bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐ and cross‐associations in two‐component mixed polymer gels
Authors: Mao Ching‐Feng
Published: November 2007

The gel properties of two‐component mixed polymer gels are investigated using a cascade model, which assumes that the gel network is formed via the self‐association of one of the two components and the cross‐association of the two components. The effects of the model parameters, such as the equilibrium constants and the functionalities for cross‐associations and self‐associations, on the composition dependence of the modulus and gel point curves are examined to elucidate the contribution of self‐associations to the gel network. The results show that the characteristics of self‐associations become pronounced when the equilibrium constant or the functionality for self‐associations is comparable to that for cross‐associations. The model is applied to analyze the critical gelling concentration data for xanthan/locust bean gum mixed gels, which shows significant self‐associations at high xanthan compositions. The resulting model curves agree well with the experimental data at all temperatures. The analysis of the temperature dependence of the best‐fit equilibrium constant yields values of enthalpy change that are consistent with previous findings. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 80–91, 2008
Plastic deformation behavior of β phase isotactic polypropylene in plane‐strain compression at elevated temperatures
Authors: Lezak E. , Bartczak Z.
Published: November 2007

Isotactic polypropylene (iPP) rich in β crystal modification was deformed by plane‐strain compression at T = 55–100 °C. The evolution of phase structure, morphology, and orientation were studied by DSC, X‐Ray, and SEM. The most important deformation mechanisms found were interlamellar slip operating in the amorphous layers, resulting in numerous fine deformation bands and the crystallographic slip systems, including the (110)[001]β chain slip and (110)[$1{\bar {1}}0$]β transverse slip. Shear within deformation bands leads to β→α solid state phase transformation in contrast to β→smectic transformation observed at room temperature. Newly formed α crystallites deform with an advancing strain by crystallographic slip mechanism, primarily the (010)[001]α chain slip. As a result of deformation and phase transformation within deformation bands β lamellae are locally destroyed and fragmented into smaller crystals. Deformation to high strains, above e = 1, brings further heavy fragmentation of lamellae, followed by fast rotation of crystallites with chain axis towards the direction of flow FD. This process, together with still active crystallographic slip, leads to the final texture with molecular axis of both crystalline β and α phase oriented along FD. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 92–108, 2008
The design of duct venting of gas explosions
Authors: Benedetto Almerinda Di , Russo Paola , Salzano Ernesto
Published: November 2007

Venting systems are useful for the mitigation of accidental explosions. Vent ducts should be used if equipment is located indoors, as NFPA 68 (2007) suggests, for discharging combustion products to safe location. However, the presence of a duct is likely to increase the severity of the explosion with respect to simply vented vessels.

Up to now, no reliable correlations are available for the sizing of ducted vented systems. The only correlation available was developed by Bartknecht in 1993 for gas explosion, also acknowledged by NFPA 68.

In this study, we propose an engineering correlation based on semi‐empirical engineering methodologies, which is able to quantify the relations between geometric properties and the peak pressure occurring in the combustion chamber in the presence of a duct fitted on the vent panel. To this aim, we have regressed all the available experimental data on gas explosion in ducted‐vented vessels. © 2007 American Institute of Chemical Engineers Process Saf Prog, 2008
Monte Carlo simulations of ferroelectric properties based on a microscopic model for PVDF
Authors: Kühn M. , Kliem H.
Published: November 2007

Ferroelectricity can be found in the organic vinylidene fluoride polymer (PVDF) which consists of the polar – [CH2–CF2]n– units. This material shows both orientational and electronic polarisation. Thus, the ferroelectric PVDF can be modelled by an interacting system which consists of permanent dipoles and field‐induced point dipoles. The orthorhombic dipole system is placed between two coplanar electrodes. All electrostatic dipole–dipole interactions are considered and the electrodes are taken into account using the method of image dipoles. Based on thermally activated pro‐ cesses, the permanent dipoles fluctuate in double well potentials according to the Boltzmann statistics. The numerical calculations are based on deterministic local field computations and on weighted probabilistic dynamic Monte Carlo steps. In this paper, we focus on the simulation of typical ferroelectric properties like hysteresis effects, the ferroelectric‐paraelectric phase transition at the Curie‐temperature, and the switching curves from the negative remanent polarisation to positive values. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence spectroscopy of Eu‐implanted zincblende GaN
Authors: Roqan I. S. , O'Donnell K. P. , Trager‐Cowan C. , Hourahine B. , Martin R. W. , Lorenz K. , Alves E. , As D. J. , Panfilova M. , Watson I. M.
Published: November 2007

Cathodoluminescence (CL) and Photoluminescence (PL) of Eu‐implanted zincblende‐GaN (ZB‐GaN:Eu) and wurtzite‐GaN (W‐GaN:Eu) are compared in order to investigate the optical activation of GaN by Eu. The Eu3+ emission spectrum depends critically on the crystal structure of the GaN host; implantation and post‐annealing at 800 °C partially converts implantation‐damaged ZB‐GaN:Eu to W‐GaN:Eu. Selective excitation of PL at wavelengths below the ZB‐GaN band edge reveals a new sharp emission line at 627 nm, together with a number of satellites, which we ascribe to ZB‐GaN:Eu. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Matrix‐assisted laser desorption/ionization mass spectrometry using a visible laser
Authors: Chen Lee Chuin , Asakawa Daiki , Hori Hirokazu , Hiraoka Kenzo
Published: November 2007

