bluuebunny/crossref_metadata_2025 huggingface dataset:
Importance of N-terminal pro-brain natriuretic peptide in monitoring acute rheumatic carditis
Authors: Esen Feyza , Argun Mustafa , Pamukçu Özge , Ozyurt Abdullah , Baykan Ali , Sezer Sadettin , Baykan Zeynep , Uzum Kazım , Narin Nazmi
Published: October 2013

Purpose

To detect the relationship of N-terminal pro-brain natriuretic peptide levels with clinical and laboratory findings by measuring them at diagnosis, during, and after treatment in children with acute rheumatic carditis.

Method

A total of 40 children including 20 acute rheumatic carditis patients aged between 5 and 16 years 20 healthy children as controls were included in the study. Blood was drawn from patients at diagnosis and in the first week, first month and third month after treatment in order to detect pro-brain natriuretic peptide, C-reactive protein levels and erythrocyte sedimentation rates. All patients underwent echocardiography.

Results

The N-terminal pro-brain natriuretic peptide levels of children with acute rheumatic carditis were significantly higher than those of the control group at diagnosis and during treatment (p<0.05). Echocardiographic evaluation of acute rheumatic carditis patients revealed that the left atrium diameter continued to decrease during the study and that the mean left atrium diameters measured at diagnosis and in the first week were statistically higher than the mean left atrium diameters measured in the third month. There was significant correlation between left atrium diameters at diagnosis and in the first month and N-terminal pro-brain natriuretic peptide levels during the same periods in the patient group.

Conclusion

Previous studies have used N-terminal pro-brain natriuretic peptide levels as a marker of enlargement of the left atrium, whereas in this study we want to emphasise its role as a marker of inflammation. This increase was significantly correlated with enlargement in the left atrium. N-terminal pro-brain natriuretic peptide levels were found to be a valuable determinant in indicating cardiac inflammation and haemodynamics.
Recurrent Medical Response Problems during Five Recent Disasters in the Netherlands
Authors: Juffermans Jorine , Bierens Joost J.L.M.
Published: October 2013

Objectives::

The aim of this qualitative, retrospective review is to identify and analyze the occurrence of recurrent problems in 20 processes that cover all relevant aspects of disaster health during the response phase. Consequently, an attempt is made to determine if there are generic themes of coherences in these problems.

Methods::

Eight after-action reports of five consecutive disasters in the Netherlands, between 1996 and 2005, were integrally analyzed in a structured manner. The analysis was confined to processes from the start of the event up to and including the initial stages of hospital admission.

Results::

Problems during all five disasters arose with eight processes: (1) submission of information to the ambulance dispatch center (ADC); (2) provision of information by the ADC to disaster response personnel; (3) scaling-up of prehospital response; (4) communication; (5) logistics; (6) registration; (7) multidisciplinary cooperation; and (8) preparation. Three generic themes of coherence were identified: (1) processes in which exchange of information among medical personal plays a major role are more likely to be affected by problems than processes in which this is less relevant; (2) processes in which disaster circumstances differ from day-to-day health care, or do not figure in day-to-day health care, are more likely to give rise to problems than processes that remain essentially similar; and (3) the existence of a protocol or disaster plan governing a process does not prevent problems.

Conclusions::

The method used enables a systematic analysis of the problems in health-related processes following five consecutive disasters. The analysis confirms that the majority of problems are repeated. The identified themes of coherences are in agreement with case reports and expert opinions. They are now supported with a higher level of evidence.
Associations between the purchase of healthy and fast foods and restrictions to food access: a cross-sectional study in Melbourne, Australia
Authors: Burns Cate , Bentley Rebecca , Thornton Lukar , Kavanagh Anne
Published: October 2013

Objective

To examine the associations between financial, physical and transport conditions that may restrict food access (which we define as food security indicators) and the purchase of fast foods and nutritious staples such as bread and milk.

Design

Multilevel logistic and multinomial regression analysis of cross-sectional survey data to assess associations between the three indicators of food insecurity and household food shopping adjusted for sociodemographic and socio-economic variables.

Setting

Random selection of households (n3995) from fifty Census Collector Districts in Melbourne, Australia, in 2003.

Subjects

The main food shoppers in each household (n2564).

Results

After adjustment for confounders, analysis showed that a greater likelihood of purchasing chain-brand fast food on a weekly basis compared with never was associated with running out of money to buy food (OR = 1·59; 95 % CI 1·08, 2·34) and reporting difficulties lifting groceries (OR = 1·77; 95 % CI 1·23, 2·54). Respondents without regular access to a car to do food shopping were less likely to purchase bread types considered more nutritious than white bread (OR = 0·75; 95 % CI 0·59, 0·95) and milk types considered more nutritious than full-cream milk (OR = 0·62; 95 % CI 0·47, 0·81). The food insecurity indicators were not associated with the purchasing of fruits, vegetables or non-chain fast food.

