bluuebunny/crossref_metadata_2025 huggingface dataset:
Putting the Common European Framework of Reference to good use
Authors: North Brian
Published: April 2011

This paper recapitulates the aims of the CEFR and highlights three aspects of good practice in exploiting it: firstly, taking as a starting point the real-world language ability that is the aim of all modern language learners; secondly, the exploitation of good descriptors as transparent learning objectives in order to involve and empower the learners; and thirdly, engaging with the communality of the CEFR Common Reference Levels in relating assessments to it. The second part of the paper focuses on good practice in such linking of assessments to the CEFR. It outlines the recommended procedures published by the Council of Europe for linking language examinations to the CEFR and the adaptation of those procedures for teacher assessment in language schools that has recently been undertaken by EAQUALS. The paper concludes by discussing certain aspects of criterion-referenced assessment (CR) and standard setting that are relevant to the linking process.
TRIPILLAR: a miniature magnetic caterpillar climbing robot with plane transition ability
Authors: Schoeneich Patrick , Rochat Frederic , Nguyen Olivier Truong-Dat , Moser Roland , Mondada Francesco
Published: April 2011

We present a miniature magnetic climbing robot with dimensions 96 × 46 × 64 mm3. With two degrees of freedom it is able to climb ferromagnetic surfaces and to make inner plane to plane transitions whatever their inclination is. This robot, named TRIPILLAR, combines triangular-shaped magnetic caterpillars and frame magnets. This particular configuration allows, for example, to move from ground to wall and ceiling and back. This achievement opens new avenues to use mobile robotics for industrial inspection with stringent size restrictions, such as the ones encountered in power plants.
Design of a controller for trajectory tracking for compliant mechanisms with effective vibration suppression
Authors: Boscariol P. , Zanotto V.
Published: April 2011

In this paper, a numerical investigation of the Model Predictive Control strategy applied to flexible-link mechanisms is presented. The mechanisms used for all the tests are a planar five-link mechanisms. The tests are aimed at showing how the proposed control system can be used for the trajectory tracking and the vibration suppression. An analysis of the effects of the choice of tuning parameters is presented as well. The design of the predictive controller is based on a linearized version of an accurate nonlinear dynamic model. The effectiveness of the proposed approach is confirmed by extensive numerical results.
Infection and white matter injury in infants with congenital cardiac disease
Authors: Glass Hannah C. , Bowman Chelsea , Chau Vann , Moosa Alisha , Hersh Adam L. , Campbell Andrew , Poskitt Kenneth , Azakie Anthony , Barkovich A. James , Miller Steven P. , McQuillen Patrick S.
Published: April 2011

More than 60% of newborns with severe congenital cardiac disease develop perioperative brain injuries. Known risk factors include: pre-operative hypoxemia, cardiopulmonary bypass characteristics, and post-operative hypotension. Infection is an established risk factor for white matter injury in premature newborns. In this study, we examined term infants with congenital cardiac disease requiring surgical repair to determine whether infection is associated with white matter injury. Acquired infection was specified by site – bloodstream, pneumonia, or surgical site infection – according to strict definitions. Infection was present in 23 of 127 infants. Pre- and post-operative imaging was evaluated for acquired injury by a paediatric neuroradiologist. Overall, there was no difference in newly acquired post-operative white matter injury in infants with infection (30%), compared to those without (31%). When stratified by anatomy, infants with transposition of the great arteries, and bloodstream infection had an estimated doubling of risk of white matter injury that was not significant, whereas those with single ventricle anatomy had no apparent added risk. When considering only infants without stroke, the estimated association was higher, and became significant after adjusting for duration of inotrope therapy. In this study, nosocomial infection was not associated with white matter injury. Nonetheless, when controlling for risk factors, there was an association between bloodstream infection and white matter injury in selected sub-populations. Infection prevention may have the potential to mitigate long-term neurologic impairment as a consequence of white matter injury, which underscores the importance of attention to infection control for these patients.
Middle-school students’ school lunch consumption does not meet the new Institute of Medicine's National School Lunch Program recommendations
Authors: Cullen Karen W , Watson Kathleen B , Dave Jayna M
Published: April 2011

Objective

To compare the school lunch consumption of Texas middle-school students with the 2009 Institute of Medicine's (IOM) school meal report recommendations. These new lunch menu patterns increase fruit to one serving and vegetables to two servings, with 50 % wholegrain food.

Design

Lunch food records were collected from middle-school students from four schools in south-east Texas in the spring of 2008, and entered into the Nutrition Data System for Research software. Average intake was calculated for those consuming meals according to the National School Lunch Program (NSLP;n5414) and for those consuming lunch from other sources (n239). The percentage of students selecting each food group was calculated.

Setting

Middle schools in south-east Texas.

Subjects

Middle-school students in south-east Texas.

Results

Students consuming NSLP meals reported consuming almost--><$>\tfrac{1}{2}<$><$>\tfrac{3}{4}<$><$>\tfrac{1}{3}<$><$>\tfrac{1}{4}<$><!--serving of whole grains at lunch. Among NSLP consumers, about 40 % selected and consumed a fruit serving. About two-thirds of students selected a vegetable, consuming about 67 %. Less than 4 % selected a dark green or orange vegetable.

