bluuebunny/crossref_metadata_2025 huggingface dataset:
Observational learning in the music masterclass
Authors: Haddon Elizabeth
Published: August 2013

This article contributes to research on music masterclasses through examining learning through observation. It investigates how students are learning as observers in this context; whether and how they will transfer their masterclass learning to their own instrumental/vocal development, and whether they have discussed learning through observation. Data were gathered from higher education students observing two masterclasses. Their responses indicate observation of technical, musical, performative and pedagogic elements. However, they also suggest limited discussion of observation and of the processes involved in implementing observational learning within their own work. The findings suggest that there is scope for enhanced learning in the masterclass, including developing perception through facilitated engagement with systematic observation and consideration of processes of transferable learning. These may have positive implications for extending learning in other contexts.
Questioning photostasis
Authors: CUNEA ALEXANDER , BEGUM RANA , REINISCH DIETER , JEFFERY GLEN
Published: August 2013

Photostasis is a phenomenon where the photoreceptor outer segment (OS) length and its rhodopsin content vary depending on environmental lighting. When light is reduced for extended periods, it is argued that OS lengthen and its rhodopsin concentration rises to increase photon capture in darker environment. Increases in OS length may occur because the retinal pigment epithelium (RPE) cells reduce OS consumption in prolonged darkness. But sample sizes in assessing changes in OS length have been small, and results highly varied with no statistical analysis ever offered. Further, animals used were often albinos, which have abnormal RPE cells. Here we keep pigmented and albino mice for 21 days in darkness and compare OS length with those in a normal 12:12 light/dark environment. We measured approximately 1300 OS but found no statistically significant difference in their lengths between light and dark groups in either pigmentation phenotype, although there was a small trend in the data favoring OS extension in the dark. Given that earlier studies were undertaken on limited samples with no statistical analysis, our data pose serious questions for the notion of mammalian photostasis in terms of significant OS plasticity.
Steady streaming in a channel with permeable walls
Authors: ILIN KONSTANTIN
Published: August 2013

We study steady streaming in a channel between two parallel permeable walls induced by oscillating (in time) injection/suction of a viscous fluid at the walls. We obtain an asymptotic expansion of the solution of the Navier–Stokes equations in the limit when the amplitude of normal displacements of fluid particles near the walls is much smaller than both the width of the channel and the thickness of the Stokes layer. It is shown that the steady part of the flow in this problem is much stronger than the steady flow produced by vibrations of impermeable boundaries. Another interesting feature of this problem is that the direction of the steady flow is opposite to what one would expect if the flow was produced by vibrations of impermeable walls.
The Effect of Heat Waves on Ambulance Attendances in Brisbane, Australia
Authors: Turner Lyle R. , Connell Des , Tong Shilu
Published: August 2013

Introduction

Heat waves have significant impacts on mortality and morbidity. However, little is known regarding effects on pre-admission health outcomes such as ambulance attendances, particularly in subtropical regions.

Problem

This study investigated both main temperature effects and the added effects of heat waves on ambulance attendances in Brisbane, a subtropical city in Australia.

Methods

Daily data relating to 783,935 ambulance attendances, along with data on meteorological variables and air pollutants, were collected for the period 2000-2007. Ambient temperature (main) effects were assessed using a distributed lag nonlinear approach that accounted for delayed effects of temperature, while added heat wave effects were incorporated separately using a local heat wave definition. Effect estimates were obtained for total, cardiovascular and respiratory attendances, and different age groups.

Results

Main effects of temperature were found for total attendances, which increased by 50.6% (95% CI, 32.3%-71.4%) for a 9.5°C increase above a reference temperature of 29°C. An added heat wave effect on total attendances was observed (18.8%; 95% CI, 6.5%-32.5%). Significant effects were found for both respiratory and cardiovascular attendances, particularly for those aged 65 and above.

Conclusion

Ambulance attendances can be significantly impacted by sustained periods of high temperatures, and are a valid source of early detection of the effects of extreme temperatures on the population. The planning of ambulance services may need to be adapted as a consequence of increasing numbers of heat waves in the future. Ambulance attendance data also should be utilized in the development of heat warning systems and climate change adaptation strategies.

TurnerLR,ConnellD,TongS.The effect of heat waves on ambulance attendances in Brisbane, Australia.Prehosp Disaster Med.2013;28(5):1-6.
Dark-Field Imaging of Thin Specimens with a Forescatter Electron Detector at Low Accelerating Voltage
Authors: Brodusch Nicolas , Demers Hendrix , Gauvin Raynald
Published: August 2013

