2,666 research outputs found
Ultra high energy events in ECHOS series and primary energy spectrum
The compilation of ultra high energy jets suggests at present the existence of a bump in primary energy spectrum (with the standard concept of high energy collisions). The pseudo-rapidity distribution exhibits some typical anomalies, more than the (P sub t) behavior, which are (may be) the fingerprints of quark gluon plasma transition. The next results of Emulsion Chamber on Supersonic (ECHOS) will be in both cases determinant to confirm those tendancies, as well as an important effort of the cosmic ray community to develop in that sense a flying emulsion chamber experiment
How to relate the oscillator and Coulomb systems on spheres and pseudospheres?
We show that the oscillators on a sphere and pseudosphere are related, by the
so-called Bohlin transformation, with the Coulomb systems on the pseudosphere:
the even states of an oscillator yields the conventional Coulomb system on
pseudosphere, while the odd states yield the Coulomb system on pseudosphere in
the presence of magnetic flux tube generating half spin. In the higher
dimensions the oscillator and Coulomb(-like) systems are connected in the
similar way. In particular, applying the Kustaanheimo-Stiefel transformation to
the oscillators on sphere and pseudosphere, we obtained the preudospherical
generalization of MIC-Kepler problem describing three-dimensional charge-dyon
system.Comment: 12 pages, Based on talk given at XXIII Colloquium on Group
Theoretical Methods in Physics (July 31-August 5, 2000, Dubna
Chemiluminescence emission in cholesteric liquid crystalline core-shell microcapsules
Chemiluminescence behaviour in the core region of water/oil/water double emulsion droplets with cholesteric liquid crystalline (CLC) middle phase (CLC core-shell microcapsules) was demonstrated. We successfully fabricated CLC core-shell microcapsules containing an aqueous luminol solution as the inner phase using a microfluidic device, in which the helical axis of the CLC phase is normal to the surface. The CLC core-shell microcapsules proved to be a plausible candidate for highly sensitive H₂O₂ sensors because of the omnidirectional photonic structures of the CLC phase.Iwai Y., Kaji H., Uchida Y., et al. Chemiluminescence emission in cholesteric liquid crystalline core-shell microcapsules. Journal of Materials Chemistry C 2, 4904 (2014); https://doi.org/10.1039/c4tc00699b
Detection and Localization of Periodontopathic Bacteria in Abdominal Aortic Aneurysms
AbstractObjectivesWe examined a possible link between periodontal disease and abdominal aortic aneurysm (AAA) by studying resected aneurysmal specimens from AAA patients for the presence of periodontitopathic bacteria.DesignProspective case control study.Material and methodsThirty-two AAA patients were enrolled in the study. Periodontitis was classified according to the probing depth of preriodontal pocket. Thirty-two aneurysmal walls, 16 mural thrombi, 5 atherosclerotic occlusive aorta and 5 control arterial tissue, were examined for 7 periodontal bacteria using polymerase chain reaction (PCR) method. The localization of the bacteria in the aneurysmal/atherosclerotic wall was determined by thromboendarterectomy.ResultsAll patients had periodontal disease, and most cases were severe. PCR examination of the aneurysmal specimens showed that 86% were positive for periodontal bacterial DNA. No bacteria were detected in the control specimens. The bacteria were found in both the intimal/medial layer and the adventitial layer of the aneurysmal wall but only in intimal/medial layer of the atherosclerotic occlusive aorta.ConclusionPeriodontopathic bacteria were present in a high percentage of specimens of diseased arteries from AAA patients and were found throughout the whole aneurysmal wall. These bacteria may play a role in the development of AAAs and/or contribute to weakening the aneurysmal wall
Generalized Taub-NUT metrics and Killing-Yano tensors
A necessary condition that a St\"ackel-Killing tensor of valence 2 be the
contracted product of a Killing-Yano tensor of valence 2 with itself is
re-derived for a Riemannian manifold. This condition is applied to the
generalized Euclidean Taub-NUT metrics which admit a Kepler type symmetry. It
is shown that in general the St\"ackel-Killing tensors involved in the
Runge-Lenz vector cannot be expressed as a product of Killing-Yano tensors. The
only exception is the original Taub-NUT metric.Comment: 14 pages, LaTeX. Final version to appear in J.Phys.A:Math.Ge
Phase Transition in a One-Dimensional Extended Peierls-Hubbard Model with a Pulse of Oscillating Electric Field: I. Threshold Behavior in Ionic-to-Neutral Transition
Photoinduced dynamics of charge density and lattice displacements is
calculated by solving the time-dependent Schr\"odinger equation for a
one-dimensional extended Peierls-Hubbard model with alternating potentials for
the mixed-stack organic charge-transfer complex, TTF-CA. A pulse of oscillating
electric field is incorporated into the Peierls phase of the transfer integral.
The frequency, the amplitude, and the duration of the pulse are varied to study
the nonlinear and cooperative character of the photoinduced transition. When
the dimerized ionic phase is photoexcited, the threshold behavior is clearly
observed by plotting the final ionicity as a function of the increment of the
total energy. Above the threshold photoexcitation, the electronic state reaches
the neutral one with equidistant molecules after the electric field is turned
off. The transition is initiated by nucleation of a metastable neutral domain,
for which an electric field with frequency below the linear absorption peak is
more effective than that at the peak. When the pulse is strong and short, the
charge transfer takes place on the same time scale with the disappearance of
dimerization. As the pulse becomes weak and long, the dimerization-induced
polarization is disordered to restore the inversion symmetry on average before
the charge transfer takes place to bring the system neutral. Thus, a
paraelectric ionic phase is transiently realized by a weak electric field. It
is shown that infrared light also induces the ionic-to-neutral transition,
which is characterized by the threshold behavior.Comment: 24 pages, 11 figure
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