bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of a school-based intervention on adherence of 7–9-year-olds to food-based dietary guidelines and intake of nutrients
Authors: Kristjansdottir Asa G , Johannsson Erlingur , Thorsdottir Inga
Published: April 2010

Objective

To assess the effects of a school-based intervention on the diets of 7–9-year-olds.

Design

Dietary intake of children in second and fourth grades was assessed with 3d weighed dietary records in autumn 2006 and autumn 2008, before and after a school-based intervention that started in the middle of second grade, and compared with control schools with no intervention. The diet was evaluated by comparison with food-based dietary guidelines (FBDG) and reference values for nutrient intake. The intervention aimed at several determinants of intake: knowledge, awareness, preferences/taste, self-efficacy and parental influence. Nutrition education material was developed for the intervention and implemented in collaboration with teachers. The main focus of the intervention was on fruit and vegetable intake as the children’s intake was far from meeting the FBDG on fruit and vegetables at baseline.

Setting

Elementary schools in Reykjavik, Iceland.

Subjects

Complete dietary records were available for 106 children both at baseline and follow-up.

Results

Total fruit and vegetable intake increased by 47 % in the intervention schools (mean: 61·3 (sd126·4) g/d) and decreased by 27 % in the control schools (mean: 46·5 (sd105·3) g/d;P< 0·001). The majority of the children in the intervention schools did still not meet the FBDG on fruits and vegetables at follow-up. Fibre intake increased significantly in the intervention schools, as well as that of potassium, magnesium, β-carotene and vitamin C (borderline).

Conclusions

The school-based intervention in 7–9-year-olds was effective in increasing fruit and vegetable intake, by 47 % increase from baseline, which was mirrored in nutrient intake.
Neutron production in terrestrial gamma ray flashes
Authors: Carlson B. E. , Lehtinen N. G. , Inan U. S.
Published: April 2010

Terrestrial gamma ray flashes (TGFs) are brief bursts of photons with energies up to 20 MeV typically observed in association with lightning. Such energetic photons may undergo photonuclear reactions with nontrivial cross section in the vicinity of the giant dipole resonance. Pulses of neutrons have been observed experimentally in coincidence with lightning, suggesting such reactions are observable. We present simulations of expected photoneutron production based on initial conditions inferred from observations of TGFs. We predict an average of ∼1012 neutrons produced per TGF and give energy, time, and space distributions of neutrons produced and neutrons reaching ground and satellite altitude. The simulation results are consistent with some observations and suggest further experiments may be profitable.
The 2007 Stromboli eruption: Event chronology and effusion rates using thermal infrared data
Authors: Calvari S. , Lodato L. , Steffke A. , Cristaldi A. , Harris A. J. L. , Spampinato L. , Boschi E.
Published: April 2010

Using thermal infrared images recorded by a permanent thermal camera network maintained on Stromboli volcano (Italy), together with satellite and helicopter‐based thermal image surveys, we have compiled a chronology of the events and processes occurring before and during Stromboli's 2007 effusive eruption. These digital data also allow us to calculate the effusion rates and lava volumes erupted during the effusive episode. At the onset of the 2007 eruption, two parallel eruptive fissures developed within the northeast crater, eventually breaching the NE flank of the summit cone and extending along the eastern margin of the Sciara del Fuoco. These fed a main effusive vent at 400 m above sea level to feed lava flows that extended to the sea. The effusive eruption was punctuated, on 15 March, by a paroxysm with features similar to those of the 5 April paroxysm that occurred during the 2002–2003 effusive eruption. A total of between 3.2 × 106 and 11 × 106 m3 of lava was erupted during the 2007 eruption, over 34 days of effusive activity. More than half of this volume was emplaced during the first 5.5 days of the eruption. Although the 2007 effusive eruption had an erupted volume comparable to that of the previous (2002–2003) effusive eruption, it had a shorter duration and thus a mean output rate (=total volume divided by eruption duration) that was 1 order of magnitude higher than that of the 2002–2003 event (∼2.4 versus 0.32 ± 0.28 m3 s−1). In this paper, we discuss similarities and differences between these two effusive events and interpret the processes occurring in 2007 in terms of the recent dynamics witnessed at Stromboli.
Observation of infrasonic and gravity waves at Soufrière Hills Volcano, Montserrat
Authors: Ripepe Maurizio , De Angelis Silvio , Lacanna Giorgio , Voight Barry
Published: April 2010

The sudden ejection of material during an explosive eruption generates a broad spectrum of pressure oscillations, from infrasonic to gravity waves. An infrasonic array, installed at 3.5 km from the Soufriere Hills Volcano has successfully detected and located, in real‐time, the infrasound generated by several pyroclastic flows (PF) estimating mean flow speeds of 30–75 m/s. On July 29 and December 3, 2008, two differential pressure transducers, co‐located with the array, recorded ultra long‐period (ULP) oscillations at frequencies of 0.97 and 3.5 mHz, typical of atmospheric gravity waves, associated with explosive eruptions. The observation of gravity waves in the near‐field (<6 km) at frequencies as low as about 1 mHz is unprecedented during volcanic eruptions.
Phylogenetic diversity and community structure of anaerobic gut fungi (phylum Neocallimastigomycota) in ruminant and non-ruminant herbivores
Authors: Liggenstoffer Audra S , Youssef Noha H , Couger M B , Elshahed Mostafa S
Published: April 2010

