bluuebunny/crossref_metadata_2025 huggingface dataset:
Luminous flux improvement of xenon fluorescent lamps by applying synchronized high-voltage pulse to the auxiliary external electrode
Authors: Motomura Hideki , Oka Kojiro , Sogabe Toru , Jinno Masafumi
Published: May 2011

As the environmental awareness of people becomes stronger, the demand for mercury-free light sources also becomes stronger. The authors have been developing cold cathode fluorescent lamps in which xenon gas is filled as an ultraviolet radiator instead of mercury. Previously the authors reported the luminous flux enhancement method using a grounded auxiliary external electrode (AEE). In this paper, in order to improve the luminous flux much more, a positive voltage pulse which was synchronized to the main driving negative voltage pulse was applied to the AEE. As a result, the maximum input power increased under which the positive column did not constrict and the luminous flux improved by 70% at the xenon filling pressure of 6.7 kPa. It is proved that the positive voltage pulse application to the AEE with the amplitude of more than 2 kV expands the positive column in the radial direction. It is attributed to the phenomenon that the residual ions and electrons, which are generated by dielectric barrier discharge between the AEE and the anode during the falling edge of the negative pulse to the cathode, spread the discharge path from the anode towards the AEE during the cold cathode discharge mode. By increasing the xenon filling pressure, luminous efficacy was improved to 25 lm W−1.
Development of free-standing InGaN LED devices on Al2O3/Si substrate by wet etching
Authors: Jamil M , Xu T , Melton A , Jampana B , Ferguson I T
Published: May 2011

Free-standing InGaN-based LEDs grown on Al2O3/Si (1 1 1) have been achieved using selective area wet etching. Conventional device design was used for LED fabrication, in which p-type and n-type contacts are located at the same side of the epilayers. These LED devices were bonded to a dual in-line package (DIP), and epoxy was used to protect the front side of the epilayers as well as the bonding wires. The silicon substrate was selectively removed by wet etching while the chip was mounted in a DIP which prevented the thin film from cracking or warping. No significant change in electrical characteristics, peak emission wavelength or EL intensity versus drive current was observed. The substrate-removal process and the challenges involved are discussed. Such packaging techniques could be beneficial for commercial-scale production of InGaN-based LEDs grown on silicon substrates.
Improvement of quantum efficiency in green light-emitting diodes with pre-TMIn flow treatment
Authors: Lee Ya-Ju , Chen Yi-Ching , Lu Tien-Chang
Published: May 2011

The effects of pre-trimethlyindium (TMIn) flow on the improved electrical characteristics and highly stable temperature properties of InGaN green light-emitting diodes (LEDs) are discussed. For the LED sample with a pre-TMIn flow treatment, the tunnelling of injected carriers associated with threading defects is significantly reduced, which promotes the diffusion–recombination of injected carriers, as well as the overall emission efficiency of the LED. In addition, the pre-TMIn flow treatment evidently reduces the dependence of external quantum efficiency on temperature and efficiency droop of green LEDs. As a result, we conclude that the pre-TMIn flow treatment is a promising scheme for the improvement of output performance of InGaN-based green LEDs.
Plasmonically enhanced quantum-dot white-light InGaN light-emitting diode
Authors: Mak G Y , Zhu L , Ma Zetao , Huang S Y , Lam E Y , Choi H W
Published: May 2011

The enhancement of white light emission from quantum-dot-coated InGaN light-emitting diodes (LEDs) via localized surface plasmon (LSP) resonance of metallic nanoparticles (MNPs) is investigated and demonstrated. With liquid-immersion laser ablation of metals, MNPs with a broad range of dimensions were synthesized in a single process. Since the LSP resonant wavelength depends strongly on the dimensions of MNPs, enhancement over a wide range of wavelengths in the visible spectrum is expected. MNPs of Ag, Au, Cu, Ni and Ti were experimented on. It is found that all MNPs result in an increase in the luminous flux and luminous efficacy of the quantum-dot-coated LEDs, with Ag NPs having the strongest effect (17.9%) amongst all metals tested. This observation is explained in terms of the resonance of the polarizability of the MNPs.
Zinc oxide nanorods/polymer hybrid heterojunctions for white light emitting diodes
Authors: Willander M , Nur O , Zaman S , Zainelabdin A , Bano N , Hussain I
Published: May 2011

Zinc oxide (ZnO) with its deep level defect emission covering the whole visible spectrum holds promise for the development of intrinsic white lighting sources with no need of using phosphors for light conversion. ZnO nanorods (NRs) grown on flexible plastic as substrate using a low temperature approach (down to 50 °C) were combined with different organic semiconductors to form hybrid junction. White electroluminescence (EL) was observed from these hybrid junctions. The configuration used for the hybrid white light emitting diodes (LEDs) consists of two-layers of polymers on the flexible plastic with ZnO NRs on the top. The inorganic/organic hybrid heterojunction has been fabricated by spin coating the p-type polymer poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT : PSS) for hole injection with an ionization potential of 5.1 eV and poly(9, 9-dioctylfluorene) (PFO) is used as blue emitting material with a bandgap of 3.3 eV. ZnO NRs are grown on top of the organic layers. Two other configurations were also fabricated; these are using a single MEH PPV (red-emitting polymer) instead of the PFO and the third configuration was obtained from a blend of the PFO and the MEH PPV. The white LEDs were characterized by scanning electron microscope, x-ray diffraction (XRD), current–voltage (I–V) characteristics, room temperature photoluminescence (PL) and EL. The EL spectrum reveals a broad emission band covering the range from 420 to 800 nm, and the emissions causing this white luminescence were identified.
Influence of the substrate platform on the opto-electronic properties of multi-layer organic light-emitting field-effect transistors
Authors: Generali Gianluca , Dinelli Franco , Capelli Raffaella , Toffanin Stefano , Muccini Michele
Published: May 2011