Conclusions

Householders experiencing financial and physical barriers were more likely to frequently purchase chain fast foods while limited access to a car resulted in a lower likelihood that the nutritious options were purchased for two core food items (bread and milk). Policies and interventions that improve financial access to food and lessen the effect of physical limitations to carrying groceries may reduce the purchasing of fast foods. Further research is required on food sourcing and dietary quality among those with food access restrictions.
Inadequate calcium intake is highly prevalent in Korean children and adolescents: the Korea National Health and Nutrition Examination Survey (KNHANES) 2007–2010
Authors: Im Jong Geun , Kim Shin Hye , Lee Gyeong-yoon , Joung Hyojee , Park Mi-Jung
Published: October 2013

Objective

The present study aimed to assess the adequacy of Ca intake and major food sources of Ca in Korean children and adolescents.

Design

A cross-sectional study.

Setting

Data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2007–2010. We analysed the daily Ca intake, major food sources of Ca and the prevalence of inadequate Ca intake in the study population. Ca intake was categorized as inadequate when the participant's daily Ca intake was less than the Estimated Average Requirement.

Subject

The study population consisted of 7233 children and adolescents (3973 boys, 3260 girls; aged 1–18 years).

Results

Mean Ca intake was 510·2 mg/d in boys and 431·7 mg/d in girls. Overall, 75·0 % of adolescents (boys 71·6 %, girls 79·1 %) had inadequate Ca intake. The prevalence of inadequate Ca intake increased significantly from toddlers (45–55 %) to adolescents (78–86 %) in both genders. The highest ranked food sources for Ca were dairy products (35·0 %), followed by vegetables (17·3 %), grains (11·3 %) and seafood (9·9 %). Ca intake from dairy products decreased significantly from 57 % in toddlers to 30 % in adolescents, while Ca intakes from other foods increased with age.

Conclusions

Inadequate Ca intake is highly prevalent and increased with age in Korean children and adolescents. It should be emphasized to encourage children and adolescents to eat more Ca-rich products to meet their Ca needs.
Structural and Spectroscopic Properties of MgTi2O5 / MgTiO3 Composite by Solid State Technique
Authors: Izci E.
Published: October 2013

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
Work Function Maps and Surface Topography Characterization of Nitroaromatic-Ended Dendron Films on Graphite
Authors: Farías Eliana D. , Brunetti Verónica , Paez Julieta I. , Strumia Miriam C. , Passeggi Mario C.G. , Ferrón Julio
Published: October 2013

Surface topography and work function maps were simultaneously obtained for carbon surfaces modified by a dendritic molecule: 3,5-Bis (3,5-dinitrobenzoylamino) benzoic acid. The dendrons were spontaneously assembled onto highly ordered pyrolytic graphite samples, exhibiting an increase in the surface potential. This fact is consistent with the incorporation of an electron-acceptor functional group that remains electroactive on the surface.
Children who develop type 1 diabetes early in life show low levels of carnitine and amino acids at birth: does this finding shed light on the etiopathogenesis of the disease?
Authors: la Marca G , Malvagia S , Toni S , Piccini B , Di Ciommo V , Bottazzo G F
Published: October 2013

Background:

Children and adolescents with overt type 1 diabetes (T1D) have been found to show an altered carnitine profile. This pattern has not previously been analyzed in neonates before onset of the disease.

Materials and methods:

Fifty children who developed T1D during the first 6 years of life, born and living in the Tuscany and Umbria Regions of Italy, were identified and 200 controls were recruited into the study. All newborns were subjected to extended neonatal screening by mass spectrometry at 48–72 h of life. Four controls for each of the 50 index cases were taken randomly and blinded in the same analytical batch. The panel used for neonatal screening consists of 13 amino acids, free carnitine, 33 acyl-carnitines and 21 ratios. All Guthrie cards are analyzed within 2 days of collection.

Results:

Total and free carnitine were found to be significantly lower in neonates who later developed T1D compared with controls. Moreover, the concentrations of the acyl-carnitines – acetyl-L-carnitine (C2), proprionylcarnitine (C3), 3-hydroxyisovalerylcarnitine (C5OH), miristoylcarnitine (C4), palmitoylcarnitine (C16) and stearoylcarnitine (C18) – were also significantly low in the cases vs controls. Furthermore, total amino-acid concentrations, expressed as the algebraic sum of all amino acids tested, showed a trend toward lower levels in cases vs controls.

Conclusions:

We found that carnitine and amino-acid deficit may be evident before the clinical appearance of T1D, possibly from birth. The evaluation of these metabolites in the neonatal period of children human leukocyte antigen genetically at ‘risk’ to develop T1D, could represent an additional tool for the prediction of T1D and could also offer the possibility to design new strategies for the primary prevention of the disease from birth.
Family-wide characterization of matrix metalloproteinases from Arabidopsis thaliana reveals their distinct proteolytic activity and cleavage site specificity
Authors: Marino Giada , Huesgen Pitter F. , Eckhard Ulrich , Overall Christopher M. , Schröder Wolfgang P. , Funk Christiane
Published: October 2013

