Late-time tails of a Yang-Mills field on Minkowski and Schwarzschild backgrounds

We study the late-time behavior of spherically symmetric solutions of the Yang-Mills equations on Minkowski and Schwarzschild backgrounds. Using nonlinear perturbation theory we show in both cases that solutions having smooth compactly supported initial data posses tails which decay as $t^{-4}$ at timelike infinity. Moreover, for small initial data on Minkowski background we derive the third-order formula for the amplitude of the tail and confirm numerically its accuracy.Comment: 7 pages, 3 figure

On asymptotic stability of the Skyrmion

We study the asymptotic behavior of spherically symmetric solutions in the Skyrme model. We show that the relaxation to the degree-one soliton (called the Skyrmion) has a universal form of a superposition of two effects: exponentially damped oscillations (the quasinormal ringing) and a power law decay (the tail). The quasinormal ringing, which dominates the dynamics for intermediate times, is a linear resonance effect. In contrast, the polynomial tail, which becomes uncovered at late times, is shown to be a \emph{nonlinear} phenomenon.Comment: 4 pages, 4 figures, minor changes to match the PRD versio

Pion light cone wave function in the non-local NJL model

We use the simple instanton motivated NJL-type model to calculate the leading twist pion light cone wave function. The model consists in employing the momentum dependent quark mass in the quark loop entering the definition of the wave function. The result is analytical up to a solution of a certain algebraic equation. Various properties including the kT dependence of the pion wave function are discussed. The resulting kT integrated wave function is not asymptotic and is in agreement with recent analysis of the CLEO data.Comment: 9 pages, 12 figures, formulas (23-25) corrected, typos correcte

Vacuum condensates and the pion wave functions in the nonlocal chiral model

We use the simple instanton motivated Nambu Jona-Lasinio - type model to calculate a twist 3 pseudoscalar pion light cone wave function. Using normalisation condition for this wave function we calculate the quark condensate and also the gluon condensate, which agree with the phenomenological values for these quantities. Since we can compute also the k_T^2 dependence of the light cone wave functions, we calculate k_T^2 moments of the pseudo-scalar and axial-vector wave functions which are related to the mixed vacuum condensates. This allows us to extract the condensates and compare them with existing estimates.Comment: 12 pages, 7 figures; three new paragraphs added: one (in sec. IV) discusses the relation between quark and gluon condensates, the other two (in secs. I and VI) clarify the difference between the normalisation scale Q_0, at which the condensates are evaluated, and the model parameter Lambda; new references added; to be published in Phys. Rev.

Using the present to interpret the past: the role of ethnographic studies in Andean archaeology

Within Andean research it is common to use ethnographic analogies to aid the interpretation of archaeological remains, and ethnographers and archaeologists have developed shared research in technology, material culture and material practice. Although most of this research does not follow the detailed recording methods of spatial patterning envisioned in earlier formulations of ethnoarchaeology, it has had a profound effect on how archaeology in the region has been interpreted. This paper uses examples from the study of pottery production to address earlier debates about the use of ethnographic analogy, discusses the dangers of imposing an idealised or uniform vision of traditional Andean societies onto earlier periods (‘Lo Andino’) but stresses the benefits of combining ethnographic and archaeological research to explore continuities and changes in cultural practice and regional variations

Protein kinase C activity and intracellular distribution in surgically excised human epileptic neocortex

Protein kinase C (PKC) activity assayed by phosphorylation of exogenous histone, was measured in neocortex obtained from 32 patients following surgery for focal epilepsy and from 6 non-epileptic patients. PKC activity was not significantly different in either the particulate or cytosolic fraction from epileptic foci (n = 17) versus samples from non-spiking regions (n = 22) or neocortex from non-epileptic patients (n = 6). From 67% to 70% of total PKC activity was present in the cytosolic fraction. Phosphorylation of endogenous cytosolic substrate proteins was also not significantly different in epileptic foci