bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ga+ irradiation in molecular-beam epitaxy grown Pt/Co/Pt thin films studied by magneto-optic spectroscopy
Authors: Jakubisova-Liskova E. , Visnovsky S. , Wawro A. , Baczewski L. T. , Mazalski P. , Maziewski A. , Liedke M. O. , McCord J. , Fassbender J.
Published: February 2014

In-depth profile changes induced by Ga+ ion irradiation in Pt(5 nm)/Co(3.3 nm)/Pt(20 nm)/Mo(20 nm) sandwiches MBE grown on Al2O3 substrates are deduced from complex magneto-optic polar Kerr effect (PMOKE) measurements at photon energies between 1 and 5 eV. The Ga+ irradiation stimulates a redistribution of Pt and Co and leads to broadening of alloyed regions at Pt-Co and Co-Pt interfaces, which is evaluated using PMOKE spectra. The effect of four Ga+ fluences D between zero and 6 × 1015 Ga+/cm2 was studied. The observed PMOKE azimuth rotation peak centered at 4.5 eV reaches the maximum of 0.42° at D = 1 × 1015 Ga+/cm2 and becomes thus enhanced by a factor of 3.2 with respect to that in the non-irradiated sample. At D = 6 × 1015 Ga+/cm2 the peak amplitude falls to 0.05°. To find the in-depth profile of Co concentration s in the sandwiches as a function of D, the PMOKE azimuth rotation and ellipticity spectra are compared with a multilayer model, where ideal flat interfaces are replaced by sequences of CosPt1−s layers. The dependence on D is compared with that evaluated by simulations of the structural effects of ion irradiation. At the highest D, the irradiation produces an almost complete erosion of the top Pt and Co accompanied by mixing at the Pt-Mo interface.
Magnetocaloric effect in as-cast Gd1−xYx alloys with x = 0.0, 0.1, 0.2, 0.3, 0.4
Authors: Lara Pérez E. S. , Betancourt I. , Hernández Paz J. F. , Matutes Aquino J. A. , Elizalde Galindo J. T.
Published: February 2014

In this report, we present the magnetocaloric effect of Gd1−xYx alloys (0.0 ≤ × ≤ 0.4) prepared by arc-melting from high purity Gd and Y precursors in inert atmosphere. The formation of Gd1−xYx solid solutions was verified by means of X-ray diffraction analysis across the compositional series; also, residual secondary phases Gd and Y were present. Magnetic characterization performed by Vibrating Sample Magnetometry at a maximum applied field of 3.0 T showed a drastic reduction of the magnetization saturation (from 233 emu/g for x = 0.0 to 183 emu/g for x = 0.4), due to a dilution effect of the Y alloying, together with a marked Curie temperature decrease from 296 K to 196 K between x = 0.0 and x = 0.4. The second-order character of the magnetic transition was established by Arrot plots for all the cases. On the other hand, the magnetic entropy variation, determined from numerical integration of Maxwell relation displayed excellent values above 5.30 J/kg K for alloys with x < 0.3 due to the steep transition of the thermomagnetic curves.
Electrodeposition of FeCoCd films with in-plane uniaxial magnetic anisotropy for microwave applications
Authors: Feng Erxi , Wang Zhenkun , Du Hongwei , Wei Jinwu , Cao Derang , Liu Qingfang , Wang Jianbo
Published: February 2014

FeCoCd thin films with 500 nm thickness are directly prepared through electrodeposition in the sulphate bath in which glycine and citric acid were added as complex agents. The composition, structure, and magnetic of FeCoCd films were investigated as a function of Cd2+ concentration, cathode current density, and deposition temperature. A wonderful soft magnetic FeCoCd film was prepared and its coercivity of easy axis and hard axis are 5 Oe and 4 Oe, respectively. The natural resonance frequency is about 3.0 GHz, which imply that the FeCoCd film is potential candidate for high frequency applications.
Effective high-energy ball milling in air of Fe65Co35 alloys
Authors: Sirvent P. , Berganza E. , Aragón A. M. , Bollero A. , Moure A. , García-Hernández M. , Marín P. , Fernández J. F. , Quesada A.
Published: February 2014

Fe65Co35 alloys are technologically relevant, especially in magnetic storage and composite permanent magnets, due to the fact that they present higher saturation magnetization per volume than any other material. Out of the various approaches undertaken for its production, mechanical ball milling remains the most common and efficient method, especially considering the large industrial scale of the applications. With the development of cost-efficient processing in mind, the influence of performing the synthesis of the FeCo alloys in air instead of the standard argon atmosphere is studied. The structural and magnetic characterization, along with the study of the oxygen content of the samples, proves that synthesizing FeCo alloys in air produce materials with nearly identical magnetic performance as their argon-milled counterpart, with the oxidation extent of the materials consisting almost exclusively of the oxide passivating layer located at the surface. In addition, no aging effect was observed in the saturation magnetization up to 6 months. It is concluded that the use of argon atmospheres, desiccators and/or glove boxes may be entirely removed from the process without affecting the magnetic properties.
Self-oscillation of standing spin wave in ring resonator with proportional-integral-derivative control
Authors: Peng B. , Urazuka Y. , Chen H. , Oyabu S. , Otsuki H. , Tanaka T. , Matsuyama K.
Published: February 2014