Conclusions

Students’ lunch intake did not meet the new IOM recommendations. Few students selected dark green or orange vegetables, and only 40 % selected fruit. Whole grains consumption was low. Interventions with all stakeholders will be necessary to improve students’ food and beverage selections overall when school meal patterns are revised.
GaN HFET MMICs with integrated Schottky-diode for highly efficient digital switch-mode power amplifiers at 2 GHz
Authors: Maroldt Stephan , Quay Rüdiger , Haupt Christian , Kiefer Rudolf , Wiegner Dirk , Ambacher Oliver
Published: April 2011

This work describes the integration of Schottky diodes into fast GaN MMIC process technology suitable for the realization of switch-mode power amplifier core chips for class-S operation at 2 GHz. With the demonstration of this technology, the so-called third-quadrant issue, which reduces the efficiency in band pass-Δ-Σ class-S operation can be diminished on device level. Compared to a hybrid diode assembly, the broadband properties of the amplifier module with on-chip-integrated diode can be improved by the reduction of parasitic losses. The GaN heterostructure field effect transistors (HFETs) with integrated series diode show a cut-off frequency of 28 GHz with drain breakdown voltages exceeding −100 and +100 V and comparable large signal performance to conventional GaN HFETs at 10 GHz. MMIC core chips for class-D and class-S switch-mode power amplifier modules are demonstrated for the operation at mobile communication frequencies between 0.45 and 2 GHz and signal bit rates up to 8 Gbps. The circuits yield broadband output power levels between 4 and 9 W with efficiencies of up to 80%.
A homodyne transceiver MMIC using SiGe:C technology for 60 GHz wireless applications
Authors: Forstner Hans Peter , Ortner Markus , Verweyen Ludger , Knapp Herbert
Published: April 2011

A highly integrated transceiver microwave monolithic integrated circuit (MMIC) manufactured in a 200-GHz SiGe:C production technology is presented, applicable for sensing- and broadband communication applications. To simplify the analog frontend, the fully differential design is based on a homodyne architecture. It comprises an LO signal generation unit based on a wideband 60 GHz fundamental Voltage Controlled Oscillator (VCO) and an on-chip prescaler, covering the full operational frequency band of 57–64 GHz. Within this bandwidth, the upconverter exhibits an upconversion gain of 23.6–26.4 dB and a maximum output-referred 1-dB compression point of 14 dBm. The downconverter provides a Double Sideband (DSB) noise figure of 9–12 dB with a downconversion gain of 37–71 dB. On chip AC-coupling of the receiver IF-output with a lower −3 dB cut-off frequency as low as 16 kHz eliminates mixer DC-offsets and enables on-chip Intermediate Frequency (IF) amplification. The whole transceiver MMIC draws a current of 415 mA from a single 3.3 V supply and requires few components externally to the chip.
Neuropsychologie der Schizophrenie
Authors: Wölwer Wolfgang , Drusch Katharina
Published: April 2011

Zusammenfassung. Beeinträchtigungen im Bereich der basalen aber auch der sozialen Kognitionen treten weitgehend verlaufsstabil bei mehr als 75 % der schizophren Erkrankten auf und sind auch schon bei Hochrisikogruppen nachweisbar. Daher werden kognitive Störungen nicht mehr nur als Epiphänomene der Schizophrenie angesehen, sondern als Bestandteil der Kernsymptomatik schizophrener Erkrankungen betrachtet und zunehmend im Hinblick auf deren ätiopathogenetische Bedeutung als Vulnerabilitätsfaktoren und ‹Endophänotypen› diskutiert. Besondere klinische Relevanz erhalten kognitive Beeinträchtigungen durch ihre negativen Auswirkungen auf das psychosoziale Funktionsniveau und die Lebensqualität der Betroffenen. Da bisherige, primär auf eine Reduktion von Positiv- und Negativsymptomatik abzielende Therapiemaßnahmen nur marginale Verbesserungen kognitiver Leistungen erzielen, ruhen die Hoffnungen auf derzeit in der Entwicklung und Evaluation befindlichen gezielten kognitiven Rehabilitationsprogrammen.
Psychometrische Analyse eines neuen Fragebogens zur Erfassung der Akzeptanz von unangenehmen und angenehmen Gefühlen (FrAGe)
Authors: Beblo Thomas , Scheulen Caroline , Fernando Silvia Carvalho , Griepenstroh Julia , Aschenbrenner Steffen , Rodewald Katlehn , Driessen Martin
Published: April 2011

Zusammenfassung. Die Akzeptanz von Gefühlen ist eine zentrale, der psychischen Gesundheit dienliche Emotionsregulationsstrategie. Das Ziel dieser Untersuchung besteht in einer ersten Überprüfung der testtheoretischen Kennwerte eines neu entwickelten Fragebogens zur Akzeptanz von unangenehmen und angenehmen Gefühlen. In zwei Studien mit 171 und 207 nicht klinischen Probanden wurden die testtheoretischen Kennwerte des ‹Fragebogens zur Akzeptanz von Gefühlen (FrAGe)› bestimmt. Der FrAGe enthält Items aus den Bereichen Akzeptanz angenehmer Gefühle, Akzeptanz unangenehmer Gefühle, Unterdrückung angenehmer Gefühle und Unterdrückung unangenehmer Gefühle. Zur ersten Validierung wurden die ‹Difficulties in Emotion Regulation Scale (DERS)› und eine Kurzversion der ‹Symptomcheckliste (SCL-K-9)› eingesetzt. Die ursprüngliche Fragebogenversion mit 40 Items wurde in der ersten Studie auf Basis von Itemanalysen überarbeitet und auf 32 Items gekürzt. Die zweite Studie zeigte gute bis zufriedenstellende Itemkennwerte sowie eine entsprechende Reliabilität und Validität des FrAGe. Einige Items im Bereich angenehmer Gefühle zeigten bei den nicht klinischen Probanden erwartungsgemäß extremere Itemmittelwerte. Insgesamt sprechen die Ergebnisse für gute psychometrische Eigenschaften des FrAGe. Bei nicht klinischen Personen ist insbesondere die Erfassung von Emotionsakzeptanz unangenehmer Gefühle empfehlenswert.
Difference in response reliability predicted by STRFs in the cochlear nuclei of barn owls
Authors: Steinberg Louisa , Pena Jose
Published: April 2011

