1,375 research outputs found
Phonons and specific heat of linear dense phases of atoms physisorbed in the grooves of carbon nanotube bundles
The vibrational properties (phonons) of a one-dimensional periodic phase of
atoms physisorbed in the external groove of the carbon nanotube bundle are
studied. Analytical expressions for the phonon dispersion relations are
derived. The derived expressions are applied to Xe, Kr and Ar adsorbates. The
specific heat pertaining to dense phases of these adsorbates is calculated.Comment: 4 PS figure
IL-6 counteracts the inhibitory effect of IL-4 on osteogenic differentiation of human adipose stem cells
Laser beam attenuation in LIF measurements on NO in a diesel engine
The effect of laser beam attenuation on nitric oxide measurements in a diesel engine is presented. A number ofexperimental ways to correct for this attenuation are discussed: transmission measurements, bidirectional laserinducedfluorescence, and Raman scattering by N2. Comparison of the results indicates that the attenuation isgenerally not uniform over the cylinder. Instead it seems to be less severe over the field of view (i.e. the upper partof the cylinder)
Laser beam attenuation in LIF measurements on NO in a diesel engine
The effect of laser beam attenuation on nitric oxide measurements in a diesel engine is presented. A number ofexperimental ways to correct for this attenuation are discussed: transmission measurements, bidirectional laserinducedfluorescence, and Raman scattering by N\u3csub\u3e2\u3c/sub\u3e. Comparison of the results indicates that the attenuation isgenerally not uniform over the cylinder. Instead it seems to be less severe over the field of view (i.e. the upper partof the cylinder)
Quantitative nitric oxide measurements by means of laser-induced fluorescence in a heavy-duty Diesel engine
Quantitative in-cylinder laser-induced fluorescence measurements ofnitric oxide in a heavy-duty Diesel engine are presented. Special attention is paid to experimental techniques to assess the attenuation of the laser beam and the fluorescence signal by the cylinder contents.This attenuation can be considerable at certain stages in the combustionstroke. The temperature and pressure dependence of the fluorescence signal is described in various models. In this study, LIFsim was used.Finally, calibration was realized by concentration measurements in the exhaust gas
production in PHENIX
Heavy quarkonia production is expected to be sensitive to the formation of a
quark gluon plasma (QGP). The PHENIX experiment has measured
production at ~200 GeV in Au+Au and Cu+Cu collisions, as well
as in reference p+p and d+Au runs. 's were measured both at mid
() and forward () rapidity. In this letter, we present
the A+A preliminary results and compare them to normal cold nuclear matter
expectations derived from PHENIX d+Au and p+p measurements as well as to
theoretical models including various effects (color screening, recombination,
sequential melting...).Comment: 5 pages, 7 figures. To appear in the proceedings of Hot Quarks 2006:
Workshop for Young Scientists on the Physics of Ultrarelativistic
Nucleus-Nucleus Collisions, Villasimius, Italy, 15-20 May 200
Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption
Optical chaos is a topic of current research characterized by
high-dimensional nonlinearity which is attributed to the delay-induced
dynamics, high bandwidth and easy modular implementation of optical feedback.
In light of these facts, which adds enough confusion and diffusion properties
for secure communications, we explore the synchronization phenomena in
spatiotemporal semiconductor laser systems. The novel system is used in a
two-phase colored image encryption process. The high-dimensional chaotic
attractor generated by the system produces a completely randomized chaotic time
series, which is ideal in the secure encoding of messages. The scheme thus
illustrated is a two-phase encryption method, which provides sufficiently high
confusion and diffusion properties of chaotic cryptosystem employed with unique
data sets of processed chaotic sequences. In this novel method of cryptography,
the chaotic phase masks are represented as images using the chaotic sequences
as the elements of the image. The scheme drastically permutes the positions of
the picture elements. The next additional layer of security further alters the
statistical information of the original image to a great extent along the
three-color planes. The intermediate results during encryption demonstrate the
infeasibility for an unauthorized user to decipher the cipher image. Exhaustive
statistical tests conducted validate that the scheme is robust against noise
and resistant to common attacks due to the double shield of encryption and the
infinite dimensionality of the relevant system of partial differential
equations.Comment: 20 pages, 11 figures; Article in press, Optics Communications (2011
Investigation of the ferromagnetic transition in the correlated 4d perovskites SrRuRhO
The solid-solution SrRuRhO () is a
variable-electron-configuration system forming in the nearly-cubic-perovskite
basis, ranging from the ferromagnetic 4 to the enhanced paramagnetic
4. Polycrystalline single-phase samples were obtained over the whole
composition range by a high-pressure-heating technique, followed by
measurements of magnetic susceptibility, magnetization, specific heat,
thermopower, and electrical resistivity. The ferromagnetic order in long range
is gradually suppressed by the Rh substitution and vanishes at .
The electronic term of specific-heat shows unusual behavior near the critical
Rh concentration; the feature does not match even qualitatively with what was
reported for the related perovskites (Sr,Ca)RuO. Furthermore, another
anomaly in the specific heat was observed at .Comment: Accepted for publication in PR
Field dependence of the vortex structure in chiral p-wave superconductors
To investigate the different vortex structure between two chiral pairing p_x
+(-) i p_y, we calculate the pair potential, the internal field, the local
density of states, and free energy in the vortex lattice state based on the
quasiclassical Eilenberger theory, and analyze the magnetic field dependence.
The induced opposite chiral component of the pair potential plays an important
role in the vortex structure. It also produces H^{1/2}-behavior of the
zero-energy density of states at higher field. These results are helpful when
we understand the vortex states in Sr2RuO4.Comment: 11 pages, 10 figures, to be published in Phys. Rev.
A schematic model for QCD I: Low energy meson states
A simple model for QCD is presented, which is able to reproduce the meson
spectrum at low energy. The model is a Lipkin type model for quarks coupled to
gluons. The basic building blocks are pairs of quark-antiquarks coupled to a
definite flavor and spin. These pairs are coupled to pairs of gluons with spin
zero. The multiplicity problem, which dictates that a given experimental state
can be described in various manners, is removed when a particle-mixing
interaction is turned on. In this first paper of a series we concentrates on
the discussion of meson states at low energy, the so-called zero temperature
limit of the theory. The treatment of baryonic states is indicated, also.Comment: 29 pages, 6 figures. submitted to Phys. Rev.
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