In this paper, we present a study of the effects of the influence of the substrate platform on the properties of a three-layer vertical hetero-junction made of thin films of α, ω-diperfluorohexyl-4T (DHF4T), a blend of tris(8-hydroxyquinoline)aluminium (Alq3) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) and α, ω-dihexyl-quaterthiophene (DH4T). The hetero-junction represents the active component of an organic light-emitting transistor (OLET). The substrate platforms investigated in this study are glass/indium-tin-oxide/poly(methyl-methacrylate) (PMMA) and Si++/silicon oxide (SiO2)/PMMA. The first platform is almost completely transparent to light and therefore is very promising for use in OLET applications. The second one has been chosen for comparison as it employs standard microelectronic materials, i.e. Si++/SiO2. We show how different gate materials and structure can affect the relevant field-effect electrical characteristics, such as the charge mobility and threshold voltage. By means of an atomic force microscopy analysis, a systematic study has been made in order to correlate the morphology of the active layers with the electrical properties of the devices.
Transport studies using laser blow-off injection of low-Z trace impurities injected into the TJ-II stellarator
Authors: Zurro B. , Hollmann E. , Baciero A. , Ochando M.A. , Medina F. , McCarthy K.J. , Blanco E. , de la Cal E. , Carralero D. , Pedrosa M.A.
Published: May 2011

Trace (<5%) impurity seeding of boron and carbon by laser blow-off is used to study low-Z parallel and radial impurity transport in the TJ-II stellarator. Toroidal transport is observed to be quite rapid τϕ ∼ 0.1 ms, roughly consistent with expectations of collisionless (kinetic) parallel ion transport. Radial impurity de-confinement of injected impurities to the plasma wall is measured to be much slower, τ
r
∼ 10 ms. The data suggest a slightly higher τ
r
for carbon than for boron, but no clear charge state dependence is observed in contrast with expectations for neoclassical transport in the low collisionality regime.
Necessary criterion for magnetic field reversal in the reversed-field pinch
Authors: Bonfiglio D. , Escande D.F. , Zanca P. , Cappello S.
Published: May 2011

We derive analytically a necessary criterion for the reversal of the axial magnetic field of ohmic single-helicity states of the reversed-field pinch. This is done in the frame of resistive magnetohydrodynamics (MHD) in cylindrical geometry using perturbation theory for a paramagnetic pinch with low edge conductivity and axial magnetic field. The criterion involves the radial profile of the logarithmic derivative of the Newcomb eigenfunction of the pinch. It is suggestive that a finite edge radial magnetic field B

r
(a) might be favourable for field reversal. In accordance with this, visco-resistive MHD simulations show that helical equilibria with smaller maximum radial magnetic fields achieve reversal when a finite B

r
(a) is applied. Numerical simulations also show that the criterion works for large perturbations of the pinch too, in particular those leading to states with a single helical axis. The necessary criterion is found to be satisfied for reversed states where a finite B

r
(a) is driven in the RFX-mod machine.
Development of a plasma current ramp-up technique for spherical tokamaks by the lower hybrid wave
Authors: Takase Y. , Ejiri A. , Kakuda H. , Nagashima Y. , Wakatsuki T. , Watanabe O. , Bonoli P. , Meneghini O. , Shiraiwa S. , Wright J. , Moeller C. , Kasahara H. , Kumazawa R. , Mutoh T. , Saito K.
Published: May 2011

Spherical tokamaks (STs) have the advantage of high beta capability, but the realization of a compact reactor requires the elimination of the central solenoid (CS). The possibility of using the lower hybrid wave (LHW) to ramp up the plasma current (I
p) from zero to a high enough level required for fusion burn in ST is examined theoretically and experimentally. Excitation of a travelling fast wave (FW) by the combline antenna installed on TST-2 was confirmed by a finite element analysis, but efficient current drive requires excitation of the LHW, either directly by the antenna or by mode conversion from the FW. The analysis using the TORLH full-wave solver indicates that core current drive by LHW is possible in the low-density, low I
p plasma formed by electron cyclotron heating (ECH). It is important to keep the density low during I
p ramp-up, and the wavenumber must be reduced as I
p increases. Initial results from TST-2 demonstrate that RF power in the LH frequency range (200 MHz) can achieve initial I
p formation, and is more effective than ECH for further ramp-up of I
p. I
p ramp-up to over 12 kA was achieved by combining ramp-up of the externally applied vertical magnetic field and ramp-up of the RF power. The significant asymmetry observed between co-current drive and counter-current drive is attributed to the presence of RF driven current. An optimized LHW antenna with appropriate polarization and wavenumber spectrum controllability is being designed. The success of the TST-2 experiment would provide a scientific basis for quantitatively evaluating the required CS capability for a low-aspect-ratio reactor.
Implementation of advanced feedback control algorithms for controlled resonant magnetic perturbation physics studies on EXTRAP T2R
Authors: Frassinetti L. , Olofsson K.E.J. , Brunsell P.R. , Drake J.R.
Published: May 2011

