Perceived motor ability and selection, optimization, and compensation: Effects of age and institutionalization

The authors examined the mediation effect of the perceived motor ability (PMA) on the direct “effects” of age (third vs. fourth age) and residential status (institutionalized vs. communitarians) on selection, optimization, and compensation (SOC) strategies. With a non-probabilistic sample of 107 elders (Mdn = 80 years) from urban areas, and controlled for cognitive impairment and depression, the authors analysed the structural component of the path model with latent constructs that represents those relationships. This was made only after the structural validity of the constructs had been assured. Constructs were operationalized through the PMA questionnaire and a 16-item version of the SOC questionnaire. Only age had direct effects on the constructs: lower PMA and lower SOC of the elders in the fourth age. Authors also verified that the PMA mediation effect was partial

Nonperturbative Aspects of the two-dimensional Massive Gauged Thirring Model

In this paper we present a study based on the use of functional techniques on the issue of insertions of massive fermionic fields in the two-dimensional massless Gauged Thirring Model. As it will be shown, the fermionic mass contributes to the Green's functions in a surprisingly simple way, leaving therefore the original nonperturbative nature of the massless results still intact in the massive theory. Also, by means of complementarity, we present a second discussion of the massive model, now at its bosonic representation.Comment: 18 pages, to appear at Int. J. Mod. Phys.

Variable cosmological term Λ(t)\Lambda(t)

We present the case of time-varying cosmological term $\Lambda(t)$. The main idea arises by proposing that as in the cosmological constant case, the scalar potential is identified as $V(\phi)=2\Lambda$, with $\Lambda$ a constant, this identification should be kept even when the cosmological term has a temporal dependence, i.e., $V(\phi(t))=2\Lambda(t)$. We Use the Lagrangian formalism for a scalar field $\phi$ with standard kinetic energy and arbitrary potential $V(\phi)$ and apply this model to the Friedmann-Robertson-Walker (FRW)cosmology. Exact solutions of the field equations are obtained by a special ansatz to solve the Einstein-Klein-Gordon equation and a particular potential for the scalar field and barotropic perfect fluid. We present the evolution on this cosmological term with different scenarios.Comment: Latex source, 12 pages, 3 figures, accepted in Astrophysics Space Scienc