Visible matrix‐assisted laser desorption/ionization (VIS‐MALDI) was performed using 2‐amino‐3‐nitrophenol as matrix. The matrix is of near‐neutral pH, and has an optical absorption band in the near‐UV and visible region. A frequency‐doubled Nd:YAG laser operated at 532 nm wavelength was used for matrix excitation and comparisons were made with a frequency‐tripled Nd:YAG laser (355 nm). Visible and ultraviolet (UV)‐MALDI produce similar mass spectra for peptides, polymers, and small proteins with comparable sensitivities. Due to the smaller optical absorption coefficient of the matrix at 532 nm wavelength, the optical penetration depth is larger, and the sample consumption per laser shot in VIS‐MALDI is higher than that of UV‐MALDI. Nevertheless, VIS‐MALDI using 2‐amino‐3‐nitrophenol as matrix may offer a complementary technique to the conventional UV‐MALDI method in applications where deeper laser penetration is required. Copyright © 2007 John Wiley & Sons, Ltd.
A field‐derived oxygen isotope fractionation equation for Salvelinus species
Authors: Storm‐Suke Andrea , Dempson J. Brian , Reist James D. , Power Michael
Published: November 2007

Field‐collected otolith samples of young‐of the‐year Arctic charr (Salvelinus alpinus) and brook charr (Salvelinus fontinalis) and monitored water temperatures were used to estimate a δ18O fractionation equation for the genus Salvelinus. When compared to literature reported equations, the developed fractionation equation had a statistically similar slope but dissimilar intercept. Statistical similarities among fractionation equation slope estimates suggest a common otolith δ18O incorporation response among fish species that may be interpreted as widespread equilibrium otolith δ18O deposition. Statistical dissimilarities among intercept estimates question broad applicability of any single fractionation equation to all fish species and were interpreted here to have biological meaning as a result of known differences in standard metabolic rates among species. Attempts to statistically cross‐validate fractionation equations by prediction of water temperatures used in other fractionation studies indicated significant biases in the range of −7.9 to 6.7°C that preclude the broad use of any single fractionation equation for accurate thermal reconstructions. Differences in equation intercepts and the prevalence of predictive biases do not support the conclusion of previous studies concerning the wide applicability and/or general accuracy of fractionation equations and suggest fractionation equations are best developed at the species‐ or taxon‐specific (e.g., genus) level. Copyright © 2007 John Wiley & Sons, Ltd.
Application of fast gas chromatography/mass spectrometry for the rapid screening of synthetic anabolic steroids and other drugs in anti‐doping analysis
Authors: Mazzarino Monica , Orengia Manuela , Botrè Francesco
Published: November 2007

This paper describes a fast gas chromatographic/mass spectrometric (GC/MS) screening method for the detection, in urine, of 36 xenobiotics (30 synthetic anabolic steroids, four narcotics, one diuretic and one stimulant) excreted free or as glucuro‐conjugates in urine and detectable as trimethylsilyl (TMS) derivatives. These drugs (and/or their urinary metabolites) can be simultaneously extracted by a single liquid/liquid separation step, at alkaline pH, after enzymatic hydrolysis with beta‐glucuronidase and then assayed as TMS derivatives by GC/MS using electron ionisation (EI) and single ion monitoring (SIM) acquisition mode. The total time needed for the GC run is less than 8 min. Good reproducibility of the retention times (CV% <1) and the relative abundances of the diagnostic fragment ions (CV% <10) was observed for all target analytes. The sensitivity of the method is sufficient to match the requirements of the World Anti‐Doping Agency (WADA) for the accredited laboratories, with limits of detection (LODs) that are lower than the corresponding WADA minimum required performance limits (MRPLs) for all target compounds. Copyright © 2007 John Wiley & Sons, Ltd.
Localized identification of shear building with embedded foundation in frequency domain
Authors: Sholeh K. , Vafaie A. , Kaveh A.
Published: November 2007

For studying the behavior of structure in an earthquake, it is advisable to model the structure as a multi‐degrees of freedom system, consisting of numerous single‐degree of freedom substructures and pay attention to soil–structure interaction. System identification is divided into two categories: namely time domain method and frequency domain approach. In this paper, a localized substructure identification of shear building considering the soil–structure interaction is presented using a frequency domain approach. In order to deal with noise‐corrupted data, a spectral smoothing technique with Parzen's window reduction method is adapted. It is shown that better convergence and accuracy can be achieved by the present technique. As a result, it is shown that by taking into account the soil–structure interaction more realistic results can be obtained. Copyright © 2007 John Wiley & Sons, Ltd.
The wind‐induced response characteristics of atypical tall buildings
Authors: You Ki‐Pyo , Kim Young‐Moon
Published: November 2007

A tall building reacts sensitively to winds because the wind force increases according to the height and shape of the building. Various shapes of tall buildings and their aerodynamic characteristics have been studied extensively. For structural design and occupant comfort, the dynamic displacement of a tall building must be maintained within the criteria for acceptable levels of wind‐induced motion. An aerodynamically appropriate building shape needs to be selected at the design stage of a tall building. In this study, wind‐induced vibration responses were investigated, according to the criteria for maximum acceptable displacement and acceleration. Copyright © 2007 John Wiley & Sons, Ltd.
Helminth parasites of the endangered Iberian lynx (Lynx pardinus) and sympatric carnivores
Authors: Millán Javier , Casanova Joan Carles
Published: November 2007

