Electron and Ion Energization in Relativistic Plasma Turbulence.

Electron and ion energization (i.e., heating and nonthermal acceleration) is a fundamental, but poorly understood, outcome of plasma turbulence. In this work, we present new results on this topic from particle-in-cell simulations of driven turbulence in collisionless, relativistic electron-ion plasma. We focus on temperatures such that ions (protons) are subrelativistic and electrons are ultrarelativistic, a regime relevant for high-energy astrophysical systems such as hot accretion flows onto black holes. We find that ions tend to be preferentially heated, gaining up to an order of magnitude more energy than electrons, and propose a simple empirical formula to describe the electron-ion energy partition as a function of the ratio of electron-to-ion gyroradii (which in turn is a function of initial temperatures and plasma beta). We also find that while efficient nonthermal particle acceleration occurs for both species in the ultrarelativistic regime, nonthermal electron populations are diminished with decreasing temperature whereas nonthermal ion populations are essentially unchanged. These results have implications for modeling and interpreting observations of hot accretion flows.

Kinetic Turbulence in Relativistic Plasma: From Thermal Bath to Nonthermal Continuum.

We present results from particle-in-cell simulations of driven turbulence in magnetized, collisionless, and relativistic pair plasmas. We find that the fluctuations are consistent with the classical k_{⊥}^{-5/3} magnetic energy spectrum at fluid scales and a steeper k_{⊥}^{-4} spectrum at sub-Larmor scales, where k_{⊥} is the wave vector perpendicular to the mean field. We demonstrate the development of a nonthermal, power-law particle energy distribution f(E)∼E^{-α}, with an index α that decreases with increasing magnetization and increases with an increasing system size (relative to the characteristic Larmor radius). Our simulations indicate that turbulence can be a viable source of energetic particles in high-energy astrophysical systems, such as pulsar wind nebulae, if scalings asymptotically become insensitive to the system size.

Single locus HLA sequencing with the nanopore technology for HLA disease association diagnosis.

Associations between HLA genotype and disease susceptibility encompass almost all the classic HLA loci. The level of typing resolution enabling a correct identification of an HLA disease susceptibility gene depends on the disease itself and/or on the accumulated knowledge about the molecular involvement of the HLA allele(s) engaged. Therefore, the application of Next Generation Sequencing technologies to HLA disease association, which would improve typing resolution, could prove useful to better understand disease severity. In the present study, we tested a nanopore sequencing approach developed by Omixon Biocomputing Ltd, dedicated to on-demand locus typing for HLA and disease, as an alternative to the conventional widely used sequence specific oligoprobe (SSO) approach. A total of 145 DNA samples used in routine diagnosis by SSO were retrospectively analyzed with nanopore technology, for HLA-A*02 immunotherapy decision for A*29, B*27, B*51, B*57 identification in class I, and DRB1, DQA1, and DQB1 for bullous dermatosis, rheumatoid arthritis, diabetes, and celiac disease requests in class II. Each locus was typed in a separate experiment, except for DQB1 and DQA1, which were analyzed together. Concordance between typings reached 100% for all the loci tested. Ambiguities by nanopore were only found for missing exon coverage. This approach was found to be very well adapted to the routine flow imposed by the SSO technique. This study illustrates the use of the new NanoTYPE MONO kit for single locus HLA sequencing for HLA and disease association diagnosis.

Two-field resolution on-call HLA typing for deceased donors using nanopore sequencing.

