bluuebunny/crossref_metadata_2025 huggingface dataset:
S100B promotes the proliferation, migration and invasion of specific brain metastatic lung adenocarcinoma cell line
Authors: Jiang Weifeng , Jia Qianxin , Liu Lili , Zhao Xinwen , Tan Aixing , Ma Ningqiang , Zhang Helong
Published: August 2011

Brain metastasis frequently occurs in cancer patients and is associated with a poor prognosis. We previously reported that S100B was highly expressed in PC14/B, a specific brain metastatic lung adenocarcinoma cell line, which suggests that it is associated with brain metastasis of lung cancer. However, the role of S100B in brain metastasis remains to be elucidated. In this study, using PC14/B cell line, we found that siRNA mediated depletion of S100B in PC14/B cells led to notable differences in cell proliferation, apoptosis, cell cycle progression, colony formation ability, cell migratory and invasive activity compared with the mock‐transfected cells. Therefore, our data suggest that S100B promotes the brain metastasis of lung adenocarcinoma by promoting cell proliferation, preventing apoptosis and increasing cell migration and invasion. Copyright © 2011 John Wiley & Sons, Ltd.
Comparison of population‐genetic structuring in congeneric kelp‐ versus rock‐associated snails: a test of a dispersal‐by‐rafting hypothesis
Authors: Nikula Raisa , Spencer Hamish G. , Waters Jonathan M.
Published: August 2011

Phylogeographic studies indicate that many marine invertebrates lacking autonomous dispersal ability are able to achieve trans‐oceanic colonization by rafting on buoyant macroalgae. However, less is known about the impact of rafting on on‐going population‐genetic connectivity of intertidal species associated with buoyant macroalgae. We hypothesize that such species will have higher levels of population‐genetic connectivity than those exploiting nonbuoyant substrates such as rock. We tested this hypothesis by comparing nuclear multilocus population‐genetic structuring in two sister topshell species, which both have a planktonic larval phase but are fairly well segregated by their habitat preference of low‐tidal bull‐kelp holdfasts versus mid‐to‐low tidal bare rock. We analyzed population samples from four sympatric sites spanning 372 km of the east coast of southern New Zealand. The sampled region encompasses a 180 km wide habitat discontinuity and is influenced by a stable, northward coastal current. The level of connectivity was high in both species, and neither of them showed significant correlation between genetic and geographic distances. However, a significant negative partial correlation between genetic distance and habitat discontinuity was found in the rock‐associated species, and estimates of migrant movement between sites were somewhat different between the two species, with the kelp‐associated species more often yielding higher estimates across the habitat discontinuity, whereas the rock‐associated species more often exhibited higher estimates between sites interspersed by rock habitats. We conclude that for species with substantial means of autonomous dispersal, the most conspicuous consequence of kelp dwelling may be enhanced long‐distance dispersal across habitat discontinuities rather than a general increase of gene flow.
Phenylethanol derivatives as triplet sensitizers for 1‐azidoadamantane
Authors: Upul Ranaweera Ranaweera R. A. , Rajam Sridhar , Gudmundsdottir Anna D.
Published: August 2011

Laser flash photolysis, phosphorescence and density functional calculations were used to characterize the triplet excited states of phenylethanol derivatives 1, 2, 3 and 4. In acetonitrile, the triplet excited states of these alcohols were formed with rate constants on the order of ~107 s–1 and decayed with rate constants between 105 and 106 s–1. The energies of these triplet excited states were between 80 and 83 kcal/mol. Furthermore, 3 can be used as a triplet sensitizer for alkyl azides to form triplet nitrene intermediates. Copyright © 2011 John Wiley & Sons, Ltd.
Investigation of indiscriminate nudging and predictability in a nested quasi‐geostrophic model
Authors: Omrani Hiba , Drobinski Philippe , Dubos Thomas
Published: August 2011

In this work, we consider the effect of indiscriminate nudging time on an idealized high‐resolution global model (GM) and limited‐area model (LAM) simulations. The model used is a two‐layer quasi‐geostrophic model on the beta‐plane.

The effect of nudging is studied as a function of the predictability time, following a ‘Big Brother’ experimental approach: a high‐resolution ‘global’ model is used to generate a ‘reference run’. These fields are filtered afterwards to remove small scales and provide the coarse‐resolution fields which are used to drive the high‐resolution GM and the LAM. Comparison of the reference fields and the high‐resolution runs over the same region allows the estimation of the ability of the high‐resolution GM and LAM to regenerate the removed small scales. This fully nonlinear set‐up mimics the configuration used for regional high‐resolution atmospheric modelling.

For the high‐resolution GM, the results show that the behaviour of the nudged model depends primarily on the ratio of the nudging time to the predictability time. When the nudging time is very small compared to the predictability time, the model reproduces the large scale used to drive the model. On the other hand, if the nudging time is close to or larger than the predictability time, the nudging effect is weak and both large and small scales are poorly reproduced compared to the reference fields. The best result is obtained with a nudging time close to half the predictability time. This technique clearly improves the model capacity to reproduce the reference fields.

