bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability of aerosol optical properties derived from in situ aircraft measurements during ACE‐Asia
Authors: Anderson Theodore L. , Masonis Sarah J. , Covert David S. , Ahlquist Norman C. , Howell Steven G. , Clarke Antony D. , McNaughton Cameron S.
Published: August 2003

Airborne measurements of aerosol light scattering (using nephelometers) and absorption (using particle/soot absorption photometers; PSAPs) in the Asian outflow region are presented. Aerosol particles were sampled through a new low turbulence inlet that proved very effective at transmitting coarse‐mode particles. Noise and artifacts are characterized using in‐flight measurements of particle‐free air and measurements with identical instruments operated in parallel. For example, the sensitivities of PSAP noise to changing altitude, changing relative humidity (RH), and particle‐loading on the internal filter are quantified. On the basis of these and previous instrument characterizations, we report averages, variations, and uncertainties of optical properties, focusing on data from approximately 300 level‐leg samples obtained during 19 research flights in the spring of 2001. Several broad patterns emerge from this analysis. Two dominant components, fine‐mode pollution and coarse‐mode mineral dust, were observed to vary independently when separated using a cut point of 1 μm aerodynamic diameter at low RH. Fine‐mode pollution was found to be moderately absorbing (single scatter albedo at low RH and 550 nm, ω = 0.88 ± 0.03; mean and 95% confidence uncertainty) and moderately hygroscopic (relative increase in scattering from 40% to 85% RH, fRH = 1.7 ± 0.2), while coarse‐mode dust was found to have very low absorption (ω = 0.96 ± 0.01) and to be almost nonhygroscopic (fRH = 1.1 ± 0.1). These and other optical properties are intended to serve as constraints on optical models of the Asian aerosol for the purpose of satellite retrievals and calculations of direct radiative effects.
Impact of bias correction to reanalysis products on simulations of North American soil moisture and hydrological fluxes
Authors: Berg Aaron A. , Famiglietti James S. , Walker Jeffrey P. , Houser Paul R.
Published: August 2003

Simulating land surface hydrological states and fluxes requires a comprehensive set of atmospheric forcing data at consistent temporal and spatial scales. At the continental‐to‐global scale, such data are not available except in weather reanalysis products. Unfortunately, reanalysis products are often biased due to errors in the host weather forecast model. This paper explores whether the error in model predictions of the initial soil moisture status and hydrological fluxes can be minimized through a bias reduction scheme to the European Centre for Medium Range Weather Forecast and National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis products. The bias reduction scheme uses both difference and ratio corrections based upon global observational data sets. Both the corrected and original forcing data were used to simulate land surface states and fluxes with a land surface model (LSM) over North America. Soil moisture, snow depth, and runoff output from the LSM are compared to observations to assess the impact of the bias correction on simulation accuracy. Results of this study demonstrate the sensitivity of LSMs to bias in the forcing data, and that implementation of a bias reduction scheme reduces errors to the simulation of soil moisture, runoff, and snow water equivalence. Accordingly, the initial soil moisture fields produced should be more representative of actual conditions, and therefore more useful to the climate modeling community. Results suggest that modelers using reanalysis products for forcing LSMs, in particular for the establishment of initial conditions, should consider a bias reduction strategy when preparing their input forcing fields.
Column closure studies of lower tropospheric aerosol and water vapor during ACE‐Asia using airborne Sun photometer and airborne in situ and ship‐based lidar measurements
Authors: Schmid B. , Hegg D. A. , Wang J. , Bates D. , Redemann J. , Russell P. B. , Livingston J. M. , Jonsson H. H. , Welton E. J. , Seinfeld J. H. , Flagan R. C. , Covert D. S. , Dubovik O. , Jefferson A.
Published: August 2003

We assess the consistency (closure) between solar beam attenuation by aerosols and water vapor measured by airborne Sun photometry and derived from airborne in situ and ship‐based lidar measurements during the April 2001 Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia). The airborne data presented here were obtained aboard the Twin Otter aircraft. Comparing aerosol extinction σep(550 nm) from four different techniques shows good agreement for the vertical distribution of aerosol layers. However, the level of agreement in absolute magnitude of the derived aerosol extinction varied among the aerosol layers sampled. The σep(550 nm) computed from airborne in situ size distribution and composition measurements shows good agreement with airborne Sun photometry in the marine boundary layer but is considerably lower in layers dominated by dust if the particles are assumed to be spherical. The σep(550 nm) from airborne in situ scattering and absorption measurements are about ∼13% lower than those obtained from airborne Sun photometry during 14 vertical profiles. Combining lidar and the airborne Sun photometer measurements reveals the prevalence of dust layers at altitudes up to 10 km with layer aerosol optical depth (from 3.5 to 10 km altitude) of ∼0.1 to 0.2 (500 nm) and extinction‐to‐backscatter ratios of 59–71 sr (523 nm). The airborne Sun photometer aboard the Twin Otter reveals a relatively dry atmosphere during ACE‐Asia with all water vapor columns <1.5 cm and water vapor densities ρw < 12 g/m3. Comparing layer water vapor amounts and ρw from the airborne Sun photometer to the same quantities measured with aircraft in situ sensors leads to a high correlation (r2 = 0.96), but the Sun photometer tends to underestimate ρw by 7%.
Orogenic tectonism on Io
Authors: Jaeger W. L. , Turtle E. P. , Keszthelyi L. P. , Radebaugh J. , McEwen A. S. , Pappalardo R. T.
Published: August 2003

