bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Black Tea and Caffeine on Regional Cerebral Blood Flow Measured with Arterial Spin Labeling
Authors: Vidyasagar Rishma , Greyling Arno , Draijer Richard , Corfield Douglas R , Parkes Laura M
Published: March 2013

Black tea consumption has been shown to improve peripheral vascular function. Its effect on brain vasculature is unknown, though tea contains small amounts of caffeine, a psychoactive substance known to influence cerebral blood flow (CBF). We investigated the effects on CBF due to the intake of tea components in 20 healthy men in a double-blinded, randomized, placebo-controlled study. On separate days, subjects received a single dose of 184 mg caffeine (equivalent to one strong espresso coffee), 2,820 mg black tea solids containing 184 mg caffeine (equivalent to 6 cups of tea), 2,820 mg decaffeinated black tea solids, or placebo. The CBF and cerebrovascular reactivity (CVR) to hypercapnia were measured with arterial spin labeled magnetic resonance imaging (MRI) before and 2 hours after administration. We found a significant global reduction with caffeine (20%) and tea (21%) in gray matter CBF, with no effect of decaffeinated tea, suggesting that only caffeine influences CBF acutely. Voxelwise analysis revealed the effect of caffeine to be regionally specific. None of the interventions had an effect on CVR. Additional research is required to conclude on the physiologic relevance of these findings and the chronic effects of caffeine and tea intake on CBF.
FSL-61 is a 6-nitroquinolone fluorogenic probe for one-electron reductases in hypoxic cells
Authors: Su Jiechuang , Guise Christopher P. , Wilson William R.
Published: March 2013

One-electron reductases that reduce nitro compounds in hypoxic human tumour cells are poorly characterized, but are important for targeting hypoxia with nitroaromatic prodrugs. Fluorogenic probes with defined reductase profiles are needed to interrogate the activity of these enzymes in intact cells. In the present paper, we report a 6-nitroquinolone ester (FSL-61) as a fluorogenic probe for POR (NADPH:cytochrome P450 oxidoreductase) activity under hypoxia, and demonstrate its suitability of monitoring POR by flow cytometry. Reduction of FSL-61 by purified recombinant human POR generated the corresponding hydroxylamine, which was non-fluorescent, but was reduced further to the fluorescent amine in cells. Hydrolysis of the ester side chain facilitated cellular entrapment, enabling detection of heterogeneous POR expression in mixed populations of cells. In addition to POR, forced expression of three other diflavin reductases [MTRR (methionine synthase reductase), NDOR1 (NADPH-dependent diflavin oxidoreductase 1) and NOS2A (nitric oxide synthase 2A)] or NADPH:adrenoredoxin oxidoreductase in HCT116 cells significantly increased hypoxic activation of FSL-61. This reductase profile is similar to that for the dinitrobenzamide prodrug PR-104A under hypoxia, and fluorogenic metabolism of FSL-61 correlated significantly with PR-104A activation in a panel of 22 human tumour cell lines. The present study thus demonstrates the utility of FSL-61 for rapid and non-destructive interrogation of the activity of one-electron reductases in hypoxic cells at the single-cell level.
Human mesenchymal stem cells derived from adipose tissue reduce functional and tissue damage in a rat model of chronic renal failure
Authors: Villanueva Sandra , Carreño Juan E. , Salazar Lorena , Vergara César , Strodthoff Rocío , Fajre Francisca , Céspedes Carlos , Sáez Pablo J. , Irarrázabal Carlos , Bartolucci Jorge , Figueroa Fernando , Vio Carlos P.
Published: March 2013

Therapeutic approaches for CKD (chronic kidney disease) have been able to reduce proteinuria, but not diminish the disease progression. We have demonstrated beneficial effects by injection of BM (bone marrow)-derived MSCs (mesenchymal stem cells) from healthy donors in a rat model with CKD. However, it has recently been reported that BM-MSCs derived from uraemic patients failed to confer functional protection in a similar model. This suggests that autologous BM-MSCs are not suitable for the treatment of CKD. In the present study, we have explored the potential of MSCs derived from adipose tissue (AD-MSCs) as an alternative source of MSCs for the treatment of CKD. We have isolated AD-MSCs and evaluated their effect on the progression of CKD. Adult male SD (Sprague–Dawley) rats subjected to 5/6 NPX (nephrectomy) received a single intravenous infusion of 0.5×106 AD-MSCs or MSC culture medium alone. The therapeutic effect was evaluated by plasma creatinine measurement, structural analysis and angiogenic/epitheliogenic protein expression. AD-MSCs were detected in kidney tissues from NPX animals. This group had a significant reduction in plasma creatinine levels and a lower expression of damage markers ED-1 and α-SMA (α-smooth muscle actin) (P<0.05). In addition, treated rats exhibited a higher level of epitheliogenic [Pax-2 and BMP-7 (bone morphogenetic protein 7)] and angiogenic [VEGF (vascular endothelial growth factor)] proteins. The expression of these biomarkers of regeneration was significantly related to the improvement in renal function. Although many aspects of the cell therapy for CKD remain to be investigated, we provide evidence that AD-MSCs, a less invasive and highly available source of MSCs, exert an important therapeutic effect in this pathology.
Endoscopic Dacryocystorhinostomy
Authors: Strong E. Bradley
Published: March 2013