The brainstem auditory pathway is obligatory for all aural information. Brainstem auditory neurons must encode the level and timing of sounds, as well as their time-dependent spectral properties, the fine structure and envelope, which are essential for sound discrimination. This study focused on envelope coding in the two cochlear nuclei of the barn owl, nucleus angularis (NA) and nucleus magnocellularis (NM). NA and NM receive input from bifurcating auditory nerve fibers and initiate processing pathways specialized in encoding interaural time (ITD) and level (ILD) differences, respectively. We found that NA neurons, though unable to accurately encode stimulus phase, lock more strongly to the stimulus envelope than NM units. The spectrotemporal receptive fields (STRFs) of NA neurons exhibit a pre-excitatory suppressive field. Using multilinear regression analysis and computational modeling, we show that this feature of STRFs can account for enhanced across-trial response reliability, by locking spikes to the stimulus envelope. Our findings indicate a dichotomy in envelope coding between the time and intensity processing pathways as early as the level of the cochlear nuclei. This allows the ILD processing pathway to encode envelope information with greater fidelity than the ITD processing pathway. Furthermore, we demonstrate that the properties of the neurons’ STRFs can be quantitatively related to spike timing reliability.
Control in technological systems and physical intelligence: an emerging theory
Authors: Alicea Bradly
Published: April 2011

The transduction and processing of physical information is becoming important in a range of research fields, from the design of materials and virtual environments to the dynamics of cellular microenvironments. Previous approaches such as morphological computation/soft robotics, neuromechanics, and embodiment have provided valuable insight. This work approaches haptic, proprioception, and physical sensing as all part of the same subject. In this presentation, three design criteria for applying physical intelligence to engineering applications will be presented. These criteria have several properties in common, which inspires two types of end-effector model: stochastic (based on a spring) and deterministic (based on a piezomechanical array). The generalized behavior and output dynamics of these models can be described as three findings summarized from previous work. In conclusion, future directions for modeling neural control using a neuromorphic approach will be discussed.
The reality behind the rhetoric: How European policies risk harming access to generic medicines in developing countries
Authors: Arkinstall James , Childs Michelle , Menghaney Leena , Ford Nathan , von Schoen-Angerer Tido
Published: April 2011

The availability of affordable generic medicines has been critical to expanding access to treatment for HIV/AIDS and other diseases in developing countries. In recent years, access to generics has come under threat by the global enforcement of minimum standards for intellectual property protection as determined by the World Trade Organization, together with additional policy measures promoted by the European Commission and others. Data exclusivity, border control measures, counterfeit legislation, the undermining of judicial process and patent term extensions all threaten to limit the ability of developing countries to access affordable medicines. The potential harm caused by these policies is magnified by the fact that the global economic crisis is resulting in shortfalls of donor funding to fight HIV/AIDS and other infectious diseases.
Spain launches a new campaign to promote greater generic drug utilisation
Authors: Olmos Jose Martínez
Published: April 2011

In Spain, the main goal of pharmaceutical provision is to provide access to all patients to the medicines they need in a timely and appropriate manner, in conformity with the sustainability of medium and long-term provision. These objectives of sustainability and efficiency attach great importance to the promotion of generic medicines. We have been working to promote generic medicines for many years, but since we started later than many of our neighbouring countries, we have not achieved the same level of use. However, we have a reference price system that enables us to set a maximum financing price for all medicines containing the same active ingredient and having the same route of administration once the innovator's patent protection has expired and a generic version has been launched. In the first half of 2010, the generic medicines market experienced significant growth in units, reaching a public market share of 26.02 per cent per prescription. In order to give them fresh impetus and continue working in this line of growth, a specific Plan has been adopted. This Plan emphasises the provision of information and education to citizens; the participation of community pharmacies in providing information to citizens and dispensing generic medicines; the provision of information and training to health professionals on their quality, safety and efficacy; and the streamlining of the marketing authorisation procedure and decision-making process on their public financing.
How suitable are the suitability petition and 505(b)(2)?
Authors: Chokshi Nirav , Modi Bhaumik
Published: April 2011

Two routes are well known for filing the variation from the approved RLD as a generic player in the US market that is, filing an Abbreviated New Drug Application (ANDA) following the approval of Suitability Petition (SP) filing and another is filing New Drug Application (NDA) inline with 505(b)(2) of the act. The SP process is addressed in 21 CFR part 10.20 and 10.30, 314.54, 314.93. Most of the times it become confusing in selecting the appropriate route of filing and evaluating their common and uncommon requirements. Underlining information in this article helps in understating the filing requirement of each route and the way in which the US Food and Drug Administration (FDA) has recently begun using its authority for variations is critical for choosing the appropriate path. The differences between the SP and the 505(b)(2) NDA submission are also discussed in department.
Strong persistence of an attractor and generalized partial synchronization in a coupled chaotic system
Authors: Manjunath G. , Fournier-Prunaret D.
Published: April 2011