The EXTRAP T2R feedback system (active coils, sensor coils and controller) is used to study and develop new tools for advanced control of the MHD instabilities in fusion plasmas. New feedback algorithms developed in EXTRAP T2R reversed-field pinch allow flexible and independent control of each magnetic harmonic. Methods developed in control theory and applied to EXTRAP T2R allow a closed-loop identification of the machine plant and of the resistive wall modes growth rates. The plant identification is the starting point for the development of output-tracking algorithms which enable the generation of external magnetic perturbations. These algorithms will then be used to study the effect of a resonant magnetic perturbation (RMP) on the tearing mode (TM) dynamics. It will be shown that the stationary RMP can induce oscillations in the amplitude and jumps in the phase of the rotating TM. It will be shown that the RMP strongly affects the magnetic island position.
Simulation of the neutral beam deposition within integrated tokamak modelling frameworks
Authors: Schneider M. , Eriksson L.-G. , Jenkins I. , Artaud J.F. , Basiuk V. , Imbeaux F. , Oikawa T.
Published: May 2011

The NEMO (NEutral beam MOdelling) code for simulating neutral beam ionization during neutral beam injection (NBI) in tokamak plasmas has been developed for implementation in integrated modelling frameworks and is presented. Integrated modelling of fusion plasmas is becoming increasingly important, both for preparation and analysis of experiments in large devices. Moreover, it should play a crucial role for the design of future fusion reactors. In a modern context, integrated modelling requires codes that are (i) flexible in terms of their interfaces, i.e. can be adapted for different simulation environments, (ii) machine independent; i.e. they should not contain hard coded information on a particular device to be simulated; (iii) optimized for speed of execution, (iv) verified and validated. The NEMO code has been specially designed to meet these requirements. The code is based on the physics concept outlined by Feng et al (1995 Comput. Phys. Commun.
88 161–72) and is a completely modular program: it works with any input NBI geometry and can be coupled to any external Fokker–Planck calculation for evaluating the distribution function of the injected species, i.e. it can provide source terms for both Monte Carlo codes and codes using finite difference/elements methods. The NEMO code has already been integrated with the CRONOS integrated modelling suite (Artaud et al
2010 Nucl. Fusion
50 043001) and the European Integrated Tokamak Modelling Task Force (ITM-TF)b
https://www.efda-itm.eu/index.html. The basics of the code are described in this paper along with an illustration of its integration in the ITM-TF simulation platform. A crucial aspect is the verification of the code, the results of benchmarks carried out with other NBI codes for JET and ITER discharges are thereby presented.
Long-range correlations and edge transport bifurcation in fusion plasmas
Authors: Xu Y. , Carralero D. , Hidalgo C. , Jachmich S. , Manz P. , Martines E. , van Milligen B. , Pedrosa M.A. , Ramisch M. , Shesterikov I. , Silva C. , Spolaore M. , Stroth U. , Vianello N.
Published: May 2011

Recently, a European transport project has been carried out among several fusion devices for studying the possible link between the mean radial electric field (E

r
), long-range correlation (LRC) and edge bifurcations in fusion plasmas. The main results reported in this paper include: (i) the discovery of low-frequency LRCs in potential fluctuations which are amplified during the development of edge mean E

r
using electrode biasing and during the spontaneous development of edge sheared flows in stellarators and tokamaks. Evidence of nonlocal energy transfer and the geodesic acoustic mode modulation on local turbulent transport have also been observed. The observed LRCs are consistent with the theory of zonal flows described by a ‘predator–prey’ model. The results point to a significant link between the LRC and transport bifurcation. (ii) Comparative studies in tokamaks, stellarators and reversed field pinches have revealed significant differences in the level of the LRC. Whereas the LRCs are clearly observed in tokamaks and stellarators, no clear signature of LRCs was seen in the RFX-mod reversed field pinch experiments. These results suggest the possible influence of magnetic perturbations on the LRC, in agreement with recent observations in the resonant magnetic perturbation experiments at the TEXTOR tokamak. (iii) The degree of the LRCs is strongly reduced on approaching the plasma density-limit in tokamaks and stellarators, suggesting the possible role of collisionality or/and the impact of mean E

r
× B flow shear on zonal flows.
Transient process of a spherical tokamak plasma startup by electron cyclotron waves
Authors: Tan Y. , Gao Z. , Wang L. , Wang W.H. , Xie L.F , Yang X.Z. , Feng C.H.
Published: May 2011

Non-inductive startup by a 2.45 GHz microwave through electron cyclotron resonance heating (ECRH) has been studied in the SUNIST spherical tokamak (R/a: 0.3 m/0.23 m; B
T0: < 0.15 T). Two types of discharges, with quite different transient characteristics, were found. The transient processes of discharges are experimentally investigated by scanning the radial position of the ECR layer, the vertical magnetic field and the microwave power. Time domain analysis of microwave reflections and Hα emissions reveal a process dominated by the combination of ionization, loss along the open field lines and the gradient B drift. It is shown that the transient character is insensitive to the experimental parameters except the pressure of filled gas. This result confirms that the control of gas puffing is of great importance for starting up a spherical tokamak by ECRH using low-frequency microwaves.
L-mode validation studies of gyrokinetic turbulence simulations via multiscale and multifield turbulence measurements on the DIII-D tokamak
Authors: Rhodes T.L. , Holland C. , Smith S.P. , White A.E. , Burrell K.H. , Candy J. , DeBoo J.C. , Doyle E.J. , Hillesheim J.C. , Kinsey J.E. , McKee G.R. , Mikkelsen D. , Peebles W.A. , Petty C.C. , Prater R. , Parker S. , Chen Y. , Schmitz L. , Staebler G.M. , Waltz R.E. , Wang G. , Yan Z. , Zeng L.
Published: May 2011