A forescatter electron detector (FSED) was used to acquire dark-field micrographs (DF-FSED) on thin specimens with a scanning electron microscope. The collection angles were adjusted with the detector distance from the beam axis, which is similar to the camera length of the scanning transmission electron microscope annular DF detectors. The DF-FSED imaging resolution was calculated with SMART-J on an aluminum alloy and carbon nanotubes (CNTs) decorated with platinum nanoparticles. The resolution was three to six times worse than with bright-field imaging. Measurements of nanometer-size objects showed a similar feature size in DF-FSED imaging despite a signal-to-noise ratio 12 times smaller. Monte Carlo simulations were used to predict the variation of the contrast of a CNT/Fe/Pt system as a function of the collection angles. It was constant for very high collection angles (>450 mrad) and confirmed experimentally. The reverse contrast between carbon black particles and the smallest titanium dioxide (TiO2) nanoparticles was predicted by Monte Carlo simulations and observed in the DF-FSED micrograph of a battery electrode coating. However, segmentation of the micrograph was not able to isolate the TiO2 nanoparticle phase because of the close contrast of small TiO2 nanoparticles compared to the C black particles.
Long-Term Ultrastructural Indices of Lead Intoxication in Pulmonary Tissue of the Rat
Authors: Kaczyńska Katarzyna , Walski Michał , Szereda-Przestaszewska Małgorzata
Published: August 2013

In the present research long-term pulmonary toxicity of lead was investigated in rats treated by intraperitoneal administration of lead acetate for three consecutive days (25 mg/kg per day). Five weeks after treatment average lead content in the whole blood was 0.41 μg/dL ± 0.05, in the lung homogenates it measured 3.35 μg/g ± 0.54, as compared to the control values of 0.13 ± 0.07 μg/dL and 1.03 μg/g ± 0.59, respectively. X-ray microanalysis of lung specimens displayed lead localized mainly within type II pneumocytes and macrophages. At the ultrastructural level the effects of lead toxicity were found in lung capillaries, interstitium, epithelial cells, and alveolar lining. Alveolar septa showed intense fibrosis, consisting of collagen, elastin, and fibroblasts. Thinned alveolar septa had emphysematous tissue with some revealing signs of angiogenesis. Type II pneumocytes contained lamellar bodies with features of laminar destruction. Fragments of the surfactant layer were often detached from the alveolar epithelium. These findings indicate that 5 weeks after exposure, lead provokes reconstruction of the alveolar septa including fibrosis and emphysematous changes in the lung tissue.
The Relationship between the Child Support Grant and Teenage Fertility in Post-Apartheid South Africa
Authors: Udjo Eric O.
Published: August 2013

Governments often provide some form of social assistance to vulnerable groups. The right to social security is enshrined in the South African Constitution and the Social Assistance Act 13 of 2004. The country provides for a child support grant to single parents or caregivers who are low-income earners. The impact of the child support grant on teenage pregnancy in South Africa has aroused interest in the last couple of years, sparking debate that it may be encouraging teenage pregnancy. However, empirical evidence has been produced to confirm this relationship. This study examines the relationship between receiving the child support grant and being pregnant with another child in two national data sets using logistic regression analysis and empirical data. The results indicate that teenagers who receive the child support grant are significantly less likely to be pregnant with another child compared with teenagers who do not receive the child support grant.
Elinor Ostrom and the robust political economy of common-pool resources
Authors: PENNINGTON MARK
Published: August 2013

This paper situates Elinor Ostrom's work on common-pool resource management in the tradition of ‘robust political economy’. Ostrom's analysis of bottom-up governance institutions is shown to recognise that such arrangements though imperfect are better placed to cope with bounded rationality and incentive compatibility problems in the management of smaller- and medium-scale common-pool resources. While Ostrom's work provides an analytical framework to explain the success of these arrangements, however, the paper argues that it lacks a robust account of when, if ever, top-down governance arrangements are to be preferred.
AXIOMATIC TRUTH, SYNTAX AND METATHEORETIC REASONING
Authors: LEIGH GRAHAM E. , NICOLAI CARLO
Published: August 2013

Following recent developments in the literature on axiomatic theories of truth, we investigate an alternative to the widespread habit of formalizing the syntax of the object-language into the object-language itself. We first argue for the proposed revision, elaborating philosophical evidences in favor of it. Secondly, we present a general framework for axiomatic theories of truth with ‘disentangled’ theories of syntax. Different choices of the object theory O will be considered. Moreover, some strengthenings of these theories will be introduced: we will consider extending the theories by the addition of coding axioms or by extending the schemas of O, if present, to the entire vocabulary of our theory of truth. Finally, we touch on the philosophical consequences that the theories described can have on the debate about the metaphysical status of the truth predicate and on the formalization of our informal metatheoretic reasoning.
Effect of spectrally aware tunable front ends on wireless communication systems
Authors: Jeong Seongheon , Chappell William J.
Published: August 2013

In this paper, the benefits of adaptive preselect filtering are investigated by analyzing mote-to-mote throughput in the presence of interference. In a city-wide deployment of a sensor network, of the 150 wireless sensor nodes deployed in our urban test system, five nodes were electrically “lost”. Surprisingly, the limiting factor was not the signal strength, but the neighboring cell towers that caused nearby interference. Therefore, we explored the effect of an adaptive front end to mitigate these nearby interferers. The sensor motes operated at a fixed band, the unlicenced band of 902 to 928 MHz, and did not have the frequency adaptability of future cognitive radios. However, the effect was demonstrative of the potential benefits of adaptive preselect filtering. The measured result shows substantial improvements over the fixed band system by even slight tuning of the bandwidth and/or the center frequency of the preselect filter. Experimentally and numerically, we show that both tuning in the filter bandwidth and/or center frequency can significantly improve the packet reception rate. Guidelines for achieving an optimized filtering technique are given to provide a broad understanding of how the adaptable preselect filtering can be utilized.
Familial Resemblance for Serum Metabolite Concentrations
Authors: Draisma Harmen H. M. , Beekman Marian , Pool René , van Ommen Gert-Jan B. , Vaarhorst Anika A. M. , de Craen Anton J. M. , Willemsen Gonneke , Slagboom P. Eline , Boomsma Dorret I.
Published: August 2013

