102,913 research outputs found
Boundary between Hadron and Quark/Gluon Structure of Nuclei
We show that the boundary between quark-dominated and hadron-dominated
regions of nuclear structure may be blurred by multi-nucleon quark clusters
arising from color percolation. Recent experiments supporting partial
percolation in cold nuclei and full percolation in hot/dense nuclear matter
include: deep inelastic lepton-nucleus scattering, relativistic heavy-ion
collisions and the binding energy in .Comment: 10 pages, 4 figures; added references; improved figures; fixed a typo
(wrong sign in Eqn 6); Fixed typos in Equation 2; updated reference
Germanium quantum dots: Optical properties and synthesis
Three different size distributions of Ge quantum dots (>~200, 110, and 60 Å) have been synthesized via the ultrasonic mediated reduction of mixtures of chlorogermanes and organochlorogermanes (or organochlorosilanes) by a colloidal sodium/potassium alloy in heptane, followed by annealing in a sealed pressure vessel at 270 °C. The quantum dots are characterized by transmission electron microscopy, x-ray powder diffraction, x-ray photoemission, infrared spectroscopy, and Raman spectroscopy. Colloidal suspensions of these quantum dots were prepared and their extinction spectra are measured with ultraviolet/visible (UV/Vis) and near infrared (IR) spectroscopy, in the regime from 0.6 to 5 eV. The optical spectra are correlated with a Mie theory extinction calculation utilizing bulk optical constants. This leads to an assignment of three optical features to the E(1), E(0'), and E(2) direct band gap transitions. The E(0') transitions exhibit a strong size dependence. The near IR spectra of the largest dots is dominated by E(0) direct gap absorptions. For the smallest dots the near IR spectrum is dominated by the Gamma25-->L indirect transitions
Intersection Information based on Common Randomness
The introduction of the partial information decomposition generated a flurry
of proposals for defining an intersection information that quantifies how much
of "the same information" two or more random variables specify about a target
random variable. As of yet, none is wholly satisfactory. A palatable measure of
intersection information would provide a principled way to quantify slippery
concepts, such as synergy. Here, we introduce an intersection information
measure based on the G\'acs-K\"orner common random variable that is the first
to satisfy the coveted target monotonicity property. Our measure is imperfect,
too, and we suggest directions for improvement.Comment: 19 pages, 5 figure
Charge modulations vs. strain waves in resonant x-ray scattering
A method is described for using resonant x-ray scattering to separately
quantify the charge (valence) modulation and the strain wave associated with a
charge density wave. The essence of the method is a separation of the atomic
form factor into a "raw" amplitude, fR(w), and a valence-dependent amplitude,
fD(w), which in many cases may be determined independently from absorption
measurements. The advantage of this separation is that the strain wave follows
the quantity |fR(w) + fD(w)|^2 whereas the charge modulation follows only
|fD(w)|^2. This allows the two distinct modulations to be quantified
separately. A scheme for characterizing a given CDW as Peierls-like or
Wigner-like naturally follows. The method is illustrated for an idealized model
of a one-dimensional chain.Comment: 6 pages, 4 figure
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