiomer of WX-UK1 was not active in this respect. Daily treatment with WX-UK1 for up to 35 days was well tolerated as judged by the unchanged body and organ weight development. In conclusion, our results provide evidence that WX-UK1 as a single agent inhibits breast tumour growth and metastasis in vivo, and thus is a promising candidate drug to treat human cancer.
Plasminogen and matrix metalloproteinase activation by enzymatically modified low density lipoproteins in monocytes and smooth muscle cells
Authors: Schmidt Roland , Bülbül özgür B. , Hölderle Monika , Walther Franziska , Schömig Albert , Gawaz Meinrad , May Andreas E. , Klouche Mariam
Published: March 2005

Protease activity promotes the progression and rupture of atherosclerotic plaques. LDL has been described to become enzymatically modified within the vessel wall yielding an atherogenic moiety (E-LDL). We studied the effect of E-LDL on the activation of plasminogen and matrix metalloproteinases (MMPs) in mono-cytes and vascular smooth muscle cells (VSMCs) as well as on MMP activation during cellular interactions. Human monocytes, monocytic MonoMac6 cells and human VSMCs were incubated with human native LDL (n-LDL) or E-LDL for 24 hours. E-LDL in contrast to n-LDL induced substantial activation of the plasminogen activation system as well as of the MMP system in monocytic cells, as measured by enhanced cell surface expression of the urokinase receptor (uPAR), the extracellular matrix metalloproteinase Inducer (EMMPRIN) and the membrane type-1 MMPs (MT1-MMP, MMP-14), as well as by secretion of active uPA, and of MMP-9. Consistently, E-LDL-treated monocytes exhibited increased transmigration through “matrigel”, which was specifically abrogated by the MMP inhibitor galardin or the plasmin inhibitor aprotinin. In VSMCs, E-LDL induced MMP-1 and MMP-2 secretion. Moreover, monocyte incubation with supernatants of E-LDL-treated (but not n-LDL-treated)VSMCs strongly induced MMP-9 in monoytes, which was inhibited by blocking mAb anti-TNF-α. Together, enzymatical modification of LDL allows a direct activation of MMP expression in monocytes and VSMCs, and indirectly promotes the induction of paracrine, cytokine-mediated intercellular activation processes. Thereby, E-LDL may contribute to atheroprogression, inflammation and plaque rupture.
Plasminogen activation and cancer
Authors: Behrendt Niels , Høyer-Hansen Gunilla , Johnsen Morten , Lund Leif R. , Ploug Michael , Rømer John , Danø Keld
Published: March 2005

Breakdown of the extracellular matrix is crucial for cancer invasion and metastasis. It is accomplished by the concerted action of several proteases, including the serine protease plasmin and a number of matrix metalloproteases. The activity of each of these proteases is regulated by an array of activators, inhibitors and cellular receptors. Thus, the generation of plasmin involves the pro-enzyme plasminogen, the urokinase type plasminogen activator uPA and its pro-enzyme pro-uPA, the uPA inhibitor PAI-1, the cell surface uPA receptor uPAR, and the plasmin inhibitor α2-antiplasmin. Furthermore, the regulation of extracellular proteolysis in cancer involves a complex interplay between cancer cells and non-malignant stromal cells in the expression of the molecular components involved. For some types of cancer, this cellular interplay mimics that observed in the tissue of origin during non-neoplastic tissue remodelling processes. We propose that cancer invasion can be considered as uncontrolled tissue remodelling. Inhibition of extracellular proteases is an attractive approach to cancer therapy. Because proteases have many different functions in the normal organism, efficient inhibition will have toxic side effects. In cancer invasion, like in normal tissue remodelling processes, there appears to be a functional overlap between different extracellular proteases. This redundancy means that combinations of protease inhibitors must be used. Such combination therapy, however, is also likely to increase toxicity. Therefore for each type of cancer, a combination of protease inhibitors that is optimised with respect to both maximal therapeutic effect and minimal toxic side effects need to be identified.
Comparison of the Global Meridional Ekman Heat Flux Estimated from Four Wind Sources
Authors: Sato Olga T. , Polito Paulo S.
Published: March 2005

The variability in the meridional Ekman heat flux estimated using wind data from four different sources is examined. The wind vectors are obtained from the European Remote Sensing (ERS), Quick Scatterometer (Quikscat), and Special Sensor Microwave Imager (SSM/I) satellite instruments and from the National Centers for Environmental Prediction (NCEP) model. The datasets range over a period of 10 years except for the Quikscat, which spans the period between 1999 and 2003. The comparison of the annual mean of the zonally integrated Ekman heat flux shows some discrepancies. In comparing the four sources, the differences increase from the tropical regions toward the equator. The annual mean of the meridional Ekman heat flux is consistently smaller when estimated with the ERS data. The correlation analysis shows that ERS and the other sources have a better agreement in the tropical regions, with correlations between 0.6 and 0.8, while in the extratropical regions the correlation is 0.4. The SSM/I, NCEP, and Quikscat winds lead to better correlations, between 0.7 and 1 in the extratropical regions. The western side of the north Indian Ocean is a site where all sources are very well correlated to each other. The variability in the Ekman heat flux is determined by changes in the temperature and wind stress fields. A combination of digital filters was used to quantify the role of several regions in the frequency–zonal wavenumber spectrum of the wind in establishing the observed Ekman heat flux. The Ekman flux component that is obtained from the product of the long-term mean wind and the temperature dominates in the low latitudes of the Atlantic Ocean. Its fractional covariance reaches 0.6 in the Atlantic, in the Pacific Ocean it is at most 0.3, and it is negligible in the Indian Ocean. The temporal variability of this heat flux component is only due to the temperature variability, because the mean winds were used. Other Ekman heat flux components are obtained from the product of the filtered wind anomalies and the temperature. These components include several bands of propagating signals (Rossby waves) and have fractional covariances that are larger in the Pacific and Indian Oceans, while in the Atlantic they can explain at most 20% of the total variance. All wind sources show a shift in the variability regime around 15° of latitude, with the mean and large-scale prevailing over meso- and small-scale variability within the Tropics and vice versa in the extratropical regions.
Oceanic Fluxes in the South Atlantic
Authors: McDonagh Elaine L. , King Brian A.
Published: March 2005

