bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of ionospheric electric fields to variations in the interplanetary magnetic field
Authors: Mishra S. P. , Nielsen E.
Published: July 2005

Abstract. The STARE system (Scandinavian Twin Auroral Radar Experiment) provides estimates of electron drift velocities, and hence also of the electric field in the high-latitude E-region ionosphere between 65 and 70 degrees latitude. The occurrence of drift velocities larger than about 400 m/s (equivalent to an electric field of 20 mV/m) have been correlated with the magnitude of the Interplanetary Magnetic Field (IMF) components Bz and By at all local times. Observation days have been considered during which both southward (Bz<0) and northward (Bz>0) IMF occurred. The occurrence of electric fields larger than 20 mV/m increases with increases in Bz magnitudes when Bz<0. It is found that the effects of southward IMF continue for some time following the northward turnings of the IMF. In order to eliminate such residual effects for Bz<0, we have, in the second part of the study, considered those days which were characterized by a pure northward IMF. The occurrence is considerably lower during times when Bz>0, than during those when Bz is negative. These results are related to the expansion and contraction of the auroral oval. The different percentage occurrences of large electric field for By>0 and By<0 components of the IMF during times when Bz>0, clearly display a dawn-dusk asymmetry of plasma flow in the ionosphere. The effects of the time-varying solar-wind speed, density, IMF fluctuations, and magnetospheric substorms on the occurrence of auroral-backscatter observations are also discussed.
N2 and M2 lunar tides: atmospheric resonance revisited
Authors: Schlapp D. M. , Stening R. J. , Forbes J. M. , Manson A. H. , Meek C. E. , Vincent R. A.
Published: July 2005

Abstract. A numerical model has been used to calculate the atmospheric response to forcing at periods in the region of 12-13.5 h. The results show that the response is enhanced in the neighbourhood of 13 h. These results have been compared with lunar tidal analyses of mesospheric wind data and geomagnetic variations at a number of stations. It is found that the N2 lunar tidal component (period 12.66 h) is significantly enhanced relative to the main lunar tidal component M2 (period 12.42 h) in both types of data, compared with what would be expected from the gravitational tidal potential. This supports the predictions of the numerical model. An appreciable phase shift is also found in the experimental data between the N2 and M2 tides, agreeing in sense with what would be expected for a resonance at a period around 13 h.
Influence of crystal shapes on radiative fluxes in visible wavelength: ice crystals randomly oriented in space
Authors: Chervet P. , Isaka H. , Nakajima T.
Published: July 2005

Abstract. Radiative properties of cirrus clouds are one of the major unsolved problems in climate studies and global radiation budget. These clouds are generally composed of various ice-crystal shapes, so we tried to evaluate effects of the ice-crystal shape on radiative fluxes. We calculated radiative fluxes of cirrus clouds with a constant geometrical depth, composed of ice crystals with different shapes (hexagonal columns, bullets, bullet-rosettes), sizes and various concentrations. We considered ice particles randomly oriented in space (3D case) and their scattering phase functions were calculated by a ray-tracing method. We calculated radiative fluxes for cirrus layers for different microphysical characteristics by using a discrete-ordinate radiative code. Results showed that the foremost effect of the ice-crystal shape on radiative properties of cirrus clouds was that on the optical thickness, while the variation of the scattering phase function with the ice shape remained less than 3% for our computations. The ice-water content may be a better choice to parameterize the optical properties of cirrus, but the shape effect must be included.
The influence of cloud structure and droplet concentration on the reflectance of shortwave radiation
Authors: Coley P. F. , Jonas P. R.
Published: July 2005

Abstract. The effects of cloud shadowing, channelling, cloud side illumination and droplet concentration are investigated with regard to the reflection of shortwave solar radiation. Using simple geometric clouds, coupled with a Monte Carlo model the transmission properties of idealized cloud layers are found. The clouds are illuminated with direct solar radiation from above. The main conclusion reached is that the distribution of the cloud has a very large influence on the reflectivity of a cloud layer. In particular, if the cloud contains vertical gaps through the cloud layer in which the liquid water content is zero, then, smaller more numerous gaps are more influential on the radiation than fewer, larger gaps with equal cloud fraction. At very low solar zenith angles channelling of the radiation reduces the reflection expected on the basis of the percentage cloud cover. At high solar zenith angles the illumination of the cloud edges significantly increases the reflection despite the shadowing of one cloud by another when the width of the gaps is small. The impact of droplet concentration upon the reflection of cloud layers is also investigated. It is found that at low solar zenith angles where channelling is important, the lower concentrations increase the transmission. Conversely, when cloud edge illumination is dominant the cloud distribution is found to be more important for the higher concentrations.
Ponderomotive effects in magnetospheric hydromagnetic waves (*)
Authors: Allan W. , Manuel J. R.
Published: July 2005

