290 research outputs found
Preservation of information in a prebiotic package model
The coexistence between different informational molecules has been the
preferred mode to circumvent the limitation posed by imperfect replication on
the amount of information stored by each of these molecules. Here we reexamine
a classic package model in which distinct information carriers or templates are
forced to coexist within vesicles, which in turn can proliferate freely through
binary division. The combined dynamics of vesicles and templates is described
by a multitype branching process which allows us to write equations for the
average number of the different types of vesicles as well as for their
extinction probabilities. The threshold phenomenon associated to the extinction
of the vesicle population is studied quantitatively using finite-size scaling
techniques. We conclude that the resultant coexistence is too frail in the
presence of parasites and so confinement of templates in vesicles without an
explicit mechanism of cooperation does not resolve the information crisis of
prebiotic evolution.Comment: 9 pages, 8 figures, accepted version, to be published in PR
Quantum dynamics in canonical and micro-canonical ensembles. Part I. Anderson localization of electrons
The new numerical approach for consideration of quantum dynamics and
calculations of the average values of quantum operators and time correlation
functions in the Wigner representation of quantum statistical mechanics has
been developed. The time correlation functions have been presented in the form
of the integral of the Weyl's symbol of considered operators and the Fourier
transform of the product of matrix elements of the dynamic propagators. For the
last function the integral Wigner- Liouville's type equation has been derived.
The numerical procedure for solving this equation combining both molecular
dynamics and Monte Carlo methods has been developed. For electrons in
disordered systems of scatterers the numerical results have been obtained for
series of the average values of the quantum operators including position and
momentum dispersions, average energy, energy distribution function as well as
for the frequency dependencies of tensor of electron conductivity and
permittivity according to quantum Kubo formula. Zero or very small value of
static conductivity have been considered as the manifestation of Anderson
localization of electrons in 1D case. Independent evidence of Anderson
localization comes from the behaviour of the calculated time dependence of
position dispersion.Comment: 8 pages, 10 figure
Creation and Reproduction of Model Cells with Semipermeable Membrane
A high activity of reactions can be confined in a model cell with a
semipermeable membrane in the Schl\"ogl model. It is interpreted as a model of
primitive metabolism in a cell. We study two generalized models to understand
the creation of primitive cell systems conceptually from the view point of the
nonlinear-nonequilibrium physics. In the first model, a single-cell system with
a highly active state confined by a semipermeable membrane is spontaneously
created from an inactive homogeneous state by a stochastic jump process. In the
second model, many cell structures are reproduced from a single cell, and a
multicellular system is created.Comment: 11 pages, 7 figure
НЕКОТОРЫЕ АСПЕКТЫ РЕЛИГИОЗНОЙ ЖИЗНИ МОСКОВСКИХ ТАТАР (ПО МАТЕРИАЛАМ ЭТНОСОЦИОЛОГИЧЕСКОГО ИССЛЕДОВАНИЯ 2014 ГОДА)
In 2014, the Marjani Institute of History at the Tatarstan Academy of Sciences launched a large-scale research project «The Tatars in the regions of the Russian Federation; religious renaissance and issues of identity. An ethno-sociological investigation into the current situation.» An important part of the research as a whole involved an analysis of the ethno-religious life of Tatars living in Moscow. The majority of those interviewed noted the fundamental signifi cance of Islam for the Tatars, along with a very closely intertwined relationship between Muslim religion and Tatar ethnic identity. The widely held notion of disrupted continuity in transmission of religious knowledge within the Moscow Tatar family is confi rmed. The middle-aged generation has ‘fallen out’ of the religious chain, having been most subject to Soviet ideological indoctrination. As such, religious activity is typically limited to the elderly and young people.Первые результаты исследования «Татары в регионах РФ: религиозное возрождение и проблемы идентичности» выявили особенности этнорелигиозной жизни московских татар. Для большей части респондентов ислам имеет базовое значение, отождествляются мусульманская религиозная и татарская этническая идентичности. Подтверждено мнение о нарушении преемственности в передаче религиозных знаний в структуре современной семьи. Из религиозной цепочки «выпадает» среднее поколение, активное проявление религиозности характерно для пожилых людей, либо для молодежи
Should the teaching of biological evolution include the origin of life?
The development of mainstream research on the origin of life as an outcome of Darwinian evolution is discussed. It is argued that prebiotic evolution and the origin of life should not be excluded from the syllabus and should be part of classes on biological evolution, and that the transition from non-living to living matter is best understood when seen as part of evolutionary biology. The wide acceptance of evolutionary approaches to the study of the emergence of life in European and Latin American countries is discussed
Landau Level Crossings and Extended-State Mapping in Magnetic Two-dimensional Electron Gases
We present longitudinal and Hall magneto-resistance measurements of a
``magnetic'' two-dimensional electron gas (2DEG) formed in modulation-doped
ZnCdMnSe quantum wells. The electron spin splitting is
temperature and magnetic field dependent, resulting in striking features as
Landau levels of opposite spin cross near the Fermi level. Magnetization
measurements on the same sample probe the total density of states and Fermi
energy, allowing us to fit the transport data using a model involving extended
states centered at each Landau level and two-channel conduction for spin-up and
spin-down electrons. A mapping of the extended states over the whole quantum
Hall effect regime shows no floating of extended states as Landau levels cross
near the Fermi level.Comment: 10 pages, 4 figures, submitted to Phys. Rev.
- …