A series of carefully designed experiments on DIII-D have taken advantage of a broad set of turbulence and profile diagnostics to rigorously test gyrokinetic turbulence simulations. In this paper the goals, tools and experiments performed in these validation studies are reviewed and specific examples presented. It is found that predictions of transport and fluctuation levels in the mid-core region (0.4 < ρ < 0.75) are in better agreement with experiment than those in the outer region (ρ ⩾ 0.75) where edge coupling effects may become increasingly important and multiscale simulations may also be necessary. Validation studies such as these are crucial in developing confidence in a first-principles based predictive capability for ITER.
Surface behaviour in deuterium permeation through erbium oxide coatings
Authors: Chikada T. , Suzuki A. , Adelhelm C. , Terai T. , Muroga T.
Published: May 2011

Suppression of tritium permeation through structural materials is essential in order to mitigate fuel loss and radioactivity concerns. Ceramic coatings have been investigated for over three decades as tritium permeation barriers (TPBs); however, a very limited number of investigations on the mechanism of hydrogen-isotope permeation through the coatings have been reported. In this study, deuterium permeation behaviour of erbium oxide coatings fabricated by filtered arc deposition on reduced activation ferritic/martensitic steels has been investigated. The samples coated on both sides of the substrates showed remarkably lower permeability than those coated on one side, and the maximum reduction efficiency indicated a factor of 105 compared with the substrate. The different permeation behaviour between the coatings facing the high and low deuterium pressure sides has been found by the crystal structure analysis and the evaluation of the energy barriers. It is suggested that the permeation processes on the front and back surfaces are independent, and the TPB efficiency of the samples coated on both sides can be expressed by a multiplication of that of each side.
Comment on ‘The role of the RF induced electric field in the current drive by EC waves in the presence of magnetic islands’
Authors: Westerhof E.
Published: May 2011

It is shown that the equations solved in the paper (Rosa and Ziebell 2010 Nucl. Fusion
50 115009) do not describe the consistent evolution of the parallel electric field and the electron cyclotron driven current density in a geometry with a magnetic island. Therefore, do the ‘effects’ of the induced parallel electric field on the electron cyclotron driven current as claimed in this paper have no bearing on the stabilizing effect of electron cyclotron current drive on neoclassical tearing modes.
Reply to comment on ‘The role of the RF induced electric field in the current drive by EC waves in the presence of magnetic islands’
Authors: Rosa P.R. da S. , Ziebell L.F.
Published: May 2011

The present paper is motivated by a comment by Westerhof and intends to clarify the contents of previous papers which we have published about investigations on the subject of EC current generation in the presence of magnetic islands, either neglecting or taking into account inductive effects.
Estimating the resolution of a commercial optical coherence tomography system with limited spatial sampling
Authors: Woolliams Peter D , Tomlins Peter H
Published: May 2011

Optical coherence tomography (OCT) is becoming increasingly widespread as an experimental tool for clinical investigation, facilitated by the development of commercial instruments. In situ performance evaluation of such ‘black box’ systems presents a challenge, where the instrument hardware and software can limit access to important configuration parameters and raw data. Two key performance metrics for imaging systems are the point-spread function (PSF) and the associated modulation transfer function (MTF). However, previously described experimental measurement techniques assume user-variable spatial sampling and may not be appropriate for the characterization of deployed commercial instruments. Characterization methods developed for other modalities do not address this issue and rely upon experimental accuracy. Therefore, in this paper we propose a method to characterize the PSF of a commercial OCT microscope that uses OCT images of three-dimensional PSF phantoms to produce an oversampled estimate of the system PSF by combining spatially coincident measurements. This method does not rely upon any strong a priori assumption of the PSF morphology, requires no modification to the system sampling configuration or additional experimental procedure. We use our results to determine the PSF and MTF across the B-scan image plane of a commercial OCT system.
Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample
Authors: Rebelo Kornmeier Joana , Gibmeier Jens , Hofmann Michael
Published: May 2011

Neutron strain measurements are critical at the surface. When scanning close to a sample surface, aberration peak shifts arise due to geometrical and divergence effects. These aberration peak shifts can be of the same order as the peak shifts related to residual strains. In this study it will be demonstrated that by optimizing the horizontal bending radius of a Si (4 0 0) monochromator, the aberration peak shifts from surface effects can be strongly reduced. A stress-free sample of fine-grained construction steel, S690QL, was used to find the optimal instrumental conditions to minimize aberration peak shifts. The optimized Si (4 0 0) monochromator and instrument settings were then applied to measure the residual stress depth gradient of a shot-peened SAE 4140 steel sample to validate the effectiveness of the approach. The residual stress depth profile is in good agreement with results obtained by x-ray diffraction measurements from an international round robin test (BRITE-EURAM-project ENSPED). The results open very promising possibilities to bridge the gap between x-ray diffraction and conventional neutron diffraction for non-destructive residual stress analysis close to surfaces.
Direct optical techniques for the measurement of water content in oil–paper insulation in power transformers
Authors: Rodríguez-Rodríguez Joaquín H , Martínez-Piñón Fernando , Álvarez-Chávez José A , Jaramillo-Vigueras David , Robles-Pimentel Edgar G
Published: May 2011

