Unexpected High Brightness Temperature 140 PC from the Core in the Jet of 3C 120

We present 1.7, 5, 15, 22 and 43 GHz polarimetric multi-epoch VLBA observations of the radio galaxy 3C 120. The higher frequency observations reveal a new component, not visible before April 2007, located 80 mas from the core (which corresponds to a deprojected distance of 140 pc), with a brightness temperature about 600 times higher than expected at such distances. This component (hereafter C80) is observed to remain stationary and to undergo small changes in its brightness temperature during more than two years of observations. A helical shocked jet model - and perhaps some flow acceleration - may explain the unusually high Tb of C80, but it seems unlikely that this corresponds to the usual shock that emerges from the core and travels downstream to the location of C80. It appears that some other intrinsic process in the jet, capable of providing a local burst in particle and/or magnetic field energy, may be responsible for the enhanced brightness temperature observed in C80, its sudden appearance in April 2007, and apparent stationarity.Comment: 5 pages, 5 figures Accepted to be published in ApJ Letter

Asymptotic behaviour of zeros of exceptional Jacobi and Laguerre polynomials

The location and asymptotic behaviour for large n of the zeros of exceptional Jacobi and Laguerre polynomials are discussed. The zeros of exceptional polynomials fall into two classes: the regular zeros, which lie in the interval of orthogonality and the exceptional zeros, which lie outside that interval. We show that the regular zeros have two interlacing properties: one is the natural interlacing between consecutive polynomials as a consequence of their Sturm-Liouville character, while the other one shows interlacing between the zeros of exceptional and classical polynomials. A generalization of the classical Heine-Mehler formula is provided for the exceptional polynomials, which allows to derive the asymptotic behaviour of their regular zeros. We also describe the location and the asymptotic behaviour of the exceptional zeros, which converge for large n to fixed values.Comment: 19 pages, 3 figures, typed in AMS-LaTe

Two novel classes of solvable many-body problems of goldfish type with constraints

Two novel classes of many-body models with nonlinear interactions "of goldfish type" are introduced. They are solvable provided the initial data satisfy a single constraint (in one case; in the other, two constraints): i. e., for such initial data the solution of their initial-value problem can be achieved via algebraic operations, such as finding the eigenvalues of given matrices or equivalently the zeros of known polynomials. Entirely isochronous versions of some of these models are also exhibited: i.e., versions of these models whose nonsingular solutions are all completely periodic with the same period.Comment: 30 pages, 2 figure

On Integrable Quantum Group Invariant Antiferromagnets

A new open spin chain hamiltonian is introduced. It is both integrable (Sklyanin`s type $K$ matrices are used to achieve this) and invariant under ${\cal U}_{\epsilon}(sl(2))$ transformations in nilpotent irreps for $\epsilon^3=1$. Some considerations on the centralizer of nilpotent representations and its representation theory are also presented.Comment: IFF-5/92, 13 pages, LaTex file, 8 figures available from author

Ethical implications of onto-epistemological pluralism in relation to entropy,

From the epistemological posture that we present in this work we sustain the following thesis:-That as subjects we constitute the world we live in through one of the possible conceptual frameworks.-Our cognitive and social practices construct the world in a certain manner, which makes us responsible for the way this world is constituted