Claiming for a demologic approach to demographic change

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Two theoretical interpretations of the dissonance between fertility intentions and behaviour

In the paper we outline two possible theoretical interpretations for the inconsistency often observed between fertility intentions and fertility behaviour. We draw on socio-psychological models of human behaviour which emphasise the role of normative-affective factors on decision-making processes. The first interpretation is based on the observation that family and fertility choices are gradually shifting from a zone where behaviour is normative regulated to a zone of normative indifference, where mere rational decision-making based on cost-benefit considerations is at work. The dissonance between fertility choices and declared intentions depends on the fact that the former are based on rational considerations, while the latter are still constrained by a normative familistic philosophy. The second interpretation assumes the existence of an interposing mechanism in the sequence expectations-behaviour. These mechanisms, as anxiety and avoidance dispositions, filter the passage from individual value orientations in the affective sphere to their actual behaviour. We base our argument on two sets of information. First, we use a survey which allows us to construct empirical indicators of psychological dispositions connected to expectations related to family and fertility behaviours (Abacus 1996, Italy). Second, we analyse 54 non-structured interviews conducted in Northern Italy, which give a detailed picture of the hypothesised mechanisms and suggest new directions for research.

Reconstructing the thermal Green functions at real times from those at imaginary times

By exploiting the analyticity and boundary value properties of the thermal Green functions that result from the KMS condition in both time and energy complex variables, we treat the general (non-perturbative) problem of recovering the thermal functions at real times from the corresponding functions at imaginary times, introduced as primary objects in the Matsubara formalism. The key property on which we rely is the fact that the Fourier transforms of the retarded and advanced functions in the energy variable have to be the `unique Carlsonian analytic interpolations' of the Fourier coefficients of the imaginary-time correlator, the latter being taken at the discrete Matsubara imaginary energies, respectively in the upper and lower half-planes. Starting from the Fourier coefficients regarded as `data set', we then develop a method based on the Pollaczek polynomials for constructing explicitly their analytic interpolations.Comment: 23 pages, 2 figure

Dynamical crystal creation with polar molecules or Rydberg atoms in optical lattices

We investigate the dynamical formation of crystalline states with systems of polar molecules or Rydberg atoms loaded into a deep optical lattice. External fields in these systems can be used to couple the atoms or molecules between two internal states: one that is weakly interacting and one that exhibits a strong dipole-dipole interaction. By appropriate time variation of the external fields we show that it is possible to produce crystalline states of the strongly interacting states with high filling fractions chosen via the parameters of the coupling.We study the coherent dynamics of this process in one dimension (1D) using a modified form of the time-evolving block decimation (TEBD) algorithm, and obtain crystalline states for system sizes and parameters corresponding to realistic experimental configurations. For polar molecules these crystalline states will be long-lived, assisting in a characterization of the state via the measurement of correlation functions. We also show that as the coupling strength increases in the model, the crystalline order is broken. This is characterized in 1D by a change in density-density correlation functions, which decay to a constant in the crystalline regime, but show different regions of exponential and algebraic decay for larger coupling strengths

Cycles post-transitionnels et modèles proie-prédateur

Cet article examine la cohérence logique des modèles mathématiques utilisés dans l’analyse des fluctuations de la fécondité depuis la fin de la « transition démographique ». Deux grandes familles de modèles sont distinguées : ceux liés à ce qu’on peut appeler la « cinématique démographique », et parmi lesquels le modèle d’Easterlin prend une place importante; et ceux liés à la « dynamique » du système de reproduction, parmi lesquels émerge le modèle proie-prédateur de Volterra, dont les possibilités d’opérationalisation font l’objet d’une réflexion approfondie.This paper investigates the logical consistency of the mathematical models used in the analysis of fertility fluctuations since the end of demographic transition. Two main families of models may be distinguished: those related to demographic "cinematics", including the well known Easterlin model; and those related to the "dynamics" of the reproduction system, among which Volterra's prey-predator model takes a particular place. The possibilities of operationalizing the latter model are also discussed.Este artículo examina la coherencia lógica de los modelos matemáticos utilizados en el análisis de las fluctuaciones de la fecundidad a partir de la "transición demográfica". Dos grandes familias de modelos están distinguidas: los que están relacionados a lo que podemos llamar la cinématica demográfica y dentro de los cuales el modelo de Easterlin toma un lugar importante, y los que están relacionados a la dinámica del sistema de reproducción, dentro de los cuales surge el modelo presa-predator de Volterra cuyas posibilidades de puesta en marcha hacen el objeto de una profunda reflexión

The anthropological embedment of fertility change in Southern Europe

The year after the 1854 cholera epidemic Frederic Le Play published a century household model map that used a typology of the organizational models of the household based on two modern variants of the patriarchal ideal type. However a considerable overlap between Le Plays household model map and the regional total fertility rate map of central-southern Europe in the 1980s have been noted. This paper examines the overall structure of relationships involved in Le Plays typology and observes that both the stem-family and the unstable family area in southern Europe are marked by small close-knit networks of strong ties with kinship predominance. Vice versa the social support hinges upon a network of kin in the stem-family area upon an alliance among different kindred units in the unstable Mediterranean area. All this leads to formulating a hypothesis of a tripartite model for western Europe relationship models. Moreover several rough contributions to an etiological model are cited in which the existing diversity in regional fertility behavior is explained by basic persistent anthropological structures