We catalog 143 Ionian mountains (montes) and mountain‐like features (mensae, tholi, plana, and small peaks) in order to investigate orogenic tectonism on Io. From this comprehensive list, we select 96 mountains for which there are sufficient coverage and resolution to discern spatial relationships with surrounding geologic features. Three of the 96 mountains are probably volcanoes, 92 appear to be tectonic massifs, and 1 is ambiguous. Of the 92 tectonic mountains, 38 abut paterae (volcanic or volcano‐tectonic craters with irregular or scalloped margins). This juxtaposition is unlikely to be a coincidence as the probability of it occurring by chance is ∼0.1%. We propose instead that orogenic faults may act as conduits for magma ascent, thus fueling patera formation near mountains. As resurfacing buries a shell of material from Io's surface to the base of the lithosphere, its effective radius is reduced and it heats up. We calculate the lithospheric volume change due to subsidence and thermal expansion as a function of lithospheric thickness. Conservation of volume dictates that this material must be uplifted at Io's surface. By estimating the total volume of the mountains, we are able to place a lower limit of 12 km on Io's lithospheric thickness. We hypothesize that, in some cases, mountain formation may be facilitated by asthenospheric diapirs impinging on the base of the lithosphere. The resulting lithospheric swell could focus the compressive stresses that drive orogenic tectonism. This model is one of several possible mechanisms for uplifting isolated mountains such as are observed on Io.
Ionospheric D region electron density profiles derived from the measured interference pattern of VLF waveguide modes
Authors: Bainbridge Geoffrey , Inan Umran S.
Published: August 2003

The altitude profile of electron density in the D region is determined using an array of GPS‐phase‐referenced VLF receivers, allowing for the simultaneous broadband (i.e., phase coherent) measurement of a 24.0 kHz signal at multiple sites ranging in propagation path length from 3060 to 3353 km. Measured data are compared with results of model calculations for four electron density profiles used in previous work, assuming a single density profile to be in effect along the entire signal path from transmitter to receiver. Interpolation between model profiles is used to find a new profile which best fits the data. Phase coherent measurements over a range of path lengths also allow for the identification of the parameters for individual waveguide modes. Measured mode parameters agree with model calculations, within the limitations imposed by the configuration of the present array. A methodology of analysis and the required set of measurements is described, which would allow the decomposition of a VLF signal into all of its constituent waveguide modes, and accurate measurement of the characteristic parameters of each mode, namely phase velocity, attenuation rate, amplitude, and phase.
A Clustering Poisson model for characterizing the interarrival times of sferics
Authors: Chrissan D. A. , Fraser‐Smith A. C.
Published: August 2003

The noise waveform of atmospheric radio noise below 100 MHz is typically impulsive in nature. The impulses are caused by atmospheric events, mainly lightning strokes, that create electromagnetic emissions known as sferics. Sferic impulses in the noise waveform are seen to cluster in groups, indicating an underlying clustering process related to the physical characteristics of the lightning mechanism. The objective of this work is the statistical modeling of the clustering of noise impulses in atmospheric radio noise in the range 10 Hz to 60 kHz (denoted low‐frequency noise). Based on hundreds of hours of impulse interarrival time measurements made by the Stanford Radio Noise Survey System on such noise, a new Clustering Poisson atmospheric noise model is developed to describe the clustering process. This new statistical model is based on several previously known statistical‐physical models of atmospheric radio noise, but in addition to these models it takes into account the clustering of sferic impulses. It is shown that the clustering model accurately characterizes the impulse interarrival time distributions found in low‐frequency radio noise data.
Mesozoic basin development and tectonic evolution of the Dabieshan orogenic belt, central China
Authors: Liu Shaofeng , Heller Paul L. , Zhang Guowei
Published: August 2003

The Dabieshan orogenic belt is a zone of long‐lived shortening with late‐stage extension that formed during Mesozoic time in central China. Regional basin analysis coupled with structural cross sections provides a means of reconstructing the paleogeography of the region from Triassic continental collision through early Tertiary extension. The overall distribution of different basin types in the orogenic belt indicates that there was a prolonged period of shortening throughout the Mesozoic that became less intense over time. Meanwhile, extension became more common from Jurassic into Tertiary time. Either compression or extension was isochronous but limited to different geographic regions and/or crustal levels or alternated repeatedly orogen‐wide through time. Nonetheless, the orogen underwent gradual transition from overall shortening and crustal thickening to dominantly extension and rift basin formation although these events overlapped in time from the Jurassic through Early Cretaceous. Penecontemporaneous compression and extension across the orogen may reflect long‐term (>100 m.y.) shortening and crustal thickening leading to gravitational spreading of the resultant thick crustal welt. We suspect that this prolonged history of shortening across two nearby (∼100 km apart) suture zones played some role in the exhumation of ultrahigh‐pressure rocks from beneath the Dabieshan.
Remote sensing of vertical distributions of smoke aerosol off the coast of Africa
Authors: Kaufman Y. J. , Haywood J. M. , Hobbs P. V. , Hart W. , Kleidman R. , Schmid B.
Published: August 2003

In 2004 NASA plans to launch the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations — CALIPSO mission, with a two‐wavelength lidar aboard. CALIPSO will fly in formation with the Moderate Resolution Imaging Spectro‐Radiometer (MODIS) on the Aqua satellite. Here we present inversions of combined aircraft lidar and MODIS data to study the properties of smoke off the southwest coast of Southern Africa. The inversion derives profiles of the aerosol extinction due to fine and coarse particles. Comparisons with three sets of airborne in situ measurements show excellent agreement of the aerosol extinction profiles; however the inversion derives smaller spectral dependence of the extinction than the in situ measurements. The inversion is sensitive to the aerosol backscattering‐to‐extinction ratio (BER). Due to nonsphericity of the coarse aerosols, the range of BERs of the smoke aerosol is 0.014 to 0.021 sr−1 for the fine and coarse particles at 0.53 and 1.06 μm wavelengths, which do not differ much from the value for dust (0.016 sr−1) at these wavelengths.
The relative motion between Africa and Eurasia as derived from ITRF2000 and GPS data
Authors: Fernandes R. M. S. , Ambrosius B. A. C. , Noomen R. , Bastos L. , Wortel M. J. R. , Spakman W. , Govers R.
Published: August 2003

