79 research outputs found
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
History of ESL Pronunciation Teaching
This chapter tells the story of over 150 years in the teaching of English as a second language (ESL) pronunciation. An analysis of historical resources may reveal a reliable history of pronunciation teaching. A consistent theme within the historical record is that prior to the second half of the nineteenth century pronunciation received little attention in L2 classrooms. Beginning in the 1850s and continuing for the next 30 years, early innovators such as Berlitz, Gouin, Marcel, and Predergast were rejecting and transitioning away from classical approaches. A change that resulted in pronunciation teaching\u27s considerably more consequential second wave was the formation in Paris during the period 1886-1889 of the International Phonetic Association. The 1950s-1970s coincide with a slow rise of attention to innovations in how to teach pronunciation. If we may speculate on the future of ESL pronunciation teaching, there is every reason to feel optimistic
A search for extraterrestrial eukaryotes: Physical and biochemical aspects of exobiology
- …