Five critically endangered Iberian lynxes (Lynx pardinus) and 35 other sympatric carnivores (19 feral catsFelis catus, 12 Egyptian mongoosesHerpestes ichneumon, and 4 common genetsGenetta genetta) were analysed for helminths in Sierra Morena and Doñana area (southern Spain).Ancylostoma tubaeforme, which was believed to be harmful for lynx cubs according to a previous study, was present in the only lynx and in 53% of cats analysed in Doñana (80% in adult cats). Other species shared in both areas wereToxocara cati(1 lynx, 31% of cats),Joyeuxiella pasqualei(1 lynx, 21% of cats) andMesocestoidessp. (2 lynxes, 5% of cats). Only one mongoose was parasitized, harbouring larvae of two acantocephalan species not previously reported in the Iberian peninsula (Centrorhynchus(Sphaerirostris)lanceaandCentrorhynchus(Longirostris)undulatus). Feral cats may be a reservoir for hookworms and other helminths affecting the Iberian lynx. In contrast, mongooses and genets may not play a role in the epidemiology of these species.
The pre-Viking age church in East Anglia
Authors: Whitelock Dorothy
Published: November 2007

It is well known that sources for the Anglo-Saxon period are unevenly distributed, and that we are particularly badly off for reliable evidence relating to East Anglia, especially in the period before the Viking raids and settlements. The main reason for this lies in the effects of those raids and settlements, for not only were the monasteries destroyed, but the two East Anglian sees ofDommocand Elmham ceased to exist, and only Elmham was restored, and not, as far as our evidence goes, much before 955. Henceforward there was only one bishop for the whole of East Anglia, though at times it appears to have had a centre for Suffolk at Hoxne as well as one at Elmham. The East Anglian see was transferred to Thetford in 1071–2, and eventually about 1095 to Norwich. With such breaks in continuity it is not to be wondered that no pre-Viking age manuscripts or charters have come down by preservation in East Anglian churches, and it is doubtful how far any information in post-Conquest writers is likely to go back on genuine tradition. What we know about the early church in East Anglia comes from evidence preserved elsewhere, except in as far as the finds at Sutton Hoo have implications concerning the conversion of this kingdom. Our main source is Bede'sHistoria Ecclesiastica, but this can be supplemented by some pieces of evidence from other sources, and it may be worth while to assemble these and study their implications.
MODELING MACROECONOMIC SUBAGGREGATES: AN APPLICATION OF NONLINEAR COINTEGRATION
Authors: JUMAH ADUSEI , KUNST ROBERT M.
Published: November 2007

Many macroeconometric models depict situations where the shares of the major demand aggregates in output are stable over time. The joint dynamic behavior of the considered demand aggregate and output may thus be approximated by a cointegrated vector autoregression. However, the shares of many demand subaggregates in output are rather mobile and changing over time. In order to simultaneously capture the flexibility of the shares of the subaggregates and the long-run constancy of the share of the total aggregate, we consider trivariate systems of two macroeconomic subaggregates and output with error-correction terms that are nonlinear functions of the original variables. The merits of the models are evaluated by means of several forecasting experiments.
Stem cell ageing: does it happen and can we intervene?
Authors: Bellantuono Ilaria , Keith W. Nicol
Published: November 2007

Adult stem cells have become the focus of intense research in recent years as a result of their role in the maintenance and repair of tissues. They exert this function through their extensive expansion (self-renewal) and multipotent differentiation capacity. Understanding whether adult stem cells retain this capacity throughout the lifespan of the individual, or undergo a process of ageing resulting in a decreased stem cell pool, is an important area of investigation. Progress in this area has been hampered by lack of suitable models and of appropriate markers and assays to identify stem cells. However, recent data suggest that an understanding of the mechanisms governing stem cell ageing can give insight into the mechanism of tissue ageing and, most importantly, advance our ability to use stem cells in cell and gene therapy strategies.
Deutsche Version des Strengths and Difficulties Questionnaire (SDQ-Deu):
Authors: Koglin Ute , Barquero Beatriz , Mayer Heidrun , Scheithauer Herbert , Petermann Franz
Published: November 2007

Zusammenfassung. Es werden Befunde zur psychometrischen Qualität der deutschen Fassung des SDQ-Lehrer-/Erzieherfragebogens (T4-16 - SDQ) dargestellt. Dieser wurde an einer Stichprobe von N = 654 Kindern zwischen drei bis fünf Jahren in der Augsburger Längsschnittstudie zur Evaluation des Präventionsprogramms Papilio® (ALEPP) eingesetzt. Die dimensionale Struktur des Fragebogens konnte mittels einer Faktorenanalyse mit Varimaxrotation exzellent repliziert werden. Lediglich zwei Items besitzen Nebenladungen, die höher sind als .40. Die interne Konsistenz (Cronbachs Alpha) ist zufriedenstellend und variiert zwischen α =.73 und α = .86. Insgesamt fallen mit den britischen Grenzwerten ( Goodman, 1997 ) zu viele Kinder in die Kategorien mit erhöhten Werten. Es wird empfohlen, die Grenzwerte für die Skala “Prosoziales Verhalten“ um zwei Punkte zu senken und für die Problemskalen (außer für “Emotionale Probleme“) um einen Punkt heraufzusetzen. Alterseffekte zeigen sich für die Subskala “Hyperaktivität“ und für den Gesamtproblemwert, während sich Geschlechtseffekte für alle Subskalen außer für “Emotionale Probleme“ feststellen lassen. Nach diesen Ergebnissen ist der SDQ als ökonomisches und praktikables Instrument zur Beurteilung des Verhaltens von jungen Kindern zu empfehlen.
Das Münchner Zivilcourage-Instrument (MüZI)
Authors: Kastenmüller Andreas , Greitemeyer Tobias , Fischer Peter , Frey Dieter
Published: November 2007