It is widely believed that when two discrete time chaotic systems are coupled together then there is a contraction in the phase space (where the essential dynamics takes place) when compared with the phase space in the uncoupled case. Contrary to such a popular belief, we produce a counter example—we consider two discrete time chaotic systems both with an identical attractor A, and show that the two systems could be nonlinearly coupled in a way such that the coupled system’s attractor persists strongly, i.e., it is A × A despite the coupling strength is varied from zero to a nonzero value. To show this, we prove robust topological mixing on A × A. Also, it is of interest that the studied coupled system can exhibit a type of synchronization called generalized partial synchronization which is also robust.
Study of ultrahigh Atwood-number Rayleigh–Taylor mixing dynamics using the nonlinear large-eddy simulation method
Authors: Burton Gregory C.
Published: April 2011

The Nonlinear Large-Eddy Simulation (nLES) method [G. C. Burton, “The nonlinear large-eddy simulation method (nLES) applied to Sc≈1 and Sc⪢1 passive-scalar mixing,” Phys. Fluids 20, 035103 (2008)] is employed in the first numerical study of multimode miscible Rayleigh–Taylor instability (RTI) in the ultrahigh Atwood-number regime above A≥0.90. The present work focuses on the dynamics of turbulent mixing at the large density ratios that may be encountered in certain astrophysical contexts and engineering applications. Using the initial condition from the landmark (N=30723) direct numerical study of Cabot and Cook [W. Cabot and A. W. Cook, “Reynolds number effects on Rayleigh-Taylor instability with possible implications for type-Ia supernovae,” Nat. Phys. 2, 562 (2006)], the nLES method is first validated in simulations of A=0.5 RTI mixing and is shown to recover important statistical measures of the mixing process, such as bubble and spike growth rates and mixing efficiency reported in that study, but at the significantly coarser resolutions typical of most large-eddy simulations. The first simulations of RTI at Atwood numbers A>0.90 are then used to explore the effects of varying the density ratio on mixing dynamics at very high Atwood numbers 0.75≤A≤0.96. Spike heights and mixing layer growth rates are shown to be strongly affected by the initial density ratio. An empirical power-law scaling relationship is shown to predict nearly exactly the variation in the ratio of spike to bubble heights as a function of Atwood number. Mixing efficiency is shown to be influenced by the initial density difference but the competition between increased molecular mixing and entrainment largely cancel, producing a relatively modest variation in these flow parameters when compared with the intermediate Atwood-number case. Late-time power spectra show the appearance of an inertial range, indicating that the mixing layer has transitioned to a fully turbulent state. The role of bubble and spike structures in the interscale transfer of kinetic energy is explored for the first time for high Atwood-number RTI flows. Bubble heads (stems) are shown to produce forward (reverse) transfer due to compressive (extensional) straining at intermediate Atwood number. At high Atwood number, however, spike stems are shown to produce forward transfer due to compressive straining generated from the larger spike penetration velocity and the differing spike morphology produced at the higher Atwood number. The study indicates that stable and accurate simulations of ultrahigh Atwood-number mixing may be conducted using the nLES method on grids significantly coarser than used previously to examine RTI flows.
Apparent sixfold configurational anisotropy and spatial confinement of ferromagnetic resonances in hexagonal magnetic antidot lattices
Authors: Krivoruchko V. N. , Marchenko A. I.
Published: April 2011

The static and dynamic properties of hexagonal lattices of magnetic antidots have been studied using micromagnetic simulations and semianalytical modeling. The theoretical model is based on the Landau–Lifshitz equation and is developed for the case of comparable magnitudes of the field and linewidth of the ferromagnetic resonance (FMR). It is found that the antidot pattern induces an apparent sixfold configurational anisotropy manifesting itself via an anisotropic resonant response of the patterned film. However, calculations performed with a reduced damping reveal that the resonance peak consists of three different quasiuniform modes of the magnetization dynamics, with the resonant field of each of them showing a twofold variation with respect to the in-plane orientation of the applied magnetic field. The easy axes of the resonant modes are mutually rotated by 60° and combine to yield the observed sixfold configurational anisotropy. Micromagnetic calculations of the local dynamic susceptibility allow us to attribute each absorption line to a different area of the sample. Finally, we analyze the effect of the antidot radius and the lattice period on the broadening of the uniform FMR line in comparison with the uniform FMR mode of the corresponding continuous film.
Computation of expectation values from vibrational coupled-cluster at the two-mode coupling level
Authors: Zoccante Alberto , Seidler Peter , Christiansen Ove
Published: April 2011