Abstract. The ponderomotive force (PMF) is a ubiquitous nonlinear wave effect arising in plasma physics when applied wave fields or plasma parameters have significant spatial gradients. Some basic properties of the PMF are described as they relate to ULF hydromagnetic waves in the magnetosphere. Examples are given of recent results obtained using both analytical and numerical techniques for waves from the lowest frequencies (determined by the dimensions of the magnetosphere) up to the vicinity of the ion cyclotron frequency. These results include the possibilities that the PMF may transport plasma over large distances in the magnetosphere, and that the PMF may energize magnetospheric ions significantly. In particular the PMF may play a role in transporting and energizing O+ ions from the ionosphere into the body of the magnetosphere. The PMF can also generate nonlinear coupling between the slow magnetosonic mode and the other hydromagnetic modes. This should lead to limitation of density enhancements and, notably in the case of standing Alfvén waves, to spatial harmonic generation, secularly growing frequency shifts, and saturation of driven wave fields. Some implications of these results for the magnetosphere are discussed.
CHANGING REPRESENTATIONS IN CENTRAL AFRICAN HISTORY
Authors: MACGAFFEY WYATT
Published: July 2005

This article examines how historiography makes its objects and includes critical reflections on the epistemological frames that have shaped historical representations of Central African states and social structures. The article examines the seductive quality of migration narratives; mythical features of some classical models, creating order from reduced totalities; historiographic burdens imposed by questionable anthropological models of kinship and matrilineal descent; and asks if the prevalence of dual regimes of priest and king is a product more of ideology than history. The article argues for increasing recognition of the value in political studies of data relating to religion and art.
BANKOE V. DOME: TRADITIONS AND PETITIONS IN THE HO-ASOGLI AMALGAMATION, BRITISH MANDATED TOGOLAND, 1919–39
Authors: LAWRANCE BENJAMIN N.
Published: July 2005

This article investigates Ewe engagement with British administrative policy via the story of a chieftaincy dispute in Ho, British Mandated Togoland, that erupted when Britain attempted to amalgamate two neighboring chieftaincies, Ho-Dome and Ho-Bankoe, by deploying a model with an ‘ethnic stamp’, that of the neighboring Akan states. Colonial-era chieftaincy has received substantial scholarly attention. This article argues that the relationship between the models deployed to reorganize chiefly power and the roles of protagonists is just as significant as the layered conflicts within chieftaincies and their respective clans. Two responses to ‘Akanized’ amalgamation are investigated: the petitions of its opponents, and the rituals developed by chiefs, priests and peasants to herald the amalgamations.
Une analyse discursive d'un type de reprise immédiate: la reprise autonymique, dans les énoncés définitoires
Authors: REBEYROLLE JOSETTE
Published: July 2005

Cet article porte sur les énoncés définitoires indirects et se donne pour objectif de préciser comment se marque l'intention définitoire du locuteur dans ces énoncés qui ne comportent aucun indicateur explicite de leur force illocutionnaire. L'analyse de l'insertion discursive de ces énoncés conduit à mettre en lumière le fait que les situations, dans lesquelles le terme à définir fait l'objet d'une première mention généralement immédiate, sont favorables pour marquer le passage du discours référentiel au discours définitoire. L'explication tient compte de la structure informationnelle des énoncés et propose une analyse en terme de décrochage autonymique.
Description syntaxique et discursive des syntagmes nominaux de type N dit + complément adjectival, prépositionnel ou nominal
Authors: WHITTAKER SUNNIVA
Published: July 2005

Le présent article a un double objectif. Tout d'abord, il vise à déterminer le rapport entre la construction nominale N dit + complément et le verbe dire. L'étude de 270 occurrences tirées des journaux Le Monde et Libération amène à conclure qu'il existe deux types formels correspondant à deux schémas valenciels du verbe dire, à savoir dire + complément d'objet, où le verbe dire a un sens métalinguistique, et dire + complément d'objet + attribut de l'objet. Les occurrences du corpus relèvent à plus de 99 pour cent du premier type. La deuxième partie de l'étude vise à mettre au jour le rôle discursif de la construction. Celui-ci est étroitement lié au statut du sujet sous-jacent du verbe dire.
Reanalysis and reforecast of three major European storms of the twentieth century using the ECMWF forecasting system. Part II: Ensemble forecasts
Authors: Jung Thomas , Klinker Ernst , Uppala Sakari
Published: July 2005

In Part II of this study the ECMWF Ensemble Prediction System (EPS) is used to study the probabilistic predictability of three major European storms of the twentieth century. The storms considered are the Dutch storm of 1 February 1953, the Hamburg storm of 17 February 1962, and the British/French storm of October 1987 (Great October storm). Common to all these storms is their severity that caused large loss of life and widespread damage.

In Part I of this study it has been found that deterministic predictability of the Dutch and Hamburg storms amount to 48 and 84 hours, respectively. Here, it is shown that the ensemble forecasts supplement the deterministic forecasts. The large number of members in the 48 and 84 hour ensemble forecasts of the Dutch and Hamburg storms, respectively, suggest that at this forecast range and for these storms the sensitivity of the forecasts to analysis and model uncertainties is rather small. From these results, therefore, it is argued that reliable warnings (i.e. low probability for the occurrence of a forecast failure) for the Dutch and Hamburg storms could have been issued 48 and 84 hours, respectively, in advance, had the current ECMWF EPS been available.

For the Great October storm it has been found in Part I of this study that short‐range and medium‐range forecasts of the intensity and track of the storm were very skilful with a high‐resolution model of the ECWMF model. The actual timing of the storm, however, was difficult to predict. Here, it is shown that the EPS is capable of predicting large forecast uncertainties associated with the timing of the Great October storm up to 4 days in advance. It is argued that reliable warnings could have been issued at least 96 hours in advance had the ECMWF EPS been available.

