bluuebunny/crossref_metadata_2025 huggingface dataset:
Character study: Strengthening the heart of good leadership
Authors: Klann Gene
Published: September 2003

In the past few years, headlines in the business pages have underscored the fact that some corporate leaders
leave a lot to be desired in the area of character. Yet because it is subjective and controversial, the issue of
character has largely been left out of the equation when it comes to training and preparing leaders. If
undertaken with the right perspective, however, there are ways to develop character in leaders.
What women want: Comparing leadership challenges in Europe and the U.S.
Authors: Ohlott Patricia , Bhandary Aparna , Tavares Joan
Published: September 2003

As European companies strive to provide more in the way of support for talented women managers who deserve to
rise up the career ladder, they have little to go by to identify the major obstacles faced by these managers and to
respond to their developmental needs. Now some recent CCL research suggests some answers.
Development of midline glial populations at the corticoseptal boundary
Authors: Shu Tianzhi , Puche Adam C. , Richards Linda J.
Published: September 2003

Three midline glial populations are found at the corticoseptal boundary: the glial wedge (GW), glia within the indusium griseum (IGG), and the midline zipper glia (MG). Two of these glial populations are involved in axonal guidance at the cortical midline, specifically development of the corpus callosum. Here we investigate the phenotypic and molecular characteristics of each population and determine whether they are generated at the same developmental stage. We find that the GW is derived from the radial glial scaffold of the cortex. GW cells initially have long radial processes that extend from the ventricular surface to the pial surface, but by E15 loose their pial attachment and extend only part of the way to the pial surface. Later in development the radial morphology of cells within the GW is replaced by multipolar astrocytes, providing supportive evidence that radial glia can transform into astrocytes. IGG and MG do not have a radial morphology and do not label with the radial glial markers, Nestin and RC2. We conclude that the GW and IGG have different morphological and molecular characteristics and are born at different stages of development. IGG and MG have many phenotypic and molecular characteristics in common, indicating that they may represent a common population of glia that becomes spatially distinct by the formation of the corpus callosum. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 81–94, 2003
Removal of both antennae influences the courtship and aggressive behaviors in male crickets
Authors: Murakami Shio , Itoh Masanori T.
Published: September 2003

To test whether insect antennae are necessary for eliciting courtship and aggression toward appropriate partners, we antennectomized adult male crickets (Gryllus bimaculatus) and observed their behavior toward other antennectomized males and intact females. At 7 days after removal of both antennae, pairs of antennectomized males were placed together; 80% displayed courtship behavior, generating courtship song by rubbing their forewings together, toward other antennectomized males, and 20% displayed aggressive behavior. Only 45% courted intact females. No intact males courted antennectomized males, and 80% displayed aggressive behavior. All intact males courted females. The results for males with one antenna removed were essentially the same as for intact males. These findings indicate that a high proportion of male crickets with both antennae removed court other males and fail to display male‐male aggression, demonstrating that removal of antennae from male crickets induces male‐male courtship and that an antenna is necessary for the expression of male‐male aggression. Moreover, brain serotonin (5‐hydroxytryptamine; 5‐HT) levels in male crickets were significantly reduced at 7 days after removal of antennae. The reduction of 5‐HT was detected primarily in the central body of the brain. Thus, 5‐HT in the central body of the male cricket brain may be involved in the behavioral changes. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 110–118, 2003
Intact spatial discrimination performance but impaired reaction time performance after frontal cortex lesions in the rat
Authors: Blokland A. , Broersen L.M. , Uylings H.B.M. , Jolles J.
Published: September 2003

In the present study the consequences of frontal cortex (FC) lesions on spatial discrimination learning and reaction time performance were assessed in rats. Spatial working‐ and reference memory were tested simutalneously in a cone field task. It was found that FC lesions did not impair both aspects of spatial discrimination performance in this task. In a choice reaction time task the FC lesion decreased the response speed (reaction time and motor time). Detailed analysis of the reaction times indicated that these effects could be attributed to an impaired motor preparation and/or an attention deficit. The present study suggests that claims of deficit in learning and memory following FC lesions should take into account possible effects of motor preparation/execution and attention.
Differential regulation of map kinase isoforms by H2O2 in neuronal cells
Authors: Gargi Amandeep , Kumar Naresh , Dey Chinmoy S.
Published: September 2003

The mitogen‐activated protein kinase (MAPK) family is involved in the regulation of cellular proliferation, differentiation and stress signals. In this study, we investigated the role of MAPK in response to H2O2, an oxidative stress, in neuronal cells. Activation of c‐Jun‐N‐terminal kinase (JNK) was sustained, where as extracellular signal‐regulated kinase (ERK) and p38 MAPK were transiently activated in response to H2O2 treatment. Inhibition of ERK and p38 resulted in higher activation of JNK in response to H2O2 treatment. The treatment with H2O2 led to apoptosis. The results implicate potential role of MAP kinases in neurodegenerative disorders mediated by oxidative stress.
Vitamin D receptor expression in the embryonic rat brain
Authors: Burkert Rachel , McGrath John , Eyles Darryl
Published: September 2003

