47,218 research outputs found
Vibrations of weakly-coupled nanoparticles
The vibrations of a coupled pair of isotropic silver spheres are investigated
and compared with the vibrations of the single isolated spheres. Situations of
both strong coupling and also weak coupling are investigated using continuum
elasticity and perturbation theory. The numerical calculation of the eigenmodes
of such dimers is augmented with a symmetry analysis. This checks the
convergence and applicability of the numerical method and shows how the
eigenmodes of the dimer are constructed from those of the isolated spheres. The
frequencies of the lowest frequency vibrations of such dimers are shown to be
very sensitive to the strength of the coupling between the spheres. Some of
these modes can be detected by inelastic light scattering and time-resolved
optical measurements which provides a convenient way to study the nature of the
mechanical coupling in dimers of micro and nanoparticles.Comment: expanded version, 8 pages, 5 figures, 2 table
Dynamical Self-assembly during Colloidal Droplet Evaporation Studied by in situ Small Angle X-ray Scattering
The nucleation and growth kinetics of highly ordered nanocrystal
superlattices during the evaporation of nanocrystal colloidal droplets was
elucidated by in situ time resolved small-angle x-ray scattering. We
demonstrated for the first time that evaporation kinetics can affect the
dimensionality of the superlattices. The formation of two-dimensional
nanocrystal superlattices at the liquid-air interface of the droplet has an
exponential growth kinetics that originates from interface "crushing".Comment: 4 pages, 4 figure
Eccentric discs in binaries with intermediate mass ratios: Superhumps in the VY Sculptoris stars
We investigate the role of the eccentric disc resonance in systems with mass
ratios q greater than 1/4, and demonstrate the effects that changes in the mass
flux from the secondary star have upon the disc radius and structure. The
addition of material with low specific angular momentum to its outer edge
restricts a disc radially. Should the mass flux from the secondary be reduced,
it is possible for the disc in a system with mass ratio as large as 1/3 to
expand to the 3:1 eccentric inner Lindblad resonance and for superhumps to be
excited.Comment: 6 pages with 7 figures, accepted by MNRA
Irrigation system performance assessment and diagnosis
Performance evaluation / Irrigation programs / Irrigation management / Irrigation systems / Case studies / Hydraulics / Management / Environmental effects / Asia / Africa / South America
Normal Heat Conduction in a Chain with Weak Interparticle Anharmonic Potential
We analytically study heat conduction in a chain with interparticle
interaction V(x)=lambda[1-cos(x)] and harmonic on-site potential. We start with
each site of the system connected to a Langevin heat bath, and investigate the
case of small coupling for the interior sites in order to understand the
behavior of the system with thermal reservoirs at the boundaries only. We
study, in a perturbative analysis, the heat current in the steady state of the
one-dimensional system with weak interparticle potential. We obtain an
expression for the thermal conductivity, compare the low and high temperature
regimes, and show that, as we turn off the couplings with the interior heat
baths, there is a "phase transition:'' the Fourier's law holds only at high
temperatures
Using World-Wide-Web technology for pathology education
In this article, we describe the development of computer-based learning programs for pathology students at Jefferson Medical College. These programs are authored using HTML (HyperText Markup Language), and are available to students on campus and via the internet. Our computer-based learning resources include scheduling information, course goals and objectives, glossary of key words, self-assessment programs and image-based case studies. These educational programs are popular with the students. We recommend the use of World Wide Web technology to improve teaching and learning in pathology education
Probabilistic computing with future deep sub-micrometer devices: a modelling approach
An approach is described that investigates the potential of probabilistic "neural" architectures for computation with deep sub-micrometer (DSM) MOSFETs. Initially, noisy MOSFET models are based upon those for a 0.35 /spl mu/m MOS technology with an exaggerated 1/f characteristic. We explore the manifestation of the 1/f characteristic at the output of a 2-quadrant multiplier when the key n-channel MOSFETs are replaced by "noisy" MOSFETs. The stochastic behavior of this noisy multiplier has been mapped on to a software (Matlab) model of a continuous restricted Boltzmann machine (CRBM) - an analogue-input stochastic computing structure. Simulation of this DSM CRBM implementation shows little degradation from that of a "perfect" CRBM. This paper thus introduces a methodology for a form of "technology-downstreaming" and highlights the potential of probabilistic architectures for DSM computation
Pure multiplicative stochastic resonance of anti-tumor model with seasonal modulability
The effects of pure multiplicative noise on stochastic resonance in an
anti-tumor system modulated by a seasonal external field are investigated by
using theoretical analyses of the generalized potential and numerical
simulations. For optimally selected values of the multiplicative noise
intensity quasi-symmetry of two potential minima and stochastic resonance are
observed. Theoretical results and numerical simulations are in good
quantitative agreement.Comment: 5 pages, 5 figure
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