The phylogenetic diversity and community structure of members of the gut anaerobic fungi (AF) (phylum Neocallimastigomycota) were investigated in 30 different herbivore species that belong to 10 different mammalian and reptilian families using the internal transcribed spacer region-1 (ITS-1) ribosomal RNA (rRNA) region as a phylogenetic marker. A total of 267 287 sequences representing all known anaerobic fungal genera were obtained in this study. Sequences affiliated with the genus Piromyces were the most abundant, being encountered in 28 different samples, and representing 36% of the sequences obtained. On the other hand, sequences affiliated with the genera Cyllamyces and Orpinomyces were the least abundant, being encountered in 2, and 8 samples, and representing 0.7%, and 1.1% of the total sequences obtained, respectively. Further, 38.3% of the sequences obtained did not cluster with previously identified genera and formed eight phylogenetically distinct novel anaerobic fungal lineages. Some of these novel lineages were widely distributed (for example NG1 and NG3), whereas others were animal specific, being encountered in only one or two animals (for example NG4, NG6, NG7, and NG8). The impact of various physiological and environmental factors on the diversity and community structure of AF was examined. The results suggest that animal host phylogeny exerts the most significant role on shaping anaerobic fungal diversity and community composition. These results greatly expand the documented global phylogenetic diversity of members of this poorly studied group of fungi that has an important function in initiating plant fiber degradation during fermentative digestion in ruminant and non-ruminant herbivores.
Hdsp, a horizontally transferred gene required for social behavior and halotolerance in salt-tolerant Myxococcus fulvus HW-1
Authors: Pan Hong-wei , Tan Zai-gao , Liu Hong , Li Zhi-feng , Zhang Cui-ying , Li Cheng-yun , Li Jie , Li Yue-zhong
Published: April 2010

Myxococcus fulvus HW-1, a salt-tolerant bacterial strain, which was isolated from a coastal environment, changes its behavior with different salinities. To study the relationship between behavioral shifts and the adaption to oceanic conditions, the HW-1 strain was randomly mutagenized using transposon insertion, producing a dispersed-growing mutant, designated YLH0401. The mutant did not develop fruiting bodies and myxospores, was deficient in S-motility, produced less extracellular matrix and was less salt tolerant. The YLH0401 strain was determined to be mutated by a single insertion in a large gene of unknown function (7011 bp in size), which is located in a horizontally transferred DNA fragment. The gene is expressed during the vegetative growth stage, as well as highly and stably expressed during the development stage. This horizontally transferred gene may allow Myxococcus to adapt to oceanic conditions.
Enantioselective transesterification of glycidol catalysed by a novel lipase expressed from Bacillus subtilis
Authors: Lei Wang , Jian‐Dong Tai , Ren Wang , Er‐Na Xun , Xiao‐fei Wei , Lei Wang , Zhi Wang
Published: April 2010

A novel plasmid (pBSR2) was constructed by incorporating a strong lipase promoter and a terminator into the original pBD64. The lipase gene from Bacillus subtilis strain IFFI10210 was cloned into the plasmid pBSR2 and transformed into B. subtilis A.S.1.1655 to obtain an overexpression strain. The recombinant lipase [BSL2 (B. subtilis lipase 2)] has been expressed from the novel constructed strain and used in kinetic resolution of glycidol through enantioselective transesterification. The effects of reaction conditions on the activity as well as enantioselectivity were investigated. BSL2 showed a satisfying enantioselectivity (E>30) under the optimum conditions [acyl donor: vinyl butyrate; the mole ratio of vinyl butyrate to glycidol was 3:1; organic medium: 1,2‐dichloroethane with water activity (aw)=0.33; temperature 40 °C]. The remaining (R)‐glycidol with a high enantiomeric purity [ee (enantiomeric excess) >99%] could be obtained when the conversion was approx. 60%. The results clearly show a good potential for industrial application of BSL2 in the resolution of glycidol through enantioselective transesterification.
Ginsenosides promote proliferation of granulosa cells from chicken prehierarchical follicles through PKC activation and up‐regulated cyclin gene expression
Authors: Tan Tu Quang , Ge Chutian , Mi Yuling , Jin Yanmei , Zhang Caiqiao
Published: April 2010

The effect of GS (ginsenosides) on proliferation of chicken GCs (granulosa cells) from prehierarchical SYF (small yellow follicles) was evaluated, and involvement of the PKC (protein kinase C) signalling pathway as well as mRNA expression of cyclins and CDK (cyclin‐dependent kinase) were investigated. Whole SYF or GCs isolated from SYF were cultured in Medium 199 supplemented with 0.5% FCS (fetal calf serum). After 16 h, the cells were challenged with GS alone or in combination with PKC inhibitor H7 or activator PMA (phorbol 12‐myristate 13‐acetate) for 24 h in serum‐free medium. Results showed that in both whole follicles and pure GCs monolayer culture system, GS (0.1–10 μg/ml) significantly increased the number of GCs in SYF in a dose‐dependent manner, and this stimulatory effect was inhibited by H7, but enhanced by PMA. Meanwhile, the PCNA‐LI (proliferating cell nuclear antigen labelling index) of GCs displayed similar changes with the cell number. Mechanism of GS action was further evaluated in cultured GCs separated from SYF. Western blot analysis showed that 10 μg/ml GS increased PKC translocation from cytoplasm to the plasma membrane of the GCs to become the active state. This effect was blocked by H7. Furthermore, GS up‐regulated the expression of cyclin D1/CDK6 and cyclin E/CDK2 mRNAs in GCs; however, inhibition of PKC with H7 attenuated this stimulatory effect. These results indicated that GS could stimulate proliferation of chicken GCs through activated PKC‐involved up‐regulation of cyclin D1/CDK6 and cyclin E/CDK2 genes, subsequently promoting development of the chicken prehierarchical follicles.
Quenching of impact ionization in heavy-ion induced electron-hole pair plasma tracks in wide bandwidth avalanche photodetectors
Authors: Laird Jamie Stuart , Onoda Shinobu , Hirao Toshio , Edmonds Larry
Published: April 2010

