bluuebunny/crossref_metadata_2025 huggingface dataset:
Zur Validität des Fragebogens zur Erfassung aggressiver Verhaltensweisen im Straßenverkehr (AViS)
Authors: Herzberg Philipp Yorck
Published: October 2004

Zusammenfassung: Für den Fragebogen zur Erfassung aggressiver Verhaltensweisen im Straßenverkehr (AViS) werden Befunde zur Konstrukt- und Kriterienvalidität (N = 841) berichtet. Die Studien zur Konstruktvalidität des AViS belegen eine theoretisch sinnvolle Einbettung verkehrsspezifischer Aggressionen in das untersuchte nomologische Netzwerk aus allgemeiner Aggression, psychologischer Reaktanz, Konfliktbewältigungsstrategien und generellen Persönlichkeitseigenschaften, wie sie mit dem EPP-D erhoben wurden. Zusammenhänge mit Indikatoren des Verkehrsverhaltens, bspw. zur Unfallbeteiligung, Verkehrsverstößen und Führerscheinentzug, belegen die Kriterienvalidität der Punktwerte des AViS. Dabei zeigte sich die Überlegenheit des AViS gegenüber allgemeinen Aggressionsmaßen.
Measurements of dielectric loss factors due to a Martian dust analog
Authors: Williams Kevin K. , Greeley Ronald
Published: October 2004

Radar signals can penetrate loose sediments such as dust, sand, and alluvium to reveal buried geologic structures obscured in visible and infrared images. In anticipation of data from instruments such as the MARSIS and SHARAD radar sounders and potential future imaging SAR and rover‐mounted GPR instruments, measurements have been made to characterize electrical loss factors of a Martian dust analog and an iron‐rich soil. This paper presents results from dielectric measurements of Carbondale Red Clay (CRC) and the palagonitic Mars JSC‐1 soil simulant from 0.2 to 1.3 GHz and from transmission measurements of radar penetration of CRC up to 12 GHz. Attenuations predicted from dielectric measurements are compared to values measured in the experiment and are discussed relative to the frequencies at which imaging radars operate. Over the frequencies considered, loss tangent, tan δ, decreases with increasing frequency, but attenuation increases due to the influence of wavelength. Attenuation in CRC ranges from 8 to 22 dB/m over P and L bands and jumps to 36 and 67 dB/m at C and X bands, respectively. Mars JSC‐1 has lower attenuation of 5 dB/m at P band and ∼12 dB/m at L band. Compared to attenuation measurements of sand, both CRC and Mars JSC‐1 cause significantly greater attenuation, likely due to their compositions containing iron‐bearing minerals. Because Martian fine sediments also contain ferric mineral components, constraining higher losses of analogs for Martian dust and fine sediments is important for predicting the performance of radar instruments operating in orbit or on the surface of Mars.
Solar and interplanetary sources of major geomagnetic storms during 1996–2002
Authors: Srivastava Nandita , Venkatakrishnan P.
Published: October 2004

During the 7‐year period of the current solar cycle, 64 geoeffective coronal mass ejections (CMEs) were found to produce major geomagnetic storms (DST < −100 nT) at the Earth. In this paper we examine solar and interplanetary properties of these geoeffective coronal mass ejections (CMEs). The observations reveal that full‐halo CMEs are potential sources of intense geomagnetic activity at the Earth. However, not all full‐halo CMEs give rise to major geomagnetic storms, which complicates the task of space weather forecasting. We examine solar origins of the geoeffective CMEs and their interplanetary effects, namely, solar wind speed, interplanetary shocks, and the southward component of the interplanetary magnetic field, in order to investigate the relationship between the solar and interplanetary parameters. In particular, the present study aims at ascertaining solar parameters that govern important interplanetary parameters responsible for producing major geomagnetic storms. Our investigation shows that fast full‐halo CMEs associated with strong flares and originating from a favorable location, i.e., close to the central meridian and low and middle latitudes, are the most potential candidates for producing strong ram pressure at the Earth's magnetosphere and hence intense geomagnetic storms. The results also show that the intensity of geomagnetic storms depends most strongly on the southward component of the interplanetary magnetic field, followed by the initial speed of the CME and the ram pressure.
Derivation of electric potential patterns in the inner magnetosphere from Cluster EDI data: Initial results
Authors: Matsui H. , Jordanova V. K. , Quinn J. M. , Torbert R. B. , Paschmann G.
Published: October 2004

