bluuebunny/crossref_metadata_2025 huggingface dataset:
Socialized Personality, Scholastic Aptitudes, Study Habits, and Academic Achievement: Exploring the Link
Authors: Aluja Anton , Blanch Angel
Published: July 2004

Summary: This study analyzed the relationships among Cattellian personality factors, scholastic aptitudes, study habits, and academic achievement. A total of 887 volunteer students from primary education (453 males and 434 females), enrolled in 29 public schools, participated in this research. It was found that the scholastic aptitudes were the most predictive variables of achievement, while the personality traits had a low direct contribution to academic achievement, although the students with higher scores on socialized personality traits showed better study habits than those students with lower scores on personality socialization traits. The relationship between personality and academic achievement seems to be mediated by study habits. Moreover, females obtained higher academic achievement scores than males. These differences could be explained by the fact that females showed a more socialized personality pattern and better study habits.
The Traits Personality Questionnaire 5 (TPQue5)
Authors: Tsaousis Ioannis , Kerpelis Ploutarxos
Published: July 2004

Abstract: Researchers and practitioners alike increasingly seek short, reliable, and valid measures in order to evaluate personality structure. This paper outlines the development of a short form of a full-length personality questionnaire. The Traits Personality Questionnaire 5 (TPQue5) consists of 75 statements measuring the Big Five dimensions (Neuroticism, Extraversion, Agreeableness, Conscientiousness, and Openness to Experience) in addition to 26 statements evaluating social desirability responses. In order to elicit the 75 items, principal components analysis was performed on the scores of 1054 individuals from the normative sample. Reliability and validity data was collected on a new sample of 735 university students. Like the Traits Personality Questionnaire (TPQue), the TPQue5 factor scales displayed excellent internal consistency, and good test-retest reliability. Convergent and discriminant validation of the TPQue5 was demonstrated through comparison with other personality measures, while the analysis of the factorial structure of the test justified its concordance with the long form. The psychometric results of this study indicate that the TPQue5 is a reliable and valid measure, which can be used for a brief description and evaluation of personality.
Effects of Practice and Intellectual Growth on Performance on the Swedish Scholastic Aptitude Test (SweSAT)
Authors: Cliffordson Christina
Published: July 2004

Summary: The purpose of the study is to examine effects of repeated test taking over several sessions on the Swedish Scholastic Aptitude Test (SweSAT). Self-selection effects on test performance due to background variables that must be taken into consideration are also investigated. All test repeaters with two and three test scores from three cohorts are included in the study. By using different regression models a distinction can be made between the effects of practice as a function of test-taking experience, and the effects of growth as a function of time. The results show self-selection effects due to age and grades, such that students with higher grades tend to be younger when taking the first test. Furthermore, this phenomenon tends to be more accentuated with repeated test takings. It is also shown that there are score gains as a function of practice at the first testing session, and that there are also effects of growth on the SweSAT performance. The magnitude of score gains associated with growth is equal over the two intervals measured, but different between the three cohorts. There are reasons to assume that effects of schooling may explain these differences. An additional explanation may be that the younger students have a greater potential for growth.
A Validation and Psychometric Examination of the Arnett Inventory of Sensation Seeking (AISS) in German Adolescents1
Authors: Roth Marcus , Herzberg Philipp Yorck
Published: July 2004

Summary: The present study examines the reliability (internal consistency) and the the factorial validity, as well as the construct validity and the criterion-oriented validity (criterion: Delinquent behavior) of the Arnett Inventory of Sensation Seeking (AISS; Arnett, 1994 ). The study analyzed a sample of German adolescents aged 14 to 16 years (N = 1236) who, in addition to the AISS, also completed the NEO-Five Factor Inventory (NEO-FFI) and the subscale Delinquent Behavior of the Youth Self-Report (YSR). The results, indeed, confirm the hypothesized two-factor structure of the AISS (novelty vs. intensity of stimulation), however, as indicated by modification indices and standardized expected parameter chances, some items had to be excluded from the model to provide an adequate fit for the data. Nevertheless, the internal consistencies of the shortened two-factor scale are considerably low, ranging from .46 to .58. As an index of construct validity, males scored higher than females on both the Intensity subscale and the Total scale. Correlation with the scales of the NEO-FFI revealed that the convergent and discriminant validities of the AISS-scales were quite satisfying. Indications of criterion-oriented validity were obtained by prediction of delinquent behavior (setting fire, stealing, and playing truant) using the Intensity subscale. On the whole, the results yielded sufficient support for the validity of the AISS, while pointing to certain desirable modifications.
Physical oceanographic conditions during GasEx‐2001
Authors: Johnson Gregory C. , Sabine Christopher L. , McTaggart Kristene E. , Hummon Julia M.
Published: July 2004

