bluuebunny/crossref_metadata_2025 huggingface dataset:
Aufmerksamkeitslenkung bei Tinnitus: Eine experimentelle psychophysiologische Untersuchung
Authors: Rief Winfried , Sander Eva , Günther Markus , Nanke Alexandra
Published: August 2004

Zusammenfassung. Theoretischer Hintergrund: Gängige Erklärungsmodelle für die Entstehung und Chronifizierung von Tinnitus betonen die Bedeutung von Aufmerksamkeitsprozessen. Fragestellung: Deshalb wird mit der vorliegenden Untersuchung überprüft, ob die Lenkung der Aufmerksamkeit die Wahrnehmung und Unannehmlichkeit eines chronischen Tinnitus beeinflussen kann. Methode: 33 Personen mit chronischem Tinnitus nahmen an einem Experiment teil, bei dem sie für jeweils 10 Minuten folgende Bedingungen erfüllen sollten: (a) auf den eigenen Tinnitus konzentrieren; (b) sich entspannen; (c) Ablenkung durch Musik; (d) Konzentration auf ein über Tongenerator dargebotenes Imitat des Tinnitusgeräusches. Ergebnisse: Die Tinnitus-Belastung ist am höchsten unter der Bedingung “auf den eigenen Tinnitus konzentrieren“ und am geringsten unter der “Musik hören“-Bedingung. Die allgemeine Befindlichkeit ist sowohl unter der “auf den Tinnitus hören“ als auch unter der “externe Präsentation des Tinnitusgeräusches“-Bedingung reduziert. Unter der “auf den Tinnitus hören“-Bedingung lässt sich eine Habituation belegen, was Implikationen für die Behandlung haben kann. Zwischen den verschiedenen experimentellen Bedingungen zeigen sich auch Unterschiede in der psychophysiologischen Aktivierung (z.B. Herzrate, Trapezius-EMG, Masseter-EMG, sensomotorischer Rhythmus im EEG). Schlussfolgerungen: Diese Studie bestätigt, dass Aufmerksamkeitslenkung einen Effekt auf die Belastung durch Tinnitus hat. Daneben gibt es auch Anhaltspunkte für Habituationseffekte, die Relevanz für die Behandlung haben können.
Late Pleistocene fault slip rate, earthquake recurrence, and recency of slip along the Pyramid Lake fault zone, northern Walker Lane, United States
Authors: Briggs Richard W. , Wesnousky Steven G.
Published: August 2004

Up to 25% of Pacific‐North America plate relative transform motion is accommodated east of the Sierra Nevada. Most of that 25% is taken up by deformation in the Walker Lane, a discontinuous zone of strike‐slip and normal faults approximately parallel to the San Andreas. The Pyramid Lake fault zone is a northwest trending right‐lateral fault in the northern Walker Lane, Nevada. Recent geodetic surveys report 6 ± 2 mm/year of right‐lateral shear strain accumulation across the northern Walker Lane. Interpretation of displaced geomorphic features preserved in post‐Lake Lahontan (∼15,500 cal. yr B.P.) surfaces indicate the Pyramid Lake fault zone has accommodated at least 2.6 ± 0.3 mm/year of right‐lateral shear during the late Pleistocene. Additionally, a minimum of two earthquakes have occurred since deposition of the Mazama tephra (∼7630 cal. yr B.P.), and at least four earthquakes have occurred on the fault after desiccation of Lake Lahontan (∼15.5 ka), with the most recent earthquake occurring after 1705 ± 175 cal. yr B.P. The observations indicate that the Pyramid Lake fault zone accommodates the major portion (≥25%–70%) of right‐lateral slip east of the Sierra Nevada at the latitude of ∼39°45′N.
Biogenic and lithogenic particle fluxes in the western region of the Sea of Okhotsk: Implications for lateral material transport and biological productivity
Authors: Nakatsuka Takeshi , Fujimune Tomoaki , Yoshikawa Chisato , Noriki Shinichiro , Kawamura Kimitaka , Fukamachi Yasushi , Mizuta Genta , Wakatsuchi Masaaki
Published: August 2004

Sinking particles collected at two depths at two sites off Sakhalin Island in the western region of the Sea of Okhotsk were analyzed to determine their major chemical components (lithogenic material, biogenic opal, calcium carbonate (CaCO3), and total organic carbon (TOC)). The lithogenic and opal fluxes increased downward, indicating the lateral input of resuspended sedimentary particles into the lower traps, while the CaCO3 or TOC fluxes did not change greatly between the upper and lower traps. The lithogenic particle flux in the lower traps showed intermittent increase events frequently during periods when cold water masses penetrated into the intermediate layer at the mooring sites. This coincidence between the flux increase and the cooling of the intermediate layer clearly indicates that the cold and turbid Dense Shelf Water (DSW) is discharged from the bottom of the northwestern continental shelf to the pelagic intermediate layer, supplying large amounts of particulate matter onto the bottom of the slope and deep basin. After removing the effect of the lateral input, the time series of the opal export from the surface water at the mooring sites were reconstructed using the upper trap data. There were two predominant characteristics in the seasonal variations of the opal export, which is nearly equal to the diatom production, in the area off Sakhalin. One is the relatively large opal flux in autumn, and the other is the southward propagation of the spring diatom bloom, although the sea ice retreats northward every spring. Both of these characteristics suggest that the river water discharged from the Amur, together with the seasonal sea ice cover, regulates primary production in this area.
Model simulation and analysis of coarse and fine particle distributions during ACE‐Asia
Authors: Tsai Fujung , Liu Tsun‐Hsien , Liu Shaw C. , Chen Tai‐Yih , Anderson Theodore L. , Masonis Sarah J.
Published: August 2004