Studies of intra‐ and inter‐plate deformation typically need a model describing the motions of the stable part of the tectonic plates for reference purposes. We have developed DEOS2k, a model for the current motion of seven major tectonic plates derived from space‐geodetic observations. This paper focuses on relative motion between Africa and Eurasia. In the past, this motion has been poorly established because of poor data coverage for Africa. DEOS2k is based on ITRF2000 [Altamimi et al., 2002] and new African GPS observations. It is an improvement over the NUVEL‐1A model for predicting the present‐day relative motions of these two plates. DEOS2k predicts in northeastern Africa that Africa‐Eurasia relative motion is about 40% smaller in magnitude than NUVEL‐1A and trends more to the northwest. This is consistent with independent local geodetic observations. A similar shift in orientation, clockwise, is observed at the western tip of the plate boundary.
Stability and significance tests for b‐value anomalies: Example from the Tyrrhenian Sea
Authors: Schorlemmer D. , Neri G. , Wiemer S. , Mostaccio A.
Published: August 2003

We spatially map b‐values in the Southern Tyrrhenian Subduction Zone (Italy). A high b‐value anomaly 90–200 km beneath the Aeolian Island volcanoes is interpreted as being related to the origin of magma for the Aeolian volcanic district. This result is independent of the sample size, width of the cross‐section or its orientation. To assess the stability of these findings, we develop a new, more realistic, uncertainty assessment based on a bootstrap method. Our approach explicitly takes into account the uncertainty in the assessment of the completeness in magnitude reporting. To quantify the significance of the results when compared to a chance occurrence, we compute Monte Carlo style simulations based on catalogs with permuted magnitudes. Our entire tests show that the high b‐value anomaly is stable and highly significant.
Friction wind speeds in dust devils: A field study
Authors: Balme Matthew , Metzger Stephen , Towner Martin , Ringrose Tim , Greeley Ronald , Iversen James
Published: August 2003

Using in‐situ field measurements, we determined surface friction velocities (u*) and aerodynamic roughness heights (z0) at the base of 10 dust devils. z0 values agree closely with previous studies in this region and range from 0.1 to 1.0 cm. The peak u* coincide with the largest wind speed measurements within the dust devil and range from 0.9 to 2.4 ms−1. Surface friction velocities are sufficient to lift all types of windblown material from dust to pebble sized particles. Peak u* values for dust devils appear to be a linear function of the peak wind speed measured at ∼2 m height within the dust devil. This provides a simple approximation for estimating surface shear stress for dust devils.
Mesospheric gravity waves over a tropical convective region observed by OH airglow imaging in Indonesia
Authors: Nakamura T. , Aono T. , Tsuda T. , Admiranto A. G. , Achmad E. , Suranto
Published: September 2003

From OH airglow imaging observation carried out over one year in Indonesia, 74 events of gravity waves in the MLT (Mesosphere and Lower Thermosphere) region were extracted. Observed period, horizontal wavelength and observed horizontal phase speeds of gravity waves were typically 5–13 min, 13–45 km and 37–75 m/s, respectively. Propagation directions were mostly southward except for the period between December and February, when eastward propagation was preferential. Spatial distributions of tropospheric clouds, estimated with GMS (Geostationary Meteorological Satellite) were consistent with the propagation direction of gravity waves, i.e., these clouds mainly existed in the opposite direction to the propagation direction of waves. This suggests that horizontal propagation characteristics of the short period gravity waves in the low latitude MLT region are mainly affected by the distribution of the wave sources in the troposphere, and the effect of the background mean wind in the middle atmosphere is smaller, as it is weaker (∼20 m/s) in the equatorial region.
The effect of the second order GPS ionospheric correction on receiver positions
Authors: Kedar S. , Hajj G. A. , Wilson B. D. , Heflin M. B.
Published: August 2003

The Global Positioning System (GPS) transmits two frequencies, allowing users to correct for the first‐order ionospheric signal group delay (or phase advance) of 1–50 m. The second‐order ionospheric term, caused by the Faraday rotation effect induced by the Earth magnetic field, is about 1000 times smaller and usually ignored. In this study, we implement the 2nd‐order correction suggested by Bassiri and Hajj [1993] and investigate its effect on GPS‐inferred station positions. The correction causes a latitude dependent ∼0.1–0.5 cm southward shift to the position which is roughly proportional to the integrated electron density above the receiver, and has strong diurnal, seasonal and decadal signatures. By analyzing a three‐year time series of equatorial station positions obtained without the 2nd‐order correction, a strong semi‐annual north‐south oscillation is observed, the origin of which has not been hitherto explained. We verify that this apparent oscillation can be largely removed once the 2nd‐order correction is applied.
Impact of iceberg C‐19 on Ross Sea primary production
Authors: Arrigo Kevin R. , van Dijken Gert L.
Published: August 2003