GasEx‐2001 is a study of air‐sea gas exchange in a region of CO2 outgassing. The bulk of the experiment followed a drifting array of near‐surface instruments deployed during the second half of February 2001 just south of the equator in the central Pacific Ocean. Physical oceanographic conditions including local currents, the seasonal cycle, Kelvin waves, and tropical instability waves are described using shipboard data and a variety of other data sources to set the large‐scale oceanographic context for GasEx‐2001. Local physical oceanographic conditions during GasEx‐2001 are then analyzed using shipboard data and a simple one‐dimensional mixed layer model. The thermocline shoals about 13 m over the 15‐day experiment, implying an upwelling rate of 1 × 10−5 m s−1. Zonal velocity is surface‐intensified and westward, with vertical shear mostly through the thermocline. Meridional velocity is also strongly sheared with a maximum equatorward flow in the thermocline that is much reduced by 17‐m depth. The mixed layer model exhibits more near‐surface warming over the course of the experiment than is observed. Prescribing upwelling in the model closes the heat budget within error estimates. Entrainment at the base of the mixed layer plays a limited role in the mixed layer budgets of carbon and other water properties. Vertical shear of horizontal velocity within the mixed layer and slippage of the array through the surface water also have small (but uncertain) roles in these budgets.
Air‐sea gas transfer in the Southern Ocean
Authors: Wanninkhof Rik , Sullivan Kevin F. , Top Zafer
Published: July 2004

Gas transfer velocities were determined in the Southern Ocean during the Southern Ocean Iron Fertilization experiment (SOFex) using the dual deliberate tracer technique. The decrease of the purposefully injected tracers, sulfur hexafluoride and helium‐3, could be well described by gas exchange parameterizations with wind speed that satisfy global constraints based on bomb‐14C uptake. The concentration decrease of tracers could be predicted slightly better with established relationships if gas transfer was modeled as a function of the cube rather than the square of the wind speed, particularly over a time interval with high and variable winds. However, both fits can model the concentration decrease within the uncertainty of the observations. This suggests that it will be singularly difficult to definitively determine if a quadratic or cubic dependence of gas exchange with wind is more appropriate based on deliberate tracer measurements. However, these results show that gas exchange rates in the Southern Ocean are not anomalous when compared with the rest of the ocean. Thus this cannot account for discrepancy between observational and model‐based estimates of uptake of CO2 in the Southern Ocean. Using a high‐quality wind speed field obtained from the QuikSCAT satellite Seawinds scatterometer and an established surface water pCO2 climatology, the CO2 uptake in the Southern Ocean (>34°S) is reassessed. The total uptake rates are similar to previous observation‐based estimates, but the analysis shows that the uptake rate is sensitive to wind speed product used and the wind speed distribution.
Evaluation of the National Oceanic and Atmospheric Administration/Coupled‐Ocean Atmospheric Response Experiment (NOAA/COARE) air‐sea gas transfer parameterization using GasEx data
Authors: Hare Jeffrey E. , Fairall Christopher W. , McGillis Wade R. , Edson James B. , Ward Brian , Wanninkhof Rik
Published: July 2004

During the two recent GasEx field experiments, direct covariance measurements of air‐sea carbon dioxide fluxes were obtained over the open ocean. Concurrently, the National Oceanic and Atmospheric Administration/Coupled‐Ocean Atmospheric Response Experiment air‐sea gas transfer parameterization was developed to predict gas transfer velocities from measurements of the bulk state of the sea surface and atmosphere. The model output is combined with measurements of the mean air and sea surface carbon dioxide fugacities to provide estimates of the air‐sea CO2 flux, and the model is then tuned to the GasEx‐1998 data set. Because of differences in the local environment and possibly because of weaknesses in the model, some discrepancies are observed between the predicted fluxes from the GasEx‐1998 and GasEx‐2001 cases. To provide an estimate of the contribution to the air‐sea flux of gas due to wave‐breaking processes, the whitecap and bubble parameterizations are removed from the model output. These results show that moderate (approximately 15 m s−1) wind speed breaking wave gas transfer processes account for a fourfold increase in the flux over the modeled interfacial processes.
Effects of wind speed and gas exchange parameterizations on the air‐sea CO2 fluxes in the equatorial Pacific Ocean
Authors: Feely R. A. , Wanninkhof R. , McGillis W. , Carr M.‐E. , Cosca C. E.
Published: July 2004

During the recent GasEx‐2001 cruise in the Equatorial Pacific aboard the NOAA ship Ronald H. Brown, carbon measurements were made in the region of 3°S, 125°W. Continuous surface water fCO2 measurements were conducted onboard in both underway and discrete analysis modes. During the 15‐day experiment, surface water fCO2 values averaged 473 ± 2 μatm, providing a constant condition of supersaturation and flux of CO2 from the ocean to the atmosphere. The relationship of gas transfer with wind speed developed in this study is used along with regional estimates of air‐water fCO2 differences to determine CO2 fluxes in the equatorial Pacific. The regional fCO2 fields are estimated from algorithms developed from previous measurements collected on the Ronald H. Brown and Ka'imimoana over the past 10 years between 5°N and 10°S, 90°W and 165°E. Using the W. McGillis et al. gas transfer‐wind speed relationship, we estimate an average flux of 1.5 ± 0.4 mol C m−2 yr−1 for the study region, with a six‐fold difference in the regional efflux of CO2 between the strong El Niño events of 1986–1987 and 1997–1998 and the La Niña events of 1996 and 1999–2001 (i.e., 0.1 to 0.56 Pg C yr−1). The combined effects of uncertainties in the gas transfer velocity and wind fields lead to average difference of 27% between the lowest and highest estimates of the CO2 flux from the region. In contrast, the uncertainties in the fCO2‐SST relationships give an average difference of about 35% between the lowest and highest estimates of the CO2 flux.
Transport and modification processes of dense shelf water revealed by long‐term moorings off Sakhalin in the Sea of Okhotsk
Authors: Fukamachi Yasushi , Mizuta Genta , Ohshima Kay I. , Talley Lynne D. , Riser Stephen C. , Wakatsuchi Masaaki
Published: July 2004