Metabolomics is the comprehensive study of metabolites, which are the substrates, intermediate, and end products of cellular metabolism. The heritability of the concentrations of circulating metabolites bears relevance for evaluating their suitability as biomarkers for disease. We report aspects of familial resemblance for the concentrations in human serum of more than 100 metabolites, measured using a targeted metabolomics platform. Age- and sex-corrected monozygotic twin correlations, midparent–offspring regression coefficients, and spouse correlations in subjects from two independent cohorts (Netherlands Twin Register and Leiden Longevity Study) were estimated for each metabolite. In the Netherlands Twin Register subjects, who were largely fasting, we found significant monozygotic twin correlations for 121 out of 123 metabolites. Heritability was confirmed by midparent–offspring regression. For most detected metabolites, the correlations between spouses were considerably lower than those between twins, indicating a contribution of genetic effects to familial resemblance. Remarkably high heritability was observed for free carnitine (monozygotic twin correlation 0.66), for the amino acids serine (monozygotic twin correlation 0.77) and threonine (monozygotic twin correlation 0.64), and for phosphatidylcholine acyl-alkyl C40:3 (monozygotic twin correlation 0.77). For octenoylcarnitine, a consistent point estimate of approximately 0.50 was found for the spouse correlations in the two cohorts as well as for the monozygotic twin correlation, suggesting that familiality for this metabolite is explained by shared environment. We conclude that for the majority of metabolites targeted by the used metabolomics platform, the familial resemblance of serum concentrations is largely genetic. Our results contribute to the knowledge of the heritability of fasting serum metabolite concentrations, which is relevant for biomarker research.
PET Imaging of Serotoninergic Neurotransmission with [11C]DASB and [18F]altanserin after Focal Cerebral Ischemia in Rats
Authors: Martín Abraham , Szczupak Boguslaw , Gómez-Vallejo Vanessa , Plaza Sandra , Padró Daniel , Cano Ainhoa , Llop Jordi
Published: August 2013

The use of selective serotonin reuptake inhibitors has shown functional improvement after stroke. Despite this, the role of serotoninergic neurotransmission after cerebral ischemia evolution and its involvement in functional recovery processes are still largely unknown. For this purpose, we performed in parallel in vivo magnetic resonance imaging and positron emission tomography (PET) with [11C]DASB and [18F]altanserin at 1, 3, 7, 14, 21, and 28 days after middle cerebral artery occlusion (MCAO) in rats. In the ischemic territory, PET with [11C]DASB and [18F]altanserin showed a dramatic decline in serotonin transporter (SERT) and 5-HT2A binding potential in the cortex and striatum after cerebral ischemia. Interestingly, a slight increase in [11C]DASB binding was observed from days 7 to 21 followed by the uppermost binding at day 28 in the ipsilateral midbrain. In contrast, no changes were observed in the contralateral hemisphere by using both radiotracers. Likewise, both functional and behavior testing showed major impaired outcome at day 1 after ischemia onset followed by a recovery of the sensorimotor function and dexterity from day 21 to day 28 after cerebral ischemia. Taken together, these results might evidence that SERT changes in the midbrain could have a key role in the functional recovery process after cerebral ischemia.
Activating the Microscale Edge Effect in a Hierarchical Surface for Frosting Suppression and Defrosting Promotion
Authors: Chen Xuemei , Ma Ruiyuan , Zhou Hongbo , Zhou Xiaofeng , Che Lufeng , Yao Shuhuai , Wang Zuankai
Published: August 2013

Despite extensive progress, current icephobic materials are limited by the breakdown of their icephobicity in the condensation frosting environment. In particular, the frost formation over the entire surface is inevitable as a result of undesired inter-droplet freezing wave propagation initiated by the sample edges. Moreover, the frost formation directly results in an increased frost adhesion, posing severe challenges for the subsequent defrosting process. Here, we report a hierarchical surface which allows for interdroplet freezing wave propagation suppression and efficient frost removal. The enhanced performances are mainly owing to the activation of the microscale edge effect in the hierarchical surface, which increases the energy barrier for ice bridging as well as engendering the liquid lubrication during the defrosting process. We believe the concept of harnessing the surface morphology to achieve superior performances in two opposite phase transition processes might shed new light on the development of novel materials for various applications.
Towards real-time image deconvolution: application to confocal and STED microscopy
Authors: Zanella R. , Zanghirati G. , Cavicchioli R. , Zanni L. , Boccacci P. , Bertero M. , Vicidomini G.
Published: August 2013