In this work we show how the vibrational coupled-cluster method at the two-mode coupling level can be used to calculate zero-point vibrational averages of properties. A technique is presented, where any expectation value can be calculated using a single set of Lagrangian multipliers computed solving iteratively a single linear set of equations. Sample calculations are presented which show that the resulting algorithm scales only with the third power of the number of modes, therefore making large systems accessible. Moreover, we present applications to water, pyrrole, and para-nitroaniline.
Observation of impurity free monoenergetic proton beams from the interaction of a CO2 laser with a gaseous target
Authors: Najmudin Z. , Palmer C. A. J. , Dover N. P. , Pogorelsky I. , Babzien M. , Dangor A. E. , Dudnikova G. I. , Foster P. S. , Green J. S. , Ispiriyan M. , Neely D. , Polyanskiy M. N. , Schreiber J. , Shkolnikov P. , Yakimenko V.
Published: April 2011

A monoenergetic proton beam is observed from the interaction of a short-pulse infrared (λ = 10.6 μm) laser at intensity I = 6 × 1015 W cm−2 with a gas jet target. The proton beam is found to have narrow energy spread (∼ 4% ), high spectral brightness (∼ 1012 protons/MeV/sr), low normalized emittance (εn ≈ 8 nm rad), and high contrast (> 200 × over noise). The narrow energy spread and low levels of impurity makes this method an interesting route for high-repetition rate high quality proton beam production.
Temperature dependence of tunability of Ba(SnxTi1−x)O3 ceramics
Authors: Curecheriu Lavinia P. , Ianculescu Adelina C. , Horchidan Nadejda , Stoleriu Stefania , Tudorache Florin , Tascu Sorin , Mitoseriu Liliana
Published: April 2011

The electric field dependence of the dielectric constant (dc-tunability) as a function of temperature for a few compositions of Ba(Sn,Ti)O3 ceramics was investigated. Dense and homogeneous BaSnxTi1−xO3 ceramics (ferroelectric for x = 0.05 and x = 0.10, relaxor for x = 0.15 and 0.20) with high dielectric constant and low dielectric losses were prepared by solid state reaction. Their dc-tunability characteristics were investigated at a few temperatures from 20–120 °C, including the Curie range. The tunability data were discussed in terms of the Johnson model completed with a Langevin term that describes the “extrinsic” contribution to the nonlinear ɛ(E) dependences.
Effects of magnetic field and transverse anisotropy on full counting statistics in single-molecule magnet
Authors: Xue Hai-Bin , Nie Y.-H. , Li Z.-J. , Liang J.-Q.
Published: April 2011

We have theoretically studied the full counting statistics of electron transport through a single-molecule magnet (SMM) with an arbitrary angle between the applied magnetic field and the SMM’s easy axis above the sequential tunneling threshold, since the angle θ cannot be controlled in present-day SMM experiments. In the absence of the small transverse anisotropy, when the coupling of the SMM with the incident-electrode is stronger than that with the outgoing-electrode, i.e., ΓL/ΓR>>1, the maximum peak of shot noise first increases and then decreases with increasing θ from 0 to 0.5π. In particular, the shot noise can reach up to a super-Poissonian value from a sub-Poissonian value when considering the small transverse anisotropy. For ΓL/ΓR≪ 1, the maximum peaks of the shot noise and skewness can be reduced from a super-Poissonian to a sub-Poissonian value with increasing θ from 0 to 0.5π; the super-Poissonian behavior of the skewness is more sensitive to the small θ than shot noise, which is suppressed when taking into account the small transverse anisotropy. These characteristics of shot noise can be qualitatively attributed to the competition between the fast and slow transport channels. The predictions regarding the θ- dependence of high order current cumulants are very interesting for a better understanding of electron transport through SMM, and will allow for experimental tests in the near future.
Electronic structure of 1/6〈202¯3〉 partial dislocations in wurtzite GaN
Authors: Kioseoglou J. , Kalesaki E. , Lymperakis L. , Neugebauer J. , Komninou Ph. , Karakostas Th.
Published: April 2011

The I1 intrinsic basal stacking faults (BSFs) are acknowledged as the principal defects observed on {112¯0} (a-plane) and {11¯00} (m-plane) grown GaN. Their importance is established by recent experimental results, which correlate the partial dislocations (PDs) bounding I1 BSFs to the luminescence characteristics of GaN. PDs are also found to play a critical role in the alleviation of misfit strain in hetero-epitaxially grown nonpolar and semipolar films. In the present study, the energetics and the electronic structure of twelve edge and mixed 1/6〈202¯3〉 PD configurations are investigated by first principles calculations. The specific PD cores of the dislocation loop bounding the I1 BSF are identified for III-rich and N-rich growth conditions. The core structures of PDs induce multiple shallow and deep states, attributed to the low coordinated core atoms, indicating that the cores are electrically active. In contrast to edge type threading dislocations no strain induced states are found.
Chemistry of Ruddlesden–Popper planar faults at a ferroelectric–ferromagnet perovskite interface
Authors: Arredondo M. , Weyland M. , Hambe M. , Ramasse Q. M. , Munroe P. , Nagarajan V.
Published: April 2011

We investigate the interfacial structure of PbZr0.20Ti0.80O3 (PZT)/La0.67Sr0.33MnO3 (LSMO)/SrTiO3 heterostructures by combining low-magnification transmission electron microscopy imaging and spectroscopy techniques with high-resolution spherical-aberration corrected scanning transmission electron microscopy imaging, geometrical phase analysis, and spectroscopy results. For certain thickness regimes, the interface between PZT and LSMO is found to have a significant density of planar defects at the interface. Both A-site cation (Pb) diffusivity and highly inhomogeneous local strains are observed at the boundaries of the defect areas. It is proposed that Pb is incorporated as PbO Ruddlesden–Popper planar fault within the LSMO. These results underline the importance of chemical fluctuations caused by long-range strain fields associated with defect cores.
A “dry and wet hybrid” lithography technique for multilevel replication templates: Applications to microfluidic neuron culture and two-phase global mixing
Authors: Paul Debjani , Saias Laure , Pedinotti Jean-Cedric , Chabert Max , Magnifico Sebastien , Pallandre Antoine , De Lambert Bertrand , Houdayer Claude , Brugg Bernard , Peyrin Jean-Michel , Viovy Jean-Louis
Published: April 2011