The region off the east coast of Sakhalin is thought of as an important pathway of dense shelf water (DSW) from its production region in the northwestern Okhotsk Sea to the southern Okhotsk Sea. From July 1998 to June 2000, the first long‐term mooring experiment was carried out in this region to observe the southward flowing East Sakhalin Current (ESC) and DSW. Moored and associated hydrographic data show considerable modification of cold dense water via mixing with warm offshore water in the slope region off northern Sakhalin. Significant onshore eddy heat flux was observed at the northernmost mooring (54.9°N), which suggests the occurrence of baroclinic instability. The eddy heat flux was not significant farther south. At moorings along 53°N, cold anticyclonic eddies were identified that were consistent with isolated eddies seen in the hydrographic data. The three years of hydrographic data also showed large differences in extent and properties of DSW. Furthermore, the mooring data show that seasonal variability of DSW was quite different in the two years. The average DSW transport for σθ > 26.7 evaluated using the moored data at 53°N for 1 year (1998–1999) was ∼0.21 Sv (= 106 m3 s−1). This value is at the lower end of the previous indirect estimates. Along with the DSW modification, this transport estimate indicates that DSW was not only carried southward by the ESC but was spread offshore by eddies off northern Sakhalin.
Cloud‐to‐ground lightning and cloud top brightness temperature over the contiguous United States
Authors: Molinie G. , Jacobson A. R.
Published: July 2004

This study analyzes cloud top brightness temperature (CTBT) and cloud‐to‐ground (CG) lightning stroke densities over the continental United States from May to October 1999. The good coverage of the study period and the large number of colocated stroke densities and CTBTs provide robust statistics. Prior studies have reported nonlinear lightning flash rate increase with cloud depth. In this work, some support is found for such relationships, in the particular case of CG strokes. The likelihood of CG stroke occurrence and of high CG stroke density is higher if CTBTs are among the coldest. However, a monthly and regional analysis of CTBT/stroke density correspondences reveals quasi‐constant overall stroke densities for CTBTs warmer than about −55°C (most of the CTBT/stroke density samples). Overall stroke densities increase as CTBT decreases only for CTBTs colder than about −55°C. This is consistent with a statistical but not instantaneous lightning flash rate/cloud depth relationship. Thus the number of ±CG strokes per CG‐producing cloud top surface area per hour, integrated over monthly periods in each geographical region, is approximately constant versus time depending only on the region.
Aerosol–cloud drop concentration closure in warm cumulus
Authors: Conant W. C. , VanReken T. M. , Rissman T. A. , Varutbangkul V. , Jonsson H. H. , Nenes A. , Jimenez J. L. , Delia A. E. , Bahreini R. , Roberts G. C. , Flagan R. C. , Seinfeld J. H.
Published: July 2004

Our understanding of the activation of aerosol particles into cloud drops during the formation of warm cumulus clouds presently has a limited observational foundation. Detailed observations of aerosol size and composition, cloud microphysics and dynamics, and atmospheric thermodynamic state were collected in a systematic study of 21 cumulus clouds by the Center for Interdisciplinary Remotely‐Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft during NASA's Cirrus Regional Study of Tropical Anvils and Cirrus Layers–Florida Area Cirrus Experiment (CRYSTAL‐FACE). An “aerosol‐cloud” closure study was carried out in which a detailed cloud activation parcel model, which predicts cloud drop concentration using observed aerosol concentration, size distribution, cloud updraft velocity, and thermodynamic state, is evaluated against observations. On average, measured droplet concentration in adiabatic cloud regions is within 15% of the predictions. This agreement is corroborated by independent measurements of aerosol activation carried out by two cloud condensation nucleus (CCN) counters on the aircraft. Variations in aerosol concentration, which ranged from 300 to 3300 cm−3, drives large microphysical differences (250–2300 cm−3) observed among continental and maritime clouds in the South Florida region. This is the first known study in which a cloud parcel model is evaluated in a closure study using a constraining set of data collected from a single platform. Likewise, this is the first known study in which relationships among aerosol size distribution, CCN spectrum, and cloud droplet concentration are all found to be consistent with theory within experimental uncertainties much less than 50%. Vertical profiles of cloud microphysical properties (effective radius, droplet concentration, dispersion) clearly demonstrate the boundary layer aerosol's effect on cloud microphysics throughout the lowest 1 km of cloud depth. Onboard measurements of aerosol hygroscopic growth and the organic to sulfate mass ratio are related to CCN properties. These chemical data are used to quantify the range of uncertainty associated with the simplified treatment of aerosol composition assumed in the closure study.
PHOBEA/ITCT 2002 airborne observations of transpacific transport of ozone, CO, volatile organic compounds, and aerosols to the northeast Pacific: Impacts of Asian anthropogenic and Siberian boreal fire emissions
Authors: Bertschi I. T. , Jaffe D. A. , Jaeglé L. , Price H. U. , Dennison J. B.
Published: July 2004

