bluuebunny/crossref_metadata_2025 huggingface dataset:
Crustal deformation and block kinematics in transition from collision to subduction: Global positioning system measurements in northern Taiwan, 1995–2005
Authors: Rau Ruey‐Juin , Ching Kuo‐En , Hu Jyr‐Ching , Lee Jian‐Cheng
Published: September 2008

We present global positioning system (GPS) measurements for the period 1995–2005 at 125 campaign‐surveyed sites in northern Taiwan. Based on elastic, rotating block modeling analyses derived from the GPS data, we describe the transitional tectonics from arc–continent (Luzon–Chinese) collision to the converging Ryukyu trench subduction and back‐arc opening along the Chinese continental margin. Station velocities relative to station S01R, in the Chinese stable continental margin, were estimated from coordinate time series of each station by using the weighted least squares technique. We found two distinct deformation patterns in two geological areas, which are basically separated by the surface projection of the NW‐trending boundary of the subducting Philippine Sea plate across northern Taiwan: (1) a waning collision area to the west and (2) a transition zone to the east. In the waning collision area, the horizontal velocity field shows vectors of 0.3–7.3 mm/yr toward the NW in the foothills and the Hsuehshan Range of northwestern Taiwan. The tectonic blocks represent a significant NW–SE internal contraction along with a small block rotation rate (<3.0°/Myr). The transition zone can be further divided into an outer range and inner range with distinguishing rotation rates and deformation behaviors. In the outer range of the transition zone, velocities of 1.0–7.8 mm/yr from south to north rotating from 008° to 143° is found in the northernmost foothills and the Hsuehshan Range. The tectonic blocks within the outer range are characterized by a coherent rotation (low internal strain rate of <0.10μstrain/yr) with an angular velocity of ∼5.1°/Myr, where the Euler pole is located near its southeastern boundary. In the inner range of transition zone, a larger clockwise rotation from west to east, with horizontal velocities of 9.3–41.2 mm/yr from 053° to 146°, are found in the northernmost Central Range. The tectonic blocks of the inner range reveal a remarkable NW–SE internal extension with an ultrarapid clockwise rotation (∼47.3°/Myr) where the Euler pole is near the southern boundary of the range close to the collision corner with the colliding Luzon arc. The trench roll‐back together with back‐arc opening are interpreted to be substantially superposed on the arc–continent collision‐induced rotation in the transition zone with particular regard to the inner range of the northeast Taiwan mountain belt.
Comparison of observed and model‐computed low frequency circulation and hydrography on the New England Shelf
Authors: Cowles G. W. , Lentz S. J. , Chen C. , Xu Q. , Beardsley R. C.
Published: September 2008

The finite volume coastal ocean model (FVCOM) is configured to study the interannual variability of circulation in the Gulf of Maine (GoM) and Georges Bank. The FVCOM‐GoM system incorporates realistic time‐dependent surface forcing derived from a high‐resolution mesoscale meteorological model (MM5) and assimilation of observed quantities including sea surface temperature and salinity and temperature fields on the open boundary. An evaluation of FVCOM‐GoM model skill on the New England shelf is made by comparison of computed fields and data collected during the Coastal Mixing and Optics (CMO) Program (August 1996–June 1997). Model mean currents for the full CMO period compare well in both magnitude and direction in fall and winter but overpredict the westward flow in spring. The direction and ellipticity of the subtidal variability correspond but computed magnitudes are around 20% below observed, partially due to underprediction of the variability by MM5. Response of subtidal currents to wind‐forcing shows the model captures the directional dependence, as well as seasonal variability of the lag. Hydrographic results show that FVCOM‐GoM resolves the spatial and temporal evolution of the temperature and salinity fields. The model‐computed surface salinity field compares well, except in May when there is no indication of the fresh surface layer from the Connecticut River discharge noted in the observations. Analysis of model‐computed results indicates that the plume was unable to extend to the mooring location due to the presence of a westward mean model‐computed flow during that time that was stronger than observed. Overall FVCOM‐GoM captures well the dynamics of the mean and subtidal flow on the New England shelf.
Characterizing the transport pathways of Asian dust
Authors: Tsai Fujung , Chen George Tai‐Jen , Liu Tsun‐Hsien , Lin Wen‐Dian , Tu Jien‐Yi
Published: September 2008

Backward trajectories, synoptic analyses, and regional dust models are applied to analyze the aerosol particles obtained from aircraft measurements during major dust events in the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) to understand the controlling mechanism of Asian dust transport. The selected high concentrations of aerosol measurements are traced back to their source areas, and the summarized eleven representative trajectories of dust particles are categorized into three types, including the upper‐level (U type), lower‐level (L type), and descending (D type) transport. The characteristics of the dust transport during different stages for each of the three types are inspected. It is found that the transport distance of a dust event strongly depended on the source areas relative to the synoptic conditions. For source areas ahead of a trough, the dust particles can be uplifted into the free troposphere. If the uplifted dust particles move to the ascending areas of a trough or ascend due to other processes in the later stage, then the dust particles likely travel longer distances. When dust particles ascend in an area too close to the trough, their subsidence may be expected as sinking motion could occur after trough passage, and thus the transport distance is limited. Uplifted dust particles are typically found at a height of 400–700 hPa (2–4.5 km above ground level) over source regions. For dust particles that are generated behind a trough, the vertical motion is limited to a layer around 700 hPa, and the transport distance is also shorter.
Satellite‐based model detection of recent climate‐driven changes in northern high‐latitude vegetation productivity
Authors: Zhang Ke , Kimball John S. , Hogg E. H. , Zhao Maosheng , Oechel Walter C. , Cassano John J. , Running Steven W.
Published: September 2008

