bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a three‐dimensional chemical transport model (PMCAMx) in the eastern United States for all four seasons
Authors: Karydis Vlassis A. , Tsimpidi Alexandra P. , Pandis Spyros N.
Published: August 2007

A three‐dimensional chemical transport model (PMCAMx) is used to simulate particulate matter (PM) mass and composition in the eastern United States during the four seasons of the year (July 2001, October 2001, January 2002, and April 2002). The model predictions are evaluated against daily average PM2.5 measurements taken throughout the eastern United States by the IMPROVE and STN monitoring networks and the EPA Supersites program. During the spring and summer the model reproduces the measured daily average PM2.5 concentrations with an error of less than 50%, two thirds of the time. The PM2.5 error is less than 30% for 43% of the measurements during these seasons. For the fall and winter the PM2.5 predictions are within 50% of the measurements for 51% of the data points and within 30% for 34% of the time. The performance of the model in reproducing sulfate, organic mass, elemental carbon, and total PM2.5 concentrations varies from average to good depending on the season. Uncertainties in ammonia emissions during the fall cause errors in the corresponding ammonium predictions, while the ammonia emissions inventory appears to be satisfactory during the other seasons. The ability of the model to reproduce the aerosol nitrate concentrations in the spring and summer is limited by difficulties in simulating the heterogeneous nighttime formation rate of nitric acid. During the summer and fall the model performance in reproducing the organic PM concentrations and diurnal patterns is good. The predicted organic PM during the summer is on average 60% primary and 40% secondary. The secondary contribution to organic PM drops to around 20% during the winter. The used average EC emission rate of approximately 0.55 ktons d−1 (0.45 ktons d−1 during the weekends) is consistent with the observed EC concentrations. The nighttime chemistry of NOx determines the PM nitrate concentrations during most days in the winter, spring, and fall and its mathematical description needs improvement. The good agreement between the predicted and observed temporal profiles for most species suggests a reasonable understanding and depiction in the model of the corresponding processes. Additional strengths and limitations of current modeling approaches for this modeling domain and for the different seasons are further discussed.
Intercomparison of dimethylsulfide oxidation mechanisms for the marine boundary layer: Gaseous and particulate sulfur constituents
Authors: Karl M. , Gross A. , Leck C. , Pirjola L.
Published: August 2007

An intercomparison of seven dimethylsulfide oxidation chemical mechanisms for the marine boundary layer (MBL) is conducted using a coupled gas phase/aerosol box model. The mechanisms are from Koga and Tanaka (1993), Hertel et al. (1994), Saltelli and Hjorth (1995), Chin et al. (1996), Capaldo and Pandis (1997), Lucas and Prinn (2002), and the mechanism developed during the Evaluation of the Climatic Impact of Dimethyl Sulfide project (EL CID, 2003). They range from schemes with very detailed description of the dimethylsulfide oxidation with up to 65 reactions to a very simple scheme with only six reactions suitable for global modeling. Coupling each oxidation mechanism to a monodisperse aerosol dynamics model allows for the simultaneous comparison of predicted gas phase and particulate concentrations of sulfur‐containing constituents, together with the predicted contribution of dimethylsulfide (DMS) to aerosol formation and growth. Significant differences for sulfur‐containing compounds between the compared schemes are observed. The temperature dependence and magnitude of the ratio between methane sulfonate and non‐sea‐salt sulfate is investigated for each scheme and compared to observations. Liquid phase oxidation processes are missing in the model and the capability of individual schemes to correctly predict observed ratios can only be assessed in part. No new particle formation was found when applying binary nucleation in the three marine boundary layer scenarios. Therefore the results suggest that several uncertainties limiting our understanding of atmospheric oxidation of dimethylsulfide with implications for climate still exist.
Temporal evolution of ClONO2 observed with Improved Limb Atmospheric Spectrometer (ILAS) during Arctic late winter and early spring in 1997
Authors: Hayashida S. , Sugita T. , Ikeda N. , Toda Y. , Irie H.
Published: August 2007

The temporal evolution of the volume mixing ratio (VMR) of chlorine nitrate (ClONO2) observed with the Improved Limb Atmospheric Spectrometer (ILAS) is described for the Arctic late winter and early spring of 1997. The temporal development of ClONO2 on the 475‐K isentropic surface during winter and spring is characterized by high variability in the VMR with seasonal enhancement to about 2 ppbv. In February, depleted values of ClONO2 were also observed; some of these low values are attributable to denitrification or to occurrence of polar stratospheric clouds. After mid‐March, when ClONO2 reached peak values, ClONO2 decreased and showed much less variability. Comparison of ClONO2 with HCl observed by the Halogen Occultation Experiment/Upper Atmospheric Research Satellite (HALOE/UARS) suggests a conversion of ClONO2 into HCl earlier at high altitudes than at lower altitudes. During the period a marked enhancement in NO2 was observed with a reduction in ClONO2 in the vortex, providing the first evidence from space of the NO2 time evolution in conjunction with ClONO2. Continuous measurements of ClONO2 through winter and spring over the Arctic are limited to date. The ILAS measurements reported in this paper will be useful for reanalyzing the seasonal variation of chlorine activation/deactivation processes in the Arctic lower stratosphere that control the degree of ozone destruction.
Beijing aerosol: Atmospheric interactions and new trends
Authors: Guinot Benjamin , Cachier Hélène , Sciare Jean , Tong Yu , Xin Wang , Jianhua Yu
Published: August 2007