For the second time in 26 months, a large iceberg (C‐19) calved off the face of the Ross Ice Shelf. Rather than breaking up, as did its predecessor B‐15, the iceberg C‐19 remained largely intact, eventually stopping temporarily near Pennell Bank before moving out of the southwestern Ross Sea. The presence of C‐19 restricted advection of sea ice out of the region, resulting in unusually high sea ice cover during the spring and summer. Consequently, phytoplankton blooms in the region were diminished dramatically and primary production was reduced by over 90%, relative to normal years. Calving events over the last two decades indicate that reduced primary productivity may be a typical consequence of large icebergs that drift through the southwestern Ross Sea during spring and summer.
Structure and mixing across an Arctic/Atlantic front in northern Baffin Bay
Authors: Lobb Julie , Carmack Eddy C. , Ingram R. Grant , Weaver Andrew J.
Published: August 2003

A front forms in northern Baffin Bay (∼75.25°N) between Atlantic‐derived water carried by the West Greenland Current and Arctic‐derived waters exiting southward through Nares Strait and Jones Sound via the Baffin Current. Subsurface waters (e.g. below 100 m) of the West Greenland Current are as much as 2°C warmer than those of the Baffin Current. Confluence of these waters leads to a frontal transition between 100–500 m wherein cross‐frontal gradients of potential temperature (Δθ/ΔL ∼ 0.06–0.07 °C·km−1) and salinity (ΔS/ΔL ∼ 0.005–0.007 PSU·km−1) are largely density compensating (Δσθ/ΔL ∼ 0.001 km−1). Subsequent thermohaline interleaving establishes conditions conducive to mixing via cabelling and double‐diffusion. The front's location would allow it to play a contributing role in the formation of Baffin Current water structure and eventual export of freshwater to the North Atlantic.
Non‐migrating diurnal tides generated with planetary waves in the Mesosphere
Authors: Mayr H. G. , Mengel J. G. , Talaat E. R. , Porter H. S. , Chan K. L.
Published: August 2003

We report results from our Numerical Spectral Model (NSM) that incorporates Hines' parameterization for small‐scale gravity waves (GW). The NSM generates non‐migrating tides in the mesosphere having amplitudes comparable to those observed, and we demonstrate that they arise from interactions between migrating tides and planetary waves (PW). We examine this mechanism for the large m = 0 diurnal tide, which was proposed to be generated with m = 1 PWs. The NSM is run for comparison without the zonal mean heat source, which suppresses the PWs that normally are excited by instabilities. The resulting amplitudes of the stationary tide are then negligibly small. When the time dependent GW momentum source for m = 0 is turned off, the stationary tide is significantly reduced. This indicates that, in the NSM, GWs play an important role in generating the nonlinear interactions between migrating tides and PWs that are necessary to produce the non‐migrating tides.
Ionospheric effects of the Leonid meteor shower in November 2001 as observed by rapid run ionosondes
Authors: Maruyama Takashi , Kato Hisao , Nakamura Maho
Published: August 2003

We operated ionosondes at four stations in a rapid‐run mode to obtain ionograms every minute for 102 hours during the period of the Leonid meteor shower in November 2001. Plenty of radio echoes that looked like echo traces produced by sporadic E reflection were seen in the ionograms, and this allowed statistical analysis in a single meteor shower event, including discrimination of the backscattering by meteor trails from reflection by a horizontally stratified sporadic E layer. The radio echoes seen in the ionograms were categorized into three types. The first were spontaneous echoes, which were distributed across a wide range of virtual heights; at times during the period of maximum meteor activity, there was a statistically good correlation among the echoes seen at the four stations. The echoes of this type appear to be produced by Fresnel backscattering from meteor trails. The second were also spontaneous echoes observed during the shower period but persisted for several tens of minutes at the same virtual height as the typical sporadic E layer, and the top frequency of these echoes decayed with time. Echoes of this type are thus attributed to the reflection from a meteor‐induced sporadic E patch. Echoes of the last type appeared outside the period of maximum activity of the meteor shower in the same range of virtual heights as the conventional sporadic E layer, and there was no time correlation between the events observed at the four stations. These events are attributed to a periodical increase in fOEs, which is modulated by planetary‐wave activity, and have no relation with the meteor shower.
Cassini between Venus and Earth: Detection of interstellar dust
Authors: Altobelli N. , Kempf S. , Landgraf M. , Srama R. , Dikarev V. , Krüger H. , Moragas‐Klostermeyer G. , Grün E.
Published: August 2003

We report the successful in situ measurement of interstellar dust particles inside the orbit of the Earth with the Cosmic Dust Analyzer (CDA) on the Cassini spacecraft. The impact ionization subsystem of the CDA is similar to the instruments on Ulysses and Galileo. As the heliocentric velocity and the direction of the interstellar dust flux are well known from Ulysses measurements, a combined analysis of the impact charge signals together with geometric and kinematic spacecraft data allowed us to separate interplanetary impacts from interstellar ones. The mean interstellar flux between 0.7 and 1.2 AU derived from our analysis is 2.5 ± 0.5 · 10−5 m−2s−1, in a mass range of 5 · 10−17 kg to 10−15 kg which is in good agreement with the interstellar dust flux measured by Ulysses at 3 AU during the same time period [Landgraf et al., 2003]. The simultaneous detection of interstellar grains by Ulysses at 3 AU and approximately 1 AU by Cassini proves that big interstellar grains (radius greater than 0.4 μm), can penetrate deeply into the inner solar system.
Cosmic ray energy loss in the heliosphere: Direct evidence from electron‐capture‐decay secondary isotopes
Authors: Niebur S. M. , Scott L. M. , Wiedenbeck M. E. , Binns W. R. , Christian E. R. , Cummings A. C. , Davis A. J. , George J. S. , Hink P. L. , Israel M. H. , Leske R. A. , Mewaldt R. A. , Stone E. C. , von Rosenvinge T. T. , Yanasak N. E.
Published: August 2003