A broad range of microfluidic applications, ranging from cell culture to protein crystallization, requires multilevel devices with different heights and feature sizes (from micrometers to millimeters). While state-of-the-art direct-writing techniques have been developed for creating complex three-dimensional shapes, replication molding from a multilevel template is still the preferred method for fast prototyping of microfluidic devices in the laboratory. Here, we report on a “dry and wet hybrid” technique to fabricate multilevel replication molds by combining SU-8 lithography with a dry film resist (Ordyl). We show that the two lithography protocols are chemically compatible with each other. Finally, we demonstrate the hybrid technique in two different microfluidic applications: (1) a neuron culture device with compartmentalization of different elements of a neuron and (2) a two-phase (gas-liquid) global micromixer for fast mixing of a small amount of a viscous liquid into a larger volume of a less viscous liquid.
Testing facility for hydrogen storage materials designed to simulate application based conditions
Authors: Westerwaal R. J. , Nyqvist R. G. , Haije W. G.
Published: April 2011

For the daily use of hydrogen storage materials, not only their intrinsic storage properties are important, but also equally important is the performance under practical conditions. Besides the techniques already available for the fundamental characterization of storage materials, there is a growing need to test storage materials under conditions resembling day-to-day use. For that we developed and tested a downscaled hydrogen storage reactor with which it is possible to monitor the hydrogenation behavior under nonideal conditions. Here we present a characterization of the developed reactor setup which enables a fast screening of storage materials. For characterization and calibration purposes, we use the rather well-documented LaNi5–Al alloy as reference. The found experimental results agree well with the properties of LaNi5–Al as reported in literature. Our results show that this reactor setup enables an efficient screening of new developed storage alloys under realistic conditions and is therefore complementary to the already existing characterization setups.
An accelerated algorithm for discrete stochastic simulation of reaction–diffusion systems using gradient-based diffusion and tau-leaping
Authors: Koh Wonryull , Blackwell Kim T.
Published: April 2011

Stochastic simulation of reaction–diffusion systems enables the investigation of stochastic events arising from the small numbers and heterogeneous distribution of molecular species in biological cells. Stochastic variations in intracellular microdomains and in diffusional gradients play a significant part in the spatiotemporal activity and behavior of cells. Although an exact stochastic simulation that simulates every individual reaction and diffusion event gives a most accurate trajectory of the system's state over time, it can be too slow for many practical applications. We present an accelerated algorithm for discrete stochastic simulation of reaction–diffusion systems designed to improve the speed of simulation by reducing the number of time-steps required to complete a simulation run. This method is unique in that it employs two strategies that have not been incorporated in existing spatial stochastic simulation algorithms. First, diffusive transfers between neighboring subvolumes are based on concentration gradients. This treatment necessitates sampling of only the net or observed diffusion events from higher to lower concentration gradients rather than sampling all diffusion events regardless of local concentration gradients. Second, we extend the non-negative Poisson tau-leaping method that was originally developed for speeding up nonspatial or homogeneous stochastic simulation algorithms. This method calculates each leap time in a unified step for both reaction and diffusion processes while satisfying the leap condition that the propensities do not change appreciably during the leap and ensuring that leaping does not cause molecular populations to become negative. Numerical results are presented that illustrate the improvement in simulation speed achieved by incorporating these two new strategies.
Work function engineering in silicides: Chlorine doping in NiSi
Authors: Slepko Alexander , Demkov Alexander A. , Loh W.-Y. , Majhi P. , Bersuker G.
Published: April 2011

We present a study of the electronic properties of chlorine-doped NiSi and ClNiSi/Si contacts by means of density functional theory (DFT). Using DFT, we consider the theoretical effect of Cl doping in orthorhombic Pbnm NiSi and its impact on the work function, Schottky barrier with Si, and on the change in conductivity caused by impurity scattering. Our calculations suggest that Cl substitution on the Si site is energetically preferable. The thermodynamic analysis shows that chlorine at the surface lowers the surface energy. We find that Cl can reduce the work function of NiSi by as much as ∼100 meV, and that the Schottky barrier with Si strongly depends on the position of the substitutional chlorine. Electric conductivity of NiSi is found to be significantly reduced even for the lowest calculated Cl concentration. Both findings are validated experimentally.
Deformation behavior of a Cu-based amorphous alloy under different strain rates
Authors: Tian Y. B. , Lin J. G. , Li W. , Ma M. , Luo Z. C. , Jiang W. J.
Published: April 2011

