bluuebunny/crossref_metadata_2025 huggingface dataset:
External auditory canal paraganglioma: an atypical presentation
Authors: Grover N , Amen F , Gallimore A , Brookes G
Published: October 2012

Objective:

We present the first published description of a painful paraganglioma of the external auditory canal. Atypical histopathology made the diagnosis difficult. We discuss the potential pitfalls of clinical diagnosis and treatment of such a case.

Clinical presentation:

A 49-year-old woman presented with left-sided otalgia, hearing loss and tinnitus. Physical examination revealed a firm swelling arising from the superior portion of the left external auditory canal. A clinical diagnosis of otitis externa was made.

Intervention:

There was minimal response to medical treatment. The swelling was aspirated, leading to brisk bleeding. A tumour was suspected from the computed tomography scan, and confirmed by a biopsy. The patient underwent excision of the paraganglioma. The histopathology was atypical, making diagnosis difficult.

Conclusion:

Such unusual masses of the external ear should always be borne in mind, especially when dealing with atypical presentations of commonly encountered diseases. Clinicians should have a low threshold for early intervention with imaging and biopsy.
The role of negative emotionality and impulsivity in depressive/anxiety disorders and alcohol dependence
Authors: Boschloo L. , Vogelzangs N. , van den Brink W. , Smit J. H. , Beekman A. T. F. , Penninx B. W. J. H.
Published: October 2012

Background

Much is still unclear about the role of personality in the structure of common psychiatric disorders such as depressive/anxiety disorders and alcohol dependence. This study will therefore examine whether various traits of negative emotionality and impulsivity showed shared or specific associations with these disorders.

Method

Cross-sectional data were used from the Netherlands Study of Depression and Anxiety (NESDA), including individuals with no DSM-IV psychiatric disorder (n = 460), depressive/anxiety disorder only (i.e. depressive and/or anxiety disorder; n = 1398), alcohol dependence only (n = 32) and co-morbid depressive/anxiety disorder plus alcohol dependence (n = 358). Aspects of negative emotionality were neuroticism, hopelessness, rumination, worry and anxiety sensitivity, whereas aspects of impulsivity included disinhibition, thrill/adventure seeking, experience seeking and boredom susceptibility.

Results

Aspects of negative emotionality formed a homogeneous dimension, which was unrelated to the more heterogeneous construct of impulsivity. Although all aspects of negative emotionality were associated with alcohol dependence only, associations were much stronger for depressive/anxiety disorder only and co-morbid depressive/anxiety disorder with alcohol dependence. The results for impulsivity traits were less profound and more variable, with disinhibition and boredom susceptibility showing modest associations with both depressive/anxiety disorder and alcohol dependence, whereas low thrill/adventure seeking and high disinhibition were more strongly related with the first and the latter, respectively.

Conclusions

Our results suggest that depressive/anxiety disorder and alcohol dependence result from shared as well as specific aetiological pathways as they showed the same associations with all aspects of negative emotionality, disinhibition and boredom susceptibility as well as specific associations with thrill/adventure seeking and disinhibition.
Enlarging operational workspaces in parallel manipulators by connecting working modes. Application to the 3

R

SS robot
Authors: Macho E. , Altuzarra O. , Pinto C. , Hernández A.
Published: October 2012

The aim of this paper is to describe a general methodology for enlarging the workspace within which a parallel manipulator can move in a controllable way. The basis for obtaining this consists in superimposing all the singularity-free regions associated with the various different robot working modes. These can be connected because such transitions do not imply a loss of control of the manipulator. This enlarged operational workspace is associated with a certain assembly mode. In addition, the strategy to be used for path planning in this kind of workspace is presented.
Development of Support Networks in Informal Dementia Care: Guided, Organic, and Chance Routes through Support
Authors: Egdell Valerie
Published: October 2012

Increasing knowledge about factors that shape the development of care networks for people with dementia is imperative in countries with aging populations that are relying increasingly on informal care. This study used a qualitative approach to identify the complex routes through support taken by informal caregivers for people with dementia in the development of their care networks. Interview data were collected from 13 caregivers. Three routes through support were identified: guided routes, organic routes, and chance routes. This article’s principal argument is that these routes are the outcomes not only of the resources that caregivers draw upon, but also of their varying expectations regarding the role of the informal caregiver. The identification of the three routes through support provides a potentially valuable framework for examining the experiences of caregivers for individuals with other long-term health conditions.
Medical management of hip fractures and the role of the orthogeriatrician
Authors: Gupta Abhaya
Published: October 2012

Published literature shows that evidence-based medical care can improve hip fracture outcomes. The orthogeriatrician plays a key role in providing this care, in collaboration with surgical and multidisciplinary professionals, managing pre-operative conditions and post-operative complications that may affect functional recovery, and ensuring co-ordinated effective management of hip fractures right from admission to discharge. Several management guidelines are available for this vulnerable group of elderly patients. Recent UK guidelines recommend that, from time of admission, hip fracture patients should be offered a formal acute orthogeriatric or orthopaedic ward-based ‘Hip Fracture Programme’, which includes orthogeriatric assessment as an essential key component.
Explosive Percolation in Erdős–Rényi-Like Random Graph Processes
Authors: PANAGIOTOU KONSTANTINOS , SPÖHEL RETO , STEGER ANGELIKA , THOMAS HENNING
Published: October 2012

The study of the phase transition of random graph processes, and recently in particular Achlioptas processes, has attracted much attention. Achlioptas, D'Souza and Spencer (Science, 2009) gave strong numerical evidence that a variety of edge-selection rules in Achlioptas processes exhibit a discontinuous phase transition. However, Riordan and Warnke (Science, 2011) recently showed that all these processes have a continuous phase transition.

