20,042 research outputs found
You\u27ll Find Old Dixieland In France
https://digitalcommons.library.umaine.edu/mmb-vp/2810/thumbnail.jp
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
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 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 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
Electric polarizabilities of proton and neutron and the relativistic center-of-mass coordinate
We argue that the relativistic correction to the
center-of-mass vector can lead to the approximate equality of the proton and
neutron electric polarizabilities in the quark model. The explicit form of
depends only on the non-relativistic potential between
quarks. In particular, this correction is the same for the potential generated
by Lorentz-vector and -scalar interactions.Comment: 8 pages, LaTeX, conclusion extende
Jet analysis by Deterministic Annealing
We perform a comparison of two jet clusterization algorithms. The first one
is the standard Durham algorithm and the second one is a global optimization
scheme, Deterministic Annealing, often used in clusterization problems, and
adapted to the problem of jet identification in particle production by high
energy collisions; in particular we study hadronic jets in WW production by
high energy electron positron scattering. Our results are as follows. First, we
find that the two procedures give basically the same output as far as the
particle clusterization is concerned. Second, we find that the increase of CPU
time with the particle multiplicity is much faster for the Durham jet
clustering algorithm in comparison with Deterministic Annealing. Since this
result follows from the higher computational complexity of the Durham scheme,
it should not depend on the particular process studied here and might be
significant for jet physics at LHC as well.Comment: 15 pages, 4 figure
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.
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
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
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
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