Although deconvolution can improve the quality of any type of microscope, the high computational time required has so far limited its massive spreading. Here we demonstrate the ability of the scaled-gradient-projection (SGP) method to provide accelerated versions of the most used algorithms in microscopy. To achieve further increases in efficiency, we also consider implementations on graphic processing units (GPUs). We test the proposed algorithms both on synthetic and real data of confocal and STED microscopy. Combining the SGP method with the GPU implementation we achieve a speed-up factor from about a factor 25 to 690 (with respect the conventional algorithm). The excellent results obtained on STED microscopy images demonstrate the synergy between super-resolution techniques and image-deconvolution. Further, the real-time processing allows conserving one of the most important property of STED microscopy, i.e the ability to provide fast sub-diffraction resolution recordings.
Language independent on–off voice over IP source model with lognormal transitions
Authors: Shaikh Ahmed D. , Blow Keith J. , Eberhard Marc A. , Fowler Scott A.
Published: August 2013

The recent explosive growth of voice over IP (VoIP) solutions calls for accurate modelling of VoIP traffic. This study presents measurements of ON and OFF periods of VoIP activity from a significantly large database of VoIP call recordings consisting of native speakers speaking in some of the world's most widely spoken languages. The impact of the languages and the varying dynamics of caller interaction on the ON and OFF period statistics are assessed. It is observed that speaker interactions dominate over language dependence which makes monologue‐based data unreliable for traffic modelling. The authors derive a semi‐Markov model which accurately reproduces the statistics of composite dialogue measurements.
Adaptive‐weighted multibit‐flipping decoding of low‐density parity‐check codes based on ordered statistics
Authors: Chen Tso‐Cho
Published: August 2013

An adaptive‐weighted multibit‐flipping decoding algorithm, which flips multiple bits in each iteration, is proposed for low‐density parity‐check codes. The multibit‐flipping criterion is devised based on the least reliable positions and ordered statistics, in which the flipping threshold is dynamically adapted during the decoding process. The proposed decoder converges faster and provides better performances than the conventional weighted bit‐flipping and multibit‐flipping decoders. Simulation results demonstrate that the proposed algorithm achieves a good tradeoff between performance and complexity.
Guaranteed cost sampled‐data fuzzy control for non‐linear systems: a continuous‐time Lyapunov approach
Authors: Koo Geun Bum , Park Jin Bae , Joo Young Hoon
Published: August 2013

This study presents a stability condition for a guaranteed cost sampled‐data fuzzy control problem of non‐linear systems. A Takagi–Sugeno (T–S) fuzzy model is adopted for the non‐linear system and the sampled‐data fuzzy controller is designed for a T–S fuzzy system. To develop the guaranteed cost control, a new stability condition of the closed‐loop system is guaranteed in the continuous‐time Lyapunov sense, and its sufficient conditions are formulated in terms of linear matrix inequalities. Based on the stability condition, the guaranteed cost control is considered and minimised for the closed‐loop system from the continuous‐time cost function. Finally, numerical examples are provided to verify the effectiveness of the proposed technique.
Analysis of polarisation conversion in cascaded bent photonic crystal fibre
Authors: Almewafy Basel H. , Hameed Mohamed Farhat O. , Areed Nihal F.F. , Heikal Ahmed M. , Obayya Salah S.A.
Published: August 2013

A rigorous analysis of polarisation conversion in a novel design of cascaded bent silica photonic crystal fibre is proposed using full vectorial finite difference method as well as full vectorial finite difference beam propagation method. The influence of different structural geometrical parameters on the polarisation rotator performance is investigated. The numerical results reveal that by a careful adjustment of the structural geometrical parameters and bending radius, nearly a 100% polarisation conversion ratio with nine sections only and low bending losses can be achieved.
Non‐uniform‐level crossing sampling for efficient sensing of temporally sparse signals
Authors: Alasti Hadi
Published: August 2013

This study investigates the performance of level‐crossing sampling (LCS) for efficient sensing of the temporally sparse random signals assuming that the sampling levels can be chosen arbitrarily. In particular, the authors investigate a non‐uniform LCS for sensing temporally sparse signals with sampling levels that are optimised to minimise the reconstruction error based on prior knowledge of signal's probability density function (pdf). Performance results showing the tradeoff between reconstruction error and average number of samples are presented. To define the sampling levels independent from the pdf of the signal, a tractable scheme is proposed. The performance and sampling efficiency of LCS for three schemes of defining the sampling levels when the signal range is known are evaluated.
Improvement of solid oxide fuel cell by imprinted micropatterns on electrolyte
Authors: Xu Yang , Tsumori Fujio , Osada Toshiko , Miura Hideshi
Published: August 2013