Beijing aerosols are scrutinized as a case study for atmospheric interactions in a complex multisource situation. For the first time, fine (<2 μm) and coarse (>2 μm) aerosols were continuously collected during a time period (20 months) long enough to capture seasonal trends of sources and interactions. Weekly samples were obtained from January 2003 to August 2004 downtown and during 9 months at two periurban sites. Aerosol samples were chemically characterized (black carbon (BC), organic carbon (OC), and major ions) and dust was obtained from mass closure. Concentration data were smoothed and boundary layer height (BLH) corrected in order to better identify sources and processes. All yearlong, the coarse aerosol is dominated by dust (75%) whereas the fine mode is dominated (46%) by carbonaceous particles. Photochemistry is an intense driving force for secondary aerosol formation including secondary organic aerosol (SOA). Dust particles present a reactive surface for secondary aerosol formation from the intense anthropogenic pool of acidic gaseous precursors (SO2, HNO3, and volatile organic compounds (VOCs)). These interactions favor the formation of a very significant coarse fraction for SO4, NO3, and POM, a feature almost never encountered in developed countries. Surprisingly too is the presence of fine NH4NO3 in summer. A new result is also that the winter “heating season” appears at present of minor importance with, however, a significant component from domestic heating as traced by BC/OC. In the future, traffic is likely to dominate downtown anthropogenic emissions. Year‐to‐year variability in meteorological conditions is likely to influence inputs from arid regions and from regional industrial and biomass burning sources.
Analysis of tropical radiative heating profiles: A comparison of models and observations
Authors: McFarlane Sally A. , Mather James H. , Ackerman Thomas P.
Published: August 2007

The vertical distribution of radiative heating in the atmosphere is an important driver of atmospheric circulation. Evaluation of model simulations of the Earth's radiation budget typically focus only on performance at the top of the atmosphere or at the surface. In this study, we compare the vertical distribution of cloud properties and radiative heating rates calculated from observations at the Department of Energy's Atmospheric Radiation Measurement (ARM) sites on the islands of Nauru and Manus to simulations performed using the Multiscale Modeling Framework (MMF) and the Community Atmosphere Model (CAM). Significant differences are found in the vertical profiles and diurnal cycle of cloud amount, condensed water content, and cloud effect on heating rates between the two models and between the models and the observations. The differences in the heating rates between the models and ARM results depend partly on the details of the parameterization of effective radius and absorption coefficients used and partly on differences in cloud frequency, vertical location of clouds, and optical thickness. Since the same radiative model is used in the CAM and MMF, differences in the effect of clouds on heating rates between the two models are due to the differing treatment of cloud processes in the models and the interaction of clouds and radiation on the local scale in the MMF.
Sunspots, El Niño, and the levels of Lake Victoria, East Africa
Authors: Stager J. Curt , Ruzmaikin Alexander , Conway Declan , Verburg Piet , Mason Peter J.
Published: August 2007

An association of high sunspot numbers with rises in the level of Lake Victoria, East Africa, has been the focus of many investigations and vigorous debate during the last century. In this paper, we show that peaks in the ∼11‐year sunspot cycle were accompanied by Victoria level maxima throughout the 20th century, due to the occurrence of positive rainfall anomalies ∼1 year before solar maxima. Similar patterns also occurred in at least five other East African lakes, which indicates that these sunspot‐rainfall relationships were broadly regional in scale. Although irradiance fluctuations associated with the sunspot cycle are weak, their effects on tropical rainfall could be amplified through interactions with sea surface temperatures and atmospheric circulation systems, including ENSO. If this Sun‐rainfall relationship persists in the future, then sunspot cycles can be used for long‐term prediction of precipitation anomalies and associated outbreaks of insect‐borne disease in much of East Africa. In that case, unusually wet rainy seasons and Rift Valley Fever epidemics should occur a year or so before the next solar maximum, which is expected to occur in 2011–2012 AD.
On using computational aeroacoustics for long‐range propagation of infrasounds in realistic atmospheres
Authors: Millet C. , Robinet J.‐C. , Roblin C.
Published: August 2007

In this study, a perturbative formulation of non linear euler equations is used to compute the infrasound propagation in real atmospheres. Based on a Dispersion‐Relation‐Preserving numerical scheme, the discretization provides very good properties for both sound generation and long range infrasound propagation over a variety of spatial atmospheric scales. The background flow is obtained by matching the comprehensive empirical global model of horizontal winds HWM‐93 with radio and rocket soundings of the lower atmosphere. Comparison of calculations and experimental data from the explosive “Misty Picture” test (on May 14, 1987) shows that asymptotic techniques based on high frequency approximations cannot explain some important features of the measurements. The small scales of high resolution meteorological data provide changes in the detection predictions and the emergence of large‐scale coherent structures of atmospheric turbulence.
On the MLT distribution of F region polar cap patches at night
Authors: Moen J. , Gulbrandsen N. , Lorentzen D. A. , Carlson H. C.
Published: August 2007