We report on numerical analysis on self-oscillation of standing spin wave excited in a nanostructured active ring resonator, consists of a ferromagnetic nanowire with perpendicular anisotropy. The confined resonant modes are along the nanowire length. A positive feedback with proportional-integral-derivative gain control was adopted in the active ring. Stable excitation of the 1st order standing spin wave has been demonstrated with micromagnetic simulations, taking into account the thermal effect with a random field model. The stationary standing spin wave with a pre-determined set variable of precession amplitude was attained within 20 ns by optimizing the proportional-integral-derivative gain control parameters. The result indicates that a monochromatic oscillation frequency fosc is extracted from the initial thermal fluctuation state and selectively amplified with the positive feedback loop. The obtained fosc value of 5.22 GHz practically agrees with the theoretical prediction from dispersion relation of the magneto static forward volume wave. It was also confirmed that the fosc change due to the temperature rise can be compensated with an external perpendicular bias field Hb. The observed quick compensation time with an order of nano second suggests the fast operation speed in the practical device application.
Analysis of thin-film magnetoimpedance sensor using the variations in impedance and the magnetic domain structure
Authors: Shin Jaewon , Hoon Kim Sung , Hashi Shuichiro , Ishiyama Kazushi
Published: February 2014

A magnetic anisotropy is very important in the development of sensitive magnetoimpedance (MI) sensors. According to changes in the direction and energy of magnetic anisotropy, the changes in permeability result in impedance variation. Hence, an understanding of relationship between structure of magnetic anisotropy and impedance variation is required for the development of MI sensors. However, the relationship has not been considered so far. Therefore, we analyzed both impedance variation and magnetic domain. The minimum impedance appeared with transversely induced magnetic anisotropy, and the maximum value of the impedance was observed when the magnetic moments of approximately 84% rotated longitudinally. Through the magnetic domain observation and the variations in the impedance, we carried out quantitative analysis of magnetic properties on the FeSiB layer with an MI sensor using impedance, hysteresis loop, and magnetic domain analysis.
Quasi magnetic isotropy and microwave performance of FeCoB multilayer laminated by uniaxial anisotropic layers
Authors: Li Shandong , Du Honglei , Zhang Yongcheng , Xue Qian , Gao Xiaoyang , Shao Weiquan , Zhou Ziyao , Nan Tianxiang , Sun Nian X.
Published: February 2014

A Fe0.7Co0.3-B multilayer was laminated by three Fe0.7Co0.3-B ferromagnetic sublayers prepared by composition gradient sputtering. Three Fe0.7Co0.3-B ferromagnetic sublayers have their individual directions of uniaxial magnetic anisotropy, and the easy magnetic axis of neighboring sublayer successively rotates 60° in the film plane. It is exciting that a quasi magnetic isotropy was achieved in the designed multilayer with a quasi-isotropic hysteresis loop and quasi-isotorpic ferromagnetic resonance around 3.7 GHz. This omnidirectional multilayer is promising for the application in inductors since the 100% hard-axis excitation is achieved for any shaped inductors.
Magnetotransport properties of Fe/GaAlAs/GaMnAs hybrid magnetic trilayer structures
Authors: Yoo Taehee , Lee Sanghoon , Liu Xinyu , Furdyna Jacek K. , Uk Lee Dong , Kim Eun Kyu
Published: February 2014

We discuss tunneling magnetoresistance (TMR) phenomena observed in hybrid magnetic tunnel junctions (MTJs) fabricated from a Fe/GaAlAs/GaMnAs trilayer. The TMR clearly shows abrupt changes of resistance that depends on the relative alignments of magnetization in the two magnetic layers comprising the MTJ. The TMR ratio of the structure strongly depends on the bias voltage, reaching values up to ∼45% when the bias voltage is low (∼0.2 mV). In addition, the device exhibits intermediate TMR values, which correspond to non-collinear alignments of magnetization in the GaMnAs and the Fe layers. Such alignments are possible due to the presence of two magnetic easy axes both in both magnetic layers originating from their strong cubic magnetic anisotropy. The TMR states realized in such Fe/GaAlAs/GaMnAs MTJs are excellent candidates for use in multi-valued memory storage devices.
Self-assembly of graphene oxide coated soft magnetic carbonyl iron particles and their magnetorheology
Authors: Zhang W. L. , Choi H. J.
Published: February 2014

The surface of carbonyl iron (CI) microspheres was modified with graphene oxide (GO) as a coating material using 4-aminobenzoic acid as the grafting agent. The morphology, elemental composition, and magnetic properties of the GO-coated CI (GO/CI) particles were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry, respectively, confirming their composite formation. The magnetorheological (MR) performance of the GO/CI particle-based suspension was examined using a rotational rheometer connected to a magnetic field supply. The GO/CI particles suspension exhibited typical MR properties with increasing shear stress and viscosity depending on the applied magnetic field strength.
Magnetic properties of CeFe11−xCoxTi with ThMn12 structure
Authors: Zhou Chen , Pinkerton Frederick E. , Herbst J. F.
Published: February 2014