External dacryocystorhinostomy was described in early 20th century. The introduction of nasal endoscopy and endoscopic sinus surgery in the 1980s paved the way for a transnasal endoscopic approach to lacrimal system. This article will review the indications and surgical techniques used for endoscopic dacryocystorhinostomy.
Note on intrinsic decay rates for abstract wave equations with memory
Authors: Lasiecka Irena , Messaoudi Salim A. , Mustafa Muhammad I.
Published: March 2013

In this paper we consider a viscoelastic abstract wave equation with memory kernel satisfying the inequality g′ + H(g) ⩽ 0, s ⩾ 0 where H(s) is a given continuous, positive, increasing, and convex function such that H(0) = 0. We shall develop an intrinsic method, based on the main idea introduced by Lasiecka and Tataru [“Uniform boundary stabilization of semilinear wave equation with nonlinear boundary dissipation,” Differential and Integral Equations 6, 507–533 (1993)], for determining decay rates of the energy given in terms of the function H(s). This will be accomplished by expressing the decay rates as a solution to a given nonlinear dissipative ODE. We shall show that the obtained result, while generalizing previous results obtained in the literature, is also capable of proving optimal decay rates for polynomially decaying memory kernels (H(s) ∼ sp) and for the full range of admissible parameters p ∈ [1, 2). While such result has been known for certain restrictive ranges of the parameters p ∈ [1, 3/2), the methods introduced previously break down when p ⩾ 3/2. The present paper develops a new and general tool that is applicable to all admissible parameters.
Lieb-Thirring trace inequalities and a question of Bourin
Authors: Hayajneh Saja , Kittaneh Fuad
Published: March 2013

In this paper, we propose some conjectures in order to solve one of the questions posed by Bourin regarding a special type of inequalities referred to as subadditivity inequalities in the case of the Hilbert-Schmidt norm. Some of these conjectures are settled affirmatively for special cases in an algorithmic way by using some number theory tools.
Oversized co-axial and cylindrical surface-wave oscillators with two-dimensional periodical grating (quasi-optical model)
Authors: Ginzburg N. S. , Malkin A. M. , Sergeev A. S. , Zaslavsky V. Yu.
Published: March 2013

Within the quasi-optical approach, we study nonlinear dynamics of co-axial and cylindrical surface-wave oscillators with two-dimensional periodic gratings. Electromagnetic fields in these structures are formed by a superposition of coupled quasi-optical wave-beams propagating in the azimuthal and longitudinal directions. Presence of the azimuthal wave-beams leads to a substantial spectrum rarefication of the modes with different azimuthal indices thus allowing their selective excitation by a large radius rectilinear hollow electron beam.
A new method to construct families of complex Hadamard matrices in even dimensions
Authors: Goyeneche D.
Published: March 2013

We present a new method for constructing affine families of complex Hadamard matrices in every even dimension. This method has an intersection with Diţă’s construction and generalizes Szöllősi's method. We extend some known families and present new ones existing in even dimensions. In particular, we find more than 13 millon inequivalent affine families in dimension 32. We also find analytical restrictions for any set of four mutually unbiased bases existing in dimension six and for any family of complex Hadamard matrices existing in every odd dimension.
Rigid motions: Action-angles, relative cohomology and polynomials with roots on the unit circle
Authors: Françoise J.-P. , Garrido P. L. , Gallavotti G.
Published: March 2013

Revisiting canonical integration of the classical solid near a hyperbolic or elliptic uniform rotation, normal canonical coordinates p, q are constructed so that the Hamiltonian becomes a function (“normal form”) of x+ = pq or of x− = p2 + q2: the two cases are treated simultaneously distinguishing them, respectively, by a label a = ±, in terms of various power series with coefficients which are shown to be polynomials in a variable \documentclass[12pt]{minimal}\begin{document}$r^2_a$\end{document}ra2 depending on the inertia moments. The normal forms are derived via the analysis of a relative cohomology problem and shown to be obtainable without reference to the construction of the normal coordinates via elliptic integrals (unlike the derivation of the normal coordinates p, q). Results and conjectures also emerge about the properties of the above polynomials and the location of their roots. In particular a class of polynomials with all roots on the unit circle arises.
Mathematics of small stochastic reaction networks: A boundary layer theory for eigenstate analysis
Authors: Mjolsness Eric , Prasad Upendra
Published: March 2013

We study and analyze the stochastic dynamics of a reversible bimolecular reaction A + B ↔ C called the “trivalent reaction.” This reaction is of a fundamental nature and is part of many biochemical reaction networks. The stochastic dynamics is given by the stochastic master equation, which is difficult to solve except when the equilibrium state solution is desired. We present a novel way of finding the eigenstates of this system of difference-differential equations, using perturbation analysis of ordinary differential equations arising from approximation of the difference equations. The time evolution of the state probabilities can then be expressed in terms of the eigenvalues and the eigenvectors.
A hybrid plasmonic semiconductor laser
Authors: Costantini D. , Greusard L. , Bousseksou A. , De Wilde Y. , Habert B. , Marquier F. , Greffet J.-J. , Lelarge F. , Decobert J. , Duan G.-H. , Colombelli R.
Published: March 2013