We are interested in determining whether low maternal vitamin D3 affects brain development in utero. Whilst the vitamin D receptor (VDR) has been identified in embryonic rat brains, the timing and magnitude of its expression across the brain remains unclear. In this study we have quantitated VDR expression during development as well correlated the timing of its appearance with two vital developmental events, apoptosis and mitosis. Brains from embryonic rats (embryonic days 15–23) were examined. We show that the well‐described increase in apoptotic cells and decrease in mitotic cells during development correlates with the appearance of the VDR in brain tissue. Given that vitamin D3 regulates mitosis and apoptosis in non‐neuronal tissue we speculate that the timing of VDR expression in embryonic brain may directly or indirectly mediate features of neuronal apoptosis and mitosis.
MRSDCI study of the two lower‐lying doublet electronic states of the BeB, MgB, and CaB molecules
Authors: Pelegrini Marina , Roberto‐Neto Orlando , Machado Francisco B. C.
Published: September 2003

Potential energy curves, dipole and transition moment functions, spectroscopy constants, radiative transition probabilities, and lifetimes for the two lower‐lying doublet states (X2Π and A2Σ+) of the BeB, MgB, and CaB molecules are reported with multireference singles and doubles configuration interaction methodology. Radiative lifetimes for ν′ = 0 are predicted to be 158 μs, 281 μs, and 87 μs for BeB, MgB, and CaB, respectively. The strongest transitions from ν′ = 0 should occur to vibrational levels ν″ = 0 and 1 for BeB, to ν″ = 2 and 3, for MgB and to ν″ = 3 and 4 for CaB. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 205–212, 2003
Polyacetylene as a qubit system
Authors: Da Silva Andre Elvas Pereira , Silva Geraldo Magela E
Published: September 2003

The dynamics of a polyacetylene single chain as a system for possible physical implementations of quantum bits is determined. This novel proposition is studied by varying intensity and duration of application of an electric field as well as the intensity, number, and position in the polymer chain of impurity molecules. The behavior of soliton pairs, whose associated energy levels form the quantum bit, is analyzed. The chain is modeled by a modified Pariser–Parr–Pople Hamiltonian extended to include the effects of an external electric field and the parameters of the impurity molecules. The effect of the variation of the field and impurities on the separation of the energy levels associated with soliton pairs is analyzed by numerical integration of the equations of motion. Two different approaches for controlling the separation of levels are presented and their features compared. First, we examine the use of changes in the electric field to control the distance (and ultimately coupling) between two solitons moving freely on the chain or captured by the potential generated by the impurity molecules. Second, we look at the change in the intensity of the impurities alone, with no application of an external field. We have found that the effect of the use of the field on the separation of levels is much smaller than the one obtained by changes in the parameters of the impurity molecules, which eventually led us to achieve quantum bit behavior in a polyacetylene chain. The influence of the field and impurity parameters in the energy levels is determined, as is their role in the coupling of the two solitons on the chain. Critical values for distance between solitons, intensity of field, and impurities that determine whether a pair of solitons can work as a quantum bit are obtained. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 224–229, 2003
Combined computational and chemometric study of 1H‐indole‐3‐acetic acid
Authors: Kiralj Rudolf , Ferreira Márcia M. C.
Published: September 2003

Geometries of free 1H‐indole‐3‐acetic acid (IAA) and IAA hydrogen bond dimer were optimized at several computational levels: molecular mechanics, semiempirical methods, ab initio density functional theory with SVWN (Slater‐Vosko‐Wilk‐Nusair) and Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar (B3LYP) functionals, and Hartree–Fock (HF). Bond length matrices X(mxn) (m = number of bonds, n = number of experimental determinations and theoretical calculations) and their transposes X(nxm) for IAA monomer, IAA dimer, and hydrogen bond ring (angles included) were analyzed using principal component analysis (PCA) and hierarchical cluster analysis (HCA). Ab initio methods prove to be superior to molecular mechanics and semiempirical methods: SVWN methods are the best for monomer, and B3LYP are best for dimer geometry optimization. The B3LYP and HF methods can be used equally well for optimization of the dimer ring geometry. Other hydrogen bond and aromaticity structural parameters exhibit preference either for B3LYP or SVWN methods. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 237–251, 2003
Conformational analysis and electronic interactions of 2‐thiosubstituted cyclohexanones by semiempirical method PM3
Authors: Faria Luciano Emerich , Donnici Claudio Luis , Lopes Júlio César Dias
Published: September 2003