Measurements by the Cosmic Ray Isotope Spectrometer (CRIS) on the Advanced Composition Explorer (ACE) spacecraft provide direct evidence that galactic cosmic rays lose energy as a result of their interactions with magnetic fields expanding with the solar wind. The secondary isotopes 49V and 51Cr can decay to 49Ti and 51V, respectively, only by electron capture. The observed abundances of these isotopes are directly related to the probability of attaching an electron from the interstellar medium; this probability decreases strongly with increasing energy around a few hundred MeV/nucleon. At the highest energies observed by CRIS, electron attachment on these nuclides is very unlikely, and thus 49V and 51Cr are essentially stable. At lower energies, attachment and decay do occur. Comparison of the energy dependence of the daughter/parent ratios 49Ti/49V and 51V/51Cr during solar minimum and solar maximum conditions confirms that increased energy loss occurs during solar maximum. This analysis indicates an increase in the modulation parameter ϕ of about 400 to 700 MV corresponding to an increase in average energy loss for these elements of about 200 to 300 MeV/nucleon.
An examination of the chemistry of peroxycarboxylic nitric anhydrides and related volatile organic compounds during Texas Air Quality Study 2000 using ground‐based measurements
Authors: Roberts James M. , Jobson Bertram T. , Kuster William , Goldan Paul , Murphy Paul , Williams Eric , Frost Gregory , Riemer Daniel , Apel Eric , Stroud Craig , Wiedinmyer Christine , Fehsenfeld Fred
Published: August 2003

Measurements of peroxycarboxylic nitric anhydrides (PANs) along with related volatile organic compounds (VOCs) were made at the La Porte super site during the TexAQS 2000 Houston study. The PAN mixing ratios ranged up to 6.5 ppbv and were broadly correlated with O3, characteristic of a highly polluted urban environment. The anthropogenic PAN homologue concentrations were generally consistent with those found in other urban environments; peroxypropionic nitric anhydride (PPN) averaged 15%, and peroxyisobutyric nitric anhydride (PiBN) averaged 3% of PAN. Some periods were noted where local petrochemical sources resulted in anomalous PANs chemistry. This effect was especially noticeable in the case of peroxyacrylic nitric anhydride (APAN) where local sources of 1,3‐butadiene and acrolein resulted in APAN as high as 30% of PAN. Peroxymethacrylic nitric anhydride (MPAN) was a fairly minor constituent of the PANs except for two periods on 4 and 5 September when air masses from high biogenic hydrocarbons (BHC) areas were observed. BHC chemistry was not a factor in the highest ozone pollution episodes in Houston but may have an impact on daily average ozone levels in some circumstances.
Implications of ice core smoothing for inferring CO2 flux variability
Authors: Trudinger C. M. , Rayner P. J. , Enting I. G. , Heimann M. , Scholze M.
Published: August 2003

Ice core records are commonly used to infer information about past variability of CO2 fluxes. Because of processes involved in enclosing this air in ice, ice core records are a smoothed representation of the actual past atmospheric variations. As such, there is a limit to how much information ice core measurements can contain about flux variability on short timescales. With a numerical model of the firn processes we quantify this smoothing and describe how it can be reproduced with pulse response functions. We generate and make available pulse response functions for CO2 at the DE08 site on Law Dome, Antarctica. We discuss implications of the smoothing for inferring CO2 flux variability from the Law Dome ice core record. In particular we look at results from an intercomparison of terrestrial biosphere models over the twentieth century and show how much of the CO2 variability would be reflected in the Law Dome ice core record. We also smooth atmospheric δ13CO2 from a study that compared fixed and varying isotopic discrimination. We find that the impact of changing discrimination, shown previously to be large on interannual timescales, is small on the decadal scales accessible from ice core records.
Twenty‐five novel HLA‐B alleles
Authors: Steiner N.K. , Gans C. , Baldassarre L. , Bradshaw D. , Rizzo M. , Divekar S. , Koester R. , Ng J. , Hartzman R.J. , Hurley C.K.
Published: September 2003

Abstract Twenty‐five novel HLA‐B alleles are described in this paper: B*0729, B*1309, B*1814, B*1815, B*2724, B*2725, B*3539, B*3926, B*4037, B*4040, B*4042, B*4043, B*4044, B*4204, B*440203, B*4428, B*4429, B*4430, B*4505, B*5308, B*5309, B*5510, B*5511, B*570102, and B*5709. Most of the variants are single nucleotide substitutions. Two involve variants at the Bw4/Bw6 epitope. Two alleles carry substitutions of conserved amino acids.
Senescence and ageing in plants and cyanobacteria
Authors: Beck Erwin , Scheibe Renate
Published: August 2003

This article is an introductory synopsis of the papers on senescence and ageing, presented in this issue of Physiologia Plantarum. The major results of the individual articles have been put into contiguity and are briefly reviewed in the light of the literature. Genetically controlled processes and stochastic reactions closely interact in the course of ageing of an individual. This holds for the cells and tissues of green plants as well as for the strongly specialized heterocysts of filamentous cyanobacteria.
Analyzes of three common thrombophilic gene mutations in German women with recurrent abortions
Authors: Pauer Hans‐Ulrich , Voigt‐Tschirschwitz Thekla , Hinney Bernd , Burfeind Peter , Wolf Cornelia , Emons Günter , Neesen Jürgen
Published: September 2003

Background.  Several etiological factors have been proposed as a cause for recurrent fetal abortions. Changes in blood coagulation during pregnancy may play an important role in the occurrence of recurrent abortions (RA).

Methods.  The aim of this study was to investigate the prevalence of factor V Leiden, factor II prothrombin, and methylenetetrahydrofolatreductase (MTHFR) mutations in women with recurrent abortions (≥2 abortions) in the German population. The mean number of abortions was 3 (range 2–8).

