bluuebunny/crossref_metadata_2025 huggingface dataset:
Other-Worldly and This-Worldly Islam and the Islamic Revival
Authors: Robinson Francis
Published: July 2004

In his Islam in Modern History, published in 1957, yet still a work remarkable for its insights, Wilfred Cantwell Smith refers to the extraordinary energy which had surged through the Muslim world with increasing force in the nineteenth and twentieth centuries. He talks of:

dynamism, the appreciation of activity for its own sake, and at the level of feeling a stirring of intense, even violent, emotionalism…The transmutation of Muslim society from its early nineteenth-century stolidity to its twentieth-century ebullience is no mean achievement. The change has been everywhere in evidence.

This surge of energy is closely associated with a shift in the balance of Muslim piety from an other-worldly towards a this-worldly focus. By this I mean a devaluing of a faith of contemplation of God's mysteries and of belief in His will to shape human life, and a valuing instead of a faith in which Muslims were increasingly aware that it was they, and only they, who could act to fashion an Islamic society on earth. This shift of emphasis has been closely associated with a new idea of great power, the caliphate of man. In the absence of Muslim power, in the absence, for the Sunnis at least, of a caliph, however symbolic, to guide, shape and protect the community, this awesome task now fell to each individual Muslim. I hazard to suggest that this shift towards a this-worldly piety, and the new responsibilities for Muslims that came with it, is the most important change that Muslims have wrought in the practice of their faith over the past one thousand years. It is a change full of possibilities for the future.
Brass, Gold and Silver from Mamluk Egypt: Metal Vessels Made for Sultan Al-Nāṣir Muḥammad
Authors: Ward Rachel
Published: July 2004

This paper is named and given in memory of Mark Zebrowski, friend and respected colleague, who contributed much to life, art history and the culture of India, including his pioneering Gold, silver and bronze from Mughal India. I will focus on the brass vessels inlaid with silver and gold which were produced for one Mamluk sultan, al-Nāṣir Muhammad (1293–4, 1299–1309, 1310–41), whose name and titles are inscribed on more than forty-six objects (see Appendix).
An Oriental Samuel Pepys? Abu'l-Faḍl Bayhaqī's Memoirs of Court Life in Eastern Iran and Afghanistan, 1030–1041
Authors: Bosworth C. Edmund
Published: July 2004

“An oriental Samuel Pepys”. The phrase has been lodged in my mind for the several decades during which I have been working, on and off, on this early Persian historian Bayhaqī. I am pretty certain that I read it originally in that monument of mid-Victorian Anglo-Indian scholarship, The History of India as told by its own Historians. The Muhammadan period, by Sir Henry Elliott and John Dowson. This multi-volume work consists of translated extracts, many quite lengthy, from texts illustrating the history of the Indian subcontinent, the greater part of them dealing with what was then some eleven centuries of Muslim rule there. In Volume II, the compilers presented several passages from Bayhaqī's work, The History of Sultan Maʿsūd of Ghazna, which had just appeared in a printed edition at Calcutta in the Bibliotheca Indica series, edited by the person who had in fact produced the pioneer catalogue of the Royal Asiatic Society's Arabic and Persian manuscripts, William H. Morley. Elliott made many translations himself, but sometimes employed local munshis, not always with happy results. Although Persian culture was still very much alive in India in the mid-nineteenth century, these munshis were far from being au fait with the early eleventh-century Persian style of Bayhaqī and were at times flummoxed by his idiomatic usages. One of my favourites here is the Persian saying ṭablī zīr-i gilīm mīzadand, translated literally and ludicrously in its context as “they were beating a drum under a carpet”. Why anyone should crawl under a carpet and beat a drum, in the midst of a high-level discussion between Sultan Maʿsūd and his administrators, the equivalent of a cabinet meeting, is rather baffling; the idiom, already used by Firdawsī in the national epic, the Shāh-nāma, means of course “to spread rumours clandestinely”.
Empfundene “Selbstnähe“ als Mediator zwischen Fähigkeitsselbstkonzept und Leistungskurswahlintentionen
Authors: Kessels Ursula , Hannover Bettina
Published: July 2004

Zusammenfassung. Ein wichtiger Prädiktor der Leistungskurswahl ist das Fähigkeitsselbstkonzept in der jeweiligen Inhaltsdomäne. Im vorliegenden Aufsatz wird argumentiert, dass positive Effekte des Selbstkonzepts nicht direkt, sondern vermittelt über erhöhte Selbstnähe zustande kommen. Selbstnähe meint das Ausmaß, in dem eine Person glaubt, über ein konkretes Objekt oder ein abstraktes Konzept (wie z.B. ein Schulfach) die eigene Person definieren und nach außen darstellen zu können. Die Absicht, sich dem jeweiligen Objekt oder Konzept zuzuwenden (z.B. einen Leistungskurs in dem Fach zu wählen) steigt einerseits mit der Selbstnähe und andererseits mit der Positivität des Selbstkonzepts eigener Fähigkeit im Umgang mit dem Objekt/Konzept. Es wird ein Messinstrument für Selbstnähe vorgestellt und nachgewiesen, dass das Selbstkonzept fachspezifischer Fähigkeit vermittelt über Selbstnähe auf Leistungskurswahl-Intentionen wirkt.
Selbstregulation und elterliche Hausaufgabenunterstützung
Authors: Bruder Susanne , Perels Franziska , Schmitz Bernhard
Published: July 2004