Electric potential patterns are derived in the inner magnetosphere at 4 < L < 10 using 2 years of data from the Electron Drift Instrument (EDI) on Cluster. First, we examine the relations between the electric field and the following three parameters to understand how the potential patterns are organized: BZ component of the interplanetary magnetic field (IMF), Kp index, and Dst index. From these correlations we can determine the effect of the interplanetary electric field (IEF) on the inner magnetospheric electric field as measured by Cluster. Next, the electric field is related to a quantity proportional to the injection rate of the plasma sheet particles, F(Dst*) ≡ (dDst*/dt + 0.13Dst*), where the effect of the magnetopause current is removed in Dst*. Then we develop a method to obtain potential patterns. An inverse problem is solved by adjusting a trade‐off parameter for smoothness of the result. The obtained potential patterns for three controlling parameters, IMF BZ, Kp index, and F(Dst*), are attached as supplemental material. We discuss the following features from these potential patterns: (1) potential drop, (2) rotation of the direction of the convection electric field, (3) dawn‐dusk asymmetry of the strength of the electric field, and (4) size of the last closed equipotential (LCE). This initial study is relevant to the development of an empirical model of inner magnetospheric convection in the equatorial plane.
Energy‐flux relationship in the FUV Jovian aurora deduced from HST‐STIS spectral observations
Authors: Gustin J. , Gérard J.‐C. , Grodent D. , Cowley S. W. H. , Clarke J. T. , Grard A.
Published: October 2004

Far ultraviolet spectral observations of the Jovian aurora have been made since 1997 with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope at low spectral resolution. The combination of the spectral resolution with the intensity variation along the STIS slit provides information on the latitudinal variation of the precipitating auroral electron energy flux and the mean electron energy, from which the electron current density at the top of the atmosphere can also be deduced. It is found that the mean electron energies associated with the main oval lie in the range 30–200 keV and show a tendency to increase with the precipitating energy flux. The current densities lie in the range ∼0.04–0.4 μA m−2, consistent with previous estimates, and are also positively correlated with the energy flux. The observed relationship between the auroral time‐integrated energy fluxes and the electron energies in the main oval is compatible with that expected from Knight's theory of field‐aligned currents. The best agreement between the observed data and the Knight curves is obtained for an electron temperature of Te = 2.5 keV and a source density N = 0.003 cm−3, that is within the range of values observed in the equatorial plane during the Voyager flybys. No systematic dependence of the electron energy with magnetic local time is found, but the morning sector around 0800 MLT shows greater variability than other regions of the oval. Analysis of time‐tagged data shows that the main oval energy flux usually varies steadily over the several minute intervals of observation and that the mean electron energy usually undergoes correlated variations such that the current density remains relatively constant. It is shown that these overall properties are also consistent with Knight's theory of auroral electron acceleration associated with field‐aligned current flow, from which it is inferred that the temporal variations observed are often due to slow changes in the magnetospheric “source” electron parameters in the presence of near‐steady magnetosphere‐ionosphere coupling currents. By contrast, time‐integrated emissions in the polar region are found to be associated with similar mean electron energies to the main oval but with typically smaller energy fluxes and current densities. Pressure balance arguments are advanced, which indicate that the brighter of these emissions must be associated with an auroral acceleration mechanism perhaps similar to that operative in the main oval, while it remains possible that the weaker emissions could result from precipitation from a quasi‐isotropic hot magnetospheric electron source.
Climatic versus biotic constraints on carbon and water fluxes in seasonally drought‐affected ponderosa pine ecosystems
Authors: Schwarz P. A. , Law B. E. , Williams M. , Irvine J. , Kurpius M. , Moore D.
Published: October 2004

We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought‐affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (<10%), largest at the MS (>50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age‐related shifts in carbon allocation and affect whole‐tree hydraulic conductance. Older forests, with well‐established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE.
Coupled crust‐mantle dynamics and intraplate tectonics: Two‐dimensional numerical and three‐dimensional analogue modeling
Authors: Pysklywec Russell N. , Cruden Alexander R.
Published: October 2004

Tectonic deformation of some intraplate regions may be caused by the Rayleigh‐Taylor (RT) instability of dense subcrustal lithosphere (mantle lithosphere) as it descends into the mantle. We report on a series of scaled three‐dimensional (3‐D) analogue and 2‐D numerical experiments of coupled crust‐mantle dynamics that study such a process. The models investigate the effects of two geometries of RT instability (linear versus axisymmetric) and use different rheological stratifications of the crust. The growth of the RT instability is strongly influenced by crustal rheology. While RT growth rates are not greatly influenced by the geometry of the mantle lithosphere instability itself, the surface is. Experiments having a viscous‐only crust are characterized by significant crustal contraction and thickening above the mantle downwelling and extension and thinning in adjacent regions. In experiments with a brittle upper crust the surface deformation is much more subdued. However, strong mantle flow‐induced deformation still occurs in the ductile lower crust beneath the quiescent brittle upper crust. When the lower crust is relatively strong, localized styles of extensional and contractional structure develop in the brittle upper crust owing to the greater degree of coupling between upper crust and the mantle instability. In all the experiments, a portion of the ductile lower crustal material is entrained within the downgoing RT instability deep into the mantle. The interplay between dynamic topography and crustal thickening/thinning induced by the underlying mantle flow governs various time‐dependent phases of subsidence and uplift of the model surface. The experiments help to account for a number of first‐order tectonic behaviors of the lithospheres of Earth and other terrestrial planets. For example, intraplate orogens and basins, complex localized tectonic structure in intraplate settings, and deep crustal seismic fabrics may arise as the variable crustal response to underlying mantle lithosphere RT instabilities.
Elemental abundance distributions in suboceanic basalt glass: Evidence of biogenic alteration
Authors: Storrie‐Lombardi M. C. , Fisk M. R.
Published: October 2004