The current practice of HLA genotyping in deceased donors poses challenges due to limited resolution within time constraints. Nevertheless, the assessment of compatibility between anti-HLA sensitized recipients and mismatched donors remains a critical medical need, particularly when dealing with allele-specific (second field genotyping level) donor-specific antibodies. In this study, we present a customized protocol based on the NanoTYPE® HLA typing kit, employing the MinION® sequencer, which enables rapid HLA typing of deceased donors within a short timeframe of 3.75 h on average at a three-field resolution with almost no residual ambiguities. Through a prospective real-time analysis of HLA typing in 18 donors, we demonstrated the efficacy and precision of our nanopore-based method in comparison to the conventional approach and without delaying organ allocation. Indeed, this duration was consistent with the deceased donor organ donation procedure leading to organ allocation via the French Biomedicine Agency. The improved resolution achieved with our protocol enhances the security of organ allocation, particularly benefiting highly sensitized recipients who often present intricate HLA antibody profiles. By overcoming technical challenges and providing comprehensive genotyping data, this approach holds the potential to significantly impact deceased donor HLA genotyping, thereby facilitating optimal organ allocation strategies.

A rapid radiochemical purity testing method for 99mTc-tetrofosmin.

UNLABELLED: The standard radiochemical purity (RCP) testing method for (99m)Tc-tetrofosmin as described in the package insert requires extensive time (20-30 min) and considerable skill to achieve accurate results. Additionally, the instant thin-layer chromatography strip impregnated with silica gel (2x20 cm) used in the standard method will not be commercially available in the future. The purpose of this study was to evaluate whether a method developed by our laboratory for RCP testing of (99m)Tc-sestamibi could also be used as an alternative method for the RCP assay of (99m)Tc-tetrofosmin. METHODS: The alternative RCP testing system consisted of a precut paper strip (1x8.5 cm) from solvent saturation pads (Pall Corp.) as the stationary phase, with 1:1 chloroform:tetrahydrofuran used as the mobile phase. To validate the reliability of the alternative method, RCP values from 17 kit preparations were compared with the 2 methods. Kits were reconstituted according to the package insert instructions, and 4 additions of (99m)Tc-sodium pertechnetate were purposely added to create trials with RCP values below the accepted limit of 90% purity. RESULTS: Two hundred four trials (100 of which were replicated) were run from the 17 kit preparations. Sixty-four (31%) of the 204 trials were below 90% purity based on the standard method. The overall agreement between the standard and alternative methods was 94% (192/204). The sensitivity of the alternative method for unacceptable RCP limits was 86% (55/64), and the specificity for acceptable RCP values was 98% (137/140). The agreement between the replicated trials of the alternative method was 99% (99/100), and for the standard method it was 92% (92/100). CONCLUSION: The standard method proved to be a much slower method and requires much more precision and attention. The alternative method is much faster, is easier, requires less attention to the solvent-development process, and can be used for RCP testing of both (99m)Tc-tetrofosmin and (99m)Tc-sestamibi. Furthermore, the stationary phase is much more readily available, is not moisture-sensitive, and is less susceptible to operator technique. Our method is accurate in determining the RCP value of (99m)Tc-tetrofosmin and is a better RCP testing method for (99m)Tc-tetrofosmin.

The tiny eukaryote Ostreococcus provides genomic insights into the paradox of plankton speciation.

The smallest known eukaryotes, at approximately 1-mum diameter, are Ostreococcus tauri and related species of marine phytoplankton. The genome of Ostreococcus lucimarinus has been completed and compared with that of O. tauri. This comparison reveals surprising differences across orthologous chromosomes in the two species from highly syntenic chromosomes in most cases to chromosomes with almost no similarity. Species divergence in these phytoplankton is occurring through multiple mechanisms acting differently on different chromosomes and likely including acquisition of new genes through horizontal gene transfer. We speculate that this latter process may be involved in altering the cell-surface characteristics of each species. In addition, the genome of O. lucimarinus provides insights into the unique metal metabolism of these organisms, which are predicted to have a large number of selenocysteine-containing proteins. Selenoenzymes are more catalytically active than similar enzymes lacking selenium, and thus the cell may require less of that protein. As reported here, selenoenzymes, novel fusion proteins, and loss of some major protein families including ones associated with chromatin are likely important adaptations for achieving a small cell size.