bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptions of the Concept of Mutation among Family Members of Patients Receiving Outpatient Genetic Services and University Students
Authors: Ando Noriko , Iwamitsu Yumi , Takemura Kazuhisa , Saito Yukiko , Takada Fumio
Published: September 2009

Our objectives were to investigate: (1) relationships between perceptions of various terms regarding mutation and the depth of knowledge regarding mutation among family members of patients receiving genetic outpatient services, and (2) differences in perceptions of the term “gene mutation” for family members versus university students. Fifty‐eight family members and 178 university students responded to two questionnaires: Impressions regarding the term, and Knowledge about the concept of mutation. Factor analyses were conducted to determine the factor structure of ratings of the terms, and two‐way analyses of variance [(1)Term, (2)Group × Knowledge] were conducted to examine differences in perceptions of the terms as measured by scores for each extracted factor. Family members had a significantly more negative perception of the term “gene mutation” than “gene change” and a less negative perception of the term “gene mutation” than “gene lesion”; they had significantly more negative perceptions of the term “gene mutation” than did university students.
Contrasting Effects of n‐3 and n‐6 Fatty Acids on Cyclooxygenase‐2 in Model Systems for Arthritis
Authors: Hurst Samantha , Rees Sarah G. , Randerson Peter F. , Caterson Bruce , Harwood John L.
Published: September 2009

Cyclooxygenase‐2 (COX‐2) is intimately involved in symptoms of arthritis while dietary n‐3 polyunsaturated fatty acids (PUFA) are thought to be beneficial. In these experiments, using both bovine and human in vitro systems that mimic features of arthritis, we show that the n‐3 PUFA eicosapentaenoic acid (EPA) is able to reduce mRNA and protein levels of COX‐2. Activity, as assessed through prostaglandin E2 formation, was also reduced in a dose‐dependent manner. These effects of EPA contrasted noticeably with the n‐6 PUFA, arachidonic acid. The data provide direct evidence for a molecular mechanism by which dietary n‐3 PUFA, such as EPA, can reduce inflammation and, hence, associated symptoms in arthritis.
Detection of lung atelectasis/consolidation by ultrasound in multiple trauma patients with mechanical ventilation
Authors: Yang Jian-xin , Zhang Mao , Liu Zhi-hai , Ba Li , Gan Jian-xin , Xu Shao-wen
Published: September 2009

Objective

To evaluate the efficacy of bedside ultrasound in detecting lung atelectasis/consolidation in multiple trauma patients with mechanical ventilation.

Methods

This prospective observation study was conducted in the emergency intensive care unit (EICU) over an 18-month period from January 2007 to June 2008. Chest ultrasound was performed in 81 multiple trauma patients with mechanical ventilation. Computed tomography (CT) was regarded as the “golden standard” to diagnose lung atelectasis/consolidation.

Results

Computed tomography detected 154 lung atelectasis/consolidation in 324 lung regions in 81 patients. Ultrasound confirmed 126 lung atelectasis/consolidation, 87 with complete and 39 with incomplete atelectasis/consolidation. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ultrasound were 81.8, 100, 100, 85.9 and 91.4%, respectively. A Kappa agreement test showed a very high concordance between ultrasound and CT with a Kappa coefficient of 0.825 (P = 0.031). The effective ratio of ultrasound guiding lung recruitment was 80.2%.

Conclusion

Ultrasound is a safe, dynamic viewing and accurate method to diagnose and manage lung atelectasis/consolidation in multiple trauma patients with mechanical ventilation.
Multiple proteins and phosphorylations regulate Saccharomycescerevisiae Cdc24p localization
Authors: Cole Karen C. , Barbour Joy-El R. , Midkiff John F. , Marble Brittany M. , Johnson Douglas I.
Published: September 2009

Targeting of Saccharomyces cerevisiae Cdc24p to polarized growth sites is essential for its function. Localization of GFP‐tagged Cdc24 proteins or fragments was assayed in deletion mutants of Cdc24p‐interacting proteins. The boi2Δ, ent2Δ, and hua1Δ mutants showed localization defects. The tos2Δ skg6Δ double mutant displayed aberrant pre‐anaphase localization to the mother‐bud neck region. The same aberrant pattern was seen when potential phosphorylation sites Ser697, Thr704, and Tyr200 were mutated. The S697A mutation also resulted in phosphorylation defects in vivo. These data support roles for Boi2p, Ent2p, Hua1p, Tos2p, and for Cdc24p phosphorylation in targeting Cdc24p to growth sites.
The stability and the nonlinear evolution of quasi-geostrophic hetons
Authors: REINAUD JEAN N. , CARTON XAVIER
Published: September 2009

We analyse the linear stability and nonlinear evolutions of circular hetons under the quasi-geostrophic approximation. We compare results obtained with a three-layer model and with a model based on a continuous density stratification. Though the models also differ by the vertical boundary conditions, they show a remarkable similarity in the stability properties of the hetons (threshold values of vortex radius for baroclinic instability, dominant modes, growth rates, etc.), and in their nonlinear evolutions (spatial reorganization of potential vorticity by nonlinear processes, end-states of the simulations). The hetons prone to baroclinic instability often break into two hetons drifting in opposite directions, and in more hetons, for wider initial structures. In both models, instability is quite sensitive to the vertical gap between the opposite-signed vortices: as it increases, the instability decreases and shifts to lower azimuthal modes. Finally, though modes l ≥ 2 (i.e. elliptical and shorter wave deformations) prevail in most of the parameter space, the mode l = 1 perturbation (a vertical tilt of the vortex column) exists for hetons with small vertical gaps. Such perturbations are concentrated vertically near the gap, and can only be evidenced in the continuously stratified model.
Low-frequency dynamics of shock-induced separation in a compression ramp interaction
Authors: GANAPATHISUBRAMANI B. , CLEMENS N. T. , DOLLING D. S.
Published: September 2009