We applied a satellite remote sensing based production efficiency model (PEM) using an integrated AVHRR and MODIS FPAR/LAI time series with a regionally corrected NCEP/NCAR reanalysis daily surface meteorology and NASA/GEWEX Surface Radiation Budget shortwave solar radiation inputs to assess annual terrestrial net primary productivity (NPP) for the pan‐Arctic basin and Alaska from 1983 to 2005. Our results show that low temperature constraints on Boreal‐Arctic NPP are decreasing by 0.43% per year (P < 0.001), whereas a positive trend in vegetation moisture constraints of 0.49% per year (P = 0.04) are offsetting the potential benefits of longer growing seasons and contributing to recent disturbances in NPP. The PEM simulations of NPP seasonality, annual anomalies and trends are similar to stand inventory network measurements of boreal aspen stem growth (r = 0.56; P = 0.007) and atmospheric CO2 measurement based estimates of the timing of growing season onset (r = 0.78; P < 0.001). Our results indicate that summer drought led to marked NPP decreases in much of the boreal forest region after the late‐1990s. However, seasonal low temperatures are still a dominant limitation on regional NPP. Despite recent drought events, mean annual NPP for the pan‐Arctic region showed a positive growth trend of 0.34% per year (20.27 TgC/a; P = 0.002) from 1983 to 2005. Drought induced NPP decreases may become more frequent and widespread as regional ecosystems adjust to a warmer, drier atmosphere, though the occurrence and severity of drought events will depend on future patterns of plant‐available moisture.
Nutrient regime at the siliceous belt of the Atlantic sector of the Southern Ocean during the past 660 ka
Authors: Schneider‐Mor Aya , Yam Ruth , Bianchi Cristina , Kunz‐Pirrung Martina , Gersonde Rainer , Shemesh Aldo
Published: September 2008

Sediment cores from Ocean Drilling Program sites 1094 and 1093 hold the most extensive and most detailed records of carbon and nitrogen isotopes of diatom‐bound organic matter in the Atlantic sector of the Southern Ocean over the past 660 ka. These records were combined with summer sea surface temperatures and winter sea ice that were deduced from diatom transfer functions to reconstruct the nutrient regime at the northern and southern boundaries of the siliceous belt at latitudes 53°S and 50°S, respectively. The strong coupling between carbon and nitrogen isotope records at site 1093 suggests that the diatom productivity was influenced mainly by changes in nutrient availability. The anticorrelation between the carbon and nitrogen isotopes at site 1094 suggests that the diatom productivity was closely linked to global temperature changes, sea ice coverage, and dissolved CO2 concentration. A detailed comparison of the nitrogen isotope records between the two sites shows three time intervals that represent different nutrient regimes. The nutrients at site 1093, which is close to the Polar Front, were dominated by eddies and meanders that sustained relatively high productivity at times of stratification or reduced ventilation, whereas at site 1094 the nutrients were influenced by ventilation processes.
Stream acidification and base cation losses with grassland afforestation
Authors: Farley Kathleen A. , Piñeiro Gervasio , Palmer Sheila M. , Jobbágy Esteban G. , Jackson Robert B.
Published: September 2008

Afforestation of natural grasslands with fast‐growing pine and eucalyptus species is increasing globally, but little is known about its effect on ecosystems and watersheds and, ultimately, the quality of water resources. To investigate the biogeochemical and hydrological consequences of this land use change, we sampled stream water in paired watersheds in Uruguay and Argentina. In watersheds planted with pine, we found no change in stream pH following afforestation, while in watersheds planted with eucalyptus, pH was 0.7 units lower on average than in streams draining grasslands. To further investigate the mechanism behind the decrease in pH, we sampled soils and streams of eucalypt catchments in Uruguay and analyzed exchangeable base cation concentrations, alkalinity, and dissolved inorganic carbon (DIC). At these sites, Ca, Mg, and Na concentrations were >30% lower in afforested soils than in grassland soils, and pH was significantly lower below 10 cm depth. Stream measurements taken over three years illustrate that these soil changes were also manifested in stream water chemistry. In the eucalypt watersheds, base cation concentrations were >40% lower, and alkalinity and DIC were halved in stream water. A test with data from additional sites where both pines and eucalypts were planted nearby showed that eucalyptus has a stronger acidifying effect than pine. Overall, our data suggest that repeated harvesting cycles at some locations could negatively impact the soil store of base cations and reduce downstream water quality. Our results can be used to help minimize negative impacts of this land use and to inform policy in this and other regions targeted for plantation forestry.
Rates of southeast Greenland ice volume loss from combined ICESat and ASTER observations
Authors: Howat Ian M. , Smith Ben E. , Joughin Ian , Scambos Ted A.
Published: September 2008