A series of novel alloys CeFe11−xCoxTi (0 ≤ x ≤ 11) with ThMn12 structure has been successfully prepared by melt-spinning. The Curie temperature Tc increases with Co content x, reaching a maximum of 689 °C at x = 9 and declining to 664 °C at complete Co filling (x = 11). The room temperature saturation magnetization 4πMs and magnetocrystalline anisotropy Ha have been estimated by fitting the first quadrant demagnetization curve with the Stoner-Wohlfarth model. 4πMs first increases with increasing Co up to x = 3, then decrease. Ha has a complex dependence on Co content, which is indicative of a change in the easy magnetization direction from axis to plane and back as the Co content increases.
On the homogenization of turbulent flow structures in the wake of a model wind turbine
Authors: Singh Arvind , Howard Kevin B. , Guala Michele
Published: February 2014

The structure of flow turbulence, measured experimentally, in the wake of a model wind turbine is investigated here through higher order scale-dependent statistics of the velocity increments and compared to the smooth wall turbulent boundary layer (base flow) case. The wind turbine wake flow is observed to possess higher turbulent kinetic energy, when compared to the base flow, though it contains more homogenized scale-dependent velocity increments, as confirmed via magnitude cumulant analysis of the streamwise velocities. Along with a reduction in intermittency (a measure of inhomogeneity) in the wake of the wind turbine, the asymmetry of the probability density functions of the velocity increments is also observed to be reduced. This is interpreted in terms of scale decoupling mechanisms and attenuating interactions and non-local energy transfer. In other words, wind turbines reduce the intermittency and asymmetry in the wake flow by breaking and/or deflecting the large-scale flow structures of the incoming flow, thus rendering the structure of the velocity fluctuations more homogenized as compared to the base flow. Experiments were conducted in a large scale, boundary layer wind tunnel at the St. Anthony Falls Laboratory.
Linking lipid architecture to bilayer structure and mechanics using self-consistent field modelling
Authors: Pera H. , Kleijn J. M. , Leermakers F. A. M.
Published: February 2014

To understand how lipid architecture determines the lipid bilayer structure and its mechanics, we implement a molecularly detailed model that uses the self-consistent field theory. This numerical model accurately predicts parameters such as Helfrichs mean and Gaussian bending modulus kc and \documentclass[12pt]{minimal}\begin{document}$\bar{k}$\end{document}k¯ and the preferred monolayer curvature \documentclass[12pt]{minimal}\begin{document}$J_0^m$\end{document}J0m, and also delivers structural membrane properties like the core thickness, and head group position and orientation. We studied how these mechanical parameters vary with system variations, such as lipid tail length, membrane composition, and those parameters that control the lipid tail and head group solvent quality. For the membrane composition, negatively charged phosphatidylglycerol (PG) or zwitterionic, phosphatidylcholine (PC), and -ethanolamine (PE) lipids were used. In line with experimental findings, we find that the values of kc and the area compression modulus kA are always positive. They respond similarly to parameters that affect the core thickness, but differently to parameters that affect the head group properties. We found that the trends for \documentclass[12pt]{minimal}\begin{document}$\bar{k}$\end{document}k¯ and \documentclass[12pt]{minimal}\begin{document}$J_0^m$\end{document}J0m can be rationalised by the concept of Israelachivili's surfactant packing parameter, and that both \documentclass[12pt]{minimal}\begin{document}$\bar{k}$\end{document}k¯ and \documentclass[12pt]{minimal}\begin{document}$J_0^m$\end{document}J0m change sign with relevant parameter changes. Although typically \documentclass[12pt]{minimal}\begin{document}$\bar{k}<0$\end{document}k¯<0, membranes can form stable cubic phases when the Gaussian bending modulus becomes positive, which occurs with membranes composed of PC lipids with long tails. Similarly, negative monolayer curvatures appear when a small head group such as PE is combined with long lipid tails, which hints towards the stability of inverse hexagonal phases at the cost of the bilayer topology. To prevent the destabilisation of bilayers, PG lipids can be mixed into these PC or PE lipid membranes. Progressive loading of bilayers with PG lipids lead to highly charged membranes, resulting in \documentclass[12pt]{minimal}\begin{document}$J_0^m \gg 0$\end{document}J0m≫0, especially at low ionic strengths. We anticipate that these changes lead to unstable membranes as these become vulnerable to pore formation or disintegration into lipid disks.
Thermodiffusion in concentrated ferrofluids: Experimental and numerical results on magnetic thermodiffusion
Authors: Sprenger Lisa , Lange Adrian , Odenbach Stefan
Published: February 2014