The compressive deformation behavior of (Cu50Zr50)92Al8 BMG under the different strain rates ranging from 6.25 × 10−4s−1 to 2 × 10−2s−1 within the super-cooled liquid region was characterized, and the effect of the plastic deformation on the mechanical properties of the alloy was investigated. It was found that the plastic flow behavior was strongly dependent on the test temperature and applied strain rates. The BMG exhibited nearly Newtonian behavior below the strain rate of 5 × 10−3s−1 at 750K, but non-Newtonian at the high strain rates and low temperatures. The non-Newtonian plastic deformation promoted the formation of nano-crystalline in the amorphous matrix, which reduced the fracture strength of (Cu50Zr50)92Al8 BMG at room temperature.
Measurement of the Kapitza resistance across a bicrystal interface
Authors: Hurley D. H. , Khafizov M. , Shinde S. L.
Published: April 2011

The Kapitza resistance across a Si bicrystal interface was measured using a pump probe optical technique. This approach, termed time resolved thermal wave microscopy (TRTWM), uses ultrafast laser pulses to image lateral thermal transport in bare semiconductors. The sample geometry is that of a Si bicrystal with the vertically oriented boundary intersecting the sample surface. High resolution transmission electron microscopy of the boundary region revealed a thin SiO2 layer at the interface. By comparing experimental results with a continuum thermal transport model the Kapitza resistance between the Si and SiO2 was estimated to be 2.3 × 10−9 m2K/W.
Influence of gate dielectrics on the performance of single-layered organic transistors and bi-layered organic light-emitting transistors prepared by the neutral cluster beam deposition method
Authors: Zhang Ying , Seo Hoon-Seok , An Min-Jun , Oh Jeong-Do , Choi Jong-Ho
Published: April 2011

The influence of two different SiO2 and polymethylmethacrylate (PMMA) gate dielectrics on the performance of single-layered organic field-effect transistors and bi-layered organic light-emitting field-effect transistors was examined. Organic active layers of p-type α,ω-dihexylsexithiophene and n-type N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide were prepared using the neutral cluster beam deposition method. Characterization of surface morphology, contact angles, structural properties and temperature dependence of field-effect mobilities measured over the temperature range of 10–300 K revealed that compared to the SiO2 dielectrics, the hydroxyl-free PMMA dielectrics provided better conditions for crystalline film growth. The PMMA-based device characteristics exhibited excellent field-effect mobilities, stress-free operational stability, and electroluminescence through efficient carrier transport and well-balanced ambipolarity under ambient conditions.
Correlation of interface roughness for ion beam sputter deposited W/Si multilayers
Authors: Biswas A. , Bhattacharyya D.
Published: April 2011

W/Si multilayers having 5, 7, 9, 13, 17, and 25 layers have been deposited on c-Si substrates by Ion Beam Sputtering technique and have been characterized by specular and diffused grazing incidence X-ray reflectivity measurements. Information regarding the density, thickness and interface widths of individual layers of the multilayer stacks have been obtained from the theoretical fitting of the specular reflectivity spectra while fitting of the diffused X-ray reflectivity have yielded information regarding roughness and diffusivity at the individual interfaces along with the in-plane correlation lengths of roughness of the individual layers and the vertical correlation length of the whole multilayer structure. Investigations have been carried out on the different behavior of W-on-Si and Si-on-W interfaces and on the variation of the above parameters with the increase in number of layers in the multilayer structures.
Geometry and energy of non-Abelian vortices
Authors: Manton Nicholas S. , Rink Norman A.
Published: April 2011

We study pure Yang–Mills theory on Σ × S2, where Σ is a compact Riemann surface, and invariance is assumed under rotations of S2. It is well known that the self-duality equations in this setup reduce to vortex equations on Σ. If the Yang–Mills gauge group is SU(2), the Bogomolny vortex equations of the Abelian Higgs model are obtained. For larger gauge groups, one generally finds vortex equations involving several matrix-valued Higgs fields. Here we focus on Yang–Mills theory with gauge group \documentclass[12pt]{minimal}\begin{document}$\mathrm{SU}(N)/\mathbb {Z}_N$\end{document} SU (N)/ZN and a special reduction which yields only one non-Abelian Higgs field. One of the new features of this reduction is the fact that while the instanton number of the theory in four dimensions is generally fractional with denominator N, we still obtain an integral vortex number in the reduced theory. We clarify the relation between these two topological charges at a bundle geometric level. Another striking feature is the emergence of nontrivial lower and upper bounds for the energy of the reduced theory on Σ. These bounds are proportional to the area of Σ. We give special solutions of the theory on Σ by embedding solutions of the Abelian Higgs model into the non-Abelian theory, and we relate our work to the language of quiver bundles, which has recently proved fruitful in the study of dimensional reduction of Yang–Mills theory.
Tin-vacancy complex in germanium
Authors: Markevich V. P. , Peaker A. R. , Hamilton B. , Litvinov V. V. , Pokotilo Yu. M. , Lastovskii S. B. , Coutinho J. , Carvalho A. , Rayson M. J. , Briddon P. R.
Published: April 2011

Electrically active defects introduced into Ge crystals co-doped with tin and phosphorus atoms by irradiation with 6 MeV electrons have been studied by means of transient capacitance techniques and ab-initio density functional modeling. It is shown that Sn atoms are effective traps for vacancies (V) in the irradiated Ge:Sn+P crystals. The electronic structure of Sn-V is unraveled on the basis of hybrid states from a Sn atom and a divacancy. Unlike the case for Si, Sn-V in Ge is not a donor. A hole trap with 0.19 eV activation energy for hole emission to the valence band is assigned to an acceptor level of the Sn-V complex. The Sn-V complex anneals out upon heat-treatments in the temperature range 50–100 °C. Its disappearance is accompanied by the formation of phosphorus-vacancy centers.
Asymptotic behaviors of stochastic two-dimensional Navier–Stokes equations with finite memory
Authors: Wan Li , Zhou Qinghua
Published: April 2011