Zusammenfassung. Zielsetzung des hier vorgestellten Elterntrainingsprogramms war es, die Eltern im Umgang mit ihren Kindern in Lernsituationen und während der Hausaufgabenbearbeitung zu unterstützen. Das Training stellt einen Ansatz zur Elternweiterbildung dar, der Selbstregulationsinhalte und Methoden zur Unterstützung selbstverantwortlichen Lernens der Kinder kombiniert. Insgesamt nahmen 31 Eltern an der Untersuchung teil, davon 20 in der Experimentalgruppe und 11 Eltern in der Kontrollgruppe. Es handelt sich um ein quasiexperimentelles Kontrollgruppendesign mit Messwiederholung. Die Effekte wurden sowohl bei den Eltern als auch auf Schülerebene überprüft. Es zeigte sich, dass sich bei den Eltern keine Effekte in den elterlichen Selbstregulationsskalen, jedoch Effekte in den Skalen der Elternmethoden finden lassen. Auch die Selbstwirksamkeitserwartung der Eltern konnte erhöht werden. Weiterhin berichteten die Eltern von reduzierten Problemen ihrer Kinder bei der Hausaufgabendurchführung. Obwohl die Kinder kein verändertes Verhalten der Eltern wahrnahmen, zeigten sich bei den Schülern trainierter Eltern positive Effekte hinsichtlich der Selbstregulationsskalen.
Entwicklungsveränderungen allgemeiner kognitiver Fähigkeiten und schulbezogener Fertigkeiten im Kindes- und Jugendalter
Authors: Schneider Wolfgang , Stefanek Jan
Published: July 2004

Zusammenfassung. In einer Re-Analyse der Längsschnittdaten zur LOGIK-Studie ( Weinert & Schneider, 1999 ) wurde der Frage nachgegangen, ob sich differentielle Entwicklungsmuster im Sinne eines “Schereneffekts“ für unterschiedliche kognitive Merkmale bei intellektuell fähigeren und weniger fähigen Probanden nachweisen lassen würden. Als relevante kognitive Merkmale fungierten Maße zur verbalen und nichtverbalen Intelligenz und zum logischen Denken sowie Kompetenzen in den Bereichen Lesen, Rechtschreiben und Mathematik. Der Untersuchungszeitraum umfasste die Spanne zwischen dem Vorschulalter (4 Jahre) und dem späten Jugendalter (17 Jahre). Spätere Gymnasiasten und Hauptschüler definierten die beiden hier relevanten Gruppen intellektuell fähiger und weniger fähiger Probanden. In Übereinstimmung mit einer Vorläuferuntersuchung ( Schneider, Knopf & Stefanek, 2002 ) ließen sich wenig Anzeichen für differentielle Entwicklungsverläufe beim Vergleich beider Gruppen finden. Die postulierten Schereneffekte waren lediglich für die verbale Intelligenz, das formale Denken sowie die Rechtschreibleistung nachweisbar. Für alle anderen erfassten Merkmale galt, dass sich reliable Unterschiede zwischen späteren Gymnasiasten und Hauptschülern schon zum ersten Messzeitpunkt (also im Alter von 4 Jahren) fanden, die sich dann im weiteren Entwicklungsverlauf nicht mehr wesentlich veränderten. Der vermutete Einfluss unterschiedlicher pädagogischer Kontexte auf die intellektuelle Entwicklung konnte nur ansatzweise bestätigt werden.
Wechselseitige Einflüsse zwischen Menarchezeitpunkt und Individuation in der Beziehung zur Mutter bei präadoleszenten Mädchen
Authors: Schuster Beate H.
Published: July 2004

Zusammenfassung. Angelehnt an Arbeiten von Steinberg (1988) wird in dem Beitrag einerseits untersucht, ob die Menarche bei Mädchen den Individuationsprozess in der Beziehung zu ihren Müttern intensiviert (“Distanzierungshypothese“) und ob andererseits Konflikte in der Beziehung zu einer früheren Menarche beitragen (“Beschleunigungshypothese“). Dabei wird der Einfluss unterschiedlicher Familienstrukturen auf die Prozesse berücksichtigt. 68 zunächst 10-jährige Mädchen wurden dreimal mit ihren Müttern während eines Aushandlungsspiels beobachtet und zu ihrer Menarche befragt. Logistische und hierarchische Regressionsanalysen bestätigten die Hypothesen zum Teil: Die Mütter verhielten sich entsprechend der Distanzierungshypothese in Folge der Menarche ihrer Töchter kontrollierender und weniger gleichberechtigend. Zeitlich unmittelbar voraus ging der Menarche starkes Abgrenzungsverhalten der Töchter, was aber nicht als Beschleunigungseffekt interpretiert wird. Unabhängig davon verhielten sich in Kern- und Stieffamilien die Mütter kontrollierender sowie weniger gleichberechtigend und die Töchter grenzten sich weniger ab als in Alleinerziehenden-Familien. Das Zusammenspiel zwischen Individuation und Menarche wird diskutiert.
Response of ocean ecosystems to climate warming
Authors: Sarmiento J. L. , Slater R. , Barber R. , Bopp L. , Doney S. C. , Hirst A. C. , Kleypas J. , Matear R. , Mikolajewicz U. , Monfray P. , Soldatov V. , Spall S. A. , Stouffer R.
Published: July 2004