Paper–oil insulation in power transformers is degraded and gradually damaged due to electrical, chemical, mechanical and moisture factors. It is well established from several studies that moisture is a major source of insulation failure in high voltage power transformers. Measurement and monitoring of moisture is essential to predict life and operation condition for power transformers. This paper presents direct optical measurement of water content at paper insulation immersed in transformer oil inside a test cell, which contains a water source, and a capillary paper bridge to transfer water to the paper inside an oil reservoir. Optical measurement of water content was carried out in the near infrared from 900 to 1500 nm band. Experimental studies of light transmission in transformer oil and water are discussed. The criteria to establish the best optical bands for maximum sensitivities are given. The measurement limitations, calibration procedures and an error analysis are presented. The resulting technique can be used for on-line measurements in electrical apparatus that use oil–paper insulation under large electrical field gradients. The presented method has advantages, since it is a direct and fast technique to measure the water transfer to paper immersed in oil, and it could be applied in compact portable equipment at a low cost.
Validation of microwave radiometry for measuring the internal temperature profile of human tissue
Authors: Levick A , Land D , Hand J
Published: May 2011

A phantom target with a known linear temperature gradient has been developed for validating microwave radiometry for measuring internal temperature profiles within human tissue. The purpose of the phantom target is to simulate the temperature gradient found within the surface layers of a baby's brain during hypothermal neuroprotection therapy, in which the outer surface of the phantom represents the skin surface and the inner surface the brain core. The target comprises a volume of phantom tissue material with similar dielectric properties to high water-content human tissue, contained between two copper plates at known temperatures. The antenna of a microwave radiometer is in contact with one surface of the phantom material. We have measured the microwave temperature of the phantom with microwave radiometry in a frequency band of 3.0–3.5 GHz. Our microwave temperature measurements have small 0.05 °C (type A) uncertainties associated with random effects and provide temperatures consistent with values determined using theoretical models of the antenna–target system within uncertainties. The measurements are in good agreement with the major signal contribution being formed over a near plane-wave response within the material with a much smaller contribution from close to the antenna face.
Algebras with radical square zero are either self-injective or CM-free
Authors: Chen Xiao-Wu
Published: May 2011

An artin algebra is called CM-free provided that all its finitely generated Gorenstein projective modules are projective. We show that a connected artin algebra with radical square zero is either self-injective or CM-free. As a consequence, we prove that a connected artin algebra with radical square zero is Gorenstein if and only if its valued quiver is either an oriented cycle with the trivial valuation or does not contain oriented cycles.
Fully documented fishery: a tool to support a catch quota management system
Authors: Kindt-Larsen Lotte , Kirkegaard Eskild , Dalskov Jørgen
Published: May 2011

Kindt-Larsen, L., Kirkegaard, E., and Dalskov, J. 2011. Fully documented fishery: a tool to support a catch quota management system. – ICES Journal of Marine Science, 68: 1606–1610. The Danish Government has proposed a catch quota management system (CQMS) in which fishers are obliged to report their total catches, including discards and landings, and both are counted against the formal total allowable catch (TAC). The success of a CQMS requires appropriate documentation to verify the total catch, the validity of scientific advice, and the implementation of the TACs through national catch quotas. A remote electronic monitoring (EM) system, providing full documentation of fishing operations and catches, was tested on six Danish fishing vessels operating under a CQMS for cod (Gadus morhua). The results showed that the EM system could provide the documentation required to support the CQMS and that it was an incentive for the participating fishers to avoid discarding cod. Changing from landings to total catch quotas would not affect the scientific-advisory processes of the International Council for the Exploration of the Sea (ICES), but it could have notable consequences for the allocation of TACs between countries.
Fibromyalgia Syndrome
Authors: Glennon Peter
Published: May 2011

The concept of widespread pain in association with fatigue and general malaise has been recognized for over 100 years. Froriep described ‘rheumatism with hard and tender places' in the 19th century and Gower introduced the term ‘fibrositis' in 1904. Vague notions of muscular tenderness and ‘ psychogenic rheumatism’ prevailed for decades after this. However, it was only with the use of the term fibromyalgia in the 1980s and the publication of the seminal paper of the American College of Rheumatology (ACR) in 1990 that a more unified concept of fibromyalgia syndrome (FMS) emerged. The aim of this article is to give the GP in training a sound understanding of FMS and to address the specific learning objectives of the GP curriculum as they apply to this complex syndrome.
Motor Neurone Disease
Authors: Jani Bhautesh D.
Published: May 2011

Motor neurone disease (MND) is a progressive degenerative disorder affecting the motor neurones. The incidence of MND is 2 per 100 000 population/year and prevalence is approximately 4–6 per 100 000 population. There is still no cure for MND, nor any treatment that improves the prognosis greatly. Early referral to a neurologist is recommended if MND is suspected. Multidisciplinary team input with focus on symptom control is the cornerstone of management.
Worker inhalation dose coefficients for radionuclides not previously identified in ICRP publication 68
Authors: McLaughlin David A. , Schwahn Scott O.
Published: May 2011