We present a semiconductor-based approach to compensate plasmonic losses. The core idea is to employ an electrically pumped laser diode and to overlap its active region with the evanescent field of a surface plasmon wave. In order to keep the losses at a manageable level, we rely on hybrid waveguide modes stemming from the coupling of a dielectric and a plasmonic mode. The laser device we demonstrate operates—at telecom wavelengths—on such a hybrid plasmonic mode. The device operates by electrical injection at room temperature. The near-field imaging of the laser facet provides evidence of the stimulated emission into the hybrid mode and confirms the prediction of the numerical simulations.
Electron and ion kinetic effects on non-linearly driven electron plasma and ion acoustic waves
Authors: Berger R. L. , Brunner S. , Chapman T. , Divol L. , Still C. H. , Valeo E. J.
Published: March 2013

Fully non-linear kinetic simulations of electron plasma and ion acoustic waves (IAWs) have been carried out with a new multi-species, parallelized Vlasov code. The numerical implementation of the Vlasov model and the methods used to compute the wave frequency are described in detail. For the first time, the nonlinear frequency of IAWs, combining the contributions from electron and ion kinetic effects and from harmonic generation, has been calculated and compared to Vlasov results. Excellent agreement of theory with simulation results is shown at all amplitudes, harmonic generation being an essential component at large amplitudes. For IAWs, the positive frequency shift from trapped electrons is confirmed and is dominant for the effective electron-to-ion temperature ratio, Z Te/Ti ≳ 10 with Z as the charge state. Furthermore, numerical results demonstrate unambiguously the dependence [R. L. Dewar, Phys. Fluids 15, 712 (1972)] of the kinetic shifts on details of the distribution of the trapped particles, which depends in turn on the conditions under which the waves were generated. The trapped particle fractions and energy distributions are derived and, upon inclusion of harmonic effects, shown to agree with the simulation results, completing a consistent picture. Fluid models of the wave evolution are considered but prove unable to capture essential details of the kinetic simulations. Detrapping by collisions and sideloss is also discussed.
Monte Carlo charge transport and photoemission from negative electron affinity GaAs photocathodes
Authors: Karkare Siddharth , Dimitrov Dimitre , Schaff William , Cultrera Luca , Bartnik Adam , Liu Xianghong , Sawyer Eric , Esposito Teresa , Bazarov Ivan
Published: March 2013

High quantum yield, low transverse energy spread, and prompt response time make GaAs activated to negative electron affinity an ideal candidate for a photocathode in high brightness photoinjectors. Even after decades of investigation, the exact mechanism of electron emission from GaAs is not well understood. Here, photoemission from such photocathodes is modeled using detailed Monte Carlo electron transport simulations. Simulations show a quantitative agreement with the experimental results for quantum efficiency, energy distributions of emitted electrons, and response time without the assumption of any ad hoc parameters. This agreement between simulation and experiment sheds light on the mechanism of electron emission and provides an opportunity to design novel semiconductor photocathodes with optimized performance.
First principles study on InP (001)-(2 × 4) surface oxidation
Authors: Santosh K. C. , Wang Weichao , Dong Hong , Xiong Ka , Longo Roberto C. , Wallace Robert M. , Cho Kyeongjae
Published: March 2013

A theoretical study of the oxidation of InP(001)-(2 × 4) surface is performed using density functional theory methods. Our results on surface oxidation show that the oxygen adsorption does not produce any gap states in the bulk InP band gap, due to the saturation of surface In dangling bonds, whereas substitutional oxygen atoms produce gap states. This study also shows that the surface stability increases with the oxygen content, indicating a strong tendency for surface oxidation. Our results help to clarify the origin of surface gap states upon surface oxidation and provide an insight at the atomic level the mechanism of surface oxidation, which will assist in the understanding of the degradation of III-V devices upon oxygen exposure or interfacial oxidation with high dielectric constant oxides.
Non-monotonic dependence of the conductivity of carbon nanotube-filled elastomers subjected to uniaxial compression/decompression
Authors: Semeriyanov F. F. , Chervanyov A. I. , Jurk R. , Subramaniam K. , König S. , Roscher M. , Das A. , Stöckelhuber K. W. , Heinrich G.
Published: March 2013

Electrical resistance of the elastomeric material polychloroprene filled with multiwalled carbon nanotubes (CNTs) dispersed by using an imidazolium based ionic liquid has been measured experimentally and calculated theoretically, as a function of the applied compression/decompression force F. Both experimental and theoretical results show that the electrical resistance R of the composite exhibits non-monotonic dependence on F. This observed non-monotonic dependence R(F) is explained by different mechanisms of conductivity that are specific to the respective domains of the magnitude of the compression/decompression force F. At small F, the observed decrease of conductivity with increasing F is found to be caused by the change of an average contact distance between CNTs. At higher F, the observed increase of R with increasing F is caused by the dependence of the per-particle surface area on F. The experimentally observed dependence R(F) is adequately described by the developed theory that relies on establishing the exact relation between the CNT network structure and the electrical response of the composite. Theoretical dependence between the conductivity of the composite and the applied stress is obtained using the percolation model of the electrical conductivity of CNT network that shows excellent quantitative agreement with the experimental results.
A model for the double loop of ferroelectric polarization close to TC
Authors: Kliem Herbert , Leschhorn Andreas , Edtbauer Tobias
Published: March 2013

