34,615 research outputs found
Late Triassic (Rhaetian) conodonts and ichthyoliths from Chile
The Late Triassic of the back arc Domeyko Basin, Chile is characterized by the onset of marine sedimentation that persisted throughout the rest of the Mesozoic. Carbonate bulk samples from the Punta del Viento Limestone Formation have yielded a numerically small, but apparently widespread, conodont fauna including Epigondolella mosheri, Epigondolella englandi and Neogondolella steinbergensis. These specimens indicate a Rhaetian (Epigondolella mosheri conodont Biozone roughly equivalent to the Paracochloceras amoenum ammonoid Biozone) age for this unit. Their recovery represents the first record of conodonts from Chile, and also indicates a considerable potential for use in correlating sequence stratigraphic events within the Mesozoic Marginal Sea in Colombia, Peru and Chile
Long Range Forces in Quantum Gravity
We calculate the leading quantum and semi-classical corrections to the
Newtonian potential energy of two widely separated static masses. In this
large-distance, static limit, the quantum behaviour of the sources does not
contribute to the quantum corrections of the potential. These arise exclusively
from the propagation of massless degrees of freedom. Our one-loop result is
based on Modanese's formulation and is in disagreement with Donoghue's recent
calculation. Also, we compare and contrast the structural similarities of our
approach to scattering at ultra-high energy and large impact parameter. We
connect our approach to results from string perturbation theory.Comment: 26 pages, REVTEX, six PostScript figures in separate uuencoded file
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The Extended Invariant Factor Algorithm with Application to the Forney Analysis of Convolutional Codes
In his celebrated paper on the algebraic structure of convolutional codes, Forney showed that by using the invariant-factor theorem, one can transform an arbitrary polynomial generator matrix for an (n, k) convolutional code C into a basic (and ultimately a minimal) generator matrix for C. He also showed how to find a polynomial inverse for a basic generator matrix for C, and a basic generator matrix for the dual code C^⊥. In this paper, we will discuss efficient ways to do all these things. Our main tool is the “entended invariant factor algorithm,” which we introduce here
TVS-cone metric spaces as a special case of metric spaces
There have been a number of generalizations of fixed point results to the so
called TVS-cone metric spaces, based on a distance function that takes values
in some cone with nonempty interior (solid cone) in some topological vector
space. In this paper we prove that the TVS-cone metric space can be equipped
with a family of mutually equivalent (usual) metrics such that the convergence
(resp. property of being Cauchy sequence, contractivity condition) in TVS sense
is equivalent to convergence (resp. property of being Cauchy sequence,
contractivity condition) in all of these metrics. As a consequence, we prove
that if a topological vector space and a solid cone are given, then the
category of TVS-cone metric spaces is a proper subcategory of metric spaces
with a family of mutually equivalent metrics (Corollary 3.9). Hence,
generalization of a result from metric spaces to TVS-cone metric spaces is
meaningless. This, also, leads to a formal deriving of fixed point results from
metric spaces to TVS-cone metric spaces and makes some earlier results vague.
We also give a new common fixed point result in (usual) metric spaces context,
and show that it can be reformulated to TVS-cone metric spaces context very
easy, despite of the fact that formal (syntactic) generalization is impossible.
Apart of main results, we prove that the existence of a solid cone ensures that
the initial topology is Hausdorff, as well as it admits a plenty of convex open
sets. In fact such topology is stronger then some norm topology.Comment: 14 page
Getting a start in dairying in Alaska
Dairying in Alaska probably will always be confined to areas where milk can reach city markets readily. The demand £or fresh milk, even at present prices, exceeds the supply. Probably the dairy farmer always will be able to produce milk in competition with fluid mlik shipped in from the States if he is a good manager and has high producing cows. A farmer with low producing cows can show a profit at present prices, but if the price of milk dropped two dollars or more per hundred, he would have a tough time making both ends meet. It is doubtful if other dairy products can be produced in Alaska to compete with stateside prices
Heat Determinant on Manifolds
We introduce and study new invariants associated with Laplace type elliptic
partial differential operators on manifolds. These invariants are constructed
by using the off-diagonal heat kernel; they are not pure spectral invariants,
that is, they depend not only on the eigenvalues but also on the corresponding
eigenfunctions in a non-trivial way. We compute the first three low-order
invariants explicitly.Comment: 41 page
Thermal instability of a compound resonator
We investigate the thermal and Kerr nonlinearity in a system of two optically-coupled silica microtoroid resonators experimentally and theoretically. A model for two coupled oscillators describing nonlinear resonance curves is developed. Stability of the static solutions is analyzed. It is shown that thermal nonlinearity is responsible for driving the eigenfrequencies of the two resonators apart, making the normal modes of the system unstable as the pump power grows. The red-detuned normal mode becomes unstable for certain pumping powers
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