The low-frequency dynamics of the shock-induced separation region in a Mach 2 compression ramp interaction is investigated by performing high-speed particle image velocimetry (HSPIV) measurements, at a rate of 6kHz, in a streamwise–spanwise plane. The HSPIV measurements made in the upstream turbulent boundary layer indicate the presence of spanwise strips of elongated regions of uniform streamwise velocity that extend to lengths greater than 30δ, validating previous results based on planar laser scattering measurements obtained by Ganapathisubramani, Clemens & Dolling (J. Fluid Mech., vol. 585, 2007, p. 369). At a wall normal-location of y/δ=0.2, a surrogate for separation based on a velocity threshold is found to fluctuate over a streamwise range of ±1.2δ, consistent with previous studies. The amplitude of unsteadiness has contributions from at least two sources that are related to the incoming boundary layer. First, the velocity threshold based surrogate separation line exhibits large-scale undulations along the spanwise direction that conform to the passage of elongated low- and high-speed regions in the upstream boundary layer. This motion is classified as the local influence of the upstream boundary layer. Second, the spanwise-averaged surrogate separation is found to respond to the overall change in streamwise velocity in the incoming boundary layer and is classified as the global influence of the upstream boundary layer. However, this global influence includes the contributions from the elongated low- and high-speed regions. Preliminary findings based on statistical analysis suggest that the local influence contributes nearly 50% more than the global influence. Regardless, the low-frequency unsteadiness of the separation-region can be attributed to the local and global influences of the incoming boundary layer.
‘Gobbling drops’: the jetting–dripping transition in flows of polymer solutions
Authors: CLASEN C. , BICO J. , ENTOV V. M. , McKINLEY G. H.
Published: September 2009

This paper discusses the breakup of capillary jets of dilute polymer solutions and the dynamics associated with the transition from dripping to jetting. High-speed digital video imaging reveals a new scenario of transition and breakup via periodic growth and detachment of large terminal drops. The underlying mechanism is discussed and a basic theory for the mechanism of breakup is also presented. The dynamics of the terminal drop growth and trajectory prove to be governed primarily by mass and momentum balances involving capillary, gravity and inertial forces, whilst the drop detachment event is controlled by the kinetics of the thinning process in the viscoelastic ligaments that connect the drops. This thinning process of the ligaments that are subjected to a constant axial force is driven by surface tension and resisted by the viscoelasticity of the dissolved polymeric molecules. Analysis of this transition provides a new experimental method to probe the rheological properties of solutions when minute concentrations of macromolecules have been added.
Flow transitions in the surface switching of rotating fluid
Authors: TASAKA Y. , IIMA M.
Published: September 2009

We study ‘surface switching’ quantitatively in flows driven by the constant rotation of the endwall of an open cylindrical vessel reported by Suzuki, Iima & Hayase (Phys. Fluids, vol. 18, 2006, p. 101701): the deformed free surface switches between axisymmetric and non-axisymmetric shapes accompanied by irregular vertical oscillation. Detailed simultaneous measurements showed that the magnitude of the velocity fluctuations (turbulent intensity) temporally varies greatly and are strongly correlated with the surface height, suggesting that dynamic switching between laminar and turbulent states is accompanied by vessel-scale surface shape changes. The study also identified clear hysteresis in the turbulent intensity arising from changes in the Reynolds number; the bifurcation diagram consists of two overlapping branches representing a high-intensity (turbulent) state and a low-intensity (laminar) state. Based on the results, a switching mechanism is suggested.
The Reed Rules and Republican Party Building: A New Look
Authors: Valelly Richard M.
Published: September 2009

The making of the Reed Rules – the source of today's U.S. House procedure – has often been studied, yet no one has previously noticed the extent to which they originated in a today forgotten Republican plan to federally regulate Southern House elections. This article shows how and why the Reed Rules and federal election regulation became fused in the 51st Congress. Republican members of the House not only had preferences over the internal governance of the House; they also simultaneously had preferences over the structure of the party system. In following this article's analysis of the linkage between the Reed Rules and the strategy of party conflict in the Gilded Age one comes to better appreciate the role of party building as a source of congressional development.
A Presidential Economic Scorecard: Performance and Perception
Authors: Dolan Chris J. , Frendreis John , Tatalovich Raymond
Published: September 2009

It is assumed that voters blame incumbents for poor economic performance but give credit when the economy is strong. A huge literature shows the impact of economic indicators and economic perceptions on vote choice and presidential popularity, but there is precious little research on whether public perceptions match economic reality. We propose a novel comparison of perceptions with performance by utilizing the Gallup Poll “most important” problem question. The average percentage that mentions unemployment, inflation, and the general economy over each presidential term from 1949 to 2008 is compared against the Presidential Economic Scorecard. The public correctly perceived unemployment and the general economy as salient national problems, but not inflation, and we speculate on why public perceptions do not correspond to actual inflation rates.
Persistent High Inequality as an Endogenous Political Process
Authors: Echeverri-Gent John
Published: September 2009

