2,447,534 research outputs found

    OGLE-TR-56

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    In early 2003 our team announced the discovery of the second extrasolar transiting planet, around the faint star OGLE-TR-56 (V = 16.6), based on the detection of small changes in the radial velocity of the primary. The star was originally identified as a candidate by the OGLE team from the shallow and periodic dips in its brightness. We present here new precise radial velocity measurements that confirm the variation measured earlier, supporting the conclusion that the companion is indeed a planet. Additional photometric observations are also available, which combined with the spectroscopy yield improved parameters (mass and radius) for the planet

    Laplace Tr ODE pdf

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    Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates. V. Follow-up of 30 OGLE Transits. New Candidates

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    We used VLT/VIMOS images in the V band to obtain light curves of extrasolar planetary transits OGLE-TR-111 and OGLE-TR-113, and candidate planetary transits: OGLE-TR-82, OGLE-TR-86, OGLE-TR-91, OGLE-TR-106, OGLE-TR-109, OGLE-TR-110, OGLE-TR-159, OGLE-TR-167, OGLE-TR-170, OGLE-TR-171. Using difference imaging photometry, we were able to achieve millimagnitude errors in the individual data points. We present the analysis of the data and the light curves, by measuring transit amplitudes and ephemerides, and by calculating geometrical parameters for some of the systems. We observed 9 OGLE objects at the predicted transit moments. Two other transits were shifted in time by a few hours. For another seven objects we expected to observe transits during the VIMOS run, but they were not detected. The stars OGLE-TR-111 and OGLE-TR-113 are probably the only OGLE objects in the observed sample to host planets, with the other objects being very likely eclipsing binaries or multiple systems. In this paper we also report on four new transiting candidates which we have found in the data.Comment: 11 pages, 17 figures, accepted for publication in A&

    Performance Enhancement of Multiuser Time Reversal UWB Communication System

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    UWB communication is a recent research area for indoor propagation channels. Time Reversal (TR) communication in UWB has shown promising results for improving the system performance. In multiuser environment, the system performance is significantly degraded due to the interference among different users. TR reduces the interference caused by multiusers due to its spatial focusing property. The performance of a multiuser TR communication system is further improved if the TR filter is modified. In this paper, multiuser TR in UWB communication is investigated using simple TR filter and a modified TR filter with circular shift operation. The concept of circular shift in TR is analytically studied. Thereafter, the channel impulse responses (CIR) of a typical indoor laboratory environment are measured. The measured CIRs are used to analyze the received signal peak power and signal to interference ratio (SIR) with and without performing the circular shift operation in a multiuser environment

    The asymmetric ABAB matrix model

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    In this letter, it is pointed out that the two matrix model defined by the action S=(1/2)(tr A^2+tr B^2)-(alpha_A/4) tr A^4-(alpha_B/4) tr B^4-(beta/2) tr(AB)^2 can be solved in the large N limit using a generalization of the solution of Kazakov and Zinn-Justin (who considered the symmetric case alpha_A=alpha_B). This model could have useful applications to 3D Lorentzian gravity.Comment: 7 pages, 1 figur

    Categorified trace for module tensor categories over braided tensor categories

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    Given a braided pivotal category C\mathcal C and a pivotal module tensor category M\mathcal M, we define a functor TrC:M→C\mathrm{Tr}_{\mathcal C}:\mathcal M \to \mathcal C, called the associated categorified trace. By a result of Bezrukavnikov, Finkelberg and Ostrik, the functor TrC\mathrm{Tr}_{\mathcal C} comes equipped with natural isomorphisms τx,y:TrC(x⊗y)→TrC(y⊗x)\tau_{x,y}:\mathrm{Tr}_{\mathcal C}(x \otimes y) \to \mathrm{Tr}_{\mathcal C}(y \otimes x), which we call the traciators. This situation lends itself to a diagramatic calculus of `strings on cylinders', where the traciator corresponds to wrapping a string around the back of a cylinder. We show that TrC\mathrm{Tr}_{\mathcal C} in fact has a much richer graphical calculus in which the tubes are allowed to branch and braid. Given algebra objects AA and BB, we prove that TrC(A)\mathrm{Tr}_{\mathcal C}(A) and TrC(A⊗B)\mathrm{Tr}_{\mathcal C}(A \otimes B) are again algebra objects. Moreover, provided certain mild assumptions are satisfied, TrC(A)\mathrm{Tr}_{\mathcal C}(A) and TrC(A⊗B)\mathrm{Tr}_{\mathcal C}(A \otimes B) are semisimple whenever AA and BB are semisimple.Comment: 49 pages, many figure

    Transversal Lattices

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    A flat of a matroid is cyclic if it is a union of circuits; such flats form a lattice under inclusion and, up to isomorphism, all lattices can be obtained this way. A lattice is a Tr-lattice if all matroids whose lattices of cyclic flats are isomorphic to it are transversal. We investigate some sufficient conditions for a lattice to be a Tr-lattice; a corollary is that distributive lattices of dimension at most two are Tr-lattices. We give a necessary condition: each element in a Tr-lattice has at most two covers. We also give constructions that produce new Tr-lattices from known Tr-lattices.Comment: 12 pages; 5 figure

    On spectra and Brown's spectral measures of elements in free products of matrix algebras

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    We compute spectra and Brown measures of some non self-adjoint operators in (M_2(\cc), {1/2}Tr)*(M_2(\cc), {1/2}Tr), the reduced free product von Neumann algebra of M_2(\cc) with M_2(\cc). Examples include ABAB and A+BA+B, where A and B are matrices in (M_2(\cc), {1/2}Tr)*1 and 1*(M_2(\cc), {1/2}Tr), respectively. We prove that AB is an R-diagonal operator (in the sense of Nica and Speicher \cite{N-S1}) if and only if Tr(A)=Tr(B)=0. We show that if X=AB or X=A+B and A,B are not scalar matrices, then the Brown measure of X is not concentrated on a single point. By a theorem of Haagerup and Schultz \cite{H-S1}, we obtain that if X=AB or X=A+B and X≠λ1X\neq \lambda 1, then X has a nontrivial hyperinvariant subspace affiliated with (M_2(\cc), {1/2}Tr)*(M_2(\cc), {1/2}Tr).Comment: final version. to appear on Math. Sca

    A conserved U-rich RNA region implicated in regulation of translation in Plasmodium female gametocytes.

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    Translational repression (TR) plays an important role in post-transcriptional regulation of gene expression and embryonic development in metazoans. TR also regulates the expression of a subset of the cytoplasmic mRNA population during development of fertilized female gametes of the unicellular malaria parasite, Plasmodium spp. which results in the formation of a polar and motile form, the ookinete. We report the conserved and sex-specific regulatory role of either the 3’- or 5’-UTR of a subset of translationally repressed mRNA species as shown by almost complete inhibition of expression of a GFP reporter protein in the female gametocyte. A U-rich, TR-associated element, identified previously in the 3’-UTR of TR-associated transcripts, played an essential role in mediating TR and a similar region could be found in the 5’-UTR shown in this study to be active in TR. The silencing effect of this 5’-UTR was shown to be independent of its position relative to its ORF, as transposition to a location 3’ of the ORF did not affect TR. These results demonstrate for the first time in a unicellular organism that the 5’ or the 3’-UTR of TR-associated transcripts play an important and conserved role in mediating TR in female gametocytes
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