We examine six different coupled climate model simulations to determine the ocean biological response to climate warming between the beginning of the industrial revolution and 2050. We use vertical velocity, maximum winter mixed layer depth, and sea ice cover to define six biomes. Climate warming leads to a contraction of the highly productive marginal sea ice biome by 42% in the Northern Hemisphere and 17% in the Southern Hemisphere, and leads to an expansion of the low productivity permanently stratified subtropical gyre biome by 4.0% in the Northern Hemisphere and 9.4% in the Southern Hemisphere. In between these, the subpolar gyre biome expands by 16% in the Northern Hemisphere and 7% in the Southern Hemisphere, and the seasonally stratified subtropical gyre contracts by 11% in both hemispheres. The low‐latitude (mostly coastal) upwelling biome area changes only modestly. Vertical stratification increases, which would be expected to decrease nutrient supply everywhere, but increase the growing season length in high latitudes. We use satellite ocean color and climatological observations to develop an empirical model for predicting chlorophyll from the physical properties of the global warming simulations. Four features stand out in the response to global warming: (1) a drop in chlorophyll in the North Pacific due primarily to retreat of the marginal sea ice biome, (2) a tendency toward an increase in chlorophyll in the North Atlantic due to a complex combination of factors, (3) an increase in chlorophyll in the Southern Ocean due primarily to the retreat of and changes at the northern boundary of the marginal sea ice zone, and (4) a tendency toward a decrease in chlorophyll adjacent to the Antarctic continent due primarily to freshening within the marginal sea ice zone. We use three different primary production algorithms to estimate the response of primary production to climate warming based on our estimated chlorophyll concentrations. The three algorithms give a global increase in primary production of 0.7% at the low end to 8.1% at the high end, with very large regional differences. The main cause of both the response to warming and the variation between algorithms is the temperature sensitivity of the primary production algorithms. We also show results for the period between the industrial revolution and 2050 and 2090.
A catalog of white light coronal mass ejections observed by the SOHO spacecraft
Authors: Yashiro S. , Gopalswamy N. , Michalek G. , St. Cyr O. C. , Plunkett S. P. , Rich N. B. , Howard R. A.
Published: July 2004

The Solar and Heliospheric Observatory (SOHO) mission's white light coronagraphs have observed nearly 7000 coronal mass ejections (CMEs) between 1996 and 2002. We have documented the measured properties of all these CMEs in an online catalog. We describe this catalog and present a summary of the statistical properties of the CMEs. The primary measurements made on each CME are the apparent central position angle, the angular width in the sky plane, and the height (heliocentric distance) as a function of time. The height‐time measurements are then fitted to first‐ and second‐order polynomials to derive the average apparent speed and acceleration of the CMEs. The statistical properties of CMEs are (1) the average width of normal CMEs (20° < width ≤ 120°) increased from 47° (1996; solar minimum) to 61° (1999; early phase of solar maximum) and then decreased to 53° (2002; late phase of solar maximum), (2) CMEs were detected around the equatorial region during solar minimum, while during solar maximum CMEs appear at all latitudes, (3) the average apparent speed of CMEs increases from 300 km s−1 (solar minimum) to 500 km s−1 (solar maximum), (4) the average apparent speed of halo CMEs (957 km s−1) is twice of that of normal CMEs (428 km s−1), and (5) most of the slow CMEs (V ≤ 250 km s−1) show acceleration while most of the fast CMEs (V > 900 km s−1) show deceleration. Solar cycle variation and statistical properties of CMEs are revealed with greater clarity in this study as compared with previous studies. Implications of our findings for CME models are discussed.
Simulation of polar cap field‐aligned electron density profiles measured with the IMAGE radio plasma imager
Authors: Tu J.‐N. , Horwitz J. L. , Nsumei P. A. , Song P. , Huang X.‐Q. , Reinisch B. W.
Published: July 2004

The radio plasma imager (RPI) on board the IMAGE satellite measured a set of field‐aligned electron density profiles at polar latitudes during a weak magnetic storm on 4 March 2003. Several of those density profiles as well as a density profile measured under moderately quiet conditions are compared with those simulated by a dynamic fluid semikinetic (DyFK) model. In this DyFK model, the collision‐dominated portion of the flux tube is treated with a moment‐based fluid model for altitudes from 120 to 1100 km, while the generalized semikinetic model is used for the 800 km to 3 RE region. The effects of auroral soft electron precipitation, convection‐driven frictional ion heating, centrifugal acceleration, and wave‐driven transverse ion heating are incorporated into simulations of ion field‐aligned flows within flux tubes drifting along empirical model specified convection trajectories across the polar ionosphere. It is found that using reasonable parameters for the indicated energization processes allows agreement between the modeled field‐aligned electron density profiles and those measured by IMAGE/RPI. The simulation results suggest that for the cases considered, the IMAGE/RPI measured electron density profiles may consist primarily of contributions from O+ ions. The O+ dominance in the simulated polar cap density profiles resulted from cleft ion fountain effects. The simulated enhancement of the O+ density accounts for the electron density enhancement in the polar cap during the magnetic storm.
Empirical simulations for the am annual‐diurnal activity
Authors: de La Sayette P.
Published: July 2004