Repeat satellite laser altimetry is critical for observing the rapidly changing mass balance of the Greenland Ice Sheet. However, sparse sampling and high surface slopes over rapidly thinning, coastal outlet glaciers may result in underestimation of mass loss. Here we supplement ICESat‐derived surface elevation changes with differenced ASTER digital elevation models of outlet glaciers in southeastern Greenland, the region with the largest concentrated change in outlet glacier mass loss. We estimate a 2002–2005 regional volume‐loss rate of 108 km3/yr. Our results are consistent with drainage‐scale GRACE and mass‐budget estimates when differences in observation periods are taken into account. The two largest glaciers, Kangerdlugssuaq and Helheim, account for only 28% of the mass loss, illustrating the combined importance of smaller glaciers and the need for complete observational coverage. Additionally, we find that rapid, concentrated thinning within the outlets represents a small contribution to the total volume change compared to dispersed inland thinning.
Do organics contribute to small particle formation in the Amazonian upper troposphere?
Authors: Ekman Annica M. L. , Krejci Radovan , Engström Anders , Ström Johan , de Reus Marian , Williams Jonathan , Andreae Meinrat O.
Published: September 2008

3‐D cloud‐resolving model simulations including explicit aerosol physics and chemistry are compared with observations of upper tropospheric (12 km) aerosol size distributions over the Amazon Basin. The model underestimates the aerosol number concentration for all modes, especially the nucleation mode (d < 18 nm). We show that a boundary layer SO2 mixing ratio of approximately 5 ppb would be needed in order to reproduce the high nucleation mode number concentrations observed. This high SO2 mixing ratio is very unlikely for the pristine Amazon Basin at this time of the year. Hence, it is suggested that vapours other than H2SO4 participate in the formation and growth of small aerosols. Using activation nucleation theory together with a small (0.4–10%) secondary organic aerosol mass yield, we show that isoprene has the potential of substantially increasing the number of small particles formed as well as reducing the underestimate for the larger aerosol modes.
Satellite remote sounding of mid‐tropospheric CO2
Authors: Chahine M. T. , Chen Luke , Dimotakis Paul , Jiang Xun , Li Qinbin , Olsen Edward T. , Pagano Thomas , Randerson James , Yung Yuk L.
Published: September 2008

Human activity has increased the concentration of the earth's atmospheric carbon dioxide, which plays a direct role in contributing to global warming. Mid‐tropospheric CO2 retrieved by the Atmospheric Infrared Sounder shows a substantial spatiotemporal variability that is supported by in situ aircraft measurements. The distribution of middle tropospheric CO2 is strongly influenced by surface sources and large‐scale circulations such as the mid‐latitude jet streams and by synoptic weather systems, most notably in the summer hemisphere. In addition, the effects of stratosphere‐troposphere exchange are observed during a final stratospheric warming event. The results provide the means to understand the sources and sinks and the lifting of CO2 from surface layers into the free troposphere and its subsequent transport around the globe. These processes are not adequately represented in three chemistry‐transport models that have been used to study carbon budgets.
Cirrus cloud microphysical properties and air motion statistics using cloud radar Doppler moments: Water content, particle size, and sedimentation relationships
Authors: Deng Min , Mace Gerald G.
Published: September 2008

Improved knowledge of ice cloud properties and the processes that maintain them is needed for modeling applications. A cirrus cloud property retrieval algorithm is applied to a 7‐year Cloud Radar data set collected at the Atmospheric Radiation Measurement Program ground sites. With this dataset, the ice cloud vertical structure is studied in terms of Temperature (T). Then the interrelationships between the ice particle size, ice water content (IWC), and mass‐weighted sedimentation rate are investigated. The mass‐weighted sedimentation rate is usually parameterized as a function T only or IWC only. Here, the mass weighted sedimentation rate is parameterized as a joint function of ice water content and T for both midlatitude and tropical ice clouds. We further examine the validity of several commonly used GCM parameterizations of ice sedimentation rate in comparison to the cirrus cloud results derived from measurements.
Relative contributions to surface shortwave irradiance over China: A new index of potential radiative forcing
Authors: Kawamoto K. , Hayasaka T.
Published: September 2008

The contributions of atmospheric factors to surface shortwave irradiance (S) variability was investigated, using radiative transfer calculations to examine all sky (both cloud‐free and cloudy) conditions. We defined the sensitivities of S to differential increases from given values of cloud, aerosol, and water vapor as potential radiative forcing (PRF). Thus, the expected change in S due to one factor would be the product of the PRF and the change in that factor. Geographical features of the PRF were described over China in January and July, and then the PRF was applied to evaluate the relative contributions of related factors to S variability over Jinan (the central‐eastern China) during 1984 and 1990. Although some shortcomings were pointed out, the usefulness of the PRF was confirmed for determining the relative contributions. In particular, to use accurate aerosol absorption properties was suggested to be crucial for quantitative radiation budget estimates.
Dependence of SuperDARN cross polar cap potential upon the solar wind electric field and magnetopause subsolar distance
Authors: Khachikjan G. Ya. , Koustov A. V. , Sofko G. J.
Published: September 2008