For ferroelectrics with a phase transition of the first order a double hysteresis loop of the polarization can be found close to TC. This behavior is explained using the Weiss field model taking into account that strain in the ferroelectric is induced by the polarization via the piezoeffect. The Weiss field model is looked at as a feedback loop where the polarization influences itself by the electrostatic interaction between the constituent dipoles.
Gate modulation on angle-resolved photoabsorption spectra of zigzag-edge graphene nanoribbons
Authors: Zhu Wen-Huan , Ding Guo-Hui , Dong Bing
Published: March 2013

Graphene nanoribbons (GNRs) exhibit novel and special electronic and optical properties with promising technological applications. The gate modulation on angle-resolved photoabsorption spectra of zigzag-edge GNRs (ZGNRs) is investigated based on the Hubbard model in the Hartree-Fock approximation. By examining the electron transition processes and the optical selection rules taking into account the Coulomb interaction effect, we demonstrate that the excitations from the edge states of ZGNRs are essential for the optical properties in the neutral case, and show the energy of the absorption peaks has the dispersion and splitting effects with increasing momentum transfer from the incident light. By modulating the chemical potential of ZGNRs, the intraband transitions which are forbidden for the neutral ZGNRs at zero temperature become important for the low energy optical properties, and a Drude peak of the optical conductivity emerges in the low frequency region.
On the relationship between small and large signal modulation capabilities in highly nonlinear quantum dot lasers
Authors: Gready D. , Eisenstein G. , Gioannini M. , Montrosset I. , Arsenijevic D. , Schmeckebier H. , Stubenrauch M. , Bimberg D.
Published: March 2013

The small signal modulation response of semiconductor lasers is commonly used to predict large signal modulation capabilities. Recent experiments suggest that this prediction may fail in some quantum dot (QD) lasers. We present a model supported by experiments, which shows that when the small signal modulation response is limited by gain compression and the gain is large, the laser can be modulated at very high bit rates. This effect is inherent to dynamics governing all semiconductor lasers but the conditions needed for high bit rate modulation in the presence of narrow small signal bandwidths are only obtainable in QD lasers.
Effects of carbon content on structural, magnetic, and electrical/thermal transport properties of antiperovskite compounds GaCxFe3
Authors: Lin S. , Wang B. S. , Tong P. , Hu L. , Huang Y. N. , Lu W. J. , Zhao B. C. , Song W. H. , Sun Y. P.
Published: March 2013

In this paper, we report the effects of carbon content on crystal structure, magnetic and electrical/thermal transport properties in antiperovskite compounds GaCxFe3 (0.15 ≤ x ≤ 0.3). Our experimental results indicate that all the physical properties we measured are sensitive to the carbon concentration for GaCxFe3. With decreasing the carbon content x, the Curie temperature (TC), saturated magnetization, and coercive force (HC) increase while the lattice constant, Debye temperature, and resistivity decrease gradually. Further analysis suggests that the serial GaCxFe3 can be a new kind of promising high-temperature soft magnetic material considering their high-TC (∼788 K) and low-HC (∼22 Oe). Interestingly, the low-temperature resistivity exhibits an abnormal semiconducting behavior below a characteristic temperature for each of GaCxFe3 (0.15 ≤ x ≤ 0.3). This abnormality of resistivity may be attributed to a combination of the renormalized electron-electron interaction and the weak-localization. Furthermore, the studies of the thermal transport and the Hall measurement suggest that the type of dominant carriers in GaCxFe3 changes gradually from hole- to electron-type with decreasing x.
The influence of individual lattice defects on the domain structure in magnetic antidot lattices
Authors: Hu X. K. , Sievers S. , Müller A. , Schumacher H. W.
Published: March 2013

We numerically and experimentally investigate the influence of single defects consisting of a missing antidot on the spin configurations in rectangular permalloy antidot lattices. The introduction of such lattice defects leads to the nucleation of complex domain structures after the decay of a saturating magnetic field. Micromagnetic simulations yield four typical domain configurations around the defect having distinct energy densities. The existence of the four spin configurations is confirmed by magnetic force microscopy on antidot lattices containing individual defects.
A new method for removing the blackout problem on reentry vehicles
Authors: Stenzel R. L. , Urrutia J. M.
Published: March 2013

Supersonic vehicles are surrounded by a plasma layer which produces a cutoff layer for electromagnetic waves. Methods to remove the layer by gas releases, dc magnetic fields, and E×B flows have been proposed earlier. The present work suggests a new approach which is based on laboratory observations. Ions are expelled by a time varying magnetic field which creates a Hall electric field. The ion expulsion opens up a window of transparency for wave communications.
Effects of irradiation on the mechanical behavior of twined SiC nanowires
Authors: Jin Enze , Niu Li-Sha , Lin Enqiang , Duan Zheng
Published: March 2013

Irradiation is known to bring new features in one-dimensional nano materials. In this study, we used molecular dynamics simulations to investigate the irradiation effects on twined SiC nanowires. Defects tend to accumulate from outside toward inside of the twined SiC nanowires with increasing irradiation dose, leading to a transition from brittle to ductile failure under tensile load. Atomic chains are formed in the ductile failure process. The first-principles calculations show that most of the atomic chains are metallic.
Fluid elasticity increases the locomotion of flexible swimmers
Authors: Espinosa-Garcia Julian , Lauga Eric , Zenit Roberto
Published: March 2013