For the high‐resolution LAM, our results show that for a sufficiently small domain the simulation is largely controlled by the lateral boundary conditions (LBCs) and is quasi‐insensitive to nudging. However, if the domain size exceeds a few Rossby radii, the high‐resolution LAM becomes sensitive to initial conditions and the control exerted by LBCs becomes insufficient to prevent a divergence from the driving fields. Although the reconstructed fine scales are significantly damped, they are surprisingly well correlated to their reference values in a deterministic sense, not a statistical sense. Copyright © 2011 Royal Meteorological Society
Insomnia in a Displaced Population is Related to War‐Associated Remembered Stress
Authors: Basishvili Tamar , Eliozishvili Marine , Maisuradze Lia , Lortkipanidze Nani , Nachkebia Nargiz , Oniani Tengiz , Gvilia Irma , Darchia Nato
Published: August 2011

Although traumatic events are presumed to cause sleep disturbances, particularly insomnia, sleep in populations subjected to forced displacement has received little attention. The present study examined the prevalence of insomnia and associated factors in internally displaced persons (IDPs) from Abkhazia 15 years after displacement to Tbilisi. Detailed subjective information about sleep–wake habits, sleep‐related and stress‐related parameters were obtained from 87 IDPs categorized into good sleepers and insomniacs. The Insomnia Severity Index, Perceived Stress Scale and Beck Depression Inventory were administered. The incidence of insomnia was 41.4%. The majority of insomniacs strongly believed that war‐related stress accounted for the onset of their insomnia. Stepwise regression (95% confidence interval) revealed four variables significantly associated with insomnia status: self‐estimated influence of war related stress (odds ratio (OR) = 2.51), frequency of nightmares (OR = 1.6), Perceived Stress Scale score (OR = 1.14) and Beck Depression Inventory score (OR = 1.12). Insomnia in IDPs was strongly related to war‐associated remembered stress. ‛Over thinking’ about major stress exposure enhanced IDPs' vulnerability to insomnia. These findings have implications for the management of insomnia and associated impairment of daytime functioning in IDPs. Copyright © 2011 John Wiley & Sons, Ltd.
The development and evaluation of a novel Internet-based computer program to assess previous-day dietary and physical activity behaviours in adults: the Synchronised Nutrition and Activity Program for Adults (SNAPA™)
Authors: Hillier Frances C. , Batterham Alan M. , Crooks Sean , Moore Helen J. , Summerbell Carolyn D.
Published: August 2011

The Synchronised Nutrition and Activity Program for Adults (SNAPA™) was developed to address the need for accurate, reliable, feasible, inexpensive and low-burden methods for assessing specific dietary and physical activity behaviours in adults. Short-term test–retest reliability of SNAPA™ was assessed in forty-four adults (age 41·4 (sd17·3) years) who completed SNAPA™ twice in 1 day. Concurrent validity against direct dietary observation and combined heart rate and accelerometry was assessed in seventy-seven adults (age 34·4(sd11·1) years). Test–retest reliability revealed no substantial systematic shifts in mean values of the outcome variables: percentage of food energy from fat (% fat), number of portions of fruit and vegetables (FV) and minutes of moderate-to-vigorous physical activity (MVPA). For lunchtime dietary intake, the mean match rate between food items reported using SNAPA™ and those observed was 81·7 %, with a phantom rate of 5·6 %. Pearson's correlations between SNAPA™ and the reference methods ranged from 0·27 to 0·56 for % fat, FV portions and minutes of MVPA. For % fat and FV intake, there was no fixed or proportional bias, and mean differences between the methods (SNAPA™ − reference) were 5·1 % and 0 portions, respectively. For minutes of MVPA, a fixed bias of − 28 min was revealed when compared with all minutes of MVPA measured by combined heart rate and accelerometry, whereas a proportional bias (slope 1·47) was revealed when compared with minutes carried out in bouts ≥ 10 min. SNAPA™ is a promising tool for measuring specific energy balance behaviours, though further work is required to improve accuracy for physical activity behaviours.
Auditory hallucinations in childhood: associations with adversity and delusional ideation
Authors: Bartels-Velthuis A. A. , van de Willige G. , Jenner J. A. , Wiersma D. , van Os J.
Published: August 2011

Background

Previous work suggests that exposure to childhood adversity is associated with the combination of delusions and hallucinations. In the present study, associations between (severity of) auditory vocal hallucinations (AVH) and (i) social adversity [traumatic experiences (TE) and stressful events (SE)] and (ii) delusional ideation were examined.

Method

A baseline case-control sample of children with and without AVH were re-assessed on AVH after 5 years and interviewed about the experience of social adversity and delusions.

Results

A total of 337 children (mean age 13.1 years, s.d.=0.5) were assessed: 40 children continued to hear voices that were present at baseline (24%, persistent group), 15 heard voices only at follow-up (9%, incident group), 130 children no longer reported AVH that were present at baseline (remitted group) and 152 never heard voices (referent group). Both TE and SE were associated with both incident and persistent AVH, as well as with greater AVH severity and delusional ideation at follow-up. In addition, the combination of AVH and delusions displayed a stronger association with TE and SE compared with either AVH or delusions alone.