Some 2‐phenylthio‐para–substituted cyclohexanones with different oxidation states of sulfur atom were studied by systematic conformational search around C–S bonds using the parametric method 3 (PM3) Hamiltonian. The axial and equatorial regular chair conformations were subjected to calculations and each one produced three rotamers: +gauche (+G), −gauche (−G), and anti (A). The axial conformations were more populated than the equatorial ones. The para‐substituent and sulfur group effects over conformational populations and carbonyl polarizations suggest that the main electronic interaction between sulfur atom and carbonyl group are of repulsive nature in both axial (such as S+C+O) and equatorial (such as S−CO−) conformations. The axial +G conformation is the more stable for all compounds, except for (R2,SS)‐sulfinyl isomer, because it allows an attractive electrostatic interaction between C–O and S–ϕ bond dipoles (such as S+CO−). The axial A conformation is the more stable for (R2,SS)‐sulfinyl compounds, because the sulfinyl oxygen is at −G position near the carbonyl group and an attractive electrostatic interaction (such as OC+O) can take place. The higher carbonyl polarization and negative charge of carbon C–2 plus hydrogen H–2 of cyclohexanone ring for sulfonyl compared with sulfanyl and sulfinyl compounds, can be explained by a through‐space interaction instead through‐bond inductive effects. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 313–321, 2003
Contemporary Financial Issues in Student Unions and Campus Activities
Authors: Schroer Tim , Johnson Christana J.
Published: September 2003

Although they vary a great deal in size and scope, student unions and activity programs share several financial constraints and challenges.
The Naturalistic Response to Scepticism
Authors: Weintraub Ruth
Published: September 2003

Hume is sometimes thought to provide a ‘naturalistic’ response to the sceptic. I consider two ways in which this response may be construed. According to the first, the fact that we are psychologically determined to hold a belief provides it with justification. According to the second, ‘natural’ beliefs provide limits within which reason can legitimately be employed, limits which the sceptic transgresses when he attempts to defend his position. Both versions of the naturalistic response to scepticism, I will argue, aren't plausible. And they aren't, at least not predominantly, Hume's.
Time to stop trying to provide an account of Time
Authors: Read Rupert
Published: September 2003

Dummett argues that there are difficulties with existing accounts of time, and urges us to consider the merits of his alternative ‘constructionist’ account. He derides my opting out of the debate between him and his Realist opponents as “quietist”.

But the epithet “quietist” only works if there actually is some genuine topic on which I am staying quiet (or silencing others). Whereas I simply urge that, while Dummett has correctly identified difficulties with Realist accounts of time, he does not have any valid reason for opposing those accounts—and such valid reason can only come from a radically different approach which questions whether those accounts or any alternatives to them can satisfy those who wish to put them forward.

I argue that at best such accounts present fragments of ‘the grammar’ of time, in a rather misleading form.
Partisan Politics, Party Competition and Veto Players: German Economic Policy in the Kohl Era
Authors: Zohlnhöfer Reimut
Published: September 2003

The article explains economic policy in Germany with a model that takes partisan theory as its starting point, but supplements it with the impact of party competition and veto players. During the 1980s the low internal cohesion of the Christian democrats along with a positive economic performance kept the coalition from introducing coherent reforms. With the loss of the majority in the second chamber, compromises with the opposition were necessary which further diluted reforms with few exceptions. When the government faced worsening economic conditions which put its re-election at risk, it introduced more radical reforms. Because of an opposition majority in the second chamber, however, those reforms ran the risk of failing. In sum, Tsebelis' veto player theory is corroborated with some qualifications, the most important of which is that it must also take into account strategic orientations of actors.
Adaptation and Integration through Policy Re-categorization
Authors: Ugland Trygve
Published: September 2003

This comparative study analyses how the state alcohol monopoly systems in Finland, Norway and Sweden were affected by interaction with the European Union (EU). Pressures from the EU, as well as the contrasting domestic responses in this process, are viewed in relation to how these institutions were integrated in terms of consistency, interdependence and structural connectedness. The article goes beyond the frequent observation that external scrutiny and pressures challenge national policy coherence to show that domestic public policies also may emerge more coherent and integrated. It is suggested that the relationship between the way public policies are integrated, categorized and re-categorized provides important insights towards our understanding of the dynamics of public policy.
Source parameters of acoustic emission events and scaling with mining‐induced seismicity
Authors: Sellers Ewan J. , Kataka Milton O. , Linzer Lindsay M.
Published: September 2003

A series of uniaxial compression tests were performed on 96‐mm‐diameter quartzite samples, 242 mm in length, to understand the scaling of rock fracture processes. Nine acoustic emission (AE) sensors glued to each sample monitored the AEs resulting from microcracking within the samples. In contrast to previous AE studies, the sensors were calibrated as velocity transducers so that the output could be compared to mining‐induced seismicity and natural earthquakes. A new hybrid, relative moment tensor method was applied to obtain source mechanism solutions for eight clusters of events. Once the AE rate accelerated prior to failure, the event positions are associated with the observed failure planes. The moment tensors were found to have double‐couple components, indicating that shearing was occurring. The stress drop appears to be constant over the range of moments suggesting the self‐similar scaling of the fracture response from the laboratory sample to mine seismicity and natural earthquakes over a wide range of length scales. Similar conclusions can be drawn by considering the apparent stress and source radius. The scaling of the peak velocity and peak acceleration parameters is apparently consistent with mining‐induced seismicity but is considerably affected by high‐frequency attenuation and the limited bandwidth. This is confirmed by the frequency‐magnitude plot, which has a slope of unity. The fracture processes in the laboratory are similar to those occurring underground near stope faces and pillars in deep‐level South African gold mines, where there is a high vertical compression and low confinement.
Permeability evolution during the formation of gas hydrates in marine sediments
Authors: Nimblett J. , Ruppel C.
Published: September 2003

