5,029 research outputs found
Optical modeling of agricultural fields and rough-textured rock and mineral surfaces
Review was made of past models for describing the reflectance and/or emittance properties of agricultural/forestry and geological targets in an effort to select the best theoretical models. An extension of the six parameter Allen-Gayle-Richardson model was chosen as the agricultural plant canopy model. The model is used to predict the bidirectional reflectance of a field crop from known laboratory spectra of crop components and approximate plant geometry. The selected geological model is based on Mie theory and radiative transfer equations, and will assess the effect of textural variations of the spectral emittance of natural rock surfaces
Approximate resonance states in the semigroup decomposition of resonance evolution
The semigroup decomposition formalism makes use of the functional model for
class contractive semigroups for the description of the time evolution
of resonances. For a given scattering problem the formalism allows for the
association of a definite Hilbert space state with a scattering resonance. This
state defines a decomposition of matrix elements of the evolution into a term
evolving according to a semigroup law and a background term. We discuss the
case of multiple resonances and give a bound on the size of the background
term. As an example we treat a simple problem of scattering from a square
barrier potential on the half-line.Comment: LaTex 22 pages 3 figure
Galilean limit of equilibrium relativistic mass distribution for indistinguishable events
The relativistic distribution for indistinguishable events is considered in
the mass-shell limit where is a given intrinsic property of
the events. The characteristic thermodynamic quantities are calculated and
subject to the zero-mass and the high-temperature limits. The results are shown
to be in agreement with the corresponding expressions of an on-mass-shell
relativistic kinetic theory. The Galilean limit which
coincides in form with the low-temperature limit, is considered. The theory is
shown to pass over to a nonrelativistic statistical mechanics of
indistinguishable particles.Comment: Report TAUP-2136-9
Equilibrium Relativistic Mass Distribution for Indistinguishable Events
A manifestly covariant relativistic statistical mechanics of the system of
indistinguishable events with motion in space-time parametrized by an
invariant ``historical time'' is considered. The relativistic mass
distribution for such a system is obtained from the equilibrium solution of the
generalized relativistic Boltzmann equation by integration over angular and
hyperbolic angular variables. All the characteristic averages are calculated.
Expressions for the pressure and the density of events are found and the
relativistic equation of state is obtained. The Galilean limit is considered;
the theory is shown to pass over to the usual nonrelativistic statistical
mechanics of indistinguishable particles.Comment: TAUP-2115-9
Covariant Equilibrium Statistical Mechanics
A manifest covariant equilibrium statistical mechanics is constructed
starting with a 8N dimensional extended phase space which is reduced to the 6N
physical degrees of freedom using the Poincare-invariant constrained
Hamiltonian dynamics describing the micro-dynamics of the system. The reduction
of the extended phase space is initiated forcing the particles on energy shell
and fixing their individual time coordinates with help of invariant time
constraints. The Liouville equation and the equilibrium condition are
formulated in respect to the scalar global evolution parameter which is
introduced by the time fixation conditions. The applicability of the developed
approach is shown for both, the perfect gas as well as the real gas. As a
simple application the canonical partition integral of the monatomic perfect
gas is calculated and compared with other approaches. Furthermore,
thermodynamical quantities are derived. All considerations are shrinked on the
classical Boltzmann gas composed of massive particles and hence quantum effects
are discarded.Comment: 22 pages, 1 figur
A New Relativistic High Temperature Bose-Einstein Condensation
We discuss the properties of an ideal relativistic gas of events possessing
Bose-Einstein statistics. We find that the mass spectrum of such a system is
bounded by where is the usual chemical
potential, is an intrinsic dimensional scale parameter for the motion of an
event in space-time, and is an additional mass potential of the
ensemble. For the system including both particles and antiparticles, with
nonzero chemical potential the mass spectrum is shown to be bounded by
and a special type of high-temperature
Bose-Einstein condensation can occur. We study this Bose-Einstein condensation,
and show that it corresponds to a phase transition from the sector of
continuous relativistic mass distributions to a sector in which the boson mass
distribution becomes sharp at a definite mass This phenomenon
provides a mechanism for the mass distribution of the particles to be sharp at
some definite value.Comment: Latex, 22 page
On the Resolution of Time Problem in Quantum Gravity Induced from Unconstrained Membranes
The relativistic theory of unconstrained -dimensional membranes
(-branes) is further developed and then applied to the embedding model of
induced gravity. Space-time is considered as a 4-dimensional unconstrained
membrane evolving in an -dimensional embedding space. The parameter of
evolution or the evolution time is a distinct concept from the
coordinate time . Quantization of the theory is also discussed. A
covariant functional Schr\" odinger equations has a solution for the wave
functional such that it is sharply localized in a certain subspace of
space-time, and much less sharply localized (though still localized) outside
. With the passage of evolution the region moves forward in space-time.
Such a solution we interpret as incorporating two seemingly contradictory
observations: (i) experiments clearly indicate that space-time is a continuum
in which events are existing; (ii) not the whole 4-dimensional space-time, but
only a 3-dimensional section which moves forward in time is accessible to our
immediate experience. The notorious problem of time is thus resolved in our
approach to quantum gravity. Finally we include sources into our unconstrained
embedding model. Possible sources are unconstrained worldlines which are free
from the well known problem concerning the Maxwell fields generated by charged
unconstrained point particles.Comment: 22 Page
Chronic destructive arthritis as an isolated symptom of familial Mediterranean fever (FMF) in a 17 year old Turkish boy
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