We sought to assess whether the magnitude of the intrinsic optical imaging signal in rat visual cortex is related to the underlying response properties of visual cortical receptive fields and to perceptual function. &...
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Accurate determination of carrier densities in ferromagnetic semiconductors by Hall measurements is hindered by the anomalous Hall effect , and thus alternative methods are being sought. Here, we propose that cyclotro...
Accurate determination of carrier densities in ferromagnetic semiconductors by Hall measurements is hindered by the anomalous Hall effect , and thus alternative methods are being sought. Here, we propose that cyclotron resonance (CR) is an excellent method for carrier density determination for InMnAs-based magnetic structures. We develop a theory for electronic and magneto-optical properties in narrow gap InMnAs films and superlattices in ultrahigh magnetic fields oriented along [001]. In n-type InMnAs films and superlattices, we find that the e-active CR peak field is pinned at low electron densities and then begins to shift rapidly to higher fields above a critical electron concentration allowing the electron density to be accurately calibrated. In p-type InMnAs, we observe two h-active CR peaks due to heavy and light holes. The line shapes depend on temperature and line broadening. The light hole CR requires higher hole densities and fields. Analyzing CR line shapes in p-films and superlattices can help determine hole densities.
In this paper, the working principle of an acoustic chromatography device is investigated by the analytical and finite element modeling (FEM) approach. Analytical and simulation results, compared to the inteferometric...
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In this paper, the working principle of an acoustic chromatography device is investigated by the analytical and finite element modeling (FEM) approach. Analytical and simulation results, compared to the inteferometric scan and the experimental results, confirm that the inertial field due to the flexural waves on the capillary has the major role for manipulation of particles. Disagreement between phase velocity from the simple beam bending solution and experiments at high frequencies are also discussed.
This paper designs space-time codes for standard PSK and QAM signal constellations that have flexible rate, diversity and require no constellation expansion. Central to this construction are binary partitions of the P...
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This paper designs space-time codes for standard PSK and QAM signal constellations that have flexible rate, diversity and require no constellation expansion. Central to this construction are binary partitions of the PSK and QAM constellations that appear in codes designed for the Gaussian channel. The space-time codes presented here are designed by separately specifying the different levels of the binary partition in the space-time array. The individual levels are addressed by either the binary symmetric matrices associated with codewords in a Kerdock code or other families of binary matrices. Binary properties of these sets are sufficient to verify the diversity property of the codewords in the complex domain. Larger sets of binary symmetric matrices (such as the set used in Delsarte-Goethals codes) are used to trade diversity protection for increased rate.
Service functions are major component of every industry. The evolution of service functions have seen manually intensive tasks being replaced by a combination of mental and interactive tasks. As a part of this transfo...
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Service functions are major component of every industry. The evolution of service functions have seen manually intensive tasks being replaced by a combination of mental and interactive tasks. As a part of this transformation, we have seen an increasing dependency on the high technology, actually information technology, mostly with computer-communications and the web. This high technology will finally replace the service functions by a combination of knowledge intensive, interactive and customer's individual tasks in the future. However, these knowledge intensive, interactive and customer's individual service functions could be enjoyable for the restricted person, due to the difficulties of the man (customers)-machine (PCs, web-server machines) interface and also the service providers are not able to obtain much more customer's individual and abstruse information for providing the customer's individual services, due to the customers' privacy problem. In this paper we focus on of knowledge intensive, interactive and customer's individual services in the future. We emphasize the importance of developing the mechanism of humanization for making these services enjoyable for anyone and the personalization for enjoyable the more individual services, and show some examples for these mechanisms in which humanization is realized by humanoid robots and personalization is realized by customers' privacy preserving scheme. We present a feedback system including the mechanism for humanization and personalization. By performing this feedback system, anyone who is not familiar to machines, can interact with machines like human-beings and can poll or report even though privacy related information anonymously to service providers. By periodically performing this feedback system, the customers' knowledge, information, suggestions and ideas can could be accumulated and the service providers could provide more individual services to customers, Once humanization and personalization mechan
Time-resolved near-field microscopy allows the propagation of ultrafast pulses to be visualized en route while they travel through complex photonic structures. These measurements enable the unambiguous determination o...