Fluxes of gas, energy, and fluid (water with dissolved gas) are known to control the distribution of gas hydrate and free gas in gas hydrate reservoirs, but theoretical studies have so far not focused on the effect of sediment properties (e.g., permeability) on these fluxes during the formation of gas hydrate deposits. Using a transient, one‐dimensional, two‐phase (gas hydrate and fluid) numerical model based on a coupled conservation approach, we examine permeability clogging during gas hydrate formation in end‐member porous media and fractures initially lacking hydrate and determine the resulting changes in fluid and advective energy flux. Gas hydrate accumulates most rapidly at depth in both systems, a result consistent with borehole logging and seismic studies on the Blake Ridge. Consideration of the ratio of surface area to fluid volume explains model results that imply more rapid permeability reduction in the porous media system and more uniform hydrate formation as a function of depth in the fracture system. Depending on fluid flux, fracture aperture, or pore sizes, and other factors, the timescale for permeability clogging due to the accumulation of gas hydrate ranges from thousands to millions of years. Regenerating gas hydrate to a concentration of 10–15% of pore space in marine settings with fluid fluxes characteristic of Hydrate Ridge or Blake Ridge requires 103–105 years, meaning that hydrate deposits in these settings cannot be viewed as a naturally renewable resource. These results also imply that significant time is required to reestablish gas hydrate deposits after large‐scale dissociation events associated with global‐scale climate change.
Sensitivity of the marine biospheric Si cycle for biogeochemical parameter variations
Authors: Heinze C. , Hupe A. , Maier‐Reimer E. , Dittert N. , Ragueneau O.
Published: September 2003

A systematic quantitative assessment of the marine silicon cycle is presented, based on a prognostic coupled water column‐sediment global biogeochemical ocean general circulation model (HAMOCC). The resulting tracer distributions are compared with a comprehensive marine Si database of measurements. The model parameters which govern the Si cycle within the model world are optimized through a linear response model. The functional relationships between the Si cycle parameters and the Si tracer distributions are derived from a series of sensitivity experiments addressing opal export production, particle flux through the water column, porewater chemistry, and external biogeochemical forcing. The most important parameters for a further quantitative improvement of the simulation are depth‐dependent opal dissolution kinetics, a productivity‐dependent opal settling velocity, a general change in maximum Si uptake velocity Vmaxopal, and the clay as well as the Si input from continental weathering. The modeled Si budget shows a larger global export production, larger opal deposition rates onto the sediment surface and higher diffusive transports of porewater silicic acid into the open water column as estimated by Tréguer et al. [1995].
Using earthquake doublets to study inner core rotation and seismicity catalog precision
Authors: Li Anyi , Richards Paul G.
Published: September 2003

We report our search for doublets in the South Sandwich Islands (SSI) region among 906 earthquakes from January 1982 to December 1998. Event pairs with source separation less than 40 km, which was calculated using PDE locations, were checked using vertical component short period and broadband digital records. Cross correlation coefficients of P (or PKP) waveforms were computed for similarity comparison. Whole waveforms of those event pairs with correlation coefficients larger than 0.8 were checked by eye. By this process, 17 doublets were found, some of which form multiplets. However, only one doublet event pair (14 August 1995 and 28 March 1987) has clear PKP(DF) phases on both records at College, Alaska (COL). The PKP(DF) travel time change measured by cross correlation is a decrease by 0.15 s, with standard deviation 0.02 s, over a time period of about 8 years. This result strongly supports differential rotation of the Earth's inner core relative to the mantle and the crust. The estimated rotation rate ranges from 0.4° to 1° per year eastward. The special case of a locked inner core can then be ruled out. We also checked the precision of PDE and ISC locations using the 17 doublets. Results show that both catalogs have relatively high location precision. Standard deviations in latitude, longitude and depth are less than 4 km, 6 km, and 10 km respectively, supporting prior claims of detection of inner core rotation [Song and Richards, 1996].
A new parameterization of hydrous mantle melting
Authors: Katz Richard F. , Spiegelman Marc , Langmuir Charles H.
Published: September 2003

Modeling of melt formation and transport in all tectonic settings requires the inclusion of water, since water has large effects on mantle solidi as well as physical properties of liquids. To facilitate the inclusion of water in melting models this paper presents a new parameterization for melt fraction as a function of pressure, temperature, water content and modal cpx, based on knowledge gained from recent advances in the fields of thermodynamic modeling as well as experimental investigations of peridotite melting and hydrous equilibria. The parameterization is computationally efficient and can be modified easily as better experimental data become available. We compare it to other published parameterizations and test it in simple calculations of adiabatic decompression melting (mid‐ocean ridge) and hydrous melting (subduction zone).
Surface sediment effects on teleseismic P wave amplitude
Authors: Zhou Ying , Nolet Guust , Dahlen F. A.
Published: September 2003

