316 research outputs found
Master crossover behavior of parachor correlations for one-component fluids
The master asymptotic behavior of the usual parachor correlations, expressing
surface tension as a power law of the density difference
between coexisting liquid and vapor, is analyzed for a
series of pure compounds close to their liquid-vapor critical point, using only
four critical parameters , , and ,
for each fluid.
... The main consequences of these theoretical estimations are discussed in
the light of engineering applications and process simulations where parachor
correlations constitute one of the most practical method for estimating surface
tension from density and capillary rise measurements
Analytical distributions for stochastic gene expression
Gene expression is significantly stochastic making modeling of genetic
networks challenging. We present an approximation that allows the calculation
of not only the mean and variance but also the distribution of protein numbers.
We assume that proteins decay substantially slower than their mRNA and confirm
that many genes satisfy this relation using high-throughput data from budding
yeast. For a two-stage model of gene expression, with transcription and
translation as first-order reactions, we calculate the protein distribution for
all times greater than several mRNA lifetimes and thus qualitatively predict
the distribution of times for protein levels to first cross an arbitrary
threshold. If in addition the promoter fluctuates between inactive and active
states, we can find the steady-state protein distribution, which can be bimodal
if promoter fluctuations are slow. We show that our assumptions imply that
protein synthesis occurs in geometrically distributed bursts and allows mRNA to
be eliminated from a master equation description. In general, we find that
protein distributions are asymmetric and may be poorly characterized by their
mean and variance. Through maximum likelihood methods, our expressions should
therefore allow more quantitative comparisons with experimental data. More
generally, we introduce a technique to derive a simpler, effective dynamics for
a stochastic system by eliminating a fast variable.Comment: Supplementary information can be found on PNAS websit
Virtual integration of laboratories over long distance for real-time co-simulation of power systems
© 2016 IEEE. The interest in the virtual integration of hardware and software assets located at geographically dispersed locations, although not new, has spiked recently. However, realizing joint real-time simulation in connected laboratories is posing new challenges. This paper discusses the generalized requirements of a framework for the virtual integration of laboratories and presents the architecture of the platform that integrates two real-time digital simulators (RTDS located at ACS, RWTH Aachen University, Germany, and OPAL-RT at Politecnico di Torino, Italy). The platform enables remote and online monitoring of the entire interconnected system which is a step towards developing Simulation as a Service concept. The application of this platform for real-time co-simulation of interconnected transmission and distribution systems is demonstrated
The plasma boundary in Single Helical Axis RFP plasmas
Single Helical Axis (SHAx) states obtained in high current reversed field
pinch (RFP) plasmas display, aside from a dominant mode in the m=1 spectrum,
also a dominant m=0 mode, with the same toroidal mode number as the m=1 one.
The two modes have a fixed phase relationship. The island chain created by the
m=0 mode across the reversal surface gives rise, at shallow reversal of the
toroidal field, to an X-point structure which separates the last closed flux
surface from the first wall, creating a divertor-like configuration. The
plasma-wall interaction is found to be related to the connection length of the
field lines intercepting the wall, which displays a pattern modulated by the
dominant mode toroidal periodicity. This configuration, which occurs only for
shallow toroidal field reversal, could be exploited to realize an island
divertor in analogy to stellarators.Comment: 12 pages, 9 figures Submitted to Nuclear Fusio
Master singular behavior for the Sugden factor of the one-component fluids near their gas-liquid critical point
We present the master (i.e. unique) behavior of the squared capillary length
- so called the Sudgen factor-, as a function of the temperature-like field
along the critical isochore, asymptotically close to the gas-liquid critical
point of twenty (one component) fluids. This master behavior is obtained using
the scale dilatation of the relevant physical fields of the one-component
fluids. The scale dilatation introduces the fluid-dependent scale factors in a
manner analog with the linear relations between physical fields and scaling
fields needed by the renormalization theory applied to the Ising-like
universality class. The master behavior for the Sudgen factor satisfies
hyperscaling and can be asymptotically fitted by the leading terms of the
theoretical crossover functions for the correlation length and the
susceptibility in the homogeneous domain recently obtained from massive
renormalization in field theory. In the absence of corresponding estimation of
the theoretical crossover functions for the interfacial tension, we define the
range of the temperature-like field where the master leading power law can be
practically used to predict the singular behavior of the Sudgen factor in
conformity with the theoretical description provided by the massive
renormalization scheme within the extended asymptotic domain of the
one-component fluid "subclass"
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The Resonance of Resonance: Critical Theory as a Sociology of World-Relations?
The main purpose of this paper is to examine Hartmut Rosa’s account of “resonance.” To this end, the analysis is divided into four parts. The first part focuses on the concept of resonance, including Rosa’s differentiation between horizontal, diagonal, and vertical “axes of resonance” and their role in the construction of different “world-relations.” The second part centers on the concept of alienation, notably the degree to which it constitutes an integral element of modern life forms and, in a larger sense, of the human condition. The third part grapples with the dialectic of resonance and alienation, shedding light on the assumption that they are antithetical to each other, while contending that their in-depth study provides normative parameters to distinguish between “the good life” and “the bad life.” The final part scrutinizes Rosa’s attempt to defend his outline of a sociological theory of resonance against objections raised by his critics and comprises a point-by-point assessment of his plea for a resonance-focused sociology of world-relations. The paper concludes by suggesting that, notwithstanding its limitations, Rosa’s approach represents one of the most promising developments in twenty-first-century critical theory
Transcriptome Kinetics Is Governed by a Genome-Wide Coupling of mRNA Production and Degradation: A Role for RNA Pol II
Transcriptome dynamics is governed by two opposing processes, mRNA production and degradation. Recent studies found that changes in these processes are frequently coordinated and that the relationship between them shapes transcriptome kinetics. Specifically, when transcription changes are counter-acted with changes in mRNA stability, transient fast-relaxing transcriptome kinetics is observed. A possible molecular mechanism underlying such coordinated regulation might lay in two RNA polymerase (Pol II) subunits, Rpb4 and Rpb7, which are recruited to mRNAs during transcription and later affect their degradation in the cytoplasm. Here we used a yeast strain carrying a mutant Pol II which poorly recruits these subunits. We show that this mutant strain is impaired in its ability to modulate mRNA stability in response to stress. The normal negative coordinated regulation is lost in the mutant, resulting in abnormal transcriptome profiles both with respect to magnitude and kinetics of responses. These results reveal an important role for Pol II, in regulation of both mRNA synthesis and degradation, and also in coordinating between them. We propose a simple model for production-degradation coupling that accounts for our observations. The model shows how a simple manipulation of the rates of co-transcriptional mRNA imprinting by Pol II may govern genome-wide transcriptome kinetics in response to environmental changes
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