We conduct experiments with flexible swimmers to address the impact of fluid viscoelasticity on their locomotion. The swimmers are composed of a magnetic head actuated in rotation by a frequency-controlled magnetic field and a flexible tail whose deformation leads to forward propulsion. We consider both viscous Newtonian and glucose-based Boger fluids with similar viscosities. We find that the elasticity of the fluid systematically enhances the locomotion speed of the swimmer and that this enhancement increases with Deborah number. Using particle image velocimetry to visualize the flow field, we find a significant difference in the amount of shear between the rear and leading parts of the swimmer head. We conjecture that viscoelastic normal stresses lead to a net elastic forces in the swimming direction and thus a faster swimming speed.
Modeling of magnetoelectric effects in flexural nanobilayers: The effects of surface stress
Authors: Hao Feng , Fang Daining
Published: March 2013

A model is developed for the effects of surface stress on low-frequency magnetoelectric (ME) effects in flexural magnetostrictive-piezoelectric bilayers, and we further take cobalt ferrite and lead zirconate titanate (PZT) as a specific case. The results show that flexural deformation can suppress the ME voltage coefficient, especially for moderate PZT volume fraction. Owing to residual surface tension, the ME voltage coefficient should depend on magnetic field, and this tendency is weakened with increasing magnetic field. Interestingly, the size dependence of ME voltage coefficient is found when the thickness of bilayer reduces to nanoscale.
A novel way to improve the quantum efficiency of silicon light-emitting diode in a standard silicon complementary metal–oxide–semiconductor technology
Authors: Xu Kaikai , Li G. P.
Published: March 2013

Silicon diode at avalanche breakdown has visible light emission in the depletion region. It is believed that this optical radiation comes from the kinetic energy loss of carriers generated by impact ionization colliding with immobile charge centers in the avalanche region. A theoretical model is presented to show the correlation of the hot carrier effect with the related photonic emission in high field. Meanwhile, a PMOSFET-like silicon light source device fabricated completely in the standard silicon CMOS process technology is measured to demonstrate that avalanching current is linearly proportional to optical emission power whether this light source acts as a two-terminal device (i.e., diode, the “p+ Source/Drain to n-Substrate junction” with floating the gate) or acts as a three-terminal device (i.e., gate-diode, the “p+ Source/Drain to n-Substrate junction” in the course of varying the gate voltage). Such linearity implies that control of the increasing current is a significant way to enhance the quantum efficiency of this light source device no matter what the physical structure (i.e., two terminals or three terminals) of this device is. For the first time, it has been discovered that, at the same avalanching current, the optical output power in gate-diode structure is higher than the optical output power in diode structure. In other words, for this PMOSFET-like device, the three-terminal operating mode is more efficient than the two-terminal operating mode.
Critical behavior and magnetocaloric effect of LaFe10−xBxSi3 alloy ribbons
Authors: Dang Thanh Tran , Hai Yen Nguyen , Thi Thanh Pham , Huy Dan Nguyen , Zhang Peng. , Phan The-Long , Cho Yu Seong
Published: March 2013

We have studied the magnetic properties and magnetocaloric effect of LaFe10−xBxSi3 (x = 1, 2, and 3) alloy ribbons prepared by a rapidly quenching method. The partial replacement of Fe for B in LaFe10−xBxSi3 leads to a rapid decrease in the Curie temperature (TC) from 425 K for x = 1, through 310 K for x = 2, to 190 K for x = 3. Among LaFe10−xBxSi3 ribbons, only LaFe7B3Si3 (i.e., x = 3) has a dominancy of amorphous phase. The M2 versus H/M plots prove this sample exhibiting a second-order magnetic phase transition. The detailed analyses of M(H) data around TC based on the modified Arrott plot introduced critical values of TC ≈ 192 K, β = 0.354 ± 0.013, γ = 1.355 ± 0.032, and δ = 4.8 ± 0.1. These values are close to those expected for the 3D-Heisenberg model (β = 0.365 and γ = 1.336), indicating an existence of ferromagnetic short-range interactions. Concerning the magnetic entropy change (ΔSm), we have found its maximum ΔSm achieved just around TC, which are 1.04 and 1.42 J/kg K for x = 2 and 3, respectively, under an applied field of 50 kOe. This result proves the ΔSm increase with increasing B content in LaFe10−xBxSi3 alloy ribbons.
The manipulation of magnetic properties by resistive switching effect in CeO2/La0.7(Sr0.1Ca0.9)0.3MnO3 system
Authors: Chen X. G. , Fu J. B. , Yun C. , Yang Y. B. , Liu S. Q. , Wang C. S. , Du H. L. , Han J. Z. , Yang Y. C. , Yang J. B.
Published: March 2013

The bipolar resistance switching behavior was observed in the epitaxially grown CeO2/La0.7(Sr0.1Ca0.9)0.3MnO3 (CeO2/LSCMO) heterojunctions on SrTiO3 substrate using pulsed laser deposition technology. It was found that the magnetization of CeO2/LSCMO heterojunction varies with the resistance state of the device when the external triggered voltage is higher than the set and reset voltages. The magnetization could be reversibly changed by exerting external set and reset voltages on the junction. The electron tunneling accompanied by a trapping/detrapping process at the interface is likely responsible for the modulation of the magnetization in this insulator/manganite device.
Multiferroic and structural properties of BiFeO3 close to the strain induced phase transition on different substrates
Authors: Mix Christian , Jakob Gerhard
Published: March 2013