While inhalation dose coefficients are provided for about 800 radionuclides in International Commission on Radiological Protection (ICRP) Publication 68, many radionuclides of practical dosimetric interest for facilities such as high-energy proton accelerators are not specifically addressed, nor are organ-specific dose coefficients tabulated. The ICRP Publication 68 dosimetry concepts are used, along with updated radiological decay data and metabolic data, to calculate committed equivalent dose coefficients [hT(50)] and committed effective dose coefficients [e(50)] for radionuclides produced at the Oak Ridge National Laboratory's Spallation Neutron Source.
Regulation of Spinal Substance P Release by Intrathecal Calcium Channel Blockade
Authors: Takasusuki Toshifumi , Yaksh Tony L.
Published: May 2011

Background

The authors investigated the role of different voltage-sensitive calcium channels expressed at presynaptic afferent terminals in substance P release and on nociceptive behavior evoked by intraplantar formalin by examining the effects of intrathecally delivered N- (ziconotide), T- (mibefradil), and L-type voltage-sensitive calcium channel blockers (diltiazem and verapamil).

Methods

Rats received intrathecal pretreatment with saline or doses of morphine, ziconotide, mibefradil, diltiazem, or verapamil. The effect of these injections upon flinching evoked by intraplantar formalin (5%, 50 μl) was quantified. To assess substance P release, the incidence of neurokinin-1 receptor internalization in the ipsilateral and contralateral lamina I was determined in immunofluorescent-stained tissues.

Results

Intrathecal morphine (20 μg), ziconotide (0.3, 0.6, and 1 μg), mibefradil (100 μg, but not 50 μg), diltiazem (500 μg, but not 300 μg), and verapamil (200 μg, but not 50 and 100 μg) reduced paw flinching in phase 2 compared with vehicle control (P < 0.05), with no effect on phase 1. Ziconotide (0.3, 0.6, and 1 μg) and morphine (20 μg) significantly inhibited neurokinin-1 receptor internalization (P < 0.05), but mibefradil, diltiazem, and verapamil at the highest doses had no effect.

Conclusion

These results emphasize the role in vivo of N-type but not T- and L-type voltage-sensitive calcium channel blockers in mediating the stimulus-evoked substance P release from small primary afferents and suggest that T- and L-type voltage-sensitive calcium channel blockers exert antihyperalgesic effects by an action on other populations of afferents or mechanisms involving postsynaptic excitability.
Unstable eigenmodes are possible drivers for cardiac arrhythmias
Authors: Tveito Aslak , Lines Glenn , Skavhaug Ola , Maleckar Mary M.
Published: May 2011

The well-organized contraction of each heartbeat is enabled by an electrical wave traversing and exciting the myocardium in a regular manner. Perturbations to this wave, referred to as arrhythmias, can lead to lethal fibrillation if not treated within minutes. One manner in which arrhythmias originate is an ill-fated interaction of the regular electrical signal controlling the heartbeat, the sinus wave, with an ectopic stimulus. It is not fully understood how and when ectopic waves are generated. Based on mathematical models, we show that ectopic beats can be characterized in terms of unstable eigenmodes of the resting state.
Ambush frequency should increase over time during optimal predator search for prey
Authors: Alpern Steve , Fokkink Robbert , Timmer Marco , Casas Jérôme
Published: May 2011

We advance and apply the mathematical theory of search games to model the problem faced by a predator searching for prey. Two search modes are available: ambush and cruising search. Some species can adopt either mode, with their choice at a given time traditionally explained in terms of varying habitat and physiological conditions. We present an additional explanation of the observed predator alternation between these search modes, which is based on the dynamical nature of the search game they are playing:
the possibility of ambush decreases the propensity of the prey to frequently change locations and thereby renders it more susceptible to the systematic cruising search portion of the strategy.
This heuristic explanation is supported by showing that in a new idealized search game where the predator is allowed to ambush or search at any time, and the prey can change locations at intermittent times, optimal predator play requires an alternation (or mixture) over time of ambush and cruise search. Thus, our game is an extension of the well-studied ‘Princess and Monster’ search game. Search games are zero sum games, where the pay-off is the capture time and neither the Searcher nor the Hider knows the location of the other. We are able to determine the optimal mixture of the search modes when the predator uses a mixture which is constant over time, and also to determine how the mode mixture changes over time when dynamic strategies are allowed (the ambush probability increases over time). In particular, we establish the ‘square root law of search predation’:
the optimal proportion of active search equals the square root of the fraction of the region that has not yet been explored.
Converging towards the optimal path to extinction
Authors: Schwartz Ira B. , Forgoston Eric , Bianco Simone , Shaw Leah B.
Published: May 2011

Extinction appears ubiquitously in many fields, including chemical reactions, population biology, evolution and epidemiology. Even though extinction as a random process is a rare event, its occurrence is observed in large finite populations. Extinction occurs when fluctuations owing to random transitions act as an effective force that drives one or more components or species to vanish. Although there are many random paths to an extinct state, there is an optimal path that maximizes the probability to extinction. In this paper, we show that the optimal path is associated with the dynamical systems idea of having maximum sensitive dependence to initial conditions. Using the equivalence between the sensitive dependence and the path to extinction, we show that the dynamical systems picture of extinction evolves naturally towards the optimal path in several stochastic models of epidemics.
Modelling of contact regimes in wire sawing with dissipative particle dynamics
Authors: Bierwisch C. , Kübler R. , Kleer G. , Moseler M.
Published: May 2011