Eight years of meridian scanning photometer data from Ny‐Ålesund, Svalbard have been analyzed to study the occurrence of F region polar cap patches at night. In total 333 patches in 43 days were observed to hit the poleward boundary of nighttime auroras which is a unique signature of ongoing tail reconnection. The MLT distribution of patches is smooth and exhibit a bell shaped function symmetric around 23:25 MLT. The symmetry of the patch distribution about midnight indicates that patches populate the morning cell and the dusk cell of polar cap convection at the same probability. About 60% of the patches exit the polar cap from 22–01 MLT, but the entire distribution span from 18:30–04:50 MLT, i.e., nearly the full MLT span where tail reconnection may occur. The patch occurrence statistics presented here is an important new result of relevance to phenomena related to the presence and transport of patches.
Assimilation of global MODIS leaf area index retrievals within a terrestrial biosphere model
Authors: Demarty J. , Chevallier F. , Friend A. D. , Viovy N. , Piao Shilong , Ciais P.
Published: August 2007

We investigate the capability of global leaf area index (LAI) retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) to be assimilated within a process‐oriented biosphere model in order to constrain the distribution of carbon fluxes. This is achieved by implementing a sequential data assimilation procedure within a Dynamic Global Vegetation Model. Assimilating two years (2000–2001) of satellite LAI retrievals advances the onset and the end of the growing season at high northern latitudes, by 20 and 40 days respectively. This reduces the growing season length and leads to lower estimates of global annual gross primary productivity (GPP) and net primary productivity (NPP), respectively by 5 and 3% with large variations from one vegetation biome to another. In situ measurements of monthly GPP from eddy flux towers provide an independent check on the performance of the assimilation procedure, resulting in an improvement of 25% in terms of root mean square error between modelled and observed GPP over the model grid points where the flux towers are located.
Modeling large‐scale inundation of Amazonian seasonally flooded wetlands
Authors: Wilson Matthew , Bates Paul , Alsdorf Doug , Forsberg Bruce , Horritt Matthew , Melack John , Frappart Frédéric , Famiglietti James
Published: August 2007

This paper presents the first application and validation of a 2D hydrodynamic model of the Amazon at a large spatial scale. The simulation results suggest that a significantly higher proportion of total flow is routed through the floodplain than previously thought. We use the hydrodynamic model LISFLOOD‐FP with topographic data from the Shuttle Radar Topography Mission to predict floodplain inundation for a 240 × 125 km section of the central Amazon floodplain in Brazil and compare our results to satellite‐derived estimates of inundation extent, existing gauged data and satellite altimetry. We find that model accuracy is good at high water (72% spatial fit; 0.99 m root mean square error in water stage heights), while accuracy drops at low water (23%; 3.17 m) due to incomplete drainage of the floodplain resulting from errors in topographic data and omission of floodplain hydrologic processes from this initial model.
Absence of geomagnetic conjugacy in pulsating auroras
Authors: Watanabe Masakazu , Kadokura Akira , Sato Natsuo , Saemundsson Thorsteinn
Published: August 2007

We have examined the geomagnetic conjugacy of pulsating auroras using TV camera data obtained simultaneously at Syowa in Antarctica and at Tjornes in Iceland. In order to exclude the magnetic field mapping problem, we investigated a period during which conjugate points were unambiguously identified from large‐scale discrete conjugate auroras. The conjugacy of pulsating auroras revealed in this study may be summarized as follows. Some pulsating auroras appear in both hemispheres, while others appear only in one hemisphere. Even in the former case, the shape of the auroral form is generally different between the two hemispheres, and there is little or no interhemispheric correlation in the intensity variations. We could not find a pulsating aurora that appeared synchronously at the two endpoints of a flux tube. From these observational results and the increasing amount of evidence in recent studies, we conclude that the conjugacy of pulsating auroras is generally poor.
Passage of intraseasonal waves in the subsurface oceans
Authors: Krishnamurti T. N. , Chakraborty Arindam , Krishnamurti Ruby , Dewar William K. , Clayson Carol Anne
Published: August 2007

This study exploits the coverage of ARGO (Array for Real‐time Geostrophic Oceanography) float data sets towards identifying passage of intraseasonal waves over the subsurface global oceans. ARGO, a new observing system, has provided an unprecedented data coverage and impact. The assimilation of ARGO data reveals that the subsurface ocean temperature carry signatures on the passage of the intraseasonal waves. This vast oceanic data sets provided an opportunity to explore the usefulness of coupled assimilation for seasonal forecasts on the passage of these waves. The results suggest that the inclusion of subsurface ARGO profiler data sets can be useful for prediction of the intraseasonal waves in the atmosphere/oceans. These improved forecasts hold the promise for improved seasonal outlook projections for the dry and wet spells of the monsoon. We also demonstrate improved phase relationship on the passage of zonal wind anomalies of the intraseasonal waves and the monsoon rainfall.
Probing the boundary between antiparallel and component reconnection during southward interplanetary magnetic field conditions
Authors: Trattner K. J. , Mulcock J. S. , Petrinec S. M. , Fuselier S. A.
Published: August 2007