The relationships between solar wind parameters and geomagnetic indices are inherently complex. More often than not, the annual‐diurnal factor of these indices is neglected, likely for two main reasons. First, it is not crucial against the high variability of interplanetary parameters. Second, it remains partially unexplained. This is the case for the dependence of geomagnetic activity on the angle Ψ between the geomagnetic dipole axis and the Earth‐Sun line. It also depends on the southward IMF‐magnetosphere reconnection process, in which the role of the GSEQ Bz contribution to GSM Bz has been so far neglected in annual‐diurnal studies. Using IMF data from 1963 to 2002, we obtain the long due GSM Bz statistical model, which has the ability to reconcile earlier conflicting results. It is then combined with the Ψ dependence to simulate the well‐known am subauroral geomagnetic index. Annual‐diurnal simulations confirm that Ψ is the main source of semiannual activity with a near 60% contribution to am. We further attribute less than 20% to the so‐called Russell and McPherron effect, which stems from GSEQ By, and the complement to the Earth's variable heliographic latitude factor.
Closure study on optical and microphysical properties of a mixed urban and Arctic haze air mass observed with Raman lidar and Sun photometer
Authors: Müller Detlef , Mattis Ina , Ansmann Albert , Wehner Birgit , Althausen Dietrich , Wandinger Ulla , Dubovik Oleg
Published: July 2004

We present a comprehensive optical and microphysical characterization of an intense haze event observed over Leipzig (51.3°N, 12.4°E), Germany, in April 2002. This event was characterized by unusually high optical depths. The haze consisted of a mixture of urban and Arctic haze aerosols which were advected from the Arctic regions across eastern Europe and Scandinavia. For the first time a closure study on such an event could be carried out on the basis of combined observations with Raman lidar and Sun photometer. This study also served as a performance test of the inversion algorithms that are used for retrieving microphysical particle properties from the optical data sets. A comparison of parameters derived in this study to respective quantities determined in the Arctic regions showed that Arctic‐haze‐like material dominated the optical and microphysical particle properties, although a significant amount of this haze must have consisted of urban aerosols. The urban aerosols from eastern Europe had properties rather similar to those characteristic for the well‐aged particles of Arctic haze. The major part of the haze was confined to heights below 3 km. Optical depth was 0.4–0.5 at 532 nm on 8 April 2002. The particle backscatter‐to‐extinction (lidar) ratio varied between 35 and 75 sr at 355 and 532 nm. The Ångström exponent of particle extinction in the wavelength range from 355 to 532 nm was 1.8–2.8. The inversion of the lidar optical data resulted in particle effective radii around 0.19 ± 0.04 μm, volume concentrations of 16–33 μm3 cm−3, surface area concentrations of 270–510 μm2 cm−3, and a single‐scattering albedo around 0.97 ± 0.06 at 532 nm. Particle size distributions showed a rather pronounced monomodal structure in the accumulation mode, which is characteristic for well‐aged particles. The particle properties derived from the two instruments agreed well for intensive parameters, i.e., Ångström exponents, lidar ratio, effective radius, and single‐scattering albedo. Extensive parameters, i.e., total particle surface area and particle volume concentration, showed similar values.
A record of atmospheric CO2 during the last 40,000 years from the Siple Dome, Antarctica ice core
Authors: Ahn Jinho , Wahlen Martin , Deck Bruce L. , Brook Ed J. , Mayewski Paul A. , Taylor Kendrick C. , White James W. C.
Published: July 2004

We have measured the CO2 concentration of air occluded during the last 40,000 years in the deep Siple Dome A (hereafter Siple Dome) ice core, Antarctica. The general trend of CO2 concentration from Siple Dome ice follows the temperature inferred from the isotopic composition of the ice and is mostly in agreement with other Antarctic ice core CO2 records. CO2 rose initially at ∼17.5 kyr B.P. (thousand years before 1950), decreased slowly during the Antarctic Cold Reversal, rose during the Younger Dryas, fell to a local minimum at around 8 kyr B.P., and rose continuously since then. The CO2 concentration never reached steady state during the Holocene, as also found in the Taylor Dome and EPICA Dome C (hereafter Dome C) records. During the last glacial termination, a lag of CO2 versus Siple Dome isotopic temperature is probable. The Siple Dome CO2 concentrations during the last glacial termination and in the Holocene are at certain times greater than in other Antarctic ice cores by up to 20 ppm (μmol CO2/mol air). While in situ production of CO2 is one possible cause of the sporadic elevated levels, the mechanism leading to the enrichment is not yet clear.
Florisphaera profunda and the origin and diagenesis of carbonate phases in eastern Mediterranean sapropel units
Authors: Thomson J. , Crudeli D. , de Lange G. J. , Slomp C. P. , Erba E. , Corselli C. , Calvert S. E
Published: July 2004

High relative concentrations of the lower photic zone nannofossil Florisphaera profunda have been reported in all recent eastern Mediterranean sapropels. In the most recent sapropel (S1), high bulk sediment Sr/Ca ratios occur along with high F. profunda contents toward the base of the unit, exemplified here in four cores from 1.5–3.5 km water depth. Co‐occurring biogenic carbonates contain insufficient Sr to account for these high Sr concentrations, and X‐ray diffraction and selective leaching show that the high Sr/Ca ratios are due to aragonite, the CaCO3 polymorph that is rarely preserved in deep marine sediments, with ∼1 wt % Sr. The possible sources of this aragonite include (1) precipitation with surface ocean production, (2) detrital input from shallow‐water sediments by high continental runoff, or (3) postdepositional diagenetic formation driven by increased pore water alkalinity resulting from sulphate reduction. The third formation mechanism for the aragonite is favored, in which case the similarity in the positions of the aragonite and F. profunda abundance maxima in sapropels is probably related to Corg accumulation and resulting sulphide diagenesis that produces high pore water alkalinity. There is clear micropaleontological evidence that dissolution of the less soluble biogenic low‐Mg CaCO3 is occurring, or has occurred, during early diagenesis in these sediments despite the coexistence of the more soluble high‐Mg calcite and aragonite polymorphs. Similar Sr/Ca maxima are also found associated with older sapropels, always located close both to local minima in surface ocean δ18O that signal maximum monsoon‐driven runoff and to maxima in diagenetic sediment sulphide contents. High freshwater flows from monsoons are believed to drive eastern Mediterranean sapropel formation through water column stabilization that favors F. profunda production and later through development of deep water column dysoxia/anoxia because of reduced ventilation. The relative abundances of F. profunda are high between 5 and 11 14C kyr B.P. with a maximum at ∼9 14C kyr B.P. The surface ocean production changes marked by F. profunda therefore begin earlier and finish later than the formation of the S1 sapropel, which only develops between 6 and 10 14C kyr B.P.
Rifting through a stack of inhomogeneous thrusts (the dipping pie concept)
Authors: Le Pourhiet Laetitia , Burov Evgenii , Moretti Isabelle
Published: July 2004