During the spring of 2002, vertical profiles of O3, CO, nonmethane volatile organic compounds (VOCs), and total aerosol scattering were collected over the northwestern coast of Washington State as part of the University of Washington's Photochemical Ozone Budget of the Eastern North Pacific Atmosphere (PHOBEA) research campaign. These observations coincided with NOAA's Intercontinental Transport and Chemical Transformation 2002 (NOAA‐ITCT 2K2) project. Thirteen research flights were conducted from 29 March through 23 May and several well‐defined polluted layers of varying thickness (∼0.2 to >3 km) were observed at altitudes between 0 and 6 km. These layers were characterized by correlated enhancements of O3, CO, VOCs, and particles. We observed rapid transpacific transport of polluted air masses on 15 April and 14, 17, and 23 May 2002, with ΔO3and ΔCO (where Δ refers to the enhancement over background) exceeding 30 and 60 ppbv, respectively, and total aerosol scattering of green light (“σsp (550 nm)”) exceeding 65 Mm−1. These episodes were efficient in transporting O3to the northeast (NE) Pacific troposphere, with ΔO3/ΔCO ratios in the pollution layers varying from 0.22 to 0.42 mol mol−1. In contrast, the average Δσsp (550 nm)/ΔCO ratio of the mid‐May events (0.66 ± 0.21 (1σ)) was more than twice that of the 15 April event (0.32 ± 0.05). The correlation between O3, CO, aerosols, and VOCs coupled with back‐trajectory analyses, satellite data, and the GEOS‐CHEM global chemical transport model indicate that the primary source of pollution observed on 15 April originated from a mixture of Asian anthropogenic and biomass‐burning emissions. For the May events, our analyses indicate that the early onset of the 2002 Siberian fire season was a significant source of the pollution episodes observed in May.
Regional drainage of meltwater beneath a Hesperian‐aged south circumpolar ice sheet on Mars
Authors: Ghatan Gil J. , Head James W.
Published: July 2004

Five sinuous valleys that begin near the margins of the Hesperian‐aged Dorsa Argentea Formation (DAF) are examined using Mars Global Surveyor Mars Orbiter Laser Altimeter data. These valleys are carved into the surrounding Noachian cratered terrain and extend away from the DAF for lengths up to 1600 km before terminating in the Argyre basin 1–3 km below their starting elevations. The association of these valleys with the DAF, thought to be the volatile‐rich deposits of a previously widespread circumpolar ice sheet, supports the scenario whereby the valleys formed contemporaneously with the DAF and served as conduits for drainage of meltwater associated with the melting and retreat of the ice sheet. Examination of the head regions of three of the valleys reveals pits and basins carved into the local deposits of the DAF closely associated with the valley heads. On the basis of the distribution of these pits and basins, their morphologies, size, spacing, and basal elevations similar to the nearby valleys, we conclude that the pits and basins represent the expression of the valleys within the DAF. We suggest that the pits and basins resulted from surface collapse of the deposits due to basal drainage of meltwater beneath the thinning ice sheet. Sinuous ridges within some of the basins appear similar to terrestrial eskers and further support this scenario.
Predictive pore‐scale modeling of two‐phase flow in mixed wet media
Authors: Valvatne Per H. , Blunt Martin J.
Published: July 2004

We show how to predict flow properties for a variety of porous media using pore‐scale modeling with geologically realistic networks. Starting with a network representation of Berea sandstone, the pore size distribution is adjusted to match capillary pressure for different media, keeping the rank order of pore sizes and the network topology fixed. Then predictions of single and multiphase properties are made with no further adjustment of the model. We successfully predict relative permeability and oil recovery for water wet, oil wet, and mixed wet data sets. For water flooding we introduce a method for assigning contact angles to match measured wettability indices. The aim of this work is not simply to match experiments but to use easily acquired data to predict difficult to measure properties. Furthermore, the variation of these properties in the field, due to wettability trends and different pore structures, can now be predicted reliably.
Water markets as a vehicle for reforming water resource allocation in the Murray‐Darling Basin of Australia
Authors: Crase Lin , Pagan Phil , Dollery Brian
Published: July 2004

Water trade and the establishment of water markets continue to gain popularity among legislators as a vehicle for progressing the reform of the water resources sector in Australia. This has manifested itself at the most recent meeting of the Council of Australian Governments, where a range of changes to address the declining health of inland rivers included the strengthening of water property rights. These views appear to be premised on the belief that nonattenuated water rights are a prerequisite for maximizing the productive benefits of water and are broadly in line with notions often derived from neoclassical market theory. However, in spite of the apparent faith in the market mechanism, there is a growing literature illustrating the limitations of the market framework in the context of water resource management. Accordingly, there would appear to be grounds for a more cautious approach that recognizes the potential for market failures to emerge. This article explores the present growth of water markets and the legislative background that circumscribes them in the Murray‐Darling Basin. Recognizing the constraints imposed by the status quo, this study then examines the implications of stronger property rights for entitlement holders and the use of water markets in the context of the goals assigned to Australian water managers.
Political economy of water pricing policy: Empirical evidence from public utilities in Mauritius
Authors: Madhoo Yeti Nisha
Published: July 2004

