68,469 research outputs found
Criticality and Condensation in a Non-Conserving Zero Range Process
The Zero-Range Process, in which particles hop between sites on a lattice
under conserving dynamics, is a prototypical model for studying real-space
condensation. Within this model the system is critical only at the transition
point. Here we consider a non-conserving Zero-Range Process which is shown to
exhibit generic critical phases which exist in a range of creation and
annihilation parameters. The model also exhibits phases characterised by
mesocondensates each of which contains a subextensive number of particles. A
detailed phase diagram, delineating the various phases, is derived.Comment: 15 pages, 4 figure, published versi
Symmetry relations in chemical kinetics arising from microscopic reversibility
It is shown that the kinetics of time-reversible chemical reactions having
the same equilibrium constant but different initial conditions are closely
related to one another by a directly measurable symmetry relation analogous to
chemical detailed balance. In contrast to detailed balance, however, this
relation does not require knowledge of the elementary steps that underlie the
reaction, and remains valid in regimes where the concept of rate constants is
ill-defined, such as at very short times and in the presence of low activation
barriers. Numerical simulations of a model of isomerization in solution are
provided to illustrate the symmetry under such conditions, and potential
applications in protein folding-unfolding are pointed out.Comment: 4 pages, 1 figure, accepted to Phys Rev Let
Rules for transition rates in nonequilibrium steady states
Just as transition rates in a canonical ensemble must respect the principle
of detailed balance, constraints exist on transition rates in driven steady
states. I derive those constraints, by maximum information-entropy inference,
and apply them to the steady states of driven diffusion and a sheared lattice
fluid. The resulting ensemble can potentially explain nonequilibrium phase
behaviour and, for steady shear, gives rise to stress-mediated long-range
interactions.Comment: 4 pages. To appear in Physical Review Letter
Nonequilibrium phase transition in a non integrable zero-range process
The present work is an endeavour to determine analytically features of the
stationary measure of a non-integrable zero-range process, and to investigate
the possible existence of phase transitions for such a nonequilibrium model.
The rates defining the model do not satisfy the constraints necessary for the
stationary measure to be a product measure. Even in the absence of a drive,
detailed balance with respect to this measure is violated. Analytical and
numerical investigations on the complete graph demonstrate the existence of a
first-order phase transition between a fluid phase and a condensed phase, where
a single site has macroscopic occupation. The transition is sudden from an
imbalanced fluid where both species have densities larger than the critical
density, to a critical neutral fluid and an imbalanced condensate
Infrared Observations of novae in the SOFIA era
Classical novae inject chemically enriched gas and dust into the local
inter-stellar medium (ISM). Abundances in the ejecta can be deduced from
infrared (IR) forbidden line emission. IR spectroscopy can determine the
mineralogy of grains that grow in nova ejecta. We anticipate the impact that
NASA's new Stratospheric Observatory for Infrared Astronomy (SOFIA) will have
on future IR studies of novae.Comment: To appear in the proceedings of "Physics of Evolved Stars 2015 - A
conference dedicated to the memory of Olivier Chesneau
The circumstellar dust of "Born-Again" stars
We describe the evolution of the carbon dust shells around Very Late Thermal
Pulse (VLTP) objects as seen at infrared wavelengths. This includes a 20-year
overview of the evolution of the dust around Sakurai's object (to which Olivier
made a seminal contribution) and FG Sge. VLTPs may occur during the endpoint of
as many as 25% of solar mass stars, and may therefore provide a glimpse of the
possible fate of the Sun.Comment: To appear in the proceedings of "Physics of Evolved Stars 2015 - A
conference dedicated to the memory of Olivier Chesneau
Genetic parameters for animal mortality in pasture-based, seasonal-calving dairy and beef herds
peer-reviewedIn the absence of informative health and welfare phenotypes, breeding for reduced animal mortality could improve overall health and welfare, provided genetic variability in animal mortality exists. The objective of the present study was to estimate genetic (and other) variance components for animal mortality in pasture-based, seasonal-calving dairy and beef herds across multiple life stages as well as to quantify the genetic relationship in mortality among life stages. National mortality records were available for all cattle born in the Republic of Ireland. Cattle were grouped into three life stages based on age (0 to 30 days, 31 to 365 days, 366 to 1095 days) whereas females with ≥1 calving event were also grouped into five life stages, based on parity number (1, 2, 3, 4, and 5), considering both the initial 60 days of lactation and a cow's entire lactation period, separately. The mean mortality prevalence ranged from 0.70 to 5.79% in young animals and from 0.53 to 3.86% in cows. Variance components and genetic correlations were estimated using linear mixed models using 21,637 to 100,993 records. Where heritability estimates were different from zero, direct heritability estimates for mortality in young animals (≤1095 days) ranged from 0.006 to 0.040, whereas the genetic standard deviation ranged from 0.015 to 0.034. The contribution of a maternal genetic effect to mortality in young animals was evident up to 30 days of age in dairy herds, but this was only the case in preliminary analysis of stillbirths in beef herds. Based on the estimated genetic standard deviation in the present study, the incidence of mortality in young animals could be reduced through breeding by up to 3.4 percentage units per generation. For cows, direct heritability estimates for mortality, where different from zero, ranged from 0.003 to 0.049. The genetic standard deviation for mortality in cows ranged from 0.005 to 0.016 during the initial 60 days of lactation and ranged from 0.011 to 0.032 during the cow's entire lactation. Genetic correlations among the age groups as well as between the age groups and cow parities had high standard errors. Genetic correlations among the cow parities were moderate to strongly positive (ranging from 0.66 to 0.99) and mostly different from zero. Results from the present study can be used to inform genetic evaluations for mortality in young animals and in cows as well as the potential genetic gain achievable
Welding of precipitation-hardening stainless steels
Welding of precipitation hardening stainless steel
Condensation phase transition in nonlinear fitness networks
We analyze the condensation phase transitions in out-of-equilibrium complex
networks in a unifying framework which includes the nonlinear model and the
fitness model as its appropriate limits. We show a novel phase structure which
depends on both the fitness parameter and the nonlinear exponent. The
occurrence of the condensation phase transitions in the dynamical evolution of
the network is demonstrated by using Bianconi-Barabasi method. We find that the
nonlinear and the fitness preferential attachment mechanisms play important
roles in formation of an interesting phase structure.Comment: 6 pages, 5 figure
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