One of the major outstanding questions about magnetic reconnection is where reconnection will occur at the Earth's magnetopause for specific conditions of the solar wind and the interplanetary magnetic field (IMF). There are two scenarios discussed in the literature: (1) antiparallel reconnection, which occurs where the magnetospheric magnetic field and the IMF are antiparallel (shear angle of approximately 180°) and (2) component reconnection, where shear angles between the magnetospheric field and the IMF as low as 50° have been reported. The distinction between the two reconnection scenarios is important for the energy and momentum transfer from the solar wind to the magnetosphere. Here we report on a method using three‐dimensional plasma observations from the Toroidal Imaging Mass‐Angle Spectrograph instrument on the Polar spacecraft as it passes through the northern magnetospheric cusp to calculate the distance to the reconnection line and subsequently trace the distance along model magnetic field lines back to the magnetopause. Results from 130 events reveal that in general, magnetic reconnection occurs along an extended line across the dayside magnetopause (i.e., consistent with the component reconnection scenario). During strong sunward or antisunward IMF conditions (BX), however, the reconnection location resembles the antiparallel reconnection model at high latitudes and does not cross the dayside magnetopause as a single tilted reconnection line. These results show that either reconnection scenario can occur at the magnetopause, depending on the specific IMF conditions.
Effect of oblique electromagnetic ion cyclotron waves on relativistic electron scattering: Combined Release and Radiation Effects Satellite (CRRES)‐based calculation
Authors: Gamayunov K. V. , Khazanov G. V.
Published: August 2007

We consider the effect of oblique electromagnetic ion cyclotron (EMIC) waves on relativistic electron scattering in the outer radiation belt (RB) using simultaneous observations of plasma and wave parameters from Combined Release and Radiation Effects Satellite (CRRES). The main findings can be summarized as follows. First, in comparison with field‐aligned waves, intermediate and highly oblique distributions decrease the range of pitch angles subject to diffusion and reduce the local scattering rate by about an order of magnitude at pitch angles where the principle n = 1 resonances operate. Oblique waves allow the n > 1 resonances to operate, extending the range of local pitch angle diffusion down to the loss cone, and increasing the diffusion at lower pitch angles by orders of magnitude. Second, the local diffusion coefficients derived from CRRES data are qualitatively similar to the local results obtained for prescribed plasma/wave parameters. Consequently, it is likely that the bounce‐averaged diffusion coefficients, if estimated from concurrent data, will exhibit the dependencies similar to those we found for model calculations. Third, in comparison with field‐aligned waves, intermediate and highly oblique waves decrease the bounce‐averaged scattering rate near the edge of the equatorial loss cone by orders of magnitude if the electron energy does not exceed a threshold (∼2–5 MeV) depending on specified plasma and/or wave parameters. Lastly, for greater electron energies, oblique waves operating the n > 1 resonances are more effective and provide the same bounce‐averaged diffusion rate near the loss cone as field‐aligned waves do.
Role of excited N2 in the production of nitric oxide
Authors: Campbell L. , Cartwright D. C. , Brunger M. J.
Published: August 2007

Excited N2 plays a role in a number of atmospheric processes, including auroral and dayglow emissions, chemical reactions, recombination of free electrons, and the production of nitric oxide. Electron impact excitation of N2 is followed by radiative decay through a series of excited states, contributing to auroral and dayglow emissions. These processes are intertwined with various chemical reactions and collisional quenching involving the excited and ground state vibrational levels. Statistical equilibrium and time step atmospheric models are used to predict N2 excited state densities and emissions (as a test against previous models and measurements) and to investigate the role of excited nitrogen in the production of nitric oxide. These calculations predict that inclusion of the reaction N2[A3Σu+] + O, to generate NO, produces an increase by a factor of up to three in the calculated NO density at some altitudes.
P and S waveform modeling of continental sub‐lithospheric detachment at the eastern edge of the Rio Grande Rift
Authors: Song Teh‐Ru Alex , Helmberger Don V.
Published: August 2007

East of the Rio Grande Rift, tomographic images of teleseismic data have revealed a SE dipping, slab‐like structure underneath the western edge of the Great Plains in the southwestern United States. However, finite difference synthetics require an amplified tomographic model to reproduce the waveform distortions as observed in broadband waveform data recorded along the LA RISTRA Transect. In addition to travel time anomalies, Song and Helmberger (2007) demonstrated how to use S waveforms and their amplitude patterns to further constrain the magnitude of the anomalous structure. Their preferred S velocity model suggests that the slab‐like structure is about 4% fast, 120 km thick and dipping 70–75° to the SE to about a depth of 600 km. We adapt the preferred S wave model from Song and Helmberger (2007) and scale the P wave model using a suite of scaling factors (SF ≡ dlnVs/dlnVp). We find that synthetics from the P model generated by SF ≈ 1.25 can distort P waveforms and fit the amplitude pattern best. Such a low SF indicates that the slab‐like anomaly is not only cold but also compositionally distinct. We make use of SF and the S wave anomaly simultaneously to obtain corresponding Vp/Vs anomaly and infer the origin of the slab‐like anomaly. Our result suggests that the observed sub‐lithospheric detachment is 310 ± 20°C colder and more depleted than the adjoining mantle asthenosphere by 3 units of Mg# (Mg / (Mg + Fe) × 100). It is negatively buoyant and is geodynamically consistent with the observed foundering of the continental lithosphere at the eastern edge of the Rio Grande Rift. In short, we demonstrate the importance of seismic waveform anomalies in geochemical and geodynamic inferences.
Speciation of ambient fine organic carbon particles and source apportionment of PM2.5 in Indian cities
Authors: Chowdhury Zohir , Zheng Mei , Schauer James J. , Sheesley Rebecca J. , Salmon Lynn G. , Cass Glen R. , Russell Armistead G.
Published: August 2007

