2,049 research outputs found
Criticality, Fractality and Intermittency in Strong Interactions
Assuming a second-order phase transition for the hadronization process, we
attempt to associate intermittency patterns in high-energy hadronic collisions
to fractal structures in configuration space and corresponding intermittency
indices to the isothermal critical exponent at the transition temperature. In
this approach, the most general multidimensional intermittency pattern,
associated to a second-order phase transition of the strongly interacting
system, is determined, and its relevance to present and future experiments is
discussed.Comment: 15 pages + 2 figures (available on request), CERN-TH.6990/93,
UA/NPPS-5-9
The random case of Conley's theorem: III. Random semiflow case and Morse decomposition
In the first part of this paper, we generalize the results of the author
\cite{Liu,Liu2} from the random flow case to the random semiflow case, i.e. we
obtain Conley decomposition theorem for infinite dimensional random dynamical
systems. In the second part, by introducing the backward orbit for random
semiflow, we are able to decompose invariant random compact set (e.g. global
random attractor) into random Morse sets and connecting orbits between them,
which generalizes the Morse decomposition of invariant sets originated from
Conley \cite{Con} to the random semiflow setting and gives the positive answer
to an open problem put forward by Caraballo and Langa \cite{CL}.Comment: 21 pages, no figur
Factorial Moments in a Generalized Lattice Gas Model
We construct a simple multicomponent lattice gas model in one dimension in
which each site can either be empty or occupied by at most one particle of any
one of species. Particles interact with a nearest neighbor interaction
which depends on the species involved. This model is capable of reproducing the
relations between factorial moments observed in high--energy scattering
experiments for moderate values of . The factorial moments of the negative
binomial distribution can be obtained exactly in the limit as becomes
large, and two suitable prescriptions involving randomly drawn nearest neighbor
interactions are given. These results indicate the need for considerable care
in any attempt to extract information regarding possible critical phenomena
from empirical factorial moments.Comment: 15 pages + 1 figure (appended as postscript file), REVTEX 3.0,
NORDITA preprint 93/4
Gauge-boson propagator in out of equilibrium quantum-field system and the Boltzmann equation
We construct from first principles a perturbative framework for studying
nonequilibrium quantum-field systems that include gauge bosons. The system of
our concern is quasiuniform system near equilibrium or nonequilibrium
quasistationary system. We employ the closed-time-path formalism and use the
so-called gradient approximation. No further approximation is introduced. We
construct a gauge-boson propagator, with which a well-defined perturbative
framework is formulated. In the course of construction of the framework, we
obtain the generalized Boltzmann equation (GBE) that describes the evolution of
the number-density functions of gauge-bosonic quasiparticles. The framework
allows us to compute the reaction rate for any process taking place in the
system. Various processes, in turn, cause an evolution of the systems, which is
described by the GBE.Comment: 28 page
Exogenous surfactant application in a rat lung ischemia reperfusion injury model: effects on edema formation and alveolar type II cells
<p>Abstract</p> <p>Background</p> <p>Prophylactic exogenous surfactant therapy is a promising way to attenuate the ischemia and reperfusion (I/R) injury associated with lung transplantation and thereby to decrease the clinical occurrence of acute lung injury and acute respiratory distress syndrome. However, there is little information on the mode by which exogenous surfactant attenuates I/R injury of the lung. We hypothesized that exogenous surfactant may act by limiting pulmonary edema formation and by enhancing alveolar type II cell and lamellar body preservation. Therefore, we investigated the effect of exogenous surfactant therapy on the formation of pulmonary edema in different lung compartments and on the ultrastructure of the surfactant producing alveolar epithelial type II cells.</p> <p>Methods</p> <p>Rats were randomly assigned to a control, Celsior (CE) or Celsior + surfactant (CE+S) group (n = 5 each). In both Celsior groups, the lungs were flush-perfused with Celsior and subsequently exposed to 4 h of extracorporeal ischemia at 4°C and 50 min of reperfusion at 37°C. The CE+S group received an intratracheal bolus of a modified natural bovine surfactant at a dosage of 50 mg/kg body weight before flush perfusion. After reperfusion (Celsior groups) or immediately after sacrifice (Control), the lungs were fixed by vascular perfusion and processed for light and electron microscopy. Stereology was used to quantify edematous changes as well as alterations of the alveolar epithelial type II cells.</p> <p>Results</p> <p>Surfactant treatment decreased the intraalveolar edema formation (mean (coefficient of variation): CE: 160 mm<sup>3 </sup>(0.61) vs. CE+S: 4 mm<sup>3 </sup>(0.75); p < 0.05) and the development of atelectases (CE: 342 mm<sup>3 </sup>(0.90) vs. CE+S: 0 mm<sup>3</sup>; p < 0.05) but led to a higher degree of peribronchovascular edema (CE: 89 mm<sup>3 </sup>(0.39) vs. CE+S: 268 mm<sup>3 </sup>(0.43); p < 0.05). Alveolar type II cells were similarly swollen in CE (423 μm<sup>3</sup>(0.10)) and CE+S (481 μm<sup>3</sup>(0.10)) compared with controls (323 μm<sup>3</sup>(0.07); p < 0.05 vs. CE and CE+S). The number of lamellar bodies was increased and the mean lamellar body volume was decreased in both CE groups compared with the control group (p < 0.05).</p> <p>Conclusion</p> <p>Intratracheal surfactant application before I/R significantly reduces the intraalveolar edema formation and development of atelectases but leads to an increased development of peribronchovascular edema. Morphological changes of alveolar type II cells due to I/R are not affected by surfactant treatment. The beneficial effects of exogenous surfactant therapy are related to the intraalveolar activity of the exogenous surfactant.</p
Where is the pseudoscalar glueball ?
The pseudoscalar mesons with the masses higher than 1 GeV are assumed to
belong to the meson decuplet including the glueball as the basis state
supplementing the standard nonet of light states
. The decuplet is investigated by means of an algebraic approach based
on hypothesis of vanishing the exotic commutators of "charges" and
their time derivatives. These commutators result in a system of equations
determining contents of the isoscalar octet state in the physical isoscalar
mesons as well as the mass formula including all masses of the decuplet:
, K(1460), , and . The physical
isoscalar mesons , are expressed as superpositions of the "ideal"
states ( and ) and the glueball with the mixing
coefficient matrix following from the exotic commutator restrictions. Among
four one-parameter families of the calculated mixing matrix (numerous solutions
result from bad quality of data on the and K(1460) masses) there is
one family attributing the glueball-dominant composition to the
meson. Similarity between the pseudoscalar and scalar decuplets, analogy
between the whole spectra of the and mesons and affinity of
the glueball with excited states are also noticed.Comment: 18 pp., 2. figs., 2 tabs.; Published version. One of the authors
withdraws his nam
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