Optoelectronics such as Si avalanche photodiodes (APDs) used in space are subjected to background cosmic radiation including highly energetic heavy ions. As these swift ions pass through a device, they lose energy by promoting free electron-hole pairs. The resultant ionization track is an extremely dense two-component free carrier plasma with submicron radial diameters. Within the track, injected space charge is high enough to severely distort the local electric field, which perturbs the current transient or impulse response induced on the device electrodes. In this paper, the time-resolved ion beam induced current response of a low breakdown bias, high-frequency Si APD has been observed for a sequence of front side irradiations with MeV heavy ions species with different track geometries. These results are compared with focused picosecond laser experiments, where injection levels are controlled from low to high. Ion induced tracks are found to effectively quench the avalanche process. Simulations using Synopsis technology computer aided design are performed to clarify the role of screening in quenching avalanche mechanisms under the conditions prevalent here.
Laser driven supersonic flow over a compressible foam surface on the Nike laser
Authors: Harding E. C. , Drake R. P. , Aglitskiy Y. , Plewa T. , Velikovich A. L. , Gillespie R. S. , Weaver J. L. , Visco A. , Grosskopf M. J. , Ditmar J. R.
Published: April 2010

A laser driven millimeter-scale target was used to generate a supersonic shear layer in an attempt to create a Kelvin–Helmholtz (KH) unstable interface in a high-energy-density (HED) plasma. The KH instability is a fundamental fluid instability that remains unexplored in HED plasmas, which are relevant to the inertial confinement fusion and astrophysical environments. In the experiment presented here the Nike laser [S. P. Obenschain et al., Phys. Plasmas 3, 2098 (1996)] was used to create and drive Al plasma over a rippled foam surface. In response to the supersonic Al flow (Mach=2.6±1.1) shocks should form in the Al flow near the perturbations. The experimental data were used to infer the existence and location of these shocks. In addition, the interface perturbations show growth that has possible contributions from both KH and Richtmyer–Meshkov instabilities. Since compressible shear layers exhibit smaller growth, it is important to use the KH growth rate derived from the compressible dispersion relation.
Magnetic states and magnetization reversal in magnetostatically coupled multilayers with low perpendicular anisotropy
Authors: Tekielak M. , Dąbrowski M. , Kisielewski M. , Maziewski A. , Zablotskii V.
Published: April 2010

Multilayers of (F/NF)N composition, where F means a ferromagnetic layer, NF a nonferromagnetic one, and N the number of repetitions, are studied by simulations and theoretically for different magnetic anisotropy characterized by the quality factor, Q (the ratio of the anisotropy energy to be gained by a magnetization along the easy axis perpendicular to the sample surface and the magnetostatic energy of a uniformly magnetized layer along the surface normal). It is shown that the range of the existence of out-of-plane magnetization states could be extended to Q<1 by proper choice of N and the layers thicknesses. The role of magnetostatic interlayer coupling in the formation of vortexlike and sinusoidal-like distributions of the magnetization is revealed. Different magnetization states are mapped onto a (Q,N)-phase diagram. We demonstrate that a (F/NF)N multilayer is a soft magnetic system in which the domain size could be changed by a few orders of magnitude by small variations of Q, N, and/or the NF spacer thickness. The evolution of magnetization distributions under applied in-plane and perpendicular magnetic fields is studied, as well as calculating the saturation fields and their dependences on Q and N.
Bias dependent two-channel conduction in InAlN/AlN/GaN structures
Authors: Leach J. H. , Ni X. , Li X. , Wu M. , Özgür Ü. , Morkoç H. , Zhou L. , Cullen D. A. , Smith D. J. , Cheng H. , Kurdak Ç. , Meyer J. R. , Vurgaftman I.
Published: April 2010

Due to growth temperature differences during deposition of GaN heterostructures utilizing InAlN barriers, an inadvertent parasitic GaN layer can form in the InAlN barrier layer. In structures utilizing AlN spacer layers, this parasitic layer acts as a second conduction channel with a carrier density dependent upon polarization charges and lattice strain as well as the surface potential. The effect of an additional GaN spacer layer in InAlN/AlN/GaN structures is assessed using simulations, electron-microscopy observations, magnetoconductivity measurements with gated Hall bar samples, and with quantitative mobility spectrum analysis. We propose a possible formation mechanism for the parasitic layer, and note that although the additional unintended layer may have beneficial aspects, we discuss a strategy to prevent its occurrence.
Exchange bias and coercivity of Ni80Fe20 layer coupled with Fe-doped Cr2O3
Authors: Ki Sanghoon , Dho Joonghoe
Published: April 2010

We have investigated the exchange bias and the coercivity in the ferromagnet Ni80Fe20 (NiFe) layer coupled with a polycrystalline Cr2(1−x)Fe2xO3(CFO; x=0.1,0.25) layer, which is known as an antiferromagnet with spiral spin order. For x=0.1, the exchange bias HEX and the coercivity HC at 10 K were 152 and 230 Oe, respectively, but their magnitudes rapidly decreased from 10 to 50 K at the temperature range that showed a splitting between zero-field-cooling and field-cooling magnetization data for the CFO target. This implies that the CFO has an unknown magnetic transition around ∼50 K in addition to the spiral antiferromagnetic transition at ∼250 K. For x=0.25, on the other hand, the exchange bias rapidly decreased from ∼170 Oe at 10 K to zero at ∼90 K.
Magnetoelasticity of Fe–Si single crystals
Authors: Xing Q. , Wu D. , Lograsso T. A.
Published: April 2010