Zusammenfassung. Zivilcourage und Hilfeverhalten sind Unterformen prosozialen Verhaltens, wobei Zivilcourage mit hohen, Hilfeverhalten dagegen mit niedrigen negativen sozialen Konsequenzen verbunden ist. Bisherige Instrumente erfassten ausschließlich Hilfeverhalten. Um Zivilcourage messbar zu machen, wurde ein Instrument entwickelt, das speziell auf prosoziales Verhalten mit hohen negativen sozialen Konsequenzen abgestimmt ist. Hierbei werden 13 Zivilcourage-Situationen präsentiert und jeweils die Bereitschaft einzugreifen erfasst. Eine explorative Faktorenanalyse (Studie 1) legte eine Drei-Faktoren-Struktur nahe, die mit einer konfirmatorischen Faktorenanalyse bestätigt werden konnte (Studie 2). Ferner wurde die Zivilcourage-Skala an einem verhaltensnahen Maß und an selbst berichtetem Verhalten validiert: Die Zivilcourage-Skala sagte prosoziales Verhalten mit hohen negativen sozialen Konsequenzen (Zivilcourage) besser vorher als eine etablierte Hilfe-Skala, wogegen sich die Hilfe-Skala als besserer Prädiktor für prosoziales Verhalten mit geringen negativen sozialen Konsequenzen (Hilfeverhalten) erwies als die Zivilcourage-Skala. Somit kann die neu entwickelte Skala als ein geeignetes Messinstrument für die Erfassung von Zivilcourage angesehen werden.
Des Guten zuviel: Der Einfluss von Bewältigungsverhalten auf die Bereitschaft zu sozialer Unterstützung
Authors: Antoniw Katja , Borghardt Andrea , Weber Hannelore
Published: November 2007

Zusammenfassung. Ziel dieser Studie war die Überprüfung des Einflusses der Effektivität von Bewältigungsverhalten (perfekt, ausgewogen, ungünstig) und der Art der sozialen Beziehung (Freundin, Bekannte) auf die Bereitschaft zu sozialer Unterstützung im Umgang mit einer alltagsnahen, leistungsbezogenen Stresssituation (Vorbereitung auf eine Prüfung). In einem experimentellen Design wurden N = 132 Teilnehmerinnen schriftlich fiktive Szenarien, in denen das Zielverhalten beschrieben war, vorgegeben und ihre Unterstützungsbereitschaft sowie ihre emotionalen Reaktionen Ärger und Mitleid erfasst. Die Ergebnisse zeigten, dass unabhängig von der Art der sozialen Beziehung Zielpersonen mit einem ausgewogenen und ungünstigen Bewältigungsverhalten eine höhere Bereitschaft zu sozialer Unterstützung auslösten als die Zielperson mit perfektem Bewältigungsverhalten. Die Zielperson mit ungünstiger Bewältigung löste am meisten und die Zielperson mit perfekter Bewältigung am wenigsten Mitleid aus. Mitleid erwies sich neben Ärger als stärkster Prädiktor zur Vorhersage der Unterstützungsbereitschaft.
Distractor Eccentricity and its Effect on Selective Attention
Authors: Chen Zhe
Published: November 2007

Abstract. Previous research has shown conflicting results regarding the effect of distractor eccentricity on selective attention. The present study examines the relationship between a distractor's retinal location and participants' response latencies to a target while holding constant the distribution of attention. In three experiments, the participants searched for a target among several distractors. The retinal location of the critical distractor was manipulated so that it was at either a central or a peripheral location. The results show that all else being equal, an incompatible distractor causes more interference at a peripheral location than at a central location. This distractor eccentricity effect suggests that the visual system can overcome the default bias in the distribution of attention that favors a central stimulus.
The Stroop Effect in English-Japanese Bilinguals
Authors: Sumiya Hiromi , Healy Alice F.
Published: November 2007

Abstract. English-Japanese bilinguals performed a Stroop color-word interference task with both English and Japanese stimuli and responded in both English and Japanese. The Japanese stimuli were either the traditional color terms (TCTs) written in Hiragana or loanwords (LWs) from English written in Katakana. Both within-language and between-language interference were found for all combinations of stimuli and responses. The between-language interference was larger for Katakana LWs (phonologically similar to English) than for Hiragana TCTs, especially with Japanese responses. The magnitude of this phonological effect increased with self-rated reading fluency in Japanese. Overall responding was slower and the Stroop effect larger with English than with Japanese stimuli. These results suggest that unintentional lexical access elicits automatic phonological processing even with intermediate-level reading proficiency.
A photochemical modeling study of ozone and formaldehyde generation and budget in the Po basin
Authors: Liu L. , Andreani‐Aksoyoglu S. , Keller J. , Ordóñez C. , Junkermann W. , Hak C. , Braathen G. O. , Reimann S. , Astorga‐Llorens C. , Schultz M. , Prévôt A. S. H. , Isaksen I. S. A.
Published: November 2007

