Decisions with endogenous frames

We develop a model of decision-making with endogenous frames and contrast the normative implications of our model to those of choice theoretic models in which observed choices are determined by exogenous frames or ancillary conditions. We argue that, frames, though they may be taken as given by the decision-maker at the point when choices are made, matter for both welfare and policy purposes

Characterizing behavioral decisions with choice data

This paper provides an axiomatic characterization of choices in a setting where a decision-maker may not fully internalize all the consequences of her choices on herself. Such a departure from rationality, it turns out, is common across a variety of positive behavioral models and admits the standard rational choice model as a special case. We show that choice data satisfying (a) Senís axioms if and fully characterize behavioral decisions, and (b) Senís axiom if and if fully characterize standard decision-making. In addition, we show that (a) it is possible to identify a minimal and a maximal set of psychological states using choice data alone, and (b) under specific choice scenarios, "revealed mistakes" can be inferred directly from choice data

Behavioural decisions & policy

We study the public policy implications of a model in which agents do not fully internalize all the conscequences of their actions. Such a model uni…es seemingly disconected models with behavioral agents. We evaluate the scope of paternalistic and libertarian-parternalistic policies in the light of our model, and propose an alternative type of approach, called soft-libertarian, which guides the decision makers in the internalization of all the conscequences of their actions. Psychotherapy is one example of a soft-libertarian policy. Moreover, we show that in our behavioral framework, policies that increase the set of opportunities or provide more information to the agent may not longer be individual welfare improving

On the Stability of Circular Orbits of Particles Moving around Black Holes Surrounded by Axially Symmetric Structures

The Rayleigh criterion is used to study the stability of circular orbits of particles moving around static black holes surrounded by different axially symmetric structures with reflection symmetry, like disks, rings and halos. We consider three models of disks one of infinite extension and two finite, and one model of rings. The halos are represented by external quadrupole moments (either oblate or prolate). Internal quadrupole perturbation (oblate and prolate) are also considered. For this class of disks the counter-rotation hypothesis implies that the stability of the disks is equivalent to the stability of test particles. The stability of Newtonian systems is also considered and compared with the equivalent relativistic situation. We find that the general relativistic dynamics favors the formation of rings.Comment: RevTex, 9 pages, 14 eps figs. Phys. Rev. D to appea

Riemann-Christoffel flows

A geometric flow based in the Riemann-Christoffel curvature tensor that in two dimensions has some common features with the usual Ricci flow is presented. For $n$ dimensional spaces this new flow takes into account all the components of the intrinsic curvature. For four dimensional Lorentzian manifolds it is found that the solutions of the Einstein equations associated to a "detonant" sphere of matter, as well, as a Friedman-Roberson-Walker cosmological model are examples of Riemann-Christoffel flows. Possible generalizations are mentioned.Comment: 3 pages, RevTex,small changes, Int. J. Theor. Phys. (in press

Spacetime Defects: Torsion Loops

Spacetimes with everywhere vanishing curvature tensor, but with torsion different from zero only on world sheets that represent closed loops in ordinary space are presented, also defects along open curves with end points at infinity are studied. The case of defects along timelike loops is also considered and the geodesics in these spaces are briefly discussed.Comment: 8 pages, LATE

Poverty and aspirations failure

We develop a model of internal constraints to show that a greater degree of initial disadvantage results in a higher likelihood of low aspirations and low achievement. Our model and results are supported by evidence from anthropology, sociology and social psychology. Our analysis suggests that internal constraints are a key ingredient in perpetuating poverty traps. We show that a poor person will choose to restrict her cognitive window (the set of other individuals who are her role models) and study the conditions under which a role model could alter her aspirations and achievement. We show how enodgenously chosen cognitive windows interact with the inital distribution of status to determine whether or not a society is connected, and hence the transmission of aspirations across individuals in that society. Our work provides a normative justification for programs that aim at empowering disadvantaged individuals by directly shocking their aspirations

Poverty and Aspirations Failure

This paper models the role of internal constraints in causing aspirations failure at the individual level. It shows how initial disadvantage increases the likelihood of binding internal constraints and hence aspirations failure, thus suggesting a new behavioral explanation for poverty traps. In examining common approaches to relaxing such internal constraints, it describe how an individual’s endogenous choice of a "cognitive window" (i.e. a set of relevant "similar" individuals)can limit the e¤ectiveness of role models. Further, we consider how the distribution of initial status determines the degree of connectedness in a society and hence the individual perception of these constraints. Our work provides a normative justification for programs that aim to empower participants through a direct positive shock to their aspirations.

Thin-disk models in an Integrable Weyl-Dirac theory

We construct a class of static, axially symmetric solutions representing razor-thin disks of matter in an Integrable Weyl-Dirac theory proposed in Found. Phys. 29, 1303 (1999). The main differences between these solutions and the corresponding general relativistic one are analyzed, focusing on the behavior of physical observables (rotation curves of test particles, density and pressure profiles). We consider the case in which test particles move on Weyl geodesics. The same rotation curve can be obtained from many different solutions of the Weyl-Dirac theory, although some of these solutions present strong qualitative differences with respect to the usual general relativistic model (such as the appearance a ring-like density profile). In particular, for typical galactic parameters all rotation curves of the Weyl-Dirac model present Keplerian fall-off. As a consequence, we conclude that a more thorough analysis of the problem requires the determination of the gauge function $\beta$ on galactic scales, as well as restrictions on the test-particle behavior under the action of the additional fields introduced by this theory.Comment: 18 pages, 3 figures; accepted in General Relativity and Gravitatio