Results.  Frequencies of the factor V Leiden mutation and the prothrombin G20210A mutation were equally high in the patient group compared with our control group (for factor V Leiden: 11/101 vs. 9/122; p‐value: 0.348; for prothrombin G20210A: 2/101 vs. 3/122; p‐value: 0.81). Moreover, in both the patient and control groups, 15 of the women were homozygous for the MTHFR C677T allele (15/101 vs. 15/122; p‐value: 0.635). The occurrence of FV Leiden, FII and MTHFR mutations was not significantly increased in the patient group compared with our control group.

Conclusion.  The results of the present study reveal no relationship between these common three thrombophilic mutations and recurrent abortions for the German population, and further studies are essentially recommended on whether a thrombophilia evaluation should be performed in patients with recurrent abortions.
Human estrogen sulfotransferase (SULT1E1) pharmacogenomics: gene resequencing and functional genomics
Authors: Adjei Araba A , Thomae Bianca A , Prondzinski Janel L , Eckloff Bruce W , Wieben Eric D , Weinshilboum Richard M
Published: August 2003

Estrogens are used as drugs and estrogen exposure is a risk factor for hormone‐dependent diseases such as breast cancer. Sulfate conjugation is an important pathway for estrogen metabolism. The sulfotransferase (SULT) enzyme SULT1E1 has the lowest Km values for estrogens and catecholestrogens of the 10 known human SULT isoforms.

We previously cloned and characterized the human SULT1E1 cDNA and gene as steps toward pharmacogenetic studies. In the present experiments, we set out to determine whether common, functionally significant genetic polymorphisms might exist for SULT1E1. As a first step, we ‘resequenced’ the eight SULT1E1 exons and exon–intron splice junctions as well as portions of the 5′‐flanking region using DNA from 60 African‐American and 60 Caucasian‐American subjects.

In all, 23 polymorphisms, 22 single nucleotide polymorphisms (SNPs) and one insertion deletion were observed. There were three nonsynonymous coding SNPs (cSNPs) that altered the following encoded amino acids: Asp22Tyr, Ala32Val and Pro253His. Among these, 12 pairs of SNPs were tightly linked. In addition, 12 unambiguous SULT1E1 haplotypes were identified, including six that were common to both populations studied.

Transient expression in COS‐1 cells of constructs containing the three nonsynonymous cSNPs showed significant decreases in SULT1E1 activity for the Tyr22 and Val32 allozymes, with corresponding decreases in levels of immunoreactive protein. There were no changes in levels of either activity or immunoreactive protein for the His253 allozyme. Apparent Km values of the Val32 allozyme for the two cosubstrates for the reaction, 17β‐estradiol and 3′‐phosphoadenosine 5′‐phosphosulfate, were not significantly different from those of the wild‐type enzyme, but there was a two‐ to three‐fold increase in Km values for the His253 allozyme and a greater than five‐fold increase for the Tyr22 allozyme.

These observations raise the possibility that genetically determined variation in SULT1E1‐catalyzed estrogen sulfation might contribute to the pathophysiology of estrogen‐dependent diseases as well as variation in the biotransformation of exogenously administered estrogens.

British Journal of Pharmacology (2003) 139, 1373–1382. doi:10.1038/sj.bjp.0705369
An orally active adenosine A1 receptor antagonist, FK838, increases renal excretion and maintains glomerular filtration rate in furosemide‐resistant rats
Authors: Schnackenberg Christine G , Merz Emily , Brooks David P
Published: August 2003

Loop and thiazide diuretics are common therapeutic agents for the treatment of sodium retention and oedema. However, resistance to diuretics and decreases in renal function can develop during diuretic therapy. Adenosine causes renal vasoconstriction, sodium reabsorption, and participates in the tubuloglomerular feedback mechanism for the regulation of glomerular filtration rate.

We tested the hypothesis that the selective adenosine A1 receptor antagonist FK838 is orally active and causes diuresis and natriuresis, but maintains glomerular filtration rate in normal rats or in rats with furosemide resistance.

In normal male Sprague – Dawley rats, FK838 dose‐dependently increased urine flow and sodium and chloride excretion while sparing potassium. In combination with furosemide, FK838 enhanced the diuretic and natriuretic actions of furosemide to the same extent as hydrochlorothiazide and did not increase the potassium loss in normal rats. In furosemide‐resistant rats, FK838 increased urine flow and electrolyte excretion to a greater extent than hydrochlorothiazide. In addition, hydrochlorothiazide significantly decreased glomerular filtration rate, whereas FK838 maintained glomerular filtration rate in furosemide‐resistant rats.

This study shows that the adenosine A1 receptor antagonist FK838 is orally active and causes potent diuresis and natriuresis and maintains glomerular filtration rate in normal or furosemide‐resistant rats. Adenosine A1 receptor antagonists may be novel therapeutics for the treatment of oedema in normal or otherwise diuretic‐resistant patients.

British Journal of Pharmacology (2003) 139, 1383–1388. doi:10.1038/sj.bjp.0705370
In vitro and ex vivo effects of a selective nociceptin/orphanin FQ (N/OFQ) peptide receptor antagonist, CompB, on specific binding of [3H]N/OFQ and [35S]GTPγS in rat brain and spinal cord
Authors: Yamada Shizuo , Kusaka Toyofumi , Urayama Akihiko , Kimura Ryohei , Watanabe Yasuo
Published: August 2003

A novel selective nociceptin/orphanin FQ (N/OFQ) peptide receptor antagonist, 1‐[(3R,4R)‐1‐cyclooctylmethyl]‐3‐hydroxymethyl‐4‐piperidyl)‐3‐ethyl‐1,3‐dihydro‐2H‐benzimidazol‐2‐one (CompB), inhibited specific binding of [3H]N/OFQ to crude membranes from the rat brain and spinal cord in a concentration‐dependent manner and their Ki values were 7.11 and 4.02 nM, respectively. Rosenthal analysis indicated that there was a significant increase in the Kd value for [3H]N/OFQ binding in the brain and spinal cord in the presence of CompB (10 nM).