The tetragonal magnetostriction constant, (3/2)λ100, of Fe–Si single crystals was measured and was found to be structure dependent. Similar to that of Fe–Ge single crystals, (3/2)λ100 is positive in the single phase A2 regime, becomes negative in the single phase D03 regime, and changes from positive to negative between the two regimes. Short-range order in the A2 regime decreases the magnetostriction prior to the onset of long range order. In the single phase regions of both A2 and D03, thermal history does not show any obvious effect on the magnetostriction, contrary to that found for Fe–Ga alloys. However, in the regions of phase mixture involving A2, B2, and D03 phases, quenching pushes the change in magnetostriction from positive to negative to higher Si contents.
Perpendicular-field magnetoresistance and thermal-ferromagnetic resonance measurement of easy-plane anisotropy in nanostructured magnetic tunnel junctions
Authors: Mascaro M. D. , Sun J. Z.
Published: April 2010

We report on measurements of the easy-plane anisotropy field of MgO-based magnetic tunnel junctions. The free layer easy-plane anisotropy field was measured by perpendicular field thermal noise-based ferromagnetic resonance spectroscopy (T-FMR) and by tunneling magnetoresistance (TMR). A model was derived to extract the saturation field of the free layer from perpendicular TMR-based resistance-field data. Both measurements confirm that for 20 Å CoFeB free layers, the measured effective easy-plane anisotropy field of 4πMeff equal to (5.3±0.6) kOe is well below the bulk value based on demagnetization. T-FMR measurements show a base resonant mode with a linear field dependence in accordance with the Kittel formula. Higher-order modes are also observed, suggesting the presence of confined spin-wave excitations. The mode frequency spacing, however, shows significant device-to-device variations whose origin is not yet uniquely determined.
Metallic Mg insertion in rf deposited MgO barrier
Authors: Souza M. M. C. , Sousa R. C. , Ducruet C. , Auffret S. , Dieny B.
Published: April 2010

Metallic Mg insertions in rf deposited MgO barrier of magnetic tunnel junctions structures were investigated in a resistance-area (RA) range from 1 to 1000 Ω μm2. For the first time, investigations on Mg insertions above the MgO barrier and simultaneously on both sides of the barrier are reported. It is shown that for RA larger than 5 Ω μm2, a bottom Mg insertion does not improve the tunnel magnetoresistance (TMR) ratio compared to a sample with no Mg insertion. Furthermore, a top Mg insertion yields a lower TMR ratio decreasing as the Mg thickness is increased. On the other side, for RA lower than 5 Ω μm2, there is no significant difference between top and bottom Mg insertions indicating that in this region, the MgO crystallization occurs mainly during the annealing process. In the RA range investigated, there is no significant difference in coupling field for different insertions. In very low RA regions between 1 and 10 Ω μm2, an increase in TMR is observed for 0.3 nm insertions simultaneously below an above the barrier.
Crystal structure and magnetic properties of rf-sputtered Cu–Zn ferrite thin films
Authors: Sultan M. , Singh R.
Published: April 2010

Cu–Zn ferrite (Cu0.6Zn0.4Fe2O4) thin films were deposited using rf-magnetron sputtering on glass substrates at room temperature in pure Ar gas environment. The influence of variation in Ar gas pressure between 5 and 15 mT on the crystal structure and magnetization has been studied. The XRD patterns show single phase nanocrystalline spinel structure with cubic symmetry. The AFM images also confirm the nanocrystalline nature of the films. The magnetization increases with increase in Ar gas pressure. The change in the crystal structure and magnetization has been explained in view of freezing of some Cu-ions on tetrahedral A-sites and equivalent number of Fe ions on octahedral B-sites during the deposition process due to high deposition rate in pure Ar environment. Furthermore, the deposition in reducing (argon) atmosphere may lead to the formation of Cu+ ions that prefer occupation of the smaller four-coordinated A-site in the spinel structure and displace Fe3+ cations to occupy the B-sites. The formation of Fe2+ cannot be ruled out in the spinel structure where a fraction of Fe3+ will be replaced by Fe2+ ions.
Dimension of conformal blocks in five dimensional Kähler–Chern–Simons theory
Authors: Liu Haitao
Published: April 2010

We briefly review the Kähler–Chern–Simon theory on five manifolds, which are trivial circle bundles over four dimensional Kähler manifolds, and present a detailed calculation of the path integral using the method of Blau and Thompson [Nucl. Phys. B 408, 345 (1993)].
Magnetic susceptibility of nanoscale Kondo systems
Authors: Skomski R. , Zhang R. , Kharel P. , Enders A. , Liou S.-H. , Sellmyer D. J.
Published: April 2010

The mesoscopic Kondo effect in metallic nanoparticles containing a magnetic impurity is investigated by model calculations. A Maxwell–Garnett approach is used to approximately determine the resistivity of doped nanoparticles in a matrix, and the magnetic susceptibility is estimated from the confinement of the conduction electrons. Conductivity measurements of nanoparticles embedded in a matrix are difficult to realize, because metallic matrices distort the Kondo cloud, whereas insulating or semiconducting matrices yield a very weak signal. By comparison, susceptibility measurements do not suffer from these shortcomings. The Kondo effect survives in nanoparticles even if the cluster size is much smaller than the Kondo screening cloud, but the effective Curie constant becomes constant below a particle-size dependent transition temperature and the temperature dependence of the susceptibility is no longer universal.
Some two-dimensional parameter spaces of a Chua system with cubic nonlinearity
Authors: Stegemann Cristiane , Albuquerque Holokx A. , Rech Paulo C.
Published: April 2010