This paper examines whether political economy considerations are important in the formulation of water pricing policy in Mauritius. Empirical models are developed incorporating current and lagged electoral years as dummy variables in order to test whether politicians make strategic use of water pricing policy to further their partisan electoral objectives. Political economy concerns are also included into our analysis by looking at the impact of lobby groups on the implementation of water prices. In the case of potable water prices, a disaggregated analysis according to consumer categories provides weak evidence of political manipulation. However, political manipulation is established in terms of subsidy allocations to the residential sector, which is the largest consumer category. As regards irrigation water, the results lend support to the contention that political parties indeed manipulate irrigation subsidies allocated to the Irrigation Authority. Evidence on the lobby effect emerges from our empirical analysis on potable water. More specifically, we find that smaller groups have successfully been able to use their political influence to obtain smaller water price increases.
The 2003 North American electrical blackout: An accidental experiment in atmospheric chemistry
Authors: Marufu Lackson T. , Taubman Brett F. , Bloomer Bryan , Piety Charles A. , Doddridge Bruce G. , Stehr Jeffrey W. , Dickerson Russell R.
Published: July 2004

The August 2003 North American electrical blackout provided a unique opportunity to quantify directly the contribution of power plants to regional haze and O3. Airborne observations over central Pennsylvania on August 15, 2003, ∼24 h into the blackout, revealed large reductions in SO2 (>90%), O3 (∼50%), and light scattered by particles (∼70%) relative to measurements outside the blackout region and over the same location when power plants were operating normally. CO and light absorbing particles were unaffected. Low level O3 decreased by ∼38 ppbv and the visual range increased by >40 km. This clean air benefit was realized over much of the eastern U.S. Reported SO2 and NOx emissions from upwind power plants were down to 34 and 20% of normal, respectively. The improvement in air quality provides evidence that transported emissions from power plants hundreds of km upwind play a dominant role in regional haze and O3 production.
Optical properties of Saharan dust layers as detected by a Raman lidar at Thessaloniki, Greece
Authors: Balis D. S. , Amiridis V. , Nickovic S. , Papayannis A. , Zerefos C.
Published: July 2004

Measurements during Saharan dust transport events were performed at several stations of the European Aerosol Research Lidar Network. During the period 2001–2002, 12 cases were captured at Thessaloniki, Greece (40.5°N, 22.9°E) with a 355 nm Raman lidar. For these cases the vertical profiles of the extinction and backscatter coefficients were determined and examined, as well as profiles of extinction‐to‐backscatter ratio (lidar ratio) and the backscatter‐related Ångström exponent between 355 and 532 nm (color index). Model calculations from the DREAM model confirmed the existence of Saharan dust in all cases examined. Within the dust plumes the lidar ratios ranged from 20 to 100 sr and the color index ranged from −1 to 3. An anticorrelation was found between the lidar ratio and the color index during the Saharan dust events. In certain cases the results suggest that the mixing of dust particles with boundary layer aerosols reduces the dust ‘signature’ and thus, makes difficult the separation of the dust particles from those of mostly urban origin.
Production and detection of hydrated cluster ions in laboratory plasma mimicking ionospheric D region
Authors: Sinha H. S. S. , Tokuyama Y. , Oyama K.‐I. , Watanabe S.
Published: July 2004

A mixture of NO and water vapor was ionized inside a chamber using an EUV source to produce cluster ions. Ion‐cluster formation started within a minute but the time for attaining peak concentration for different ions varied from 1 min to 40 min. New findings here are (a) the detection of higher order clusters of proton and NO+ hydrates (109+, 127+ and 102+) and (b) that the concentration of most of the hydrated ions showed oscillatory behavior. Other positive ions detected were 33+, 54+, 66+, 71+, 76+, 83+, 86+, 93+, 94+, 112+, 117+, 131+ (with high concentration) and 19+, 29+ and 37+ (with low concentrations). Effect of lower and upper thresholds of chamber pressure, for the production of cluster ions was observed. These pressure thresholds correspond to an altitude range of 50 to 100 km in the ionosphere, where cluster ions have been observed.
Evidence for bimodal particle distribution from the spectra of polar mesospheric clouds
Authors: Carbary J. F. , Morrison D. , Romick G. J.
Published: July 2004

The spectrographic imagers on the MSX satellite have made the first observations of the middle ultraviolet spectra (200–315 nm) of polar mesospheric clouds (PMCs). Dividing the PMC spectra by the solar spectrum yields a scattering spectrum expressible as a matrix‐vector formalism of Mie scattering functions and the particle distribution. Using this formalism, PMC particle distributions are related to the observed scattering spectrum. The scattering spectrum always exhibits a peculiar “hump” at ∼260 nm that cannot be explained by any effect other than the particle distribution. A lognormal distribution of small particles (mode ∼ 50 nm) produces the overall shape of the spectrum but not the “hump.” Although not unique, a simple bimodal distribution of small particles (r ∼ 50 nm) and large particles (r ∼ 200 nm) describes the scattering spectrum and its hump very well. The clouds may therefore consist of two different populations, as suggested by some models of the clouds. Numerically, smaller particles dominate by about 10:1, but the larger particles strongly influence the scattering spectrum.
High‐accuracy zenith delay prediction at optical wavelengths
Authors: Mendes V. B. , Pavlis E. C.
Published: July 2004