In this work we prove discontinuous phase transitions for three random graph processes: all three start with the empty graph on n vertices and, depending on the process, we connect in every step (i) one vertex chosen randomly from all vertices and one chosen randomly from a restricted set of vertices, (ii) two components chosen randomly from the set of all components, or (iii) a randomly chosen vertex and a randomly chosen component.
Neonatal ascending aortic thrombus: successful medical treatment
Authors: Gallotti Roberto , Cammock Cheryl E. , Dixon Natalia , Ootaki Yoshio
Published: October 2012

Neonatal aortic thrombosis is a potentially life-threatening condition with significant morbidity and mortality if undiagnosed and untreated. The most common location of arterial thrombosis in neonates is in the abdominal aorta and is associated with umbilical artery catheterisation. There are only a few previous reports of thrombosis in the ascending aorta. We describe a case of ascending aortic thrombosis in a neonate who underwent successful thrombolytic therapy.
Flood-Related Work Disruption and Poor Health Outcomes Among University Students
Authors: Peek-Asa Corinne , Ramirez Marizen , Young Tracy , Cao YanYan
Published: October 2012

Introduction

Globally, floods are the most common and among the most devastating of natural disasters. Natural disasters such as floods impact local businesses, increasing local unemployment by up to 8.2%. Previous research has linked individual losses from disasters with symptoms such as posttraumatic stress disorder. However, little is known about the impact of work disruption and job loss on post-disaster psychological symptoms. University students, who are often living far away from family support structures and have limited resources, may be particularly vulnerable. This study examines student psychological health following a large flood at a university.

Hypothesis

Students who experienced flood-related job loss or disruption had a higher proportion of psychological symptoms than those who did not experience job loss or disruption, controlling for individual loss such as injury, home loss or evacuation.

Methods

On June 8, 2008, a major flood affected seven US Midwestern states. A total of two dozen people were killed and 148 injured, although no deaths or serious injuries were reported in the population used for this study. At the study university, operations were closed for one week, and 20 buildings were severely damaged. A cross-sectional survey of all students enrolled during the semester of the flood was conducted. Students were sent an online survey six weeks after the flood. In addition to questions about damage to their homes, the survey asked students if their work was disrupted because of the floods. Symptoms of PTSD were measured through the modified Child PTSD Symptom Scale.

Results

Of the 1,231 responding students with complete surveys, 667 (54.2%) reported that their work was disrupted due to the floods. Controlling for gender, ethnicity, grade, and damage to the student's home, students reporting work disruption were more than four times more likely to report PTSD symptoms (95% CI, 2.5-8.2). Work disruption was independently associated with decreases in general mental and physical health following the floods, as well as with increases in alcohol use.

Conclusion

Disaster research has focused on damage to individuals and homes, but there has been little focus on work losses. Individuals who lose their jobs may be a vulnerable population post-disaster.

Peek-AsaC, RamirezM, YoungT, CaoY. Flood-related work disruption and poor health outcomes among university students. Prehosp Disaster Med. 2012;27(6):1-6.
ANTIREALISM AND CONSTRUCTIVISM: BROUWER’S WEAK COUNTEREXAMPLES
Authors: McCARTY CHARLES
Published: October 2012

Strictly intuitionistic inferences are employed to demonstrate that three conditions—the existence of Brouwerian weak counterexamples to Test, the recognition condition, and the BHK interpretation of the logical signs—are together inconsistent. Therefore, if the logical signs in mathematical statements governed by the recognition condition are constructive in that they satisfy the clauses of the BHK, then every relevant instance of the classical principle Test is true intuitionistically, and the antirealistic critique of conventional logic, once thought to yield such weak counterexamples, is seen, in this instance, to fail.
Kompensatorische Förderung am Beispiel eines vorschulischen Trainings der phonologischen Bewusstheit
Authors: Jäger Dana , Faust Verena , Blatter Kristine , Schöppe Doreen , Artelt Cordula , Schneider Wolfgang , Stanat Petra
Published: October 2012

