Description: We consider the initial value problem for systems of nonlinear Klein–Gordon equations with quadratic nonlinearities. We prove the existence of scattering states, namely, the asymptotic stability of small solutions in the neighborhood of the free solutions for small initial data in the weighted Sobolev space H4,3(R3)×H3,3(R3). If nonlinearities satisfy the strong null condition, then the same result is true in two space dimensions for small initial data in H5...
Description: Spectra of the cluster surface equilibrium fluctuations are treated by decomposition into the bulk and net capillary ones. The bulk fluctuations without capillary ones are simulated by the surface of a cluster truncated by a sphere. The bulk fluctuation spectrum is shown to be generated primarily by the discontinuity in the spatial distribution of cluster internal particles. The net capillary fluctuation slice spectrum is obtained in molecular dynamics simul...
Description: A light source on the surface of a slab of 2+1-dimensional photonic crystal has been prepared by the Langmuir–Blodgett deposition of a colloidal crystal on top of a thin film containing CdTe nanocrystals. The directional enhancement of the light emission intensity in the spectral range of the photonic bandgap has been revealed through the comparative examination of the angle-resolved transmission, diffraction, and photoluminescence spectra of the prepared st...
Description: A plasma-based resonant backward Raman amplifier/compressor for high power amplification of short laser pulses might, under ideal conditions, convert as much as 90% of the pump energy to the seed pulse. While the theoretical highest possible efficiency of this scheme has not yet been achieved, larger efficiencies than ever before obtained experimentally (6.4%) are now being reported, and these efficiencies are accompanied by strong pulse compression. Based o...
Description: This paper presents the acceleration sensitivity and the resulting vibration-induced phase noise of an electrostatically coupled encapsulated silicon microresonator. External vibrations can produce phase noise in microresonators by generating time-varying stress in the resonant beams. A spring mounted resonator design that reduces the induced axial stress is presented here. Measurements and simulations show that the acceleration sensitivity and the vibration...
Description: In this paper we show that magnetostatic models of permanent magnets, based on distributions of magnetic charge and shaped by a helicoidal geometry of cylindrical type, have the volume charge density ρM equal to zero. This result is valid when (i) the modulus of the vector physical magnetization density M has a constant value in all the points of the helicoidal magnet and (ii) M has the same direction of an oriented straight line having a constant angle with...
Description: Evolutionism
Description: High intensity electron emission cathodes based on a well-aligned ZnO nanorod array were fabricated. An investigation of the properties of the plasma and the electron beams produced by ZnO nanorod array cathodes was presented. Intense current electron beams were obtained from the cathodes. At an electric field of 7–8 V/μm and pulse duration of ∼ 100 ns, the highest emission current density reached 76–91 A/cm2. The production mechanism of the electron beams w...
Description: The effects of stressed thin films on substrates that possess anisotropic elasticity have been measured and modeled. Substrate curvature induced by a uniform, stressed film will be axisymmetric for substrates possessing greater than twofold in-plane symmetry, and anisotropic for twofold symmetric substrates. For a (011) Si substrate, the difference between the curvature along the 〈110〉 and 〈100〉 principal axes varies by approximately 47%. A simple, analytica...
Description: The evaluation of different surface coatings used in alkali metal atomic magnetometers is necessary for the improvement of sensitivity of these devices. A method to measure the polarization lifetime of alkali atoms in the region between substrates with different coatings was developed to determine the effectiveness of the coating at preserving alkali spin polarization as well as chemical compatibility and high-temperature stability. Multiple coatings can be ...
Description: Results of ∼ 200 kbar pressure generation at 50 μm distance from the implosion axis of the converging shock wave produced by an underwater electrical explosion of a cylindrical wire array are reported. The array was exploded using a submicrosecond high-current generator (stored energy of ∼ 4.2 kJ, current amplitude of ∼ 325 kA, rise time of ∼ 1 μs). Multiframe shadow imaging of the shock wave was used to determine its time of flight. These data were applied ...
Description: The multiferroic 0.7 BiFeO3–0.3 PbTiO3 has been fabricated in both sintered ceramic and powder form using conventional mixed oxide synthesis. Rietveld’s analysis of neutron powder diffraction data has shown that the sintered ceramic and powder are predominantly R3c and P4mm phases, respectively. It is shown explicitly that magnetic ordering does not occur for the P4mm phase at room temperature.
Description: A new numerical exploration suggests that the motion of two vortex pairs, with constituent vortices all of the same absolute circulation, displays chaotic scattering regimes. The mechanisms leading to chaotic scattering are different from the “slingshot effect” identified by Price [Phys. Fluids A 5, 2479 (1993) ] and occur in a different region of the four-vortex phase space. They may, in many cases, be understood by appealing to the solutions of the three-v...
Description: High-resolution detection of specific molecules in cells is a major challenge in biology. We show that infrared scanning near-field microscopy can detect the spatial distribution of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid–type glutamate receptor clusters on hippocampal neurons. The GluR2 subunits were labeled with the die Alexa 488 and high-resolution infrared micrographs were taken at 6.25 μm. The absence of photobleaching makes this approach ...
Description: A theoretical model has been developed for predicting the reflectivity of thin planar surfaces imbedded with long conductive fibers. Intersecting fibers in the plane form larger conducting clusters. The model includes this effect, which serves to increase the reflectivity. Magnetic coupling between the fibers is also included. This coupling is found to be particularly important at higher frequencies. Test panels were made using a direct write process to imbe...
Description: Amorphization has been achieved in blended elemental Fe-based multicomponent alloy powders by mechanical alloying. The effect of Nb addition to the Fe42Ni28Zr10−xNbxB20 alloy in the composition range of 1–6 at. % Nb has been investigated and it was shown that the glass-forming ability (GFA) of the alloys, defined as the milling time required to produce an amorphous phase, improved with Nb addition. The improvement was not regular; the highest GFA was achieve...
Description: Electroluminescence from single nitride-based quantum dots is reported. Clear single quantum dot emission is observed, which persists up to ~85 K. This is achieved through the study of a quantum dot layer in the intrinsic region of a forward-biased vertical p-i-n diode. The current-voltage characteristic of the devices is examined at 4.3 K and observed to exhibit electrical bistability phenomena, which is explained in terms of charge accumulation in the InGa...