A major limitation in accuracy in modern satellite laser ranging is the modeling of atmospheric refraction. Recent improvements in this area include the development of mapping functions to project the atmospheric delay experienced in the zenith direction to a given elevation angle. In this paper, we derive zenith delay models from revised equations for the computation of the refractive index of the atmosphere, valid for a wide spectrum of optical wavelengths. The zenith total delay predicted with these models were tested against ray tracing through radiosonde data from a full year of data, for 180 stations distributed worldwide, and showed sub‐millimeter accuracy for wavelengths ranging from 0.355 μm to 1.064 μm.
Preliminary observations of global ocean mass variations with GRACE
Authors: Chambers Don P. , Wahr John , Nerem R. Steven
Published: July 2004

Monthly estimates of the Earth's gravitational field from the GRACE mission are used to construct a time‐series of global mean ocean mass variations between August 2002 and December 2003. This time‐series is compared to a mean climatology determined from satellite altimeter measurements of global mean sea level corrected for the steric variation. The GRACE observations show a seasonal exchange of water mass with the continents of the same magnitude (∼8.5 mm) and phase (maximum in early‐ to mid‐October) as the steric‐corrected altimetry. This is one of the first direct validations over the ocean of the primary GRACE science mission to measure time‐variable transports of water mass in the Earth system, and it suggests that GRACE data can be used to measure non‐steric mean sea level variations which is important for climate change studies.
A validation of the cloud parameterization in the regional model SN‐REMO
Authors: Meinke Insa , von Storch Hans , Feser Frauke
Published: July 2004

The cloud parameterization in the regional atmospheric model SN‐REMO (Spectrally Nudged Regional Model) was validated using satellite data from the ISCCP (International Satellite Cloud Climatology Project). There is an overall good agreement between the cloudiness of SN‐REMO and ISCCP in terms of temporal and spatial means. However, with further investigation a deficiency was localized regarding the simulation of cloud amount: Too many clouds are simulated. This overestimation occurs especially during the night. It is connected with a poor simulation of the cloud diurnal cycle. Clouds at low‐level emissivity heights (1000–475 hPa) are causing this overestimation. The magnitude of the overall overestimation is also affected by the underestimation of simulated cloud amount at high‐level emissivity heights (<475 hPa) and its diurnal variation. The overestimation of the simulated cloud amount is caused by subgrid‐scale cloudiness. Since the simulation of subgrid‐scale clouds in the regional model SN‐REMO is described by a relative humidity parameterization, these deficiencies are connected with this parameterization.
A “triple sea‐ice state” mechanism for the abrupt warming and synchronous ice sheet collapses during Heinrich events
Authors: Kaspi Yohai , Sayag Roiy , Tziperman Eli
Published: July 2004

Abrupt, switch‐like, changes in sea ice cover are proposed as a mechanism for the large‐amplitude abrupt warming that seemed to have occurred after each Heinrich event. Sea ice changes are also used to explain the colder‐than‐ambient glacial conditions around the time of the glacier discharge. The abrupt warming events occur in this mechanism, owing to rapid sea ice melting which warmed the atmosphere via the strong sea ice albedo and insulating feedbacks. Such abrupt sea ice changes can also account for the warming observed during Dansgaard‐Oeschger events. The sea ice changes are caused by a weak (order of 5 Sv) response of the thermohaline circulation (THC) to glacier discharges. The main point of this work is therefore that sea ice may be thought of as a very effective amplifier of a weak THC variability, explaining the abrupt temperature changes over Greenland. Synchronous ice sheet collapses from different ice sheets around the North Atlantic, indicated by some proxy records, are shown to be possible via the weak coupling between the different ice sheets by the atmospheric temperature changes caused by the sea ice changes. This weak coupling can lead to a “nonlinear phase locking” of the different ice sheets which therefore discharge synchronously. It is shown that the phase locking may also lead to “precursor” glacier discharge events from smaller ice sheets before the Laurentide Ice Sheet discharges. The precursor events in this mechanism are the result rather than the cause of the major glacier discharges from the Laurentide Ice Sheet.
Calculation of converged rovibrational energies and partition function for methane using vibrational–rotational configuration interaction
Authors: Chakraborty Arindam , Truhlar Donald G. , Bowman Joel M. , Carter Stuart
Published: July 2004

The rovibration partition function of CH4 was calculated in the temperature range of 100–1000 K using well-converged energy levels that were calculated by vibrational–rotational configuration interaction using the Watson Hamiltonian for total angular momenta J=0–50 and the MULTIMODE computer program. The configuration state functions are products of ground-state occupied and virtual modals obtained using the vibrational self-consistent field method. The Gilbert and Jordan potential energy surface was used for the calculations. The resulting partition function was used to test the harmonic oscillator approximation and the separable-rotation approximation. The harmonic oscillator, rigid-rotator approximation is in error by a factor of 2.3 at 300 K, but we also propose a separable-rotation approximation that is accurate within 2% from 100 to 1000 K.
Atomistic mechanisms for the (1×1)⇌hex surface phase transformations of Pt(100)
Authors: van Beurden P. , Kramer G. J.
Published: July 2004