The Taiwan air quality model incorporating a dust module was applied to calculate masses of supermicron (diameter greater than 1 μm) and submicron particles (diameter less than 1 μm) and their dust fractions during the ACE‐Asia airborne experiments over the northwestern Pacific. The results showed that the calculated vertical profiles of supermicron particle concentrations matched reasonably well with the observations obtained from 19 research aircraft missions. During dust storm events and at dust concentrated altitudes, the calculated dust fractions in the supermicron particles were usually greater than 90%, and the dust was concentrated in the lower troposphere mainly below 6 km. Without dust storm, dust was still the major component of the supermicron particles above boundary layer. In contrast to supermicron particles, the model results showed that the major component of the submicron particles observed during aircraft experiments was mostly from pollution. The calculated vertical profiles of submicron particle concentrations were sensitive to the emission inventory of air pollutants over east Asia. The correlation between observed anthropogenic volatile organic compound and submicron particles were used to identify the pollution fraction in the submicron particles, and the results were consistent with the model calculations of dust fraction. The model results showed that the dust fractions in the submicron particles were usually less than 28% in the boundary layer. During dust storm events the dust fractions were usually greater than 40% but can be as low as 24% when significant amount of pollutants were present.
Impacts of dust on regional tropospheric chemistry during the ACE‐Asia experiment: A model study with observations
Authors: Tang Youhua , Carmichael Gregory R. , Kurata Gakuji , Uno Itsushi , Weber Rodney J. , Song Chul‐Han , Guttikunda Sarath K. , Woo Jung‐Hun , Streets David G. , Wei Cao , Clarke Antony D. , Huebert Barry , Anderson Theodore L.
Published: August 2004

A comprehensive regional‐scale chemical transport model, Sulfur Transport and Emissions Model 2001 (STEM‐2K1), is employed to study dust outflows and their influence on regional chemistry in the high‐dust Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) period, from 4–14 April 2001. In this period, dust storms are initialized in the Taklamagan and Gobi deserts because of cold air outbreaks, are transported eastward, and are often intensified by dust emitted from exposed soils as the front moves off the continent. Simulated dust agrees well with surface weather observations, satellite images, and the measurements of the C‐130 aircraft. The C‐130 aircraft observations of chemical constituents of the aerosol are analyzed for dust‐rich and low‐dust periods. In the submicron aerosol, dust‐rich air masses have elevated ratios of ΔCa/ΔMg, ΔNH4+/ΔSO42−, and ΔNO3−/ΔCO (Δ represents the difference between observed and background concentrations). The impacts of heterogeneous reactions on dust involving O3, NO2, SO2, and HNO3 are studied by incorporating these reactions into the analysis. These reactions have significant influence on regional chemistry. For example, the low O3 concentrations in C‐130 flight 6 can be explained only by the influence of heterogeneous reactions. In the near‐surface layer, the modeled heterogeneous reactions indicated that O3, SO2, NO2, and HNO3 are decreased by up to 20%, 55%, 20%, and 95%, respectively, when averaged over this period. In addition, NO, HONO, and daytime OH can increase by 20%, 30%, and 4%, respectively, over polluted regions. When dust encounters fresh pollutants, these heterogeneous reactions can lead to a series of complex responses of the photochemical system. In addition, these reactions can alter the chemical‐size distribution of the aerosol. Under heavy dust loadings, these reactions can lead to >20% of the sulfate and >70% of the nitrate being associated with the coarse fraction. The radiative influence of dust can also affect the photochemical system. For example, OH levels can decrease by 20% near surface. The dust radiative influence is shown to be weaker than the heterogeneous influence for most species.
Aerosol composition change between 1992 and 2002 at Gosan, Korea
Authors: Park Min Ha , Kim Yong Pyo , Kang Chang‐Hee , Shim Shang‐Gyu
Published: August 2004

TSP composition data and backward trajectory analysis results at Gosan, Korea, for 10 years between March 1992 and February 2002 are studied to understand the site characteristics and the relationship between the aerosol composition and meteorological conditions. The average non‐sea‐salt‐(nss)‐sulfate concentration (6.74 μg m−3) is higher than those observed at other background areas in the world. It was demonstrated that the observed high level of sulfate is due to transport from outside the site. The concentrations of nss‐sulfate/ammonium/nss‐potassium, sodium/chloride/magnesium, and nss‐calcium/nitrate show a strong relationship, suggesting their common emissions sources and/or transport pattern. It is likely that the concentration ratio of nss‐sulfate to nitrate is decreasing because of the increase of the nitrate concentration. On the basis of various measurement and emission estimate studies, it is suggested that this trend is mainly caused by the emission trend change in China. About half of the air mass trajectories are from northern China, and a quarter are from southern China. On the basis of cluster analysis, it was found that when air parcels moved from China, the concentrations of nss‐sulfate, ammonium, and nitrate are the highest.
Meteorological events and transport patterns in ACE‐Asia
Authors: Merrill John T. , Kim Jiyoung
Published: August 2004

The Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) intensive phase took place from 30 March to 4 May 2001, involving extensive aerosol observations from aircraft, ship, and ground stations. Meteorological events of significance to the ACE‐Asia intensive observations made during this period were identified and analyzed using a combination of gridded meteorological analysis fields, observations, and analyses of precipitation, atmospheric radiation distributions, and other variables, and products prepared from these data. The observed flow characteristics were found to be close to the center of the range of interannual variation, with most anomalies spatially confined and small in magnitude. The occurrence and distribution of midlatitude cyclones which had an impact on the circulation and transport patterns affecting the area of the campaign were close to the climatological mean. Total aerosol scattering and the fraction caused by submicron particles, and trajectory analysis results from points along the flight track of the C‐130, were used to examine the relationship between the aerosol distributions and transport patterns and the meteorological situation. Notably strong coarse‐mode scattering was observed at low altitudes in post cold‐frontal circulations during dust outbreaks, and very strong mixed‐mode scattering occurred in plumes from polluted areas flowing offshore removed from important surface or upper air features.
Aerosol chemical, physical, and radiative characteristics near a desert source region of northwest China during ACE‐Asia
Authors: Xu Jin , Bergin Michael H. , Greenwald Roby , Schauer James J. , Shafer Martin M. , Jaffrezo Jean L. , Aymoz Gilles
Published: August 2004

The Gobi desert in northwest China is an important source of mineral aerosols over both eastern Asia and the northern Pacific Ocean. In order to determine the chemical, physical, and radiative properties of aerosols originating from the Gobi desert source region, field measurements were performed in Yulin, China, in April 2001 as part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) campaign. The means and standard deviations of the measured aerosol light absorption coefficient σap, scattering coefficient σsp, and single‐scattering albedo ω are 6 Mm−1 (11 Mm−1), 158 Mm−1 (193 Mm−1), and 0.95 (0.05), respectively. A clear diurnal pattern is observed in both σap and σsp, resulting from diurnal changes in the mixing height as well as from local combustion sources in the morning and dust sources in the afternoon. Two distinct populations of aerosol mass scattering efficiencies Escat_2.5, one for aerosols dominated by desert dust (∼1.0 m2 g−1) and the other for aerosols composed primarily of local pollutants (∼3.0 m2 g−1), are observed. During the field study there were three significant dust events that occurred for, on average, several days at a time. The most significant dust storm resulted in a 24‐hour‐average PM2.5 concentration (mass concentration of particles having aerodynamic diameters less than 2.5 μm) of 453 μg m−3 and a peak σsp of 2510 Mm−1 on 8 April. The mean PM2.5 mass concentration during the dust storm periods is approximately 169 μg m−3, about 4 times greater than the mean value of 44 μg m−3 observed during local pollution periods. When local pollution is the dominant source of fine particulate mass, organic matter (OM) is the major chemical component, contributing 41% to the PM2.5 mass, followed by crustal material (29%), sulfate (17%), and elemental carbon (EC) (13%). During sand storm periods, ∼51% of PM2.5 mass is crustal material, followed by CO32− (11%) and OM (9.5%). The element enrichment factors indicate that coal combustion, biomass burning, and mobile source emissions are important local pollution sources. Overall, our results indicate that in addition to dust, local pollution also has a significant influence on aerosol properties in the region.
Chemical composition of atmospheric aerosols from Zhenbeitai, China, and Gosan, South Korea, during ACE‐Asia
Authors: Arimoto R. , Zhang X. Y. , Huebert B. J. , Kang C. H. , Savoie D. L. , Prospero J. M. , Sage S. K. , Schloesslin C. A. , Khaing H. M. , Oh S. N.
Published: August 2004

Studies were conducted as part of Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) to characterize the major ion and elemental composition of aerosol particle samples collected at Gosan, an ACE‐Asia supersite (GOS, Korea, total suspended particle or TSP samples) and at Zhenbeitai (ZBT, China, TSP and particles < 2.5 μm diameter or PM2.5 samples), a site closer to the sources for Asia dust. The concentrations of 24 elements in the ZBT PM2.5 samples were correlated with Al (an indicator of mineral dust), and the ratios of these elements to Al were similar to those in a loess certified reference material, but a second group of elements was enriched over crustal proportions most likely as a result of pollution emissions. The concentrations of various water‐soluble (WS) cations (Na+, K+, Ca2+, Mg2+) also were generally well correlated with Al in both the ZBT and GOS samples, with the exception being WS K+ at ZBT, where biomass burning may have had an effect. The percentage of calcium that was soluble approached 100% at ZBT versus ∼60% at GOS, and the ratio WS Ca2+/Al also was higher at ZBT. The molar ratio of sulfate to WS Ca2+ was ∼0.1 at ZBT but increased to near unity at GOS, where the aerosol nitrate/WS Ca2+ ratio was tenfold to hundredfold higher compared with ZBT, presumably because of anthropogenic influences. The observed differences in aerosol characteristics between sites can only be explained as the end product of different source contributions combined with complex processes involving gas‐particle conversion, size‐dependent fractionation, and aerosol mixing.
Effect of variability of soil physical properties on clutter and false alarms in land mine detection
Authors: Fokin Vladimir N. , Fokina Margarita S. , Sabatier James M. , Xiang Ning , Howard Wheeler B.
Published: August 2004