In this work, a photochemical dispersion model, CAMx (Comprehensive Air quality Model with eXtensions) was used to simulate a high ozone episode observed in the Po basin during the 2003 FORMAT (Formaldehyde as a Tracer of Oxidation in the Troposphere) campaign. The study focuses on formaldehyde and ozone, and a budget analysis was set up for interpreting the importance of different processes, namely emission, chemistry, transport and deposition, for three different areas (urban, downwind, suburban) around the Milan metropolitan region. In addition, a sensitivity study was carried out based on 11 different VOC emission scenarios. The results of the budget study show that the strongest O3 production rate (4 ppbv/hour) occurs in the downwind area of the city of Milan, and that accumulated O3 is transported back to Milan city during nighttime. More than 80% of the HCHO concentration over the Milan metropolitan region is secondary, i.e., photochemically produced from other VOCs. The sensitivity study shows that the emissions of isoprene are not, on average, a controlling factor for the peak concentrations of O3 and HCHO over the model domain because of very few oak trees in this region. Although the paraffinic (PAR) emissions are fairly large, a 20% reduction of PAR yields only 1.7% of HCHO reduction and 2.7% reduction of the O3 peak. The largest reduction of O3 levels can be obtained by reduced xylene (XYL) emissions. A 20% reduction of the total anthropogenic VOC emissions leads to 15.5% (20.3 ppbv) reduction of O3 peak levels over the Milan metropolitan region.
Cloud‐fraction‐dependent bias in satellite liquid water path retrievals of shallow, non‐precipitating marine clouds
Authors: Horváth Ákos , Gentemann Chelle
Published: November 2007

This study compares Wentz microwave liquid water path retrievals with MODIS and MISR optical estimates in shallow, non‐precipitating marine clouds. In overcast conditions, the microwave and optical estimates are comparable; however, as cloud fraction decreases microwave retrievals strongly and increasingly overestimate optical ones. This positive microwave bias cannot be explained neither by the elimination of negative values in the operational Wentz dataset, nor by the somewhat reduced sensitivity of MODIS cloud detection to small clouds.
Cascadia tremor polarization evidence for plate interface slip
Authors: Wech Aaron G. , Creager Kenneth C.
Published: November 2007

New seismic measurements of the repeated phenomenon of Episodic Tremor and Slip in northern Cascadia indicate identical source processes of tremor and slow slip. Predicted polarization directions of upgoing S‐waves radiated from shear slip on the plate interface align with the relative motion between the Juan de Fuca and North American plates. Seismic observations from small‐aperture array data on the Olympic Peninsula of the Cascadia subduction zone show uncharacteristically stable linear particle motion coincident with the passage of tremor sources beneath the array. The azimuth of this horizontal ground motion matches expected polarizations from slip on the plate interface. This finding suggests that Cascadia tremor is shear slip on the plate interface, implying that, as in Japan, geodetically observed slow slip and seismically observed tremor are manifestations of the same phenomenon.
Multiple equilibria in a single‐column model of the tropical atmosphere
Authors: Sobel A. H. , Bellon G. , Bacmeister J.
Published: November 2007

A single‐column model run under the weak temperature gradient approximation, a parameterization of large‐scale dynamics appropriate for the tropical atmosphere, is shown to have multiple stable equilibria. Under conditions permitting persistent deep convection, the model has a statistically steady state in which such convection occurs, as well as an extremely dry state in which convection does not occur. Which state is reached depends on the initial moisture profile.
Reconstructing the quasi‐biennial oscillation back to the early 1900s
Authors: Brönnimann Stefan , Annis Jeffrey L. , Vogler Christian , Jones Phil D.
Published: November 2007

The quasi‐biennial oscillation (QBO) is important for understanding the dynamical and chemical variability of the global stratosphere. Currently available wind data from the equatorial stratosphere extend back to 1953. Here we present reconstructions of the QBO extending back to 1900 that can be used to constrain climate model simulations. The reconstructions are based on historical pilot balloon data as well as hourly sea‐level pressure (SLP) data from Jakarta, Indonesia. The latter were used to extract the signal of the solar semi‐diurnal tide in the middle atmosphere, which is modulated by the QBO. The reconstructions are in good agreement with the QBO signal extracted from historical total ozone data extending back to 1924. Further analyses suggest that the maximum phases of the QBO are captured relatively well after about 1910.
Spectral features of SKR observed by Cassini/RPWS: Frequency bandwidth, flux density and polarization
Authors: Galopeau Patrick H. M. , Boudjada Mohammed Y. , Lecacheux Alain
Published: November 2007

We report on an analysis about the spectral shape of the Saturnian kilometric radiation (SKR) recorded by the RPWS/HFR experiment onboard the Cassini spacecraft. The SKR envelope is found to be very variable in timescales covering a large range, from hours to days. Despite this change, we proceed to a classification of the shape in the frequency range from 3.5 kHz to 1.2 MHz taking into consideration the phenomenology and the state polarization of the radio wave. In the considered SKR bandwidth, we make a distinction between three principal components having different spectral shapes and degrees of total polarization. The well‐known SKR component exhibits a degree of circular polarization close to 100% and emits in the frequency range from 80–90 kHz to 800–900 kHz. The two other components become visible in the lower and higher parts of the HFR receiver and show a weak linear polarization less than 10%. The generation of the SKR is linked to particles precipitations in the auroral regions, nevertheless the variability of the spectral shape is still subject of investigation. The present analysis is confronted with the theoretical model of SKR envelope spectrum proposed by Galopeau et al. (1989).
Horizontal amplitude and phase structure of low‐latitude Pc 3 pulsations around the dawn terminator
Authors: Tanaka Y.‐M. , Yumoto K. , Yoshikawa A. , Itonaga M. , Shinohara M. , Takasaki S. , Fraser B. J.
Published: November 2007

