Particles-vortex interactions and flow visualization in He4

Recent experiments have demonstrated a remarkable progress in implementing and use of the Particle Image Velocimetry (PIV) and particle tracking techniques for the study of turbulence in He4. However, an interpretation of the experimental data in the superfluid phase requires understanding how the motion of tracer particles is affected by the two components, the viscous normal fluid and the inviscid superfluid. Of a particular importance is the problem of particle interactions with quantized vortex lines which may not only strongly affect the particle motion, but, under certain conditions, may even trap particles on quantized vortex cores. The article reviews recent theoretical, numerical, and experimental results in this rapidly developing area of research, putting critically together recent results, and solving apparent inconsistencies. Also discussed is a closely related technique of detection of quantized vortices negative ion bubbles in He4.Comment: To appear in the J Low Temperature Physic

DES Y3 + KiDS-1000: Consistent cosmology combining cosmic shear surveys

We present a joint cosmic shear analysis of the Dark Energy Survey (DES Y3) and the Kilo-Degree Survey (KiDS-1000) in a collaborative effort between the two survey teams. We find consistent cosmological parameter constraints between DES Y3 and KiDS-1000 which, when combined in a joint-survey analysis, constrain the parameter $S_8 = \sigma_8 \sqrt{\Omega_{\rm m}/0.3}$ with a mean value of $0.790^{+0.018}_{-0.014}$. The mean marginal is lower than the maximum a posteriori estimate, $S_8=0.801$, owing to skewness in the marginal distribution and projection effects in the multi-dimensional parameter space. Our results are consistent with $S_8$ constraints from observations of the cosmic microwave background by Planck, with agreement at the $1.7\sigma$ level. We use a Hybrid analysis pipeline, defined from a mock survey study quantifying the impact of the different analysis choices originally adopted by each survey team. We review intrinsic alignment models, baryon feedback mitigation strategies, priors, samplers and models of the non-linear matter power spectrum.Comment: 38 pages, 21 figures, 15 tables, submitted to the Open Journal of Astrophysics. Watch the core team discuss this analysis at https://cosmologytalks.com/2023/05/26/des-kid

Fundamental molecular techniques for rhizobia

Working with DNA is now a fundamental skill in working with rhizobia. It is necessary for typing strains using PCR methods and for sequencing activities ap¬plied to understanding genomes; their structure, how they function, and their taxonomic position. Nucleic acid purification is the separation of nucleic acids from proteins, cell wall debris and polysaccharide after lysis of cells. For rhizobia, we provide here a num¬ber of commonly used methods for the extraction of genomic and plasmid DNA. Methods for extraction of total RNA are presented in Chapter 13. The CTAB method (Protocol 11.1.1) has been used extensively for extraction of total genom¬ic DNA for DNA sequencing while Protocol 11.1.2 gives higher yields but gener¬ally with slightly lower purity. Plasmid DNA can be differentially displayed using Protocol 11.2.1 for determination of replicon number. This method allows locali¬sation of genes to replicons, confirmation of genome assemblies and identification of genetic changes. The plasmids can subsequently be purified from low melting point gels using GELase (Epicentre, http://www.epibio.com/item.asp?id=297). Protocol 11.2.2 presents a method to recover introduced plasmids from rhizobia (i.e. complementing plasmids) for transformation into Escherichia coli prior to restriction analysis. Protocol 11.2.3 provides an alternative method to the GELase procedure for purifying plasmids but has not been tested as extensively

Specialised genetic techniques for rhizobia

The aim of this chapter is to provide a selection of specialised genetic techniques which are widely used to interrogate gene functions in root nodule bacteria (RNB). The reader is referred to reviews of the applicability of these techniques to understand biological processes occurring in RNB (i.e. Long 1989; Stanley and Cervantes 1991). The techniques presented here cover the ability to randomly mutate genes, select mutants of interest based on their phenotype and identify the gene affected, verify that the gene mutation caused the observed phenotypic defect, examine expression of a target gene, perform genome structural and func¬tional studies and conduct comparative analyses with other RNB