Teleseismic P waves are dominated by relatively low frequency (<1 Hz) signals due to the Earth's attenuation; because of this, receiver site effects are usually assumed to be independent of frequency. We investigate the site amplitude effects due to a surface sediment layer and show that teleseismic frequency‐dependent site effects can be important. One‐dimensional modeling shows that the effects of amplification due to differences in impedance, combined with amplitude losses to reverberations in the sediment layer, can result in significantly frequency‐dependent site effects. The extent of the frequency dependence depends upon the two‐way travel time of P waves in the sediments and the dominant period of the P waves. Using model CRUST2.0, we compute a 2° × 2° map of the “reference” period of P waves above which the dependency can be neglected. We argue that the common practice of applying station corrections to magnitude determination will underestimate the magnitude of large earthquakes. To show that these effects are observable in practice, we analyze the amplitude ratios of seven teleseismic events at the station pair KURK and MAKZ and six events at the station pair KMI and CHTO. The amplitude ratios are relatively insensitive to other contributing effects and are in good agreement with the predicted frequency‐dependent effects of the surface sediment layer.
Seismic evidence for a chemical heterogeneity in the midmantle: A strong and slightly dipping seismic reflector beneath the Mariana subduction zone
Authors: Niu Fenglin , Kawakatsu Hitoshi , Fukao Yoshio
Published: September 2003

A clear later phase ∼80 s after the direct P wave is observed in most of individual seismograms recorded by a short‐period seismometer network in Japan (J‐array) from a cluster of deep earthquakes that occurred at the northern Mariana subduction zone. This phase (1) shows a P wave particle motion, (2) arrives later from earthquakes with shallower focal depths, (3) has a steeper incident angle than that of P wave, and (4) shows a deviation of a few degrees in the arrival azimuth from that of P wave. We interpret it as an S‐to‐P converted wave which takes off downward from the source and is reflected at a velocity discontinuity (reflector) below the earthquakes. Travel time inversion shows that the seismic reflector dips southwest by ∼20° at 24.25°N, 144.75°E, and at a depth of 1115 km with a lateral extension at least 100 × 100 km. The location corresponds to the lower edge of a high‐velocity anomaly in global tomographic models. Amplitude and waveform analyses suggest a decrease of S wave velocity by 2–6% and an increase of density by 2–9% within the reflector. There is almost no difference in P wave velocity (<1%) between the reflector and the surrounding mantle. The estimated thickness of the reflector is ∼12 km. These observations indicate that the observed seismic structure is more likely to be a chemical reservoir rather than a purely thermal anomaly. The seismic reflector might be a piece of subducted oceanic crust, as suggested by a previous study. It also could be related to the break down of the D phase of dense hydrous magnesium silicates at midmantle pressure condition reported by recent mineral physics studies. Both scenarios imply that mechanical/chemical segregation might occur within the subducted slab at midmantle condition.
Dense water formation in the Aegean Sea: Numerical simulations during the Eastern Mediterranean Transient
Authors: Nittis Kostas , Lascaratos Alex , Theocharis Alex
Published: September 2003

Dense water formation processes in the Aegean Sea (eastern Mediterranean) are studied using a three‐dimensional numerical ocean model. The simulations cover the period 1979–1994 during which major changes that affected the thermohaline circulation of the whole Mediterranean Sea were recorded. Sensitivity studies that focus on the role of freshwater budget are presented, and the results are evaluated against available hydrological data of the same period. The very cold winters of 1987, 1992, and 1993 and the extended dry period 1989–1993 that affected the whole eastern Mediterranean Sea are the main driving mechanisms, corresponding to 50% and 32%, respectively, of the excessive deepwater volume formed in the Aegean after 1987. The reduced Black Sea Water outflow during the same dry period was another important forcing mechanism, contributing 18% to the total formation, while the increased inflow of saline waters from the Levantine Sea after 1992 was an additional preconditioning factor. The locations and mechanisms of water formation processes are identified with combined analysis of data from the March 1987 oceanographic cruise in the Aegean Sea and the respective model results for that period. Deep water is found to be formed mainly through open ocean convection in the central and north Aegean Sea, while the contribution of shelf areas is limited. Intermediate water is also formed through open ocean convection in the southern Aegean Sea during cold winters as well as in the central and northern Aegean during mild winters. The total volume of dense water formed during 1979–1994 corresponds to an annual formation rate of 0.24 Sv for deep water and 0.34 Sv for intermediate water.
Profiling of a Saharan dust outbreak based on a synergy between active and passive remote sensing
Authors: Léon Jean‐François , Tanré Didier , Pelon Jacques , Kaufman Yoram J. , Haywood Jim M. , Chatenet Bernadette
Published: September 2003