Conclusions

Early childhood AVH are mostly benign and transitory. However, experience of social adversity is associated with persistence, severity and onset of new AVH closer to puberty, and with delusional ideation.
Foreign live-in domestic workers as caretakers of older Kuwaiti men and women: socio-demographic and health correlates
Authors: SHAH NASRA , BADR HANAN , SHAH MAKHDOOM
Published: August 2011

Ageing of the population is posing new challenges for caretakers. This paper aims to examine: (a) age and gender differences in care provided by a domestic worker versus a family member in the performance of activities of daily living (ADL); (b) socio-demographic correlates of care during illness; and (c) self-reported physical, functional, and psychological health status in relation to care-giver. A cross-sectional household survey was conducted among 2,487 Kuwaiti nationals aged 50 years or older. This paper focuses on persons aged 70 or more. We found that domestic workers provided care to 28 per cent of men and 58 per cent of women who needed assistance with ADL; and to 14 per cent men and 51 per cent women during illness. These respondents ranked poorer on several health indicators and reported higher depressive symptoms score than those looked after by a family member. Logistic regression indicated that care by a domestic worker was approximately seven times more likely for women than men, about 10.8 times more likely for those without co-resident children compared with those who had three or more co-resident children, and 44 per cent less likely for the poorest compared with the richest persons. It appears that reliance on domestic workers is increasing and such reliance will remain necessary in the absence of culturally acceptable alternative institutional arrangements.
Coordinating comprehension and production in simultaneous interpreters: Evidence from the Articulatory Suppression Effect
Authors: YUDES CAROLINA , MACIZO PEDRO , BAJO TERESA
Published: August 2011

This study aimed to investigate the capacity of coordinating comprehension and production processes and the role of phonological working memory in simultaneous interpreting. To this end we evaluated the Articulatory Suppression (AS) effect in three groups of participants, monolingual controls, students of interpreting and professional interpreters. Three variables were examined, the material to be studied (words, pseudo-words), the complexity of the articulations (simple, complex) and the articulatory rate (participants produced their speech at their own rate). Monolingual controls showed AS effect in all study conditions; students of interpreting showed AS effect in complex study conditions and professional interpreters showed AS effect only when they studied pseudo-words and produced complex articulations. These results suggest that coordinating comprehension and production processes in interpreters is mediated by the retrieval of lexical–semantic information and the distribution of the speech.
Glücksspiel im Gehirn: Neurobiologische Grundlagen pathologischen Glücksspielens
Authors: Mörsen Chantal Patricia , Heinz Andreas , Bühler Mira , Mann Karl
Published: August 2011

Hintergrund: Pathologisches Glücksspielen (PG) wird in den internationalen Klassifikationssystemen bislang als Impulskontrollstörung klassifiziert. Erst in jüngster Zeit wird aufgrund der Ähnlichkeiten in Phänomenologie, Ätiologie, Verlauf sowie genetischen und neurobiologischen Faktoren mit der Substanzabhängigkeit eine Einordnung des PGs als Verhaltenssucht diskutiert. Insbesondere neurobiologische und neuropsychologische Befunde haben zu dieser veränderten Sichtweise beigetragen. Methode: Im vorliegenden Beitrag werden Befunde zu neurobiologischen Grundlagen PGs vorgestellt. Der Schwerpunkt liegt auf neurokognitiven Prozessen wie Belohnungs- und Bestrafungsverarbeitung, Cue-Reaktivität, Impulsivität und Entscheidungsfindung. Die Befunde werden im Hinblick auf Ähnlichkeiten und Unterschiede PGs zur Substanzabhängigkeit diskutiert. Ergebnisse: Ähnlich wie bei der Substanzabhängigkeit zeigt sich auch bei pathologischen Spielern Veränderungen mesolimbischer-präfrontaler Netzwerke, die sich in einer verminderten Belohnungs- und Bestrafungssensitivität, Impulshemmung und einer erhöhten Cue-Reaktivität auf glücksspielassoziierte Reize äußern können. Jedoch sind die Befunde teilweise nicht eindeutig und eine Vielzahl der Studien unterliegt methodischen Einschränkungen. Schlussfolgerungen: Bisherige Befunde stützen die Einordnung pathologischen Spielverhaltens als Verhaltenssucht.
Kognitive Langzeitfolgen nach einer akuten Enzephalitiseine
Authors: Hahn Katrin , Baumeister Christine , Schielke Eva
Published: August 2011

Akute Enzephalitiden sind seltene Erkrankungen. Es existieren nur wenige Untersuchungen bezüglich der kognitiven Langzeiterholung dieser Patienten. Nachfolgende neuropsychologische Studie untersuchte prospektiv kognitive Langzeitfolgen in Patienten nach einer durchgemachten akuten Enzephalitis und verglich sie mit Alters- Geschlechts- und Bildungsgematchten Kontrollpersonen. Die Zeit zwischen Untersuchung und Akutereignis betrug 6 – 93 Monate. Die Ergebnisse zeigten in der Mehrzahl eine positive kognitive Erholung. Im Vordergrund standen unabhängig von der Ätiologie der Enzephalitis Störungen des Antriebs und der Exekutivfunkionen. Eine postenzephalitische Epilepsie erwies sich als negativer Risikofaktor für die kognitive Rehabilitation.
Primäre Dystonien – zwischen Botulinum Toxin-Behandlung, Neuropsychologie, Psychotherapie und Tiefer Hirnstimulation
Authors: Leplow Bernd
Published: August 2011