The atomistic mechanisms and dynamics of the (1×1)→hex surface reconstruction of the clean Pt(100) and its lifting upon CO adsorption have been studied by means of both density functional theory and molecular dynamics simulations based on the modified embedded-atom method. It was found that during the surface reconstruction from the square (1×1) to the ∼20% more dense (quasi)hexagonal phase, the required extra atoms are extracted from the second layer, leaving highly mobile subsurface vacancies, even in the presence of adatom islands or steps. These vacancies will, by surface diffusion, coalesce to form steps. In contrast, during the reverse process—where the hex surface reconstruction is lifted upon adsorption of CO—the roughly 20% excess surface atoms are in a collective manner ejected to form chains of adatoms. In turn, these adatoms coalesce into islands and steps by surface diffusion. A result of the two totally different mechanisms is that the reconstruction process can be concluded not to be the reverse of the deconstruction process.
Thermodynamics of soft anisotropic contact lines
Authors: Rey Alejandro D.
Published: July 2004

Contact lines arising from the intersection of interfaces between liquids and nematic liquid crystals are representative models of soft anisotropic contact lines. This paper presents the thermodynamics of soft anisotropic contact lines and the derivation of the one dimensional (1D) Gibbs–Duhem adsorption equation. Consistency between the 1D Gibbs–Duhem equation and the classical equations of lineal nematostatics is shown. Using a phase space that takes into account thermodynamics, liquid crystalline order, and geometric variables, the generalized nematic line Gibbs–Duhem equation reveals the presence of couplings between curvature, torsion, adsorption, temperature, and average molecular orientation. Merging the thermodynamic analysis with nematostatics results in a model for contact line shape and orientation selection. The ability of an adsorbed solute to orient the director and to bend and twist the contact line is predicted. The thermodynamic origin of preferred orientation at a straight contact line is established.
Photodissociation of ICN at the liquid/vapor interface of water
Authors: Winter Nicole , Benjamin Ilan
Published: July 2004

The photodissociation of ICN adsorbed at the liquid/vapor interface of water is studied using classical molecular dynamics with nonadiabatic surface hopping. The cage escape, geminate recombination to form ICN and INC and the subsequent vibrational relaxation of these two molecules (on their ground electronic states) is compared with the same process in bulk water and with previous photodissociation studies at liquid interfaces. We find that the reduced surface density and weaker solvent-solute interactions give rise to reduced rate of nonadiabatic transitions and that the probability for cage escape at the interface is significantly enhanced due to the possibility that one or both of the photodissociation fragments desorb into the gas phase. The overall desorption probability varies from 75% to 92% for ICN initially located just below the Gibbs surface (50% bulk density) to ICN located just above the Gibbs surface, respectively. The corresponding geminate recombination probabilities are 18% and 9%, respectively. The vibrational relaxation rate of the recombined ICN is slower than in the bulk by a factor of 2.3.
Motion of spheres along a fluid-gas interface
Authors: Cichocki Bogdan , Ekiel-Jeżewska Maria L. , Nägele Gerhard , Wajnryb Eligiusz
Published: July 2004

A system of many spherical particles, suspended in a quiescent fluid and touching a planar free fluid-gas interface, is considered. Stick fluid boundary conditions at the sphere surfaces are assumed. The free surface boundary conditions are taken into account with the use of the method of images. For such a quasi-two-dimensional system, the one-sphere resistance operator is calculated numerically. Moreover, the corresponding friction and mobility tensors are constructed from irreducible multipole expansion. Finally, the long-distance terms of the two-sphere mobility tensor are evaluated explicitly up to the order of 1/r3, where r is the interparticle distance. Experiments which have motivated this work are outlined.
The essential role of H-F substitution in the electron-phonon interactions and electron transfer in the negatively charged acenes
Authors: Kato Takashi , Yamabe Tokio
Published: July 2004

The single charge transfer through acenes, partially H-F substituted acenes, and fluoroacenes is discussed. The reorganization energies between the neutral molecules and the corresponding monoanions for partially H-F substituted acenes lie between those for acenes and fluoroacenes. The delocalization of the lowest unoccupied molecular orbitals (LUMO) by substituting hydrogen atoms by fluorine atoms with the highest electronegativity in every element is the main reason why the reorganization energy between the neutral molecule and the monoanion for partially H-F substituted acenes lies between those for acenes and fluoroacenes. This result implies that the negatively charged partially H-F substituted acenes would be better conductors with rapid electron transfer than the negatively charged fluoroacenes if we assume that the overlap of the LUMO between partially H-F substituted acenes is not significantly different from that between two neighboring fluoroacenes. The structures of the monoanions of acenes, fluoroacenes, and partially H-F substituted acenes are optimized under D2h geometry, and the Jahn-Teller effects in the monoanions of benzene and fluorobenzene are discussed. The vibration effect onto the charge transfer problem is also discussed. The C-C stretching modes around 1500 cm−1 are the main modes converting the neutral molecules to the monoanions in acenes, fluoroacenes, and partially H-F substituted acenes. It can be confirmed from the calculational results that the C-C stretching modes around 1500 cm−1 the most strongly couple to the LUMO in these molecules. The main reason why the total electron-phonon coupling constants (lLUMO) for the monoanions of acenes in which four outer hydrogen atoms are substituted by fluorine atoms are larger than those for the monoanions of acenes in which several inner hydrogen atoms are substituted by fluorine atoms is suggested. The relationships between the electron transfer and the electron-phonon interactions are discussed. The plot of the reorganization energies against the lLUMO values is found to be nearly linear. In view of these results, the relationships between the normal and superconducting states are briefly discussed.
Spectroscopic study of J aggregates of amphiphilic merocyanine dyes formed in their pure Langmuir films
Authors: Ikegami Keiichi
Published: July 2004