Spaceborne lidars will give a new view of the vertical distribution of atmospheric aerosols and clouds. CALIPSO will be launched in the fall of 2004 and will provide, for the first time, a global picture of the profile of atmospheric scattering layers using an onboard lidar radiated at 0.532 and 1.064 μm. CALIPSO will fly in an orbital formation with passive radiometers, such as the Moderate resolution Imaging Spectrometer (MODIS) and the Polarization and Directionality of Earth's Reflectance (POLDER) instruments, that monitor Earth's atmosphere. The purpose of this paper is to analyze the improvement in retrieval capabilities of profiles of aerosol optical properties using a synergy between passive and active (lidar) remote sensing techniques. Aerosol properties derived from the MODIS spectroradiometer are used to constrain the inversion of the lidar signal in terms of aerosol optical thickness and effective radius. We use the lidar spectral backscattering coefficient between 0.532 and 1.064 μm to determine the profile of backscatter‐to‐extinction ratio. The effective radius of an assumed bimodal aerosol size distribution is then retrieved as a function of the altitude. A sensitivity analysis demonstrates the robustness of the inversion procedure in case of noise detection and calibration error. The algorithm has been tested during the Saharan dust experiment, which took place in the northeastern tropical Atlantic in September 2000. The vertical profile of extinction compares well with in situ measurements of the aerosol extinction. Profiles derived from lidar measurements on 25 September highlight the presence of the Saharan air layer located between 2.2 and 4.5 km with particle effective radii of 1.19 ± 0.6 μm. Another dust layer within the sub‐Saharan transition layer over the marine boundary layer is also observed, with particle radii significantly smaller than within the Saharan air layer.
Spatial heterogeneity in aeolian erodibility: Uniform, topographic, geomorphic, and hydrologic hypotheses
Authors: Zender Charles S. , Newman David , Torres Omar
Published: September 2003

Soil aeolian erodibility is the efficiency with which soil produces dust for a given meteorological forcing. Quantifying soil erodibility is crucial for forecasting dust events and the climatological distribution and forcing of dust. We use long‐term station observations and satellite indices of mineral dust to ascertain the role of regional topography, geomorphology, and hydrology in controlling sediment availability and erodibility. Our null hypothesis is that soil erodibility is globally uniform, so that emissions are determined by instantaneous local meteorology, vegetation, and soil moisture. We describe and quantify three competing hypotheses on regional processes which may affect local soil erodibility: (1) Erodibility is characterized by the relative elevation of source regions in surrounding basins. (2) Erodibility is characterized by the upstream area from which sediments may have accumulated locally through all climate regimes. (3) Erodibility is characterized by the local present‐day surface runoff. These hypotheses are tested in 3‐year simulations of the global Dust Entrainment and Deposition (DEAD) model. All three spatially varying erodibility hypotheses produce significantly better agreement with station and satellite data than the null (Uniform) hypothesis. The Uniform hypothesis explains none of the spatial structure of emissions in Australia. Heterogeneous erodibility may explain up to 15–20%, 15–20%, and 50% more of the spatial structure of dust emissions than Uniform erodibility in the Sahara+Arabian Peninsula, East Asia, and Australia, respectively. The Geomorphic erodibility hypothesis performs best overall, but results vary by region and by metric. These results support the hypothesis that dust emission “hot spots” exist in regions where alluvial sediments have accumulated and may be disturbed. Our physically based erodibility hypotheses help explain dust observations in some regions, particularly East Asia, and can be used to help discriminate between natural and anthropogenic soil emissions.
Meteorological conditions and transport pathways during the Transport and Chemical Evolution over the Pacific (TRACE‐P) experiment
Authors: Fuelberg Henry E. , Kiley Christopher M. , Hannan John R. , Westberg David J. , Avery Melody A. , Newell Reginald E.
Published: September 2003

The Transport and Chemical Evolution over the Pacific (TRACE‐P) experiment was conducted between February and April 2001. It included extensive chemical sampling by two aircraft based primarily in Hong Kong and Yokota Air Base, Japan. TRACE‐P examined pathways for the outflow of chemically and radiatively important gases and aerosols and their precursors from eastern Asia to the western Pacific and explored the chemical evolution of Asian outflow. This paper describes meteorological conditions and transport pathways over the Pacific Basin during TRACE‐P. Meteorological conditions changed rapidly during the period due to the seasonal winter to spring transition and the decay of prolonged ENSO cold phase (La Nina) conditions. To document these changes, TRACE‐P was divided into two halves, and mean flow patterns during each half are presented and discussed. Important circulation features are the semipermanent Siberian anticyclone and transient middle latitude cyclones that form near eastern Asia and then move eastward over the northern Pacific. Five‐day backward trajectories from the various flight tracks show that air sampled by the aircraft had been transported from a variety of locations. Some parcels remained over the tropical western North Pacific during the entire period, while other important origins were Southeast Asia, Africa, and central Asia. Specifically, lower tropospheric flight segments out of Hong Kong sampled both prefrontal maritime air as well as postfrontal air from the Asian continent. Conversely, low‐level flight segments out of Yokota, Japan mostly sampled postfrontal Asian air. Southern portions of middle and upper tropospheric flight segments from Hong Kong sampled air previously in the deep tropics, while the more northerly flight segments sampled air that originated from the west (e.g., passing over central Africa and India). Most upper level flight segments from Yokota sampled air arriving from the west. Patterns of satellite‐derived precipitation and lightning are described. TRACE‐P occurs during a neutral to weak La Nina period of relatively cold sea surface temperatures in the tropical Pacific. Compared with climatology, the TRACE‐P period exhibits deep convection located west of its typical position; however, tropospheric flow patterns do not exhibit a strong La Nina signal. Circulation patterns during TRACE‐P are found to be generally similar to those during NASA's PEM WEST‐B mission that occurred in the same region during February–March 1994.
Summary of measurement intercomparisons during TRACE‐P
Authors: Eisele F. L. , Mauldin L. , Cantrell C. , Zondlo M. , Apel E. , Fried A. , Walega J. , Shetter R. , Lefer B. , Flocke F. , Weinheimer A. , Avery M. , Vay S. , Sachse G. , Podolske J. , Diskin G. , Barrick J. D. , Singh H. B. , Brune W. , Harder H. , Martinez M. , Bandy A. , Thornton D. , Heikes B. , Kondo Y. , Riemer D. , Sandholm S. , Tan D. , Talbot R. , Dibb Jack
Published: September 2003