MMPs (matrix metalloproteases) are a family of zinc-dependent endopeptidases widely distributed throughout all kingdoms of life. In mammals, MMPs play key roles in many physiological and pathological processes, including remodelling of the extracellular matrix. In the genome of the annual plant Arabidopsis thaliana, five MMP-like proteins (At-MMPs) are encoded, but their function is unknown. Previous work on these enzymes was limited to gene expression analysis, and so far proteolytic activity has been shown only for At1-MMP. We expressed and purified the catalytic domains of all five At-MMPs as His-tagged proteins in Escherichia coli cells to delineate the biochemical differences and similarities among the Arabidopsis MMP family members. We demonstrate that all five recombinant At-MMPs are active proteases with distinct preferences for different protease substrates. Furthermore, we performed a family-wide characterization of their biochemical properties and highlight similarities and differences in their cleavage site specificities as well as pH- and temperature-dependent activities. Detailed analysis of their sequence specificity using PICS (proteomic identification of protease cleavage sites) revealed profiles similar to human MMPs with the exception of At5-MMP; homology models of the At-MMP catalytic domains supported these results. Our results suggest that each At-MMP may be involved in different proteolytic processes during plant growth and development.
Effects of Hall current and electron temperature anisotropy on proton fire-hose instabilities
Authors: Hau L.-N. , Wang B.-J.
Published: October 2013

The standard magnetohydrodynamic (MHD) theory predicts that the Alfvén wave may become fire-hose unstable for β∥−β⊥>2. In this study, we examine the proton fire-hose instability (FHI) based on the gyrotropic two-fluid model, which incorporates the ion inertial effects arising from the Hall current and electron temperature anisotropy but neglects the electron inertia in the generalized Ohm's law. The linear dispersion relation is derived and analyzed which in the long wavelength approximation, λik→0 or αe=μ0(p∥,e−p⊥,e)/B2=1, recovers the ideal MHD model with separate temperature for ions and electrons. Here, λi is the ion inertial length and k is the wave number. For parallel propagation, both ion cyclotron and whistler waves become propagating and growing for β∥−β⊥>2+λi2k2(αe−1)2/2. For oblique propagation, the necessary condition for FHI remains to be β∥−β⊥>2 and there exist one or two unstable fire-hose modes, which can be propagating and growing or purely growing. For large λik values, there exists no nearly parallel FHI leaving only oblique FHI and the effect of αe>1 may greatly enhance the growth rate of parallel and oblique FHI. The magnetic field polarization of FHI may be reversed due to the sign change associated with (αe−1) and the purely growing FHI may possess linear polarization while the propagating and growing FHI may possess right-handed or left-handed polarization.
Coherent-control of linear signals: Frequency-domain analysis
Authors: Mukamel Shaul
Published: October 2013

The dependence of various types of linear signals on the phase profile of broadband optical pulses is examined using fundamental time translation invariance symmetry of multipoint correlation functions. The frequency-domain wave-mixing analysis presented here unifies several arguments made earlier with respect to the conditions whereby coherent control schemes may be used.
Simple, green, and clean removal of a poly(methyl methacrylate) film on chemical vapor deposited graphene
Authors: Park J.-H. , Jung W. , Cho D. , Seo J.-T. , Moon Y. , Woo S. H. , Lee C. , Park C.-Y. , Ahn J. R.
Published: October 2013

The clean removal of a poly(methyl methacrylate) (PMMA) film on graphene has been an essential part of the process of transferring chemical vapor deposited graphene to a specific substrate, influencing the quality of the transferred graphene. Here we demonstrate that the clean removal of PMMA can be achieved by a single heat-treatment process without the chemical treatment that was adopted in other methods of PMMA removal. The cleanness of the transferred graphene was confirmed by four-point probe measurements, synchrotron radiation x-ray photoemission spectroscopy, optical images, and Raman spectroscopy.
Effects of injection on the instability of boundary layers over hypersonic configurations
Authors: Li Fei , Choudhari Meelan , Chang Chau-Lyan , White Jeffery
Published: October 2013

Computations are performed to study the boundary layer instability mechanisms pertaining to hypersonic vehicles with significant ablative effects. The process of laminar-turbulent transition over vehicles with ablative heat shields can be influenced by both the out-gassing associated with surface pyrolysis and the resulting modification of surface geometry including the formation of micro-roughness. To isolate the effects of out-gassing, this paper examines the stability of canonical boundary layer flows over smooth surfaces in the presence of gas injection into the boundary layer, with an emphasis on the case of massive injection that is relevant to previous laboratory experiments. For a slender cone, the effects of strong out-gassing on the predominantly second mode instability are found to be weakly stabilizing. This new, somewhat surprising result is confirmed by computations carried out on a flat plate boundary layer at high Mach numbers. In contrast, for a blunt capsule flow dominated by first mode instability, the effect of out-gassing is shown to be strongly destabilizing, consistent with the well-known behavior of subsonic boundary layers.
Electron acceleration in cavitated laser produced ion channels
Authors: Naseri N. , Pesme D. , Rozmus W.
Published: October 2013