Studien belegen, dass Trainings der phonologischen Bewusstheit den Schriftspracherwerb in der Erstsprache erleichtern. Weitgehend ungeklärt ist, inwiefern phonologische Fähigkeiten in der Zweitsprache bei Vorschulkindern effektiv trainiert werden können. Ziel der vorliegenden Studie ist die unmittelbare und langfristige Prüfung differenzieller Effekte eines Trainings der phonologischen Bewusstheit in Kombination mit einem Buchstabe-Laut-Training bei Vorschulkindern mit niedrigen Ausgangswerten in der phonologischen Bewusstheit (sog. „Risikokinder“). Zusätzlich wurde das kompensatorische Förderpotenzial des Trainings bei Kindern mit nichtdeutscher Herkunftssprache betrachtet. Um diese Fragestellungen zu beantworten, wurden gezielte Vergleiche durchgeführt. (1) Der Vergleich von Kindern mit anfangs niedrigen, durchschnittlichen und überdurchschnittlichen Ausprägungen in der phonologischen Bewusstheit zeigte, dass vor allem Risikokinder vom Training profitierten und sich langfristig an die beiden Nichtrisikogruppen annäherten. Nach Trainingsende zeigte der Vergleich trainierter Risikokinder mit der gesamten Kontrollgruppe, dass der anfängliche Rückstand der Risikokinder durch das Training kompensiert werden konnte. (2) Beim Vergleich des Trainingserfolgs von Kindern mit deutscher und nichtdeutscher Herkunftssprache spielte der Migrationshintergrund in der Risikogruppe keine Rolle. Die Betrachtung von Risikokindern mit und ohne Migrationshintergrund der Trainings- und Kontrollgruppe bestätigte die kompensatorische Wirkung des Trainingsprogramms.
Waterman Award nominations sought
Authors: Showstack Randy
Published: October 2012

The U.S. National Science Foundation (NSF) is accepting nominations for the 2013 Alan T. Waterman Award. The award, established in 1975 to commemorate NSF's first director, is the foundation's highest honor for promising, early‐career researchers. Nominees are accepted from all sources, from any field of science and engineering that NSF supports. In addition to receiving a medal, the award recipient will also receive a $1,000,000 grant over 5 years for scientific research or advanced study in any field of science or engineering supported by NSF. Completed nomination packages are due by 31 October. For more information, see http://www.nsf.gov/od/waterman/waterman.jsp.
Polarization and polar climate
Authors: Overland James , Schweitzer Peter
Published: October 2012

International Polar Year 2012 Conference: From Knowledge to Action;Montreal, Quebec, Canada, 22–27 April 2012 As a follow‐ up to the 2007–2008 International Polar Year (IPY), more than 3000 international participants came together in April 2012 at a conference entitled “From Knowledge to Action.” The conference addressed a broad scope of topics beyond academic science to include challenges of globalization, climate change, and social and economic issues. Participants included researchers and others with expertise in multiple fields: policy and decision making, law, industry, nongovernmental organizations, circumpolar communities, and indigenous peoples. The challenge of translating academic and other forms of knowledge into societal benefits dominated the event.
Summarizing the field of surrogate modeling research
Authors: Schultz Colin
Published: October 2012

As computer simulations of complex physical interactions grow, so do the time and expense required to operate them. Mirroring the development of such full‐scale models has been the related field of surrogate modeling or metamodeling. Surrogate models take a variety of forms, but their shared goal is to provide a numerical output similar to that of a fully complex physical model while minimizing the computational time and cost required to calculate the result. With an eye toward introducing those unfamiliar with the practices and pitfalls of surrogate modeling to the topic and with a focus on its applications to water resources research, Razavi et al. prepared a systematic review of the surrogate modeling literature.
Can aerosol loading explain the solar dimming over the Tibetan Plateau?
Authors: Yang Kun , Ding Baohong , Qin Jun , Tang Wenjun , Lu Ning , Lin Changgui
Published: October 2012

Solar radiation over the Tibetan Plateau has declined over recent three decades, whereas total cloud cover has a decreasing trend. A likely explanation to this paradox is the increase in aerosols over this clean region. However, this study shows that the radiation extinction due to aerosol loading is of one order lower in magnitude than the observed dimming, and the solar dimming is also seen in a satellite product that was produced without considering temporal variations of aerosols. Instead, the inter‐annual variability and decadal change in solar radiation is contrasting to that in water vapor amount and deep cloud cover (but not total cloud cover). Therefore, we suggest that the solar dimming over the Plateau is mainly due to the increase in water vapor amount and deep cloud cover, which in turn are related to the rapid warming and the increase in convective available potential energy.
Kinetic description of ionospheric outflows based on the exact form of Fokker‐Planck collision operator: Electrons
Authors: Khazanov George V. , Khabibrakhmanov Ildar K. , Glocer Alex
Published: October 2012

We present the results of a finite difference implementation of the kinetic Fokker‐Planck model with an exact form of the nonlinear collisional operator. The model is time dependent and three‐dimensional; one spatial dimension and two in velocity space. The spatial dimension is aligned with the local magnetic field, and the velocity space is defined by the magnitude of the velocity and the cosine of pitch angle. An important new feature of model, the concept of integration along the particle trajectories, is discussed in detail. Integration along the trajectories combined with the operator time splitting technique results in a solution scheme which accurately accounts for both the fast convection of the particles along the magnetic field lines and relatively slow collisional process. We present several tests of the model's performance and also discuss simulation results of the evolution of the plasma distribution for realistic conditions in Earth's plasmasphere under different scenarios.
Southern Weddell Sea shelf edge geomorphology: Implications for gully formation by the overflow of high‐salinity water
Authors: Gales J. A. , Larter R. D. , Mitchell N. C. , Hillenbrand C.‐D. , Østerhus S. , Shoosmith D. R.
Published: October 2012

