24,537 research outputs found
Luminescence of Apollo 11 and 12 lunar samples
Luminescence of Apollo 11 and 12 rocks measured with UV, X ray, and proton radiatio
Microcanonical mean-field thermodynamics of self-gravitating and rotating systems
We derive the global phase diagram of a self-gravitating -body system
enclosed in a finite three-dimensional spherical volume as a function of
total energy and angular momentum, employing a microcanonical mean-field
approach. At low angular momenta (i.e. for slowly rotating systems) the known
collapse from a gas cloud to a single dense cluster is recovered. At high
angular momenta, instead, rotational symmetry can be spontaneously broken and
rotationally asymmetric structures (double clusters) appear.Comment: 4 pages, 4 figures; to appear in Phys. Rev. Let
Theoretical investigation of finite size effects at DNA melting
We investigated how the finiteness of the length of the sequence affects the
phase transition that takes place at DNA melting temperature. For this purpose,
we modified the Transfer Integral method to adapt it to the calculation of both
extensive (partition function, entropy, specific heat, etc) and non-extensive
(order parameter and correlation length) thermodynamic quantities of finite
sequences with open boundary conditions, and applied the modified procedure to
two different dynamical models. We showed that rounding of the transition
clearly takes place when the length of the sequence is decreased. We also
performed a finite-size scaling analysis of the two models and showed that the
singular part of the free energy can indeed be expressed in terms of an
homogeneous function. However, both the correlation length and the average
separation between paired bases diverge at the melting transition, so that it
is no longer clear to which of these two quantities the length of the system
should be compared. Moreover, Josephson's identity is satisfied for none of the
investigated models, so that the derivation of the characteristic exponents
which appear, for example, in the expression of the specific heat, requires
some care
GEOS A readiness test evaluation report
Prelaunch and postlaunch readiness tests of geodetic earth orbiting satellite and optical tracking participatio
Enumerative aspects of the Gross-Siebert program
We present enumerative aspects of the Gross-Siebert program in this
introductory survey. After sketching the program's main themes and goals, we
review the basic definitions and results of logarithmic and tropical geometry.
We give examples and a proof for counting algebraic curves via tropical curves.
To illustrate an application of tropical geometry and the Gross-Siebert program
to mirror symmetry, we discuss the mirror symmetry of the projective plane.Comment: A version of these notes will appear as a chapter in an upcoming
Fields Institute volume. 81 page
Investigation of planetary ionospheres
Feasibility of using radio sounding techniques to investigate ionospheric properties of planet
Star Algebra Spectroscopy
The spectrum of the infinite dimensional Neumann matrices M^{11}, M^{12} and
M^{21} in the oscillator construction of the three-string vertex determines key
properties of the star product and of wedge and sliver states. We study the
spectrum of eigenvalues and eigenvectors of these matrices using the derivation
K_1 = L_1 + L_{-1} of the star algebra, which defines a simple infinite matrix
commuting with the Neumann matrices. By an exact calculation of the spectrum of
K_1, and by consideration of an operator generating wedge states, we are able
to find analytic expressions for the eigenvalues and eigenvectors of the
Neumann matrices and for the spectral density. The spectrum of M^{11} is
continuous in the range [-1/3, 0) with degenerate twist even and twist odd
eigenvectors for every eigenvalue except for -1/3.Comment: LaTeX, 30 pages, 2 figure
Feasibility study of the ultraviolet spectral analysis of the lunar surface
Ultraviolet spectral analysis of granite, gabbro, and serpentinite samples to determine feasibility of mapping surface composition of moo
Siegel Gauge in Vacuum String Field Theory
We study the star algebra of ghost sector in vacuum string field theory
(VSFT). We show that the star product of two states in the Siegel gauge is BRST
exact if we take the BRST charge to be the one found in hep-th/0108150, and the
BRST exact states are nil factors in the star algebra. By introducing a new
star product defined on the states in the Siegel gauge, the equation of motion
of VSFT is characterized as the projection condition with respect to this new
product. We also comment on the comma form of string vertex in the ghost
sector.Comment: 13 pages, lanlmac; v3: comment adde
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