Wegen ihrer psychophysiologischen und emotionalen Besonderheiten standen die Primären Dystonien viele Jahrzehnte lang im Spannungsfeld unterschiedlichster medizinischer und psychologischer Ätiologievorstellungen und Therapiestrategien. Inzwischen ist klar, dass es sich um Erkrankungen der Basalganglien handelt, deren Pathophysiologie weit über die rein motorischen Funktionen hinaus wirkt. Dieser Umstand erklärt auch die psychische, psychophysiologische und neuropsychologische Symptomatik, auf die in diesem Beitrag ausführlich eingegangen wird. Aber auch die Behandlungen am somatischen Substrat,wie sie heute durch die Botulinum Toxin Therapie und die „Tiefe Hirnstimulation“ praktiziert werden, bringen eine Vielzahl psychologischer Indikationen mit sich. Das betrifft die Verbesserung der Compliance bei der Botulinum-Behandlung ebenso wie die klinisch-psychologische und neuropsycholigische Diagnostik vor und nach einer Hirnoperation. Zusätzlich wird auf die Möglichkeiten einer Begleitbehandlung mit Hilfe formalisierter Psychotherapie eingegangen.
Renormalized one-loop theory of correlations in disordered diblock copolymers
Authors: Qin Jian , Grzywacz Piotr , Morse David C.
Published: August 2011

A renormalized one-loop (ROL) theory developed in previous work [P. Grzywacz, J. Qin, and D. C. Morse, Phys. Rev E. 76, 061802 (2007)]10.1103/PhysRevE.76.061802 is used to calculate corrections to the random phase approximation (RPA) for the structure factor S(q) in disordered diblock copolymer melts. Predictions are given for the peak intensity S(q*), peak position q*, and single-chain statistics for symmetric and asymmetric copolymers as functions of χeN, where χe is an effective Flory-Huggins interaction parameter and N is the degree of polymerization. The ROL and Fredrickson-Helfand (FH) theories are found to yield asymptotically equivalent results for the dependence of the peak intensity S(q*) upon χeN for symmetric diblock copolymers in the limit of strong scattering, or large χeN, but to yield qualitatively different predictions for symmetric copolymers far from the ODT and for asymmetric copolymers. The ROL theory predicts a suppression of S(q*) and a decrease of q* for large values of χeN, relative to the RPA predictions, but an enhancement of S(q*) and an increase in q* for small χeN. The decrease in q* near the ODT is shown to be unrelated to any change in single-chain statistics, and to be a result of inter-molecular correlations. Conversely, the predicted increase in q* at small values of χeN is a direct result of non-Gaussian single-chain statistics.
GaSe1−xSx and GaSe1−xTex thick crystals for broadband terahertz pulses generation
Authors: Nazarov M. M. , Yu. Sarkisov S. , Shkurinov A. P. , Tolbanov O. P.
Published: August 2011

We demonstrate the possibility of broadband THz pulse generation in mixed GaSe1−xSx and GaSe1−xTex crystals. The ordinary and extraordinary refractive indices of the crystals have been measured by the terahertz time-domain spectroscopy method, those values strongly influence the efficiency of THz generation process. The high birefringence and transparency of pure GaSe and mixed crystals allow optical rectification of femtosecond laser pulses in the several millimeters thick crystal using the еее interaction process (with two pumping waves and generated THz wave all having extraordinary polarization in the crystal).
Oxygen partial pressure effect on the thermal stability of Nd-123 superconductor thin films
Authors: Yan S. B. , Chen Y. Y. , Cheng L. , Yao X.
Published: August 2011

The effect of oxygen partial pressure on the thermal stability of Nd-123 superconductor thin films was investigated by means of high temperature in situ microscopy. It was found that the thermal stability of Nd-123 films decreases as the oxygen partial pressure increases. We attribute the thermal stability suppression to the increased growth rate of Nd-422 and a high concentration difference ratio. Under the assumption of quasi-equilibrium, a simplified model for peritectic melting of RE-123 was suggested.
Formation and decay processes of Ar/He microwave plasma jet at atmospheric gas pressure
Authors: Takamura S. , Amano S. , Kurata T. , Kasada H. , Yamamoto J. , Razzak M. A. , Kushida G. , Ohno N. , Kando M.
Published: August 2011

Dynamic behaviors of gas/plasma mixture generated by microwave discharge jet at atmospheric pressure have been investigated in terms of the effects of working gas dynamics on the discharge characteristics, focusing on the following four points: formation of discharge jet at the ignition phase, growing speed of plasma plume in relation to gas flow rate, acceleration and deceleration of upward movement of plasma plume, and decay process of plasma column at turn-off of microwave power. Four stages are identified at the discharge ignition. The acceleration coming from buoyancy effect and the deceleration due to gas flow turbulence have been found. The decay speed of plasma column at a power shut-off is found to be influenced by the gas flow turbulence and the recombination rate.
Effects of interfacial oxide layers of the electrode metals on the electrical characteristics of organic thin-film transistors with HfO2 gate dielectric
Authors: Tang W. M. , Greiner M. T. , Helander M. G. , Lu Z. H. , Ng W. T.
Published: August 2011