Optimization of the wire sawing process of silicon ingots requires a profound understanding of the dynamic interaction of wire, slurry and silicon material. In this paper, the influence of wire velocity and applied wire stress on the process is investigated using dissipative particle dynamics and discrete element simulations for modelling the fluid and the grains in the abrasive suspension. In our simulations, different contact regimes occur depending on grain shape and a stress balance within the system. We observed semi-contact for high wire stress and low wire velocity and non-contact for low stress and high velocities in agreement with predictions from elasto-hydrodynamic modelling. Our simulations suggest the usage of sharp grains, since in this case, stress localization on the base of the sawing groove occurs even in the non-contact regime. These insights are likely to provide a scientific base for the optimization of sawing rates and reduction of kerf loss.
Thermal and hydrodynamic effects in the ordering of lamellar fluids
Authors: Gonnella G. , Lamura A. , Tiribocchi A.
Published: May 2011

Phase separation in a complex fluid with lamellar order has been studied in the case of cold thermal fronts propagating diffusively from external walls. The velocity hydrodynamic modes are taken into account by coupling the convection–diffusion equation for the order parameter to a generalized Navier–Stokes equation. The dynamical equations are simulated by implementing a hybrid method based on a lattice Boltzmann algorithm coupled to finite difference schemes. Simulations show that the ordering process occurs with morphologies depending on the speed of the thermal fronts or, equivalently, on the value of the thermal conductivityξ. At large values ofξ, as in instantaneous quenching, the system is frozen in entangled configurations at high viscosity while it consists of grains with well-ordered lamellae at low viscosity. By decreasing the value ofξ, a regime with very ordered lamellae parallel to the thermal fronts is found. At very low values ofξthe preferred orientation is perpendicular to the walls ind=2, while perpendicular order is lost moving far from the walls ind=3.
Transient and asymptotic dispersion in confined sphere packings with cylindrical and non-cylindrical conduit geometries
Authors: Khirevich Siarhei , Höltzel Alexandra , Tallarek Ulrich
Published: May 2011

We study the time and length scales of hydrodynamic dispersion in confined monodisperse sphere packings as a function of the conduit geometry. By a modified Jodrey–Tory algorithm, we generated packings at a bed porosity (interstitial void fraction) ofε=0.40 in conduits with circular, rectangular, or semicircular cross section of area 100πd2p(wheredpis the sphere diameter) and dimensions of about 20dp(cylinder diameter) by 6553.6dp(length), 25dpby 12.5dp(rectangle sides) by 8192dpor 14.1dp(radius of semicircle) by 8192dp, respectively. The fluid-flow velocity field in the generated packings was calculated by the lattice Boltzmann method for Péclet numbers of up to 500, and convective–diffusive mass transport of 4×106inert tracers was modelled with a random-walk particle-tracking technique. We present lateral porosity and velocity distributions for all packings and monitor the time evolution of longitudinal dispersion up to the asymptotic (long-time) limit. The characteristic length scales for asymptotic behaviour are explained from the symmetry of each conduit’s velocity field. Finally, we quantify the influence of the confinement and of a specific conduit geometry on the velocity dependence of the asymptotic dispersion coefficients.
Constrained simulations of flow in haemodynamic devices: towards a computational assistance of magnetic resonance imaging measurements
Authors: Cenova Iva , Kauzlarić David , Greiner Andreas , Korvink Jan G.
Published: May 2011

Cardiovascular diseases, mostly related to atherosclerosis, are the major cause of death in industrial countries. It is observed that blood flow dynamics play an important role in the aetiology of atherosclerosis. Especially, the blood velocity distribution is an important indicator for predisposition regions. Today magnetic resonance imaging (MRI) delivers, in addition to the morphology of the cardiovascular system, blood flow patterns. However, the spatial resolution of the data is slightly less than 1 mm and owing to severe restrictions in magnetic field gradient switching frequencies and intensities, this limit will be very hard to overcome. In this paper, constrained fluid dynamics is applied within the smoothed particle hydrodynamics formalism to enhance the MRI flow data. On the one hand, constraints based on the known volumetric flow rate are applied. They prove the plausibility of the order of magnitude of the measurements. On the other hand, the higher resolution of the simulation allows one to determine in detail the flow field between the coarse data points and thus to improve their spatial resolution.
Anisotropic imbibition on surfaces patterned with polygonal posts
Authors: Blow M. L. , Yeomans J. M.
Published: May 2011

We present and interpret lattice Boltzmann simulations of thick films spreading on surfaces patterned with polygonal posts. We show that the mechanism of pinning and depinning differs with the direction of advance, and demonstrate that this leads to anisotropic spreading within a certain range of material contact angles.
Numerical simulations of the behaviour of a drop in a square pipe flow using the two-phase lattice Boltzmann method
Authors: Kataoka Yuta , Inamuro Takaji
Published: May 2011

The lattice Boltzmann method for multi-component immiscible fluids is applied to simulations of the behaviour of a drop in a square pipe flow for various Reynolds numbers of 10<
Re
<500, Weber numbers of 0<
We
<250 and viscosity ratios of
η
=1/5, 1, 2 and 5. It is found that, for low Weber numbers, the drop moves straight along a stable position on the diagonal line of the pipe section, and it moves along the centre axis of the pipe for larger Weber numbers. We obtain the boundary of the two different behaviours of the drop in terms of Reynolds number, Weber number and viscosity ratio.
Influence of walls on the migration of non-Brownian spherical particles in creeping flow: a lattice Boltzmann study
Authors: Monaco Ernesto , Brenner Gunther
Published: May 2011