A box inverse of the World Ocean Circulation Experiment A10 (30°S) and A11 (nominally 45°S) sections in the South Atlantic Ocean was undertaken. The authors find a heat flux across A10 of 0.22 ± 0.08 PW, consistent with previous studies, and a heat flux of 0.43 ± 0.08 PW across A11. The A11 heat flux is lower than some previous analyses of this section but implies a plausible oceanic heat convergence (heat loss to the atmosphere) of 0.21 ± 0.10 PW. The difference is principally due to adding a cyclonic component to the circulation in the Cape Basin. As compared with the solution of other studies, the anticyclonic circulation in the surface and intermediate water of the subtropical gyre is weakened. The circulation of the deep water is cyclonic rather than anticyclonic; this is in better agreement with previously published circulation schemes based on examination of water properties. A southward freshwater flux of 0.7 Sv (1 Sv ≡ 106 m3 s−1) at A11, consistent with previous inverse studies, is still inconsistent with the net Atlantic evaporation inferred from integrated surface climatologies. Results suggest a small gain of freshwater (0.2 ± 0.1 Sv) between the sections.
Using MM5 to Hindcast the Ocean Surface Forcing Fields over the Gulf of Maine and Georges Bank Region*
Authors: Chen Changsheng , Beardsley R. C. , Hu Song , Xu Qichun , Lin Huichan
Published: March 2005

The fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) is applied to the Gulf of Maine/Georges Bank (GoM/GB) region. This model is configured with two numerical domains with horizontal resolutions of 30 and 10 km, respectively, and driven by the NCAR-Eta weather model through a nested grid approach. Comparison of model-computed winds, wind stress, and heat flux with in situ data collected on moored meteorological buoys in the western GoM and over GB in 1995 shows that during the passage of atmospheric fronts over this region, MM5 provides a reasonable prediction of wind speed but not wind direction, and provides a relatively accurate estimation of longwave radiation but overestimates sensible and latent fluxes. The nudging data assimilation approach with inclusion of in situ wind data significantly improves the accuracy of the predicted wind speed and direction. Incorporation of the Fairall et al. air–sea flux algorithms with inclusion of Advanced Very High Resolution Radiometer (AVHRR)-derived SST improves the accuracy of the predicted latent and sensible heat fluxes in the GoM/GB region for both stable and unstable weather conditions.
Maximum Likelihood Estimates of Vortex Parameters from Simulated Coherent Doppler Lidar Data
Authors: Frehlich Rod , Sharman Robert
Published: March 2005

The performance of pulsed coherent Doppler lidar in estimating aircraft trailing wake vortices by scanning across the aircraft flight track is evaluated using Monte Carlo lidar simulations of a simple vortex pair in both a nonturbulent and turbulent environment. The performance estimates are based on maximum likelihood estimates of aircraft wake vortex parameters and provide a measure of the ability of the lidar to detect and track wake vortices under the best possible conditions. Two aircraft types are considered: the Boeing 737 and the Boeing 747. Rigorous error analyses are produced by comparing the estimated parameters from numerical simulations of raw lidar data with the known input parameters of the simulation. It is shown that the probability density functions for the estimates are approximately Gaussian and the bias is very small. The main source of the bias was determined to be the movement of the vortex during the lidar scan. The estimation error is increased by the effects of a background turbulent velocity field. The trade-off between lidar pulse energy and pulse repetition frequency for the standard condition of constant laser power is also presented. It is shown that these maximum likelihood estimates provide accurate detection and tracking of the key vortex parameters for a simple vortex model, with and without background turbulence.
A Mesoscale Analysis Method for Surface Potential Temperature in Mountainous and Coastal Terrain
Authors: Deng Xingxiu , Stull Roland
Published: March 2005

A technique is developed to anisotropically spread surface observations in steep valleys. The goal is to create an improved objective analysis for the lowest, terrain-following numerical weather prediction (NWP) model level in mountainous terrain.

The method is a mother–daughter (MD) approach, where the amount of information transferred from one grid point (the mother) to all neighboring grid points (the daughters) depends on elevation differences. The daughters become mothers and further share information with their neighboring grid points. This iterative method allows information to follow valleys around ridges, while reducing spread over the ridge top. The method is further refined to account for land–sea anisotropy.

This approach is tested in the objective analyses of surface potential temperatures over the steep mountainous and coastal terrain of southwestern British Columbia, Canada. Analysis results are compared with other existing schemes using the Advanced Regional Prediction System Data Assimilation System (ADAS). It is found that the MD approach outperforms the other schemes over mountainous and coastal terrain.