23,889 research outputs found

    Luminescence of Apollo 11 and 12 lunar samples

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    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

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    We derive the global phase diagram of a self-gravitating NN-body system enclosed in a finite three-dimensional spherical volume VV 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

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    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

    Enumerative aspects of the Gross-Siebert program

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    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

    GEOS A readiness test evaluation report

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    Prelaunch and postlaunch readiness tests of geodetic earth orbiting satellite and optical tracking participatio

    Investigation of planetary ionospheres

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    Feasibility of using radio sounding techniques to investigate ionospheric properties of planet

    Star Algebra Spectroscopy

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    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

    Siegel Gauge in Vacuum String Field Theory

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    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

    Feasibility study of the ultraviolet spectral analysis of the lunar surface

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    Ultraviolet spectral analysis of granite, gabbro, and serpentinite samples to determine feasibility of mapping surface composition of moo

    Avoiding errors in progressive tetrahedralizations

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