The horizontal spatial structure of Pc 3 pulsations observed at low geomagnetic latitude (22–46°) around dawn is studied statistically using data acquired by the Circum‐pan Pacific Magnetometer Network (CPMN). It is found that while the phase of the H component of low‐latitude Pc 3 pulsations remains largely unchanged with the passing of dawn, the D component undergoes a phase shift of ca. 180°. This phase variation across dawn is related to the abrupt change in the major axis orientation of polarization ellipses observed in previous studies. Both the H and D components have higher amplitude after dawn than before dawn. This horizontal amplitude and phase structure is well explained by the response of a nonuniform ionosphere around dawn to incident Alfvén waves, where the secondary electric field caused by charge accumulation at the dawn terminator plays an important role in deformation of the current system. Enhancement of the D/H ratio is also observed just after dawn at very low latitudes (22°). As Alfvén waves are not excited efficiently at very low geomagnetic latitudes, including the magnetic equator, the observed horizontal structure in such regions may be due to a large‐scale current system originating at higher latitudes.
Suppression of inflammatory and immune responses by the A2Aadenosine receptor: an introduction
Authors: Palmer T M , Trevethick M A
Published: November 2007

The purine nucleoside adenosine has been described as a ‘retaliatory metabolite’ by virtue of its ability to function in an autocrine manner to modify the activity of a range of cell types following its extracellular accumulation during cell stress or injury. These effects are largely protective and are triggered by the binding of adenosine to any of four G‐protein‐coupled adenosine receptors. Most of the anti‐inflammatory effects of adenosine have been assigned to the adenosine A2Areceptor subtype, which is expressed in many immune and inflammatory cells. In this brief article, we will outline the growing evidence to support the hypothesis that the development of agonists selective for the A2Areceptor is an effective strategy for suppressing the exaggerated inflammatory responses associated with many diseases by virtue of the receptor's ability to inhibit multiple pro‐inflammatory signalling cascades.

British Journal of Pharmacology(2008)153, S27–S34; doi:10.1038/sj.bjp.0707524; published online 19 November 2007
Intracellular machinery for the transport of AMPA receptors
Authors: Esteban J A
Published: November 2007

AMPA‐type glutamate receptors are one of the most dynamic components of excitatory synapses. Their regulated addition and removal from synapses leads to long‐lasting forms of synaptic plasticity, known as long‐term potentiation (LTP) and long‐term depression (LTD). In addition, AMPA receptors reach their synaptic targets after a complicated journey involving multiple transport steps through different membrane compartments. This review summarizes our current knowledge of the trafficking pathways of AMPARs and their relation to synaptic function and plasticity.

British Journal of Pharmacology(2008)153, S35–S43; doi:10.1038/sj.bjp.0707525; published online 19 November 2007
Platelet‐dependent accumulation of leukocytes in sinusoids mediates hepatocellular damage in bile duct ligation‐induced cholestasis
Authors: Laschke M W , Dold S , Menger M D , Jeppsson B , Thorlacius H
Published: November 2007

Background:

Although it is well known that extrahepatic cholestasis induces liver damage, the mechanisms are still not completely understood. The aim of the present study was to evaluate the role of platelets and P‐selectin in cholestasis‐induced liver injury.

Experimental approach:

C57BL/6 mice underwent bile duct ligation (BDL) and pretreatment with an anti‐GP1bα antibody, which depletes platelets, an anti‐P‐selectin antibody or a control antibody. Hepatic platelet and leukocyte recruitment as well as microvascular perfusion were determined by intravital fluorescence microscopy.

Key results:

BDL caused significant liver damage and sinusoidal perfusion failure. BDL further induced hepatic platelet accumulation with widespread intravascular platelet aggregates, increased platelet adhesion in postsinusoidal venules and massive platelet accumulation in liver sinusoids. Administration of the anti‐GP1bα antibody reduced systemic platelet count by 90%. Depletion of platelets in BDL mice not only abolished accumulation and adhesion of platelets in sinusoids and venules but also restored sinusoidal perfusion and reduced liver enzymes by more than 83%. Platelet depletion further reduced BDL‐associated sinusoidal leukocyte accumulation by 48% although leukocyte–endothelium interactions in venules were not affected. Immunoneutralization of P‐selectin also inhibited hepatic microvascular accumulation of platelets and leukocytes, and protected against cholestasis‐provoked hepatocellular damage.

Conclusions and implications:

Platelets play an important role in BDL‐induced liver injury by promoting leukocyte recruitment and deteriorating microvascular perfusion. Moreover, our findings demonstrate that cholestasis‐induced accumulation of platelets is mediated by P‐selectin. Thus, targeting platelet accumulation may be a useful strategy against liver damage associated with obstructive jaundice.