The NASA DC‐8 and P‐3B aircraft flew within about a kilometer or less of each other on three occasions during the Transport and Chemical Evolution Over the Pacific (TRACE‐P) campaign in order to intercompare similar measurements on the two aircraft. The first and last intercomparisons were in relatively remote marine environments during transits to and from Asia. The first began with a boundary layer measurement followed by an ascent to 3 km. The second set of intercomparisons was at a fixed altitude of about 5.2 km off the coast of Japan, also in relatively clean air. Finally, the third measurement began at 5.3 km and then descended into the boundary layer. A number of measurements were compared with the best agreement observed for the most abundant compounds such as CO2 and CH4 and with very good agreement for CO, O3, and j values. Other comparisons, including measurements of the same compounds on both aircraft and measurements of the same compound by two different instruments on the DC‐8, varied over a wide range from quite good for PAN, NO, HNO3, H2O; to reasonable agreement for OH, HO2 CH2O, acetone, and methylethylketone; and to generally poor for NO2,SO2, PPN, acetaldehyde, and methanol. The comparison results, particularly those for the fast 1‐s CO and O3 measurements, suggest that credible intercomparisons can be made using two aircraft in close proximity for relatively long lifetime and stable compounds. Much new understanding can also be gained from measurements of more reactive and generally shorter lifetime compounds, but additional improvements are needed to make such studies as meaningful as those of longer lifetime compounds. Comparisons such as these, made as a component of a larger field campaign, have the advantage that they test the actual instrument configuration used during the field study and they require no additional instrument installation and testing.
Wavelength‐dependent aerosol single‐scattering albedo: Measurements and model calculations for a coastal site near the Sea of Japan during ACE‐Asia
Authors: Höller Robert , Ito Keisuke , Tohno Susumu , Kasahara Mikio
Published: September 2003

Wavelength‐dependent optical properties together with the size‐resolved elemental and chemical composition of the atmospheric aerosol were measured at Yasaka, Japan, near Wakasa Bay on the coast of the Sea of Japan. Observations were performed as part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) campaign during three weeks in March and April 2001. Information about the detailed chemical composition and the size distribution of the aerosol, including absorbing material, was used to model optical properties of the aerosol and compare them with directly measured properties. Continuous, size‐resolved measurements of aerosol scattering and backscattering coefficients were made at wavelengths of 450, 550, and 700 nm. Aerosol size distribution measurements were taken three times during the campaign for a period of 3–4 days each, using cascade impactors. One of the measurement periods was influenced by an intense yellow dust event originating on the Asian continent (20–25 March 2001), while the other two data sets were only weakly influenced by dust particles. The size‐resolved measurement of aerosol scattering coefficients and the chemical analysis showed that the dust was accompanied by fine accumulation‐mode particles during the dust event. The effects of the mineral dust particles on the optical and chemical properties of the aerosol are discussed, and data sets with and without desert dust influence are compared. Before the optical closure calculation a mass closure of the aerosol was performed, and the influence of the nonanalyzed fraction on the calculated optical properties of the aerosol is investigated. In general, good agreement between measured and modeled aerosol optical properties was found for the aerosol scattering and absorption coefficients, while less agreement was found for the backscattering coefficients, especially for the coarse mode of the aerosol. A distinct difference between the dust and nondust periods was found for the wavelength‐dependent single‐scattering albedo.
Size distributions of ionic aerosols measured at Waliguan Observatory: Implication for nitrate gas‐to‐particle transfer processes in the free troposphere
Authors: Ma Jianzhong , Tang Jie , Li Shao‐Meng , Jacobson Mark Z.
Published: September 2003

