Time evolution of the Partridge-Barton Model

The time evolution of the Partridge-Barton model in the presence of the pleiotropic constraint and deleterious somatic mutations is exactly solved for arbitrary fecundity in the context of a matricial formalism. Analytical expressions for the time dependence of the mean survival probabilities are derived. Using the fact that the asymptotic behavior for large time $t$ is controlled by the largest matrix eigenvalue, we obtain the steady state values for the mean survival probabilities and the Malthusian growth exponent. The mean age of the population exhibits a $t^{-1}$ power law decayment. Some Monte Carlo simulations were also performed and they corroborated our theoretical results.Comment: 10 pages, Latex, 1 postscript figure, published in Phys. Rev. E 61, 5664 (2000

A Bit-String Model for Biological Aging

We present a simple model for biological aging. We studied it through computer simulations and we have found this model to reflect some features of real populations.Comment: LaTeX file, 4 PS figures include

Fertility and territorial well-being in Italy .How is fertility related to social, economic and environmental quality?

We analyzed the association between fertility rates and well-being measured at the regional level. How does the gap between intended and realized fertility relate with other well-being indicators measured at the aggregate level in terms of social, economic, environmental conditions? We try to answer this question with reference to Italy in the period 2010-2017 through the analysis of the association between the regional fertility rates and a rich system of regional indicators measuring various aspects of the social, economic and environmental quality (Equitable and Sustainable Well-being or Benessere Equo e Sostenibile - BES, in Italian). The results show that in regions best performing in terms of economic conditions and of the functioning of public services as well as in terms of the quality of the educational system and of the environment, fertility is higher than the national average

Fertility and well-being in the italian regions

We analyse the association between fertility rates and well-being in the Italian regions in the period 2012-2017. Well-being is measured by the indicators of Equitable and Sustainable Well-being (BES), collected by ISTAT since 2013 with the aim of evaluating the economic, social and environmental development of the society through measurement of citizens’ life quality. We expect that the regions performing better in terms of well-being conditions are also those with the highest levels of fertility. Both graphical and panel data regression analyses support our main hypothesis, but also reveal that in different clusters of regions the intensity and direction of the relationship significantly change. Our results also stress the need of taking the different domains of well-being into account while explaining reproductive behaviour of resident population at territorial level

Comments on Anomaly Cancellations by Pole Subtractions and Ghost Instabilities with Gravity

We investigate some aspects of anomaly cancellation realized by the subtraction of an anomaly pole, stressing on some of its properties in superspace. In a local formulation these subtractions can be described in terms of a physical scalar, an axion and related ghosts. They appear to be necessary for the unitarization of the theory in the ultraviolet, but they may generate an infrared instability of the corresponding effective action, signalled by ghost condensation. In particular the subtraction of the superanomaly multiplet by a pole in superspace is of dubious significance, due to the different nature of the chiral and conformal anomalies. In turn, this may set more stringent constraints on the coupling of supersymmetric theories to gravity.Comment: 18 pages. Revised version. To appear in "Classical and Quantum Gravity

Phenomenological description of the states 0+0^+ and 2+2^+ in some even-even nuclei

A sixth-order quadrupole boson Hamiltonian is used to describe the states $0^+$ and $2^+$ identified in several nuclei by various types of experiments. Two alternative descriptions of energy levels are proposed. One corresponds to a semi-classical approach of the model Hamiltonian while the other one provides the exact eigenvalues. Both procedures yield close formulas for energies. The first procedure involves four parameters, while the second involves a compact formula with five parameters. In each case the parameters are fixed by a least-square fit procedure. Applications are performed for eight even-even nuclei. Both methods yield results which are in a surprisingly good agreement with the experimental data. We give also our predicted reduced transition probabilities within the two approaches, although the corresponding experimental data are not yet available.Comment: 27pages, 18 figure

The quadrupole collective model from a Cartan-Weyl perspective

The matrix elements of the quadrupole variables and canonic conjugate momenta, emerging from collective nuclear models are calculated within a $SU(1,1)\times O(5)$ basis. Using a harmonic oscillator implementation of the SU(1,1) degree of freedom, it can be shown that the matrix elements of the quadrupole phonon creation and annihilation operators can be calculated in a pure algebraic way, making use of an intermediate state method.Comment: Special issue of journal of physics for the QTS5 conferenc

The Heumann-Hotzel model for aging revisited

Since its proposition in 1995, the Heumann-Hotzel model has remained as an obscure model of biological aging. The main arguments used against it were its apparent inability to describe populations with many age intervals and its failure to prevent a population extinction when only deleterious mutations are present. We find that with a simple and minor change in the model these difficulties can be surmounted. Our numerical simulations show a plethora of interesting features: the catastrophic senescence, the Gompertz law and that postponing the reproduction increases the survival probability, as has already been experimentally confirmed for the Drosophila fly.Comment: 11 pages, 5 figures, to be published in Phys. Rev.

Observation and theoretical description of the pure Fano-effect in the valence-band photo-emission of ferromagnets

The pure Fano-effect in angle-integrated valence-band photo-emission of ferromagnets has been observed for the first time. A contribution of the intrinsic spin polarization to the spin polarization of the photo-electrons has been avoided by an appropriate choice of the experimental parameters. The theoretical description of the resulting spectra reveals a complete analogy to the Fano-effect observed before for paramagnetic transition metals. While the theoretical photo-current and spin difference spectra are found in good quantitative agreement with experiment in the case of Fe and Co only a qualitative agreement could be achieved in the case of Ni by calculations on the basis of plain local spin density approximation (LSDA). Agreement with experimental data could be improved in this case in a very substantial way by a treatment of correlation effects on the basis of dynamical mean field theory (DMFT).Comment: 11 pages, 3 figures accepted by PR