HABITABILITY ON KEPLER WORLDS: ARE MOONS RELEVANT?

A new approach for the Kepler worlds: an analogy with systems biology This chapter is based on an extension of previous work and a book review, where additional information has been provided for the interested reader We are considering the question of possible relevance of not only the exoplanets that are currently being searched in the over one hundred thousand stars in our galactic neighborhood with the Kepler mission (the "Kepler worlds"), but also their eventually detectable satellites on the bases of the insights we have gathered in our own solar system. Kepler's planets are too faint for a spectroscopic determination of their atmospheric composition. Kepler is designed to merely determine the frequency of Earth-like planets. The next step is finding close-by Earths and analyzing their atmospheres Astrobiology is a science overlapping the life and physical sciences, but it has surprisingly remained largely disconnected from recent trends in certain branches of both life and physical sciences. We have discussed potential applications to astrobiology of approaches that aim at integration rather than reduction. Aiming at discovering how systems properties emerge has proved valuable in many fields, including engineering, chemistry and biology. In the case of biology, a good definition of systemics-studying systems from a holstic point of view-considers functional genomics in an attempt to characterize the molecular constituents of life: B

First Steps in Eukaryogenesis: Physical phenomena in the origin and evolution of chromosome structure

Our present understanding of the origin and evolution of chromosomes differs considerably from current understanding of the origin and evolution of the cell itself. Chromosome origins have been less prominent in research, as the emphasis has not shifted so far appreciably from the phenomenon of primeval nucleic acid encapsulation to that of the origin of gene organization, expression, and regulation. In this work we discuss some reasons why preliminary steps in this direction are being taken. We have been led to examine properties that have contributed to raise the ancestral prokaryotic programmes to a level where we can appreciate in eukaryotes a clear departure from earlier themes in the evolution of the cell from the last common ancestor. We shift our point of view from the evolution of cell morphology to the point of view of the genes. In particular, we focus attention on possible physical bases for the way transmission of information has evolved in eukaryotes, namely, the inactivation of whole chromosomes. The special case of the inactivation of the X chromosome in mammals is discussed, paying particular attention to the physical process of the spread of X inactivation in monotremes (platypus and echidna). When experimental data is unavailable some theoretical analysis is possible based on the idea that in certain cases collective phenomena in genetics, rather than chemical detail, are better correlates of complex chemical processes

Quantum random walks with history dependence

We introduce a multi-coin discrete quantum random walk where the amplitude for a coin flip depends upon previous tosses. Although the corresponding classical random walk is unbiased, a bias can be introduced into the quantum walk by varying the history dependence. By mixing the biased random walk with an unbiased one, the direction of the bias can be reversed leading to a new quantum version of Parrondo's paradox.Comment: 8 pages, 6 figures, RevTe

Returning to Europa: can traces of surficial life be detected?

There is at present a possibility for returning to Europa with Laplace, a mission to Europa and the Jupiter System for European Space Agency's Cosmic Vision Programme. The question of habitability by the identification of reliable bio-indicators is a major priority. We explain the options for approaching the question of selecting the right instrumentation for measuring the more abundant sulphur isotope, in spite of the fact that <SUP>32</SUP>S is isobaric (same m/z) with <SUP>16</SUP>O<SUB>2</SUB>. Two technologies are available for investigating the possible biogenicity of the surficial sulphur on the icy patches discovered by the Galileo mission. We argue that there is a need to use higher-order statistics in the data that are to be gathered with the instruments chosen for the payload (ion-traps for orbital measurements, or penetrators for surficial measurements). In particular, we argue in favour of data analysis taken from an orbital spacecraft that addresses fluctuations of the data retrieved, rather than the mean. For this purpose, we reconsider the significance of deviations of sulphur abundances relative to normal (meteoritic) values. In the present work, we consider the experimentally testable possibility of biogenically driven isotopic anomalies in the light of statistical data analysis. The fluctuation test that is being proposed in the context of future missions to Europa may well be appropriate to a laboratory experiment with sulphur-reducing bacteria with the corresponding isotopic fractionation