Submarine gullies are the most common morphological features observed on Antarctic continental slopes. The processes forming these gullies, however, remain poorly constrained. In some areas, gully heads incise the continental shelf edge, and one hypothesis proposed is erosion by overflow of cold, dense water masses formed on the continental shelf. We examined new multibeam echo sounder bathymetric data from the Weddell Sea continental slope, the region that has the highest rate of cold, dense water overflow in Antarctica. Ice Shelf Water (ISW) cascades downslope with an average transport rate of 1.6 Sverdrups (Sv) in the southern Weddell Sea. Our new data show that within this region, ISW overflow does not deeply incise the shelf edge. The absence of gullies extending deeply into the glacial sediments at the shelf edge implies that cold, high salinity water overflow is unlikely to have caused the extensive shelf edge erosion observed on other parts of the Antarctic continental margin. Instead, the gullies observed in the southern Weddell Sea are relatively small and their characteristics indicative of small‐scale slides, probably resulting from the rapid accumulation and subsequent failure of proglacial sediment during glacial maxima.
Speech Planning Happens Before Speech Execution: Online Reaction Time Methods in the Study of Apraxia of Speech
Authors: Maas Edwin , Mailend Marja-Liisa
Published: October 2012

Purpose

The purpose of this article is to present an argument for the use of online reaction time (RT) methods to the study of apraxia of speech (AOS) and to review the existing small literature in this area and the contributions it has made to our fundamental understanding of speech planning (deficits) in AOS.

Method

Following a brief description of limitations of offline perceptual methods, we provide a narrative review of various types of RT paradigms from the (speech) motor programming and psycholinguistic literatures and their (thus far limited) application with AOS.

Conclusion

On the basis of the review of the literature, we conclude that with careful consideration of potential challenges and caveats, RT approaches hold great promise to advance our understanding of AOS, in particular with respect to the speech planning processes that generate the speech signal before initiation. A deeper understanding of the nature and time course of speech planning and its disruptions in AOS may enhance diagnosis and treatment for AOS.

Results

Only a handful of published studies on apraxia of speech have used reaction time methods. However, these studies have provided deeper insight into speech planning impairments in AOS based on a variety of experimental paradigms.
Apraxia of Speech: Concepts and Controversies
Authors: Ziegler Wolfram , Aichert Ingrid , Staiger Anja
Published: October 2012

Purpose

This article was written as an editorial to a collection of original articles on apraxia of speech (AOS) in which some of the more recent advancements in the understanding of this syndrome are discussed. It covers controversial issues concerning the theoretical foundations of AOS. Our approach was motivated by a change of perspective on motor speech that has taken place in neurobiology, neurolinguistics, phonology, and phonetics during the past few decades.

Method

The literature on AOS is reviewed from 3 different but overlapping perspectives—that is, a disconnection, a motor memory, and a fine motor skill perspective. Separate sections are devoted to the delimitations of AOS from oral facial apraxia, dysarthria, and phonological impairment.

Conclusions

We conclude that many of the still unresolved conceptual issues about AOS arise from an underspecification of existing models of spoken language production. We suggest that phonological and motor impairments of sound production should be studied by an integrated approach.
Horizontally propagating three-dimensional chemo-hydrodynamic patterns in the chlorite-tetrathionate reaction
Authors: Pópity-Tóth Éva , Horváth Dezső , Tóth Ágota
Published: October 2012

Planar reaction fronts resulting from the coupling of exothermic autocatalytic reactions and transport processes can be deformed by convection in the presence of gravity field. We have experimentally investigated how buoyancy affects the spatiotemporal pattern formation at various solution thicknesses in three-dimensional medium. In the chlorite–tetrathionate reaction, a stable structure propagating horizontally with constant velocity and geometry develops when appropriately thick solutions are studied. Both the horizontal and the vertical projections of the resulting three-dimensional structures are quantitatively characterized: the smooth leading edge of the front is independent of the solution thickness and the structured trailing edge ends in a center cusp with a constant angle.
Marangoni-driven convection around exothermic autocatalytic chemical fronts in free-surface solution layers
Authors: Rongy L. , Assemat P. , De Wit A.
Published: October 2012

Gradients of concentration and temperature across exothermic chemical fronts propagating in free-surface solution layers can initiate Marangoni-driven convection. We investigate here the dynamics arising from such a coupling between exothermic autocatalytic reactions, diffusion, and Marangoni-driven flows. To this end, we numerically integrate the incompressible Navier-Stokes equations coupled through the tangential stress balance to evolution equations for the concentration of the autocatalytic product and for the temperature. A solutal and a thermal Marangoni numbers measure the coupling between reaction-diffusion processes and surface-driven convection. In the case of an isothermal system, the asymptotic dynamics is characterized by a steady fluid vortex traveling at a constant speed with the front, deforming and accelerating it [L. Rongy and A. De Wit, J. Chem. Phys. 124, 164705 (2006)]. We analyze here the influence of the reaction exothermicity on the dynamics of the system in both cases of cooperative and competitive solutal and thermal effects. We show that exothermic fronts can exhibit new unsteady spatio-temporal dynamics when the solutal and thermal effects are antagonistic. The influence of the solutal and thermal Marangoni numbers, of the Lewis number (ratio of thermal diffusivity over molecular diffusivity), and of the height of the liquid layer on the spatio-temporal front evolution are investigated.
Abnormal interface state generation under positive bias stress in TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors
Authors: Lo Wen-Hung , Chang Ting-Chang , Tsai Jyun-Yu , Dai Chih-Hao , Chen Ching-En , Ho Szu-Han , Chen Hua-Mao , Cheng Osbert , Huang Cheng-Tung
Published: October 2012