HfO2-based devices employing various electrode metals (Al, W, Pt, Cu, and Cr) were fabricated and characterized in order to examine the importance of the choice of metal electrode when sputter-depositing HfO2 films. It was found that metal-insulator-metal capacitors with an Al bottom electrode exhibit a significantly smaller leakage current and a larger breakdown field strength than devices using W, Pt, Cu, and Cr electrodes. By examining HfO2/metal interfaces with x-ray photoelectron spectroscopy, it was found that metal electrodes are oxidized during the deposition of HfO2, resulting in interfacial oxide layers of the electrode metals (Al2O3, WO3, PtO, CuO, and Cr2O3 + CrO3) between the metal electrode and the HfO2 layer. The formation of a metal oxide interlayer is a consequence of the high-energy oxygen ions generated during HfO2 sputtering. The difference in the device performance was attributed to the electronic properties of the oxide interlayers. It was found that when the oxide interlayers are semiconducting (e.g., WO3, PtO, CuO, or Cr2O3 + CrO3), devices have high leakage currents and low breakdown field strengths, and an insulating oxide interlayer (Al2O3) enhances these device characteristics. Organic thin-film transistors (OTFTs) using a HfO2 dielectric layer showed that an Al gate has a much lower off-state current, larger on/off ratio, and smaller sub-threshold slope compared with OTFTs using a Cr electrode. These results demonstrate the importance of the metal gate electrode and the electrical characteristics of its oxide when using the sputter-deposition of HfO2 to fabricate thin-film transistors.
Size effect of cubic ZrO2 nanoparticles on ionic conductivity of polyethylene oxide-based composite
Authors: Dey Arup , Ghoshal Tandra , Karan S. , De S. K.
Published: August 2011

A solvent free solid composite polymer electrolyte (SCPE) film consisting of high molecular mass polyethylene oxide (PEO) with sodium perchlorate (NaClO4) as electrolytic salt and cubic zirconium oxide (ZrO2) nanoparticles as the filler has been prepared by solution casting technique to influence the transport properties. X-ray diffraction and Fourier transform infrared spectroscopy confirm the formation of the SCPE film, whereas atomic force microscopy reveals the presence of a network of interconnected nanoparticles forming uniform surface feature of relatively low roughness. The highest ionic conductivity (σ = 6.96 × 10-5 S-cm-1) for PEO25 - NaClO4 with 5 wt. % ZrO2 nanoparticles of the smallest size 4.5 nm is an order of magnitude higher than the pure PEO25 - NaClO4 at room temperature. The conductivity enhancement is due to the creation of additional sites and favorable conduction pathways for ionic transport through Lewis acid-base type interactions between the polar surface groups of the ceramic filler and the electrolyte ionic species.
The influence of walls on Lagrangian statistics in two-dimensional turbulence
Authors: Kadoch B. , Bos W. J. T. , Schneider K.
Published: August 2011

The influence of solid walls on the Lagrangian statistics of statistically stationary two-dimensional turbulence is investigated by comparing the flow in a circular wall-bounded and in an unbounded periodic domain. A Fourier pseudo-spectral method is used, which is combined in the wall bounded case with a volume penalization technique to impose no-slip conditions. A particular emphasis is put on the acceleration of fluid particles. It is investigated to what extent the impact of the boundaries influences the shape of the probability density functions of Lagrangian velocity increments. It is shown that the influence of walls is not confined to a small near-wall region but alters the statistics in the entire flow domain. This can be explained by the vorticity generation in the turbulent boundary layer which destabilizes and leads to the formation of vortices that subsequently detach and travel into the bulk flow. The enstrophy level is thus increased with respect to the one in the unbounded periodic domain.
Radial electric field generated by resonant trapped electron pinch with radio frequency injection in a tokamak plasma
Authors: Gao Zhe , Fisch N. J. , Qin Hong
Published: August 2011

Radial electric fields in tokamaks can be generated by charge accumulation due to a resonant trapped electron pinch effect. The radial field can then drive a toroidal flow. This resonant pinch effect was evaluated for the current-drive scheme that diffused electrons in the direction parallel to the toroidal field. It was found that, for typical tokamak parameters, to generate a radial electric field on the order of 100 kV/m, an rf power density on the order of kW/m3 is required. This power, absorbed by trapped electrons, is a small fraction of rf power density for current drive which is absorbed by passing electrons. However, according to the Landau resonant mechanism, the fraction of the momentum to trapped electrons decays exponentially with the square of the parallel phase velocity of the wave; therefore, the power absorbed at lower resonant velocities is the key. On the other hand, the redistribution of the current profile, due to rf current, decreases the local poloidal field and may reduce the particle transport significantly. It can relax the requirement of momentum deposited to trapped electrons, and, at the same time, contribute to explain the strongly correlation between the rotation and the driven current observed in experiments.
Analytical solutions for Tokamak equilibria with reversed toroidal current
Authors: Martins Caroline G. L. , Roberto M. , Caldas I. L. , Braga F. L.
Published: August 2011

In tokamaks, an advanced plasma confinement regime has been investigated with a central hollow electric current with negative density which gives rise to non-nested magnetic surfaces. We present analytical solutions for the magnetohydrodynamic equilibria of this regime in terms of non-orthogonal toroidal polar coordinates. These solutions are obtained for large aspect ratio tokamaks and they are valid for any kind of reversed hollow current density profiles. The zero order solution of the poloidal magnetic flux function describes nested toroidal magnetic surfaces with a magnetic axis displaced due to the toroidal geometry. The first order correction introduces a poloidal field asymmetry and, consequently, magnetic islands arise around the zero order surface with null poloidal magnetic flux gradient. An analytic expression for the magnetic island width is deduced in terms of the equilibrium parameters. We give examples of the equilibrium plasma profiles and islands obtained for a class of current density profile.
Fabrication and characterization of Na0.5K0.5NbO3-CuNb2O6 lead-free step-down piezoelectric transformers
Authors: Yang Ming-Ru , Chu Sheng-Yuan , Chan I-Hao , Huang Sheng-Kai
Published: August 2011