The effects of variability of the ground on land mine detection and false alarm rates are analyzed within the framework of a viscoelastic‐layered model of the ground. A matrix technique was used to describe sound interaction with layered viscoelastic ground. The resonance method in combination with a global search method is used to estimate a set of parameters for a three‐layered viscoelastic ground model. Results of the estimation show good agreement between computed and experimental data. The effect of a finite size of sound source on the acoustic‐to‐seismic transfer function is discussed. The effect of variability of ground properties on the acoustic‐to‐seismic transfer function (admittance function) is analyzed. Analysis is performed on the plane of parameters of the layered ground in a wide frequency range for all angles of incidence. It is revealed that small variations in the shear speed in the top layer of ground will not cause variation in the acoustic‐to‐seismic transfer function at low frequencies but may cause strong variation at high frequencies. Results of outdoor measurements of the acoustic‐to‐seismic transfer function are presented, and a correlation between the high magnitude of the acoustic‐to‐seismic transfer function in certain frequency ranges and moisture content on the surface is revealed. A simple model explaining the correlation between moisture content in the upper layer, the acoustic‐to‐seismic transfer function, and ground properties is suggested.
Self organized spatial‐temporal structure within the fractured Vadose Zone: Influence of fracture intersections
Authors: Glass Robert J. , LaViolette Randall A.
Published: August 2004

Under conditions of unsaturated flow, others have shown experimentally that fracture intersections can direct flow to a single exiting fracture. In addition, they have been found to gather water from above to release as a pulse below. We formulate a simple model where these two behaviors are embedded within a network. With slow steady inflow distributed randomly along the top of the network, the system self organizes to form avalanches of water that can penetrate to great depths. When all intersections split their outflow, flow diverges with depth and develops into a self‐organized dynamical state where the distribution of avalanche sizes follows a power‐law over many decades. As the fraction of intersections that direct outflow singly is increased, spatial structure passes from divergent through braided to a fully convergent, hierarchical flow regime where avalanche size is minimized along one‐dimensional slender pathways.
A new way to measure cirrus cloud ice water content by using ice Raman scatter with Raman lidar
Authors: Wang Zhien , Whiteman David N. , Demoz Belay B. , Veselovskii Igor
Published: August 2004

To improve our understanding of cirrus cloud radiative impact on the current and future climate, improved knowledge of cirrus cloud microphysical properties is needed. However, long‐term studies of the problem indicate that accurate cirrus cloud measurements are challenging. This is true for both, remote sensing as well as in situ sampling. This study presents a new method to remotely sense cirrus microphysical properties utilizing the Raman scattered intensities from ice crystals using a Raman lidar. Since the intensity of Raman scattering is fundamentally proportional to the number of molecules involved, this method provides a more direct way of measuring the ice water content compared with other schemes. Case studies presented here show that this method has the potential to provide simultaneous measurements of many of the essential information of cirrus microphysical properties.
An empirical investigation of source term balance of small scale surface waves
Authors: Hwang Paul A. , Wang David W.
Published: August 2004

Phillips [1984] presents a method to derive the dissipation function (D) of the wave action density conservation equation from the functional dependence of the wave saturation spectrum (B) on wind friction velocity. The method is applied to field spectra of small scale waves (wavelengths between 0.02 and 6 m). The results indicate that D approaches asymptotically to B3 toward long gravity waves and to B2.3 for short gravity waves. In the middle wavelength range (0.16 to 2.1 m), the dependence is as strong as B10. This may suggest that the spectral property of wave breaking is localized in the wavenumber space, with strong signature in the 0.16 to 2.1 m wavelength scale.
Evidence for a massive phreatomagmatic eruption in the initial stages of formation of the Mangala Valles outflow channel, Mars
Authors: Wilson Lionel , Head James W.
Published: August 2004

New data reveal the presence of a system of parallel dune‐like ridges extending in a band for up to 25–30 km around the eastern margin of the source trough for the Mangala Valles outflow channel system. We interpret these ridges to be formed during initial phreatomagmatic activity caused by dike emplacement, cryospheric cracking, magma‐groundwater mixing, and explosive eruption to the surface. The erupted material consisted of fragmented magma, steam, and country rock which expanded from a choked state at the surface vent to form a near‐ballistic, Io‐like eruption plume. Outward flow of the plume at velocities of ∼430 m/s from a ∼30–60 km‐long section of the graben is interpreted to have formed the system of dune‐like ridges. Subsequent outpouring of groundwater formed the Mangala Valles outflow channel system.
Comparing morphologies of drainage basins on Mars and Earth using integral‐geometry and neural maps
Authors: Stepinski T. F. , Coradetti S.
Published: August 2004

We compare morphologies of drainage basins on Mars and Earth in order to confine the formation process of Martian valley networks. Basins on both planets are computationally extracted from digital topography. Integral‐geometry methods are used to represent each basin by a circularity function that encapsulates its internal structure. The shape of such a function is an indicator of the style of fluvial erosion. We use the self‐organizing map technique to construct a similarity graph for all basins. The graph reveals systematic differences between morphologies of basins on the two planets. This dichotomy indicates that terrestrial and Martian surfaces were eroded differently. We argue that morphologies of Martian basins are incompatible with runoff from sustained, homogeneous rainfall. Fluvial environments compatible with observed morphologies are discussed. We also construct a similarity graph based on the comparison of basins' hypsometric curves to demonstrate that hypsometry is incapable of discriminating between terrestrial and Martian basins.
Ridge migration, asthenospheric flow and the origin of magmatic segmentation in the global mid‐ocean ridge system
Authors: Katz Richard F. , Spiegelman Marc , Carbotte Suzanne M.
Published: August 2004