From the results presented in this study it is concluded that an Ensemble Prediction System is an important component of every early warning system for it allows an a priori quantification of the probability of the occurrence of severe wind storms. Copyright © 2005 Royal Meteorological Society
FLUX: A logic programming method for reasoning agents
Authors: THIELSCHER MICHAEL
Published: July 2005

FLUX is a programming method for the design of agents that reason logically about their actions and sensor information in the presence of incomplete knowledge. The core of FLUX is a system of Constraint Handling Rules, which enables agents to maintain an internal model of their environment by which they control their own behavior. The general action representation formalism of the fluent calculus provides the formal semantics for the constraint solver. FLUX exhibits excellent computational behavior due to both a carefully restricted expressiveness and the inference paradigm of progression.
Schedulers and redundancy for a class of constraint propagation rules
Authors: BRAND SEBASTIAN , APT KRZYSZTOF R.
Published: July 2005

We study here schedulers for a class of rules that naturally arise in the context of rule-based constraint programming. We systematically derive a scheduler for them from a generic iteration algorithm of Apt (2000). We apply this study to so-called membership rules of Apt and Monfroy (2001). This leads to an implementation that yields a considerably better performance for these rules than their execution as standard CHR rules. Finally, we show how redundant rules can be identified and how appropriately reduced sets of rules can be computed.
Commitment gegenüber Verleiher und Entleiher bei Zeitarbeitern
Authors: Felfe Jörg , Schmook Renate , Six Bernd , Wieland Rainer
Published: July 2005

Zusammenfassung. Aktuell ist ein Anstieg neuer Arbeits- und Beschäftigungsformen zu verzeichnen. Hierzu gehört auch Zeit- oder Leiharbeit. Zeitarbeit wird vor allem als Chance für Unternehmen gesehen, kurzfristigen Personalbedarf zu decken, ohne sich langfristig an neue Mitarbeiter zu binden und Verpflichtungen hinsichtlich einer Weiterbeschäftigung einzugehen. Für die Beschäftigten kann Zeitarbeit als Chance zum Berufseinstieg, für Flexibilität und zur Verbreiterung der beruflichen Erfahrung gesehen werden. Definitionsgemäß gehören Zeitarbeiter zwei Organisationen gleichzeitig an - dem Zeitarbeitsunternehmen (Verleiher) und dem Entleiher - und entwickeln zu beiden unterschiedliche Beziehungen. An einer Stichprobe von N = 185 Zeitarbeitern wird das Commitment gegenüber dem Verleiher, dem Entleiher sowie gegenüber Zeitarbeit als Arbeitsform untersucht. Die Ergebnisse zeigen, dass Merkmale des Verleihers (Einkommen, Führung) vor allem mit dem Commitment gegenüber dem Verleiher korrelieren, während Bedingungen beim Entleiher (Arbeitsaufgabe, Führung beim Entleiher) mit dem Commitment gegenüber dem Entleiher korrespondieren. Außerdem wird geprüft, welche spezifischen Zusammenhänge die Commitmentfoci zu OCB (Organizational Citizenship Behavior), Arbeitszufriedenheit und Stresserleben als Konsequenzen aufweisen. Es lässt sich zeigen, dass das Commitment gegenüber dem Entleiher eine wichtige Rolle für die Leistung und das Erleben bei Zeitarbeitern spielt und daher systematisch gefördert werden sollte.
Berufliche Folgen der Inanspruchnahme von Elternzeiten aus Sicht von Personalfachleuten aus der Privatwirtschaft und dem Öffentlichen Dienst
Authors: Wiese Bettina S.
Published: July 2005

Zusammenfassung. Das Anrecht auf Elternzeit nach der Geburt eines Kindes soll die Vereinbarkeit von Beruf und Familie erleichtern. Aber welche karrierebezogenen Risiken birgt die Inanspruchnahme von Elternzeiten? N = 64 Personalverantwortliche aus dem Öffentlichen Dienst und der Privatwirtschaft wurden gebeten, die potenziellen beruflichen Folgen (z. B. negative Gehaltsentwicklung, nachfolgend geringere Übertragung von Personalverantwortung) einer ein- bzw. dreijährigen Elternzeit für weibliche Führungskräfte in ihren Organisationen einzuschätzen. Es zeigte sich, dass bei dreijähriger Elternzeit von einem signifikant höheren Risiko negativer beruflicher Konsequenzen ausgegangen wurde als bei einjähriger Elternzeit. Dies traf sowohl für den Öffentlichen Dienst als auch für die Privatwirtschaft zu. Allerdings wurde in der Privatwirtschaft bei dreijähriger Elternzeit von stärkeren negativen Konsequenzen ausgegangen als im Öffentlichen Dienst. Eine ergänzende Analyse offener Angaben ergab, dass Personalfachleute weiblichen Führungskräften in der Familiengründungsphase raten würden, sich um einen zügigen Wiedereinstieg ins Berufsleben zu bemühen, wobei in diesem Zusammenhang insbesondere auch die Möglichkeit einer zeitweisen Teilzeitbeschäftigung thematisiert wurde.
Local structure of a phase-separating binary mixture in a mesoporous glass matrix studied by small-angle neutron scattering
Authors: Schemmel Sebastian , Rother Gernot , Eckerlebe Helmut , Findenegg Gerhard H.
Published: July 2005