Lead-free (Na0.5K0.5)NbO3 (NKN) ceramics doped with 1 mol% CuNb2O6 (01CN) ceramics were prepared using the conventional mixed oxide method at a sintering temperature of 1075 °C. NKN + 1 mol% CuTa2O6 (NKN-01CN) ceramics sintered at 1075 °C exhibit excellent “hard” piezoelectric properties of kp = 40%, kt = 45%, and k33 = 57%, with ferroelectric property Ec = 23 kV/cm. The mechanical quality factor (Qm) is extraordinarily high (1933) and the temperature stability is excellent (Temperature coefficient of frequency (TCF) = −154 ppm/°C). The piezoelectric transformer (PT) was fabricated on NKN-01CN lead-free substrates, and the electrical characteristics were investigated. The devices were simplified into an equivalent circuit and analyzed using the MATLAB software package. The simulation results matched the experimental results. By reversing the input and the output, the step-down PT can be easily fabricated using a simple disk-type structure. A maximum efficiency of 93% with a voltage gain of 0.12 was measured, which was in good agreement with the simulation results (a maximum efficiency of 98.7% with a voltage gain of 0.13) for the step-down mode.
Temperature dependence of the plasmon energy in liquid and solid phases of pure Al and of an Al-Si alloy using electron energy-loss spectroscopy
Authors: Eswara Moorthy Santhana K. , Howe James M.
Published: August 2011

The plasmon energy of the solid and liquid phases of pure Al, and an Al-Si alloy, was recorded as a function of temperature. For the case of pure Al, the trend in the solid and liquid phases followed the expected behavior based on a free (specific) volume change. Quantitatively, the slope of Ep versus T was −0.5 meV/K in the solid state and −2.2 meV/K in the liquid state. For the case of the Al-Si alloy, the trend in the solid phase was similar to that of pure Al, however, the trend in the liquid Al-Si phase was exactly opposite to what was observed for the pure Al liquid (i.e., +1.9 meV/K). This unexpected result is explained based on the variation, i.e., partitioning, of Si with temperature in the Al-Si alloy.
Study of valence band structure of Fe doped anatase TiO2 thin films
Authors: Bapna Komal , Phase D. M. , Choudhary R. J.
Published: August 2011

We study the structural and electronic properties of Fe doped (4–8 at. %) and undoped TiO2 thin films deposited by pulsed laser deposition on Si(111) substrate. The films grow in single phase anatase structure of TiO2 as revealed by x-ray diffraction and Raman spectroscopy measurements. The Fe doped films reveal room temperature magnetic hysteresis behavior. We have probed the electronic environment of Fe in TiO2 matrix and its coupling to the cations, using photoelectron spectroscopy measurements. Photoelectron spectroscopic studies reveal the ionic state of Fe in TiO2, precluding the formation of Fe metal clusters. Valence band spectra of these films suggest that it primarily consists of O-2p derived state, however, Fe derived state is also observed in Fe doped films. Resonance photoelectron spectroscopy studies indicate that Fe ions are hybridized with Ti3+ defect states.
Note: Measurement method for sound velocity of melts in large volume press and its application to liquid sodium up to 2.0 GPa
Authors: Song Wei , Liu Yonggang , Wang Zhigang , Gong Chaoying , Guo Jie , Zhou Wenge , Xie Hongsen
Published: August 2011

Based on large volume press and conventional pulse-echo ultrasonic technique, we have overcome the difficulty in determining the length of liquid specimen under high pressure, and the sound velocity in liquid Na has been measured up to 2 GPa. The P-V data deduced by our sound velocity results through equation of state is in an excellent agreement with previous data directly determined by piezometer method. This new experimental technique is convenient and ready for use, being expected to advance investigation on thermodynamic properties of liquid metals and other melts under high pressure.
Turbulent boundary layer flow subject to streamwise oscillation of spanwise wall-velocity
Authors: Skote M.
Published: August 2011

Direct numerical simulations have been performed to study the effect of a stationary distribution of spanwise wall-velocity that oscillates in the streamwise direction on a turbulent boundary layer. For the first time, a spatially developing flow with this type of forcing is studied. The part of the boundary layer which flows over the alternating wall-velocity section is greatly affected with a drag reduction close to 50% which exhibits an oscillatory distribution with a wavenumber which is twice that of the imposed wall-velocity. The maximum in drag reduction occurs where the wall velocity is at its maximum (or minimum) and the minimum occurs where the wall velocity is zero. Comparisons of the mean spanwise velocity profiles with the analytical solution to the laminar Navier-Stokes equations show very good agreement. The streamwise velocity profile indicates a thickening of the viscous sub-layer when scaled with the local friction velocity and an upward shifting of the logarithmic region when scaled with the reference (unmanipulated) friction velocity. An estimation of the idealized power consumption shows that—with the present wall forcing magnitude—more energy is required for the spatial oscillation than what is saved by drag reduction.
Using the charge-stabilization technique in the double ionization potential equation-of-motion calculations with dianion references
Authors: Kuś Tomasz , Krylov Anna I.
Published: August 2011

