1,860 research outputs found

    Lax Tensors, Killing Tensors and Geometric Duality

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    The solution of the Lax tensor equations in the case LαÎČÎł=−LÎČαγL_{\alpha\beta\gamma}=-L_{\beta\alpha\gamma} was analyzed. The Lax tensors on the dual metrics were investigated. We classified all two dimensional metrics having the symmetric Lax tensor LαÎČÎłL_{\alpha\beta\gamma}. The Lax tensors of the flat space, Rindler system and its dual were found.Comment: 9 pages LATE

    Negative Even Grade mKdV Hierarchy and its Soliton Solutions

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    In this paper we provide an algebraic construction for the negative even mKdV hierarchy which gives rise to time evolutions associated to even graded Lie algebraic structure. We propose a modification of the dressing method, in order to incorporate a non-trivial vacuum configuration and construct a deformed vertex operator for sl^(2)\hat{sl}(2), that enable us to obtain explicit and systematic solutions for the whole negative even grade equations

    The Trail, 1987-02-12

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    https://soundideas.pugetsound.edu/thetrail_all/2446/thumbnail.jp

    On Non-Commutative Integrable Burgers Equations

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    We construct the recursion operators for the non-commutative Burgers equations using their Lax operators. We investigate the existence of any integrable mixed version of left- and right-handed Burgers equations on higher symmetry grounds.Comment: 8 page

    Kolonoskopi sâ€șrasâ€șnda oksijenasyon ve kalp hâ€șzâ€ș de€ifliklikleri ile iliflkili risk faktörleri

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    Background/aims: Although hypoxemia is a relatively common complication of colonoscoy, the possible predictive factors of oxygen desaturation and tachycardia in patients undergoing this procedure are not well known. In this study, the possible predictive factors of severe oxygen desaturation (SaO260yr) age (OR: 6.03; 95% CI, 1.35-26.99), receiving sedation (OR: 11.42; 95% CI, 2.05-63.49), chronic lung disease (OR: 4.54; 95% CI and 1.40-11.68), and obesity (OR: 8.95; 95% CI, 1.17-68.55). The presence of hypertension and anemia, a history of cigarette smoking and duration of the colonoscopy had no significant effect on arterial oxygen desaturation (p>0.05). The pulse rate was raised above 100/min during colonoscopy in 26 of 79 patients (32.9%). Increase in heart rate was found to be related to arterial oxygen desaturation (OR: 13.72; 95% CI, 2.67-70.32), anemia (OR:6.17; 95% CI, 1.15-32.91) and advanced (>60 yr) age (OR: 6.08; 95% CI, 1.62-22.81). Gender, sedation, obesity, hypertension, chronic lung disease and smoking did not affect the heart rate (p>0.05). Two patients had transitional bradyarrythmia, which had no relationship with the parameters studied. There was no incidence of significant hypoxia or change in heart rate which might have caused termination of the procedure. Conclusions: Benign and transient arterial oxygen desaturation and tachycardia may occur during colonoscopy procedure. Sedation, obesity, advanced age and chronic lung disease might contribute to these adverse events

    Dynamics and stability of the Godel universe

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    We use covariant techniques to describe the properties of the Godel universe and then consider its linear response to a variety of perturbations. Against matter aggregations, we find that the stability of the Godel model depends primarily upon the presence of gradients in the centrifugal energy, and secondarily on the equation of state of the fluid. The latter dictates the behaviour of the model when dealing with homogeneous perturbations. The vorticity of the perturbed Godel model is found to evolve as in almost-FRW spacetimes, with some additional directional effects due to shape distortions. We also consider gravitational-wave perturbations by investigating the evolution of the magnetic Weyl component. This tensor obeys a simple plane-wave equation, which argues for the neutral stability of the Godel model against linear gravity-wave distortions. The implications of the background rotation for scalar-field Godel cosmologies are also discussed.Comment: Revised version, to match paper published in Class. Quantum Gra

    On the (Non)-Integrability of KdV Hierarchy with Self-consistent Sources

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    Non-holonomic deformations of integrable equations of the KdV hierarchy are studied by using the expansions over the so-called "squared solutions" (squared eigenfunctions). Such deformations are equivalent to perturbed models with external (self-consistent) sources. In this regard, the KdV6 equation is viewed as a special perturbation of KdV equation. Applying expansions over the symplectic basis of squared eigenfunctions, the integrability properties of the KdV hierarchy with generic self-consistent sources are analyzed. This allows one to formulate a set of conditions on the perturbation terms that preserve the integrability. The perturbation corrections to the scattering data and to the corresponding action-angle variables are studied. The analysis shows that although many nontrivial solutions of KdV equations with generic self-consistent sources can be obtained by the Inverse Scattering Transform (IST), there are solutions that, in principle, can not be obtained via IST. Examples are considered showing the complete integrability of KdV6 with perturbations that preserve the eigenvalues time-independent. In another type of examples the soliton solutions of the perturbed equations are presented where the perturbed eigenvalue depends explicitly on time. Such equations, however in general, are not completely integrable.Comment: 16 pages, no figures, LaTe

    A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE

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    In this small note we are concerned with the solution of Forward-Backward Stochastic Differential Equations (FBSDE) with drivers that grow quadratically in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem is a comparison result that allows comparing componentwise the signs of the control processes of two different qgFBSDE. As a byproduct one obtains conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio

    Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

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    Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 <pT,assoc<pT,trig< < p_{\rm{T}, assoc} < p_{\rm{T}, trig} < 5.0 GeV/cc is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range ∣η∣<0.9|\eta|<0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

    Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

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    Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range ∣η∣<0.8|\eta| < 0.8 are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286
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