Single phase BiFeO3 (BFO) thin films have been grown strained on different substrates by pulsed laser deposition. The crystal structure and symmetry were investigated by detailed X-ray diffraction and reciprocal space maps as a function of the layer thicknesses of BFO and La0.7Sr0.3MnO3 (LSMO) buffer layers. Corresponding changes in surface morphology and ferroelectric domain structure were observed. The influence of the BFO layer thickness and the use of a LSMO buffer layer proved to be crucial for good ferroelectric and structural properties of BFO. Limits for the stability of bulk-like or strain dominated and ferroelectric domain structures are found for growth under different levels of compressive strain.
Heterojunction of multiferroic HoMnO3 on Nb-doped SrTiO3
Authors: Han T. C. , Chen C. T. , Pan S. S. , Lin J. G.
Published: March 2013

Orthorhombic HoMnO3 thin films with a-axis orientation are epitaxial grown on Nb-doped SrTiO3(110) substrate using pulsed laser deposition technique to fabricate all-oxide p-n heterojunctions. The structural, magnetic, and electrical properties of heterostructures are measured. The temperature-dependent current-voltage data from 320 to 60 K display diode-like rectifying characteristics in the as-prepared p-n junction. Furthermore, an anomalous increase in the reverse-bias current with decreasing temperature below 240 K is observed. Further analysis suggests that this anomalous electrical transport behavior could be ascribed to the Fowler-Nordheim tunneling through the junctions.
The formation of Ti–O tetrahedra and band gap reduction in SiO2 via pulsed ion implantation
Authors: Green R. J. , Zatsepin D. A. , Hunt A. , Kurmaev E. Z. , Gavrilov N. V. , Moewes A.
Published: March 2013

Titanium ions are implanted into amorphous SiO2 at two different fluences using pulsed ion implantation, and the resulting samples are annealed. Bulk sensitive soft X-ray absorption spectroscopy of the Ti L2,3 edge reveal strikingly different spectra for the two fluences. Spectral simulations using multiplet crystal field theory show clearly that for low fluence the Ti ions have a local octahedral coordination, while at higher fluence the formation of Ti4+–O tetrahedra dominates. Using O K-edge X-ray absorption and emission, the effect of the Ti states on the valence and conduction bands of the host SiO2 is revealed. With the introduction of Ti tetrahedra, the band gap reduces from about 8 eV to just over 4 eV, due entirely to the Ti 3d conduction band states. These results demonstrate the possibility to obtain Ti–O tetrahedra in silica by Ti ion implantation and a suitable thermal treatment, clarify the mechanism of band gap reduction with Ti doping in SiO2, and demonstrate the sensitivity of L-edge X-ray absorption with a multiplet crystal field theory analysis to the Ti coordination of novel materials.
Propagation of magnetically controllable lasers and magneto-optic dual switching using nitrogen-vacancy centers in diamond
Authors: Li J.-H. , Yu R. , Wu Y.
Published: March 2013

We study coherent laser-induced optical behaviors in weak twin-light propagation through strained diamond nitrogen-vacancy (NV) centers via switching on and off an external magnetic field. By numerically solving the coupled Bloch-Maxwell equations for NV center and field simultaneously in space and time, we address dynamic control of pulse propagation and magneto-optic dual switching in such a laser-driven NV center system. The proposed scheme may have applications in the design of magneto-optic switching and magneto-optic storage devices.
Coupling and noise induced spiking-bursting transition in a parabolic bursting model
Authors: Ji Lin , Zhang Jia , Lang Xiufeng , Zhang Xiuhui
Published: March 2013

The transition from tonic spiking to bursting is an important dynamic process that carry physiologically relevant information. In this work, coupling and noise induced spiking-bursting transition is investigated in a parabolic bursting model with specific discussion on their cooperation effects. Fast/slow analysis shows that weak coupling may help to induce the bursting by changing the geometric property of the fast subsystem so that the original unstable periodical solution are stabilized. It turned out that noise can play the similar stabilization role and induce bursting at appropriate moderate intensity. However, their cooperation may either strengthen or weaken the overall effect depending on the choice of noise level.
Self healing of defected graphene
Authors: Chen Jianhui , Shi Tuwan , Cai Tuocheng , Xu Tao , Sun Litao , Wu Xiaosong , Yu Dapeng
Published: March 2013

For electronics applications, defects in graphene are usually undesirable because of their ability to scatter charge carriers, thereby reduce the carrier mobility. It would be extremely useful if the damage can be repaired. In this work, we employ Raman spectroscopy, X-ray photoemission spectroscopy, transmission electron microscopy, and electrical measurements to study defects in graphene introduced by argon plasma bombardment. We have found that majority of these defects can be cured by a simple thermal annealing process. The self-healing is attributed to recombination of mobile carbon adatoms with vacancies. With increasing level of plasma induced damage, the self-healing becomes less effective.
Nonlinear magnetoelectric response of a Metglas/piezofiber laminate to a high-frequency bipolar AC magnetic field
Authors: Wang Yaojin , Shen Ying , Gao Junqi , Li Menghui , Li Jiefang , Viehland D.
Published: March 2013