This paper is concerned with the channeling of a relativistic laser pulse in an underdense plasma and with the subsequent generation of fast electrons in the cavitated ion channel. The laser pulse has a duration of several hundreds of femtoseconds and its power PL exceeds the critical power for laser channeling Pch, with Pch≈1.1Pc, Pc denoting the critical power for relativistic self-focusing. The laser pulse is focused in a plasma of electron density n0 such that the ratio n0/nc lies in the interval [10−3,10−1], nc denoting the critical density. The laser-plasma interaction under such conditions is investigated by means of three dimensional Particle-In-Cell (PIC) simulations. It is observed that the steep laser front gives rise to the excitation of a surface wave which propagates along the sharp radial boundaries of the electron free channel created by the laser pulse. The mechanism responsible for the generation of relativistic electrons observed in the PIC simulations is also analyzed by means of a test particles code. The fast electrons are found to be generated by the combination of a surface wave and of the betatron resonance. The maximum electron energy observed in the simulations is scaled as a function of PL/Pc; it reaches 350–600 MeV for PL/Pc = 70–140.
Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser-produced plasma ions acceleration
Authors: Sakaki H. , Nishiuchi M. , Maeda S. , Sagisaka A. , Pirozhkov A. S. , Pikuz T. , Faenov A. , Ogura K. , Fukami T. , Matsukawa K. , Kanasaki M. , Fukuda Y. , Yogo A. , Esirkepov T. , Kiriyama H. , Shimomura T. , Nakai Y. , Tanoue M. , Torimoto K. , Okamoto M. , Sato T. , Niita K. , Tamura J. , Nishio K. , Sako H. , Yamauchi T. , Watanabe Y. , Bulanov S. , Kondo K.
Published: October 2013

High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams, such as high-energy proton and ions with high charge to mass ratio (Q/M; same as multi-charged ions). Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity of 1 × 1021 W/cm2 on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR-39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System. The results obtained provide useful approach for analyzing the various laser based ion beams.
Anisotropic diffusion of concentrated hard-sphere colloids near a hard wall studied by evanescent wave dynamic light scattering
Authors: Michailidou V. N. , Swan J. W. , Brady J. F. , Petekidis G.
Published: October 2013

Evanescent wave dynamic light scattering and Stokesian dynamics simulations were employed to study the dynamics of hard-sphere colloidal particles near a hard wall in concentrated suspensions. The evanescent wave averaged short-time diffusion coefficients were determined from experimental correlation functions over a range of scattering wave vectors and penetration depths. Stokesian dynamics simulations performed for similar conditions allow a direct comparison of both the short-time self- and collective diffusivity. As seen earlier [V. N. Michailidou, G. Petekidis, J. W. Swan, and J. F. Brady, Phys. Rev. Lett. 102, 068302 (2009)] while the near wall dynamics in the dilute regime slow down compared to the free bulk diffusion, the reduction is negligible at higher volume fractions due to an interplay between the particle-wall and particle-particle hydrodynamic interactions. Here, we provide a comprehensive comparison between experiments and simulations and discuss the interplay of particle-wall and particle-particle hydrodynamics in the self- and cooperative dynamics determined at different scattering wave vectors and penetration depths.
The formation of turbulent vortex rings by synthetic jets
Authors: Lawson J. M. , Dawson J. R.
Published: October 2013

An investigation is made into the mechanism of pinch-off for turbulent vortex rings formed by a synthetic jet using time resolved particle image velocimetry measurements in air. During formation, measurements of the material acceleration field show a trailing pressure maximum (TPM) forms behind the vortex core. The adverse pressure gradient behind this TPM inhibits vorticity transport into the ring and the TPM is spatially coincident with the termination of vorticity flux into a control volume moving with the ring. A Lagrangian Coherent Structures (LCS) analysis is shown to be in agreement with the role of the TPM in pinch-off and in identifying the vortex ring before separation. The LCS analysis provides physical insights which form the basis of a revised model of pinch-off, based on kinematics, which predicts the time of formation (formation number) well for the present dataset. The delivery of impulse to the vortex ring is also considered. Two equally important mechanisms are shown to play a role: a material flux and a vortex force. In the case of long maximum stroke ratio, it is demonstrated that a vortex force continues to deliver impulse to the ring after the material flux is terminated at pinch-off and that this contribution may be substantial. This shows that the pinch-off and separation process cannot be considered impulse invariant, which has important implications for unsteady propulsion, present models of vortex ring formation, and existing explanations for vortex ring pinch-off.
Trkalian fields: ray transforms and mini-twistors
Authors: Saygili K.
Published: October 2013

We study X-ray and Divergent beam transforms of Trkalian fields and their relation with Radon transform. We make use of four basic mathematical methods of tomography due to Grangeat, Smith, Tuy, and Gelfand-Goncharov for an integral geometric view on them. We also make use of direct approaches which provide a faster but restricted view of the geometry of these transforms. These reduce to well known geometric integral transforms on a sphere of the Radon or the spherical Curl transform in Moses eigenbasis, which are the members of an analytic family of integral operators. We also discuss their inversion. The X-ray (also Divergent beam) transform of a Trkalian field is Trkalian. Also the Trkalian subclass of X-ray transforms yields Trkalian fields in the physical space. The Riesz potential of a Trkalian field is proportional to the field. Hence, the spherical mean of the X-ray (also Divergent beam) transform of a Trkalian field over all lines passing through a point yields the field at this point. The pivotal point is the simplification of an intricate quantity: Hilbert transform of the derivative of Radon transform for a Trkalian field in the Moses basis. We also define the X-ray transform of the Riesz potential (of order 2) and Biot-Savart integrals. Then, we discuss a mini-twistor representation, presenting a mini-twistor solution for the Trkalian fields equation. This is based on a time-harmonic reduction of wave equation to Helmholtz equation. A Trkalian field is given in terms of a null vector in $\mathbb {C}^{3}$C3 with an arbitrary function and an exponential factor resulting from this reduction.
The H + CO ⇌ HCO reaction studied by ab initio benchmark calculations
Authors: Peters Phillip S. , Duflot Denis , Wiesenfeld Laurent , Toubin Céline
Published: October 2013