Dependence of the cross polar cap potential (CPCP) upon the interplanetary electric field (IEF), solar wind ram pressure, and magnetopause standoff distance (RMS) are investigated by considering the Super Dual Auroral Radar Network (SuperDARN) HF radar data on the CPCP and information on the solar wind and interplanetary magnetic field from ACE satellite. Data of up to IEF ∼12 mV/m are available. The CPCP scatterplot versus IEF shows a linear increase between 0 and ∼3 mV/m. For larger IEFs, the rate of the CPCP growth decreases, and the dependence eventually saturates. If the same data are arranged in groups of RMS values, linear dependences were found for each group, but the slope of the regression line increases with RMS. The inferred linear fit lines of CPCP versus IEF for various RMS groups intersect each other at IEF ∼3 mV/m. This number is found to be unique because for the IEF above it (below it), the CPCP decreases (increases) with the solar wind ram pressure. This value also corresponds to the condition of the solar wind magnetic field at the subsolar point to be equal to the Earth's dipole magnetic field, as previously reported by Siscoe et al. (2002). Presented analysis suggests that the magnetopause standoff distance (the length of the merging X line) is an important factor in the CPCP saturation.
High‐latitude ionosphere convection and Birkeland current response for the 15 May 2005 magnetic storm recovery phase
Authors: Eriksson S. , Hairston M. R. , Rich F. J. , Korth H. , Zhang Y. , Anderson B. J.
Published: September 2008

The high‐latitude response of sunward E × B flow and Birkeland field‐aligned currents (FAC) is analyzed for the 15 May 2005 magnetic cloud that generated a great magnetic storm (SYM‐H = −305 nT at 0820 UT). The interplanetary magnetic field (IMF) clock angle, θ = arctan(By/Bz), gradually rotated from 65° to −80° during the 10‐h long northward IMF period and the recovery of this storm. DMSP observations confirm a dawnward migration of a Northern Hemisphere sunward E × B flow channel (FC) between a downward and upward FAC pair. This FAC system developed during southward IMF (θ = 109°) at the poleward edge of the duskside auroral oval as part of a four‐sheet FAC system 23 min before the IMF became northward. TIMED/GUVI observations show that the dawnward migration of the upward FAC coincides with a drifting transpolar auroral arc (TPA). IMAGE/WIC did not observe a TPA in the southern (winter) hemisphere. DMSP and Iridium observations are in good agreement with MHD simulation predictions of a northward IMF reorientation of high‐latitude FACs. The northern FC migration was likely due to summer hemisphere conductances, a strong average IMF Bx = −35 nT and the sunward dipole tilt angle that favor a northern high‐latitude reconnection mechanism for a well‐organized sunward FC and FAC system migration. The storm recovery rate appeared to be related with the region 2 FAC. A fast 11.4 nT/h rate was observed for a weak or nonexistent region 2 system during the high‐latitude FAC redistribution. The SYM‐H recovery slowed significantly to 0.9 nT/h following the 1800 UT region 2 system recovery.
Effects of ionospheric heating on feedback‐unstable electromagnetic waves
Authors: Streltsov A. V.
Published: September 2008

This paper presents first results from a numerical study of effects of ionospheric heating on the development of the ionospheric feedback instability in the auroral zone. The instability is driven by the electric field produced in the ionosphere by the closure of large‐scale magnetic‐field‐aligned currents. This field heats ionospheric electrons and ions and changes the recombination rate and the ion mobility inside the ionospheric E‐region. Self‐consistent numerical simulations, based on the reduced two‐fluid Magnetohydrodynamics (MHD) equations including active ionospheric feedback, demonstrate that these two quantities are very important parameters determining dynamics of the ionospheric feedback instability. In particular, simulations show that decrease in the ion mobility caused by heating can very efficiently suppress the instability, although the same effect also causes increase in the perpendicular electric field in the ionosphere. This result suggests that the ionospheric feedback instability should develop when ions in the ionosphere are cold, and it may explain why small‐scale, intense electromagnetic structures and currents normally attributed to the instability are predominantly observed above the auroral ionosphere during the nighttime and during winter seasons. Simulations also demonstrate that heating of the ionospheric electrons can promote development of the instability, although this effect is not as strong as the effect of the ion heating.
Electrodynamics of the formation of ionospheric wave number 4 longitudinal structure
Authors: Jin H. , Miyoshi Y. , Fujiwara H. , Shinagawa H.
Published: September 2008

The global wave number 4 longitudinal structure of ionospheric density has been observed recently by a number of satellite measurements and considered as a signature of dynamical coupling from the deep atmosphere to the ionosphere. By using a numerical model of atmospheric electrodynamics with input fields from a whole atmosphere general circulation model and an ionosphere‐thermosphere model, we investigated the generation mechanism for the longitudinal structure of the F‐region zonal electric field (vertical E × B drift) as a possible driver of the ionospheric density variation, especially with respect to the eastward zonal wave number 3 diurnal tide (DE3) that originates from the convective activities in the troposphere and propagates upward. The simulation showed that the longitudinal profile of zonal perturbation electric field is largely influenced by the zonal DE3 wind around the height of peak Hall conductivity during the daytime, and that it is by the zonal DE3 wind in the F‐region during the nighttime. The daytime zonal electric field is a direct result from charge separation induced by the Hall dynamo current, whereas the nighttime zonal electric field is rather produced to satisfy the electrostatic condition.
Effects of shock parameters on upstream energetic electron burst events
Authors: Yuan Xingqiu , Cairns Iver H. , Trichtchenko Larisa , Rankin Robert
Published: September 2008