A nonlinear magnetoelectric (ME) response has been investigated in a Metglas/piezofiber laminate by applying a bipolar AC magnetic field (Hac) without a DC magnetic bias. The ME voltage (VME) was measured for various amplitudes of Hac of up to 9 Oe over the frequency (f) range 0.1 < f < 40 kHz. Compared to the linear ME behavior, an anomalous response to f and Hac was observed, which is believed to be associated with the Eddy-current loss in the Metglas layers. A frequency multiplication effect was also observed for VME, which was understood by Fourier analysis of the nonlinearity in the magnetostriction.
Monitoring the formation of oxide apertures in micropillar cavities
Authors: Bakker Morten P. , Suntrup Donald J. , Snijders Henk , Truong Tuan-Ahn , Petroff Pierre M. , van Exter Martin P. , Bouwmeester Dirk
Published: March 2013

An imaging technique is presented that enables monitoring of the wet thermal oxidation of a thin AlAs layer embedded between two distributed Bragg reflector mirrors in a micropillar. After oxidation we confirm by white light reflection spectroscopy that high quality optical modes confined to a small volume have been formed. The combination of these two optical techniques provides a reliable and efficient way of producing oxide apertured micropillar cavities for which the wet thermal oxidation is a critical fabrication step.
Note: Alignment/focus dependent core-line sensitivity for quantitative chemical analysis in hard x-ray photoelectron spectroscopy using a hemispherical electron analyzer
Authors: Weiland Conan , Browning Raymond , Karlin Barry A. , Fischer Daniel A. , Woicik Joseph C.
Published: March 2013

X-ray photoelectron spectroscopy is an established technique for quantitative chemical analysis requiring accurate peak intensity analysis. We present evidence of focus/alignment dependence of relative peak intensities for peaks over a broad kinetic energy range with a hemispherical electron analyzer operated in a position imaging mode. A decrease of over 50% in the Ag 2p3/2 to Ag 3d ratio is observed in a Ag specimen. No focus/alignment dependence is observed when using an angular imaging mode, necessitating the use of angular mode for quantitative chemical analysis.
Evolution of structural and dynamic heterogeneities and activation energy distribution of deformation units in metallic glass
Authors: Jiao W. , Wen P. , Peng H. L. , Bai H. Y. , Sun B. A. , Wang W. H.
Published: March 2013

We present experimental results on the distribution and evolution of energy barriers of deformation units in metallic glass (MG) via an activation-relaxation method. Our results show that the dynamical heterogeneity of metallic glass arises from its structural inhomogeneity, and there exist the close correlations between the deformation units, dynamical and structural heterogeneities, and relaxation behaviors in metallic glasses. The results might provide insights on the heterogeneities, plastic deformation, and relaxations behaviors of metallic glass.
A demographic framework for the adaptive management of the endangered arid-zone tree species Acacia peuce
Authors: Raghu S. , Nano Catherine E. M. , Pavey Chris R.
Published: March 2013

Slow-growing desert tree species pose unique conservation challenges; their demography is driven by rare stochastic climatic events, remoteness of populations makes monitoring difficult and, consequently, their management is often information-limited. In particular, the paucity of information on vital rates at a relevant temporal scale makes analyses of demography and population viability difficult. Our objective was to undertake a demographic analysis of the threatened arid-zone tree species (Acacia peuce F.Muell.) that is a model system in terms of being (1) a slow-growing desert tree species whose recruitment is limited to stochastic and rare extreme rainfall events, and (2) a species of conservation significance growing in a remote location where remoteness imposes limitations on conservation monitoring. Complementary analyses using pattern- and process-derived matrix population models, based on a dataset derived from a 30-year monitoring effort, verified that the smallest of the A. peuce populations would continue to grow under current environmental conditions. Population growth in this species is most influenced by the survival or adult and sapling stages. Stochastic demographic simulations revealed that climate change is likely to significantly elevate the risk of population decline, particularly in fragment stands. The long-term viability of A. peuce hinges on sustaining the survival rates of adult and sapling stages by managing stresses to individuals in these stages, and through minimising anthropogenic disturbance to populations during rare, stochastic and extreme rainfall events that trigger recruitment. Extending the current non-binding agreement enabling the use of fences to exclude cattle, and improved interpretative signage to raise awareness of anthropogenic impacts on this species will significantly aid conservation of this species. The integration of modelling, monitoring, and management within a demographic framework can facilitate efficient and effective conservation of slow-growing arid-zone tree species, despite the challenges imposed by remoteness.
The Scale Analysis of Number Mapping onto Space: Manual Estimation Study
Authors: Karolis Vyacheslav
Published: March 2013

Previous studies have shown an interference of task-irrelevant numerical information with the spatial parameters of visuomotor behaviour. These findings lend support to the notion that number and space share a common metric with respect to action. Here I argue that the demonstration of the structural similarity between scales for number and space would be a more stringent test for the shared metrics than a mere fact of interference. The present study investigated the scale of number mapping onto space in a manual estimation task. The physical size of target stimuli and the magnitudes of task-irrelevant numbers were parametrically manipulated in the context of the Titchener illusion. The results revealed different scaling schemas for number and space. Whereas estimates in response to changes in stimulus physical size showed a gradual increase, the effect of number was categorical with the largest number (9) showing greater manual estimate than the other numbers (1, 3, and 7). Possible interpretations that are not necessarily incompatible with the hypothesis of shared metrics with respect to action are proposed. However, the present findings suggest that a meticulous scale analysis is required in order to determine the nature of number–space interaction.
Formation of the compact jets in the black hole GX 339−4
Authors: Corbel S. , Aussel H. , Broderick J. W. , Chanial P. , Coriat M. , Maury A. J. , Buxton M. M. , Tomsick J. A. , Tzioumis A. K. , Markoff S. , Rodriguez J. , Bailyn C. D. , Brocksopp C. , Fender R. P. , Petrucci P. O. , Cadolle-Bel M. , Calvelo D. , Harvey-Smith L.
Published: March 2013