Orogenic building leaves a complex heritage consisting of a stack of nappes that may have contrasting lithologic structures resulting in heterogeneous mechanical behavior of the system during the postorogenic stages. While the thermal state of the region is reequilibrating, strong lateral variations of the depth to the brittle‐ductile transition develop as a consequence of these preexisting heterogeneities. We use a thermomechanical model to quantify how an inherited weak nappe influences the development of fault patterns resulting from postorogenic extension. The competence contrast between the nappe and the rest of the upper crust as well as the strength of the crust itself are the principal variable parameters of our experiments. The results suggest that a dipping weak nappe introduces a lateral velocity discontinuity and serves as a localization factor for deformation. The presence of a preexisting nappe with a low competence contrast is sufficient to localize strain along the nappe leading to the formation of a flexural rolling hinge. In this case, the migration of the basin is slow, continuous, and limited by gravity driven processes that lead to the rise of hot (weak) material under the subsiding basin. In case of a high competence contrast, overall crustal strength is reduced by a “dipping pie” effect. Assuming overall high crustal strength, the presence of a contrasting nappe leads to a bimodal fault pattern governed by two types of faults: crustal‐scale planar faults rooting on the brittle ductile transition of the crust and thin‐skinned listric faults rooting on the nappe itself. This bimodality results in a jump‐like migration of the basin downward along the dipping weak nappe. Applying this model to the case of the Gulf of Corinth (Greece) allows us to explain, in the case of assumed high competence contrast, the observed microseismicity patterns, the asymmetry of the Gulf, and the kinematics of fault migration within the basin.
Log Pearson type 3 quantile estimators with regional skew information and low outlier adjustments
Authors: Griffis V. W. , Stedinger J. R. , Cohn T. A.
Published: July 2004

The recently developed expected moments algorithm (EMA) [Cohn et al., 1997] does as well as maximum likelihood estimations at estimating log‐Pearson type 3 (LP3) flood quantiles using systematic and historical flood information. Needed extensions include use of a regional skewness estimator and its precision to be consistent with Bulletin 17B. Another issue addressed by Bulletin 17B is the treatment of low outliers. A Monte Carlo study compares the performance of Bulletin 17B using the entire sample with and without regional skew with estimators that use regional skew and censor low outliers, including an extended EMA estimator, the conditional probability adjustment (CPA) from Bulletin 17B, and an estimator that uses probability plot regression (PPR) to compute substitute values for low outliers. Estimators that neglect regional skew information do much worse than estimators that use an informative regional skewness estimator. For LP3 data the low outlier rejection procedure generally results in no loss of overall accuracy, and the differences between the MSEs of the estimators that used an informative regional skew are generally modest in the skewness range of real interest. Samples contaminated to model actual flood data demonstrate that estimators which give special treatment to low outliers significantly outperform estimators that make no such adjustment.
On the advective‐diffusive transport in porous media in the presence of time‐dependent velocities
Authors: Selvadurai A. P. S.
Published: July 2004

This paper develops certain exact closed form solutions to one‐dimensional problems involving both advective and advective‐diffusive transport in a porous medium, particularly in the presence of a Darcy velocity field that is time‐dependent. Such situations can occur when the boundary potential inducing flow in the porous medium is time‐dependent. A particular form chosen is an exponentially decaying time‐dependency in the flow velocity, resulting from a non‐replenishing source. The value of the one‐dimensional solution stems not only from its potential applicability for the calibration of computational schemes used to examine the advection‐diffusion equation in general, but also for the study of the purely advective flow problem with time‐dependent velocity that requires sophisticated adaptive computational schemes to ensure numerical stability at a leading front in the form a discontinuity.
A method for on‐line measurement of water‐soluble organic carbon in ambient aerosol particles: Results from an urban site
Authors: Sullivan A. P. , Weber R. J. , Clements A. L. , Turner J. R. , Bae M. S. , Schauer J. J.
Published: July 2004

An instrument for on‐line continuous measurement of the water‐soluble organic carbon (WSOC) component of aerosol particles is described and results from an urban site in St. Louis are presented. A Particle‐into‐Liquid Sampler impacts ambient particles, grown to large water droplets, onto a plate and then washes them into a flow of purified water. The resulting liquid is filtered and the carbon content quantified by a Total Organic Carbon analyzer providing continuous six‐minute integral measurements with a detection limit of 0.1 μg C/m3. Summer and fall measurements of WSOC and organic carbon (OC) indicated WSOC/OC ratio typically ranged from 0.40 to 0.80. A diurnal variation in WSOC/OC that correlated with ozone was observed over extended periods in June; however, other periods in August had no correlation. The results suggested that WSOC was composed of a complex mixture of compounds that may contain a significant fraction from secondary organic aerosol formation.
Subpolar Mode Water formation traced by neodymium isotopic composition
Authors: Lacan F. , Jeandel C.
Published: July 2004

