3,691 research outputs found
Combining Multi-Fidelity Modelling and Asynchronous Batch Bayesian Optimization
Bayesian Optimization is a useful tool for experiment design. Unfortunately, the classical, sequential setting of Bayesian Optimization does not translate well into laboratory experiments, for instance battery design, where measurements may come from different sources and their evaluations may require significant waiting times. Multi-fidelity Bayesian Optimization addresses the setting with measurements from different sources. Asynchronous batch Bayesian Optimization provides a framework to select new experiments before the results of the prior experiments are revealed. This paper proposes an algorithm combining multi-fidelity and asynchronous batch methods. We empirically study the algorithm behavior, and show it can outperform single-fidelity batch methods and multi-fidelity sequential methods. As an application, we consider designing electrode materials for optimal performance in pouch cells using experiments with coin cells to approximate battery performance
The LEPR gene is associated with reproductive seasonality traits in Rasa Aragonesa sheep
The aim of this study was to characterize and identify causative polymorphisms in the leptin receptor (LEPR) gene responsible for the seasonal variation of reproductive traits in sheep. Three reproductive seasonality traits were studied: the total days of anoestrous (TDA), the progesterone cycling months (P4CM) and the oestrous cycling months (OCM). In total, 18 SNPs were detected in 33 ewes with extreme values for TDA and OCM. Six SNPs were non-synonymous substitutions and two of them were predicted in silico as deleterious: rs596133197 and rs403578195. These polymorphisms were then validated in 239 ewes. The SNP rs403578195, located in exon 8 and leading to a change of alanine to glycine (Ala284Gly) in the extracellular domain of the protein, was associated with the OCM trait, being the G allele associated with a decrease of 12 percent of the OCM trait. Haplotype analyses also suggested the involvement of other non-synonymous SNP located in exon 20 (rs405459906). This SNP also produces an amino acid change (Lys1069Glu) in the intracellular domain of the protein and segregates independently of rs403578195. These results confirm for the first time the role of the LEPR gene in sheep reproductive seasonality
Phase-field approach to heterogeneous nucleation
We consider the problem of heterogeneous nucleation and growth. The system is
described by a phase field model in which the temperature is included through
thermal noise. We show that this phase field approach is suitable to describe
homogeneous as well as heterogeneous nucleation starting from several general
hypotheses. Thus we can investigate the influence of grain boundaries,
localized impurities, or any general kind of imperfections in a systematic way.
We also put forward the applicability of our model to study other physical
situations such as island formation, amorphous crystallization, or
recrystallization.Comment: 8 pages including 7 figures. Accepted for publication in Physical
Review
Phase-field model for Hele-Shaw flows with arbitrary viscosity contrast. II. Numerical study
We implement a phase-field simulation of the dynamics of two fluids with
arbitrary viscosity contrast in a rectangular Hele-Shaw cell. We demonstrate
the use of this technique in different situations including the linear regime,
the stationary Saffman-Taylor fingers and the multifinger competition dynamics,
for different viscosity contrasts. The method is quantitatively tested against
analytical predictions and other numerical results. A detailed analysis of
convergence to the sharp interface limit is performed for the linear dispersion
results. We show that the method may be a useful alternative to more
traditional methods.Comment: 13 pages in revtex, 5 PostScript figures. changes: 1 reference added,
figs. 4 and 5 rearrange
SNP rs403212791 in exon 2 of the MTNR1A gene is associated with reproductive seasonality in the Rasa aragonesa sheep breed
The aim of this study was to characterize and identify causative SNPs in the MTNR1A gene responsible for the reproductive seasonality traits in the Rasa aragonesa sheep breed. A total of 290 ewes (155, 84 and 51 mature, young and ewe lambs, respectively) from one flock were controlled from January to August. The following three reproductive seasonality traits were considered: the total days of anoestrus (TDA) and the progesterone cycling months (P4CM); both ovarian function seasonality traits based on blood progesterone levels; and the oestrus cycling months (OCM) based on oestrous detection, which indicate behavioural signs of oestrous. We have sequenced the total coding region plus 733 and 251 bp from the promoter and 3'-UTR