Recent simulation results have revealed that energetic electron bursts are produced cyclically at the shock reformation period upstream of reforming shocks and are qualitatively very different from the continuous beam expected from time‐stationary shocks (Yuan et al., 2007a). This paper extends our previous studies by numerically investigating the dependence of electron burst events on shock parameters (the upstream plasma β and Mach number MA). The test particle approximation is made for electrons, and the electron trajectories are traced exactly in the time‐dependent electromagnetic field profiles, generated by one‐dimensional hybrid simulation code. Simulation results indicate that the upstream incoming electrons can be reflected nonuniformly or continuously depending on the shock parameters. Bursty energetic electron events take place when the plasma beta is low (β ≤ 0.4) and the shock Mach number is high (MA ≥ 6). Time‐varying loss cone, beam, and ring beam features are observed in the upstream electron distribution functions. The beam density, speed, average kinetic energy, and speed spread cyclically change with time by factor of ∼2–4. In contrast, continuously reflected electrons are observed for low beta (β ≤ 0.4), low Mach number (MA ≤ 4) shocks, even when the shock is reforming because the changes in shock fields are relative small. The electron burst events disappear and the observed upstream electron distribution function contours are steady state. A continuous electron beam is formed, which is qualitative the same as the beam from steady‐state shocks. Increasing the plasma beta (providing the shock is still reforming) has minor effects on the upstream electron beam features.
AKR breakup and auroral particle acceleration at substorm onset
Authors: Morioka A. , Miyoshi Y. , Tsuchiya F. , Misawa H. , Yumoto K. , Parks G. K. , Anderson R. R. , Menietti J. D. , Donovan E. F. , Honary F. , Spanswick E.
Published: September 2008

The dynamical behavior of auroral kilometric radiation (AKR) is investigated in connection with auroral particle acceleration at substorm onsets using high‐time‐resolution wave spectrograms provided by Polar/PWI electric field observations. AKR develops explosively at altitudes above a preexisting low‐altitude AKR source at substorm onsets. This “AKR breakup” suggests an abrupt formation of a new field‐aligned acceleration region above the preexisting acceleration region. The formation of the new acceleration region is completed in a very short time (amplitude increases 10,000 times in 30 seconds), suggesting that the explosive development is confined to a localized region. AKR breakups are usually preceded (1–3 minutes) by the appearance and/or gradual enhancement of the low‐altitude AKR. This means that the explosive formation of the high‐altitude electric field takes place in the course of the growing low‐altitude acceleration. The development of the low‐altitude acceleration region is thus a necessary condition for the ignition of the high‐altitude bursty acceleration. The dH/dt component from a search‐coil magnetometer at ground shows that a few minutes prior to substorm onsets, the quasi‐DC component begins a negative excursion that is nearly synchronized with the start of the gradual enhancement of the low‐altitude AKR, indicating a precursor‐like behavior for the substorm. This negative variation of dH/dt suggests an exponentially increasing ionospheric current induced by the upward field‐aligned current. At substorm onsets, the decrease in the quasi‐DC variation of dH/dt further accelerates, indicating a sudden reinforcement of the field‐aligned current.
The North American Mercury Model Intercomparison Study (NAMMIS): Study description and model‐to‐model comparisons
Authors: Bullock O. Russell , Atkinson Dwight , Braverman Thomas , Civerolo Kevin , Dastoor Ashu , Davignon Didier , Ku Jia‐Yeong , Lohman Kristen , Myers Thomas C. , Park Rokjin J. , Seigneur Christian , Selin Noelle E. , Sistla Gopal , Vijayaraghavan Krish
Published: September 2008

An atmospheric mercury model intercomparison study has been conducted to compare three regional‐scale atmospheric mercury models, CMAQ, REMSAD, and TEAM, in a tightly constrained testing environment with a focus on North America. Each of these models used the same horizontal modeling grid, pollutant emission information, modeled meteorology, and boundary conditions to the greatest extent practical. Three global‐scale atmospheric mercury models were applied to define three separate initial condition and boundary condition (IC/BC) data sets for elemental mercury, reactive gaseous mercury, and particulate mercury air concentrations for use by the regional‐scale models. The monthly average boundary concentrations of some mercury species simulated by the global models were found to vary by more than a factor of 10, especially at high altitudes. CMAQ, REMSAD, and TEAM were each applied three times, once for each IC/BC data set, to simulate atmospheric mercury transport and deposition during 2001. This paper describes the study design and shows qualitative model‐to‐model comparisons of simulation results on an annual basis. The air concentration patterns for mercury simulated by the regional‐scale models showed significant differences even when the same IC/BC data set was used. Simulated wet deposition of mercury was strongly influenced by the shared precipitation data, but differences of over 50% were still apparent. Simulated dry deposition of mercury was found to vary between the regional‐scale models by nearly a factor of 10 in some locations. Further analysis is underway to perform statistical comparisons of simulated and observed mercury wet deposition using weekly and annual sample integration periods.
Historical reconstruction of monthly oceanic precipitation (1900–2006)
Authors: Smith Thomas M. , Sapiano Mathew R. P. , Arkin Phillip A.
Published: September 2008