At the same time that the world has reached unprecedented prosperity, issues of economic inequality have attained great political salience. In the wake of the 2008 global financial crisis, there are major differences in opinion regarding the responsibility of the United States and other wealthy countries and what the proper response should be. In July 2008, the Doha round of negotiations at the WTO broke down after developing countries could not reach an agreement with wealthy countries on agricultural trade. The IMF is under pressure to reform its governance to provide better representation to middle-income and poor countries. And development experts admonish the world about the growing gap between the world's affluent countries and “the bottom billion” (Collier 2007). It used to be that economic-development strategies would target economic growth and “let the rising tide lift all ships.” Now, there is growing concern that growth be inclusive in order to make optimal use of societal resources and mitigate the political volatility that results when substantial segments of societies are excluded from the benefits of development.
The Conditional Relationship between Inequality and Development
Authors: Boix Carles
Published: September 2009

In recent years political scientists and economists have spent considerable efforts investigating the impact of income inequality both on political institutions and social conflict (Boix 2003, 2008; Acemoglu and Robinson 2006; Geddes 2007) and on growth and development (Atkinson and Bourguignon 2000). In this article I focus on the latter question: I discuss the extent to which (that is, the conditions under which) inequality may hinder economic growth. I do so by moving away from the current literature, which models the relationship between development and inequality in a linear fashion—with the latter unconditionally distorting (or boosting) the incentives to invest and therefore reducing (or increasing) the rate of growth. Instead, I claim that the potential correlation between inequality and development will be always conditional on the (mostly political and institutional) causes that generate the existing income distribution to start with. Hence it is not surprising to find instances in which growth and (mostly temporary) inequality come hand in hand as well as other periods and countries where there is both high and persistent inequality jointly with economic stagnation.
Politics and Inequality in Latin America
Authors: Huber Evelyne
Published: September 2009

Our symposium offers a variety of perspectives, such as on self-perpetuation of inequality in the international system, or on the consequences of inequality for economic growth or for social and political conflicts. This contribution discusses the determinants of domestic policy choices that affect inequality and the consequences of these policy choices. The empirical focus is on Latin American countries, which collectively are characterized by the highest regional levels of inequality in the world, but individually show considerable variation. Different analyses have emphasized different causes of income inequality and of the variation in inequality, such as historical structural roots in land distribution and natural-resource endowments, geography, ethnic divisions, the economic context, demographics, and state action or lack thereof. The role of the state has not received much systematic attention until rather recently, though, despite its essential role in the allocation of resources.
Simulating Terrorism: Credible Commitment, Costly Signaling, and Strategic Behavior
Authors: Siegel David A. , Young Joseph K.
Published: September 2009

We present two simulations designed to convey the strategic nature of terrorism and counterterrorism. The first is a simulated hostage crisis, designed primarily to illustrate the concepts of credible commitment and costly signaling. The second explores high-level decision making of both a terrorist group and the state, and is designed to highlight scarce-resource allocation and organizational dynamics. The simulations should be useful both in a traditional classroom setting as well as to the larger public. We provide a primer on the subject matter, and all the material necessary to run the simulations.
Teaching about Terrorism: Lessons Learned at SWOTT
Authors: Miller Gregory D.
Published: September 2009

This article discusses some of the challenges and lessons for teaching undergraduate-level courses related to terrorism. The author outlines some of the primary issues that instructors can expect to face, and provides strategies for dealing with several of these challenges. The goal is to relay useful information to those teaching, or planning to teach, courses on terrorism, with the larger hope of strengthening the community of terrorism scholars and possibly developing some best practices for teaching courses on terrorism.
Geomorphically based predictive mapping of soil thickness in upland watersheds
Authors: Pelletier Jon D. , Rasmussen Craig
Published: September 2009

The hydrologic response of upland watersheds is strongly controlled by soil (regolith) thickness. Despite the need to quantify soil thickness for input into hydrologic models, there is currently no widely used, geomorphically based method for doing so. In this paper we describe and illustrate a new method for predictive mapping of soil thicknesses using high‐resolution topographic data, numerical modeling, and field‐based calibration. The model framework works directly with input digital elevation model data to predict soil thicknesses assuming a long‐term balance between soil production and erosion. Erosion rates in the model are quantified using one of three geomorphically based sediment transport models: nonlinear slope‐dependent transport, nonlinear area‐ and slope‐dependent transport, and nonlinear depth‐ and slope‐dependent transport. The model balances soil production and erosion locally to predict a family of solutions corresponding to a range of values of two unconstrained model parameters. A small number of field‐based soil thickness measurements can then be used to calibrate the local value of those unconstrained parameters, thereby constraining which solution is applicable at a particular study site. As an illustration, the model is used to predictively map soil thicknesses in two small, ∼0.1 km2, drainage basins in the Marshall Gulch watershed, a semiarid drainage basin in the Santa Catalina Mountains of Pima County, Arizona. Field observations and calibration data indicate that the nonlinear depth‐ and slope‐dependent sediment transport model is the most appropriate transport model for this site. The resulting framework provides a generally applicable, geomorphically based tool for predictive mapping of soil thickness using high‐resolution topographic data sets.
Reduction of spring warming over East Asia associated with vegetation feedback
Authors: Jeong Su‐Jong , Ho Chang‐Hoi , Kim Kwang‐Yul , Jeong Jee‐Hoon
Published: September 2009

