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The pupillary response of cephalopods
This paper provides the first detailed description of the time courses of light-evoked pupillary constriction for two species of cephalopods, Sepia officinalis (a cuttlefish) and Eledone cirrhosa (an octopus). The responses are much faster than hitherto reported, full contraction in Sepia taking less than 1 s, indicating it is among the most rapid pupillary responses in the animal kingdom. We also describe the dependence of the degree of pupil constriction on the level of ambient illumination and show considerable variability between animals. Furthermore, both Sepia and Eledone lack a consensual light-evoked pupil response. Pupil dilation following darkness in Sepia is shown to be very variable, often occurring within a second but at other times taking considerably longer. This may be the result of extensive light-independent variations in pupil diameter in low levels of illumination
Hydrogenated grain boundaries in graphene
We have investigated by means of first principles calculations the structural
and electronic properties of hydrogenated graphene structures with distinct
grain boundary defects. Our total energy results reveal that the adsorption of
a single H is more stable at grain boundary defect. The electronic structure of
the grains boundaries upon hydrogen adsorption have been examined. Further
total energy calculations indicate that the adsorption of two H on two neighbor
carbons, forming a basic unit of graphane, is more stable at the defect region.
Therefore, we expect that these extended defects would work as a nucleation
region for the formation of a narrow graphane strip embedded in graphene
region
Addendum to paper: Strong-Coupling Behavior of -Theories and Critical Exponents [Phys. Rev. D 57, 2264 (1998)]
The graphical extrapolation procedure to infinite order of variational
perturbation theory in a recent calculation of critical exponents of
three-dimensional -theories at infinite couplings is improved by
another way of plotting the results.Comment: Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper also at
http://www.physik.fu-berlin.de/~kleinert/kleiner_re257a/preprint.htm
Duality, Time-asymmetry and the Condensation of Vacuum
A variant of the divergence theory for vacuum-condensation developed in a
previous communication is analyzed from the viewpoint of a 'time' asymmetric
law in vacuum. This law is found to establish a substantial distinction between
dynamically allowed vacuum-configurations related by signature changing duality
transformations.Comment: 6 pages, latex fil
Digital computer processing of X-ray photos
Digital computers correct various distortions in medical and biological photographs. One of the principal methods of computer enhancement involves the use of a two-dimensional digital filter to modify the frequency spectrum of the picture. Another computer processing method is image subtraction
Study of a colliding laser-produced plasma by analysis of time and space-resolved image spectra
The interaction of two counter-propagating laser-produced plasmas was studied using simultaneous
imaging and spectroscopic techniques. Spectrally-filtered time-gated ICCD imaging was used
to obtain information about the spatial dynamics and temporal evolution of the collision process.
While, time-resolved imaging spectroscopy was used to determine the spatial and temporal distributions
of electron temperature and density within the interaction region. We examine specifically
the interaction of plasmas whose parameters match those typically used in pulsed laser deposition
of thin films. These low temperature plasmas are highly collisional leading to the creation of a
pronounced stagnation layer in the interaction region
Unbroken versus broken mirror world: a tale of two vacua
If the Lagrangian of nature respects parity invariance then there are two
distinct possibilities: either parity is unbroken by the vacuum or it is
spontaneously broken. We examine the two simplest phenomenologically consistent
gauge models which have unbroken and spontaneously broken parity symmetries,
respectively. These two models have a Lagrangian of the same form, but a
different parameter range is chosen in the Higgs potential. They both predict
the existence of dark matter and can explain the MACHO events. However, the
models predict quite different neutrino physics. Although both have light
mirror (effectively sterile) neutrinos, the ordinary-mirror neutrino mixing
angles are unobservably tiny in the broken parity case. The minimal broken
parity model therefore cannot simultaneously explain the solar, atmospheric and
LSND data. By contrast, the unbroken parity version can explain all of the
neutrino anomalies. Furthermore, we argue that the unbroken case provides the
most natural explanation of the neutrino physics anomalies (irrespective of
whether evidence from the LSND experiment is included) because of its
characteristic maximal mixing prediction.Comment: About 15 pages, Late
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Subsolar noble gases in an acid-resistant residue of the EH5 chondrite St Mark's
Extract from the introduction: Enstatite chondrites have remarkable properties: they were formed in a reducing environment, they are putatively similar to precursor material of Earth, Venus, or Mercury, have a terrestrial oxygen isotopic composition and an uncommon noble gas signature [1-5]. Trapped noble gases in Echondrites are intermediate between solar and chondritic composition and consist of two components: Subsolar, enriched in Ar and Kr relative to Xe and Q-gas, possibly residing in enstatite, micro-vesicles or graphite within enstatite [6,7] and Q-gases [5,8]
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