Global observations of mid‐ocean ridge (MOR) bathymetry demonstrate an asymmetry in axial depth across ridge offsets that is correlated with the direction of ridge migration. Motivated by these observations, we have developed two‐dimensional numerical models of asthenospheric flow and melting beneath a migrating MOR. The modification of the flow pattern produced by ridge migration leads to an asymmetry in melt production rates on either side of the ridge. By coupling a simple parametric model of three dimensional melt focusing to our simulations, we generate predictions of axial depth differences across offsets in the MOR. These predictions are quantitatively consistent with the observed asymmetry.
Consistent surface albedo retrieval from two adjacent geostationary satellites
Authors: Govaerts Y. M. , Lattanzio A. , Pinty B. , Schmetz J.
Published: August 2004

Monitoring and understanding climate changes of the Earth require the generation of long‐term and consistent global data set from observations. In this context, geostationary satellite observations could play a significant role thanks to the long duration of the missions and the corresponding archives. In particular, their frequent acquisition cycle throughout the day can be used to document the surface anisotropy and therefore surface albedo. This paper investigates the possibility to generate a consistent surface albedo maps from two adjacent geostationary satellites, namely Meteosat‐5 and ‐7. The analysis relies on the comparison of albedo values derived over the common observed area. These values agree favorably between the two spacecrafts.
Electric field distributions for Langmuir waves in planetary foreshocks
Authors: Boshuizen Christopher R. , Cairns Iver H. , Robinson P. A.
Published: August 2004

This paper addresses several key issues regarding the statistics of Langmuir wave fields E in planetary foreshocks by presenting (1) a detailed theory for the electric field strength probability distributions averaged over Earth's foreshock and (2) the first analyses of the distributions observed in the outer planets. First, existing theory is extended and generalized, describing in detail how lognormal distributions of P(log E) for a specific location can be aggregated over foreshock location to give power law distributions (log E). The extended theory is in good agreement with the observations of power law distributions (log E) for Earth's foreshock, and implies that stochastic growth theory (SGT) is likely to be relevant. The statistics of the Langmuir wave fields of the outer planets Saturn, Uranus, and Neptune are then analyzed and compared. The characteristics of the observed distributions (logE) agree qualitatively with each other and Earth, and these distributions collapse onto a single curve when scaled on the assumption that the ratio of the wave energy density to thermal plasma energy density is constant with heliocentric distance. The extended theory developed for Earth is also found to agree well with the scaled (log E) distributions for each outer planet. The evidence is thus that the physics of electrons and Langmuir waves in all planetary foreshocks is essentially identical and that the distributions (log E) are consistent with SGT.
Inferences on ultralow‐velocity zone structure from a global analysis of SPdKS waves
Authors: Thorne Michael S. , Garnero Edward J.
Published: August 2004

Anomalous boundary layer structure at the core‐mantle boundary (CMB) is investigated using a global set of broadband SKS and SPdKS waves from permanent and portable broadband seismometer arrays. SPdKS is an SKS wave that intersects the CMB at the critical angle for ScP, thus initiating a diffracted P wave (Pdiff) along the CMB at the core entry and exit locations. The waveshape and timing of SPdKS data are analyzed relative to SKS, with some SPdKS data showing significant delays and broadening. Broadband data from several hundred deep focus earthquakes were analyzed; retaining data with simple sources and high signal‐to‐noise ratios resulted in 53 high‐quality earthquakes. For each earthquake an empirical source was constructed by stacking pre‐SPdKS distance range SKS pulses (∼90°–100°). These were utilized in our synthetic modeling process, whereby reflectivity synthetic seismograms are produced for three classes of models: (1) mantle‐side ultralow‐velocity zones (UVLZ), (2) underside CMB core rigidity zones, and (3) core‐mantle transition zones. For ULVZ structures, ratios of P‐to‐S velocity reductions of 1:1 and 1:3 are explored, where 1:3 is appropriate for a partial melt origin of ULVZ. Over 330 unique CMB boundary layer models have been constructed and tested, corroborating previous work suggesting strong trade‐offs between the three model spaces. We produce maps of inferred boundary layer structure from the global data and find evidence for extremely fine‐scale heterogeneity where our wave path sampling is the densest. While uncertainties are present relating to the source versus receiver sides of the SPdKS wave path geometry, our data are consistent with the hypothesis that ULVZ presence (or absence) correlates with reduced (or average) heterogeneity in the overlying mantle.
Functional analysis of peroxisome-proliferator-responsive element motifs in genes of fatty acid-binding proteins
Authors: SCHACHTRUP Christian , EMMLER Tanja , BLECK Bertram , SANDQVIST Anton , SPENER Friedrich
Published: August 2004