In this paper we investigate three two-dimensional parameter spaces of a three-parameter set of autonomous differential equations used to model the Chua oscillator, where the piecewise-linear function usually taken to describe the nonlinearity of the Chua diode has been replaced by a cubic polynomial. It is made by using three independent two-dimensional cross sections of the three-dimensional parameter space generated by the model, which contains three parameters. We show that, independent of the parameter set considered in plots, all the diagrams present periodic structures embedded in a large chaotic region, and we also show that these structures organize themselves in period-adding cascades. We argue that these selected two-dimensional cross sections can be representative of the three-dimensional parameter space as a whole, in the range of parameters here investigated.
Effect of background gas pressure and laser pulse intensity on laser induced plasma radiation of copper samples
Authors: Mehrabian S. , Aghaei M. , Tavassoli S. H.
Published: April 2010

Study of laser induced plasma emission of Cu in one dimension is numerically carried out. Effects of different background gas pressure (He), 100, 500, and 760 torr, and laser pulse intensities, 0.5, 0.7, and 1 GW/cm2, on the plasma emission as well as ablation processes are investigated. Under a specified condition, heat conduction equation in the target accompanied with gas dynamic equations in the plume is solved simultaneously. The mentioned equations are coupled to each other through the Knudsen layer conditions and the energy and mass balances at the interface between the target and the vapor. The Bremsstrahlung radiation of plasma and the spectral emission of copper atoms are studied under various background gas pressure and laser pulse intensities. Furthermore, number density of He, Cu, and the electron, pressure, and temperature of the plume under various conditions are obtained. In the early time after laser pulse, plasma radiation is mainly due to the Bremsstrahlung radiation while after some 10 ns, the plasma radiation is dominated by spectral emission of Cu atoms. A similar uncoupling is observed spatially. The Bremsstrahlung emission is dominant near the sample surface while at farther points the spectral emission is the dominant one. By increase in the background pressure and also the pulse intensity, the dominancy of the spectral emission would occur later in time and farther in position.
Note: Development of a compact electromagnetic hydraulic pump for a microrobot joint driving system
Authors: Chen Naijian , Wang Sun’an , Zhang Jinhua
Published: April 2010

This note describes a compact electromagnetic hydraulic pump (EMHP) designed primarily to build a microdriving system for a robot joint actuator. A characteristic mathematical model integrating electricity, magnetism, and hydraulics is constructed to represent the working process of the EMHP. Tests show that a volumetric flow rate of up to 430 cm3/min and load pressure of up to 2.5 MPa can be achieved. The prototype pump can supply stable pressure of 0∼2.4 MPa and acceleration of 1.2 MPa/s for the robot joint actuator.
Propagation impedance of surface waves
Authors: Mugnai D. , Ranfagni A.
Published: April 2010

We report some experimental results of delay time in electromagnetic propagation in the presence of a lossy dielectric medium. The results were performed in the range of microwaves and showed a shortening of the delay time when the surface of the medium is situated very close to the wave path. A theoretical model dealing with surface waves of Zenneck type was considered.
Optimal multiferroic properties and enhanced magnetoelectric coupling in SmFeO3–PbTiO3 solid solutions
Authors: Singh Anupinder , Choudhary Ishan , Mehta Sunita , Dahiya Sajjan , Walia Chitsimranjit Singh , Raina K. K. , Chatterjee Ratnamala
Published: April 2010

Multiferroic solid solutions of (Pb0.8Sm0.2)(Ti0.8Fe0.2)O3 are synthesized by conventional solid-state reaction. Microstructure property relationship has been studied and it is shown that the multiferroic properties in the sample are dependent on sintering temperature. The sample sintered at 1200 °C exhibits optimal properties and shows enhanced magnetoelectric coupling at room temperature. For the sample sintered at 1200 °C, large remnant polarization (Pr∼20 μC/cm2) and positive remnant magnetization (Mr∼0.021 emu/g) were observed at room temperature.
Radiation-temperature shock scaling of 1 ns laser-driven hohlraums
Authors: Li Yongsheng , Lan Ke , Lai Dongxian , Gao Yaoming , Pei Wenbing
Published: April 2010

Simulations of the x-ray ablation process of aluminum are performed using a one-dimensional multigroup radiation hydrodynamic code RDMG [F. Tinggui et al., Chin. J. Comput. Phys. 16, 199 (1999)]. The scaling relation of the peak temperatures of the x-ray sources with the shock velocities is studied, and its dependence on the temporal profile and the length of the x-ray sources is described and analyzed in this paper. A scaling relation applicable to x-ray sources of 1 ns pulse laser-driven hohlraums is proposed, the dependence of which is studied and found to be negligible. Our scaling relation of radiation temperature versus shock velocity is about 10 eV lower than that proposed by Kauffman et al. [Phys. Rev. Lett. 73, 2320 (1994)] for shock velocity of (4–8)×106 cm/s.
Modified correlation entropy estimation for a noisy chaotic time series
Authors: Jayawardena A. W. , Xu Pengcheng , Li W. K.
Published: April 2010