Ferrofluids consist of magnetic nanoparticles dispersed in a carrier liquid. Their strong thermodiffusive behaviour, characterised by the Soret coefficient, coupled with the dependency of the fluid's parameters on magnetic fields is dealt with in this work. It is known from former experimental investigations on the one hand that the Soret coefficient itself is magnetic field dependent and on the other hand that the accuracy of the coefficient's experimental determination highly depends on the volume concentration of the fluid. The thermally driven separation of particles and carrier liquid is carried out with a concentrated ferrofluid (φ = 0.087) in a horizontal thermodiffusion cell and is compared to equally detected former measurement data. The temperature gradient (1 K/mm) is applied perpendicular to the separation layer. The magnetic field is either applied parallel or perpendicular to the temperature difference. For three different magnetic field strengths (40 kA/m, 100 kA/m, 320 kA/m) the diffusive separation is detected. It reveals a sign change of the Soret coefficient with rising field strength for both field directions which stands for a change in the direction of motion of the particles. This behaviour contradicts former experimental results with a dilute magnetic fluid, in which a change in the coefficient's sign could only be detected for the parallel setup. An anisotropic behaviour in the current data is measured referring to the intensity of the separation being more intense in the perpendicular position of the magnetic field: ST‖ = −0.152 K−1 and ST⊥ = −0.257 K−1 at H = 320 kA/m. The ferrofluiddynamics-theory (FFD-theory) describes the thermodiffusive processes thermodynamically and a numerical simulation of the fluid's separation depending on the two transport parameters ξ‖ and ξ⊥ used within the FFD-theory can be implemented. In the case of a parallel aligned magnetic field, the parameter can be determined to ξ‖ = {2.8; 9.1; 11.2} × 10−11 · D‖ kg/(A2m) for the different field strengths and in dependence on the magnetic diffusion coefficient D‖. An adequate fit in the perpendicular case is not possible, by ξ⊥ = 1 × 10−17 kg/(Am2) a rather good agreement between numerical and experimental data can be found for a field strength of 40 kA/m, a change in the coefficient's sign in the perpendicular setup is not numerically determinable via this theory. The FFD-theory is only partly applicable to calculate the concentration profile in concentrated magnetic fluids established due to a temperature gradient and magnetic field applied.
The interaction between viscous fingering and wrinkling in elastic-walled Hele-Shaw cells
Authors: Pihler-Puzović D. , Juel A. , Heil M.
Published: February 2014

The development of viscous fingers in circular Hele-Shaw cells is a classical and widely studied fluid mechanical problem. The introduction of wall elasticity (via the replacement of one of the bounding plates by an elastic membrane) can weaken or even suppress the fingering instability, but it also makes the system susceptible to additional solid-mechanical instabilities. We show that in elastic-walled Hele-Shaw cells that are bounded by sufficiently thin elastic sheets the (fluid-based) viscous fingering instability can arise concurrently with a (solid-based) wrinkling instability. We study the interaction between these distinct instabilities, using a theoretical model that couples the depth-averaged lubrication equations for the fluid flow to the Föppl-von Kármán equations, which describe the deformation of the thin elastic sheet. We employ a linear stability analysis to determine the growth rate of non-axisymmetric perturbations to the axisymmetrically expanding bubble, and perform direct numerical simulations to study the nonlinear interactions between the instabilities. We show that the system's behaviour may be characterised by a non-dimensional parameter that indicates the strength of the fluid-structure interaction. For small [large] values of this parameter, the system's behaviour is dominated by viscous fingering [wrinkling], with strong interactions between the two instabilities arising in an intermediate regime.
The aqueous viscous drag of a contracting open surface
Authors: Cohen Fredric S. , Ryham Rolf J.
Published: February 2014

A problem for fluid flow around an axisymmetric spherical surface with a hole is presented to characterize pore dynamics in liposomes. A rotational stream function for the contraction of a punctured plane region is obtained and is used in the perturbation expansion for a stream function in the case of a spherical surface with a hole of small radius compared to the spherical radius. The Rayleigh dissipation function is calculated and used to infer the aqueous friction induced by the contraction of the hole. The theoretical aqueous friction coefficient is compared with one derived from experimental data, and they are in agreement.
Internal-strain effect on the valence band of strained silicon and its correlation with the bond angles
Authors: Inaoka Takeshi , Yanagisawa Susumu , Kadekawa Yukihiro
Published: February 2014

By means of the first-principles density-functional theory, we investigate the effect of relative atom displacement in the crystal unit cell, namely, internal strain on the valence-band dispersion of strained silicon, and find close correlation of this effect with variation in the specific bond angles due to internal strain. We consider the [111] ([110]) band dispersion for (111) ((110)) biaxial tensility and [111] ([110]) uniaxial compression, because remarkably small values of hole effective mass m* can be obtained in this dispersion. Under the practical condition of no normal stress, biaxial tensility (uniaxial compression) involves additional normal compression (tensility) and internal strain. With an increase in the internal-strain parameter, the energy separation between the highest and second-highest valence bands becomes strikingly larger, and the highest band with conspicuously small m* extends remarkably down to a lower energy region, until it intersects or becomes admixed with the second band. This is closely correlated with the change in the specific bond angles, and this change can reasonably explain the above enlargement of the band separation.
Hypersonic band gap in an AlN-TiN bilayer phononic crystal slab
Authors: Hemon S. , Akjouj A. , Soltani A. , Pennec Y. , El Hassouani Y. , Talbi A. , Mortet V. , Djafari-Rouhani B.
Published: February 2014