The alteration of subseafloor volcanic glass from three locations is qualitatively attributed to biological (biotic) or chemical (abiotic) reactions on the basis of microscopic morphology of the boundary between the unaltered and altered glass. Eleven‐element composition of fresh basalt glass (sideromelane) and its alteration products were determined by electron microprobe. Principal component analysis (PCA) using these eleven elements as input (Na11, Mg12, Al13, Si14, P15, Cl17, K19, Ca20, Ti22, Mn25, and Fe26) extracts three factors accounting for 80.5% of the variance in the data. These three factors can serve as inputs to a hierarchical cluster analysis (HCA) algorithm for data‐driven discovery of three sample classes. This autonomous classification agrees with the petrographic microscopic classification in 14 of 15 biotic clay analyses. From a set of 34 analyses identified microscopically as abiotic clay the autonomous system identifies 4 with elemental abundance characteristics similar to the biotic clay and 4 similar to unaltered glass. PCA factors are then used as inputs to train an artificial neural network to produce a Bayesian probability of correct classification using the classes discovered by HCA. Mean Bayesian probabilities of correct classification for abiotic clays, biotic clays, and glass were 76.1 ± 8.5%, 64.9 ± 9.0%, and 77.0 ± 7.2%, respectively. Interestingly, in the 9 of 74 cases where visual and elemental analysis disagree, the Bayesian probability estimate of correct classification using only elemental abundance data is low (60.0 ± 11.7%) compared to analyses where visual and elemental data agree (75.5 ± 7.8%). To our knowledge, this is the first demonstration of a quantitative method for discrimination of biotic and abiotic alteration of subocean basalt glass. As such, the techniques make possible the systematic assessment of the impact of microbial life on subsurface basalts.
Rapid analysis of 13C in plant‐wax n‐alkanes for reconstruction of terrestrial vegetation signals from aquatic sediments
Authors: McDuffee Kelsey E. , Eglinton Timothy I. , Sessions Alex L. , Sylva Sean , Wagner Thomas , Hayes John M.
Published: October 2004

Long‐chain, odd‐carbon‐numbered C25 to C35n‐alkanes are characteristic components of epicuticular waxes produced by terrestrial higher plants. They are delivered to aquatic systems via eolian and fluvial transport and are preserved in underlying sediments. The isotopic compositions of these products can serve as records of past vegetation. We have developed a rapid method for stable carbon isotopic analyses of total plant‐wax n‐alkanes using a novel, moving‐wire system coupled to an isotope‐ratio mass spectrometer (MW‐irMS). The n‐alkane fractions are prepared from sediment samples by (1) saponification and extraction with organic solvents, (2) chromatographic separation using silica gel, (3) isolation of straight‐chain carbon skeletons using a zeolite molecular sieve, and (4) oxidation and removal of unsaturated hydrocarbons with RuO4. Short‐chain n‐alkanes of nonvascular plant origin (<C25) are removed by evaporation on the moving wire. Test samples processed using this procedure yielded n‐alkane fractions essentially free of interfering components. The δ13C values obtained by MW‐irMS did not differ significantly from weighted averages of individual n‐alkane δ13C values obtained by irmGC‐MS. Isotopic variations in compound‐class n‐alkane fractions from a latitudinal transect of core‐top sediments from the Southwest African margin (3°N–28°S) were congruent with those measured by compound‐specific isotopic analyses of plant‐wax n‐alkanes. The amplitude of the variations was smaller, indicating contributions from non‐plant‐wax hydrocarbons, but the measurements revealed variations in carbon isotopic composition that are consistent with vegetation zones on the adjacent continent.
Twentieth‐century climate change in New England and New York, USA
Authors: Trombulak Stephen C. , Wolfson Richard
Published: October 2004

We have analyzed twentieth‐century temperature data from 73 climate stations in New England and New York. Linear regression gives a 100‐year temperature change (ΔT100) for each station. All but two stations show an increase over this time, giving a regional area‐weighted average ΔT100 of 1.11°C. Average ΔT100 values for each state are all positive, ranging from 0.86°C to 1.86°C. Spatial autocorrelation analysis reveals a southeastern New England cluster of stations with relatively large ΔT100, and a cluster in western New York with low but still positive ΔT100. Thus, at differing spatial scales, temperature in this region increased during the twentieth century, in most cases by more than the global average increase of some 0.6°C during this same period. Our results contrast markedly with the New England Regional Assessment, and may have implications for other regional assessments undertaken under the auspices of the U.S. Global Change Research Program.
A quantitative explanation for the phenomenon known as storm‐enhanced density
Authors: Kelley Michael C. , Vlasov Michael N. , Foster John C. , Coster Anthea J.
Published: October 2004

This paper presents a quantitative explanation of storm‐enhanced density (SED). The plasma's root origin lies in the fully sunlit equatorial ionosphere where a penetrating zonal electric field drives plasma upward so fast that it cannot recombine. This plasma spills over into the anomaly and then is driven poleward by a penetrating zonal electric field. However, the poleward field cannot extend into the dayside due to high conductivity and the flow stagnates, causing plasma to build up in a narrow channel along the dusk terminator and flow into the convection pattern. It is remarkable that plasma finds its way into the polar cap from the daytime equator. We believe that this plasma structure is connected to the plasmaspheric tails reported in the literature.
Lithospheric and upper mantle stratifications beneath Tibet: New insights from Sp conversions
Authors: Wittlinger G. , Farra V. , Vergne J.
Published: October 2004