A method of estimating the Kolmogorov–Sinai (KS) entropy, herein referred to as the modified correlation entropy, is presented. The method can be applied to both noise-free and noisy chaotic time series. It has been applied to some clean and noisy data sets and the numerical results show that the modified correlation entropy is closer to the KS entropy of the nonlinear system calculated by the Lyapunov spectrum than the general correlation entropy. Moreover, the modified correlation entropy is more robust to noise than the correlation entropy.
High-order expansion of T2×t2 Jahn–Teller potential-energy surfaces in tetrahedral molecules
Authors: Opalka Daniel , Domcke Wolfgang
Published: April 2010

Methods from Jahn–Teller theory and invariant theory have been combined for the construction of analytic diabatic potential-energy surfaces of triply degenerate states in tetrahedral molecules. The potentials of a threefold degenerate electronic state of T2 symmetry, subject to the T2×t2 or T2×(t2+t2) Jahn–Teller effect in a three-dimensional or six-dimensional space of nuclear coordinates, respectively, are considered. The permutation symmetry of four identical nuclei is taken into account in the polynomial expansion of the diabatic surfaces. Symmetry adapted polynomials up to high orders are explicitly given and a simple combinatorial scheme was developed to express terms of arbitrary order as products of a small number of polynomials which are invariant under the permutation of identical nuclei. The method is applied to the methane cation in its triply degenerate ground state. The parameters of the analytic surfaces have been fitted to accurate ab initio data calculated at the full-valence CASSCF/MRCI/cc-pVTZ level. A three-sheeted six-dimensional analytic potential-energy surface of the T22 ground state of CH4+ is reported, which involves terms up to eighth order in the degenerate stretching coordinate, up to 12th order in the degenerate bending coordinate, and up to fourth order in the stretch-bend coupling.
Shock ignition target design for inertial fusion energy
Authors: Schmitt Andrew J. , Bates Jason W. , Obenschain Steven P. , Zalesak Steven T. , Fyfe David E.
Published: April 2010

Continuing work in the design of shock ignition targets is described. Because of reduced implosion velocity requirements, low target adiabats, and efficient drive by short wavelength lasers, these targets produce high gain (>100) at laser energies well below 1 MJ. Effects of hydrodynamic instabilities such as Rayleigh–Taylor or Richtmyer–Meshkov are greatly reduced in these low-aspect ratio targets. Of particular interest is the optimum ratio of ignitor to compression pulse energy. A simple pellet model and simulation-derived coupling coefficients are used to analyze optimal fuel assembly, and determine that shock ignition allows enough control to create theoretically optimum assemblies. The effects on target design due to constraints on the compression and ignitor pulse intensities are also considered and addressed. Significant sensitivity is observed from low-mode perturbations because of large convergence ratios, but a more powerful ignitor can mitigate this.
A novel approach to use of elastomer for monitoring of pressure using plastic optical fiber
Authors: Kulkarni Atul , Kim Hyeongkeun , Choi Jaeboong , Kim Taesung
Published: April 2010

Elastomer has become a material of much interest for use as a deformation element in pressure and force monitoring devices. In the present work, we fabricated and characterized a pressure sensor that uses the polydimethylsiloxane (PDMS) elastomer and the plastic optical fiber (POF). The POF is used to guide light through the 10 mm thick PDMS block and collect the transmitted light and deliver it to the detector. In the force sensor, an applied pressure deforms the PDMS block, increasing the transmissivity of the device. The fabricated pressure sensor shows satisfactory response up to 478 kPa with excellent sensitivity and repeatability. The present pressure sensor is simple to fabricate and can be used for a wide range industrial and automobile applications.
Influence of feedback parameters on ferroelectric domain imaging with piezoresponse force microscopy
Authors: Bo Huifeng , Kan Yi , Lu Xiaomei , Peng Song , Wang Xiaofei , Liu Yunfei , Cai Wei , Xue Ruoshi , Zhu Jinsong
Published: April 2010

The piezoresponse (PR) amplitude and phase signals for antiparallel ferroelectric domains were investigated with different feedback parameters. It is found that the drive frequency and setpoint can strongly alternate the PR image contrast, while the drive phase can be considered as a constant adding to the PR phase signal. The PR amplitude is proportional to the drive amplitude while the PR phase is drive amplitude independent. The larger piezoelectric vibration amplitude and fitting piezoelectric constants (PCs) obtained by vectorial analysis compared with the known values are originated from the sample resonance, and the local electrostatic force can lead to a nonlinear shift in the measured PCs from the theoretical expectations.
High-temperature dielectric response of (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3: Does Burns temperature exist in ferroelectric relaxors?
Authors: Bobnar V. , Filipič C. , Levstik A. , Kutnjak Z.
Published: April 2010

It has been considered that polar nanoregions (PNRs) in relaxors form at Burns temperature Td≈600 K. High-temperature dielectric investigations of Pb(Mg1/3Nb2/3)O3 (PMN) and 0.7PMN−0.3PbTiO3 reveal, however, that the dielectric dispersion around 600 K appears due to the surface-layer contributions. The intrinsic response, analyzed in terms of the universal scaling, imply much higher Td or formation of PNRs in a broad temperature range, while high dielectric constants manifest that polar order exists already at the highest measured temperatures of 800 K. The obtained critical exponents indicate critical behavior associated with universality classes typically found in spin glasses.
Kinetics of intermediate-mediated self-assembly in nanosized materials: A generic model
Authors: Lutsko James F. , Basios Vasileios , Nicolis Grégoire , Caremans Tom P. , Aerts Alexander , Martens Johan A. , Kirschhock Christine E. A. , van Erp Titus S.
Published: April 2010