Fine particle organic carbon in Delhi, Mumbai, Kolkata, and Chandigarh is speciated to quantify sources contributing to fine particle pollution. Gas chromatography/mass spectrometry of 29 particle‐phase organic compounds, including n‐alkanes, polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, and levoglucosan along with quantification of silicon, aluminum, and elemental carbon are used in a molecular‐marker based source apportionment model to quantify the primary source contributions to the PM2.5 mass concentrations for four seasons in three sites and for the summer in Chandigarh. Five primary sources are identified and quantified: diesel engine exhaust, gasoline engine exhaust, road dust, coal combustion, and biomass combustion. Important trends in the seasonal and spatial patterns of the impact of these five sources are observed. On average, primary emissions from fossil fuel combustion (coal, diesel, and gasoline) are responsible for about 25–33% of PM2.5 mass in Delhi, 21–36% in Mumbai, 37–57% in Kolkata, and 28% in Chandigarh. These figures can be compared to the biomass combustion contributions to ambient PM2.5 of 7–20% for Delhi, 7–20% for Mumbai, 13–18% for Kolkata, and 8% for Chandigarh. These measurements provide important information about the seasonal and spatial distribution of fine particle phase organic compounds in Indian cities as well as quantifying source contributions leading to the fine particle air pollution in those cities.
ORGANOTIN IMPLICATIONS IN ANTICARCINOGENESIS. BACKGROUND AND THYMUS INVOLVEMENT
Authors: Cardarelli Nathan F , Quitter Bernadette M , Allen Anthony , Dobbins Emmy , Libby Eugene P , Hager Patrick , Sherman Larry R
Published: August 2007

A comprehensive study of the scientific literature regarding tin content in normal and pathogenic human tissue has disclosed that various organotin materials retard both the onset and growth of cancer in laboratory animals, and decreased tissue tin in humans may be associated with tumour development.

Initial studies by the authors have shown that the thymus gland of the mouse possesses a relatively high concentration of tin and is also the major site of accumulation for 14C‐labelled tri‐n‐butyltin fluoride (TBTF). When mammary cancer‐prone mice with transplanted tumours were orally dosed continuously with this agent in their drinking water, the tumour growth rate was significantly reduced. Both mouse mammary tumours and human lung tumours show low tin content compared to normal body tissue.
THE POTENTIAL BRONCHODILATOR ACTION OF VERAPAMIL
Authors: Cade JF , Clegg EA , Moulds RFW , Santamaria JD , Rubinfeld AR , Pain MCF
Published: August 2007

Although calcium antagonists such verapamil are used primarily in cardiovascular disease, they appear to relax smooth muscle generally. Therefore, the possibility that verapamil might have bronchodilator properties was explored using the guinea‐pig tracheal ring technique. Verapamil was found to produce considerable tracheal smooth muscle relaxation from a threshold concentration of 2 × 10−7M and with maximum effect at 10−3M. The responses to the contractile agonists histamine and prostaglandin F2α and especially methacholine and serotonin were substantially reduced by prior administration of verapamil. Verapamil 2 × 10−4M was equally effective as isoprenaline 10−8M in producing 50% maximum direct relaxation but was more effective than isoprenaline as an antagonist of the contractile agonists, methacholine, histamine and serotonin, but not prostaglandin F2α. Verapamil abolished the contractile responses to barium chloride. It is concluded that, although verapamil was not very potent as a direct bronchodilator, it could potentially be of prophylactic benefit in asthma because of its efficacy as an antagonist of common contractile agonists.
MIGRATION OF POLYMORPHONUCLEAR NEUTROPHILS AND MACROPHAGES FROM BONE MARROW TO THE PERITONEAL CAVITY AFTER (3H)‐THYMIDINE LABELLING OF RAT TIBIAL BONE MARROW IN VIVO
Authors: Smeaton TC
Published: August 2007

The kinetics of migration of bone marrow cells to the peritoneal cavity have been studied using in vivo labelling of the marrow of the rat tibia with (methyl‐3H)‐thymidine (*TdR). The incorporation of 3H into DNA is directly related to the amount infused over a thirty‐minute period, though only 2–3% of the infused dose is incorporated into DNA in the bone. Autoradiography has shown widespread labelling of bone marrow cells throughout the tibia. Band cells and polymorphonuclear neutrophils (PMN) show an increase in labelling during the 2–3 days after infusion, confirming the maturation of granulocytes prior to their release to the circulation. The disappearance of 3H‐labelled DNA from the bone occurs rapidly during the 3 days after infusion of *TdR with a half‐life (t½) of 1·4‐1·7 days. There is a concomitant increase in the specific activity of DNA in peritoneal cells elicited by agar, particularly in the macrophage (Mφ), Labelling of PMN in the peritoneal exudate occurs only when agar is injected from 2–4 days after infusion of *TdR. The time for maturation of PMN in the rat bone marrow (BM) (2–3 days) has been confirmed, and the method of labelling permits both measurement of the migration of cells from BM to peritoneal cavity and an estimate of the rates of migration.
ULTRAVIOLET CARCINOGENESIS IN THE HAIRLESS MOUSE SKIN INFLUENCE OF THE SUNSCREEN 2‐ETHYLHEXYL‐P‐METHOXYCINNAMATE
Authors: Gallagher CH , Greenoak GE , Reeve Vivienne E , Canfield PJ , Baker RSU , Bonin AM
Published: August 2007

The mutagenicity of some samples of a commonly used sunscreen, 2‐ethylhexyl‐p‐methoxycinnamate (2‐EHMC), led to these studies of its potential carcinogenicity in the HRA/Skh hairless mouse.