The mesoscopic structure of the binary system isobutyric acid+heavy water (D2O) confined in a porous glass (controlled-pore silica glass, mean pore width ca. 10 nm) was studied by small-angle neutron scattering at off-critical compositions in a temperature range above and below the upper critical solution point. The scattering data were analyzed in terms of a structure factor model similar to that proposed by Formisano and Teixeira [Eur. Phys. J. E 1, 1 (2000)], but allowing for both Ornstein–Zernike-type composition fluctuations and domainlike structures in the microphase-separated state of the pore liquid. The results indicate that the phase separation in the pores is shifted by ca. 10 K and spread out in temperature. Microphase separation is pictured as a transition from partial segregation at high temperature, due to the strong preferential adsorption of water at the pore wall, to a tube or capsule configuration of the two phases at low temperatures, depending on the overall composition of the pore liquid. Results for samples in which the composition of the pore liquid can vary with temperature due to equilibration with extra-pore liquid are consistent with this picture.
Interaction of alkali metals with perylene-3,4,9,10- tetracarboxylic–dianhydride thin films
Authors: Wüsten J. , Berger S. , Heimer K. , Lach S. , Ziegler Ch.
Published: July 2005

n doping of the molecular organic semiconductor perylene-3,4,9,10-tetracarboxylic–dianhydride (PTCDA) is often achieved by use of alkali metals as dopants. This doping process is commonly performed in two steps. In the first the dopant is evaporated onto the surface of the PTCDA film. As it has been believed that the dopant shows an inhomogeneous diffusion profile through the layer with most of the dopant accumulated in the first few layers, a subsequent annealing step has been performed in order to reach a homogeneous distribution of the dopant in the whole layer. In this paper experimental results concerning chemical composition ((angle resolved) X-ray photoemission spectroscopy, secondary-ion-mass spectrometry, Fourier transform infrared spectroscopy), electronic structure (ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy), as well as electrical properties (conductivity, Seebeck coefficient) are shown before and after doping and before and after annealing. These results suggest that the deposited dopant is redistributed and partially removed during the annealing step. A model for the dopant distribution is suggested.
Gradient-corrected density-functional potential with correct asymptotic behavior: Application to interconfigurational energies in transition-metal atoms
Authors: Ren Chung-Yuan
Published: July 2005

Based upon the optimized effective potential with the self-interaction correction, we present in this paper an alternative gradient-corrected density-functional approximation with the proper long-range behavior of the effective potential. As applied to the study of the interconfigurational energies of the whole transition-metal atoms, the present combination of the gradient-corrected contribution and the modified optimized effective potential lead the s ionization to the excellent agreement with the experiment. The calculated d ionizations and s–d transition energies are also discussed.
Temperature dependence of the photoluminescence and scintillation decay of Yb3+-doped YAlO3 single crystals
Authors: Pejchal J. , Nikl M. , Shim J. B. , Yoshikawa A. , Fukuda T. , Voloshinovskii A. , Múčka V. , Yoon D. H.
Published: July 2005

Temperature dependence of luminescence decay parameters of YbxY1−xAlO3 scintillator within 10(80)–300K is presented for two samples with x=0.02 and 0.3 and using the ultraviolet (x-ray) nanosecond pulsed excitations. Above 180K the scintillation decay is governed by a fast, nearly exponential component in both samples of the decay time of several nanoseconds and all the slower decay components become negligible. Faster scintillation response of the x=0.3 sample is achieved in the whole temperature range with respect to the x=0.02 one due to the concentration quenching of charge-transfer luminescence of Yb3+.
The elasticity of α-helices
Authors: Choe Seungho , Sun Sean X.
Published: July 2005

The elasticity of α-helices is examined using equilibrium molecular-dynamics simulations. From the statistics of curvatures and twists, we compute the elastic moduli of several representative α-helices, both in the presence and absence of aqueous solvent. We discover that the bending modulus (persistence length) of the helices is independent of the amino-acid sequence, although helices in water are slightly softer than in vacuum. The response of the helices under the action of an external force is also computed and compared with continuum mechanics predictions. Within the time scale of our simulation, we show that the properties of α-helices are well reproduced by an elastic and isotropic rod. The persistence length (bending modulus) of most α-helices in water or vacuum is ≈100nm, roughly twice that of DNA.
Surface morphology and optical properties of thin films of thiophene-based binary blends
Authors: Salerno Marco , Blyth Robert Ian Renton , Thompson Julie , Cingolani Roberto , Gigli Giuseppe
Published: July 2005

We report on the relationship between optical and morphological properties of thin films of a blend of thiophene-based monomer and a diamine derivative. This system is of interest as it gives rise to white emission, due to the formation of exciplex energy levels in the solid state. The photoluminescence emission has been collected for different relative concentrations of the two blend components, and the film topography has been mapped correspondingly by means of atomic force microscopy. Along with a complex evolution of the film surface morphology, a significant variation of the emission properties has been observed upon change of the blend composition. In particular, the intensity of the broad low-energy exciplex band turns out to be affected by a balance of two factors, namely, the extension of homogeneous blend film areas, and their effective concentration.
Polymer cholesteric liquid-crystal flake reorientation in an alternating-current electric field
Authors: Kosc T. Z. , Marshall K. L. , Jacobs S. D. , Lambropoulos J. C.
Published: July 2005