We propose in this paper a generic model of a nonstandard aggregation mechanism for self-assembly processes of a class of materials involving the mediation of intermediates consisting of a polydisperse population of nanosized particles. The model accounts for a long induction period in the process. The proposed mechanism also gives insight on future experiments aiming at a more comprehensive picture of the role of self-organization in self-assembly processes.
Stress-based vapor sensing using resonant microbridges
Authors: Southworth D. R. , Bellan L. M. , Linzon Y. , Craighead H. G. , Parpia J. M.
Published: April 2010

We demonstrate that silicon-polymer composite microbridges provide a robust means of water vapor detection at ambient pressure. Volumetric changes in the reactive polymer alter the tension in a doubly clamped structure leading to large and rapid changes in the resonance frequency. We demonstrate stress-based sensing of water vapor in ambient pressure nitrogen using doubly clamped buckled beams coated with a hygroscopic polymer. We show stress sensitivity of around 20 kPa (∼170 ppb of water vapor) and subsecond response time for coated microbridges.
Exchange bias in spin glass (FeAu)/NiFe thin films
Authors: Yuan Fu-Te , Lin Jeng-Kai , Yao Y. D. , Lee Shang-Fan
Published: April 2010

The exchange bias of a ferromagnet in contact with a spin glass is evidenced in the sputter deposited (Fe 9.6 at. % Au)/NiFe bilayers. The biasing field decreases as temperature increases, change the sign after reaching a compensation temperature (To), and are reduced to zero at higher temperatures. Furthermore, To decreases with the decreasing FeAu layer thickness. Likewise, the inverse bias decreases with the increasing maximum field of a hysteresis loop. A spin structure model is suggested to explain our data. The results confirm the robust nature of the inverse bias in spin glass/ferromagnetic structure and reveal distinct physics from conventional antiferromagnetic/ferromagnetic systems.
Origin of antiferromagnetism in CoO: A density functional theory study
Authors: Deng Hui-Xiong , Li Jingbo , Li Shu-Shen , Xia Jian-Bai , Walsh Aron , Wei Su-Huai
Published: April 2010

We have investigated the origin of antiferromagnetism of CoO in the rocksalt structure using spin-polarized density functional theory calculations. We find that in the rocksalt structure, the superexchange interaction between the occupied and unoccupied eg states plays the dominant role, which leads to an antiferromagnetic ground state, but the system also has a strong direct exchange interaction between the partially occupied minority spin t2g states that leads to the unusual situation that the ferromagnetic phase is more stable than most antiferromagnetic configurations.
Spectroscopic investigation of the semiconductor molecular packing in fully operational organic thin-film transistors
Authors: Fraboni B. , Scidà A. , Cavallini A. , Cosseddu P. , Bonfiglio A. , Milita S. , Nastasi M.
Published: April 2010

We report on Photocurrent (PC) and optical absorption spectroscopy analyses of the electronic density of states (DOS) distribution around the band-edge of pentacene films of different thickness (from 50 to 300 nm). Both experimental methods allowed us to independently monitor the increase with increasing film thickness of the Davydov splitting of the first absorption band, correlated with modifications in the film molecular structure and packing when passing from a dominant “thin film” to a dominant “bulk” phase. We show how PC spectroscopy has the remarkable ability to detect the modification of the DOS distribution in a noninvasive way, thus allowing the study of fully operational organic thin film transistors.
Photoinduced deformation of azopolymer nanometric spheres
Authors: Barillé R. , Tajalli P. , Kucharski S. , Ortyl E. , Nunzi J.-M.
Published: April 2010

Nanometric spheres of an azopolymer are obtained by micellization from a solution. We observe photoinduced deformation of the individual nanospheres under white light illumination. The diameter expands up to 35% parallel to the substrate surface. The magnitude of the force that is necessary to produce the same effect is estimated.
Plasmonic enhanced quantum well infrared photodetector with high detectivity
Authors: Wu Wei , Bonakdar Alireza , Mohseni Hooman
Published: April 2010

We report a normal-incident quantum well infrared photodetector (QWIP) strongly coupled with surface plasmon modes. A periodic hole array perforated in gold film was integrated with In0.53Ga0.47As/InP QWIP to convert normal-incident electromagnetic waves into surface plasmon waves, and to excite the intersubband transition of carriers in the quantum wells. The peak responsivity of the photodetector at ∼8 μm was ∼7 A/W at the bias of 0.7 V at 78 K with the peak detectivity as high as ∼7.4×1010 cm Hz1/2/W. The full width at half maximum of the response spectrum was only ∼0.84 μm due to a narrow plasmonic resonance.
Thermodynamic and Thermophysical Properties of Organic Nitrogen Compounds. Part I. Methanamine, Ethanamine, 1- and 2-Propanamine, Benzenamine, 2-, 3-, and 4-Methylbenzenamine
Authors: Chao J. , Gadalla N. A. M. , Gammon B. E. , Marsh K. N. , Rodgers A. S. , Somayajulu G. R. , Wilhoit R. C.
Published: April 2010

The thermodynamic and thermophysical properties of eight primary amines, methanamine, ethanamine, 1- and 2-propanamine, benzenamine, and 2-, 3-, and 4-methylbenzenamine have been evaluated. Recommended values are given for the following properties: normal boiling, freezing, and triple-point temperatures, critical constants, thermodynamic properties in the solid and liquid phases, vapor pressure, enthalpy of vaporization, density, second virial coefficients, and enthalpy of combustion. Ideal gas thermodynamic properties have been calculated by statistical mechanical methods.
What Sound Does That Taste? Cross-Modal Mappings across Gustation and Audition
Authors: Simner Julia , Cuskley Christine , Kirby Simon
Published: April 2010

