46,138 research outputs found

    Manin-Olshansky triples for Lie superalgebras

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    Following V. Drinfeld and G. Olshansky, we construct Manin triples (\fg, \fa, \fa^*) such that \fg is different from Drinfeld's doubles of \fa for several series of Lie superalgebras \fa which have no even invariant bilinear form (periplectic, Poisson and contact) and for a remarkable exception. Straightforward superization of suitable Etingof--Kazhdan's results guarantee then the uniqueness of qq-quantization of our Lie bialgebras. Our examples give solutions to the quantum Yang-Baxter equation in the cases when the classical YB equation has no solutions. To find explicit solutions is a separate (open) problem. It is also an open problem to list (\`a la Belavin-Drinfeld) all solutions of the {\it classical} YB equation for the Poisson superalgebras \fpo(0|2n) and the exceptional Lie superalgebra \fk(1|6) which has a Killing-like supersymmetric bilinear form but no Cartan matrix

    Meeting update: faecal microbiota transplantation––bench, bedside, courtroom?

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    A group of stakeholders met, under the aegis of the British Society of Gastroenterology, to discuss the current landscape of faecal microbiota transplant- ation (FMT) within the UK and beyond. The meeting covered a wide range of topics, ranging from the practical aspects of establishing an FMT service and regu- latory issues relating to its delivery, to research implications and likely future directions

    Overall properties of the Gaia DR1 reference frame

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    We compare quasar positions of the auxiliary quasar solution with ICRF2 sources using different samples and evaluate the influence on the {\it Gaia} DR1 reference frame owing to the Galactic aberration effect over the J2000.0-J20015.0 period. Then we estimate the global rotation between TGAS with {\it Tycho}-2 proper motion systems to investigate the property of the {\it Gaia} DR1 reference frame. Finally, the Galactic kinematics analysis using the K-M giant proper motions is performed to understand the property of {\it Gaia} DR1 reference frame. The positional comparison between the auxiliary quasar solution and ICRF2 shows negligible orientation and validates the declination bias of \sim0.1-0.1\mas~in {\it Gaia} quasar positions with respect to ICRF2. Galactic aberration effect is thought to cause an offset \sim0.010.01\mas~of the ZZ axis direction of {\it Gaia} DR1 reference frame. The global rotation between TGAS and {\it Tycho}-2 proper motion systems, obtained by different samples, shows a much smaller value than the claimed value 0.240.24\masyr. For the Galactic kinematics analysis of the TGAS K-M giants, we find possible non-zero Galactic rotation components beyond the classical Oort constants: the rigid part ωYG=0.38±0.15\omega_{Y_G} = -0.38 \pm 0.15\masyr~and the differential part ωYG=0.29±0.19\omega^\prime_{Y_G} = -0.29 \pm 0.19\masyr~around the YGY_G axis of Galactic coordinates, which indicates possible residual rotation in {\it Gaia} DR1 reference frame or problems in the current Galactic kinematical model.Comment: 6 pages, 1 figure. Accepted for publication in A&

    Three realizations of quantum affine algebra Uq(A2(2))U_q(A_2^{(2)})

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    In this article we establish explicit isomorphisms between three realizations of quantum twisted affine algebra Uq(A2(2))U_q(A_2^{(2)}): the Drinfeld ("current") realization, the Chevalley realization and the so-called RLLRLL realization, investigated by Faddeev, Reshetikhin and Takhtajan.Comment: 15 page

    The absolute radiometric calibration of the advanced very high resolution radiometer

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    The measurement conditions are described for an intensive field campaign at White Sands Missile Range for the calibration of the AVHRRs on NOAA-9, NOAA-10 and NOAA-11, LANDSAT-4 TM and SPOT. Three different methods for calibration of AVHRRs by reference to a ground surface site are reported, and results from these methods are compared. Significant degradations in NOAA-9 and NOAA-10 AVHRR responsivities occurred since prelaunch calibrations were completed. As of February 1988, degradations in NOAA-9 AVHRR responsivities were on the order of 37 percent in channel and 41 percent in channel 2, and for the NOAA-10 AVHRR these degradations were 42 and 59 percent in channels 1 and 2, respectively

    Hot Spots on the Fermi Surface of Bi2212: Stripes versus Superstructure

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    In a recent paper Saini et al. have reported evidence for a pseudogap around (pi,0) at room temperature in the optimally doped superconductor Bi2212. This result is in contradiction with previous ARPES measurements. Furthermore they observed at certain points on the Fermi surface hot spots of high spectral intensity which they relate to the existence of stripes in the CuO planes. They also claim to have identified a new electronic band along Gamma-M1 whose one dimensional character provides further evidence for stripes. We demonstrate in this Comment that all the measured features can be simply understood by correctly considering the superstructure (umklapp) and shadow bands which occur in Bi2212.Comment: 1 page, revtex, 1 encapsulated postscript figure (color

    Quantum logic for control and manipulation of molecular ions using a frequency comb

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    Due to their rich level structure, molecules are well-suited for probing time variation of fundamental constants, precisely measuring parity violation and time-reversal non-invariance effects, studying quantum mechanical aspects of chemical reactions, and implementing scalable quantum information processing architectures. Molecular ions are particularly attractive for these applications due to their long storage times and the near-perfect isolation from environment that result in long coherence times required to achieve high measurement precision and reduce systematic errors. However, the control of molecular quantum states remains a challenge. Based on quantum logic techniques, we propose a scheme for preparation, manipulation, and detection of quantum states of single molecular ions. The scheme relies on coherent coupling between internal and motional degrees of freedom of the molecular ion via a frequency comb laser field, while detection and cooling of the motion of ions is done via a co-trapped atomic ion.Comment: 5 pages, 3 figure

    Chaotic to ordered state transition of cathode-sheath instabilities in DC glow discharge plasmas

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    Transition from chaotic to ordered state has been observed during the initial stage of a discharge in a cylindrical dc glow discharge plasma. Initially it shows a chaotic behavior but increasing the discharge voltage changes the characteristics of the discharge glow and shows a period substraction of order 7 period \to 5 period \to3 period \to1 period i.e. the system goes to single mode through odd cycle subtraction. On further increasing the discharge voltage, the system goes through period doubling, like 1 period \to 2 period \to 4 period. On further increasing the voltage, the system goes to stable state without having any oscillations.Comment: chathode-sheath, instabilities, chaos, period-subtraction, bifurcation, dc-discharg
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