A study is presented of an improved interfacial structure between the electrode and electrolyte of a solid oxide fuel cell. An imprint process, which is considered as a powerful tool to transcribe nano to micropatterns on materials, was employed to imprint fine patterns onto a ceramic sheet of electrolyte. In the presented work, a sheet of ceramic compound material was prepared, and micropatterns were imprinted on its surface. After debinding and sintering, a dense ceramic sheet with fine micropatterns was obtained. To investigate the effect of micropatterns on the overall performance of a fuel cell, three kinds of electrolyte sheets with different surface patterns were employed for this technique. After applying anode and cathode layers, the three fuel cell samples were assembled to test the cell performance. The result was that the finer pattern caused better performance in the three samples by exhibiting the highest overall voltage and power density, and the effective factors of patterns on ion conductivity were discussed as well. Based on the investigation, some further improved three‐dimensional microstructures were proposed and fabricated by the method of micro powder imprinting (μPI).
The beta-Wishart ensemble
Authors: Dubbs Alexander , Edelman Alan , Koev Plamen , Venkataramana Praveen
Published: August 2013

We introduce a “broken-arrow” matrix model for the β-Wishart ensemble, which improves on the traditional bidiagonal model by generalizing to non-identity covariance parameters. We prove that its joint eigenvalue density involves the correct hypergeometric function of two matrix arguments, and a continuous parameter β > 0. If we choose β = 1, 2, 4, we recover the classical Wishart ensembles of general covariance over the reals, complexes, and quaternions. Jack polynomials are often defined as the eigenfunctions of the Laplace-Beltrami operator. We prove that Jack polynomials are in addition eigenfunctions of an integral operator defined as an average over a β-dependent measure on the sphere. When combined with an identity due to Stanley, we derive a definition of Jack polynomials. An efficient numerical algorithm is also presented for simulations. The algorithm makes use of secular equation software for broken arrow matrices currently unavailable in the popular technical computing languages. The simulations are matched against the cdfs for the extreme eigenvalues. The techniques here suggest that arrow and broken arrow matrices can play an important role in theoretical and computational random matrix theory including the study of corners processes. We provide a number of simulations illustrating the extreme eigenvalue distributions that are likely to be useful for applications. We also compare the n → ∞ answer for all β with the free-probability prediction.
Ground state energy of mean field model of interacting bosons in Bernoulli potential
Authors: Bishop M. , Wehr J.
Published: August 2013

This paper explores the ground state energy of a system of interacting “soft core” bosons in a random Bernoulli potential in the Gross-Pitaevskii mean-field approximation. First, we prove a condition for a state to delocalize due to interaction. Using this condition, asymptotics for ground state energy per particle are derived in the large system limit for small values of the coupling constant. Our methods directly describe the shape of the ground state in a given realization of the random potential.
Density equalisation in supercooled high- and low-density water mixtures
Authors: English Niall J. , Kusalik Peter G. , Tse John S.
Published: August 2013

The temporal evolution of two model high-density/low-density (HDL/LDL) interfaces was examined from molecular dynamics (MD) calculations at temperatures close to the predicted second critical point of water for three water models. In all cases, interfacial density equalisation occurred rapidly showing no preference for inhomogenous distribution. A uniform density (of ca. 0.99–1.067 g/cm3, depending on the potential) was always observed at the interface, indicating the free energy of water in low- and high-density forms is metastable, and that LDL and HDL should not coexist as independent entities at thermodynamic equilibrium. It is reckoned that previous MD studies supporting the “two-liquid” model have an explicit, if inappropriate, assumption of mechanical equilibrium between the two phases. The present result challenges the notion that a second critical point exists, and that LDL/HDL mixtures could be even kinetically metastable.
Preheat of radiative shock in double-shell ignition targets
Authors: Li J. W. , Pei W. B. , He X. T. , Li J. H. , Zheng W. D. , Zhu S. P. , Kang W.
Published: August 2013

For the double-shell ignition target, the nonuniform preheat of the inner shell by high-energy x rays, especially the M-band line radiation and L-shell radiation from the Au hohlraum, aggravates the hydrodynamic instability that causes shell disruption. In this paper, for the first time, we propose another preheating mechanism due to the radiative shock formed in the CH foam, and also confirm and validate such preheat of radiative shock by numerical results. We also give an estimate of the improved double-shell in which the CH foam is replaced by the metallic foam to mitigate the hydrodynamic instabilities, and find that the radiative shock formed in the metallic foam produces a much stronger radiation field to preheat the inner shell, which plays a role in better controlling the instabilities. In double-shells, the preheat of radiative shock, as a potential effect on the instabilities, should be seriously realized and underlined.
Dense strongly coupled plasma in double laser pulse ablation of lithium: Experiment and simulation
Authors: Kumar Ajai , Sivakumaran V. , J. Ashwin , Ganesh R. , Joshi H. C.
Published: August 2013

In a simple method of low power nano-second double pulsed laser ablation experiment in collinear geometry, formation of high density strongly coupled plasma is demonstrated. Using time-resolved measurements of the Stark broadened line width and line intensity ratio of the emission lines, the density and temperature of the plasma were estimated respectively. In this experiment, it is shown that ions are strongly coupled (ion-ion coupling parameter comes out to be >4). For comparison, both single and double pulsed laser ablations are presented. For the estimated experimental plasma parameters, first principle Langevin dynamics simulation corroborates the existence of a strongly coupled regime.
Design and fabrication of eight zone vertical dynamic gradient freeze system for organic single crystal growth
Authors: Prabhakaran SP. , Babu R. Ramesh , Ramamurthi K.
Published: August 2013