In a daily treatment regime, repeated for 9 weeks, groups of mice were painted on the dorsum with 2‐EHMC, and were then exposed to low doses of one of two artificial ultraviolet (UV) light sources. Mice were also treated with UV alone and with 2‐EHMC alone. The accumulated UV exposure alone produced tumours in 40–100% of mice. However, 2‐EHMC‐treated mice were protected. Subsequent treatment of the 2‐EHMC‐protected mice, and mice previously treated with 2‐EHMC alone, with the tumour promoter, croton oil, produced tumours on a significant number of animals.

We conclude that 2‐EHMC protects from UV tumorigenesis in the absence of a tumour promoter. However, although tumours appeared on only 4 out of 160 2‐EHMC‐treated mice exposed to UV, the carcinogenic process had been initiated in others, as application of the tumour promoter, croton oil, produced tumours. Statistical analysis of the incidence of promoted tumours inferred that prior irradiation with UV may not have been implicated. Therefore, 2‐EHMC itself may initiate tumours in this strain of hairless mouse.
ISOLATION OF ORTHO‐ AND PARAMYXOVIRUSES FROM WILD BIRDS IN WESTERN AUSTRALIA, AND THE CHARACTERIZATION OF NOVEL INFLUENZA A VIRUSES
Authors: Mackenzie JS , Edwards EC , Holmes RM , Hinshaw VS
Published: August 2007

As part of the World Health Organization's international programme on the ecology of influenza, cloacal swabs were collected from 3, 736 birds belonging to 67 species over a 3‐year period in Western Australia for the isolation of ortho‐ and paramyxoviruses. A total of 24 influenza A viruses were isolated from various species of ducks, shearwaters, noddies, terns and a coot, and were sub‐typed as H1N9, H3N8, H4N4, H4N6, H6N2, H6N4, H?N2, H?N6 and H?N9. The H? haemugglutinins did not react in tests with reference antisera. Whether they represent a novel haemagglutinin subtype or atypical members of an established subtype remains to be determined, although preliminary results indicate that they may be atypical members of the H7 subtype. The H1N9 isolate is the first reported isolate of this particular antigenic combination. A total of 17 Newcastle disease viruses was isolated from ducks, noddies, terns and a black‐fronted plover: preliminary results suggest that they are avirulent for domestic chickens. This study indicates that ortho‐ and paramyxoviruses are present in a variety of wild birds in Australia.
Fosmids of novel marine Planctomycetes from the Namibian and Oregon coast upwelling systems and their cross-comparison with planctomycete genomes
Authors: Woebken Dagmar , Teeling Hanno , Wecker Patricia , Dumitriu Alexandra , Kostadinov Ivaylo , DeLong Edward F , Amann Rudolf , Glöckner Frank O
Published: August 2007

Planctomycetes are widely distributed in marine environments, where they supposedly play a role in carbon recycling. To deepen our understanding about the ecology of this sparsely studied phylum six planctomycete fosmids from two marine upwelling systems were investigated and compared with all available planctomycete genomic sequences including the as yet unpublished near-complete genomes of Blastopirellula marina DSM 3645T and Planctomyces maris DSM 8797T. High numbers of sulfatase genes (41–109) were found on all marine planctomycete genomes and on two fosmids (2). Furthermore, C1 metabolism genes otherwise only known from methanogenic Archaea and methylotrophic Proteobacteria were found on two fosmids and all planctomycete genomes, except for ‘Candidatus Kuenenia stuttgartiensis’. Codon usage analysis indicated high expression levels for some of these genes. In addition, novel large families of planctomycete-specific paralogs with as yet unknown functions were identified, which are notably absent from the genome of ‘Candidatus Kuenenia stuttgartiensis’. The high numbers of sulfatases in marine planctomycetes characterizes them as specialists for the initial breakdown of sulfatated heteropolysaccharides and indicate their importance for recycling carbon from these compounds. The almost ubiquitous presence of C1 metabolism genes among Planctomycetes together with codon usage analysis and information from the genomes suggest a general importance of these genes for Planctomycetes other than formaldehyde detoxification. The notable absence of these genes in Candidatus K. stuttgartiensis plus the surprising lack of almost any planctomycete-specific gene within this organism reveals an unexpected distinctiveness of anammox bacteria from all other Planctomycetes.
What is the function of neuronal AP‐3?
Authors: Danglot Lydia , Galli Thierry
Published: August 2007

Neurotransmission requires the proper organization and rapid recycling of synaptic vesicles. Rapid retrieval has been suggested to occur either by kiss‐and‐stay or kiss‐and‐run mechanisms, whereas classical recycling is mediated by clathrin‐dependent endocytosis. Molecular coats are key components in the selection of cargos, AP‐2 (adaptor protein 2) playing a prominent role in synaptic vesicle endocytosis. Another coat protein, AP‐3, has been implicated in synaptic vesicle biogenesis and in the generation of secretory and lysosomal‐related organelles. In the present review, we will particularly focus on the recent data concerning the recycling of synaptic vesicles and the function of AP‐3 and the v‐SNARE (vesicular soluble N‐ethylmaleimide‐sensitive fusion protein‐attachment protein receptor) TI‐VAMP (tetanus neurotoxin‐insensitive vesicle‐associated membrane protein) in these processes. We propose that AP‐3 plays an important regulatory role in neurons which contributes to the basal and stimulated exocytosis of synaptic vesicles.
If I only had a brain: exploring mouse brain images in the Allen Brain Atlas
Authors: Hochheiser Harry , Yanowitz Judith
Published: August 2007