An oceanic precipitation reconstruction is developed and evaluated for periods extending back to as early as 1900. Large‐scale monthly oceanic precipitation is reconstructed using the available network of historical gauge data fit to a set of large‐scale covariance spatial modes based on modern analysis. The modern analysis is based on satellite microwave estimates merged with atmospheric reanalysis estimates. For 1900–2006, a monthly and 5° spatial product is developed for reconstructing climate‐scale (large‐scale spatial and inter‐seasonal and longer timescales) variation in pre‐satellite periods. Advantages of this study include the use of a homogeneous satellite analysis for computing reconstruction statistics and improved tuning of the reconstruction methods. Cross‐validation testing is used to show how much historical variance can be reconstructed with the available sampling. In addition, reconstructions are performed using several different gauge data sets to evaluate differences due to the choice of gauge data. Testing shows that that these improved methods produce reconstructions with useful skill in the tropics and Northern Hemisphere midlatitudes. In the Southern Hemisphere midlatitudes and in polar latitudes in both hemispheres, sampling is too sparse to yield much skill. The reconstruction is able to resolve large‐scale modes of variation useful for some diagnostic studies of the 20th century. Reconstruction efforts will continue as improved satellite and atmospheric reanalyses become available.
Effects of the immunomodulator, VGX‐1027, in endotoxin‐induced uveitis in Lewis rats
Authors: Mangano K , Sardesai N Y , Quattrocchi C , Mazzon E , Cuzzocrea S , Bendtzen K , Meroni P L , Kim J J , Nicoletti F
Published: September 2008

Background and purpose:

VGX‐1027 is a novel, low molecular weight, immunomodulatory compound that has shown efficacy against a variety of immuno‐inflammatory disease models in animals including autoimmune diabetes in NOD mice, collagen‐induced arthritis and chemically induced inflammatory colitis. Here, we have studied the effects of VGX‐1027 on the development of endotoxin‐induced uveitis (EIU) in male Lewis rats, as a model of inflammatory ocular diseases in humans.

Experimental approach:

EIU was induced by a single footpad injection of 200 μg lipopolysaccharide (LPS). Groups of rats were treated with either VGX‐1027 (25 mg kg−1) or its vehicle at different time points (30 min, 6 h or 12 h) after the challenge with LPS or, as positive control, with dexamethasone. The rats were killed within 16 h after LPS challenge, and the eyes and aqueous humor were collected to study serological, immunological and histological signs of EIU.

Key results:

The rats treated with VGX‐1027 within 6 h after LPS challenge exhibited milder clinical, histological and laboratory signs of EIU than those treated with vehicle.

Conclusion and implications:

This study provides the first evidence that systemic treatment with VGX‐1027 counteracts the uveitis‐inducing effect of LPS in rats and suggests that this drug may have potential in the treatment of immuno‐inflammatory conditions of the eye in humans.

British Journal of Pharmacology (2008) 155, 722–730; doi:10.1038/bjp.2008.315; published online 8 September 2008
trans‐Resveratrol, an extract of red wine, inhibits human eosinophil activation and degranulation
Authors: Tan Y , Lim L H K
Published: September 2008

Background and purpose:

trans‐Resveratrol, a non‐flavonoid polyphenol found abundantly in red wine possesses antiproliferative and anti‐inflammatory activity in various inflammatory disease conditions. However, the effect of trans‐resveratrol on eosinophil activation in relation to allergy has not been investigated.

Experimental approach:

Human eosinophils were isolated and purified from whole blood and incubated for 16 h with trans‐resveratrol. Eosinophil chemotaxis, activation and degranulation, and apoptosis were investigated. The effect of trans‐resveratrol on the inhibition of p38 and ERK1/2 activation was examined.

Key results:

Treatment of human eosinophils with trans‐resveratrol at concentrations <100 μM for 16 h did not induce eosinophil apoptosis. Similar results were seen after 24 h and 48 h incubations. trans‐Resveratrol (<100 μM) significantly inhibited eosinophil peroxidase release after activation with IL‐5 (IC50=2.9±0.9 μM) or C5a (IC50=3.9±0.5 μM) after 5 min priming with cytochalasin B (CB). Similarly, the production of leukotriene C4 after stimulation with calcium ionophore, and eosinophil chemotaxis in response to eotaxin, as well as CD11b upregulation and CD62 L shedding was also significantly reduced by trans‐resveratrol, at concentrations above 5 μM. All the activators induced p38 and ERK1/2 phosphorylation maximal at 2 min of activation. trans‐Resveratrol potently inhibited p38 and ERK1/2 activation after calcium ionophore and CB and C5a activation.

Conclusions and implications:

trans‐Resveratrol is effective at inhibiting human eosinophil activation and degranulation at concentrations <100 μM, while not inducing apoptosis. This potent anti‐inflammatory activity of trans‐resveratrol and possibly its metabolites on eosinophils may be worth investigating for the treatment of eosinophil‐related allergic diseases.