British Journal of Pharmacology (2008) 153, 148–156; doi:10.1038/sj.bjp.0707578; published online 19 November 2007
Collective vibrations in cluster models for semiconductor surfaces: Vibrational spectra of acetylenyl and methylacetylenyl functionalized Si(111)
Authors: Ferguson Glen Allen , Raghavachari Krishnan
Published: November 2007

The geometries and harmonic vibrational frequencies of the acetylenyl and methylacetylenyl functionalized Si(111) surfaces are investigated using quantum chemical calculations. The vibrational spectra are computed using a previously introduced method whereby the collective vibrational modes that correspond to the vibrations of the infinite periodic system are derived from modest sized cluster models. Our predictions should be useful for the interpretation of the experimental spectra when they become available. The symmetry elements of the methylacetylenyl Si(111) surface that are derived from the space group of the optimized structure and a vibrational mode resulting from photon-adsorbate coupling are explored.
Operation of a frequency-narrowed high-beam quality broad-area laser by a passively stabilized external cavity technique
Authors: Bayram S. B. , Coons R. W.
Published: November 2007

The average spectral bandwidth of a 2W broad-area diode laser was narrowed to 5GHz with wavelength tunability of up to 12nm at a center wavelength of 790nm with the use of a Littman-Metcalf external cavity in a displaced configuration. The use of lens and combined lens-laser transformation systems allowed precise alignment of the beam shaping optics, which led to significant improvements of the beam quality and an enhanced suppression of the free-running laser modes. We characterize the spatial beam quality of our external cavity diode laser by measuring the M2 quality factor and relate this to our measured bandwidths. Our external cavity can be configured over a range of cavity lengths and is modular in design, enabling access to a broad frequency spectrum for a wide range of applications that require high-power, narrow bandwidth operation.
A Eulerian model for large-eddy simulation of concentration of particles with small Stokes numbers
Authors: Shotorban Babak , Balachandar S.
Published: November 2007

In order to conduct the large-eddy simulation (LES) of particle-laden turbulent flows through a two-fluid approach, a model is proposed for the concentration of particles using an equilibrium assumption in which the Eulerian velocity of particles can be expressed in terms of the velocity and acceleration of the fluid phase as well as the gravitational acceleration through an asymptotic series expansion. This assumption is valid only for small Stokes numbers. The assessment of the model is carried out in forced isotropic turbulence. The LES model results well compared against results obtained by direct numerical simulation.
Drift in supported membranes
Authors: Prasad Ashok , Kondev Jané , Stone Howard A.
Published: November 2007

An object moving in a fluid transports the fluid along the direction of its motion. Using the concept of drift, i.e., the net motion of a small volume of fluid or a tracer particle due to a moving body, we quantify this entrainment for an inclusion in a supported lipid bilayer membrane. Our analysis demonstrates that a moving object in a supported membrane transports a small volume of fluid by a significant distance only when the initial position of the fluid volume in question is within a distance ξ from the line of motion, where ξ is the screening length of the membrane. The total area swept out by a line of such fluid volume elements, initially at rest and oriented perpendicular to the direction of motion, is the drift area. We show that the drift area is related quadratically to the screening length. These calculations suggest that dynamic domains of entrained lipids of size ξ form spontaneously around moving objects in supported membranes due to hydrodynamic interactions. This effect is potentially important for transport processes in biological and artificial membranes.
Atmospheric effect of air, N2, O2, and water vapor on the ionization energy of titanyl phthalocyanine thin film studied by photoemission yield spectroscopy
Authors: Honda Masato , Kanai Kaname , Komatsu Kenichi , Ouchi Yukio , Ishii Hisao , Seki Kazuhiko
Published: November 2007

The effect of atmospheric gases on the ionization energy (I) of titanyl phthalocyanine thin film was investigated by an apparatus of photoemission yield spectroscopy developed for the measurements of I for the same specimen both in vacuum and under gaseous atmosphere. It was found that the value of I is affected by the exposure to various ambient gases (i.e., air, nitrogen, and oxygen of 1 atm, and water vapor corresponding to 27% relative humidity at 300 K), and that the effect strongly depends on the gas. The ionization energies in vacuum could be determined as the onset I0 of the cube-root plot of the photoemission yield as a function of photon energy. When the sample was exposed to gases, the cube-root plot still gives an onset, but often a long tail at the low-energy side with another onset It was also observed. The first exposure to air did not affect both I0 and It much, while the following evacuation-exposure cycles caused mostly reversible decrease and increase of I0 and It by about 0.2 and 0.4 eV, respectively. Among the examined constituent gases of air, nitrogen was found to hardly affect both I0 and It except for the small temporal decrease by 0.06 eV at the first exposure. Similar trends of the change of I0 and It with those for air were found for oxygen, with the amplitudes of mostly reversible change being 0.1 eV for I0 and 0.2 eV for It. Overlapped with these changes, a slow decrease of both I0 and It, was also observed with a slope of 0.01 eV per day. For water, the trends were mostly similar with O2, except that (1) the first exposure to water vapor showed small and large changes in I0 (0.03 eV increase) and It (0.4 eV decrease) and (2) the amplitudes of the mostly reversible change of I0 (0.3 eV) and It (0.05 eV) were much larger and smaller than those for O2, respectively. A long-term decrease was also observed with a slope of 0.04 eV per day. These results indicate that the atmospheric effect by ambient air on I is mainly caused by water vapor, although oxygen also makes significant contribution. Since the observed trends are rather complex, there seem to be multiple factors affecting I, which is the energy difference between the vacuum level and the highest occupied molecular orbita. Possible microscopic mechanisms of the observed variation of I on these levels are also discussed in terms of the energy change in these levels.
Thermoelectric properties of p-type Fe-doped TiCoSb half-Heusler compounds
Authors: Wu Ting , Jiang Wan , Li Xiaoya , Zhou Yanfei , Chen Lidong
Published: November 2007