The title reaction has been calculated using complete active space self-consistent field and internally contracted multi-reference configuration interaction, including Davidson correction, calculations. Dunning's correlation consistent atomic basis sets, together with several complete basis set extrapolation schemes, were employed. Core-valence and scalar relativistic effects were also taken into account, as well as anharmonicity of the vibrational modes. Core-valence correlation appears to have a large impact on the calculated frequencies, spectroscopic constants, and on the energetics. In particular, the best estimate for the HCO (DCO) formation barrier height at 0 K, 4.54 ± 0.14 (4.43 ± 0.14) kcal mol−1 is larger than previous theoretical works and well above the usually accepted value of 2.0 ± 0.4 kcal mol−1, measured at room temperature. Inclusion of temperature and entropy at 298 K does not seem to be able to solve this discrepancy. The present theoretical barrier height is therefore the recommended value. The exo-ergicity of the HCO (DCO) dissociation reaction, predicted to be −13.36 ± 0.57 (−14.72 ± 0.57) kcal mol−1, is slightly below the experimental value. Finally, all tested density functionals fail to reproduce accurately both the formation and dissociation barriers.
The liquid structure of tetrachloroethene: Molecular dynamics simulations and reverse Monte Carlo modeling with interatomic potentials
Authors: Gereben Orsolya , Pusztai László
Published: October 2013

The liquid structure of tetrachloroethene has been investigated on the basis of measured neutron and X-ray scattering structure factors, applying molecular dynamics simulations and reverse Monte Carlo (RMC) modeling with flexible molecules and interatomic potentials. As no complete all-atom force field parameter set could be found for this planar molecule, the closest matching all-atom Optimized Potentials for Liquid Simulations (OPLS-AA) intra-molecular parameter set was improved by equilibrium bond length and angle parameters coming from electron diffraction experiments [I. L. Karle and J. Karle, J. Chem. Phys. 20, 63 (1952)]. In addition, four different intra-molecular charge distribution sets were tried, so in total, eight different molecular dynamics simulations were performed. The best parameter set was selected by calculating the mean square difference between the calculated total structure factors and the corresponding experimental data. The best parameter set proved to be the one that uses the electron diffraction based intra-molecular parameters and the charges qC = 0.1 and qCl = −0.05. The structure was further successfully refined by applying RMC computer modeling with flexible molecules that were kept together by interatomic potentials. Correlation functions concerning the orientation of molecular axes and planes were also determined. They reveal that the molecules closest to each other exclusively prefer the parallel orientation of both the molecular axes and planes. Molecules forming the first maximum of the center-center distribution have a preference for <30° and >60° axis orientation and >60° molecular plane arrangement. A second coordination sphere at ∼11 Å and a very small third one at ∼16 Å can be found as well, without preference for any axis or plane orientation.
Low fragment polyatomic molecular ion source by using permanent magnets
Authors: Takeuchi Mitsuaki , Hayashi Kyouhei , Imanaka Kousuke , Ryuto Hiromichi , Takaoka Gikan H.
Published: October 2013

Electron-ionization-type polyatomic molecular ion source with low fragment was developed by using a pair of ring-shaped Sm-Co magnets. The magnets were placed forward and backward side of ionization part to confine electrons extracted from a thermionic cathode. Calculated electron trajectory of the developed ion source was 20 times longer than that of an ordinary outer filament configuration that has no magnetic confinement. Mass spectra of the molecular ions generated from n-tetradecane (C14H30) gas exhibited 4 times larger intensity than that of the ordinary configuration in a range of mass/charge from 93 to 210 u. This indicates that suppression of fragment ion was obtained by increase of low energy electrons resulted from the electron confinement.
Assessment and modification of an ion source grid design in KSTAR neutral beam system
Authors: Lee Dong Won , Shin Kyu In , Jin Hyung Gon , Guen Choi Bo , Kim Tae-Seong , Jeong Seung Ho
Published: October 2013

A new 2 MW NB (Neutral Beam) ion source for supplying 3.5 MW NB heating for the KSTAR campaign was developed in 2012 and its grid was made from OFHC (Oxygen Free High Conductivity) copper with rectangular cooling channels. However, the plastic deformation such as a bulging in the plasma grid of the ion source was found during the overhaul period after the 2012 campaign. A thermal-hydraulic and a thermo-mechanical analysis using the conventional code, ANSYS, were carried out and the thermal fatigue life assessment was evaluated. It was found that the thermal fatigue life of the OFHC copper grid was about 335 cycles in case of 0.165 MW/m2 heat flux and it gave too short fatigue life to be used as a KSTAR NB ion source grid. To overcome the limited fatigue life of the current design, the following methods were proposed in the present study: (1) changing the OHFC copper to CuCrZr, copper-alloy or (2) adopting a new design with a pure Mo metal grid and CuCrZr tubes. It is confirmed that the proposed methods meet the requirements by performing the same assessment.
Diagnostics in a single element of a matrix source of negative hydrogen ions
Authors: Lishev St. , Yordanov D. , Shivarova A.
Published: October 2013