We assess the upper mantle structure under the Tibetan plateau from a S‐to‐P converted waves receiver functions study. Contrary to the Ps receiver functions blurred by multiples from Moho to 350 km depth, the Sp are better suited for imaging at these depths. The Moho is clearly recovered and often exhibits a complex and warped structure. The upper crust is marked by a significant low velocity zone in the southern part of the plateau, probably associated with partial melt, which vanishes north of the Bangong suture. In the upper mantle, between the Moho and the 660 km discontinuity, four stratification levels are identified. The strongest converter at a depth ranging between 120 to 180 km corresponds to the bottom of a low shear‐wave velocity layer imaged by surface wave inversion.
Seasonal variations in Saturn's E‐ring
Authors: Juhász Antal , Horányi Mihály
Published: October 2004

By following the trajectories of a large number of particles we capture the seasonal variations of the density and spatial distributions of dust in Saturn's E‐ring. We have used an optimized set of parameters from our earlier azimuthally symmetric ring model [Juhász and Horányi, 2002] to match remote sensing, and in situ observations as well. The model will be tested by the upcoming Cosmic Dust Analyzer (CDA) measurements onboard Cassini. It will be useful to find regions in the E‐ring where the source moon of the detected dust grains can be identified. In these regions CDA measurements of the chemical composition of the dust particles will enable us to learn about the surface properties of their moon of origin.
North Atlantic Subtropical Mode Water: A history of ocean‐atmosphere interaction 1961–2000
Authors: Kwon Young‐Oh , Riser Stephen C.
Published: October 2004

Water masses that ventilate intermediate ocean depth, such as the North Atlantic Subtropical Mode Water (NASTMW), play important roles in various aspects of climate, but their basic properties and space‐time variability need to be better quantified. Herein we examine the mean annual cycle and long‐term variability of NASTMW for the 40‐year period 1961–2000. Integrated NASTMW properties such as water mass volume, temperature, and heat content show a consistent annual cycle superimposed over a much larger interannual‐to‐decadal cycle that is strongly correlated to the North Atlantic Oscillation index. The 40‐year record clearly shows the ocean's ability to integrate atmospheric forcing over several years and to exhibit an interannual memory of wintertime forcing by the atmosphere.
Temporal evolution of substorm‐enhanced whistler‐mode waves: Relationship between space‐based observations, ground‐based observations, and energetic electrons
Authors: Abel G. A. , Smith A. J. , Meredith N. P. , Anderson R. R.
Published: October 2004

We examine 22 case studies of CRRES satellite observations of substorm‐enhanced whistler‐mode waves. These observations were made close to the geomagnetic equator and between 0200 and 0600 MLT. The frequency of the enhanced whistler‐mode waves is seen to vary strongly with magnetic field strength, and for this reason we plot the data in terms of the equivalent parallel resonant energy of an electron in first‐order cyclotron resonance with a wave of a given frequency. No consistent increase or decrease of the equivalent parallel resonant energy of the substorm‐enhanced whistler‐mode waves with time is seen; rather the typical behavior is that it remains constant with time. We interpret our findings in terms of the injected electron population and resonance ellipses in velocity space. Furthermore, we relate the findings of our study to observations of ducted waves seen on the ground as substorm chorus events (SCEs) and conclude that the frequency dispersion seen in SCEs is dominated by electric field effects.
On the direction of the Poynting flux related to the mesoscale electromagnetic turbulence at high latitudes
Authors: Golovchanskaya I. V. , Maltsev Y. P.
Published: October 2004

Up to now, several tens of theories for inverted‐V structure and discrete arc formation have been proposed. In about half of them the source of auroral structuring is supposed to be in the ionosphere, whereas a magnetospheric origin is inferred in others. In order to discriminate between these two classes of mechanisms, we have examined the observed direction of the high‐latitude Poynting flux δP = δE × δB associated with the structured electric δE and magnetic δB fields. The upward direction of δP would indicate an ionospheric generator of these fields, while downward δP is a signature of a magnetospheric mechanism at work. The analysis was performed for scales ranging from 3.8 km to a few hundreds of kilometers in the ionosphere, meaning that the irregularities under study can be identified with discrete auroral features. The electric and magnetic field measurements of the Dynamics Explorer 2 satellite (altitudes from 300 to 1000 km) for a period of one and a half years were used. We have found that in about 95% of cases the relative orientation of δE and δB is such that δP points downward, suggesting a magnetospheric origin of electromagnetic field structuring at high latitudes. Being averaged over the polar cap, δP exhibits a steady growth with northward Bz interplanetary magnetic field (IMF) increasing, while, averaged over the auroral oval, δP grows with increasing southward Bz IMF.
Energy budget of Alfven wave interactions with the auroral acceleration region
Authors: Pilipenko V. , Fedorov E. , Engebretson M. J. , Yumoto K.
Published: October 2004