Design and construction of the vertical dynamic gradient freeze (VDGF) system operating in the temperature range from 50 °C to 500 °C for growing organic single crystals are described. The design of VDGF system consists of furnace, control system, translation assembly, and image capturing device. Furnace has been constructed with eight zones controlled independently by a dynamic temperature control system for achieving desired thermal environment and multiple temperature gradients, which are essential for the growth of organic single crystals. The transparent furnace enables direct observation to record and monitor the solid-liquid interface and growth of crystals through charge coupled device based video camera. The system is fully computerized hence it is possible to retrieve the complete growth and furnace history. In order to investigate the functioning of the constructed VDGF system for the growth of organic single crystals, a well known organic nonlinear optical single crystal of benzimidazole was grown. The crystalline quality and the optical transmittance of the grown crystal were studied.
Recurrence relations of the multi-indexed orthogonal polynomials
Authors: Odake Satoru
Published: August 2013

Ordinary orthogonal polynomials are uniquely characterized by the three term recurrence relations up to an overall multiplicative constant. We show that the newly discovered M-indexed orthogonal polynomials satisfy 3+2M term recurrence relations with non-trivial initial data of the lowest M+1 members. These include the multi-indexed orthogonal polynomials of Laguerre, Jacobi, Wilson, and Askey-Wilson types. The M = 0 case is the corresponding classical orthogonal polynomials.
A versatile medium-resolution x-ray emission spectrometer for diamond anvil cell applications
Authors: Mortensen D. R. , Seidler G. T. , Bradley J. A. , Lipp M. J. , Evans W. J. , Chow P. , Xiao Y.-M. , Boman G. , Bowden M. E.
Published: August 2013

We present design and performance details for a polycapillary-coupled x-ray spectrometer that provides very high collection efficiency at a moderate energy resolution suitable for many studies of nonresonant x-ray emission spectroscopy, especially for samples of heavy elements under high pressures. Using a single Bragg analyzer operating close to backscattering geometry so as to minimize the effect of the weak divergence of the quasicollimated exit beam from the polycapillary optic, this instrument can maintain a typical energy resolution of 5 eV over photon energies from 5 keV to 10 keV. We find dramatically improved count rates as compared to a traditional higher-resolution instrument based on a single spherically bent crystal analyzer.
The effect of SiO2 content on activation volumes in exchange coupled composite media
Authors: Chureemart J. , Lari L. , Nolan T. P. , O'Grady K.
Published: August 2013

The activation volume, Vact, and the physical grain volume, VTEM, have been investigated on identical structures of exchange coupled composite media with three different contents of silicon dioxide (SiO2) utilised for intergranular exchange decoupling. Time dependence measurements known as the waiting time method have been used to determine Vact. Transmission Electron Microscopy analysis has been carried out to investigate the grain size distribution and the composition distribution at the grain boundaries using bright field high resolution-scanning transmission electron microscopy (BF HR-STEM) and high angle annular dark-field (HAADF) modes. We found that Vact and VTEM decrease as the oxide content is increased. The activation volume and the single grain volume are in excellent agreement for the samples with the highest oxide content indicating complete exchange decoupling. The BF HR-STEM and HAADF STEM images indicate excellent SiO2 segregation at the grain boundaries. This result implies that the activation volume in advanced recording media can be estimated via the correlation to the grain size.
Effect of Co addition on the atomic ordering of FeCo-phase in nanocrystalline Fe81-xCoxNb7B12 alloys (x = 20.25, 27, 40.5, 54, 60.75): An anomalous diffraction and Mössbauer study
Authors: Gupta P. , Ganguli Tapas , Švec P. , Sinha A. K. , Gupta A. , Švec P. , Singh M. N. , Reddy V. R. , Deb S. K.
Published: August 2013

The influence of Co addition on the atomic ordering of bcc FeCo-phase in partially nanocrystalline Fe81-xCoxNb7B12 alloys (x = 20.25, 27, 40.5, 54, 60.75) was investigated using synchrotron radiation based x-ray diffraction (SR-XRD) and 57Fe Mössbauer spectroscopy (MS). The results indicate that as the Co content in the alloy increases, there is a decrease in the thermal stability against crystallization of the amorphous phase. In the pure amorphous state, topological ordering as well as compositional homogeneity of the amorphous phase increases with Co addition (x ≥ 40.5). In the partially nanocrystalline state (isothermally annealed at 823 K for 1 h), the anomalous diffraction measurements close to Fe K-edge provide unambiguous evidence of atomically ordered α′-FeCo phase (CsCl type) as the nanocrystalline ferromagnetic phase by the presence of (100) super-lattice reflection for the alloys with x ≥ 40.5. However, alloys with x ≤ 27 present a disordered structure as confirmed by the absence of superlattice reflection. The long range order parameter (S) possess maximum value for the alloys close to equi-atomic composition (x = 40.5 and 54). By predominant low hyperfine field contribution (close to 33.7 T), Mössbauer spectroscopy measurement also validates the atomically ordered FeCo nanocrystalline phase in Fe81-xCoxNb7B12 alloy with x ≥ 40.5.
The role of plasma evolution and photon transport in optimizing future advanced lithography sources
Authors: Sizyuk Tatyana , Hassanein Ahmed
Published: August 2013

