Optimizing Nucleus Size Metrics for Liquid–Solid Nucleation from Transition Paths of Near-Nanosecond Duration

2011 ◽  
Vol 2 (10) ◽  
pp. 1133-1138 ◽  
Author(s):  
Gregg T. Beckham ◽  
Baron Peters
Keyword(s):  
Nucleus Size ◽  
Nanosecond Duration ◽  
Transition Paths ◽  
Solid Nucleation

scholarly journals Activity of the first interstellar comet 2I/Borisov around perihelion: results from Indian observatories

2021 ◽  
Vol 502 (3) ◽  
pp. 3491-3499
Author(s):  
K Aravind ◽  
Shashikiran Ganesh ◽  
Kumar Venkataramani ◽  
Devendra Sahu ◽  
Dorje Angchuk ◽  
...  
Keyword(s):  
Solar System ◽  
Production Rate ◽  
Rate Ratio ◽  
Carbon Chain ◽  
Astronomical Observatory ◽  
Nucleus Size ◽  
Chain Molecules ◽  
Molecular Emission ◽  
Imaging And Spectroscopy ◽  
Gas Ratio

ABSTRACT Comet 2I/Borisov is the first true interstellar comet discovered. Here, we present results from observational programs at two Indian observatories, 2 m Himalayan Chandra Telescope at the Indian Astronomical Observatory, Hanle (HCT) and 1.2 m telescope at the Mount Abu Infrared Observatory (MIRO). Two epochs of imaging and spectroscopy were carried out at the HCT and three epochs of imaging at MIRO. We found CN to be the dominant molecular emission on both epochs, 2019 November 30 and December 22, at distances of rH = 2.013 and 2.031 au, respectively. The comet was inferred to be relatively depleted in Carbon bearing molecules on the basis of low C2 and C3 abundances. We find the production rate ratio, Q(C2)/Q(CN) = 0.54 ± 0.18, pre-perihelion and Q(C2)/Q(CN) = 0.34 ± 0.12 post-perihelion. This classifies the comet as being moderately depleted in carbon chain molecules. Using the results from spectroscopic observations, we believe the comet to have a chemically heterogeneous surface having variation in abundance of carbon chain molecules. From imaging observations, we infer a dust-to-gas ratio similar to carbon chain depleted comets of the Solar system. We also compute the nucleus size to be in the range 0.18 km ≤ r ≤ 3.1 km. Our observations show that 2I/Borisov’s behaviour is analogous to that of the Solar system comets.

scholarly journals A contour property based approach to segment nuclei in cervical cytology images

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Iram Tazim Hoque ◽  
Nabil Ibtehaz ◽  
Saumitra Chakravarty ◽  
M. Saifur Rahman ◽  
M. Sohel Rahman
Keyword(s):  
Pap Smear ◽  
State Of The Art ◽  
Cervical Cytology ◽  
Average Intensity ◽  
Nucleus Size ◽  
Real Dataset ◽  
Art Methods ◽  
Convolution Filter ◽  
Cervical Cells ◽  
Nucleus Segmentation

Abstract Background Segmentation of nuclei in cervical cytology pap smear images is a crucial stage in automated cervical cancer screening. The task itself is challenging due to the presence of cervical cells with spurious edges, overlapping cells, neutrophils, and artifacts. Methods After the initial preprocessing steps of adaptive thresholding, in our approach, the image passes through a convolution filter to filter out some noise. Then, contours from the resultant image are filtered by their distinctive contour properties followed by a nucleus size recovery procedure based on contour average intensity value. Results We evaluate our method on a public (benchmark) dataset collected from ISBI and also a private real dataset. The results show that our algorithm outperforms other state-of-the-art methods in nucleus segmentation on the ISBI dataset with a precision of 0.978 and recall of 0.933. A promising precision of 0.770 and a formidable recall of 0.886 on the private real dataset indicate that our algorithm can effectively detect and segment nuclei on real cervical cytology images. Tuning various parameters, the precision could be increased to as high as 0.949 with an acceptable decrease of recall to 0.759. Our method also managed an Aggregated Jaccard Index of 0.681 outperforming other state-of-the-art methods on the real dataset. Conclusion We have proposed a contour property-based approach for segmentation of nuclei. Our algorithm has several tunable parameters and is flexible enough to adapt to real practical scenarios and requirements.

Homogeneous nucleation in a Poiseuille flow

2021 ◽  
Vol 23 (6) ◽  
pp. 3974-3982
Author(s):  
Fuqian Yang
Keyword(s):  
Poiseuille Flow ◽  
Homogeneous Nucleation ◽  
Critical Nucleus ◽  
Flow Speed ◽  
Nucleus Size ◽  
Average Flow ◽  
Critical Nucleus Size

Variation of the critical nucleus size and the corresponding work of formation with average flow speed at axisymmetric axis.

Trapping Effect on the Kinetic Critical Radius in Nucleation and Growth Processes

2014 ◽  
Vol 790-791 ◽  
pp. 97-102
Author(s):  
Zoltán Erdélyi ◽  
Zoltán Balogh ◽  
Gabor L. Katona ◽  
Dezső L. Beke
Keyword(s):  
Critical Nucleus ◽  
Solid Phase ◽  
Kinetic Monte Carlo ◽  
Mean Field ◽  
Transformation Process ◽  
Nucleus Size ◽  
Critical Nucleus Size ◽  
Acta Mater ◽  
Order Of Magnitude ◽  
The Difference

The critical nucleus size—above which nuclei grow, below dissolve—during diffusion controlled nucleation in binary solid-solid phase transformation process is calculated using kinetic Monte Carlo (KMC). If atomic jumps are slower in an A-rich nucleus than in the embedding B-rich matrix, the nucleus traps the A atoms approaching its surface. It doesn’t have enough time to eject A atoms before new ones arrive, even if it would be favourable thermodynamically. In this case the critical nucleus size can be even by an order of magnitude smaller than expected from equilibrium thermodynamics or without trapping. These results were published in [Z. Erdélyi et al., Acta Mater. 58 (2010) 5639]. In a recent paper M. Leitner [M. Leitner, Acta Mater. 60 (2012) 6709] has questioned our results based on the arguments that his simulations led to different results, but he could not point out the reason for the difference. In this paper we summarize our original results and on the basis of recent KMC and kinetic mean field (KMF) simulations we show that Leitner’s conclusions are not valid and we confirm again our original results.

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