We consider the interaction of Alfven waves with the auroral acceleration region (AAR), which is characterized by a mirror resistance and a related electric potential drop that supports a field‐aligned upward current and the acceleration of electrons. An Alfven wave incident on the AAR from the magnetosphere partially reflects back and partially penetrates into the AAR. An analytical treatment of the interaction of Alfven waves with the combined magnetosphere‐AAR‐topside ionosphere‐E layer system immersed into a converging dipole‐like magnetic field has been made within the “thin” AAR approximation. The rate of wave reflection/transmission is estimated to be critically dependent on the wave transverse scale. Incident Alfven waves with spatial scales about the Alfven damping scale λA are absorbed most effectively in the AAR. Magnetospheric Alfven waves penetrating into the AAR can produce oscillatory variations of the field‐aligned potential drop and field‐aligned electron acceleration. Modeling the spatial spectrum of an Alfven burst by a power‐law dependence ∝ k−p in the interval between low and high cutoff wave numbers indicates that the estimated rate of total wave power absorbed by the AAR is significant, up to 30–50% depending on p, when the ionospheric projection of the low cutoff wave number is on the order of the scale λA.
Signature of TEC storm on 6 November 2001 derived from dense GPS receiver network and ionosonde chain over Japan
Authors: Maruyama Takashi , Ma Guanyi , Nakamura Maho
Published: October 2004

Ionospheric disturbances during a magnetic storm on 6 November 2001 were analyzed using total electron content (TEC) calculated from measurements made with a dense GPS receiver network, GEONET, which covers the whole of Japan and F‐layer peak parameters obtained by a meridional ionosonde chain which consists of ionosondes at Wakkanai (45.39°N), Kokubunji (35.71°N), Yamagawa (31.20°N), and Okinawa/Ogimi (26.68°N). Maps of TEC as a function of latitude and time were compared with NmF2 and hpF2. A weak to moderate ionospheric positive storm in terms of fOF2 was associated with the magnetic storm. On the other hand, TEC was nearly doubled at all latitudes during the daytime. This event was the effect of a prompt penetrating eastward electric field in the presence of an enhanced equatorward neutral circulation, which was set up prior to the electric field penetration and persisted for more than 24 hours. The ionosphere was raised simultaneously by ∼100 km at the four ionosonde stations. The small ion‐neutral collision frequency at high altitudes results in loading of plasma into the plasmasphere. The significant difference in storm signatures between NmF2 and TEC was interpreted as increased upward plasma diffusion, which worked as a sink for the plasma at the F layer peak. The increase in TEC in the plasmasphere, however, was the order of 10 TEC units, which is insufficient to cause the large observed TEC enhancement but was responsible for maintaining the nighttime TEC enhancement. On the bottomside the plasma distribution departed significantly from the photochemical equilibrium due to the upwelling, and the photochemical production tended to adjust it, providing the major source of the great increase in TEC. At night, positive storm conditions both for NmF2 and TEC persisted at latitudes higher than 33°N, which was caused by the downward plasma flux and the equatorward neutral winds. At latitudes lower than 33°N, negative perturbation was observed in the evening hours, caused by the suppression of the evening enhancement of the eastward electric field.
Maps of precipitation by source region, binned by IMF, with inertial convection streamlines
Authors: Newell P. T. , Ruohoniemi J. M. , Meng C.‐I.
Published: October 2004

We present maps of ionospheric precipitation regions, based on 11 years of DMSP particle data, binned by the interplanetary magnetic field (IMF), with superposed SuperDARN convection streamlines gathered under similar conditions. The convection patterns are transformed into an inertial coordinate system. The maps, which include both the nightside and dayside, are created in a fully automated fashion, with, for example, the cusp centered at its centroid latitude for each half hour bin of MLT, with a latitudinal width equal to the statistical difference between the poleward and equatorward edges. The mantle asymmetry about noon does not fit the pattern expected from simple theoretical considerations (namely, that the mantle should be thicker postnoon for positive By in the Northern Hemisphere). The mantle is appreciably thicker prenoon than postnoon, especially for positive By but also even for negative By. This asymmetry matches the SuperDARN convection flows, in which, irrespective of the sign of By, most of the conversion of closed field lines to open occurs prenoon. Quantitatively expressed, for southward IMF, the potential encompassed by flux crossing the open‐closed boundary prenoon (0600–1200 MLT) exceeds that for postnoon (1200–1800 MLT) by 30 kV to 15 kV for By > 3 nT and by 30 kV to 20 kV for By < −3 nT. The mantle shape thus matches convection pattern variations. Only ∼25–35% of the dayside open‐closed field line conversion occurs within the particle cusp, with the lower number appropriate to northward IMF. Most closed‐to‐open field line conversion occurs away from noon. Merging is thus active throughout the frontside magnetosphere. Field lines that merge well away from noon do not experience enough particle inflow against the solar wind velocity to produce anything more than a weak, deenergized (mantle) precipitation. The boundary between the dusk cell and dawn cells consistently coincides with one edge of the cusp. IMF By also controls where most of the nightside reconnection occurs. For positive Bz and By > 3 nT, 31 kV reconnects from 1800 to 2400 MLT, but only 14 kV reconnects from 0000 to 06000 MLT. The convection reversal boundary (CRB) consistently coincides with the nightside open‐closed particle boundary (OCB). On the dayside, the CRB lies equatorward (poleward) of the OCB in the postnoon (prenoon) sector for By < 0 (By > 0). This shift is consistent with the effects of an interhemispheric current produced by the partial penetration of the IMF By into the frontside magnetosphere.
Subauroral morning proton spots (SAMPS) as a result of plasmapause‐ring‐current interaction
Authors: Frey H. U. , Haerendel G. , Mende S. B. , Forrester W. T. , Immel T. J. , Østgaard N.
Published: October 2004