British Journal of Pharmacology (2008) 155, 995–1004; doi:10.1038/bjp.2008.330; published online 8 September 2008
CGRP function‐blocking antibodies inhibit neurogenic vasodilatation without affecting heart rate or arterial blood pressure in the rat
Authors: Zeller J , Poulsen K T , Sutton J E , Abdiche Y N , Collier S , Chopra R , Garcia C A , Pons J , Rosenthal A , Shelton D L
Published: September 2008

Background and purpose:

Calcitonin gene‐related peptide (CGRP) receptor antagonists effectively abort migraine headache and inhibit neurogenic vasodilatation in humans as well as rat models. Monoclonal antibodies typically have long half‐lives, and we investigated whether or not function‐blocking CGRP antibodies would inhibit neurogenic vasodilatation with a long duration of action and therefore be a possible approach to preventive therapy of migraine. During chronic treatment with anti‐CGRP antibodies, we measured cardiovascular function, which might be a safety concern of CGRP inhibition.

Experimental approach:

We used two rat blood flow models that measure electrically stimulated vasodilatation in the skin or in the middle meningeal artery (MMA). These vasomotor responses are largely dependent on the neurogenic release of CGRP from sensory afferents. To assess cardiovascular function during chronic systemic anti‐CGRP antibody treatment, we measured heart rate and blood pressure in conscious rats.

Key results:

Treatment with anti‐CGRP antibodies inhibited skin vasodilatation or the increase in MMA diameter to a similar magnitude as treatment with CGRP receptor antagonists. Although CGRP antibody treatment had a slower onset of action than the CGRP receptor antagonists, the inhibition was still evident 1 week after dosing. Chronic treatment with anti‐CGRP antibodies had no detectable effects on heart rate or blood pressure.

Conclusions and implications:

We showed for the first time that anti‐CGRP antibodies exert a long lasting inhibition of neurogenic vasodilatation in two different rat models of arterial blood flow. We have provided strong preclinical evidence that anti‐CGRP antibody may be a suitable drug candidate for the preventive treatment of migraine.

British Journal of Pharmacology(2008)155, 1093–1103; doi:fn4; published online 8 September 2008
Post‐injury baicalein improves histological and functional outcomes and reduces inflammatory cytokines after experimental traumatic brain injury
Authors: Chen S‐F , Hsu C‐W , Huang W‐H , Wang J‐Y
Published: September 2008

Background and purpose:

Traumatic brain injury (TBI) triggers a complex series of inflammatory responses that contribute to secondary tissue damage. The aim of this study was to investigate the effect of baicalein, a flavonoid possessing potent anti‐inflammatory properties, on functional and histological outcomes and inflammatory cytokine expression, following TBI in rats.

Experimental approach:

Rats subjected to controlled cortical impact injury were injected with baicalein (30 mg kg−1) or vehicle immediately after injury or daily for 4 days. Neurological status was evaluated using the rotarod, adhesive removal, modified neurological severity scores and beam walk tests. Contusion volume and neuronal degeneration were measured using cresyl violet and FluoroJade B (FJB) histochemistry. Levels of tumour necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β) and interleukin‐6 (IL‐6) mRNA and protein were assessed by real‐time quantitative reverse transcriptase‐PCR, enzyme‐linked immunosorbent assay and immunohistochemistry.

Key results:

Single‐dose and multiple‐dose treatment with baicalein significantly improved functional recovery and reduced contusion volumes up to day 28 post‐injury, although multiple‐dose baicalein was the more effective treatment. Single‐dose baicalein also significantly reduced the number of degenerating neurons (31%) on post‐injury day 1 as indicated by FJB staining. These changes were associated with significantly decreased levels, at the contusion site, of TNF‐α, IL‐1β and IL‐6 mRNA at 6 h, and cytokine protein on day 1 post‐injury.

Conclusions and implications:

Post‐injury treatment with baicalein improved functional and histological outcomes and reduced induction of proinflammatory cytokines in rat TBI. The neuroprotective effect of baicalein may be related to a decreased inflammatory response following the injury.

British Journal of Pharmacology (2008) 155, 1279–1296; doi:10.1038/bjp.2008.345; published online 8 September 2008
CGRP blockers in migraine therapy: where do they act?
Authors: Edvinsson L
Published: September 2008

Calcitonin gene‐related peptide (CGRP) is expressed throughout the CNS and peripheral nervous system, consistent with control of vasodilatation, nociception, motor function, secretion and olfaction. αCGRP is prominently localized in primary afferent C and Aδ fibres of spinal and trigeminal ganglia. Activation of the trigeminal nerve results in antidromic release of CGRP, acting through a CGRP1 receptor. Antagonists of CGRP1 receptors reduce signalling in the trigeminovascular pathway at multiple sites, putatively inside the blood–brain barrier. Other ways of interacting with CGRP mechanisms have appeared limiting the availability of CGRP in the circulation with a specific CGRP antibody or with a CGRP‐binding RNA‐Spiegelmer. Either way reduces neurogenic inflammation and attenuates signalling within the trigeminovascular pathway. Specific CGRP receptor blockade has been shown to reduce the effect of released CGRP and to abort acute migraine attacks. The novel approach of reducing available CGRP is limited by the blood–brain barrier; its usefulness may be more as prophylaxis rather than as acute treatment of migraine.