regions, respectively, from the gene in 268 ewes. We found 9 and 4 SNPs associated with seasonality traits in the promoter (for TDA and P4CM) and exon 2 (for the three traits), respectively. The SNPs located in the gene promoter modify the putative binding sites for various trans-acting factors. In exon 2, two synonymous SNPs affect RFLP sites, rs406779174/RsaI (for the three traits) and rs430181568/MnlI (for OCM), and they have been related with seasonal reproductive activity in previous association studies with other breeds. SNP rs400830807, which is located in the 3'-UTR, was associated with the three traits, but this did not modify the putative target sites for ovine miRNAs according to in silico predictions. Finally, the SNP rs403212791 (NW_014639035.1: g.15099004G > A), which is also associated with the three seasonality phenotypes, was the most significant SNP detected in this study and was a non-synonymous polymorphism, leading a change from an Arginine to a Cysteine (R336C). Haplotype analyses confirmed the association results and showed that the effects found for the seasonality traits were caused by the SNPs located in exon 2. We have demonstrated that the T allele in the SNP rs403212791 in the MNTR1A gene is associated with a lower TDA and higher P4CM and OCM values in the Rasa Aragonesa breed
Phase-Field Formulation for Quantitative Modeling of Alloy Solidification
A phase-field formulation is introduced to simulate quantitatively
microstructural pattern formation in alloys. The thin-interface limit of this
formulation yields a much less stringent restriction on the choice of interface
thickness than previous formulations and permits to eliminate non-equilibrium
effects at the interface. Dendrite growth simulations with vanishing solid
diffusivity show that both the interface evolution and the solute profile in
the solid are well resolved
Single-Electron Spectroscopy
Contains research goals and objectives, reports on four research projects and a list of publications.Joint Services Electronics Program Contract DAAL03-92-C-0001Joint Services Electronics Program Grant DAAH04-95-1-0038National Science Foundation Young Investigator AwardPackard FoundationU.S. Navy - Office of Naval Researc
Phase-field model for Hele-Shaw flows with arbitrary viscosity contrast. I. Theoretical approach
We present a phase-field model for the dynamics of the interface between two
inmiscible fluids with arbitrary viscosity contrast in a rectangular Hele-Shaw
cell. With asymptotic matching techniques we check the model to yield the right
Hele-Shaw equations in the sharp-interface limit and compute the corrections to
these equations to first order in the interface thickness. We also compute the
effect of such corrections on the linear dispersion relation of the planar
interface. We discuss in detail the conditions on the interface thickness to
control the accuracy and convergence of the phase-field model to the limiting
Hele-Shaw dynamics. In particular, the convergence appears to be slower for
high viscosity contrasts.Comment: 17 pages in revtex. changes: 1 reference adde
Is Poverty Decentralising? Quantifying Uncertainty in the Decentralisation of Urban Poverty
In this paper we argue that the recent focus on the suburbanisation of poverty is
problematic because of the ambiguities and inconsistencies in defining suburbia. To
improve transparency, replicability and comparability, we suggest that research on the
geographical changes to the distribution of poverty should focus on three questions: (1)
How centralised is urban poverty? (2) To what extent is it decentralising? (3) Is it
becoming spatially dispersed? With respect to all three questions, the issue of
quantifying uncertainty has been under-researched. The main contribution of the paper
is to provide a practical and robust solution to the problem of inference based on a
Bayesian multivariate conditional autoregressive (CAR) model, made accessible via the
R-software package CARBayes. Our approach can be applied to spatio-temporally
autocorrelated data, and can estimate both levels of and change in global RCIs (relative
centralisation index), local RCIs and dissimilarity indices. We illustrate our method with
an application to Scotland's four largest cities. Our results show that poverty was
centralised in 2011 in Glasgow, Dundee and Aberdeen. Poverty in Edinburgh, however,
was decentralised: non-poor households tend to live closer to the centre than poor
ones, and increasingly so. We also find evidence of statistically significant reductions in
centralisation of poverty in all four cities. To test whether this change is associated with
poverty becoming more dispersed, we estimate changes to evenness and local
decentralisation of poverty, revealing complex patterns of change
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