10,251 research outputs found
Global transposable characteristics in the yeast complete DNA sequence
Global transposable characteristics in the complete DNA sequence of the
Saccharomyces cevevisiae yeast is determined by using the metric representation
and recurrence plot methods. In the form of the correlation distance of
nucleotide strings, 16 chromosome sequences of the yeast, which are divided
into 5 groups, display 4 kinds of the fundamental transposable characteristics:
a short period increasing, a long quasi-period increasing, a long major value
and hardly relevant.Comment: 19 pages, 5 figures, 5 table
Periodic correlation structures in bacterial and archaeal complete genomes
The periodic transference of nucleotide strings in bacterial and archaeal
complete genomes is investigated by using the metric representation and the
recurrence plot method. The generated periodic correlation structures exhibit
four kinds of fundamental transferring characteristics: a single increasing
period, several increasing periods, an increasing quasi-period and almost
noincreasing period. The mechanism of the periodic transference is further
analyzed by determining all long periodic nucleotide strings in the bacterial
and archaeal complete genomes and is explained as follows: both the repetition
of basic periodic nucleotide strings and the transference of non-periodic
nucleotide strings would form the periodic correlation structures with
approximately the same increasing periods.Comment: 23 pages, 6 figures, 2 table
Terminal thermocapillary migration of a droplet at small Reynolds numbers and large Marangoni numbers
In this paper, the overall steady-state momentum and energy balances in the
thermocapillary migration of a droplet at small Reynolds numbers and large
Marangoni numbers are investigated to confirm the quasi-steady state assumption
of the system. The droplet is assumed to have a slight axisymmetric deformation
from a sphere shape. It is shown that under the quasi-steady state assumption,
the total momentum of the thermocapillary droplet migration system at small
Reynolds numbers is conservative. The general solution of the steady momentum
equations can be determined with its parameters depending on the temperature
fields. However, a nonconservative integral thermal flux across the interface
for the steady thermocapillary migration of the droplet at small Reynolds
numbers and large Marangoni numbers is identified. The nonconservative integral
thermal flux indicates that no solutions of the temperature fields exist for
the steady energy equations. The terminal thermocapillary migration of the
droplet at small Reynolds numbers and large Marangoni numbers cannot reach a
steady state and is thus in an unsteady process
Terminal states of thermocapillary migration of a planar droplet at moderate and large Marangoni numbers
In this paper, thermocapillary migration of a planar droplet at moderate and
large Marangoni numbers is investigated analytically and numerically. By using
the dimension-analysis method, the thermal diffusion time scale is determined
as the controlling one of the thermocapillary droplet migration system. During
this time, the whole thermocapillary migration process is fully developed. By
using the front-tracking method, the steady/unsteady states as the terminal
ones at moderate/large Marangoni numbers are captured in a longer time scale
than the thermal diffusion time scale. In the terminal states, the
instantaneous velocity fields in the unsteady migration process at large
Marangoni numbers have the forms of the steady ones at moderate Marangoni
numbers. However, in view of the former instantaneous temperature fields, the
surface tension of the top surface of the droplet gradually becomes the main
component of the driving force on the droplet after the inflection point
appears. It is different from that the surface tension of the bottom surface of
the droplet is the main component of the driving force on the droplet for the
latter ones. The physical mechanism of thermocapillary droplet migration can be
described as the significance of the thermal convection around the droplet is
higher than/just as the thermal conduction across the droplet at large/moderate
Marangoni numbers.Comment: 8 pages, 6 figure
Stability of a hot two-temperature accretion disc with advection
The effects of radial advection and thermal diffusion were considered in
investigating the linear stability of an optically thin, two-temperature
accretion disc. If the disc has only very little advection, we proved that the
thermal instability exists when the disc is geometrically thin. But it dispears
in a geometrically slim disc if the thermal diffusion was considered. Moreover,
if the disc is advection dominated, the thermal instability does not exist. In
addition, we found that the instabilities of inertial-acoustic modes exist only
in a geometrically thin disc or an advection-dominated disc with low Mach
number, whereas the Lightman & Eardley viscous instability always dispears in a
two-temperature disc. A simple comparison also showed that an optically thin,
bremsstrahlung cooling dominated disc is generally more thermally unstable than
a two-temperature disc if it is not advection-dominated.Comment: 12 pages, LaTeX file, 3 figures, accepted for publication in MNRAS.
Revised with a few important references added and several inaccurate
references correcte
Environmental Regulation and Productivity Growth: A Study of the APEC Economies
Environmental regulation has become more and more important in policy making among the world economies. How has it affected productivity growth and hence economic growth? The answer to this question is either controversial or yet to be explored in many cases. The objective of this paper is to present a case study of 17 Asian Pacific Economic Cooperation (APEC) economies. A directional distance function approach is employed to estimate output-oriented Malmquist-Luenberger productivity indices. The latter are in turn decomposed into efficiency changes and technological progress. Work in this paper differs from the existing literature by taking into consideration of the impact of environmental regulation on productivity growth. Three scenarios are modeled, ie. no control on CO2 emissions (unregulated), maintaining current emission level and a partial reduction of emissions. In general, it is found that the rates of productivity growth incorporating CO2 as an undesirable output are slightly higher than those estimated following the traditional method. Furthermore, the causes of productivity changes are also investigated in this paper.Technical efficiency, technological progress, total factor productivity, directional distance functions, Malmquist–Luenberger index, DEA
System Dynamics Model of Knowledge Acquisition via E-Learning of SNS Oriented Knowledge Community in Enterprise
To explore the dynamics mechanism for knowledge acquisition via E-Learning of SNS (Social Network Service) knowledge community in enterprise, so that strategy forknowledge community management can be proposed accordingly. Firstly, elements of knowledge acquisition via E-Learning in knowledge community are analyzed. Secondly,causal loop diagrams are made to make system analysis. Thirdly system dynamics model is established to describe development and changes of knowledge acquisition bysystem dynamics modeling tools. Then sensitivity analysis is made to explore the influences of parameters including, network size, E-Learning experience, knowledgedemand and knowledge acquisition cost. By using system dynamics and sensitivity analysis, we can exploit the dynamic mechanism of knowledge acquisition via E-Learningof SNS oriented knowledge community in enterprise
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