Over East Asia, surface air temperature displays a significant increasing trend particularly in early months of the year for the period of 1982–2000. Warming per decade is strongest in late winter, 1.5°C in February and 1.1°C in March, but is significantly reduced in spring, 0.4°C in April and 0.1°C in May. During the analysis period, the reduced temperature increase from late winter to spring is found to be in contrast with the increased vegetation greenness derived from the satellite‐measured leaf area index over the domain. We examined this inverse relationship using two climate model experiments— coupled with and without a dynamic vegetation model. In both experiments, strong warming in winter is relatively well reproduced, but weak warming in spring is observed only in the coupled experiment. Analysis of the surface energy budget indicates that weaker spring warming results from an evaporative cooling effect due to the increased vegetation greenness. Over East Asia, the vegetation‐evaporation feedback, therefore, may produce seasonal asymmetry in the warming trend.
First observations of large‐scale wave structure and equatorial spread F using CERTO radio beacon on the C/NOFS satellite
Authors: Thampi Smitha V. , Yamamoto Mamoru , Tsunoda Roland T. , Otsuka Yuichi , Tsugawa Takuya , Uemoto Jyunpei , Ishii Mamoru
Published: September 2009

First observations of large‐scale wave structure (LSWS) and the subsequent development of equatorial spread F (ESF), using total electron content (TEC) derived from the ground based reception of beacon signals from the CERTO (Coherent Electromagnetic Radio Tomography) radio beacon on board C/NOFS (Communications/Navigation Outage Forecasting System) satellite, are presented. Selected examples of TEC variations, using measurements made during January 2009 from Bac Lieu, Vietnam (9.2°N, 105.6°E geographic, 1.7°N magnetic dip latitude) are presented to illustrate two key findings: (1) LSWS appears to play a more important role in the development of ESF than the post‐sunset rise (PSSR) of the F‐layer, and (2) LSWS can appear well before E region sunset. Other findings, that LSWS does not have significant zonal drift in the initial stages of growth, and can have zonal wavelengths of several hundred kilometers, corroborate earlier reports.
Characterisation of photochemically formed reactive species from kinetic and thermodynamic data using UV-Vis. Laser flash photolysis, Time resolved IR and matrix isolation techniques
Authors: Long Conor , Pryce Mary T.
Published: September 2009

This report is concerned with research using time resolved spectroscopic and matrix isolation techniques in the years 2006 to 2008. Both inorganic and organometallic systems are covered. The report groups the published output depending on the position in the periodic table of the principal metallic element of the complexes under investigation.
Bound states of the OH(Π2)–HCl complex on ab initio diabatic potentials
Authors: Groenenboom Gerrit C. , Fishchuk Anna V. , van der Avoird Ad
Published: September 2009

The bound states of the open-shell OH(Π2)–HCl complex were calculated in four dimensions with a diabatic model using electronic states that correlate asymptotically with the ground and excited spin-orbit states of the OH(Π2) fragment and the ground state of the HCl fragment. The ab initio diabatic potentials and their analytic expansion applied in these calculations were obtained earlier by Wormer et al. [J. Chem. Phys. 122, 244325 (2005)]. In addition to the four-dimensional calculations, we considered a (3+1)-dimensional model in which the intermolecular distance coordinate R is adiabatically separated from the remaining coordinates. Both models include the important spin-orbit coupling in the OH fragment. Energy levels and parity splittings were computed for a total angular momentum of J=12 and 32; rotational constants and other spectroscopic parameters were extracted from these calculations. The vibrationally averaged geometry in the ground state of the complex is planar and this state is more or less localized near the minimum in the lowest adiabatic potential with binding energy De=1123 cm−1; the dissociation energy D0 with respect to OH(Π23/2) and HCl is found to be 685 cm−1. The splitting between the Π23/2 and Π21/2 spin-orbit states of free OH is largely reduced by the anisotropic interaction with HCl through the off-diagonal diabatic coupling potential and these states are strongly mixed. Low lying rovibronic states that correlate with the OH(Π23/2) ground state were found at 14 cm−1 for total angular momentum projection quantum number |Ω|=32 and 26 cm−1 for |Ω|=12, relative to the ground state with |Ω|=12. The OH–HCl stretch fundamental frequency equals to 93.6 cm−1, the lowest bend excited states (involving a coupled bend motion of both fragments) were found in the region of 150–160 cm−1 above the ground state. Especially in the excited states important nonadiabatic effects are observed that involve both of the asymptotically degenerate adiabatic electronic states. In some of these excited states the vibrationally averaged geometry is nonplanar.
Absorption intensities, emission cross sections, and crystal field analysis of selected intermanifold transitions of Ho3+ in Ho3+:Y2O3 nanocrystals
Authors: Nash Kelly L. , Dennis Robert C. , Ray Nathan J. , Gruber John B. , Sardar Dhiraj K.
Published: September 2009