TiFe x Co 1 − x Sb half-Heusler materials with randomly distributed TiO2 particles have been synthesized by arc melting and annealing. Thermoelectric properties were measured in the temperature range of ∼300–850 K. TiCoSb shows n-type conduction, while TiFexCo1−xSb transfers to p-type conduction when x≥0.01. The electrical conductivity of p-type TiFexCo1−xSb increased with increasing Fe content. The maximum Seebeck coefficient reached about 300 μV/K at 850 K for x=0.15. Since Fe powder contained a trace of Fe2O3, a small amount of TiO2 particles formed during the synthesis process. The lattice thermal conductivity dramatically decreased with increasing Fe content, which was mostly caused by the introduction of in situ formed TiO2 particles, as well as the effects of mass fluctuation and strain field fluctuation due to the substitution of Fe to the Co site. The dimensionless figure of merit (ZT=S2σT/κ) was significantly improved over the whole temperature region, and a maximum ZT value of 0.45 has been obtained for the composition of TiFe0.15Co0.85Sb at 850 K.
Application of nonlinear dynamics to monitoring progressive fatigue damage in human cortical bone
Authors: Ulrich T. J. , Johnson Paul A. , Müller Marie , Mitton David , Talmant Maryline , Laugier Pascal
Published: November 2007

In this work, the results of applying nonlinear dynamics to study progressive material fatigue in human bone are described. Material nonlinear dynamical response has been shown to be associated with mechanical damage. The progressive mechanical damage experiments were conducted in cortical bone extracted from a human femur. After each damage step, the material dynamical nonlinear response was measured by applying wave modulation and extracting a nonlinear parameter proportional to the sideband amplitude. The nonlinear parameter increases rapidly with damage step, indicating increased damage after the initial cycling procedure, while the quasistatic stiffness taken from the cycling experiments shows little change.
Strain effects and microstructural evolution in Ge–Si system materials prepared by ion implantation and by ultrahigh vacuum chemical vapor deposition
Authors: Tu Hailing , Xiao Qinghua , Ma Tongda
Published: November 2007

Appropriately utilizing some microstructures may be very helpful to acquire desirable Ge–Si system materials. In this work, the Ge–Si system materials have been prepared either by ion implantation or ultrahigh vacuum chemical vapor deposition (UHVCVD). The interesting microstructures including half-loop dislocations, SiGe nanoclusters, and dislocation dipoles have been found in these two kinds of Ge–Si system materials. It is demonstrated that the evident surface strain state and adequate surface layer quality have been realized by employing these microstructures. Compared with the dipole dislocations in the Ge–Si systems deposited by UHVCVD on the compliant silicon on insulator, the half-loop dislocations and the SiGe nanoclusters induced by Ge ion implantation and subsequent annealing can relax the SiGe layer more effectively and lead to relatively large strain in the surface silicon. It may provide some new approaches to the control of misfit strains for fabricating desirable Ge–Si system materials.
Dynamics of magnetic vortex core switching in Fe nanodisks by applying in-plane magnetic field pulse
Authors: Xiao Q. F. , Rudge J. , Girgis E. , Kolthammer J. , Choi B. C. , Hong Y. K. , Donohoe G. W.
Published: November 2007

We investigated the influence of the magnetic field pulse parameters and the size of the Fe element to the vortex core switching by micromagnetic modeling. When the magnetic field pulse with an appropriate strength and duration is applied to 30nm thick Fe circular disks with diameters between 100nm and 1μm, the vortex configuration is perturbed away from the equilibrium state, and the circular symmetric distribution of the in-plane magnetization around the vortex core deforms. This leads to the creation of a new vortex core with the opposite polarity and an antivortex. With increasing time, the vortex-antivortex pair annihilates. As a result of the annihilation, a single vortex core with opposite polarity remains and a vortex core switch is realized. The process of core switching, however, strongly depends on the amplitude and duration of the magnetic pulse.
White luminescence from silica glass containing red/green/blue luminescent nanocrystalline silicon particles
Authors: Sato Keisuke , Kishimoto Naoki , Hirakuri Kenji
Published: November 2007

Silica glasses containing blue/green/red luminescent nanocrystalline silicon (nc-Si) particles that consist of monolayer and/or three-layer structures were fabricated by a radio-frequency sputtering technique and postannealing treatment. These silica glasses showed very broad luminescence spectra with a peak at 460 nm (blue light), 550 nm (green light), and 800 nm (red light). When these samples were irradiated by using a xenon lamp with an optical bandpass filter of 313 nm, the luminescence colors from these silica glasses were a white light. The white luminescence of the sample with the three-layer structure exhibited the high luminance value of 1.5 cd/m2. This value was ascribed to the adjustment of sizes and densities of blue/green/red luminescent nc-Si particles, and the lowering of densities of Pb centers (nonradiative recombination centers) at the nc-Si particle/silica glass interface layer.