This Letter studies positive bias stress-induced abnormal interface state on TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors. It can be found that the degradation is associated with electron trapping, resulting in Vth shift but without subthreshold slope degradation. However, charge pumping current (ICP) shows a significant degradation after stress. Accordingly, the impact ionization-induced Nit located HfO2/SiO2 is proposed to demonstrate the ICP degradation. The AC stress with several frequencies is used to evidence the occurrence of impact ionization. Further, the device with additional pre-existing Nit located SiO2/Si has insignificant degradation due to reduction in stress electric field.
Temperature dependent photon echoes of a GaN thin film
Authors: Schneck J. R. , Dimakis E. , Woodward J. , Erramilli S. , Moustakas T. D. , Ziegler L. D.
Published: October 2012

UV photon echoes from a ∼120 nm GaN thin film exhibit a biexponential decay attributed to the coherence loss of slowly and rapidly decaying excitons corresponding to excitons with different degrees of localization or trapping in this material. Both exciton populations are strongly inhomogeneously broadened. For one exciton type, T2 is ∼300 fs at 10 K and ≤25 fs at 300 K; for the other, T2 is pulse-width limited (≤25 fs) at all temperatures. At low temperatures, coherence decay predominantly results from impurity and defect site interactions. At higher temperatures, strong exciton-LO phonon coupling dominates dephasing.
A high resolution gamma-ray spectrometer based on superconducting microcalorimeters
Authors: Bennett D. A. , Horansky R. D. , Schmidt D. R. , Hoover A. S. , Winkler R. , Alpert B. K. , Beall J. A. , Doriese W. B. , Fowler J. W. , Fitzgerald C. P. , Hilton G. C. , Irwin K. D. , Kotsubo V. , Mates J. A. B. , O’Neil G. C. , Rabin M. W. , Reintsema C. D. , Schima F. J. , Swetz D. S. , Vale L. R. , Ullom J. N.
Published: October 2012

Improvements in superconductor device fabrication, detector hybridization techniques, and superconducting quantum interference device readout have made square-centimeter-sized arrays of gamma-ray microcalorimeters, based on transition-edge sensors (TESs), possible. At these collecting areas, gamma microcalorimeters can utilize their unprecedented energy resolution to perform spectroscopy in a number of applications that are limited by closely-spaced spectral peaks, for example, the nondestructive analysis of nuclear materials. We have built a 256 pixel spectrometer with an average full-width-at-half-maximum energy resolution of 53 eV at 97 keV, a useable dynamic range above 400 keV, and a collecting area of 5 cm2. We have demonstrated multiplexed readout of the full 256 pixel array with 236 of the pixels (91%) giving spectroscopic data. This is the largest multiplexed array of TES microcalorimeters to date. This paper will review the spectrometer, highlighting the instrument design, detector fabrication, readout, operation of the instrument, and data processing. Further, we describe the characterization and performance of the newest 256 pixel array.
Water nucleation: A comparison between some phenomenological theories and experiment
Authors: Bennett Thomas P. , Barrett Jonathan C.
Published: October 2012

The predictions of several homogeneous nucleation theories are compared with experimental results for water for a range of temperatures and vapor supersaturations, S. The theoretical models considered are: classical theory (including the 1/S correction factor), the Gibbs p-form, mean-field kinetic nucleation theory (MKNT), the extended modified liquid drop model-dynamical nucleation theory, and two forms of density functional theory, one without and one with a contribution due to association. The theoretical expressions for the logarithm of the nucleation rate are expanded in a series in powers of the logarithm of S. The residual dependence (once the classical dependence has been factored out) of the experimental results shows a stronger decrease with increasing temperature than all the theories except MKNT. The residual S-dependence of the experimental results decreases with increasing supersaturation whereas all the theories except the Gibbs p-form predict an increase. The first correction term to classical theory involves both the liquid compressibility and curvature correction to the surface tension (Tolman length) so the experimental results suggest that the Tolman length is zero (as assumed in the Gibbs p-form) or positive whereas the other theories predict a negative Tolman length. The effect of including a term proportional to ln(lnS) in the series expansion is also discussed.
NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses
Authors: Storek Michael , Böhmer Roland , Martin Steve W. , Larink Dirk , Eckert Hellmut
Published: October 2012

Alkali ion charge transport has been studied in a series of mixed glass former lithium borophosphate glasses of composition 0.33Li2O + 0.67[xB2O3 + (1 – x)P2O5]. The entire concentration range, 0.0 ≤ x ≤ 1.0, from pure glassy Li2P4O11 to pure glassy Li2B4O7 has been examined while keeping the molar fraction of Li2O constant. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li+ ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure.
Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material
Authors: Ramu Ashok T. , Mages Phillip , Zhang Chong , Imamura Jeffrey T. , Bowers John E.
Published: October 2012