Optical absorption and emission intensities are investigated for Ho3+ in nanocrystalline Ho3+:Y2O3. Room temperature absorption intensities of Ho3+(4f10) transitions in synthesized Ho3+:Y2O3 nanocrystals have been analyzed using the Judd–Ofelt (JO) approach to obtain the phenomenological intensity parameters Ω2, Ω4, and Ω6. The JO intensity parameters are used to calculate the spontaneous emission probabilities, radiative lifetimes, and branching ratios of the Ho3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds L2S+1J of Ho3+(4f10). The emission cross sections of the intermanifold transitions F54,S52→I58 (0.549 μm) and I56→I58 (1.204 μm) have been determined. The room temperature fluorescence lifetimes of these transitions in Ho3+:Y2O3 nanocrystals were measured. Radiative and fluorescence lifetimes are used to determine the quantum efficiency. The low temperature spectra are analyzed for the energy (Stark) level transitions of select L2S+1J multiplet manifolds of Ho3+(4f10). The comparative study of Ho3+(4f10) ions suggests that synthesized Ho3+:Y2O3 nanocrystals could be an excellent alternative to single-crystal Ho3+:Y2O3 for certain photonic applications, especially in the near infrared region.
CuPt ordering in high bandgap GaxIn1−xP alloys on relaxed GaAsP step grades
Authors: Steiner M. A. , Bhusal L. , Geisz J. F. , Norman A. G. , Romero M. J. , Olavarria W. J. , Zhang Y. , Mascarenhas A.
Published: September 2009

We have fabricated a series of GaxIn1−xP samples over the compositional range 0.51<x<0.76 on GaAs substrates. The samples were prepared by first growing a thick step-graded layer of GaAs1−yPy to bridge the lattice misfit between the GaxIn1−xP layers and the GaAs substrate. The order parameter was tuned using a dilute antimony surfactant during growth. The composition, strain, and order parameter of each sample were characterized by x-ray diffraction, and the bandgap was measured by photoluminescence. We find good agreement between the experimentally measured bandgaps and theoretically modeled curves.
Gas hydrates: Unlocking the energy from icy cages
Authors: Koh Carolyn A. , Sum Amadeu K. , Sloan E. Dendy
Published: September 2009

Technological advancements to control gas hydrates in energy transportation, recovery, and storage require detailed knowledge of the structural properties of these materials, and the thermodynamic and kinetic mechanisms of gas hydrate formation and decomposition. Paradigm shifts are moving the energy industry from thermodynamic to kinetic control strategies of gas hydrates in gas and oil deepwater pipelines, and from exploration to production from hydrated arctic deposits. This review examines the recent research progress in molecular structural kinetic studies of gas hydrates, and the development of new strategies for detecting and producing energy from arctic and oceanic hydrated deposits, and producing new materials for hydrogen storage.
Orientation control and self-assembled nanopyramid structure of LaFeO3 films epitaxially grown on SrTiO3(001) substrates
Authors: Bi Lei , Kim Hyun-Suk , Dionne Gerald F. , Ross C. A. , Paik Hanjong , Park Yun Chang
Published: September 2009

Epitaxial films of LaFeO3 (LFO) were grown on SrTiO3(001) (STO) substrates using pulsed laser deposition. Two epitaxial orientations were observed: α where LFO(110)∥STO(100) and β where LFO(001)∥STO(100). By controlling the deposition conditions, LaFeO3 films could be grown with just the α orientation or with simultaneous α and β orientations in which the film consisted of a self-assembled array of nanoscale β pyramids embedded in a matrix of α. The microstructure and growth mechanism of the films and their exchange-bias with a Co overlayer are discussed.
Optimization of the electrical asymmetry effect in dual-frequency capacitively coupled radio frequency discharges: Experiment, simulation, and model
Authors: Schulze J. , Schüngel E. , Czarnetzki U. , Donkó Z.
Published: September 2009

An electrical asymmetry in capacitive rf discharges with a symmetrical electrode configuration can be induced by driving the discharge with a fundamental frequency and its second harmonic. For equal amplitudes of the applied voltage waveforms, it has been demonstrated by modeling, simulation, and experiments that this electrical asymmetry effect (EAE) leads to the generation of a variable dc self-bias that depends almost linearly on the phase angle between the driving voltage signals. Here, the dependence of the dc self-bias generated by the EAE on the choice of the voltage amplitudes, i.e., the ratio A of high to low frequency amplitude, is investigated experimentally as well as by using an analytical model and a particle-in-cell simulation. It is found that (i) the strongest electrical asymmetry is induced for A<1 at pressures ranging from 6 to 100 Pa and that (ii) around this optimum voltage ratio the dc self-bias normalized to the sum of both voltage amplitudes is fairly insensitive to changes of A. Thus, by choosing the optimum voltage ratio, the EAE is optimized: The ion energy can be changed over a broader energy range and a high degree of process stability with respect to small changes in the applied voltages is expected.
Elastic Lennard-Jones polymers meet clusters: Differences and similarities
Authors: Schnabel Stefan , Bachmann Michael , Janke Wolfhard
Published: September 2009