The motion of highly dielectric polymer cholesteric liquid crystal (PCLC) flakes suspended in a host fluid can be controlled with an ac electric field. The electric field acts to induce a dipole moment on the flake due to interfacial, or Maxwell–Wagner, polarization. Theoretical modeling of PCLC flakes as oblate spheroids shows that the flakes will reorient to align one of the two major axes parallel to the electric field. The theory also supports the observed dependence of the particle reorientation time on the electric-field magnitude, frequency, and particle shape. A PCLC flake’s orientation determines its ability to reflect light of a specific wavelength and circular polarization. The ability to switch the position of PCLC flakes with an electric field has implications for electro-optic devices and display applications.
A reflection absorption infrared spectroscopy and density-functional theory investigation of methanol dehydrogenation on Rh(111)∕V alloy surfaces
Authors: Koch H. P. , Krenn G. , Bako I. , Schennach R.
Published: July 2005

The dehydrogenation reaction of methanol on a Rh(111) surface, a Rh(111)∕V subsurface alloy, and on a Rh(111)∕V islands surface has been studied by thermal-desorption spectroscopy, reflection absorption infrared spectroscopy, and density-functional theory calculations. The full monolayer of methanol forms a structure with a special geometry with methanol rows, where two neighboring molecules have different oxygen–rhodium distances. They are close enough to form a H-bonded bilayer structure, with such a configuration, where every second methanol C–O bond is perpendicular to the surface on both Rh(111) and on the Rh(111)∕V subsurface alloy. The Rh(111)∕V subsurface alloy is slightly more reactive than the Rh(111) surface which is due to the changes in the electronic structure of the surface leading to slightly different methanol species on the surface. The Rh(111)∕V islands surface is the most reactive surface which is due to a new reaction mechanism that involves a methanol species stabilized up to about 245 K, partial opening of the methanol C–O bond, and dissociation of the product carbon monoxide. The latter two reactions also lead to a deactivation of the Rh(111)∕V islands surface.
Comparative study of O2 dissociation on various metalloporphyrins
Authors: Tsuda Muneyuki , Sy Dy Eben , Kasai Hideaki
Published: July 2005

We investigate O2 interaction with various metalloporphyrins (MnP, FeP, CoP, and NiP) using ab initio calculations based on density-functional theory. We discuss the trends in the activation barriers for the O–O bond cleavage in relation to the geometric, vibrational, electronic, and energetic properties of the systems. Whether the lowest unoccupied molecular orbital–highest occupied molecular orbital (LUMO–HOMO) levels of the metalloporphyrins involve the corresponding metal centers depends on the d orbital occupancies of the metals. We found that activation barriers for the O2 dissociation can be mainly determined from the LUMO–HOMO characters of the metalloporphyrins, and consequently the FeP is the best catalyst with respect to the O2 interaction from adsorption to dissociation.
Electron-beam-induced deformations of SiO2 nanostructures
Authors: Storm A. J. , Chen J. H. , Ling X. S. , Zandbergen H. W. , Dekker C.
Published: July 2005

The imaging beam of a transmission electron microscope can be used to fine tune critical dimensions in silicon oxide nanostructures. This technique is particularly useful for the fabrication of nanopores with single-nanometer precision, down to 2 nm. We report a detailed study on the effect of electron-beam irradiation on apertures with various geometries. We show that, on the same wafer, pores that are smaller than a certain critical size shrink and that larger ones expand. Our results are in agreement with the hypothesis that surface-tension effects drive the modifications. Additionally, we have determined the chemical composition in the pore region before and after modifications and found no significant changes. This result proves that contamination growth is not the underlying mechanism of pore closure.
Spectral and localization properties for the one-dimensional Bernoulli discrete Dirac operator
Authors: de Oliveira César R. , Prado Roberto A.
Published: July 2005

An one-dimensional (1D) Dirac tight-binding model is considered and it is shown that its nonrelativistic limit is the 1D discrete Schrödinger model. For random Bernoulli potentials taking two values (without correlations), for typical realizations and for all values of the mass, it is shown that its spectrum is pure point, whereas the zero mass case presents dynamical delocalization for specific values of the energy. The massive case presents dynamical localization (excluding some particular values of the energy). Finally, for general potentials the dynamical moments for distinct masses are compared, especially the massless and massive Bernoulli cases.
Vibrational assignment and Franck–Condon analysis of the mass-analyzed threshold ionization (MATI) spectrum of CH2ClI: The effect of strong spin-orbit interaction
Authors: Lee Mina , Kim Hyoseok , Lee Yoon Sup , Kim Myung Soo
Published: July 2005