The Seebeck coefficient of a typical thermoelectric material, silicon-doped InGaAs lattice-matched to InP, is measured over a temperature range from 300 K to 550 K. By depositing and patterning a thermometric reference bar of silicon-doped InP adjacent to a bar of the material under test, temperature differences are measured directly. This is in contrast to conventional two-thermocouple techniques that subtract two large temperatures to yield a small temperature difference, a procedure prone to errors. The proposed technique retains the simple instrumentation of two-thermocouple techniques while eliminating the critical dependence of the latter on good thermal contact. The repeatability of the proposed technique is demonstrated to be ±2.6% over three temperature sweeps, while the repeatability of two-thermocouple measurements is about ±5%. The improved repeatability is significant for reliable reporting of the ZT figure of merit, which is proportional to the square of the Seebeck coefficient. The accuracy of the proposed technique depends on the accuracy with which the high-temperature Seebeck coefficient of the reference material may be computed or measured. In this work, the Seebeck coefficient of the reference material, n+ InP, is computed by rigorous solution of the Boltzmann transport equation. The accuracy and repeatability of the proposed technique can be systematically improved by scaling, and the method is easily extensible to other material systems currently being investigated for high thermoelectric energy conversion efficiency.
Extraction of temperature dependent electrical resistivity and thermal conductivity from silicon microwires self-heated to melting temperature
Authors: Bakan Gokhan , Adnane Lhacene , Gokirmak Ali , Silva Helena
Published: October 2012

Temperature-dependent electrical resistivity, ρ(T), and thermal conductivity, k(T), of nanocrystalline silicon microwires self-heated to melt are extracted by matching simulated current-voltage (I-V) characteristics to experimental I-V characteristics. Electrical resistivity is extracted from highly doped p-type wires on silicon dioxide in which the heat losses are predominantly to the substrate and the self-heating depends mainly on ρ(T) of the wires. The extracted ρ(T) decreases from 11.8 mΩ cm at room-temperature to 5.2 mΩ cm at 1690 K, in reasonable agreement with the values measured up to ∼650 K. Electrical resistivity and thermal conductivity are extracted from suspended highly doped n-type silicon wires in which the heat losses are predominantly through the wires. In this case, measured ρ(T) (decreasing from 20.5 mΩ cm at room temperature to 12 mΩ cm at 620 K) is used to extract ρ(T) at higher temperatures (decreasing to 1 mΩ cm at 1690 K) and k(T) (decreasing from 30 W m−1 K−1 at room temperature to 20 W m−1 K−1 at 1690 K). The method is tested by using the extracted parameters to model wires with different dimensions. The experimental and simulated I-V curves for these wires show good agreement up to high voltage and temperature levels. This technique allows extraction of the electrical resistivity and thermal conductivity up to very high temperatures from self-heated microstructures.
Non-destructive magneto-strain analysis of YB2Cu3Oy superconducting magnets using neutron diffraction in the time-of-flight mode
Authors: Tomita M. , Muralidhar M. , Suzuki K. , Ishihara A. , Fukumoto Y. , Osamura K. , Machiya S. , Harjo S.
Published: October 2012

In general, neutron diffraction allows a non-destructive investigation of bulk samples. In this study, a magneto-strain analysis of the trapped field in YB2Cu3Oy “YBCO” superconducting bulks was carried out at 45 K using neutron diffraction time-of-flight (TOF) method. The TAKUMI TOF neutron diffractometer offers unique advantages, including accommodation of large objectives, control of the experimental set-up using a 4-axial goniometer (XYZθ), and a positional resolution of 0.01 mm allowing an accurate sample positioning. As a result, the lattice strain in the YB2Cu3Oy material could be estimated in both radial and hoop directions by estimating the difference of plane spacing with/without the trapped magnetic field. The results indicate that the samples with a low trapped field values have smaller magnetic strain than those with a high trapped field. Further, the strain in the hoop direction is higher than that in the radial direction. The present results indicate that neutron diffraction measurements are an effective method for evaluating the bulk residual strains in a non-destructive manner.
Annealing induced coherent evolutions of biaxial strain and antiferromagnetic-insulator phase in La0.625Ca0.375MnO3 films
Authors: Han Yunxin , Wu Wenbin , Jiang Guoshun , Zhu Changfei
Published: October 2012

La0.625Ca0.375MnO3 (LCMO) films with thicknesses between 7 and 54 nm were epitaxially grown on (LaAlO3)0.3(Sr2AlTaO6)0.35 (001) [LSAT (001)] substrates by using pulsed laser deposition. For this epitaxial system, antiferromagnetic-insulator (AFI) state can be controlled by changing the film thickness and annealing time with various epitaxial strain states, although this phenomenon is absent in the relatively thick films or bulk samples. The consistency between magnetization and resistivity data suggests all these interesting transport behaviors are attributed to the fluctuation of AFI volume fractions and their instability. Especially, there are huge low-field magnetoresistance over −54% (32 nm) at 0.1 T and enhanced magnetoresistance over a broad temperature range. Based on these above results, annealing induced coherent evolutions of biaxial strain and AFI phase in LCMO epitaxial films is a consequence of the strain-driven orbital ordered state, and this may make an approach for a possible application of strongly correlated electron devices.
Density functional theory for molecular multiphoton ionization in the perturbative regime
Authors: Toffoli Daniele , Decleva Piero
Published: October 2012