We investigate solid-solid and solid-liquid transitions of elastic flexible off-lattice polymers with Lennard-Jones monomer-monomer interaction and anharmonic springs by means of sophisticated variants of multicanonical Monte Carlo methods. We find that the low-temperature behavior depends strongly and nonmonotonically on the system size and exhibits broad similarities to unbound atomic clusters. Particular emphasis is dedicated to the classification of icosahedral and nonicosahedral low-energy polymer morphologies.
Controlled dust formation in pulsed rf plasmas
Authors: Berndt J. , Kovačević E. , Stefanović I. , Boufendi L.
Published: September 2009

This paper deals with the formation of nanoparticles in a pulsed discharge. Experiments are performed in a capacitively coupled discharge operated in a mixture of argon and acetylene. The paper focuses especially on the influence of the pulse frequency on the dust formation. The experiments reveal the existence of a rather narrow frequency band that separates a frequency region with no dust formation from a frequency region where dust formation occurs. The decisive point in the observations is that a small change in the pulse frequency (from 700 to 725 Hz) is enough to induce or, respectively, suppress the formation of dust particles. The experimental results are discussed by means of a simple model that allows one to calculate the density of negative ions (C2H−, C4H−, etc.) as a function of the pulse frequency.
Temperature enhancement of secondary electron emission from hydrogenated diamond films
Authors: Stacey A. , Prawer S. , Rubanov S. , Akhvlediani R. , Michaelson Sh. , Hoffman A.
Published: September 2009

The effect of temperature on the stability of the secondary electron emission (SEE) yield from ∼100-nm-thick continuous diamond films is reported. At room temperature, the SEE yield was found to decay as a function of electron irradiation dose. The SEE yield is observed to increase significantly upon heating of the diamond surface. Furthermore, by employing moderate temperatures, the decay of the SEE yield observed at room temperature is inhibited, showing a nearly constant yield with electron dose at 200 °C. The results are explained in terms of the temperature dependence of the electron beam-induced hydrogen desorption from the diamond surface and surface band bending. These findings demonstrate that the longevity of diamond films in practical applications of SEE can be increased by moderate heating.
Magnetometric sensitivity optimization for nonlinear optical rotation with frequency-modulated light: Rubidium D2 line
Authors: Kimball D. F. Jackson , Jacome L. R. , Guttikonda Srikanth , Bahr Eric J. , Chan Lok Fai
Published: September 2009

Atomic spin polarization of alkali atoms in the ground-state can survive thousands of collisions with paraffin-coated cell walls. The resulting long spin-relaxation times achieved in evacuated, paraffin-coated cells enable precise measurement of atomic spin precession and energy shifts of ground-state Zeeman sublevels. In the present work, nonlinear magneto-optical rotation with frequency-modulated light (FM NMOR) is used to measure magnetic field-induced spin precession for rubidium atoms contained in a paraffin-coated cell. The magnetometric sensitivity of FM NMOR for the rubidium D2 line is studied as a function of light power, detuning, frequency-modulation amplitude, and rubidium vapor density. For a 5-cm-diameter cell at temperature T≈35 °C, the optimal shot-noise-projected magnetometric sensitivity is found to be 2×10−11 G/Hz (corresponding to a sensitivity to spin precession frequency of ≈10 μHz/Hz or a sensitivity to Zeeman sublevel shifts of ≈4×10−20 eV/Hz).
Orientation-controlled charge transfer at CuPc/F16CuPc interfaces
Authors: Chen Wei , Chen Shuang , Chen Shi , Li Huang Yu , Huang Han , Qi Dong Chen , Gao Xing Yu , Ma Jing , Wee Andrew Thye Shen
Published: September 2009

Molecular orientation-controlled charge transfer has been observed at the organic-organic heterojunction interfaces of copper-hexadecafluoro-phthalocyanine (F16CuPc) or copper(II) phthalocyanine (CuPc) on both standing-up and lying-down CuPc or F16CuPc thin films. In situ synchrotron-based photoemission spectroscopy reveals that the charge transfer at the standing F16CuPc/CuPc or CuPc/F16CuPc interface is much larger than that at the lying F16CuPc/CuPc or CuPc/F16CuPc interface. This can be explained by the orientation-dependent ionization potentials of well-ordered organic thin films, which place the highest-occupied molecular orbital of the standing CuPc film much closer to the lowest-unoccupied molecular orbital of the standing F16CuPc film, facilitating stronger charge transfer as compared to that at the lying OOH interfaces. Our results suggest the possibility of manipulating interfacial electronic structures of organic heterojunctions by controlling the molecular orientation, in particular for applications in ambipolar organic field transistors and organic photovoltaics.
High efficiency p-i-n top-emitting organic light-emitting diodes with a nearly Lambertian emission pattern
Authors: Leem Dong-Seok , Kim Sei-Yong , Lee Jae-Hyun , Kim Jang-Joo
Published: September 2009

We report high efficiency phosphorescent green p-i-n top-emitting organic light-emitting diodes consisting of metal anodes (Ag and Al), a rhenium oxide p-dopant, a rubidium carbonate n-dopant, and a semitransparent Ag cathode. Significantly high peak current efficiencies of 88 and 73 cd/A are demonstrated for the devices using Ag and Al anodes, respectively, through the optimization of organic layer thickness. The electroluminescence intensities of the Ag-based device with viewing angles show a nearly Lambertian distribution, whereas those of the Al-based device exhibit a relatively strong angular dependence, which is mainly attributed to the change in the resonance wavelength of the microcavity of the devices. Efficiencies, emission spectra, and angular dependence of the emission of the devices are further successfully analyzed using an optical model.
Phase-coherent quantum transport in silicon nanowires based on Wigner transport equation: Comparison with the nonequilibrium-Green-function formalism
Authors: Barraud Sylvain
Published: September 2009