The formation of Subpolar Mode Water (SPMW) is documented by combining neodymium isotopic composition (Nd IC) as a conservative tracer with salinity, temperature and O2 concentration. Nd IC reveals a more pronounced eastward extension of the Labrador Current, particularly its Subarctic Intermediate Water component, than the other parameters. Nd IC also suggests that waters flowing through the Denmark Strait do not significantly contribute to the SPMW formation. A two end‐member mixing, involving Subarctic Intermediate Water (and maybe ultimately Labrador Current Water) and North Atlantic Central Water, is proposed to explain SPMW formation. These results provide important insight into the processes controlling the Nd IC in the North Atlantic Subpolar Gyre, which could provide a means for reconstructing the northward extension of the Gulf Stream in the past.
Properties of methane clouds on Titan: Results from microphysical modeling
Authors: Barth Erika L. , Toon Owen B.
Published: July 2004

Observations indicate methane in Titan's atmosphere may be both highly supersaturated and condensed in clouds. In this paper, we present simulations of methane clouds which show that supersaturation and condensation can be compatible given certain conditions. Cloud formation is limited by lack of suitable nuclei as it is for terrestrial cirrus. The simulations suggest much of the troposphere contains optically thin clouds composed of methane which have formed on ethane coated cores. Optically thick methane clouds form in regions where atmospheric dynamics pushes the supersaturation beyond a threshold value. Horizontal quasi‐barotropic motions are more likely to drive the supersaturation creating these clouds than are vertical motions.
Energy spectrum proportional to the squared phase speed of Rossby modes in the general circulation of the atmosphere
Authors: Tanaka H. L. , Watarai Yasushi , Kanda Takahiro
Published: July 2004

In this study, energy spectrum of the large‐scale atmospheric motions is examined in the framework of the 3D normal mode decomposition. The horizontal scale of disturbance is measured by the phase speed of a Rossby mode c. According to the analysis result for the barotropic component of the atmosphere, we obtain a characteristic energy spectrum with distinct slopes for the turbulence and wave regimes separated by the spherical Rhines speed. In order to explain the observational finding that the energy spectrum is proportional to c2, we put forward a hypothesis based on the criterion of Rossby wave breaking such that the local meridional gradient of potential vorticity becomes negative, ∂q/∂y < 0, somewhere in the domain. With a constant m describing a total mass of the atmosphere for unit area, we have shown that the barotropic energy spectrum of the general circulation E can be represented as E = mc2.
Monitoring aerosol optical properties over the Mediterranean from SeaWiFS images using a neural network inversion
Authors: Jamet C. , Moulin C. , Thiria S.
Published: July 2004

The SeaWiFS archive provides a unique opportunity to study aerosol optical properties over oceans since October 1997. Standard SeaWiFS aerosol products are however not suitable because optical thicknesses are limited to 0.35 and Angström exponents to 1.5. We developed an inversion based on neural networks to retrieve both optical thickness and Angström exponent from SeaWiFS red and near infrared channels. Neural networks are capable of approximating non‐linear inverse functions and of processing efficiently large amounts of data. Neural networks were trained with radiative transfer computations for wide ranges of optical thickness and Angström exponent. All SeaWiFS images of the Mediterranean for year 2000 were processed and monthly mean maps of aerosol optical thickness and Angström exponent were derived. A comparison with ground‐based measurements at three AERONET stations in the Mediterranean shows the good accuracy of the method, as well as the improvement compared to operational SeaWiFS aerosol products.
Thunderstorm and lightning characteristics associated with sprites in Brazil
Authors: Pinto O. , Saba M. M. F. , Pinto I. R. C. A. , Tavares F. S. S. , Naccarato K. P. , Solorzano N. N. , Taylor M. J. , Pautet P. D. , Holzworth R. H.
Published: July 2004

A study of the thunderstorm and cloud‐ground lightning characteristics associated with sprite events observed in Brazil is presented. The study is based on ground and aircraft sprite observations with high sensitivity intensified CCD cameras of six different thunderstorms, GOES satellite infrared images, radar and lightning network data. A total of eighteen transient optical events were recorded at three different days in 2002 and 2003, sixteen of which exhibited vertical structures typically associated with sprites. Four thunderstorms were associated with two different cold fronts, one with a Mesoscale Convective System, and one was a local isolated thunderstorm. The sprites occurred during time periods when the percentage of positive flashes was higher than the average percentage for the storm lifetime. The lightning associated with the sprite events was all positive flashes with a mean peak current higher than the mean value for all flashes in the storms.
Altitude variation of glacier mass balance in Scandinavia
Authors: Rasmussen L. A.
Published: July 2004