A small radius discharge in hydrogen inductively driven by a planar coil is studied experimentally regarding development of a matrix source of negative hydrogen ions: a matrix of small radius discharges, each of them completed with a magnetic filter and a single aperture extraction device. Probe and laser photodetachment diagnostics are the methods employed. Results for the axial structure of the discharge show the influence of the absorbed rf power, of the magnetic filter (and its position), and of the bias applied to the first electrode of the extraction device on the spatial distribution of the plasma parameters and on the discharge modes.
Observed asymptotic differences in energies of stable and minimal point configurations on $\mathbb {S}^2$S2 and the role of defects
Authors: Calef M. , Griffiths W. , Schulz A. , Fichtl C. , Hardin D.
Published: October 2013

Configurations of N points on the two-sphere that are stable with respect to the Riesz s-energy have a structure that is largely hexagonal. These stable configurations differ from the configurations with the lowest reported N-point s-energy in the location and structure of defects within this hexagonal structure. These differences in energy between the stable and minimal configuration suggest that energy scale at which defects play a role. This work uses numerical experiments to report this difference as a function of N, allowing us to infer the energy scale at which defects play a role. This work is presented in the context of established estimates for the minimal N-point energy, and in particular we identify terms in these estimates that likely reflect defect structure.
A portable hydro-thermo-mechanical loading cell for in situ small angle neutron scattering studies of proton exchange membranes
Authors: Yu Dunji , An Ke , Gao Carrie Y. , Heller William T. , Chen Xu
Published: October 2013

A portable hydro-thermo-mechanical loading cell has been designed to enable in situ small angle neutron scattering (SANS) studies of proton exchange membranes (PEMs) under immersed tensile loadings at different temperatures. The cell consists of three main parts as follows: a letter-paper-size motor-driven mechanical load frame, a SANS friendly reservoir that provides stable immersed and thermal sample conditions, and a data acquisition and control system. The ex situ tensile tests of Nafion 212 membranes demonstrated a satisfactory thermo-mechanical testing performance of the cell for either dry or immersed conditions at elevated temperatures. The in situ SANS tensile measurements on the Nafion 212 membranes immersed in D2O at 70 °C proved the feasibility and capability of the cell for small angle scattering study on deformation behaviors of PEM and other polymer materials under hydro-thermo-mechanical loading.
The velocity operator in quantum mechanics in noncommutative space
Authors: Kováčik Samuel , Prešnajder Peter
Published: October 2013

We tested the consequences of noncommutative (NC from now on) coordinates xk, k = 1, 2, 3 in the framework of quantum mechanics. We restricted ourselves to 3D rotationally invariant NC configuration spaces with dynamics specified by the Hamiltonian \documentclass[12pt]{minimal}\begin{document}$\hat{H} = \hat{H}_0 + \hat{U}$\end{document}Ĥ=Ĥ0+Û, where \documentclass[12pt]{minimal}\begin{document}$\hat{H}_0$\end{document}Ĥ0 is an analogue of kinetic energy and \documentclass[12pt]{minimal}\begin{document}$\hat{U} = \hat{U}(\hat{r})$\end{document}Û=Û(r̂) denotes an arbitrary rotationally invariant potential. We introduced the velocity operator by \documentclass[12pt]{minimal}\begin{document}$\hat{V}_k = - i [\hat{X}_k, \hat{H}]$\end{document}V̂k=−i[X̂k,Ĥ] (\documentclass[12pt]{minimal}\begin{document}$\hat{X}_k$\end{document}X̂k being the position operator), which is a NC generalization of the usual gradient operator (multiplied by −i). We found that the NC velocity operators possess various general, independent of potential, properties: (1) uncertainty relations \documentclass[12pt]{minimal}\begin{document}$[\hat{V}_i,\hat{X}_j]$\end{document}[V̂i,X̂j] indicate an existence of a natural kinetic energy cut-off, (2) commutation relations \documentclass[12pt]{minimal}\begin{document}$[\hat{V}_i,\hat{V}_j] = 0$\end{document}[V̂i,V̂j]=0, which is non-trivial in the NC case, (3) relation between \documentclass[12pt]{minimal}\begin{document}$\hat{V}^2$\end{document}V̂2 and \documentclass[12pt]{minimal}\begin{document}$\hat{H}_0$\end{document}Ĥ0 that indicates the existence of maximal velocity and confirms the kinetic energy cut-off, (4) all these results sum up in canonical (general, not depending on a particular form of the central potential) commutation relations of Euclidean group E(4) = SO(4)▷T(4), (5) Heisenberg equation for the velocity operator, relating acceleration \documentclass[12pt]{minimal}\begin{document}$\dot{\hat{V}}_k = -i[\hat{V}_k, \hat{H}]$\end{document}V̂̇k=−i[V̂k,Ĥ] to derivatives of the potential.
The string equation and the τ-function Witt constraints for the discrete Kadomtsev-Petviashvili hierarchy
Authors: Liu Shaowei , Ma Wen-Xiu
Published: October 2013