There was a dose‐dependent increase in Kd values for [3H]N/OFQ binding in the brain and spinal cord following i.v. injection of CompB at relatively low doses (0.69–6.88 μmol kg−1), compared with the control values. In the spinal cord, enhancement with each dose was constantly greater and the duration of enhancement (6.88 μmol kg−1) was significantly longer.

The degree of increase in Kd values for [3H]N/OFQ binding after i.v. injection of CompB (6.88 μmol kg−1) was significantly larger in the lumbar region of the spinal cord compared to other regions.

CompB (0.1, 0.3 μM) shifted the concentration–effect curves of N/OFQ‐stimulated [35S]GTPγS binding in the brain and spinal cord to the right.

The i.v. injection of CompB (6.88 μmol kg−1) significantly suppressed the N/OFQ‐stimulated [35S]GTPγS binding in the rat spinal cord and shifted the concentration–effect curve to the right, while it produced little inhibitory effect in the brain. The present study has shown that CompB may exhibit pharmacological effects through a predominant blockade of N/OFQ peptide receptors in the spinal cord under in vivo conditions.

British Journal of Pharmacology (2003) 139, 1462–1468. doi:10.1038/sj.bjp.0705371
GABAB receptor agonists reverse akinesia following intranigral or intracerebroventricular injection in the reserpine‐treated rat
Authors: Johnston Tom , Duty Susan
Published: August 2003

This study examined whether GABAB receptor agonists injected directly into the substantia nigra pars reticulata (SNr) and globus pallidus (GP), or given intracerebroventricularly, could reverse reserpine‐induced akinesia in the rat.

Male Sprague–Dawley rats, stereotaxically cannulated above the SNr, GP or third ventricle, were rendered akinetic by injection of reserpine (5 mg kg−1 s.c.). After 18 h, the locomotor effects of the GABAB receptor agonists, baclofen or SKF 97541 were examined.

Unilateral injection of baclofen (1–5 μg in 0.5 μl) into the GP failed to evoke any locomotor response (n=6). In contrast, unilateral intranigral injection of baclofen (0.08–1.6 μg in 0.5 μl) produced a dose‐dependent increase in net contraversive rotations reaching a maximum of 162±24 turns 90 min−1 (n=6–8). Pretreatment with the selective GABAB receptor antagonist, CGP 46381 (2.4 μg in 0.5 μl), inhibited the effects of baclofen (0.8 μg) by 68±9% (n=6).

Following intracerebroventricular injection, baclofen (0.8–4 μg in 2 μl) produced a dose‐dependent increase in net arbitrary locomotor units (ALUs), reaching a maximum of 447±154 ALUs in 35 min (n=6–7). SKF 97541 (4–32 μg in 2 μl) similarly reversed akinesia, reaching 129±69 ALUs in 15 min (n=6).

These data show that activation of GABAB receptors within the SNr, but not the GP, reverses reserpine‐induced akinesia. The success of intracerebroventricular injection of baclofen suggests a potential for systemically active GABAB receptor agonists in the treatment of akinesia in Parkinson's disease.

British Journal of Pharmacology (2003) 139, 1480–1486. doi:10.1038/sj.bjp.0705372
Tedisamil and lidocaine enhance each other's antiarrhythmic activity against ischaemia‐induced arrhythmias in rats
Authors: Sarraf Guilda , Barrett Terrance D , Walker Michael J A
Published: August 2003

Combinations of the action potential‐widening drug tedisamil (Class III antiarrhythmic activity), and the inactivated state sodium channel blocker lidocaine (Class Ib antiarrhythmic activity) were assessed for antiarrhythmic actions in a rat model of ischaemia‐induced arrhythmias and for electrophysiological actions in normal rat myocardial tissue.

Both tedisamil and lidocaine dose‐dependently suppressed ischaemia‐induced arrhythmias. The ED50 values were 3.0±1.3 and 4.9±0.6 μmol kg−1 min−1, respectively.

Combinations of the two drugs acted synergistically such that the ED50 for tedisamil was reduced to 0.8±0.2 μmol kg−1 min−1 in the presence of 2 μmol kg−1 min−1 lidocaine. Similarly, the ED50 for lidocaine was reduced to 0.7±0.2 μmol kg−1 min−1 in the presence of 2 μmol kg−1 min−1 tedisamil (both P<0.05).

In a separate series of experiments in which normal ventricular tissue was electrically stimulated, 2 μmol kg−1 min−1 lidocaine produced a leftward shift in the dose–response curve for tedisamil's effect on effective refractory period (P<0.05). This dose of lidocaine had no effect on its own. These data indicate that the synergistic actions of combinations of tedisamil and lidocaine were mediated, at least in part, by extension of effective refractory period in normal myocardial tissue.

In contrast to the strategy of developing drugs that are selective for a single electrophysiological mechanism, the results of the present study suggest that effective antiarrhythmic drugs might be developed by optimising the combination of two complimentary electrophysiological mechanisms (i.e., action potential‐prolonging activity and inactivated state sodium channel blockade).

