673 research outputs found
Matrix iterations and Cichon's diagram
Using matrix iterations of ccc posets, we prove the consistency with ZFC of
some cases where the cardinals on the right hand side of Cichon's diagram take
two or three arbitrary values (two regular values, the third one with
uncountable cofinality). Also, mixing this with the techniques in J Symb Log
56(3):795-810, 1991, we can prove that it is consistent with ZFC to assign, at
the same time, several arbitrary regular values on the left hand side of
Cichon's diagram.Comment: 14 pages, 2 figures, article in press for the journal Archive for
Mathematical Logi
Physical paradigm of Life as a generalization of biochemical conception. A Physical law governing life origin and development
The present view of biological phenomena is based on a biomolecular paradigm
that development of living organisms is entirely defined by information stored
in a molecular form as some genetic code. However, new facts and discoveries
indicate that biological phenomena cannot be reduced to a biomolecular realm
alone, but are also governed by mechanisms of other nature. These mechanisms,
acting in tight cooperation with biochemical mechanisms, define life cycles of
individual organisms, and, through this, the origin and evolution of the living
world. Here, we present such a physical mechanism (General growth law), which
represents a new physical law of nature acting at cellular, organ, system and
whole organism levels, directing growth and reproduction together with
biomolecular mechanisms. It imposes uniquely defined constraints on
distribution of nutrients between biomass production and maintenance, thus
defining the composition of biochemical reactions, their change and
irreversibility during the organismal life cycle. Mathematically, this law is
represented by the growth equation. Using this equation, we introduce growth
models and explain division mechanisms for unicellular organisms. High adequacy
of obtained results to experiments proves validity of the General growth law
and of the new physical paradigm of Life based on this law.Comment: 38 pages, 8 figures, 1 table. Analysis of general principles of Life
organization was added, as well as new material and two figures. In
particular, analysis of views of E. Schrodinger, whose famous lectures
contributed to origin of a biochemical paradigm, exposes what assumptions led
him to make inaccurate conclusions. A new, more general physical paradigm of
Life was propose
Propulsion and control of deformable bodies in an ideal fluid
Motivated by considerations of shape changing propulsion of underwater robotic vehicles, this paper analyses the mechanics of deformable bodies operating in an ideal fluid. The application of methods from geometric mechanics results in a compact and insightful formulation of the problem. We develop an explicit formula for the fluid mechanical connection, in terms of the fluid potential function, for this class of systems. The connection can be used to analyze many issues in motion planning and control. The theory is illustrated by application to an amoeba-like device
- …