The influence of walls on binary encounters of spherical particles under creeping flow is studied by means of the lattice Boltzmann method. Depending on the initial particle displacement different behaviours can be observed, including the ‘swapping’ trajectories. The domain of the swapping trajectories is identified for interacting spheres with the same diameter; some preliminary results are given for the case of two spheres with different diameters. Finally, the influence of particle swapping on the dynamics of monodisperse suspensions is also described.
Flavobacterium yonginense sp. nov. and Flavobacterium myungsuense sp. nov., isolated from a mesotrophic artificial lake
Authors: Joung Yochan , Kim Haneul , Ahn Tae-Seok , Joh Kiseong
Published: May 2011

Two non-motile, Gram-staining-negative, yellow-pigmented bacterial strains designated HMD1001T and HMD1033T were isolated from the water of a mesotrophic artificial lake in Korea. A phylogenetic tree based on 16S rRNA gene sequences indicated that both strains could be assigned to the genus

Flavobacterium

; strain HMD1001T appeared most closely related to

Flavobacterium fluvii

H7T (96.8 % sequence similarity),

F. succinicans

DSM 4002T (96.6 %) and

F. hydatis

DSM 2063T (96.6 %) whereas strain HMD1033T appeared most closely related to

Flavobacterium psychrolimnae

LMG 2201T (96.2 %),

F. segetis

AT1048T (96.2 %) and

F. weaverense

AT1042T (96.2 %). The major fatty acids of strain HMD1001T were iso-C15 : 0 (21.5 %), summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c; 18.0 %) and iso-C15 : 1 G (7.6 %), whereas those of HMD1033T were summed feature 3 (23.8 %), iso-C15 : 0 3-OH (16.9 %), iso-C15 : 0 (15.3 %) and anteiso-C15 : 0 (12.1 %). The genomic DNA G+C contents of strains HMD1001T and HMD1033T were 35.9 and 32.2 mol%, respectively. Phylogenetic and phenotypic evidence indicates that strains HMD1001T and HMD1033T represent two novel species of the genus

Flavobacterium

, for which the names Flavobacterium yonginense sp. nov. (type strain HMD1001T  = KCTC 22796T  = CECT 7594T) and Flavobacterium myungsuense sp. nov. (type strain HMD1033T  = KCTC 22825T  = CECT 7649T) are proposed.
Microbacterium

yannicii sp. nov., isolated from Arabidopsis thaliana roots
Authors: Karojet Silke , Kunz Sabine , van Dongen Joost T.
Published: May 2011

Bacterial strain G72T was isolated from surface-sterilized roots of Arabidopsis thaliana growing in its natural habitat. This Gram-positive, rod-shaped, non-motile, microaerophilic and aerobically growing isolate was characterized by using a polyphasic approach. On the basis of 16S rRNA gene sequence similarity, strain G72T belongs to the genus

Microbacterium

. However, reassociation values in a DNA–DNA hybridization analysis with closely related strains were between 45.1  and 15.9 %. The DNA G+C content was 70.1 mol%. Strain G72T possessed a peptidoglycan type based on B2β with partial substitution of glutamic acid by 3-hydroxy glutamic acid (Glu/Hyg–Gly–d-Orn). The isolate contained MK-13, MK-12 and MK-11 as major respiratory quinones and anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0 as predominant fatty acids. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and three unidentified glycolipids. Based on its physiological and biochemical traits, as well as genotypic results, strain G72T is considered to represent a novel species, for which the name

Microbacterium

yannicii sp. nov. is proposed. The type strain is G72T ( = DSM 23203T  = LMG 25521T).
Chryseobacterium vietnamense sp. nov., isolated from forest soil
Authors: Li Zhikun , Zhu Honghui
Published: May 2011

A Gram-reaction-negative bacterial strain, designated GIMN1.005T, was isolated from a forest soil sample in Vietnam. The isolate was yellow-pigmented, strictly aerobic, and unable to grow below 5 °C or above 37 °C and in the presence of more than 2.0 % NaCl. Cells were non-motile, non-gliding and non-spore-forming. The yellow pigment was of the flexirubin type, non-diffusible and non-fluorescent. Analysis of 16S rRNA gene sequences showed that strain GIMN1.005T occupied a distinct lineage within the genus
Chryseobacterium
, with sequence similarity values of 98.6, 98.5 and 98.3 % to
Chryseobacterium aquifrigidense
KCTC 12894T,
Chryseobacterium jejuense
KACC 12501T and
Chryseobacterium indologenes
GIFU 1347T, respectively. The level of DNA–DNA relatedness between strain GIMN1.005T and
C. jejuense
KACC 12501T was <30 %. The DNA G+C content of strain GIMN1.005T was 42.1 mol%. The predominant cellular fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c); menaquinone 6 (MK-6) was the sole respiratory quinone. On the basis of phenotypic properties and phylogenetic distinctiveness, strain GIMN1.005T is considered to represent a novel species of the genus
Chryseobacterium
, for which the name Chryseobacterium vietnamense sp. nov. is proposed. The type strain is GIMN1.005T ( = CCTCC M 209230T = NRRL B-59550T).