Laser produced plasma (LPP) sources for extreme ultraviolet (EUV) photons are currently based on using small liquid tin droplets as target that has many advantages including generation of stable continuous targets at high repetition rate, larger photons collection angle, and reduced contamination and damage to the optical mirror collection system from plasma debris and energetic particles. The ideal target is to generate a source of maximum EUV radiation output and collection in the 13.5 nm range with minimum atomic debris. Based on recent experimental results and our modeling predictions, the smallest efficient droplets are of diameters in the range of 20–30 μm in LPP devices with dual-beam technique. Such devices can produce EUV sources with conversion efficiency around 3% and with collected EUV power of 190 W or more that can satisfy current requirements for high volume manufacturing. One of the most important characteristics of these devices is in the low amount of atomic debris produced due to the small initial mass of droplets and the significant vaporization rate during the pre-pulse stage. In this study, we analyzed in detail plasma evolution processes in LPP systems using small spherical tin targets to predict the optimum droplet size yielding maximum EUV output. We identified several important processes during laser-plasma interaction that can affect conditions for optimum EUV photons generation and collection. The importance and accurate description of modeling these physical processes increase with the decrease in target size and its simulation domain.
Large-scale molecular dynamics simulations of glancing angle deposition
Authors: Hubartt Bradley C. , Liu Xuejing , Amar Jacques G.
Published: August 2013

Using a computationally efficient method, we have carried out large-scale molecular dynamics simulations of Cu/Cu(100) growth up to 20 monolayers (ML) for deposition angles ranging from 50° to 85° and for both random and fixed azimuthal angles. A variety of quantities including the porosity, roughness, lateral correlation length, average grain size, strain, and defect concentration are used to characterize the thin-film morphology. For large deposition angles (θ≥80°), we find well-defined columnar growth while for smaller angles, columnar growth has not yet set in. In addition, for θ=70°−85°, the thin-film porosity and columnar tilt angles (for fixed azimuthal angle ϕ) are in reasonable agreement with experiments. For both random and fixed ϕ, the number of grains, average grain-size, and number of surface atoms belonging to (111) facets increase rapidly with deposition angle. As a result, twin facet formation and budding occur in our simulations, in good agreement with experiments. In good qualitative agreement with recent experimental observations, we also find that the average strain is initially compressive but becomes tensile after the onset of columnar growth. Our simulations also reveal that for large deposition angles a variety of unexpected and complex dynamical processes play a key role in determining the evolution of the surface morphology and microstructure. In particular, due to the existence of deposition-induced events, the vacancy density remains very small, even though the defect density is relatively large and increases with deposition angle. In addition, large-scale re-arrangement events as well as thermal (elastic) vibrations lead to large-amplitude oscillations in the columnar growth regime. These oscillations play a key role in promoting rapid coalescence via additional large-scale collective motion, thus, significantly enhancing the coarsening process.
Critical state solution and alternating current loss computation of polygonally arranged thin superconducting tapes
Authors: Brambilla Roberto , Grilli Francesco , Martini Luciano
Published: August 2013

The current density and field distributions in polygonally arranged thin superconducting tapes carrying AC current are derived under the assumption of the critical state model. Starting from the generic Biot-Savart law for a general polygonal geometry, we derive a suitable integral equation for the calculation of the current density and magnetic field in each tape. The model works for any transport current below Ic, which makes it attractive for studying cases of practical interest, particularly the dependence of AC losses on parameters such as the number of tapes, their distance from the center, and their separation.
Excitation of two-dimensional plasma wakefields by trains of equidistant particle bunches
Authors: Lotov K. V.
Published: August 2013

Nonlinear effects responsible for elongation of the plasma wave period are numerically studied with the emphasis on two-dimensionality of the wave. The limitation on the wakefield amplitude imposed by detuning of the wave and the driver is found.
Bistability and nonlinear negative differential conductance in semiconductor superlattices illuminated by laser light
Authors: Meng F. , Huppert S. , Harmand J. C. , Ferreira R. , Mangeney J.
Published: August 2013

We have experimentally and theoretically investigated negative differential conductance regions in the current-voltage characteristic of undoped semiconductor superlattice surrounded by barriers and illuminated by laser light. The negative differential conductances are nonlinear and show bistable behavior as a function of the applied voltage. These phenomena are quantitatively described by a self-consistent analysis of the field-dependent Wannier-Stark absorption and accumulation of photocarriers in the presence of barriers at the superlattice borders.
Communication: Non-radiative recombination via conical intersection at a semiconductor defect
Authors: Shu Yinan , Levine Benjamin G.
Published: August 2013