Using the tool of pseudo-difference operators, the string equation for the discrete Kadomtsev-Petviashvili (KP) hierarchy is introduced and a general expression for the string equation is formulated. Furthermore, the operators of the constraints that the string equation imposes on the τ-function of the p-reduced dKP hierarchy are presented. The algebra, which part of the constraints spans, and eigenvalues of part of the constraints corresponding to the τ-function are calculated. It is also shown that this algebra is exactly a Witt algebra not only for p = 2, but also for a general \documentclass[12pt]{minimal}\begin{document}$p\in \mathbb {N}$\end{document}p∈N, and that the τ-function of the p-reduced dKP hierarchy constrained by the string equation is a vacuum vector of a Witt algebra.
Simple bound state energy spectra solutions of Dirac equation for Hulthén and Eckart potentials
Authors: Barakat T. , Abdalla M. Sebawe
Published: October 2013

Within the framework of simple similarity transformation method, we present simple Schrödinger-like equation for Dirac equation with Hulthén and Eckart Lorentz vectors potentials. Using the asymptotic iteration method we have managed to obtain the explicit analytical solution of the bound state energy spectra as well as the eigenfunctions for both potentials. Discussion related to the eigenfunction for both cases is also considered. We have shown that the wave function is sensitive for both potentials as well as the parameter δ.
Spin-dependent resonant tunneling of multiferroic tunnel junction via head-to-head 180° domain wall
Authors: Dai Jian-Qing , Zhang Hu , Song Yu-Min
Published: October 2013

The extraordinary properties of the two-dimensional electron gas (2DEG) at oxide heterostructure interface such as LaAlO3/SrTiO3 have attracted considerable investigations. Recent work suggested that the 2DEG could be formed within the SrTiO3 tunnel barrier by replacing the central TiO2 atomic layer with LaO, and that such a tunnel junction exhibits resonant tunneling behavior with new intriguing properties and potential applications [J. D. Burton et al., Phys. Rev. B 80, 115408 (2009)]. Here we investigate an alternative approach providing the resonant transmission of which a 180° head-to-head (HH) domain wall in the middle of the tunnel barrier induces the 2DEG via the free electronic carriers screening the polarization bound charges in situ. Using first-principles calculations on the Fe/PbTiO3/Fe as a model system, we show that this strategy allows for the formation of a 2DEG within the barrier, and that the remarkable difference between the majority- and minority-spin channels results in large tunneling magnetoresistance (TMR) effect. The resonant tunneling and the large TMR effect are beneficial to magnetic recording applications. We also discuss the feasibility to obtain such a 180° HH domain wall in the practical magnetic tunnel junctions and the influences of FeO formation at the iron-complex oxide interface on the electronic structure and tunneling properties.
From cognitive networks to seizures: Stimulus evoked dynamics in a coupled cortical network
Authors: Lee Jaejin , Ermentrout Bard , Bodner Mark
Published: October 2013

Epilepsy is one of the most common neuropathologies worldwide. Seizures arising in epilepsy or in seizure disorders are characterized generally by uncontrolled spread of excitation and electrical activity to a limited region or even over the entire cortex. While it is generally accepted that abnormal excessive firing and synchronization of neuron populations lead to seizures, little is known about the precise mechanisms underlying human epileptic seizures, the mechanisms of transitions from normal to paroxysmal activity, or about how seizures spread. Further complication arises in that seizures do not occur with a single type of dynamics but as many different phenotypes and genotypes with a range of patterns, synchronous oscillations, and time courses. The concept of preventing, terminating, or modulating seizures and/or paroxysmal activity through stimulation of brain has also received considerable attention. The ability of such stimulation to prevent or modulate such pathological activity may depend on identifiable parameters. In this work, firing rate networks with inhibitory and excitatory populations were modeled. Network parameters were chosen to model normal working memory behaviors. Two different models of cognitive activity were developed. The first model consists of a single network corresponding to a local area of the brain. The second incorporates two networks connected through sparser recurrent excitatory connectivity with transmission delays ranging from approximately 3 ms within local populations to 15 ms between populations residing in different cortical areas. The effect of excitatory stimulation to activate working memory behavior through selective persistent activation of populations is examined in the models, and the conditions and transition mechanisms through which that selective activation breaks down producing spreading paroxysmal activity and seizure states are characterized. Specifically, we determine critical parameters and architectural changes that produce the different seizure dynamics in the networks. This provides possible mechanisms for seizure generation. Because seizures arise as attractors in a multi-state system, the system may possibly be returned to its baseline state through some particular stimulation. The ability of stimulation to terminate seizure dynamics in the local and distributed models is studied. We systematically examine when this may occur and the form of the stimulation necessary for the range of seizure dynamics. In both the local and distributed network models, termination is possible for all seizure types observed by stimulation possessing some particular configuration of spatial and temporal characteristics.
Systematic theoretical studies of the interaction of 1,4-diazabicyclo [2.2.2]octane (DABCO) with rare gases
Authors: Mathivon Kevin , Linguerri Roberto , Hochlaf Majdi
Published: October 2013