The charge-stabilization method is applied to double ionization potential equation-of-motion (EOM-DIP) calculations to stabilize unstable dianion reference functions. The auto-ionizing character of the dianionic reference states spoils the numeric performance of EOM-DIP limiting applications of this method. We demonstrate that reliable excitation energies can be computed by EOM-DIP using a stabilized resonance wave function instead of the lowest energy solution corresponding to the neutral + free electron(s) state of the system. The details of charge-stabilization procedure are discussed and illustrated by examples. The choice of optimal stabilizing Coulomb potential, which is strong enough to stabilize the dianion reference, yet, minimally perturbs the target states of the neutral, is the crux of the approach. Two algorithms of choosing optimal parameters of the stabilization potential are presented. One is based on the orbital energies, and another – on the basis set dependence of the total Hartree-Fock energy of the reference. Our benchmark calculations of the singlet-triplet energy gaps in several diradicals show a remarkable improvement of the EOM-DIP accuracy in problematic cases. Overall, the excitation energies in diradicals computed using the stabilized EOM-DIP are within 0.2 eV from the reference EOM spin-flip values.
Note: Vector network analyzer-ferromagnetic resonance spectrometer using high Q-factor cavity
Authors: Lo C. K. , Lai W. C. , Cheng J. C.
Published: August 2011

A ferromagnetic resonance (FMR) spectrometer whose main components consist of an X-band resonator and a vector network analyzer (VNA) was developed. This spectrometer takes advantage of a high Q-factor (9600) cavity and state-of-the-art VNA. Accordingly, field modulation lock-in technique for signal to noise ratio (SNR) enhancement is no longer necessary, and FMR absorption can therefore be extracted directly. Its derivative for the ascertainment of full width at half maximum height of FMR peak can be found by taking the differentiation of original data. This system was characterized with different thicknesses of permalloy (Py) films and its multilayer, and found that the SNR of 5 nm Py on glass was better than 50, and did not have significant reduction even at low microwave excitation power (−20 dBm), and at low Q-factor (3000). The FMR other than X-band can also be examined in the same manner by using a suitable band cavity within the frequency range of VNA.
Charging energy and barrier height of pentacene on Au(111): A local-orbital hybrid-functional density functional theory approach
Authors: Pieczyrak B. , Abad E. , Flores F. , Ortega J.
Published: August 2011

We analyze the pentacene/Au(111) interface by means of density functional theory (DFT) calculations using a new hybrid functional; in our approach we introduce, in a local-orbital formulation of DFT, a hybrid exchange potential, and combine it with a calculation of the molecule charging energy to properly describe the transport energy gap of pentacene on Au(111). Van der Waals forces are taken into account to obtain the adsorption geometry. Interface dipole potentials are also calculated; it is shown that the metal/pentacene energy level alignment is determined by the potential induced by the charge transfer between the metal surface and the organic material, as described by the induced density of interface states model. Our results compare well with the experimental data.
Switchable voltage control of the magnetic coercive field via magnetoelectric effect
Authors: Wang Jing , Ma Jing , Li Zheng , Shen Yang , Lin Yuanhua , Nan C. W.
Published: August 2011

Switchable voltage modulation of the magnetic properties is reported in different multiferroic bilayers with magnetic films grown on pre-poled ferroelectric substrates, based on the magneto-optical Kerr effect observations. The dynamic voltage control of the magnetic coercive field (Hc) is dependent not only on the materials properties of each ferroic layer, but also on the bias voltage history. The Hc versus electric field behaviors essentially track the dependence of the piezostrains of the substrates on the bias voltage. The observations demonstrate that Hc in such multiferroic bilayers can be controlled by voltage via strain-mediated magnetoelectric coupling and that the Hc change is not an artifact due to a heating effect.
Profiling of barrier capacitance and spreading resistance using a transient linearly increasing voltage technique
Authors: Gaubas E. , Čeponis T. , Kusakovskij J.
Published: August 2011

A technique for the combined measurement of barrier capacitance and spreading resistance profiles using a linearly increasing voltage pulse is presented. The technique is based on the measurement and analysis of current transients, due to the barrier and diffusion capacitance, and the spreading resistance, between a needle probe and sample. To control the impact of deep traps in the barrier capacitance, a steady state bias illumination with infrared light was employed. Measurements of the spreading resistance and barrier capacitance profiles using a stepwise positioned probe on cross sectioned silicon pin diodes and pnp structures are presented.
The theoretical current-voltage dependence of a non-degenerate disordered organic material obtained with conductive atomic force microscopy
Authors: Woellner Cristiano F. , Freire José A. , Guide Michele , Nguyen Thuc-Quyen
Published: August 2011

We develop a simple continuum model for the current voltage characteristics of a material as measured by the conducting atomic force microscopy, including space charge effects. We address the effect of the point contact on the magnitude of the current and on the transition voltages between the different current regimes by comparing these with the corresponding expressions obtained with planar electrodes.
Note: Determination of temperature dependence of GaP bandgap energy from diode temperature response characteristics
Authors: Krasnov V. A. , Shutov S. V. , Shwarts Yu. M. , Yerochin S. Yu.
Published: August 2011