Galactic black hole binaries produce powerful outflows which emit over almost the entire electromagnetic spectrum. Here, we report the first detection with the Herschel observatory of a variable far-infrared source associated with the compact jets of the black hole transient GX 339−4 during the decay of its recent 2010–2011 outburst, after the transition to the hard state. We also outline the results of very sensitive radio observations conducted with the Australia Telescope Compact Array, along with a series of near-infrared, optical (OIR) and X-ray observations, allowing for the first time the re-ignition of the compact jets to be observed over a wide range of wavelengths. The compact jets first turn on at radio frequencies with an optically thin spectrum that later evolves to an optically thick synchrotron emission. An OIR reflare is observed about 10 d after the onset of radio and hard X-ray emission, likely reflecting the necessary time to build up enough density, as well as to have acceleration (e.g. through shocks) along an extended region in the jets. The Herschel measurements are consistent with an extrapolation of the radio inverted power-law spectrum, but they highlight a more complex radio to OIR spectral energy distribution for the jets.
The Internet as Infrastructure
Authors: Sandvig Christian
Published: March 2013

This chapter discusses how useful it can be to view the Internet as an infrastructure, demonstrating how technical changes of the infrastructure can have unanticipated and unintended societal consequences. The Libyan decision induced substantial dismay in the Internet industry. The case of Violet Blue entails technical decisions about the design of interactive software, usability, culture, religion, history, politics, and economics. Moreover, the infrastructure studies of the Internet are outlined as the relationists and the new materialists. The Internet turns out as an infrastructural primitive or template for its parents: a model privately organized system of distributed computation – theur-infrastructure. Communication in its original meaning was transportation, a box of goods was said to be ‘communicated’ when it was delivered. It is observed that the Internet demands attention as a foundation for modern life.
The Study of Online Relationships and Dating
Authors: Gunter Barrie
Published: March 2013

This chapter, which investigates a range of evidence about online dating behaviour, and a synthesis of approaches to research in this area, also evaluates the nature of the market and the experiences of those who have engaged in online dating. Further issues linked with patterns of online self-disclosure and self-presentation, and concerns about deception in online dating, are then assessed. Corporate data have indicated that the online dating business is mostly on an upward trajectory. Data show greater age difference tolerance of online daters and a willingness to adopt a broader selection of partners compared with offline-only daters. Many online dating site users increasingly fail to be fully engaged by sites that offer search opportunities for partner matches using check-box profiling. The issues of deception and trust in relation to personal profiles have been regarded as problematic factors that could cause tension among online daters.
Trust in Commercial and Personal Transactions in the Digital Age
Authors: Connolly Regina
Published: March 2013

This chapter concentrates on how trust has been conceptualized and studied, providing a refined understanding of many trust-related issues that affect commerce but arguably also other online transactions in the digital age, such as in the public services. A discussion of the role of experience, gender, and culture in relation to the generation of online trust beliefs is presented. It is noted that trust development is dependent on time. Trust is ‘necessary for the success of economic transactions’ and is viewed as the relationship facilitator between trading partners. The focus of online trust issues has developed, and the role of recommendation agents and avatars in trust building is described in the same way that the antecedents of trust received attention a number of years ago. It is hoped that this chapter has clarified some of the key issues that require consideration when researching trust in an online transaction context.
Digital Transformations of Scholarship and Knowledge
Authors: Meyer Eric T. , Schroeder Ralph
Published: March 2013

This chapter examines how the Internet is transforming academic research in the sciences, social sciences, and humanities. The question of changes in knowledge is one that science and technology should be well equipped to answer. The chapter also offers examples that show the range of e-Research. E-Research needs novel tools, and organisational structures as well as researchers should change their everyday practices. VOSON can be seen as part of a burgeoning engagement in e-Social Science. The e-Research component has the advantage of enhanced visibility. The sociology of science and technology does not have the conceptual tools to simultaneously deal with how research communities are oriented to shared objects, how this impacts various styles of science and knowledge, and how scholarly practices are therefore being transformed.
Theoretical Perspectives in the Study of Communication and the Internet
Authors: Rice Ronald E. , Fuller Ryan
Published: March 2013

This chapter exposes the prominence of different theoretical perspectives on the Internet. A broad scope of primary and secondary theories has been increasingly used to understand the social and communicative aspects of the Internet and the increasingly specialized areas being developed by Internet researchers, such as around social media. The chapters published in the first half of the period (2000–04) are compared to those in the second period of the sample (2005–09). It is observed that the media attributes, the public sphere, and community have been the most popular theory themes. There are also opportunities for further theoretical development in the areas of credibility/trust, participatory media/users, relational management, and cultural differences.