A study on the turbulent transport of an advective nature in the fluid plasma

Advective nature of the electrostatic turbulent flux of plasma energy is studied numerically in a nearly adiabatic state. Such a state is represented by the Hasegawa-Mima equation that is driven by a noise that may model the destabilization due to the phase mismatch of the plasma density and the electric potential. The noise is assumed to be Gaussian and not to be invariant under reflection along a direction $\hat s$. It is found that the flux density induced by such noise is anisotropic: While it is random along $\hat s$, it is not along the perpendicular direction ${\hat s}_\perp$ and the flux is not diffusive. The renormalized response may be approximated as advective with the velocity being proportional to $(k\rho_s)^2$ in the Fourier space $\vec k$

Biosystematics of the genus Dactylosporangium and some other filamentous actinomycetes

This study tested the hypothesis that a relationship exists between taxonomic diversity and antibiotic resistance patterns of filamentous actinomycetes. To this end, 200 filamentous actinomycetes were selectively isolated from a hay meadow soil and assigned to groups based on pigments formed on oatmeal and peptone-yeast extract-iron agars. Forty-four representatives of the colour-groups were assigned to the genera Dactylosporangium, Micromonospora and Streptomyces based on complete 16S rRNA gene sequence analyses. In general, the position of these isolates in the phylogenetic trees correlated with corresponding antibiotic resistance patterns. A significant correlation was found between phylogenetic trees based on 16S rRNA gene and vanHAX gene cluster sequences of nine vancomycin-resistant Streptomyces isolates. These findings provide tangible evidence that antibiotic resistance patterns of filamentous actinomycetes contain information which can be used to design novel media for the selective isolation of rare and uncommon, commercially significant actinomycetes, such as those belonging to the genus Dactylosporangium, a member of the family Micromonosporaceae. A culture-independent, nested PCR procedure based on genus-specific oligonucleotide primers detected the presence of Dactylosporangium strains in 14 out of 21 environmental samples. Clones generated from the 14 positive samples formed novel phyletic lines in the Dactylosporangium 16S rRNA gene tree. Presumptive dactylosporangiae were isolated from 7 of these samples using a medium designed to be selective for members of the genus Dactylosporangium. One hundred and two out of 219 representative presumptive dactylosporangiae were considered to be bona fide members of the genus Dactylosporangium as they gave PCR amplification products with primers specific for this taxon. Representatives of the Dactylsporangium isolates formed distinct phyletic lines in the Dactylosporangium 16S rRNA gene tree were designated as new species, namely Dactylosporangium luridum sp. nov. and Dactylosporangium luteum sp. nov., based on a polyphasic study. Similarly, “Dactylosporangium salmoneum” NRRL B-16294 was validly described as a new species, Dactylosporangium salmoneum sp. nov., nom. rev. In addition, “Dactylosporangium variesporum” NRRL B-16296 was transferred to the genus Saccharothrix as Saccharothrix variisporea corrig. (ex. Tomita et al. 1977) sp. nov., nom. rev. Some of the representative Dactylosporangium isolates inhibited the growth of Bacillus subtilis, Kocuria rhyzophila and Staphylococcus aureus strains, suggesting that novel Dactylosporangium strains might be a rich source of novel antibiotics. Verrucosispora maris AB-18-032, another member of the family Micromonosporaceae, produces atrop-abyssomicin C, the first natural inhibitor of the para-aminobenzoic acid pathway. The self-protective mechanism of this strain was sought by conjugating an atrop-abyssomicin C sensitive Streptomyces griseus strain against a genomic DNA library prepared from V. maris AB-18-032. Seven resultant resistant exconjugants were screened for atrop-abyssomicin C resistance genes using four designed PCR primers. The failure to detect PCR amplification products suggests that the resistance shown by the exconjugants is conferred by mutation within the S. griseus strain or by cloning of unidentified resistance genes from the V. maris strain.EThOS - Electronic Theses Online ServiceNational Institute for International Education of the Korean Government (NIIED) : Newcastle UniversityGBUnited Kingdo

Mitigating Adversarial Vulnerability through Causal Parameter Estimation by Adversarial Double Machine Learning

Adversarial examples derived from deliberately crafted perturbations on visual inputs can easily harm decision process of deep neural networks. To prevent potential threats, various adversarial training-based defense methods have grown rapidly and become a de facto standard approach for robustness. Despite recent competitive achievements, we observe that adversarial vulnerability varies across targets and certain vulnerabilities remain prevalent. Intriguingly, such peculiar phenomenon cannot be relieved even with deeper architectures and advanced defense methods. To address this issue, in this paper, we introduce a causal approach called Adversarial Double Machine Learning (ADML), which allows us to quantify the degree of adversarial vulnerability for network predictions and capture the effect of treatments on outcome of interests. ADML can directly estimate causal parameter of adversarial perturbations per se and mitigate negative effects that can potentially damage robustness, bridging a causal perspective into the adversarial vulnerability. Through extensive experiments on various CNN and Transformer architectures, we corroborate that ADML improves adversarial robustness with large margins and relieve the empirical observation.Comment: Accepted in ICCV 202