The stochastic 2D Navier–Stokes equations with finite memory are studied. For the differentiable memory function, the almost sure exponential stability of the weak solution is shown by employing a non-negative semimartingale convergence argument. For the nondifferentiable memory function, the exponential stability in mean square for the weak solution is proved by using the differentiability property of the moment function.
Nonperiodic stochastic boundary conditions for molecular dynamics simulations of materials embedded into a continuum mechanics domain
Authors: Rahimi Mohammad , Karimi-Varzaneh Hossein Ali , Böhm Michael C. , Müller-Plathe Florian , Pfaller Sebastian , Possart Gunnar , Steinmann Paul
Published: April 2011

A scheme is described for performing molecular dynamics simulations on polymers under nonperiodic, stochastic boundary conditions. It has been designed to allow later the embedding of a particle domain treated by molecular dynamics into a continuum environment treated by finite elements. It combines, in the boundary region, harmonically restrained particles to confine the system with dissipative particle dynamics to dissipate energy and to thermostat the simulation. The equilibrium position of the tethered particles, the so-called anchor points, are well suited for transmitting deformations, forces and force derivatives between the particle and continuum domains. In the present work the particle scheme is tested by comparing results for coarse-grained polystyrene melts under nonperiodic and regular periodic boundary conditions. Excellent agreement is found for thermodynamic, structural, and dynamic properties.
Ballistic phonon transmission in quasiperiodic acoustic nanocavities
Authors: Mo Yuan , Huang Wei-Qing , Huang Gui-Fang , Chen Yuan , Hu Wangyu , Wang Ling-Ling , Pan Anlian
Published: April 2011

Ballistic phonon transport is investigated in acoustic nanocavities modulated in a quasiperiodic manner at low temperatures. Two different types of quasiperiodic acoustic nanocavities are considered: the lengths of nanocavities (QPL) and the lengths of the bridges (QPD) connecting two successive nanocavities are modulated according to the Fibonacci rule. We demonstrate that the transmission spectra and thermal conductance in both systems are similar, which is more prominent in QPD than in QPL. The transmission and thermal conductance of QPD are larger than those of QPL due to the fact that constant nanocavity length in QPD would strengthen ballistic phonon resonant transport, while varying nanocavity length in QPL lead to strong phonon scattering.
Self-eliminating instrumental frequency response from free carrier absorption signals for silicon wafer characterization
Authors: Huang Qiuping , Li Bincheng
Published: April 2011

Accurate determination of electronic transport properties of semiconductor wafers with modulated free carrier absorption (MFCA) and multiparameter fitting requires the total elimination of instrumental response from the MFCA signals. In this paper, an approach to eliminate the effect of instrumental response on the frequency dependence of MFCA amplitude and phase is developed both theoretically and experimentally to simultaneously determine the transport properties (minority-carrier lifetime, carrier diffusion coefficient, and front surface recombination velocity) of silicon wafers. Experimental results showed that with the proposed method the instrumental frequency response was fully eliminated from the experimental MFCA data and had no impact on the multiparameter fitting, while with conventional methods the accuracy of the fitted transport parameters was influenced detrimentally by the errors of the measured instrumental frequency responses, in particular for the minority-carrier lifetime and the front surface recombination velocity.
Constructing a force interaction model for thermal conductivity computation using molecular dynamics simulation: Ethylene glycol as an example
Authors: Lin Yung-Sheng , Hsiao Pai-Yi , Chieng Ching-Chang
Published: April 2011

This study aims to construct a force interaction model for thermal conductivity computation and to analyze the liquid properties in atomic level for liquid ethylene glycol (EG) using molecular dynamic simulation. The microscopic details of the molecular system and the macroscopic properties of experimental interest are connected by Green–Kubo relations. In addition, the major contributions of heat transfer modes for thermal conductivity due to convection, interaction, and torque are obtained quantitatively. This study reveals that the intramolecular interaction force fields result in different conformations of the EG in the liquid and thus the molecular shapes. The trans/gauche ratio for EG's O–Me–Me–O torsional angle and the number of intermolecular/intramolecular H-bonds are found to be important parameters affecting the thermal conductivity.
Semiconductor-metal transition in thin VO2 films grown by ozone based atomic layer deposition
Authors: Rampelberg Geert , Schaekers Marc , Martens Koen , Xie Qi , Deduytsche Davy , De Schutter Bob , Blasco Nicolas , Kittl Jorge , Detavernier Christophe
Published: April 2011

Thin films of vanadium dioxide (VO2) have been grown by a low temperature atomic layer deposition process at 150 °C using tetrakis[ethylmethylamino]vanadium as a vanadium source and ozone as reactant gas. Films deposited on SiO2 were amorphous, but during a thermal treatment at 450 °C tetragonal VO2(R) was formed. During in situ x-ray diffraction measurements, the semiconductor–metal transition was observed as a reversible transition between VO2(M1) and VO2(R) near 67 °C. Correlated with this phase change, a reversible change in resistivity was observed of more than two orders of magnitude for a film of 42 nm thickness.