Various theoretical formulations are proposed for investigating the carrier transport in nanoscale electronic devices. In this paper, a discrete formulation of the Wigner transport equation (WTE) for the self-consistent simulation of phase-coherent quantum transport in silicon nanowire metal-oxide-semiconductor field-effect transistor (MOSFET) devices is presented. The device is simulated using an effective-mass Hamiltonian within the mode-space approximation. The numerical scheme proposed in this work solves self-consistently three dimensional Poisson’s equation, two dimensional Schrödinger’s equation in each cross-sectional plane of the nanowire, and the steady-state one dimensional WTE for each conduction mode to handle the quantum transport along the channel. Details on numerical implementation of the Wigner function method are given, and the results are compared with those of the nonequilibrium Green’s function (NEGF) method in the ballistic limit. The calculations of current-voltage electrical characteristics of surround-gated silicon nanowires are performed using both NEGF and WTE formulations. The good agreement observed between these approaches means that a direct solution of the WTE is an accurate simulation method for modeling the ballistic quantum transport in silicon nanowire MOSFETs.
Organic thin-film solar cells with a Cu anode: Improvement of the photovoltaic properties on aging in air
Authors: Yoshida Yuki , Tanaka Senku , Fujita Yasuhisa , Hiromitsu Ichiro
Published: September 2009

The photovoltaic properties of a Ga-doped ZnO (GZO)/3,4,9,10-perylene-tetracarboxyl-bis-benzimidazole (PTCBI)/Zn-phthalocyanine (ZnPc)/Cu heterojunction cell (cell A) and a GZO/ZnPc/Cu Schottky-barrier cell (cell B) were investigated. The energy conversion efficiency η of cell A was only 0.02% immediately after the device preparation but improved to 0.46% after aging for 24 days in air. To elucidate the mechanism of this aging effect, photocurrent action and electro-absorption spectra were measured for cell B. The results reveal that a Schottky barrier exists at the ZnPc/Cu interface which blocks the transport of photogenerated holes to the Cu electrode, and the barrier height is reduced by a white-light illumination of the device after aging. The change in barrier height is attributed to the formation of electron traps at the surface of the ZnPc layer on aging that trap photogenerated electrons.
Fluctuations and stratification in sedimentation of dilute suspensions of spheres
Authors: Gómez Daniel Chehata , Bergougnoux Laurence , Guazzelli Élisabeth , Hinch John
Published: September 2009

We have tested in experiments and simulations whether stratification can control velocity fluctuations in suspensions of sedimenting spheres. The initial value and early decay of the velocity fluctuations are not affected by stratification. On the other hand, in the descending front where the stratification is strong and well defined, the velocity fluctuations are inhibited according to a previously proposed scaling. In between, after the initial decay and before the arrival of the front, the local value of the stratification does not always play a role.
Role of shallow Si/SiO2 interface states on high frequency channel noise in n-channel metal-oxide-semiconductor field effect transistors
Authors: Su Hao , Wang Hong , Xu Tao , Zeng Rong
Published: September 2009

The role of shallow interface states on high frequency channel noise in n-channel metal-oxide-semiconductor field effect transistors (n-MOSFETs) has been studied. Our experimental results reveal that the excess channel noise in gigahertz range induced by hot carrier stress could be attributed to the carrier transitions associated with shallow interface states. This suggests that the shallow Si/SiO2 interface states in MOSFETs may play an important role in determining the channel noise in gigahertz frequency range.
Advancements in electron cyclotron emission imaging demonstrated by the TEXTOR ECEI diagnostic upgrade
Authors: Tobias B. , Kong X. , Liang T. , Spear A. , Domier C. W. , Luhmann N. C. , Classen I. G. J. , Boom J. E. , van de Pol M. J. , Jaspers R. , Donné A. J. H. , Park H. K. , Munsat T.
Published: September 2009

A new TEXTOR electron cyclotron emission imaging system has been developed and employed, providing a diagnostic with new features and enhanced capabilities when compared to the legacy system it replaces. Optical coupling to the plasma has been completely redesigned, making use of new minilens arrays for reduced optical aberration and providing the new feature of vertical zoom, whereby the vertical coverage is now remotely adjustable on a shot-by-shot basis from 20–35 cm. Other innovations, such as the implementation of stacked quasioptical planar notch filters, allow for the diagnostic to be operated without interruption or degradation in performance during electron cyclotron resonance heating. Successful commissioning of the new diagnostic and a demonstration of the improved capabilities are presented in this paper, along with a discussion of the new technologies employed.
The bootstrap current in small rotating magnetic islands
Authors: Bergmann A. , Poli E. , Peeters A. G.
Published: September 2009