The proton aurora imager SI‐12 on the IMAGE spacecraft occasionally observes subauroral morning proton spots (SAMPS) that rotate with 70–95% of the Earth's corotation speed. Coincident particle measurements by DMSP confirm the source to be pure precipitating protons with mean energies likely above the detector limit of 30 keV. The spots appear in the recovery phase after magnetic storms and last for 1–4 hours in the magnetic local time region of 0300–1200 hours. The latitude location is strongly related to the minimum Dst of the previous geomagnetic storm with the lowest latitude observations after the strongest storms. The rotation speed is related to the latitude (L shell) of the spots with the largest corotation lags for spots that map to the largest L shells. IMAGE‐EUV observations of the plasmasphere indicate a relationship with density gradients in the expanding plasmasphere after magnetic storms. We interpret these spots as the result of wave‐particle interaction. As one likely process, we suggest the interaction of ring current protons with electromagnetic ion‐cyclotron (EMIC) waves as a result of the expansion and subrotation of the dense, cold plasmasphere ions. The appearance of subauroral proton spots is therefore a consequence of the plasmasphere refilling after geomagnetic storms.
MHD stability of magnetotail equilibria including a background pressure
Authors: Schindler K. , Birn J.
Published: October 2004

This paper deals with ideal‐MHD stability of equilibrium configurations modeling the plasma sheet of the Earth's magnetotail. The approach exploits the fact that in the absence of a cross‐tail magnetic field component, the MHD stability problem for two‐dimensional (2‐D) equilibria under general 3‐D perturbations can be reduced to analyzing stability with respect to ballooning modes alone. The correspondingly specialized MHD energy principle is numerically minimized for three different equilibrium models. In all cases the stability of symmetric modes was governed by the interchange criterion based on entropy. A constant background pressure is included, which, even if small, can have a significant stabilizing effect. An analytical approach provides a set of rather simple stability criteria, which are consistent with the numerical minimization results. A main conclusion is that configurations with realistic tailward pressure profiles are found stable. For all three models the entropy criterion implies that stability transitions of the symmetric mode cannot occur during the adiabatic evolution of ideal‐MHD tail configurations.
Substorm onset observations by IMAGE‐FUV
Authors: Frey H. U. , Mende S. B. , Angelopoulos V. , Donovan E. F.
Published: October 2004

Over the first 2.5 years of operation, the FUV instrument on the IMAGE spacecraft observed more than 2400 substorm onsets in the Northern Hemisphere. The observations confirm earlier results of statistical studies in terms of a median substorm onset location at 2300 hours MLT and 66.4 degrees magnetic latitude. The purpose of this report is to publish the list to allow for further investigation. The list can easily be searched for onsets close to certain ground stations or at specific magnetic latitudes or local times. As one example of such use, we demonstrate how the probability of onset observation was determined for the ground‐based automatic observatories of the THEMIS (Time History of Events and Macroscale Interactions during Substorms) project.
Subionospheric early VLF signal perturbations observed in one‐to‐one association with sprites
Authors: Haldoupis C. , Neubert T. , Inan U. S. , Mika A. , Allin T. H. , Marshall R. A.
Published: October 2004

Observations on the night of 21 July 2003 of the ionospheric effects of a thunderstorm in central France are reported. From 0200 to 0315 UT, a camera system in the Pyrenees Mountains captured 28 sprites, triggered by +CG lightning as observed by the French METEORAGE lightning detection system. A narrowband VLF receiver located on Crete, at ∼2200 km southeast of the storm, observed subionospheric VLF signals from six ground‐based transmitters. The amplitude of one of the VLF signals, originating at a transmitter located ∼150 km west of the storm and passing through the storm region, exhibited rapid onset perturbations occurring in a nearly one‐to‐one relationship with the optical sprites. These “early” VLF events are consistent with a process of narrow‐angle forward scattering from a volume of enhanced ionization above the storm with lateral sizes larger than the VLF radio wavelength. The many +CG and −CG discharges that did not produce sprites were also found to not be associated with detectable VLF amplitude perturbations, even though some of these discharges reached relatively large peak currents. The rapid onsets of several of the sprite‐related VLF perturbations were followed by relatively long onset durations, ranging from ∼0.5 to 2.5 s, indicating that these events were early but not “fast.” These “early/slow” events may suggest a slow process of ionization build‐up in the lower ionosphere, following intense lightning discharges that also lead to sprites. A limited number of early VLF perturbation events were also associated with whistler‐induced electron precipitation events, or classic Trimpi perturbations, undoubtedly produced by the precipitation of electrons due to whistler‐mode waves injected into the magnetosphere by the same lightning flash that led to the production of the sprite.
Introduction to special section: Transport and transformation of biogeochemically important materials in coastal waters
Authors: Green Sarah A. , Eadie Brian J.
Published: October 2004