We investigate the intermolecular 1,4-diazabicyclo [2.2.2] octane (DABCO) interaction potential with He, Ne, Ar, and Kr rare gases (Rg) by means of post Hartree-Fock and the newly implemented explicitly correlated coupled cluster approaches in connection with several basis sets. After benchmarking computations, we show that the inclusion of diffuse atomic orbitals is mandatory for the accurate description of structures, energetics, and spectroscopic properties of DABCO–Rg van der Waals clusters and that the (R)MP2/aug-cc-pVXZ (X = D, T) level is accurate enough for that purposes. For the neutral and ionic DABCO–Rg complexes, we characterized the low energy stationary points on the ground state potential. Most of the computed structures show a distortion along the low frequency mode of the van der Waals complex. Tunneling through this potential barrier leads to a splitting of the ground vibrational levels of several cm−1. Our results served to reassign the available experimental spectra for DABCO0,+1–Ar and DABCO0,+1–Kr.
Three body dissociation of ${\rm CS}_2^{2+}$CS22+ subsequent to various S(2p) Auger transitions
Authors: Saha K. , Banerjee S. B. , Bapat B.
Published: October 2013

Fragmentation kinematics of CS2 following various S(2p) Auger transitions is studied. Employing a combination of electron energy analysis and recoil ion momentum spectroscopy, changes in the dissociation channel yields, as well as the differences in the kinematical parameters for various bands of Auger hole states are presented. The fragmentation mechanism for dissociative channels leading to complete atomization of \documentclass[12pt]{minimal}\begin{document}${\rm CS}_2^{2+}$\end{document} CS 22+ molecular ion is studied in detail. We find that \documentclass[12pt]{minimal}\begin{document}${\rm CS}_2^{2+}$\end{document} CS 22+ does not retain linear geometry and is bent before undergoing concerted break-up. It is also observed that different geometric configurations of the \documentclass[12pt]{minimal}\begin{document}${\rm CS}_2^{2+}$\end{document} CS 22+ precursor result in different kinetic energy release values.
Rotating shallow water turbulence: Experiments with altimetry
Authors: Afanasyev Y. D. , Craig J. D. C.
Published: October 2013

Results from a new series of experiments on turbulent flows in a rotating circular container are presented. Electromagnetic forcing is applied to induce flow in a layer of fluid of constant depth. Continuously forced and decaying flows are investigated. Optical altimetry is used to measure the gradient of the surface elevation field and to obtain the velocity and vorticity fields with high temporal and spatial resolution. Spectral analysis of the flows demonstrates the formation of dual cascade with energy and enstrophy intervals although the corresponding spectral fluxes of energy and enstrophy are not uniform in these intervals. The energy interval is characterized by the slope of ∼−5/3 in terms of wavenumber and is limited in extent by the finite radius of deformation effect. In the enstrophy range, the slope is steeper than −3 due to the presence of long-lived coherent vortices. The spatial patterns of fluxes to large or small scales in the flow indicate that inverse energy transfer and direct enstrophy transfer occur mainly in elongated vorticity patches. Cyclone/anticyclone asymmetry in favor of anticyclones is observed in our flows. Dominance of anticyclones is most clear during the decay phase of turbulence. The anticyclones remain circular, while cyclonic vorticity is stretched into elongated patches. Measurements show that skewness of vorticity distribution increases with increasing Froude number of the flow.
Time resolved optical diagnostics of ZnO plasma plumes in air
Authors: Gupta Shyam L. , Singh Ravi Pratap , Thareja Raj K.
Published: October 2013

We report dynamical evolution of laser ablated ZnO plasma plumes using interferometry and shadowgraphy; 2-D fast imaging and optical emission spectroscopy in air ambient at atmospheric pressure. Recorded interferograms using Nomarski interferometer and shadowgram images at various time delays show the presence of electrons and neutrals in the ablated plumes. The inference drawn from sign change of fringe shifts is consistent with two dimensional images of the plume and optical emission spectra at varying time delays with respect to ablating pulse. Zinc oxide plasma plumes are created by focusing 1.06 μm radiation on to ZnO target in air and 532 nm is used as probe beam.
Standard-resistor compounds with adjustable operating temperature
Authors: Oe T. , Urano C. , Kaneko N. , Hadano M. , Takenaka K.
Published: October 2013

The broad peak of the temperature-resistivity curve ρ(T) in antiperovskite Mn3AgN can potentially be used to develop materials with temperature coefficients of resistance as low as that of the widely used standard-resistor material Manganin. By partially replacing Ag by In or Mn by Fe, we suppressed the peak height of ρ(T) in Mn3AgN to levels that in some cases were lower than that of Manganin, and by co-doping with Cu and In or Fe, the peak temperature could be controlled over a temperature width of at least 50 K around room temperature while retaining the broadness of ρ(T) curve.
Comment on “Comparative analysis of glass-formation in binary, ternary, and multicomponent alloys” [J. Appl. Phys. 108, 103511 (2010)]
Authors: Luo L. J. , Dong C.
Published: October 2013

Best ternary bulk metallic glass formers A44B38C18, A44B43C13, A65B25C10, A56B32C12, A55B28C17, A70B20C10, and A65B20C15 are quantitatively explained using the cluster-plus-glue-atom model.