It is known that an amphiphilic merocyanine dye, 3-carboxymethyl-5-[2-(3-octadecyl-2(3H)- benzothiazolylidene)ethylidene]-2-thioxo-4-thiazolidinone (DS) and its derivatives DSe and 6MeDS form J aggregates under the presence of metallic cations, although the dyes’ static dipole moments must be favorable for H aggregates. A metal-free J aggregate of 6MeDS has been generated in its pure Langmuir films and transferred onto CaF2 substrates to investigate the molecular environment around the carboxylic group born by the dye. Combining visible and infrared spectroscopy, geometrical consideration based on ab initio calculations, and simulation of the excitation energy, a structural model of this J aggregate has been proposed. With this model, formation of intermolecular carboxyl-keto hydrogen bonds, which can compensate the electrostatic disadvantage of the J aggregate under the presence of water, has been suggested. As for another derivative of DS, DO, similar discussion has been made for its Mg2+-containing J aggregate, which is found in this work. In addition, the proposed structural model can tell the cause of the difference in the tendency to J aggregate among 6MeDS, DSe, DS, and DO.
Few-states models for three-photon absorption
Authors: Cronstrand Peter , Norman Patrick , Luo Yi , Ågren Hans
Published: July 2004

Few-states models are derived for the calculation of three-photon absorption matrix elements. Together with earlier derived few-states models for two-photon absorption, the models are evaluated against results from response theory calculations that provide the full sum-over-states values. It is demonstrated that not even for systems with charge-transfer character, where few-states models for two-photon absorption are in excellent agreement with response theory, do the models provide a quantitatively correct description for three-photon absorption. The convergence behavior, merits, and shortcomings of the models are elucidated in some detail. The role of various characteristics of the electronic structure, such as symmetry, charge transfer, and conjugation—important for the formation of a large three-photon cross section—is analyzed. As for two-photon absorption cross sections, it is essential to consider generalized few-states models also for three-photon absorption, that is, to account for dipolar directions and laser beam polarization. Despite their poor quantitative performance, it is argued that few-states models at times can be useful for interpretation purposes when applied to three-photon absorption.
Bounds to average interelectronic angles in Hartree-Fock theory of atoms
Authors: Koga Toshikatsu , Matsuyama Hisashi
Published: July 2004

The average interelectronic angle 〈θ12〉 is the expectation value of the angle θij (0⩽θij⩽π) subtended by the position vectors ri and rj of a pair of electrons i and j. In the Hartree-Fock theory of atoms, we point out that the angle 〈θ12〉 and its subshell-pair components 〈θ12〉nl,n′l′ are bounded from above and below, where n and l are the principal and azimuthal quantum numbers. The upper bounds for 〈θ12〉nl,n′l′ with 0⩽l, l′⩽3 are 9π/16 (=101.25°), 135π/256 (≅94.922°), 265π/512 (≅93.164°), and 129π/256 (≅90.703°) for sp, pd, df, and sf pairs, respectively, while they are π/2 (=90°) for the other ll′ pairs, independent of n and n′. A weighted sum of these subshell-pair bounds gives an upper bound to 〈θ12〉. The lower bounds are π/2 in all the cases.
Thermal decomposition of peroxy acetyl nitrate CH3C(O)OONO2
Authors: von Ahsen Stefan , Willner Helge , Francisco Joseph S.
Published: July 2004

The thermal decomposition of peroxy acetyl nitrate (PAN) is investigated by low pressure flash thermolysis of PAN highly diluted in noble gases and subsequent isolation of the products in noble gas matrices at low temperatures and by density functional computations. The IR spectroscopically observed formation of CH3C(O)OO and H2CCO (ketene) besides NO2, CO2, and HOO implies a unimolecular decay pathway for the thermal decomposition of PAN. The major decomposition reaction of PAN is bond fission of the O-N single bond yielding the peroxy radical. The O-O bond fission pathway is a minor route. In the latter case the primary reaction products undergo secondary reactions whose products are spectroscopically identified. No evidence for rearrangement processes as the formation of methyl nitrate is observed. A detailed mapping of the reaction pathways for primary and secondary reactions using quantum chemical calculations is in good agreement with the experiment and predicts homolytic O-N and O-O bond fissions within the PAN molecule as the lowest energetic primary processes. In addition, the first IR spectroscopic characterization of two rotameric forms for the radical CH3C(O)OO is given.