We show both theoretically and experimentally the existence of a complete band gap in a phononic crystal (PnC) constituted by periodical air holes drilled in a solid bi-layer slab. The composite slab is formed with an aluminum nitride (AlN) layer deposited on a titanium nitride (TiN) thin metallic film. Indeed, AlN slabs are of great interest in many technological applications, in particular, owing to the capabilities of AlN as a complementary metal-oxide-semiconductor compatible material for integration in piezoelectric radio frequency filters (thin-film bulk acoustic resonator technology). The TiN layer was chosen as a buffer to enable small lattice mismatch with AlN, thus resulting in highly c-axis oriented and low stresses at the interface. We calculate the band structure of the crystal by using a finite element method and discuss the frequency and width of the band gap as a function of the thicknesses of both layers and the shape of the holes, i.e., from cylindrical to conical. The introduction of the TiN slab contributes to slowly widen the band gap. The band gap narrows when the holes become conical and closes when the radius of one face in the cone exceeds by 15% the radius of the other face. Experimentally, the measurement of the elastic wave transmission through eight rows of the bi-layer PnC shows a band gap around 950 MHz with an attenuation higher than 20 dB. The experimental results are well reproduced by the simulations provided the conical shape of the air inclusions is taken into account.
Growth of homogeneous single-layer graphene on Ni-Ge binary substrate
Authors: Wang Gang , Chen Da , Lu Zitong , Guo Qinglei , Ye Lin , Wei Xing , Ding Guqiao , Zhang Miao , Di Zengfeng , Liu Su
Published: February 2014

In contrast to the commonly used chemical vapor deposition growth that leads to multilayer graphene formation by carbon segregation from the Ni bulk, we designed a Ni-Ge binary system to directly grow graphene film on Ni-Ge binary substrate, via chemical vapor deposition with methane and hydrogen gas as precursors. Our system fully overcomes the fundamental limitations of Ni and yields homogenous single layer graphene over large areas. The chemical vapor deposition growth of graphene on Ni-Ge binary substrate shows that self limiting monolayer graphene growth can be obtained on these substrate.
Magnetic field sensing based on tilted fiber Bragg grating coated with nanoparticle magnetic fluid
Authors: Yang Dexing , Du Lei , Xu Zengqi , Jiang Yajun , Xu Jian , Wang Meirong , Bai Yang , Wang Haiyan
Published: February 2014

A magnetic field sensor based on a tilted fiber Bragg grating (TFBG) coated with magnetic fluid is proposed and demonstrated experimentally. The sensing element is made by injecting the magnetic fluid into a capillary tube which contains a TFBG. The resonant wavelengths of the cladding modes of TFBG shift by varying the magnetic field which is perpendicular to the axis of TFBG. The results indicate that the resonant wavelength shifts of the cladding modes show a nonlinear dependence on the magnetic field. As the magnetic field increases to 32 mT, the largest resonant wavelength shift reaches to 106 pm. Moreover, this sensor shows good repeatability when it is used for magnetic field sensing.
Direct imaging of enhanced current collection on grain boundaries of Cu(In,Ga)Se2 solar cells
Authors: Kim JunHo , Kim SeongYeon , Jiang Chun-Sheng , Ramanathan Kannan , Al-Jassim Mowafak M.
Published: February 2014

We report on direct imaging of current collection by performing conductive atomic force microscopy (C-AFM) measurement on a complete Cu(In,Ga)Se2 solar cell. The localized current was imaged by milling away the top conductive layer of the device by repeated C-AFM scans. The result exhibits enhanced photocurrent collection on grain boundaries (GBs) of CIGS films, consistent with the argument for electric-field-assisted carrier collection on the GBs.
Cyclic performance of viscoelastic dielectric elastomers with solid hydrogel electrodes
Authors: Bai Yuanyuan , Jiang Yanhui , Chen Baohong , Chiang Foo Choon , Zhou Yongcun , Xiang Feng , Zhou Jinxiong , Wang Hong , Suo Zhigang
Published: February 2014

Hydrogels containing electrolyte can work as ionic conductors to actuate dielectric elastomer (DE) artificial muscles. Based on a popular design of a circular actuator, we study theoretically and experimentally the cyclic performance of acrylic DE actuators with solid hydrogel electrodes. The viscoelasticity of solid electrodes constrains the maximum strain that is attainable for one cycle of triangular voltage, and it also diminishes the accumulated increment of the maximum strain after many cycles of loadings.
Achieving high brightness of silicon nanocrystal light-emitting device with a field-effect approach
Authors: Chen Jia-Rong , Wang Dong-Chen , Hao Hong-Chen , Lu Ming
Published: February 2014

We report a field-effect approach to enhance the electroluminescence (EL) from a model Si nanocrystal light-emitting device (Si-NC LED). The field effects are established within the carrier injection regions of the LEDs via introducing an i-type Si layer on the top of active layer and an Al2O3 layer between the active layer and the Si substrate. The fields are consistent in polarity with the forwardly biased electric field within the LEDs. One order of magnitude increases in the EL intensity from Si-NC LED are readily achieved after introducing the field effects.
Dipolar field effects on the critical current for spin transfer switch of iron and permalloy nanoelements
Authors: Oliveira L. L. , Dantas J. T. S. , Souza R. M. , Carriço A. S. , Dantas Ana L.
Published: February 2014