Two projects in the Laurentian Great Lakes were funded under the Coastal Ocean Processes Program. In Lake Superior the Keweenaw Interdisciplinary Transport Experiment in Superior (KITES) focused on a region dominated by a strong coastal jet, and a sister project in Lake Michigan, Episodic Events—Great Lakes Experiment (EEGLE), concentrated on the biogeochemical effects of a major plume of resuspended sediment that occurs annually in the southern portion of the lake.
Vertical extrapolation of Mars magnetic potentials
Authors: Jurdy Donna M. , Stefanick Michael
Published: October 2004

Mars Global Surveyor (MGS) measured the most strongly magnetized crust in the heavily cratered southern hemisphere of Mars. Our analysis concentrates on the magnetic lineations or patterns centered near latitude 40°S, longitude 180°W, with a range of values ±40°, using a rotated Cartesian coordinate system. We downward continued the magnetic field measured at ∼400 km elevation and very closely match the corresponding component measured during the aerobraking phase at altitudes extending down to ∼100 km. Using the vertical component of the magnetic field alone, we construct a unique scalar potential and independently obtain from the derivatives of this scalar potential the x and y components of the field. These derived components agree very well with the observed horizontal components. This demonstrates the validity and utility of the method and the Cartesian approximation, and also it confirms the consistency of the MGS magnetic data set. A model constructed with just 8 vertical dipoles accounts for 80% of the variance of the scalar potential at 400 km over the region analyzed, but 14 dipoles can account for only 64% of the variance at 100 km. We also construct the vector potential, the curl of which generates the three components of the magnetic field. This more complicated description may contain more physical meaning than the scalar potential. The vector potential shows abrupt changes in direction over the analyzed region, suggesting either different stages of magnetization or local demagnetization.
Estimation of flow properties using surface deformation and head data: A trajectory‐based approach
Authors: Vasco D. W.
Published: October 2004

A trajectory‐based algorithm provides an efficient and robust means to infer flow properties from surface deformation and head data. The algorithm is based upon the concept of an “arrival time” of a drawdown front, which is defined as the time corresponding to the maximum slope of the drawdown curve. The technique involves three steps: the inference of head changes as a function of position and time, the use of the estimated head changes to define arrival times, and the inversion of the arrival times for flow properties. Trajectories, computed from the output of a numerical simulator, are used to relate the drawdown arrival times to flow properties. The inversion algorithm is iterative, requiring one reservoir simulation for each iteration. The method is applied to data from a set of 14 tiltmeters, located at the Raymond Quarry field site in California. Using the technique, I am able to image a high‐conductivity channel which extends to the south of the pumping well. The presence of this permeable pathway is supported by an analysis of earlier cross‐well transient pressure test data.
Allergic sensitization enhances the contribution of Rho‐kinase to airway smooth muscle contraction
Authors: Schaafsma Dedmer , Gosens Reinoud , Bos I Sophie T , Meurs Herman , Zaagsma Johan , Nelemans S Adriaan
Published: October 2004

Repeated allergen challenge has been shown to increase the role of Rho‐kinase in airway smooth muscle (ASM) contraction. We considered the possibility that active allergic sensitization by itself, that is, without subsequent allergen exposure, could be sufficient to enhance Rho‐kinase‐mediated ASM contraction.

Guinea pigs were actively IgE‐sensitized to ovalbumin (OA), using Al(OH)3 as adjuvant. Contractile responsiveness to Gq‐coupled receptor agonists (methacholine, histamine or PGF2α) was investigated in tracheal rings. No effect of sensitization was observed on basal‐ and methacholine‐induced myogenic tone. In contrast, potency of histamine and PGF2α increased, that is, EC50 decreased, after OA‐sensitization by 2.6‐ and 4.7‐fold, respectively, without effect on maximal contraction (Emax).

Basal tone in preparations from both control and OA‐sensitized animals was strongly decreased in the presence of the Rho‐kinase inhibitor (+)‐(R)‐trans‐4‐(1‐aminoethyl)‐N‐(4‐pyridyl) cyclohexane carboxamide (Y‐27632) (1 μM). In control preparations, the Emax and potency of histamine were unaffected by Y‐27632, but were decreased for PGF2α (by 38.2% and 2.0‐fold, respectively). However, in preparations from OA‐sensitized animals, Y‐27632 induced a significant reduction in Emax (33.5%) and potency (2.3‐fold) of histamine and of PGF2α (48.3% and 6.6‐fold, respectively), normalizing the OA‐sensitization‐induced increase in sensitivity toward these agonists.