A simple method of Eg(T) dependence determination for active areas of semiconductor devices based on wide bandgap semiconductors has been proposed and developed. Verification of the method has been carried out while determining Eg(T) dependence in a base area of p+-n-type GaP diodes in the temperature range 77–523 K. The method is based on U-T characterization of the diodes and calculation of Eg(T) dependence according to the expression obtained within present study. Satisfactory agreement between experimental and theoretical results has been achieved including references available on gallium phosphide. The method proposed could be applied to experimental data processing in high-temperature thermometry.
Note: Non-destructive measurement of thermal effusivity of a solid and liquid using a freestanding serpentine sensor-based 3ω technique
Authors: Qiu L. , Zheng X. H. , Zhu J. , Tang D. W.
Published: August 2011

A non-destructive thermal effusivity characterization method described as a freestanding serpentine sensor-based 3ω technique was reported. This freestanding serpentine sensor was fabricated by the mature flexible printed circuit production technique. Expression for the temperature response of the freestanding serpentine sensor with respect to the thermal effusivity of the test sample was presented. The technique was further verified by measuring four kinds of standard samples at room temperature. Experimental results which well agree with reference values demonstrate the new technique is of great application value to thermal effusivity characterization of solids, liquids, and structures to which the conventional 3ω technique is not applicable, e.g., solids with porous surfaces.
Dielectric effect induced by the barrier layers in Ni-doped KTaO3
Authors: Tsukada Shinya , Hayashi Taisuke , Ohba Takuya , Akishige Yukikuni
Published: August 2011

A dielectric constant of over 100 000, with dielectric loss of less than 0.1, was found in 1.0 mol. % Ni-doped KTaO3 (KT:1%Ni) single crystals, showing temperature and frequency stabilities favorable for capacitor applications. The dielectric constant was found to depend on the electrode material, and Ag electrodes markedly enhanced the dielectric properties. This result indicates that the giant effective dielectric constant is due to a non-Ohmic electrode contact with a semiconducting KT:1%Ni.
Capturing dynamic cation hopping in cubic pyrochlores
Authors: Brooks Hinojosa Beverly , Asthagiri Aravind , Nino Juan C.
Published: August 2011

In direct contrast to recent reports, density functional theory predicts that the most stable structure of Bi2Ti2O7 pyrochlore is a cubic Fd3¯m space group by accounting for atomic displacements. The displaced Bi occupies the 96g(x,x,z) Wyckoff position with six equivalent sites, which create multiple local minima. Using nudged elastic band method, the transition states of Bi cation hopping between equivalent minima were investigated and an energy barrier between 0.11 and 0.21 eV was determined. Energy barriers associated with the motion of Bi between equivalent sites within the 96g Wyckoff position suggest the presence of dielectric relaxation in Bi2Ti2O7.
Communication: Highly accurate ozone formation potential and implications for kinetics
Authors: Dawes Richard , Lolur Phalgun , Ma Jianyi , Guo Hua
Published: August 2011

Atmospheric ozone is formed by the O + O2 exchange reaction followed by collisional stabilization of the O3* intermediate. The dynamics of the O + O2 reaction and to a lesser extent the O3 stabilization depend sensitively on the underlying potential energy surface, particularly in the asymptotic region. Highly accurate Davidson corrected multi-state multi-reference configuration interaction calculations reported here reveal that the minimal energy path for the formation of O3 from O + O2 is a monotonically decaying function of the atom-diatom distance and contains no “reef” feature found in previous ab initio calculations. The absence of a submerged barrier leads to an exchange rate constant with the correct temperature dependence and is in better agreement with experiment, as shown by quantum scattering calculations.
Effective discharge planning - timely assignment of an estimated date of discharge
Authors: Ou Lixin , Chen Jack , Young Lis , Santiano Nancy , Baramy La-Stacey , Hillman Ken
Published: August 2011

Objective. To examine the implementation of estimated date of discharge (EDD) for planned admissions and admissions via the emergency department, to assess the variance between EDD and the actual date of discharge (ADD), and to explore the determinants of delayed discharge in a tertiary referral centre, Sydney, Australia. Methods. Primary data from a convenience sample of 1958 admissions for allocation of EDDs were linked with administrative data. The window for assigning EDDs for planned admissions was 24 h, for admissions via the emergency department it was 48 h. Logistic regression models were used to examine the key factors associated with an EDD being assigned within 24 h or 48 h of an admission. An ordinal logistic regression model was used to explore the determinants of delayed discharge. Results. Only 13.4% of planned admissions and 27.5% of admissions via the emergency department were allocated a timely EDD. Older patients, patients with significant burdens of chronic morbidity (OR = 0.903; P = 0.011); and patients from a non-English-speaking background (OR = 0.711; P = 0.059) were less likely to be assigned a timely EDD. The current Charlson Index score was a significant predictor of a positive variance between EDD and ADD. Conclusions. The prevalence of the timely assignment of an EDD was low and was lowest for planned admissions. The current Charlson Index score is an effective tool for identifying patients who are more likely to experience delayed discharge. What is known about the topic? Failure to assign an EDD is one of the major barriers to implementing effective discharge. Establishing an EDD for a patient within 24 h of an admission is thought to be a measure of efficient and high quality discharge planning. What does this paper add? Older patients, patients with significant burdens of chronic morbidity, and patients from a non-English-speaking background were less likely to be assigned a timely EDD. The current Charlson Index score was a significant predictor of a positive variance between EDD and ADD. What are the implications for practitioners? A significant gap existed between policy and the implementation of assigning EDD in a large sample of discharges. Effective discharge planning may be obstructed by failure to assign an EDD at the time of admission.