157 research outputs found
Quantum Interference: From Kaons to Neutrinos (with Quantum Beats in between)
Using the vehicle of resolving an apparent paradox, a discussion of quantum
interference is presented. The understanding of a number of different physical
phenomena can be unified, in this context. These range from the neutral kaon
system to massive neutrinos, not to mention quantum beats, Rydberg wave
packets, and neutron gravity.Comment: 12 pages, LaTeX, 3 figure
Conoscopic patterns in photonic band gap of cholesteric liquid crystal cells with twist defects
We theoretically investigate into the effects of the incidence angles in
light transmission of cholesteric liquid crystal two-layer sandwich structures
with twist defects created by rotation of the one layer about the helical
axis.The conoscopic images and polarization resolved patterns are obtained for
thick layers by computing the intensity and the polarization parameters as a
function of the incidence angles.In addition to the defect angle induced
rotation of the pictures as a whole, the rings of defect mode resonances are
found to shrink to the origin and disappear as the defect twist angle varies
from zero to its limiting value and beyond.Comment: revtex4, 7 pages, 4 figure
A review of diagnostic and functional imaging in headache
The neuroimaging of
headache patients has revolutionised
our understanding of the pathophysiology
of primary headaches and provided
unique insights into these syndromes.
Modern imaging studies
point, together with the clinical picture,
towards a central triggering
cause. The early functional imaging
work using positron emission
tomography shed light on the genesis
of some syndromes, and has
recently been refined, implying that
the observed activation in migraine
(brainstem) and in several trigeminal-autonomic headaches (hypothalamic
grey) is involved in the pain
process in either a permissive or
triggering manner rather than simply
as a response to first-division nociception
per se. Using the advanced
method of voxel-based morphometry,
it has been suggested that there
is a correlation between the brain
area activated specifically in acute
cluster headache — the posterior
hypothalamic grey matter — and an
increase in grey matter in the same
region. No structural changes have
been found for migraine and medication
overuse headache, whereas
patients with chronic tension-type
headache demonstrated a significant
grey matter decrease in regions
known to be involved in pain processing.
Modern neuroimaging thus
clearly suggests that most primary
headache syndromes are predominantly
driven from the brain, activating
the trigeminovascular reflex and
needing therapeutics that act on both
sides: centrally and peripherally
Theoretical discussion of the scanning tunneling microscope applied to a semiconductor surface
Examining Agreement and Longitudinal Stability Among Traditional and RTI-Based Definitions of Reading Disability Using the Affected-Status Agreement Statistic
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