Localization of electronic excitations at molecule-sized semiconductor defects often precedes non-radiative (NR) decay, and it is known that many molecules undergo NR decay via conical intersection. Herein, we report the direct simulation of fast and efficient NR decay via a conical intersection at a known semiconductor defect. It is suggested that this silicon epoxide defect may selectively quench photoluminescence (PL) in small silicon nanocrystals (band gap > ∼2.8 eV), and thus influence both the observed PL yield and PL energy of oxidized silicon nanocrystals.
Vacancy-type defects introduced by plastic deformation of GaN studied using monoenergetic positron beams
Authors: Uedono Akira , Yonenaga Ichiro , Watanabe Tomohito , Kimura Shogo , Oshima Nagayasu , Suzuki Ryoichi , Ishibashi Shoji , Ohno Yutaka
Published: August 2013

Vacancy-type defects in plastically deformed GaN were studied using monoenergetic positron beams. Dislocations with a Burgers vector of (1/3)[12¯10] were introduced by applying compressive stress at 950 °C. Measurements of Doppler broadening spectra of the annihilation radiation and positron lifetime spectra showed that both microvoids and Ga-vacancy-type defects were introduced into the deformed sample. The former defects are considered to be introduced through an agglomeration of vacancies introduced by dislocation motions. We observed a distribution of the mean positron lifetime along a long side of the deformed sample, which corresponds to the stress distribution during the deformation. In photoluminescence studies, yellow-band luminescence (2.2 eV) decreased due to the deformation. The suppression of this band was attributed to the vacancy-type defects and/or dislocations introduced by the deformation.
Nonpolar light emitting diode with sharp near-ultraviolet emissions using hydrothermally grown ZnO on p-GaN
Authors: Baik Kwang Hyeon , Kim Hyonwoong , Kim Jihyun , Jung Sukkoo , Jang Soohwan
Published: August 2013

Nonpolar n-ZnO/p-GaN heterojunction light emitting diode has been demonstrated with a-plane (112¯0) ZnO active layer grown by a facile low-cost solution growth method at low temperature of 90 °C. High quality nonpolar ZnO planar film without seed layer was directly formed on a-plane GaN template due to the anisotropic growth rates along the specific crystallographic directions. The turn on voltage of the device was as low as 3 V, and narrow stable UV-blue electroluminescence emissions with peak wavelength of 392 to 420 nm under various forward bias conditions at room temperature were observed.
Absolute second order nonlinear susceptibility of Pt nanowire arrays on MgO faceted substrates with various cross-sectional shapes
Authors: Ogata Yoichi , Mizutani Goro
Published: August 2013

We have measured optical second harmonic generation (SHG) intensity from three types of Pt nanowires with 7 nm widths of elliptical and boomerang cross-sectional shapes and with 2 nm width elliptical cross-sectional shapes on the MgO faceted templates. From the SHG intensities, we calculated the absolute value of the nonlinear susceptibility χ(2) integrated in the direction of the wire-layer thickness. The tentatively obtained bulk χ(2)B of the wire layer was very large, approaching the value of the well-known nonlinear optical material BaTiO3.
Effects of Using Multiple Hands and Fingers on Haptic Performance
Authors: Morash Valerie S , Pensky Allison E Connell , Miele Joshua A
Published: August 2013

It remains controversial whether using two hands and multiple fingers provides any perceptual advantage over a single index finger. The present study examines this long-running question in the haptic-exploration literature by applying rigorous, psychophysical, and mathematical modeling techniques. We compared the performance of fourteen blindfolded sighted participants on seven tactile-map tasks using seven finger conditions. All tasks were benefited by multiple fingers, but it varied whether multiple fingers were beneficial on one hand, two hands, or both. Line-tracing tasks were performed faster when two hands were used, but not more than one finger per hand. Local and global search tasks were faster with multiple fingers, but not two hands. Distance comparison tasks were also performed faster with multiple fingers, and sometimes with two hands. Lastly, moving in a straight line was faster with multiple fingers, but was especially difficult with just two index fingers. These results provide empirical evidence that multiple hands and fingers benefit haptic perception, but the benefits are more complex than simply extending the tactile field of ‘view’. This analogy between touch and vision fails to account for the autonomous movements and sensations of the fingers, which we show benefit the haptic perceptual system.
Neurokinin3 receptor as a target to predict and improve learning and memory in the aged organism
Authors: de Souza Silva Maria A. , Lenz Bernd , Rotter Andrea , Biermann Teresa , Peters Oliver , Ramirez Alfredo , Jessen Frank , Maier Wolfgang , Hüll Michael , Schröder Johannes , Frölich Lutz , Teipel Stefan , Gruber Oliver , Kornhuber Johannes , Huston Joseph P. , Müller Christian P. , Schäble Sandra
Published: August 2013

Significance

Cognitive decline during aging impairs life quality and may lead to dementia. It is associated with a dysfunction of the brain acetylcholinergic system. Here we demonstrate that pharmacological stimulation of neurokinin3 receptors improves learning and memory in aged rats by enhancing acetylcholinergic function in the brain. In a human association study we show that a single-nucleotide polymorphism in the neurokinin3-receptor–coding gene
TACR3
can predict learning and memory in elderly patients with cognitive impairments and their hippocampus volume. These findings suggest the neurokinin3 receptor as a potential biomarker and treatment target for cognitive enhancement in the elderly.