British Journal of Pharmacology (2008) 155, 967–969; doi:fn1; published online 8 September 2008
Detection of Stomach Cancer by TV-Endoscope Colour Enhancement Image Processing
Authors: Miyamoto Masaki
Published: September 2008

Using modern TV-endoscope equipment, we have experimented image processing in several ways. This time, we designed new image processing unit called “Color Subtracted Enhancement image processing unit”. This unit　was made by combining the RGB-Subtraction　image processing device with the color enhancement image processing device. The　RGB-subtraction device is an analogue unit that　enables us to remove the visible red, green and blue peaks from the image. We can subtract the images R-G, R-B, G-R, B-R, B-G simply by changing the switches. The color enhancement device (developed by Olympus optical corporation inc.) is a digital processing unit that lets us reinforce any of these colors. This unit let us enhance any of RGB colors on the image which is processed by RGB-subtraction device. Using this unit, we tried to clarify the border between normal and diseased mucosa. We detected invasion of the lesion and compared　the original image with the processed images. Moreover, we marked the border visualized by this unit and compared the marking point with histological border .

Result:

Based on the R-G image (i.e. that was produced by subtracting green from red) and the R-B image, the processed images are more clearly than those based on the B-G image. The G-B image, the B-R image and the G-R image. The color subtracted enhancement image ocessing enabled us to detect the border between normal and diseased mucosa and showed us the concavity and convexity of early cancer and gastric ulcers.

Conclusions:

Elevations, depressions and color changes of gastric mucosa were clearly visible by using the TV-endoscope color subtracted enhancement image processing unit. This technique will facilitate the treatment of gastric lesions with endoscopic surgery.
Variational and robust density fitting of four-center two-electron integrals in local metrics
Authors: Reine Simen , Tellgren Erik , Krapp Andreas , Kjærgaard Thomas , Helgaker Trygve , Jansik Branislav , Høst Stinne , Salek Paweł
Published: September 2008

Density fitting is an important method for speeding up quantum-chemical calculations. Linear-scaling developments in Hartree–Fock and density-functional theories have highlighted the need for linear-scaling density-fitting schemes. In this paper, we present a robust variational density-fitting scheme that allows for solving the fitting equations in local metrics instead of the traditional Coulomb metric, as required for linear scaling. Results of fitting four-center two-electron integrals in the overlap and the attenuated Gaussian damped Coulomb metric are presented, and we conclude that density fitting can be performed in local metrics at little loss of chemical accuracy. We further propose to use this theory in linear-scaling density-fitting developments.
Arrays of SiO2 substrate-free micromechanical uncooled infrared and terahertz detectors
Authors: Grbovic D. , Lavrik N. V. , Rajic S. , Datskos P. G.
Published: September 2008

We describe the design, fabrication, and characterization of arrays of uncooled infrared and terahertz micromechanical detectors that utilize SiO2 as a main structural material. Materials with highly dissimilar coefficients of thermal expansion, namely, Al and SiO2, were used to form folded bimaterial regions. This approach improved the detector sensitivity by 12 times compared to SiNx-based detectors of similar shape and size. Two types of structural SiO2 layers were investigated: thermally grown and plasma-enhanced chemical-vapor-deposited SiO2. Fabrication of the detector arrays relied on a straightforward process flow that involved three photolithography steps and no wet etching. The noise equivalent temperature difference intrinsic to the detectors fabricated during this work can reach 3.8 mK when excluding any contribution from the optical readout used to interrogate the arrays.
Amide-I relaxation-induced hydrogen bond distortion: An intermediate in electron capture dissociation mass spectrometry of α-helical peptides?
Authors: Pouthier Vincent , Tsybin Yury O.
Published: September 2008

Electron capture dissociation (ECD) of peptides and proteins in the gas phase is a powerful tool in tandem mass spectrometry whose current description is not sufficient to explain many experimental observations. Here, we attempt to bridge the current understanding of the vibrational dynamics in α-helices with the recent experimental results on ECD of α-helical peptides through consideration of amide-I relaxation-induced hydrogen bond distortion. Based on a single spine of H-bonded peptide units, we assume that charge neutralization upon electron capture by a charged α-helix excites a nearby amide-I mode, which relaxes over a few picoseconds due to Fermi resonances with intramolecular normal modes. The amide-I population plays the role of an external force, which drives the displacements of each peptide unit. It induces a large immobile contraction of the H bonds surrounding the excited site whose lifetime is about the amide-I lifetime. In addition, it creates two lattice deformations describing H bond stretchings, which propagate from the excited region toward both termini of the α-helix, get reflected at the termini and yield H bond contractions which move back to the excited region. Consequently, we show that H bonds experience rather large contractions whose amplitude depends on general features such as the position of the amide-I mode, the peptide length and the H bond force constants. When an H bond contraction is sufficiently large, it may promote a hydrogen atom transfer between two neighboring peptide units leading to the formation of a radical at charge site remote carbonyl carbon which is known to be a precursor to the rupture of the corresponding NCα bond. The introduced here way of excitation energy generation and transfer may significantly advance ECD understanding and complement existing ECD mechanisms.