Retinoic acids and long-chain fatty acids are lipophilic agonists of nuclear receptors such as RXRs (retinoic X receptors) and PPARs (peroxisome-proliferator-activated receptors) respectively. These agonists are also ligands of intracellular lipid-binding proteins, which include FABPs (fatty acid-binding proteins). We reported previously that L (liver-type)-FABP targets fatty acids to the nucleus of hepatocytes and affects PPARα activation, which binds together with an RXR subtype to a PPRE (peroxisome-proliferator-responsive element). In the present study, we first determined the optimal combination of murine PPAR/RXR subtypes for binding to known murine FABP-PPREs and to those found by computer search and then tested their in vitro functionality. We show that all PPARs bind to L-FABP-PPRE, PPARα, PPARγ1 and PPARγ2 to A (adipocyte-type)-FABP-PPRE. All PPAR/RXR heterodimers transactivate L-FABP-PPRE, best are combinations of PPARα with RXRα or RXRγ. In contrast, PPARα heterodimers do not transactivate A-FABP-PPRE, best combinations are of PPARγ1 with RXRα and RXRγ, and of PPARγ2 with all RXR subtypes. We found that the predicted E (epidermal-type)- and H (heart-type)-FABP-PPREs are not activated by any PPAR/RXR combination without or with the PPAR pan-agonist bezafibrate. In the same way, C2C12 myoblasts transfected with promoter fragments of E-FABP and H-FABP genes containing putative PPREs are also not activated through stimulation of PPARs with bezafibrate applied to the cells. These results demonstrate that only PPREs of L- and A-FABP promoters are functional, and that binding of PPAR/RXR heterodimers to a PPRE in vitro does not necessarily predict transactivation.
Endothelial lipase-modified high-density lipoprotein exhibits diminished ability to mediate SR-BI (scavenger receptor B type I)-dependent free-cholesterol efflux
Authors: GAUSTER Martin , OSKOLKOVA Olga V. , INNERLOHINGER Josef , GLATTER Otto , KNIPPING Gabriele , FRANK Saša
Published: August 2004

Endothelial lipase (EL) is a phospholipase with little triacylglycerol lipase activity. To assess structural and functional properties of EL-HDL (EL-modified high-density lipoprotein), HDL was incubated with conditioned medium from Cos-7 cells infected with adenovirus encoding human EL. After re-isolation of HDL by ultracentrifugation, TLC and HPLC analyses revealed that EL-HDL was markedly depleted in phosphatidylcholine and enriched in lyso-phosphatidylcholine compared with LacZ-HDL (control HDL) incubated with conditioned medium from Cos-7 cells infected with adenovirus encoding β-galactosidase. The EL-HDL was enriched in non-esterified fatty acids and, as revealed by lipid electrophoresis, was more negatively charged than control HDL. The HDL particle size as well as the total cholesterol, free cholesterol and triacylglycerol content of HDL were not significantly altered after EL modification. The ability of EL-HDL to mediate 3H-cholesterol efflux from SR-BI (scavenger receptor B type I) overexpressing Chinese-hamster ovary cells was impaired and markedly lower compared with LacZ-HDL at HDL concentrations of 100 μg/ml and above. Studies with 125I-labelled HDL showed almost unaltered binding affinity (Km values) and a slightly but significantly decreased binding capacity (Bmax values) of EL-HDL to SR-BI, compared with LacZ-HDL. The ATP-binding-cassette transporter A1-dependent cholesterol and phospholipid effluxes were not affected by EL modification. From these results, we concluded that EL modification alters chemical composition and physical properties of HDL, resulting in its decreased binding capacity to SR-BI and a diminished ability to mediate SR-BI-dependent cholesterol efflux.
Cloning and expression of an inhibitor of microbial metalloproteinases from insects contributing to innate immunity
Authors: CLERMONT Anja , WEDDE Marianne , SEITZ Volkhard , PODSIADLOWSKI Lars , LENZE Dido , HUMMEL Michael , VILCINSKAS Andreas
Published: August 2004

The first IMPI (inhibitor of metalloproteinases from insects) was identified in the greater wax moth, Galleria mellonella [Wedde, Weise, Kopacek, Franke and Vilcinskas (1998) Eur. J. Biochem. 255, 535–543]. Here we report cloning and expression of a cDNA coding for this IMPI. The IMPI mRNA was identified among the induced transcripts from a subtractive and suppressive PCR analysis after bacterial challenge of G. mellonella larvae. Induced expression of the IMPI during a humoral immune response was confirmed by real-time PCR, which documented up to 500 times higher amounts of IMPI mRNA in immunized larvae in comparison with untreated ones. The IMPI sequence shares no similarity with those of tissue inhibitors of metalloproteinases or other natural inhibitors of metalloproteinases, and the recombinant IMPI specifically inhibits thermolysin-like metalloproteinases, but not matrix metalloproteinases. These results support the hypothesis that the IMPI represents a novel type of immune-related protein which is induced and processed during the G. mellonella humoral immune response to inactivate pathogen-associated thermolysin-like metalloproteinases.
Heterodimeric interaction and interfaces of S100A1 and S100P
Authors: WANG Guozheng , ZHANG Shu , FERNIG David G. , SPILLER David , MARTIN-FERNANDEZ Marisa , ZHANG Hongmei , DING Yi , RAO Zihe , RUDLAND Philip S. , BARRACLOUGH Roger
Published: August 2004

With the widespread use of yeast two-hybrid systems, many heterodimeric forms of S100 proteins have been found, although their biological significance is unknown. In the present study, S100A1 was found to interact with another S100 protein, S100P, by using the yeast two-hybrid system. The binding parameters of the interaction were obtained using an optical biosensor and show that S100P has a slightly higher affinity for S100A1 (Kd=10–20 nM) when compared with that for self-association (Kd=40–120 nM). The physical interaction of S100A1 and S100P was also demonstrated in living mammalian cells using a fluorescence resonance energy transfer technique. Preincubation of recombinant S100P with S100A1, before the biosensor assay, reduced by up to 50% the binding of S100P to a recombinant C-terminal fragment of non-muscle myosin A, one of its target molecules. Site-specific mutations of S100P and S100A1, combined with homology modelling of an S100P/S100A1 heterodimer using known S100P and S100A1 structures, allowed the hydrophobic interactions at the dimeric interface of the heterodimer to be defined and provide an explanation for the heterodimerization of S100P and S100A1 at the molecular level. These results have revealed the similarities and the differences between the S100P homodimer and the S100A1/S100P heterodimer.
Fructosamine 3-kinase-related protein and deglycation in human erythrocytes
Authors: COLLARD François , WIAME Elsa , BERGANS Niki , FORTPIED Juliette , VERTOMMEN Didier , VANSTAPEL Florent , DELPIERRE Ghislain , VAN SCHAFTINGEN Emile
Published: August 2004