The combination of a powerful well‐designed user interface with detailed high‐quality data sets can create new possibilities for data exploration and analysis. The Allen Brain Atlas (http:www.brain‐map.org) provides a collection of tools for examining a set of images that detail gene expression in the mouse brain. Powerful web‐based viewers for individual images and parallel examination of related images interact with an external application for three‐dimensional views. The underlying dataset, generated via high‐throughput analysis of expression patterns of more than 21000 genes in adult mouse brains, provides three‐dimensional views of gene expression patterns displayed in the context of an anatomical ontology. Facilities for filtering views, saving views of interest, annotating images and sharing views via email support the ongoing process of analysis and provide a model for the future of integrated tools for analysing large image data sets.
Fabrication of organic light-emitting diode pixels by laser-assisted forward transfer
Authors: Fardel Romain , Nagel Matthias , Nüesch Frank , Lippert Thomas , Wokaun Alexander
Published: August 2007

Fabrication of a polymer light-emitting device was achieved by a laser forward transfer technique using the decomposition of a thin triazene polymer film by a XeCl excimer laser. The dry deposition process allows transfer of a bilayer consisting of the electroluminescent polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] covered with an aluminum electrode onto a receiver substrate. The soft transfer results in laterally well resolved pixels (≈500μm), whose fluorescence as well as electroluminescence spectra remain unaltered. The rectifying and smooth current-voltage characteristics add to the merits of this laser-based transfer method that opens up the possibility of direct-writing heat- and UV-sensitive materials.
Optical conductance of waveguides built into finite photonic crystals
Authors: Albaladejo S. , Sáenz J. J. , Lester M. , Froufe-Pérez L. S. , García-Martín A.
Published: August 2007

The concept of optical conductance is introduced in order to characterize the transport properties of waveguides built into finite photonic crystals. The conductance is given by the integral of the transmission cross section as a function of the incoming angle. This concept is illustrated by exact calculations of the light-guiding properties of a waveguide built into a photonic crystal slab based on a square lattice of dielectric cylinders in air. In analogy with their electronic counterparts, the optical conductance of a waveguide is quantized and thus provides a direct measure of the number of guided modes supported by the system.
Planar amplifier for a microlaser on a cholesteric liquid crystal
Authors: Blinov L. M. , Cipparrone G. , Lazarev V. V. , Umanskii B. A.
Published: August 2007

A planar device is described, which combines an oscillator (microlaser) based on a dye doped cholesteric liquid crystal and an amplifier made of another laser dye solution in glycerin. Both the oscillator and amplifier are pumped longitudinally with the same pump beam. With that simple 4mm thick structure, the oscillator beam was amplified seven times.
Evolution of interfacial adhesion force in dynamic micromachines due to repetitive impact loading
Authors: Philippine M. A. , Timpe S. J. , Komvopoulos K.
Published: August 2007

A contact-mode surface micromachine was used to study the effect of repetitive impact loading on the evolution of the adhesion force at sidewall contact interfaces. Low and stable adhesion force was encountered during the initial stage of impact testing (run-in phase). A surface degradation phase occurred subsequently in which the adhesion force increased logarithmically with impact cycles. The experimental trend was used to derive a method for predicting micromachine failure due to excessive interfacial adhesion. High-magnification scanning electron microscopy did not reveal any modification of the surface topography even after 5.5×107 impact cycles, despite the significant enhancement of the adhesion force, attributed to the increase of the real contact area and the higher surface energy produced as a result of the removal of thin surface layers. The dominant surface degradation mechanisms are interpreted in the context of adhesion force measurements and microscopy images of the impacted surfaces.
Synthesis of elongated Au nanoparticles in silica matrix by ion irradiation
Authors: Mishra Y. K. , Singh F. , Avasthi D. K. , Pivin J. C. , Malinovska D. , Pippel E.
Published: August 2007

The present work reports the synthesis of elongated Au nanoparticles (NPs) parallel to each other, embedded in silica matrix. Au NPs in silica, prepared using rf magnetron sputtering, were irradiated by 120MeV Au ions at different fluences to induce elongation. Optical absorption study of irradiated film showed a clear splitting of surface plasmon bands corresponding to transverse and longitudinal modes. Transmission electron microscopy investigations of pristine and irradiated samples revealed an elongation (aspect ratio of ∼3.5) in Au NPs occurred as a result of irradiation. The results are discussed in the framework of thermal spike model.
Reduction of etched AlGaAs sidewall roughness by oxygen-enhanced wet thermal oxidation
Authors: Liang D. , Hall D. C.
Published: August 2007

The authors demonstrate that the oxidation smoothing of sidewall roughness of dry-etched Al0.3Ga0.7As ridge structures is enabled through a modified wet thermal oxidation process which involves the addition of dilute amounts of O2 to the water vapor ambient. High magnification cross-section and top-view scanning electron microscope imagings both before and after oxide removal clearly show a substantial reduction of photolithography- and dry-etching-induced sidewall roughness (from σ∼100nm down to σ∼1–2nm), occurring only with the participation of added O2. The smoothing process provides means to realize high-index-contrast GaAs-based optical waveguides with both low bend and scattering losses.
Ultrastiff carbides uncovered in first principles
Authors: Chen Zhouwen , Gu Mingxia , Sun Chang Q. , Zhang Xinyu , Liu Riping
Published: August 2007