For each of ten glaciers in Norway and two in Sweden, vertical profiles of net balance bn(z), which are typically published as values at about a dozen altitudes, are strongly linear and nearly parallel from year to year. Separate linear functions fit the bn(z) from year to year with r2 ≥ 0.89 over the 12 glaciers. A family of parallel lines for each glacier that differ from year to year only by an amount Δbn constant with altitude has r2 ≥ 0.85. There is an altitude z′ on each glacier where the measured balance bn(z′) correlates well with the glacier‐total bn with r ≥ 0.97 over the 12 glaciers. A remarkable consequence of this and of the high correlation of bn between many of the glaciers in the region is that measurements on one glacier (1775 meters on Hardangerjøkulen) provide a good estimate of bn at several other glaciers.
Metal–organic–metal cathode for high-contrast organic light-emitting diodes
Authors: Feng X. D. , Khangura R. , Lu Z. H.
Published: July 2004

Organic light-emitting diodes have been fabricated using a stacked metal–organic–metal cathode structure. The first metal layer is embedded approximately between an emission layer and an electron transport layer serving as a floating electron injection electrode. The second metal layer is a terminal layer serving as a contacting electrode. The optical transmission of the embedded electrode and the optical path between the two electrodes were used together to maximize destructive optical interference, thus rendering the cathode nonreflective. These devices also showed excellent diode characteristics; for example, a luminance of 100 cd/m2 at ∼3 V. Optical reflectance in the visible spectrum for the diodes was found to be reduced from ∼80% on conventional devices to ∼20% on devices with the metal–organic–metal cathode.
Ab initio study of small graphitic cones with triangle, square, and pentagon apex
Authors: Compernolle Steven , Kiran B. , Chibotaru L. F. , Nguyen M. T. , Ceulemans Arnout
Published: July 2004

Accurate geometries of carbon nanocones of different sizes with a triangle, square or pentagon at the apex have been determined for the first time using a quantum chemical optimization method. The structure close to the apex is distorted from an ideal conical surface. The charging effect of the central defect is quite different from that predicted by tight-binding calculations. The symmetry behavior of the frontier orbitals and the size of the highest occupied molecular orbital–lowest unoccupied molecular orbital gap versus cone type and size is explained. The density of states quickly converges towards that of graphite when the size of the cone increases. In comparison to previous results in the literature it is found that the local densities of states of cones, that are locally different but belong to the same topo-combinatoric class, share common features.
The Xe shielding surfaces for Xe interacting with linear molecules and spherical tops
Authors: Sears Devin N. , Jameson Cynthia J.
Published: July 2004

The Xe129 nuclear magnetic resonance spectrum of xenon in gas mixtures of Xe with other molecules provides a test of the ab initio surfaces for the intermolecular shielding of Xe in the presence of the other molecule. We examine the electron correlation contributions to the Xe–CO2, Xe–N2, Xe–CO, Xe–CH4, and Xe–CF4 shielding surfaces and test the calculations against the experimental temperature dependence of the density coefficients of the Xe chemical shift in the gas mixtures at infinite dilution in Xe. Comparisons with the gas phase data permit the refinement of site–site potential functions for Xe–N2, Xe–CO, and Xe–CF4 especially for atom-Xe distances in the range 3.5–6 Å. With the atom–atom shielding surfaces and potential parameters obtained in the present work, construction of shielding surfaces and potentials for applications such as molecular dynamics averaging of Xe chemical shifts in liquid solvents containing CH3, CH2, CF3, and CF2 groups is possible.
The history force on a rapidly shrinking bubble rising at finite Reynolds number
Authors: Takemura Fumio , Magnaudet Jacques
Published: July 2004

Using an optical device and a travelling system, we determine precisely the evolution of the radius and rising speed of a single CO2 or CO2–air bubble rising at finite Reynolds number in an aqueous NaOH solution and rapidly dissolving in it. We willingly introduce a slight amount of pentanol in the aqueous solution to force the bubble surface to obey a no-slip condition. The measurements allow us to evaluate directly the instantaneous magnitude of the buoyancy, added-mass, and quasisteady drag forces experienced by the bubble. We then deduce the magnitude of the so-called history force from the total force balance. It turns out that this force can be up to one-half of the buoyancy force during a certain stage of the motion. Using the argument developed by Magnaudet and Legendre [Phys. Fluids 10, 550 (1998)], we derive the counterpart of the Basset–Boussinesq history force for the case of a rigid sphere with a time-dependent radius, as well as the counterpart of some finite-Reynolds-number empirical extensions of this expression. We use these results to predict the time evolution of the history force in our experiments. Owing to finite-Reynolds-number effects, the zero-Reynolds-number expression yields totally unrealistic results. In contrast we find that, once properly generalized to a sphere of time-varying radius, the finite-Reynolds-number expression proposed by Kim, Elghobashi, and Sirignano [J. Fluid Mech. 367, 221 (1998)] provides an accurate estimate of the evolution of the history force and hence allows the bubble velocity to be precisely predicted all along the dissolution process.
Coupled reference interaction site model/simulation approach for thermochemistry of solvation: Theory and prospects
Authors: Freedman Holly , Truong Thanh N.
Published: July 2004

We present a new methodology for computing solvation free energy, which is based upon the reference interaction site model (RISM)/hypernetted chain (HNC) solvation free energy expression, but which substitutes radial distribution functions taken from simulations for those calculated by simultaneous solution of the RISM and HNC equations. Consequently, solvation free energy can be obtained from a single molecular dynamics or Monte Carlo simulation. Here we describe in detail the coupled RISM/simulation approach, and offer some error analysis. Finally we give the results of its application to a set of small test molecules in aqueous solution. The success shown in some of our results demonstrates that the coupled RISM/simulation approach is worth considering further as a potentially useful tool in studies of solvated systems, such as aqueous molecular biosystems.
Optical linear response function with linear and diagonal quadratic electron-vibration coupling in mixed quantum-classical systems
Authors: Toutounji Mohamad
Published: July 2004