Fructosamine 3-kinase (FN3K), an enzyme initially identified in erythrocytes, catalyses the phosphorylation of fructosamines on their third carbon, leading to their destabilization and their removal from protein. We show that human erythrocytes also contain FN3K-related protein (FN3K-RP), an enzyme that phosphorylates psicosamines and ribulosamines, but not fructosamines, on the third carbon of their sugar moiety. Protein-bound psicosamine 3-phosphates and ribulosamine 3-phosphates are unstable, decomposing at pH 7.1 and 37 °C with half-lives of 8.8 h and 25 min respectively, as compared with 7 h for fructosamine 3-phosphates. NMR analysis indicated that 1-deoxy-1-morpholinopsicose (DMP, a substrate for FN3K and FN3K-RP), like 1-deoxy-1-morpholinofructose (DMF, a substrate of FN3K), penetrated erythrocytes and was converted into the corresponding 3-phospho-derivative. Incubation of erythrocytes with 50 mM allose, 200 mM glucose or 10 mM ribose for 24 h resulted in the accumulation of glycated haemoglobin, and this accumulation was approx. 1.9–2.6-fold higher if DMP, a competitive inhibitor of both FN3K and FN3K-RP, was present in the incubation medium. Incubation with 50 mM allose or 200 mM glucose also caused the accumulation of ketoamine 3-phosphates, which was inhibited by DMP. By contrast, DMF, a specific inhibitor of FN3K, only affected the glucose-dependent accumulation of glycated haemoglobin and ketoamine 3-phosphates. These data indicate that FN3K-RP can phosphorylate intracellular, protein-bound psicosamines and ribulosamines, thus leading to deglycation.
Cortactin signalling and dynamic actin networks
Authors: DALY Roger J.
Published: August 2004

Cortactin was first identified over a decade ago, and its initial characterization as both an F-actin binding protein and v-Src substrate suggested that it was likely to be a key regulator of actin rearrangements in response to tyrosine kinase signalling. The recent discovery that cortactin binds and activates the actin related protein (Arp)2/3 complex, and thus regulates the formation of branched actin networks, together with the identification of multiple protein targets of the cortactin SH3 domain, have revealed diverse cellular roles for this protein. This article reviews current knowledge regarding the role of cortactin in signalling to the actin cytoskeleton in the context of these developments.
RNA processing and Arabidopsis flowering time control
Authors: Simpson G.G. , Quesada V. , Henderson I.R. , Dijkwel P.P. , Macknight R. , Dean C.
Published: August 2004

Plants control their flowering time in order to ensure that they reproduce under favourable conditions. The components involved in this complex process have been identified using a molecular genetic approach in Arabidopsis and classified into genetically separable pathways. The autonomous pathway controls the level of mRNA encoding a floral repressor, FLC, and comprises three RNA-binding proteins, FCA, FPA and FLK. FCA interacts with the 3′-end RNA-processing factor FY to autoregulate its own expression post-transcriptionally and to control FLC. Other components of the autonomous pathway, FVE and FLD, regulate FLC epigenetically. This combination of epigenetic and post-transcriptional control gives precision to the control of FLC expression and flowering time.
Chloroplast RNA-binding and pentatricopeptide repeat proteins
Authors: Nakamura T. , Schuster G. , Sugiura M. , Sugita M.
Published: August 2004

Chloroplast gene expression is mainly regulated at the post-transcriptional level by numerous nuclear-encoded RNA-binding protein factors. In the present study, we focus on two RNA-binding proteins: cpRNP (chloroplast ribonucleoprotein) and PPR (pentatricopeptide repeat) protein. These are suggested to be major contributors to chloroplast RNA metabolism. Tobacco cpRNPs are composed of five different proteins containing two RNA-recognition motifs and an acidic N-terminal domain. The cpRNPs are abundant proteins and form heterogeneous complexes with most ribosome-free mRNAs and the precursors of tRNAs in the stroma. The complexes could function as platforms for various RNA-processing events in chloroplasts. It has been demonstrated that cpRNPs contribute to RNA stabilization, 3′-end formation and editing. The PPR proteins occur as a superfamily only in the higher plant species. They are predicted to be involved in RNA/DNA metabolism in chloroplasts or mitochondria. Nuclear-encoded HCF152 is a chloroplast-localized protein that usually has 12 PPR motifs. The null mutant of Arabidopsis, hcf152, is impaired in the 5′-end processing and splicing of petB transcripts. HCF152 binds the petB exon–intron junctions with high affinity. The number of PPR motifs controls its affinity and specificity for RNA. It has been suggested that each of the highly variable PPR proteins is a gene-specific regulator of plant organellar RNA metabolism.
Characterization of a crucifer plant pre-rRNA processing complex
Authors: Sáez-Vasquez J. , Caparros-Ruiz D. , Barneche F. , Echeverría M.
Published: August 2004

