Post-Oligarchic Evolution of Protoplanetary Embryos and the Stability of Planetary Systems

We investigate the orbit-crossing time (T_c) of protoplanet systems both with and without a gas-disk background. The protoplanets are initially with equal masses and separation (EMS systems) scaled by their mutual Hill's radii. In a gas-free environment, we find log (T_c/yr) = A+B \log (k_0/2.3). Through a simple analytical approach, we demonstrate that the evolution of the velocity dispersion in an EMS system follows a random walk. The stochastic nature of random-walk diffusion leads to (i) an increasing average eccentricity ~ t^1/2, where t is the time; (ii) Rayleigh-distributed eccentricities (P(e,t)=e/\sigma^2 \exp(-e^2/(2\sigma^2)) of the protoplanets; (iii) a power-law dependence of T_c on planetary separation. As evidence for the chaotic diffusion, the observed eccentricities of known extra solar planets can be approximated by a Rayleigh distribution. We evaluate the isolation masses of the embryos, which determine the probability of gas giant formation, as a function of the dust and gas surface densities.Comment: 15 pages, 13 figures (2 color ones), accepted for publication in Ap

Border is better than distance? Contagious corruption in one belt one road economies

Employing data of one belt one road (OBOR) countries from 2002 to 2013, this study compares the contagious corruption difference between geographic border and distance through the dynamic spatial econometric model. The empirical results not only confirm that corruption in OBOR countries exists under various contagious channels, but also indicate that border effects, serving as contagious channels for corruption, are better than distance effects. The empirical implication is that OBOR countries with a common border tend to possess contagious corruption due to the hosts’ demonstration effect and the convenience of transferring illegal assets. We advise that those OBOR countries should enhance the supervision of cash flow, look for any opportunity of kicking back a portion of the stolen money, and establish a specific task force on corruption

Determination and Improvement of Building Speed in Rapid Freeze Prototyping 514

Rapid freeze prototyping (RFP) is a solid freeform fabrication process that builds an ice part by rapidly freezing water in a layer by layer manner. One advantage of this process is the ability to build ice parts faster than other SFF processes. The factors that affect the speed of contour building and interior filling in RFP are identified. The influence of these factors is analyzed through heat transfer and material flow analyses. A model based on heat transfer analysis is proposed to determine the maximum achievable speed of contour building under stable conditions. Experiments are conducted to validate the performance of the proposed model for determination of building speed.Mechanical Engineerin

Addressing the implementation challenge of the global biodiversity framework

A Global Biodiversity Framework (GBF) is under discussion for the period 2021–2030, which will replace the “Aichi Targets” adopted by the Convention on Biological Diversity (CBD) in 2010. Given the limited success in meeting most of the Aichi Targets, this new framework must adopt a different approach. A key challenge the GBF must address is its implementation at national scales. Four ways this implementation challenge can be addressed include:The framework must move away from numerical targets to pursue positive trends in biodiversity, through adopting a “vectors of change” approach;The framework should be structured to focus on ecosystems and processes;The framework should synergise more extensively with existing biodiversity-relevant global agreements to maximise leverage and reduce overlap of resource use;The framework must adopt a much stronger theory of change than is in the current GBF Draft, to serve as the roadmap governments can use in upscaling their implementation of biodiversity conservation, sustainable use and benefit sharing. Finally, the GBF must become a “learning framework”, committed to facilitating and enabling governments to each meet their specific biodiversity challenges, while sharing back experiences with the global community, leading ultimately to realising the 2050 CBD vision of people living in harmony with nature. © 2020, The Author(s)

Development of genomic SSR and potential EST-SSR markers in Bupleurum chinense DC.

Nineteen genomic SSR markers were developed using inter-simple sequence repeat (ISSR)- suppression PCR technique in Bupleurum chinense DC., a widely used Chinese medicinal plant. A total of 126 alleles were detected across 22 individual plants of B. chinense DC. f. octoradiatum (Bunge) Shan et Sheh, with an average of 3 - 13 alleles per locus. The observed heterozygosity (HO) and the expected heterozygosity (HE) values ranged from 0.23 to 1.00 and from 0.29 to 0.92, respectively. Nine loci deviated from Hardy-Weinberg equilibrium (HWE) (P < 0.05) and eight pairs of loci showed significant linkage disequilibrium (LD) (Fisher’s exact test, P < 0.01). The species transferability of these genomic SSR markers was also detected in seven other Bupleurum species. Eight SSR markers were successfully amplified in all tested species. In addition, forty four EST-SSRs which can be amplified with expected sizes were identified from a B. chinense root cDNA library. The genomic SSR markers and potential EST-SSR markers developed in the present study should be useful for genetic diversity and molecular marker assistant selection breeding research in Bupleurum species

Quenched QCD with domain wall fermions

We report on simulations of quenched QCD using domain wall fermions, where we focus on basic questions about the formalism and its ability to produce expected low energy hadronic physics for light quarks. The work reported here is on quenched $8^3 \times 32$ lattices at $\beta = 5.7$ and 5.85, using values for the length of the fifth dimension between 10 and 48. We report results for parameter choices which lead to the desired number of flavors, a study of undamped modes in the extra dimension and hadron masses.Comment: Contribution to Lattice '98. Presented by R. Mawhinney. 3 pages, 3 figure