A general implementation of the lowest nonvanishing order perturbation theory for the calculation of molecular multiphoton ionization cross sections is proposed in the framework of density functional theory. Bound and scattering wave functions are expanded in a multicentric basis set and advantage is taken of the full molecular point group symmetry, thus enabling the application of the formalism to medium-size molecules. Multiphoton ionization cross sections and angular asymmetry parameters have been calculated for the two- and four-photon ionization of the \documentclass[12pt]{minimal}\begin{document}${\rm H}_2^+$\end{document}H2+ molecule, for linear and circular light polarizations. Both fixed and random orientations of the target molecule have been considered. To demonstrate the efficiency of the proposed methodology, the two-photon cross section and angular asymmetry parameters for the HOMO and HOMO-1 orbital ionization of benzene are also presented.
Improved charge-trapping properties of TiON/HfON dual charge storage layer by tapered band structure
Authors: Liu L. , Xu J. P. , Ji F. , Chen J. X. , Lai P. T.
Published: October 2012

A TiON/HfON dual charge storage layer (CSL) with tapered bandgap structure is proposed for metal-oxide–nitride-oxide–silicon-type memory by using the inter-diffusion of Ti and Hf atoms near the TiON/HfON interface to form an intermixing layer of HfxTiyON with varying Hf/Ti ratio in the dual CSL during post-deposition annealing, as confirmed by transmission electron microscopy. The memory capacitor with TiON/HfON as dual-CSL shows a large memory window of 5.0 V at ±12 V for 100 μs, improved cycling endurance with little degradation after 105 cycles and good data retention with an extrapolated 10-yr window of 4.6 V at room temperature. These are highly associated with the tapered bandgap structure and appropriate trap distribution in the dual CSL. Therefore, the TiON/HfON dual-CSL structure provides a very promising solution for future charge-trapping memory applications.
Generation of large spin currents in graphene using adiabatic quantum pumping
Authors: Zhang Qingtian , Liu Jun-Feng , Lin Zijing , Chan K. S.
Published: October 2012

We study adiabatic quantum pumping of Dirac fermions in a monolayer graphene in the large pumping amplitude regime in order to study how to generate a large spin polarized current. Spin current is generated by applying two periodic oscillating gate voltages to a monolayer graphene with exchange splitting induced by ferromagnetic proximity. We find that pumped charge and spin currents are sensitive functions of the Fermi energy and pure spin current and spin current with different degrees of polarization and large magnitudes are obtained in our scheme. We also study the effects of parameters of the system, such as the barrier separation and the exchange splitting, on the pumped currents. The spin current generated by this method can be as high as 80-100 nA. This shows the method can be used in the study of spin physics in graphene and the realization of graphene spintronic devices.
Information processing with a single multifunctional nanofluidic diode
Authors: Ramirez Patricio , Ali Mubarak , Ensinger Wolfgang , Mafe Salvador
Published: October 2012

We show that a multifunctional nanofluidic diode, based on a single pH-sensitive polymeric pore, can be used for different information processing tasks. This fact should permit a significant simplification of the logic circuitry in physico-chemical processors. The inputs are the pH values in the external solutions and the applied potential difference (voltage). The output is the electrical pore conductance. As a proof of concept, different logic and arithmetic computational functions are demonstrated.
Gap independent coupling into parallel plate terahertz waveguides using cylindrical horn antennas
Authors: Shutler Alisha J. , Grischkowsky D.
Published: October 2012

We demonstrate how replacing the silicon lenses, traditionally used to couple radiation into parallel plate waveguides, with integrated cylinder-based horn couplers not only greatly improves ease of use and fabrication but also features gap independent coupling. The couplers, created from chords of a cylinder, give reflection free transmission through the waveguide that is on the order of the quasi-optical approach. The gap independent coupling is demonstrated through a precise measurement of the metal conductivity of the THz skin depth layer.
Capacitance spectroscopy study of deep levels in Cl-implanted 4H-SiC
Authors: Alfieri G. , Kimoto T.
Published: October 2012

We report on a deep level transient spectroscopy study of Cl-implanted n- and p-type 4H-SiC epilayers. Samples were electrically characterized after each step of an isochronal annealing series, between room temperature and 1800 ∘C, and twelve deep traps were detected. Of these, seven traps were found in n-type material, ranging from 0.15 to 1.6 eV below the conduction band minimum (EC), and five were detected in p-type material, located between 0.5 and 1.7 eV above the valence band maximum (EV). Besides the presence of the well known Z1/2 and EH6/7 levels in n-type 4H-SiC and of the D-center in p-type samples, we found that Cl implantation gives rise to three new traps in n-type material at EC−0.37 eV, EC−1.06 eV, and EC−1.3 eV and one new level in p-type at EV+0.97  eV. These traps are persistent after annealing at 1800 ∘C, and no data were found in the previous experimental studies reported in the literature. The possible involvement of Cl in the microscopic structure of these defects is discussed based on a depth profiling analysis of their concentration.
Full dimensional quantum-mechanical simulations for the vibronic dynamics of difluorobenzene radical cation isomers using the multilayer multiconfiguration time-dependent Hartree method
Authors: Meng Qingyong , Faraji Shirin , Vendrell Oriol , Meyer Hans-Dieter
Published: October 2012