Waliguan Observatory (WO) is a land‐based Global Atmosphere Watch baseline station on the Tibetan Plateau. Size‐resolved ionic aerosols (NH4+, Na+, K+, Ca2+, Mg2+, SO42−, Cl−, NO3− CO32−, formate, acetate and oxalate), organic aerosols, black carbon and gaseous HNO3 and SO2 were measured during an intensive fall‐winter field experiment. The observational data were analyzed with a focus on the partitioning of nitrate between the gas and particle phases. Nitrate was found to exist mainly in the particle phase with a typical particulate‐to‐total nitrate ratio, i.e., NO3−(p)/(NO3−(p) + HNO3(g)), of about 0.9. It was also found that the size distribution pattern of particulate nitrate at WO varied in different samples and the amount of particulate nitrate residing in the fine mode (Dp < 2.0 μm) was typically larger than or comparable with that in the coarse mode. A gas‐particle chemical equilibrium model was used to predict these particulate nitrate size distributions. The size distributions of particulate nitrate were reasonably reproduced with the model within the uncertainties caused by the detection limits. The chemical pathways for the formation of particulate nitrate at WO were analyzed with the size distributions of measured ionic aerosols. It was demonstrated that fine nitrate particles may have been produced by the reaction of gaseous nitric acid with gaseous ammonia, while coarse nitrate particles may have been generated via the condensation of nitric acid on the surface of mineral aerosols. The signature of biomass burning at WO was found to be associated with black carbon as well as the accumulation of potassium and oxalate in the fine particles.
Effects of spectrometer band pass, sampling, and signal‐to‐noise ratio on spectral identification using the Tetracorder algorithm
Authors: Swayze Gregg A. , Clark Roger N. , Goetz Alexander F. H. , Chrien Thomas G. , Gorelick Noel S.
Published: September 2003

Estimates of spectrometer band pass, sampling interval, and signal‐to‐noise ratio required for identification of pure minerals and plants were derived using reflectance spectra convolved to AVIRIS, HYDICE, MIVIS, VIMS, and other imaging spectrometers. For each spectral simulation, various levels of random noise were added to the reflectance spectra after convolution, and then each was analyzed with the Tetracorder spectral identification algorithm [Clark et al., 2003]. The outcome of each identification attempt was tabulated to provide an estimate of the signal‐to‐noise ratio at which a given percentage of the noisy spectra were identified correctly. Results show that spectral identification is most sensitive to the signal‐to‐noise ratio at narrow sampling interval values but is more sensitive to the sampling interval itself at broad sampling interval values because of spectral aliasing, a condition when absorption features of different materials can resemble one another. The band pass is less critical to spectral identification than the sampling interval or signal‐to‐noise ratio because broadening the band pass does not induce spectral aliasing. These conclusions are empirically corroborated by analysis of mineral maps of AVIRIS data collected at Cuprite, Nevada, between 1990 and 1995, a period during which the sensor signal‐to‐noise ratio increased up to sixfold. There are values of spectrometer sampling and band pass beyond which spectral identification of materials will require an abrupt increase in sensor signal‐to‐noise ratio due to the effects of spectral aliasing. Factors that control this threshold are the uniqueness of a material's diagnostic absorptions in terms of shape and wavelength isolation, and the spectral diversity of the materials found in nature and in the spectral library used for comparison. Array spectrometers provide the best data for identification when they critically sample spectra. The sampling interval should not be broadened to increase the signal‐to‐noise ratio in a photon‐noise‐limited system when high levels of accuracy are desired. It is possible, using this simulation method, to select optimum combinations of band‐pass, sampling interval, and signal‐to‐noise ratio values for a particular application that maximize identification accuracy and minimize the volume of imaging data.
Possible identification of local deposits of Cl2SO2 on Io from NIMS/Galileo spectra
Authors: Schmitt B. , Rodriguez S.
Published: September 2003

Starting from the recent discovery of chlorine ions in Io's plasma torus, we searched for evidence of Cl‐bearing species at the surface of the satellite. We have identified Cl2SO2, with possible contribution by ClSO2, as candidates for the absorber(s) of the 3.92 μm band locally present in NIMS/Galileo spectra of the reddish deposits south of Marduk's volcanic center. Low‐temperature laboratory measurements of the infrared spectra of several Cl and S‐bearing molecules in the solid state, coupled with radiative transfer modeling, first allowed us to select four candidate molecules. Their abundance and stability at Io's surface have been tested through formation, condensation, and destruction scenarios using volcanic and atmospheric models completed with chemical and thermodynamical data. In particular, the sublimation rates of solid Cl2SO2 and SO2 have been measured to study the selective condensation of these species. Cl2SO2 diluted at ∼1% in a millimeter thick layer of solid SO2 is the favorite candidate for the 3.92 μm band. We strongly favor a formation process of this molecule by heterogeneous reaction of Cl atoms on SO2 ice condensing on plume particles or at Io's surface. The high Cl2SO2 abundance observed implies that a Cl‐rich volcanic eruption ([Cl − (Na + K)]/S > 0.015) occurred at Marduk. ClSO2 is a potential additional contributor to the band. Pure H2S is safely discarded as it is extremely unstable at Io's surface but an upper limit of 0.01% is derived for H2S diluted in SO2. Finally, chemical constraints allow us to firmly exclude H2S2. We also suggest that Cl2S may be an alternative explanation for the reddish coloration of some volcanic deposits.