The authors have computationally designed ultraincompressible materials, namely, rhenium carbide, in the WC and NiAs structures with a very high shear modulus. The corresponding calculated bulk modulus is comparable with that of diamond. Especially for the WC-typed rhenium carbide (ReC), the incompressibility along the c axis is demonstrated to exceed the linear incompressibility of diamond. The unique mechanical properties would make it suitable for applications under extreme conditions.
Electromechanical response of porous piezoelectric materials: Effects of porosity distribution
Authors: Kar-Gupta Ronit , Venkatesh T. A.
Published: August 2007

A finite element model is developed to systematically characterize the effects of porosity distribution on the complete electromechanical response of transversely porous (3-1) piezoelectric systems and to obtain a quantitative assessment of the relative effects of porosity geometry and porosity distribution in porous piezoelectric materials. Upon identifying 25 characteristic porosity configurations for three piezoelectric materials with widely different crystal symmetries and porosity ellitpticity, it is demonstrated that the fundamental elastic, dielectric, and piezoelectric properties of porous materials exhibit relatively greater sensitivity to the porosity geometry, while the corresponding figures of merit such as the acoustic impedance and the hydrostatic charge coefficient can be modulated by tailoring the porosity distribution.
Monocrystalline NbN nanofilms on a 3C-SiC∕Si substrate
Authors: Gao J. R. , Hajenius M. , Tichelaar F. D. , Klapwijk T. M. , Voronov B. , Grishin E. , Gol’tsman G. , Zorman C. A. , Mehregany M.
Published: August 2007

The authors have realized NbN (100) nanofilms on a 3C-SiC (100)/Si(100) substrate by dc reactive magnetron sputtering at 800°C. High-resolution transmission electron microscopy (HRTEM) is used to characterize the films, showing a monocrystalline structure and confirming epitaxial growth on the 3C-SiC layer. A film ranging in thickness from 3.4to4.1nm shows a superconducting transition temperature of 11.8K, which is the highest reported for NbN films of comparable thickness. The NbN nano-films on 3C-SiC offer a promising alternative to improve terahertz detectors. For comparison, NbN nanofilms grown directly on Si substrates are also studied by HRTEM.
Interfacial and capillary pressure effects on the thermal performance of wax/foam composites
Authors: Almajali M. , Lafdi K. , Shaikh S.
Published: August 2007

A numerical investigation study was performed to study the phase change behavior of wax/foam composite encapsulated in an aluminum casing. Two types of foam materials, namely, aluminum and carbon, were infiltrated with paraffin wax. The progress of melt interface and temperature distribution within the encapsulated composite was analyzed using computational fluid dynamics software (CFD). A two-energy equation model was implemented in the CFD software through the use of user defined function (UDF). Interfacial effects influencing the heat transfer process at the casing-composite junction and between the wax-foam surfaces within the composite were addressed through the use of separate UDF. In addition, the effect of capillary pressure developed within the foam matrix was incorporated using an area ratio parameter. The contact resistance at the foam-casing interface and the capillary pressure had a major influence on the thermal behavior of the system. These two factors lowered down the heat transfer rate considerably and the melting area was reduced by more than 30%. The temperature profiles for the foam material showed a different pattern as compared to the temperature within the wax, which was due to the effect of thermal nonequilibrium.
Magnetic and transport properties of Eu1−xSrxCoO3
Authors: Kim K. H. , Qian T. , Kim Bog G.
Published: August 2007

We have studied the magnetic and electronic properties of Eu1−xSrxCoO3 with 0/16≤x≤12/16. In the Sr doping range from 2/16 to 11/16, the ferromagnetic clusters coexist spatially with an antiferromagnetic matrix. The magnetization at low temperatures strongly depends on the Sr concentration x, exhibiting a maximum near half doping, which is described in term of the double-exchange mechanism. The semiconductor-metal transition at low temperatures occurs at x between 4/16 and 5/16, which indicates that the ferromagnetic clusters coalesce, leading to a percolative metallic conduction up to the composition of x=10/16. As compared with those of La1−xSrxCoO3 and Nd1−xSrxCoO3, Eu1−xSrxCoO3 shows a larger critical Sr concentration for semiconductor-metal transition and lower ferromagnetic transition temperatures, which is attributed to the enhanced global and local lattice distortion due to the smaller cation radius of the Eu3+ ions.
Optical investigation of p-type ZnO epilayers doped with different phosphorus concentrations by radio-frequency magnetron sputtering
Authors: Kwon B. J. , Kwack H. S. , Lee S. K. , Cho Y. H. , Hwang D. K. , Park S. J.
Published: August 2007

Optical properties of p-type ZnO epilayers doped with different amounts of phosphorus by radio-frequency magnetron sputtering are investigated by x-ray diffraction, temperature dependent photoluminescence (PL), and time-resolved PL techniques. Bound exciton, free electrons-to-acceptors, donor-to-acceptor pair, and deep-level emissions are observed at about 3.356, 3.32, 3.24, and 2.4eV at 10K for p-type ZnO, respectively. The crystal quality and luminescence efficiency are improved with increasing phosphorus doping concentration. These results show that phosphorus doping plays an important role both in reducing native defects and in generating shallow acceptors in ZnO, leading to a good p-type conductivity in ZnO.