Detailed analysis of the one-photon mass-analyzed threshold ionization (MATI) spectrum of CH2ClI is presented. This includes the determination of the ionization energy of CH2ClI, complete vibrational assignments, and quantum-chemical calculations at the spin-orbit density-functional-theory (SODFT) level with various basis sets. Relativistic effective core potentials with effective spin-orbit operators can be used in SODFT calculations to treat the spin-orbit term on an equal footing with other relativistic effects and electron correlations. The comparison of calculated and experimental vibrational frequencies indicate that the spin-orbit effects are essential for the reasonable description of the CH2ClI+ cation. Geometrical parameters and thus the molecular shape of the cation are greatly influenced by the spin-orbit effects even for the ground state. Calculated geometrical parameters deviate substantially for different basis sets or effective core potentials. In an effort to derive the exact geometrical parameters for this cation, SODFT geometries were further improved utilizing Franck–Condon fit of the MATI spectral pattern. This empirical fitting produced the well-converged set of geometrical parameters that are quite insensitive to the choice of SODFT calculations. The C-I bond length and the Cl-C-I bond angle show large deviations among different SODFT calculations, but the empirical spectral fitting yields 2.191±0.003Å for the C-I bond length and 107.09±0.09° for the Cl-C-I angle. Those fitted geometrical parameters along with the experimental vibrational frequencies could serve as a useful reference in calibrating relativistic quantum-chemical methods for radicals.
Edge-localized mode dynamics and transport in the scrape-off layer of the DIII-D tokamak
Authors: Boedo J. A. , Rudakov D. L. , Hollmann E. , Gray D. S. , Burrell K. H. , Moyer R. A. , McKee G. R. , Fonck R. , Stangeby P. C. , Evans T. E. , Snyder P. B. , Leonard A. W. , Mahdavi M. A. , Schaffer M. J. , West W. P. , Fenstermacher M. E. , Groth M. , Allen S. L. , Lasnier C. , Porter G. D. , Wolf N. S. , Colchin R. J. , Zeng L. , Wang G. , Watkins J. G. , Takahashi T. ,   The DIII-D Team
Published: July 2005

High temporal and spatial resolution measurements in the boundary of the DIII-D tokamak show that edge-localized modes (ELMs) are produced in the low field side, are poloidally localized and are composed of fast bursts (∼20 to 40μs long) of hot, dense plasma on a background of less dense, colder plasma (∼5×1018m−3, 50 eV) possibly created by the bursts themselves. The ELMs travel radially in the scrape-off layer (SOL), starting at the separatrix at ∼450m∕s, and slow down to ∼150m∕s near the wall, convecting particles and energy to the SOL and walls. The temperature and density in the ELM plasma initially correspond to those at the top of the density pedestal but quickly decay with radius in the SOL. The temperature decay length (∼1.2 to 1.5 cm) is much shorter than the density decay length (∼3 to 8 cm), and the latter decreases with increasing pedestal (and SOL) density. The local particle and energy flux (assuming Ti=Te) at the midplane wall during the bursts are 10% to 50% (∼1 to 2×1021m−2s−1) and 1% to 2% (∼20 to 30kW∕m2), respectively, of the LCFS fluxes, indicating that particles are transported radially much more efficiently than heat. Evidence is presented suggesting toroidal rotation of the ELM plasma in the SOL. The ELM plasma density and temperature increase linearly with discharge/pedestal density up to a Greenwald fraction of ∼0.6, and then decrease resulting in more benign (grassier) ELMs.
Linear gyrokinetic calculations of toroidal momentum transport in a tokamak due to the ion temperature gradient mode
Authors: Peeters A. G. , Angioni C. ,   the ASDEX Upgrade Team
Published: July 2005

It is shown from a symmetry in the gyrokinetic equation that for up–down symmetric tokamak equilibria and for uϕ⪢ρυthi∕r (where uϕ is the toroidal velocity, υthi is the thermal ion velocity, ρ is the Larmor radius, and r is the radius of the flux surface), the transport of parallel momentum can be written as the sum of a diffusive and a pinch contribution with no off-diagonal terms due to temperature and pressure gradients. The measured parallel velocity gradient in ASDEX Upgrade [O. Gruber, H.-S. Bosch, S. Günter et al., Nucl. Fusion 39, 1321 (1999)] is insufficient to drive the parallel velocity shear instability. The parallel velocity is then transported by the ion temperature gradient mode. The diffusive contribution to the transport flux is investigated using a linear gyrokinetic approach, and it is found that the diffusion coefficient for parallel velocity transport divided by the ion heat conductivity coefficient is close to 1, and only weakly dependent on plasma parameters.
Oblique shocks in rapid granular flows
Authors: Hákonardóttir Kristin Martha , Hogg Andrew J.
Published: July 2005

The interaction between rapid, free-surface granular flows and deflecting dams is investigated by laboratory experimentation and by the formulation and analysis of a shallow-layer model of the motion. It is found that uniform, downslope flows of grains are deflected to flow parallel to the barrier and that upstream of the barrier, the flow state undergoes an abrupt transition whereby its depth, velocity, and direction of motion change. These oblique shocks are investigated for a range of Froude numbers and for a range of angles between the deflector and the direction of steepest descent. The experimental results are found to be in good agreement with predictions from the shallow-layer theory. Experiments were also conducted with rapid, free-surface flows of water. They reveal not only similarities between the steady deflection patterns of the water and grain flows, but also some differences in the nature of their initial interaction. A simple interpretation for this is given in terms of the relatively high pressures that develop during the initial impact of the incompressible water with the impermeable barrier. Deflecting dams are deployed to defend against large-scale snow avalanches and these results are applied to this situation.
Electrostatic waves in an electron-beam plasma system
Authors: Lu Quanming , Wang Shui , Dou Xiankang
Published: July 2005