All people share implicit mappings across the senses, which give us preferences for certain sensory combinations over others (eg light colours are preferentially paired with higher-pitch sounds; Ward et al, 2006 Cortex42 264–280). Although previous work has tended to focus on the cross-modality of vision with other senses, here we present evidence of systematic cross-modality between taste and sound. We created four sound continua representing to varying extents phonetic qualities of speech (F1, F2, voice discontinuity, and spectral balance). Sixty-five participants selected their preferred sound to accompany each of the basic tastes of sweet, sour, bitter, and salty, at two different concentrations. We found significant shared preferences among our participants to map certain acoustic qualities to certain types of tastes (eg sweet tastes tend to be mapped to a lower spectral balance than sour tastes). We also found a preference for mapping certain sound qualities to different taste concentrations. Together our data provide the first detailed analysis of how phonetic features map systematically to different tastants and concentrations. We examine the roots of these mappings, and discuss how such associations might guide the ways in which human languages are used to name objects with taste.
Distinct large-scale turbulent-laminar states in transitional pipe flow
Authors: Moxey David , Barkley Dwight
Published: April 2010

When fluid flows through a channel, pipe, or duct, there are two basic forms of motion: smooth laminar motion and complex turbulent motion. The discontinuous transition between these states is a fundamental problem that has been studied for more than 100 yr. What has received far less attention is the large-scale nature of the turbulent flows near transition once they are established. We have carried out extensive numerical computations in pipes of variable lengths up to 125 diameters to investigate the nature of transitional turbulence in pipe flow. We show the existence of three fundamentally different turbulent states separated by two distinct Reynolds numbers. Below Re 1 ≃ 2,300, turbulence takes the form of familiar equilibrium (or longtime transient) puffs that are spatially localized and keep their size independent of pipe length. At Re 1the flow makes a striking transition to a spatio-temporally intermittent flow that fills the pipe. Irregular alternation of turbulent and laminar regions is inherent and does not result from random disturbances. The fraction of turbulence increases with Re until Re 2 ≃ 2,600 where there is a continuous transition to a state of uniform turbulence along the pipe. We relate these observations to directed percolation and argue that Re 1marks the onset of infinite-lifetime turbulence.
Nonlinear coupling between cerebral blood flow, oxygen consumption, and ATP production in human visual cortex
Authors: Lin Ai-Ling , Fox Peter T. , Hardies Jean , Duong Timothy Q. , Gao Jia-Hong
Published: April 2010

The purpose of this study was to investigate activation-induced hypermetabolism and hyperemia by using a multifrequency (4, 8, and 16 Hz) reversing-checkerboard visual stimulation paradigm. Specifically, we sought to (
i
) quantify the relative contributions of the oxidative and nonoxidative metabolic pathways in meeting the increased energy demands [i.e., ATP production (J
ATP
)] of task-induced neuronal activation and (
ii
) determine whether task-induced cerebral blood flow (CBF) augmentation was driven by oxidative or nonoxidative metabolic pathways. Focal increases in CBF, cerebral metabolic rate of oxygen (CMRO
2
; i.e., index of aerobic metabolism), and lactate production (J
Lac
; i.e., index of anaerobic metabolism) were measured by using physiologically quantitative MRI and spectroscopy methods. Task-induced increases in J
ATP
were small (12.2–16.7%) at all stimulation frequencies and were generated by aerobic metabolism (approximately 98%), with %ΔJ
ATP
being linearly correlated with the percentage change in CMRO
2
(
r
= 1.00,
P
< 0.001). In contrast, task-induced increases in CBF were large (51.7–65.1%) and negatively correlated with the percentage change in CMRO
2
(r = −0.64,
P
= 0.024), but positively correlated with %ΔJ
Lac
(
r
= 0.91,
P
< 0.001). These results indicate that (
i
) the energy demand of task-induced brain activation is small (approximately 15%) relative to the hyperemic response (approximately 60%), (
ii
) this energy demand is met through oxidative metabolism, and (
iii
) the CBF response is mediated by factors other than oxygen demand.
Auditory discrimination learning and knowledge transfer in mice depends on task difficulty
Authors: Kurt Simone , Ehret Günter
Published: April 2010

Mice reproduce interesting effects in auditory discrimination learning and knowledge transfer discussed in human studies: (
i
) the advantage in the transfer from a hard to an easy task by benefits from transfer of procedural knowledge and information-integration learning, and (
ii
) the disadvantage in the transfer from easy to hard tasks by inability to generalize across perceptually different classes of stimuli together with initially unsuccessful attempts to transfer cognitive skills from one task to the other. House mice (NMRI strain) were trained in a shuttle-box stimulus discrimination task. They had to discriminate either between two pure tones of different frequencies (PT) or between two different modulation frequencies of an amplitude-modulated tone (AM). Then transfer of knowledge between these two tasks was tested. Mice rapidly learned PT discrimination within two to three training sessions (easy task). AM discrimination learning took longer and did not reach the high performance level of PT discrimination (hard task). No knowledge transfer was detected in animals first trained with the easy (PT) followed by the hard (AM) discrimination task. Mice benefited, however, from knowledge transfer when the AM discrimination was followed by the PT discrimination. When the task changed, confusion of conditioned stimuli occurred if the carrier frequency of the AM was the same as one of the frequencies in the PT task. These results show a hard-to-easy effect when possible knowledge transfer is tested between qualitatively different stimulus classes. The data establish mice as promising animal model for research on genetics of auditory perception and learning.