We report a theoretical study of dipolar effects on the switching current density of soft ferromagnetic elliptical nanoelements. Relevant changes on the critical current value are found according to the orientation of the magnetization and the spin polarization with the major axis. We show that the critical current density may be reduced by as much as 92% for thin nanoelements magnetized along the minor axis direction, using in-plane spin polarization parallel to the magnetization.
Growth and characterization of Pt-protected Gd5Si4 thin films
Authors: Hadimani R. L. , Mudryk Y. , Prost T. E. , Pecharsky V. K. , Gschneidner K. A. , Jiles D. C.
Published: February 2014

Successful growth and characterization of thin films of giant magnetocaloric Gd5(SixGe1−x)4 were reported in the literature with limited success. The inherent difficulty in producing this complex material makes it difficult to characterize all the phases present in the thin films of this material. Therefore, thin film of binary compound of Gd5Si4 was deposited by pulsed laser deposition. It was then covered with platinum on the top of the film to protect against any oxidation when the film was exposed to ambient conditions. The average film thickness was measured to be approximately 350 nm using a scanning electron microscopy, and the composition of the film was analyzed using energy dispersive spectroscopy. X-ray diffraction analysis indicates the presence of Gd5Si4 orthorhombic structure along with Gd5Si3 secondary phase. The transition temperature of the film was determined from magnetic moment vs. temperature measurement. The transition temperature was between 320 and 345 K which is close to the transition temperature of the bulk material. Magnetic moment vs. magnetic field measurement confirmed that the film was ferromagnetic below 342 K.
The Regional Economic Impact of More Graduates in the Labour Market: A ‘Micro-to-Macro’ Analysis for Scotland
Authors: Hermannsson Kristinn , Lisenkova Katerina , Lecca Patrizio , Swales J Kim , McGregor Peter G
Published: February 2014

This paper explores the system-wide impact of graduates on the regional economy. Graduates enjoy a significant wage premium, often interpreted as reflecting their greater productivity relative to nongraduates. If this is so there is a clear and direct supply-side impact of higher education institution (HEI) activities on regional economies. We use an HEI-disaggregated computable general equilibrium model of Scotland to estimate the impact of the growing proportion of graduates in the Scottish labour force that is implied by the current participation rate and demographic change, taking the graduate wage premium in Scotland as an indicator of productivity enhancement. While the detailed results vary with alternative assumptions about the extent to which wage premia reflect productivity, they do suggest that the long-term supply-side impacts of HEIs provide a significant boost to regional GDP. Furthermore, the results suggest that the supply-side impacts of HEIs are likely to be more important than the expenditure impacts that are the focus of most HEI impact studies.
The Effect of Globalization on the Distribution of Taxes and Social Expenditures in Europe: Do Welfare State Regimes Matter?
Authors: Onaran Özlem , Boesch Valerie
Published: February 2014

This paper estimates the effect of globalization on the implicit tax rates (ITRs) on capital income, labor income, and consumption, and the share of social protection expenditures in total public expenditures in Western and Eastern Europe. It tests the coexistence of efficiency and compensation effects of globalization on the expenditure and the revenue sides of government budgets. In Western Europe, globalization leads to an increase in social expenditures; however, these expenditures are to an increasing extent financed by taxes on labor. There are important differences between the welfare states. In the conservative regimes, both social expenditures and taxes on labor increase due to globalization. In the social-democratic regimes social expenditures are not affected by globalization, but the ITR on labor increases, whereas ITRs on capital and consumption decrease as a result of globalization. In the liberal regimes, the ITR on labor is rising, while social expenditures are declining. In the southern welfare regime globalization does not have any significant effects on the distribution of taxes or social spending. In Eastern Europe, in the Baltic states globalization leads to a decrease in social spending, whereas in the other Central and Eastern European New Member States (postcommunist European regimes) there is an upward convergence in social spending due to globalization. The ITRs on consumption decrease due to globalization in the postcommunist European regimes, whereas in the Baltic states there is no robust significant effect of globalization on taxes.
Healthy Land? An Examination of the Area-Level Association between Brownfield Land and Morbidity and Mortality in England
Authors: Bambra Clare , Robertson Steve , Kasim Adetayo , Smith Joe , Cairns-Nagi Joanne Marie , Copeland Alison , Finlay Nina , Johnson Karen
Published: February 2014

It is increasingly understood that the physical environment remains an important determinant of area-level health and spatial and socioeconomic health inequalities. Existing research has largely focused on the health effects of differential access to green space, the proximity of waste facilities, or air pollution. The role of brownfield—or previously developed—land has been largely overlooked. This is the case even in studies that utilise multiple measures of environmental deprivation. This paper presents the results of the first national-scale empirical examination of the association between brownfield land and morbidity and mortality, using data from England. Census Area Statistical ward-level data on the relative proportion of brownfield land (calculated from the 2009 National Land Use Database), standardised morbidity (2001 Census measures of ‘not good’ general health and limiting long-term illness), and premature (aged under 75 years) all-cause mortality ratios from 1998/99 to 2002/03 were examined using linear mixed modelling (adjusting for potential environmental, socioeconomic, and demographic confounders). A significant and strong, adjusted, area-level association was found between brownfield land and morbidity: People living in wards with a high proportion of brownfield land are significantly more likely to suffer from poorer health than those living in wards with a small proportion of brownfield land. This suggests that brownfield land could potentially be an important and previously overlooked independent environmental determinant of population health in England. The remediation and redevelopment of brownfield land should therefore be considered as a public health policy issue.
Informal and Formal Sources of Knowledge as Drivers of Regional Innovation: Digging a Little Further into Complexity
Authors: Barrutia Jose M , Echebarria Carmen , Apaolaza-Ibáñez Vanessa , Hartmann Patrick
Published: February 2014