A one-dimensional (1D) electrostatic particle-in-cell simulation was performed to study wave excitation processes due to a tenuous electron beam in a plasma system, which is composed of hot and cold electron components. In this case, three types of electrostatic waves are excited, namely, Langmuir waves, electron-acoustic waves, and beam-driven waves. The beam-driven waves have a broad frequency spectrum, which extends from (0.1–0.2)ωpe (ωpe is the electron plasma frequency) to (1.5–2.5)ωpe, with phase speeds close to the speed of the electron beam. The interactions among these waves are investigated for different values of density, temperature, and speed of the electron beam, etc. One special case is that when the density of the electron beam is sufficiently high, compressive solitary waves with bipolar structure of the electric field are generated. The generation mechanism of these solitons is mainly due to the trapping of a fraction of the beam electrons by the potential well of the enhanced beam-driven waves, as shown by the holes that are formed in phase-space plots. The relevance of these excited electrostatic waves to the intense broadband electrostatic noise observed in the Earth’s auroral region is also discussed.
k
-component q-deformed charge coherent states and their nonclassical properties
Authors: Liu X.-M. , Quesne C. , Song F.
Published: July 2005

k -component q-deformed charge coherent states are constructed, their (over)completeness proved and their generation explored. The q-deformed charge coherent states and the even (odd) q-deformed charge coherent states are the two special cases of them as k becomes 1 and 2, respectively. A D-algebra realization of the SUq(1,1) generators is given in terms of them. Their nonclassical properties are studied and it is shown that for k⩾3, they exhibit two-mode q-antibunching, but neither SUq(1,1) squeezing, nor one- or two-mode q-squeezing.
A simple paradigm for active and nonlinear microrheology
Authors: Squires Todd M. , Brady John F.
Published: July 2005

In microrheology, elastic and viscous moduli are obtained from measurements of the fluctuating thermal motion of embedded colloidal probes. In such experiments, the probe motion is passive and reflects the near-equilibrium (linear response) properties of the surrounding medium. By actively pulling the probe through the material, further information about material properties can be obtained, analogous to large-amplitude measurements in (macro-) rheology. We consider a simple model of such systems: a colloidal probe pulled through a suspension of neutrally buoyant bath colloids. We choose a system with hard-sphere interactions but neglect hydrodynamic interactions, which is simple enough to permit analytic solutions, but nontrivial enough to raise issues important for the interpretation of experiments in active and nonlinear microrheology. We calculate the microstructural deformation for arbitrary probe size and pulling rate (expressed as a dimensionless Péclet number Pe). From this, we determine the average retarding effect on the probe due to the microstructure, as well as fluctuations about this average. The high-Pe limit is singular, giving a finite Brownian contribution even in the limit of negligible diffusion. Significantly, different results are obtained for probes driven at constant velocity and constant force. Furthermore, we demonstrate that a probe pulled with an optical tweezer (roughly a harmonic well) can behave as fixed-force, fixed-velocity, or as a mixture of those modes, depending on the strength of the trap and on the pulling speed. More generally, we discuss how these results relate to previous work on the rheology of colloidal suspensions. Not surprisingly, the present theory (which ignores hydrodynamic interactions) gives shear thinning but no shear thickening; we expect that the incorporation of hydrodynamics would result in shear thickening as well. The effective micro- and macro-viscosities, when appropriately scaled, are in semi-quantitative agreement. This seems remarkable, given the rather significant difference in the two methods of measurement. However, for more complicated or unknown materials, where such scaling relations may not be known in advance, the comparison between micro- and macro may not be so favorable, which raises important questions about the relation between micro- and macrorheology. Finally, by analogy with previous work on macrorheology, we propose methods to scale up the present (dilute) theory to account for more concentrated suspensions, and suggest new active microrheological experiments to probe different aspects of suspension behavior.
Highly sensitive detection technique of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy
Authors: Farys V. , Schiavone P. , Polack F. , Idir M. , Bertolo M. , Bianco A. , La Rosa S. , Cautero G. , Vannuffel C. , Quesnel E. , Muffato V.
Published: July 2005

A technique to probe defects buried inside extreme ultraviolet (EUV) masks has been implemented using a dark-field microscopy detection setup. Specific samples have been fabricated to evaluate the sensitivity of this technique. They consist of silicon oxide gratings of a few nanometers height, coated with 40 layer pairs of molybdenum–silicon. We observed images with a good contrast on samples with defects as low as 3nm. However, the imaging mechanism of scanning dark-field microscopy is not linear and can produce image distortions. Conditions of correct imaging have been analyzed, and simulations have been performed that show good agreement with the experimental data. This work opens the way for a better understanding of the capability of at-wavelength inspection technique for EUV mask.
Tunable magnetic fluid grating by applying a magnetic field
Authors: Pu Shengli , Chen Xianfeng , Chen Lijun , Liao Weijun , Chen Yuping , Xia Yuxing
Published: July 2005

A kind of tunable magnetic fluid grating is developed in this letter. The operating principle of the tunable magnetic fluid grating is analyzed theoretically. When the absorption coefficient modulation of the grating is not too large, the energy of the zeroth-order diffracted light can be transferred to that of the higher-order completely and vice versa. Experiments are done to investigate the tunable diffraction properties of the magnetic fluid grating, and the transfer of the energy of the zeroth-order diffracted light to that of the higher-order is apparent.
Hypnotic suggestion reduces conflict in the human brain
Authors: Raz Amir , Fan Jin , Posner Michael I.
Published: July 2005

