5,179 research outputs found
Who is that? Brain networks and mechanisms for identifying individuals
Social animals can identify conspecifics by many forms of sensory input. However, whether the neuronal computations that support this ability to identify individuals rely on modality-independent convergence or involve ongoing synergistic interactions along the multiple sensory streams remains controversial. Direct neuronal measurements at relevant brain sites could address such questions, but this requires better bridging the work in humans and animal models. Here, we overview recent studies in nonhuman primates on voice and face identity-sensitive pathways and evaluate the correspondences to relevant findings in humans. This synthesis provides insights into converging sensory streams in the primate anterior temporal lobe (ATL) for identity processing. Furthermore, we advance a model and suggest how alternative neuronal mechanisms could be tested
Local structure of In_(0.5)Ga_(0.5)As from joint high-resolution and differential pair distribution function analysis
High resolution total and indium differential atomic pair distribution
functions (PDFs) for In_(0.5)Ga_(0.5)As alloys have been obtained by high
energy and anomalous x-ray diffraction experiments, respectively. The first
peak in the total PDF is resolved as a doublet due to the presence of two
distinct bond lengths, In-As and Ga-As. The In differential PDF, which involves
only atomic pairs containing In, yields chemical specific information and helps
ease the structure data interpretation. Both PDFs have been fit with structure
models and the way in that the underlying cubic zinc-blende lattice of
In_(0.5)Ga_(0.5)As semiconductor alloy distorts locally to accommodate the
distinct In-As and Ga-As bond lengths present has been quantified.Comment: 9 pages, 7 figur
Polyhedral units and network connectivity in calcium aluminosilicate glasses from high-energy x-ray diffraction
Structure factors for Cax/2AlxSi1-xO2 glasses (x=0,0.25,0.5,0.67) extended to
a wave vector of magnitude Q= 40 1/A have been obtained by high-energy x-ray
diffraction. For the first time, it is possible to resolve the contributions of
Si-O, Al-O and Ca-O coordination polyhedra to the experimental atomic pair
distribution functions (PDF). It has been found that both Si and Al are
four-fold coordinated and so participate in a continuous tetrahedral network at
low values of x. The number of network breaking defects in the form of
non-bridging oxygens (NBO's) increases slowly with x until x=0.5 (NBO's ~ 10%
at x=0.5). By x=0.67 the network breaking defects become significant as
evidenced by the significant drop in the average coordination number of Si. By
contrast, Al-O tetrahedra remain free of NBO's and fully integrated in the
Al/Si-O network for all values of x. Calcium maintains a rather uniform
coordination sphere of approximately 5 oxygen atoms for all values of x. The
results suggest that not only Si/Al-O tetrahedra but Ca-O polyhedra, too, play
a role in determining the glassy structure
CONSIDERATIONS ON THE RESULTS OF EXCISIONAL HEPATIC BIOPSIES IN SOME HEPATOBILIARY AFFECTIONS
No abstract
Low-angle misorientation dependence of the optical properties of InGaAs/InAlAs quantum wells
We investigate the dependence of the low-temperature photoluminescence
linewidths from InP-lattice-matched InGaAs/InAlAs quantum wells on the
low-angle misorientation from the (100) surface of the host InP substrate.
Quantum wells were grown on InP substrates misorientated by 0, 0.2, 0.4 and 0.6
degrees; 0.4 degrees was found to consistently result in the narrowest peaks,
with the optimal spectral purity of ~4.25 meV found from a 15nm quantum well.
The width of the emission from the 15nm quantum well was used to optimize the
growth parameters. Thick layers of Si-doped InGaAs were then grown and found to
have bulk, low temperature (77 K), electron mobilities up to \mu ~ 3.5 x 10^4
cm2/Vs with an electron concentration of ~1 x 10^16
Evidence for shape coexistence in Mo
A angular correlation experiment has been performed to
investigate the low-energy states of the nucleus Mo. The new data,
including spin assignments, multipole mixing ratios and lifetimes reveal
evidence for shape coexistence and mixing in Mo, arising from a proton
intruder configuration. This result is reproduced by a theoretical calculation
within the proton-neutron interacting boson model with configuration mixing,
based on microscopic energy density functional theory. The microscopic
calculation indicates the importance of the proton particle-hole excitation
across the Z=40 sub-shell closure and the subsequent mixing between spherical
vibrational and the -soft equilibrium shapes in Mo.Comment: 6 pages, 5 figures, 3 tables; published in Phys. Rev.
Sum Rule Approach to the Isoscalar Giant Monopole Resonance in Drip Line Nuclei
Using the density-dependent Hartree-Fock approximation and Skyrme forces
together with the scaling method and constrained Hartree-Fock calculations, we
obtain the average energies of the isoscalar giant monopole resonance. The
calculations are done along several isotopic chains from the proton to the
neutron drip lines. It is found that while approaching the neutron drip line,
the scaled and the constrained energies decrease and the resonance width
increases. Similar but smaller effects arise near the proton drip line,
although only for the lighter isotopic chains. A qualitatively good agreement
is found between our sum rule description and the presently existing random
phase approximation results. The ability of the semiclassical approximations of
the Thomas-Fermi type, which properly describe the average energy of the
isoscalar giant monopole resonance for stable nuclei, to predict average
properties for nuclei near the drip lines is also analyzed. We show that when
hbar corrections are included, the semiclassical estimates reproduce, on
average, the quantal excitation energies of the giant monopole resonance for
nuclei with extreme isospin values.Comment: 31 pages, 12 figures, revtex4; some changes in text and figure
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