We study the combined effect of formal (FSK) and informal (ISK) sources of knowledge on European regional innovation performance. Our findings show that the effect of the two sources of knowledge on innovation performance is not simple and linear. First, both sources of knowledge have an interaction effect on innovation performance (ie, the effect of FSK on regional innovation depends on the level of access to ISK in the region, and vice versa). Second, while the effect of ISK is linear (although different for each region), the effect of the FSK (which is more intensive in monetary, time, effort, and opportunity costs) has a diminishing-returns form, and achieves a saturation point at high levels of use of FSK. Our findings also show that the balanced access to both types of sources is important and that, for instance, regions with limited access to ISK should not expect miraculous effects from high levels of FSK. To the best of our knowledge, no previous research has been reported which has empirically studied the combined effect of both sources of knowledge at a European regional level.
International Migration and Local Emplacement: Everyday Place-Making Practices of Skilled Migrants in Oslo, Norway
Authors: van Riemsdijk Micheline
Published: February 2014

Literatures on skilled migration have predominantly investigated migration flows at the global and international scale, paying less attention to the local experiences of skilled migrants. Recently, scholars have called for studies that locally ground literatures on transnationalism and diasporas through studies of everyday practices. Such a perspective provides a more nuanced understanding of the local incorporation of skilled migrants and local politics of belonging. Drawing on an empirical study of foreign-born information technology specialists in Oslo, Norway, this paper investigates the ways in which skilled migrants create local spaces and places of belonging, and the actors and institutions that are involved in this place-making process. In particular, this paper brings together literatures on international migration, place, and belonging to provide insights into the local incorporation of skilled migrants. The findings underline the salience of history and locality in geographies of belonging, and the necessity to address the experiences of “ordinary” skilled migrants in integration debates.
Travel Distances in Daily Travel and Long-Distance Travel: What Role is Played by Urban Form?
Authors: Holz-Rau Christian , Scheiner Joachim , Sicks Kathrin
Published: February 2014

There is a lot of research on spatial differences in travel behaviour, specifically on travel distances. This research suggests that the distances travelled by the inhabitants of municipalities with lower population and neighbourhoods with lower density and less mixed land use are longer than those travelled by the inhabitants of cities with higher population, high density, and greater mixed land use. However, related studies focus mainly on daily travel. In this paper we study travel distances in daily trips based on random day trip diaries and long-distance trips for private and business purposes based on retrospective questions in the same questionnaire, asking about “longer journeys with overnight stay” within three months of the survey. We use Heckman models and ordinary least squares regressions to study the effects of municipality size classes based on population, population density, and land-use mix, while controlling for sociodemographics. We find distances travelled on long-distance trips and daily trips to be affected by sociodemographics in much the same way, while spatial effects affect distances travelled on daily and long-distance trips mostly in different directions. Residents of small municipalities and low-density neighbourhoods make fewer and/or shorter long-distance journeys than those living in large cities and high-density neighbourhoods, but the latter travel shorter distances in their daily lives.
Natura Urbans, Natura Urbanata: Ecological Urbanism, Circulation, and the Immunization of Nature
Authors: Adams Ross Exo
Published: February 2014

While ‘ecological urbanism’ promises the introduction of a new generation of apparatuses, exacting control ever more deeply within the social whole, the logic by which such networks of power operate has remained largely unchanged since the 19th century. This paper will demonstrate the persistence of this logic by placing ecological urbanism within a genealogy of the concept of urbanization. Looking at the work of Spanish civil engineer, Ildfonso Cerdá, I will examine his remarkably prescient theory in which he proposed to replace what he saw as the ‘anachronistic’ ciudad (city) with the ‘modern’ figure of the urbe—a generic, scaleless template of territorialization engulfed in expansive urbanización. The first part of the paper focuses on Cerdá's concept of vialidad (roughly, ‘circulation’), which formed the basis of his theory of urbanization and provided its origin in ‘nature’ itself. Urbanization was an effort to free mankind from political domination and recover it's ‘natural’ destiny by unifying a latent global society in a single, interconnected global urbe. However, not only did Cerdá's theory introduce a new, far more pervasive technological relationship of power between government and population; it also set free to circulate what was previously fixed in the space and form of the city: the apparatus. In the second part of the paper I reexamine ecological urbanism with regard to the founding relationship between urbanization and nature. Now, because it is nature that has become pathological to humanity, it is nature which must be immunized. Ecological urbanism thus reinvigorates the capacity of the urban to stave off the end of the world, not only by rhetorically reaffirming the natural origins of urbanization but also by inverting this relationship: ecological urbanism proposes to reconstruct nature as urbanization.
What is a Destituent Power?
Authors: Agamben Giorgio
Published: February 2014

