Intrinsic optical signal (IOS) imaging is a widely accepted technique for imaging brain activity. We propose an integrated device consisting of interleaved arrays of gallium arsenide (GaAs) based semiconductor light s...
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Intrinsic optical signal (IOS) imaging is a widely accepted technique for imaging brain activity. We propose an integrated device consisting of interleaved arrays of gallium arsenide (GaAs) based semiconductor light sources and detectors operating at telecommunications wavelengths in the near-infrared. Such a device will allow for long-term, minimally invasive monitoring of neural activity in freely behaving subjects, and will enable the use of structured illumination patterns to improve system performance. In this work we describe the proposed system and show that near-infrared IOS imaging at wavelengths compatible with semiconductor devices can produce physiologically significant images in mice, even through skull
Real collective density variables C(k) [cf. Eq. (1.3)] in many-particle systems arise from nonlinear transformations of particle positions, and determine the structure factor S(k), where k denotes the wave vector. Our...
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Real collective density variables C(k) [cf. Eq. (1.3)] in many-particle systems arise from nonlinear transformations of particle positions, and determine the structure factor S(k), where k denotes the wave vector. Our objective is to prescribe C(k) and then to find many-particle configurations that correspond to such a target C(k) using a numerical optimization technique. Numerical results reported here extend earlier one- and two-dimensional studies to include three dimensions. In addition, they demonstrate the capacity to control S(k) in the neighborhood of ∣k∣=0. The optimization method employed generates multiparticle configurations for which S(k)∝∣k∣α, ∣k∣⩽K, and α=1, 2, 4, 6, 8, and 10. The case α=1 is relevant for the Harrison-Zeldovich model of the early universe, for superfluid He4, and for jammed amorphous sphere packings. The analysis also provides specific examples of interaction potentials whose classical ground states are configurationally degenerate and disordered.
Molecular-dynamics simulations of the crystalline silicon-silicon nitride interfaces are performed to investigate the mechanical failure mechanisms at the interfaces under external strain. At 8% applied tensile strain...
Molecular-dynamics simulations of the crystalline silicon-silicon nitride interfaces are performed to investigate the mechanical failure mechanisms at the interfaces under external strain. At 8% applied tensile strain, parallel to the interface, regular crack initiation and propagation in silicon nitride and dislocation emission and propagation in silicon are observed. At larger 16% strain, however, the formation of a pit similar to that in experiments with lattice-mismatched systems is observed. The simulation results suggest the primary mechanism of pit formation is interaction of a local compressional pinch of the film at the interface with the close proximity to the arrival of a dislocation at the interface in the highly strained silicon.
The controlled self-assembly of thiol stabilized gold nanocrystals in a mediating solvent and confined within mesoporous alumina was probed in situ with small angle x-ray scattering. The evolution of the self-assembly...
The controlled self-assembly of thiol stabilized gold nanocrystals in a mediating solvent and confined within mesoporous alumina was probed in situ with small angle x-ray scattering. The evolution of the self-assembly process was controlled reversibly via regulated changes in the amount of solvent condensed from an undersaturated vapor. Analysis indicated that the nanoparticles self-assembled into cylindrical monolayers within the porous template. Nanoparticle nearest-neighbor separation within the monolayer increased and the ordering decreased with the controlled addition of solvent. The process was reversible with the removal of solvent. Isotropic clusters of nanoparticles were also observed to form temporarily during desorption of the liquid solvent and disappeared upon complete removal of liquid. Measurements of the absorption and desorption of the solvent showed strong hysteresis upon thermal cycling. In addition, the capillary filling transition for the solvent in the nanoparticle-doped pores was shifted to larger chemical potential, relative to the liquid/vapor coexistence, by a factor of 4 as compared to the expected value for the same system without nanoparticles.
We investigate high amplitude coherent optical phonon dynamics in bismuth through femtosecond x-ray and optical scattering. From these experiments, we present the first detailed measurements of changes in the interato...
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We present the first detailed measurements of the interatomic potential of photoexcited bismuth using ultrafast optical and x-ray scattering. Our results show that electronic softening is responsible for the strong ch...
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The advantage of magnetic resonance imaging (MRI)-guided surgery, in which MR images taken during surgery are used to guide the surgery, has been recognized recently. However, there is a problem, due to long imaging t...
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We investigate high amplitude coherent optical phonon dynamics in bismuth through femtosecond X-ray and optical scattering. From these experiments, we present the first detailed measurements of changes in the interato...
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ISBN:
(纸本)1557528136
We investigate high amplitude coherent optical phonon dynamics in bismuth through femtosecond X-ray and optical scattering. From these experiments, we present the first detailed measurements of changes in the interatomic potential following high-density photoexcitation.
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