British Journal of Pharmacology (2003) 139, 1389–1398. doi:10.1038/sj.bjp.0705373
Irreversible and reversible pore formation by polymeric alkylpyridinium salts (poly‐APS) from the sponge Reniera sarai
Authors: McClelland D , Evans R M , Abidin I , Sharma S , Choudhry F Z , Jaspars M , Sepčić K , Scott R H
Published: August 2003

In this study, we investigated the electrophysiological actions of a high molecular weight fraction, predominantly containing two polymeric 1,3‐alkylpyridinium salts (poly‐APS) of 5.5 and ∼19 kDa isolated from the marine sponge Reniera sarai. The biological properties of poly‐APS are of particular interest because this preparation may be used to deliver macromolecules into the intracellular environment without producing long‐term damage to cells. Poly‐APS (50–0.05 μg ml−1) was applied to cultured dorsal root ganglion neurones or HEK 293 cells and changes in cell membrane properties were measured using whole‐cell patch‐clamp recording and fura‐2 Ca2+ imaging.

Poly‐APS (50 μg ml−1) evoked irreversible depolarisations in membrane potential and reductions in input resistance. However, doses of 5 μg ml−1 and less produced reversible effects on these cell membrane characteristics and on Ca2+ permeability.

At 0.05 μg ml−1, poly‐APS could robust transient increases in Ca2+ permeability without damaging the neurones or subsequently attenuating Ca2+ entry through voltage‐activated channels.

Bathing cells in NaCl‐based extracellular medium containing 1.5 mM zinc attenuated the irreversible and reversible effects of poly‐APS on membrane properties (membrane potential, input resistance and whole‐cell currents). In both DRG neurones and HEK 293 cells, zinc attenuated Ca2+ entry evoked by poly‐APS. These effects of zinc were only observed if zinc was continually present during poly‐APS application. However, zinc failed to attenuate the actions of poly‐APS if it was applied after the sponge toxin preparation had evoked changes in membrane properties.

In conclusion, the pore‐forming preparation poly‐APS can have dose‐dependent interactions with cell membranes and at low doses these can be reversible. Additionally, the interactions between poly‐APS and cell membranes could be attenuated by zinc.

British Journal of Pharmacology (2003) 139, 1399–1408. doi:10.1038/sj.bjp.0705374
Pharmacological characterization of prostanoid receptors mediating vasoconstriction in human umbilical vein
Authors: Daray Federico Manuel , Minvielle Ana Itatí , Puppo Soledad , Rothlin Rodolfo Pedro
Published: August 2003

This study was undertaken to characterize pharmacologically the prostanoid receptor subtypes mediating contraction in human umbilical vein (HUV).

HUV rings were mounted in organ baths and concentration–response curves to U‐46619 (TXA2 mimetic) were constructed in the absence or presence of SQ‐29548 or ICI‐192,605 (TP receptor antagonists). U‐46619 was a potent constrictor (pEC50: 8.03). SQ‐29548 and ICI‐192,605 competitively antagonized responses to U‐46619 with pKB values of 7.96 and 9.07, respectively.

Concentration–response curves to EP receptor agonists: PGE2, misoprostol and 17‐phenyl‐trinor‐PGE2 gave pEC50 values of 5.06, 5.25 and 5.32, respectively. Neither pEC50 nor maximum of PGE2 and 17‐phenyl‐trinor‐PGE2 concentration–response curves were modified by the DP/EP1/EP2 receptor antagonist AH 6809 (1 μM). However, ICI‐192,605 produced a concentration‐dependent antagonism of the responses to all the EP receptor agonists. The pA2 estimated for ICI‐192,605 against PGE2 or misoprostol were 8.91 and 9.22, respectively.

Concentration–response curves to FP receptor agonists: PGF2α and fluprostenol gave pEC50 values of 6.20 and 5.82, respectively. ICI‐192,605 (100 nM) was completely ineffective against PGF2α or fluprostenol. In addition, lack of antagonistic effect of AH 6809 (1 μM) against PGF2α was observed.

In conclusion, the findings obtained with TP‐selective agonist and antagonists provide strong evidence of the involvement of TP receptors promoting vasoconstriction in HUV. Furthermore, the action of the natural and synthetic EP receptor agonists appears to be mediated via TP receptors. On the other hand, the results employing FP receptor agonists and antagonists of different prostanoid receptors suggest the presence of FP receptors mediating vasoconstriction in this vessel.

British Journal of Pharmacology (2003) 139, 1409–1416. doi:10.1038/sj.bjp.0705375
Phenylglycine derivatives as antagonists of group III metabotropic glutamate receptors expressed on neonatal rat primary afferent terminals
Authors: Miller Jacqueline C , Howson Patrick A , Conway Stuart J , Williams Richard V , Clark Barry P , Jane David E
Published: August 2003

Three novel phenylglycine analogues; (RS)‐α‐methyl‐3‐chloro‐4‐phosphonophenylglycine (UBP1110), (RS)‐α‐methyl‐3‐methoxy‐4‐phosphonophenylglycine (UBP1111) and (RS)‐α‐methyl‐3‐methyl‐4‐phosphonophenylglycine (UBP1112) antagonised the depression of the fast component of the dorsal root‐evoked ventral root potential induced by (S)‐AP4 with apparentKDvalues of: 7.4±2.3, 5.4±0.6 and 5.1±0.3μM(alln=3), respectively.

A Schild analysis of the antagonism of (S)‐AP4 induced depression of synaptic transmission by UBP1112 revealed a pA2value of 5.3 and a slope of 0.81±0.26 (n=9).

None of the phenylglycines tested were potent antagonists of responses mediated by group II mGlu receptors (apparentKDvalues >480μM). UBP1112 when tested at a concentration of 1 mMhad little or no activity on (S)‐3,5‐DHPG‐, NMDA‐, AMPA‐ or kainate‐induced responses on motoneurones.

British Journal of Pharmacology(2003)139, 1523–1531. doi:10.1038/sj.bjp.0705377