In cruciferous plants, the primary pre-rRNA cleavage site (P site) is immediately downstream of four similar, highly conserved sequences (A1, A2, A3 and B) located within the 5′-ETS (5′-external transcribed spacer). In the present study, we describe the characterization of a plant NF D (nuclear factor D) that binds and interacts specifically with this A123BP cluster in the rDNA sequence. NF D is a high-molecular-mass complex containing nucleolin, fibrillarin and U3 and U14 snoRNAs. Furthermore, we show that NF D binds and cleaves pre-rRNA specifically at the P site. Thus we conclude that NF D is a pre-rRNA processing complex that may first assemble on rDNA and then bind nascent pre-rRNA.
The role of the initiation surveillance complex in promoting efficient protein synthesis
Authors: Gallie D.R.
Published: August 2004

Initiation is most often the rate-limiting step of translation. Translation initiation requires the involvement of numerous factors that assist binding of the 40 S ribosomal subunit to an mRNA and the assembly of the 80 S ribosome at the correct initiation codon. Recruitment of an initiation surveillance complex is required for translation and serves to identify mRNAs that are structurally and functionally competent for translation. For most cellular mRNAs, recruitment of the surveillance complex requires the 5′-cap and 3′-poly(A) tail. However, some cellular and viral mRNAs that naturally lack either of these have evolved alternatives that serve to recruit the complex. The initiation surveillance complex functions to stabilize eIF4F (where eIF stands for eukaryotic initiation factor), the cap-binding complex, to the cap; promote eIF4A helicase activity to remove secondary structure in the 5′-leader that might otherwise reduce 40 S ribosomal subunit scanning; promote eIF4B binding to increase eIF4A/eIF4F function and stabilize binding of the poly(A)-binding protein to the poly(A) tail. The surveillance complex is regulated through changes in phosphorylation in response to environmental conditions or by developmental signals as a means to regulate globally protein synthesis. Thus the initiation surveillance complex ensures that only intact mRNAs are recruited for translation and serves to regulate protein synthesis.
Plant translation initiation factors: it is not easy to be green
Authors: Browning K.S.
Published: August 2004

Plants have significant differences in some of the ‘parts’ of the translational machinery. There are two forms of eukaryotic initiation factor (eIF) 4F, eIF3 has two novel subunits, eIF4B is poorly conserved, and eIF2 kinases and eIF4E binding proteins (4E-BP) are yet to be discovered. These differences suggest that plants may regulate their translation in unique ways.
Control of translation reinitiation on the cauliflower mosaic virus (CaMV) polycistronic RNA
Authors: Ryabova L. , Park H.-S. , Hohn T.
Published: August 2004

Translation of the polycistronic 35S RNA of CaMV (cauliflower mosaic virus) occurs via a reinitiation mechanism, which requires TAV (transactivator/viroplasmin). To allow translation reinitiation of the major open reading frames on the polycistronic RNA, TAV interacts with the host translational machinery via eIF3 (eukaryotic initiation factor 3) and the 60S ribosome. Accumulation of TAV and eIF3 in the polysomal fraction isolated from CaMV-infected cells suggested that TAV prevents loss of eIF3 from the translating ribosomes during the first initiation event. The TAV–eIF3–80S complex could be detected in vitro by sucrose-gradient-sedimentation analysis. The question is whether TAV interacts directly with the 48S preinitiation complex or enters polysomes after the first initiation event. eIF4B, a component of the 48S initiation complex, can preclude formation of the TAV–eIF3 complex via competition with TAV for eIF3 binding; the eIF4B- and TAV-binding sites on eIF3g overlap. eIF4B out-competes TAV for binding to eIF3 and to the eIF3–40S complex. Transient overexpression of eIF4B in plant protoplasts specifically inhibits TAV-mediated transactivation of polycistronic translation. Our results thus indicate that eIF4B precludes TAV–eIF3–40S complex formation during the first initiation event. Consequently, overexpression of TAV in plant protoplasts affects only the second and subsequent initiation events. We propose a model in which TAV enters the host translational machinery at the eIF4B-removal step to stabilize eIF3 within polysomes.
Autoregulation of the gene for cystathionine γ-synthase in Arabidopsis: post-transcriptional regulation induced by S-adenosylmethionine
Authors: Onouchi H. , Lambein I. , Sakurai R. , Suzuki A. , Chiba Y. , Naito S.
Published: August 2004

Cystathionine γ-synthase (CGS) catalyses the first committed step of methionine biosynthesis in higher plants. CGS is encoded by the CGS1 gene in Arabidopsis. Stability of CGS1 mRNA is down-regulated in response to methionine application and the exon 1-coding region of CGS1 itself is necessary and sufficient for this regulation. mto1 (for methionine overaccumulation) mutants of Arabidopsis, which carry single-amino-acid sequence alterations within CGS1 exon 1, are deficient in this regulation and overaccumulate methionine. Since CGS1 exon 1 acts in cis during this regulation, we have proposed a model that the regulation occurs during translation of CGS1 mRNA when the nascent polypeptide of CGS and its mRNA are in close proximity. In fact, application of the translation inhibitor cycloheximide abolished this regulation in vivo. This model predicts that the regulation can be reproduced in an in vitro translation system. Studies using the in vitro translation system of wheatgerm extract have indicated that S-adenosylmethionine, a direct metabolite of methionine, is the effector of this regulation. A 5′-truncated RNA species, which is a probable degradation intermediate of CGS1 mRNA in vivo, was also detected in vitro, suggesting that the wheatgerm in vitro translation system reflects the in vivo regulation.