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ISBN:
(纸本)0780383435
Time-resolved near-field microscopy allows the propagation of ultrafast pulses to be visualized en route while they travel through complex photonic structures. These measurements enable the unambiguous determination of both local phase and group velocities. We illustrate this powerful technique by tracking an ultrashort wavepacket as it completes several round trips in a ring resonator.
Triple-layer omni-directional reflectors (ODRs) consisting of a semiconductor, a transparent quarter-wavelength dielectric layer and metal layer have high reflectivities at all angles of incidence. In this paper, trip...
Triple-layer omni-directional reflectors (ODRs) consisting of a semiconductor, a transparent quarter-wavelength dielectric layer and metal layer have high reflectivities at all angles of incidence. In this paper, triple-layer ODRs are demonstrated that incorporate nanoporous SiO 2 , a novel low-refractive-index (low-n) material with refractive indices n ≪ 1.46 as well as dense SiO 2 (n = 1.46). GaP and Ag serve as the semiconductor and metal layer materials, respectively. An angle-integrated transverse electric (TE) mode reflectivity of R avg | TE = 99.9 % and transverse magnetic (TM) mode reflectivity R avg | TM = 98.9 % are calculated for the triple-layer ODRs employing nanoporous SiO 2 . Reflectivity measurements, including the angular dependence of R, are presented. Novel hybrid ODRs consisting of semiconductor, a several micron thick low-n dielectric material layer, a distributed Bragg reflector (DBR) and metal layer have outstanding reflectivities for all incident angles. GaP and Ag serve as the semiconductor and metal layer, respectively. Nanoporous SiO 2 is used as the low-n material. TiO 2 and dense SiO 2 serve as the DBR materials. The angle-intergrated reflectivities of the TE and TM modes are calculated to be larger than 99.9 % for the hybrid ODRs. The results indicate the great potential of the ODRs for light-emitting diodes with high light extraction efficiency.
We report on photoexcitation of coherent longitudinal acoustic phonons in single-crystal cuprate thin films on epitaxialy matched substrates. The photoinduced reflectance oscillations are unusually long lived; in some...
We report on photoexcitation of coherent longitudinal acoustic phonons in single-crystal cuprate thin films on epitaxialy matched substrates. The photoinduced reflectance oscillations are unusually long lived; in some samples we could easily resolve them for hundreds of periods. We studied the effect of varying a number of parameters, including the film doping level, thickness, and temperature, as well as the pump and probe beam wavelength, power, polarization, and incidence angle. We account quantitatively for the oscillation period, dispersion, phase, and decay of amplitude with time.
The magnetization reversal mechanism in an array of submicron elliptical Permalloy elements with an aspect ratio 1.4:1 is investigated using the diffracted magneto-optic Kerr effect technique, Lorentz scanning transmi...
The magnetization reversal mechanism in an array of submicron elliptical Permalloy elements with an aspect ratio 1.4:1 is investigated using the diffracted magneto-optic Kerr effect technique, Lorentz scanning transmission electron microscopy, and Lorentz transmission electron microscopy. The experimental results are interpreted from a comparison with micromagnetic simulations. The reversal mechanism is found to be dependent on the direction of the magnetic field and to occur via the formation of one or two vortices; the one vortex state is nucleated when the field is applied along the short axis. For the field applied along the long axis a mixture of one- and two-vortex states is observed at remanence.
We have studied the hydrostatic pressure dependence of Ge nanocrystals embedded in a SiO2 matrix on a Si substrate by Raman scattering at room temperature. During the first cycle of increasing pressure, we observed a ...
We have studied the hydrostatic pressure dependence of Ge nanocrystals embedded in a SiO2 matrix on a Si substrate by Raman scattering at room temperature. During the first cycle of increasing pressure, we observed a step change in the Ge Raman mode from 310.4 to 313.8cm−1 at ∼23kbar. The linear pressure coefficients α obtained before and after the step change at ∼23kbar are 0.42 and 0.64cm−1kbar−1, respectively. Upon decreasing pressure, the Ge mode follows a single slope of pressure coefficient α=0.64cm−1kbar−1. A finite-element analysis was carried out to investigate the elastic-field distribution in the Ge/SiO2/Si nanocrystal system, where the discontinuity of the specific geometric configuration with different elastic constants causes local areas of stress concentration around the interface. The step change of the Raman shifts with pressure at ∼23kbar was attributed to complete delamination between the SiO2 film and the Si substrate.
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