The following essay by Giorgio Agamben is based on a lecture given in central France in the summer of 2013. Responding directly to recent occupations and insurrections—from Cairo and Istanbul to London and New York City—Agamben builds upon his existing work in order to develop and clarify his understanding of the political and, in particular, the notion of destituent power ( potenza destituente). In contrast to attempts to affirm a constituent power independent of a relation to constituted power, which for Agamben both reproduce the governmental structure of the exception and represent the apex of metaphysics, destituent power outlines a force that, in its very constitution, deactivates the governmental machine. For Agamben, it is in the sensible elaboration of the belonging together of life and form, being and action, beyond all relation, that the impasse of the present will be overcome. Ultimately, Agamben points not only towards what it means to become Ungovernable, but towards the potential of staying so.
Comparison of objective measures of pork colour traits during ageing of the longissimus muscle from pigs housed organically and conventionally
Authors: Álvarez-Rodríguez J. , Tor M. , Cubiló D. , Ripoll G. , Babot D. , Villalba D.
Published: February 2014

Pigs raised conventionally (n = 56) and indoors organically (n = 47) from different three-way crossbred genotypes were used to assess the capacity of pork colour attributes during ageing to discriminate between two methods of rearing pigs. Instrumental colour characteristics were measured on L. thoracis muscle from day 1 to 7 of storage, and the relative contents of metmyoglobin (MMb) and oxymyoglobin (MbO2) were estimated. The yellowness and chroma indices were lower in conventional than organic pork at all sampling times except on day 3 of storage. Lightness and hue angle were lower, whereas redness index was greater, in conventional than organic pork during all days of storage. Using MMb rather than MbO2 could be useful to highlight myoglobin oxidation in pork meat because it was weakly correlated with the measured CIELab colour attributes. Despite the differences in instrumental colour attributes, discrimination between conventional and organic (not free-ranging) pig husbandry was not possible. However, 3 days of storage combined the best colour (low hue angle and high redness index) and haeminic pigment balance (low MMb and high MbO2).
Effect of dietary inclusion level of a multi-species probiotic on broiler performance and two biomarkers of their caecal ecology
Authors: Mountzouris Konstantinos C. , Palamidi Irida , Tsirtsikos Panagiotis , Mohnl Michaela , Schatzmayr Gerd , Fegeros Konstantinos
Published: February 2014

The effect of the dietary inclusion level of a three-species probiotic on broiler performance, nutrient digestibility, caecal microbiota composition and volatile fatty acid (VFA) pattern was evaluated. Day-old Cobb broilers (n = 448) were allocated in four treatments for 6 weeks. Each treatment had four replicates (two per gender) of 28 broilers each. Depending on the type of addition per kg basal diet, treatments were C (no other addition), PL (108 colony forming units of probiotic), PH (109 colony forming units of probiotic) and A (2.5 mg avilamycin). Overall bodyweight gain was better (P = 0.002) in PL and PH than in the control (2082 g) by 8.7% and 7.5%, respectively, while treatment PL did not differ from A (2341 g), which showed the highest bodyweight gain. The ileal and total-tract apparent digestibility of DM and the apparent metabolisable energy content corrected for N improved linearly (P ≤ 0.05) with the probiotic level. Fluorescent in situ hybridisation analysis showed caecal Bifidobacterium levels to increase linearly (P = 0.006) with the probiotic level. Probiotic administration resulted in altered caecal VFA patterns compared with the control. Gender effects (P ≤ 0.05) were noted for caecal levels of C. histolyticum group, Bacteroides fragilis group and Streptococcus spp., while interactions (P ≤ 0.05) of treatment with gender were seen for Bifidobacterium and all VFA components, except for acetate. In conclusion, beneficial effects on bodyweight gain, DM digestibility, apparent metabolisable energy content corrected for N, caecal Bifidobacterium levels and VFA patterns were noted with both probiotic inclusion levels.
Eucalypt forests as indicators of the gradients within the central Queensland serpentine landscape of Australia
Authors: Hendry Rebecca A. , Wormington Kevin Ray
Published: February 2014

The eucalypt forests of the central Queensland serpentine landscape on the eastern coast of Australia are dominated by two overstorey species. These are Eucalyptus fibrosa F.Muell. subsp. fibrosa, the most dominant tree occurring throughout the landscape, and Corymbia xanthope A.R.Bean & Brooker, a serpentine endemic species which has a more restricted distribution. We hypothesised that the structure and foliage elements of the eucalypt forests could be used as biological indicators of the severity of the serpentine soils. This was tested by surveying 30 plots (50 × 20 m) within the upland landform patterns of the central Queensland serpentine landscape. The structure of the forests and abundance of the species were recorded and foliage samples from the dominant tree E. fibrosa subp. fibrosa were collected and analysed for metal and nutrient content. Soil samples from each site were collected and analysed for major cations, bio-available metals and fertility. Analysis of the data showed that there are significant correlations between the structure of the eucalypt forests and the landform patterns and soil chemistry. The relative basal area of C. xanthope is a useful measure of the severity of the serpentine soils and correlates to the soil Mg : Ca quotients. The tree E. fibrosa subsp. fibrosa was found to regulate its uptake of soil elements and cannot be used as an indicator of soil elements.