Optical linear response function of linearly and quadratically coupled mixed quantum-classical condensed phase systems is derived. The linear response function is derived using Kapral’s formalism of statistical mechanics in mixed quantum-classical systems. Our mixed quantum-classical linear dipole moment correlation function J(t) is compared with the full quantum J(t) [Y. J. Yan and S. Mukamel, J. Chem. Phys. 85, 5908 (1986)] in the high temperature limit. Model calculations and discussion of our results are presented. Various formulas of Franck–Condon factors for both linear and quadratic coupling are discussed.
Isomeric interconversion in the linear Cl−-HD anion complex
Authors: Wilson R. L. , Loh Z. M. , Wild D. A. , Bieske E. J. , Buchachenko A. A.
Published: July 2004

The rotationally resolved infrared photodissociation spectrum of Cl−-HD is measured in the HD stretch region. Two Σ-Σ bands are observed, corresponding to transitions from the ground state [the (vHD=0, n=0) level] and first excited intermolecular bend state [the (vHD=0, n=1) level]. The (vHD=0, n=0) and (vHD=0, n=1) states are predominantly associated with the linear Cl−⋯DH and Cl−⋯HD geometries, respectively. The spectrum is complicated by perturbative interactions between levels of the (vHD=0, n=0) and (vHD=0, n=1) rotational manifolds and between levels of the (vHD=1, n=0) and (vHD=1, n=1) rotational manifolds. A global fit to the transition frequencies, taking the lower and upper state perturbations into account, yields zero-order rotational and centrifugal distortion constants and allows us to establish that the (vHD=0, n=1, J″=0) level lies 13.7 cm−1 above the (vHD=0, n=0, J″=0) level. Rovibrational energy level calculations performed using a recent ab initio potential energy surface confirm the picture emerging from the experimental data and provide good agreement with measured molecular parameters. The results emphasize the importance of quantum mechanical interconversion between two isomeric structures of a simple anion complex.
Polyelectrolyte shells of copolymer micelles in aqueous solutions: A Monte Carlo study
Authors: Uhlı́k Filip , Limpouchová Zuzana , Jelı́nek Karel , Procházka Karel
Published: July 2004

Multimolecular micelles, formed by polystyrene-block-poly(methacrylic acid) in water, are studied by lattice Monte Carlo method. Electrostatic interactions are calculated in the mean-field approximation by solving the Poisson-Boltzmann equation. The model is parametrized according to available experimental data. The dependence of micellar size on pH and ionic strength is calculated and compared with experimental data. A special attention is devoted to the behavior in solutions with a low ionic strength.
Free volume properties of a linear soft polymer: A computer simulation study
Authors: Sega Marcello , Jedlovszky Pál , Medvedev Nikolai N. , Vallauri Renzo
Published: July 2004

Molecular dynamics simulation of a linear soft polymer has been performed and the free volume properties of the system have been analyzed in detail in terms of the Voronoi polyhedra of the monomers. It is found that there are only small density fluctuations present in the system. The local environment of the monomers is found to be rather spherical, even in comparison with liquids of atoms or small molecules. The monomers are found to be, on average, eight coordinated by their nearest geometric neighbors, including intra-chain and inter-chain ones. The packing of the monomers is found to be rather compact, in a configuration of 1900 monomers there are, on average, only three voids large enough to incorporate a spherical particle as large as a monomer, indicating that the density of the large vacancies in the system is considerably, i.e., by a few orders of magnitude lower than in molecular liquids corresponding to roughly the same reduced densities.
Phase behavior of n-alkanes in supercritical solution: A Monte Carlo study
Authors: Virnau Peter , Müller Marcus , MacDowell L. G. , Binder K.
Published: July 2004

We present a coarse-grained model for n-alkanes in a supercritical solution, which is exemplified by a mixture of hexadecane and CO2. For pure hexadecane, the Monte Carlo simulations of the coarse-grained model reproduce the experimental phase diagram and the interfacial tension with good accuracy. For the mixture, the phase behavior sensitively depends on the compatibility of the polymer with the solvent. We present a global phase diagram with critical lines, which is in semiquantitative agreement with experiments. In this context we developed two computational schemes: The first adopts Wang-Landau sampling to the off-lattice grand canonical ensemble, the second combines umbrella sampling with an extrapolation scheme to determine the weight function. Additionally, we use Wertheim’s theory (TPT1) to obtain the equation of state for our coarse-grained model of supercritical mixtures and discuss the behavior for longer alkanes.
Electron acceleration by a circularly polarized laser pulse in a plasma
Authors: Singh K. P.
Published: July 2004

Results of a relativistic three-dimensional single particle code, on direct laser acceleration of electrons in an axial static field are presented. The electron rotates around the propagation direction of the laser pulse during the interaction with circularly polarized intense laser pulse. Betatron resonance occurs between the electrons and electric field of the laser pulse for two optimum values of the magnetic fields, and the electrons gain much higher energies. The resonance is stronger at higher values of the magnetic field. The values of magnetic fields at which resonance occurs depend upon the laser intensity and plasma density, and initial electron energy. At higher plasma density, the group velocity of the laser pulse is too slow to catch up with the accelerated electrons, reducing the duration of interaction and diminishing energy gain. The electrons with less initial energy find more time to interact with the laser pulse and gain more energy than the electrons with more initial energy. Electron trajectory and energy for different parameters have been obtained.