3,857 research outputs found
Non-Standard Time Reversal for Particle Multiplets and the Spin-Flavor Structure of Hadrons
We show that a system of quarks interacting with chiral fields provides a
physical representation of a ``non-standard'' time reversal for particle
multiplets proposed by Weinberg. As an application, we argue that, if the
internal structure of hadrons is described by a chiral lagrangian, the
so-called time-reversal-odd quark distribution functions might not be forbidden
by time-reversal invariance.Comment: 2 pages, proceedings of "The Spin Structure of the Proton", ECT -
Trento, July 2001. Eds. S Bass, A De Roeck and A Deshpand
Dynamics of Phase Transitions in Asymmetric Nuclear Matter
We present several possibilities offered by the reaction dynamics of
dissipative heavy ion collisions to study in detail the symmetry term of the
nuclear equation of state, . In particular we discuss isospin effects on
the nuclear liquid-gas phase transition, {\it Isospin Distillation}, and on
collective flows. We stress the importance of a microscopic relativistic
structure of the effective interaction in the isovector channel. The
possibility of an {\it early} transition to deconfined matter in high isospin
density regions is also suggested. We finally select {\it Eleven} observables,
in different beam energy regions, that appear rather sensitive to the isovector
part of the nuclear , in particular in more exclusive experiments.Comment: 8 pages, 7 figures, ISPUN02 Conference, Halong-Vietnam, Nov.20-25
2002, to appear in Nucl.Phys.A. Elsevier Proceedings Styl
The impact of significant input of fine sediment on benthic fauna at tributary junctions: a case study of the Bermejo-Paraguay River confluence, Argentina
This study examines the morphological features, suspended sediment inputs and hydraulic conditions within a large river in association with ecological patterns before and after a tributary confluence. In order to examine these effects, the macroinvertebrate distributions from three reaches of the Paraguay and Bermejo Rivers (Paraguay-Argentina) are investigated. The Bermejo River is a tributary that supplies significant quantities of fine sediment to the Paraguay River, primarily in suspension. Two reaches were examined on the Paraguay River, upstream and downstream of the Bermejo River junction, with the third study reach located on the Bermejo River, upstream of the confluence with the Paraguay River. The results provide clear evidence that a significantly increased loading of fine sediment at a river confluence has effects on the distribution and potential movement of benthic invertebrates in the lotic environment by representing physical barriers at affected sites. These effects may be important at both local and regional scales, and such increases in suspended sediment (especially associated with anthropogenic change) may thus pose a major threat to ecosystem integrity that has been historically underestimated
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