We also investigated the contribution of Rho‐kinase in vivo by measuring airway responsiveness toward inhaled histamine in permanently instrumented, unanaesthetized control and OA‐sensitized guinea pigs. Treatment with Y‐27632 by inhalation (5 mM, nebulizer concentration) decreased airway responsiveness toward histamine both in control and OA‐sensitized animals. However, the histamine PC100 ratio pre/post Y‐27632 inhalation was significantly smaller in OA‐sensitized animals as compared to control animals, indicating an enhanced contribution of Rho‐kinase.

Expression of RhoA, an upstream activator of Rho‐kinase, was significantly increased (2.6‐fold) in lung homogenates of OA‐sensitized guinea pigs compared to control animals, as determined by Western analysis.

In conclusion, the results show a receptor‐dependent role of Rho‐kinase in agonist‐induced ASM contraction. The contribution of Rho‐kinase to contractile airway responsiveness, both in vivo and ex vivo, is augmented after active allergic sensitization, as a consequence of increased expression of RhoA presumably. Inhibition of the RhoA/Rho‐kinase pathway may be considered a useful pharmacotherapeutical target in allergy and asthma.

British Journal of Pharmacology (2004) 143, 477–484. doi:10.1038/sj.bjp.0705903
Proteinase‐activated receptor‐4: evaluation of tethered ligand‐derived peptides as probes for receptor function and as inflammatory agonists in vivo
Authors: Hollenberg Morley D , Saifeddine Mahmoud , Sandhu Sabrina , Houle Steeve , Vergnolle Nathalie
Published: October 2004

We evaluated the ability of a number of peptides based on the tethered ligand sequences of human, rat and murine proteinase‐activated receptor‐4 (PAR4), to serve as receptor‐activating probes or antagonists for bioassays carried out in vitro and for in vivo models of inflammation.

In a rat PAR4‐dependent platelet aggregation assay, the relative potencies of the active sequences (AYPGKF‐NH2>GYPGKF‐NH2>GYPGFK‐NH2>GFPGKP‐NH2) were consistent with an activation of PAR4.

In the aggregation assay, the reverse or partial reverse‐sequence peptides (VQGPYG‐NH2, YAPGKF‐NH2 and FKGPYA‐NH2) were inactive, while trans‐cinnamoyl (Tc)‐YPGKF‐NH2, Tc‐APGKF‐NH2 and N‐palmitoyl‐SGRRYGHALR‐NH2 (pepducin P4pal‐10) were antagonists.

However, in an endothelium‐dependent NO‐mediated rat aorta (RA) relaxation assay and in a gastric longitudinal muscle (LM) contraction assay, these antagonist peptides were agonists as were most other peptides, with distinct orders of potencies that differed for both the RA and LM assays and from the platelet assay.

We conclude that PAR4‐derived tethered ligand peptide agonists can act at receptors other than PAR4 and that a judicious choice of ligands is required to probe for PAR4 function in bioassay systems and in particular for in vivo models.

By selecting from these peptides the ones most reliably reflecting PAR4 activation (AYPGKF‐NH2 as a standard agonist; YAPGKF‐NH2 as a PAR4‐inactive standard), we were able to establish an inflammatory role for the PAR4‐activating peptides acting via a non‐neurogenic mechanism in a rat paw oedema model.

British Journal of Pharmacology (2004) 143, 443–454. doi:10.1038/sj.bjp.0705946
An appreciation of Tony Birmingham
Authors: Marsden Charles
Published: October 2004

British Journal of Pharmacology (2004) 143, 439–440. doi:10.1038/sj.bjp.0705953
Selective GABA‐receptor actions of amobarbital on thalamic neurons
Authors: Kim H‐S , Wan X , Mathers D A , Puil E
Published: October 2004

We studied amobarbital's effects on membrane properties and currents, and electrically evoked inhibitory postsynaptic currents (IPSCs) mediated by γ‐aminobutyric acid (GABA) in rat thalamic slices. Using concentration–response relationships, we compared amobarbital's effects in nociceptive nuclei and non‐nociceptive nucleus reticularis thalami (nRT).

Amobarbital decreased input resistance by activating GABAA receptors. Amobarbital produced a larger decrease in ventrobasal than nRT neurons.

Amobarbital depressed burst and tonic firing. Depression of burst firing was more effective, particularly in ventrobasal and intralaminar neurons. Depression was reversed by GABAA antagonists, and surmountable by increasing current injection, implicating a receptor‐mediated shunt mechanism.

Amobarbital did not affect the tetrodotoxin‐isolated low threshold Ca2+ spike during GABAA blockade. Amobarbital reduced excitability without altering outward leak, or hyperpolarisation‐activated inward currents.

Amobarbital increased mean conductance and burst duration of single GABAA channels. Consistent with this, amobarbital increased amplitude and decay time of IPSCs with distinct EC50s, implicating actions at two GABAA receptor sites.

Activation of GABAA receptors by low concentrations, fast IPSC amplitude modulation, and failure to affect intrinsic currents distinguished amobarbital's mechanism of action from previously characterised barbiturates. The selective actions of amobarbital on GABAA receptor may have relevance in explaining anaesthetic and analgesic uses.

British Journal of Pharmacology (2004) 143, 485–494. doi:10.1038/sj.bjp.0705974