Full dimensional multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) calculations of the dynamics of the three difluorobenzene cationic isomers in five lowest-lying doublet electronic states using the ab initio multistate multimode vibronic coupling Hamiltonian (MMVCH) model are carried out using the Heidelberg MCTDH package. The same dynamical problems, but treated with the MCTDH scheme and using a reduced dimensional ab initio MMVCH model, have been previously reported [S. Faraji, H.-D. Meyer, and H. Köppel, “Multistate vibronic interactions in difluorobenzene radical cations. II Quantum dynamical simulations,” J. Chem. Phys. 129, 074311 (2008)10.1063/1.2958918]. For easy comparison with the reduced dimensional results, 11D or 10D ML-MCTDH calculations are also performed. Extensive ML-MCTDH test calculations are performed to find appropriate ML-MCTDH wavefunction structures (ML-trees), and the convergence of the ML-MCTDH calculations are carefully checked to ensure accurate results. Based on the appropriate ML-trees, the photoelectron (PE) spectrum and the mass analyzed threshold ionization (MATI) spectrum are simulated, analyzed, and compared with corresponding experimental spectra. Because of its efficient simulation capability for large systems, ML-MCTDH calculations save a considerable amount of central processing unit (CPU)-time, even when a reduced dimensional MMVCH is used, i.e., the same reduced model as in the corresponding MCTDH calculations. Simulations of the experimental PE spectra by full dimensional ML-MCTDH calculations reproduced main peaks, which originate from different electronic states. The agreement is improved as compared to the reduced dimensionality calculations. Unfortunately, the experimental PE spectra are not very well resolved. Therefore, we compare our calculations additionally with highly resolved MATI spectra, which, however, are only available for the \documentclass[12pt]{minimal}\begin{document}$\tilde{X}$\end{document}X̃ state. Based on a series of ML-MCTDH simulations with longer propagation time for \documentclass[12pt]{minimal}\begin{document}$\tilde{X}$\end{document}X̃, a number of vibrational modes, including fundamentals, their combinations, and overtones are simulated and assigned by comparing with the experimental assignments and the ab initio frequencies. Excellent correlation between the experimental and full dimensional ML-MCTDH results show that ML-MCTDH is accurate and very efficient and that the ab initio MMVCH model is very suitable for ML-MCTDH calculations.
InGaP-based InGaAs quantum dot solar cells with GaAs spacer layer fabricated using solid-source molecular beam epitaxy
Authors: Sugaya T. , Takeda A. , Oshima R. , Matsubara K. , Niki S. , Okano Y.
Published: October 2012

We report InGaP-based multistacked InGaAs quantum dot (QD) solar cells with GaAs spacer layers. We obtain a highly stacked and well-aligned InGaAs QD structure with GaAs spacer layers in an InGaP matrix grown by solid-source molecular beam epitaxy. The photoluminescence intensity of the InGaAs QDs in the InGaP matrix increases as the number of QD layers increases, which indicates the growth of a high-quality InGaP-based multistacked InGaAs QD structure. The short-circuit current density and the conversion efficiency of the InGaP-based QD solar cells increase as the number of InGaAs QD layers increases.
High electron mobility through the edge states in random networks of c-axis oriented wedge-shaped GaN nanowalls grown by molecular beam epitaxy
Authors: Bhasker H. P. , Dhar S. , Sain A. , Kesaria Manoj , Shivaprasad S. M.
Published: October 2012

Transport and optical properties of random networks of c-axis oriented wedge-shaped GaN nanowalls grown spontaneously on c-plane sapphire substrates through molecular beam epitaxy are investigated. Our study suggests a one dimensional confinement of carriers at the top edges of these connected nanowalls, which results in a blue shift of the band edge luminescence, a reduction of the exciton-phonon coupling, and an enhancement of the exciton binding energy. Not only that, the yellow luminescence in these samples is found to be completely suppressed even at room temperature. All these changes are highly desirable for the enhancement of the luminescence efficiency of the material. More interestingly, the electron mobility through the network is found to be significantly higher than that is typically observed for GaN epitaxial films. This dramatic improvement is attributed to the transport of electrons through the edge states formed at the top edges of the nanowalls.
Manganese induced modifications in yttria stabilized zirconia
Authors: Mahapatra Manoj K. , Singh Prabhakar , Misture Scott T.
Published: October 2012

We have investigated the role of manganese oxide on the crystallographic and morphological modifications of cubic 8 mol. % yttria stabilized zirconia (YSZ). X-ray diffraction studies indicate that manganese dissolution leads to partial transformation of cubic YSZ into the tetragonal polymorph along with contraction of the unit cell. Evolution of an undulated surface with 2–15 nm roughness has been observed using electron and atomic force microscopies.