177,927 research outputs found

    Pioneer Anomaly and the Helicity-Rotation Coupling

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    The modification of the Doppler effect due to the coupling of the helicity of the radiation with the rotation of the source/receiver is considered in the case of the Pioneer 10/11 spacecraft. We explain why the Pioneer anomaly is not influenced by the helicity-rotation coupling.Comment: LaTeX file, 1 figure, 6 pages, v2: note and figure added at the end of the paper, to be published in Phys. Lett.

    On vv--domains and star operations

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    Let ∗\ast be a star operation on an integral domain DD. Let \f(D) be the set of all nonzero finitely generated fractional ideals of DD. Call DD a ∗\ast--Pr\"ufer (respectively, (∗,v)(\ast, v)--Pr\"ufer) domain if (FF−1)∗=D(FF^{-1})^{\ast}=D (respectively, (FvF−1)∗=D(F^vF^{-1})^{\ast}=D) for all F\in \f(D). We establish that ∗\ast--Pr\"ufer domains (and (∗,v)(\ast, v)--Pr\"ufer domains) for various star operations ∗\ast span a major portion of the known generalizations of Pr\"{u}fer domains inside the class of vv--domains. We also use Theorem 6.6 of the Larsen and McCarthy book [Multiplicative Theory of Ideals, Academic Press, New York--London, 1971], which gives several equivalent conditions for an integral domain to be a Pr\"ufer domain, as a model, and we show which statements of that theorem on Pr\"ufer domains can be generalized in a natural way and proved for ∗\ast--Pr\"ufer domains, and which cannot be. We also show that in a ∗\ast --Pr\"ufer domain, each pair of ∗\ast -invertible ∗\ast -ideals admits a GCD in the set of ∗\ast -invertible ∗\ast -ideals, obtaining a remarkable generalization of a property holding for the "classical" class of Pr\"ufer vv--multiplication domains. We also link DD being ∗\ast --Pr\"ufer (or (∗,v)(\ast, v)--Pr\"ufer) with the group Inv∗(D)^{\ast}(D) of ∗\ast -invertible ∗\ast -ideals (under ∗\ast-multiplication) being lattice-ordered

    The ground state and the long-time evolution in the CMC Einstein flow

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    Let (g,K)(k) be a CMC (vacuum) Einstein flow over a compact three-manifold M with non-positive Yamabe invariant (Y(M)). As noted by Fischer and Moncrief, the reduced volume V(k)=(-k/3)^{3}Vol_{g(k)}(M) is monotonically decreasing in the expanding direction and bounded below by V_{\inf}=(-1/6)Y(M))^{3/2}. Inspired by this fact we define the ground state of the manifold M as "the limit" of any sequence of CMC states {(g_{i},K_{i})} satisfying: i. k_{i}=-3, ii. V_{i} --> V_{inf}, iii. Q_{0}((g_{i},K_{i}))< L where Q_{0} is the Bel-Robinson energy and L is any arbitrary positive constant. We prove that (as a geometric state) the ground state is equivalent to the Thurston geometrization of M. Ground states classify naturally into three types. We provide examples for each class, including a new ground state (the Double Cusp) that we analyze in detail. Finally consider a long time and cosmologically normalized flow (\g,\K)(s)=((-k/3)^{2}g,(-k/3))K) where s=-ln(-k) is in [a,\infty). We prove that if E_{1}=E_{1}((\g,\K))< L (where E_{1}=Q_{0}+Q_{1}, is the sum of the zero and first order Bel-Robinson energies) the flow (\g,\K)(s) persistently geometrizes the three-manifold M and the geometrization is the ground state if V --> V_{inf}.Comment: 40 pages. This article is an improved version of the second part of the First Version of arXiv:0705.307

    A method for calculating the effects of design errors and measurement errors on pump performance

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    Technique has been developed for calculating effects of design errors and measurement errors on pump performance. Error equations and charts are utilized to relate amount of error in given performance parameter to amount of error in given design or measured variable. Error equations were derived primarily for axial flow pumps, but are not limited to axial flow

    Systematics of the North American menhadens: molecular evolutionary reconstructions in the genus Brevoortia (Clupeiformes: Clupeidae)

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    Evolutionary associations among the four North American species of menhadens (Brevoortia spp.) have not been thoroughly investigated. In the present study, classifications separating the four species into small-scaled and large-scaled groups were evaluated by using DNA data, and genetic associations within these groups were explored. Specifically, data from the nuclear genome (microsatellites) and the mitochondrial genome (mtDNA sequences) were used to elicit patterns of recent and historical evolutionary associations. Nuclear DNA data indicated limited contemporary gene flow among the species, and also indicated higher relatedness within the small-scaled and large-scaled menhadens than between these groups. Mitochondrial DNA sequences of the large-scaled menhadens indicated the presence of two ancestral lineages, one of which contained members of both species. This result may indicate genetic diver-gence (reproductive isolation) followed by secondary contact (hybridization) between these species. In contrast, a single ancestral lineage indicated incomplete genetic divergence between the small-scaled menhaden. These results are discussed in the context of the biology and demographics of each species

    Phase detector assembly Patent

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    Detector assembly for discriminating first signal with respect to presence or absence of second signal at time of occurrence of first signa

    Reaching DEEP in Math (Developing Educational Excellence and Proficiency in Mathematics)

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    This paper describes the DEEP in Math Program developed in the academic year 1998-1999 from a collaborative effort of the Louisiana Systemic lnitiative Program (LaSlP) and the Louisiana Department of Education (LDE). It includes evidence of impressive results in low achieving schools and in high-poverty districts targeted by the effort. The plan was for LaSlP to give intensive content and leadership training in Summer 1999 and academic year 1999-2000 to carefully selected. well-qualified math leaders. These leaders were then employed full-time in the 1999-2000 academic year and beyond by their local education authorities to work with all math teachers in a few designated schools at some cohesive subset of grades 3-8
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