Many studies have suggested that conflict monitoring involves the anterior cingulate cortex (ACC). We previously showed that a specific hypnotic suggestion reduces involuntary conflict and alters information processing in highly hypnotizable individuals. Hypothesizing that such conflict reduction would be associated with decreased ACC activation, we combined neuroimaging methods to provide high temporal and spatial resolution and studied highly and less-hypnotizable participants both with and without a suggestion to interpret visual words as nonsense strings. Functional MRI data revealed that under posthypnotic suggestion, both ACC and visual areas presented reduced activity in highly hypnotizable persons compared with either no-suggestion or less-hypnotizable controls. Scalp electrode recordings in highly hypnotizable subjects also showed reductions in posterior activation under suggestion, indicating visual system alterations. Our findings illuminate how suggestion affects cognitive control by modulating activity in specific brain areas, including early visual modules, and provide a more scientific account relating the neural effects of suggestion to placebo.
Iron-rich silicates in the Earth's D″ layer
Authors: Mao Wendy L. , Meng Yue , Shen Guoyin , Prakapenka Vitali B. , Campbell Andrew J. , Heinz Dion L. , Shu Jinfu , Caracas Razvan , Cohen Ronald E. , Fei Yingwei , Hemley Russell J. , Mao Ho-kwang
Published: July 2005

High-pressure experiments and theoretical calculations demonstrate that an iron-rich ferromagnesian silicate phase can be synthesized at the pressure–temperature conditions near the core–mantle boundary. The iron-rich phase is up to 20% denser than any known silicate at the core–mantle boundary. The high mean atomic number of the silicate greatly reduces the seismic velocity and provides an explanation to the low-velocity and ultra-low-velocity zones. Formation of this previously undescribed phase from reaction between the silicate mantle and the iron core may be responsible for the unusual geophysical and geochemical signatures observed at the base of the lower mantle.
Fisher's theorems for multivariable, time- and space-dependent systems, with applications in population genetics and chemical kinetics
Authors: Vlad Marcel O. , Szedlacsek Stefan E. , Pourmand Nader , Cavalli-Sforza L. Luca , Oefner Peter , Ross John
Published: July 2005

We study different physical, chemical, or biological processes involving replication, transformation, and disappearance processes, as well as transport processes, and assume that the time and space dependence of the species densities are known. We derive two types of Fisher equations. The first type relates the average value of the time derivative of the relative time-specific rates of growth of the different species to the variance of the relative, time-specific rates of growth. A second type relates the average value of the gradient or the divergence of the relative, space-specific rates of growth to the space correlation matrix of the relative, space-specific rates of growth. These Fisher equations are exact results, which are independent of the detailed kinetics of the process: they are valid whether the evolution equations are linear or nonlinear, local or nonlocal in space and/or time and can be applied for the study of a large class of physical, chemical, and biological systems described in terms of time- and/or space-dependent density fields. We examine the implications of our generalized Fisher relations in population genetics, biochemistry, and chemical kinetics (reaction–diffusion systems). We show that there is a connection between the enhanced (hydrodynamic) transport of mutations induced by population growth and space-specific rate vectors: the velocity of enhanced transport is proportional to the product of the diffusion coefficient of the species and the space rate vector; this relation is similar to a fluctuation–dissipation relation in statistical mechanics.
Celiac Disease: From Inflammation to Atrophy: A Long‐Term Follow‐up Study
Authors: Lähdeaho Marja‐Leena , Kaukinen Katri , Collin Pekka , Ruuska Tarja , Partanen Jukka , Haapala Anna‐Maija , Mäki Markku
Published: July 2005

Objectives:

Celiac disease develops gradually from lymphocytosis, crypt hyperplasia and minor villous atrophy to overt villous atrophy. It IS NOT known how such minor mucosal changes predict eventual celiac disease. The aim of this study was to evaluate the role of intraepithelial lymphocytosis and marginally decreased villous height/crypt depth ratio in the development of overt villous atrophy in a long‐term follow‐up.

Methods:

The authors evaluated 980 small bowel biopsies of children who had previously been studied and found to be histologically negative for celiac disease between 1976 and 1992. Villous height/crypt depth ratio and the number of intraepithelial lymphocytes were measured in these initial biopsies. Cases with slight biopsy changes were identified for further study and sex and age matched subjects with normal biopsies from same group were selected as controls. They all were asked to submit serum samples for gliadin, endomysial and tissue transglutaminase antibodies 8 to 28 years after the initial biopsy. Those with positive screening tests were asked to undergo endoscopy and small intestinal biopsy.

Results:

236 cases with slight changes were identified, and 236 with normal mucosa served as controls; 76 cases and 68 controls participated in the follow‐up study. Ten individuals had positive screening test results. Two new celiac disease patients, one in each group, were found. Four patients in the case group had been diagnosed with celiac disease by routine procedures during the follow‐up. Thus, five cases and one control had developed celiac disease.

Conclusions:

Small bowel mucosal lymphocytosis or slight reduction in villous height/crypt depth ratio are common findings in patients with suspicion of celiac disease. These findings alone are poor predictors of celiac disease.