The bootstrap current in small magnetic islands of neoclassical tearing modes is studied with guiding center particle simulations including pitch angle scattering. A model for a rotating island and its electric field is used and a new approximation to the electric potential in small islands is derived. Islands with sizes of the order of the ion banana orbit width are studied by means of a two-step model, which allows to treat both ions and electrons kinetically. The bootstrap current in such small islands is found to depend strongly on the direction of rotation of the island. The bootstrap current in small islands rotating in the ion diamagnetic direction is strongly diminished, similarly to what happens in big islands. In small islands rotating in the electron diamagnetic direction, on the contrary, the bootstrap current is almost completely preserved, implying a reduced neoclassical drive of the island growth.
Phonons in Ge nanowires
Authors: Peelaers H. , Partoens B. , Peeters F. M.
Published: September 2009

The phonon spectra of thin freestanding, hydrogen passivated, Ge nanowires are calculated by ab initio techniques. The effect of confinement on the phonon modes as caused by the small diameters of the wires is investigated. Confinement causes a hardening of the optical modes and a softening of the longitudinal acoustic modes. The stability of the nanowires, undoped or doped with B or P atoms, is investigated using the obtained phonon spectra. All considered wires were stable, except for highly doped, very thin nanowires.
Strain effects in group-III nitrides: Deformation potentials for AlN, GaN, and InN
Authors: Yan Qimin , Rinke Patrick , Scheffler Matthias , Van de Walle Chris G.
Published: September 2009

A systematic density functional theory study of strain effects on the electronic band structure of the group-III nitrides (AlN, GaN, and InN) is presented. To overcome the deficiencies of the local-density and generalized gradient approximations the Heyd–Scuseria–Ernzerhof (HSE) hybrid functional is used. Cross checks for GaN demonstrate good agreement between HSE and exact-exchange based G0W0 calculations. We observe a pronounced nonlinear dependence of band-energy differences on strain. For realistic strain conditions in the linear regime around the experimental equilibrium volume a consistent and complete set of deformation potentials is derived.
Tunable magnetoelastic phononic crystals
Authors: Robillard J.-F. , Matar O. Bou , Vasseur J. O. , Deymier P. A. , Stippinger M. , Hladky-Hennion A.-C. , Pennec Y. , Djafari-Rouhani B.
Published: September 2009

The feasibility of tuning the band structure of phononic crystals is demonstrated by employing magnetostrictive materials and applying an external magnetic field. Band structures are calculated with a plane wave expansion method that accounts for coupling between the elastic behavior and the magnetic field through the development of elastic, piezomagnetic, and magnetic permeability effective tensors. We show the contactless tunability of the absolute band gaps of a two-dimensional phononic crystal composed of an epoxy matrix and Terfenol-D inclusions. The tunable phononic crystal behaves like a transmission switch for elastic waves when the magnitude of an applied magnetic field crosses a threshold.
Observation of pressure stimulated voltages in rocks using an electric potential sensor
Authors: Aydin A. , Prance R. J. , Prance H. , Harland C. J.
Published: September 2009

Recent interest in the electrical activity in rock and the use of electric field transients as candidates for earthquake precursors has led to studies of pressure stimulated currents in laboratory samples. In this paper, an electric field sensor is used to measure directly the voltages associated with these currents. Stress was applied as uniaxial compression to marble and granite at an approximately constant rate. In contrast with the small pressure stimulated currents previously measured, large voltage signals are reported. Polarity reversal of the signal was observed immediately before fracture for the marble, in agreement with previous pressure stimulated current studies.
Weibel instabilities in a completely degenerate electron Fermi gas
Authors: Tsintsadze Levan N.
Published: September 2009

Weibel instability in a degenerate Fermi plasma is studied. A new type of quantum Weibel instabilities is disclosed. In particular, a novel oscillatory Weibel instability is found and its growth rate is obtained. A transverse zero sound in a quantum degenerate electron gas, which has no counterpart in the classical consideration, is revealed.
Excitation frequency dependent mode manipulation in radio-frequency atmospheric argon glow discharges
Authors: Zhang Jie , Ding Ke , Wei Kaya , Zhang Jing , Shi Jianjun
Published: September 2009

An experimental investigation is presented to characterize the dependence of discharge operation modes (α and γ modes) and their transition on excitation frequency in radio-frequency atmospheric argon glow discharges. The current-voltage characteristics are used to distinguish the α and γ modes at an excitation frequency range of 5–24 MHz. The operation regime of α mode with stable and uniform discharge in large volume is found to expand at higher excitation frequency. It is shown that, when excitation frequency is below 10 MHz, the discharge evolves directly into γ mode after gas breakdown and, when excitation frequency is above 10 MHz, the discharge operates in the coexistence mode of α and γ after mode transition.
Social Production of Desirable Space: An Exploration of the Practice and Role of Property Agents in the UK Commercial Property Market
Authors: Schiellerup Pernille , Gwilliam Julie
Published: September 2009

The design, construction, and occupation of a sustainable built environment have been the focus of much research over recent years. Most notably, the focus has been on the modelling and prediction of energy use and carbon production during the design process together with the monitoring of carbon emissions during occupation. A second focus has highlighted the influence of occupant behaviour on carbon emissions. However, this overlooks the complex social interactions which together produce the built environment. There is room for seeking to unpack the social production of (un)sustainable buildings from design through construction to commissioning. These buildings significantly set the agenda for the behaviour of occupants whatever their level of carbon consciousness. In this paper we use the practices and role of property agents in the commercial property market as a window on the social production of (un)sustainable buildings.